Search

The SARS-CoV-2 pandemic alerted the potential for significant harm due to future cross-species transmission of various animal coronaviruses to human. There is a significant need of antibody-based drugs to treat patients infected with previously unseen coronaviruses. In this study, we generated CV804, an antibody that binds to the S2 domain of SARS-CoV-2 spike protein, which is highly conserved across the coronavirus family and less susceptible to mutations. CV804 demonstrated broad cross-reactivities not only disease-associated human beta coronaviruses including SARS-CoV, MERS-CoV, HCoV-OC43, HCoV-HKU1 and with existing mutant strains of SARS-CoV-2 and but also with 20 representative animal-origin coronaviruses. CV804 exhibits strong antibody-dependent cellular cytotoxicity (ADCC) to SARS-CoV-2 spike protein expressed on cells in vitro, while completely lacks virus-neutralization activity. In animal models, CV804 suppressed disease progression caused by SARS-CoV-2 infection. Structural studies using HDX-MS combined with reactivity analysis with point mutants of recombinant spike proteins revealed that CV804 binds to a unique conformational epitope within the S2 domain of the spike proteins that is highly conserved among various coronaviruses. Overall, obtained data suggest that the non-neutralizing CV804 antibody recognizes the conformational structure of the spike protein displayed on the surface of infected cells and weakens the viral virulence by supporting the host immune cells' attack through ADCC activity in vivo. The CV804 epitope information revealed in this study is useful for designing pan-corona antibody therapeutics and universal coronavirus vaccines for preparing potential future pandemics. [ABSTRACT FROM AUTHOR]

The importance of treating non‐pulmonary vein (PV) foci is increasing with improvements in the durability of PV isolation. We describe two cases wherein non‐PV foci were induced by mechanical irritation and conventional induction in the same area, which was impossible to induce after ablation, suggesting a relationship between mechanical irritation and induction of non‐PV foci. In a recurrent case of non‐PV foci, atrial fibrillation (AF) was induced only by mechanical irritation. No recurrence has been observed since the ablation of the area. Thus, treatment of the AF induction site with mechanical irritation could be considered an effective therapy for non‐PV foci. [ABSTRACT FROM AUTHOR]

Most autophagy-related genes, or ATG genes, have been identified through studies using budding yeast. Although the functions of the ATG genes are well understood, the contributions of individual genes to non-selective and various types of selective autophagy remain to be fully elucidated. In this study, we quantified the activity of non-selective autophagy, the cytoplasm-to-vacuole targeting (Cvt) pathway, mitophagy, endoplasmic reticulum (ER)-phagy and pexophagy in all Saccharomyces cerevisiae atg mutants. Among the mutants of the core autophagy genes considered essential for autophagy, the atg13 mutant and mutants of the genes involved in the two ubiquitin-like conjugation systems retained residual autophagic functionality. In particular, mutants of the Atg8 ubiquitin-like conjugation system (the Atg8 system) exhibited substantial levels of non-selective autophagy, the Cvt pathway and pexophagy, although mitophagy and ER-phagy were undetectable. Atg8-system mutants also displayed intravacuolar vesicles resembling autophagic bodies, albeit at significantly reduced size and frequency. Thus, our data suggest that membranous sequestration and vacuolar delivery of autophagic cargo can occur in the absence of the Atg8 system. Alongside these findings, the comprehensive analysis conducted here provides valuable datasets for future autophagy research. [ABSTRACT FROM AUTHOR]

The endoplasmic reticulum (ER) undergoes selective autophagy called reticulophagy or ER-phagy. Multiple reticulon- and receptor expression enhancing protein (REEP)-like ER-shaping proteins, including budding yeast Atg40, serve as reticulophagy receptors that stabilize the phagophore on the ER by interacting with phagophore-conjugated Atg8. Additionally, they facilitate phagophore engulfment of the ER by remodeling ER morphology. We reveal that Hva22, a REEP family protein in fission yeast, promotes reticulophagy without Atg8-binding capacity. The role of Hva22 in reticulophagy can be replaced by expressing Atg40 independently of its Atg8-binding ability. Conversely, adding an Atg8-binding sequence to Hva22 enables it to substitute for Atg40 in budding yeast. Thus, the phagophore-stabilizing and ER-shaping activities, both of which Atg40 solely contains, are divided between two separate factors, receptors and Hva22, respectively, in fission yeast. Abbreviations: AIM: Atg8-family interacting motif; Atg: autophagy related; DTT: dithiothreitol; ER: endoplasmic reticulum GFP: green fluorescent protein; NAA: 1-naphthaleneacetic acid; REEP: receptor expression enhancing protein; RFP: red fluorescent protein; UPR: unfolded protein response. [ABSTRACT FROM AUTHOR]

