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Microplastics (MPs) and antibiotics often coexist in complex marine environments, yet their combined detrimental effects on marine organisms remain underexplored. This study evaluated the effects of polyethylene microplastics (PE, 200 μg/L) and sulfamethoxazole (SMX, 50 μg/L), both individually and in combination, on Mytilus galloprovincialis. The exposure lasted 6 days, followed by a 6-day recovery period. Bioaccumulation, DNA damage, pollutants transport/metabolism related responses and responding alterations of mitogen-activated protein kinase (MAPK) signaling pathway were detected in gills and digestive glands. Bioaccumulation of SMX/PE in mussels occurred in a tissue-specific manner, co-exposure altered SMX contents in investigated tissues. Co-exposure did not induce extra DNA damage, elevated DNA damage was alleviated during the recovery period in all treated groups. The exposure of SMX/PE exerted different alterations in pollutants transport/metabolism related responses, characterized by multixenobiotic resistance and relative expression of key genes (cytochrome P450 monooxygenase, glutathione S-transferase, ATP-binding cassette transporters). Key molecules (p38 MAPK, c-jun N-terminal kinase, extracellular regulated protein kinase, nuclear factor-κB and tumor protein p53) in MAPK signaling pathway were activated at transcriptional and translational levels after SMX/PE and co-exposure. Co-regulation between MAPK members and pollutants transport/metabolism related factors was revealed, suggesting MAPK signaling pathway served as a regulating hub in exposed mussels to conquer SMX/PE stress. Overall, this study provides new insights on SMX/PE induced health risks in marine mussels and potential mechanism through MAPK cascades regulation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The mitogen-activated protein kinase (MAPK) cascade (MAPKKK-MAPKK-MAPK) plays a critical role in biotic and abiotic stress responses and abscisic acid (ABA) signalling. A previous study has shown that the ABA-activated MKK1-MPK1 cascade is essential in regulating ABA response and stress tolerance in rice. However, the specific MAPKKK upstream of the MKK1-MPK1 cascade in ABA signalling remains unknown. Here, we identified that MAPKKK28, a previously uncharacterized member of the rice MEKK family, is involved in regulating ABA responses, including seed germination, root growth, stomatal closure, and the tolerance to oxidative stress and osmotic stress. We found that MAPKKK28 directly interacts with and phosphorylates MKK1. Further analysis indicated that the activation of both MKK1 and MPK1 depends on MAPKKK28 in ABA signalling. Genetic analysis revealed that MAPKKK28 functions upstream of the MKK1-MPK1 cascade to positively regulate ABA responses and enhance tolerance to oxidative and osmotic stress. These results not only reveal a new complete MAPK cascade in plants but also uncover its importance in ABA signalling., (© 2024 John Wiley & Sons Ltd.)

Candida glabrata is an important and increasingly common pathogen of humans, particularly in immunocompromised hosts. Despite this, little is known about how this fungus causes disease. Here, we applied RNA sequencing and an in vivo invasive infection model to identify the attributes that allow this organism to infect hosts. Fungal transcriptomes show a dramatic increase in the expression of Fus3 and Kss1, two mitogen-activated protein kinases (MAPKs), during invasive infection. We further demonstrate that they are both highly induced under a combination of serum and high CO 2 conditions. Deletion of both FUS3 and KSS1 , but neither gene alone, results in a reduced fungal burden in organs, as well as in the gastrointestinal tract in the DSS (Dextran Sulfate Sodium)-induced colitis model. Similarly, the defect in persistence in macrophages and attenuated adhesion to epithelial cells are observed when FUS3 and KSS1 are both disrupted. The fus3 kss1 double mutant also displays defects in the induction of virulence attributes such as genes required for iron acquisition and adhesion and in the anti-fungal drug tolerance. The putative downstream transcription factors Ste12 (1), Ste12 (2), Tec1, and Tec2 are found to be involved in the regulation of these virulence attributes. Collectively, our study indicates that an evolutionary conserved MAPK pathway, which regulates mating and filamentous growth in Saccharomyces cerevisiae , is critical for C. glabrata pathogenicity., Importance: The MAPK signaling pathway, mediated by closely related kinases Fus3 and Kss1, is crucial for controlling mating and filamentous growth in Saccharomyces cerevisiae , but this pathway does not significantly impact hyphal development and pathogenicity in Candida albicans , a commensal-pathogenic fungus of humans. Furthermore, deletion of Cpk1, the ortholog of Fus3 in pathogenic fungus Cryptococcus neoformans , has no effect on virulence. Here, we demonstrate that the MAPK pathway is crucial for the pathogenicity of Candida glabrata , a fungus that causes approximately one-third of cases of hematogenously disseminated candidiasis in the United States. This pathway regulates multiple virulence attributes including the induction of iron acquisition genes and adhesins, as well as persistence in macrophages and organs. Our work provides insights into C. glabrata pathogenesis and highlights an example in which regulatory rewiring of a conserved pathway confers a virulent phenotype in a pathogen., Competing Interests: The authors declare no conflict of interest.

Trichosporon asahii, a dimorphic fungus, causes bloodstream infections in immunocompromised patients with neutropenia. Biofilms are formed on the surfaces of medical devices such as catheters as T. asahii transitions morphologically from yeast to hyphae in the host environment. Oxidative stress tolerance and morphological changes of T. asahii are regulated by Hog1, a mitogen-activated protein kinase. The role of Hog1 in the biofilm formation by T. asahii, however, has remained unknown. In the present study, we demonstrated that a hog1 gene-deficient T. asahii mutant formed excess biofilm under a rich medium in vitro, but did not form biofilm in an in vivo evaluation system using silkworms. The hog1 gene-deficient T. asahii mutant formed a greater amount of biofilm than the parent strain in vitro. Under an oxidative stress condition in vitro, however, lower amounts of biofilm were formed by the hog1 gene-deficient T. asahii mutant than by the parent strain. In an in vivo evaluation system using silkworms, lower amounts of biofilm were formed by the hog1 gene-deficient T. asahii mutant than by the parent strain. Our findings suggest that Hog1 regulates biofilm formation by T. asahii in response to host environmental conditions, including oxidative stress., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Candida auris , a multidrug-resistant human fungal pathogen, was first identified in 2009 in Japan. Since then, systemic C. auris infections have now been reported in more than 50 countries, with mortality rates of 30%-60%. A major contributing factor to its high inter- and intrahospital clonal transmission is that C. auris, unlike most Candida species, displays unique skin tropism and can stay on human skin for a prolonged period. However, the molecular mechanisms responsible for C. auris skin colonization, intradermal persistence, and systemic virulence are poorly understood. Here, we report that C. auris Hog1 mitogen-activated protein kinase is essential for efficient skin colonization, intradermal persistence as well as systemic virulence. RNA-seq analysis of wild-type parental and hog1 Δ mutant strains revealed marked downregulation of genes involved in processes such as cell adhesion, cell wall rearrangement, and pathogenesis in hog1 Δ mutant compared to the wild-type parent. Consistent with these data, we found a prominent role for Hog1 in maintaining cell wall architecture, as the hog1 Δ mutant demonstrated a significant increase in cell-surface β-glucan exposure and a concomitant reduction in chitin content. Additionally, we observed that Hog1 was required for biofilm formation in vitro and fungal survival when challenged with primary murine macrophages and neutrophils ex vivo . Collectively, these findings have important implications for understanding the C. auris skin adherence mechanisms and penetration of skin epithelial layers preceding bloodstream infections., Importance: Candida auris is a World Health Organization fungal priority pathogen and an urgent public health threat recognized by the Centers for Disease Control and Prevention. C. auris has a unique ability to colonize human skin. It also persists on abiotic surfaces in healthcare environments for an extended period of time. These attributes facilitate the inter- and intrahospital clonal transmission of C. auris . Therefore, understanding C. auris skin colonization mechanisms is critical for infection control, especially in hospitals and nursing homes. However, despite its profound clinical relevance, the molecular and genetic basis of C. auris skin colonization mechanisms are poorly understood. Herein, we present data on the identification of the Hog1 MAP kinase as a key regulator of C. auris skin colonization. These findings lay the foundation for further characterization of unique mechanisms that promote fungal persistence on human skin., Competing Interests: The authors declare no conflict of interest.

Aging is a highly complex process and one of the largest risk factors for many chronic diseases. Aronia melanocarpa (AM) is rich in bioactive phytochemicals with antioxidant, anti-inflammatory, and anticancer properties. However, little is known about its effects on aging. The objective of this study was to evaluate the effects of AM extract on lifespan and health-span using Caenorhabditis elegans as a representative model. The mechanisms of its effects were explored using transcriptomics and untargeted metabolomics. Results showed that the lifespan of C. elegans was significantly extended by 22.2% after high-dose AM treatment. AM improved the behavior and physiological functions of C. elegans by increasing the pharyngeal pumping rate, decreasing lipofuscin accumulation and the reactive oxygen species level, enhancing resistance to oxidative stress, and increasing the activities of superoxide dismutase and catalase. Transcriptome analysis showed that the pmk-1 gene (mitogen-activated protein kinase 1), which is involved in the MAPK signaling pathway, was the gene with the largest fold change after AM intervention. However, in the C. elegans pmk-1(km25) mutant, the beneficial effect of AM in improving nematode senescence disappeared. An untargeted metabolomics study showed that the levels of 4-hydroxyproline, rhamnose, and cysteine were increased after AM supplementation, and their extending effect on the lifespan and health-span of C. elegans were partly dependent on the pmk-1 gene. In conclusion, our results revealed that AM can promote the lifespan and health-span of C. elegans via the PMK-1 pathway, highlighting the potential of AM as a dietary supplement to delay aging.

