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Zhang Y, Kunii M, Taniguchi M, Yoshimura SI, Harada A. Rab6-Mediated Polarized Transport of Synaptic Vesicle Precursors Is Essential for the Establishment of Neuronal Polarity and Brain Formation. J Neurosci 2024; 44:e2334232024. [PMID: 38830762 DOI: 10.1523/jneurosci.2334-23.2024] [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: 12/14/2023] [Revised: 05/13/2024] [Accepted: 05/26/2024] [Indexed: 06/05/2024] Open
Abstract
Neurons are highly polarized cells that are composed of a single axon and multiple dendrites. Axon-dendrite polarity is essential for proper tissue formation and brain functions. Intracellular protein transport plays an important role in the establishment of neuronal polarity. However, the regulatory mechanism of polarized transport remains unclear. Here, we show that Rab6, a small GTPase that acts on the regulation of intracellular vesicular trafficking, plays key roles in neuronal polarization and brain development. Central nervous system-specific Rab6a/b double knock-out (Rab6 DKO) mice of both sexes exhibit severe dysplasia of the neocortex and the cerebellum. In the Rab6 DKO neocortex, impaired axonal extension of neurons results in hypoplasia of the intermediate zone. In vitro, deletion of Rab6a and Rab6b in cultured neurons from both sexes causes the abnormal accumulation of synaptic vesicle precursors (SVPs) adjacent to the Golgi apparatus, which leads to defects in axonal extension and the loss of axon-dendrite polarity. Moreover, Rab6 DKO causes significant expansion of lysosomes in the soma in neurons. Overall, our results reveal that Rab6-mediated polarized transport of SVPs is crucial for neuronal polarization and subsequent brain formation.
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Affiliation(s)
- Yu Zhang
- Departments of Cell Biology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
| | - Masataka Kunii
- Departments of Cell Biology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
| | - Manabu Taniguchi
- Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
| | - Shin-Ichiro Yoshimura
- Departments of Cell Biology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
| | - Akihiro Harada
- Departments of Cell Biology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
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2
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Bergeman MH, Velarde K, Glenn HL, Hogue IB. Herpes Simplex Virus 1 (HSV-1) Uses the Rab6 Post-Golgi Secretory Pathway For Viral Egress. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.13.571414. [PMID: 38168379 PMCID: PMC10760111 DOI: 10.1101/2023.12.13.571414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Herpes Simplex Virus 1 (HSV-1) is an alpha herpesvirus that infects a majority of the world population. The mechanisms and cellular host factors involved in the intracellular transport and exocytosis of HSV-1 particles are not fully understood. To elucidate these late steps in the replication cycle, we developed a live-cell fluorescence microscopy assay of HSV-1 virion intracellular trafficking and exocytosis. This method allows us to track individual virus particles, and identify the precise moment and location of particle exocytosis using a pH-sensitive reporter. We show that HSV-1 uses the host Rab6 post-Golgi secretory pathway during egress. The small GTPase, Rab6, binds to nascent secretory vesicles at the trans-Golgi network and regulates vesicle trafficking and exocytosis at the plasma membrane. HSV-1 particles colocalize with Rab6a in the region of the Golgi, cotraffic with Rab6a to the cell periphery, and undergo exocytosis from Rab6a vesicles. Consistent with previous reports, we find that HSV-1 particles accumulate at preferential egress sites in infected cells. The Rab6a secretory pathway mediates this preferential/polarized egress, since Rab6a vesicles accumulate near the plasma membrane similarly in uninfected cells. These data suggest that, following particle envelopment, HSV-1 egress follows a pre-existing cellular secretory pathway to exit infected cells rather than novel, virus-induced mechanisms.
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Affiliation(s)
- Melissa H. Bergeman
- ASU-Banner Neurodegenerative Disease Research Center, Arizona State University
- School of Life Sciences, Arizona State University, Tempe, Arizona
| | - Kimberly Velarde
- School of Life Sciences, Arizona State University, Tempe, Arizona
| | - Honor L. Glenn
- Center for Structural Discovery, Biodesign Institute, Arizona State University
| | - Ian B. Hogue
- ASU-Banner Neurodegenerative Disease Research Center, Arizona State University
- School of Life Sciences, Arizona State University, Tempe, Arizona
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3
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Jin G, Lin L, Li K, Li J, Yu C, Wei Z. Structural basis of ELKS/Rab6B interaction and its role in vesicle capturing enhanced by liquid-liquid phase separation. J Biol Chem 2023:104808. [PMID: 37172719 DOI: 10.1016/j.jbc.2023.104808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 04/29/2023] [Accepted: 05/04/2023] [Indexed: 05/15/2023] Open
Abstract
ELKS proteins play a key role in organizing intracellular vesicle trafficking and targeting in both neurons and non-neuronal cells. While it is known that ELKS interacts with the vesicular traffic regulator, the Rab6 GTPase, the molecular basis governing ELKS-mediated trafficking of Rab6-coated vesicles has remained unclear. In this study, we solved the Rab6B structure in complex with the Rab6-binding domain of ELKS1, revealing that a C-terminal segment of ELKS1 forms a helical hairpin to recognize Rab6B through a unique binding mode. We further showed that liquid-liquid phase separation (LLPS) of ELKS1 allows it to compete with other Rab6 effectors for binding to Rab6B and accumulate Rab6B-coated liposomes to the protein condensate formed by ELKS1. We also found that the ELKS1 condensate recruits Rab6B-coated vesicles to vesicle releasing sites and promotes vesicle exocytosis. Together, our structural, biochemical, and cellular analyses suggest that ELKS1, via the LLPS-enhanced interaction with Rab6, captures Rab6-coated vesicles from the cargo transport machine for efficient vesicle releasing at exocytotic sites. These findings shed new light on the understanding of spatiotemporal regulation of vesicle trafficking through the interplay between membranous structures and membraneless condensates.
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Affiliation(s)
- Gaowei Jin
- Brain Research Center, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Leishu Lin
- Brain Research Center, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Kaiyue Li
- Brain Research Center, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Jiashan Li
- Brain Research Center, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Cong Yu
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, and Shenzhen Key Laboratory of Cell Microenvironment, Shenzhen, Guangdong, China 518055.
| | - Zhiyi Wei
- Brain Research Center, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.
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4
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Li W, Ji R, Lin Y, Cheng X, Tang Z, He H, Zhang L, Qin J, Tian M, Jin G, Zhang X. miR-6216 Regulates Neural Stem Cell Proliferation by Targeting RAB6B. Neurosci Res 2023:S0168-0102(23)00073-1. [PMID: 37059126 DOI: 10.1016/j.neures.2023.04.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 03/16/2023] [Accepted: 04/11/2023] [Indexed: 04/16/2023]
Abstract
Neural stem cells (NSCs) are a class of self-renewing, multipotent and undifferentiated progenitor cells that retain the capacity to both glial and neuronal lineages. MicroRNAs (miRNAs) are small non-coding RNAs that play an important role in stem cell fate determination and self-renewal. Our previous RNA-seq data indicated that the expression of miR-6216 was decreased in denervated hippocampal exosomes compared with normal. However, whether miR-6216 participates in regulating NSC function remains to be elucidated. In this study, we demonstrated that miR-6216 negatively regulates RAB6B expression. Forced overexpression of miR-6216 inhibited NSC proliferation, and overexpression of RAB6B promoted NSC proliferation. These findings suggest that miR-6216 played an important role in regulating NSC proliferation via targeting RAB6B, and improve the understanding of the miRNA-mRNA regulatory network that affects NSC proliferation.
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Affiliation(s)
- Wen Li
- Department of Human Anatomy, Institute of Neurobiology, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Co-Innovation Center of Neuroregeneration, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Key Laboratory of Neuroregeneration of Jiangsu Province and Ministry of Education, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China
| | - Ruijie Ji
- Department of Human Anatomy, Institute of Neurobiology, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Co-Innovation Center of Neuroregeneration, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China
| | - Yujian Lin
- Department of Human Anatomy, Institute of Neurobiology, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Co-Innovation Center of Neuroregeneration, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Key Laboratory of Neuroregeneration of Jiangsu Province and Ministry of Education, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China
| | - Xiang Cheng
- Department of Human Anatomy, Institute of Neurobiology, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Co-Innovation Center of Neuroregeneration, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Key Laboratory of Neuroregeneration of Jiangsu Province and Ministry of Education, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China
| | - Zixin Tang
- Department of Human Anatomy, Institute of Neurobiology, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Co-Innovation Center of Neuroregeneration, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Key Laboratory of Neuroregeneration of Jiangsu Province and Ministry of Education, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China
| | - Hui He
- Department of Human Anatomy, Institute of Neurobiology, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Co-Innovation Center of Neuroregeneration, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Key Laboratory of Neuroregeneration of Jiangsu Province and Ministry of Education, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China
| | - Lei Zhang
- Department of Human Anatomy, Institute of Neurobiology, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Co-Innovation Center of Neuroregeneration, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Key Laboratory of Neuroregeneration of Jiangsu Province and Ministry of Education, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China
| | - Jianbing Qin
- Department of Human Anatomy, Institute of Neurobiology, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Co-Innovation Center of Neuroregeneration, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Key Laboratory of Neuroregeneration of Jiangsu Province and Ministry of Education, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China
| | - Meiling Tian
- Department of Human Anatomy, Institute of Neurobiology, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Co-Innovation Center of Neuroregeneration, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Key Laboratory of Neuroregeneration of Jiangsu Province and Ministry of Education, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China
| | - Guohua Jin
- Department of Human Anatomy, Institute of Neurobiology, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Co-Innovation Center of Neuroregeneration, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Key Laboratory of Neuroregeneration of Jiangsu Province and Ministry of Education, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China
| | - Xinhua Zhang
- Department of Human Anatomy, Institute of Neurobiology, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Co-Innovation Center of Neuroregeneration, Nantong University, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China; Key Laboratory of Neuroregeneration of Jiangsu Province and Ministry of Education, No.19 Qixiu Road, No.3 Building of Qixiu Campus, Nantong 226001, Jiangsu, PR China.
