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Chen J, Zhao H, Liu M, Chen L. A new perspective on the autophagic and non-autophagic functions of the GABARAP protein family: a potential therapeutic target for human diseases. Mol Cell Biochem 2024; 479:1415-1441. [PMID: 37440122 DOI: 10.1007/s11010-023-04800-5] [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: 03/16/2023] [Accepted: 06/24/2023] [Indexed: 07/14/2023]
Abstract
Mammalian autophagy-related protein Atg8, including the LC3 subfamily and GABARAP subfamily. Atg8 proteins play a vital role in autophagy initiation, autophagosome formation and transport, and autophagy-lysosome fusion. GABARAP subfamily proteins (GABARAPs) share a high degree of homology with LC3 family proteins, and their unique roles are often overlooked. GABARAPs are as indispensable as LC3 in autophagy. Deletion of GABARAPs fails autophagy flux induction and autophagy lysosomal fusion, which leads to the failure of autophagy. GABARAPs are also involved in the transport of selective autophagy receptors. They are engaged in various particular autophagy processes, including mitochondrial autophagy, endoplasmic reticulum autophagy, Golgi autophagy, centrosome autophagy, and dorphagy. Furthermore, GABARAPs are closely related to the transport and delivery of the inhibitory neurotransmitter γ-GABAA and the angiotensin II AT1 receptor (AT1R), tumor growth, metastasis, and prognosis. GABARAPs also have been confirmed to be involved in various diseases, such as cancer, cardiovascular disease, and neurodegenerative diseases. In order to better understand the role and therapeutic potential of GABARAPs, this article comprehensively reviews the autophagic and non-autophagic functions of GABARAPs, as well as the research progress of the role and mechanism of GABARAPs in cancer, cardiovascular diseases and neurodegenerative diseases. It emphasizes the significance of GABARAPs in the clinical prevention and treatment of diseases, and may provide new therapeutic ideas and targets for human diseases. GABARAP and GABARAPL1 in the serum of cancer patients are positively correlated with the prognosis of patients, which can be used as a clinical biomarker, predictor and potential therapeutic target.
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Affiliation(s)
- Jiawei Chen
- Central Laboratory of Yan'nan Hospital Affiliated to Kunming, Medical University, Key Laboratory of Cardiovascular Diseases of Yunnan Province, Key Laboratory of Tumor Immunological Prevention and Treatment of Yunnan Province, No. 245, Renmin East Road, Kunming, 650000, Yunnan, China
- Institute of Pharmacy and Pharmacology, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical School, University of South China, Hengyang, 421001, Hunan, China
| | - Hong Zhao
- Central Laboratory of Yan'nan Hospital Affiliated to Kunming, Medical University, Key Laboratory of Cardiovascular Diseases of Yunnan Province, Key Laboratory of Tumor Immunological Prevention and Treatment of Yunnan Province, No. 245, Renmin East Road, Kunming, 650000, Yunnan, China
- Institute of Pharmacy and Pharmacology, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical School, University of South China, Hengyang, 421001, Hunan, China
- School of Nursing, Hengyang Medical School, University of South China, Hengyang, 421001, Hunan, China
| | - Meiqing Liu
- Central Laboratory of Yan'nan Hospital Affiliated to Kunming, Medical University, Key Laboratory of Cardiovascular Diseases of Yunnan Province, Key Laboratory of Tumor Immunological Prevention and Treatment of Yunnan Province, No. 245, Renmin East Road, Kunming, 650000, Yunnan, China.
| | - Linxi Chen
- Institute of Pharmacy and Pharmacology, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical School, University of South China, Hengyang, 421001, Hunan, China.
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2
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Angert I, Karuka SR, Mansky LM, Mueller JD. Partitioning of ribonucleoprotein complexes from the cellular actin cortex. SCIENCE ADVANCES 2022; 8:eabj3236. [PMID: 35984883 PMCID: PMC9390997 DOI: 10.1126/sciadv.abj3236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 07/08/2022] [Indexed: 06/15/2023]
Abstract
The cell cortex plays a crucial role in cell mechanics, signaling, and development. However, little is known about the influence of the cortical meshwork on the spatial distribution of cytoplasmic biomolecules. Here, we describe a fluorescence microscopy method with the capacity to infer the intracellular distribution of labeled biomolecules with subresolution accuracy. Unexpectedly, we find that RNA binding proteins are partially excluded from the cytoplasmic volume adjacent to the plasma membrane that corresponds to the actin cortex. Complementary diffusion measurements of RNA-protein complexes suggest that a rudimentary model based on excluded volume interactions can explain this partitioning effect. Our results suggest the actin cortex meshwork may play a role in regulating the biomolecular content of the volume immediately adjacent to the plasma membrane.