Muscle disuse induces atrophy through increased reactive oxygen species (ROS) released from damaged mitochondria. Mitophagy, the autophagic degradation of mitochondria, is associated with increased ROS production. However, the mitophagy activity status during disuse‐induced muscle atrophy has been a subject of debate. Here, we developed a new mitophagy reporter mouse line to examine how disuse affected mitophagy activity in skeletal muscles. Mice expressing tandem mCherry‐EGFP proteins on mitochondria were then used to monitor the dynamics of mitophagy activity. The reporter mice demonstrated enhanced mitophagy activity and increased ROS production in atrophic soleus muscles following a 14‐day hindlimb immobilization. Results also showed an increased expression of multiple mitophagy genes, including Bnip3, Bnip3l, and Park2. Our findings thus conclude that disuse enhances mitophagy activity and ROS production in atrophic skeletal muscles and suggests that mitophagy is a potential therapeutic target for disuse‐induced muscle atrophy. [ABSTRACT FROM AUTHOR]

We describe an autopsy case of a 75-year-old female with limited cutaneous systemic sclerosis (lcSSc) and gangrene due to macrovascular involvement. She was diagnosed with lcSSc complicated with pulmonary arterial hypertension and digital ulcers 9 years before admission. She had recurrent and refractory lower limb ulcers (LLUs), and died because of sepsis caused by gangrene infection. Autopsy findings revealed severely thickened arterial walls of the visceral organs, consistent with vascular involvement of SSc. Systemic vascular involvement in lcSSc may progress in patients with LLUs who harbour several risk factors for vascular involvement. [ABSTRACT FROM AUTHOR]

Mitochondria produce the majority of ATP required by cells via oxidative phosphorylation. Therefore, regulation of mitochondrial quality and quantity is important for maintaining cellular activities. Mitophagy, the selective degradation of mitochondria, is thought to contribute to control of mitochondrial quality and quantity. In recent years, the molecular mechanism of mitophagy has been extensively studied in yeast and mammalian cells. In particular, identification of the mitophagy receptor Atg32 has contributed to substantial progress in understanding of mitophagy in yeast. This review summarizes the molecular mechanism of mitophagy in yeast and compares it to the mechanism of mitophagy in mammals. We also discuss the current understanding of mitophagy in plants. [ABSTRACT FROM AUTHOR]

Abstract: The fungicide fludioxonil is used to control plant-pathogenic fungi by causing improper activation of the Hog1-type MAPK. However, the appearance of fludioxonil resistant mutants, mostly caused by mutations in the group III histidine kinases, poses a serious problem. Moreover, such mutations cause also hyperosmotic sensitivity and the underlying mechanism has been elusive for a long time. Using Saccharomyces cerevisiae as an experimental host, we show that those phenotypes are conferred by a constitutively active form of the group III histidine kinase. Our results explain the different reasons for fludioxonil resistance conferred by its deletion and missense mutation. [Copyright &y& Elsevier]

Yeast cells undergo diploid-specific developments such as spore formation via meiosis and pseudohyphal development under certain nutrient-limited conditions. Studies on these aspects require homozygous diploid mutants, which are generally constructed by crossing strains of opposite mating-type with the same genetic mutation. So far, there has been no direct way to generate and select diploids from haploid cells. Here, we developed a method for efficient construction of homozygous diploids using a PGAL1-HO gene (galactose-inducible mating-type switch) and a PSTE18-URA3 gene (counter selection marker for diploids). Diploids are generated by transient induction of the HO endonuclease, which is followed by mating of part of the haploid population. Since the STE18 promoter is repressed in diploids, diploids carrying PSTE18-URA3 can be selected on 5-fluoroorotic acid (5-FOA) plates where the uracil prototrophic haploids cannot grow. To demonstrate that this method is useful for genetic studies, we screened suppressor mutations of the complex colony morphology, strong agar invasion and/or hyper-filamentous growth caused by lack of the Hog1 MAPK in the diploid Σ1278b strain background. Following this approach, we identified 49 suppressor mutations. Those include well-known positive regulator genes for filamentous growth signaling pathways, genes involved in mitochondrial function, DNA damage checkpoint, chromatin remodeling, and cell cycle, and also previously uncharacterized genes. Our results indicate that combinatorial use of the PGAL1-HO and PSTE18-URA3 genes is suitable to efficiently construct and select diploids and that this approach is useful for genetic studies especially when combined with large-scale screening. [ABSTRACT FROM AUTHOR]