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5
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Nik Akhtar S, Bunner WP, Brennan E, Lu Q, Szatmari EM. Crosstalk between the Rho and Rab family of small GTPases in neurodegenerative disorders. Front Cell Neurosci 2023; 17:1084769. [PMID: 36779014 PMCID: PMC9911442 DOI: 10.3389/fncel.2023.1084769] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 01/06/2023] [Indexed: 01/28/2023] Open
Abstract
Neurodegeneration is associated with defects in cytoskeletal dynamics and dysfunctions of the vesicular trafficking and sorting systems. In the last few decades, studies have demonstrated that the key regulators of cytoskeletal dynamics are proteins from the Rho family GTPases, meanwhile, the central hub for vesicle sorting and transport between target membranes is the Rab family of GTPases. In this regard, the role of Rho and Rab GTPases in the induction and maintenance of distinct functional and morphological neuronal domains (such as dendrites and axons) has been extensively studied. Several members belonging to these two families of proteins have been associated with many neurodegenerative disorders ranging from dementia to motor neuron degeneration. In this analysis, we attempt to present a brief review of the potential crosstalk between the Rab and Rho family members in neurodegenerative pathologies such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington disease, and amyotrophic lateral sclerosis (ALS).
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Affiliation(s)
- Shayan Nik Akhtar
- The Harriet and John Wooten Laboratory for Alzheimer’s and Neurodegenerative Diseases Research, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Wyatt P. Bunner
- Laboratory of Neuroscience, Department of Physical Therapy, College of Allied Health Sciences, East Carolina University, Greenville, NC, United States
| | - Elizabeth Brennan
- Laboratory of Neuroscience, Department of Physical Therapy, College of Allied Health Sciences, East Carolina University, Greenville, NC, United States
| | - Qun Lu
- The Harriet and John Wooten Laboratory for Alzheimer’s and Neurodegenerative Diseases Research, Brody School of Medicine, East Carolina University, Greenville, NC, United States,*Correspondence: Erzsebet M. Szatmari Qun Lu
| | - Erzsebet M. Szatmari
- Laboratory of Neuroscience, Department of Physical Therapy, College of Allied Health Sciences, East Carolina University, Greenville, NC, United States,*Correspondence: Erzsebet M. Szatmari Qun Lu
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6
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Oh RY, Deshwar AR, Marwaha A, Sabha N, Tropak M, Hou H, Yuki KE, Wilson MD, Rump P, Lunsing R, Elserafy N, Chung CWT, Hewson S, Klein-Rodewald T, Calzada-Wack J, Sanz-Moreno A, Kraiger M, Marschall S, Fuchs H, Gailus-Durner V, Hrabe de Angelis M, Dowling J, Schulze A. Biallelic loss-of-function variants in RABGAP1 cause a novel neurodevelopmental syndrome. Genet Med 2022; 24:2399-2407. [PMID: 36083289 DOI: 10.1016/j.gim.2022.07.024] [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: 06/06/2022] [Revised: 07/25/2022] [Accepted: 07/26/2022] [Indexed: 11/17/2022] Open
Abstract
PURPOSE RABGAP1 is a GTPase-activating protein implicated in a variety of cellular and molecular processes, including mitosis, cell migration, vesicular trafficking, and mTOR signaling. There are no known Mendelian diseases caused by variants in RABGAP1. METHODS Through GeneMatcher, we identified 5 patients from 3 unrelated families with homozygous variants in the RABGAP1 gene found on exome sequencing. We established lymphoblastoid cells lines derived from an affected individual and her parents and performed RNA sequencing and functional studies. Rabgap1 knockout mice were generated and phenotyped. RESULTS We report 5 patients presenting with a common constellation of features, including global developmental delay/intellectual disability, microcephaly, bilateral sensorineural hearing loss, and seizures, as well as overlapping dysmorphic features. Neuroimaging revealed common features, including delayed myelination, white matter volume loss, ventriculomegaly, and thinning of the corpus callosum. Functional analysis of patient cells revealed downregulated mTOR signaling and abnormal localization of early endosomes and lysosomes. Rabgap1 knockout mice exhibited several features in common with the patient cohort, including microcephaly, thinning of the corpus callosum, and ventriculomegaly. CONCLUSION Collectively, our results provide evidence of a novel neurodevelopmental syndrome caused by biallelic loss-of-function variants in RABGAP1.
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Affiliation(s)
- Rachel Youjin Oh
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Ashish R Deshwar
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, Toronto, Ontario, Canada; Program in Genetics and Genome Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Ashish Marwaha
- Department of Medical Genetics, University of Calgary, Calgary, Alberta, Canada
| | - Nesrin Sabha
- Program in Genetics and Genome Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Michael Tropak
- Program in Genetics and Genome Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Huayun Hou
- Program in Genetics and Genome Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Kyoko E Yuki
- Program in Genetics and Genome Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Michael D Wilson
- Program in Genetics and Genome Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Patrick Rump
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Roelineke Lunsing
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Noha Elserafy
- Department of Clinical Genetics, Liverpool Hospital, Sydney, New South Wales, Australia
| | - Clara W T Chung
- Department of Clinical Genetics, Liverpool Hospital, Sydney, New South Wales, Australia; School of Women's and Children's Health, University of New South Wales, Sydney, New South Wales, Australia
| | - Stacy Hewson
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Tanja Klein-Rodewald
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstaedter Landstraße, Neuherberg, Germany
| | - Julia Calzada-Wack
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstaedter Landstraße, Neuherberg, Germany
| | - Adrián Sanz-Moreno
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstaedter Landstraße, Neuherberg, Germany
| | - Markus Kraiger
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstaedter Landstraße, Neuherberg, Germany
| | - Susan Marschall
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstaedter Landstraße, Neuherberg, Germany
| | - Helmut Fuchs
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstaedter Landstraße, Neuherberg, Germany
| | - Valerie Gailus-Durner
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstaedter Landstraße, Neuherberg, Germany
| | - Martin Hrabe de Angelis
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstaedter Landstraße, Neuherberg, Germany; Chair of Experimental Genetics, TUM School of Life Sciences, Technische Universität München, Freising, Germany; German Center for Diabetes Research (DZD), Ingolstaedter Landstraße, Neuherberg, Germany
| | - James Dowling
- Program in Genetics and Genome Biology, Hospital for Sick Children, Toronto, Ontario, Canada; Division of Neurology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Andreas Schulze
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, Toronto, Ontario, Canada; Program in Genetics and Genome Biology, Hospital for Sick Children, Toronto, Ontario, Canada; Departments of Paediatrics and Biochemistry, University of Toronto, Toronto, Ontario, Canada.
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7
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Peng H, Zhu E, Wang J, Du X, Wang C, Yang M, Zhang Y. RAB6B is a potential prognostic marker and correlated with the remolding of tumor immune microenvironment in hepatocellular carcinoma. Front Pharmacol 2022; 13:989655. [PMID: 36120364 PMCID: PMC9478551 DOI: 10.3389/fphar.2022.989655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 08/15/2022] [Indexed: 11/13/2022] Open
Abstract
Backgrounds: Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and the second leading cause of death among all cancers. The Ras-associated binding (Rab) proteins constitute the largest family of the Ras superfamily of small GTPases, which mainly mediate membrane trafficking processes. RAB6B is a member of Rab GTPases, and it has been found to be dysregulated in various tumors. However, the clinical significance, correlations with immune cells, and stroma infiltration of RAB6B in HCC remain unclear.Methods: RAB6B mRNA and protein expression in HCC were examined using the TIMER, HCCDB, UALCAN, and HPA databases. The genetic alterations of RAB6B were analyzed by cBioPortal and COSMIC databases. The correlations between RAB6B and tumor-infiltrating immune cells and cancer-associated fibroblasts were explored by using TIMER, TISIDB, and GEPIA databases. Co-expression networks of RAB6B were investigated based on LinkedOmics. Drug sensitivity was analyzed through the GDSC and CTRP databases. RAB6B was knocked down with siRNA in HCC cell lines. EdU assay was performed to detect the cell proliferation ability, flow cytometry was used to compare the differences in the ability of apoptosis, and MTT was used to evaluate the drug sensitivity in vitro.Results: RAB6B mRNA and protein expression were upregulated in the HCC tissues. Kaplan–Meier and Cox regression analyses suggested that highly expressed RAB6B was an independent prognostic factor for poor survival in HCC patients. Moreover, we found that RAB6B expression was positively correlated with the infiltration of immune cells in HCC, including some immunosuppressive cells, chemokines, and receptors, meanwhile RAB6B expression was associated with CD8+T cells exhaustion, resulting in an immunosuppressive microenvironment. Additionally, functional enrichment analysis indicated that RAB6B may be involved in ECM remodeling in the TME, and RAB6B expression was positively associated with CAFs infiltration. Furthermore, RAB6B presented a positive association with sensitivity to GDSC and CTRP drugs. RAB6B knockdown inhibited the cell proliferation and promoted apoptosis and sensitivity to cisplatin of HCC cells in vitro.Conclusion: Our study revealed that RAB6B is a potential biomarker for poor prognosis in HCC patients and correlates with the formation of the immunosuppressive microenvironment in HCC.
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Affiliation(s)
- Hao Peng
- Medical School, Southeast University, Nanjing, China
| | - Erwei Zhu
- The Second People’s Hospital of Lianyungang (The Oncology Hospital of Lianyungang), Lianyungang, China
| | - Jitao Wang
- Medical School, Southeast University, Nanjing, China
- Xingtai Institute of Cancer Control, Xingtai People’s Hospital, Xingtai, China
| | - Xuanlong Du
- Medical School, Southeast University, Nanjing, China
| | - Chonggao Wang
- Medical School, Southeast University, Nanjing, China
| | - Meng Yang
- State Key Laboratory of Complex Severe and Rare Diseases, Department of Ultrasound, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
- *Correspondence: Meng Yang, ; Yewei Zhang,
| | - Yewei Zhang
- Hepatopancreatobiliary Center, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China
- *Correspondence: Meng Yang, ; Yewei Zhang,
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8
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Brault J, Bardin S, Lampic M, Carpentieri JA, Coquand L, Penisson M, Lachuer H, Victoria GS, Baloul S, El Marjou F, Boncompain G, Miserey‐Lenkei S, Belvindrah R, Fraisier V, Francis F, Perez F, Goud B, Baffet AD. RAB6
and dynein drive
post‐Golgi
apical transport to prevent neuronal progenitor delamination. EMBO Rep 2022; 23:e54605. [PMID: 35979738 PMCID: PMC9535803 DOI: 10.15252/embr.202254605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 07/18/2022] [Accepted: 07/25/2022] [Indexed: 12/03/2022] Open
Abstract
Radial glial (RG) cells are the neural stem cells of the developing neocortex. Apical RG (aRG) cells can delaminate to generate basal RG (bRG) cells, a cell type associated with human brain expansion. Here, we report that aRG delamination is regulated by the post‐Golgi secretory pathway. Using in situ subcellular live imaging, we show that post‐Golgi transport of RAB6+ vesicles occurs toward the minus ends of microtubules and depends on dynein. We demonstrate that the apical determinant Crumbs3 (CRB3) is also transported by dynein. Double knockout of RAB6A/A' and RAB6B impairs apical localization of CRB3 and induces a retraction of aRG cell apical process, leading to delamination and ectopic division. These defects are phenocopied by knockout of the dynein activator LIS1. Overall, our results identify a RAB6‐dynein‐LIS1 complex for Golgi to apical surface transport in aRG cells, and highlights the role of this pathway in the maintenance of neuroepithelial integrity.
