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1,25‐Dihydroxyvitamin D 3 –Induced Calcium Efflux from Calvaria Is Mediated by Protein Kinase C
Author(s) -
DranitzkiElhalel Michal,
Wald Hanna,
Popovtzer Mordecai M.,
Sprague Stuart M.
Publication year - 1999
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1359/jbmr.1999.14.11.1822
Subject(s) - protein kinase c , calphostin c , calvaria , endocrinology , calphostin , medicine , bone resorption , calcium in biology , calcium , staurosporine , chemistry , intracellular , cytosol , calcium metabolism , biology , kinase , biochemistry , enzyme , in vitro
1,25‐dihydroxyvitamin D 3 (1,25(OH) 2 D 3 ) is an important regulator of bone metabolism involved in both formation and resorption. Traditionally it was assumed that vitamin D receptors are intracellular. Recent data indicate that vitamin D may also act through a membrane receptor, specifically raising intracellular calcium and inositol 1,4,5 triphosphate. The present study was undertaken to explore further the mechanism(s) of vitamin D–induced bone resorption in cultured bone. 1,25(OH) 2 D 3 induced a dose‐dependent increase of calcium efflux from cultured bone. This increase was completely obliterated by inhibition of protein kinase C (PKC) with either staurosporine or calphostin C. In cultured rat calvariae, 1,25(OH) 2 D 3 also induced a dose‐dependent translocation of PKC from cytosol to membrane. The activation of PKC by 1,25(OH) 2 D 3 occurred following a 30‐s incubation, peaked at 1 minute, and disappeared by 5 minutes. 1,25(OH) 2 D 3 did not increase cAMP production in similarly cultured calvaria. These results suggest that the action of 1,25(OH) 2 D 3 on calcium flux from cultured bone is mediated, in part, via activation of PKC.