ESCRT machinery plays a role in microautophagy in yeast
Abstract 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 usi...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
BMC
2020-10-01
|
| Series: | BMC Molecular and Cell Biology |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s12860-020-00314-w |
| _version_ | 1818216550598967296 |
|---|---|
| author | Shamsul Morshed Most Naoshia Tasnin Takashi Ushimaru |
| author_facet | Shamsul Morshed Most Naoshia Tasnin Takashi Ushimaru |
| author_sort | Shamsul Morshed |
| collection | DOAJ |
| description | Abstract 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. |
| first_indexed | 2024-12-12T06:53:45Z |
| format | Article |
| id | doaj.art-8ec4e64dc78a4bf4acb7aeb7edb86c8a |
| institution | Directory Open Access Journal |
| issn | 2661-8850 |
| language | English |
| last_indexed | 2024-12-12T06:53:45Z |
| publishDate | 2020-10-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Molecular and Cell Biology |
| spelling | doaj.art-8ec4e64dc78a4bf4acb7aeb7edb86c8a2022-12-22T00:34:01ZengBMCBMC Molecular and Cell Biology2661-88502020-10-0121111010.1186/s12860-020-00314-wESCRT machinery plays a role in microautophagy in yeastShamsul Morshed0Most Naoshia Tasnin1Takashi Ushimaru2Graduate School of Science and Technology, Shizuoka UniversityGraduate School of Science and Technology, Shizuoka UniversityGraduate School of Science and Technology, Shizuoka UniversityAbstract 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.http://link.springer.com/article/10.1186/s12860-020-00314-wAP-3 pathwayESCRTMicroautophagyPho8Vph1VPS pathway |
| spellingShingle | Shamsul Morshed Most Naoshia Tasnin Takashi Ushimaru ESCRT machinery plays a role in microautophagy in yeast BMC Molecular and Cell Biology AP-3 pathway ESCRT Microautophagy Pho8 Vph1 VPS pathway |
| title | ESCRT machinery plays a role in microautophagy in yeast |
| title_full | ESCRT machinery plays a role in microautophagy in yeast |
| title_fullStr | ESCRT machinery plays a role in microautophagy in yeast |
| title_full_unstemmed | ESCRT machinery plays a role in microautophagy in yeast |
| title_short | ESCRT machinery plays a role in microautophagy in yeast |
| title_sort | escrt machinery plays a role in microautophagy in yeast |
| topic | AP-3 pathway ESCRT Microautophagy Pho8 Vph1 VPS pathway |
| url | http://link.springer.com/article/10.1186/s12860-020-00314-w |
| work_keys_str_mv | AT shamsulmorshed escrtmachineryplaysaroleinmicroautophagyinyeast AT mostnaoshiatasnin escrtmachineryplaysaroleinmicroautophagyinyeast AT takashiushimaru escrtmachineryplaysaroleinmicroautophagyinyeast |