Global warming has significantly impacted agriculture, particularly in animal husbandry and aquaculture industry. Rising ocean temperatures due to global warming are severely affecting shellfish production, necessitating an understanding of how shellfish cope with thermal stress. The mitogen-activated protein kinases (MAPK) signaling pathway plays a crucial role in cell growth, differentiation, adaptation to environmental stress, inflammatory response, and managing high temperature stress. To investigate the function of MAPKs in bay scallops, a comparative genomics and bioinformatics approach identified three MAPK genes: AiERK, Aip38, and AiJNK. Structural and phylogenetic analyses of these proteins were conducted to determine their evolutionary relationships. Spatiotemporal expression patterns were examined at different developmental stages and in various tissues of healthy adult scallops. Additionally, the expression regulation of these genes was studied in selected tissues (hemocyte, gill, heart, mantle) following exposure to high temperatures (32 °C) for different durations (0 h, 6 h, 12 h, 24 h, 3 d, 6 d, 10 d). The spatiotemporal expressions of AiMAPKs were ubiquitous, with significant increases in AiERK expression observed at the umbo larval stage (3.09-fold), while Aip38 and AiJNK were identified as potential maternal effect genes. In adult scallops, different gene expression patterns of AiMAPKs were observed across eight tissues, with high expressions in the foot and gill, and lower expressions in the striated muscle. Following high temperature stress, AiMAPKs expressions in the gill and mantle were mainly up-regulated, while in the hemocyte, they were primarily down-regulated. These findings indicate time- and tissue-dependent expression patterns with functional allocation in response to different thermal durations. This study enhances our understanding of the function and evolution of AiMAPKs genes in shellfish and provides a theoretical basis for elucidating the energy regulation mechanism of bay scallops in response to high temperature stress., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

CDKs are the master regulator of cell division and their activity is controlled by the regulatory subunit cyclins and phosphorylation by the CAKs. However, the role of MAP kinases in regulating plant cell cycle or CDKs have not been explored. Here, we report that the MAP kinases OsMPK3, OsMPK4, and OsMPK6 physically interact and phosphorylate OsCDKD and its regulatory subunit OsCYCH in rice. MAP kinases phosphorylate CDKD at Ser-168 and Thr-235 residues in OsCDKD. The MAP kinase-mediated phosphorylation of OsCDKD is required for its activation to control the small RNA biogenesis. The phosphodead version of OsCDKD fails to activate the C-terminal domain of RNA Polymerase II, thereby negatively impacting small RNA transcription. Further, the overexpression lines of wild-type (WT) OsCDKD and phosphomimic OsCDKD show increased root growth, plant height, tiller number, panicle number, and seed number in comparison to WT, phosphodead OsCDKD-OE, and kinase-dead OsCDKD-OE plants. In a nutshell, our study establishes a novel regulation of OsCDKD by MAPK-mediated phosphorylation in rice. The phosphorylation of OsCDKD by MAPKs imparts a positive effect on rice growth and development by regulating miRNAs transcription., (© 2024 The Author(s). New Phytologist © 2024 New Phytologist Foundation.)

Arabidopsis LIM proteins are named after the initials of three proteins Lin-11, Isl-1, and MEC-3, which belong to a class of transcription factors that play an important role in the developmental regulation of eukaryotes and are also involved in a variety of life processes, including gene transcription, the construction of the cytoskeleton, signal transduction, and metabolic regulation. Plant LIM proteins have been shown to regulate actin bundling in different cells, but their role in immunity remains elusive. Mitogen-activated protein kinases (MAPKs) are a family of conserved serine/threonine protein kinases that link upstream receptors to their downstream targets. Pathogens produce pathogen-associated molecular patterns (PAMPs) that trigger the activation of MAPK cascades in plants. Recently, we conducted a large-scale phosphoproteomic analysis of PAMP-induced Arabidopsis plants to identify putative MAPK targets. One of the identified phospho-proteins was WLIM2A, an Arabidopsis LIM protein. In this study, we investigated the role of WLIM2A in plant immunity. We employed a reverse-genetics approach and generated wlim2a knockout lines using CRISPR-Cas9 technology. We also generated complementation and phosphosite-mutated WLIM2A expression lines in the wlim2a background. The wlim2a lines were compromised in their response to Pseudomonas syringae Pst DC3000 but showed enhanced resistance to the necrotrophic fungus Botrytis cinereae . Transcriptome analyses of wlim2a mutants revealed the deregulation of immune hormone biosynthesis and signaling of salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) pathways. The wlim2a mutants also exhibited altered stomatal phenotypes. Analysis of plants expressing WLIM2A variants of the phospho-dead or phospho-mimicking MAPK phosphorylation site showed opposing stomatal behavior and resistance phenotypes in response to Pst DC3000 infection, proving that phosphorylation of WLIM2A plays a crucial role in plant immunity. Overall, these data demonstrate that phosphorylation of WLIM2A by MAPKs regulates Arabidopsis responses to plant pathogens.

Mitotic anaphase onset is a key cellular process tightly regulated by multiple kinases. The involvement of mitogen-activated protein kinases (MAPKs) in this process has been established in Xenopus egg extracts. However, the detailed regulatory cascade remains elusive, and it is also unknown whether the MAPK-dependent mitotic regulation is evolutionarily conserved in the single-cell eukaryotic organisms such as fission yeast ( Schizosaccharomyces pombe ). Here, we show that two MAPKs in S. pombe indeed act in concert to restrain anaphase-promoting complex/cyclosome (APC/C) activity upon activation of the spindle assembly checkpoint (SAC). One MAPK, Pmk1, binds to and phosphorylates Slp1 Cdc20 , the co-activator of APC/C. Phosphorylation of Slp1 Cdc20 by Pmk1, but not by Cdk1, promotes its subsequent ubiquitylation and degradation. Intriguingly, Pmk1-mediated phosphorylation event is also required to sustain SAC under environmental stress. Thus, our study establishes a new underlying molecular mechanism of negative regulation of APC/C by MAPK upon stress stimuli, and provides a previously unappreciated framework for regulation of anaphase entry in eukaryotic cells., Competing Interests: LS, XC, CS, WS, LL, SB, XW, JC, CJ, SW, ZL, RW, YW, QJ No competing interests declared, (© 2024, Sun, Chen, Song et al.)

Eukaryotic organisms are composed of different cell types with defined shapes and functions. Specific cell types are produced by the process of cell differentiation, which is regulated by signal transduction pathways. Signaling pathways regulate cell differentiation by sensing cues and controlling the expression of target genes whose products generate cell types with specific attributes. In studying how cells differentiate, fungi have proved valuable models because of their ease of genetic manipulation and striking cell morphologies. Many fungal species undergo filamentous growth-a specialized growth pattern where cells produce elongated tube-like projections. Filamentous growth promotes expansion into new environments, including invasion into plant and animal hosts by fungal pathogens. The same signaling pathways that regulate filamentous growth in fungi also control cell differentiation throughout eukaryotes and include highly conserved mitogen-activated protein kinase (MAPK) pathways, which is the focus of this review. In many fungal species, mucin-type sensors regulate MAPK pathways to control filamentous growth in response to diverse stimuli. Once activated, MAPK pathways reorganize cell polarity, induce changes in cell adhesion, and promote the secretion of degradative enzymes that mediate access to new environments. However, MAPK pathway regulation is complicated because related pathways can share components with each other yet induce unique responses (i.e. signal specificity). In addition, MAPK pathways function in highly integrated networks with other regulatory pathways (i.e. signal integration). Here, we discuss signal specificity and integration in several yeast models (mainly Saccharomyces cerevisiae and Candida albicans) by focusing on the filamentation MAPK pathway. Because of the strong evolutionary ties between species, a deeper understanding of the regulation of filamentous growth in established models and increasingly diverse fungal species can reveal fundamentally new mechanisms underlying eukaryotic cell differentiation., Competing Interests: Conflicts of interest The authors declare that there are no competing interests with this study. There are no new data associated with this article., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Genetics Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Mitogen-activated protein kinase (MAPK) signalling is vitally important in tumour development and progression. This study is the first to comprehensively analyse the role of MAPK-family genes in the progression, prognosis, immune-cell infiltration, methylation, and potential therapeutic value drug candidates in ccRCC. We identified a novel prognostic panel of six MAPK-signature genes (MAP3K12, MAP3K1, MAP3K5, MAPK1, MAPK8, MAPK9), and introduced a robust MAPK-signature risk model for predicting ccRCC prognosis. Model construction, evaluation, and external validation using datasets from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database demonstrated its stability, as well as high sensitivity and specificity. Enrichment analysis suggested the participation of immune-mediated mechanism in MAPK dysregulation in ccRCC. Immune-infiltration analysis confirmed the relationship and revealed that the MAPK-signature risk model might stratify immunotherapy response in ccRCC, which was verified in drug sensitivity analysis and validated in external ccRCC immunotherapy dataset (GSE67501). Potential therapeutic drug predictions for key MAPKs using DSigDB, Network Analyst, CTD, and DGIdb were subsequently verified by molecular docking with AutoDock Vina and PyMol. Mendelian randomization further demonstrated the possibilities of the MAPK-signature genes as targets for therapeutic drugs in ccRCC. Methylation analysis using UALCAN and MethSurv revealed the participation of epigenetic modifications in dysregulation and survival difference of MAPK pathway in ccRCC. Among the key MAPKs, MAP3K12 exhibited the highest significance, indicating its independent prognostic value as single gene in ccRCC. Knockout and overexpression validation experiments in vitro and in vivo found that MAP3K12 acted as a promoter of tumour progression in RCC, suggesting a pivotal role for MAP3K12 in the proliferation, migration, and invasion of RCC cells. Our findings proposed the potential of MAPK-signature genes as biomarkers for prognosis and therapy response, as well as targets for therapeutic drugs in ccRCC., Competing Interests: Declaration of competing interest The authors declare no competing interest exists. The authors declared that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024. Published by Elsevier B.V.)