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Affiliation(s)
| | - Sabine Bardin
- Institut Curie PSL Research University, CNRS UMR144 Paris France
| | - Marusa Lampic
- Institut Curie PSL Research University, CNRS UMR144 Paris France
| | | | - Laure Coquand
- Institut Curie PSL Research University, CNRS UMR144 Paris France
- Sorbonne University Paris France
| | - Maxime Penisson
- Sorbonne University Paris France
- INSERM UMR‐S 1270 Paris France
- Institut du Fer à Moulin Paris France
| | - Hugo Lachuer
- Institut Curie PSL Research University, CNRS UMR144 Paris France
| | | | - Sarah Baloul
- Institut Curie PSL Research University, CNRS UMR144 Paris France
| | - Fatima El Marjou
- Institut Curie PSL Research University, CNRS UMR144 Paris France
| | | | | | - Richard Belvindrah
- Sorbonne University Paris France
- INSERM UMR‐S 1270 Paris France
- Institut du Fer à Moulin Paris France
| | - Vincent Fraisier
- UMR 144‐Cell and Tissue Imaging Facility (PICT‐IBiSA) CNRS‐Institut Curie Paris France
| | - Fiona Francis
- Sorbonne University Paris France
- INSERM UMR‐S 1270 Paris France
- Institut du Fer à Moulin Paris France
| | - Franck Perez
- Institut Curie PSL Research University, CNRS UMR144 Paris France
| | - Bruno Goud
- Institut Curie PSL Research University, CNRS UMR144 Paris France
| | - Alexandre D Baffet
- Institut Curie PSL Research University, CNRS UMR144 Paris France
- Institut National de la Santé et de la Recherche Médicale (INSERM) Paris France
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9
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Domínguez Cadena LC, Schultz TE, Zamoshnikova A, Donovan ML, Mathmann CD, Yu CH, Mori G, Stow JL, Blumenthal A. Rab6b localizes to the Golgi complex in murine macrophages and promotes tumor necrosis factor release in response to mycobacterial infection. Immunol Cell Biol 2021; 99:1067-1076. [PMID: 34555867 DOI: 10.1111/imcb.12503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 08/27/2021] [Accepted: 09/21/2021] [Indexed: 11/30/2022]
Abstract
The proinflammatory cytokine tumor necrosis factor (TNF) plays a central role in the host control of mycobacterial infections. Expression and release of TNF are tightly regulated, yet the molecular mechanisms that control the release of TNF by mycobacteria-infected host cells, in particular macrophages, are incompletely understood. Rab GTPases direct the transport of intracellular membrane-enclosed vesicles and are important regulators of macrophage cytokine secretion. Rab6b is known to be predominantly expressed in the brain where it functions in retrograde transport and anterograde vesicle transport for exocytosis. Whether it executes similar functions in the context of immune responses is unknown. Here we show that Rab6b is expressed by primary mouse macrophages, where it localized to the Golgi complex. Infection with Mycobacterium bovis bacille Calmette-Guérin (BCG) resulted in dynamic changes in Rab6b expression in primary mouse macrophages in vitro as well as in organs from infected mice in vivo. We further show that Rab6b facilitated TNF release by M. bovis BCG-infected macrophages, in the absence of discernible impact on Tnf messenger RNA and intracellular TNF protein expression. Our observations identify Rab6b as a positive regulator of M. bovis BCG-induced TNF trafficking and secretion by macrophages and positions Rab6b among the molecular machinery that orchestrates inflammatory cytokine responses by macrophages.
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Affiliation(s)
- Leslie C Domínguez Cadena
- The University of Queensland Diamantina Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Thomas E Schultz
- The University of Queensland Diamantina Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Alina Zamoshnikova
- The University of Queensland Diamantina Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Meg L Donovan
- The University of Queensland Diamantina Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Carmen D Mathmann
- The University of Queensland Diamantina Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Chien-Hsiung Yu
- The University of Queensland Diamantina Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Giorgia Mori
- The University of Queensland Diamantina Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Jennifer L Stow
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Antje Blumenthal
- The University of Queensland Diamantina Institute, The University of Queensland, Brisbane, QLD, Australia
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10
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Guo L, Ren H, Fan S, Guan H, Wang J. Autoantibody against the Rab6A/Rab6B in primary autoimmune cerebellar ataxia associated with Sjogren's syndrome: A case report. J Neuroimmunol 2021; 359:577667. [PMID: 34332492 DOI: 10.1016/j.jneuroim.2021.577667] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 07/15/2021] [Accepted: 07/17/2021] [Indexed: 12/31/2022]
Abstract
In the current study we report a novel autoantibody against Purkinje cells in a patient with primary autoimmune cerebellar ataxia (PACA) associated with Sjogren's syndrome (SS). Tissue-based indirect immunofluorescence assay (TBA) of the patient's serum and cerebrospinal fluid (CSF) revealed IgG antibody to Purkinje cells and the granular layer of the rat cerebellum. Rab6A was identified as autoantigen by mass spectrometry (MS) and Western blotting, and the interactions between Rab6A or its homologous Rab6B and autoantibody in patient serum were verified by recombinant cell-based assay (CBA) and neutralization experiments. This autoantibody may represent a novel biomarker in the diagnosis of PACA.
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Affiliation(s)
- Liyuan Guo
- CAS Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China; Department of Psychology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Haitao Ren
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Siyuan Fan
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Hongzhi Guan
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
| | - Jing Wang
- CAS Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China; Department of Psychology, University of Chinese Academy of Sciences, Beijing 100049, China.
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11
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Hakobyan S, Loeffler-Wirth H, Arakelyan A, Binder H, Kunz M. A Transcriptome-Wide Isoform Landscape of Melanocytic Nevi and Primary Melanomas Identifies Gene Isoforms Associated with Malignancy. Int J Mol Sci 2021; 22:ijms22137165. [PMID: 34281234 PMCID: PMC8268681 DOI: 10.3390/ijms22137165] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/22/2021] [Accepted: 06/28/2021] [Indexed: 12/12/2022] Open
Abstract
Genetic splice variants have become of central interest in recent years, as they play an important role in different cancers. Little is known about splice variants in melanoma. Here, we analyzed a genome-wide transcriptomic dataset of benign melanocytic nevi and primary melanomas (n = 80) for the expression of specific splice variants. Using kallisto, a map for differentially expressed splice variants in melanoma vs. benign melanocytic nevi was generated. Among the top genes with differentially expressed splice variants were Ras-related in brain 6B (RAB6B), a member of the RAS family of GTPases, Macrophage Scavenger Receptor 1 (MSR1), Collagen Type XI Alpha 2 Chain (COLL11A2), and LY6/PLAUR Domain Containing 1 (LYPD1). The Gene Ontology terms of differentially expressed splice variants showed no enrichment for functional gene sets of melanoma vs. nevus lesions, but between type 1 (pigmentation type) and type 2 (immune response type) melanocytic lesions. A number of genes such as Checkpoint Kinase 1 (CHEK1) showed an association of mutational patterns and occurrence of splice variants in melanoma. Moreover, mutations in genes of the splicing machinery were common in both benign nevi and melanomas, suggesting a common mechanism starting early in melanoma development. Mutations in some of these genes of the splicing machinery, such as Serine and Arginine Rich Splicing Factor A3 and B3 (SF3A3, SF3B3), were significantly enriched in melanomas as compared to benign nevi. Taken together, a map of splice variants in melanoma is presented that shows a multitude of differentially expressed splice genes between benign nevi and primary melanomas. The underlying mechanisms may involve mutations in genes of the splicing machinery.
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Affiliation(s)
- Siras Hakobyan
- Institute of Molecular Biology NAS RA, Yerevan 0014, Armenia; (S.H.); (A.A.)
| | - Henry Loeffler-Wirth
- Interdisciplinary Centre for Bioinformatics, University of Leipzig, Härtelstr. 16–18, 04107 Leipzig, Germany; (H.L.-W.); (H.B.)
| | - Arsen Arakelyan
- Institute of Molecular Biology NAS RA, Yerevan 0014, Armenia; (S.H.); (A.A.)
| | - Hans Binder
- Interdisciplinary Centre for Bioinformatics, University of Leipzig, Härtelstr. 16–18, 04107 Leipzig, Germany; (H.L.-W.); (H.B.)
| | - Manfred Kunz
- Department of Dermatology, Venereology and Allergology, University of Leipzig Medical Center, Philipp-Rosenthal-Str. 23, 04103 Leipzig, Germany
- Correspondence: ; Tel.: +49-341-9718610; Fax: +49-341-9718609
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12
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Nyitrai H, Wang SSH, Kaeser PS. ELKS1 Captures Rab6-Marked Vesicular Cargo in Presynaptic Nerve Terminals. Cell Rep 2021; 31:107712. [PMID: 32521280 PMCID: PMC7360120 DOI: 10.1016/j.celrep.2020.107712] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 04/07/2020] [Accepted: 05/06/2020] [Indexed: 11/28/2022] Open
Abstract
Neurons face unique transport challenges. They need to deliver cargo over long axonal distances and to many presynaptic nerve terminals. Rab GTPases are master regulators of vesicular traffic, but essential presynaptic Rabs have not been identified. Here, we find that Rab6, a Golgi-derived GTPase for constitutive secretion, associates with mobile axonal cargo and localizes to nerve terminals. ELKS1 is a stationary presynaptic protein with Golgin homology that binds to Rab6. Knockout and rescue experiments for ELKS1 and Rab6 establish that ELKS1 captures Rab6 cargo. The ELKS1-Rab6-capturing mechanism can be transferred to mitochondria by mistargeting ELKS1 or Rab6 to them. We conclude that nerve terminals have repurposed mechanisms from constitutive exocytosis for their highly regulated secretion. By employing Golgin-like mechanisms with anchored ELKS extending its coiled-coils to capture Rab6 cargo, they have spatially separated cargo capture from fusion. ELKS complexes connect to active zones and may mediate vesicle progression toward release sites.
