HEMIN INDUCES AUTOPHAGY IN LEUKEMIC ERYTHROBLAST CELL LINE

FADER CM; VERGARA A; MOOR F; SALASSA N; COLOMBO MI

Mendoza

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular; 2012

Autophagy is a normal degradative pathway that involves the sequestration of cytoplasmic components and organelles in a vacuole called autophagosome which finally fuses with the lysosome to degrade the sequestered material. 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 indicate that hemine (erythroid maturation inductor) produced an increased number and enlargement of GFP-LC3 positive vesicles labeled with lysotracker or DQ-BSA compared with others maturation inductors. 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 an increased total amount and a higher level of processed GFP-LC3. Taken together, our results suggest that  hemin  could induce an autophagic response in K562 cells, probably allowing an efficient and faster maturation.