The promoter region of the human PMCA1 gene mediates transcriptional downregulation by 1,25-dihydroxyvitamin D(3).
The gene for plasma membrane calcium pump isoform1 (PMCA1) is expressed in calcium-transporting epithelia and bone mesenchymal cells and is upregulated to 1,25-(OH)(2)D(3) in those tissues. A candidate sequence for a vitamin D response element (VDRE) is present within a 1.7-kb promoter region of the human PMCA1 (hPMCA1) gene. We studied hPMCA1 promoter activity in MDBK and ROS 17/2.8 cell lines as PMCA1 mRNA expression is upregulated by 1,25-(OH)(2)D(3) in both. Structural analysis of the putative hPMCA1 VDRE sequence was performed using mobility shift analysis (EMSA) and nuclear extracts from COS-1 cells expressing human VDR (hVDR) and RXRalpha (hRXRalpha). 1,25-(OH)(2)D(3) induced transrepression of the entire 1.7-kb hPMCA1 promoter and of one promoter deletion construct in ROS 17/2.8 cells but not MDBK cells when assayed by luciferase reporter gene assays. Three additional hPMCA1 promoter deletion constructs were unaffected by 1,25-(OH)(2)D(3) in either cell line. While hVDR and hRXRalpha were capable of complexing with a rat osteocalcin DR3 VDRE, EMSA analysis of the potential VDRE from the hPMCA1 gene did not show interaction of either nuclear receptor. Our results indicate tissue-specific sensitivity of the promoter region of the hPMCA1 gene to direct transcriptional downregulation by 1,25-(OH)(2)D(3) and suggest that any positive regulatory VDRE must lie outside of the 1.7-kb core promoter.
Glendenning
P
P
Department of Medicine, University of Western Australia, Western Australia, Australia. pglenden@mail.rah.sa.gov.au
Ratajczak
T
T
Prince
R L
RL
Garamszegi
N
N
Strehler
E E
EE
D000818:Animals; D019556:COS Cells; D002117:Calcitriol / Q000494:pharmacology*; D002120:Calcium Channel Agonists / Q000494:pharmacology*; D000252:Calcium-Transporting ATPases / Q000235:genetics*; D027682:Cation Transport Proteins; D002417:Cattle; D002478:Cells, Cultured; D015536:Down-Regulation; D004586:Electrophoresis; D005786:Gene Expression Regulation; D015675:Osteocalcin / Q000378:metabolism; D053499:Plasma Membrane Calcium-Transporting ATPases; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000235:genetics; D051381:Rats; D014158:Transcription, Genetic / Q000187:drug effects*
C506952:ATP2B1 protein, human; D002120:Calcium Channel Agonists; D027682:Cation Transport Proteins; D015675:Osteocalcin; D053499:Plasma Membrane Calcium-Transporting ATPases; C506955:Atp2b1 protein, rat; D000252:Calcium-Transporting ATPases; D002117:Calcitriol