Analysing the Role of Growth Plate Specific Genes in Endochondral Ossification by Specific Overexpression or Deletion under the BAC Col10a1 Promoter

• Applicant: Professor Klaus von der Mark, Ph.D.
• Subject Area: Developmental Biology
• Term: from 2007 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 36677775

Cartilage-bone transition by endochondral ossification is a highly complex process which determines not only longitudinal growth of long bones, ribs and vertebrae, but also plays a critical role in bone fracture callus healing, osteophyte formation and cartilage tissue engineering. Decisive steps in this process are maturation and hypertrophy of chondrocytes in the growth plate before inducing mineralisation, apoptosis and resorption of hypertrophic cartilage followed by bone marrow invasion. These events are regulated by synergistic interactions of several signalling pathways and transcriptions factors controlled by a multitude of growth factors and hormones. In order to elucidate specific functions of genes presumably involved in endochondral ossification, we designed a collagen X specific BAC (Bacterial Artificial Chromosome) recombineering system which allows specific and robust overexpression of reporter genes and other genes of interest in hypertrophic cartilage under the authentic Co110a1 promoter in transgenic mice. The specific aim of this project is to generate a Co110a1-BAC-CRE mouse which will allow specific gene deletion in the growth plate of mutated mice by removing exons flanked by 1oxP sites, primarily (l integral, PTHrP and (-catenin. Second, the transcription factor Sox9 and the hormone-like factor PTHrP, both know to delay chondrocyte maturation, will be overexpressed in BAC –Co110a1 transgenic mice in order to elucidate their specific function in endochondral ossification. We propose that this Co110a1-specific BAC recombineering system will provide a powerful and specific new tool to elucidate and to manipulate the complex process of endochondral ossification.

• DFG Programme: Research Grants