MMP-2 functions as a negative regulator of chondrogenic cell condensation via down-regulation of the FAK-integrin beta1 interaction.
Matrix metalloprotease-2 (MMP-2) has the capacity to degrade cartilage extracellular matrix molecules, the turnover of which is an essential event in chondrogenesis. Here, we investigated the functional role of MMP-2 in chondrogenesis of leg bud mesenchymal cells. Small interference RNA (siRNA)-mediated knockdown of mmp-2 promoted precartilage condensation and chondrogenesis. Treatment with bafilomycin A1, an MMP-2 activator, or GM6001, an MMP inhibitor, at the pre-condensation stage resulted in the inhibition or promotion of chondrogenesis, respectively. By comparison, treatment at the post-condensation stage had little or no effect on chondrogenesis. These results indicate that MMP-2 is involved in the regulation of cell condensation. Inhibition of MMP-2 activity by mmp-2 specific siRNA increased the protein level of fibronectin, and integrins alpha5 and beta1. The interaction between focal adhesion kinase (FAK) and integrin beta1 leading to tyrosine phosphorylation of FAK was also enhanced. Moreover, inactivation of p38MAPK down-regulated the level of MMP-2 mRNA and activity, and increased mesenchymal cell condensation in parallel with enhanced phosphorylation of FAK. Taken together, our data indicate that MMP-2 mediates the inhibitory signals of p38MAPK during mesenchymal cell condensation by functioning as a negative regulator of focal adhesion activity regulated by FAK via interactions with fibronectin through integrin beta1.
Jin
Eun-Jung
EJ
Department of Biology, College of Natural Sciences (BK21), Daegu 702-701, Korea.
Choi
Young-Ae
YA
Kyun Park
Eui
E
Bang
Ok-Sun
OS
Kang
Shin-Sung
SS
D000818:Animals; D001483:Base Sequence; D002642:Chick Embryo; D020219:Chondrogenesis / Q000235:genetics / Q000502:physiology*; D017931:DNA Primers / Q000235:genetics; D015536:Down-Regulation; D005121:Extremities / Q000196:embryology; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism*; D019012:Integrin beta1 / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000378:metabolism*; D061965:Matrix Metalloproteinase Inhibitors; D059630:Mesenchymal Stem Cells / Q000378:metabolism; D010766:Phosphorylation; D034741:RNA, Small Interfering / Q000235:genetics; D014443:Tyrosine / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D017931:DNA Primers; D019012:Integrin beta1; D061965:Matrix Metalloproteinase Inhibitors; D034741:RNA, Small Interfering; D014443:Tyrosine; D051416:Focal Adhesion Protein-Tyrosine Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020778:Matrix Metalloproteinase 2