1,25-Dihydroxyvitamin D3 has opposite effects on the expression of parathyroid secretory protein and parathyroid hormone genes.
Previous studies have shown that 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] decreases levels of mRNA for prepro-PTH as well as PTH secretion after chronic exposure (24-48 h) of parathyroid cells in tissue culture. We have now extended these studies to determine the effects of the vitamin D3 metabolite on parathyroid secretory protein (PSP) gene expression. Primary cultures of bovine parathyroid cells were incubated with 10(-8) M 1,25-(OH)2D3 for periods of time ranging from 24-72 h. As observed in earlier experiments, prepro-PTH mRNA decreased to less than 50% of the control value after 72 h. In marked contrast, PSP mRNA showed a 2.5-fold increase by 24 h and greater than 7-fold stimulation by 72 h. In the same studies, PTH secretion was suppressed (to 60% of control), while PSP secretion was increased by 40% over control values. Exposure to high (2.5 mM) or low (0.5 mM) calcium had no effect on PSP mRNA, even though low calcium stimulated the secretion of PSP while high calcium suppressed secretion. These studies showed that 1,25-(OH)2D3 has opposite effects on the gene expression of PSP and PTH in bovine parathyroid cells in tissue culture.
Russell
J
J
Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461.
Lettieri
D
D
Adler
J
J
Sherwood
L M
LM
D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D053379:Chromogranin A; D002864:Chromogranins; D015870:Gene Expression / Q000187:drug effects* / Q000502:physiology; D010280:Parathyroid Glands / Q000166:cytology / Q000378:metabolism; D010281:Parathyroid Hormone / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D002135:Calcium-Binding Proteins; D053379:Chromogranin A; D002864:Chromogranins; D010281:Parathyroid Hormone; D012333:RNA, Messenger; D002117:Calcitriol; D002118:Calcium