Mechanotransduction of rat aortic vascular smooth muscle cells requires RhoA and intact actin filaments.
The growth-promoting effect of mechanical stress on vascular smooth muscle cells (VSMCs) has been implicated in the progress of vascular disease in hypertension. Extracellular signal-regulated kinases (ERKs) have been implicated in cellular responses, such as vascular remodeling, induced by mechanical stretch. However, it remains to be determined how mechanical stretch activates ERKs. The cytoskeleton seems the most likely candidate for force transmission into the interior of the cell. Therefore, we examined (1) whether the cytoskeleton involves mechanical stretch-induced signaling, (2) whether Rho is activated by stretch, and (3) whether Rho mediates the stretch-induced signaling in rat cultured VSMCs. Mechanical stretch activated ERKs, with a peak response observed at 20 minutes, followed by a significant increase in DNA synthesis. Treatment with the ERK kinase-1 inhibitor, PD98059, inhibited the stretch-induced increase in DNA synthesis. Cytochalasin D, which selectively disrupts the network of actin filaments, markedly inhibited stretch-induced ERK activation. In the control state, RhoA was observed predominantly in the cytosolic fraction, but it was translocated in part to the particulate fraction in response to mechanical stretch. Botulinum C3 exoenzyme, which inactivates Rho p21 (known to participate in the reorganization of the actin cytoskeleton), attenuated stretch-induced ERK activation. Inhibition of Rho kinase (p160ROCK) also suppressed stretch-induced ERK activation dose dependently. Our results suggest that mechanotransduction in VSMCs is dependent on intact actin filaments, that Rho is activated by stretch, and that Rho/p160ROCK mediates stretch-induced ERK activation and vascular hyperplasia.
Numaguchi
K
K
Department of Biochemistry, Vanderbilt University School of Medicine, Meharry Medical College, Nashville, TN, USA.
Eguchi
S
S
Yamakawa
T
T
Motley
E D
ED
Inagami
T
T
D036002:ADP Ribose Transferases / Q000494:pharmacology; D000199:Actins / Q000502:physiology*; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000166:cytology / Q000502:physiology*; D001692:Biological Transport / Q000502:physiology; D001905:Botulinum Toxins; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D019204:GTP-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000502:physiology*; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D051381:Rats; D015398:Signal Transduction / Q000502:physiology*; D013314:Stress, Mechanical; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein
D000199:Actins; D047908:Intracellular Signaling Peptides and Proteins; D010982:Platelet-Derived Growth Factor; C075278:platelet-derived growth factor A; D000804:Angiotensin II; D004247:DNA; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D001905:Botulinum Toxins; D019204:GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein