Biology subjects

Chiang, C.

Publications and source records attributed to Chiang, C..

14 recordsLinked to original sources

bioRxiv2026

Nsp3 Ubl1-orchestrated dephosphorylation of N protein promotes coronaviral subgenomic RNA synthesis

The coronavirus nucleocapsid (N) protein is indispensable for the viral lifecycle as part of the viral Replication-Transcription Complex together with Nsp3. Recent research demonstrated that phosphorylation of N by several host kinases intricately regulates its functions during infection. However, the mechanisms that control N dephosphorylation, and its physiological consequence, remain poorly understood. Here, we show that SARS-CoV-2 Nsp3 is a key orchestrator of N dephosphorylation by recruiting the phosphatase PP1/{gamma} via a conserved PP1-binding motif in the Ubl1 domain. Disruption of this motif abolishes N dephosphorylation and selectively impairs subgenomic RNA synthesis. Comparative interactome proteomics analysis of phospho-mimic vs. phospho-deficient N, together with functional validation, revealed that the host splicing factor SRSF1 cooperates with unphosphorylated N to promote subgenomic RNA transcription. These findings uncover an unrecognized mechanism in which Nsp3-guided N dephosphorylation by PP1/{gamma} enables coronavirus subgenomic RNA replication and highlight a potentially targetable axis for antiviral intervention.

microbiology↗

bioRxiv2025

Hierarchical regulation of cerebellar neurogenesis by Sin3A-mediated gene repression

Cerebellar granule cells (GCs) are critical for motor and cognitive functions. Lineage tracing studies have identified a hierarchical developmental progression of GC neurogenesis, transitioning from Sox2+ stem-like cells to Atoh1+ rapidly proliferating granule cell precursors (GCPs), and ultimately to NeuN+ mature GCs. However, the molecular mechanisms governing these transitions remain poorly understood. In this study, we identified a transient, slow-cycling progenitor population defined by co-expression of Sox2 and Atoh1. We show that GC maturation depends critically on the repressive function of the Sin3A/Hdac1 complex, which sequentially silences Sox2 and then Atoh1 to ensure orderly progression through developmental stages. Loss of these repressions prolongs progenitor states, compromises survival, and markedly reduces GC output. We also identify NeuroD1 as a co-repressor that collaborates with Sin3A/Hdac1 to inhibit Atoh1 transcription. Our findings highlight the central role of the Sin3A complex in orchestrating distinct stages of cerebellar GC lineage development and may provide insights into Sin3A-related cerebellar disorders and medulloblastoma in human. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=149 SRC="FIGDIR/small/683101v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@1f7ebdaorg.highwire.dtl.DTLVardef@19d4cc9org.highwire.dtl.DTLVardef@1c595eorg.highwire.dtl.DTLVardef@12f4b34_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LISin3A is sequentially required for GC lineage progression C_LIO_LISin3A promotes the transition of slow-cycling progenitors to GCPs by repressing Sox2 expression C_LIO_LISin3A facilitates GCP differentiation by repressing Atoh1 expression C_LIO_LINeuroD1 recruits the Sin3A/Hdac1 complex to suppress Atoh1 expression C_LI

neuroscience↗

bioRxiv2025

Inhibition of coronaviral exonuclease activity by TRIM-mediated SUMOylation

Members of the TRIM E3 ligase family are effectors of the host innate or intrinsic defense against various viruses; however, how specific TRIM proteins antagonize coronavirus infection is still largely elusive. Through an RNAi screen targeting 71 human TRIM genes, we identified multiple TRIM proteins with antiviral or proviral activity against SARS-CoV-2. TRIM32 potently restricted SARS-CoV-2 replication in a RING E3 ligase-dependent but interferon-independent manner. Mechanistically, TRIM32 binds to and SUMOylates the 3'-to-5' exoribonuclease (ExoN) of NSP14, which is essential for SARS-CoV-2 replication. TRIM32-mediated NSP14 SUMOylation at K9 and K200 inhibits RNA binding and NSP10 cofactor recruitment, respectively, ultimately suppressing ExoN activity. Our study further revealed that NSP14 SUMOylation by TRIM32 and its antiviral activity are broadly conserved for coronaviruses. These results identify the coronaviral NSP14 protein as a direct target of host restriction via SUMOylation, which may uncover novel ways to therapeutically inhibit coronavirus infections in humans.

