Biology subjects

Wu, J.

Publications and source records attributed to Wu, J..

At least 829 records · Page 46Linked to original sources

bioRxiv2019

CRISPR-assisted targeted enrichment-sequencing (CATE-seq)

The current targeted sequencing of genome is mainly dependent on various hybridization-based methods. However, the hybridization-based methods are still limited by the intrinsic shortcomings of nucleic acid hybridization. This study developed a new CRISPR-based targeted sequencing technique, CRISPR-assisted targeted enrichment-sequencing (CATE-seq). In this technique, the input genomic DNA (gDNA) was firstly bound by a complex of dCas9 and capture sgRNA (csgRNA). The DNA-dCas9-csgRNA complex was then captured on magnetic beads through an easy room-temperature annealing between a short universal capture sequence (24 bp) at the 3' end of csgRNA and capture oligonucleotide coupled on magnetic beads. The enriched DNAs were finally analyzed by next generation sequencing. Using this technique, three different scales of targeted enrichments were successfully performed, including enriching 35 target exons of 6 genes from 6 gDNA samples with 54 csgRNAs, 339 target exons of 186 genes from 9 gDNA samples with 367 csgRNAs, and 2031 target exons of 451 genes from 2 gDNA samples with 2302 csgRNAs. This technique has several significant advantages over the current hybridization-based methods, including high simplicity, specificity, sensitivity, throughput, and scalability.

cancer biology↗

bioRxiv2019

Bisphenol A promotes stress granule assembly and modulates the integrated stress response

Bisphenol-A (BPA) is a ubiquitous precursor of polycarbonate plastics that is found in the blood and serum of >92% of Americans. While BPA has been well documented to act as a weak estrogen receptor (ER) agonist, its effects on cellular stress are unclear. Here, we demonstrate that high-dose BPA causes stress granules (SGs) in human cells. A common estrogen derivative, {beta}-estradiol, does not trigger SGs, indicating the mechanism of SG induction is not via the ER pathway. We also tested other structurally related environmental contaminants including the common BPA substitutes BPS and BPF, the industrial chemical 4-nonylphenol (4-NP) and structurally related compounds 4-EP and 4-VP, and the pesticide 2,4-dichlorophenoxyacetic acid (2,4-D). The variable results from these related compounds suggest that structural homology is not a reliable predictor of the capacity of a compound to cause SGs. Also, we demonstrate that BPA acts primarily through the PERK pathway to generate canonical SGs. Finally, we show that chronic exposure to a low physiologically relevant dose of BPA disrupts SG assembly by inhibiting SGs upon additional acute stress. Our work identifies additional effects of BPA beyond endocrine disruption that may have consequences for human health.

cell biology↗

bioRxiv2019

Phylogenetic and structural diversity of aromatically dense pili from environmental metagenomes

Electroactive type IV pili, or e-pili, are used by some microbial species for extracellular electron transfer. Recent studies suggest that e-pili may be more phylogenetically and structurally diverse than previously assumed. Here, we used updated aromatic density thresholds ([≥]9.8% aromatic amino acids, [≤]22-aa aromatic gaps, and aromatic amino acids at residues 1, 24, 27, 50 and/or 51, and 32 and/or 57) to search for putative e-pilin genes in metagenomes from diverse ecosystems with active microbial metal cycling. Environmental putative e-pilins were diverse in length and phylogeny, and included truncated e-pilins in Geobacter spp., as well as longer putative e-pilins in Fe(II)-oxidizing Betaproteobacteria and Zetaproteobacteria.\n\nOriginality and SignificanceElectroactive pili (e-pili) are used by microorganisms to respire solid metals in their environment through extracellular electron transfer. Thus, e-pili enable microbes to occupy specific environmental niches. Additionally, e-pili have important potential for biotechnological applications. Currently the repertoire of known e-pili is small, and their environmental distribution is largely unknown. Using sequence analysis, we identified numerous genes encoding putative e-pili from diverse anoxic, metal-rich ecosystems. Our results expand the diversity of putative e-pili in environments where metal oxides may be important electron acceptors for microbial respiration.

