Cyclic strain-mediated regulation of endothelial matrix metalloproteinase-2 expression and activity.

OBJECTIVE: To investigate the role of cyclic strain in controlling matrix metalloproteinase-2 (MMP-2) expression and activity in endothelial cells (ECs) in vitro.
METHODS: A Flexercell Tension Plus FX-4000T system was used to apply a physiological level of equibiaxial cyclic strain (0-10% strain, 60 cycles/min, 0-24 h, cardiac waveform) to bovine aortic endothelial cells (BAECs). Cells and conditioned media were harvested for analysis of MMP-2/9 expression and activity (pro and active) using reverse-transcriptase polymerase chain reaction (RT-PCR), Western blotting and zymography techniques.
RESULTS: Cyclic strain significantly increased MMP-2 expression and activity force- and time-dependently. Pretreatment with Gialpha-protein inhibitors, pertussis toxin (PTX) and NF023, transient expression of inhibitory mutants of Gialpha-subunits, or pretreatment with RGD peptides to block RGD-dependent integrin signaling failed to attenuate strain-induced increases in MMP-2 expression in BAECs. In contrast, inhibition of Gbetagamma-signaling with betaArk-ct or tyrosine kinase blockade with genistein reduced strain-induced MMP-2 expression while concomitantly inhibiting strain-induced p38 and ERK activity in these cells. Pretreatment with PD169316 and PD98059 to selectively inhibit p38 and ERK activity, respectively, also resulted in a significant inhibition of the strain-induced MMP-2 response. Finally, inhibition of the adaptor protein, Shc, (via Shc-SH2 transfection) resulted in a significant decrease in strain-induced MMP-2 activity concomitant with a reduction in ERK activity in BAECs.
CONCLUSION: Cyclic strain stimulates MMP-2 expression, in part, by stimulating both p38- and ERK-dependent pathways through activation of Gbetagamma and tyrosine kinase in BAECs.