HEMIN INDUCES AUTOPHAGY IN LEUKEMIC ERYTHROBLASTS.

RECALDE, MG.; VERGARA, A.N.; MOOR, F.; COLOMBO M.I.; FADER, C.M.

Potrero de los Funes-San Luis

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB).; 2011

In eukaryotic cells, autophagy is a conserved intracellular pathway in which cytoplasmic components and some organelles are sequestered in a double-membrane vacuole (autophagosome) and degraded in the lysosomal compartment. Autophagy has been associated with several physiologic processes as erythroid maturation. LC3 is a protein present in autophagosomal membrane, therefore is considerate as a bonafide marker of this structure. Our results have shown that hemin (an erythroblast maturation inductor) produced an increased number and enlargement of GFP-LC3 positive vesicles labeled with lysotracker or DQ-BSA compared with others inductors as phorbol ester, sodium butyrate and dihydroxyurea. Moreover, we have demonstrated, in K562 cells incubated with hemin, an enlargement GFP-Lamp1 positive vesicles labeled with mitotracker. We have also shown in erythroblastic leukemic cells co-expressing RFP-LC3 and GFPRab11 (a multivesicular bodies marker) incubated in the presence of hemin an enlarged vesicles labeled with both markers. Likewise, we have performed a western blot to detect the processing of LC3 protein upon hemin incubation. We have observed in this assay that GFP-LC3 protein was cleaved, generating low molecular weight products. Taken together, our results suggest that hemin could induce an autophagic response in K562 cells, probably allowing an efficient and faster maturation.