An Arabidopsis (Arabidopsis thaliana) mitogen-activated protein kinase (MAPK) cascade composed of YODA (YDA)-MKK4/MKK5-MPK3/MPK6 plays an essential role downstream of the ERECTA (ER)/ER-LIKE (ERL) receptor complex in regulating stomatal development in the leaf epidermis. STOMAGEN (STO), a peptide ligand produced in mesophyll cells, competes with EPIDERMAL PATTERNING FACTOR2 (EPF2) for binding ER/ERL receptors to promote stomatal formation. In this study, we found that activation of MPK3/MPK6 suppresses STO expression. Using MUTE and STO promoters that confer epidermis- and mesophyll-specific expression, respectively, we generated lines with cell-specific activation and suppression of MPK3/MPK6. The activation or suppression of MPK3/MPK6 in either epidermis or mesophyll cells is sufficient to alter stomatal differentiation. Epistatic analyses demonstrated that STO overexpression can rescue the suppression of stomatal formation conferred by the mesophyll-specific expression of the constitutively active MKK4DD or MKK5DD, but not by the epidermis-specific expression of these constitutively active MKKs. These data suggest that STO is downstream of MPK3/MPK6 in mesophyll cells, but upstream of MPK3/MPK6 in epidermal cells in stomatal development signaling. This function of the MPK3/MPK6 cascade allows it to coordinate plant epidermis development based on its activity in mesophyll cells during leaf development., Competing Interests: Conflict of interest statement. None declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Plants can perceive a slight upsurge in ambient temperature and respond by undergoing morphological changes, such as elongated hypocotyls and early flowering. The dynamic functioning of PHYTOCHROME INTERACTING FACTOR4 (PIF4) in thermomorphogenesis is well established, although the complete regulatory pathway involved in thermosensing remains elusive. We establish that an increase in temperature from 22 to 28 °C induces upregulation and activation of MITOGEN-ACTIVATED PROTEIN KINASE 4 (MPK4) in Arabidopsis (Arabidopsis thaliana), subsequently leading to the phosphorylation of PIF4. Phosphorylated PIF4 represses the expression of ACTIN-RELATED PROTEIN 6 (ARP6), which is required for mediating the deposition of histone variant H2A.Z at its target loci. Furthermore, we demonstrate that variations in ARP6 expression in PIF4 phosphor-null and phosphor-mimetic seedlings affect hypocotyl growth at 22 and 28 °C by modulating the regulation of ARP6-mediated H2A.Z deposition at the loci of genes involved in elongating hypocotyl cells. Interestingly, the expression of MPK4 is also controlled by H2A.Z deposition in a temperature-dependent manner. Taken together, these findings highlight the regulatory mechanism of thermosensing by which MPK4-mediated phosphorylation of PIF4 affects ARP6-mediated H2A.Z deposition at the genes involved in hypocotyl cell elongation., Competing Interests: Conflict of interest statement. The authors declare no conflict of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Drought stress inhibits plant growth and agricultural production. Improving plant instantaneous water use efficiency (iWUE), which is strictly regulated by stomata, is an effective way to cope with drought stress. However, the mechanisms of iWUE regulation are poorly understood. Through genetic screening for suppressors of mpk12-4, an Arabidopsis (Arabidopsis thaliana) mutant with a major iWUE quantitative trait locus gene MITOGEN-ACTIVATED PROTEIN KINASE12 deleted, we identified HIGH LEAF TEMPERATURE1 (HT1). Genetic interaction and physiological analyses showed that MPK12 controls iWUE through multiple modules in a high CO2-induced stomatal closing pathway that regulate SLOW ANION CHANNEL-ASSOCIATED1 (SLAC1) activity. HT1 acts downstream of MPK12, whereas OPEN STOMATA1 (OST1) and GUARD CELL HYDROGEN PEROXIDE-RESISTANT1 (GHR1) function downstream of HT1 by activating SLAC1 in iWUE. Photosynthetic-CO2 response curves and biomass analyses under different water-supply conditions showed that HT1 dysfunction improved iWUE and also increased plant growth capacity, and products of HT1 putative orthologs from Brassica (Brassica napus) and rice (Oryza sativa) exhibited functions similar to that of Arabidopsis HT1 in iWUE and the CO2-signaling pathway. Our study revealed the mechanism of MPK12-mediated iWUE regulation in Arabidopsis and provided insight into the internal relationship between iWUE and CO2 signaling in guard cells and a potential target for improving crop iWUE and drought tolerance., Competing Interests: Conflict of interest statement. None declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Mitogen-activated protein kinase (MAPK) signalling cascades are functionally important signalling modules in eukaryotes. Transcriptome reprogramming of immune-related genes is a key process in plant immunity. Emerging evidence shows that plant MAPK cascade is associated with processing (P)-body components and contributes to transcriptome reprogramming of immune-related genes. However, it remains largely unknown how this process is regulated. Here, we show that OsMPK12, which is induced by Magnaporthe oryzae infection, positively regulates rice blast resistance. Further analysis revealed that OsMPK12 directly interacts with enhancer of mRNA decapping protein 4 (OsEDC4), a P-body-located protein, and recruits OsEDC4 to where OsMPK12 is enriched. Importantly, OsEDC4 directly interacts with two decapping complex members OsDCP1 and OsDCP2, indicating that OsEDC4 is a subunit of the mRNA decapping complex. Additionally, we found that OsEDC4 positively regulates rice blast resistance by regulating expression of immune-related genes and maintaining proper mRNA levels of some negatively-regulated genes. And OsMPK12 and OsEDC4 are also involved in rice growth and development regulation. Taken together, our data demonstrate that OsMPK12 positively regulates rice blast resistance via OsEDC4-mediated mRNA decay of immune-related genes, providing new insight into not only the new role of the MAPK signalling cascade, but also posttranscriptional regulation of immune-related genes., (© 2024 John Wiley & Sons Ltd.)

Plants synthesize hundreds of small secretory peptides, which are perceived by the receptor-like kinase (RLK) family at the cell surface. Various signaling peptide-RLK pairs ensure plant adaptation to distinct environmental conditions. Here, we report that SERINE RICH ENDOGENOUS PEPTIDE (SCOOP) immune peptides modulate root growth and development by regulating PIN-FORMED (PIN)-regulated polar auxin transport in Arabidopsis. The SCOOP4 and SCOOP12 treatments impaired root gravitropic growth, auxin redistribution in response to gravistimulation, and PIN abundance in the PM. Furthermore, genetic and cell biological analyses revealed that these physiological and cellular effects of SCOOP4 and SCOOP12 peptides are mediated by the receptor MALE DISCOVERER1-INTERACTING RECEPTOR LIKE KINASE2 (MIK2) and the downstream mitogen-activated kinase MPK6. Biochemical evidence indicates that MPK6 directly phosphorylates the cytosolic loop of PIN proteins. Our work established a link between the immune signaling peptide SCOOPs and root growth pathways, providing insights into the molecular mechanisms underlying plant root adaptive growth in the defense response., (© 2024 Society for Experimental Biology and John Wiley & Sons Ltd.)