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Affiliation(s)
- Isaac Angert
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
- Institute of Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA
- Division of Basic Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Siddarth Reddy Karuka
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
| | - Louis M. Mansky
- Institute of Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA
- Division of Basic Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Joachim D. Mueller
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
- Institute of Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
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3
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Sun HQ, Chen Y, Hedde PN, Mueller J, Albanesi JP, Yin H. PI4P-Dependent Targeting of ATG14 to Mature Autophagosomes. Biochemistry 2022; 61:722-729. [PMID: 35380781 DOI: 10.1021/acs.biochem.1c00775] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Degradation of autophagosomal cargo requires the tethering and fusion of autophagosomes with lysosomes that is mediated by the scaffolding protein autophagy related 14 (ATG14). Here, we report that phosphatidylinositol 4-kinase 2A (PI4K2A) generates a pool of phosphatidylinositol 4-phosphate (PI4P) that facilitates the recruitment of ATG14 to mature autophagosomes. We also show that PI4K2A binds to ATG14, suggesting that PI4P may be synthesized in situ in the vicinity of ATG14. Impaired targeting of ATG14 to autophagosomes in PI4K2A-depleted cells is rescued by the introduction of PI4P but not its downstream product phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). Thus, PI4P and PI(4,5)P2 have independent functions in late-stage autophagy. These results provide a mechanism to explain prior studies indicating that PI4K2A and its product PI4P are necessary for autophagosome-lysosome fusion.
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Affiliation(s)
- Hui-Qiao Sun
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
| | - Yan Chen
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Per Niklas Hedde
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii 96813, United States.,Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California 92697, United States
| | - Joachim Mueller
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Joseph P Albanesi
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
| | - Helen Yin
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
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Jacquet M, Hervouet E, Baudu T, Herfs M, Parratte C, Feugeas JP, Perez V, Reynders C, Ancion M, Vigneron M, Baguet A, Guittaut M, Fraichard A, Despouy G. GABARAPL1 Inhibits EMT Signaling through SMAD-Tageted Negative Feedback. BIOLOGY 2021; 10:biology10100956. [PMID: 34681055 PMCID: PMC8533302 DOI: 10.3390/biology10100956] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 09/10/2021] [Accepted: 09/14/2021] [Indexed: 12/03/2022]
Abstract
Simple Summary Epithelial–mesenchymal transition (EMT) is involved in metastasis formation, chemoresistance, apoptosis resistance, and acquisition of stem cell properties, making this process an attractive target in cancer. However, direct targeting of EMT remains challenging. Autophagy—an intracellular mechanism—has been noted to be involved in the regulation of EMT—mainly by its involvement in the degradation of EMT actors, explaining why understanding of how autophagy could regulate EMT might be promising in the development of new cancer therapies. Here, we found that GABARAPL1—an autophagy-related gene—was increased in human NSCLC mesenchymal tumors compared to epithelial tumors, and induction of EMT in an A549 lung cancer cell line by TGF-β/TNF-α cytokines also led to an increase in GABARAPL1 expression. This regulation could involve the EMT-related transcription factors of the SMAD family. To understand the role of GABARAPL1 in EMT regulation in lung cancer cells, A549 KO GABARAPL1 were designed and used to investigate whether GABARAPL1 could inhibit EMT via its involvement in SMAD degradation. The results indicate that GABARAPL1-mediated autophagic degradation could intervene as a negative EMT-regulatory loop. Abstract The pathway of selective autophagy, leading to a targeted elimination of specific intracellular components, is mediated by the ATG8 proteins, and has been previously suggested to be involved in the regulation of the Epithelial–mesenchymal transition (EMT) during cancer’s etiology. However, the molecular factors and steps of selective autophagy occurring during EMT remain unclear. We therefore analyzed a cohort of lung adenocarcinoma tumors using transcriptome analysis and immunohistochemistry, and found that the expression of ATG8 genes is correlated with that of EMT-related genes, and that GABARAPL1 protein levels are increased in EMT+ tumors compared to EMT- ones. Similarly, the induction of EMT in the A549 lung adenocarcinoma cell line using TGF-β/TNF-α led to a high increase in GABARAPL1 expression mediated by the EMT-related transcription factors of the SMAD family, whereas the other ATG8 genes were less modified. To determine the role of GABARAPL1 during EMT, we used the CRISPR/Cas9 technology in A549 and ACHN kidney adenocarcinoma cell lines to deplete GABARAPL1. We then observed that GABARAPL1 knockout induced EMT linked to a defect of GABARAPL1-mediated degradation of the SMAD proteins. These findings suggest that, during EMT, GABARAPL1 might intervene in an EMT-regulatory loop. Indeed, induction of EMT led to an increase in GABARAPL1 levels through the activation of the SMAD signaling pathway, and then GABARAPL1 induced the autophagy-selective degradation of SMAD proteins, leading to EMT inhibition.
