Effects of vitamin D metabolites on collagen production and cell proliferation of growth zone and resting zone cartilage cells in vitro

Abstract

Previous studies have suggested that vitamin D metabolites directly influence the differentiation and maturation of chondrocytes in calcifying cartilage. Recently, this laboratory has shown that the response of chondrocyte plasma membrane and matrix vesicle enzymes to 1,25-(OH)2D3 and 24,25-(OH)2D3 is both cell and membrane specific. The current study demonstrates that cell replication and matrix protein synthesis are also modulated by vitamin D. Confluent, third-passage growth zone (GC) and resting zone (RC) costochondral chondrocytes were incubated in medium containing 10(-13)-10(-7) M 1,25-(OH)2D3 or 10(-12)-10(-6) M 24,25-(OH)2D3. The amount of collagenase-digestible protein (CDP) secreted into the media was inversely proportional to the concentration of fetal bovine serum (FBS). At 10% FBS, greater than 80% of the CDP was incorporated into the matrix. 1,25-(OH)2D3 stimulated CDP and percentage collagen synthesis by GC cells but had no effect on the synthesis of noncollagenous protein (NCP). 1,25-(OH)2D3 inhibited CDP and percentage collagen synthesis by RC cells but did not alter NCP synthesis. [3H]thymidine incorporation was inhibited in both cell types, whether confluent or subconfluent cultures were examined. At 10(-6) and 10(-7) M 24,25-(OH)2D3, there was a significant decrease in CDP production and percentage collagen synthesis by RC cells but no effect on NCP. However, at 10(-9) and 10(-10) M hormone there was an increase in NCP production but no effect on CDP, resulting in a decrease in percentage collagen synthesis. CDP and NCP production were unaffected by 24,25-(OH)2D3 in GC cells. High concentrations of hormone inhibited [3H]thymidine incorporation in both cell types.(ABSTRACT TRUNCATED AT 250 WORDS)

Protein-disulfide Isomerase-associated 3 (Pdia3) Mediates the Membrane Response to 1,25-Dihydroxyvitamin D3 in Osteoblasts

“…These results support the hypothesis that Pdia3 acts in a dose-dependent manner and its actions vary with cell differentiation. The 1␣,25(OH) 2 D 3 content of the osteogenic media was determined by the content of the secosteroid in FBS, ϳ10 Ϫ12 M (48). When differentiated osteoblasts were pulsed with exogenous 1␣,25-(OH) 2 D 3 , thereby increasing the concentration, the effect of the secosteroid was to reduce phosphate content, but without impacting Ca 2ϩ .…”

1α,25(OH)2D3 is an autocrine regulator of extracellular matrix turnover and growth factor release via ERp60 activated matrix vesicle metalloproteinases

“…24R,25(OH) 2 D 3 regulates matrix synthesis in the resting zone, including MV composition and production, whereas 1α,25 (OH) 2 D 3 regulates matrix synthesis and MV composition in growth zone cells [5][6][7][8]. These effects on matrix vesicle content are genomic.…”

Rapid membrane responses to dihydrotestosterone are sex dependent in growth plate chondrocytes

“…Cells were incubated in DMEM containing 10% fetal bovine serum (FBS) and 50 g/ml vitamin C in atmosphere of 5% CO 2 and 100% humidity at 37 • C. The culture media were replaced after 24 h and then at 72 h until cells reached confluence. Fourth passage cells were used for all experiments based on previous studies showing that these cells preserve their chondrogenic phenotype as well as their differential responsiveness to vitamin D metabolites at this passage [51].…”

“…Cultures were incubated for 9 min with the control medium or 10 −7 M DHT in the presence or absence of 0.1, 1 or 10 M U73122, and PKC specific activity was determined [49,51].…”