Search

T cells and their derived cytokines have been shown to modulate brain function. In this issue of Cell , Zhu, Yan, and colleagues demonstrate that opioid use impacts the crosstalk between the CNS and the peripheral immune system. Regulatory T cell (Treg)-derived IFN-γ signaling translates into synaptic weakening in the nucleus accumbens (NAc) to impart withdrawal-induced behavioral dysfunction. [ABSTRACT FROM AUTHOR]

Plant pathogenic bacteria deliver effectors into plant cells to suppress immunity and promote pathogen survival; however, these effectors can be recognized by plant disease resistance proteins to activate innate immunity. The bacterial acetyltransferase effectors HopZ5 and AvrBsT trigger immunity in Arabidopsis thaliana genotypes lacking SUPPRESSOR OF AVRBST-ELICITED RESISTANCE 1 (SOBER1). Using an Arabidopsis accession, Tscha-1, that naturally lacks functional SOBER1 but is unable to recognize HopZ5, we demonstrated that RESISTANCE TO P. SYRINGAE PV MACULICOLA 1 (RPM1) and RPM1-INTERACTING PROTEIN 4 (RIN4) are indispensable for HopZ5- or AvrBsT-triggered immunity. Remarkably, T166 of RIN4, the phosphorylation of which is induced by AvrB and AvrRpm1, is directly acetylated by HopZ5 and AvrBsT. Furthermore, we demonstrated that the acetylation of RIN4 T166 is required and sufficient for HopZ5- or AvrBsT-triggered RPM1-dependent defense activation. Finally, we showed that SOBER1 interferes with HopZ5- or AvrBsT-triggered immunity by deacetylating RIN4 T166. Collectively, our study elucidates detailed molecular mechanisms underlying the activation and suppression of plant innate immunity triggered by two bacterial acetyltransferases, HopZ5 and AvrBsT, from different bacterial pathogens. Pathogen effector-induced biochemical modifications of host target proteins can activate NLR-mediated plant immunity. This study shows the molecular mechanism by which an Arabidopsis NLR immune receptor, RPM1, is activated by sensing RIN4 acetylation directed by two bacterial acetyltransferase effectors, HopZ5 and AvrBsT. An Arabidopsis deacetylase, SOBER1, interferes with HopZ5- or AvrBsT-triggered immunity by deacetylation of RIN4. [ABSTRACT FROM AUTHOR]

Reactive oxygen signaling regulates numerous biological processes, including stress responses in plants. Redox sensors transduce reactive oxygen signals into cellular responses. Here, we present biochemical evidence that a plant quiescin sulfhydryl oxidase homolog (QSOX1) is a redox sensor that negatively regulates plant immunity against a bacterial pathogen. The expression level of QSOX1 is inversely correlated with pathogen-induced reactive oxygen species (ROS) accumulation. Interestingly, QSOX1 both senses and regulates ROS levels by interactingn with and mediating redox regulation of S-nitrosoglutathione reductase, which, consistent with previous findings, influences reactive nitrogen-mediated regulation of ROS generation. Collectively, our data indicate that QSOX1 is a redox sensor that negatively regulates plant immunity by linking reactive oxygen and reactive nitrogen signaling to limit ROS production. This study identifies QSOX1 as a redox sensor protein that mediates feedback inhibition of defense-associated reactive oxygen production and negatively regulates plant immunity by transducing an initial burst of reactive oxygen into an oxidative relay. The activity of QSOX1 eventually limits the ongoing reactive oxygen production by linking an initial reactive oxygen burst to reactive nitrogen signaling. [ABSTRACT FROM AUTHOR]

Host and microbe cooperate to generate bioactive metabolites with significant scientific and clinical importance. In this issue of Cell Host & Microbe , Zhu, Dwidar et al. identify parallel microbial pathways that transform dietary amino acids into the precursors of deleterious host-derived metabolites and confirm their correlation to adverse cardiovascular health. [ABSTRACT FROM AUTHOR]