The article presents a study which examined the suppression of phenotypes of the kexB disruptant in Aspergillus oryzae and Aspergillus nidulas under hyperosmotic conditions. Suppression mechanism of the oryzapsins and processing of recombinant fusion protein were analyzed. Results show that kexB phenotypes were not suppressed by oryzapsins, but the recombinant fusion proteins were cleaved, and concludes that an alternative processing protease in the Aspergillus fungi is possible.

The article discusses a study which presents novel reporter systems for monitoring activation of the Aspergillus nidulans high-osmolarity glycerol response (AnHOG) pathway. It is stated that AnHOG pathway involved in osmoadaptation. The study found that fludioxonil causes improper activation of HogA mitogen-activated protein kinase in A. nidulans. The results indicate that the reporter activity is regulated via HogA activation.

The article examines the role of SskA ad SrrA response regulators in oxidative stress responses of hyphae and asexual spores in the phosphorelay signaling network of fungus Aspergillus nidulans. According to the authors, expression of the vegetative-stage specific catB catalase gene was severely impaired in both mutants. They add the results of the study indicate the physiological importance of the His-Asp phosphorelay signaling network involving the SskA and SrrA response regulators.

Genome sequencing analyses revealed thatAspergillus nidulanshas orthologous genes to all those of the high-osmolarity glycerol (HOG) response mitogen-activated protein kinase (MAPK) pathway ofSaccharomyces cerevisiae.A. nidulansmutant strains lackingsskA,sskB,pbsB,orhogA, encoding proteins orthologous to the yeast Ssk1p response regulator, Ssk2p/Ssk22p MAPKKKs, Pbs2p MAPKK and Hog1p MAPK, respectively, showed growth inhibition under high osmolarity, and HogA MAPK in these mutants was not phosphorylated under osmotic or oxidative stress. Thus, activation of theA. nidulansHOG (AnHOG) pathway depends solely on the two-component signalling system, and MAPKK activation mechanisms in the AnHOG pathway differ from those in the yeast HOG pathway, where Pbs2p is activated by two branches, Sln1p and Sho1p. Expression ofpbsBcomplemented the high-osmolarity sensitivity of yeastpbs2Δ, and the complementation depended on Ssk2p/Ssk22p, but not on Sho1p. Pbs2p requires its Pro-rich motif for binding to the Src-homology3 (SH3) domain of Sho1p, but PbsB lacks a typical Pro-rich motif. However, a PbsB mutant (PbsB(Pro)) with the yeast Pro-rich motif was activated by the Sho1p branch in yeast. In contrast, HogA insskAΔ expressing PbsB(Pro) was not phosphorylated under osmotic stress, suggesting thatA. nidulansShoA, orthologous to yeast Sho1p, is not involved in osmoresponsive activation of the AnHOG pathway. We also found that besides HogA, PbsB can activate another Hog1p MAPK orthologue, MpkC, inA. nidulans, althoughmpkCis dispensable in osmoadaptation. In this study, we discuss the differences between the AnHOG and the yeast HOG pathways. [ABSTRACT FROM AUTHOR]

Reports on the isolation and functional analysis of a gene, tcsB, by encoding a transmembrane hybrid-type histidine kinase from Aspergillus nidulans. TcsB encoding of an A. nidulans hybrid-type histidine kinase; Strains, media and growth conditions; Molecular cloning and sequencing of tcsB gene.

The article analyzes a histidine protein kinase, NikA, that is found in many fungi, with special reference to responses to potent fungicides, iprodione and fluodioxonil. According to the authors, NikA and two downstream response regulators are crucially implicated in the mode of action of fungicides and that the further downstream HogA-mitogen activated protein kinase cascade is exaggerated abnormally in hyphase by the fungicides in a manner dependent on the NikA-SskA phosphorelay.

We talk to corresponding author Tomotake Kanki and co-first authors Tomoyuki Fukuda and Kentaro Furukawa about their paper "The mitochondrial intermembrane space protein mitofissin drives mitochondrial fission required for mitophagy" (this issue of Molecular Cell), their career paths, interests outside of their fields, and how they strike a work-life balance. [ABSTRACT FROM AUTHOR]