microbiology↗

bioRxiv2022

A Novel Selective ERK1/2 Inhibitor, Laxiflorin B, Targets EGFR Mutation Subtypes in Non-small-cell Lung Cancer

Extracellular regulated protein kinases 1/2 (ERK1/2) are key members of multiple signaling pathways including the ErbB axis. ERK1/2 ectopic activation is responsible for various types of cancer, especially drug resistance to inhibitors of RTK, RAF and MEK, but specific ERK1/2 inhibitors are scarce. In this study, we identified a potential novel ERK covalent inhibitor, Laxiflorin B, a herbal compound with anticancer activity. However, Laxiflorin B is present at low levels in herbs; therefore, we adopted a semi-synthetic process for the efficient production of Laxiflorin B to improve the yield. Laxiflorin B induced mitochondria-mediated apoptosis via BAD activation in non-small-cell lung cancer (NSCLC) cells, especially in EGFR mutant subtypes. Transcriptomic analysis suggested that Laxiflorin B inhibits amphiregulin (AREG) and epiregulin (EREG) expression through ERK inhibition, and suppressed the activation of their receptors, ErbBs, via a positive feedback loop. More importantly, mass spectrometry combined with computer simulation analysis revealed that Laxiflorin B binds covalently to Cys-183 in the ATP-binding pocket of ERK1 through D-ring, and Cys-178 of ERK1 though non-inhibitory binding of A-ring, respectively. Laxiflorin B also exhibited strong tumor suppressive effects with low toxicity in a NSCLC tumor xenograft model in nude mice, and AREG and EREG were identified as biomarkers of Laxiflorin B efficacy. Finally, Laxiflorin B-4, a C-6 modification of Laxiflorin B, exhibited higher affinity for ERK1/2 and stronger tumor suppression. These findings provide a new approach to tumor inhibition using natural anticancer compounds.

pharmacology and toxicology↗

bioRxiv2021

Ancestral diversity improves discovery and fine-mapping of genetic loci for anthropometric traits - the Hispanic/Latino Anthropometry Consortium

Hispanic/Latinos have been underrepresented in genome-wide association studies (GWAS) for anthropometric traits despite notable anthropometric variability with ancestry proportions, and a high burden of growth stunting and overweight/obesity in Hispanic/Latino populations. This address this knowledge gap, we analyzed densely-imputed genetic data in a sample of Hispanic/Latino adults, to identify and fine-map common genetic variants associated with body mass index (BMI), height, and BMI-adjusted waist-to-hip ratio (WHRadjBMI). We conducted a GWAS of 18 studies/consortia as part of the Hispanic/Latino Anthropometry (HISLA) Consortium (Stage 1, n=59,769) and validated our findings in 9 additional studies (HISLA Stage 2, n=9,336). We conducted a trans-ethnic GWAS with summary statistics from HISLA Stage 1 and existing consortia of European and African ancestries. In our HISLA Stage 1+2 analyses, we discovered one novel BMI locus, as well two novel BMI signals and another novel height signal, each within established anthropometric loci. In our trans-ethnic meta- analysis, we identified three additional novel BMI loci, one novel height locus, and one novel WHRadjBMI locus. We also identified three secondary signals for BMI, 28 for height, and two for WHRadjBMI. We replicated >60 established anthropometric loci in Hispanic/Latino populations at genome-wide significance--representing up to 30% of previously-reported index SNP anthropometric associations. Trans-ethnic meta-analysis of the three ancestries showed a small-to-moderate impact of uncorrected population stratification on the resulting effect size estimates. Our novel findings demonstrate that future studies may also benefit from leveraging differences in linkage disequilibrium patterns to discover novel loci and additional signals with less residual population stratification.

genetics↗

bioRxiv2021

Dendritic GABAergic inhibition controlled by Shh signaling-dependent stellate cell pool is critical for motor learning

