Demonstration of angiotensin II-induced Ras activation in the trans-Golgi network and endoplasmic reticulum using bioluminescence resonance energy transfer-based biosensors.
Previous studies have demonstrated that molecules of the Ras signaling pathway are present in intracellular compartments, including early endosomes, the endoplasmic reticulum (ER), and the Golgi, and suggested that mitogens can regulate Ras activity in these endomembranes. In this study, we investigated the effect of angiotensin II (AngII) on intracellular Ras activity in living HEK293 cells expressing angiotensin type 1 receptors (AT(1)-Rs) using newly developed bioluminescence resonance energy transfer biosensors. To investigate the subcellular localization of AngII-induced Ras activation, we targeted our probes to various intracellular compartments, such as the trans-Golgi network (TGN), the ER, and early endosomes. Using these biosensors, we detected AngII-induced Ras activation in the TGN and ER, but not in early endosomes. In cells expressing a cytoplasmic tail deletion AT(1)-R mutant, the AngII-induced response was enhanced, suggesting that receptor internalization and β-arrestin binding are not required for AngII-induced Ras activation in endomembranes. Although we were able to demonstrate EGF-induced Ras activation in the plasma membrane and TGN, but not in other endomembranes, AG1478, an EGF receptor inhibitor, did not affect the AngII-induced response, suggesting that the latter is independent of EGF receptor transactivation. AngII was unable to stimulate Ras activity in the studied compartments in cells expressing a G protein coupling-deficient AT(1)-R mutant ((125)DRY(127) to (125)AAY(127)). These data suggest that AngII can stimulate Ras activity in the TGN and ER with a G protein-dependent mechanism, which does not require β-arrestin-mediated signaling, receptor internalization, and EGF receptor transactivation.
Department of Physiology, Faculty of Medicine, Semmelweis University, H-1444 Budapest, Hungary.
András
A
Balla
László Sándor
LS
Erdélyi
Eszter
E
Soltész-Katona
Tamas
T
Balla
Péter
P
Várnai
László
L
Hunyady
D000804:Angiotensin II / Q000032:analysis* / Q000378:metabolism; D019390:Arrestins / Q000235:genetics / Q000378:metabolism; D015374:Biosensing Techniques / Q000379:methods*; D004721:Endoplasmic Reticulum / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008163:Luminescent Measurements / Q000379:methods*; D015689:Oncogene Protein p21(ras) / Q000235:genetics / Q000378:metabolism*; D011799:Quinazolines; D044140:Receptor, Angiotensin, Type 1 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D020032:Tyrphostins / Q000494:pharmacology; D000071557:beta-Arrestins; D021601:trans-Golgi Network / Q000235:genetics / Q000378:metabolism*
D019390:Arrestins; D004791:Enzyme Inhibitors; D011799:Quinazolines; D044140:Receptor, Angiotensin, Type 1; D020032:Tyrphostins; D000071557:beta-Arrestins; D000804:Angiotensin II; C101044:RTKI cpd; D066246:ErbB Receptors; D015689:Oncogene Protein p21(ras)