title: Voltage-gated ion channel Kv4.3 is associated with Rap guanine nucleotide exchange factors and regulates angiotensin receptor type 1 signaling to small G-protein Rap.
abstract: The voltage-gated potassium channel Kv4.3 was coexpressed with its beta-subunit Kv channel-interacting protein 2 and the angiotensin type 1 receptor in HEK-293 cells. Proteomic analysis of proteins coimmunoprecipitated with Kv4.3 revealed that Kv4.3 is associated with Rap guanine nucleotide exchange factors MR-GEF and EPAC-1. Previously, we demonstrated that Kv4.3 interacts with the angiotensin type 1 receptor in HE293 cells and cardiac myocytes. On the basis of this, we investigated the angiotensin type 1 receptor signaling to small G-proteins Ras and Rap-1 in the presence and absence of the Kv4.3-Kv channel-interacting protein 2 macromolecular complex. Ras activation was not significantly affected by coexpression of Kv4.3 and Kv channel-interacting protein 2. Ras exhibited a rapid activation-inactivation pattern with maximum activity at 2.5 min after addition of angiotensin II. In contrast, activation of Rap-1 was affected dramatically by coexpression of Kv4.3 and Kv channel-interacting protein 2 with the angiotensin type 1 receptor. In the absence of Kv4.3 and Kv channel-interacting protein 2, stimulation of the angiotensin type 1 receptor resulted in steady activation of Rap-1 that reached a plateau 25 min after addition of angiotensin II. In the presence of Kv4.3 and Kv channel-interacting protein 2, Rap-1 reaches a maximum activity 2.5 min after addition of angiotensin II and then deactivates rapidly, demonstrating a pattern of activation similar to that of Ras. Our findings show that Kv4.3 regulates angiotensin type 1 receptor signaling to the small G-protein Rap-1.
authors.affiliation: Department of Physiology and Biophysics, Institute of Molecular Cardiology, State University of New York at Stony Brook, Stony Brook, NY 11794, USA.
authors.forename: Irina A
authors.initials: IA
authors.lastname: Potapova
authors.forename: Ira S
authors.initials: IS
authors.lastname: Cohen
authors.forename: Sergey V
authors.initials: SV
authors.lastname: Doronin
mesh_terms: D002460:Cell Line; D020662:Guanine Nucleotide Exchange Factors; D006801:Humans; D015640:Ion Channel Gating; D020543:Proteome; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism*; D051672:Shal Potassium Channels / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D020662:Guanine Nucleotide Exchange Factors; D020543:Proteome; D044140:Receptor, Angiotensin, Type 1; D051672:Shal Potassium Channels