Possible roles of LC3-independent autophagy in elimination of Shigella in human colon cells (INC4P.343)

Abstract Autophagy is essential for the defense against bacterial invasion. The intestinal tract is quite specialized in order to co-exist with extracellular bacteria, and thus, this system efficiently exploits autophagy to regulate the number of bacteria and to control the immune response to preventing chronic inflammation. Bacterial elimination is mediated by microtubule-associated protein 1A/1B-light chain 3 (LC3), which is critical for the activation of the autophagic canonical pathway in mammals. Although both human colon HT-29 cell line and the human cervical HeLa cell line display normal LC3 expression, HeLa cells are very susceptible to Shigella infection, whereas HT-29 cells efficiently restrict the number of intracellular Shigella. Our results suggest that colon cells may utilize LC3-independent noncanonical autophagy to regulate bacterial growth and survival.