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Tasnin MN, Ito K, Katsuta H, Takuma T, Sharmin T, Ushimaru T. The PI3 Kinase Complex II-PI3P-Vps27 Axis on Vacuolar Membranes is Critical for Microautophagy Induction and Nutrient Stress Adaptation. J Mol Biol 2021; 434:167360. [PMID: 34798133 DOI: 10.1016/j.jmb.2021.167360] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 11/11/2021] [Accepted: 11/12/2021] [Indexed: 12/27/2022]
Abstract
Phosphatidylinositol 3-phosphate (PI3P), a scaffold of membrane-associated proteins required for diverse cellular events, is produced by Vps34-containing phosphatidylinositol 3-kinase (PI3K). PI3K complex I (PI3KCI)-generated PI3P is required for macroautophagy, whereas PI3K complex II (PI3KCII)-generated PI3P is required for endosomal sorting complex required for transport (ESCRT)-mediated multi-vesicular body (MVB) formation in late endosomes. ESCRT also promotes vacuolar membrane remodeling in microautophagy after nutrient starvation and inactivation of target of rapamycin complex 1 (TORC1) protein kinase in budding yeast. Whereas PI3KCI and macroautophagy are critical for the nutrient starvation response, the physiological roles of PI3KCII and microautophagy during starvation are largely unknown. Here, we showed that PI3KCII-produced PI3P on vacuolar membranes is required for microautophagy induction and survival in nutrient-stressed conditions. PI3KCII is required for Vps27 (an ESCRT-0 component) recruitment and ESCRT-0 complex formation on vacuolar surfaces after TORC1 inactivation. Forced recruitment of Vps27 onto vacuolar membranes rescued the defect in microautophagy induction in PI3KCII-deficient cells, indicating that a critical role of PI3P on microautophagy induction is Vps27 recruitment onto vacuolar surfaces. Finally, vacuolar membrane-associated Vps27 was able to recover survival during nutrient starvation in cells lacking PI3KCII or Vps27. This study revealed that the PI3KCII-PI3P-Vps27 axis on vacuolar membranes is critical for ESCRT-mediated microautophagy induction and nutrient stress adaptation.
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Affiliation(s)
- Most Naoshia Tasnin
- Graduate School of Science and Technology, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka 422-8021, Japan
| | - Kisara Ito
- Department of Bioscience, Faculty of Science, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka 422-8021, Japan
| | - Haruko Katsuta
- Course of Biological Science, Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka 422-8021, Japan
| | - Tsuneyuki Takuma
- Course of Biological Science, Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka 422-8021, Japan
| | - Tasnuva Sharmin
- Graduate School of Science and Technology, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka 422-8021, Japan
| | - Takashi Ushimaru
- Graduate School of Science and Technology, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka 422-8021, Japan; Department of Bioscience, Faculty of Science, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka 422-8021, Japan; Course of Biological Science, Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka 422-8021, Japan.
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