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Affiliation(s)
- Hajnalka Nyitrai
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Shan Shan H Wang
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Pascal S Kaeser
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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13
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Schwab N, Ju Y, Hazrati LN. Early onset senescence and cognitive impairment in a murine model of repeated mTBI. Acta Neuropathol Commun 2021; 9:82. [PMID: 33964983 PMCID: PMC8106230 DOI: 10.1186/s40478-021-01190-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 05/03/2021] [Indexed: 12/19/2022] Open
Abstract
Mild traumatic brain injury (mTBI) results in broad neurological symptoms and an increased risk of being diagnosed with a neurodegenerative disease later in life. While the immediate oxidative stress response and post-mortem pathology of the injured brain has been well studied, it remains unclear how early pathogenic changes may drive persistent symptoms and confer susceptibility to neurodegeneration. In this study we have used a mouse model of repeated mTBI (rmTBI) to identify early gene expression changes at 24 h or 7 days post-injury (7 dpi). At 24 h post-injury, gene expression of rmTBI mice shows activation of the DNA damage response (DDR) towards double strand DNA breaks, altered calcium and cell–cell signalling, and inhibition of cell death pathways. By 7 dpi, rmTBI mice had a gene expression signature consistent with induction of cellular senescence, activation of neurodegenerative processes, and inhibition of the DDR. At both timepoints gliosis, microgliosis, and axonal damage were evident in the absence of any gross lesion, and by 7 dpi rmTBI also mice had elevated levels of IL1β, p21, 53BP1, DNA2, and p53, supportive of DNA damage-induced cellular senescence. These gene expression changes reflect establishment of processes usually linked to brain aging and suggests that cellular senescence occurs early and most likely prior to the accumulation of toxic proteins. These molecular changes were accompanied by spatial learning and memory deficits in the Morris water maze. To conclude, we have identified DNA damage-induced cellular senescence as a repercussion of repeated mild traumatic brain injury which correlates with cognitive impairment. Pathways involved in senescence may represent viable treatment targets of post-concussive syndrome. Senescence has been proposed to promote neurodegeneration and appears as an effective target to prevent long-term complications of mTBI, such as chronic traumatic encephalopathy and other related neurodegenerative pathologies.
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14
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He Q, Li Z, Yin J, Li Y, Yin Y, Lei X, Zhu W. Prognostic Significance of Autophagy-Relevant Gene Markers in Colorectal Cancer. Front Oncol 2021; 11:566539. [PMID: 33937013 PMCID: PMC8081889 DOI: 10.3389/fonc.2021.566539] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 03/22/2021] [Indexed: 12/22/2022] Open
Abstract
Background Colorectal cancer (CRC) is a common malignant solid tumor with an extremely low survival rate after relapse. Previous investigations have shown that autophagy possesses a crucial function in tumors. However, there is no consensus on the value of autophagy-associated genes in predicting the prognosis of CRC patients. This work screens autophagy-related markers and signaling pathways that may participate in the development of CRC, and establishes a prognostic model of CRC based on autophagy-associated genes. Methods Gene transcripts from the TCGA database and autophagy-associated gene data from the GeneCards database were used to obtain expression levels of autophagy-associated genes, followed by Wilcox tests to screen for autophagy-related differentially expressed genes. Then, 11 key autophagy-associated genes were identified through univariate and multivariate Cox proportional hazard regression analysis and used to establish prognostic models. Additionally, immunohistochemical and CRC cell line data were used to evaluate the results of our three autophagy-associated genes EPHB2, NOL3, and SNAI1 in TCGA. Based on the multivariate Cox analysis, risk scores were calculated and used to classify samples into high-risk and low-risk groups. Kaplan-Meier survival analysis, risk profiling, and independent prognosis analysis were carried out. Receiver operating characteristic analysis was performed to estimate the specificity and sensitivity of the prognostic model. Finally, GSEA, GO, and KEGG analysis were performed to identify the relevant signaling pathways. Results A total of 301 autophagy-related genes were differentially expressed in CRC. The areas under the 1-year, 3-year, and 5-year receiver operating characteristic curves of the autophagy-based prognostic model for CRC were 0.764, 0.751, and 0.729, respectively. GSEA analysis of the model showed significant enrichment in several tumor-relevant pathways and cellular protective biological processes. The expression of EPHB2, IL-13, MAP2, RPN2, and TRAF5 was correlated with microsatellite instability (MSI), while the expression of IL-13, RPN2, and TRAF5 was related to tumor mutation burden (TMB). GO analysis showed that the 11 target autophagy genes were chiefly enriched in mRNA processing, RNA splicing, and regulation of the mRNA metabolic process. KEGG analysis showed enrichment mainly in spliceosomes. We constructed a prognostic risk assessment model based on 11 autophagy-related genes in CRC. Conclusion A prognostic risk assessment model based on 11 autophagy-associated genes was constructed in CRC. The new model suggests directions and ideas for evaluating prognosis and provides guidance to choose better treatment strategies for CRC.
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Affiliation(s)
- Qinglian He
- Department of Pathology, Guangdong Medical University, Dongguan, China
| | - Ziqi Li
- Department of Pathology, Guangdong Medical University, Dongguan, China
| | - Jinbao Yin
- Department of Pathology, Guangdong Medical University, Dongguan, China
| | - Yuling Li
- Department of Pathology, Dongguan People's Hospital, Southern Medical University, Dongguan, China
| | - Yuting Yin
- Department of Pathology, Guangdong Medical University, Dongguan, China
| | - Xue Lei
- Department of Pathology, Guangdong Medical University, Dongguan, China
| | - Wei Zhu
- Department of Pathology, Guangdong Medical University, Dongguan, China
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15
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Nguyen GTT, Sutinen A, Raasakka A, Muruganandam G, Loris R, Kursula P. Structure of the Complete Dimeric Human GDAP1 Core Domain Provides Insights into Ligand Binding and Clustering of Disease Mutations. Front Mol Biosci 2021; 7:631232. [PMID: 33585569 PMCID: PMC7873046 DOI: 10.3389/fmolb.2020.631232] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 12/23/2020] [Indexed: 11/13/2022] Open
Abstract
Charcot-Marie-Tooth disease (CMT) is one of the most common inherited neurological disorders. Despite the common involvement of ganglioside-induced differentiation-associated protein 1 (GDAP1) in CMT, the protein structure and function, as well as the pathogenic mechanisms, remain unclear. We determined the crystal structure of the complete human GDAP1 core domain, which shows a novel mode of dimerization within the glutathione S-transferase (GST) family. The long GDAP1-specific insertion forms an extended helix and a flexible loop. GDAP1 is catalytically inactive toward classical GST substrates. Through metabolite screening, we identified a ligand for GDAP1, the fatty acid hexadecanedioic acid, which is relevant for mitochondrial membrane permeability and Ca2+ homeostasis. The fatty acid binds to a pocket next to a CMT-linked residue cluster, increases protein stability, and induces changes in protein conformation and oligomerization. The closest homologue of GDAP1, GDAP1L1, is monomeric in its full-length form. Our results highlight the uniqueness of GDAP1 within the GST family and point toward allosteric mechanisms in regulating GDAP1 oligomeric state and function.
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Affiliation(s)
- Giang Thi Tuyet Nguyen
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland.,Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Aleksi Sutinen
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland.,Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Arne Raasakka
- VIB-VUB Center for Structural Biology, Vlaams Instituut voor Biotechnologie, Brussels, Belgium
| | - Gopinath Muruganandam
- VIB-VUB Center for Structural Biology, Vlaams Instituut voor Biotechnologie, Brussels, Belgium.,Department of Bioengineering Sciences, Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Remy Loris
- VIB-VUB Center for Structural Biology, Vlaams Instituut voor Biotechnologie, Brussels, Belgium.,Department of Bioengineering Sciences, Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Petri Kursula
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland.,Department of Biomedicine, University of Bergen, Bergen, Norway
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16
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Bardin S, Goud B. Generating Rab6 Conditional Knockout Mice. Methods Mol Biol 2021; 2293:257-263. [PMID: 34453723 DOI: 10.1007/978-1-0716-1346-7_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
RAB6 GTPase is the most abundant Golgi-associated RAB protein and regulates several transport steps at the level of this organelle. Homozygous Rab6a knockout (k/o) is embryonic lethal in mouse. To study RAB6 function in cell lineages and tissues, we thus generated various conditional Rab6a knockout (k/o) mice using the Cre/lox system.
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Affiliation(s)
- Sabine Bardin
- Molecular Mechanisms of Intracellular Transport, Institut Curie, PSL Research University, Centre National de la Recherche Scientifique, UMR 144, Paris, France
| | - Bruno Goud
- Molecular Mechanisms of Intracellular Transport, Institut Curie, PSL Research University, Centre National de la Recherche Scientifique, UMR 144, Paris, France.
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17
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Cayre S, Faraldo MM, Bardin S, Miserey-Lenkei S, Deugnier MA, Goud B. RAB6 GTPase regulates mammary secretory function by controlling the activation of STAT5. Development 2020; 147:dev.190744. [PMID: 32895290 PMCID: PMC7561474 DOI: 10.1242/dev.190744] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 08/19/2020] [Indexed: 12/11/2022]
Abstract
The Golgi-associated RAB GTPases, RAB6A and RAB6A', regulate anterograde and retrograde transport pathways from and to the Golgi. In vitro, RAB6A/A' control several cellular functions including cell division, migration, adhesion and polarity. However, their role remains poorly described in vivo Here, we generated BlgCre; Rab6a F/F mice presenting a specific deletion of Rab6a in the mammary luminal secretory lineage during gestation and lactation. Rab6a loss severely impaired the differentiation, maturation and maintenance of the secretory tissue, compromising lactation. The mutant epithelium displayed a decreased activation of STAT5, a key regulator of the lactogenic process primarily governed by prolactin. Data obtained with a mammary epithelial cell line suggested that defective STAT5 activation might originate from a perturbed transport of the prolactin receptor, altering its membrane expression and signaling cascade. Despite the major functional defects observed upon Rab6a deletion, the polarized organization of the mammary epithelial bilayer was preserved. Altogether, our data reveal a crucial role for RAB6A/A' in the lactogenic function of the mammary gland and suggest that the trafficking pathways controlled by RAB6A/A' depend on cell-type specialization and tissue context.
