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

FEBS J. 2007 Sep;274(17):4375-84. doi: 10.1111/j.1742-4658.2007.05966.x.

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Guanine Nucleotide Exchange Factors
  • Humans
  • Ion Channel Gating*
  • Proteome
  • Receptor, Angiotensin, Type 1 / metabolism*
  • Shal Potassium Channels / metabolism*
  • Signal Transduction

Substances

  • Guanine Nucleotide Exchange Factors
  • Proteome
  • Receptor, Angiotensin, Type 1
  • Shal Potassium Channels