Warning: Undefined variable $zfal in C:\Inetpub\vhosts\kidney.de\httpdocs\mlpefetch.php on line 525
Deprecated: str_replace(): Passing null to parameter #3 ($subject) of type array|string is deprecated in C:\Inetpub\vhosts\kidney.de\httpdocs\mlpefetch.php on line 525
Warning: Undefined variable $sterm in C:\Inetpub\vhosts\kidney.de\httpdocs\mlpefetch.php on line 530
Warning: Undefined variable $sterm in C:\Inetpub\vhosts\kidney.de\httpdocs\mlpefetch.php on line 531
Warning: file_get_contents(http://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&id=18290715&cmd=llinks): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
in C:\Inetpub\vhosts\kidney.de\httpdocs\mlpefetch.php on line 445
 
English Wikipedia
Nephropedia Template TP (
Twit Text
DeepDyve
Pubget Overpricing |  
lüll
Vitamin D receptor: key roles in bone mineral pathophysiology, molecular mechanism of action, and novel nutritional ligands Jurutka PW; Bartik L; Whitfield GK; Mathern DR; Barthel TK; Gurevich M; Hsieh JC; Kaczmarska M; Haussler CA; Haussler MRJ Bone Miner Res 2007[Dec]; 22 Suppl 2 (ä): V2-10The vitamin D hormone, 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)], binds with high affinity to the nuclear vitamin D receptor (VDR), which recruits its retinoid X receptor (RXR) heterodimeric partner to recognize vitamin D responsive elements (VDREs) in target genes. 1,25(OH)(2)D(3) is known primarily as a regulator of calcium, but it also controls phosphate (re)absorption at the intestine and kidney. Fibroblast growth factor 23 (FGF23) is a phosphaturic hormone produced in osteoblasts that, like PTH, lowers serum phosphate by inhibiting renal reabsorption through Npt2a/Npt2c. Real-time PCR and reporter gene transfection assays were used to probe VDR-mediated transcriptional control by 1,25(OH)(2)D(3). Reporter gene and mammalian two-hybrid transfections, plus competitive receptor binding assays, were used to discover novel VDR ligands. 1,25(OH)(2)D(3) induces FGF23 78-fold in osteoblasts, and because FGF23 in turn represses 1,25(OH)(2)D(3) synthesis, a reciprocal relationship is established, with FGF23 indirectly curtailing 1,25(OH)(2)D(3)-mediated intestinal absorption and counterbalancing renal reabsorption of phosphate, thereby reversing hyperphosphatemia and preventing ectopic calcification. Therefore, a 1,25(OH)(2)D(3)-FGF23 axis regulating phosphate is comparable in importance to the 1,25(OH)(2)D(3)-PTH axis that regulates calcium. 1,25(OH)(2)D(3) also elicits regulation of LRP5, Runx2, PHEX, TRPV6, and Npt2c, all anabolic toward bone, and RANKL, which is catabolic. Regulation of mouse RANKL by 1,25(OH)(2)D(3) supports a cloverleaf model, whereby VDR-RXR heterodimers bound to multiple VDREs are juxtapositioned through chromatin looping to form a supercomplex, potentially allowing simultaneous interactions with multiple co-modulators and chromatin remodeling enzymes. VDR also selectively binds certain omega3/omega6 polyunsaturated fatty acids (PUFAs) with low affinity, leading to transcriptionally active VDR-RXR complexes. Moreover, the turmeric-derived polyphenol, curcumin, activates transcription of a VDRE reporter construct in human colon cancer cells. Activation of VDR by PUFAs and curcumin may elicit unique, 1,25(OH)(2)D(3)-independent signaling pathways to orchestrate the bioeffects of these lipids in intestine, bone, skin/hair follicle, and other VDR-containing tissues.|*Calcification, Physiologic/drug effects[MESH]|*Food[MESH]|Animals[MESH]|COS Cells[MESH]|Calcium/metabolism[MESH]|Cell Line[MESH]|Chlorocebus aethiops[MESH]|Fibroblast Growth Factor-23[MESH]|Gene Expression Regulation/drug effects[MESH]|Homeostasis/drug effects[MESH]|Humans[MESH]|Ligands[MESH]|Models, Genetic[MESH]|Phosphates/metabolism[MESH]|Receptors, Calcitriol/*metabolism[MESH]|Vitamin D/analogs & derivatives/pharmacology[MESH] |