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Affiliation(s)
- Surya Cayre
- Department of Cell Biology and Cancer, Institut Curie, PSL Research University, Sorbonne Université, CNRS, UMR144, Paris F-75005, France
| | - Marisa M Faraldo
- Department of Cell Biology and Cancer, Institut Curie, PSL Research University, Sorbonne Université, CNRS, UMR144, Paris F-75005, France.,INSERM, Paris F-75013, France
| | - Sabine Bardin
- Department of Cell Biology and Cancer, Institut Curie, PSL Research University, Sorbonne Université, CNRS, UMR144, Paris F-75005, France
| | - Stéphanie Miserey-Lenkei
- Department of Cell Biology and Cancer, Institut Curie, PSL Research University, Sorbonne Université, CNRS, UMR144, Paris F-75005, France
| | - Marie-Ange Deugnier
- Department of Cell Biology and Cancer, Institut Curie, PSL Research University, Sorbonne Université, CNRS, UMR144, Paris F-75005, France .,INSERM, Paris F-75013, France
| | - Bruno Goud
- Department of Cell Biology and Cancer, Institut Curie, PSL Research University, Sorbonne Université, CNRS, UMR144, Paris F-75005, France
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18
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Zhao L, Xue M, Zhang L, Guo B, Qin Y, Jiang Q, Sun R, Yang J, Wang L, Liu L, Wang X, Huang C, Tong D. MicroRNA-4268 inhibits cell proliferation via AKT/JNK signalling pathways by targeting Rab6B in human gastric cancer. Cancer Gene Ther 2020; 27:461-472. [PMID: 31303644 DOI: 10.1038/s41417-019-0118-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 05/26/2019] [Accepted: 06/01/2019] [Indexed: 02/07/2023]
Abstract
MicroRNAs (miRNAs) play critical roles in the tumorigenesis and progression of gastric cancer (GC). However, the biological function of miR-4268 in GC and its mechanism remain unclear. In the present study, qTR-PCR found that the expression of miR-4268 was significantly downregulated in GC tissues and cell lines. The overexpression of miR-4268 inhibited GC cell proliferation and the cell cycle G1/S phase transition, and induced cell apoptosis. In contrast, inhibition of miR-4268 promoted cell proliferation and G1-S transition, and suppressed cell apoptosis. Further analyses revealed that miR-4268 expression was negatively correlated with Rab6B expression in GC tissues. Rab6B was verified to be a direct target of miR-4268. Notably, silencing Rab6B resulted in the same biological effects in GC cells as those induced by overexpression of miR-4268. Importantly, both miR-4268 overexpression and Rab6B silence inhibited the AKT/JNK signaling pathways, which modulated cell cycle regulators (Cyclin D1 and CDK4). In contrast, inhibition of miR-4268 promoted the AKT/JNK signaling pathways. MiR-4268 overexpression also promoted the p38 MAPK signaling pathway. Taken together, miR-4268 suppresses GC cell proliferation through inhibiting the AKT/JNK signaling pathways by targeting Rab6B and induces cell apoptosis through promoting the p38 MAPK signaling pathway. Our findings indicate a tumor-suppressor role of miR-4268 in GC pathogenesis and the potential of miR-4268 in GC theropy.
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Affiliation(s)
- Lingyu Zhao
- Department of Cell Biology and Genetics/Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, China
| | - Meng Xue
- Department of Cell Biology and Genetics/Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, China
- Department of Obstetrics and Gynecology, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi, China
| | - Lu Zhang
- Department of Foreign Languages, Ming De College of Northwestern Polytechnical University, Xi'an, Shaanxi, China
| | - Bo Guo
- Department of Cell Biology and Genetics/Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, China
| | - Yannan Qin
- Department of Cell Biology and Genetics/Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, China
| | - Qiuyu Jiang
- Department of Cell Biology and Genetics/Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, China
| | - Ruifang Sun
- Department of Pathology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, China
| | - Juang Yang
- Department of Cell Biology and Genetics/Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, China
| | - Lumin Wang
- Department of Cell Biology and Genetics/Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, China
| | - Liying Liu
- Department of Cell Biology and Genetics/Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, China
| | - Xiaofei Wang
- Department of Cell Biology and Genetics/Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, China
| | - Chen Huang
- Department of Cell Biology and Genetics/Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, China.
| | - Dongdong Tong
- Department of Cell Biology and Genetics/Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, China.
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19
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Abstract
Defects in membrane trafficking are hallmarks of neurodegeneration. Rab GTPases are key regulators of membrane trafficking. Alterations of Rab GTPases, or the membrane compartments they regulate, are associated with virtually all neuronal activities in health and disease. The observation that many Rab GTPases are associated with neurodegeneration has proven a challenge in the quest for cause and effect. Neurodegeneration can be a direct consequence of a defect in membrane trafficking. Alternatively, changes in membrane trafficking may be secondary consequences or cellular responses. The secondary consequences and cellular responses, in turn, may protect, represent inconsequential correlates or function as drivers of pathology. Here, we attempt to disentangle the different roles of membrane trafficking in neurodegeneration by focusing on selected associations with Alzheimer’s disease, Parkinson’s disease, Huntington’s disease and selected neuropathies. We provide an overview of current knowledge on Rab GTPase functions in neurons and review the associations of Rab GTPases with neurodegeneration with respect to the following classifications: primary cause, secondary cause driving pathology or secondary correlate. This analysis is devised to aid the interpretation of frequently observed membrane trafficking defects in neurodegeneration and facilitate the identification of true causes of pathology.
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20
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Krombeen SK, Shankar V, Noorai RE, Saski CA, Sharp JL, Wilson ME, Wilmoth TA. The identification of differentially expressed genes between extremes of placental efficiency in maternal line gilts on day 95 of gestation. BMC Genomics 2019; 20:254. [PMID: 30925895 PMCID: PMC6441153 DOI: 10.1186/s12864-019-5626-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 03/20/2019] [Indexed: 12/11/2022] Open
Abstract
Background Placental efficiency (PE) describes the relationship between placental and fetal weights (fetal wt/placental wt). Within litters, PE can vary drastically, resulting in similarly sized pigs associated with differently sized placentas, up to a 25% weight difference. However, the mechanisms enabling the smaller placenta to grow a comparable littermate are unknown. To elucidate potential mechanisms, morphological measurements and gene expression profiles in placental and associated endometrial tissues of high PE and low PE feto-placental units were compared. Tissue samples were obtained from eight maternal line gilts during gestational day 95 ovario-hysterectomies. RNA was extracted from tissues of feto-placental units with the highest and lowest PE in each litter and sequenced. Results Morphological measurements, except placental weight, were not different (P > 0.05) between high and low PE. No DEG were identified in the endometrium and 214 DEG were identified in the placenta (FDR < 0.1), of which 48% were upregulated and 52% were downregulated. Gene ontology (GO) analysis revealed that a large percentage of DEG were involved in catalytic activity, binding, transporter activity, metabolism, biological regulation, and localization. Four GO terms were enriched in the upregulated genes and no terms were enriched in the downregulated genes (FDR < 0.05). Eight statistically significant correlations (P < 0.05) were identified between the morphological measurements and DEG. Conclusion Morphological measures between high and low PE verified comparisons were of similarly sized pigs grown on different sized placentas, and indicated that any negative effects of a reduced placental size on fetal growth were not evident by day 95. The identification of DEG in the placenta, but absence of DEG in the endometrium confirmed that the placenta responds to the fetus. The GO analyses provided evidence that extremes of PE are differentially regulated, affecting components of placental transport capacity like nutrient transport and blood flow. However, alternative GO terms were identified, indicating the complexity of the relationship between placental and fetal weights. These findings support the use of PE as a marker of placental function and provide novel insight into the genetic control of PE, but further research is required to make PE production applicable.
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Affiliation(s)
- Shanice K Krombeen
- Department of Animal and Veterinary Science, Clemson University, Clemson, SC, 29634, USA
| | - Vijay Shankar
- Center for Human Genetics, Clemson University, Greenwood, SC, 29646, USA
| | - Rooksana E Noorai
- Genomics and Bioinformatics Facility, Clemson University, Clemson, SC, 29634, USA
| | - Christopher A Saski
- Department of Plant and Environmental Sciences, Clemson University, Clemson, SC, 29634, USA
| | - Julia L Sharp
- Department of Statistics, Colorado State University, Fort Collins, CO, 80523, USA
| | - Matthew E Wilson
- Division of Animal and Nutritional Sciences, West Virginia University, Morgantown, WV, 26506, USA
| | - Tiffany A Wilmoth
- Department of Animal and Veterinary Science, Clemson University, Clemson, SC, 29634, USA.
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21
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Held RG, Kaeser PS. ELKS active zone proteins as multitasking scaffolds for secretion. Open Biol 2019; 8:rsob.170258. [PMID: 29491150 PMCID: PMC5830537 DOI: 10.1098/rsob.170258] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Accepted: 02/06/2018] [Indexed: 12/18/2022] Open
Abstract
Synaptic vesicle exocytosis relies on the tethering of release ready vesicles close to voltage-gated Ca2+ channels and specific lipids at the future site of fusion. This enables rapid and efficient neurotransmitter secretion during presynaptic depolarization by an action potential. Extensive research has revealed that this tethering is mediated by an active zone, a protein dense structure that is attached to the presynaptic plasma membrane and opposed to postsynaptic receptors. Although roles of individual active zone proteins in exocytosis are in part understood, the molecular mechanisms that hold the protein scaffold at the active zone together and link it to the presynaptic plasma membrane have remained unknown. This is largely due to redundancy within and across scaffolding protein families at the active zone. Recent studies, however, have uncovered that ELKS proteins, also called ERC, Rab6IP2 or CAST, act as active zone scaffolds redundant with RIMs. This redundancy has led to diverse synaptic phenotypes in studies of ELKS knockout mice, perhaps because different synapses rely to a variable extent on scaffolding redundancy. In this review, we first evaluate the need for presynaptic scaffolding, and we then discuss how the diverse synaptic and non-synaptic functional roles of ELKS support the hypothesis that ELKS provides molecular scaffolding for organizing vesicle traffic at the presynaptic active zone and in other cellular compartments.