microbiology↗

bioRxiv2019

Oncoprotein CoAA repeats interact with RNA polymerase II CTD repeats

The heptad repeating sequence of the C-terminal domain (CTD) of the largest subunit of RNA polymerase II is highly conserved in eukaryotes. In yeast, a CTD code consisting of pairs of heptad repeats is essential for viability. However, the strict requirement of diheptad repeats for the CTD function in transcription and splicing is unexplained. Here we show that CoAA (gene symbol RBM14), an oncoprotein and mammalian transcriptional coactivator, possesses diheptad repeats and directly interacts with the CTD. CoAA comprises 27 copies of tyrosine-rich repeats and regulates pre-mRNA synthesis and alternative splicing. Tyrosine substitutions in either the CoAA repeats or the CTD repeats diminish their interactions. Ser2- or Ser5-phosphorylated CTD peptides exhibit higher binding affinity to CoAA than the corresponding non-phosphorylated CTD peptide. CoAA dynamically interacts with both the CTD and hnRNP M, which is an alternative splicing regulator also comprising diheptad repeats. Arginine methylation of CoAA switches its interaction from the hnRNP M repeats to the CTD repeats. This study provides a mechanism for CoAA at the interface of transcription and alternative splicing, and explains the functional requirement of diheptad repeats in the CTD. In the human genome, tyrosine-rich repeats similar to the CoAA repeats were only found in six oncoproteins including EWS and SYT. We suggest that the diheptad sequence is one of the signature features for the CTD interaction among oncoproteins involved in transcription and alternative splicing. We anticipate that direct RNA Pol II interaction is a mechanism in oncogenesis.

biochemistry↗

bioRxiv2019

Distinct gut metagenomics and metaproteomics signatures in prediabetics and treatment-naïve type 2 diabetics

BackgroundThe gut microbiota plays important roles in modulating host metabolism. Previous studies have demonstrated differences in the gut microbiome of T2D and prediabetic individuals compared to healthy individuals, with distinct disease-related microbial profiles being reported in groups of different age and ethnicity. However, confounding factors such as anti-diabetic medication hamper identification of the gut microbial changes in disease development.\n\nMethodWe used a combination of in-depth metagenomics and metaproteomics analyses of faecal samples from treatment-naive type 2 diabetic (TN-T2D, n=77), pre-diabetic (Pre-DM, n=80), and normal glucose tolerant (NGT, n=97) individuals to investigate compositional and functional changes of the gut microbiota and the faecal content of microbial and host proteins in Pre-DM and treatment-naive T2D individuals to elucidate possible host-microbial interplays characterising different disease stages.\n\nFindingsWe observed distinct differences characterizing the gut microbiota of these three groups and validated several key features in an independent TN-T2D cohort. We also demonstrated that the content of several human antimicrobial peptides and pancreatic enzymes differed in faecal samples between three groups, such as reduced faecal level of antimicrobial peptides and pancreatic enzymes in TN-T2D.\n\nInterpretationOur findings suggest a complex, disease stage-dependent interplay between the gut microbiota and the host and emphasize the value of metaproteomics to gain further insight into interplays between the gut microbiota and the host.\n\nFundingNational Key Research and Development Program of China, No. 2017YFC0909703, Shenzhen Municipal Government of China, No. JCYJ20170817145809215, and National Natural Science Foundation of China, No. 31601073.

microbiology↗

bioRxiv2019

Massively parallel single-cell B-cell receptor sequencing enables rapid discovery of diverse antigen-reactive antibodies

Using high-throughput single-cell B-cell receptor sequencing (scBCR-seq) we obtained accurately paired full-length heavy- and light-chain variable domains from thousands of individual B cells in a massively parallel fashion. We sequenced more than 250,000 B cells from rat, mouse and human repertoires to characterize their lineages and expansion. In addition, we immunized rats with chicken ovalbumin and profiled antigen-reactive B cells from lymph nodes of immunized animals. The scBCR-seq data recovered 81% (n = 56/69) of B-cell lineages identified from hybridomas generated from the same set of B cells that were subjected to scBCR-seq. Importantly, scBCR-seq identified an additional 710 candidate lineages that were not recovered as hybridomas. We synthesized, expressed and tested 93 clones from the identified lineages and found that 99% (n = 92/93) of the clones were antigen-reactive. Our results establish scBCR-seq as a powerful tool for antibody discovery.

immunology↗

bioRxiv2019

Phosphatidylinositol Cycle Disruption is Central to Atypical Hemolytic-Uremic Syndrome Caused by Diacylglycerol Kinase Epsilon Deficiency