The green peach aphid (GPA), Myzus persicae (Sulzer), is a serious agricultural pest with a worldwide distribution and a vector of over 100 plant viruses. Various pathways, such as the mitogen-activated protein kinase (MAPK) cascades, play pivotal roles in signaling plant defense against pest attack, and circular RNAs (circRNAs) regulate the expression of mRNAs in response to pest attack. However, the mechanism underlying peach (Prunus persica) response to GPA attack remains unclear. The present study initially identified and characterized 316 circRNAs and 18 PpMAPKs from healthy and GPA-infested peach leaves by whole-transcriptome sequencing and predicted the differentially expressed circRNAs (DECs) after GPA infestation. PCR and Sanger sequencing confirmed the presence of six DECs in peach samples. Besides, RNA sequencing analysis detected 13 DECs, including 5 upregulated and 8 downregulated ones, in peach in response to the GPA attack. Gene ontology (GO) enrichment analysis indicated that specific DECs play crucial roles in the MAPK signaling pathway, and qRT-PCR revealed that GPA infestation altered the expression patterns of PpMAPKs. Finally, five circRNAs, three microRNA (miRNAs), and two MAPK target genes were identified to interact as a network and perform critical roles in modulating the MAPK pathway in the peach during GPA infestation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Group III hybrid histidine kinases (HHK3) are known molecular targets of the widely used fungicidal agent fludioxonil which indirectly converts these kinases to a phosphatase form that causes constitutive activation of Hog1 MAPK. To better understand the fungicidal effect of fludioxonil we have screened S. cerevisiae haploid deletion collection for fludioxonil resistant mutant and identified Ssd1 as a critical factor for this. Deletion of SSD1 not only promoted resistance to fludioxonil but also abrogated Hog1 activation and other cellular damages caused by fludioxonil. Our results showed that fludioxonil perturbed the localization of Cbk1 kinase, an essential protein in yeast, at the bud neck triggering the accumulation of Ssd1 in P-bodies. As a result, localized synthesis of Ssd1 bound mRNA encoding cell wall proteins at the polarized growth site was impaired which created a sustained cell wall stress causing constitutive activation of Hog1. Our data, for the first time, clearly indicated the role of Cbk1 upstream of Hog1 and provided a novel paradigm in the mechanism of action of fludioxonil., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The retina is composed of neuronal layers that include several types of interneurons and photoreceptor cells, and separate underlying retinal pigment epithelium (RPE), Bruch's membrane, and choroid. Different regions of the human retina include the fovea, macula, and periphery, which have unique physiological functions and anatomical features. These regions are also unique in their protein expression, and corresponding cellular and molecular responses to physiological and pathophysiological stimuli. Skeie and Mahajan analyzed regional protein expression in the human choroid-RPE complex. Mitogen-Activated Protein Kinase (MAPK) signaling pathways have been implicated in responses to stimuli such as oxidative stress and inflammation, which are critical factors in retina diseases including age-related macular degeneration. We, therefore, analyzed the Skeie and Mahajan, 2014, dataset for regional differences in the expression of MAPK-related proteins and discussed the potential implications in retinal diseases presenting with regional signs and symptoms. Regional protein expression data from the Skeie and Mahajan, 2014, study were analyzed for members of signaling networks involving MAPK and MAPK-related proteins, categorized by specific MAPK cascades, such as p38, ERK1/2, and JNK1/2, both upstream or downstream of the respective MAPK and MAPK-related proteins. We were able to identify 207 MAPK and MAPK-related proteins, 187 of which belonging to specific MAPK cascades. A total of 31 of these had been identified in the retina with two proteins, DLG2 and FLG downstream, and the other 29 upstream, of MAPK proteins. Our findings provide evidence for potential molecular substrates of retina region-specific disease manifestation and potential new targets for therapeutics development.

Plants respond to increased CO2 concentrations through stomatal closure, which can contribute to increased water use efficiency. Grasses display faster stomatal responses than eudicots due to dumbbell-shaped guard cells flanked by subsidiary cells working in opposition. However, forward genetic screening for stomatal CO2 signal transduction mutants in grasses has yet to be reported. The grass model Brachypodium distachyon is closely related to agronomically important cereal crops, sharing largely collinear genomes. To gain insights into CO2 control mechanisms of stomatal movements in grasses, we developed an unbiased forward genetic screen with an EMS-mutagenized B. distachyon M5 generation population using infrared imaging to identify plants with altered leaf temperatures at elevated CO2. Among isolated mutants, a "chill1" mutant exhibited cooler leaf temperatures than wild-type Bd21-3 parent control plants after exposure to increased CO2. chill1 plants showed strongly impaired high CO2-induced stomatal closure despite retaining a robust abscisic acid-induced stomatal closing response. Through bulked segregant whole-genome sequencing analyses followed by analyses of further backcrossed F4 generation plants and generation and characterization of sodium azide and CRISPR-cas9 mutants, chill1 was mapped to a protein kinase, Mitogen-Activated Protein Kinase 5 (BdMPK5). The chill1 mutation impaired BdMPK5 protein-mediated CO2/HCO3- sensing together with the High Temperature 1 (HT1) Raf-like kinase in vitro. Furthermore, AlphaFold2-directed structural modeling predicted that the identified BdMPK5-D90N chill1 mutant residue is located at the interface of BdMPK5 with the BdHT1 Raf-like kinase. BdMPK5 is a key signaling component that mediates CO2-induced stomatal movements and is proposed to function as a component of the primary CO2 sensor in grasses., Competing Interests: Conflict of interest statement. None declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Cells harbour numerous receptor pathways to respond to diverse stimuli, yet often share common downstream signalling components. Mitogen-activated protein kinase (MPK) cascades are an example of such common hubs in eukaryotes. How such common hubs faithfully transduce distinct signals within the same cell-type is insufficiently understood, yet of fundamental importance for signal integration and processing in plants. We engineered a unique genetic background allowing direct comparisons of a developmental and an immunity pathway in one cell-type, the Arabidopsis root endodermis. We demonstrate that the two pathways maintain distinct functional and transcriptional outputs despite common MPK activity patterns. Nevertheless, activation of different MPK kinases and MPK classes led to distinct functional readouts, matching observed pathway-specific readouts. On the basis of our comprehensive analysis of core MPK signalling elements, we propose that combinatorial activation within the MPK cascade determines the differential regulation of an endodermal master transcription factor, MYB36, that drives pathway-specific gene activation., (© 2024. The Author(s).)

Type 2C protein phosphatases (PP2Cs) are emerging as important regulators of plant immune responses, although little is known about how they might impact nucleotide-binding, leucine-rich repeat (NLR)-triggered immunity (NTI). We discovered that expression of the PP2C immunity-associated candidate 14 gene (Pic14) is induced upon activation of the Pto/Prf-mediated NTI response in tomato. Pto/Prf recognizes the effector AvrPto translocated into plant cells by the pathogen Pseudomonas syringae pv. tomato (Pst) and activate a MAPK cascade and other responses which together confer resistance to bacterial speck disease. Pic14 encodes a PP2C with an N-terminal kinase-interacting motif (KIM) and a C-terminal phosphatase domain. Upon inoculation with Pst-AvrPto, Pto/Prf-expressing tomato plants with loss-of-function mutations in Pic14 developed less speck disease, specifically in older leaves, compared to wild-type plants. Transient expression of Pic14 in leaves of Nicotiana benthamiana and tomato inhibited cell death typically induced by Pto/Prf and the MAPK cascade members M3Kα and Mkk2. The cell death-suppressing activity of Pic14 was dependent on the KIM and the catalytic phosphatase domain. Pic14 inhibited M3Kα- and Mkk2-mediated activation of immunity-associated MAPKs and Pic14 was shown to be an active phosphatase that physically interacts with and dephosphorylates Mkk2 in a KIM-dependent manner. Together, our results reveal Pic14 as an important negative regulator of Pto/Prf-triggered immunity by interacting with and dephosphorylating Mkk2., (© 2024 Society for Experimental Biology and John Wiley & Sons Ltd.)

Background: The mitogen-activated protein kinase (MAPK) cascade is crucial cell signal transduction mechanism that plays an important role in plant growth and development, metabolism, and stress responses. The MAPK cascade includes three protein kinases, MAPK, MAPKK, and MAPKKK. The three protein kinases mediate signaling to downstream response molecules by sequential phosphorylation. The MAPK gene family has been identified and analyzed in many plants, however it has not been investigated in alfalfa., Results: In this study, Medicago sativa MAPK genes (referred to as MsMAPKs) were identified in the tetraploid alfalfa genome. Eighty MsMAPKs were divided into four groups, with eight in group A, 21 in group B, 21 in group C and 30 in group D. Analysis of the basic structures of the MsMAPKs revealed presence of a conserved TXY motif. Groups A, B and C contained a TEY motif, while group D contained a TDY motif. RNA-seq analysis revealed tissue-specificity of two MsMAPKs and tissue-wide expression of 35 MsMAPKs. Further analysis identified MsMAPK members responsive to drought, salt, and cold stress conditions. Two MsMAPKs (MsMAPK70 and MsMAPK75) responds to salt and cold stresses; two MsMAPKs (MsMAPK60 and MsMAPK73) responds to cold and drought stresses; four MsMAPKs (MsMAPK1, MsMAPK33, MsMAPK64 and MsMAPK71) responds to salt and drought stresses; and two MsMAPKs (MsMAPK5 and MsMAPK7) responded to all three stresses., Conclusion: This study comprehensively identified and analysed the alfalfa MAPK gene family. Candidate genes related to abiotic stresses were screened by analysing the RNA-seq data. The results provide key information for further analysis of alfalfa MAPK gene functions and improvement of stress tolerance., (© 2024. The Author(s).)