Summary Metagenomic studies show that diverse resident viruses inhabit the healthy gut; however, little is known about the role of these viruses in the maintenance of gut homeostasis. We found that mice treated with antiviral cocktail displayed more severe dextran sulfate sodium (DSS)-induced colitis compared with untreated mice. DSS-induced colitis was associated with altered enteric viral abundance and composition. When wild-type mice were reconstituted with Toll-like receptor 3 (TLR3) or TLR7 agonists or inactivated rotavirus, colitis symptoms were significantly ameliorated. Mice deficient in both TLR3 and TLR7 were more susceptible to DSS-induced experimental colitis. In humans, combined TLR3 and TLR7 genetic variations significantly influenced the severity of ulcerative colitis. Plasmacytoid dendritic cells isolated from inflamed mouse colon produced interferon-β in a TLR3 and TLR7-dependent manner. These results imply that recognition of resident viruses by TLR3 and TLR7 is required for protective immunity during gut inflammation. [ABSTRACT FROM AUTHOR]

Summary Interleukin-17A (IL-17A) is a pro-inflammatory cytokine linked to rapid malignant progression of colorectal cancer (CRC) and therapy resistance. IL-17A exerts its pro-tumorigenic activity through its type A receptor (IL-17RA). However, IL-17RA is expressed in many cell types, including hematopoietic, fibroblastoid, and epithelial cells, in the tumor microenvironment, and how IL-17RA engagement promotes colonic tumorigenesis is unknown. Here we show that IL-17RA signals directly within transformed colonic epithelial cells (enterocytes) to promote early tumor development. IL-17RA engagement activates ERK, p38 MAPK, and NF-κB signaling and promotes the proliferation of tumorigenic enterocytes that just lost expression of the APC tumor suppressor. Although IL-17RA signaling also controls the production of IL-6, this mechanism makes only a partial contribution to colonic tumorigenesis. Combined treatment with chemotherapy, which induces IL-17A expression, and an IL-17A neutralizing antibody enhanced the therapeutic responsiveness of established colon tumors. These findings establish IL-17A and IL-17RA as therapeutic targets in colorectal cancer. [ABSTRACT FROM AUTHOR]

Plant cells have two defense systems that detect bacterial pathogens. One is a basal defense system that recognizes complex pathogen-associated molecular patterns (PAMPs). A second system uses disease-resistance (R) proteins to recognize type III effector proteins that are delivered into the plant cell by the pathogen's type III secretion system. Here we show that these two pathways are linked. We find that two Pseudomonas syringae type III effectors, AvrRpt2 and AvrRpm1, inhibit PAMP-induced signaling and thus compromise the host's basal defense system. RIN4 is an Arabidopsis protein targeted by AvrRpt2 and AvrRpm1 for degradation and phosphorylation, respectively. We find that RIN4 is itself a regulator of PAMP signaling. The R proteins, RPS2 and RPM1, sense type III effector-induced perturbations of RIN4. Thus, R proteins guard the plant against type III effectors that inhibit PAMP signaling and provide a mechanistic link between the two plant defense systems. [ABSTRACT FROM AUTHOR]

Children with inflammatory bowel diseases (IBD) are particularly vulnerable to infection with Clostridioides difficile (CDI). IBD and IBD + CDI have overlapping symptoms but respond to distinctive treatments, highlighting the need for diagnostic biomarkers. Here, we studied pediatric patients with IBD and IBD + CDI, comparing longitudinal data on the gut microbiome, metabolome, and other measures. The microbiome is dysbiotic and heterogeneous in both disease states, but the metabolome reveals disease-specific patterns. The IBD group shows increased concentrations of markers of inflammation and tissue damage compared with healthy controls, and metabolic changes associate with susceptibility to CDI. In IBD + CDI, we detect both metabolites associated with inflammation/tissue damage and fermentation products produced by C. difficile. The most discriminating metabolite found is isocaproyltaurine, a covalent conjugate of a distinctive C. difficile fermentation product (isocaproate) and an amino acid associated with tissue damage (taurine), which may be useful as a joint marker of the two disease processes. • Multi-omics reveals markers of CDI in pediatric IBD patients • Identification of metabolites reveals distinctive features for IBD and CDI • Isocaproyltaurine is made by C. difficile and associates with active IBD • Identifies biomarkers potentially useful for distinguishing disease processes Children with inflammatory bowel diseases (IBD) are prone to infection with C. difficile (CDI). Bushman et al. report the microbiome and metabolome of children with IBD or IBD + CDI, revealing distinctive metabolites associated with the two disease processes that may be useful as biomarkers to guide targeted therapy. [ABSTRACT FROM AUTHOR]

Summary To initiate V(D)J recombination for generating the adaptive immune response of vertebrates, RAG1/2 recombinase cleaves DNA at a pair of recombination signal sequences, the 12- and 23-RSS. We have determined crystal and cryo-EM structures of RAG1/2 with DNA in the pre-reaction and hairpin-forming complexes up to 2.75 Å resolution. Both protein and DNA exhibit structural plasticity and undergo dramatic conformational changes. Coding-flank DNAs extensively rotate, shift, and deform for nicking and hairpin formation. Two intertwined RAG1 subunits crisscross four times between the asymmetric pair of severely bent 12/23-RSS DNAs. Location-sensitive bending of 60° and 150° in 12- and 23-RSS spacers, respectively, must occur for RAG1/2 to capture the nonamers and pair the heptamers for symmetric double-strand breakage. DNA pairing is thus sequence-context dependent and structure specific, which partly explains the “beyond 12/23” restriction. Finally, catalysis in crystallo reveals the process of DNA hairpin formation and its stabilization by interleaved base stacking. [ABSTRACT FROM AUTHOR]

Recent single-cell RNA sequencing studies have revealed distinct microglial states in development and disease. These include proliferative-region-associated microglia (PAMs) in developing white matter and disease-associated microglia (DAMs) prevalent in various neurodegenerative conditions. PAMs and DAMs share a similar core gene signature. However, the extent of the dynamism and plasticity of these microglial states, as well as their functional significance, remains elusive, partly due to the lack of specific tools. Here, we generated an inducible Cre driver line, Clec7a-CreERT2, that targets PAMs and DAMs in the brain parenchyma. Utilizing this tool, we profiled labeled cells during development and in several disease models, uncovering convergence and context-dependent differences in PAM and DAM gene expression. Through long-term tracking, we demonstrated microglial state plasticity. Lastly, we specifically depleted DAMs in demyelination, revealing their roles in disease recovery. Together, we provide a versatile genetic tool to characterize microglial states in CNS development and disease. [Display omitted] • Generation of a Clec7a-CreERT2 mouse model to study specific microglial states • scRNA-seq of labeled PAMs and DAMs reveals convergent and divergent gene signatures • Tracking microglial states in vivo reveals context-dependent plasticity • State-specific ablation shows DAMs are protective and required for remyelination Microglia are heterogeneous cells that underlie numerous roles in brain development and neurodegenerative disease. Barclay et al. generate Clec7a-CreERT2 mice to profile, track, and deplete two microglial states, proliferative-region-associated microglia (PAMs) and disease-associated microglia (DAMs), revealing the convergence and divergence of PAM and DAM signatures, context-dependent microglial state plasticity, and a protective role for DAMs during myelin repair. [ABSTRACT FROM AUTHOR]

Summary: The receptor-evoked Ca2+ signal includes activation of the store-operated channels (SOCs) TRPCs and the Orais. Although both are gated by STIM1, it is not known how STIM1 gates the channels and whether STIM1 gates the TRPCs and Orais by the same mechanism. Here, we report the molecular mechanism by which STIM1 gates TRPC1, which involves interaction between two conserved, negatively charged aspartates in TRPC1(639DD640) with the positively charged STIM1(684KK685) in STIM1 polybasic domain. Charge swapping and functional analysis revealed that exact orientation of the charges on TRPC1 and STIM1 are required, but all positive-negative charge combinations on TRPC1 and STIM1, except STIM1(684EE685)+TRPC1(639RR640), are functional as long as they are reciprocal, indicating that STIM1 gates TRPC1 by intermolecular electrostatic interaction. Similar gating was observed with TRPC3(697DD698). STIM1 gates Orai1 by a different mechanism since the polybasic and S/P domains of STIM1 are not required for activation of Orai1 by STIM1. [Copyright &y& Elsevier]

