Biology subjects

Heng, J.

Publications and source records attributed to Heng, J..

5 recordsLinked to original sources

bioRxiv2023

Differences in syncytia formation by SARS-CoV-2 variants modify host chromatin accessibility and cellular senescence via TP53

COVID-19 remains a significant public health threat due to the ability of SARS-CoV-2 variants to evade the immune system and cause breakthrough infections. Although pathogenic coronaviruses such as SARS-CoV-2 and MERS-CoV lead to severe respiratory infections, how these viruses affect the chromatin proteomic composition upon infection remains largely uncharacterized. Here we used our recently developed integrative DNA And Protein Tagging (iDAPT) methodology to identify changes in host chromatin accessibility states and chromatin proteomic composition upon infection with pathogenic coronaviruses. SARS-CoV-2 infection induces TP53 stabilization on chromatin, which contributes to its host cytopathic effect. We mapped this TP53 stabilization to the SARS-CoV-2 spike and its propensity to form syncytia, a consequence of cell-cell fusion. Differences in SARS-CoV-2 spike variant-induced syncytia formation modify chromatin accessibility, cellular senescence, and inflammatory cytokine release via TP53. Our findings suggest that differences in syncytia formation alter senescence-associated inflammation, which varies among SARS-CoV-2 variants.

microbiology↗

bioRxiv2023

Conformational dynamics of the μ-opioid receptor determine ligand intrinsic efficacy

The -opioid receptor (OR) is an important target for pain management and the molecular understanding of drug action will facilitate the development of better therapeutics. Here we show, using double electron-electron resonance (DEER) and single-molecule fluorescence resonance energy transfer (smFRET), how ligand-specific conformational changes of the OR translate into a broad range of intrinsic efficacies at the transducer level. We identify several cytoplasmic receptor conformations interconverting on different timescales, including a pre-activated receptor conformation which is capable of G protein binding, and a fully activated conformation which dramatically lowers GDP affinity within the ternary complex. Interaction of {beta}-arrestin-1 with the OR core binding site appears less specific and occurs with much lower affinity than binding of G protein Gi. One-Sentence SummaryLigand-dependent conformational dynamics of the -opioid receptor determine downstream signaling efficacy.

biochemistry↗

bioRxiv2022

Cryo-EM complex structure of active GPR75 with a nanobody

Although there has been enormous progress in the last half-century in the drug discovery targeting obesity and associated co-morbidities, the clinical treatment of obesity remains tremendously challenging. GPR75 is an orphan receptor and is suggested to be a potential novel target for the control of obesity and related metabolic disorders. Inhibition of the GPR75 signaling pathway by small molecules, antibodies, or genetic manipulations may provide a therapeutic strategy for obesity. Here, we report the active-like Cryo-EM structure of human GPR75 with an intracellular nanobody, which reveals the receptor activation mechanism. The extensive interaction network required to achieve the active structure helps explain the allosteric coupling between the orthosteric pocket and the G-protein coupling domain. The well-defined orthosteric ligand binding pocket of human GPR75 provides a structural basis for anti-obesity drug discovery.

biophysics↗

bioRxiv2022

Calcineurin-fusion facilitates Cryo-EM Structure Determination of a Family A GPCR

Advances in singe-particle cryo-electron microscopy (cryo-EM) have made possible to solve the structures of numerous Family A and Family B G protein coupled receptors (GPCRs) in complex with G proteins and arrestins, as well as several Family C GPCRs. Determination of these structures has been facilitated by the presence of large extra-membrane components (such as G protein, arrestin, or Venus flytrap domains) in these complexes that aid in particle alignment during processing of the cryo-EM data. In contrast, determination of the inactive state structure of Family A GPCRs is more challenging due to the relatively small size of the seven transmembrane domain (7TM) and to the surrounding detergent micelle that, in the absence of other features, make particle alignment impossible. Here we describe an alternative protein engineering strategy where the heterodimeric protein calcineurin is fused to a GPCR by three points of attachment, the cytoplasmic ends of TM5, TM6 and TM7. This three-point attachment provides a more rigid link with the GPCR transmembrane domain that facilitates particle alignment during data processing, allowing us to determine the structures of the {beta}2 adrenergic receptor ({beta}2AR) in the apo, antagonist-bound, and agonist-bound states. We expect that this fusion strategy may have broad application in cryo-EM structural determination of other Family A GPCRs.

biophysics↗

bioRxiv2019

Brain-enriched coding and long non-coding RNA genes are overrepresented in recurrent autism spectrum disorder CNVs

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with substantial phenotypic and etiological heterogeneity. It is estimated that 10-20% of cases are due to copy number variations (CNVs). Here we apply a newly developed CNV association tool (SNATCNV) to reanalyse CNV data from 19,663 autistic and 6,479 control subjects from the AutDB database. We demonstrate that SNATCNV outperforms existing CNV association methods by finding smaller genomic regions that better discriminate cases and controls. By integrating data from the FANTOM5 expression atlas we show that both known ASD causal genes identified by the SFARI and MSSNG consortia and genes within the CNVs identified by SNATCNV have brain enriched expression patterns; both brain-enriched coding and long-non-coding RNA genes are over-represented. We provide full lists of these brain enriched coding and lncRNA genes as a resource to the research community. We also go on to show that each CNV region is associated with a distinct set of phenotypes, that some are sex biased and highlight one deleted region where a brain-enriched lncRNA is the only gene present. Our analyses identify 47 high confidence ASD associated CNV regions and identifies brain-enriched genes which underlie this neurodevelopmental disorder.

neuroscience↗