Biology subjects

Shen, S.

Publications and source records attributed to Shen, S..

At least 55 records · Page 3Linked to original sources

bioRxiv2024

Proteomics analysis reveals novel phosphorylated residues and associated proteins of the polyomavirus DNA replication initiation complex.

Polyomavirus (PyV) Large T-antigen (LT) is the major viral regulatory protein that targets numerous cellular factors/pathways: tumor suppressors, cell cycle regulators, transcription and chromatin regulators, as well as other factors for viral replication. LT directly recruits the cellular replication factors involved in LTs recognition of the viral origin, origin unwinding, and primer synthesis which is carried out by mutual interactions between LT, DNA polymerase alpha-primase (Polprim), and single strand (ss) DNA binding replication protein A (RPA). The activities as well as interactions of these three with each other as well as other factors, are known to be modulated by post-translational modifications (PTMs); however, modern high-sensitivity proteomic analyses of the PTMs as well as proteins associated with the three have been lacking. Elution from immunoprecipitation (IP) of the three factors were subjected to high-resolution liquid chromatography tandem mass spectrometry (LC-MS/MS). We identified 479 novel phosphorylated amino acid residues (PAARs) on the three factors: 82 PAARs on SV40 LT, 305 on the Polprim heterotetrametric complex and 92 on the RPA heterotrimeric complex. LC-MS/MS analysis also identified proteins that co-immunoprecipitated (coIP-ed) with the three factors that were not previously reported: 374 with LT, 453 with Polprim and 183 with RPA. We used a bioinformatic-based approach to analyze the proteomics data and demonstrate a highly significant "enrichment" of transcription-related process associated uniquely with LT, consistent with its role as a transcriptional regulator, as opposed to Polprim and RPA associated proteins which showed no such enrichment. The most significant cell cycle related network was regulated by ETS proto-oncogene 1 (ETS1), indicating its involvement in regulatory control of DNA replication, repair, and metabolism. The interaction between LT and ETS1 is validated and shown to be independent of nucleic acids. One of the novel phosphorylated aa residues detected on LT from this study, has been demonstrated by us to affect DNA replication activities of SV40 Large T-antigen. Our data provide substantial additional novel information on PAARs, and proteins associated with PyV LT, and the cellular Polprim-, RPA- complexes which will benefit research in DNA replication, transformation, transcription, and other viral and host cellular processes.

microbiology↗

bioRxiv2023

Structural insights into specific recognition of PTENα/β-NTE by WDR5 in cancer progression

PTEN/{beta}, two variants of PTEN, play a key role in promoting tumor growth by interacting with WDR5 through their N-terminal extensions (NTEs). This interaction facilitates the recruitment of the SET1/MLL methyltransferase complex, resulting in histone H3K4 trimethylation and upregulation of oncogenes such as NOTCH3, which in turn promotes tumor growth. However, the molecular mechanism underlying this interaction has remained elusive. In this study, we determined the crystal structure of PTEN-NTE in complex with WDR5, which reveal that PTEN specifically binds to the WIN site of WDR5 through a novel binding motif specifically found in the NTE domain of PTEN/{beta}. Disruption of this interaction significantly impedes cell proliferation and tumor growth, highlighting the potential of the WIN site inhibitors of WDR5 as therapeutic agents for PTEN/{beta} associated cancers. These findings not only shed light on the important role of the PTEN/{beta}-WDR5 interaction in carcinogenesis, but also present a promising avenue for developing cancer treatments that target this pathway.

cancer biology↗

bioRxiv2023

Beyond BioID: Streptavidin outcompetes antibody fluorescence signals in protein localization and readily visualises targets evading immunofluorescence detection.