IL-33 belongs to the inflammatory factor family and is closely associated with the inflammatory response. However, its role in the development of intrauterine adhesions (IUAs) remains unclear. In this study, the role of IL-33 in the formation of IUAs after endometrial injury was identified via RNA sequencing after mouse endometrial organoids were transplanted into an IUA mouse model. Major pathological changes in the mouse uterus, consistent with the expression of fibrotic markers, such as TGF-β, were observed in response to treatment with IL-33. This finding may be attributed to activation of the phosphorylation of downstream MAPK signaling pathway components, which are activated by the release of IL-33 in macrophages. Our study provides a novel mechanism for elucidating IUA formation, suggesting a new therapeutic strategy for the prevention and clinical treatment of IUAs., (© 2024. The Author(s).)

Peptostreptococcus stomatis (P. stomatis) is enriched in colorectal cancer (CRC), but its causality and translational implications in CRC are unknown. Here, we show that P. stomatis accelerates colonic tumorigenesis in Apc Min/+ and azoxymethane/dextran sodium sulfate (AOM-DSS) models by inducing cell proliferation, suppressing apoptosis, and impairing gut barrier function. P. stomatis adheres to CRC cells through its surface protein fructose-1,6-bisphosphate aldolase (FBA) that binds to the integrin α6/β4 receptor on CRC cells, leading to the activation of ERBB2 and the downstream MEK-ERK-p90 cascade. Blockade of the FBA-integrin α6/β4 abolishes ERBB2-mitogen-activated protein kinase (MAPK) activation and the protumorigenic effect of P. stomatis. P. stomatis-driven ERBB2 activation bypasses receptor tyrosine kinase (RTK) blockade by EGFR inhibitors (cetuximab, erlotinib), leading to drug resistance in xenograft and spontaneous CRC models of KRAS-wild-type CRC. P. stomatis also abrogates BRAF inhibitor (vemurafenib) efficacy in BRAF V600E -mutant CRC xenografts. Thus, we identify P. stomatis as an oncogenic bacterium and a contributory factor for non-responsiveness to RTK inhibitors in CRC., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Allosteric mechanisms provide finely-tuned control over signalling proteins. Proteins of the same family may share high sequence identity and structural similarity but show distinct traits of allosteric control and evolutionary divergent regulation. Revealing the determinants of such properties may be important to understand the molecular bases of different regulatory pathways. Herein, we investigate whether and how evolutionarily-divergent traits of allosteric regulation in homologous proteins can be decoded in terms of internal dynamics and interaction networks that support functionally oriented conformations. In this framework, we start from the comparative analysis of the dynamics and energetics of the yeast MAP Kinases (MAPKs) Fus3 and Kss1 in their native basins. Importantly, distinctive dynamic and energetic stabilization features emerge, which can be related to the two proteins' differential ability to be phosphorylated and engage with the allosteric activator Ste5. We then expanded our study to other evolutionarily-related MAPKs. We show that the dynamical and energetical traits defining the distinct regulatory profiles of Fus3 and Kss1 can be traced along their evolutionary tree. Overall, our approach is able to reconnect (latent) allostery with the principal elements of protein structural stabilization and dynamics, showing how allosteric regulation was encrypted in MAPKs structure well before Ste5 appearance., (© 2024 Wiley-VCH GmbH.)

Key Message: Volatile compounds released from basil prime the tomato wound response by promoting jasmonic acid, mitogen-activated protein kinase, and reactive oxygen species signaling. Within mixed planting systems, companion plants can promote growth or enhance stress responses in target plants. However, the mechanisms underlying these effects remain poorly understood. To gain insight into the molecular nature of the effects of companion plants, we investigated the effects of basil plants (Ocimum basilicum var. minimum) on the wound response in tomato plants (Solanum lycopersicum cv. 'Micro-Tom') within a mixed planting system under environmentally controlled chamber. The results showed that the expression of Pin2, which specifically responds to mechanical wounding, was induced more rapidly and more strongly in the leaves of tomato plants cultivated with companion basil plants. This wound response priming effect was replicated through the exposure of tomato plants to an essential oil (EO) prepared from basil leaves. Tomato leaves pre-exposed to basil EO showed enhanced expression of genes related to jasmonic acid, mitogen-activated protein kinase (MAPK), and reactive oxygen species (ROS) signaling after wounding stress. Basil EO also enhanced ROS accumulation in wounded tomato leaves. The wound response priming effect of basil EO was confirmed in wounded Arabidopsis plants. Loss-of-function analysis of target genes revealed that MAPK genes play pivotal roles in controlling the observed priming effects. Spodoptera litura larvae-fed tomato leaves pre-exposed to basil EO showed reduced growth compared with larvae-fed control leaves. Thus, mixed planting with basil may enhance defense priming in both tomato and Arabidopsis plants through the activation of volatile signaling., (© 2024. The Author(s).)

Mitogen-activated protein kinase (MAPK) pathways are fundamental to the regulation of biological processes in eukaryotic organisms. The basidiomycete Cryptococcus neoformans , known for causing fungal meningitis worldwide, possesses five MAPKs. Among these, Cpk1, Hog1, and Mpk1 have established roles in sexual reproduction, stress responses, and cell wall integrity. However, the roles of Cpk2 and Mpk2 are less understood. Our study elucidates the functional interplay between the Cpk1/Cpk2 and Mpk1/Mpk2 MAPK pathways in C. neoformans . We discovered that CPK2 overexpression compensates for cpk1 Δ mating deficiencies via the Mat2 transcription factor, revealing functional redundancy between Cpk1 and Cpk2. We also found that Mpk2 is phosphorylated in response to cell wall stress, a process regulated by the MAPK kinase (MAP2K) Mkk2 and MAP2K kinases (MAP3Ks) Ssk2 and Ste11. Overexpression of MPK2 partially restores cell wall integrity in mpk1 Δ by influencing key cell wall components, such as chitin and the polysaccharide capsule. Contrarily, MPK2 overexpression cannot restore thermotolerance and cell membrane integrity in mpk1 Δ. These results suggest that Mpk1 and Mpk2 have redundant and opposing roles in the cellular response to cell wall and membrane stresses. Most notably, the dual deletion of MPK1 and MPK2 restores wild-type mating efficiency in cpk1 Δ mutants via upregulation of the mating-regulating transcription factors MAT2 and ZNF2 , suggesting that the Mpk1 and Mpk2 cooperate to negatively regulate the pheromone-responsive Cpk1 MAPK pathway. Our research collectively underscores a sophisticated regulatory network of cryptococcal MAPK signaling pathways that intricately govern sexual reproduction and cell wall integrity, thereby controlling fungal development and pathogenicity.IMPORTANCEIn the realm of fungal biology, our study on Cryptococcus neoformans offers pivotal insights into the roles of specific proteins called mitogen-activated protein kinases (MAPKs). Here, we discovered the cryptic functions of Cpk2 and Mpk2, two MAPKs previously overshadowed by their dominant counterparts Cpk1 and Mpk1, respectively. Our findings reveal that these "underdog" proteins are not just backup players; they play crucial roles in vital processes like mating and cell wall maintenance in C. neoformans . Their ability to step in and compensate when their dominant counterparts are absent showcases the adaptability of C. neoformans . This newfound understanding not only enriches our knowledge of fungal MAPK mechanisms but also underscores the intricate balance and interplay of proteins in ensuring the organism's survival and adaptability., Competing Interests: The authors declare no conflict of interest.

The high osmolarity glycerol 1 mitogen-activated protein kinase (Hog1-MAPK) cascade genes are important for diverse biological processes. The activated Hog1 upon multiple environmental stress stimuli enters into the nucleus where it directly phosphorylates transcription factors to regulate various physiological processes in phytopathogenic fungi. However, their roles have not been well-characterized in Fusarium verticillioides. In this study, FvHog1 is identified and functionally analyzed. The findings reveal that the phosphorylation level and nuclear localization of FvHog1 are increased in Fumonisin B1 (FB1)-inducing condition to regulate the expression of FB1 biosynthesis FUM genes. More importantly, the deletion mutants of Hog1-MAPK pathway show increased sensitivity to Ca 2+ stress and elevated intracellular Ca 2+ content. The phosphorylation level and nuclear localization of FvHog1 are increased with Ca 2+ treatment. Furthermore, our results show that FvHog1 can directly phosphorylate Ca 2+ -responsive zinc finger transcription factor 1 (FvCrz1) to regulate Ca 2+ homeostasis. In conclusion, our findings indicate that FvHog1 is required for FB1 biosynthesis, pathogenicity and Ca 2+ homeostasis in F. verticillioides. It provides a theoretical basis for effective prevention and control maize ear and stalk rot disease., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The timing of seed germination is controlled by the combination of internal dormancy and external factors. Temperature is a major environmental factor for seed germination. The permissive temperature range for germination is narrow in dormant seeds and expands during after-ripening (AR) (dormancy release). Quantitative trait loci analyses of preharvest sprouting in cereals have revealed that MKK3, a mitogen-activated protein kinase (MAPK) cascade protein, is a negative regulator of grain dormancy. Here, we show that the MAPKKK19/20-MKK3-MPK1/2/7/14 cascade modulates the germination temperature range in Arabidopsis seeds by elevating the germinability of the seeds at sub- and supraoptimal temperatures. The expression of MAPKKK19 and MAPKKK20 is induced around optimal temperature for germination in after-ripened seeds but repressed in dormant seeds. MPK7 activation depends on the expression levels of MAPKKK19/20 , with expression occurring under conditions permissive for germination. Abscisic acid (ABA) and gibberellin (GA) are two major phytohormones which are involved in germination control. Activation of the MKK3 cascade represses ABA biosynthesis enzyme gene expression and induces expression of ABA catabolic enzyme and GA biosynthesis enzyme genes, resulting in expansion of the germinable temperature range. Our data demonstrate that the MKK3 cascade integrates temperature and AR signals to phytohormone metabolism and seed germination., Competing Interests: Competing interests statement:The authors declare no competing interest.

