title: ERK1/2 regulates ANG II-dependent cell proliferation via cytoplasmic activation of RSK2 and nuclear activation of elk1.
abstract: In a concurrently submitted article, we show that ANG II-induced ERK1/2 activation is mediated by both c-Src/Yes/Fyn and heterotrimeric G protein/PKCzeta-dependent signaling. Furthermore, we show that heterotrimeric G protein/PKCzeta-activated ERK1/2 is destined for the nucleus while ERK1/2 activated by c-Src/Yes/Fyn-dependent signaling remains in the cytoplasm. Interestingly, both mechanisms of activation are required for maximum ANG II-induced cell proliferation. In this study, we sought to determine the mechanisms by which ERK1/2 facilitate cell proliferation via these distinct nuclear and cytoplasmic events, using cells that were lacking either c-Src/Yes/Fyn or heterotrimeric G protein/PKCzeta-dependent ERK1/2 activation. A loss of c-Src/Yes/Fyn blocked ANG II-dependent RSK2 activation, RSK2 nuclear translocation, serum-response factor (SRF) phosphorylation, a portion of c-fos transcriptional activity and c-Fos phosphorylation. Blocking ANG II-induced heterotrimeric G protein/PKCzeta activity resulted in a loss of ERK1/2 nuclear translocation, elk1 phosphorylation, and the remaining portion of c-fos transcriptional activity not dependent on c-Src/Yes/Fyn. Inhibition of RSK with the potent and selective inhibitor, SL0101, attenuated ANG II-induced cell proliferation, and, in combination with a PKCzeta pseudosubstrate, completely attenuated cell proliferation. Thus we conclude that ERK1/2 mediate ANG II-dependent cell proliferation via distinct cytoplasmic and nuclear signaling events, which are in turn governed by c-Src/Yes/Fyn and heterotrimeric G protein/PKCzeta-dependent 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; D006224:Cricetinae; D003593:Cytoplasm / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000378:metabolism; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / 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; D044140:Receptor, Angiotensin, Type 1 / Q000235:genetics / Q000378:metabolism; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D050807:ets-Domain Protein Elk-1 / Q000378:metabolism*; 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; D016760:Proto-Oncogene Proteins c-fos; D051076:Proto-Oncogene Proteins c-fyn; D051575:Proto-Oncogene Proteins c-yes; D016392:Proto-Oncogene Proteins pp60(c-src); D044140:Receptor, Angiotensin, Type 1; D038744:Ribosomal Protein S6 Kinases, 90-kDa; D050807:ets-Domain Protein Elk-1; D000099221:Protein Kinase C zeta; C069330:ribosomal protein S6 kinase, 90kDa, polypeptide 3