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Affiliation(s)
- Richard G Held
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Pascal S Kaeser
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
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22
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Abstract
The Golgi apparatus is a central sorting station in the cell. It receives newly synthesized molecules from the endoplasmic reticulum and directs them to different subcellular destinations, such as the plasma membrane or the endocytic pathway. Importantly, in the last few years, it has emerged that the maintenance of Golgi structure is connected to the proper regulation of membrane trafficking. Rab proteins are small GTPases that are considered to be the master regulators of the intracellular membrane trafficking. Several of the over 60 human Rabs are involved in the regulation of transport pathways at the Golgi as well as in the maintenance of its architecture. This chapter will summarize the different roles of Rab GTPases at the Golgi, both as regulators of membrane transport, scaffold, and tethering proteins and in preserving the structure and function of this organelle.
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23
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Pécot T, Zengzhen L, Boulanger J, Salamero J, Kervrann C. A quantitative approach for analyzing the spatio-temporal distribution of 3D intracellular events in fluorescence microscopy. eLife 2018; 7:32311. [PMID: 30091700 PMCID: PMC6085121 DOI: 10.7554/elife.32311] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 06/08/2018] [Indexed: 12/14/2022] Open
Abstract
Analysis of the spatial distribution of endomembrane trafficking is fundamental to understand the mechanisms controlling cellular dynamics, cell homeostasy, and cell interaction with its external environment in normal and pathological situations. We present a semi-parametric framework to quantitatively analyze and visualize the spatio-temporal distribution of intracellular events from different conditions. From the spatial coordinates of intracellular features such as segmented subcellular structures or vesicle trajectories, QuantEv automatically estimates weighted densities that are easy to interpret and performs a comprehensive statistical analysis from distribution distances. We apply this approach to study the spatio-temporal distribution of moving Rab6 fluorescently labeled membranes with respect to their direction of movement in crossbow- and disk-shaped cells. We also investigate the position of the generating hub of Rab11-positive membranes and the effect of actin disruption on Rab11 trafficking in coordination with cell shape. Proteins are the workhorses of the body, performing a range of roles that are essential for life. Often, this requires these molecules to move from one location to another inside a cell. Scientists are interested in following an individual protein in a living cell ‘in real time’, as this helps understand what this protein does. Scientists can track the whereabouts of a protein by ‘tagging’ it with a fluorescent molecule that emits light which can be picked up by a powerful microscope. This process is repeated many times on different samples. Finally, researchers have to analyze all the resulting images, and conduct statistical analysis to draw robust conclusions about the overall trajectories of the proteins. This process often relies on experts assessing the images, and it is therefore time-consuming and not easily scalable or applied to other experiments. To help with this, Pécot et al. have developed QuantEV, a free algorithm that can analyze proteins’ paths within a cell, and then return statistical graphs and 3D visualizations. The program also gives access to the statistical procedure that was used, which means that different experiments can be compared. Pécot et al. used the method to follow the Rab6 protein in cells of different shapes, and found that the conformation of the cell influences where Rab6 is located. For example, in crossbow-shaped cells, Rab6 is found more often toward the three tips of the crossbow, while its distribution is uniform in cells that look like disks. Another experiment examined where the protein Rab11 is normally placed, and how this changes when the cell’s skeleton is artificially disrupted. Both studies help to gain an insight into the behavior of the cellular structures in which Rab6 and Rab11 are embedded. Following proteins in the cell is an increasingly popular method, and there is therefore a growing amount of data to process. QuantEV should make it easier for biologists to analyze their results, which could help them to have a better grasp on how cells work in various circumstances.
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Affiliation(s)
- Thierry Pécot
- Serpico Team-Project, Inria, Centre Rennes-Bretagne Atlantique, Rennes, France
| | - Liu Zengzhen
- CNRS UMR 144, Space Time Imaging of Endomembranes Dynamics Team, PSL Research University, Institut Curie, Paris, France
| | - Jérôme Boulanger
- CNRS UMR 144, Space Time Imaging of Endomembranes Dynamics Team, PSL Research University, Institut Curie, Paris, France
| | - Jean Salamero
- CNRS UMR 144, Space Time Imaging of Endomembranes Dynamics Team, PSL Research University, Institut Curie, Paris, France.,Cell and Tissue Imaging Facility, IBiSA, Institut Curie, Paris, France
| | - Charles Kervrann
- Serpico Team-Project, Inria, Centre Rennes-Bretagne Atlantique, Rennes, France
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24
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Raza S, Alvisi G, Shahin F, Husain U, Rabbani M, Yaqub T, Anjum AA, Sheikh AA, Nawaz M, Ali MA. Role of Rab GTPases in HSV-1 infection: Molecular understanding of viral maturation and egress. Microb Pathog 2018; 118:146-153. [PMID: 29551438 DOI: 10.1016/j.micpath.2018.03.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 03/14/2018] [Accepted: 03/15/2018] [Indexed: 12/17/2022]
Abstract
Most enveloped viruses exploit complex cellular pathways for assembly and egress from the host cell, and the large DNA virus Herpes simplex virus 1 (HSV-1) makes no exception, hijacking several cellular transport pathways for its glycoprotein trafficking and maturation, as well as for viral morphogenesis and egress according to the envelopment, de-envelopment and re-envelopment model. Importantly Rab GTPases, widely distributed master regulators of intracellular membrane trafficking pathways, have recently being tightly implicated in such process. Indeed, siRNA-mediated genetic ablation of specific Rab proteins differently affected HSV-1 production, suggesting a complex role of different Rab proteins in HSV-1 life cycle. In this review, we discuss how different Rabs can regulate HSV-1 assembly/egress and the potential therapeutic applications of such findings for the management of HSV-1 infections.
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Affiliation(s)
- Sohail Raza
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan.
| | - Gualtiero Alvisi
- Department of Molecular Medicine, University of Padua, 35121, Italy
| | - Farzana Shahin
- The State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Urooj Husain
- Postgraduate Medical Institute Lahore 54000, Pakistan
| | - Masood Rabbani
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan
| | - Tahir Yaqub
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan
| | - Aftab Ahmad Anjum
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan
| | - Ali Ahmad Sheikh
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan
| | - Muhammad Nawaz
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan
| | - Muhammad Asad Ali
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan
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25
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Identification of novel prognostic indicators for triple-negative breast cancer patients through integrative analysis of cancer genomics data and protein interactome data. Oncotarget 2018; 7:71620-71634. [PMID: 27690302 PMCID: PMC5342106 DOI: 10.18632/oncotarget.12287] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 09/22/2016] [Indexed: 12/31/2022] Open
Abstract
Triple negative breast cancers (TNBCs) are highly heterogeneous and aggressive without targeted treatment. Here, we aim to systematically dissect TNBCs from a prognosis point of view by building a subnetwork atlas for TNBC prognosis through integrating multi-dimensional cancer genomics data from The Cancer Genome Atlas (TCGA) project and the interactome data from three different interaction networks. The subnetworks are represented as the protein-protein interaction modules perturbed by multiple genetic and epigenetic interacting mechanisms contributing to patient survival. Predictive power of these subnetwork-derived prognostic models is evaluated using Monte Carlo cross-validation and the concordance index (C-index). We uncover subnetwork biomarkers of low oncogenic GTPase activity, low ubiquitin/proteasome degradation, effective protection from oxidative damage, and tightly immune response are linked to better prognosis. Such a systematic approach to integrate massive amount of cancer genomics data into clinical practice for TNBC prognosis can effectively dissect the molecular mechanisms underlying TNBC patient outcomes and provide potential opportunities to optimize treatment and develop therapeutics.
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26
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Molecular Insights into the Roles of Rab Proteins in Intracellular Dynamics and Neurodegenerative Diseases. Neuromolecular Med 2018; 20:18-36. [PMID: 29423895 DOI: 10.1007/s12017-018-8479-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 01/27/2018] [Indexed: 02/01/2023]
Abstract
In eukaryotes, the cellular functions are segregated to membrane-bound organelles. This inherently requires sorting of metabolites to membrane-limited locations. Sorting the metabolites from ribosomes to various organelles along the intracellular trafficking pathways involves several integral cellular processes, including an energy-dependent step, in which the sorting of metabolites between organelles is catalyzed by membrane-anchoring protein Rab-GTPases (Rab). They contribute to relaying the switching of the secretory proteins between hydrophobic and hydrophilic environments. The intracellular trafficking routes include exocytic and endocytic pathways. In these pathways, numerous Rab-GTPases are participating in discrete shuttling of cargoes. Long-distance trafficking of cargoes is essential for neuronal functions, and Rabs are critical for these functions, including the transport of membranes and essential proteins for the development of axons and neurites. Rabs are also the key players in exocytosis of neurotransmitters and recycling of neurotransmitter receptors. Thus, Rabs are critical for maintaining neuronal communication, as well as for normal cellular physiology. Therefore, cellular defects of Rab components involved in neural functions, which severely affect normal brain functions, can produce neurological complications, including several neurodegenerative diseases. In this review, we provide a comprehensive overview of the current understanding of the molecular signaling pathways of Rab proteins and the impact of their defects on different neurodegenerative diseases. The insights gathered into the dynamics of Rabs that are described in this review provide new avenues for developing effective treatments for neurodegenerative diseases-associated with Rab defects.
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27
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Abstract
GTP-ases of the Rab family (about 70 in human) are key regulators of intracellular transport and membrane trafficking in eukaryotic cells. Remarkably, almost one third associate with membranes of the Golgi complex and TGN (trans-Golgi network). Through interactions with a variety of effectors that include molecular motors, tethering complexes, scaffolding proteins and lipid kinases, they play an important role in maintaining Golgi architecture.