Cerebellar inhibitory interneurons are important regulators of neural circuit activity for diverse motor and non-motor functions. The molecular layer interneurons (MLI), consisting of basket cells (BCs) and stellate cells (SCs), provide dendritic and somatic inhibitory synapses onto Purkinje cells, respectively. They are sequentially generated in an inside-out pattern from Pax2+ immature interneurons which migrate from the prospective white matter to the ML of the cortex. However, little is known as to how MLI subtype identities and pool sizes are determined, nor are their contributions to motor learning well understood. Here, we show that GABAergic progenitors fated to generate both BCs and SCs respond to the Shh signal. Conditional abrogation of Shh signaling inhibited proliferation of GABAergic progenitors and reduced the number of Pax2+ cells, whereas persistent Shh pathway activation increased their numbers. These changes, however, did not affect early-born BC numbers but selectively altered the SC pool size. Moreover, genetic depletion of GABAergic progenitors when BCs are actively generated also resulted in a specific reduction of SCs, suggesting that the specification of MLI subtypes is independent of Shh signaling and their birth order and likely occurs after Pax2+ cells settle into their laminar positions in an inside-out sequence. Mutant mice with reduced SC numbers displayed decreased dendritic inhibitory synapses and neurotransmission onto Purkinje cells, resulting in an impaired acquisition of eyeblink conditioning. These findings also reveal an essential role of Shh signaling-dependent SCs in regulating inhibitory dendritic synapses and motor learning.

neuroscience↗

bioRxiv2021

Structural variants are a major source of gene expression differences in humans and often affect multiple nearby genes

Structural variants (SVs) are an important source of human genome diversity but their functional effects are not well understood. We mapped 61,668 SVs in 613 individuals with deep genome sequencing data from the GTEx project and measured their effects on gene expression. We estimate that common SVs are causal at 2.66% of eQTLs, which is a 10.5-fold enrichment relative to their abundance in the genome and consistent with prior work using smaller sample sizes. Duplications and deletions were the most impactful variant types, whereas the contribution of mobile element insertions was surprisingly small (0.12% of eQTLs, 1.9-fold enriched). Multi-tissue analysis of expression effects revealed that gene-altering SVs show significantly more constitutive effects than other variant types, with 62.09% of coding SV-eQTLs active in all tissues with known eQTL activity compared to 23.08% of coding SNV- and indel-eQTLs, whereas noncoding SVs, SNVs and indels show broadly similar patterns. We also identified 539 rare SVs associated with nearby gene expression outliers. Of these, 62.34% are noncoding SVs that show strong effects on gene expression yet modest enrichment at known regulatory elements, demonstrating that rare noncoding SVs are a major source of gene expression differences but remain difficult to predict from current annotations. Remarkably, both common and rare noncoding SVs often show strong regional effects on the expression of multiple genes: SV-eQTLs affect an average of 1.82 nearby genes compared to 1.09 genes affected by SNV- and indel-eQTLs, and 21.34% of rare expression-altering SVs show strong effects on 2-9 different genes. We also observe significant effects on gene expression extending 1 Mb from the SV. This provides a mechanism by which individual noncoding SVs may have strong and/or pleiotropic effects on phenotypic variation and disease.

genomics↗

bioRxiv2021

Methylation of KRAS at lysine 182 and 184 by SETD7 promotes KRAS degradation

Oncogenic KRAS mutations are considered to be a key driver for initiation and progression in non-small-cell lung cancer (NSCLC). However, how post-translational modifications (PTMs) of KRAS, especially methylation, modify KRAS activity and downstream signals remain largely unclear. Here, we showed that SET domain containing histone lysine methyltransferase 7 (SETD7) interacts with KRAS and methylates KRAS at lysine 182 and 184. SETD7-mediated methylation of KRAS led to degradation of KRAS and attenuation of the RAS/MEK/ERK signaling cascade, endowing SETD7 with a potent tumor-suppressive role in NSCLC, both in vitro and in vivo. Mechanistically, RABGEF1, a ubiquitin E3 ligase of KRAS, was recruited and promoted KRAS degradation in a K182/K184 methylation-dependent manner. Notably, low SETD7 or RABGEF1 expression was associated with poor prognosis in lung adenocarcinoma patients. Taken together, our results establish a novel connection between lysine methylation and KRAS protein stability, in addition to elucidating a tumor-suppressive function of SETD7 that operates via modulation of oncogenic RAS signaling.

