Static strain stimulates expression of matrix metalloproteinase‐2 and VEGF in microvascular endothelium via JNK‐ and ERK‐dependent pathways

Abstract

VEGF and MMP protein production are both required for exercise-induced capillary growth in skeletal muscle. The underlying process by which muscle activity initiates an angiogenic response is not established, but it is known that mechanical forces such as muscle stretch are involved. We hypothesized that stretch of skeletal muscle microvascular endothelial cells induces production of MMP-2 and VEGF through a common signal pathway. Endothelial cells were grown on Bioflex plates and exposed to 10% static stretch for up to 24 h. MMP-2 protein level was measured by gelatin zymography and VEGF, MMP-2, and MT1-MMP mRNA levels were quantified by real-time quantitative PCR. ERK1/2 and JNK phosphorylation and VEGF protein levels were assessed by Western blotting. Effects of mitogen-activated protein kinases (MAPKs) (ERK1/2, JNK) and reactive oxygen species (ROS) on stretch-induced expression of MMP-2 and VEGF were tested using pharmacological inhibitors. Stretching of endothelial cells for 24 h caused significant increases in MMP-2 protein and mRNA level, but no change in MT1-MMP mRNA. While MMP-2 protein production was enhanced by H(2)O(2) in unstretched cells, ROS inhibition during stretch did not diminish MMP-2 mRNA or protein production. Inhibition of JNK suppressed stretch-induced MMP-2 protein and mRNA, but inhibition of ERK had no effect. In contrast, inhibition of ERK but not JNK attenuated the stretch-induced increase in VEGF mRNA. Our results demonstrate that differential regulation of MMP-2 and VEGF by MAPK signal pathways contribute to stretch-induced activation of microvascular endothelial cells.

Endurance exercise activates matrix metalloproteinases in human skeletal muscle

“…As was observed for MMP-9, restricted blood flow to the exercising muscle had no effect on MMP-2 mRNA level and activity, or on MMP-14 and TIMP-1 mRNA levels. The expression of MMPs in skeletal muscle endothelial cells is greatly affected by mechanical stretch (22,23,27) and MMP-2 expression in muscle tendon is increased by mechanical loading (15,20). These results are consistent with our findings, in that the workload and thus presumably the mechanical load was identical under the two exercise conditions.…”

Intermittent pneumatic leg compressions acutely upregulate VEGF and MCP-1 expression in skeletal muscle

“…In cultured endothelial cells, HIF-1␣ mRNA was found to be upregulated after 24 h but not after 6 h of exposure to static stretch (30). Likewise, changes in MMP-2 mRNA are not significant until 6 h of static strain application in microvascular endothelial cells (32). In humans, Rullman et al (40) also failed to find changes in the expression of MMP-2 following an acute bout (65 min) of exercise.…”

Matrix Metalloproteinase 2 as a Potential Mediator of Vascular Smooth Muscle Cell Migration and Chronic Vascular Remodeling in Hypertension

“…In endothelial cells, static stretch increases MMP-2 expression via c-Jun N-terminal kinase (JNK; fig. 1a) [35]. Moreover, inhibition of nuclear factor kappa B (NF-κB), but not extracellular-signal-regulated kinase (ERK), blocked MMP-2 activation in aorta cultured at 150 mm Hg, thus suggesting that NF-κB also participates in mechanical stress and pressure-induced vascular remodeling [4,36].…”