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Affiliation(s)
- Bruno Goud
- a Institut Curie, PSL Research University, CNRS, UMR 144, Molecular Mechanisms of Intracellular Transport , Paris , France
| | - Shijie Liu
- b Department of Physiology and Biophysics , University of Arkansas for Medical Sciences , Little Rock , USA
| | - Brian Storrie
- b Department of Physiology and Biophysics , University of Arkansas for Medical Sciences , Little Rock , USA
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28
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Sominsky L, Goularte JF, Andrews ZB, Spencer SJ. Acylated Ghrelin Supports the Ovarian Transcriptome and Follicles in the Mouse: Implications for Fertility. Front Endocrinol (Lausanne) 2018; 9:815. [PMID: 30697193 PMCID: PMC6340924 DOI: 10.3389/fendo.2018.00815] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 12/27/2018] [Indexed: 12/16/2022] Open
Abstract
Ghrelin, an orexigenic gut-derived peptide, is gaining increasing attention due to its multifaceted role in a number of physiological functions, including reproduction. Ghrelin exists in circulation primarily as des-acylated and acylated ghrelin. Des-acyl ghrelin, until recently considered to be an inactive form of ghrelin, is now known to have independent physiological functionality. However, the relative contribution of acyl and des-acyl ghrelin to reproductive development and function is currently unknown. Here we used ghrelin-O-acyltransferase (GOAT) knockout (KO) mice that have no measurable levels of endogenous acyl ghrelin and chronically high levels of des-acyl ghrelin, to characterize how the developmental and life-long absence of acyl ghrelin affects ovarian development and reproductive capacity. We combined the assessment of markers of reproductive maturity and the capacity to breed with measures of ovarian morphometry, as well as with ovarian RNA sequencing analysis. Our data show that while GOAT KO mice retain the capacity to breed in young adulthood, there is a diminished number of ovarian follicles (per mm3) in the juvenile and adult ovaries, due to a significant reduction in the number of small follicles, particularly the primordial follicles. We also show pronounced specific changes in the ovarian transcriptome in the juvenile GOAT KO ovary, indicative of a potential for premature ovarian development. Collectively, these findings indicate that an absence of acyl ghrelin does not prevent reproductive success but that appropriate levels of acyl and des-acyl ghrelin may be necessary for optimal ovarian maturation.
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Affiliation(s)
- Luba Sominsky
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
- *Correspondence: Luba Sominsky
| | - Jeferson F. Goularte
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, VIC, Australia
| | - Zane B. Andrews
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, VIC, Australia
| | - Sarah J. Spencer
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
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29
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Banworth MJ, Li G. Consequences of Rab GTPase dysfunction in genetic or acquired human diseases. Small GTPases 2017; 9:158-181. [PMID: 29239692 DOI: 10.1080/21541248.2017.1397833] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Rab GTPases are important regulators of intracellular membrane trafficking in eukaryotes. Both activating and inactivating mutations in Rab genes have been identified and implicated in human diseases ranging from neurological disorders to cancer. In addition, altered Rab expression is often associated with disease prognosis. As such, the study of diseases associated with Rabs or Rab-interacting proteins has shed light on the important role of intracellular membrane trafficking in disease etiology. In this review, we cover recent advances in the field with an emphasis on cellular mechanisms.
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Affiliation(s)
- Marcellus J Banworth
- a Department of Biochemistry and Molecular Biology , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
| | - Guangpu Li
- a Department of Biochemistry and Molecular Biology , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
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30
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Shorter SA, Pettit MW, Dyer PDR, Coakley Youngs E, Gorringe-Pattrick MAM, El-Daher S, Richardson S. Green fluorescent protein (GFP): is seeing believing and is that enough? J Drug Target 2017; 25:809-817. [PMID: 28743200 DOI: 10.1080/1061186x.2017.1358725] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Intracellular compartmentalisation is a significant barrier to the successful nucleocytosolic delivery of biologics. The endocytic system has been shown to be responsible for compartmentalisation, providing an entry point, and trigger(s) for the activation of drug delivery systems. Consequently, many of the technologies used to understand endocytosis have found utility within the field of drug delivery. The use of fluorescent proteins as markers denoting compartmentalisation within the endocytic system has become commonplace. Several of the limitations associated with the use of green fluorescent protein (GFP) within the context of drug delivery have been explored here by asking a series of related questions: (1) Are molecules that regulate fusion to a specific compartment (i.e. Rab- or SNARE-GFP fusions) a good choice of marker for that compartment? (2) How reliable was GFP-marker overexpression when used to define a given endocytic compartment? (3) Can glutathione-s-transferase (GST) fused in frame with GFP (GST-GFP) act as a fluid phase endocytic probe? (4) Was GFP fluorescence a robust indicator of (GFP) protein integrity? This study concluded that there are many appropriate and useful applications for GFP; however, thought and an understanding of the biological and physicochemical character of these markers are required for the generation of meaningful data.
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Affiliation(s)
- Susan A Shorter
- a IDS Laboratory, Department of Life and Sports Science, Faculty of Engineering and Science , University of Greenwich , Chatham , Kent , UK
| | - Marie W Pettit
- a IDS Laboratory, Department of Life and Sports Science, Faculty of Engineering and Science , University of Greenwich , Chatham , Kent , UK
| | - Paul D R Dyer
- a IDS Laboratory, Department of Life and Sports Science, Faculty of Engineering and Science , University of Greenwich , Chatham , Kent , UK
| | - Emma Coakley Youngs
- a IDS Laboratory, Department of Life and Sports Science, Faculty of Engineering and Science , University of Greenwich , Chatham , Kent , UK
| | - Monique A M Gorringe-Pattrick
- a IDS Laboratory, Department of Life and Sports Science, Faculty of Engineering and Science , University of Greenwich , Chatham , Kent , UK
| | - Samer El-Daher
- a IDS Laboratory, Department of Life and Sports Science, Faculty of Engineering and Science , University of Greenwich , Chatham , Kent , UK
| | - Simon Richardson
- a IDS Laboratory, Department of Life and Sports Science, Faculty of Engineering and Science , University of Greenwich , Chatham , Kent , UK
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31
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Golgi trafficking defects in postnatal microcephaly: The evidence for “Golgipathies”. Prog Neurobiol 2017; 153:46-63. [DOI: 10.1016/j.pneurobio.2017.03.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 02/22/2017] [Accepted: 03/29/2017] [Indexed: 12/17/2022]
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32
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Ma R, Zhang J, Liu X, Li L, Liu H, Rui R, Gu L, Wang Q. Involvement of Rab6a in organelle rearrangement and cytoskeletal organization during mouse oocyte maturation. Sci Rep 2016; 6:23560. [PMID: 27030207 PMCID: PMC4814827 DOI: 10.1038/srep23560] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 03/07/2016] [Indexed: 12/19/2022] Open
Abstract
Rab GTPases have been reported to define the identity and transport routes of vesicles. Rab6 is one of the most extensively studied Rab proteins involved in regulating organelle trafficking and integrity maintenance. However, to date, the function of Rab6 in mammalian oocytes has not been addressed. Here we report severe disorganization of endoplasmic reticulum upon specific knockdown of Rab6a in mouse oocytes. In line with this finding, intracellular Ca2+ stores are accordingly reduced in Rab6a-depleted oocytes. Furthermore, in these oocytes, we observe the absence of cortical granule free domain, which is a kind of special organelle in matured oocytes and its exocytosis is calcium dependent. On the other hand, following Rab6a knockdown, the prominent defects of cytoskeletal structures are detected during oocyte meiosis. In particular, the majority of Rab6a-depleted oocytes fail to form the actin cap, and the frequency of spindle defects and chromosome misalignment is significantly elevated. In summary, our data reveal that Rab6a not only participates in modulating the organization of oocyte organelles, but also is a novel regulator of meiotic apparatus in mammalian oocytes.
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Affiliation(s)
- Rujun Ma
- College of Animal Science &Technology, Nanjing Agricultural University, Nanjing, China.,State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China.,Center of Reproductive Medicine, Jinling Hospital, Medical School of Nanjing University, Nanjing, China
| | - Jiaqi Zhang
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Xiaohui Liu
- College of Animal Science &Technology, Nanjing Agricultural University, Nanjing, China.,State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Ling Li
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Honglin Liu
- College of Animal Science &Technology, Nanjing Agricultural University, Nanjing, China
| | - Rong Rui
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Ling Gu
- College of Animal Science &Technology, Nanjing Agricultural University, Nanjing, China
| | - Qiang Wang
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
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33
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Rab GTPases and the Autophagy Pathway: Bacterial Targets for a Suitable Biogenesis and Trafficking of Their Own Vacuoles. Cells 2016; 5:cells5010011. [PMID: 27005665 PMCID: PMC4810096 DOI: 10.3390/cells5010011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 03/02/2016] [Accepted: 03/03/2016] [Indexed: 12/18/2022] Open
Abstract
Autophagy is an intracellular process that comprises degradation of damaged organelles, protein aggregates and intracellular pathogens, having an important role in controlling the fate of invading microorganisms. Intracellular pathogens are internalized by professional and non-professional phagocytes, localizing in compartments called phagosomes. To degrade the internalized microorganism, the microbial phagosome matures by fusion events with early and late endosomal compartments and lysosomes, a process that is regulated by Rab GTPases. Interestingly, in order to survive and replicate in the phagosome, some pathogens employ different strategies to manipulate vesicular traffic, inhibiting phagolysosomal biogenesis (e.g., Staphylococcus aureus and Mycobacterium tuberculosis) or surviving in acidic compartments and forming replicative vacuoles (e.g., Coxiellaburnetti and Legionella pneumophila). The bacteria described in this review often use secretion systems to control the host’s response and thus disseminate. To date, eight types of secretion systems (Type I to Type VIII) are known. Some of these systems are used by bacteria to translocate pathogenic proteins into the host cell and regulate replicative vacuole formation, apoptosis, cytokine responses, and autophagy. Herein, we have focused on how bacteria manipulate small Rab GTPases to control many of these processes. The growing knowledge in this field may facilitate the development of new treatments or contribute to the prevention of these types of bacterial infections.
