1
|
Hou P, Guo Y, Jin H, Sun J, Bai Y, Li W, Li L, Cao Z, Wu F, Zhang H, Li Y, Yang S, Xia X, Huang P, Wang H. Bif-1c Attenuates Viral Proliferation by Regulating Autophagic Flux Blockade Induced by the Rabies Virus CVS-11 Strain in N2a Cells. Microbiol Spectr 2023; 11:e0307922. [PMID: 37014208 PMCID: PMC10269655 DOI: 10.1128/spectrum.03079-22] [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] [Received: 08/06/2022] [Accepted: 03/09/2023] [Indexed: 04/05/2023] Open
Abstract
Bax-interacting factor-1 (Bif-1) is a multifunctional protein involved in apoptosis, autophagy, and mitochondrial morphology. However, the associations between Bif-1 and viruses are poorly understood. As discrete Bif-1 isoforms are selectively expressed and exert corresponding effects, we evaluated the effects of neuron-specific/ubiquitous Bif-1 isoforms on rabies virus (RABV) proliferation. First, infection with the RABV CVS-11 strain significantly altered Bif-1 expression in mouse neuroblastoma (N2a) cells, and Bif-1 knockdown in turn promoted RABV replication. Overexpression of neuron-specific Bif-1 isoforms (Bif-1b/c/e) suppressed RABV replication. Moreover, our study showed that Bif-1c colocalized with LC3 and partially alleviated the incomplete autophagic flux induced by RABV. Taken together, our data reveal that neuron-specific Bif-1 isoforms impair the RABV replication process by abolishing autophagosome accumulation and blocking autophagic flux induced by the RABV CVS-11 strain in N2a cells. IMPORTANCE Autophagy can be triggered by viral infection and replication. Autophagosomes are generated and affect RABV replication, which differs by viral strain and infected cell type. Bax-interacting factor-1 (Bif-1) mainly has a proapoptotic function but is also involved in autophagosome formation. However, the association between Bif-1-involved autophagy and RABV infection remains unclear. In this study, our data reveal that a neuron-specific Bif-1 isoform, Bif-1c, impaired viral replication by unchoking autophagosome accumulation induced by RABV in N2a cells to a certain extent. Our study reveals for the first time that Bif-1 is involved in modulating autophagic flux and plays a crucial role in RABV replication, establishing Bif-1 as a potential therapeutic target for rabies.
Collapse
Affiliation(s)
- Pengfei Hou
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
- Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Yidi Guo
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Hongli Jin
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
- Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Jingxuan Sun
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Yujie Bai
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Wujian Li
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
- Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Ling Li
- National Research Center for Exotic Animal Diseases, China Animal Health and Epidemiology Center, Qingdao, China
| | - Zengguo Cao
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
- Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Fangfang Wu
- Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Haili Zhang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Yuanyuan Li
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Songtao Yang
- Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Xianzhu Xia
- Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Pei Huang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Hualei Wang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| |
Collapse
|
2
|
Liu L, Tang Y, Zhou Z, Huang Y, Zhang R, Lyu H, Xiao S, Guo D, Ali DW, Michalak M, Chen XZ, Zhou C, Tang J. Membrane Curvature: The Inseparable Companion of Autophagy. Cells 2023; 12:1132. [PMID: 37190041 PMCID: PMC10136490 DOI: 10.3390/cells12081132] [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] [Received: 12/07/2022] [Revised: 04/06/2023] [Accepted: 04/10/2023] [Indexed: 05/17/2023] Open
Abstract
Autophagy is a highly conserved recycling process of eukaryotic cells that degrades protein aggregates or damaged organelles with the participation of autophagy-related proteins. Membrane bending is a key step in autophagosome membrane formation and nucleation. A variety of autophagy-related proteins (ATGs) are needed to sense and generate membrane curvature, which then complete the membrane remodeling process. The Atg1 complex, Atg2-Atg18 complex, Vps34 complex, Atg12-Atg5 conjugation system, Atg8-phosphatidylethanolamine conjugation system, and transmembrane protein Atg9 promote the production of autophagosomal membranes directly or indirectly through their specific structures to alter membrane curvature. There are three common mechanisms to explain the change in membrane curvature. For example, the BAR domain of Bif-1 senses and tethers Atg9 vesicles to change the membrane curvature of the isolation membrane (IM), and the Atg9 vesicles are reported as a source of the IM in the autophagy process. The amphiphilic helix of Bif-1 inserts directly into the phospholipid bilayer, causing membrane asymmetry, and thus changing the membrane curvature of the IM. Atg2 forms a pathway for lipid transport from the endoplasmic reticulum to the IM, and this pathway also contributes to the formation of the IM. In this review, we introduce the phenomena and causes of membrane curvature changes in the process of macroautophagy, and the mechanisms of ATGs in membrane curvature and autophagosome membrane formation.
Collapse
Affiliation(s)
- Lei Liu
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
- National “111” Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan 430068, China
| | - Yu Tang
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
- National “111” Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan 430068, China
| | - Zijuan Zhou
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
- National “111” Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan 430068, China
| | - Yuan Huang
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
| | - Rui Zhang
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
| | - Hao Lyu
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
| | - Shuai Xiao
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
| | - Dong Guo
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
| | - Declan William Ali
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Marek Michalak
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Xing-Zhen Chen
- Membrane Protein Disease Research Group, Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Cefan Zhou
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
| | - Jingfeng Tang
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan 430068, China
| |
Collapse
|
3
|
Abstract
Abstract
α-Synuclein is a small neuronal protein that reversibly associates with lipid membranes. The membrane interactions are believed to be central to the healthy function of this protein involved in synaptic plasticity and neurotransmitter release. α-Synuclein has been speculated to induce vesicle fusion as well as fission, processes which are analogous to each other but proceed in different directions and involve different driving forces. In the current work, we analyse α-synuclein-induced small unilamellar vesicle deformation from a thermodynamics point of view. We show that the structures interpreted in the literature as fusion intermediates are in fact a stable deformed state and neither fusion nor vesicle clustering occurs. We speculate on the driving force for the observed deformation and put forward a hypothesis that α-synuclein self-assembly on the lipid membrane precedes and induces membrane remodelling.
Collapse
|
4
|
Overlapping Role of SCYL1 and SCYL3 in Maintaining Motor Neuron Viability. J Neurosci 2018; 38:2615-2630. [PMID: 29437892 DOI: 10.1523/jneurosci.2282-17.2018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 12/23/2017] [Accepted: 01/31/2018] [Indexed: 11/21/2022] Open
Abstract
Members of the SCY1-like (SCYL) family of protein kinases are evolutionarily conserved and ubiquitously expressed proteins characterized by an N-terminal pseudokinase domain, centrally located Huntingtin, elongation factor 3, protein phosphatase 2A, yeast kinase TOR1 repeats, and an overall disorganized C-terminal segment. In mammals, three family members encoded by genes Scyl1, Scyl2, and Scyl3 have been described. Studies have pointed to a role for SCYL1 and SCYL2 in regulating neuronal function and viability in mice and humans, but little is known about the biological function of SCYL3. Here, we show that the biochemical and cell biological properties of SCYL3 are similar to those of SCYL1 and both proteins work in conjunction to maintain motor neuron viability. Specifically, although lack of Scyl3 in mice has no apparent effect on embryogenesis and postnatal life, it accelerates the onset of the motor neuron disorder caused by Scyl1 deficiency. Growth abnormalities, motor dysfunction, hindlimb paralysis, muscle wasting, neurogenic atrophy, motor neuron degeneration, and loss of large-caliber axons in peripheral nerves occurred at an earlier age in Scyl1/Scyl3 double-deficient mice than in Scyl1-deficient mice. Disease onset also correlated with the mislocalization of TDP-43 in spinal motor neurons, suggesting that SCYL1 and SCYL3 regulate TDP-43 proteostasis. Together, our results demonstrate an overlapping role for SCYL1 and SCYL3 in vivo and highlight the importance the SCYL family of proteins in regulating neuronal function and survival. Only male mice were used in this study.SIGNIFICANCE STATEMENT SCYL1 and SCYL2, members of the SCY1-like family of pseudokinases, have well established roles in neuronal function. Herein, we uncover the role of SCYL3 in maintaining motor neuron viability. Although targeted disruption of Scyl3 in mice had little or no effect on embryonic development and postnatal life, it accelerated disease onset associated with the loss of Scyl1, a novel motor neuron disease gene in humans. Scyl1 and Scyl3 double-deficient mice had neuronal defects characteristic of amyotrophic lateral sclerosis, including TDP-43 pathology, at an earlier age than did Scyl1-deficient mice. Thus, we show that SCYL1 and SCYL3 play overlapping roles in maintaining motor neuronal viability in vivo and confirm that SCYL family members are critical regulators of neuronal function and survival.
Collapse
|
5
|
Marcassa E, Raimondi M, Anwar T, Eskelinen EL, Myers MP, Triolo G, Schneider C, Demarchi F. Calpain mobilizes Atg9/Bif-1 vesicles from Golgi stacks upon autophagy induction by thapsigargin. Biol Open 2017; 6:551-562. [PMID: 28302665 PMCID: PMC5450315 DOI: 10.1242/bio.022806] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
CAPNS1 is essential for stability and function of the ubiquitous calcium-dependent proteases micro- and milli-calpain. Upon inhibition of the endoplasmic reticulum Ca2+ ATPase by 100 nM thapsigargin, both micro-calpain and autophagy are activated in human U2OS osteosarcoma cells in a CAPNS1-dependent manner. As reported for other autophagy triggers, thapsigargin treatment induces Golgi fragmentation and fusion of Atg9/Bif-1-containing vesicles with LC3 bodies in control cells. By contrast, CAPNS1 depletion is coupled with an accumulation of LC3 bodies and Rab5 early endosomes. Moreover, Atg9 and Bif-1 remain in the GM130-positive Golgi stacks and Atg9 fails to interact with the endocytic route marker transferrin receptor and with the core autophagic protein Vps34 in CAPNS1-depleted cells. Ectopic expression of a Bif-1 point mutant resistant to calpain processing is coupled to endogenous p62 and LC3-II accumulation. Altogether, these data indicate that calpain allows dynamic flux of Atg9/Bif-1 vesicles from the Golgi toward the budding autophagosome. Summary: ER stress triggers calpain-dependent Bif-1 activation and induction of autophagosome maturation by promoting ATG9/Bif-1 vesicle trafficking and fusion with LC3 bodies.
