Specific regulation of CYP27B1 and VDR in proximal versus distal renal cells.
In this study, we utilized murine renal proximal (MPCT-G) and distal (DKC-8) tubular epithelial cell lines to compare the gene expressions and promoter activities of 1,25(OH)(2)D(3) receptor (VDR) and 25-hydroxyvitamin D-1alpha-hydroxylase (CYP27B1) in response to 50 nM of parathyroid hormone (PTH) and changes in extracellular calcium (Ca(2+)) concentration. In MPCT-G cells, VDR gene expression was suppressed by PTH, whereas CYP27B1 gene expression was elevated in response to PTH. In DKC-8 cells, treatment of PTH significantly increased the relative gene expression of VDR by 6.5-fold while CYP27B1 gene expression was unchanged. High Ca(2+) exposure stimulated VDR gene expression and repressed CYP27B1 gene expression in both dose and time-dependent fashion in MPCT-G but not DKC-8 cells. The analysis of promoter activities and VDR protein levels corresponded with the gene expression data. We conclude that PTH-mediated decrease in VDR and increase in renal CYP27B1 is proximal cell-specific.
Bajwa
Amandeep
A
Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA 23298-0614, USA.
Forster
Megan N
MN
Maiti
Aparna
A
Woolbright
Benjamin L
BL
Beckman
Matthew J
MJ
D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D007150:Immunohistochemistry; D007686:Kidney Tubules, Distal / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D051379:Mice; D011401:Promoter Regions, Genetic; D044168:Receptor, Parathyroid Hormone, Type 1 / Q000378:metabolism; D018167:Receptors, Calcitriol / Q000378:metabolism*; D044169:Receptors, Calcium-Sensing / Q000378:metabolism; D013250:Steroid Hydroxylases / Q000378:metabolism; D065668:Vitamin D3 24-Hydroxylase
D044168:Receptor, Parathyroid Hormone, Type 1; D018167:Receptors, Calcitriol; D044169:Receptors, Calcium-Sensing; D013250:Steroid Hydroxylases; D065668:Vitamin D3 24-Hydroxylase; D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase