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Mou, X.

Publications and source records attributed to Mou, X..

17 recordsLinked to original sources

Interactome-based deep learning and path-level decomposition reveal TGFβ-IFNα competition in MASH

Dysregulated signaling drives Metabolic Dysfunction-Associated Steatohepatitis (MASH) through a complex crosstalk between pro- and anti-fibrotic cues. We previously observed potential competition between IFN-mediated JAK-STAT signaling and TGF{beta} in modulating MASH fibrosis, but the precise mechanism of that competition, and whether it can act directly on hepatocytes, is yet unknown. We used DT-LEMBAS, an interactome-based deep learning framework, training an ensemble of 50 models on drug-induced transcriptomics from primary human hepatocytes. The ensemble captured transcriptional changes induced by simulated receptor knockouts and aligned predicted profiles with known TGF{beta}- and IFN-induced phenotypes. Systematic simulations demonstrate their competitive modulation of MASH phenotype scores benchmarked against human cohorts. To extract mechanistic insights, we developed a gradient-based approach, where we computed the Jacobian of the used recurrent signaling network and applied chain rule decomposition to identify a four-node module of SMAD3, TP63, STAT2, and STAT3. Mechanistic hypotheses involving these canonical and non-canonical TF mediators were experimentally validated in primary hepatocyte spheroids. This work establishes a generalizable and scalable approach to decode large signaling neural networks into interpretable biological subnetworks.

systems biology↗

The OxyR-Responsive TacAT Module Promotes Oxidative Stress Adaptation and In Vivo Fitness in K. pneumoniae

During infection, Klebsiella pneumoniae must withstand host-derived oxidative stress not only by detoxifying reactive oxygen species (ROS) but also by repairing oxidative damage to cellular physiology. How these detoxification and stress-adaptive responses are coordinated remains unclear. Here, we identify a plasmid-encoded tacAT locus as an OxyR-responsive regulatory module that supports peroxide tolerance and in vivo fitness in K. pneumoniae. Guided by the conservation of the OxyR DNA-binding domain and its consensus binding motif, we surveyed promoter-proximal regions of the K. pneumoniae CRK3022 chromosome and plasmids for candidate OxyR-responsive loci. This analysis identified tacAT, a putative type II toxin-antitoxin (TA) module, as the only plasmid-associated candidate. OxyR directly bound the tacAT promoter and contributed to tacAT induction during hydrogen peroxide (H?O?) stress. The TacAT complex exhibited DNA-binding and transcriptional regulatory activity, promoting the expression of genes linked to protein quality control and membrane/envelope homeostasis, including clpB, htpG, cadC, bhsA, and marA. Deletion of tacAT compromised survival under lethal peroxide challenge and attenuated bacterial dissemination, tissue pathology, and inflammatory responses in a murine bacteremia model. These findings define an OxyR-TacAT regulatory branch that connects peroxide sensing with stress-adaptive gene expression, revealing how a TA-associated module can be integrated into stress-adaptive programs during host-associated oxidative stress.

microbiology↗

Promoter architecture decodes response regulator phosphorylation into distinct transcriptional logics in Pseudomonas aeruginosa

Two-component systems convert environmental signals into transcriptional responses, but how one response-regulator phosphorylation state produces different outputs at different promoters remains unclear. Here we show that promoter architecture determines how the ParR response regulator in Pseudomonas aeruginosa interprets phosphorylation. Phenotypic, transcriptomic, biochemical and promoter-engineering analyses showed that phosphorylation of the conserved ParR receiver residue Asp57 lowered DNA-occupancy thresholds across target promoters. Individual promoters, however, converted this shared increase in binding into activation, repression or phosphorylation-dependent sign switching. Chromosomally D57 ParR variants reproduced these behaviours at endogenous loci and altered antibiotic susceptibility, biofilm formation and virulence-associated phenotypes. Mapping and engineering of representative promoters identified a two-tier cis-regulatory code: half-site sequence compatibility determines productive ParR engagement, whereas spacer length determines regulatory sign and magnitude. Spacer swaps were sufficient to reprogram promoter logic between regulatory modes. These findings separate regulator state from promoter decoding and show how bacterial promoter architecture can diversify the outputs of a shared phosphorylation signal. ImportancePseudomonas aeruginosa is an opportunistic pathogen that survives antimicrobial treatment and adapts to diverse host environments by rapidly changing gene expression. How a single sensory pathway generates different, and sometimes opposing, responses across many genes has remained unclear. We show that the regulatory protein ParR does not impose one fixed transcriptional program. Instead, the DNA architecture of each target promoter determines whether the same phosphorylation signal activates, represses, or reverses gene expression. The sequence and spacing of ParR recognition sites form a compact regulatory code, and changing spacer length alone can reprogram promoter behavior. Different ParR states were also associated with changes in antibiotic susceptibility, biofilm formation, and virulence-associated phenotypes. Our findings explain how one bacterial signaling pathway can generate diverse physiological outcomes without additional regulators and provide a framework for understanding regulatory flexibility in Pseudomonas aeruginosa and for engineering genetic circuits with multiple outputs. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=142 SRC="FIGDIR/small/740031v1_ufig1.gif" ALT="Figure 1"> View larger version (55K): org.highwire.dtl.DTLVardef@1b6ec28org.highwire.dtl.DTLVardef@4a3f2eorg.highwire.dtl.DTLVardef@79e528org.highwire.dtl.DTLVardef@b3aa77_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

