School Of Basic And Applied Sciences

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Author: search.filters.author.Giacobini, P.

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    A microRNA switch regulates the rise in hypothalamic GnRH production before puberty
    (Nature Publishing Group, 2016) Messina, Andrea; Langlet, Fanny; Chachlaki, Konstantina; Roa, Juan; Rasika, Sowmyalakshmi; Jouy, Nathalie; Gallet, Sarah; Gaytan, Francisco; Parkash, Jyoti; Tena-Sempere, Manuel; Giacobini, Paolo; Prevot, Vincent; Messina, A.; Langlet, F.; Chachlaki, K.; Roa, J.; Rasika, S.; Jouy, N.; Gallet, S.; Gaytan, F.; Parkash, J.; Tena-Sempere, M.; Giacobini, P.; Prevot, V.
    A sparse population of a few hundred primarily hypothalamic neurons forms the hub of a complex neuroglial network that controls reproduction in mammals by secreting the 'master molecule' gonadotropin-releasing hormone (GnRH). Timely postnatal changes in GnRH expression are essential for puberty and adult fertility. Here we report that a multilayered microRNA-operated switch with built-in feedback governs increased GnRH expression during the infantile-to-juvenile transition and that impairing microRNA synthesis in GnRH neurons leads to hypogonadotropic hypogonadism and infertility in mice. Two essential components of this switch, miR-200 and miR-155, respectively regulate Zeb1, a repressor of Gnrh transcriptional activators and Gnrh itself, and Cebpb, a nitric oxide-mediated repressor of Gnrh that acts both directly and through Zeb1, in GnRH neurons. This alteration in the delicate balance between inductive and repressive signals induces the normal GnRH-fuelled run-up to correct puberty initiation, and interfering with this process disrupts the neuroendocrine control of reproduction. ? 2016 Nature Publishing Group. All rights reserved.
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    Stage-specific functions of Semaphorin7A during adult hippocampal neurogenesis rely on distinct receptors
    (Nature Publishing Group, 2017) Jongbloets, Bart C.; Lemstra, Suzanne; Schellino, Roberta; Broekhoven, Mark H.; Parkash, Jyoti; Hellemons, Anita J.C.G.M.; Mao, Tianyi; Giocobini, Paolo; Praag, Henriette Van; Marchis, Silvia De; Ramakers, Geert M.J.; Pasterkamp, R. Jeroen; Jongbloets, B.C.; Lemstra, S.; Schellino, R.; Broekhoven, M.H.; Parkash, J.; Hellemons, A.J.C.G.M.; Mao, T.; Giacobini, P.; Van Praag, H.; De Marchis, S.; Ramakers, G.M.J.; Pasterkamp, R.J.
    The guidance protein Semaphorin7A (Sema7A) is required for the proper development of the immune and nervous systems. Despite strong expression in the mature brain, the role of Sema7A in the adult remains poorly defined. Here we show that Sema7A utilizes different cell surface receptors to control the proliferation and differentiation of neural progenitors in the adult hippocampal dentate gyrus (DG), one of the select regions of the mature brain where neurogenesis occurs. PlexinC1 is selectively expressed in early neural progenitors in the adult mouse DG and mediates the inhibitory effects of Sema7A on progenitor proliferation. Subsequently, during differentiation of adult-born DG granule cells, Sema7A promotes dendrite growth, complexity and spine development through ?1-subunit-containing integrin receptors. Our data identify Sema7A as a key regulator of adult hippocampal neurogenesis, providing an example of how differential receptor usage spatiotemporally controls and diversifies the effects of guidance cues in the adult brain.