Autophagy Defends Cells Against Invading Group A Streptococcus
Autophagy Defends Cells Against Invading Group A Streptococcus
Science 306: 1037-1039 (2004)
Speaker：楊朝傑 Time：12/22/2004, 13:10~14:00
Commentator：楊倍昌 Place：Room 601
Abstract：
Streptococcus pyogenes (group A Streptococcus, GAS) is known to be the causation of diseases in broad range symptoms that included streptococcal toxic shock syndrome, sepsis, and necrotising fasciitis.1 Nonphagocytic cells are the initial sites of host invasion and internalization by GAS. The internalization of GAS has been considered importantly for GAS persistence, dissemination and resistance antibiotics killing. However, the intracellular fate of GAS is not clear. In this paper, the authors found that the autophagy may play the important role for intracellular GAS. Autophagy is a major intracellular degradation/recycling system ubiquitous in eukaryotic cells. It mediates the bulk degradation of cytoplasmic components in which a portion of the cytoplasm is sequestered in an autophagosome and eventually degraded upon fusion with lysosomes.2 In this paper, the authors found that the autophagy could effectively eliminate intracellular GAS within nonphagocytic cells. When GAS was escaping from endosomes into the cytoplasm, GAS became enveloped by GAS-containing LC3-positive autophagosome-like vacuoles (GcAVs), and were killed upon fusion with lysosomes. In addition, when GAS invaded to autophagy-deficient Atg5-/- cells, GAS survived, multiplied and were released from the cells. These evidences suggested that the autophagic machinery can act as an innate defense system against invading pathogens.3
References：
1. A. L. Bisno, M.O. Brito, and C. M. Collins. Molecular basis of group A streptococcal virulence. Lancet Infect Dis 3: 191–200 (2003).
2. T. Yoshimori. Autophagy: a regulated bulk degradation process inside cells. Biochem. Biophys. Res. Commun. 313: 453-458 (2004).
3. I. Nakagawa et al. Autophay defends cells against invading Group A Streptococcus. Science 306: 1037-1039 (2004).