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Cong, P.

Publications and source records attributed to Cong, P..

7 recordsLinked to original sources

DynMoCo: a Novel AI Framework to Reveal Modular Substructures of Protein From Molecular Dynamics

Proteins are dynamic molecular machines whose functions are determined by their structures. While static structures can offer initial insights or hypotheses about protein function, they are often insufficient for a detailed mechanistic understanding. Molecular dynamics (MD) simulations provide atomistic view of proteins dynamic motion and conformational change, but the resulting high-dimensional data are challenging to interpret. Traditional summary statistics and dimensionality-reduction methods often focus on global motions and can overlook regional, yet functionally critical motions. Inspired by approaches from social network science, we introduce a novel perspective for analyzing MD simulations through dynamic community detection, where molecules are modeled as time-evolving graphs, and communities of residues or atoms that move coherently or exhibit functional coupling are identified. We present DynMoCo, a novel deep learning framework that integrates graph convolutional networks with recurrent models for end-to-end dynamic community detection on molecular graphs. Given a MD trajectory, DynMoCo identifies spatially grounded substructures, tracks their evolution over time, and can incorporate structural knowledge to ensure physically meaningful communities. We provide a library of custom-written scripts to allow users to extract and visualize these communites on the MD simulated molecules in motion. We demonstrate the method on force-ramp and force-clamp steered MD simulations of three integrin systems, revealing modular substructures within known domains and characterizing their conformational rearrangements during force-induced unbending. By reducing high-dimensional MD data into interpretable communities, this approach offers new insights into the intrinsic organization and dynamic function of complex biomolecular systems. SIGNIFICANCEProteins often perform their functions through dynamic, locally coordinated motions. Molecular dynamics simulations provide detailed views of these motions but produce high-dimensional data that are challenging to analyze and interpret. We present a novel deep learning model that analyzes molecular dynamics simulations data and identifies structurally coherent and potentially functionally related communities, while tracking their temporal evolution. This analysis tool provides a novel way to analyze MD data transforming it into interpretable representations of modular dynamic, enabling discovery of new mechanistic insights and advancing our understanding of how molecular motions drive biological function.

biophysics↗

Evaluating the effects of CD8/CD4 on T cell function in terms of TCR-pMHC-coreceptor catch and slip bonds

BackgroundT cells interact with peptide-major histocompatibility complex (pMHC) via the T cell receptor (TCR) and coreceptor CD4 or CD8 depending on the MHC class. These interactions form catch and slip bonds depending on the pMHC activity. Coreceptors and bond profiles impact TCR triggering and antigen discrimination. MethodsBuilt upon our recent correlative analysis of TCR-pMHC catch bond with T cell function, we analyzed 26 pairs of T-cell-pMHC interactions to compare the correlations of their biophysical metrics with antigen-induced T cell responses in two situations: when the coreceptor is prevented vs permitted to bind pMHC. ResultsWe found that the force-based metrics of TCR bond with pMHC perform better than parameters measured in the absence of force either in situ at the T cell membrane or in fluid phase using purified ectodomain proteins as predictors of T cell activation and thymocyte selection in both cases when the contributions of coreceptors are absent and present. Moreover, CD8 or CD4 co-engagement with pMHC systematically increases these metrics and increases TCR sensitivity and specificity, indicating coreceptor-mediated amplification of, or conversion to, catch-bonds that enhances mechanical tuning of TCR responses. ConclusionOur findings highlight the importance of force in antigen recognition by the TCR and reveal that parameters derived from the bond profile, especially in the presence of coreceptor, are more informative predictors of T cell activation compared to conventional affinity-based measurements. These results offer mechanistic insights into the roles of catch bonds and coreceptors in TCR antigen recognition.

immunology↗

Cooperative ectodomain interaction among TCRαβ, CD3γε, and CD3δε enhances TCR mechanotransduction

