Differential localization of Arginyilated Calreticulin to translational and transcritional stress response

MARCOS A. CARPIO; LÓPEZ SAMBROOKS, CECILIA; MAURICIO R. GALIANO; MARTA E. HALLAK

Mar del Plata

Congreso; 43rd Annual Meeting - Argentine Society for Biochemistry and Molecular Biology; 2007

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

The posttranslational arginylation of proteins consists in the covalent union of an arginine into an acidic amino acid at the NH2-terminus. We demonstrated the posttranslational incorporation of arginine into calreticulin (CRT). An antibody that specifically recognizes endogenous arginylated CRT (R-CRT) was developed. By immunocytochemistry it was observed in NIH3T3 cells that R-CRT is localized in the cytosol while CRT is localized in the ER. Under environmental stress conditions (e.g. modified calcium homeostasis, heat and oxidative conditions) that activate the unfolded protein response and shuts down protein synthesis, R-CRT was found associated to stress granules that are a consequence of abortive translational initiations. On the other hand, as a response to DNA damage conditions (e.g. Doxorubicin (Dx), UV), R-CRT was found in cell nucleus. It was described that Dx and UV treatment activate transcriptional factors such as p53, which are translocated to the nucleus. We found that nuclear translocation of R-CRT is different in p53 -/- cells with respect to p53 +/+ cells, suggesting a possible relationship among both. The intranuclear redistribution found for arginylated CRT might be related to pro-apoptotic mechanisms triggered by genotoxic agents. Thus, posttranslational arginylation of CRT can regulate its intracellular localization and perhaps its cell function. 2-terminus. We demonstrated the posttranslational incorporation of arginine into calreticulin (CRT). An antibody that specifically recognizes endogenous arginylated CRT (R-CRT) was developed. By immunocytochemistry it was observed in NIH3T3 cells that R-CRT is localized in the cytosol while CRT is localized in the ER. Under environmental stress conditions (e.g. modified calcium homeostasis, heat and oxidative conditions) that activate the unfolded protein response and shuts down protein synthesis, R-CRT was found associated to stress granules that are a consequence of abortive translational initiations. On the other hand, as a response to DNA damage conditions (e.g. Doxorubicin (Dx), UV), R-CRT was found in cell nucleus. It was described that Dx and UV treatment activate transcriptional factors such as p53, which are translocated to the nucleus. We found that nuclear translocation of R-CRT is different in p53 -/- cells with respect to p53 +/+ cells, suggesting a possible relationship among both. The intranuclear redistribution found for arginylated CRT might be related to pro-apoptotic mechanisms triggered by genotoxic agents. Thus, posttranslational arginylation of CRT can regulate its intracellular localization and perhaps its cell function.