Collapse
Affiliation(s)
- Elena Marcassa
- C.I.B. National Laboratory, AREA Science Park, Padriciano 99, Trieste 34149, Italy
| | - Marzia Raimondi
- C.I.B. National Laboratory, AREA Science Park, Padriciano 99, Trieste 34149, Italy
| | - Tahira Anwar
- Department of Biosciences, University of Helsinki, PO Box 56, Helsinki 00014, Finland
| | - Eeva-Liisa Eskelinen
- Department of Biosciences, University of Helsinki, PO Box 56, Helsinki 00014, Finland
| | - Michael P Myers
- International Centre for Genetic Engineering and Biotechnology, AREA Science Park - Padriciano 99, Trieste 34149, Italy
| | - Gianluca Triolo
- International Centre for Genetic Engineering and Biotechnology, AREA Science Park - Padriciano 99, Trieste 34149, Italy
| | - Claudio Schneider
- C.I.B. National Laboratory, AREA Science Park, Padriciano 99, Trieste 34149, Italy
| | - Francesca Demarchi
- C.I.B. National Laboratory, AREA Science Park, Padriciano 99, Trieste 34149, Italy
| |
Collapse
|
6
|
Bhowmik T, Gomes A. NKCT1 (purified Naja kaouthia protein toxin) conjugated gold nanoparticles induced Akt/mTOR inactivation mediated autophagic and caspase 3 activated apoptotic cell death in leukemic cell. Toxicon 2016; 121:86-97. [PMID: 27527270 DOI: 10.1016/j.toxicon.2016.08.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Revised: 08/04/2016] [Accepted: 08/11/2016] [Indexed: 12/24/2022]
Abstract
BACKGROUND Gold nanoparticle (GNP) and snake venom protein toxin NKCT1 was conjugated as stated earlier (Bhowmik et al., 2013). The aim of this study was to explore the caspase dependent apoptotic pathway and autophagy inducing ability of gold nanoparticles tagged snake venom protein toxin NKCT1 (GNP-NKCT1) in human leukemic U937 and K562 cell line. METHODS GNP-NKCT1 induced apoptosis in U937 and K562 cell line were assessed through mitochondrial membrane potential assay, ROS generation assay, caspase 3 pathways and western blotting. GNP-NKCT1 induced autophagic pathway was detected through Akt, mTOR and PI3K expression by western blotting. Autophagic cell death also checked after addition of caspase 3 inhibitor and which also reconfirmed by western blotting of autophagic marker protein, lysosomal staining. RESULTS Loss of mitochondrial membrane potential was occurred in both the leukemic cell line after induction by GNP-NKCT1 and treatment of which also exhibited high ROS generation. Caspase 3 expression of cell was also increased. With caspase 3 inhibitor, GNP-NKCT1 downregulated PI3K/Akt and mTOR expression and thus undergoing autophagic cell death. Lysosomal staining confirmed lysosomal enzyme involvement in the autophagic response. Up regulation of Atg 3, Atg12, Beclin 1, LC3-II protein and BIF-1 and down regulation of Atg4B were also showed by blotting. CONCLUSION The results demonstrated that conjugation of Gold nanoparticles with NKCT1 could induce an alternate cell death pathway other than apoptosis in the form of autophagy in leukemic cell. GENERAL SIGNIFICANCE This study might provide the understanding area of chemotherapeutic drug development from natural resources like snake venoms.
Collapse
Affiliation(s)
- Tanmoy Bhowmik
- Lab of Toxinology and Exp. Pharmacodynamics, Department of Physiology, University of Calcutta, 92, APC Road, Kolkata, 700 009 India
| | - Antony Gomes
- Lab of Toxinology and Exp. Pharmacodynamics, Department of Physiology, University of Calcutta, 92, APC Road, Kolkata, 700 009 India.
| |
Collapse
|
7
|
Pagliuso A, Valente C, Giordano LL, Filograna A, Li G, Circolo D, Turacchio G, Marzullo VM, Mandrich L, Zhukovsky MA, Formiggini F, Polishchuk RS, Corda D, Luini A. Golgi membrane fission requires the CtBP1-S/BARS-induced activation of lysophosphatidic acid acyltransferase δ. Nat Commun 2016; 7:12148. [PMID: 27401954 PMCID: PMC4945875 DOI: 10.1038/ncomms12148] [Citation(s) in RCA: 214] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 06/03/2016] [Indexed: 11/25/2022] Open
Abstract
Membrane fission is an essential cellular process by which continuous membranes split into separate parts. We have previously identified CtBP1-S/BARS (BARS) as a key component of a protein complex that is required for fission of several endomembranes, including basolateral post-Golgi transport carriers. Assembly of this complex occurs at the Golgi apparatus, where BARS binds to the phosphoinositide kinase PI4KIIIβ through a 14-3-3γ dimer, as well as to ARF and the PKD and PAK kinases. We now report that, when incorporated into this complex, BARS binds to and activates a trans-Golgi lysophosphatidic acid (LPA) acyltransferase type δ (LPAATδ) that converts LPA into phosphatidic acid (PA); and that this reaction is essential for fission of the carriers. LPA and PA have unique biophysical properties, and their interconversion might facilitate the fission process either directly or indirectly (via recruitment of proteins that bind to PA, including BARS itself).
Collapse
Affiliation(s)
- Alessandro Pagliuso
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, Pozzuoli 80078, Italy
| | - Carmen Valente
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Lucia Laura Giordano
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Angela Filograna
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Guiling Li
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Diego Circolo
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Gabriele Turacchio
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Vincenzo Manuel Marzullo
- IRCCS SDN Istituto di Ricerca Diagnostica e Nucleare, Via Emanuele Gianturco 113, 80143 Naples, Italy
| | - Luigi Mandrich
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Mikhail A. Zhukovsky
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Fabio Formiggini
- Italian Institute of Technology, Centre for Advanced Biomaterials for Health Care at CRIB, Largo Barsanti e Matteucci 53, Naples 80125, Italy
| | - Roman S. Polishchuk
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, Pozzuoli 80078, Italy
| | - Daniela Corda
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Alberto Luini
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
- IRCCS SDN Istituto di Ricerca Diagnostica e Nucleare, Via Emanuele Gianturco 113, 80143 Naples, Italy
| |
Collapse
|
8
|
Liu Y, Takahashi Y, Desai N, Zhang J, Serfass JM, Shi YG, Lynch CJ, Wang HG. Bif-1 deficiency impairs lipid homeostasis and causes obesity accompanied by insulin resistance. Sci Rep 2016; 6:20453. [PMID: 26857140 PMCID: PMC4746598 DOI: 10.1038/srep20453] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 01/04/2016] [Indexed: 12/27/2022] Open
Abstract
Bif-1 is a membrane-curvature inducing protein that is implicated in the regulation of autophagy and tumorigenesis. Here, we report that Bif-1 plays a critical role in regulating lipid catabolism to control the size of lipid droplets and prevent the development of obesity and insulin resistance upon aging or dietary challenge. Our data show that Bif-1 deficiency promotes the expansion of adipose tissue mass without altering food intake or physical activities. While Bif-1 is dispensable for adipose tissue development, its deficiency reduces the basal rate of adipose tissue lipolysis and results in adipocyte hypertrophy upon aging. The importance of Bif-1 in lipid turnover is not limited to adipose tissue since fasting and refeeding-induced lipid droplet clearance is also attenuated by Bif-1 loss in the liver. Interestingly, obesity induced by a high fat-diet or Bif-1 deficiency downregulates the expression of proteins involved in the autophagy-lysosomal pathway, including Atg9a and Lamp1 in the adipose tissue. These findings thus identify Bif-1 as a novel regulator of lipid homeostasis to prevent the pathogenesis of obesity and its associated metabolic complications.
Collapse
Affiliation(s)
- Ying Liu
- Department of Pharmacology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Yoshinori Takahashi
- Department of Pediatrics, Penn State University College of Medicine, Hershey, PA 17033, USA
- Penn State Cancer Institute, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Neelam Desai
- Department of Pediatrics, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Jun Zhang
- Department of Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Jacob M. Serfass
- Department of Pharmacology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Yu-Guang Shi
- Department of Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Christopher J. Lynch
- Department of Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Hong-Gang Wang
- Department of Pharmacology, Penn State University College of Medicine, Hershey, PA 17033, USA
- Department of Pediatrics, Penn State University College of Medicine, Hershey, PA 17033, USA
- Penn State Cancer Institute, Penn State University College of Medicine, Hershey, PA 17033, USA
| |
Collapse
|
9
|
Abstract
The Golgi complex plays a central role in the intracellular sorting of proteins. Transport through the Golgi in the anterograde direction has been explained by cisternal maturation, while transport in the retrograde direction is attributed to vesicles formed by the coat protein I (COPI) complex. A more detailed understanding of how COPI acts in Golgi transport is being achieved in recent years, due in large part to a COPI reconstitution system. Through this approach, the mechanistic complexities of COPI vesicle formation are being elucidated. This approach has also uncovered a new mode of anterograde transport through the Golgi, which involves COPI tubules connecting the Golgi cisternae. We describe in this chapter the reconstitution of COPI vesicle and tubule formation from Golgi membrane.
Collapse
Affiliation(s)
- Seung-Yeol Park
- Division of Rheumatology, Immunology, and Allergy, Brigham and Women's Hospital, Boston, MA, 02115, USA
- Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA
| | - Jia-Shu Yang
- Division of Rheumatology, Immunology, and Allergy, Brigham and Women's Hospital, Boston, MA, 02115, USA
- Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA
| | - Victor W Hsu
- Division of Rheumatology, Immunology, and Allergy, Brigham and Women's Hospital, Boston, MA, 02115, USA.
- Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA.
- Brigham and Women's Hospital, 1 Jimmy Fund Way, Boston, MA, 02115, USA.
| |
Collapse
|
10
|
Frolov VA, Escalada A, Akimov SA, Shnyrova AV. Geometry of membrane fission. Chem Phys Lipids 2015; 185:129-40. [DOI: 10.1016/j.chemphyslip.2014.07.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 07/16/2014] [Accepted: 07/18/2014] [Indexed: 11/24/2022]
|
11
|
Kahn RA. GAPs: Terminator versus effector functions and the role(s) of ArfGAP1 in vesicle biogenesis. CELLULAR LOGISTICS 2014; 1:49-51. [PMID: 21686252 DOI: 10.4161/cl.1.2.15153] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2011] [Accepted: 02/14/2011] [Indexed: 11/19/2022]
Abstract
Whether your passion is to understand and reverse disease processes or "simply" a better understanding of how cells work, anyone wishing to understand cell regulation today must have a detailed and accurate understanding of regulatory GTPase mechanisms and their application to specific pathways. This is becoming increasingly difficult as the details of signaling by members of different families of GTPases and their regulators expand. But this is all the more reason to continually ask, which aspects of GTPase signaling are distinct to a GTPase or its subfamily and which are conserved throughout the superfamily? We each have slightly different views of the key aspects of GTPase signaling that are derived from the main GTPases studied in our own labs; e.g., translocation onto a membrane is an essential and integral aspect of Arf activation but not of other GTPases. However, one aspect of GTPase signaling that I had come to believe to be widespread and of general importance is not universally accepted. In fact, through my conversations at the recent FASEB summer research conference on "Arf Family GTPases" and reading of the literature in a graduate tutorial class, I realized that it is not known or accepted by the majority of researchers. The question is the role of GTPase activating proteins (GAPs) in signaling. Are they "pure" terminators of signaling or do they serve effector functions?
