ERYTHROPOIETIN DIFFERENTIAL ACTION ON MATURE AND IMMATURE SH-SY5Y CELL CULTURES

WENKER, SHIRLEY; CHAMORRO MARÍA EUGENIA; VITTORI DANIELA; NESSE ALCIRA

Huerta Grande-Córdoba

Congreso; I Reunión Conjunta de Neurociencias (IRCN); 2009

Sociedad Argentina de Investigación en Neurociencias

Erythropoietin (Epo) has emerged as a multifunctional factor that could play an important role in tissues outside the hematopoietic system. In previous works, we found an Epo antiapoptotic action on undifferentiated neuronal SH-SY5Y cells against cytotoxicity induced by stauroporine (STP) or TNF-alpha. Then, we investigated whether the protective effect of Epo could be detected in neuronal cells differentiated by retinoic acid (RA). Immature and mature stages of SH-SY5Y cells were exposed to proapoptotic agents. In immature cell cultures, STP, TNF-alpha or hypoxia significantly reduced cell viability (MTT assay) and increased apoptosis (Hoechst staining) (STP 49±3, TNF 49±3, H 28±2, P0.05 vs. Control). However, cell resistance was observed after RA differentiated cells (RA-STP 28±3, RA-TNF 15±3, RA-H 7±2, P0.05 vs. Control). Pretreatment of undifferentiated cells with Epo significantly (P0.05) prevented cell death against STP (23±3), TNF (20±6), or hypoxia (7±2). These effects can be partially explained by Bcl-xL and Bcl-2 upregulation (RT-PCR and Western Blotting). Instead, no additional effect of Epo was observed upon differentiated cells. Inhibition of Jak-2 pathway and ARNm analysis of the erythropoietin receptor (Real time PCR) suggest that this lack of response could be associated to receptor downregulation. In conclusion, Epo is able to protect immature SH-SY5Y cells from cell death induced by STP, TNF-alpha or hypoxia but is uncapable to affect RA-differentiated cells. A close dependence of the Epo neuroprotective action on the degree of cell differentiation could be one explanation. This differential behavior of immature and mature neuronal cells could be important in the pharmacological effect of Epo.