Biology subjects
Publications and source records attributed to Shan, Y..
Withdraw statementThe authors have withdrawn this manuscript because [the current results no longer support the conclusion in the article]. Therefore, the authors do not wish this work to be cited as reference for the project. If you have any questions, please contact the corresponding author.
Inflammatory bowel diseases (IBD) arise from a convergence of underlying genetic susceptibility, environmental factors, and shifts in gut microbiota function and membership. Although the latter may trigger and contribute to IBD, there is little consensus on a specific causative pathogen. In this study, we demonstrate that commensal Bacteroides fragilis strains from ulcerative colitis (UC) patients before and during the development of ileal pouchitis engraft and promote colitis in specific pathogen free (SPF) IL-10 deficient (IL-10-/-) mice, but not in wild type SPF mice or when mono-associated in germ free mice. The colitis in IL-10-/- mice was also associated with significant alterations in commensal microbiota potentially important for maintaining intestinal and immune homeostasis. UC pouchitis B. fragilis also engrafts in DSS-induced colitis in WT SPF mice, indicating a fitness advantage under conditions of mucosal inflammation over other commensals in the gut microbiota. These findings show that gut inflammation promotes the expansion and fitness of UC-derived Bacteroides species that is associated with changes in the SPF gut microbiota and may be promote colitis in genetically susceptible hosts. ImportanceThis study supports the notion that human inflammatory bowel diseases arise from the emergence of indigenous pathobionts in genetically-prone subjects. Colitis-promoting pathobionts are well-suited to establish themselves in the host inflammatory environment and outcompete endogenous microbiota. Once engrafted, the pathobiont can further aggravate inflammation in a genetically-susceptible host. Such complex interplay among several factors creates a vicious pro-inflammatory cycle and promotes disease development. These findings are consistent with our previous clinical observation that B. fragilis, an otherwise low-abundance commensal species, expands prior to the development of UC pouchitis. We believe these findings are relevant to the pathogenesis of UC pouchitis and possibly human inflammatory bowel diseases in general, underscoring the role of commensal to pathobiont transitions, rather than classical pathogens, in promoting and exacerbating the onset of human IBD.
High-throughput drug screens are a powerful tool for cancer drug development. However, the results of such screens are often made available only as raw data, which is intractable for researchers without informatic skills, or as highly processed summary statistics, which can lack essential information for translating screening results into clinically meaningful discoveries. To improve the usability of these datasets, we developed Simplicity, a robust and user-friendly web interface for visualizing, exploring, and summarizing raw and processed data from high-throughput drug screens. Importantly, Simplicity allows for easy recalculation of summary statistics at user-defined drug concentrations. This allows Simplicitys outputs to be used with methods that rely on statistics being calculated at clinically relevant doses. Simplicity can be freely accessed at https://oncotherapyinformatics.org/simplicity/.
Channelrhodopsins harvest the light and convert photons to the cellular ion flow. The ion selectivity and activation mechanism at the atomic level remains unknown. Here we describe cryo-EM structures for H. catenoides kalium channelrhodopsin (HcKCR1), its paralog, sodium selective channelrhodopsin (HcCCR), an open state of HcKCR1 (C110T), the voltage-dependent inwardly rectifier (D116N) and higher potassium selective channelrhodopsin (B1ChR2) from Bilabrum sp, illuminating the ion selectivity and activation mechanism. Briefly, the hourglass shaped lumen is occupied by the stepwise dehydrated potassium in both intracellular and extracellular side. The aromatic amino acids likely function as partial dehydrated potassium filter in the extracellular lumen, and intracellular dehydrated ion occupying layer chooses the right size of dehydrated ion, thus specifying ion selectivity and the higher dehydration capacity, the higher potassium selectivity. Furthermore, structural comparison of HcKCR1 and C110T suggested that the conformational changes of retinal triggers the extracellular side of TM6 extension as well as the retinal interaction residues motion, which then leads to ion flow. Our results not only uncovered the ion selectivity mechanism of potassium or sodium selective channelrhodopsins, but also elucidated their activation mechanism. It may provide a framework for designing next generation optogenetic tools.