Promoter architecture diversifies ParR-dependent transcription in Pseudomonas aeruginosa

Two-component systems convert environmental signals into transcriptional responses, but how one response-regulator phosphorylation state produces different outputs at different promoters remains unclear. Here we show that promoter architecture determines how the ParR response regulator in Pseudomonas aeruginosa interprets phosphorylation. Phenotypic, transcriptomic, biochemical and promoter-engineering analyses showed that phosphorylation of the conserved ParR receiver residue Asp57 lowered DNA-occupancy thresholds across target promoters. Individual promoters, however, converted this shared increase in binding into activation, repression or phosphorylation-dependent sign switching. Chromosomally D57 ParR variants reproduced these behaviours at endogenous loci and altered antibiotic susceptibility, biofilm formation and virulence-associated phenotypes. Mapping and engineering of representative promoters identified a two-tier cis-regulatory code: half-site sequence compatibility determines productive ParR engagement, whereas spacer length determines regulatory sign and magnitude. Spacer swaps were sufficient to reprogram promoter logic between regulatory modes. These findings separate regulator state from promoter decoding and show how bacterial promoter architecture can diversify the outputs of a shared phosphorylation signal. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=142 SRC="FIGDIR/small/738673v1_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@1a0a26forg.highwire.dtl.DTLVardef@10836a8org.highwire.dtl.DTLVardef@3c6cd8org.highwire.dtl.DTLVardef@10dfefb_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsParR coordinates antibiotic resistance, biofilm formation and virulence-linked phenotypes in P. aeruginosa. Promoters convert ParR phosphorylation into activation, repression or sign switching. Half-site compatibility and spacer length form a cis-regulatory code for ParR output.

biochemistry↗

A Global Discovery of Antimicrobial Peptides in Deep-Sea Microbiomes Driven by an ESM-2 and Transformer-based Dual-Engine Framework

The global crisis of multidrug-resistant pathogens necessitates innovative antimicrobial peptide (AMP) discovery. However, current AMP predictors are severely compromised by three overlooked systematic data biases, including sequence length imbalance, N-terminal methionine artifacts, and lack of microbial optimization. To overcome these fundamental bottlenecks, we developed XAMP, a dual-engine predictor integrating XAMP-E (ESM-2-based for high accuracy) and XAMP-T (a one-layer Transformer for high speed), trained on rigorously debiased datasets. Consequently, XAMP achieved a median AUC of 0.972, representing an improvement of up to 21.9% in AUC while operating 5 to 40 times faster. Beyond accurate classification, we found that AMPs inherently possess a significantly higher net charge (+3.9 vs. +0.5) despite similar hydrophobicity, along with distinct cooperative patterns such as W-K/R pairs. Applying this pipeline to 238 deep-sea metagenomes (>1000m depth), we identified 2,355 promising AMP candidates from microbial dark matter, and metaproteomic analysis confirmed in-situ expression for a subset of these candidates. Notably, these deep-sea AMPs exhibited a significant 1.53-to 2.93-fold enrichment in K/R/W/Y residues compared to known AMPs. Experimental validation demonstrated that six synthesized peptides exhibit potent, broad-spectrum activity against ESKAPE pathogens, with particular efficacy against Gram-negative bacteria that dominate deep-sea ecosystems and pose major clinical challenges. This study establishes that correcting algorithmic data biases is a prerequisite for reliable mining, providing a robust framework to unlock the therapeutic potential hidden within microbial dark matter, offering new avenues to combat the antibiotic resistance crisis.

