Chemokines induce matrix metalloproteinase-2 through activation of epidermal growth factor receptor in arterial smooth muscle cells

We have recently shown that vasoactive peptides such as angiotensin II (Ang II) and endothelin-1 (ET-1) increase the expression of Gi proteins and the proliferation of A10 vascular smooth muscle cells (VSMC) through mitogen-activated protein (MAP) kinase – phosphoinositide (PI) 3-kinase pathways. This study was intended to examine the implication of epidermal growth factor receptor (EGFR) activation in ET-1-induced enhanced expression of Gi proteins and proliferation of A10 VSMC, and to further investigate the underlying mechanisms responsible for these increases. Cell proliferation was determined by [3H]thymidine incorporation and the expression of Gi proteins; extracellular signal-regulated kinases 1 and 2 (ERK1/2) and EGFR phosphorylation was determined by Western blotting. Treatment of A10 VSMC with ET-1 enhanced the expression of Gi proteins, which was attenuated by BQ123 and BQ788, antagonists of ETA and ETB receptor respectively. In addition, ET-1 enhanced the phosphorylation of EGFR in A10 VSMC, which was restored to the control levels by EGFR inhibitor and ETA and ETB receptor antagonists. Furthermore, ET-1 also augmented the proliferation and ERK1/2 phosphorylation of A10 VSMC, which were restored to the control levels by inhibition of EGFR. These data suggest that ET-1 transactivates EGFR, which, through MAP kinase signaling, may contribute to the enhanced expression of Gi proteins and thus increased proliferation of A10 VSMC.

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Mechanical stretch stimulates growth of vascular smooth muscle cells via epidermal growth factor receptor

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.2000.278.2.h521 ◽

2000 ◽

Vol 278 (2) ◽

pp. H521-H529 ◽

Cited By ~ 72

Author(s):

Hiroaki Iwasaki ◽

Satoru Eguchi ◽

Hikaru Ueno ◽

Fumiaki Marumo ◽

Yukio Hirata

Keyword(s):

Epidermal Growth Factor Receptor ◽

Smooth Muscle ◽

Growth Factor ◽

Epidermal Growth Factor ◽

Smooth Muscle Cells ◽

Vascular Smooth Muscle Cells ◽

Kinase Inhibitor ◽

Growth Factor Receptor ◽

Mechanical Stretch ◽

Epidermal Growth

We have studied whether activation of epidermal growth factor receptor (EGFR) is involved in stretch-induced extracellular signal-regulated kinase 1/2 (ERK1/2) activation and protein synthesis in cultured rat vascular smooth muscle cells (VSMC). Cyclic stretch (1 Hz) induced a rapid (within 5 min) phosphorylation of ERK1/2, an effect that was time and strength dependent and inhibited by an EGFR kinase inhibitor (AG-1478) but not by a platelet-derived growth factor receptor kinase inhibitor (AG-1296). The stretch rapidly (within 2 min) induced tyrosine phosphorylation of several proteins, among which 180-kDa protein was shown to be EGFR as revealed by blockade with AG-1478 as well as immunoprecipitation with anti-EGFR antibody coupled with immunoblotting with anti-phosphotyrosine antibody. The stretch rapidly (within 2 min) induced association of tyrosine-phosphorylated EGFR with adaptor proteins (Shc/Grb2) as revealed by coprecipitation with glutathione- S-transferase-Grb2 fusion protein coupled with immunoblotting with anti-phosphotyrosine, anti-EGFR, and anti-Shc antibodies. Transfection of a dominant-negative mutant of H-Ras also inhibited stretch-induced ERK1/2 activation. Treatment with a stretch-activated ion channel blocker (Gd3+) and an intracellular Ca2+ antagonist (TMB-8) inhibited stretch-induced phosphorylation of EGFR and ERK1/2. Treatment with AG-1478 and a mitogen-activated protein kinase kinase inhibitor (PD-98059), but not AG-1296, blocked [3H]leucine uptake stimulated by a high level of stretch. These data suggest that ERK1/2 activation by mechanical stretch requires Ca2+-sensitive EGFR activation mainly via stretch-activated ion channels, thereby leading to VSMC growth.

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