THE SECRETORY PATHWAY AND ITS ADAPTATION TO A HIGH SECRETORY DEMAND

MARTINEZ H; SAMPIERI L; GARCÍA IA; ALVAREZ CA

Rosario

Congreso; L Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2014

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Membrane transport from the ER to the Golgi complex requires multiple molecules located in at least three distinctmembrane entities: at specialized subdomains of the Endoplasmic reticulum called ERES (ER exit sites), at VTCs(Vesicular tubular clusters) and at cis-Golgi network. The mammalian Rab1 GTPase is essential for ER to Golgitransport and, through its interactions with diverse effector proteins, regulates the formation, tethering and fusion oftransport carriers derived from the ER. It is clear that Rab1b is acting in sequential stages at the ER-Golgi transportand we propose a model that postulates that Rab1b is a coordinator of this step of transport.Furthermore, since Rab1 isoforms (Rab1a and Rab1b) are ubiquitous and different tissues express dissimilar mRNAlevels of Rab1 isoforms, we also analyzed cellular effects induced by changes of Rab1b levels. We report that anincrease in Rab1b levels induces changes in Golgi structure and gene expression. Such gene expression changesrequire the activation of p38 mitogen-activated protein kinase (MAPK) and the cAMP-responsive element-bindingprotein (CREB) binding consensus site. The data strongly suggest that a Rab1b increase is required to elicit asecretory response