CAD/DFF40 is responsible for the degradation of chromosomal DNA into nucleosomal fragments and subsequent chromatin condensation during apoptosis. It exists as an inactive complex with its inhibitor ICAD/DFF45 in proliferating cells but becomes activated upon cleavage of ICAD/DFF45 into three domains by caspases in dying cells. The molecular mechanism underlying the control and activation of CAD/DFF40 was unknown. Here, the crystal structure of activated CAD/DFF40 reveals that it is a pair of molecular scissors with a deep active-site crevice that appears ideal for distinguishing internucleosomal DNA from nucleosomal DNA. Ensuing studies show that ICAD/DFF45 sequesters the nonfunctional CAD/DFF40 monomer and is also able to disassemble the functional CAD/DFF40 dimer. This capacity requires the involvement of the middle domain of ICAD/DFF45, which by itself cannot remain bound to CAD/DFF40 due to low binding affinity for the enzyme. Thus, the consequence of the caspase-cleavage of ICAD/DFF45 is a self-assembly of CAD/DFF40 into the active dimer. [Copyright &y& Elsevier]

Despite recent advancements in identifying engram cells, our understanding of their regulatory and functional mechanisms remains in its infancy. To provide mechanistic insight into engram cell functioning, we introduced a novel local microcircuit labeling technique that enables the labeling of intraregional synaptic connections. Utilizing this approach, we discovered a unique population of somatostatin (SOM) interneurons in the mouse basolateral amygdala (BLA). These neurons are activated during fear memory formation and exhibit a preference for forming synapses with excitatory engram neurons. Post-activation, these SOM neurons displayed varying excitability based on fear memory retrieval. Furthermore, when we modulated these SOM neurons chemogenetically, we observed changes in the expression of fear-related behaviors, both in a fear-associated context and in a novel setting. Our findings suggest that these activated SOM interneurons play a pivotal role in modulating engram cell activity. They influence the expression of fear-related behaviors through a mechanism that is dependent on memory cues. • LCD-eGRASP enables intraregional synaptic labeling between two different cell types • Activated SOM (SOMact) has stronger synaptic connection with excitatory engram neurons • Fear memory retrieval decreases SOMact excitability • Inhibition of SOMact promotes fear-related behaviors in mice Engram refers to the physical form of memory stored in the brain. Researchers have identified the engram cells, but it is less known how these engram cells are controlled. Using a novel synapse-labeling method, Kim et al. identified a new population of inhibitory neurons that is involved in fear memory formation and expression of fear-related behaviors in mice. [ABSTRACT FROM AUTHOR]

Chronic stimulation can cause T cell dysfunction and limit the efficacy of cellular immunotherapies. Improved methods are required to compare large numbers of synthetic knockin (KI) sequences to reprogram cell functions. Here, we developed modular pooled KI screening (ModPoKI), an adaptable platform for modular construction of DNA KI libraries using barcoded multicistronic adaptors. We built two ModPoKI libraries of 100 transcription factors (TFs) and 129 natural and synthetic surface receptors (SRs). Over 30 ModPoKI screens across human TCR- and CAR-T cells in diverse conditions identified a transcription factor AP4 (TFAP4) construct that enhanced fitness of chronically stimulated CAR-T cells and anti-cancer function in vitro and in vivo. ModPoKI's modularity allowed us to generate an ∼10,000-member library of TF combinations. Non-viral KI of a combined BATF-TFAP4 polycistronic construct enhanced fitness. Overexpressed BATF and TFAP4 co-occupy and regulate key gene targets to reprogram T cell function. ModPoKI facilitates the discovery of complex gene constructs to program cellular functions. [Display omitted] • Pooled knockin of hundreds of TFs/surface receptors combined with different TCRs/CARs • Chronic stimulation screens discover programs to improve T cell persistence • Combinatorial knockin screens with ∼10,000 transcription factor combinations • BATF-TFAP4 dual knockin construct improves CAR-T cell fitness and function Modular pooled knockin screening (ModPoKI) is an adaptable platform that enables the evaluation of hundreds to thousands of different T cell constructs for engineered cellular immunotherapies. [ABSTRACT FROM AUTHOR]

