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- Title
Parathyroid hormone prevents 1,25(OH)<sub>2</sub>D<sub>3</sub> induced down-regulation of the vitamin D receptor in growth plate chondrocytes <em>in vitro</em>.
- Authors
Klaus, Günter; May, Tanja; Hügel, Ulrike; von Eichel, Barbara; Rodriguez, Julian; Fernandez, Porfirio; Reichrath, Jörg; Ritz, Eberhard; Mehls, Otto
- Abstract
Parathyroid hormone prevents 1,25(OH)2D3 induced down-regulation of the vitamin D receptor in growth plait chondrocytes <em>in vitro</em>. 1,25(OH)2 D3 effect has an antiproliferative effect on growth plate chondrocytes when given in high doses, whereas low doses stimulate chondrocyte proliferation. In the present in <em>in vitro</em>, study we investigated the effects of parathyroid hormone (PTH) when given concomitantly with 125(OH)2D3 on cell proliferation and vitamin D receptor (VDR) regulation. Freshly isolated rat that chondrocytes were grown in monolayer cultures or in agarose stabilized suspension cultures (10% charcoal-treated FCS). VDR expression sins determined by RT-PCR generating a 297 bp fragment and by binding assays (Scatehard analysis) with [³H]-1.25(OH)23 . Cell proliferation was measured by [³H]-thymidine incorporation. growth curves in monolayer cultures and by colony formation in agarose-stabilized suspension cultures. Optimal concentration of 1,25(OH)2D3 (10-12 M) and of PTH fragments [bPTH( I-34) or hPTH(28-48), 10-10 M]. Showed additive effects on DNA synthesis of and colony formation by growth plate chondrocytes This may he explained in pan by an up-regulation of VDR by PTH;. PTH increased both mRNA expression of VDR and binding capacity. 1.25(OH)2D3 (10-12) induced an up-regulation after the for within 24 hours followed by a down-regulation after incubation for more than 24 hours. PTH fragments added concomitantly presented the down- regulation seen with 1.25(OH)23.These findings provide evidence that PTH is a growth promoting hormone that also modulates the effects of 1.25(OH)2D3 by regulating the VDR status of 1.25(OH)2D3 target cells.
- Subjects
PARATHYROID hormone; VITAMIN D; CARTILAGE cells; GROWTH plate; CELL proliferation; CALCIUM regulating hormones
- Publication
Kidney International, 1997, Vol 52, Issue 1, p45
- ISSN
0085-2538
- Publication type
Article
- DOI
10.1038/ki.1997.302