beta3-chimaerin, a new member of the chimaerin family with a novel SH3 interacting domain

ZUBELDIA BRENNER L; ALVARO GUTIERREZ-UZQUIZA; HONGBIN WANG; KAZANIETZ MARCELO G.; COLUCCIO LESKOW FEDERICO

Bariloche

Congreso; Sistam; 2012

beta3-chimaerin, a new member of the chimaerin family with a novel SH3 interacting domain Federico Coluccio Leskow1, Lautaro Zubeldia-Brenner1*, Alvaro Gutierrez-Uzquiza2*, Hongbin Wang2 and Marcelo G. Kazanietz2 1. Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, IQUIBICEN-CONICET, Buenos Aires, C1428EGA, Argentina. 2. Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6160, USA * These authors contributed equally to this work. federico@fbmc.fcen.uba.ar Abstract: Chimaerins are a family of DAG-modulated regulators of the small GTPase Rac playing a crucial role in development, axon guidance, metabolism, cell migration, and T-cell activation. Four chimaerin isoforms have been reported to-date as products of two chimaerin genes: CHN1 (alpha1 and 2) and CHN2 (beta1 and 2). The known products of these genes are assumed to be generated by alternative splicing. Bioinformatic analysis of the CHN2 gene revealed that these beta1 and beta2 are the product of alternate transcription start sites regulated by different promoter regions. We report the cloning and functional characterization of beta3-chimaerin, the product of an additional transcription star site 80 Kb upstream CHN2. The expression profile of beta3-chimaerin was analyzed by Real Time PCR using a hole body cDNA array, showing higher levels of mRNA in epididymis, plasma blood leucocytes, spleen and thymus. Using a brain cDNA array we also detected high levels of expression in the pituitary gland, cerebellum grey, cerebellum white and vermis. Beta3-chimaerin differs from beta2-cimaerin on its N-terminal domain being 7 times more sensitive to PMA-induced translocation with a higher Rac-GAP activity. This N-terminal domain is only conserved in chimpanzees and has no sequence identity to any other known protein. Using a yeast two hybrid assay we proved that this novel domain interacts with Nck third SH3 domain, representing a novel SH3 interacting domain.