| Summary: | 碩士 === 國立臺灣大學 === 動物學研究所 === 97 === Sphingosine 1-phosphate (S1P) and Lysophosphatidic acid (LPA) are low molecular weight lysophospholipids (LPLs). Through binding to specific G protein-coupled receptor family, LPLs regulate various cellular functions, including proliferation, migration, invasion, and differentiation. Matrix-Metalloproteinases (MMPs) are Zinc-dependent proteases and more than twenty MMPs have been identified in human. MMPs play important roles in modulating interactions between cells and extracellular matrix (ECM) via the degradation of various matrix proteins. Membrane type 1-metalloproteinase (MT1-MMP) not only degrades ECM protein but also activates metalloproteinase-2 (MMP-2, Gelatinase A), which is important to endothelial cell migration. In addition, tissue inhibitor of metalloproteinase-2 (TIMP-2) also regulates MMP-2 activation. Our previous study showed that LPLs enhance MMP-2 expression and activity in human umbilical vein endothelial cells (HUVECs). In this study, we revealed that LPLs also induce MT1-MMP and TIMP-2 expression in HUVECs through real-time PCR. Furthermore, in the presence of chemical inhibitors, we demonstrated that LPLs-induced MT1-MMP and TIMP-2 expression are through the Gi- and Gq- dependent pathways. Next, we studied the function of MT1-MMP by introducing MT1-MMP siRNA. Herein, we clarified that MT1-MMP is involved in S1P-induced endothelial cell (EC) functions by conducting the MMP-2 activity assay, EC adhesion, and tube formation assay. In the last part, we found that MT1-MMP siRNA down-regulates MMP-2 and TIMP-2 expressions. This indicates that MT1-MMP not only regulates MMP-2 activity but also modulates the expression of MMP-2. To sum up, we suggest that LPLs play a role in regulating MT1-MMP and TIMP-2 expression; moreover, through regulating MMP-2 activity and expression, EC adhesion, and tube formation, MT1-MMP may be an important mediator of LPLs-induced angiogenesis.
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