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Affiliation(s)
- Marine Jacquet
- Université Bourgogne Franche-Comté, INSERM, EFS BFC, UMR1098, Interactions Hôte-Greffon-Tumeur/Ingénierie Cellulaire et Génique, F-25000 Besançon, France; (M.J.); (E.H.); (T.B.); (C.P.); (J.-P.F.); (V.P.); (A.B.); (M.G.); (A.F.)
| | - Eric Hervouet
- Université Bourgogne Franche-Comté, INSERM, EFS BFC, UMR1098, Interactions Hôte-Greffon-Tumeur/Ingénierie Cellulaire et Génique, F-25000 Besançon, France; (M.J.); (E.H.); (T.B.); (C.P.); (J.-P.F.); (V.P.); (A.B.); (M.G.); (A.F.)
- DImaCellplatform, Université Bourgogne Franche-Comté, F-25000 Besançon, France
- EPIGENExp, Université Bourgogne Franche-Comté, F-25000 Besançon, France
| | - Timothée Baudu
- Université Bourgogne Franche-Comté, INSERM, EFS BFC, UMR1098, Interactions Hôte-Greffon-Tumeur/Ingénierie Cellulaire et Génique, F-25000 Besançon, France; (M.J.); (E.H.); (T.B.); (C.P.); (J.-P.F.); (V.P.); (A.B.); (M.G.); (A.F.)
| | - Michaël Herfs
- Laboratory of Experimental Pathology, GIGA-Cancer, University of Liege, 4000 Liege, Belgium; (M.H.); (C.R.); (M.A.)
| | - Chloé Parratte
- Université Bourgogne Franche-Comté, INSERM, EFS BFC, UMR1098, Interactions Hôte-Greffon-Tumeur/Ingénierie Cellulaire et Génique, F-25000 Besançon, France; (M.J.); (E.H.); (T.B.); (C.P.); (J.-P.F.); (V.P.); (A.B.); (M.G.); (A.F.)
| | - Jean-Paul Feugeas
- Université Bourgogne Franche-Comté, INSERM, EFS BFC, UMR1098, Interactions Hôte-Greffon-Tumeur/Ingénierie Cellulaire et Génique, F-25000 Besançon, France; (M.J.); (E.H.); (T.B.); (C.P.); (J.-P.F.); (V.P.); (A.B.); (M.G.); (A.F.)
| | - Valérie Perez
- Université Bourgogne Franche-Comté, INSERM, EFS BFC, UMR1098, Interactions Hôte-Greffon-Tumeur/Ingénierie Cellulaire et Génique, F-25000 Besançon, France; (M.J.); (E.H.); (T.B.); (C.P.); (J.-P.F.); (V.P.); (A.B.); (M.G.); (A.F.)
| | - Célia Reynders
- Laboratory of Experimental Pathology, GIGA-Cancer, University of Liege, 4000 Liege, Belgium; (M.H.); (C.R.); (M.A.)
| | - Marie Ancion
- Laboratory of Experimental Pathology, GIGA-Cancer, University of Liege, 4000 Liege, Belgium; (M.H.); (C.R.); (M.A.)
| | - Marc Vigneron
- Team Replisome Dynamics and Cancer, UMR7242 Biotechnologie et Signalisation Cellulaire, Ecole Supérieure de Biotechnologie de Strasbourg, CNRS-Université de Strasbourg, F-67412 Illkirch, France;
| | - Aurélie Baguet
- Université Bourgogne Franche-Comté, INSERM, EFS BFC, UMR1098, Interactions Hôte-Greffon-Tumeur/Ingénierie Cellulaire et Génique, F-25000 Besançon, France; (M.J.); (E.H.); (T.B.); (C.P.); (J.-P.F.); (V.P.); (A.B.); (M.G.); (A.F.)
| | - Michaël Guittaut
- Université Bourgogne Franche-Comté, INSERM, EFS BFC, UMR1098, Interactions Hôte-Greffon-Tumeur/Ingénierie Cellulaire et Génique, F-25000 Besançon, France; (M.J.); (E.H.); (T.B.); (C.P.); (J.-P.F.); (V.P.); (A.B.); (M.G.); (A.F.)
