A novel role for GADD45beta as a mediator of MMP-13 gene expression during chondrocyte terminal differentiation

Kosei Ijiri, Harvard Medical School
Luiz F. Zerbini, Harvard Medical School
Haibing Peng, Harvard Medical School
Ricardo G. Correa, The Salk Institute for Biological Studies
Binfeng Lu, University of Pittsburgh School of Medicine
Nicole Walsh, Harvard Medical School
Yani Zhao, University of Pittsburgh School of Medicine
Noboru Taniguchi, Graduate School of Medicine and Dentistry
Xu-Ling Huang, Harvard Medical School
Hasan Otu, Harvard Medical School
Hong Wang, Harvard Medical School
Jian Fei. Wang, Harvard Medical School
Setsuro Komiya, Graduate School of Medicine and Dentistry
Patricia Ducy, Baylor College of Medicine
Mahboob U. Rahman, Harvard Medical School
Richard A. Flavell, Yale University School of Medicine
Ellen M. Gravallese, University of Massachusetts Medical School
Peter Oettgen, Harvard Medical School
Towia A. Libermann, Harvard Medical School
Mary B. Goldring, Harvard Medical School

At the time of publication, Ellen Gravallese was not yet affiliated with the University of Massachusetts Medical School

Abstract

The growth arrest and DNA damage-inducible 45beta (GADD45beta) gene product has been implicated in the stress response, cell cycle arrest, and apoptosis. Here we demonstrated the unexpected expression of GADD45beta in the embryonic growth plate and uncovered its novel role as an essential mediator of matrix metalloproteinase-13 (MMP-13) expression during terminal chondrocyte differentiation. We identified GADD45beta as a prominent early response gene induced by bone morphogenetic protein-2 (BMP-2) through a Smad1/Runx2-dependent pathway. Because this pathway is involved in skeletal development, we examined mouse embryonic growth plates, and we observed expression of Gadd45beta mRNA coincident with Runx2 protein in pre-hypertrophic chondrocytes, whereas GADD45beta protein was localized prominently in the nucleus in late stage hypertrophic chondrocytes where Mmp-13 mRNA was expressed. In Gadd45beta(-/-) mouse embryos, defective mineralization and decreased bone growth accompanied deficient Mmp-13 and Col10a1 gene expression in the hypertrophic zone. Transduction of small interfering RNA-GADD45beta in epiphyseal chondrocytes in vitro blocked terminal differentiation and the associated expression of Mmp-13 and Col10a1 mRNA in vitro. Finally, GADD45beta stimulated MMP-13 promoter activity in chondrocytes through the JNK-mediated phosphorylation of JunD, partnered with Fra2, in synergy with Runx2. These observations indicated that GADD45beta plays an essential role during chondrocyte terminal differentiation.