Collapse
Affiliation(s)
- Richard A Kahn
- Department of Biochemistry; Emory University School of Medicine; Atlanta, GA USA
| |
Collapse
|
12
|
ArfGAP3 is a component of the photoreceptor synaptic ribbon complex and forms an NAD(H)-regulated, redox-sensitive complex with RIBEYE that is important for endocytosis. J Neurosci 2014; 34:5245-60. [PMID: 24719103 DOI: 10.1523/jneurosci.3837-13.2014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Ribbon synapses are tonically active synapses in the retina and inner ear with intense vesicle traffic. How this traffic is organized and regulated is still unknown. Synaptic ribbons, large presynaptic structures associated with numerous synaptic vesicles, appear to be essential for this process. The base of the synaptic ribbon is anchored at the active zone and is a hotspot of exocytosis. The synaptic ribbon complex is also important for vesicle replenishment. RIBEYE is a unique and major component of synaptic ribbons. It consists of a unique A-domain and an NAD(H)-binding, C-terminal B-domain. In the present study, we show that the Arf-GTPase activating protein-3 (ArfGAP3), a well characterized regulator of vesicle formation at the Golgi apparatus, is also a component of the synaptic ribbon complex in photoreceptor synapses of the mouse retina and interacts with RIBEYE as shown by multiple, independent approaches. ArfGAP3 binds to RIBEYE(B)-domain in an NAD(H)-dependent manner. The interaction is redox sensitive because NADH is more efficient than the oxidized NAD(+) in promoting ArfGAP3-RIBEYE interaction. RIBEYE competes with the GTP-binding protein Arf1 for binding to ArfGAP3. Thus, binding of RIBEYE(B) to ArfGAP3 could prevent inactivation of Arf1 by ArfGAP3 and provides the synaptic ribbon with the possibility to control Arf1 function. The interaction is relevant for endocytic vesicle trafficking because overexpression of ArfGAP3 in photoreceptors strongly inhibited endocytotic uptake of FM1-43.
Collapse
|
13
|
Croisé P, Estay-Ahumada C, Gasman S, Ory S. Rho GTPases, phosphoinositides, and actin: a tripartite framework for efficient vesicular trafficking. Small GTPases 2014; 5:e29469. [PMID: 24914539 DOI: 10.4161/sgtp.29469] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Rho GTPases are well known regulators of the actin cytoskeleton that act by binding and activating actin nucleators. They are therefore involved in many actin-based processes, including cell migration, cell polarity, and membrane trafficking. With the identification of phosphoinositide kinases and phosphatases as potential binding partners or effectors, Rho GTPases also appear to participate in the regulation of phosphoinositide metabolism. Since both actin dynamics and phosphoinositide turnover affect the efficiency and the fidelity of vesicle transport between cell compartments, Rho GTPases have emerged as critical players in membrane trafficking. Rho GTPase activity, actin remodeling, and phosphoinositide metabolism need to be coordinated in both space and time to ensure the progression of vesicles along membrane trafficking pathways. Although most molecular pathways are still unclear, in this review, we will highlight recent advances made in our understanding of how Rho-dependent signaling pathways organize actin dynamics and phosphoinositides and how phosphoinositides potentially provide negative feedback to Rho GTPases during endocytosis, exocytosis and membrane exchange between intracellular compartments.
Collapse
Affiliation(s)
- Pauline Croisé
- CNRS UPR 3212; Institut des Neurosciences Cellulaires et Intégratives; Université de Strasbourg; Strasbourg, France
| | - Catherine Estay-Ahumada
- CNRS UPR 3212; Institut des Neurosciences Cellulaires et Intégratives; Université de Strasbourg; Strasbourg, France
| | - Stéphane Gasman
- CNRS UPR 3212; Institut des Neurosciences Cellulaires et Intégratives; Université de Strasbourg; Strasbourg, France
| | - Stéphane Ory
- CNRS UPR 3212; Institut des Neurosciences Cellulaires et Intégratives; Université de Strasbourg; Strasbourg, France
| |
Collapse
|
14
|
McLelland GL, Soubannier V, Chen CX, McBride HM, Fon EA. Parkin and PINK1 function in a vesicular trafficking pathway regulating mitochondrial quality control. EMBO J 2014; 33:282-95. [PMID: 24446486 DOI: 10.1002/embj.201385902] [Citation(s) in RCA: 392] [Impact Index Per Article: 39.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Mitochondrial dysfunction has long been associated with Parkinson's disease (PD). Parkin and PINK1, two genes associated with familial PD, have been implicated in the degradation of depolarized mitochondria via autophagy (mitophagy). Here, we describe the involvement of parkin and PINK1 in a vesicular pathway regulating mitochondrial quality control. This pathway is distinct from canonical mitophagy and is triggered by the generation of oxidative stress from within mitochondria. Wild-type but not PD-linked mutant parkin supports the biogenesis of a population of mitochondria-derived vesicles (MDVs), which bud off mitochondria and contain a specific repertoire of cargo proteins. These MDVs require PINK1 expression and ultimately target to lysosomes for degradation. We hypothesize that loss of this parkin- and PINK1-dependent trafficking mechanism impairs the ability of mitochondria to selectively degrade oxidized and damaged proteins leading, over time, to the mitochondrial dysfunction noted in PD.
Collapse
Affiliation(s)
- Gian-Luca McLelland
- McGill Parkinson Program Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital McGill University, Montreal, QC, Canada
| | | | | | | | | |
Collapse
|
15
|
Tsai YC, Chiang W, Liou W, Lee WH, Chang YW, Wang PY, Li YC, Tanaka T, Nakamura A, Pai LM. Endophilin B is required for the Drosophila oocyte to endocytose yolk downstream of Oskar. Development 2014; 141:563-73. [PMID: 24401369 DOI: 10.1242/dev.097022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The nutritional environment is crucial for Drosophila oogenesis in terms of controlling hormonal conditions that regulate yolk production and the progress of vitellogenesis. Here, we discovered that Drosophila Endophilin B (D-EndoB), a member of the endophilin family, is required for yolk endocytosis as it regulates membrane dynamics in developing egg chambers. Loss of D-EndoB leads to yolk content reduction, similar to that seen in yolkless mutants, and also causes poor fecundity. In addition, mutant egg chambers exhibit an arrest at the previtellogenic stage. D-EndoB displayed a crescent localization at the oocyte posterior pole in an Oskar-dependent manner; however, it did not contribute to pole plasm assembly. D-EndoB was found to partially colocalize with Long Oskar and Yolkless at the endocytic membranes in ultrastructure analysis. Using an FM4-64 dye incorporation assay, D-EndoB was also found to promote endocytosis in the oocyte. When expressing the full-length D-endoB(FL) or D-endoB(ΔSH3) mutant transgenes in oocytes, the blockage of vitellogenesis and the defect in fecundity in D-endoB mutants was restored. By contrast, a truncated N-BAR domain of the D-EndoB only partially rescued these defects. Taken together, these results allow us to conclude that D-EndoB contributes to the endocytic activity downstream of Oskar by facilitating membrane dynamics through its N-BAR domain in the yolk uptake process, thereby leading to normal progression of vitellogenesis.
Collapse
Affiliation(s)
- Yi-Cheng Tsai
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, 333, Taiwan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
He S, Ni D, Ma B, Lee JH, Zhang T, Ghozalli I, Pirooz SD, Zhao Z, Bharatham N, Li B, Oh S, Lee WH, Takahashi Y, Wang HG, Minassian A, Feng P, Deretic V, Pepperkok R, Tagaya M, Yoon HS, Liang C. PtdIns(3)P-bound UVRAG coordinates Golgi-ER retrograde and Atg9 transport by differential interactions with the ER tether and the beclin 1 complex. Nat Cell Biol 2013; 15:1206-1219. [PMID: 24056303 PMCID: PMC3805255 DOI: 10.1038/ncb2848] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 08/21/2013] [Indexed: 12/14/2022]
Abstract
Endoplasmic reticulum (ER)-Golgi membrane transport and autophagy are intersecting trafficking pathways that are tightly regulated and crucial for homeostasis, development and disease. Here, we identify UVRAG, a beclin-1-binding autophagic factor, as a phosphatidylinositol-3-phosphate (PtdIns(3)P)-binding protein that depends on PtdIns(3)P for its ER localization. We further show that UVRAG interacts with RINT-1, and acts as an integral component of the RINT-1-containing ER tethering complex, which couples phosphoinositide metabolism to COPI-vesicle tethering. Displacement or knockdown of UVRAG profoundly disrupted COPI cargo transfer to the ER and Golgi integrity. Intriguingly, autophagy caused the dissociation of UVRAG from the ER tether, which in turn worked in concert with the Bif-1-beclin-1-PI(3)KC3 complex to mobilize Atg9 translocation for autophagosome formation. These findings identify a regulatory mechanism that coordinates Golgi-ER retrograde and autophagy-related vesicular trafficking events through physical and functional interactions between UVRAG, phosphoinositide and their regulatory factors, thereby ensuring spatiotemporal fidelity of membrane trafficking and maintenance of organelle homeostasis.