- DImaCellplatform, Université Bourgogne Franche-Comté, F-25000 Besançon, France
| | - Annick Fraichard
- Université Bourgogne Franche-Comté, INSERM, EFS BFC, UMR1098, Interactions Hôte-Greffon-Tumeur/Ingénierie Cellulaire et Génique, F-25000 Besançon, France; (M.J.); (E.H.); (T.B.); (C.P.); (J.-P.F.); (V.P.); (A.B.); (M.G.); (A.F.)
| | - Gilles Despouy
- Université Bourgogne Franche-Comté, INSERM, EFS BFC, UMR1098, Interactions Hôte-Greffon-Tumeur/Ingénierie Cellulaire et Génique, F-25000 Besançon, France; (M.J.); (E.H.); (T.B.); (C.P.); (J.-P.F.); (V.P.); (A.B.); (M.G.); (A.F.)
- Correspondence:
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Liu K, Kong L, Graham DB, Carey KL, Xavier RJ. SAC1 regulates autophagosomal phosphatidylinositol-4-phosphate for xenophagy-directed bacterial clearance. Cell Rep 2021; 36:109434. [PMID: 34320354 PMCID: PMC8327279 DOI: 10.1016/j.celrep.2021.109434] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 12/21/2020] [Accepted: 07/01/2021] [Indexed: 02/07/2023] Open
Abstract
Phosphoinositides are important molecules in lipid signaling, membrane identity, and trafficking that are spatiotemporally controlled by factors from both mammalian cells and intracellular pathogens. Here, using small interfering RNA (siRNA) directed against phosphoinositide kinases and phosphatases, we screen for regulators of the host innate defense response to intracellular bacterial replication. We identify SAC1, a transmembrane phosphoinositide phosphatase, as an essential regulator of xenophagy. Depletion or inactivation of SAC1 compromises fusion between Salmonella-containing autophagosomes and lysosomes, leading to increased bacterial replication. Mechanistically, the loss of SAC1 results in aberrant accumulation of phosphatidylinositol-4-phosphate [PI(4)P] on Salmonella-containing autophagosomes, thus facilitating recruitment of SteA, a PI(4)P-binding Salmonella effector protein, which impedes lysosomal fusion. Replication of Salmonella lacking SteA is suppressed by SAC-1-deficient cells, however, demonstrating bacterial adaptation to xenophagy. Our findings uncover a paradigm in which a host protein regulates the level of its substrate and impairs the function of a bacterial effector during xenophagy.
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Affiliation(s)
- Kai Liu
- Center for Computational and Integrative Biology, Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Lingjia Kong
- Center for Computational and Integrative Biology, Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Daniel B Graham
- Center for Computational and Integrative Biology, Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Center for the Study of Inflammatory Bowel Disease, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Klarman Cell Observatory, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | | | - Ramnik J Xavier
- Center for Computational and Integrative Biology, Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Center for the Study of Inflammatory Bowel Disease, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Klarman Cell Observatory, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
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De Tito S, Hervás JH, van Vliet AR, Tooze SA. The Golgi as an Assembly Line to the Autophagosome. Trends Biochem Sci 2020; 45:484-496. [PMID: 32307224 DOI: 10.1016/j.tibs.2020.03.010] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 03/05/2020] [Accepted: 03/17/2020] [Indexed: 12/11/2022]
Abstract
Autophagy is traditionally depicted as a signaling cascade that culminates in the formation of an autophagosome that degrades cellular cargo. However, recent studies have identified myriad pathways and cellular organelles underlying the autophagy process, be it as signaling platforms or through the contribution of proteins and lipids. The Golgi complex is recognized as being a central transport hub in the cell, with a critical role in endocytic trafficking and endoplasmic reticulum (ER) to plasma membrane (PM) transport. However, the Golgi is also an important site of key autophagy regulators, including the protein autophagy-related (ATG)-9A and the lipid, phosphatidylinositol-4-phosphate [PI(4)P]. In this review, we highlight the central function of this organelle in autophagy as a transport hub supplying various components of autophagosome formation.