cancer biology↗

bioRxiv2020

Association of Structural Variation with Cardiometabolic Traits in Finns

The contribution of genome structural variation (SV) to quantitative traits associated with cardiometabolic diseases remains largely unknown. Here, we present the results of a study examining genetic association between SVs and cardiometabolic traits in the Finnish population. We used sensitive methods to identify and genotype 129,166 high-confidence SVs from deep whole genome sequencing (WGS) data of 4,848 individuals. We tested the 64,572 common and low frequency SVs for association with 116 quantitative traits, and tested candidate associations using exome sequencing and array genotype data from an additional 15,205 individuals. We discovered 31 genome-wide significant associations at 15 loci, including two novel loci at which SVs have strong phenotypic effects: (1) a deletion of the ALB gene promoter that is greatly enriched in the Finnish population and causes decreased serum albumin level in carriers (p=1.47x10-54), and is also associated with increased levels of total cholesterol (p=1.22x10-28) and 14 additional cholesterol-related traits, and (2) a multiallelic copy number variant (CNV) at PDPR that is strongly associated with pyruvate (p=4.81x10-21) and alanine (p=6.14x10-12) levels and resides within a structurally complex genomic region that has accumulated many rearrangements over evolutionary time. We also confirmed six previously reported associations, including five led by stronger signals in single nucleotide variants (SNVs), and one linking recurrent HP gene deletion and cholesterol levels (p=6.24x10-10), which was also found to be strongly associated with increased glycoprotein level (p=3.53x10-35). Our study confirms that integrating SVs in trait-mapping studies will expand our knowledge of genetic factors underlying disease risk.

genetics↗

bioRxiv2020

ISG15-dependent Activation of the RNA Sensor MDA5 and its Antagonism by the SARS-CoV-2 papain-like protease

Activation of the RIG-I-like receptors, RIG-I and MDA5, establishes an antiviral state by upregulating interferon (IFN)-stimulated genes (ISGs). Among these is ISG15 whose mechanistic roles in innate immunity still remain enigmatic. Here we report that ISGylation is essential for antiviral IFN responses mediated by the viral RNA sensor MDA5. ISG15 conjugation to the caspase activation and recruitment domains of MDA5 promotes the formation of higher-order assemblies of MDA5 and thereby triggers activation of innate immunity against a range of viruses including coronaviruses, flaviviruses and picornaviruses. The ISG15-dependent activation of MDA5 is antagonized through direct de-ISGylation mediated by the papain-like protease (PLpro) of SARS-CoV-2, a recently emerged coronavirus that causes the COVID-19 pandemic. Our work demonstrates a crucial role for ISG15 in the MDA5-mediated antiviral response, and also identifies a novel immune evasion mechanism of SARS-CoV-2, which may be targeted for the development of new antivirals and vaccines to combat COVID-19.

immunology↗

bioRxiv2019

Population history from the Neolithic to present on the Mediterranean island of Sardinia: An ancient DNA perspective

Recent ancient DNA studies of western Eurasia have revealed a dynamic history of admixture, with evidence for major migrations during the Neolithic and Bronze Age. The population of the Mediterranean island of Sardinia has been notable in these studies - Neolithic individuals from mainland Europe cluster more closely with Sardinian individuals than with all other present-day Europeans. The current model to explain this result is that Sardinia received an initial influx of Neolithic ancestry and then remained relatively isolated from expansions in the later Neolithic and Bronze Age that took place in continental Europe. To test this model, we generated genome-wide capture data (approximately 1.2 million variants) for 43 ancient Sardinian individuals spanning the Neolithic through the Bronze Age, including individuals from Sardinias Nuragic culture, which is known for the construction of numerous large stone towers throughout the island. We analyze these new samples in the context of previously generated genome-wide ancient DNA data from 972 ancient individuals across western Eurasia and whole-genome sequence data from approximately 1,500 modern individuals from Sardinia. The ancient Sardinian individuals show a strong affinity to western Mediterranean Neolithic populations and we infer a high degree of genetic continuity on the island from the Neolithic (around fifth millennium BCE) through the Nuragic period (second millennium BCE). In particular, during the Bronze Age in Sardinia, we do not find significant levels of the \"Steppe\" ancestry that was spreading in many other parts of Europe at that time. We also characterize subsequent genetic influx between the Nuragic period and the present. We detect novel, modest signals of admixture between 1,000 BCE and present-day, from ancestry sources in the eastern and northern Mediterranean. Within Sardinia, we confirm that populations from the more geographically isolated mountainous provinces have experienced elevated levels of genetic drift and that northern and southwestern regions of the island received more gene flow from outside Sardinia. Overall, our genetic analysis sheds new light on the origin of Neolithic settlement on Sardinia, reinforces models of genetic continuity on the island, and provides enhanced power to detect post-Bronze-Age gene flow. Together, these findings offer a refined demographic model for future medical genetic studies in Sardinia.