Summary The RAG1 endonuclease, together with its cofactor RAG2, is essential for V(D)J recombination but is a potent threat to genome stability. The sources of RAG1 mis-targeting and the mechanisms that have evolved to suppress it are poorly understood. Here, we report that RAG1 associates with chromatin at thousands of active promoters and enhancers in the genome of developing lymphocytes. The mouse and human genomes appear to have responded by reducing the abundance of “cryptic” recombination signals near RAG1 binding sites. This depletion operates specifically on the RSS heptamer, whereas nonamers are enriched at RAG1 binding sites. Reversing this RAG-driven depletion of cleavage sites by insertion of strong recombination signals creates an ectopic hub of RAG-mediated V(D)J recombination and chromosomal translocations. Our findings delineate rules governing RAG binding in the genome, identify areas at risk of RAG-mediated damage, and highlight the evolutionary struggle to accommodate programmed DNA damage in developing lymphocytes. [ABSTRACT FROM AUTHOR]

Summary: Mutations in leucine-rich repeat kinase 2 (LRRK2) are a common cause of familial and sporadic Parkinson’s disease (PD). Elevated LRRK2 kinase activity and neurodegeneration are linked, but the phosphosubstrate that connects LRRK2 kinase activity to neurodegeneration is not known. Here, we show that ribosomal protein s15 is a key pathogenic LRRK2 substrate in Drosophila and human neuron PD models. Phosphodeficient s15 carrying a threonine 136 to alanine substitution rescues dopamine neuron degeneration and age-related locomotor deficits in G2019S LRRK2 transgenic Drosophila and substantially reduces G2019S LRRK2-mediated neurite loss and cell death in human dopamine and cortical neurons. Remarkably, pathogenic LRRK2 stimulates both cap-dependent and cap-independent mRNA translation and induces a bulk increase in protein synthesis in Drosophila, which can be prevented by phosphodeficient T136A s15. These results reveal a novel mechanism of PD pathogenesis linked to elevated LRRK2 kinase activity and aberrant protein synthesis in vivo. [ABSTRACT FROM AUTHOR]

Summary: All metazoan guts are subjected to immunologically unique conditions in which an efficient antimicrobial system operates to eliminate pathogens while tolerating symbiotic commensal microbiota. However, the molecular mechanisms controlling this process are only partially understood. Here, we show that bacterial-derived uracil acts as a ligand for dual oxidase (DUOX)-dependent reactive oxygen species generation in Drosophila gut and that the uracil production in bacteria causes inflammation in the gut. The acute and controlled uracil-induced immune response is required for efficient elimination of bacteria, intestinal cell repair, and host survival during infection of nonresident species. Among resident gut microbiota, uracil production is absent in symbionts, allowing harmonious colonization without DUOX activation, whereas uracil release from opportunistic pathobionts provokes chronic inflammation. These results reveal that bacteria with distinct abilities to activate uracil-induced gut inflammation, in terms of intensity and duration, act as critical factors that determine homeostasis or pathogenesis in gut-microbe interactions. [ABSTRACT FROM AUTHOR]

