Project description:The nuclei of rod photoreceptors in mice and other nocturnal species have an unusual inverted chromatin structure with centrally located heterochromatin that helps to focus light and improve photosensitivity. To gain a deeper understanding of this unique nuclear organization of rod photoreceptors, we have carried out Hi-C on retina at 3 stages of development and on purified rod photoreceptors. Predicted looping interactions from the Hi-C data were validated with fluorescent in situ hybridization (FISH). We discovered that a subset of genes important for retinal development, cancer and stress response in the retina are localized to the facultative heterochromatin domain in a developmental stage– and cell type–specific manner. We used machine learning to develop an algorithm based on our chromatin Hidden Markov Modeling (chromHMM) of retinal development to predict heterochromatin domains and study their dynamics during retinogenesis. FISH data for 264 genomic loci were used to train and validate the algorithm. These integrated data (https://pecan.stjude.cloud/retinalnucleome) were used to identify a developmental stage- and cell type-specific core regulatory circuit super-enhancer (CRC-SE) upstream of the Vsx2 gene that is required for bipolar neuron expression. Deletion of the Vsx2 CRC-SE in mice led to the loss of bipolar neurons in the retina.
Project description:More than 8,000 genes are turned on or off as progenitor cells produce the 7 classes of retinal cell types during development. Thousands of enhancers are also active in the developing retinae, many having features of cell- and developmental stage-specific activity. We studied dynamic changes in the 3D chromatin landscape important for precisely orchestrated changes in gene expression during retinal development by ultra-deep in situ Hi-C analysis on murine retinae. We identified developmental-stage-specific changes in chromatin compartments and enhancer-promoter interactions. We developed a machine learning-based algorithm to map euchromatin and heterochromatin domains genome-wide and overlaid it with chromatin compartments identified by Hi-C. Single-cell ATAC-seq and RNA-seq were integrated with our Hi-C and previous ChIP-seq data to identify cell- and developmental-stage-specific super-enhancers (SEs). We identified a bipolar neuron-specific core regulatory circuit SE upstream of Vsx2, whose deletion in mice led to the loss of bipolar neurons.
Project description:Ten-eleven translocation (Tet) hydroxylases (Tet1-3) oxidize 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC). In neurons increased 5hmC levels within gene bodies correlate positively with gene expression. Here, we studied 5hmC profiles (hMeDIP) during retinal maturation between postnatal week 2 and postnatal week 3 using HiSeq 2000 instrument. Study of retinal 5hmC profile dynamics in 2-week old and 3-week old wild type (WT) mouse.
Project description:Germ cells are unique in engendering totipotency, yet the mechanisms underlying this capacity remain elusive. Here, we perform comprehensive and in-depth nucleome analysis of mouse germ-cell development in vitro, encompassing pluripotent precursors, primordial germ cells (PGCs) before and after epigenetic reprogramming, and spermatogonia/spermatogonial stem cells (SSCs). Although epigenetic reprogramming, including genome-wide DNA de-methylation, creates broadly open chromatin with abundant enhancer-like signatures, the augmented chromatin insulation safeguards transcriptional fidelity. These insulatory constraints are then erased en masse for spermatogonial development. Notably, despite distinguishing epigenetic programming, including global DNA re-methylation, the PGCs-to-spermatogonia/SSCs development entails further euchromatization. This accompanies substantial erasure of lamina-associated domains, generating spermatogonia/SSCs with a minimal peripheral attachment of chromatin except for pericentromeres—an architecture conserved in primates. Accordingly, faulty nucleome maturation, including persistent insulation and improper euchromatization, leads to impaired spermatogenic potential. Given that PGCs after epigenetic reprogramming serve as oogenic progenitors as well, our findings elucidate a principle for the nucleome programming that creates gametogenic progenitors in both sexes, defining a basis for nuclear totipotency.
Project description:Single cell RNA-sequencing shows cell type specific expression of genes in the retina. Single cell ATAC-sequencing of the wild type retina revealed that chromatin in the Vsx2 CRC SE, a stage- and cell type-specific core regulatory circuit super-enhancer (CRC-SE) upstream of the Vsx2 gene, was only open in bipolar cells. Deletion of the Vsx2 CRC-SE in mice led to the loss of bipolar neurons in the retina, which was confirmed by scRNA-sequencing of Vsx2SEKO mice.
Project description:The mature mammalian retina results from a complex series of developmental events. A lot of work now exists on the organization, function, and development of mouse retina, and the high-throughput technologies for gene expression analyses have helped us to obtain deep insight into the mechanism about the genes that control the retinal neurogenesis and vasculogenesis. MicroRNAs (miRNAs) are a class of endogenous non-coding RNAs that inhibit protein translation through binding to target mRNAs. miRNAs have been reported to be involved in regulating multiple physiological and pathological activities, such as ontogenesis, organogenesis, immunoprotection, and tumorigenesis. To identify miRNAs that are specifically regulated in retinal development, total RNAs isolated from retinas isolated from mice in different developmental periods were used for high-throughput sequencing. The data presented here reveals the spatiotemporal miRNA expression patterns which occur during mice retina development and provides a foundation to further investigate how miRNAs contribute to retinal neurogenesis and vasculogenesis.
Project description:In order to provide multi-omic resolution to human retinal organoid developmental dynamics, we performed scRNA-seq and scATAC-seq from the same cell suspension across a time course (6-46 weeks) of human retinal organoid development. This data set covers all the retinal organoid scRNA-seq data generated from IMR90 and409B2-iCas9 cell lines.