Project description:Germ cells are unique in that they tailor chromatin toward generating totipotency. Accordingly, mammalian spermatogonia, including spermatogonial stem cells (SSCs) which constitute the source for male gametes, acquire distinctive chromatin organization with weak insulation, but the underlying mechanism remains unknown. Here, we show that STAG3, this far known to exclusively form meiotic cohesins, generates a mitotic cohesin for male germline nucleome programming in mice. Due to its shorter chromatin residence, STAG3–cohesin attenuates topologically associating domains (TADs), rewires enhancer–promoter and Polycomb-mediated repressive interactions, and facilitates finer and more strengthened compartments, establishing a distinctive spermatogonial nucleome. Moreover, in the absence of STAG3–cohesin, SSCs show an impaired differentiation priming for spermatogenesis. Mitotic STAG3–cohesin is also expressed in human B cells and their malignant variations, promoting their propagation. Our findings on mitotic STAG3–cohesin elucidate a principle of male germline nucleome programming, demonstrate an unexpected mitotic role for STAG3 and might potentially improve understanding of human malignancies.
Project description:Germ cells are unique in that they tailor chromatin toward generating totipotency. Accordingly, mammalian spermatogonia, including spermatogonial stem cells (SSCs) which constitute the source for male gametes, acquire distinctive chromatin organization with weak insulation, but the underlying mechanism remains unknown. Here, we show that STAG3, this far known to exclusively form meiotic cohesins, generates a mitotic cohesin for male germline nucleome programming in mice. Due to its shorter chromatin residence, STAG3–cohesin attenuates topologically associating domains (TADs), rewires enhancer–promoter and Polycomb-mediated repressive interactions, and facilitates finer and more strengthened compartments, establishing a distinctive spermatogonial nucleome. Moreover, in the absence of STAG3–cohesin, SSCs show an impaired differentiation priming for spermatogenesis. Mitotic STAG3–cohesin is also expressed in human B cells and their malignant variations, promoting their propagation. Our findings on mitotic STAG3–cohesin elucidate a principle of male germline nucleome programming, demonstrate an unexpected mitotic role for STAG3 and might potentially improve understanding of human malignancies.
Project description:Germ cells are unique in that they tailor chromatin toward generating totipotency. Accordingly, mammalian spermatogonia, including spermatogonial stem cells (SSCs) which constitute the source for male gametes, acquire distinctive chromatin organization with weak insulation, but the underlying mechanism remains unknown. Here, we show that STAG3, this far known to exclusively form meiotic cohesins, generates a mitotic cohesin for male germline nucleome programming in mice. Due to its shorter chromatin residence, STAG3–cohesin attenuates topologically associating domains (TADs), rewires enhancer–promoter and Polycomb-mediated repressive interactions, and facilitates finer and more strengthened compartments, establishing a distinctive spermatogonial nucleome. Moreover, in the absence of STAG3–cohesin, SSCs show an impaired differentiation priming for spermatogenesis. Mitotic STAG3–cohesin is also expressed in human B cells and their malignant variations, promoting their propagation. Our findings on mitotic STAG3–cohesin elucidate a principle of male germline nucleome programming, demonstrate an unexpected mitotic role for STAG3 and might potentially improve understanding of human malignancies.
Project description:Germ cells are unique in that they tailor chromatin toward generating totipotency. Accordingly, mammalian spermatogonia, including spermatogonial stem cells (SSCs) which constitute the source for male gametes, acquire distinctive chromatin organization with weak insulation, but the underlying mechanism remains unknown. Here, we show that STAG3, this far known to exclusively form meiotic cohesins, generates a mitotic cohesin for male germline nucleome programming in mice. Due to its shorter chromatin residence, STAG3–cohesin attenuates topologically associating domains (TADs), rewires enhancer–promoter and Polycomb-mediated repressive interactions, and facilitates finer and more strengthened compartments, establishing a distinctive spermatogonial nucleome. Moreover, in the absence of STAG3–cohesin, SSCs show an impaired differentiation priming for spermatogenesis. Mitotic STAG3–cohesin is also expressed in human B cells and their malignant variations, promoting their propagation. Our findings on mitotic STAG3–cohesin elucidate a principle of male germline nucleome programming, demonstrate an unexpected mitotic role for STAG3 and might potentially improve understanding of human malignancies.
Project description:Germ cells are unique in that they tailor chromatin toward generating totipotency. Accordingly, mammalian spermatogonia, including spermatogonial stem cells (SSCs) which constitute the source for male gametes, acquire distinctive chromatin organization with weak insulation, but the underlying mechanism remains unknown. Here, we show that STAG3, this far known to exclusively form meiotic cohesins, generates a mitotic cohesin for male germline nucleome programming in mice. Due to its shorter chromatin residence, STAG3–cohesin attenuates topologically associating domains (TADs), rewires enhancer–promoter and Polycomb-mediated repressive interactions, and facilitates finer and more strengthened compartments, establishing a distinctive spermatogonial nucleome. Moreover, in the absence of STAG3–cohesin, SSCs show an impaired differentiation priming for spermatogenesis. Mitotic STAG3–cohesin is also expressed in human B cells and their malignant variations, promoting their propagation. Our findings on mitotic STAG3–cohesin elucidate a principle of male germline nucleome programming, demonstrate an unexpected mitotic role for STAG3 and might potentially improve understanding of human malignancies.
Project description:Cohesin is a tetrameric protein complex with a ring-like structure that entraps DNA to ensure sister chromatid cohesion and higher-order chromatin organization. The mechanism by which cohesin regulates chromatin structure and gene expression remains a fundamental question. In multicellular organisms, germ cells are unique in that they tailor chromatin organization toward generating totipotency. As part of this program, spermatogonial stem cells (SSCs) in mammals, the source for male gametes, acquire distinctive chromatin organization with exceptionally weak insulation, but the underlying mechanism is unknown. Here, we show that STAG3, exclusively known to form meiotic cohesins, contributes to a mitotic cohesin defining nucleome programming during male germline development. With slower loop extrusion and shorter chromatin residence, STAG3–cohesin attenuates topologically associating domains (TADs) demarcated by CCCTC-binding factor (CTCF), re-wires both enhancer–promoter and Polycomb-mediated repressive interactions, and creates finer and strengthened compartments, establishing a characteristic SSC nucleome. Moreover, STAG3–cohesin controls the balance between SSC self-renewal and differentiation for spermatogenesis. Notably, mitotic STAG3–cohesin is also highly expressed in human B cells and potentially involved in B-cell malignancies. Thus, mitotic STAG3–cohesin with its unique loop extrusion property elucidates a principle for male germline nucleome programming and, more broadly, may contribute to human malignancy.