ESCRT machinery plays a role in microautophagy in yeast
| Autor: | Most Naoshia Tasnin, Shamsul Morshed, Takashi Ushimaru |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
0301 basic medicine
AP-3 pathway Saccharomyces cerevisiae Proteins Endosome Green Fluorescent Proteins Mutant Endosomes Saccharomyces cerevisiae macromolecular substances ESCRT Green fluorescent protein 03 medical and health sciences 0302 clinical medicine Yeast Dried Vph1 lcsh:QH573-671 Microautophagy VPS pathway Protein kinase A Molecular Biology Endosomal Sorting Complexes Required for Transport lcsh:Cytology Chemistry Membrane Proteins Cell Biology Yeast Cell biology Protein Transport 030104 developmental biology Cytoplasm Saccharomycetales Vacuoles Lysosomes Pho8 030217 neurology & neurosurgery Research Article |
| Zdroj: | BMC Molecular and Cell Biology, Vol 21, Iss 1, Pp 1-10 (2020) BMC Molecular and Cell Biology |
| DOI: | 10.21203/rs.3.rs-19822/v4 |
| Popis: | Background Microautophagy, which degrades cargos by direct lysosomal/vacuolar engulfment of cytoplasmic cargos, is promoted after nutrient starvation and the inactivation of target of rapamycin complex 1 (TORC1) protein kinase. In budding yeast, microautophagy has been commonly assessed using processing assays with green fluorescent protein (GFP)-tagged vacuolar membrane proteins, such as Vph1 and Pho8. The endosomal sorting complex required for transport (ESCRT) system is proposed to be required for microautophagy, because degradation of vacuolar membrane protein Vph1 was compromised in ESCRT-defective mutants. However, ESCRT is also critical for the vacuolar sorting of most vacuolar proteins, and hence reexamination of the involvement of ESCRT in microautophagic processes is required. Results Here, we show that the Vph1-GFP processing assay is unsuitable for estimating the involvement of ESCRT in microautophagy, because Vph1-GFP accumulated highly in the prevacuolar class E compartment in ESCRT mutants. In contrast, GFP-Pho8 and Sna4-GFP destined for vacuolar membranes via an alternative adaptor protein-3 (AP-3) pathway, were properly localized on vacuolar membranes in ESCRT-deficient cells. Nevertheless, microautophagic degradation of GFP-Pho8 and Sna4-GFP after TORC1 inactivation was hindered in ESCRT mutants, indicating that ESCRT is indeed required for microautophagy after nutrient starvation and TORC1 inactivation. Conclusions These findings provide evidence for the direct role of ESCRT in microautophagy induction. |
| Databáze: | OpenAIRE |
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