Immunofluorescence is a common method to localise proteins within their cellular context via fluorophore labelled antibodies and for some applications without alternative. However, some protein targets evade detection due to low protein abundance or accessibility issues. In addition, some imaging methods require a massive reduction in antigen density thus impeding detection of even medium-abundant proteins. Here, we show that the fusion of the target protein to TurboID, a biotin ligase labelling lysine residues in close proximity, and subsequent detection of biotinylation by fluorescent streptavidin offers an "all in one" solution to the above-mentioned restrictions. For a wide range of target proteins tested, the streptavidin signal was significantly stronger than an antibody signal, markedly improving the imaging sensitivity in expansion microscopy and correlative light and electron microscopy, with no loss in resolution. Importantly, proteins within phase-separated regions, such as the central channel of the nuclear pores, the nucleolus or RNA granules, were readily detected with streptavidin, while most antibodies fail to label proteins in these environments. When TurboID is used in tandem with an HA epitope tag, co-probing with streptavidin and anti-HA can be used to map antibody- accessibility to certain cellular regions. As a proof of principle, we mapped antibody access to all trypanosome nuclear pore proteins (NUPs) and found restricted antibody labelling of all FG NUPs of the central channel that are known to be phase-separated, while most non-FG Nups could be labelled. Lastly, we show that streptavidin imaging can resolve dynamic, temporally and spatially distinct sub-complexes and, in specific cases, reveal a history of dynamic protein interaction. In conclusion, streptavidin imaging has major advantages for the detection of lowly abundant or inaccessible proteins and in addition, can provide information on protein interactions and biophysical environment.

cell biology↗

bioRxiv2023

MdHY5 and MdHY5S form a transcription loop to regulate browning and phenolics synthesis in apple under purple light

Enzymatic browning significantly affects the appearance and quality of fresh-cut fruit. Light treatment can effectively inhibit fresh-cut apple browning via unknown molecular mechanisms. Here, we found that the application of purple LED light decreased the browning index of fresh-cut apple, delaying browning as compared to that of fresh-cut apple placed in the dark, and suggesting that purple LED light suppresses browning. In addition, the expression levels of MdHY5 and MdHY5S, important BASIC LEUCINE ZIPPER DOMAIN (bZIP) transcription factors that are involved in the light signaling pathway, were increased by purple LED light treatment. Silencing MdHY5 and MdHY5S in apple meant that purple LED light treatment no longer inhibited fresh-cut apple browning, the expression levels of the browning-related genes POLYPHENOL OXIDASE (MdPPO) and PEROXIDASE (MdPOD) increased, and the expression of the phenolic synthesis gene PHENYLALANINE AMMONIALYASE (MdPAL) decreased. Further study revealed that MdHY5 and MdHY5S bind to the MdPPO and MdPOD promoters, reducing their transcription. In contrast, MdHY5 and MdHY5S bind to the MdPAL promoter, enhancing transcription. Further research revealed that MdHY5 and MdHY5S also bind directly to each others promoters to form a positive transcriptional loop that activates their transcription. Our findings revealed that purple LED light inhibits browning and increases phenolics synthesis in fresh-cut apple by activating MdHY5 and MdHY5S. The results provide a theoretical basis upon which the new methods for improving the appearance and quality of fresh-cut apple can be based.

developmental biology↗

bioRxiv2023

Fecal microbial transfer and complex carbohydrates mediate protection against COPD

ObjectiveChronic obstructive pulmonary disease (COPD) is a major cause of global illness and death, most commonly caused by cigarette smoke. The mechanisms of pathogenesis remain poorly understood, limiting the development of effective therapies. The gastrointestinal microbiome has been implicated in chronic lung diseases via the gut-lung axis, but its role is unclear. DesignUsing an in vivo mouse model of cigarette smoke-induced COPD and fecal microbial transfer (FMT), we characterized the fecal microbiota using metagenomics, proteomics and metabolomics. Findings were correlated with airway and systemic inflammation, lung and gut histopathology, and lung function. Complex carbohydrates were assessed in mice using a high resistant starch diet, and in sixteen COPD patients using a randomized, double-blind, placebo-controlled pilot study of inulin supplementation. ResultsFMT alleviated hallmark features of COPD (inflammation, alveolar destruction, impaired lung function), gastrointestinal pathology and systemic immune changes. Protective effects were additive to smoking cessation. Disease features correlated with the relative abundance of Muribaculaceae, Desulfovibrionaceae and Lachnospiraceae family members. Proteomics and metabolomics identified downregulation of glucose and starch metabolism in cigarette smoke-associated microbiota, and supplementation of mice or human patients with complex carbohydrates improved disease outcomes. ConclusionThe gut microbiome contributes to COPD pathogenesis and can be targeted therapeutically. What is already known on this topicO_LIChanges in gut microbiota are associated with COPD but the underlying host and microbial mechanisms are unclear, limiting the therapeutic applications. C_LI What this study addsO_LIMicrobiome composition and metabolism is reproducibly correlated with lung and gastrointestinal pathology in experimental COPD. C_LIO_LIMicrobiome modifying interventions effectively alleviate disease, including protective effects supplementing smoking cessation. C_LIO_LINutritional interventions targeting the microbiome in COPD patients demonstrate efficacy in a small pilot study. C_LI How this study might affect research, practice or policyO_LIMicrobiome-targeting therapeutics and nutritional interventions may be developed for COPD, including as supplements to smoking cessation. C_LI