The CK1 family are conserved serine/threonine kinases with numerous substrates and cellular functions. The fission yeast CK1 orthologues Hhp1 and Hhp2 were first characterized as regulators of DNA repair, but the mechanism(s) by which CK1 activity promotes DNA repair had not been investigated. Here, we found that deleting Hhp1 and Hhp2 or inhibiting CK1 catalytic activities in yeast or in human cells activated the DNA damage checkpoint due to persistent double-strand breaks (DSBs). The primary pathways to repair DSBs, homologous recombination and non-homologous end joining, were both less efficient in cells lacking Hhp1 and Hhp2 activity. In order to understand how Hhp1 and Hhp2 promote DSB repair, we identified new substrates using quantitative phosphoproteomics. We confirmed that Arp8, a component of the INO80 chromatin remodeling complex, is a bona fide substrate of Hhp1 and Hhp2 that is important for DSB repair. Our data suggest that Hhp1 and Hhp2 facilitate DSB repair by phosphorylating multiple substrates, including Arp8.
Voltage gradient is a general physical cue that regulates diverse biological function through voltage-gated ion channels. How voltage sensing mediates ion flows remains unknown at the molecular level. Here, we report six conformations of the human Eag2 (hEag2) ranging from closed, pre-open, open, and pore dilation but non-conducting states captured by cryo-electron microscopy (cryo-EM). These multiple states illuminate dynamics of selectivity filter and ion permeating pathway with delayed rectifier property and Cole-Moore effect at the atomic level. Mechanistically, a short S4-S5 linker is coupled with the constrict sites to mediate voltage transducing in a non-domain-swapped configuration, resulting transitions for constrict sites of F464s and Q472s from gating to open state stabilizing for voltage energy transduction. Meanwhile, an additional ion occupied at positions S6 potassium ion confers the delayed rectifier property and Cole-Moore effects. These results provide novel insight into voltage transducing and potassium current across membrane, and shed light on the long-sought Cole-Moore effects.
Human Slack (hSlack) channel is abundantly expressed in the central nervous system and regulates numerous physiological processes. Here, we identified hSlack channel is a voltage dependent physical force induced desensitization potassium channel. In the cell-attached mode, hSlack exhibited large voltage dependent potassium currents without significant delayed rectification or C-type inactivation. After breaking the cell membrane resulting the inside-out mode, the potassium currents were largely inhibited and it transited to the strong voltage dependent delayed rectified state. Structural results suggested that the "S6 site" confers the voltage dependent delayed rectification of hSlack channel, like our recent finding in hEag2 channel (In revision). Strikingly, the physical force induced desensitization and gating kinetics transition are mediated by the gatekeeper lipids in the central pore. Our results reported a novel physical force sensing channel through the pore lipids mediating physical force induced desensitization and gating kinetics transition. It opens a new door to understand the molecular basis of mechanobiology.
H. catenoides kalium channelrhodopsins (HcKCR1 and HcKCR2) are potassium-selective light-gated ion channels with unique properties for optogenetics. Here we report cryo-electron microscopy (cryo-EM) structures of HcKCR1 and HcKCR2 with endogenous retinal. Strikingly, one structure of HcKCR1 represents the conducting state with continuous potassium ion flow in the lumen, while another in non-conducting state with discontinuous potassium ion flow. Further electrophysiological studies identified extracellular side of ion permeation region as the major element for channel potassium selectivity and retinal binding region for channel gating. Our results uncover the unprecedented potassium selectivity and light-gating mechanism, and may facilitate the rational design of new optogenetic tools.