Impairment in glucocerebrosidase (GCase) is strongly associated with the development of Parkinson's disease (PD), yet the regulators responsible for its impairment remain elusive. In this paper, we identify the E3 ligase Thyroid Hormone Receptor Interacting Protein 12 (TRIP12) as a key regulator of GCase. TRIP12 interacts with and ubiquitinates GCase at lysine 293 to control its degradation via ubiquitin proteasomal degradation. Ubiquitinated GCase by TRIP12 leads to its functional impairment through premature degradation and subsequent accumulation of α-synuclein. TRIP12 overexpression causes mitochondrial dysfunction, which is ameliorated by GCase overexpression. Further, conditional TRIP12 knockout in vitro and knockdown in vivo promotes the expression of GCase, which blocks α-synuclein preformed fibrils (α-syn PFFs)-provoked dopaminergic neurodegeneration. Moreover, TRIP12 accumulates in human PD brain and α-synuclein-based mouse models. The identification of TRIP12 as a regulator of GCase provides a new perspective on the molecular mechanisms underlying dysfunctional GCase-driven neurodegeneration in PD. [Display omitted] • GCase is a substrate of E3 ligase TRIP12 • TRIP12 accumulates in α-synuclein-based mouse models and sporadic PD brains • TRIP12 ubiquitination of GCase at K293 contributes to mitochondrial dysfunction • TRIP12 depletion protects α-synuclein PFFs-induced pathology both in vitro and in vivo The E3 ligase TRIP12 interacts with and ubiquitinates GCase associated with the development of PD. The ubiquitinated GCase by TRIP12 leads to its functional impairment, and subsequent accumulation of α-synuclein and mitochondrial dysfunction. TRIP12 depletion promotes the expression of GCase, which blocks dopaminergic neurodegeneration due to α-synuclein preformed fibrils. [ABSTRACT FROM AUTHOR]

Differences in life-history strategy are thought to contribute to adaptation to specific environmental conditions. Among life-history traits in plants, flowering time and shoot morphology are particularly important for reproductive success. Even though flowering time and shoot morphology are linked, the evolutionary changes in the genetic circuitry that simultaneously affects both traits remain obscure. Here, we have identified changes in a putative pre-mRNA processing factor, HUA2, as being responsible for the distinct shoot morphology and flowering behavior in Sy-0, a natural strain of Arabidopsis. HUA2 has previously been shown to positively regulate two MADS box genes affecting flowering time (FLOWERING LOCUS C [FLC]) and floral patterning (AGAMOUS [AG]) . We demonstrate that natural changes in HUA2 activity have opposite effects on its known functions, thus having implications for the coordinate control of induction and maintenance of floral fate. The changes in Sy-0 lead to enhanced FLC expression, resulting in an enlarged basal rosette and aerial rosettes, whereas suppression of AG function favors a reversion of floral meristems from determinate to indeterminate development. Natural variation in HUA2 activity thus coordinates changes in two important life-history traits, flowering time and shoot morphology. [Copyright &y& Elsevier]

Summary: The Drosophila host defense against gram-negative bacteria is mediated by the Imd pathway upon sensing of peptidoglycan by the peptidoglycan recognition protein (PGRP)-LC. Here we report a functional analysis of PGRP-LB, a catalytic member of the PGRP family. We show that PGRP-LB is a secreted protein regulated by the Imd pathway. Biochemical studies demonstrate that PGRP-LB is an amidase that specifically degrades gram-negative bacteria peptidoglycan. In agreement with its amidase activity, PGRP-LB downregulates the Imd pathway. Hence, activation of PGRP-LB by the Imd pathway provides a negative feedback regulation to tightly adjust immune activation to infection. Our study also reveals that PGRP-LB controls the immune reactivity of flies to the presence of ingested bacteria in the gut. Our work highlights the key role of PGRPs that encode both sensors and scavengers of peptidoglycan, which modulate the level of the host immune response to the presence of infectious microorganisms. [Copyright &y& Elsevier]