physiology↗

bioRxiv2023

DNA damaged-induced phosphorylation of a viral replicative DNA helicase results in inhibition of DNA replication through attenuation of helicase function

A major function of the DNA damage responses (DDRs) that act during the replicative phase of the cell cycle is to inhibit initiation and elongation of DNA replication. The polyomavirus SV40 is an important model system for studying human DNA replication and DDRs due to its heavy reliance on host factors for viral DNA replication, and the arrest of SV40 DNA replication in response to DDR activation. The inhibition of SV40 DNA replication following DDR activation is associated with enhanced DDR kinase phosphorylation of SV40 Large T-antigen (LT), the viral origin-binding protein and DNA helicase. NetPhos prediction of LT phosphorylation on multiple sites were confirmed by mass spectroscopy, including a highly conserved DDR kinase site, T518. In cell-based DNA replication assays expression of the phosphomimetic mutant form of LT at T518 (T518D) resulted in dramatically decreased levels of SV40 DNA replication; while LT-dependent transcriptional activation was unaffected. WT and LT T518D were subsequently expressed, purified, and analyzed in vitro for assessment of biochemical function. In concordance with the cell-based data, reactions using SV40 LT-T518D, but not T518A, showed dramatic inhibition of SV40 DNA replication. Importantly, the LT T518D mutation did not affect critical LT protein interactions or its ATPase function, but showed decreased helicase activity on long, but not very short, DNA templates. These results suggest that DDR phosphorylation at T518 inhibits SV40 DNA replication by impeding LT helicase activity, thereby slowing the DNA replication fork. This is consistent with the slowing of cellular replication forks following DDR and may provide a paradigm for another mechanism for how DNA replication forks can be slowed in response to DDR, by phosphorylation of DNA helicases.

microbiology↗

bioRxiv2023

Development of LIBRA-seq for the Guinea Pig Model System as a Tool for the Evaluation of Antibody Responses to Multivalent HIV-1 Vaccines

Consistent elicitation of serum antibody responses that neutralize diverse clades of HIV-1 remains a primary goal of HIV-1 vaccine research. Prior work has defined key features of soluble HIV-1 Envelope (Env) immunogen cocktails that influence the neutralization breadth and potency of multivalent vaccine-elicited antibody responses including the number of Env strains in the regimen. We designed immunization groups that consisted of different numbers of Env strains to be used in a cocktail immunization strategy: the smallest cocktail (group 2) consisted of a set of two Env strains, which were a subset of the three Env strains that made up group 3, which in turn were a subset of the six Env strains that made up group 4. Serum neutralizing titers were broadest in guinea pigs that were immunized with a cocktail of three Envs compared to cocktails of two and six, suggesting that multivalent Env immunization provides a benefit but may be detrimental when the cocktail size is too large. We then adapted the LIBRA-seq platform for antibody discovery to be compatible with guinea pigs, and isolated several tier 2 neutralizing monoclonal antibodies. Three antibodies isolated from two separate guinea pigs were similar in their gene usage and CDR3s, establishing evidence for a guinea pig public clonotype elicited through vaccination. Taken together, this work investigated multivalent HIV-1 Env immunization strategies and provides a novel methodology for screening guinea pig B cell receptor antigen specificity at a high throughput level using LIBRA-seq. IMPORTANCEMultivalent vaccination with soluble Env immunogens is at the forefront of HIV-1 vaccination strategies, but little is known about the influence of the number of Env strains included in vaccine cocktails. Our results suggest that adding more strains is sometimes beneficial but may be detrimental when the number of strains is too high. Additionally, we adapted the LIBRA-seq platform to be compatible with guinea pig samples and isolated several tier 2 neutralizing monoclonal antibodies, some of which share V and J gene usage and >80% CDR3 identity, thus establishing the existence of public clonotypes in guinea pigs elicited through vaccination.