The cell wall is the first barrier against external adversity and plays roles in maintaining normal physiological functions of fungi. Previously, we reported a nucleosome assembly protein, MoNap1, in Magnaporthe oryzae that plays a role in cell wall integrity (CWI), stress response, and pathogenicity. Moreover, MoNap1 negatively regulates the expression of MoSMI1 encoded by MGG_03970. Here, we demonstrated that deletion of MoSMI1 resulted in a significant defect in appressorium function, CWI, cell morphology, and pathogenicity. Further investigation revealed that MoSmi1 interacted with MoOsm1 and MoMps1 and affected the phosphorylation levels of MoOsm1, MoMps1, and MoPmk1, suggesting that MoSmi1 regulates biological functions by mediating mitogen-activated protein kinase (MAPK) signalling pathway in M. oryzae. In addition, transcriptome data revealed that MoSmi1 regulates many infection-related processes in M. oryzae, such as membrane-related pathway and oxidation reduction process. In conclusion, our study demonstrated that MoSmi1 regulates CWI by mediating the MAPK pathway to affect development and pathogenicity of M. oryzae., (© 2024 The Author(s). Molecular Plant Pathology published by British Society for Plant Pathology and John Wiley & Sons Ltd.)

Living organisms are frequently exposed to multiple biotic and abiotic stress forms during their lifetime. Organisms cope with stress conditions by regulating their gene expression programs. In response to different environmental stress conditions, yeast cells activate different tolerance mechanisms, many of which share common signaling pathways. Flocculation is one of the key mechanisms underlying yeast survival under unfavorable environmental conditions, and the Tup1-Cyc8 corepressor complex is a major regulator of this process. Additionally, yeast cells can utilize different mitogen-activated protein kinase (MAPK) pathways to modulate gene expression during stress conditions. Here, we show that the high osmolarity glycerol (HOG) MAPK pathway is involved in the regulation of yeast flocculation. We observed that the HOG MAPK pathway was constitutively activated in flocculating cells, and found that the interaction between phosphorylated Hog1 and the FLO genes promoter region increased significantly upon sodium chloride exposure. We found that treatment of cells with cantharidin decreased Hog1 phosphorylation, causing a sharp reduction in the expression of FLO genes and the flocculation phenotype. Similarly, deletion of HOG1 in yeast cells reduced flocculation. Altogether, our results suggest a role for HOG MAPK signaling in the regulation of FLO genes and yeast flocculation., (© 2024 Federation of European Biochemical Societies.)

Tapetum, the innermost layer of the anther wall, provides essential nutrients and materials for pollen development. Timely degradation of anther tapetal cells is a prerequisite for normal pollen development in flowering plants. Tapetal cells facilitate male gametogenesis by providing cellular contents after highly coordinated programmed cell death (PCD). Tapetal development is regulated by a transcriptional network. However, the signaling pathway(s) involved in this process are poorly understood. In this study, we report that a mitogen-activated protein kinase (MAPK) cascade composed of OsYDA1/OsYDA2-OsMKK4-OsMPK6 plays an important role in tapetal development and male gametophyte fertility. Loss of function of this MAPK cascade leads to anther indehiscence, enlarged tapetum, and aborted pollen grains. Tapetal cells in osmkk4 and osmpk6 mutants exhibit an increased presence of lipid body-like structures within the cytoplasm, which is accompanied by a delayed occurrence of PCD. Expression of a constitutively active version of OsMPK6 (CA-OsMPK6) can rescue the pollen defects in osmkk4 mutants, confirming that OsMPK6 functions downstream of OsMKK4 in this pathway. Genetic crosses also demonstrated that the MAPK cascade sporophyticly regulates pollen development. Our study reveals a novel function of rice MAPK cascade in plant male reproductive biology., (© 2024 Institute of Botany, Chinese Academy of Sciences.)

Background: About 75% of medullary thyroid cancers (MTCs) are sporadic with 45% to 70% being driven by a RET mutation. Selpercatinib is an approved treatment for RET-mutated (mut RET ) MTC; however, treatments are needed for wild-type RET MTC (wt RET ). Genomic alterations and transcriptomic signatures of wt RET MTC may reveal new therapeutic insights., Study Design: We did a retrospective analysis of MTC samples submitted for DNA/RNA sequencing and programmed cell death ligand 1 expression using immunohistochemistry at a Clinical Laboratory Improvement Amendments/College of American Pathologists-certified laboratory. Tumor microenvironment immune cell fractions were estimated using RNA deconvolution (quanTIseq). Transcriptomic signatures of inflammation and MAP kinase pathway activation scores were calculated. Mann-Whitney U, chi-square, and Fisher's exact tests were applied (p values adjusted for multiple comparisons)., Results: The 160-patient cohort included 108 mut RET and 52 wt RET MTC samples. wt RET tumors frequently harbored mitogen-activated protein kinase (MAPK) pathway mutations, including HRAS (42.31%), KRAS (15.7%), NF1 (6.7%), and BRAF (2%), whereas only 1 MAPK pathway mutation ( NF1 ) was identified among mut RET MTC. Recurrent mutations seen in wt RET MTC included MGA , VHL, APC , STK11 , and NFE2L2 . Increased transcriptional activation of the MAPK pathway was observed in patients with wt RET harboring mutations in MAPK genes. Although the frequency of programmed cell death ligand 1 expression was similar in wt RET and mut RET (10.2% vs 7%, p = 0.531), wt RET tumors were more often tumor mutational burden high (7.7% vs 0%, p = 0.011), and wt RET MTC exhibited higher expression of immune checkpoint genes., Conclusions: We identified molecular alterations and immune-related features that distinguish wt RET from mut RET MTC. Although RET mutation drives MTC in the absence of other alterations, we showed that wt RET MTC frequently harbors MAPK pathway mutations. These findings may indicate a potential basis for MAPK-targeted therapy, possibly in combination with immuno-oncology agents for selected patients with wt RET MTC., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American College of Surgeons.)

Ectomycorrhizal symbiosis, which involves mutually beneficial interactions between soil fungi and tree roots, is essential for promoting tree growth. To establish this symbiotic relationship, fungal symbionts must initiate and sustain mutualistic interactions with host plants while avoiding host defense responses. This study investigated the role of reactive oxygen species (ROS) generated by fungal NADPH oxidase (Nox) in the development of Laccaria bicolor/Populus tremula × alba symbiosis. Our findings revealed that L. bicolor LbNox expression was significantly higher in ectomycorrhizal roots than in free-living mycelia. RNAi was used to silence LbNox, which resulted in decreased ROS signaling, limited formation of the Hartig net, and a lower mycorrhizal formation rate. Using Y2H library screening, BiFC and Co-IP, we demonstrated an interaction between the mitogen-activated protein kinase LbSakA and LbNoxR. LbSakA-mediated phosphorylation of LbNoxR at T409, T477 and T480 positively modulates LbNox activity, ROS accumulation and upregulation of symbiosis-related genes involved in dampening host defense reactions. These results demonstrate that regulation of fungal ROS metabolism is critical for maintaining the mutualistic interaction between L. bicolor and P. tremula × alba. Our findings also highlight a novel and complex regulatory mechanism governing the development of symbiosis, involving both transcriptional and posttranslational regulation of gene networks., (© 2024 The Authors. New Phytologist © 2024 New Phytologist Foundation.)

Smk1 is a MAPK homolog in the yeast Saccharomyces cerevisiae that controls the postmeiotic program of spore wall assembly. During this program, haploid cells are surrounded by a layer of mannan and then a layer of glucan. These inner layers of the spore wall resemble the vegetative cell wall. Next, the outer layers consisting of chitin/chitosan and then dityrosine are assembled. The outer layers are spore-specific and provide protection against environmental stressors. Smk1 is required for the proper assembly of spore walls. However, the protective properties of the outer layers have limited our understanding of how Smk1 controls this morphogenetic program. Mutants lacking the chitin deacetylases, Cda1 and Cda2, form spores that lack the outer layers of the spore wall. In this study, cda1,2∆ cells were used to demonstrate that Smk1 promotes deposition of the glucan layer of the spore wall through the partially redundant glucan synthases Gsc2 and Fks3. Although Gsc2 is localized to sites of spore wall assembly in the wild type, it is mislocalized in the mother cell cytoplasm in the smk1∆ mutant. These findings suggest that Smk1 controls assembly of the spore wall by regulating the localization of Gsc2 during sporogenesis., (© 2024 The Author(s). Yeast published by John Wiley & Sons Ltd.)

