TY - JOUR
T1 - Bone morphogenetic protein-2 (BMP-2) activates NFATc1 transcription factor via an autoregulatory loop involving Smad/Akt/Ca2+ signaling
AU - Mandal, Chandi C.
AU - Das, Falguni
AU - Ganapathy, Suthakar
AU - Harris, Stephen E.
AU - Choudhury, Goutam Ghosh
AU - Ghosh-Choudhury, Nandini
N1 - Funding Information:
This work was supported in part by Veterans Affairs Merit Review grants and National Institutes of Health Grant RO1 AR52425 (to N. G.-C.) and National Institutes of Health Grant RO1 DK50190 and Veterans Affairs Merit Review grants (to G. G. C.). The authors do not have any conflict of interests. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
PY - 2016/1/15
Y1 - 2016/1/15
N2 - Bone remodeling is controlled by dual actions of osteoclasts (OCs) and osteoblasts (OBs). The calcium-sensitive nuclear factor of activated T cells (NFAT) c1 transcription factor, as an OC signature gene, regulates differentiation of OCs downstream of bone morphogenetic protein-2 (BMP-2)-stimulated osteoblastcoded factors. To analyze a functional link between BMP-2 and NFATc1, we analyzed bones from OB-specific BMP-2 knockout mice for NFATc1 expression by immunohistochemical staining and found significant reduction in NFATc1 expression. This indicated a requirement of BMP-2 for NFATc1 expression in OBs. We showed that BMP-2, via the receptor-specific Smad pathway, regulates expression of NFATc1 in OBs. Phosphatidylinositol 3-kinase/Akt signaling acting downstream of BMP-2 also drives NFATc1 expression and transcriptional activation. Under the basal condition, NFATc1 is phosphorylated. Activation of NFAT requires dephosphorylation by the calcium-dependent serine/threonine phosphatase calcineurin. We examined the role of calcium in BMP-2-stimulated regulation of NFATc1 in osteoblasts. 1,2Bis(2aminophenoxy)ethaneN,N,N′,N′-tetraacetic acid acetoxymethyl ester, an inhibitor of intracellular calcium abundance, blocked BMP-2-induced transcription of NFATc1. Interestingly, BMP-2 induced calcium release from intracellular stores and increased calcineurin phosphatase activity, resulting in NFATc1 nuclear translocation. Cyclosporin A, which inhibits calcineurin upstream of NFATc1, blocked BMP-2-induced NFATc1 mRNA and protein expression. Expression of NFATc1 directly increased its transcription and VIVIT peptide, an inhibitor of NFATc1, suppressed BMP-2-stimulated NFATc1 transcription, confirming its autoregulation. Together, these data show a role of NFATc1 downstream of BMP-2 in mouse bone development and provide novel evidence for the presence of a cross-talk among Smad, phosphatidylinositol 3-kinase/Akt, and Ca2+ signaling for BMP-2-induced NFATc1 expression through an autoregulatory loop.
AB - Bone remodeling is controlled by dual actions of osteoclasts (OCs) and osteoblasts (OBs). The calcium-sensitive nuclear factor of activated T cells (NFAT) c1 transcription factor, as an OC signature gene, regulates differentiation of OCs downstream of bone morphogenetic protein-2 (BMP-2)-stimulated osteoblastcoded factors. To analyze a functional link between BMP-2 and NFATc1, we analyzed bones from OB-specific BMP-2 knockout mice for NFATc1 expression by immunohistochemical staining and found significant reduction in NFATc1 expression. This indicated a requirement of BMP-2 for NFATc1 expression in OBs. We showed that BMP-2, via the receptor-specific Smad pathway, regulates expression of NFATc1 in OBs. Phosphatidylinositol 3-kinase/Akt signaling acting downstream of BMP-2 also drives NFATc1 expression and transcriptional activation. Under the basal condition, NFATc1 is phosphorylated. Activation of NFAT requires dephosphorylation by the calcium-dependent serine/threonine phosphatase calcineurin. We examined the role of calcium in BMP-2-stimulated regulation of NFATc1 in osteoblasts. 1,2Bis(2aminophenoxy)ethaneN,N,N′,N′-tetraacetic acid acetoxymethyl ester, an inhibitor of intracellular calcium abundance, blocked BMP-2-induced transcription of NFATc1. Interestingly, BMP-2 induced calcium release from intracellular stores and increased calcineurin phosphatase activity, resulting in NFATc1 nuclear translocation. Cyclosporin A, which inhibits calcineurin upstream of NFATc1, blocked BMP-2-induced NFATc1 mRNA and protein expression. Expression of NFATc1 directly increased its transcription and VIVIT peptide, an inhibitor of NFATc1, suppressed BMP-2-stimulated NFATc1 transcription, confirming its autoregulation. Together, these data show a role of NFATc1 downstream of BMP-2 in mouse bone development and provide novel evidence for the presence of a cross-talk among Smad, phosphatidylinositol 3-kinase/Akt, and Ca2+ signaling for BMP-2-induced NFATc1 expression through an autoregulatory loop.
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U2 - 10.1074/jbc.M115.668939
DO - 10.1074/jbc.M115.668939
M3 - Article
C2 - 26472929
AN - SCOPUS:84954562433
SN - 0021-9258
VL - 291
SP - 1148
EP - 1161
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 3
ER -