AO_SCPLOWBSTRACTC_SCPLOWThe hypothalamic suprachiasmatic nucleus (SCN) is the central pacemaker for mammalian circadian rhythms. As such, this ensemble of cell-autonomous neuronal oscillators with divergent periods must maintain coordinated oscillations. To investigate ultrastructural features enabling such synchronization, 805 coronal ultrathin sections of mouse SCN tissue were imaged with electron microscopy and aligned into a volumetric stack, from which selected neurons within the SCN core were reconstructed in silica. We found that clustered SCN core neurons were physically connected to each other via multiple large soma-to-soma plate-like contacts. In some cases, a sliver of a glial process was interleaved. These contacts were large, covering on average [~]21% of apposing neuronal somata. It is possible that contacts may be the electrophysiological substrate for synchronization between SCN neurons. Such plate-like contacts may explain why synchronization of SCN neurons is maintained even when chemical synaptic transmission or electrical synaptic transmission via gap junctions is blocked. Such ephaptic contact-mediated synchronization among nearby neurons may therefore underlie the wave-like oscillations of circadian core clock genes and calcium signals observed in the SCN. SO_SCPLOWIGNIFICANCEC_SCPLOWThree-dimensional reconstruction of SCN tissue via serial electron microscopy revealed a novel structural feature of SCN neurons that may account for inter-neuronal synchronization that persists even when usual mechanisms of neuronal communication are blocked. We found that SCN core neurons are connected by multiple soma-soma contact specializations, ultrastructural elements that could enable synchronization of tightly packed neurons organized in clustered networks. This extensive network of plate-like soma-soma contacts among clustered SCN neurons may provide insight into how [~]20,000 autonomous neuronal oscillators with a broad range of intrinsic periods remain synchronized in the absence of ordinary communication modalities, thereby conferring the resilience required for the SCN to function as the mammalian circadian pacemaker.
Sequencing-based spatial transcriptomics (ST) is an emerging technique to study in situ gene expression patterns at the whole-genome scale. In addition to transcriptomic data, the technique usually generates matched histopathological images for the same tissue sample. ST data analysis is complicated by severe technical noise; matched histopathological images with high spatial continuity and resolution introduce complementary cellular phenotypical information and provide a chance to mitigate the noise in ST data. Hence, we propose a novel ST data analysis method called transcriptome and histopathological image integrative analysis for spatial transcriptomics (TIST), which integrates the information from sequencing-based ST data and histopathological images. TIST uses a Markov random field (MRF) model to learn the macroscopic cellular features from histopathological images and devises a random-walk-based strategy to integrate the extracted image features, the transcriptomic features and the location information for spatial cluster (SC) identification and gene expression enhancement. We tested TIST both on simulated datasets and on 33 real datasets; we found that TIST achieved superior performance on multiple tasks, which illustrates the utility of this method in facilitating the discovery of biological insights from sequencing-based ST data.
Rapeseed (Brassica napus) oil is a main vegetable oil source in the world. The devastating disease of stem rot caused by the necrotrophic fungus Sclerotinia sclerotiorum and pod shattering led to a great yield loss in Brassica napus. S.sclerotiorum infects the rapeseed by the detached floral petals, in which the released ascospores land and germinate as mycelium, then the petals fall on the leaves at lower part of the rapeseed and heavily attacks the leaves and stems. The prevention of petal-shedding is a promising approach to avoid the stem rot damage, moreover, longer period of flowering time will bring rapeseed flower tourism a huge economic benefit. Notably, IDA (INFLORESCENCE DEFICIENT IN ABSCISSION) and IDA-LIKE(IDL) protein control floral organ abscission in Arabidopsis thaliana. In our study, the precisely editing of two IDA homologues genes using CRISPR/Cas9 system in Brassica napus caused the petal attaching to the flower till pod mature and enhancing the silique dehiscence resistance. Incubating the S.sclerotiorum to petal showed the edited rapeseed avoiding the infection of S.sclerotiorum RNA-Seq analysis demonstrated that in the editted plant, the genes involed in IDA pathway were regulated, while other genes keep unaltered. Investigation of agronomic traits showed that no positive the agronimic traits was introduced in editted plant. Our study demonstrated that mutation of two BnaIDAs creating a promising germplasm for disease avoidance, siliques shattering resistance and flowering period elongation which will contribute great to rapeseed industry.
