title: ANG II-induced cell proliferation is dually mediated by c-Src/Yes/Fyn-regulated ERK1/2 activation in the cytoplasm and PKCzeta-controlled ERK1/2 activity within the nucleus.
abstract: High-affinity binding of angiotensin II (ANG II) to the ANG II type 1 receptor (AT(1)R) results in the activation of ERK1/2 mitogen-activated protein kinases (MAPK). However, the precise mechanism of ANG II-induced ERK1/2 activation has not been fully characterized. Here, we investigated the signaling events leading to ANG II-induced ERK1/2 activation using a c-Src/Yes/Fyn tyrosine kinase-deficient mouse embryonic fibroblast (MEF) cell line stably transfected with the AT(1)R (SYF/AT(1)). ERK1/2 activation was reduced by approximately 50% within these cells compared with wild-type controls (WT/AT(1)). The remaining approximately 50% of intracellular ERK1/2 activation was dependent upon heterotrimeric G protein and protein kinase C zeta (PKCzeta) activation. Therefore, ANG II-induced ERK1/2 activation occurs via two independent mechanisms. We next investigated whether a loss of either c-Src/Yes/Fyn or PKCzeta signaling affected ERK1/2 nuclear translocation and cell proliferation in response to ANG II. ANG II-induced cell proliferation was markedly reduced in SYF/AT(1) cells compared with WT/AT(1) cells (P < 0.01), but interestingly, ERK2 nuclear translocation was normal. ANG II-induced nuclear translocation of ERK2 was blocked via pretreatment of WT/AT(1) cells with a PKCzeta pseudosubstrate. ANG II-induced cell proliferation was significantly reduced in PKCzeta pseudosubstrate-treated WT/AT(1) cells (P < 0.01) and was completely blocked in SYF/AT(1) cells treated with this same compound. Thus ANG II-induced cell proliferation appears to be regulated by both ERK1/2-driven nuclear and cytoplasmic events. In response to ANG II, the ability of ERK1/2 to remain within the cytoplasm or translocate into the nucleus is controlled by c-Src/Yes/Fyn or heterotrimeric G protein/PKCzeta signaling, respectively.
authors.affiliation: Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida 32610, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Godeny
authors.forename: Peter P
authors.initials: PP
authors.lastname: Sayeski
mesh_terms: D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000378:metabolism; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D051076:Proto-Oncogene Proteins c-fyn / Q000378:metabolism*; D051575:Proto-Oncogene Proteins c-yes / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism*; D051381:Rats; D044140:Receptor, Angiotensin, Type 1 / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D000099221:Protein Kinase C zeta
chemical_list: D000804:Angiotensin II; D004791:Enzyme Inhibitors; D020962:Heterotrimeric GTP-Binding Proteins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D011493:Protein Kinase C; D051076:Proto-Oncogene Proteins c-fyn; D051575:Proto-Oncogene Proteins c-yes; D016392:Proto-Oncogene Proteins pp60(c-src); D044140:Receptor, Angiotensin, Type 1; D011993:Recombinant Fusion Proteins; D000099221:Protein Kinase C zeta