BackgroundLoss-of-function mutations in diacylglycerol kinase epsilon (DGKE) cause a rare form of atypical hemolytic-uremic syndrome (aHUS) for which there is no treatment besides kidney transplantation. Highly expressed in kidney endothelial cells, DGKE is a lipid kinase that phosphorylates diacylglycerol (DAG) to phosphatic acid (PA). Specifically, DGKEs preferred substrate is 38:4-DAG, that is DAG containing stearic acid (18:0) and arachidonic acid (20:4). DAG is produced when phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) is cleaved by phospholipase C (PLC). A better understanding of how DGKE deficiency impacts the endothelial lipid landscape is critical to developing a treatment for this condition.\n\nMethodsWe used orthogonal methods to compare the lipid levels in two novel models of DGKE deficiency to their respective controls: an immortalized human umbilical vein endothelial cell (iHUVEC) engineered with CRISPR/Cas9 and a blood outgrowth endothelial cell (BOEC) from an affected patient. Methods included mass spectrometry lipidomics, radiolabeling of phosphoinositides with [3H]myo-inositol, and live-tracking of a transfected fluorescent PtdIns(4,5)P2 biosensor.\n\nResultsUnexpectedly, mass spectrometry lipidomics data revealed that high 38:4-DAG was not observed in the two DGKE-deficient models. Instead, a reduction in 38:4-PtdIns(4,5)P2 was the major abnormality.These results were confirmed with the other two methods in DGKE-deficient iHUVEC.\n\nConclusionReduced 38:4-PtdIns(4,5)P2--but not increased 38:4-DAG--is likely to be key to the pro-thrombotic phenotype exhibited by patients with DGKE aHUS.\n\nTRANSLATIONAL STATEMENTMutations in DGKE cause a severe renal thrombotic microangiopathy that affects young children and leads to end-stage renal disease before adulthood. DGKE preferentially phosphorylates diacylglycerol to its corresponding phosphatidic acid (PA), which is then used to synthesize PtdIns(4,5)P2 via the phosphatidylinositol cycle. Understanding the disease pathophysiology is necessary to develop a treatment to prevent this outcome. This paper describes how we applied mass spectrometry lipidomics to two novel models of DGKE deficiency to investigate how this defect impacts the levels of diacylglycerol, PA and related phosphoinositides in endothelia. Unexpectedly, our data show that the critical abnormality caused by DGKE deficiency is not high diacylglycerol, but rather low PtdIns(4,5)P2. Restoring endothelial PtdIns(4,5)P2 homeostasis may be the cornerstone to treat these patients.

biochemistry↗

bioRxiv2019

Transferrin plays a central role to maintain coagulation balance by interacting with clotting factors

Coagulation balance is maintained through fine-tuning interactions among clotting factors. Physiological concentrations of clotting factors are huge difference. Especially, coagulation proteases concentration (pM to nM) is much lower than their natural inactivator antithrombin III (AT-III, [~]3 M). Here we show that transferrin (normal plasma concentration [~]40 M) interacts with fibrinogen, thrombin, FXIIa and AT-III with different affinity to maintain coagulation balance. Normally, transferrin is sequestered by binding with fibrinogen (normal plasma concentration [~]10 M) with a molar ratio of 4:1. In atherosclerosis, abnormally up-regulated transferrin interacts with and potentiates thrombin/FXIIa and blocks AT-IIIs inactivation on coagulation proteases by binding to AT-III, and thus induces hypercoagulability. In mouse models, transferrin-overexpression aggravated atherosclerosis while transferrin-knockdown, anti-transferrin antibody or designed peptides interfering transferrin-thrombin/FXIIa interactions alleviated it. Collectively, these findings identify transferrin as a clotting factor and an adjuster for maintaining coagulation balance and modify the coagulation cascade.

molecular biology↗

bioRxiv2019

Bimodal Regulation of the PRC2 Complex by USP7 Underlies Melanomagenesis

Although overexpression of EZH2, a catalytic subunit of the polycomb repressive complex 2 (PRC2), is an eminent feature of various cancers, the regulation of its abundance and function remains insufficiently understood. We report here that the PRC2 complex is physically associated with ubiquitin-specific protease USP7 in melanoma cells where USP7 acts to deubiquitinate and stabilize EZH2. Interestingly, we found that USP7-catalyzed H2BK120 deubiquitination is a prerequisite for chromatin loading of PRC2 thus H3K27 trimethylation. Genome-wide analysis of the transcriptional targets of the USP7/PRC2 complex identified a cohort of genes including FOXO1 that are involved in cell growth and proliferation. We demonstrated that the USP7/PRC2 complex drives melanoma cell proliferation and tumorigenesis in vitro and in vivo. We showed that the expression of both USP7 and EZH2 elevates during melanoma progression, corresponding to a diminished FOXO1 expression, and the level of the expression of USP7 and EZH2 strongly correlates with histological grades and prognosis of melanoma patients. These results reveal a dual role for USP7 in the regulation of the abundance and function of EZH2, supporting the pursuit of USP7 as a therapeutic target for melanoma.