AO_SCPLOWBSTRACTC_SCPLOWIdentifying high-risk individuals with diseases through reliable prediction models guides screening and preventive treatment. Most complex diseases have a genetic basis influenced by multiple genes and so disease risk can be estimated using polygenic risk score (PRS) algorithms. Many PRS algorithms have been developed so far. Among them, BayesR shows good characteristics of unbiasedness, accuracy, sparseness, and robustness. It detects the associated SNPs, estimates the SNP effects, and makes prediction of disease risks based on all SNPs simultaneously. However, this method assumes that the phenotypes follow a Gaussian distribution, which cannot be met in case-control studies. Here, we made an extension of the BayesR method, called BayesRB, by adding auxiliary variables to the BayesR model. We explored the characteristics, efficacy, and accuracy of BayesRB when estimating SNP effects and predicting disease risks compared with three traditional algorithms under different conditions using both simulated data and real data from the Welcome Trust Case Control Consortium (WTCCC). For SNP effect estimation, BayesRB shows unbiasedness and sparseness for big and small effect SNPs, respectively. For disease risk prediction, BayesRB had the best performance among the methods. This study provides a theoretical basis for complex disease risk prediction and disease prevention
Obtaining functional human cells through interspecies chimerism with human pluripotent stem cells (hPSCs) remains unsuccessful due to its extreamly low efficiency. Here, we show that hPSCs failed to differentiate and contribute teratoma in presence of mouse PSCs (mPSCs). While, MYCN, a pro-growth factor dramatically promotes hPSC contribution in teratoma co-formation by hPSCs/mPSCs. MYCN combined with BCL2 (M/B) greatly enhanced conventional hPSCs to integrate into preimplantation embryos of different species, such as mice, rabbits and pigs and substrantially contributed to mouse post-implantation chimera in embryonic and extra-embyonic tissues. Strikingly, M/B-hPSCs injected into preimplantation Flk-1+/- mouse embryos show further enhanced chimerism that allows obtaining live human CD34+ blood progenitor cells from chimeras through cell sorting. The chimera derived human CD34+ cells further gave rise to various subtype blood cells in typical colony forming unit(CFU) assay. Thus, we proof the concept to obtain functional human cells through enchanced interspecies chimerism with hPSCs.
We developed SpotLink software for identifying site non-specific cross-links at the proteome scale. Contributed by the dual pointer dynamic pruning (DPDP) algorithm and the quality control of cross-linking sites, SpotLink identified more than 3000 cross-links from human proteome database with rich site information in a few days. We demonstrated that SpotLink outperformed other approaches in terms of sensitivity and precision on a simulated dataset and a protein complexes dataset with known structures. Additionally, we discovered some valuable protein-protein interaction (PPI) information contained in the protein complexes dataset and HeLa dataset, indicating the unique identification advantages of site non-specific cross-linking. The excellent performance of SpotLink will increase the usage of site non-specific cross-linking in the near future. SpotLink is publicly available on GitHub [https://github.com/DICP1810/SpotLink].
Heterogeneity is the major challenge for cancer prevention and therapy. Here, we firstly constructed high-resolution spatial transcriptomes of primary liver cancers (PLCs) containing 84,823 spots within 21 tissues from 7 patients. The sequential comparison of spatial tumor microenvironment (TME) characteristics from non-tumor to leading-edge to tumor regions revealed that the tumor capsule potentially affects intratumor spatial cluster continuity, transcriptome diversity and immune cell infiltration. Locally, we found that the bidirectional ligand-receptor interactions at the 100 m wide cluster-cluster boundary contribute to maintaining intratumor architecture. Our study provides novel insights for diverse tumor ecosystem of PLCs and has potential benefits for cancer intervention.
Protein-protein interactions (PPIs) are ubiquitous biomolecular processes that are central to virtually all aspects of cellular function. Identifying small molecules that modulate specific disease-related PPIs is a strategy with enormous promise for drug discovery. The design of drugs to disrupt PPIs is challenging, however, because many potential drug-binding sites at PPI interfaces are "cryptic": When unoccupied by a ligand, cryptic sites are often flat and featureless, and thus not readily recognizable in crystal structures, with the geometric and chemical characteristics of typical small-molecule binding sites only emerging upon ligand binding. The rational design of small molecules to inhibit specific PPIs would benefit from a better understanding of how such molecules bind at PPI interfaces. To this end, we have conducted unbiased, all-atom MD simulations of the binding of four small-molecule inhibitors (SP4206 and three SP4206 analogs) to interleukin 2 (IL2)--which performs its function by forming a PPI with its receptor--without incorporating any prior structural information about the ligands binding. In multiple binding events, a small molecule settled into a stable binding pose at the PPI interface of IL2, resulting in a protein-small-molecule binding site and pose virtually identical to that observed in an existing crystal structure of the IL2-SP4206 complex. Binding of the small molecule stabilized the IL2 binding groove, which when the small molecule was not bound emerged only transiently and incompletely. Moreover, free energy perturbation (FEP) calculations successfully distinguished between the native and non-native IL2-small-molecule binding poses found in the simulations, suggesting that binding simulations in combination with FEP may provide an effective tool for identifying cryptic binding sites and determining the binding poses of small molecules designed to disrupt PPI interfaces by binding to such sites.
Zero-valent sulfur (ZVS) is a critical intermediate in the biogeochemical sulfur cycle. Up to date, sulfur oxidizing bacteria have been demonstrated to dominate the formation of ZVS. In contrast, formation of ZVS mediated by sulfate reducing bacteria (SRB) has been rarely reported. Here, we report for the first time that a typical sulfate reducing bacterium Desulfovibrio marinus CS1 directs the formation of ZVS via sulfide oxidation. In combination with proteomic analysis and protein activity assays, thiosulfate reductase (PhsA) and sulfide: quinone oxidoreductase (SQR) were demonstrated to play key roles in driving ZVS formation. In this process, PhsA catalyzed thiosulfate to form sulfide, which was then oxidized by SQR to form ZVS. Consistently, the expressions of PhsA and SQR were significantly up-regulated in strain CS1 when cultured in the deep-sea cold seep, strongly indicating strain CS1 might form ZVS in its real inhabiting niches. Notably, homologs of phsA and sqr widely distributed in the metagenomes of deep-sea SRB. Given the high abundance of SRB in cold seeps, it is reasonable to propose that SRB might greatly contribute to the formation of ZVS in the deep-sea environments. Our findings add a new aspect to the current understanding of the source of ZVS.
Chloroflexi bacteria are abundant and globally distributed in various unexplored biospheres on Earth. However, only few Chloroflexi members have been cultivated, hampering further understanding of this important group. In the current study, we firstly clarify the high abundance of the phylum Chloroflexi in deep-sea sediments via the operational taxonomic units analysis. We further successfully isolate a novel Chloroflexi strain ZRK33 from cold seep sediments by using an enrichment medium constantly supplemented with rifampicin. Phylogenetic analyses based on 16S rRNA gene, genome, RpoB and EF-tu proteins indicate that strain ZRK33 represents a novel class, and the class is designated as Sulfochloroflexia because whole set of genes encoding key enzymes responsible for assimilatory sulfate reduction are identified in the genome of strain ZRK33. Indeed, assimilation of sulfate or thiosulfate by strain ZRK33 evidently benefits its growth and morphogenesis. Proteomic results suggest that metabolization of sulfate or thiosulfate significantly promotes the transport and degradation of various macromolecules and thereby stimulating the energy production. Notably, the putative genes associated with assimilatory and dissimilatory sulfate reduction ubiquitously distribute in the metagenome-assembled genomes of 27 Chloroflexi members derived from deep-sea sediments, strongly suggesting that Chloroflexi bacteria play undocumented key roles in deep-sea sulfur cycling.