Collapse
Affiliation(s)
- Shanshan He
- Department of Molecular Microbiology and Immunology, University of Southern California, Los Angeles, CA 90033, USA
| | - Duojiao Ni
- Department of Molecular Microbiology and Immunology, University of Southern California, Los Angeles, CA 90033, USA
| | - Binyun Ma
- Department of Molecular Microbiology and Immunology, University of Southern California, Los Angeles, CA 90033, USA
| | - Joo-Hyung Lee
- Department of Molecular Microbiology and Immunology, University of Southern California, Los Angeles, CA 90033, USA
| | - Tian Zhang
- Department of Molecular Microbiology and Immunology, University of Southern California, Los Angeles, CA 90033, USA
| | - Irene Ghozalli
- Department of Molecular Microbiology and Immunology, University of Southern California, Los Angeles, CA 90033, USA
| | - Sara Dolatshahi Pirooz
- Department of Molecular Microbiology and Immunology, University of Southern California, Los Angeles, CA 90033, USA
| | - Zhen Zhao
- Department of Molecular Microbiology and Immunology, University of Southern California, Los Angeles, CA 90033, USA
| | - Nagakumar Bharatham
- Division of Structural Biology and Biochemistry, School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | - Baihong Li
- Division of Structural Biology and Biochemistry, School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | - Soohwan Oh
- Department of Molecular Microbiology and Immunology, University of Southern California, Los Angeles, CA 90033, USA
| | - Wen-Hwa Lee
- Department of Biological Chemistry, University of California, Irvine, Irvine, California 92697
| | - Yoshinori Takahashi
- Department of Pharmacology and Penn State Hershey Cancer Institute; The Pennsylvania State University College of Medicine; Hershey, PA USA
| | - Hong-Gang Wang
- Department of Pharmacology and Penn State Hershey Cancer Institute; The Pennsylvania State University College of Medicine; Hershey, PA USA
| | - Arlet Minassian
- Department of Molecular Microbiology and Immunology, University of Southern California, Los Angeles, CA 90033, USA
| | - Pinghui Feng
- Department of Molecular Microbiology and Immunology, University of Southern California, Los Angeles, CA 90033, USA
| | - Vojo Deretic
- Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131
| | - Rainer Pepperkok
- European Molecular Biology Laboratory, Heidelberg, Cell Biology/Cell Biophysics Unit, Meyerhofstr. 1, D-69117 Heidelberg Germany
| | - Mitsuo Tagaya
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0393, Japan
| | - Ho Sup Yoon
- Division of Structural Biology and Biochemistry, School of Biological Sciences, Nanyang Technological University, Singapore 637551
- Department of Genetic Engineering, College of Life Sciences, Kyung Hee University, Yongin-si, Gyeonggi-do, 446-701, Republic of Korea
| | - Chengyu Liang
- Department of Molecular Microbiology and Immunology, University of Southern California, Los Angeles, CA 90033, USA
| |
Collapse
|
17
|
Mironov AA, Sesorova IV, Beznoussenko GV. Golgi's way: a long path toward the new paradigm of the intra-Golgi transport. Histochem Cell Biol 2013; 140:383-93. [PMID: 24068461 DOI: 10.1007/s00418-013-1141-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2013] [Indexed: 11/28/2022]
Abstract
The transport of proteins and lipids is one of the main cellular functions. The vesicular model, compartment (or cisterna) maturation model, and the diffusion model compete with each other for the right to be the paradigm within the field of the intra-Golgi transport. These models have significant difficulties explaining the existing experimental data. Recently, we proposed the kiss-and-run (KAR) model of intra-Golgi transport (Mironov and Beznoussenko in Int J Mol Sci 13(6):6800-6819, 2012), which can be symmetric, when fusion and fission occur in the same location, and asymmetric, when fusion and fission take place at different sites. Here, we compare the ability of main models of the intra-Golgi transport to explain the existing results examining the evidence in favor and against each model. We propose that the KAR model has the highest potential for the explanation of the majority of experimental observations existing within the field of intracellular transport.
Collapse
Affiliation(s)
- Alexander A Mironov
- Istituto di Oncologia Molecolare di Fondazione Italiana per la Ricerca sul Cancro, 20139, Milan, Italy,
| | | | | |
Collapse
|
18
|
Nishimura T, Uchida Y, Yachi R, Kudlyk T, Lupashin V, Inoue T, Taguchi T, Arai H. Oxysterol-binding protein (OSBP) is required for the perinuclear localization of intra-Golgi v-SNAREs. Mol Biol Cell 2013; 24:3534-44. [PMID: 24048449 PMCID: PMC3826991 DOI: 10.1091/mbc.e13-05-0250] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
OSBP regulates the Golgi cholesterol level. This study demonstrates that OSBP and cholesterol are essential for localization of Golgi v-SNAREs. Knockdown of ArfGAP1 restores v-SNARE localization in OSBP-depleted cells, suggesting that OSBP-regulated cholesterol ensures proper COP-I vesicle transport. Oxysterol-binding protein (OSBP) and OSBP-related proteins (ORPs) have been implicated in the distribution of sterols among intracellular organelles. OSBP regulates the Golgi cholesterol level, but how it relates to Golgi function is elusive. Here we report that OSBP is essential for the localization of intra-Golgi soluble vesicle N-ethylmaleimide-sensitive fusion attachment protein receptors (v-SNAREs). Depletion of OSBP by small interfering RNA causes mislocalization of intra-Golgi v-SNAREs GS28 and GS15 throughout the cytoplasm without affecting the perinuclear localization of Golgi target-SNARE syntaxin5 and reduces the abundance of a Golgi enzyme, mannosidase II (Man II). GS28 mislocalization and Man II reduction are also induced by cellular cholesterol depletion. Three domains of OSBP—an endoplasmic reticulum–targeting domain, a Golgi-targeting domain, and a sterol-binding domain—are all required for Golgi localization of GS28. Finally, GS28 mislocalization and Man II reduction in OSBP-depleted cells are largely restored by depletion of ArfGAP1, a regulator of the budding of coat protein complex (COP)-I vesicles. From these results, we postulate that Golgi cholesterol level, which is controlled by OSBP, is essential for Golgi localization of intra-Golgi v-SNAREs by ensuring proper COP-I vesicle transport.
Collapse
Affiliation(s)
- Taki Nishimura
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan Pathological Cell Biology Laboratory, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan Department of Physiology and Biophysics, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR 72205
| | | | | | | | | | | | | | | |
Collapse
|
19
|
Components of the CtBP1/BARS-dependent fission machinery. Histochem Cell Biol 2013; 140:407-21. [PMID: 23996193 DOI: 10.1007/s00418-013-1138-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/20/2013] [Indexed: 01/12/2023]
Abstract
The brefeldin A ADP-ribosylated substrate, a member of the C-terminal-binding protein family that is referred to as CtBP1/BARS, is a dual-function protein that acts as a transcriptional co-repressor in the nucleus and as an inducer of membrane fission in the cytoplasm. In this review, we first discuss the mechanisms that enable CtBP1/BARS to shift between the nuclear transcriptional co-repressor and the cytosolic fission-inducing activities. Then, we focus on the role of CtBP1/BARS in membrane fission. CtBP1/BARS controls several fission events including macropinocytosis, fluid-phase endocytosis, COPI-coated vesicle formation, basolaterally directed post-Golgi carrier formation, and Golgi partitioning in mitosis. We report on recent advances in our understanding of the CtBP1/BARS membrane fission machineries that operate at the trans-side and at the cis-side of the Golgi complex. Specifically, we discuss how these machineries are assembled and regulated, and how they operate in the formation of the basolaterally directed post-Golgi carriers.
Collapse
|
20
|
Vannier C, Pesty A, San-Roman MJ, Schmidt AA. The Bin/amphiphysin/Rvs (BAR) domain protein endophilin B2 interacts with plectin and controls perinuclear cytoskeletal architecture. J Biol Chem 2013; 288:27619-27637. [PMID: 23921385 DOI: 10.1074/jbc.m113.485482] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Proteins of the Bin/amphiphysin/Rvs (BAR) domain superfamily are essential in controlling the shape and dynamics of intracellular membranes. Here, we present evidence for the unconventional function of a member of the endophilin family of BAR and Src homology 3 domain-containing proteins, namely endophilin B2, in the perinuclear organization of intermediate filaments. Using mass spectrometry analysis based on capturing endophilin B2 partners in in situ pre-established complexes in cells, we unravel the interaction of endophilin B2 with plectin 1, a variant of the cytoskeleton linker protein plectin as well as with vimentin. Endophilin B2 directly binds the N-terminal region of plectin 1 via Src homology 3-mediated interaction and vimentin indirectly via plectin-mediated interaction. The relevance of these interactions is strengthened by the selective and drastic reorganization of vimentin around nuclei upon overexpression of endophilin B2 and by the extensive colocalization of both proteins in a meshwork of perinuclear filamentous structures. By generating mutants of the endophilin B2 BAR domain, we show that this phenotype requires the BAR-mediated membrane binding activity of endophilin B2. Plectin 1 or endophilin B2 knockdown using RNA interference disturbed the perinuclear organization of vimentin. Altogether, these data suggest that the endophilin B2-plectin 1 complex functions as a membrane-anchoring device organizing and stabilizing the perinuclear network of vimentin filaments. Finally, we present evidence for the involvement of endophilin B2 and plectin 1 in nuclear positioning in individual cells. This points to the potential importance of the endophilin B2-plectin complex in the biological functions depending on nuclear migration and positioning.
Collapse
Affiliation(s)
- Christian Vannier
- From CNRS, UMR7592, Institut Jacques Monod, Université Paris Diderot, Sorbonne Paris Cité, 15 Rue Hélène Brion, F-75205 Paris Cedex 13, France
| | - Arlette Pesty
- From CNRS, UMR7592, Institut Jacques Monod, Université Paris Diderot, Sorbonne Paris Cité, 15 Rue Hélène Brion, F-75205 Paris Cedex 13, France
| | - Mabel Jouve San-Roman
- From CNRS, UMR7592, Institut Jacques Monod, Université Paris Diderot, Sorbonne Paris Cité, 15 Rue Hélène Brion, F-75205 Paris Cedex 13, France
| | - Anne A Schmidt
- From CNRS, UMR7592, Institut Jacques Monod, Université Paris Diderot, Sorbonne Paris Cité, 15 Rue Hélène Brion, F-75205 Paris Cedex 13, France.
| |
Collapse
|
21
|
Adolf F, Herrmann A, Hellwig A, Beck R, Brügger B, Wieland FT. Scission of COPI and COPII vesicles is independent of GTP hydrolysis. Traffic 2013; 14:922-32. [PMID: 23691917 DOI: 10.1111/tra.12084] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 05/15/2013] [Accepted: 05/20/2013] [Indexed: 12/29/2022]
Abstract
Intracellular transport and maintenance of the endomembrane system in eukaryotes depends on formation and fusion of vesicular carriers. A seeming discrepancy exists in the literature about the basic mechanism in the scission of transport vesicles that depend on GTP-binding proteins. Some reports describe that the scission of COP-coated vesicles is dependent on GTP hydrolysis, whereas others found that GTP hydrolysis is not required. In order to investigate this pivotal mechanism in vesicle formation, we analyzed formation of COPI- and COPII-coated vesicles utilizing semi-intact cells. The small GTPases Sar1 and Arf1 together with their corresponding coat proteins, the Sec23/24 and Sec13/31 complexes for COPII and coatomer for COPI vesicles were required and sufficient to drive vesicle formation. Both types of vesicles were efficiently generated when GTP hydrolysis was blocked either by utilizing the poorly hydrolyzable GTP analogs GTPγS and GMP-PNP, or with constitutively active mutants of the small GTPases. Thus, GTP hydrolysis is not required for the formation and release of COP vesicles.
