HEMIN INDUCES MITOPHAGY IN k562 CELLS

SALASSA BN; VERGARA AN; GROSSO RA; COLOMBO MI.; FADER CM

Rosario

Congreso; 50th reunión anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB); 2014

SAIB

Autophagy is a lysosomal catabolic event which is implicated in the turnover and clearance of cytoplasmic components in healthy and damaged tissue via a lysosomal pathway. This pathway plays a significant role in the erythropoiesis process, contributing to the clearance of some organelles that are not necessary in the mature cells. The main objective of this study was to determine whether hemin, a strong inducer of hemoglobin synthesis, induces erythroid maturation in K562 cells using autophagy. We demonstrated, in K562 cells, that hemin increased the number and size of autophagic vacuoles. These structures were labeled with lysosomal markers such as lysotracker or DQ-BSA. In addition, we have determined by Western blot a rise in the lipidated form of the autophagic protein LC3 (i.e. LC3-II) upon hemin incubation. Likewise, we have also demonstrated an increased expression level of autophagy related genes by semi-quantitative real-time RT-PCR (ie Map1a1b, Beclin1, ATG5). Moreover, we provide evidences that hemin induces mitochondrial membrane depolarization and that mitochondria sequestration by autophagy and requires the active form of NIX protein. Summarizing, we have found that hemin stimulates mitophagy in K562 cells, likely to allow a more efficient and faster erythroid maturation