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Reduced chondrocyte proliferation and chondrodysplasia in mice lacking the integrin-linked kinase in chondrocytes.

Terpstra L, Prud'homme J, Arabian A, Takeda S, Karsenty G, Dedhar S, St-Arnaud R - J. Cell Biol. (2003)

Bottom Line: This interaction is mediated by integrins and their cytoplasmic effectors, such as the integrin-linked kinase (ILK).In contrast, chondrocyte proliferation, assessed by BrdU or proliferating cell nuclear antigen labeling, was markedly reduced in the mutant growth plates.ILK inactivation in chondrocytes resulted in reduced cyclin D1 expression, and this most likely explains the defect in chondrocyte proliferation observed when ILK is inactivated in growth plate cells.

View Article: PubMed Central - PubMed

Affiliation: Genetics Unit, Shriners Hospital for Children, 1529 Cedar Avenue, Montréal, Québec, Canada H3G 1A6.

ABSTRACT
Chondrocyte proliferation and differentiation requires their attachment to the collagen type II-rich matrix of developing bone. This interaction is mediated by integrins and their cytoplasmic effectors, such as the integrin-linked kinase (ILK). To elucidate the molecular mechanisms whereby integrins control these processes, we have specifically inactivated the ILK gene in growth plate chondrocytes using the Cre-lox methodology. Mice carrying an ILK allele flanked by loxP sites (ILK-fl) were crossed to transgenic mice expressing the Cre recombinase under the control of the collagen type II promoter. Inactivation of both copies of the ILK-fl allele lead to a chondrodysplasia characterized by a disorganized growth plate and to dwarfism. Expression of chondrocyte differentiation markers such as collagen type II, collagen type X, Indian hedgehog and the PTH-PTHrP receptor was normal in ILK-deficient growth plates. In contrast, chondrocyte proliferation, assessed by BrdU or proliferating cell nuclear antigen labeling, was markedly reduced in the mutant growth plates. Cell-based assays showed that integrin-mediated adhesion of primary cultures of chondrocytes from mutant animals to collagen type II was impaired. ILK inactivation in chondrocytes resulted in reduced cyclin D1 expression, and this most likely explains the defect in chondrocyte proliferation observed when ILK is inactivated in growth plate cells.

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Reduced adhesion of ILK-deficient chondrocytes. Chondrocytes were harvested from the ribs of newborn mice and cultured for 2 d before labeling with 35S-methionine and performing the adhesion assay. Adhesion is quantified by counting the radioactivity of labeled, adherent cells (in cpm). Background adhesion was measured using BSA-coated plates. The chondrocytes from mutant mice (fl/fl, Cre; black bars), which do not express ILK, are impaired in their capacity to bind a collagen type II matrix.
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fig7: Reduced adhesion of ILK-deficient chondrocytes. Chondrocytes were harvested from the ribs of newborn mice and cultured for 2 d before labeling with 35S-methionine and performing the adhesion assay. Adhesion is quantified by counting the radioactivity of labeled, adherent cells (in cpm). Background adhesion was measured using BSA-coated plates. The chondrocytes from mutant mice (fl/fl, Cre; black bars), which do not express ILK, are impaired in their capacity to bind a collagen type II matrix.

Mentions: Primary cultures of costochondral chondrocytes were derived to further characterize the effects of the inactivation of ILK in these cells. Initially, adhesion to extracellular matrix components was measured. Chondrocytes of all genotypes adhered poorly to the BSA-coated negative control plates (Fig. 7)Figure 7.


Reduced chondrocyte proliferation and chondrodysplasia in mice lacking the integrin-linked kinase in chondrocytes.

Terpstra L, Prud'homme J, Arabian A, Takeda S, Karsenty G, Dedhar S, St-Arnaud R - J. Cell Biol. (2003)

Reduced adhesion of ILK-deficient chondrocytes. Chondrocytes were harvested from the ribs of newborn mice and cultured for 2 d before labeling with 35S-methionine and performing the adhesion assay. Adhesion is quantified by counting the radioactivity of labeled, adherent cells (in cpm). Background adhesion was measured using BSA-coated plates. The chondrocytes from mutant mice (fl/fl, Cre; black bars), which do not express ILK, are impaired in their capacity to bind a collagen type II matrix.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172728&req=5

fig7: Reduced adhesion of ILK-deficient chondrocytes. Chondrocytes were harvested from the ribs of newborn mice and cultured for 2 d before labeling with 35S-methionine and performing the adhesion assay. Adhesion is quantified by counting the radioactivity of labeled, adherent cells (in cpm). Background adhesion was measured using BSA-coated plates. The chondrocytes from mutant mice (fl/fl, Cre; black bars), which do not express ILK, are impaired in their capacity to bind a collagen type II matrix.
Mentions: Primary cultures of costochondral chondrocytes were derived to further characterize the effects of the inactivation of ILK in these cells. Initially, adhesion to extracellular matrix components was measured. Chondrocytes of all genotypes adhered poorly to the BSA-coated negative control plates (Fig. 7)Figure 7.

Bottom Line: This interaction is mediated by integrins and their cytoplasmic effectors, such as the integrin-linked kinase (ILK).In contrast, chondrocyte proliferation, assessed by BrdU or proliferating cell nuclear antigen labeling, was markedly reduced in the mutant growth plates.ILK inactivation in chondrocytes resulted in reduced cyclin D1 expression, and this most likely explains the defect in chondrocyte proliferation observed when ILK is inactivated in growth plate cells.

View Article: PubMed Central - PubMed

Affiliation: Genetics Unit, Shriners Hospital for Children, 1529 Cedar Avenue, Montréal, Québec, Canada H3G 1A6.

ABSTRACT
Chondrocyte proliferation and differentiation requires their attachment to the collagen type II-rich matrix of developing bone. This interaction is mediated by integrins and their cytoplasmic effectors, such as the integrin-linked kinase (ILK). To elucidate the molecular mechanisms whereby integrins control these processes, we have specifically inactivated the ILK gene in growth plate chondrocytes using the Cre-lox methodology. Mice carrying an ILK allele flanked by loxP sites (ILK-fl) were crossed to transgenic mice expressing the Cre recombinase under the control of the collagen type II promoter. Inactivation of both copies of the ILK-fl allele lead to a chondrodysplasia characterized by a disorganized growth plate and to dwarfism. Expression of chondrocyte differentiation markers such as collagen type II, collagen type X, Indian hedgehog and the PTH-PTHrP receptor was normal in ILK-deficient growth plates. In contrast, chondrocyte proliferation, assessed by BrdU or proliferating cell nuclear antigen labeling, was markedly reduced in the mutant growth plates. Cell-based assays showed that integrin-mediated adhesion of primary cultures of chondrocytes from mutant animals to collagen type II was impaired. ILK inactivation in chondrocytes resulted in reduced cyclin D1 expression, and this most likely explains the defect in chondrocyte proliferation observed when ILK is inactivated in growth plate cells.

Show MeSH
Related in: MedlinePlus