The mechanism of angiotensin II-induced extracellular signal-regulated kinase-1/2 activation is independent of angiotensin AT(1A) receptor internalisation

• Published in: Cellular signalling 2001-04, Vol.13 (4), p.269-277
• Main Authors: Turner, N A, Ball, S G, Balmforth, A J
• Format: Article
• Language: English
• Subjects: Angiotensin II - genetics; Angiotensin II - metabolism; Animals; Calcium - physiology; Cell Line; Concanavalin A - pharmacology; Dose-Response Relationship, Drug; Enzyme Activation; Humans; Immunoblotting; Mitogen-Activated Protein Kinase 1 - metabolism; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinases - metabolism; Models, Biological; Mutation; Protein Kinase C - metabolism; Protein Kinase C - physiology; Proto-Oncogene Proteins pp60(c-src) - metabolism; Rats; Receptor, Angiotensin, Type 1; Receptor, Epidermal Growth Factor - metabolism; Receptors, Angiotensin - chemistry; Receptors, Angiotensin - genetics; Receptors, Angiotensin - metabolism; Signal Transduction; Time Factors; Transcriptional Activation; Transfection
• ISSN: 0898-6568
• DOI: 10.1016/S0898-6568(01)00135-8

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.