Effect of 1,25-Dihydroxyvitamin D3 on Induction of Chondrocyte Maturation in Culture: Extracellular Matrix Gene Expression and Morphology*

Abstract

Chondrocytes, derived from a tissue that remains as permanent hyaline cartilage in vivo (embryonic chicken caudal sterna) were treated with 10(-8) to 10(-8) M 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. These nonadherent rounded chondrocytes acquired an adherent, polygonal morphology in a dose-dependent fashion with 1,25(OH)2D3 treatment. During the first 4 days of 1,25(OH)2D3 treatment cell flattening was associated with a 10-fold increase in beta-actin and fibronectin and their corresponding messenger RNAs (mRNAs). After adherence over the 12 days of continuous hormone treatment, a 2- to 4-fold increase in DNA synthesis and DNA accumulation were observed for the highest hormone dose (10(-8) M). Over the same time course total collagen synthesis decreased 35-50% primarily due to decreased type II collagen synthesis, which accompanied comparable decreases in its mRNA. In contrast, both alpha 1(I) and alpha 2(I) showed a continuous 5- to 10-fold increase; however, type I collagen protein synthesis remained undetectable, indicating translational control of the type I collagen synthesis. alpha 1(X) mRNAs showed a 2- 3-fold increase after 12 days of hormone treatment, and its polypeptide was clearly detected by sodium dodecyl sulfate polyacrylamide gel analysis. Type IX collagen synthesis showed a 2-fold increase in synthesis and its mRNA levels during the first 4 days of 1,25(OH)2D3 treatment but thereafter had levels comparable to control cultures. Analysis of proteoglycan synthesis and core protein mRNA levels showed there was a 2-fold increase in core protein mRNAs while proteoglycan synthesis, as assessed by 35S incorporation, showed only a 10-20% increase. Direct hormone effects vs. those secondary to altered cellular morphology were determined by blocking cell adherence by growth of the 1,25(OH)2D3-treated cultures on bacteriological petri dishes. All of the observed effects on cytoskeletal and collagen mRNAs were blocked except the elevations observed in proteoglycan core protein and alpha 1(IX) mRNAs. DNA contents in hormone-treated cultures also remained elevated. These results suggest that 1,25(OH)2D3 both activates and suppresses specific genes, promoting chondrocyte maturation toward a more hypertrophic phenotype. However, prevention of the initial morphological alterations that are induced by 1,25(OH)2D3 blocks many of the subsequent changes in connective tissue expression.

Concepts of Osteoblast Growth and Differentiation: Basis for Modulation of Bone Cell Development and Tissue Formation

“…This implies a contribution of signals from the extracellular matrix that promotes the developmental sequence of osteoblast differentiation and a higher level of gene expression than in the absence of the extracellular matrix. The dependency on ascorbic acid and collagen matrix formation for expression of differentiation-related genes has also been observed for chondrocyte culture systems (Leboy et al, 1989;Gerstenfeld et al, 1990;Franceschi and Young, 1990).…”

Effects of 1,25-Dihydroxyvitamin D₃ on Tumor Cell Invasion to the Extracellular Matrix in Human Fibrosarcoma HT1080 Cells and Its Correlation with Laminin

“…These findings show the lack of effect of l,25(OH)2D3 on cell attachment to the matrix because it has no effect on the expression of laminin receptor. l,25(OH)2D3-induced changes in the ex pression of extracellular matrix proteins have been reported in several normal tissue cells and tumor cells [19][20][21][22][23], Brackman [23] re ported that l,25(OH)2D3 induced a marked reduction in laminin and fibronectin expres sion using immunocytochemistry on murine fibroblast spheroids. Our own data shown in figure4 demonstrate that l,25(OH)2D3 in duces a reduction of the expression of laminin mRNA in a dose-dependent manner in HT1080 cells.…”

“…The interaction of tumor cells with the extracellu lar matrix has an important role in tumor invasion and metastasis. It has been suggested that extracellular matrix proteins such as lam inin and fibronectin might signal through a protease system, leading to increased matrix synthesis [15,16], We have previously found that type IV collagenolytic and migration ac tivity of tumor cells were accelerated by cell attachment to laminin via the cell surface laminin receptor, suggesting that laminin plays an important role in the matrix degrada tion by tumor cells and cell migration [17,18], Recently, l,25(OH)2D3 has been reported to modulate the expression of extracellular ma trix proteins in several cell lines [19][20][21][22][23]. Brackman [23] reported that the hormone induced a substantial reduction in the expres sion of laminin and fibronectin from murine fibroblasts.…”

Bone changes caused by experimental Solanum malacoxylon poisoning in rabbits

“…It has been demonstrated that 1,25(OH) 2 D 3 promotes chondrocytes differentiation of chondrocytes along the endochondral differentiation cascade (Gerstenfeld et al 1990). Prominent areas of chondrocytes were observed in the periosteum of ribs of Sm-treated rabbits, just beneath its outer layer (*).…”