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Shinoda S, Sakai Y, Matsui T, Uematsu M, Koyama-Honda I, Sakamaki JI, Yamamoto H, Mizushima N. Syntaxin 17 recruitment to mature autophagosomes is temporally regulated by PI4P accumulation. eLife 2024; 12:RP92189. [PMID: 38831696 DOI: 10.7554/elife.92189] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2024] Open
Abstract
During macroautophagy, cytoplasmic constituents are engulfed by autophagosomes. Lysosomes fuse with closed autophagosomes but not with unclosed intermediate structures. This is achieved in part by the late recruitment of the autophagosomal SNARE syntaxin 17 (STX17) to mature autophagosomes. However, how STX17 recognizes autophagosome maturation is not known. Here, we show that this temporally regulated recruitment of STX17 depends on the positively charged C-terminal region of STX17. Consistent with this finding, mature autophagosomes are more negatively charged compared with unclosed intermediate structures. This electrostatic maturation of autophagosomes is likely driven by the accumulation of phosphatidylinositol 4-phosphate (PI4P) in the autophagosomal membrane. Accordingly, dephosphorylation of autophagosomal PI4P prevents the association of STX17 to autophagosomes. Furthermore, molecular dynamics simulations support PI4P-dependent membrane insertion of the transmembrane helices of STX17. Based on these findings, we propose a model in which STX17 recruitment to mature autophagosomes is temporally regulated by a PI4P-driven change in the surface charge of autophagosomes.
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Affiliation(s)
- Saori Shinoda
- Department of Biochemistry and Molecular Biology, Graduated School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Yuji Sakai
- Department of Biochemistry and Molecular Biology, Graduated School of Medicine, The University of Tokyo, Tokyo, Japan
- Department of Biosystems Science, Institute for Life and Medical Sciences, Kyoto University, Kyoto, Japan
| | - Takahide Matsui
- Department of Molecular Oncology, Institute for Advanced Medical Sciences, Nippon Medical School, Tokyo, Japan
| | - Masaaki Uematsu
- Department of Biochemistry and Molecular Biology, Graduated School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Ikuko Koyama-Honda
- Department of Biochemistry and Molecular Biology, Graduated School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Jun-Ichi Sakamaki
- Department of Biochemistry and Molecular Biology, Graduated School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hayashi Yamamoto
- Department of Biochemistry and Molecular Biology, Graduated School of Medicine, The University of Tokyo, Tokyo, Japan
- Department of Molecular Oncology, Institute for Advanced Medical Sciences, Nippon Medical School, Tokyo, Japan
| | - Noboru Mizushima
- Department of Biochemistry and Molecular Biology, Graduated School of Medicine, The University of Tokyo, Tokyo, Japan
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Tian Z, Diao J. A matter of timing. eLife 2024; 13:e99181. [PMID: 38831693 PMCID: PMC11149926 DOI: 10.7554/elife.99181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2024] Open
Abstract
A change in the electric charge of autophagosome membranes controls the recruitment of SNARE proteins to ensure that membrane fusion occurs at the right time during autophagy.
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Affiliation(s)
- Zhiqi Tian
- Department of Cancer Biology, University of Cincinnati College of MedicineCincinnatiUnited States
| | - Jiajie Diao
- Department of Cancer Biology, University of Cincinnati College of MedicineCincinnatiUnited States
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3
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Xu Y, Duan S, Ye W, Zheng Z, Zhang J, Gao Y, Ye S. SLC34A2 promotes cell proliferation by activating STX17-mediated autophagy in esophageal squamous cell carcinoma. Thorac Cancer 2024; 15:1369-1384. [PMID: 38720472 PMCID: PMC11168907 DOI: 10.1111/1759-7714.15314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 03/26/2024] [Accepted: 04/04/2024] [Indexed: 06/14/2024] Open
Abstract
BACKGROUND Solute carrier family 34 member 2 (SLC34A2) has been implicated in the development of various malignancies. However, the clinical significance and underlying molecular mechanisms of SLC34A2 in esophageal squamous cell carcinoma (ESCC) remain elusive. METHODS Western blotting, quantitative real-time PCR and immunohistochemistry were utilized to evaluate the expression levels of SLC34A2 mRNA/protein in ESCC cell lines or tissues. Kaplan-Meier curves were employed for survival analysis. CCK-8, colony formation, EdU and xenograft tumor model assays were conducted to determine the impact of SLC34A2 on ESCC cell proliferation. Cell cycle was examined using flow cytometry. RNA-sequencing and enrichment analysis were carried out to explore the potential signaling pathways. The autophagic flux was evaluated by western blotting, mRFP-GFP-LC3 reporter system and transmission electron microscopy. Immunoprecipitation and mass spectrometry were utilized for identification of potential SLC34A2-interacting proteins. Cycloheximide (CHX) chase and ubiquitination assays were conducted to test the protein stability. RESULTS The expression of SLC34A2 was significantly upregulated in ESCC and correlated with unfavorable clinicopathologic characteristics particularly the Ki-67 labeling index and poor prognosis of ESCC patients. Overexpression of SLC34A2 promoted ESCC cell proliferation, while silencing SLC34A2 had the opposite effect. Moreover, SLC34A2 induced autophagy to promote ESCC cell proliferation, whereas inhibition of autophagy suppressed the proliferation of ESCC cells. Further studies showed that SLC34A2 interacted with an autophagy-related protein STX17 to promote autophagy and proliferation of ESCC cells by inhibiting the ubiquitination and degradation of STX17. CONCLUSIONS These findings indicate that SLC34A2 may serve as a prognostic biomarker for ESCC.
