Center of Biomedical Research Excellence (COBRE) for Skeletal Health and Repair

Mechanism of Growth Plate Development Regulated by HDAC4

Principal Investigator: Lei Wei, MD, PhD

Abstract

The goal of this project is to understand the signaling mechanisms that regulate growth plate development by analyzing the role of histone deacetylase 4 (HDAC4). HDAC4 is a negative regulator of growth plate maturation that works by binding to and inhibiting the activity of Runx 2/Cbfa1 in the nucleus. Runx 2/Cbfa1 is a transcription factor necessary for chondrocyte hypertrophy during endochondral bone formation in the growth plate.

The findings of Lei Wei, MD, PhD indicate the HDAC4 nuclear-cytoplasmic shuttling and degradation may control chondrocyte hypertrophy during growth plate development. However, the mechanisms of the HDAC4 nuclear-cytoplasmic shuttling and HDAC4 degradation are as yet undetermined. Uncovering the process will significantly increase our understanding of growth plate development.

Based on these findings, the central hypothesis is that the relocation and degradation of HDAC4 is a central regulatory step that controls chondrocyte differentiation in the growth plate. The central hypothesis has been subdivided into two specific hypotheses. First, HDAC4 nuclear-cytoplasmic shuttling controls chondrocyte differentiation and is dependent on the Ca2+/calmodulin signaling pathway, and second, P38 MAPK controls chondrocyte hypertrophy by increasing caspases degrading HDAC4, which releases Runx2 from its interaction with HDAC4.

They have been tested in the following two aims:
  • Specific Aim 1: To determine whether activation of the Ca2+/calmodulin signaling pathway via constitutively active Ca2+/calmodulin-dependent protein kinase IV (CaMKIV) prevents nuclear entry of HDAC4 and enhances the binding of HDAC4 to the cytoplasmic binding protein 14-3-3 in cytoplasm. This process may regulate chondrocyte differentiation.
  • Specific Aim 2: To determine:
    • If caspases induce the degradation of HDAC4, which in turn increases Runx2 activity.
    • If the process is controlled by p38 MAPK by using constitutively active MKK6 to elevate p38 and dominant negative p38 MAPK to repress p38 in the presence or absence of caspase inhibitors.
    • If Runx2 expression is dependent on p38 MAPK through in situ hybridization in p38 MAPK defective growth plates.
    • If the activities of p38, ERK, and JNK are involved in the process by western blot.
Publications
  1. Katsuaki Kanbe; Lei Wei; Changqi Sun; Qian Chen. Pericellular Matrilins Regulate Activation of Chondrocytes by Cyclic Load-Induced Matrix Deformation. The Journal of Bone and Mineral Research. 2007;22:318-328.
  2. Surena Namdari, MD, Lei Wei, MD, PhD, Douglas Moore, MS, and Qian Chen, PhD. Genetic Inhibition of P38 MAP Kinase Activity in Cartilage Reduces Limb Length and Worsens Osteoarthritis in Adult Mice. Arthritis & Rheumatism 58(11): 3520-3529, 2008.
  3. Wei, L., Sun X., Kanbe K., Terek R. Critical Roles for Chemokine SDF-1 Signaling in Development of Growth Plate Chondrocyte Hypertrophy. Bone Supplement 1, 2008; 43:532.
  4. Yan-lin Li, Rui Han, Xue-ling Zhao, Xiao-guang Xiu, Hong-tao Guo,Yong-nian Wang, Lei Wei. A New Osteonecrosis Animal Model of The Femoral Head Induced by Microwave Heating and Repaired With Tissue Engineered Bone. International Orthopaedics. 33(2):573-80, 2009 Apr.
  5. Ming Pei, Fan He, Ashley Rawson and Lei Wei. Melatonin enhances chondrogenic differentiation of porcine articular chondrocytes. J Pineal Res. 46(2):181-7, 2009.
  6. Xiaojuan Sun, Lei Wei, and Richard M.Terek. HDAC4 Represses Vascular Endothelial Growth Factor Expression in Chondrosarcoma by Modulating RUNX2 Activity. Journal of Biological Chemistry 284(33):21881-90, 2009 Aug 14.
  7. Pei M., Chen D., Li J., Wei L. Histone deacetylase 4 promotes TGF-beta1-induced synovium-derived stem cell chondrogenesis but inhibits chondrogenically differentiated stem cell hypertrophy. Differentiation 2009 Dec;78(5):260-8. PMID: 19716643
  8. Lei Wei, Braden C. Fleming, Xiaojuan Sun, Erin Teeple, Wesley Wu, Gregory D. Jay, Khaled A. Elsaid, Jason T. Machan, Qian Chen. Comparison of Differential Biomarkers of Osteoarthritis with and without Post-traumatic Injury in the Hartley Guinea Pig Model. Journal of Orthopedic Research. 2010 Jul;28(7):900-6. PMID: 20108346.
  9. Lei Wei, Katsuaki Kanbe, Mark Lee, Richard Terek, Qian Chen. Stimulation of Chondrocyte Hypertrophy by Chemokine Stromal Cell-Derived Factor 1 in the Chondro-osseous Junction during endochondral bone formation. Developmental Biology 2010 May 1;341(1):236-45 PMID: 20206617
  10. Xiaojuan Sun, Lei Wei, Qian Chen and Richard M Terek. CXCR4/SDF1 mediate hypoxia induced chondrosarcoma cell invasion through ERK signaling and increased MMP1 expression. Molecular Cancer 2010 Jan 26;9:17. PMID: 20102637.
  11. HE Yi-Xin, Zhang Ge, Pan Xiao-Hua, Liu Zhong, Zheng Li-zhen, Chan Chun-Wai, Lee Kwong-Man, Cao Yong-Ping, Li Gang, Wei Lei, Hung Leung-Kim, Leung Kwok-Sui, Qin Ling. Impaired bone healing pattern in mice with ovariectomy-induced osteoporosis: A drill-hole defect model. 2011 Bone, in press (Ms. Ref. No.: BONE-D-10-00635R2 accepted).
  12. Guan YJ, Yang X, Wei L, Chen Q. MiR-365: A Mechano-sensitive MicroRNA Stimulates Chondrocyte Differentiation through Targeting Histone Deacetylase 4. FASEB J, 2011, in press
Center of Biomedical Research Excellence (COBRE) for Skeletal Health and Repair