Summary We have uncovered the existence of extracellular vesicle (EV)-mediated signaling between cell types within the adipose tissue (AT) proper. This phenomenon became evident in our attempts at generating an adipocyte-specific knockout of caveolin 1 (cav1) protein. Although we effectively ablated the CAV1 gene in adipocytes, cav1 protein remained abundant. With the use of newly generated mouse models, we show that neighboring endothelial cells (ECs) transfer cav1-containing EVs to adipocytes in vivo , which reciprocate by releasing EVs to ECs. AT-derived EVs contain proteins and lipids capable of modulating cellular signaling pathways. Furthermore, this mechanism facilitates transfer of plasma constituents from ECs to the adipocyte. The transfer event is physiologically regulated by fasting/refeeding and obesity, suggesting EVs participate in the tissue response to changes in the systemic nutrient state. This work offers new insights into the complex signaling mechanisms that exist among adipocytes, stromal vascular cells, and, potentially, distal organs. Graphical Abstract Highlights • A network of EV-mediated exchange of cellular material exists in adipose tissue • This exchange can replace protein levels in adipocytes despite gene disruption • EV trafficking in adipose tissue is regulated by the systemic metabolic state • Endothelial cells pack extracellular molecules in EVs for release to adipose tissue Extracellular vesicles exchange protein and lipid signals between endothelial cells and adipocytes conveying information about nutrient state changes from the blood in adipose tissues. [ABSTRACT FROM AUTHOR]

Summary Mitochondrial crista structure partitions vital cellular reactions and is precisely regulated by diverse cellular signals. Here, we show that, in Drosophila , mitochondrial cristae undergo dynamic remodeling among distinct subcellular regions and the Parkinson’s disease (PD)-linked Ser/Thr kinase PINK1 participates in their regulation. Mitochondria increase crista junctions and numbers in selective subcellular areas, and this remodeling requires PINK1 to phosphorylate the inner mitochondrial membrane protein MIC60/mitofilin, which stabilizes MIC60 oligomerization. Expression of MIC60 restores crista structure and ATP levels of PINK1 -null flies and remarkably rescues their behavioral defects and dopaminergic neurodegeneration. In an extension to human relevance, we discover that the PINK1-MIC60 pathway is conserved in human neurons, and expression of several MIC60 coding variants in the mitochondrial targeting sequence found in PD patients in Drosophila impairs crista junction formation and causes locomotion deficits. These findings highlight the importance of maintenance and plasticity of crista junctions to cellular homeostasis in vivo . [ABSTRACT FROM AUTHOR]

Summary Intrinsically photosensitive retinal ganglion cells (ipRGCs) combine direct photosensitivity through melanopsin with synaptically mediated drive from classical photoreceptors through bipolar-cell input. Here, we sought to provide a fuller description of the least understood ipRGC type, the M5 cell, and discovered a distinctive functional characteristic—chromatic opponency (ultraviolet excitatory, green inhibitory). Serial electron microscopic reconstructions revealed that M5 cells receive selective UV-opsin drive from Type 9 cone bipolar cells but also mixed cone signals from bipolar Types 6, 7, and 8. Recordings suggest that both excitation and inhibition are driven by the ON channel and that chromatic opponency results from M-cone-driven surround inhibition mediated by wide-field spiking GABAergic amacrine cells. We show that M5 cells send axons to the dLGN and are thus positioned to provide chromatic signals to visual cortex. These findings underscore that melanopsin’s influence extends beyond unconscious reflex functions to encompass cortical vision, perhaps including the perception of color. [ABSTRACT FROM AUTHOR]

Targeting specific cell types in the mammalian inner ear is important for treating genetic hearing loss due to the different cell type-specific functions. Adeno-associated virus (AAV) is an efficient in vivo gene transfer vector, and it has demonstrated promise for treating genetic hearing loss. Although more than 100 AAV serotypes have been identified, few studies have investigated whether AAV can be distributed to specific inner ear cell types. Here we screened three EGFP-AAV reporter constructs (serotypes DJ, DJ8, and PHP.B) in the neonatal mammalian inner ear by injection via the round window membrane to determine the cellular specificity of the AAV vectors. Sensory hair cells, supporting cells, cells in Reissner's membrane, interdental cells, and root cells were successfully transduced. Hair cells in the cochlear sensory epithelial region were the most frequently transduced cell type by all tested AAV serotypes. The recombinant DJ serotype most effectively transduced a range of cell types at a high rate. Our findings provide a basis for improving treatment of hereditary hearing loss using targeted AAV-mediated gene therapy.