cell biology↗

bioRxiv2019

Efficient pan-cancer whole-slide image classification and outlier detection using convolutional neural networks

Visual analysis of solid tissue mounted on glass slides is currently the primary method used by pathologists for determining the stage, type and subtypes of cancer. Although whole slide images are usually large (10s to 100s thousands pixels wide), an exhaustive though time-consuming assessment is necessary to reduce the risk of misdiagnosis. In an effort to address the many diagnostic challenges faced by trained experts, recent research has been focused on developing automatic prediction systems for this multi-class classification problem. Typically, complex convolutional neural network (CNN) architectures, such as Googles Inception, are used to tackle this problem. Here, we introduce a greatly simplified CNN architecture, PathCNN, which allows for more efficient use of computational resources and better classification performance. Using this improved architecture, we trained simultaneously on whole-slide images from multiple tumor sites and corresponding non-neoplastic tissue. Dimensionality reduction analysis of the weights of the last layer of the network capture groups of images that faithfully represent the different types of cancer, highlighting at the same time differences in staining and capturing outliers, artifacts and misclassification errors. Our code is available online at: https://github.com/sedab/PathCNN.

pathology↗

bioRxiv2019

Effect of Thrombospondin-4 on Pro-inflammatory Phenotype Differentiation and Apoptosis in Macrophages.

Thrombospondin-4 (TSP4) attracted a lot of attention recently as a result of new functions identified for this matricellular protein in cardiovascular, muscular, and nervous systems. We have previously reported that TSP4 promotes local vascular inflammation in mouse atherosclerosis model. A common variant of TSP4, P387-TSP4, was associated with increased cardiovascular disease risk in human population studies. In a mouse atherosclerosis model, TSP4 had profound effect on accumulation of macrophages in lesions, which prompted us to examine its effects on macrophages, more in detail in this report.\n\nWe examined the effects of A387-TSP-4 and P387-TSP-4 on mouse macrophages in cell culture and in vivo in the model of LPS-induced peritonitis. In tissues and in cell culture, TSP4 expression was associated with inflammation: TSP4 expression was upregulated in peritoneal tissues in LPS-induced peritonitis, and pro-inflammatory signals, INF{gamma}, GM-CSF, and LPS, induced TSP4 expression in macrophages in vivo and in cell culture. Deficiency in TSP-4 in macrophages from Thbs4-/- mice reduced the expression of pro-inflammatory macrophage markers, suggesting that TSP-4 facilitates macrophage differentiation into pro-inflammatory phenotype. Expression of TSP4, especially more active P387-TSP4, was associated with higher cellular apoptosis. Cultured macrophages displayed increased adhesion to TSP4 and reduced migration in presence of TSP4, and these responses were further increased with P387 variant.\n\nWe concluded that TSP4 expression in tissue macrophages and in cultured macrophages increases their accumulation in tissues during the acute inflammatory process and supports macrophage differentiation into a pro-inflammatory phenotype. In a model of acute inflammation, TSP4 supports pro-inflammatory macrophage apoptosis, a response that is closely related to their pro-inflammatory activity and release of pro-inflammatory signals. P387-TSP4 was found to be more active form of TSP4 in all examined functions.

cell biology↗

bioRxiv2019

Extensive genetic diversity of bat-borne polyomaviruses reveals inter-family host-switching events