genetics↗

bioRxiv2018

Mapping and characterization of structural variation in 17,795 deeply sequenced human genomes

A key goal of whole genome sequencing (WGS) for human genetics studies is to interrogate all forms of variation, including single nucleotide variants (SNV), small insertion/deletion (indel) variants and structural variants (SV). However, tools and resources for the study of SV have lagged behind those for smaller variants. Here, we used a cloud-based pipeline to map and characterize SV in 17,795 deeply sequenced human genomes from common disease trait mapping studies. We publicly release site-frequency information to create the largest WGS-based SV resource to date. On average, individuals carry 2.9 rare SVs that alter coding regions, which affect the dosage or structure of 4.2 genes and account for 4.0-11.2% of rare high-impact coding alleles. Based on a computational model, we estimate that SVs account for 17.2% of rare alleles genome-wide whose predicted deleterious effects are equivalent to loss-of-function (LoF) coding alleles; ~90% of such SVs are non-coding deletions (mean 19.1 per genome). We report 158,991 ultra-rare SVs and show that ~2% of individuals carry ultra-rare megabase-scale SVs, nearly half of which are balanced and/or complex rearrangements. Finally, we exploit this resource to infer the dosage sensitivity of genes and non-coding elements, revealing strong trends related to regulatory element class, conservation and cell-type specificity. This work will help guide SV analysis and interpretation in the era of WGS.

genomics↗

bioRxiv2018

svtools: population-scale analysis of structural variation

SummaryLarge-scale human genetics studies are now employing whole genome sequencing with the goal of conducting comprehensive trait mapping analyses of all forms of genome variation. However, methods for structural variation (SV) analysis have lagged far behind those for smaller scale variants, and there is an urgent need to develop more efficient tools that scale to the size of human populations. Here, we present a fast and highly scalable software toolkit (svtools) and cloud-based pipeline for assembling high quality SV maps - including deletions, duplications, mobile element insertions, inversions, and other rearrangements - in many thousands of human genomes. We show that this pipeline achieves similar variant detection performance to established per-sample methods (e.g., via LUMPY), while providing fast and affordable joint analysis at the scale of [≥]100,000 genomes. These tools will help enable the next generation of human genetics studies.\n\nAvailability and Implementationsvtools is implemented in Python and freely available (MIT) from https://github.com/hall-lab/svtools.\n\nContactihall@wustl.edu

bioinformatics↗

bioRxiv2018

Exome sequencing identifies high impact trait-associated alleles enriched in Finns

As yet undiscovered rare variants are hypothesized to substantially influence an individuals risk for common diseases and traits, but sequencing studies aiming to identify such variants have generally been underpowered. In isolated populations that have expanded rapidly after a population bottleneck, deleterious alleles that passed through the bottleneck may be maintained at much higher frequencies than in other populations. In an exome sequencing study of nearly 20,000 cohort participants from northern and eastern Finnish populations that exemplify this phenomenon, most novel trait-associated deleterious variants displayed frequencies 10-173 times higher than in other European populations. These enriched alleles underlie 30 novel associations with 20 disease-related quantitative traits and demonstrate a geographical clustering equivalent to that of Mendelian disease mutations characteristic of the Finnish population. Sequencing studies in populations without this unique history would require hundreds of thousands to millions of participants for comparable power.

genomics↗