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J Neurosci. 2005 Mar 9;25(10):2687-701.

Canonical transient receptor potential 1 plays a role in basic fibroblast growth factor (bFGF)/FGF receptor-1-induced Ca2+ entry and embryonic rat neural stem cell proliferation.

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  • 1Laboratory of Neurophysiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA. alessandra.fiorio@unito.it

Abstract

Basic fibroblast growth factor (bFGF) and its major receptor FGF receptor-1 (FGFR-1) play an important role in the development of the cortex. The mechanisms underlying the mitogenic role of bFGF/FGFR-1 signaling have not been elucidated. Intracellular Ca2+ concentrations ([Ca2+]i) in proliferating cortical neuroepithelial cells are markedly dependent on Ca2+ entry (Maric et al., 2000a). The absence of voltage-dependent Ca2+ entry channels, which emerge later, indicates that other membrane mechanisms regulate [Ca2+]i during proliferation. Canonical transient receptor potential (TRPC) family channels are candidates because they are voltage independent and are expressed during CNS development (StrĂ¼bing et al., 2003). Here, we investigated the involvement of TRPC1 in bFGF-mediated Ca2+ entry and proliferation of embryonic rat neural stem cells (NSCs). Both TRPC1 and FGFR-1 are expressed in the embryonic rat telencephalon and coimmunoprecipitate. Quantitative fluorescence-activated cell sorting analyses of phenotyped telencephalic dissociates show that approximately 80% of NSCs are TRPC1+, proliferating, and express FGFR-1. Like NSCs profiled ex vivo, NSC-derived progeny proliferating in vitro coexpress TRPC1 and FGFR1. Antisense knock-down of TRPC1 significantly decreases bFGF-mediated proliferation of NSC progeny, reduces the Ca2+ entry component of the Cai2+ response to bFGF without affecting Ca2+ release from intracellular stores or 1-oleoyl-2-acetyl-sn-glycerol-induced Ca2+ entry, and significantly blocks an inward cation current evoked by bFGF in proliferating NSCs. Both Ca2+ influx evoked by bFGF and NSC proliferation are attenuated by Gd3+ and SKF96365 two antagonists of agonist-stimulated Ca2+ entry. Together, these results show that TRPC1 contributes to bFGF/FGFR-1-induced Ca2+ influx, which is involved in self-renewal of embryonic rat NSCs.

PMID:
15758179
[PubMed - indexed for MEDLINE]
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