immunology↗

bioRxiv2023

Activation-induced shift in nutrient preference and function-specific nutrient dependence in human neutrophils

Neutrophils - the first responders in innate immunity - perform a variety of effector functions associated with specific metabolic demand. To maintain fitness and support functions, neutrophils have been found to utilize extracellular glucose, intracellular glycogen, and other alternative substrates. However, the quantitative contribution of these nutrients under specific conditions and the relative dependence of various cell functions on specific nutrients remain unclear. Here, using ex vivo and in vivo isotopic tracing, we reveal that under resting condition, human peripheral blood neutrophils, in contrast to in vitro cultured human neutrophil-like cell lines, rely on glycogen as a major direct source of glycolysis and pentose phosphate pathway. Upon activation with a diversity of stimuli, neutrophils undergo a significant and often rapid nutrient preference shift, with glucose becoming the dominant metabolic source thanks to a multi-fold increase in glucose uptake mechanistically mediated by the phosphorylation and translocation of GLUT1. At the same time, cycling between gross glycogenesis and glycogenolysis is also substantially increased, while the net flux favors sustained or increased glycogen storage. The shift in nutrient utilization impacts neutrophil functions in a function-specific manner. The activation of oxidative burst specifically depends on the utilization of extracellular glucose rather than glycogen. In contrast, the release of neutrophil traps can be flexibly supported by either glucose or glycogen. Neutrophil migration and fungal control is promoted by the shift away from glycogen utilization. Together, these results quantitatively characterize fundamental features of neutrophil metabolism and elucidate how metabolic remodeling shapes neutrophil functions upon activation.

biochemistry↗

bioRxiv2023

Exogenous Methylglyoxal Improves Maize Yield by Alleviating Plant Diabetes and leaf senescence under Drought

Drought-induced leaf senescence is related to high sugar levels in leaves, photosynthesis inhibition, and ultimate yield loss. This physiological phenomenon in leaves bears resemblance to the symptom of diabetes in human disease. However, the underlying mechanisms of plant diabetes on carbon imbalance in maize leaf and corresponding detoxification strategy have not been well understood. In this study, we demonstrated that foliar application of exogenous methylglyoxal (MG) delayed leaf senescence and promoted photoassimilation, retrieved 14% yield loss induced by drought stress during grain filling stage. Transcriptome and metabolite analysis revealed that drought increased sugar accumulation in leaf with inhibition of sugar transporters facilitating phloem loading. This further lead to disequilibrium of glycolysis and over-accumulation of endogenous MG. Contrarily, exogenous MG significantly upregulated glycolytic flux and glyoxalase system catabolizing endogenous MG and advanced glycation end products toxicity, ultimately alleviating plant diabetes. Besides, the genes facilitating anabolism and catabolism of trehalose- 6-phosphate were promoted and suppressed by drought, respectively, whereas exogenous MG reversed the effect. Moreover, exogenous MG activated phenylpropanoid biosynthetic pathway, likely promoting cell structural integrity. Collectively, these results suggest that exogenous MG alleviates the toxic effect from drought-induced sugar accumulation and activates the defense-related pathway, thereby maintaining leaf function and yield production. HighlightExogenous methylglyoxal stimulates glycolytic flux and glyoxalase system, providing a potential insight to alleviate plant diabetes under drought condition.

physiology↗

bioRxiv2023

High red/far-red ratio promotes root colonization of Serratia plymuthica A21-4 in tomato by root exudates-stimulated chemotaxis and biofilm formation