TCR signaling poses a mechanical problem: pMHC binding occurs at the TCR{beta} ectodomain (ECD) head, whereas ITAM phosphorylation occurs on CD3 cytoplasmic tails. Chemistry cannot bridge this >10 nm gap, requiring the two events to be coupled through the TCR-CD3 interface, thus involving conformational allostery and being regulatable by force. Although weak ECD cis-interactions between TCR{beta} and CD3 have been proposed to contribute to this coupling, their kinetics and mechanical competence remain elusive. Here, we quantify TCR{beta}-CD3 ECD cis-interactions in a pseudo-cis configuration using two-dimensional binding and single-bond force spectroscopy, finding that TCR{beta}-CD3{gamma}{varepsilon} and TCR{beta}-CD3{delta}{varepsilon} interactions have low affinity and rapid kinetics, yet form catch bonds. Critically, concurrent engagement of CD3{gamma}{varepsilon} and CD3{delta}{varepsilon} produces high cis-cooperativity, yielding a stronger and longer-lasting CD3{gamma}{varepsilon}-TCR{beta}-CD3{delta}{varepsilon} trimolecular catch bond than the sum of the two dimeric bonds, with force-stabilized lifetimes matching those of agonist TCR-pMHC trans-interaction. Molecular dynamics simulations reveal an expanded, cooperative, and asymmetric contact network, making CD3{delta}{varepsilon} more force-responsive and susceptible to conformational change than CD3{gamma}{varepsilon}. Interface mutations do not alter force-free affinities but remodel cooperative cis-bond profiles, leading to an inverse correlation with trans-bond profiles and T cell signaling. These results identify cooperative ECD cis-interaction as a mechanically regulatable allosteric coupling element at the TCR-CD3 junction important to antigen recognition and signal initiation.

immunology↗

An early Cambrian polyp reveals an anemone-like ancestor for medusozoan cnidarians

Extant cnidarians are a disparate phylum of non-bilaterians and their diploblastic body plan represents a key step in animal evolution. Anthozoans (anemones, corals) are benthic polyps, while adult medusozoans (jellyfishes) are dominantly pelagic medusae. A sessile polyp is present in both groups and is widely conceived as the ancestral form of their last common ancestor. However, the nature and anatomy of this ancestral polyp, particularly of medusozoans, are controversial, owing to the divergent body plans of both groups in the extant lineages and the rarity of medusozoan soft tissues in the fossil record. Here we redescribe the enigmatic Conicula striata Luo et Hu from the early Cambrian Chengjiang biota, south China, which has previously been interpreted as a polyp, lophophorate or deuterostome. We show that C. striata possessed features of both anthozoans and medusozoans. Its stalked polyp and fully encasing conical, annulated organic skeleton (periderm) are features of medusozoans. However, the gut is partitioned by [~]28 mesenteries, and has a tubular pharynx, resembling anthozoans. Our phylogenetic analysis recovers C. striata as a stem medusozoan, indicating that the enormously diverse medusozoans were derived from an anemone-like ancestor, with the pharynx lost and number of mesenteries reduced prior to the origin of crown group Medusozoa.

paleontology↗

Genomic analyses of 10,376 individuals provides comprehensive map of genetic variations, structure and reference haplotypes for Chinese population

Here, we initiated the Westlake BioBank for Chinese (WBBC) pilot project with 4,535 whole-genome sequencing individuals and 5,481 high-density genotyping individuals. We identified 80.99 million SNPs and INDELs, of which 38.6% are novel. The genetic evidence of Chinese population structure supported the corresponding geographical boundaries of the Qinling-Huaihe Line and Nanling Mountains. The genetic architecture within North Han was more homogeneous than South Han, and the history of effective population size of Lingnan began to deviate from the other three regions from 6 thousand years ago. In addition, we identified a novel locus (SNX29) under selection pressure and confirmed several loci associated with alcohol metabolism and histocompatibility systems. We observed significant selection of genes on epidermal cell differentiation and skin development only in southern Chinese. Finally, we provided an online imputation server (https://wbbc.westlake.edu.cn/) which could result in higher imputation accuracy compared to the existing panels, especially for lower frequency variants.