Epimedin B (EB), a predominant compound found in Herba Epimedii, has been shown to be effective in the treatment of osteoporosis and peripheral neuropathy. However, the anti-inflammatory effect of EB has not yet been reported. The anti-inflammatory activity of EB was evaluated in a zebrafish inflammation model induced by copper sulfate (CuSO 4 ) and tail cutting. Our findings demonstrated that EB effectively inhibited acute inflammation, mitigated the accumulation of reactive oxygen species (ROS), and ameliorated the neuroinflammation-associated impairment of locomotion in zebrafish. Moreover, EB regulates several genes related to the mitogen-activated protein kinase (MAPK)/nuclear factor-κB (NF-κB)/Nod-like receptor signalling pathways (mapk8b, src, mmp9, akt1, mapk14a, mapk14b, mapk1, egfra, map3k4, nfκb2, iκbαa, pycard, nlrp3 and caspase1) and inflammatory cytokine (stat6, arg1, irfɑ, stat1ɑ, il-1β, il-4, il-6, il-8, cox-2, ptges, tnf-α and tgf-β). Therefore, our findings indicate that EB could serve as a promising therapeutic candidate for treating inflammation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Animal geneticists and breeders have the impending challenge of enhancing the resilience of Indian livestock to heat stress through better selection strategies. Climate change's impact on livestock is more intense in tropical countries like India where dairy cattle crossbreeds are more sensitive to heat stress. The main reason for this study was to find the missing relative changes in transcript levels in thermo-neutral and heat stress conditions in crossbred cattle through whole-transcriptome analysis of RNA-Seq data. Differentially expressed genes (DEGs) identified based on the minimum log twofold change value and false discovery rate 0.05 revealed 468 up-regulated genes and 2273 down-regulated significant genes. Functional annotation and pathway analysis of these significant DEGs were compared based on Gene Ontology (Biological process), Kyoto Encyclopedia of Genes and Genome (KEGG), and Reactome pathways using g: Profiler, ShinyGO v0.76, and iDEP.951 web tools. On finding network visualization, the most over-represented and correlated pathways were neuronal and sensory organ development, calcium signalling pathway, Mitogen-activated protein kinase (MAPK) and Smad signalling pathway, Ras-proximate-1, or Ras-related protein 1 (Rap 1) signalling pathway, apoptosis, and oxidative stress. Similarly, down-regulated genes were most expressed in mRNA processing, immune system, B-cell receptor signalling pathway, Nucleotide oligomerization domain (NOD)-like receptors (NLRs) signalling pathway and nonsense-mediated decay (NMD) pathway. The heat stress-responsive genes identified in this study will facilitate our understanding of the molecular basis for climate resilience and heat tolerance in Indian dairy crossbreeds., (© 2024. The Author(s) under exclusive licence to International Society of Biometeorology.)

The micronutrient iron plays a crucial role in the growth and development of plants, necessitating meticulous regulation for its absorption by plants. Prior research has demonstrated that the transcription factor MxZR3.1 restricts iron absorption in apple rootstocks; however, the precise mechanism by which MxZR3.1 contributes to the regulation of iron homoeostasis in apple rootstocks remains unexplored. Here, MxMPK3-2, a protein kinase, was discovered to interact with MxZR3.1. Y2H, bimolecular fluorescence complementation and pull down experiments were used to confirm the interaction. Phosphorylation and cell semi-degradation tests have shown that MxZR3.1 can be used as a substrate of MxMPK3-2, which leads to the MxZR3.1 protein being more stable. In addition, through tobacco transient transformation (LUC and GUS) experiments, it was confirmed that MxZR3.1 significantly inhibited the activity of the MxHA2 promoter, while MxMPK3-2 mediated phosphorylation at the Ser94 site of MxZR3.1 further inhibited the activity of the MxHA2 promoter. It is tightly controlled to absorb iron during normal growth and development of apple rootstocks due to the regulatory effect of the MxMPK3-2-MxZR3.1 module on MxHA2 transcription level. Consequently, this research has revealed the molecular basis of how the MxMPK3-2-MxZR3.1 module in apple rootstocks controls iron homoeostasis by regulating the MxHA2 promoter's activity., (© 2024 John Wiley & Sons Ltd.)

Replicative senescence is triggered when telomeres reach critically short length and activate permanent DNA damage checkpoint-dependent cell cycle arrest. Mitochondrial dysfunction and increase in oxidative stress are both features of replicative senescence in mammalian cells. However, how reactive oxygen species levels are controlled during senescence is elusive. Here, we show that reactive oxygen species levels increase in the telomerase-negative cells of Saccharomyces cerevisiae during replicative senescence, and that this coincides with the activation of Hog1, a mammalian p38 MAPK ortholog. Hog1 counteracts increased ROS levels during replicative senescence. While Hog1 deletion accelerates replicative senescence, we found this could stem from a reduced cell viability prior to telomerase inactivation. ROS levels also increase upon telomerase inactivation when Mec1, the yeast ortholog of ATR, is mutated, suggesting that oxidative stress is not simply a consequence of DNA damage checkpoint activation in budding yeast. We speculate that oxidative stress is a conserved hallmark of telomerase-negative eukaryote cells, and that its sources and consequences can be dissected in S. cerevisiae., (© 2024. The Author(s).)

The objective of this Special Issue was to collate recent advances in the understanding of MAPKs' functions, particularly their roles in various pathologies, which constitute one of the most dynamic areas in cell signaling research [...].

Kernel weight is a critical agronomic trait in maize production. Many genes are related to kernel weight but only a few of them have been applied to maize breeding and cultivation. Here, we identify a novel function of maize mitogen-activated protein kinase 6 (ZmMPK6) in the regulation of maize kernel weight. Kernel weight was reduced in zmmpk6 mutants and increased in ZmMPK6-overexpressing lines. In addition, starch granules, starch content, protein content, and grain-filling characteristics were also affected by the ZmMPK6 expression level. ZmMPK6 is mainly localized in the nucleus and cytoplasm, widely distributed across various tissues, and is expressed during kernel development, which is consistent with its role in kernel weight. Thus, these results provide new insights into the role of ZmMPK6, a mitogen-activated protein kinase, in maize kernel weight, and could be applied to further molecular breeding for kernel quality and yield in maize., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Mitogen-activated protein kinase (MAPK) pathways control the response to intrinsic and extrinsic stimuli. In the budding yeast Saccharomyces cerevisiae, cells undergo filamentous growth, which is regulated by the fMAPK pathway. To better understand the regulation of the fMAPK pathway, a genetic screen was performed to identify spontaneous mutants with elevated activity of an fMAPK pathway-dependent growth reporter (ste4  FUS1-HIS3). In total, 159 mutants were isolated and analyzed by secondary screens for invasive growth by the plate-washing assay and filament formation by microscopy. Thirty-two mutants were selected for whole-genome sequencing, which identified new alleles in genes encoding known regulators of the fMAPK pathway. These included gain-of-function alleles in STE11, which encodes the MAPKKK, as well as loss-of-function alleles in KSS1, which encodes the MAP kinase, and loss-of-function alleles in RGA1, which encodes a GTPase-activating protein (GAP) for CDC42. New alleles in previously identified pathway modulators were also uncovered in ALY1, AIM44, RCK2, IRA2, REG1, and in genes that regulate protein folding (KAR2), glycosylation (MNN4), and turnover (BLM10). Mutations leading to C-terminal truncations in the transcription factor Ste12p were also uncovered that resulted in elevated reporter activity, identifying an inhibitory domain of the protein from residues 491 to 688. We also find that a diversity of filamentous growth phenotypes can result from combinatorial effects of multiple mutations and by loss of different regulators of the response. The alleles identified here expand the connections surrounding MAPK pathway regulation and reveal new features of proteins that function in the signaling cascade., Competing Interests: Conflicts of interest The author(s) declare no conflicts of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Genetics Society of America.)

