Phosphorylation of GSK-3beta by cGMP-dependent protein kinase II promotes hypertrophic differentiation of murine chondrocytes

J Clin Invest. 2008 Jul;118(7):2506-15. doi: 10.1172/JCI35243.

Abstract

cGMP-dependent protein kinase II (cGKII; encoded by PRKG2) is a serine/threonine kinase that is critical for skeletal growth in mammals; in mice, cGKII deficiency results in dwarfism. Using radiographic analysis, we determined that this growth defect was a consequence of an elongated growth plate and impaired chondrocyte hypertrophy. To investigate the mechanism of cGKII-mediated chondrocyte hypertrophy, we performed a kinase substrate array and identified glycogen synthase kinase-3beta (GSK-3beta; encoded by Gsk3b) as a principal phosphorylation target of cGKII. In cultured mouse chondrocytes, phosphorylation-mediated inhibition of GSK-3beta was associated with enhanced hypertrophic differentiation. Furthermore, cGKII induction of chondrocyte hypertrophy was suppressed by cotransfection with a phosphorylation-deficient mutant of GSK-3beta. Analyses of mice with compound deficiencies in both protein kinases (Prkg2(-/-)Gsk3b(+/-)) demonstrated that the growth retardation and elongated growth plate associated with cGKII deficiency were partially rescued by haploinsufficiency of Gsk3b. We found that beta-catenin levels decreased in Prkg2(-/-) mice, while overexpression of cGKII increased the accumulation and transactivation function of beta-catenin in mouse chondroprogenitor ATDC5 cells. This effect was blocked by coexpression of phosphorylation-deficient GSK-3beta. These data indicate that hypertrophic differentiation of growth plate chondrocytes during skeletal growth is promoted by phosphorylation and inactivation of GSK-3beta by cGKII.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkaline Phosphatase / genetics
  • Animals
  • Axin Protein
  • Cell Differentiation*
  • Cell Line
  • Cells, Cultured
  • Chondrocytes / cytology*
  • Chondrocytes / metabolism
  • Collagen Type X / genetics
  • Collagen Type X / metabolism
  • Cyclic GMP-Dependent Protein Kinase Type II
  • Cyclic GMP-Dependent Protein Kinases / genetics
  • Cyclic GMP-Dependent Protein Kinases / metabolism*
  • Gene Expression / drug effects
  • Glycogen Synthase Kinase 3 / deficiency
  • Glycogen Synthase Kinase 3 / genetics
  • Glycogen Synthase Kinase 3 / metabolism*
  • Glycogen Synthase Kinase 3 beta
  • Growth Plate / abnormalities
  • Growth Plate / metabolism
  • HeLa Cells
  • High Mobility Group Proteins / genetics
  • High Mobility Group Proteins / metabolism
  • Humans
  • Lithium Chloride / pharmacology
  • Matrix Metalloproteinase 13 / genetics
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mice, Transgenic
  • Models, Biological
  • Phosphorylation
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism
  • SOX9 Transcription Factor
  • Signal Transduction / drug effects
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • beta Catenin / metabolism

Substances

  • Axin Protein
  • Collagen Type X
  • High Mobility Group Proteins
  • Repressor Proteins
  • SOX9 Transcription Factor
  • SOX9 protein, human
  • Sox9 protein, mouse
  • Transcription Factors
  • beta Catenin
  • GSK3B protein, human
  • Glycogen Synthase Kinase 3 beta
  • Gsk3b protein, mouse
  • Cyclic GMP-Dependent Protein Kinase Type II
  • Cyclic GMP-Dependent Protein Kinases
  • PRKG2 protein, human
  • Prkg2 protein, mouse
  • Glycogen Synthase Kinase 3
  • Alkaline Phosphatase
  • Matrix Metalloproteinase 13
  • Lithium Chloride