title: The mechanism of angiotensin II-induced extracellular signal-regulated kinase-1/2 activation is independent of angiotensin AT(1A) receptor internalisation.
abstract: The aim of this study was to determine whether internalisation of the angiotensin II (Ang II) AT(1A) receptor (AT(1A)R) was a prerequisite for Ang II-induced activation of the extracellular signal-regulated kinases, ERK-1/2. The human embryonic kidney (HEK293) cell line stably transfected with either the wild-type rat AT(1A)R or an internalisation-deficient C-terminal truncated mutant of the AT(1A)R (AT(1A)T318R) was used as a model for these studies. Inhibition of AT(1A)R internalisation by treatment with an inhibitor of clathrin-mediated endocytosis, Concanavalin A (Con A), did not inhibit Ang II-induced ERK-1/2 activation. Furthermore, cells transfected with the internalisation-deficient AT(1A)T318R mutant readily activated ERK-1/2 in response to Ang II. Ang II activated ERK-1/2 via two distinct signalling pathways in HEK-AT(1A)R cells. Approximately half of Ang II-induced ERK-1/2 activation was protein kinase C (PKC)-dependent, and the remainder was calcium- and c-Src-dependent and involved transactivation of the epidermal growth factor receptor (EGFR). In summary, Ang II-induced activation of ERK-1/2 occurs via two distinct pathways in HEK293 cells, neither of which requires AT(1A)R internalisation.
authors: Integrated Molecular Cardiology Group, Institute for Cardiovascular Research, Worsley Building, University of Leeds, LS2 9JT, Leeds, UK.
authors: N A
authors: NA
authors: Turner
authors: S G
authors: SG
authors: Ball
authors: A J
authors: AJ
authors: Balmforth
mesh_terms: D000804:Angiotensin II / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000502:physiology; D002460:Cell Line; D003208:Concanavalin A / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D066246:ErbB Receptors / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008954:Models, Biological; D009154:Mutation; D011493:Protein Kinase C / Q000378:metabolism / Q000502:physiology; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism; D051381:Rats; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors; D015533:Transcriptional Activation; D014162:Transfection
chemical_list: D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin; D003208:Concanavalin A; D000804:Angiotensin II; D066246:ErbB Receptors; D016392:Proto-Oncogene Proteins pp60(c-src); D011493:Protein Kinase C; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D002118:Calcium