INIMEC - CONICET   05467
INSTITUTO DE INVESTIGACION MEDICA MERCEDES Y MARTIN FERREYRA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
GM2-Ganglioside Accumulation Mediates Endoplasmic Reticulum Calcium Depletion and PERK Signalling Activation
Autor/es:
VIRGOLINI, MARÍA JOSÉ; LOPEZ, PABLO HH; BOLLO, MARIANA I
Lugar:
Puerto Varas
Reunión:
Congreso; XXVIII Reunión Anual Sociedad de Biología Celular de Chile; 2014
Institución organizadora:
Sociedad de Biología Celular de Chile
Resumen:
Introduction: The accumulation of misfolded proteins within the endoplasmic reticulum (ER) triggers a cellular process known as the Unfolded Protein Response (UPR), in which the cell attempts to restore ER homeostasis. If ER damage is persistent or excessive, an apoptotic response is initiated. It is well accepted that ER calcium depletion induces ER stress. PERK is an early ER stress sensor that attenuates protein synthesis. We demonstrated that Calcineurin (CN) associates with PERK, enhancing inhibition of protein translation and cell viability. But PERK signaling, including pro-apoptotic transcription factor CHOP, persists activated under prolonged stress. Chronic UPR is proposed to contribute to the pathology of many neurodegenerative diseases. GM2-gangliosidosis are characterized by a progressive neurodegeneration due to deficiency in -hexosaminidase activity. However, the mechanisms that determine how GM2 accumulation triggers neuronal cell death remain unknown. Material and Methods: N2A cells were either loaded with GM2 or treated with ShRNA specific for -hexosaminidase. The GM2 accumulation in the ER was assessed by thin layer chromatography and immunocytochemistry. Besides, we exanimated whether UPR was activated using immunopresipitations, western-bloting and Ca2+ measurements. Results and Discussion: We report that the GM2 accumulation in the ER induces PERK activation, and provokes up-regulation of either CN or CHOP, at different time points. This stress also decreases the ER calcium content. Moreover, calcium depletion, as well as CHOP level increase, were enhanced by MBCD, a pharmacological agent that augment ganglioside delivery to the ER. This finding suggests that varied time course of the individual PERK signaling elements influence the cell?s ultimate fate in response to abnormal GM2 accumulation