Collapse
Affiliation(s)
- Frank Adolf
- Heidelberg University Biochemistry Center, University of Heidelberg, Im Neuenheimer Feld 328, D-69120, Heidelberg, Germany
| | | | | | | | | | | |
Collapse
|
22
|
Abstract
The striking morphology of the Golgi complex has fascinated cell biologists since its discovery over 100 years ago. Yet, despite intense efforts to understand how membrane flow relates to Golgi form and function, this organelle continues to baffle cell biologists and biochemists alike. Fundamental questions regarding Golgi function, while hotly debated, remain unresolved. Historically, Golgi function has been described from a protein-centric point of view, but we now appreciate that conceptual frameworks for how lipid metabolism is integrated with Golgi biogenesis and function are essential for a mechanistic understanding of this fascinating organelle. It is from a lipid-centric perspective that we discuss the larger question of Golgi dynamics and membrane trafficking. We review the growing body of evidence for how lipid metabolism is integrally written into the engineering of the Golgi system and highlight questions for future study.
Collapse
Affiliation(s)
- Vytas A Bankaitis
- Department of Cell and Developmental Biology, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7090, USA.
| | | | | |
Collapse
|
23
|
Mironov AA, Beznoussenko GV. The kiss-and-run model of intra-Golgi transport. Int J Mol Sci 2012; 13:6800-6819. [PMID: 22837664 PMCID: PMC3397496 DOI: 10.3390/ijms13066800] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 05/09/2012] [Accepted: 05/22/2012] [Indexed: 11/16/2022] Open
Abstract
The Golgi apparatus (GA) is the main station along the secretory pathway. Mechanisms of intra-Golgi transport remain unresolved. Three models compete with each other for the right to be defined as the paradigm. The vesicular model cannot explain the following: (1) lipid droplets and aggregates of procollagen that are larger than coatomer I (COPI)-dependent vesicles are transported across the GA; and (2) most anterograde cargoes are depleted in COPI vesicles. The compartment progression/maturation model has the following problems: (1) most Golgi-resident proteins are depleted in COPI vesicles; (2) there are no COPI vesicles for the recycling of the resident proteins in the trans-most-Golgi cisterna; and (3) different proteins have different rates of intra-Golgi transport. The diffusion model based on permanent inter-cisternal connections cannot explain the existence of lipid, ionic and protein gradients across the Golgi stacks. In contrast, the kiss-and-run model has the potential to explain most of the experimental observations. The kiss-and-run model can be symmetric when fusion and then fission occurs in the same place, and asymmetric when fusion takes place in one location, whereas fission takes place in another. The asymmetric kiss-and-run model resembles the carrier maturation mechanism, and it can be used to explain the transport of large cargo aggregates.
Collapse
Affiliation(s)
- Alexander A. Mironov
- IFOM Foundation, FIRC Institute of Molecular Oncology (IFOM-IEO Campus), Via Adamello 16, 20139, Milan, Italy
| | - Galina V. Beznoussenko
- IFOM Foundation, FIRC Institute of Molecular Oncology (IFOM-IEO Campus), Via Adamello 16, 20139, Milan, Italy
| |
Collapse
|
24
|
Regulation of the Golgi complex by phospholipid remodeling enzymes. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1821:1078-88. [PMID: 22562055 DOI: 10.1016/j.bbalip.2012.04.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 03/15/2012] [Accepted: 04/13/2012] [Indexed: 11/23/2022]
Abstract
The mammalian Golgi complex is a highly dynamic organelle consisting of stacks of flattened cisternae with associated coated vesicles and membrane tubules that contribute to cargo import and export, intra-cisternal trafficking, and overall Golgi architecture. At the morphological level, all of these structures are continuously remodeled to carry out these trafficking functions. Recent advances have shown that continual phospholipid remodeling by phospholipase A (PLA) and lysophospholipid acyltransferase (LPAT) enzymes, which deacylate and reacylate Golgi phospholipids, respectively, contributes to this morphological remodeling. Here we review the identification and characterization of four cytoplasmic PLA enzymes and one integral membrane LPAT that participate in the dynamic functional organization of the Golgi complex, and how some of these enzymes are integrated to determine the relative abundance of COPI vesicle and membrane tubule formation. This article is part of a Special Issue entitled Lipids and Vesicular Transport.
Collapse
|
25
|
Gortat A, San-Roman MJ, Vannier C, Schmidt AA. Single point mutation in Bin/Amphiphysin/Rvs (BAR) sequence of endophilin impairs dimerization, membrane shaping, and Src homology 3 domain-mediated partnership. J Biol Chem 2011; 287:4232-47. [PMID: 22167186 DOI: 10.1074/jbc.m111.325837] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bin/Amphiphysin/Rvs (BAR) domain-containing proteins are essential players in the dynamics of intracellular compartments. The BAR domain is an evolutionarily conserved dimeric module characterized by a crescent-shaped structure whose intrinsic curvature, flexibility, and ability to assemble into highly ordered oligomers contribute to inducing the curvature of target membranes. Endophilins, diverging into A and B subgroups, are BAR and SH3 domain-containing proteins. They exert activities in membrane dynamic processes such as endocytosis, autophagy, mitochondrial dynamics, and permeabilization during apoptosis. Here, we report on the involvement of the third α-helix of the endophilin A BAR sequence in dimerization and identify leucine 215 as a key residue within a network of hydrophobic interactions stabilizing the entire BAR dimer interface. With the combination of N-terminal truncation retaining the high dimerization capacity of the third α-helices of endophilin A and leucine 215 substitution by aspartate (L215D), we demonstrate the essential role of BAR sequence-mediated dimerization on SH3 domain partnership. In comparison with wild type, full-length endophilin A2 heterodimers with one protomer bearing the L215D substitution exhibit very significant changes in membrane binding and shaping activities as well as a dramatic decrease of SH3 domain partnership. This suggests that subtle changes in the conformation and/or rigidity of the BAR domain impact both the control of membrane curvature and downstream binding to effectors. Finally, we show that expression, in mammalian cells, of endophilin A2 bearing the L215D substitution impairs the endocytic recycling of transferrin receptors.
Collapse
Affiliation(s)
- Anna Gortat
- CNRS, UMR7592, Institut Jacques Monod, Université Paris Diderot, Sorbonne Paris Cité, F-75205 Paris, France
| | | | | | | |
Collapse
|
26
|
Minamisawa N, Sato M, Cho KH, Ueno H, Takechi K, Kajikawa M, Yamato KT, Ohyama K, Toyooka K, Kim GT, Horiguchi G, Takano H, Ueda T, Tsukaya H. ANGUSTIFOLIA, a plant homolog of CtBP/BARS, functions outside the nucleus. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2011; 68:788-99. [PMID: 21801251 DOI: 10.1111/j.1365-313x.2011.04731.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
CtBP/BARS is a unique protein family in having quite diversified cellular functions, intercellular localizations, and developmental roles. ANGUSTIFOLIA (AN) is the sole homolog of CtBP/BARS from Arabidopsis thaliana, although it has plant AN-specific motifs and a long C-terminus. Previous studies suggested that AN would function in the nucleus as a transcriptional co-repressor, as CtBPs function in animals; however, precise verification has been lacking. In this paper, we isolated a homologous gene (MAN) of AN from liverwort, Marchantia polymorpha. Transformation of the Arabidopsis an-1 mutant with 35S-driven MAN completely complemented the an-1 phenotype, although it lacks the putative nuclear localization signal (NLS) that exists in AN proteins isolated from other plant species. We constructed several plasmids for expressing modified ANs with amino acid substitutions in known motifs. The results clearly indicated that modified AN with mutations in the putative NLS-like domain could complement the an-1 phenotype. Therefore, we re-examined localization of AN using several techniques. Our results demonstrated that AN localizes on punctuate structures around the Golgi, partially overlapping with a trans-Golgi network resident, which highlighted an unexpected link between leaf development and membrane trafficking. We should reconsider the roles and evolutionary traits of AN based on these findings.
Collapse
Affiliation(s)
- Naoko Minamisawa
- Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Popoff V, Adolf F, Brügger B, Wieland F. COPI budding within the Golgi stack. Cold Spring Harb Perspect Biol 2011; 3:a005231. [PMID: 21844168 DOI: 10.1101/cshperspect.a005231] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The Golgi serves as a hub for intracellular membrane traffic in the eukaryotic cell. Transport within the early secretory pathway, that is within the Golgi and from the Golgi to the endoplasmic reticulum, is mediated by COPI-coated vesicles. The COPI coat shares structural features with the clathrin coat, but differs in the mechanisms of cargo sorting and vesicle formation. The small GTPase Arf1 initiates coating on activation and recruits en bloc the stable heptameric protein complex coatomer that resembles the inner and the outer shells of clathrin-coated vesicles. Different binding sites exist in coatomer for membrane machinery and for the sorting of various classes of cargo proteins. During the budding of a COPI vesicle, lipids are sorted to give a liquid-disordered phase composition. For the release of a COPI-coated vesicle, coatomer and Arf cooperate to mediate membrane separation.
Collapse
Affiliation(s)
- Vincent Popoff
- Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany
| | | | | | | |
Collapse
|
28
|
Yang JS, Valente C, Polishchuk RS, Turacchio G, Layre E, Moody DB, Leslie CC, Gelb MH, Brown WJ, Corda D, Luini A, Hsu VW. COPI acts in both vesicular and tubular transport. Nat Cell Biol 2011; 13:996-1003. [PMID: 21725317 PMCID: PMC3149785 DOI: 10.1038/ncb2273] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Accepted: 05/04/2011] [Indexed: 12/20/2022]
Abstract
Intracellular transport occurs through two general types of carrier, either vesicles or tubules. Coat proteins act as the core machinery that initiates vesicle formation, but the counterpart that initiates tubule formation has been unclear. Here, we find that the coat protein I (COPI) complex initially drives the formation of Golgi buds. Subsequently, a set of opposing lipid enzymatic activities determines whether these buds become vesicles or tubules. Lysophosphatidic acid acyltransferase-γ (LPAATγ) promotes COPI vesicle fission for retrograde vesicular transport. In contrast, cytosolic phospholipase A2-α (cPLA2α) inhibits this fission event to induce COPI tubules, which act in anterograde intra-Golgi transport and Golgi ribbon formation. These findings not only advance a molecular understanding of how COPI vesicle fission is achieved, but also provide insight into how COPI acts in intra-Golgi transport and reveal an unexpected mechanistic relationship between vesicular and tubular transport.