Effective colonization on plant roots is a prerequisite for plant growth promoting rhizobacterias (PGPR) to exert beneficial activities. Light is essential for plant growth, development and stress response. However, how light modulates root colonization of PGPR remains unclear. Here, we found that high red/far red(R/FR) light promoted and low R/FR light inhibited the colonization and growth enhancement of Serratia plymuthica A21-4 on tomato. Non-targeted metabolomic analysis of root exudates collected from different R/FR ratio treated tomato seedlings with A21-4 inoculation by ultra performance liquid chromatography-tandem mass spectrometry showed that 64 primary metabolites including amino acids, sugars and organic acids in high R/FR light-grown plants significantly increased compared with those determined for low R/FR light-grown plants. Among them, 7 amino acids, 1 organic acid and 1 sugar obviously induced the chemotaxis and biofilm formation of A21-4 compared to the control. Furthermore, exogenous addition of five artificial root exudate compontents (leucine, methionine, glutamine, 6-aminocaproic acid and melezitose) regained and further increased the colonization and growth promoting ability of A21-4 in tomato under low R/FR light and high R/FR light, respectively, indicating their involvement in high R/FR light-regulated the interaction of tomato root and A21-4. Taken together, our results, for the first time, clearly demonstrate that high R/FR light-induced root exudates play a key role in chemotaxis, biofilm formation and root colonization of A21-4. This study provides new insights into the interactions of plant-PGPR under different light conditions and can help promote the combined application of light supplementation and PGPR to facilitate crop growth and health in green agricultural production.

microbiology↗

bioRxiv2023

In Vivo Three-dimensional Brain Imaging with Chemiluminescence Probes in Alzheimers Disease Models

Optical three-dimensional (3D) molecular imaging is highly desirable for providing precise distribution of the target-of-interest in disease models. However, such 3D imaging is still far from wide applications in biomedical research; 3D brain optical molecular imaging, in particular, has rarely been reported. In this report, we designed chemiluminescence probes with high quantum yields (QY), relatively long emission wavelengths, and high signal-to-noise ratios (SNRs) to fulfill the requirements for 3D brain imaging in vivo. With assistance from density-function theory (DFT) computation, we designed ADLumin-Xs by locking up the rotation of the double-bond via fusing the furan ring to the phenyl ring. Our results showed that ADLumin-5 had a high quantum yield of chemiluminescence and could bind to amyloid beta (A{beta}). Remarkably, ADLumin-5s radiance intensity in brain areas could reach 4x107 photon/s/cm2/sr, which is probably 100-fold higher than most chemiluminescence probes for in vivo imaging. Because of its strong emission, we demonstrated that ADLumin-5 could be used for in vivo 3D brain imaging in transgenic mouse models of Alzheimers disease (AD). Significance StatementAlthough MRI, PET, CT, and SPECT have been routinely used for 3D imaging, including 3D brain imaging, they are considerably expensive. Optical imaging is largely low-cost and high throughput. However, the 3D capacity of optical imaging is always limited. Obviously, optical 3D molecular imaging is highly challenging, particularly for 3D brain imaging. In this report, we provided the first example of 3D brain imaging with chemiluminescence probes ADLumin-Xs, which have advantages in quantum yields (QY), emission wavelengths, and signal-to-noise ratios (SNRs) to fulfill the requirements for 3D brain imaging. And we believe that such 3D capacity is potentially a game-changer for brain molecular imaging in preclinical studies.

bioengineering↗

bioRxiv2023

Cell Type-Specific Regulation by a Heptad of Transcription Factors in Human Hematopoietic Stem and Progenitor Cells

Hematopoietic stem and progenitor cells (HSPCs) rely on a complex interplay of transcription factors (TFs) to regulate differentiation into mature blood cells. A heptad of TFs - FLI1, ERG, GATA2, RUNX1, TAL1, LYL1, LMO2 - bind regulatory elements in bulk CD34+ HSPCs. However, whether specific heptad-TF combinations have distinct roles in regulating hematopoietic differentiation remained unknown. We mapped genome-wide chromatin contacts and TF binding profiles in HSPC subsets (HSC, CMP, GMP, MEP) and found that heptad occupancy and enhancer-promoter interactions varied significantly across cell types and were associated with cell-type-specific gene expression. Distinct regulatory elements were enriched with specific heptad-TF combinations, including stem-cell-specific elements with ERG, and myeloid- and erythroid-specific elements with combinations of FLI1, RUNX1, GATA2, TAL1, LYL1, and LMO2. These findings suggest that specific heptad-TF combinations play critical roles in regulating hematopoietic differentiation and provide a valuable resource for development of targeted therapies to manipulate specific HSPC subsets.

developmental biology↗

bioRxiv2023

Plasma cells in human pancreatic ductal adenocarcinoma secrete antibodies to self-antigens

