An Initial Step of GAS-Containing Autophagosome-Like Vacuoles Formation Requires Rab7

PLoS Pathogens

Takeshi Noda¹  Ichiro Nakagawa²  Tamotsu Yoshimori³  Atsuo Amano⁴  Akitsugu Yamamoto⁵  Hitomi Yamaguchi⁶ 

[1] Department of Cell Biology, Faculty of Bio-Science, Nagahama Institute of Bio-Science and Technology, Nagahama-Shiga, Japan;Department of Cell Regulation, Research Institute for Microbial Diseases, Osaka University, Suita-Osaka, Japan;Department of Oral Frontier Biology, Osaka University Graduate School of Dentistry, Suita-Osaka, Japan;PRESTO, Japan Science and Technology Agency, Kawaguchi-Saitama, Japan;Section of Bacterial Pathogenesis, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan;Structural Biology Center, National Institute of Genetics/SOKENDAI, Mishima-Shizuoka, Japan

关键词: HeLa cells;    Autophagic cell death;    Membrane fusion;    Lysosomes;    Fluorescence microscopy;    DAPI staining;    Cytoplasm;    Electron microscopy;   

DOI  :  10.1371/journal.ppat.1000670

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Group A streptococcus (GAS; Streptococcus pyogenes) is a common pathogen that invades non-phagocytic human cells via endocytosis. Once taken up by cells, it escapes from the endocytic pathway to the cytoplasm, but here it is contained within a membrane-bound structure termed GAS-containing autophagosome-like vacuoles (GcAVs). The autophagosome marker GFP-LC3 associates with GcAVs, and other components of the autophagosomal pathway are involved in GcAV formation. However, the mechanistic relationship between GcAV and canonical autophagy is largely unknown. Here, we morphologically analyzed GcAV formation in detail. Initially, a small, GFP-LC3-positive GcAV sequesters each streptococcal chain, and these then coalesce into a single, large GcAV. Expression of a dominant-negative form of Rab7 or RNAi-mediated knockdown of Rab7 prevented the initial formation of small GcAV structures. Our results demonstrate that mechanisms of GcAV formation includes not only the common machinery of autophagy, but also Rab7 as an additional component, which is dispensable in canonical autophagosome formation.

【 授权许可】

CC BY