Differential Expression of GADD45β in Normal and Osteoarthritic Cartilage: Potential Role in Homeostasis of Articular Chondrocytes

Authors

Kosei Ijiri, Beth Israel Deaconess Medical Center
Luiz F. Zerbini, Beth Israel Deaconess Medical Center
Haibing Peng, Beth Israel Deaconess Medical Center
Hasan H. Otu, University of Nebraska-LincolnFollow
Kaneyuki Tsuchimochi, Beth Israel Deaconess Medical Center
Miguel Otero, Beth Israel Deaconess Medical Center
Cecilia Dragomir, Weill College of Medicine of Cornell University
Nicole Walsh, Beth Israel Deaconess Medical Center
Benjamin E. Bierbaum, New England Baptist Hospital
David Mattingly, New England Baptist Hospital
Geoff van Flandern, New England Baptist Hospital
Setsuro Komiya, Kagoshima University
Thomas Aigner, University of Leipzig
Towia A. Libermann, Beth Israel Deaconess Medical Center
Mary B. Goldring, Beth Israel Deaconess Medical CenterFollow

Document Type

Article

Date of this Version

2008

Citation

Arthritis Rheum. 2008 July ; 58(7): 2075–2087

Comments

© 2008, American College of Rheumatology

doi:10.1002/art.23504

Abstract

Objective—Our previous study suggested that growth arrest and DNA damage–inducible protein 45β (GADD45β) prolonged the survival of hypertrophic chondrocytes in the developing mouse embryo. This study was undertaken, therefore, to investigate whether GADD45β plays a role in adult articular cartilage.

Methods—Gene expression profiles of cartilage from patients with late-stage osteoarthritis (OA) were compared with those from patients with early OA and normal controls in 2 separate microarray analyses. Histologic features of cartilage were graded using the Mankin scale, and GADD45β was localized by immunohistochemistry. Human chondrocytes were transduced with small interfering RNA (siRNA)–GADD45β or GADD45β-FLAG. GADD45β and COL2A1 messenger RNA (mRNA) levels were analyzed by real-time reverse transcriptase–polymerase chain reaction, and promoter activities were analyzed by transient transfection. Cell death was detected by Hoechst 33342 staining of condensed chromatin.

Results—GADD45β was expressed at higher levels in cartilage from normal donors and patients with early OA than in cartilage from patients with late-stage OA. All chondrocyte nuclei in normal cartilage immunostained for GADD45β. In early OA cartilage, GADD45β was distributed variably in chondrocyte clusters, in middle and deep zone cells, and in osteophytes. In contrast, COL2A1, other collagen genes, and factors associated with skeletal development were up-regulated in late OA, compared with early OA or normal cartilage. In overexpression and knockdown experiments, GADD45β down-regulated COL2A1 mRNA and promoter activity. NF-κB overexpression increased GADD45β promoter activity, and siRNA-GADD45β decreased cell survival per se and enhanced tumor necrosis factor α–induced cell death in human articular chondrocytes.

Conclusion—These observations suggest that GADD45β might play an important role in regulating chondrocyte homeostasis by modulating collagen gene expression and promoting cell survival in normal adult cartilage and in early OA.