This study aimed to investigate the protective effect and its underlying mechanism of n-butanol extract of Pulsatilla Decoction(BEPD) containing medicinal serum on vaginal epithelial cells under Candida glabrata stimulation via the epidermal growth factor receptor/mitogen activated protein kinase( EGFR/MAPK) pathway based on transcriptomics. A vulvovaginal candidiasis(VVC) mouse model was established first and transcriptome sequencing was performed for the vaginal mucosa tissues to analyze the gene expression differences among the control, VVC model, and BEPD intervention groups. Simultaneously, BEPD-containing serum and fluconazole-containing serum were prepared. A431 cells were divided into the control, model, blank serum, fluconazole-containing serum, BEPD-containing serum, EGFR agonist and EGFR inhibitor groups. Additionally, in vitro experiments were conducted using BEPD-containing serum, fluconazole-containing serum, and an EGFR agonist and inhibitor to investigate the intervention mechanisms of BEPD on C. glabrata-induced vaginal epithelial cell damage. Cell counting kit-8(CCK-8) assay was utilized to determine the safe concentrations of C. glabrata, drug-containing serum, and compounds on A431 cells. Enzyme-linked immunosorbent assay(ELISA)was employed to measure the expression levels of interleukin(IL)-1β, IL-6, granulocyte-macrophage colony-stimulating factor(GMCSF), granulocyte CSF(G-CSF), chemokine(C-X-C motif) ligand 20(CCL20), and lactate dehydrogenase(LDH). Gram staining was used to evaluate the adhesion of C. glabrata to vaginal epithelial cells. Flow cytometry was utilized to assess the effect of C.glabrata on A431 cell apoptosis. Based on the transcriptomics results, immunofluorescence was performed to measure the expressions of p-EGFR and p-ERK1/2 proteins, while Western blot validated the expressions of p-EGFR, p-ERK1/2, p-C-Fos, p-P38, Bax and Bcl-2 proteins. Sequencing results showed that compared with the VVC model, BEPD treatment up-regulated 1 075 genes and downregulated 927 genes, mainly enriched in immune-inflammatory pathways, including MAPK. Mechanistically, BEPD significantly reduced the expression of p-EGFR, p-ERK1/2, p-C-Fos and p-P38, as well as the secretion of IL-1β, IL-6, GM-CSF, G-CSF and CCL20, LDH release induced by C. glabrata, and the adhesion of C. glabrata to A431 cells, suggesting that BEPD exerts a protective effect on vaginal epithelial cells damaged by C. glabrata infection by modulating the EGFR/MAPK axis. In addition, BEPD downregulated the pro-apoptotic protein Bax expression and up-regulated the anti-apoptotic protein Bcl-2 expression, leading to a reduction in C. glabrata-induced cell apoptosis. In conclusion, this study reveals that the intervention of BEPD in C. glabrata-induced VVC may be attributed to its regulation of the EGFR/MAPK pathway, which protects vaginal epithelial cells.

Abscisic acid (ABA) is a phytohormone that promotes leaf senescence in response to environmental stress. We previously identified methyl CpG-binding domain 10 (MBD10) as a phosphoprotein that becomes differentially phosphorylated after ABA treatment in Arabidopsis. ABA-induced leaf senescence was delayed in mbd10 knockout plants but accelerated in MBD10-overexpressing plants, suggesting that MBD10 positively regulates ABA-induced leaf senescence. ABA-induced phosphorylation of MBD10 occurs in planta on Thr-89, and our results demonstrated that Thr-89 phosphorylation is essential for MBD10's function in leaf senescence. The in vivo phosphorylation of Thr-89 in MBD10 was significantly downregulated in a quadruple mutant of group C MAPKs (mpk1/2/7/14), and group C MAPKs directly phosphorylated MBD10 in vitro. Furthermore, mpk1/2/7/14 showed a similar phenotype as seen in mbd10 for ABA-induced leaf senescence, suggesting that group C MAPKs are the cognate kinases of MBD10 for Thr-89. Because group C MAPKs have been reported to function downstream of SnRK2s, our results indicate that group C MAPKs and MBD10 constitute a regulatory pathway for ABA-induced leaf senescence., (© 2024 Society for Experimental Biology and John Wiley & Sons Ltd.)

Purpose: The National Cancer Institute-Children's Oncology Group (NCI-COG) Pediatric MATCH trial assigns patients age 1-21 years with refractory malignancies to phase II treatment arms of molecularly targeted therapies on the basis of genetic alterations detected in their tumor. Patients with activating alterations in the mitogen-activated protein kinase pathway were treated with ulixertinib, an extracellular signal-regulated kinase (ERK)1/2 inhibitor., Methods: As there were no previous pediatric data, ulixertinib was initially tested in a dose escalation cohort to establish the recommended phase II dose (RP2D) before proceeding to the phase II cohort. Ulixertinib was administered at 260 mg/m 2 /dose orally twice a day (dose level 1 [DL1], n = 15) or 350 mg/m 2 /dose orally twice a day (DL2, n = 5). The primary end point was objective response rate; secondary end points included safety/tolerability and progression-free survival (PFS)., Results: Twenty patients (median 12 years; range, 5-20) were treated, all evaluable for response. CNS tumors comprised 55% (11/20) of diagnoses, with high-grade glioma and low-grade glioma most common (n = 5 each). All CNS tumors except one harbored BRAF fusions or V600E mutations. Rhabdomyosarcoma (n = 5) was the most frequent non-CNS diagnosis. DL1 was declared the RP2D in the dose escalation cohort after dose-limiting toxicities in Cycle 1 occurred in 1/6 patients at DL1 and 2/5 patients at DL2, including fatigue, anorexia, rash, nausea, vomiting, diarrhea, dehydration, hypoalbuminemia, and hypernatremia. No objective responses were observed. Six-month PFS was 37% (95% CI, 17 to 58). Three patients with BRAF -altered CNS tumors achieved stable disease >6 months., Conclusion: Ulixertinib, a novel targeted agent with no previous pediatric data, was successfully evaluated in a national precision medicine basket trial. The pediatric RP2D of ulixertinib is 260 mg/m 2 /dose orally twice a day. Limited single-agent efficacy was observed in a biomarker-selected cohort of refractory pediatric tumors.

Disruptor of telomeric silencing 1 (Dot1p) is an exquisitely conserved histone methyltransferase and is the sole enzyme responsible for H3K79 methylation in the budding yeast Saccharomyces cerevisiae. It has been shown to be highly phosphorylated in vivo; however, the upstream kinases that act on Dot1p are almost entirely unknown in yeast and all other eukaryotes. Here, we used in vitro and in vivo kinase discovery approaches to show that mitogen-activated protein kinase HOG1 (Hog1p) is a bona fide kinase of the Dot1p methyltransferase. In vitro kinase assays showed that Hog1p phosphorylates Dot1p at multiple sites, including at several proline-adjacent sites that are consistent with known Hog1p substrate preferences. The activity of Hog1p was specifically enhanced at these proline-adjacent sites on Dot1p upon Hog1p activation by the osmostress-responsive MAP kinase kinase PBS2 (Pbs2p). Genomic deletion of HOG1 reduced phosphorylation at specific sites on Dot1p in vivo, providing further evidence for Hog1p kinase activity on Dot1p in budding yeast cells. Phenotypic analysis of knockout and phosphosite mutant yeast strains revealed the importance of Hog1p-catalysed phosphorylation of Dot1p for cellular responses to ultraviolet-induced DNA damage. In mammalian systems, this kinase-substrate relationship was found to be conserved: human DOT1L (the ortholog of yeast Dot1p) can be phosphorylated by the proline-directed kinase p38β (also known as MAPK11; the ortholog of yeast Hog1p) at multiple sites in vitro. Taken together, our findings establish Hog1p and p38β as newly identified upstream kinases of the Dot1p/DOT1L H3K79 methyltransferase enzymes in eukaryotes., (© 2024 The Authors. The FEBS Journal published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)

CgHog1, terminal kinase of the high-osmolarity glycerol signalling pathway, orchestrates cellular response to multiple external stimuli including surplus-environmental iron in the human fungal pathogen Candida glabrata (Cg). However, CgHog1 substrates remain unidentified. Here, we show that CgHog1 adversely affects Cg adherence to host stomach and kidney epithelial cells in vitro, but promotes Cg survival in the iron-rich gastrointestinal tract niche. Further, CgHog1 interactome and in vitro phosphorylation analysis revealed CgSub2 (putative RNA helicase) to be a CgHog1 substrate, with CgSub2 also governing iron homeostasis and host adhesion. CgSub2 positively regulated EPA1 (encodes a major adhesin) expression and host adherence via its interactor CgHtz1 (histone H2A variant). Notably, both CgHog1 and surplus environmental iron had a negative impact on CgSub2-CgHtz1 interaction, with CgHTZ1 or CgSUB2 deletion reversing the elevated adherence of Cghog1Δ to epithelial cells. Finally, the surplus-extracellular iron led to CgHog1 activation, increased CgSub2 phosphorylation, elevated CgSub2-CgHta (canonical histone H2A) interaction, and EPA1 transcriptional activation, thereby underscoring the iron-responsive, CgHog1-induced exchange of histone partners of CgSub2. Altogether, our work mechanistically defines how CgHog1 couples Epa1 adhesin expression with iron abundance, and point towards specific chromatin composition modification programs that probably aid fungal pathogens align their adherence to iron-rich (gut) and iron-poor (blood) host niches., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Sahu et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Trichophyton rubrum is a human fungal pathogen that causes dermatophytosis, an infection that affects keratinized tissues. Integrated molecular signals coordinate mechanisms that control pathogenicity. Transcriptional regulation is a core regulation of relevant fungal processes. Previous RNA sequencing data revealed that the absence of the transcription factor StuA resulted in the differential expression of the MAPK-related high glycerol osmolarity gene (hog1) in T. rubrum. Here we validated the role of StuA in regulating the transcript levels of hog1. We showed through RT-qPCR that transcriptional regulation controls hog1 levels in response to glucose, keratin, and co-culture with human keratinocytes. In addition, we also detected hog1 pre-mRNA transcripts that underwent alternative splicing, presenting intron retention in a StuA-dependent mechanism. Our findings suggest that StuA and alternative splicing simultaneously, but not dependently, coordinate hog1 transcript levels in T. rubrum. As a means of preventing and treating dermatophytosis, our results contribute to the search for new potential drug therapies based on the molecular aspects of signaling pathways in T. rubrum., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)