Collapse
Affiliation(s)
- Jia-Shu Yang
- Division of Rheumatology, Immunology and Allergy, Brigham and Women’s Hospital, and Department of Medicine, Harvard Medical School, Boston, MA 02115 USA
| | - Carmen Valente
- Telethon Institute of Genetics and Medicine, Via Pietro Castellino 111, 80131 Napoli, Italy
- Institute of Protein Biochemistry, National Research Council Via Pietro Castellino 111, 80131 Napoli, Italy
| | - Roman S. Polishchuk
- Telethon Institute of Genetics and Medicine, Via Pietro Castellino 111, 80131 Napoli, Italy
| | - Gabriele Turacchio
- Institute of Protein Biochemistry, National Research Council Via Pietro Castellino 111, 80131 Napoli, Italy
| | - Emilie Layre
- Division of Rheumatology, Immunology and Allergy, Brigham and Women’s Hospital, and Department of Medicine, Harvard Medical School, Boston, MA 02115 USA
| | - D. Branch Moody
- Division of Rheumatology, Immunology and Allergy, Brigham and Women’s Hospital, and Department of Medicine, Harvard Medical School, Boston, MA 02115 USA
| | - Christina C. Leslie
- Department of Pediatrics, National Jewish Medical and Research Center, and Departments of Pathology and Pharmacology, University of Colorado School of Medicine, Denver, CO 80262
| | - Michael H. Gelb
- Department of Chemistry and Biochemistry, University of Washington, Seattle, WA 98195
| | - William J. Brown
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
| | - Daniela Corda
- Institute of Protein Biochemistry, National Research Council Via Pietro Castellino 111, 80131 Napoli, Italy
| | - Alberto Luini
- Telethon Institute of Genetics and Medicine, Via Pietro Castellino 111, 80131 Napoli, Italy
- Institute of Protein Biochemistry, National Research Council Via Pietro Castellino 111, 80131 Napoli, Italy
| | - Victor W. Hsu
- Division of Rheumatology, Immunology and Allergy, Brigham and Women’s Hospital, and Department of Medicine, Harvard Medical School, Boston, MA 02115 USA
| |
Collapse
|
29
|
Abstract
Background information. CtBPs [C-terminal (of E1A) binding protein] have roles in the nucleus as transcriptional co-repressors, and in the cytoplasm in the maintenance of vesicular membranes. CtBPs are expressed from two genes, CTBP1 and CTBP2, mRNA products of which are alternatively spliced at their 5′-ends to generate distinct protein isoforms. Extensive molecular and cellular analyses have identified CtBPs as regulators of pathways critical for tumour initiation, progression and response to therapy. However, little is known of the expression or regulation of CtBP isoforms in human cancer, nor of the relative contributions of CTBP1 and CTBP2 to the tumour cell phenotype. Results. Expression of CtBP proteins and CTBP1 and CTBP2 mRNA splice forms in breast cancer cell lines and tumour tissue was examined. CtBP1 proteins are identifiable as a single band on Western blots and are ubiquitously detectable in breast tumour samples, by both Western blotting and immunohistochemistry. CtBP1 is present in six of six breast cancer cell lines, although it is barely detectable in SKBr3 cells due to reduced CTBP1 mRNA expression. In the cell lines, the predominant CTBP1 mRNA splice form encodes CtBP1-S protein; in tumours, both major CTBP1 mRNA splice forms are variably expressed. CtBP2 proteins are ubiquitously expressed in all lines and tumour samples. The predominant CTBP2 mRNA encodes CtBP2-L, although an alternatively spliced form that encodes CtBP2-S, previously unidentified in humans, is expressed at low abundance. Both CtBP2-L and CtBP2-S are readily detectable as two distinct bands on Western blots; here we show that the CTBP2-L mRNA is translated from two AUG codons to generate both CtBP2-L and CtBP2-S. We have also identified an autoregulatory feedback mechanism whereby CtBP protein abundance is maintained in proliferating breast cancer cells through the post-transcriptional regulation of CtBP2. This feedback is disrupted by UV-C radiation or exposure to cisplatin. Finally, we demonstrate that CtBP1 and CtBP2 both have p53-dependent and -independent roles in suppressing the sensitivity of breast cancer cells to mechanistically diverse cancer chemotherapeutic agents. Conclusions. These studies support recent evidence that CtBP family proteins represent potential targets for therapeutic strategies for the treatment of cancer in general, and breast cancer in particular.
Collapse
|
30
|
|
31
|
Havrylov S, Redowicz MJ, Buchman VL. Emerging roles of Ruk/CIN85 in vesicle-mediated transport, adhesion, migration and malignancy. Traffic 2010; 11:721-31. [PMID: 20331533 DOI: 10.1111/j.1600-0854.2010.01061.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Ruk/CIN85 is an adaptor protein. Similar to many other proteins of this type, Ruk/CIN85 is known to take part in multiple cellular processes including signal transduction, vesicle-mediated transport, cytoskeleton remodelling, programmed cell death and viral infection. Recent studies have also revealed the potential importance of Ruk/CIN85 in cancer cell invasiveness. In this review we summarize the various roles of this protein as well as the potential contribution of Ruk/CIN85 to malignancy and the invasiveness of cancer cells. In the last section of the paper we also speculate on the utility of Ruk/CIN85 as a target for novel anti-cancer therapies.
Collapse
Affiliation(s)
- Serhiy Havrylov
- Nencki Institute of Experimental Biology, Pasteura 3 Street, 02-093 Warsaw, Poland
| | | | | |
Collapse
|
32
|
Abstract
Autophagosomes are large double-membrane vesicles that enclose cytoplasmic components targeting them for degradation. Two recent reports reveal that phagophores, the autophagosome precursors, are surrounded by and connected to rough endoplasmic reticulum (ER) membranes. These results shed light on how membranes may be supplied and reorganized for autophagosomal biogenesis.
Collapse
Affiliation(s)
- Fulvio Reggiori
- Department of Cell Biology, University Medical Centre Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
| | | |
Collapse
|
33
|
Hsu VW, Yang JS. Mechanisms of COPI vesicle formation. FEBS Lett 2009; 583:3758-63. [PMID: 19854177 PMCID: PMC2788077 DOI: 10.1016/j.febslet.2009.10.056] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Revised: 10/15/2009] [Accepted: 10/20/2009] [Indexed: 10/20/2022]
Abstract
Coat Protein I (COPI) is one of the most intensely investigated coat complexes. Numerous studies have contributed to a general understanding of how coat proteins act to initiate intracellular vesicular transport. This review highlights key recent findings that have shaped our current understanding of how COPI vesicles are formed.
Collapse
Affiliation(s)
- Victor W Hsu
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA.
| | | |
Collapse
|
34
|
Simonsen A, Tooze SA. Coordination of membrane events during autophagy by multiple class III PI3-kinase complexes. ACTA ACUST UNITED AC 2009; 186:773-82. [PMID: 19797076 PMCID: PMC2753151 DOI: 10.1083/jcb.200907014] [Citation(s) in RCA: 368] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Autophagy or “self-eating” is a highly conserved pathway that enables cells to degrade pieces of themselves in autolysosomes to enable their survival in times of stress, including nutrient deprivation. The formation of these degradative compartments requires cytosolic proteins, some of which are autophagy specific, as well as intracellular organelles, such as the ER and Golgi, and the endosome–lysosome system. Here we discuss the cross talk between autophagy and intracellular compartments, highlighting recent exciting data about the role and regulation of the Vps34 class III phosphatidylinositol (PI) 3-kinase in autophagy.
Collapse
Affiliation(s)
- Anne Simonsen
- Department of Biochemistry, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, 0317 Oslo, Norway.
| | | |
Collapse
|
35
|
Proteins recruited by SH3 domains of Ruk/CIN85 adaptor identified by LC-MS/MS. Proteome Sci 2009; 7:21. [PMID: 19531213 PMCID: PMC2702278 DOI: 10.1186/1477-5956-7-21] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Accepted: 06/16/2009] [Indexed: 11/27/2022] Open
Abstract
Background Ruk/CIN85 is a mammalian adaptor molecule with three SH3 domains. Using its SH3 domains Ruk/CIN85 can cluster multiple proteins and protein complexes, and, consequently, facilitates organisation of elaborate protein interaction networks with diverse regulatory roles. Previous research linked Ruk/CIN85 with the regulation of vesicle-mediated transport and cancer cell invasiveness. Despite the recent findings, precise molecular functions of Ruk/CIN85 in these processes remain largely elusive and further research is hampered by a lack of complete lists of its partner proteins. Results In the present study we employed a LC-MS/MS-based experimental pipeline to identify a considerable number (over 100) of proteins recruited by the SH3 domains of Ruk/CIN85 in vitro. Most of these identifications are novel Ruk/CIN85 interaction candidates. The identified proteins have diverse molecular architectures and can interact with other proteins, as well as with lipids and nucleic acids. Some of the identified proteins possess enzymatic activities. Functional profiling analyses and literature mining demonstrate that many of the proteins recruited by the SH3 domains of Ruk/CIN85 identified in this work were involved in the regulation of membranes and cytoskeletal structures necessary for vesicle-mediated transport and cancer cell invasiveness. Several groups of the proteins were also associated with few other cellular processes not previously related to Ruk/CIN85, most prominently with cell division. Conclusion Obtained data support the notion that Ruk/CIN85 regulates vesicle-mediated transport and cancer cell invasiveness through the assembly of multimeric protein complexes governing coordinated remodelling of membranes and underlying cytoskeletal structures, and imply its important roles in formation of coated vesicles and biogenesis of invadopodia. In addition, this study points to potential involvement of Ruk/CIN85 in other cellular processes, chiefly in cell division.
