TPA decreases 1,25(OH) 2D 3 binding and calbindin D-28K in renal (MDBK) cells

• Published in: Molecular and cellular endocrinology Vol. 83; no. 2; pp. 143 - 151
• Main Authors: Simboli-Campbell, Maura, Gagnon, AnneMarie, Franks, Douglas J., Welsh, JoEllen
• Format: Journal Article
• Language: English
• Published: Elsevier Ireland Ltd 1992
• Subjects: 12- O-Tetradecanoylphorbol 13-acetate; Calbindin D28-K; Kidney, bovine; MDBK cell; Protein kinase C; Vitamin D receptor; Protein kinase C; Vitamin D receptor; Calbindin D28-K; Kidney, bovine; 12- O-Tetradecanoylphorbol 13-acetate; MDBK cell
• ISSN: 0303-7207; 1872-8057
• DOI: 10.1016/0303-7207(92)90155-Y

The effect of the phorbol ester TPA (12- O-tetradecanoylphorbol 13-acetate) on vitamin D receptors (VDRs) was studied in MDBK cells, a normal bovine renal epithelial cell line. 24 h treatment of MDBK cells with TPA resulted in down-regulation of VDR number, with no change in the binding affinity for 1,25-dihydroxyvitamin D 3 (1,25(OH) 2D 3) or approximate molecular weight determined by fast protein liquid chromatography (FPLC). TPA treatment also reduced the level of calbindin D-28K, a vitamin D-dependent renal protein. 4α-Phorbol 12,13-didecanoate (4α-PDD), an inactive phorbol ester, did not affect either 1,25(OH) 2D 3 binding or calbindin D-28K levels. TPA elicited a significant decrease in membrane-associated protein kinase C (PKC) activity which coincided with the reduction in VDR number and calbindin D-28K. These data support a link between TPA, PKC activity and vitamin D actions in kidney.