Autophagy requires Tip20 in Saccharomyces cerevisiae
- 138 Downloads
Autophagy is a highly conserved intracellular degradation pathway in eukaryotic cells that responds to environmental changes. Genetic analyses have shown that more than 40 autophagy-related genes (ATG) are directly involved in this process in fungi. In addition to Atg proteins, most vesicle transport regulators are also essential for each step of autophagy. The present study showed that one Endoplasmic Reticulum protein in Saccharomyces cerevisiae, Tip20, which controls Golgi-to-ER retrograde transport, was also required for starvation-induced autophagy under high temperature stress. In tip20 conditional mutant yeast, the transport of Atg8 was impaired during starvation, resulting in multiple Atg8 puncta dispersed outside the vacuole that could not be transported to the pre-autophagosomal structure/phagophore assembly site (PAS). Several Atg8 puncta were trapped in ER exit sites (ERES). Moreover, the GFP-Atg8 protease protection assay indicated that Tip20 functions before autophagosome closure. Furthermore, genetic studies showed that Tip20 functions downstream of Atg5 and upstream of Atg1, Atg9 and Atg14 in the autophagy pathway. The present data show that Tip20, as a vesicle transport regulator, has novel roles in autophagy.
KeywordsAutophagy Atg8 autophagosome biogenesis ERES Tip20
endoplasmic reticulum exit sites
green fluorescent protein
pre-autophagosomal structure/phagophore assembly site
red fluorescent protein.
We are grateful to H. Schmitt for providing WT, tip20-5 and dsl1-22 strains, J Nunnaria for providing DsRed-HDEL-305 plasmids, and Q Jin for providing pFA6a-tdTomato-KanMx plasmid. This work was supported by grants from the Natural Science Foundation of China (31301173 to SZ and 31101428 to LC) and Shandong Agricultural University Talent Introduction Funding (20171226 to HD).
- Meiringer CT, Rethmeier R, Auffarth K, Wilson J, Perz A, Barlowe C, Schmitt HD and Ungermann C 2011 The Dsl1 protein tethering complex is a resident endoplasmic reticulum complex, which interacts with five soluble NSF (N-ethylmaleimide-sensitive factor) attachment protein receptors (SNAREs): implications for fusion and fusion regulation. J. Biol. Chem. 286 25039–25046CrossRefGoogle Scholar
- Ravikumar B, Sarkar S, Davies JE, Futter M, Garcia-Arencibia M, Green-Thompson ZW, Jimenez-Sanchez M, Korolchuk VI, Lichtenberg M, Luo S, Massey DC, Menzies FM, Moreau K, Narayanan U, Renna M, Siddiqi FH, Underwood BR, Winslow AR and Rubinsztein DC 2010 Regulation of mammalian autophagy in physiology and pathophysiology. Physiol. Rev. 90 1383–1435CrossRefGoogle Scholar
- Zou S, Sun D and Liang Y 2017 The Roles of the SNARE protein Sed5 in autophagy in Saccharomyces cerevisiae. Mol. Cell. 40 643–654Google Scholar