A Vps21 endocytic module regulates autophagy.
Bottom Line: These GTPases function in modules that include guanine-nucleotide exchange factor (GEF) activators and downstream effectors.We propose that the endocytic Vps21 module also regulates autophagy.These findings support the idea that the two pathways leading to the lysosome--endocytosis and autophagy--converge through the Vps21 and Ypt7 GTPase modules.
Affiliation: College of Life Sciences, Key Laboratory of Agricultural Environmental Microbiology of Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.Show MeSH
Related in: MedlinePlus
Mentions: Vps9 is the GEF that activates Vps21 in endocytosis (Hama et al., 1999). To determine whether Vps9 also activates Vps21 in autophagy, we first determined whether vps9∆ mutant cells exhibit defects in autophagy. Assays described earlier showed that vps9∆ mutant cells exhibit defects in selective and nonselective autophagy similar to those observed for vps21∆ mutant cells (Figure 5, A–C, and Supplemental Figure S5, B and C). Moreover, fluorescence and electron microscopy analyses show that, like vps21∆ mutant cells, ∼40% of the vps9∆ mutant cells contain APCs outside their vacuoles under starvation (Figures 6A and 4, C and D, respectively). Remarkably, the autophagic defects displayed by vps9∆ mutant cells are very similar to those of vps21∆ mutant cells.
Affiliation: College of Life Sciences, Key Laboratory of Agricultural Environmental Microbiology of Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.