Early activation of p160 by pressure overload in rat heart

Torsoni, Adriana S., Priscila M. Fonseca, Daniela P Crosara-Alberto, and Kleber G. Franchini. Early activation of p160ROCK by pressure overload in rat heart. Am J Physiol Cell Physiol 284: C1411–C1419, 2003. First published February 5, 2003; 10.1152/ajpcell.00098.2002.—We investigated the effects of acute pressure overload on activation of p160ROCK in rat myocardium. Constriction of transverse aorta, controlled to increase peak systolic pressure of ascending aorta by 40 mmHg, induced a rapid association of RhoA with Dbl-3 and p160ROCK. The binding of p160ROCK to RhoA was rapidly increased, peaking at 30 min ( 3.5-fold), but reduced to lower levels ( 1.9-fold) by 60 min of pressure overload. The activity of immunoprecipitated p160ROCK toward myosin light chain increased 2.5-fold within 10 min but decreased to lower levels ( 1.6-fold) after 60 min of pressure overload. Confocal microscopic analysis indicated that pressure overload induced the formation of aggregates of p160ROCK and RhoA along the longitudinal axis of cardiac myocytes. Immunoelectron microscopic analysis showed that pressure overload induced the association of p160ROCK and RhoA to Z-line, T-tubule, and subsarcolemmal areas. The rapid activation of p160ROCK by pressure overload and its aggregation in subcellular structures involved in transmission of mechanical force suggest a role for this enzyme in the mechanobiochemical transduction in the myocardium.