Cartilage extracellular matrix (ECM) degradation and angiogenesis are critical for skeletal development in general and for endochondral ossification in particular. Matrix metalloproteinases (MMPs) play an important role in these processes. MMP-14 (or MT1-MMP, membrane type I-MMP), an integral membrane MMP, is prominently expressed during skeletal development. In vitro, MMP-14 cleaves ECM molecules such as collagen I and aggrecan. It is the cell surface activator of progelatinase A and collagenase-3, the most active collagen II protease. These observations predicted a significant role for MMP-14 in cartilage ECM proteolysis and skeletal development. We have confirmed this by generation of transgenic null mice lacking MMP-14, via homologous recombination in embryonic stem cells. The abnormalities in MMP-14 deficient mice include defective cartilage resorption, decreased chondrocyte proliferation, delayed formation of secondary ossification centers, and defective angiogenesis. The consequences of these abnormalities are severe dwarfism and early death. The precise molecular pathways leading up to this phenotype are unknown and will be investigated in this proposal. We will address the effects of the transgene on parameters of chondrocyte performance and bone growth, and on expression of genes for stage specific chondrocyte markers and molecules related to angiogenesis. Experiments are described to determine whether MMP-14 directly resorbs cartilage extracellular matrix or whether it acts through activation of other metalloproteases. Since secondary ossification center formation is delayed, we will study angiogenesis using in vitro and in vivo assays in these mice. In view of preliminary studies which suggest interference with the growth hormone-insulin-like growth factor (IGF) axis in these mice, we will investigate a role for MMP-14 in mediating the bioavailability of free IGF via proteolysis of IGF binding proteins.

National Institute of Health (NIH)
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Research Project (R01)
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Orthopedics and Musculoskeletal Study Section (ORTH)
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Sharrock, William J
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Cleveland Clinic Lerner
United States
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Gonzalo, Pilar; Guadamillas, Marta C; Hernández-Riquer, María Victoria et al. (2010) MT1-MMP is required for myeloid cell fusion via regulation of Rac1 signaling. Dev Cell 18:77-89
Mosig, Rebecca A; Dowling, Oonagh; DiFeo, Analisa et al. (2007) Loss of MMP-2 disrupts skeletal and craniofacial development and results in decreased bone mineralization, joint erosion and defects in osteoblast and osteoclast growth. Hum Mol Genet 16:1113-23
Genis, Laura; Gonzalo, Pilar; Tutor, Antonio S et al. (2007) Functional interplay between endothelial nitric oxide synthase and membrane type 1 matrix metalloproteinase in migrating endothelial cells. Blood 110:2916-23
Galvez, Beatriz G; Genis, Laura; Matias-Roman, Salomon et al. (2005) Membrane type 1-matrix metalloproteinase is regulated by chemokines monocyte-chemoattractant protein-1/ccl2 and interleukin-8/CXCL8 in endothelial cells during angiogenesis. J Biol Chem 280:1292-8
Ray, Bimal K; Shakya, Arvind; Turk, James R et al. (2004) Induction of the MMP-14 gene in macrophages of the atherosclerotic plaque: role of SAF-1 in the induction process. Circ Res 95:1082-90
Somerville, Robert P T; Oblander, Samantha A; Apte, Suneel S (2003) Matrix metalloproteinases: old dogs with new tricks. Genome Biol 4:216
Somerville, Robert P T; Longpre, Jean-Michel; Jungers, Katherine A et al. (2003) Characterization of ADAMTS-9 and ADAMTS-20 as a distinct ADAMTS subfamily related to Caenorhabditis elegans GON-1. J Biol Chem 278:9503-13