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

• Main Authors: Fluharty Eric, Vasudevan Chandrasekaran, Rizzo Mark A, Rojas Raúl, Shome Kuntala, Li Hai-Sheng, Santy Lorraine C, Casanova James E, Romero Guillermo
• Format: Article
• Language: English
• Published: BMC 2003-09-01
• Series: BMC Cell Biology
• Online Access: http://www.biomedcentral.com/1471-2121/4/13

<p>Abstract</p> <p>Background</p> <p>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.</p> <p>Results</p> <p>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.</p> <p>Conclusions</p> <p>Small ARF-GEFs of the cytohesin/ARNO family mediate the activation of ARF and PLD by the insulin receptor.</p>