Figure 16.1. Effect of adenovirus-mediated expression of Rab1 and its dominant negative mutant Rab1N124I on the cell surface expression (A) and subcellular localization (B) of GPCRs in neonatal cardiomyocytes. (A) Cardiomyocytes were cultured and infected with control, Rab1, or Rab1N124I adenovirus for 2 days at a multiplicity of infection of 20. The cell-surface expression of AT1R, α₁-AR, and β-AR was determined by the radioligand [³H]-Ang II, [³H]-prazosin, and [³H]-CGP12177, respectively. The data shown are the percentage of the mean value obtained from the cardiomyocytes infected with control adenovirus (the dotted line). *p<0.05 versus control. (B) Cardiomyocytes were grown on coverslips, infected with control or Rab1N124I adenoviruses, and transiently transfected with GFP-tagged β₂-AR. Two days after infection, the myocytes were fixed and stained with 4,6-diamidino-2-phenylindole (nuclear). Blue, nuclear stained by 4,6-diamidino-2-phenylindole; green, GFP-β₂-AR. (From Filipeanu, C. M., Zhou, F., Claycomb, W. C., and Wu, G. (2004). Regulation of the cell surface expression and function of angiotensin II type 1 receptor by Rab1-mediated endoplasmic reticulum-to-Golgi transport in cardiac myocytes. J. Biol. Chem. 279, 41077–41084; and Filipeanu, C. M., Zhou, F., Fugetta, E. K., and Wu, G. (2006a). Differential regulation of the cell-surface targeting and function of β- and α1-adrenergic receptors by Rab1 GTPase in cardiac myocytes. Mol. Pharmacol.69, 1571–1578.)

Figure 16.2. Effect of adenovirus-mediated expression of Rab1 and its dominant negative mutant Rab1N124I on Ang II–stimulated hypertrophic response in neonatal cardiomyocyte. To reflect the effect of Rab1 on Ang II–mediated stimulation, the contribution of Rab1 itself to protein synthesis and cell surface area was subtracted. Cardiomyocytes were cultured and infected with control, Rab1, and Rab1N124I adenoviruses for 2 days, and then stimulated with Ang II (100 nM) for 24 h. (A) Effect of Rab1 on Ang II–stimulated total protein synthesis measured by [³H]-leucine incorporation. (B) Effect of Rab1 on Ang II–mediated increase in cell surface area. (C) Effect of Rab1N124I on Ang II–stimulated sarcomeric organization revealed by staining with phalloidin for F-actin. *p <0.05 versus control. (Adapted from From Filipeanu, C. M., Zhou, F., Claycomb, W. C., and Wu, G. (2004). Regulation of the cell surface expression and function of angiotensin II type 1 receptor by Rab1-mediated endoplasmic reticulum-to-Golgi transport in cardiac myocytes. J. Biol. Chem. 279, 41077–41084.)