bioinformatics↗

Modification of RNAs in natural rG4 (MoRNiNG), A Database of RNA Modification Sites Associated with the Dynamics of RNA Secondary Structures

RNA structures are essential building blocks of functional RNA molecules. Profiling secondary structures in vivo and in real-time remains challenging because RNAs exhibit dynamic structures and complex conformations. Besides the stem-loop canonical secondary structure, the non-canonical structure RNA G-quadruplex (rG4) is of great interest for its potential as a drug target. Early studies have demonstrated that RNAs can form distinct secondary structures. However, it is not well understood how distinct RNA structures, formed from the same RNA sequences, function within the transcriptome. The factors driving and regulating structure transitions remain poorly investigated. Inspired by a segment in the HOXB9 mRNA capable of forming multiple structures, we found that many RNA segments across the transcriptome exhibit multi-faceted structure-forming potential. For the HOXB9 case, we demonstrated that RNA modification influences RNA structure and binding with RNA binding proteins. Therefore, we collected RNA modification sites naturally occurring in the putative G-quadruplex-forming sequences (PQSs) of transcripts and developed MoRNiNG, a freely accessible database at https://www.cityu.edu.hk/bms/morning. The database is designed and organized by reliability tiers determined by the resolution of RNA modification sites and capable of including various large datasets. We experimentally validated the influence of m6A, m5C, and A-to-I editing on rG4-forming sequences and provided evidence to support the modification switch concept. The diversity and transition of secondary structures from the same RNA segment offers valuable insights into the regulation of RNA structure dynamics.

systems biology↗

Modeling Spectroradiometric Measurements of Oral Mucosal Autofluorescence

This study explores the potential of quantitative autofluorescence imaging (AFI) as an objective tool for monitoring the health of oral mucosal tissue. Our approach involves acquiring spectroradiometric measurements of tissue fluorescence and utilizing a model to understand the fluorophores influencing these measurements, including the impact of blood attenuation. We acquired fluorescence measurements from the dorsal tongue and inner lip of healthy human volunteers, subsequently fitting the model to these data to estimate individual fluorophore contributions and the optical density of the blood. Our dataset and model, which are freely shared in an open repository, aim to advance the development of quantitative, non-invasive diagnostic imaging systems for monitoring oral health, ultimately facilitating the detection and characterization of oral mucosal tissue abnormalities.

bioengineering↗

A Novel TRPC6 Mutation Causes Autosomal Dominant FSGS

FSGS is the most common primary glomerular lesion that causes kidney failure in the US. FSGS results from injury or loss of glomerular visceral epithelial cells (i.e. podocytes). Pathogenic variants in TRPC6 can cause FSGS through dysregulated calcium conductance and associated disturbances in podocyte physiology. Here, we describe a 5-generation kindred with FSGS caused by a novel compound C-terminal TRPC6 mutation. Analysis of patient-specific iPSC-derived podocytes and glomerular capillary wall-on-a-chip systems revealed that the compound variants disrupt TRPC6 protein structure, intermolecular interactions, and membrane localization. Combined therapy with Sildenafil and Losartan ameliorated these disturbances compared to conventional immunosuppressive treatment.

genetics↗

Observational activation of anterior cingulate cortical neurons coordinates hippocampal replay in social learning

Social learning enables a subject to make decisions by observing the actions of another. How neural circuits acquire relevant information during observation to guide subsequent behavior is unknown. Utilizing an observational spatial working memory task, we show that neurons in the rat anterior cingulate cortex (ACC) associated with spatial trajectories during self-running in a maze are reactivated when observing another rat running the same maze. The observation-induced ACC activities are reduced in error trials and are correlated with activities of hippocampal place cells representing the same trajectories. The ACC activities during observation also predict subsequent hippocampal place cell activities during sharp-wave ripples and spatial contents of hippocampal replay prior to self-running. The results support that ACC neurons involved in decisions during self-running are reactivated during observation and interact with hippocampal replay to guide subsequent spatial navigation.

neuroscience↗

Heterogeneous hybrid immunity against Omicron variant JN.1 at 11 months following breakthrough infection

