Leukemia-associated Rho guanine nucleotide exchange factor (LARG) links heterotrimeric G proteins of the G(12) family to Rho

A putative guanine nucleotide exchange factor (GEF), termed leukemia-associ ated RhoGEF (LARG), was recently identified upon fusion to the coding seque nce of the MLL gene in acute myeloid leukemia. Although the function of LAR G is still unknown, it exhibits a number of structural domains suggestive o f a role in signal transduction, including a PDZ domain, a LH/ RGS domain, and a Dbl homology/pleckstrin homology domain. Here, we show that LARG can activate Rho in vivo. Furthermore, we present evidence that LARG is an inte gral component of a novel biochemical route whereby G protein-coupled recep tors (GPCRs) and heterotrimeric G proteins of the Gait family stimulate Rho -dependent signaling pathways. (C) 2000 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.