| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1Laboratory of Developmental Nephrology, Faculty of Medicine, Technion-Israel Institute of Technology, and 2 Pediatric Nephrology Unit, Department of Nephrology, Rambam Medical Center, Haifa, Israel
Submitted 20 January 2004 ; accepted in final form 2 September 2004
Tubular reabsorption of Mg2+ is mediated by the tight junction protein paracellin-1, which is encoded by the gene PCLN-1 (CLDN16) and exclusively expressed in the kidney. Tubular Mg2+ reclamation is modulated by many hormones and factors. The aim of this study was to define regulatory elements essential for renal tubular cell-specific expression of human PCLN-1 (hPCLN-1) and to explore the effect of Mg2+ transport modulators on the paracellin-1 gene promoter. Endogenous paracellin-1 mRNA and protein were detected in renal cell lines opossom kidney (OK), HEK293, and MDCT, but not in the fibroblast cell line NIH3T3. A 7.5-kb hPCLN-1 5'-flanking DNA sequence along with seven 5'-deletion products were cloned into luciferase reporter vectors and transiently transfected into the renal and nonrenal cells. The highest levels of luciferase activity resulted from transfection of a 5'-flanking 2.5-kb fragment (pJ2M). This activity was maximal in OK cells, was orientation dependent, and was absent in NIH3T3 cells. Mg2+ deprivation significantly increased pJ2M-driven activity in transfected OK cells, whereas Mg2+ load decreased it compared with conditions of normal Mg2+. Deletion analysis along with electrophoretic mobility-shift assay demonstrated that OK cells contain nuclear proteins, which bind a 70-bp region between –1633 and –1703 of major functional significance. Deleting this 70-bp segment, which contains a single peroxisome proliferator-response element (PPRE), or mutating the PPRE, caused a 60% reduction in luciferase activity. Stimulating the 70-bp sequence with 1,25(OH)2 vitamin D decreased luciferase activity by 52%. This effect of 1,25(OH)2 vitamin D was abolished in the absence of PPRE or in the presence of mutated PPRE. We conclude that the PPRE within this 70-bp DNA region may play a key role in the cell-specific and regulatory activity of the hPCLN-1 promoter. Ambient Mg2+ concentration and 1,25(OH)2 vitamin D may modulate paracellular, paracellin-1-mediated, Mg2+ transport at the transcriptional level. 1,25(OH)2 vitamin D exerts its activity on the hPCLN-1 promoter likely via the PPRE site.
magnesium; renal tubule; transcription; promoter; gene expression; gene regulation; peroxisome proliferator response element; 1,25(OH)2 vitamin D
This article has been cited by other articles:
|
|
 |
|
  L. Adler, E. Efrati, and I. Zelikovic Molecular mechanisms of epithelial cell-specific expression and regulation of the human anion exchanger (pendrin) gene Am J Physiol Cell Physiol, May 1, 2008; 294(5): C1261 - C1276. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. Thongon, L.-i. Nakkrasae, J. Thongbunchoo, N. Krishnamra, and N. Charoenphandhu Prolactin stimulates transepithelial calcium transport and modulates paracellular permselectivity in Caco-2 monolayer: mediation by PKC and ROCK pathways Am J Physiol Cell Physiol, May 1, 2008; 294(5): C1158 - C1168. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. B. N. Lee, E. Huang, and H. J. Ward Tight junction biology and kidney dysfunction Am J Physiol Renal Physiol, January 1, 2006; 290(1): F20 - F34. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