Intratumoral B cell responses are associated with more favorable clinical outcomes in human pancreatic ductal adenocarcinoma (PDAC). However, the antigens driving these B cell responses are largely unknown. We sought to discover these antigens by using single-cell RNA sequencing (scRNA-Seq) and immunoglobulin (Ig) sequencing of tumor-infiltrating immune cells from seven primary PDAC samples. We identified activated T and B cell responses and evidence of germinal center reactions. Ig sequencing identified plasma cell (PC) clones expressing isotype-switched and hyper-mutated Igs, suggesting the occurrence of T cell-dependent B cell responses. We assessed the reactivity of 41 recombinant antibodies that represented the products of 235 PCs and 12 B cells toward multiple cell lines and PDAC tissues, and observed frequent staining of intracellular self-antigens. Three of these antigens were identified: the filamentous actin (F-actin), the nucleic protein, RUVBL2, and the mitochondrial protein, HSPD1. Antibody titers to F-actin and HSPD1 were elevated in the plasma of PDAC patients, and also detectable in healthy donors. Thus, PCs in PDAC produce auto-antibodies reacting with intracellular self-antigens, which may result from promotion of pre-existing, autoreactive B cell responses. These observations indicate that the chronic inflammatory microenvironment of PDAC can support the adaptive immune response.

cancer biology↗

bioRxiv2023

Proliferating cell nuclear antigen involves in temperature stress tolerance of Ulva prolifera

Ulva prolifera is the dominant species of "green tide", and has higher tolerance to environmental stresses such as temperature. However, the molecular mechanisms are still unclear. Here, transcriptome analysis, Western blot and RT-qPCR analysis of U. prolifera suggested that, under temperature stresses (4{degrees}C, 36{degrees}C), the expression of PCNA and CyclinA was promoted, and the MAPK signaling was activated. Besides, the results showed that PCNA interacted with CyclinA. Interestingly, the expression of miR-2916, which was predicted to bind PCNA at -552[~]-772, was negatively correlated with the expression of PCNA under temperature stresses (4{degrees}C, 36{degrees}C). In addition, the results showed that low temperature (4{degrees}C) had no obvious effect on the survival, the formation of cell walls, and the division of protoplasts. However, high temperature (36{degrees}C) had obvious effect on them. PCNA inhibitors increased the sensitivity of the protoplasts under temperature stresses. Together, our results suggested PCNA regulating the proliferation in response to the temperature stress of U. prolifera was associated with miR-2916/PCNA/CyclinA/MAPK pathway. In conclusion, the study preliminarily illuminates the molecular mechanism in response to temperature stress of U. prolifera, and may provide a new insight for prevention of green tide.

cell biology↗

bioRxiv2023

Translational control by Trypanosoma brucei DRBD18 contributes to the maintenance of the procyclic state

Trypanosoma brucei occupies distinct niches throughout its life cycle, within both the mammalian and tsetse fly hosts. The immunological and biochemical complexity and variability of each of these environments require a reshaping of the protein landscape of the parasite both to evade surveillance and face changing metabolic demands. Whereas most well-studied organisms rely on transcriptional control as the main regulator of gene expression, post-transcriptional control mechanisms are particularly important in T. brucei, and these are often mediated by RNA-binding proteins. DRBD18 is a T. brucei RNA-binding protein that interacts with ribosomal proteins and translation factors. Here, we tested a role for DRBD18 in translational control. We show that DRBD18 depletion by RNA interference leads to altered polysomal profiles with a specific depletion of heavy polysomes. Ribosome profiling analysis reveals that 101 transcripts change in translational efficiency (TE) upon DRBD18 depletion: 41 exhibit decreased TE and 60 exhibit increased TE. A further 66 transcripts are buffered, i.e. changes in transcript abundance are compensated by changes in TE such that the total translational output is expected not to change. Proteomic analysis validates these data. In DRBD18-depleted cells, a cohort of transcripts that codes for procyclic form-specific proteins is translationally repressed while, conversely, transcripts that code for bloodstream form- and metacyclic form-specific proteins are translationally enhanced. These data suggest that DRBD18 contributes to the maintenance of the procyclic state through both positive and negative translational control of specific mRNAs.