Polyomaviruses (PyVs) are small, double-stranded DNA tumor viruses carried by diverse vertebrates. PyVs have previously been considered highly host restricted in mammalian hosts, with host-switching events thought rare or nonexistent. Prior investigations have revealed short-range host-switching events of PyVs in two different African bat species within the horseshoe bat genus Rhinolophus. Herein, we have conducted a systematic investigation of PyVs in 1,083 archived bat samples collected from five provinces across China, and identified 192 PyVs from 186 bats from 15 host species within 6 families (Rhinolophidae, Vespertilionidae, Hipposideridae, Emballonuridae, Miniopteridae and Pteropodidae) representing 28 newly-described PyVs, indicative of extensive genetic diversity of bat PyVs. Surprisingly, two PyVs were identified in multiple bat species from different families, and another PyV clustered phylogenetically with PyVs carried by bats from a different host family, indicative of three inter-family PyV host-switching events. The time to most recent common ancestor (tMRCA) of the three events was estimated at 0.02-11.6 million years ago (MYA), which is inconsistent with the estimated tMRCA of their respective bat hosts (36.3-66.7 MYA), and is most parsimoniously explained by host-switching events. PyVs identified from geographically separated Chinese horseshoe bat species in the present study showed close genetic identities, and clustered with each other and with PyVs from African horseshoe bats, allowing assessment of the effects of positive selection in VP1 within the horseshoe bat family Rhinolophidae. Correlation analysis indicated that co-evolution with their hosts contributed much more to evolutionary divergence of PyV than geographic distance. In conclusion, our findings provide the first evidence of inter-family host-switching events of PyV in mammals and challenge the prevailing evolutionary paradigm for strict host restriction of mammalian PyVs.\n\nAuthor summarySince the discovery of murine polyomavirus in the 1950s, polyomaviruses (PyVs) have been considered both genetically stable and highly host-restricted in their mammalian hosts. In this study, we have identified multiple cases of host-switching events of PyVs by large scale surveillance in diverse bat species collected in China. These host-switching events occurred between bat families living in the same colony, indicating that a large population with frequent contacts between different bat species may represent an ecological niche facilitating PyV host-switching. The cases studied involved members of bats from several families, including horseshoe bats, which were previously found to harbor a number of highly virulent viruses to both humans and domestic animals. Our findings have provided evidence that even highly host-specific DNA viruses can transmit between bats of different species and indicate an increased propensity for spillover events involving horseshoe bats. We propose an evolutionary scheme for bat-borne PyVs in which intra-host divergence and host-switching has generated the diverse PyVs in present day bats. This scheme provides a useful model to study the evolution of PyVs in other hosts and, potentially, the modeling of bat zoonoses and the transmission of other DNA viruses in other mammals, including humans.

microbiology↗

bioRxiv2019

Germline-encoded TCR-MHC contacts promote TCR V gene bias in umbilical cord blood T cell repertoire

T cells recognize antigens as peptides bound to major histocompatibility complex (MHC) proteins through T cell receptors (TCRs) on their surface. To recognize a wide range of pathogens, each individual possesses a substantial number of TCRs with an extremely high degree of variability. It remains controversial whether germline-encoded TCR repertoire is shaped by MHC polymorphism and, if so, what is the preference between MHC genetic variants and TCR V gene compatibility. To investigate the \"net\" genetic association between MHC variations and TRBV genes, we applied quantitative trait locus (QTL) mapping to test the associations between MHC polymorphism and TCR {beta} chain V (TRBV) genes usage using umbilical cord blood (UCB) samples of 201 Chinese newborns. We found TRBV gene and MHC loci that are predisposed to interact with one another differ from previous conclusions. The majority of MHC amino acid residues associated with the TRBV gene usage show spatial proximities in known structures of TCR-pMHC complexes. These results show for the first time that MHC variants bias TRBV gene usage in UCB of Chinese ancestry and indicate that germline-encoded contacts influence TCR-MHC interactions in intact T cell repertoires.

immunology↗

bioRxiv2019

Sing cell RNA-seq reveals cellular diversity and developmental characteristics of human infant retina

Retina, located in the innermost layer of the eye of human, holds the decisive role in visual perception. Dissecting the heterogeneity of retina is essential for understanding the mechanism of vision formation and even the development of central nervous system (CNS). Here, we performed single cell RNA-seq, analyzed 57,832 cells from human infant donors, resulting in 20 distinct clusters representing major cell types in retina: rod photoreceptors, cone photoreceptors, bipolar cells, horizontal cells, amacrine cells, Muller glia cells and microglia. We next constructed extensive networks of intercellular communication and identified ligand-receptor interactions playing crucial roles in regulating neural cell development and immune homeostasis in retina. Though re-clustering, we identified known subtypes in cone PRs and additional unreported subpopulations and corresponding markers in rod PRs as well as bipolar cells. Additionally, we linked inherited retinal disease to certain cell subtypes or subpopulations through enrichment analysis. Intriguingly, we found that status and functions of photoreceptors changed drastically between early and late retina. Overall, our study offers the first retinal cell atlas in human infants, dissecting the heterogeneity of retina and identifying the key molecules in the developmental process, which provides an important resource that will pave the way for retina development mechanism research and regenerative medicine concerning retinal biology.

