Research article

The Guanine Nucleotide Exchange Factor ARNO mediates the activation of ARF and phospholipase D by insulin

Hai-Sheng Li¹ , Kuntala Shome¹ , Raúl Rojas^1,2 , Mark A Rizzo¹ , Chandrasekaran Vasudevan¹ , Eric Fluharty¹ , Lorraine C Santy³ , James E Casanova³ and Guillermo Romero¹

¹Departments of Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, U.S.A

²Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, U.S.A

³Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22908, U.S.A

author email corresponding author email

BMC Cell Biology 2003, 4:13doi:10.1186/1471-2121-4-13

Published:	11 September 2003

Abstract

Background

Phospholipase D (PLD) is involved in many signaling pathways. In most systems, the activity of PLD is primarily regulated by the members of the ADP-Ribosylation Factor (ARF) family of GTPases, but the mechanism of activation of PLD and ARF by extracellular signals has not been fully established. Here we tested the hypothesis that ARF-guanine nucleotide exchange factors (ARF-GEFs) of the cytohesin/ARNO family mediate the activation of ARF and PLD by insulin.

Results

Wild type ARNO transiently transfected in HIRcB cells was translocated to the plasma membrane in an insulin-dependent manner and promoted the translocation of ARF to the membranes. ARNO mutants: ΔCC-ARNO and CC-ARNO were partially translocated to the membranes while ΔPH-ARNO and PH-ARNO could not be translocated to the membranes. Sec7 domain mutants of ARNO did not facilitate the ARF translocation. Overexpression of wild type ARNO significantly increased insulin-stimulated PLD activity, and mutations in the Sec7 and PH domains, or deletion of the PH or CC domains inhibited the effects of insulin.

Conclusions

Small ARF-GEFs of the cytohesin/ARNO family mediate the activation of ARF and PLD by the insulin receptor.