Calcitonin induces 25-hydroxyvitamin D3 1alpha-hydroxylase mRNA expression via protein kinase C pathway in LLC-PK1 cells.
The biosynthesis of 1alpha, 25-dihydroxyvitamin D3 from 25-hydroxyvitamin D3 is catalyzed by 25-hydroxyvitamin D3 1alpha-hydroxylase (CYP27B1) in renal proximal tubules. It was recently demonstrated that LLC-PK1 cells express CYP27B1 mRNA, which is regulated by intracellular cAMP but not vitamin D3. To clarify the effect of calcitonin on vitamin D3 metabolism in vitro, LLC-PK1 cells were incubated with hormonal factors, and expression of CYP27B1 mRNA was measured by quantitative reverse transcription-PCR. Calcitonin at 100 nmol/L significantly increased CYP27B1 mRNA expression by 24 h (271 +/- 21% of control). Incubation with calcitonin over a range of 1 micromol/L to 1 pmol/L resulted in a concentration-dependent increase in CYP27B1 mRNA levels. It is known that the calcitonin receptor has dual intracellular signaling pathways, via protein kinases A and C. Both 500 micromol/L 8-bromo-cAMP, a protein kinase A activator, and 100 nmol/L phorbol 12-myristate 13-acetate, a protein kinase C activator, increased CYP27B1 mRNA levels at 24 h (207 +/- 54 and 246 +/- 58% of control, respectively). However, calcitonin-induced CYP27B1 mRNA expression was only inhibited by the protein kinase C inhibitors staurosporine and calphostin C. The protein kinase A inhibitors Rp-cAMPS at 10 and 100 micromol/L and H-89 at 10 micromol/L had no effect on the action of calcitonin, in spite of cAMP-activation by calcitonin. The present data suggest that calcitonin upregulates CYP27B1 mRNA expression via the protein kinase C pathway in LLC-PK1 cells.
Yoshida
N
N
Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan.
Yoshida
T
T
Nakamura
A
A
Monkawa
T
T
Hayashi
M
M
Saruta
T
T
D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D002116:Calcitonin / Q000008:administration & dosage / Q000494:pharmacology*; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007700:Kinetics; D018374:LLC-PK1 Cells; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D019311:Staurosporine / Q000494:pharmacology; D013552:Swine; D013873:Thionucleotides / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects
D017931:DNA Primers; D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D013873:Thionucleotides; C016957:adenosine-3',5'-cyclic phosphorothioate; D002116:Calcitonin; D000242:Cyclic AMP; D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D019311:Staurosporine