cell biology↗

bioRxiv2019

Single cell RNA sequencing reveals cellular diversity of trisomy 21 retina

Retina is a crucial tissue for the capturing and processing of light stimulus. Characterization of the retina at single cell level is essential for the understanding of its biological functions. A variety of abnormalities in terms of morphology and function were reported in T21 retina. To evaluate the effects of chromosome aneuploidy on retina development, we characterized single cell transcriptional profiles of a T21 fetus and performed comprehensive bioinformatic analyses. Our data revealed the diversity and heterogeneity of cellular compositions in T21 retina. In total, we identified seven major cell types, and detected several subtypes within each cell type, followed by the detection of corresponding molecular markers including previously reported ones and a series of novel markers. Our analyses identified extensive communication networks between distinct cellular types, among which a few ligand-receptor interactions were associated with the development of retina and immunoregulatory interactions. Taken together, our data provided the first single cell transcriptome profile for human T21 retina which facilitates our understanding on the dosage effects of chromosome 21 on the development of retina.

cell biology↗

bioRxiv2019

Spatiotemporal restriction of FUSCA3 expression by class I BPC promotes ovule development and coordinates embryo and endosperm growth

Spatiotemporal regulation of gene expression plays an important role in developmental timing in plants and animals. FUSCA3 regulates the transition between different phases of development by acting as a link between different hormonal pathways in Arabidopsis. However, the mechanisms governing its spatiotemporal expression patterns are poorly understood. Here, we show that FUS3 is expressed in the chalaza and funiculus of the mature ovule and seed, but is repressed in the embryo sac, integuments and endosperm. FUS3 repression requires class I BASIC PENTACYSTEINE (BPC) proteins, which directly bind to the FUS3 locus and restrict its expression pattern. During vegetative and reproductive development, derepression of FUS3 in bpc1/2 or pML1:FUS3 misexpression lines results in dwarf plants carrying defective flowers and aborted ovules. Post-fertilization, ectopic FUS3 expression in the endosperm increases endosperm nuclei proliferation and seed size and delays or arrests embryo development. These phenotypes are rescued in bpc1/2 fus3-3. Lastly, class I BPCs interact with FIS-PRC2 (FERTILIZATION-INDEPENDENT SEED-Polycomb Repressive Complex 2), which represses FUS3 in the endosperm. We propose that BPC1/2 promotes the transition from reproductive to seed development by repressing FUS3 in ovule integuments. After fertilization, BPC1/2 and FIS-PRC2 repress FUS3 in the endosperm to coordinate endosperm and embryo growth.

plant biology↗

bioRxiv2019

Magnus Representation of Genome Sequences

We introduce an alignment-free method, the Magnus Representation, to analyze genome sequences. The Magnus Representation captures higher-order information in genome sequences. We combine our approach with the idea of k-mers to define an effectively computable Mean Magnus Vector. We perform phylogenetic analysis on three datasets: mosquito-borne viruses, filoviruses, and bacterial genomes. Our results on ebolaviruses are consistent with previous phylogenetic analyses, and confirm the modern viewpoint that the 2014 West African Ebola outbreak likely originated from Central Africa. Our analysis also confirms the close relationship between Bundibugyo ebolavirus and Tai Forest ebolavirus. For bacterial genomes, our method is able to classify relatively well at the family and genus level, as well as at higher levels such as phylum level. The bacterial genomes are also separated well into Gram-positive and Gram-negative subgroups.

genomics↗

bioRxiv2019

Three-dimensional genome reorganization during mouse spermatogenesis

Three-dimensional genome organization plays an important role in many biological processes. Yet, how the genome is packaged at the molecular level during mammalian spermatogenesis remains unclear. Here, we performed Hi-C in seven sequential stages during mouse spermatogenesis. We found that topological associating domains (TADs) and chromatin loops underwent highly dynamic reorganization. They displayed clear existence in primitive type A spermatogonia, disappearance at pachytene stage, and reestablishment in spermatozoa. Surprisingly, even in the absence of TADs and chromatin loops at pachytene stage, CTCF remained bound at TAD boundary regions (identified in primitive type A spermatogonia). Additionally, many enhancers and promoters exhibited features of open chromatin and transcription remained active at pachytene stage. A/B compartmentalization and segmentation ratio were conserved in different stages of spermatogenesis in autosomes, although there were A/B compartment switching events correlated with gene activity changes. Intriguingly, A/B compartment structure on the X chromosome disappeared during pacSC, rST and eST stages. Together, our work uncovered a dynamic three-dimensional chromatin organization during mouse spermatogenesis and suggested that transcriptional regulation could be independent of TADs and chromatin loops at specific developmental stages.

genomics↗