microbiology↗

bioRxiv2023

Identification of key virus--prokaryote infection pairs that contribute to viral shunt in a freshwater lake

Viruses infect and kill productive prokaryotes in a density-or frequency-dependent manner and affect carbon cycling. However, the effects of the stratification transition, including the stratified and destratified periods, on the changes in prokaryotic/viral communities and the interactions among them remain unclear. We conducted a monthly survey of the surface and deep layers of a large and deep freshwater lake (Lake Biwa, Japan) for a year and analyzed the prokaryotic production and prokaryotic/viral metagenome. Our analysis (including 1 608 prokaryotes and 13 761 viruses) revealed that 19 prokaryotic species, accounting for [~]40% of total abundance, might be suppressed by viruses when prokaryotic production is higher. This suggests that a small proportion of prokaryotes contribute to a large amount of prokaryotic abundance, and these prokaryotes are infected and lysed by viruses, driving the viral shunt in the freshwater lake. Furthermore, we found that annual vertical mixing might yield a similar rate of community change between the surface and deep layers. This finding might be valuable in understanding how the communities change when the stratification of freshwater lakes is affected by global warming in the future.

microbiology↗

bioRxiv2023

A tessellated lymphoid network provides whole-body T cell surveillance in zebrafish

Homeostatic trafficking to lymph nodes allows T cells to efficiently survey the host for cognate antigen. Non-mammalian jawed vertebrates lack lymph nodes but maintain similarly diverse T cell pools. Here, we exploit in vivo imaging of transparent zebrafish to investigate how T cells organize and survey for antigen in an animal devoid of lymph nodes. We find that naive-like T cells in zebrafish organize into a previously undescribed whole-body lymphoid network that supports streaming migration and coordinated trafficking through the host. This network has the cellular hallmarks of a mammalian lymph node, including naive T cells and CCR7-ligand expressing non-hematopoietic cells, and facilitates rapid collective migration. During infection, T cells transition to a random walk that supports antigen presenting cell interactions and subsequent activation. Our results reveal that T cells can toggle between collective migration and individual random walks to prioritize either large-scale trafficking or antigen search in situ. This novel lymphoid network thus facilitates whole-body T cell trafficking and antigen surveillance in the absence of a lymph node system. Significance StatementIn mammals, lymph nodes play a critical role in the initiation of adaptive immune responses by providing a dedicated place for T cells to scan antigen-presenting cells. Birds, reptiles, amphibians, and fish all maintain diverse repertoires of T cells but lack lymph nodes, raising questions about how adaptive immunity functions in lower jawed vertebrates. Here, we describe a novel network of lymphocytes in zebrafish that supports whole-body T cell trafficking and provides a site for antigen search, mirroring the function of mammalian lymph nodes. Within this network, T cells can prioritize large-scale trafficking or antigen scanning by toggling between two distinct modes of migration. This network provides valuable insights into the evolution of adaptive immunity.

immunology↗

bioRxiv2022

SETD2 Deficiency Promotes Inflammatory Bowel Disease via Oxidative Stress and FasL-induced Apoptosis

SET-domain-containing 2 (SETD2) is known as the major trimethyltransferase that regulates the methylation of histone H3 lysine 36 (H3K36), which has been found frequently mutated in IBD samples. Although SETD2 deficiency has been proven to modulate oxidative stress, the specific mechanisms of SETD2 in IBD are still little known. To investigate the possible role of SETD2 in IBD, we generated and genotyped epithelium-specific deletion of Setd2 (Setd2Vil-KO) progeny mice to establish mice IBD pathology model and then studied molecular expression differences at mRNA and protein levels in the intestinal epithelial tissue of Setd2Vil-KO mice. Compared with Setd2F/F mice, the tissue of Setd2Vil-KO mice showed increases in oxidative stress and cell apoptosis level via RT-qPCR, while TUNEL assay and immunofluorescence showed significantly enhanced apoptotic signaling and FasL expression. Together, our findings highlight that SETD2 regulates oxidative stress and FasL-induced apoptosis in Setd2Vil-KO mice intestinal epithelial cells through epigenetics mechanisms, which plays an essential role in IBD pathogenesis. Therefore, our study provides new insights into the prevention and therapy of IBD from the perspective of epigenetic regulation.

molecular biology↗