genetics↗

Essential role of Bone morphogenetic protein 15 in porcine ovarian and follicular development and ovulation

Bone morphogenetic protein 15 (BMP15) is a multifunctional oocyte-specific secreted factor. It controls female fertility and follicular development in both species-specific and dosage-sensitive manners. Previous studies found that BMP15 played a critical role on follicular development and ovulation rate of mono-ovulatory mammalian species, but has minimal impact on poly-ovulatory mice. However, whether this is true in non-rodent poly-ovulatory species need to be validated. To investigate this question, we generated a BMP15 knockdown pig model. We found that BMP15 knockdown gilts showed markedly reduced fertility accompanied with phenotype of dysplastic ovaries containing significantly declined number of follicles, increased number of abnormal follicles, and abnormally enlarged antral follicles resulting in disordered ovulation. Molecular and transcriptome analysis revealed that knockdown of BMP15 significantly suppressed cell proliferation, differentiation, Fshr expression, leading to premature luteinization and reduced estradiol production in GCs, and simultaneously decreased the quality and meiotic maturation of oocyte. Our results provide in vivo evidences for the essential role of BMP15 in porcine ovarian and follicular development, and new insight into the complicated regulatory function of BMP15 in female fertility of poly-ovulatory species.

developmental biology↗

Functional analysis of KIT gene structural mutations causing porcine dominant white phenotype by using genome edited mouse models

Dominant white phenotype in pigs is considered to be caused by two structural mutations in KIT gene, including a 450-kb duplication encompassing the entire KIT gene, and a splice mutation (G > A) at the first base in intron 17, which leads to the deletion of exon 17 in mature KIT mRNA, and the production of KIT protein lacking a critical catalytic domain of kinase. However, this speculation has not yet been validated by functional studies. Here, by using CRISPR/Cas9 technology, we created two mouse models mimicing the structural mutations of KIT gene in dominant white pigs, including the splice mutation mouse model KIT D17/+ with exon 17 of one allele of KIT gene deleted, and duplication mutation mouse model KIT Dup/+ with one allele of KIT gene coding sequence (CDS) duplicated. We found that each mutation individually can not cause dominant white phenotype. Splice mutation homozygote is lethal and heterozygous mice present piebald coat. Inconsistent with previous speculation, we found KIT gene duplication mutation did not confer the patched phenotype, and had no obvious impact on coat color. Interestingly, combination of these two mutations lead to dominant white phenotype. Further molecular analysis revealed that combination of these two structural mutations could inhibit the kinase activity of the KIT protein, thus reduce the phosphorylation level of PI3K and MAPK pathway associated proteins, which may be related to the observed impaired migration of melanoblasts during embryonic development, and eventually lead to dominant white phenotype. Our study provides a further insight into the underlying genetic mechanisms of porcine dominant white coat colour.\n\nAuthor summaryKIT plays a critical role in control of coat colour in mammals. Two mutation coexistence in KIT are considered to be the cause of the Dominant white phenotype in pigs. One mutation is a 450-kb large duplication encompassing the entire KIT gene, another mutation is a splice mutation causing the skipping of KIT exon 17. The mechanism of these two mutations of KIT on coat color formation has not yet been validated. In this study, by using genome edited mouse models, we found each structural mutation individual does not lead dominant white phenotype, but combination of these two mutations could lead to a nearly complete white coat colour similar to pig dominant white phenotype, possibly due to the inhibition of the kinase activity of the KIT protein, thus its signalling function on PI3K and MAPK pathways, leading to impaired migration of melanoblasts during embryonic development, and eventually lead to dominant white phenotype. Our study provides a further insight into the underlying genetic mechanisms of porcine dominant white coat colour.

molecular biology↗