Collapse
|
36
|
Abstract
CtBPs (CtBP1 and CtBP2) act in the nucleus as transcriptional corepressors and in the cytoplasm as regulators of Golgi apparatus fission. Studies in which the expression or function of CtBPs has been inhibited have independently identified roles for CtBPs in both suppressing apoptosis and promoting cell cycle progression. Here, we have analyzed the consequences of ablating CtBP expression in breast cancer-derived cell lines. We found that loss of CtBP expression suppresses cell proliferation through a combination of apoptosis, reduction in cell cycle progression, and aberrations in transit through mitosis. The third phenotype includes errors in mitotic chromosome segregation that are associated with decreased association of the chromosome passenger protein aurora B with mitotic chromatin and that are likely to be a primary cause of the proapoptotic and antiproliferative effects of CtBP loss. We also show that loss of CtBP expression results in the activation of the transcription factor p53 and that loss of p53 function renders cells more susceptible to CtBP small interfering RNA-induced apoptosis.
Collapse
|
37
|
Abstract
The coat protein I (COPI) complex is considered to be one of the best-characterized coat complexes. Studies on how it functions in vesicle formation have provided seminal contributions to the general paradigm in vesicular transport that the ADP-ribosylation factor (ARF) small GTPases are key regulators of coat complexes. Here, we discuss emerging evidence that suggests the need to revise some long-held views on how COPI vesicle formation is achieved.
Collapse
|
38
|
Takahashi Y, Meyerkord CL, Wang HG. Bif-1/endophilin B1: a candidate for crescent driving force in autophagy. Cell Death Differ 2009; 16:947-55. [PMID: 19265852 DOI: 10.1038/cdd.2009.19] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Autophagy is an intracellular bulk degradation system that plays a vital role in maintaining cellular homeostasis. This degradation process involves dynamic membrane rearrangements resulting in the formation of double-membraned autophagosomes. However, the driving force for generating curvature and deformation of isolation membranes remains a mystery. Bax-interacting factor 1 (Bif-1), also known as SH3GLB1 or Endophilin B1, was originally discovered as a Bax-binding protein. Bif-1 contains an amino-terminal N-BAR (Bin-Amphiphysin-Rvs) domain and a carboxy-terminal SH3 (Src-homology 3) domain and shows membrane binding and bending activities. It has been shown that Beclin1 is involved in the nucleation of autophagosomal membranes through an unknown mechanism. It is interesting that, Bif-1 forms a complex with Beclin1 through ultraviolet irradiation resistant-associated gene (UVRAG) and promotes the activation of the class III PI3 kinase, Vps34, in mammalian cells. In response to nutrient starvation, Bif-1 accumulates in punctate foci where it co-localizes with LC3, Atg5, and Atg9. Furthermore, Bif-1-positive, crescent-shaped small vesicles expand by recruiting and fusing with Atg9-positive small membranes to complete autophagosome formation. This review highlights the role of Bif-1 in the regulation of autophagy and discusses the potential involvement of Bif-1 in the biogenesis of membranes for the formation of autophagosomes.
Collapse
Affiliation(s)
- Y Takahashi
- Department of Pharmacology and Penn State Hershey Cancer Institute, The Pennsylvania State University College of Medicine, Hershey, PA 17033-0850, USA
| | | | | |
Collapse
|
39
|
Chen N, Karantza-Wadsworth V. Role and regulation of autophagy in cancer. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1793:1516-23. [PMID: 19167434 DOI: 10.1016/j.bbamcr.2008.12.013] [Citation(s) in RCA: 279] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Revised: 12/19/2008] [Accepted: 12/20/2008] [Indexed: 01/10/2023]
Abstract
Autophagy is an evolutionarily conserved process whereby cytoplasm and cellular organelles are degraded in lysosomes for amino acid and energy recycling. Autophagy is a survival pathway activated in response to nutrient deprivation and other stressful stimuli, such as metabolic stress and exposure to anticancer drugs. However, autophagy may also result in cell death, if it proceeds to completion. Defective autophagy is implicated in tumorigenesis, as the essential autophagy regulator beclin 1 is monoallelically deleted in human breast, ovarian and prostate cancers, and beclin 1(+/-) mice are tumor-prone. How autophagy suppresses tumorigenesis is under intense investigation. Cell-autonomous mechanisms, involving protection of genome integrity and stability, and a non-cell-autonomous mechanism, involving suppression of necrosis and inflammation, have been discovered so far. The role of autophagy in treatment responsiveness is also complex. Autophagy inhibition concurrently with chemotherapy or radiotherapy has emerged as a novel approach in cancer treatment, as autophagy-competent tumor cells depend on autophagy for survival under drug- and radiation-induced stress. Alternatively, autophagy stimulation and preservation of cellular fitness by maintenance of protein and organelle quality control, suppression of DNA damage and genomic instability, and limitation of necrosis-associated inflammation may play a critical role in cancer prevention.
Collapse
Affiliation(s)
- Ning Chen
- University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854, USA
| | | |
Collapse
|
40
|
A role for the host coatomer and KDEL receptor in early vaccinia biogenesis. Proc Natl Acad Sci U S A 2008; 106:163-8. [PMID: 19109439 DOI: 10.1073/pnas.0811631106] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Members of the poxvirus family have been investigated for their applications as vaccines and expression vectors and, more recently, because of concern for their potential as biological weapons. Vaccinia virus, the prototypic member, evolves through multiple forms during its replication. Here, we show a surprising way by which vaccinia hijacks coatomer for early viral biogenesis. Whereas coatomer forms COPI vesicles in the host early secretory system, vaccinia formation bypasses this role of coatomer, but instead, depends on coatomer interacting with the host KDEL receptor. To gain insight into the viral roles of these two host proteins, we have detected them on the earliest recognized viral forms. These findings not only suggest insights into early vaccinia biogenesis but also reveal an alternate mechanism by which coatomer acts.
Collapse
|
41
|
Etxebarria A, Terrones O, Yamaguchi H, Landajuela A, Landeta O, Antonsson B, Wang HG, Basañez G. Endophilin B1/Bif-1 stimulates BAX activation independently from its capacity to produce large scale membrane morphological rearrangements. J Biol Chem 2008; 284:4200-12. [PMID: 19074440 DOI: 10.1074/jbc.m808050200] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Endophilin B1/BAX-interacting factor 1 (Bif-1) is a protein that cooperates with dynamin-like protein 1 (DLP1/Drp1) to maintain normal mitochondrial outer membrane (MOM) dynamics in healthy cells and also contributes to BAX-driven MOM permeabilization (MOMP), the irreversible commitment point to cell death for the majority of apoptotic stimuli. However, despite its importance, exactly how Bif-1 fulfils its proapoptotic role is unknown. Here, we demonstrate that the stimulatory effect of Bif-1 on BAX-driven MOMP and on BAX conformational activation observed in intact cells during apoptosis can be recapitulated in a simplified system consisting of purified proteins and MOM-like liposomes. In this reconstituted model system the N-BAR domain of Bif-1 reproduced the stimulatory effect of Bif-1 on functional BAX activation. This process was dependent on physical interaction between Bif-1 N-BAR and BAX as well as on the presence of the mitochondrion-specific lipid cardiolipin. Despite that Bif-1 N-BAR produced large scale morphological rearrangements in MOM-like liposomes, this phenomenon could be separated from functional BAX activation. Furthermore, DLP1 also caused global morphological changes in MOM-like liposomes, but DLP1 did not stimulate BAX-permeabilizing function in the absence or presence of Bif-1. Taken together, our findings not only provide direct evidence for a functional interplay between Bif-1, BAX, and cardiolipin during MOMP but also add significantly to the growing body of evidence indicating that components of the mitochondrial morphogenesis machinery possess proapoptotic functions that are independent from their recognized roles in normal mitochondrial dynamics.
Collapse
Affiliation(s)
- Aitor Etxebarria
- Unidad de Biofísica, Centro Mixto Consejo Superior de Investigaciones Cientificas, Universidad del Pais Vasco/Euskal Herriko Unibertsitatea, 48080 Bilbao, Spain
| | | | | | | | | | | | | | | |
Collapse
|
42
|
Asp L, Kartberg F, Fernandez-Rodriguez J, Smedh M, Elsner M, Laporte F, Bárcena M, Jansen KA, Valentijn JA, Koster AJ, Bergeron JJM, Nilsson T. Early stages of Golgi vesicle and tubule formation require diacylglycerol. Mol Biol Cell 2008; 20:780-90. [PMID: 19037109 DOI: 10.1091/mbc.e08-03-0256] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We have investigated the role for diacylglycerol (DAG) in membrane bud formation in the Golgi apparatus. Addition of propranolol to specifically inhibit phosphatidate phosphohydrolase (PAP), an enzyme responsible for converting phosphatidic acid into DAG, effectively prevents formation of membrane buds. The effect of PAP inhibition on Golgi membranes is rapid and occurs within 3 min. Removal of the PAP inhibitor then results in a rapid burst of buds, vesicles, and tubules that peaks within 2 min. The inability to form buds in the presence of propranolol does not appear to be correlated with a loss of ARFGAP1 from Golgi membranes, as knockdown of ARFGAP1 by RNA interference has little or no effect on actual bud formation. Rather, knockdown of ARFGAP1 results in an increase in membrane buds and a decrease of vesicles and tubules suggesting it functions in the late stages of scission. How DAG promotes bud formation is discussed.
Collapse
Affiliation(s)
- Lennart Asp
- Department of Medical and Clinical Genetics, the Sahlgrenska Academy at the University of Gothenburg, 405 30 Gothenburg, Sweden
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Salvarezza SB, Deborde S, Schreiner R, Campagne F, Kessels MM, Qualmann B, Caceres A, Kreitzer G, Rodriguez-Boulan E. LIM kinase 1 and cofilin regulate actin filament population required for dynamin-dependent apical carrier fission from the trans-Golgi network. Mol Biol Cell 2008; 20:438-51. [PMID: 18987335 DOI: 10.1091/mbc.e08-08-0891] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The functions of the actin cytoskeleton in post-Golgi trafficking are still poorly understood. Here, we report the role of LIM Kinase 1 (LIMK1) and its substrate cofilin in the trafficking of apical and basolateral proteins in Madin-Darby canine kidney cells. Our data indicate that LIMK1 and cofilin organize a specialized population of actin filaments at the Golgi complex that is selectively required for the emergence of an apical cargo route to the plasma membrane (PM). Quantitative pulse-chase live imaging experiments showed that overexpression of kinase-dead LIMK1 (LIMK1-KD), or of LIMK1 small interfering RNA, or of an activated cofilin mutant (cofilin S3A), selectively slowed down the exit from the trans-Golgi network (TGN) of the apical PM marker p75-green fluorescent protein (GFP) but did not interfere with the apical PM marker glycosyl phosphatidylinositol-YFP or the basolateral PM marker neural cell adhesion molecule-GFP. High-resolution live imaging experiments of carrier formation and release by the TGN and analysis of peri-Golgi actin dynamics using photoactivatable GFP suggest a scenario in which TGN-localized LIMK1-cofilin regulate a population of actin filaments required for dynamin-syndapin-cortactin-dependent generation and/or fission of precursors to p75 transporters.