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Affiliation(s)
- Yi Xu
- Department of Oncology, The First Affiliated HospitalSun Yat‐Sen UniversityGuangzhouChina
| | - Shiyu Duan
- Department of Pathology, Guangdong Provincial People's HospitalGuangdong Academy of Medical SciencesGuangzhouChina
| | - Wen Ye
- Department of Oncology, The First Affiliated HospitalSun Yat‐Sen UniversityGuangzhouChina
| | - Zhousan Zheng
- Department of Oncology, The First Affiliated HospitalSun Yat‐Sen UniversityGuangzhouChina
| | - Jiaxing Zhang
- Department of Oncology, The First Affiliated HospitalSun Yat‐Sen UniversityGuangzhouChina
| | - Ying Gao
- Department of Radiation Oncology, The First Affiliated HospitalSun Yat‐Sen UniversityGuangzhouChina
| | - Sheng Ye
- Department of Oncology, The First Affiliated HospitalSun Yat‐Sen UniversityGuangzhouChina
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4
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Zhu P, Li J, Yan F, Islam S, Lin X, Xu X. Allelic heterogeneity of TTNtv dilated cardiomyopathy can be modeled in adult zebrafish. JCI Insight 2024; 9:e175501. [PMID: 38412038 PMCID: PMC11128207 DOI: 10.1172/jci.insight.175501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 02/21/2024] [Indexed: 02/29/2024] Open
Abstract
Allelic heterogeneity (AH) has been noted in truncational TTN-associated (TTNtv-associated) dilated cardiomyopathy (DCM); i.e., mutations affecting A-band-encoding exons are pathogenic, but those affecting Z-disc-encoding exons are likely benign. The lack of an in vivo animal model that recapitulates AH hinders the deciphering of the underlying mechanism. Here, we explored zebrafish as a candidate vertebrate model by phenotyping a collection of zebrafish ttntv alleles. We noted that cardiac function and sarcomere structure were more severely disrupted in ttntv-A than in ttntv-Z homozygous embryos. Consistently, cardiomyopathy-like phenotypes were present in ttntv-A but not ttntv-Z adult heterozygous mutants. The phenotypes observed in ttntv-A alleles were recapitulated in null mutants with the full titin-encoding sequences removed. Defective autophagic flux, largely due to impaired autophagosome-lysosome fusion, was also noted only in ttntv-A but not in ttntv-Z models. Moreover, we found that genetic manipulation of ulk1a restored autophagy flux and rescued cardiac dysfunction in ttntv-A animals. Together, our findings presented adult zebrafish as an in vivo animal model for studying AH in TTNtv DCM, demonstrated TTN loss of function is sufficient to trigger ttntv DCM in zebrafish, and uncovered ulk1a as a potential therapeutic target gene for TTNtv DCM.
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Affiliation(s)
- Ping Zhu
- Department of Biochemistry and Molecular Biology and
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Jiarong Li
- Department of Biochemistry and Molecular Biology and
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, USA
- Department of Cardiovascular Surgery, Second Xiangya Hospital, Central South University, Changsha, China
| | - Feixiang Yan
- Department of Biochemistry and Molecular Biology and
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Shahidul Islam
- Department of Biochemistry and Molecular Biology and
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Xueying Lin
- Department of Biochemistry and Molecular Biology and
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Xiaolei Xu
- Department of Biochemistry and Molecular Biology and
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, USA
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Jian F, Wang S, Tian R, Wang Y, Li C, Li Y, Wang S, Fang C, Ma C, Rong Y. The STX17-SNAP47-VAMP7/VAMP8 complex is the default SNARE complex mediating autophagosome-lysosome fusion. Cell Res 2024; 34:151-168. [PMID: 38182888 PMCID: PMC10837459 DOI: 10.1038/s41422-023-00916-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 12/11/2023] [Indexed: 01/07/2024] Open
Abstract
Autophagosome-lysosome fusion mediated by SNARE complexes is an essential step in autophagy. Two SNAP29-containing SNARE complexes have been extensively studied in starvation-induced bulk autophagy, while the relevant SNARE complexes in other types of autophagy occurring under non-starvation conditions have been overlooked. Here, we found that autophagosome-lysosome fusion in selective autophagy under non-starvation conditions does not require SNAP29-containing SNARE complexes, but requires the STX17-SNAP47-VAMP7/VAMP8 SNARE complex. Further, the STX17-SNAP47-VAMP7/VAMP8 SNARE complex also functions in starvation-induced autophagy. SNAP47 is recruited to autophagosomes following concurrent detection of ATG8s and PI(4,5)P2 via its Pleckstrin homology domain. By contrast, SNAP29-containing SNAREs are excluded from selective autophagy due to inactivation by O-GlcNAcylation under non-starvation conditions. These findings depict a previously unknown, default SNARE complex responsible for autophagosome-lysosome fusion in both selective and bulk autophagy, which could guide research and therapeutic development in autophagy-related diseases.
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Affiliation(s)
- Fenglei Jian
- School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Shen Wang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Rui Tian
- School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Yufen Wang
- School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Chuangpeng Li
- School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Yan Li
- Department of Obstetrics and Gynecology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Shixuan Wang
- Department of Obstetrics and Gynecology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Chao Fang
- School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Cong Ma
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China.
| | - Yueguang Rong
- School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, Hubei, China.
- Cell Architecture Research Center, Huazhong University of Science and Technology, Wuhan, Hubei, China.
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