1,25-DIHYDROXYVITAMIN D-3 EFFECTS IN RAT-KIDNEY - REGULATION OF PROTEIN-PHOSPHORYLATION

This study tested the hypothesis that 1,25-dihydroxyvitamin D-3 treatm ent alters the pattern of protein phosphorylation in rat kidney. Treat ment with 1,25-dihydroxyvitamin D-3 (100 ng/day s.c. x 7d) in vitamin D-deficient rats markedly decreased phosphorylation of a particulate p rotein (91+/-0.6 kDa, n=9) and moderately increased phosphorylation of a cytosolic protein (108+/-0.8 kDa, n=9) in the kidney. The decreased phosphorylation of the 91-kDa particulate protein showed a graded dos e response (0-200 ng/day), as did the more moderate increase in phosph orylation of the 108-kDa cytosolic protein, In conclusion, this study has provided evidence that 1,25-dihydroxyvitamin D-3 plays an importan t role in the regulation of protein phosphorylation in rat kidney and adds these biochemical events to the growing list of 1,25-dihydroxyvit amin D-3 effects in this poorly understood target tissue. (C) 1994 Aca demic Press, Inc.