Collapse
Affiliation(s)
- Susana B Salvarezza
- Margaret Dyson Vision Research Institute and Department of Cell and Developmental Biology, HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine, Weill Medical College of Cornell University, New York, NY 10065, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Yang JS, Gad H, Lee SY, Mironov A, Zhang L, Beznoussenko GV, Valente C, Turacchio G, Bonsra AN, Du G, Baldanzi G, Graziani A, Bourgoin S, Frohman MA, Luini A, Hsu VW. A role for phosphatidic acid in COPI vesicle fission yields insights into Golgi maintenance. Nat Cell Biol 2008; 10:1146-53. [PMID: 18776900 PMCID: PMC2756218 DOI: 10.1038/ncb1774] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Accepted: 08/19/2008] [Indexed: 01/30/2023]
Abstract
Proteins essential for vesicle formation by the Coat Protein I (COPI) complex are being identified, but less is known about the role of specific lipids. Brefeldin-A ADP-ribosylated substrate (BARS) functions in the fission step of COPI vesicle formation. Here, we show that BARS induces membrane curvature in cooperation with phosphatidic acid. This finding has allowed us to further delineate COPI vesicle fission into two sub-stages: 1) an earlier stage of bud-neck constriction, in which BARS and other COPI components are required, and 2) a later stage of bud-neck scission, in which phosphatidic acid generated by phospholipase D2 (PLD2) is also required. Moreover, in contrast to the disruption of the Golgi seen on perturbing the core COPI components (such as coatomer), inhibition of PLD2 causes milder disruptions, suggesting that such COPI components have additional roles in maintaining Golgi structure other than through COPI vesicle formation.
Collapse
Affiliation(s)
- Jia-Shu Yang
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, and Department of Medicine, Harvard Medical School, Boston, MA 02115 USA
| | - Helge Gad
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, 66030 Santa Maria Imbaro (Chieti), Italy
| | - Stella Y. Lee
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, and Department of Medicine, Harvard Medical School, Boston, MA 02115 USA
| | - Alexander Mironov
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, 66030 Santa Maria Imbaro (Chieti), Italy
| | - Leiliang Zhang
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, and Department of Medicine, Harvard Medical School, Boston, MA 02115 USA
| | - Galina V. Beznoussenko
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, 66030 Santa Maria Imbaro (Chieti), Italy
| | - Carmen Valente
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, 66030 Santa Maria Imbaro (Chieti), Italy
| | - Gabriele Turacchio
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, 66030 Santa Maria Imbaro (Chieti), Italy
| | - Akua N. Bonsra
- Department of Pharmacology and the Center for Developmental Genetics, Stony Brook University, Stony Brook, NY 11794
| | - Guangwei Du
- Department of Pharmacology and the Center for Developmental Genetics, Stony Brook University, Stony Brook, NY 11794
| | - Gianluca Baldanzi
- Department of Clinical and Experimental Medicine Università del Piemonte Orientale, 28100 Novara, Italy
| | - Andrea Graziani
- Department of Clinical and Experimental Medicine Università del Piemonte Orientale, 28100 Novara, Italy
| | - Sylvain Bourgoin
- Le Centre Hospitalier Universitaire de Quebec, pavillon CHUL, Rhumatologie et Immunology, Quebec, Canada G1V4G2
| | - Michael A. Frohman
- Department of Pharmacology and the Center for Developmental Genetics, Stony Brook University, Stony Brook, NY 11794
| | - Alberto Luini
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, 66030 Santa Maria Imbaro (Chieti), Italy
| | - Victor W. Hsu
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, and Department of Medicine, Harvard Medical School, Boston, MA 02115 USA
| |
Collapse
|
45
|
Yamaguchi H, Woods NT, Dorsey JF, Takahashi Y, Gjertsen NR, Yeatman T, Wu J, Wang HG. SRC directly phosphorylates Bif-1 and prevents its interaction with Bax and the initiation of anoikis. J Biol Chem 2008; 283:19112-8. [PMID: 18474606 DOI: 10.1074/jbc.m709882200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bif-1 interacts with Bax and enhances its conformational rearrangement, resulting in apoptosis. However, the molecular mechanism governing the interaction between Bif-1 and Bax is poorly defined. Here we provide evidence that Bif-1 is phosphorylated, an event that can be repressed by apoptotic stimuli. The protein kinase c-Src binds to and directly phosphorylates Bif-1 on tyrosine 80. Moreover, Src phosphorylation of Bif-1 suppresses the interaction between Bif-1 and Bax, resulting in the inhibition of Bax activation during anoikis. Together, these results suggest that phosphorylation of Bif-1 impairs its binding to Bax and represses apoptosis, providing another mechanism by which Src oncogenic signaling can prevent cell death.
Collapse
Affiliation(s)
- Hirohito Yamaguchi
- H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida 33612, USA
| | | | | | | | | | | | | | | |
Collapse
|
46
|
Levi S, Rawet M, Kliouchnikov L, Parnis A, Cassel D. Topology of Amphipathic Motifs Mediating Golgi Localization in ArfGAP1 and Its Splice Isoforms. J Biol Chem 2008; 283:8564-72. [DOI: 10.1074/jbc.m709738200] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
|
47
|
ARF1 is directly involved in dynamin-independent endocytosis. Nat Cell Biol 2007; 10:30-41. [PMID: 18084285 DOI: 10.1038/ncb1666] [Citation(s) in RCA: 161] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Accepted: 11/29/2007] [Indexed: 12/20/2022]
Abstract
Endocytosis of glycosylphosphatidyl inositol (GPI)-anchored proteins (GPI-APs) and the fluid phase takes place primarily through a dynamin- and clathrin-independent, Cdc42-regulated pinocytic mechanism. This mechanism is mediated by primary carriers called clathrin-independent carriers (CLICs), which fuse to form tubular early endocytic compartments called GPI-AP enriched endosomal compartments (GEECs). Here, we show that reduction in activity or levels of ARF1 specifically inhibits GPI-AP and fluid-phase endocytosis without affecting other clathrin-dependent or independent endocytic pathways. ARF1 is activated at distinct sites on the plasma membrane, and by the recruitment of RhoGAP domain-containing protein, ARHGAP10, to the plasma membrane, modulates cell-surface Cdc42 dynamics. This results in the coupling of ARF1 and Cdc42 activity to regulate endocytosis at the plasma membrane. These findings provide a molecular basis for a crosstalk of endocytosis with secretion by the sharing of a key regulator of secretory traffic, ARF1.
Collapse
|
48
|
GTP-independent rapid and slow endocytosis at a central synapse. Nat Neurosci 2007; 11:45-53. [PMID: 18066059 DOI: 10.1038/nn2021] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2007] [Accepted: 11/01/2007] [Indexed: 11/08/2022]
Abstract
Vesicle endocytosis is essential for maintaining synaptic transmission. Its key step, membrane scission, is thought to be mediated by the GTPase dynamin in all forms of endocytosis at synapses. Our findings indicate that GTP-independent and probably dynamin-independent endocytosis co-exist with GTP- and dynamin-dependent endocytosis at the same synaptic nerve terminal, the calyx of Held, in rats. This previously undescribed form of endocytosis could be slow (tens of seconds) and/or rapid (a few seconds), similar to GTP- and dynamin-dependent endocytosis. It was activated during intense stimulation, whereas GTP- and dynamin-dependent endocytosis dominated during mild stimulation. These results establish a new model, in which vesicles are divided into two pools depending on their requirement for GTP and dynamin for retrieval. The GTP- and dynamin-dependent pool has higher priority for release and retrieval, but limited capacity, saturation of which leads to release and thus retrieval of GTP- and dynamin-independent vesicles.
Collapse
|
49
|
Takahashi Y, Coppola D, Matsushita N, Cualing HD, Sun M, Sato Y, Liang C, Jung JU, Cheng JQ, Mulé JJ, Pledger WJ, Wang HG. Bif-1 interacts with Beclin 1 through UVRAG and regulates autophagy and tumorigenesis. Nat Cell Biol 2007; 9:1142-51. [PMID: 17891140 PMCID: PMC2254521 DOI: 10.1038/ncb1634] [Citation(s) in RCA: 673] [Impact Index Per Article: 39.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2007] [Accepted: 08/30/2007] [Indexed: 02/06/2023]
Abstract
Autophagy is an evolutionarily conserved 'self-eating' process. Although the genes essential for autophagy (named Atg) have been identified in yeast, the molecular mechanism of how Atg proteins control autophagosome formation in mammalian cells remains to be elucidated. Here, we demonstrate that Bif-1 (also known as Endophilin B1) interacts with Beclin 1 through ultraviolet irradiation resistance-associated gene (UVRAG) and functions as a positive mediator of the class III PI(3) kinase (PI(3)KC3). In response to nutrient deprivation, Bif-1 localizes to autophagosomes where it colocalizes with Atg5, as well as microtubule-associated protein light chain 3 (LC3). Furthermore, loss of Bif-1 suppresses autophagosome formation. Although the SH3 domain of Bif-1 is sufficient for binding to UVRAG, both the BAR and SH3 domains are required for Bif-1 to activate PI(3)KC3 and induce autophagosome formation. We also observed that Bif-1 ablation prolongs cell survival under starvation conditions. Moreover, knockout of Bif-1 significantly enhances the development of spontaneous tumours in mice. These findings suggest that Bif-1 joins the UVRAG-Beclin 1 complex as a potential activator of autophagy and tumour suppressor.
Collapse
Affiliation(s)
- Yoshinori Takahashi
- H. Lee Moffitt Cancer Center & Research Institute, 12902 Magnolia Drive. Tampa, FL 33612, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
50
|
Abstract
Membrane trafficking and remodeling of the actin cytoskeleton are critical activities contributing to cellular events that include cell growth, migration and tumor invasion. ADP-ribosylation factor (Arf)-directed GTPase activating proteins (GAPs) have crucial roles in these processes. The Arf GAPs function in part by regulating hydrolysis of GTP bound to Arf proteins. The Arf GAPs, which have multiple functional domains, also affect the actin cytoskeleton and membranes by specific interactions with lipids and proteins. A description of these interactions provides insights into the molecular mechanisms by which Arf GAPs regulate physiological and pathological cellular events. Here we describe the Arf GAP family and summarize the currently identified protein interactors in the context of known Arf GAP functions.
Collapse
Affiliation(s)
- Hiroki Inoue
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | | |
Collapse
|