A highly transmissible SARS-CoV-2 variant JN.1 is rapidly spreading throughout the nation, becoming the predominant strain in China and worldwide. However, the current immunity against the circulating JN.1 at population level has yet to be fully evaluated. We recruited representative cohorts with stratified age groups and diverse combinations of vaccination and/or infection in recent months, and promptly assessed humoral immunity for these subjects predominantly exhibiting hybrid immunity. We report that at 11 months following BA.5-wave breakthrough infection (BTI), these vaccinated individuals generally showed above-the-threshold yet low level of neutralizing activity against JN.1, with slightly greater potency observed in children and adolescents compared to adults and seniors. Meanwhile, XBB/EG.5-wave reinfection post-BTI significantly boosted the neutralizing antibodies against Omicron variants, including JN.1 in both adults (13.4-fold increase) and seniors (24.9-fold increase). To better understand respiratory mucosal protection against JN.1 over an extended period of months post-BTI, we profiled the humoral immunity in bronchoalveolar lavage samples obtained from vaccinated subjects with or without BTI, and revealed increased potency of neutralizing activity against the BA.5 and JN.1 variants in the respiratory mucosa through natural infection. Notably, at 11 months post-BTI, memory B cell responses against prototype and JN.1 were detectable in both blood and respiratory mucosa, displaying distinct memory features in the circulation and airway compartments. XBB/EG.5-wave reinfection drove the expansion of JN.1-specific B cells, along with the back-boosting of B cells responding to the ancestral viral strain, suggesting the involvement of immune imprinting. Together, this study indicates heterogeneous hybrid immunity over 11 months post-BTI, and underscores the vulnerability of individuals, particularly high-risk seniors, to JN.1 breakthrough infection. An additional booster with XBB-containing vaccine may greatly alleviate the onward transmission of immune-evasive SARS-CoV-2 variants.

immunology↗

ChineseEEG: A Chinese Linguistic Corpora EEG Dataset for Semantic Alignment and Neural Decoding

An Electroencephalography (EEG) dataset utilizing rich text stimuli can advance the understanding of how the brain encodes semantic information and contribute to semantic decoding in brain-computer interface (BCI). Addressing the scarcity of EEG datasets featuring Chinese linguistic stimuli, we present the ChineseEEG dataset, a high-density EEG dataset complemented by simultaneous eye-tracking recordings. This dataset was compiled while 10 participants silently read approximately 11 hours of Chinese text from two well-known novels. This dataset provides long-duration EEG recordings, along with pre-processed EEG sensor-level data and semantic embeddings of reading materials extracted by a pre-trained natural language processing (NLP) model. As a pilot EEG dataset derived from natural Chinese linguistic stimuli, ChineseEEG can significantly support research across neuroscience, NLP, and linguistics. It establishes a benchmark dataset for Chinese semantic decoding, aids in the development of BCIs, and facilitates the exploration of alignment between large language models and human cognitive processes. It can also aid research into the brains mechanisms of language processing within the context of the Chinese natural language.

neuroscience↗

Feeding disruptions lead to a significant increase in disease modules in adult mice

Feeding disruption is intimately associated with numerous diseases, yet its molecular mechanisms remain to be elucidated in circadian biology. We discovered that in the liver of adult mice, feeding disruption can lead to a substantial increase in disease modules in the transcriptome. This increase in disease modules occurs far earlier than the individuals aging and disease onset. In contrast, calorie restriction significantly reduces the formation of disease modules. This offers a critical missing link between feeding disruption and the molecular systems mechanisms of disease.

neuroscience↗

Shigella IpaH9.8 limits GBP1-dependent LPS release from intracytosolic bacteria to suppress caspase-4 activation

Pyroptosis is an inflammatory form of cell death induced upon the recognition of invading microbes. During an infection, pyroptosis is enhanced in interferon-gamma (IFN{gamma}) exposed cells due to the actions of members of the guanylate binding protein (GBP) family. GBPs promote activation of caspase-4 (CASP4) by enhancing its interactions with lipopolysaccharide (LPS), a component of the outer envelope of Gram-negative bacteria. Once activated, CASP4 promotes the formation of non-canonical inflammasomes, signaling platforms that mediate pyroptosis. To establish an infection, intracellular bacterial pathogens, like Shigella species, inhibit pyroptosis. The pathogenesis of Shigella is dependent on its type III secretion system, which injects ~30 effector proteins into host cells. Upon entry into host cells, Shigella are encapsulated by GBP1, followed by GBP2, GBP3, GBP4, and in some cases, CASP4. It has been suggested that the recruitment of CASP4 to bacteria leads to its activation. Here, we demonstrate that two Shigella effectors, OspC3 and IpaH9.8, cooperate to inhibit CASP4-mediated pyroptosis. We show that in the absence of OspC3, an inhibitor of CASP4, IpaH9.8 inhibits pyroptosis via its known degradation of GBPs. We find that, while some LPS is present within the host cell cytosol of epithelial cells infected with wild type Shigella, in the absence of IpaH9.8, increased amounts are shed in a GBP1-dependent manner. Furthermore, that additional IpaH9.8 targets, likely GBPs, promote CASP4 activation, even in the absence of GBP1. These observations suggest that by promoting LPS release, GBP1 provides CASP4 access to LPS, thus promoting host cell death via pyroptosis. Significance StatementNon-canonical inflammasomes mediate the death of intestinal epithelial cells in response to invading Gram-negative bacterial pathogens. CASP4 is activated upon binding to LPS. Recent studies have suggested that GBP1 recruits and enables the activation of CASP4 on the surface of intracytosolic bacteria. This has led to the proposal that non-canonical inflammasomes assemble on the bacterial surface due to GBP1-mediated access of CASP4 to the membrane-embedded lipid A component of LPS. Here, we show that by targeting the degradation of GBPs, Shigella IpaH9.8 limits the release of LPS from intracellular Shigella into the host cell cytosol in a GBP1-dependent manner. Furthermore, we find evidence to suggest that in the absence of GBP1, other members of the GBP family promote CASP4 activation.

microbiology↗

MADET: A Manually Curated Knowledgebase for Microbiomic Effects on Efficacy and Toxicity of Anticancer Treatments

A plethora of studies have reported the associations between microbiota and multiple diseases, leading to at least four databases to demonstrate microbiota-disease associations, i.e., gutMDisorder, mBodyMap, GMrepo and Amadis. Moreover, gut microbiota also mediates drug efficacy and toxicity, whereas a comprehensive database to elucidate the microbiota-drug associations is lacking. Here we report an open-access knowledgebase, MADET (Microbiomics of Anticancer Drug Efficacy and Toxicity), which harbors 453 manually annotated microbiota-drug associations from 24 papers. MADET provides user-friendly functions allowing users to freely browse, search, and download the data conveniently from the database. Users can customize their search filters in MADET using different types of keywords, including bacterial name (e.g., Akkermansia muciniphila), anticancer treatment (e.g., anti-PD-1 therapy) or cancer type (e.g., lung cancer) with different types of experimental evidence of microbiota-drug association and causation. We have also enabled user submission to further enrich the data document in MADET. The MADET database is freely available at https://www.madet.info. We anticipate that MADET will serve as a useful resource for a better understanding of the microbiota-drug associations and facilitate the future development of novel biomarkers and live biotherapeutic products for anticancer therapies.

microbiology↗

BSG/CD147 and ACE2 receptors facilitate SARS-CoV-2 infection of human iPS cell-derived kidney podocytes

BackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes the Coronavirus disease 2019 (COVID-19), which was declared a pandemic by the World Health Organization (WHO) in March 2020. The disease has caused more than 5.1 million deaths worldwide. While cells in the respiratory system are frequently the initial target for SARS-CoV-2, clinical studies suggest that COVID-19 can become a multi-organ disease in the most severe cases. Still, the direct affinity of SARS-CoV-2 for cells in other organs such as the kidneys, which are often affected in severe COVID-19, remains poorly understood. MethodIn this study, we employed a human induced pluripotent stem (iPS) cell-derived model to investigate the affinity of SARS-CoV-2 for kidney glomerular podocytes. We studied uptake of the live SARS-CoV-2 virus as well as pseudotyped viral particles by human iPS cell derived podocytes using qPCR, western blot, and immunofluorescence. Global gene expression and qPCR analyses revealed that human iPS cell-derived podocytes express many host factor genes (including ACE2, BSG/CD147, PLS3, ACTR3, DOCK7, TMPRSS2, CTSL CD209, and CD33) associated with SARS-CoV-2 binding and viral processing. ResultInfection of podocytes with live SARS-CoV-2 or spike-pseudotyped lentiviral particles revealed viral uptake by the cells at low Multiplicity of Infection (MOI of 0.01) as confirmed by RNA quantification and immunofluorescence studies. Our results also indicate that direct infection of human iPS cell-derived podocytes by SARS-CoV-2 virus can cause cell death and podocyte foot process retraction, a hallmark of podocytopathies and progressive glomerular diseases including collapsing glomerulopathy observed in patients with severe COVID-19 disease. Additionally, antibody blocking experiments identified BSG/CD147 and ACE2 receptors as key mediators of spike binding activity in human iPS cell-derived podocytes. ConclusionThese results show that SARS-CoV-2 can infect kidney glomerular podocytes in vitro. These results also show that the uptake of SARS-CoV-2 by kidney podocytes occurs via multiple binding interactions and partners, which may underlie the high affinity of SARS-CoV-2 for kidney tissues. This stem cell-derived model is potentially useful for kidney-specific antiviral drug screening and mechanistic studies of COVID-19 organotropism. Significant statementMany patients with COVID19 disease exhibit multiorgan complications, suggesting that SARS-CoV-2 infection can extend beyond the respiratory system. Acute kidney injury is a common COVID-19 complication contributing to increased morbidity and mortality. Still, SARS-Cov-2 affinity for specialized kidney cells remain less clear. By leveraging our protocol for stem cell differentiation, we show that SARS-CoV-2 can directly infect kidney glomerular podocytes by using multiple Spike-binding proteins including ACE2 and BSG/CD147. Our results also indicate that infection by SARS-CoV-2 virus can cause podocyte cell death and foot process effacement, a hallmark of podocytopathies including collapsing glomerulopathy observed in patients with severe COVID-19 disease. This stem cell-derived model is potentially useful for kidney-specific antiviral drug screening and mechanistic studies of COVID-19 organotropism.

bioengineering↗

Identification and targeting of G-quadruplex structures in MALAT1 long non-coding RNA

RNA G-quadruplexes (rG4s) have functional roles in many cellular processes in diverse organisms. While a number of rG4 examples have been reported in coding messenger RNAs (mRNA), so far only limited works have studied rG4s in non-coding RNAs (ncRNAs), especially in long non-coding RNAs (lncRNAs) that are of emerging interest and significance in biology. Herein, we report that MALAT1 lncRNA contains conserved rG4 motifs, forming thermostable rG4 structures with parallel topology. We also show that rG4s in MALAT1 lncRNA can interact with NONO protein with high specificity and affinity in vitro and in nuclear cell lysate, and we provide in vivo data to support that NONO protein recognizes MALAT1 lncRNA via rG4 motifs. Notably, we demonstrate that rG4s in MALAT1 lncRNA can be targeted by rG4-specific small molecule, peptide, and L-aptamer, leading to the dissociation of MALAT1 rG4-NONO protein interaction. Altogether, this study uncovers new and important rG4s in MALAT1 lncRNAs, reveals their specific interactions with NONO protein, offers multiple strategies for targeting MALAT1 and its RNA-protein complex via its rG4 structure, and illustrates the prevalence and significance of rG4s in ncRNAs.

biochemistry↗

mRNA translation control by Dhx36 binding to 5' UTR G-quadruplex structures is essential for skeletal muscle stem cell regenerative functions

Skeletal muscle has a remarkable ability to regenerate owing to its resident stem cells, also called satellite cells (SCs), that are normally quiescent. When stimulated by damage, SCs activate and expand to form new fibers. The mechanisms underlying SC proliferative progression remain poorly understood. Here we show that Dhx36, a helicase that unwinds RNA quadruplex (rG4) structures, is essential for muscle regeneration by regulating SC expansion. We find that Dhx36 (initially named RHAU) is barely expressed at quiescence and is highly induced during SC activation and proliferation. Inducible deletion of Dhx36 in adult SCs causes defective proliferation and muscle regeneration after damage. System-wide mapping in proliferating SCs revealed Dhx36 binding predominantly to rG4 structures at various regions of mRNAs, while integrated polysome profiling showed that Dhx36 promotes mRNA translation via 5UTR rG4 binding. Furthermore, we demonstrate that Dhx36 specifically regulates the translation of Gnai2 mRNA by unwinding its 5UTR rG4 structures and identify Gnai2 as a downstream effector of Dhx36 for SC expansion. Altogether our findings uncover Dhx36 as an indispensable post-transcriptional regulator of SC function and muscle regeneration through binding and unwinding rG4 structures at 5UTR of target mRNAs.

cell biology↗