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Affiliation(s)
- Stefano De Tito
- The Molecular Cell Biology of Autophagy, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Javier H Hervás
- The Molecular Cell Biology of Autophagy, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Instituto Biofisika (CSIC, UPV/EHU), Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, Bilbao, Spain
| | - Alexander R van Vliet
- The Molecular Cell Biology of Autophagy, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Sharon A Tooze
- The Molecular Cell Biology of Autophagy, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.
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The Great Escape: how phosphatidylinositol 4-kinases and PI4P promote vesicle exit from the Golgi (and drive cancer). Biochem J 2019; 476:2321-2346. [DOI: 10.1042/bcj20180622] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 08/06/2019] [Accepted: 08/12/2019] [Indexed: 12/13/2022]
Abstract
Abstract
Phosphatidylinositol 4-phosphate (PI4P) is a membrane glycerophospholipid and a major regulator of the characteristic appearance of the Golgi complex as well as its vesicular trafficking, signalling and metabolic functions. Phosphatidylinositol 4-kinases, and in particular the PI4KIIIβ isoform, act in concert with PI4P to recruit macromolecular complexes to initiate the biogenesis of trafficking vesicles for several Golgi exit routes. Dysregulation of Golgi PI4P metabolism and the PI4P protein interactome features in many cancers and is often associated with tumour progression and a poor prognosis. Increased expression of PI4P-binding proteins, such as GOLPH3 or PITPNC1, induces a malignant secretory phenotype and the release of proteins that can remodel the extracellular matrix, promote angiogenesis and enhance cell motility. Aberrant Golgi PI4P metabolism can also result in the impaired post-translational modification of proteins required for focal adhesion formation and cell–matrix interactions, thereby potentiating the development of aggressive metastatic and invasive tumours. Altered expression of the Golgi-targeted PI 4-kinases, PI4KIIIβ, PI4KIIα and PI4KIIβ, or the PI4P phosphate Sac1, can also modulate oncogenic signalling through effects on TGN-endosomal trafficking. A Golgi trafficking role for a PIP 5-kinase has been recently described, which indicates that PI4P is not the only functionally important phosphoinositide at this subcellular location. This review charts new developments in our understanding of phosphatidylinositol 4-kinase function at the Golgi and how PI4P-dependent trafficking can be deregulated in malignant disease.
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Baba T, Toth DJ, Sengupta N, Kim YJ, Balla T. Phosphatidylinositol 4,5-bisphosphate controls Rab7 and PLEKHM1 membrane cycling during autophagosome-lysosome fusion. EMBO J 2019; 38:e100312. [PMID: 31368593 PMCID: PMC6463214 DOI: 10.15252/embj.2018100312] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 01/02/2019] [Accepted: 01/23/2019] [Indexed: 12/12/2022] Open
Abstract
The small GTPase Rab7 is a key organizer of receptor sorting and lysosomal degradation by recruiting of a variety of effectors depending on its GDP/GTP-bound state. However, molecular mechanisms that trigger Rab7 inactivation remain elusive. Here we find that, among the endosomal pools, Rab7-positive compartments possess the highest level of PI4P, which is primarily produced by PI4K2A kinase. Acute conversion of this endosomal PI4P to PI(4,5)P2 causes Rab7 dissociation from late endosomes and releases a regulator of autophagosome-lysosome fusion, PLEKHM1, from the membrane. Rab7 effectors Vps35 and RILP are not affected by acute PI(4,5)P2 production. Deletion of PI4K2A greatly reduces PIP5Kγ-mediated PI(4,5)P2 production in Rab7-positive endosomes leading to impaired Rab7 inactivation and increased number of LC3-positive structures with defective autophagosome-lysosome fusion. These results reveal a late endosomal PI4P-PI(4,5)P2 -dependent regulatory loop that impacts autophagosome flux by affecting Rab7 cycling and PLEKHM1 association.
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Affiliation(s)
- Takashi Baba
- Section on Molecular Signal TransductionProgram for Developmental NeuroscienceEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMDUSA
| | - Daniel J Toth
- Section on Molecular Signal TransductionProgram for Developmental NeuroscienceEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMDUSA
| | - Nivedita Sengupta
- Section on Molecular Signal TransductionProgram for Developmental NeuroscienceEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMDUSA
| | - Yeun Ju Kim
- Section on Molecular Signal TransductionProgram for Developmental NeuroscienceEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMDUSA
| | - Tamas Balla
- Section on Molecular Signal TransductionProgram for Developmental NeuroscienceEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMDUSA
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