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34
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Liu S, Majeed W, Kudlyk T, Lupashin V, Storrie B. Identification of Rab41/6d Effectors Provides an Explanation for the Differential Effects of Rab41/6d and Rab6a/a' on Golgi Organization. Front Cell Dev Biol 2016; 4:13. [PMID: 26973836 PMCID: PMC4771738 DOI: 10.3389/fcell.2016.00013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 02/09/2016] [Indexed: 11/24/2022] Open
Abstract
Unexpectedly, members of the Rab VI subfamily exhibit considerable variation in their effects on Golgi organization and trafficking. By fluorescence microscopy, neither depletion nor overexpression of the GDP-locked form of Rab6a/a', the first trans Golgi-associated Rab protein discovered, affects Golgi ribbon organization while, on the other hand, both Rab41/6d depletion and overexpression of GDP-locked form cause Golgi fragmentation into a cluster of punctate elements, suggesting that Rab41/6d has an active role in maintenance of Golgi ribbon organization. To establish a molecular basis for these differences, we screened for Rab41/6d interacting proteins by yeast two-hybrid assay. 155 non-repetitive hits were isolated and sequenced, and after searching in NCBI database, 102 different proteins and protein fragments were identified. None of these hits overlapped with any published Rab6a/a' effector. Eight putative Rab41 interactors involved in membrane trafficking were found. Significantly, these exhibited a preferential interaction with GTP- vs. GDP-locked Rab41/6d. Of the 8 hits, the dynactin 6, syntaxin 8, and Kif18A plasmids were the only ones expressing the full-length protein. Hence, these 3 proteins were selected for further study. We found that depletion of dynactin 6 or syntaxin 8, but not Kif18A, resulted in a fragmented Golgi apparatus that displayed a Rab41/6d knockdown phenotype, i.e., the Golgi apparatus was disrupted into a cluster of punctate Golgi elements. Co-immunoprecipation experiments verified that the interaction of dynactin 6 and syntaxin 8 with GTP-locked Rab41/6d was stronger than that with wild type Rab41/6d and least with the GDP-locked form. In contrast, co-immunoprecipitation interaction with Rab6a was greatest with the GDP-locked Rab6a, suggestive of a non-physiological interaction. In conclusion, we suggest that dynactin 6, a subunit of dynactin complex, the minus-end-directed, dynein motor, provides a sufficient molecular basis to explain the active role of Rab41/6d in maintaining Golgi ribbon organization while syntaxin 8 contributes more indirectly to Golgi positioning.
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Affiliation(s)
- Shijie Liu
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences Little Rock, AR, USA
| | - Waqar Majeed
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences Little Rock, AR, USA
| | - Tetyana Kudlyk
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences Little Rock, AR, USA
| | - Vladimir Lupashin
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences Little Rock, AR, USA
| | - Brian Storrie
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences Little Rock, AR, USA
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Zhang D, Dubey J, Koushika SP, Rongo C. RAB-6.1 and RAB-6.2 Promote Retrograde Transport in C. elegans. PLoS One 2016; 11:e0149314. [PMID: 26891225 PMCID: PMC4758642 DOI: 10.1371/journal.pone.0149314] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 01/30/2016] [Indexed: 12/25/2022] Open
Abstract
Retrograde transport is a critical mechanism for recycling certain membrane cargo. Following endocytosis from the plasma membrane, retrograde cargo is moved from early endosomes to Golgi followed by transport (recycling) back to the plasma membrane. The complete molecular and cellular mechanisms of retrograde transport remain unclear. The small GTPase RAB-6.2 mediates the retrograde recycling of the AMPA-type glutamate receptor (AMPAR) subunit GLR-1 in C. elegans neurons. Here we show that RAB-6.2 and a close paralog, RAB-6.1, together regulate retrograde transport in both neurons and non-neuronal tissue. Mutants for rab-6.1 or rab-6.2 fail to recycle GLR-1 receptors, resulting in GLR-1 turnover and behavioral defects indicative of diminished GLR-1 function. Loss of both rab-6.1 and rab-6.2 results in an additive effect on GLR-1 retrograde recycling, indicating that these two C. elegans Rab6 isoforms have overlapping functions. MIG-14 (Wntless) protein, which undergoes retrograde recycling, undergoes a similar degradation in intestinal epithelia in both rab-6.1 and rab-6.2 mutants, suggesting a broader role for these proteins in retrograde transport. Surprisingly, MIG-14 is localized to separate, spatially segregated endosomal compartments in rab-6.1 mutants compared to rab-6.2 mutants. Our results indicate that RAB-6.1 and RAB-6.2 have partially redundant functions in overall retrograde transport, but also have their own unique cellular- and subcellular functions.
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Affiliation(s)
- Donglei Zhang
- The Waksman Institute, Department of Genetics, Rutgers The State University of New Jersey, Piscataway, New Jersey, United States of America
| | - Jyoti Dubey
- Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai, India
- Institute for Stem Cell Biology and Regenerative Medicine (InStem), Bangalore, India
- Manipal University, Karnataka, India
| | - Sandhya P. Koushika
- Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai, India
| | - Christopher Rongo
- The Waksman Institute, Department of Genetics, Rutgers The State University of New Jersey, Piscataway, New Jersey, United States of America
- * E-mail:
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Bardin S, Miserey-Lenkei S, Hurbain I, Garcia-Castillo D, Raposo G, Goud B. Phenotypic characterisation of RAB6A knockout mouse embryonic fibroblasts. Biol Cell 2015; 107:427-39. [PMID: 26304202 DOI: 10.1111/boc.201400083] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 08/18/2015] [Indexed: 01/08/2023]
Abstract
BACKGROUND INFORMATION Rab6 is one of the most conserved Rab GTPaes throughout evolution and the most abundant Rab protein associated with the Golgi complex. The two ubiquitous Rab isoforms, Rab6A and Rab6A', that are generated by alternative splicing of the RAB6A gene, regulate several transport steps at the Golgi level, including retrograde transport between endosomes and Golgi, anterograde transport between Golgi and the plasma membrane, and intra-Golgi and Golgi to endoplasmic reticulum transport. RESULTS We have generated mice with a conditional null allele of RAB6A. Mice homozygous for the RAB6A null allele died at an early stage of embryonic development. Mouse embryonic fibroblasts (MEFs) were isolated from RAB6A(loxP/loxP) Rosa26-CreERT2 and incubated with 4-hydroxy tamoxifen, resulting in the efficient depletion of Rab6A and Rab6A'. We show that Rab6 depletion affects cell growth, alters Golgi morphology and decreases the Golgi-associated levels of some known Rab6 effectors such as Bicaudal-D and myosin II. We also show that Rab6 depletion protects MEFs against ricin toxin and delays VSV-G secretion. CONCLUSIONS Our study shows that RAB6 is an essential gene required for normal embryonic development. We confirm in MEF cells most of the functions previously attributed to the two ubiquitous Rab6 isoforms.
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Affiliation(s)
- Sabine Bardin
- Institut Curie, PSL Research University and CNRS UMR 144, Paris, 75248, France
| | | | - Ilse Hurbain
- Institut Curie, PSL Research University and CNRS UMR 144, Paris, 75248, France
| | - Daniela Garcia-Castillo
- Institut Curie, PSL Research University, CNRS UMR 3666 and INSERM U1143, Paris, 75248, France
| | - Graça Raposo
- Institut Curie, PSL Research University and CNRS UMR 144, Paris, 75248, France
| | - Bruno Goud
- Institut Curie, PSL Research University and CNRS UMR 144, Paris, 75248, France
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The trials and tubule-ations of Rab6 involvement in Golgi-to-ER retrograde transport. Biochem Soc Trans 2015; 42:1453-9. [PMID: 25233431 DOI: 10.1042/bst20140178] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In the early secretory pathway, membrane flow in the anterograde direction from the endoplasmic reticulum (ER) to the Golgi complex needs to be tightly co-ordinated with retrograde flow to maintain the size, composition and functionality of these two organelles. At least two mechanisms of transport move material in the retrograde direction: one regulated by the cytoplasmic coatomer protein I complex (COPI), and a second COPI-independent pathway utilizing the small GTP-binding protein Rab6. Although the COPI-independent pathway was discovered 15 years ago, it remains relatively poorly characterized, with only a handful of machinery molecules associated with its operation. One feature that makes this pathway somewhat unusual, and potentially difficult to study, is that the transport carriers predominantly seem to be tubular rather than vesicular in nature. This suggests that the regulatory machinery is likely to be different from that associated with vesicular transport pathways controlled by conventional coat complexes. In the present mini-review, we have highlighted the key experiments that have characterized this transport pathway so far and also have discussed the challenges that lie ahead with respect to its further characterization.
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Matsuto M, Kano F, Murata M. Reconstitution of the targeting of Rab6A to the Golgi apparatus in semi-intact HeLa cells: A role of BICD2 in stabilizing Rab6A on Golgi membranes and a concerted role of Rab6A/BICD2 interactions in Golgi-to-ER retrograde transport. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:2592-609. [PMID: 25962623 DOI: 10.1016/j.bbamcr.2015.05.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2014] [Revised: 05/02/2015] [Accepted: 05/05/2015] [Indexed: 12/21/2022]
Abstract
Rab is a small GTP-binding protein family that regulates various pathways of vesicular transport. Although more than 60 Rab proteins are targeted to specific organelles in mammalian cells, the mechanisms underlying the specificity of Rab proteins for the respective organelles remain unknown. In this study, we reconstituted the Golgi targeting of Rab6A in streptolysin O (SLO)-permeabilized HeLa cells in a cytosol-dependent manner and investigated the biochemical requirements of targeting. Golgi-targeting assays identified Bicaudal-D (BICD)2, which is reportedly involved in the dynein-mediated transport of mRNAs during oogenesis and embryogenesis in Drosophila, as a cytosolic factor for the Golgi targeting of Rab6A in SLO-permeabilized HeLa cells. Subsequent immunofluorescence analyses indicated decreased amounts of the GTP-bound active form of Rab6 in BICD2-knockdown cells. In addition, fluorescence recovery after photobleaching (FRAP) analyses revealed that overexpression of the C-terminal region of BICD2 decreased the exchange rate of GFP-Rab6A between the Golgi membrane and the cytosol. Collectively, these results indicated that BICD2 facilitates the binding of Rab6A to the Golgi by stabilizing its GTP-bound form. Moreover, several analyses of vesicular transport demonstrated that Rab6A and BICD2 play crucial roles in Golgi tubule fusion with the endoplasmic reticulum (ER) in brefeldin A (BFA)-treated cells, indicating that BICD2 is involved in coat protein I (COPI)-independent Golgi-to-ER retrograde vesicular transport.
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Affiliation(s)
- Mariko Matsuto
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8902, Japan
| | - Fumi Kano
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8902, Japan; PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
| | - Masayuki Murata
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8902, Japan.
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Chen Y, Jiang C, Jin M, Gong Y, Zhang X. The role of Rab6 GTPase in the maturation of phagosome against Staphylococcus aureus. Int J Biochem Cell Biol 2015; 61:35-44. [PMID: 25660370 DOI: 10.1016/j.biocel.2015.01.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 01/18/2015] [Accepted: 01/28/2015] [Indexed: 02/02/2023]
Abstract
Phagocytosis, an evolutionarily conserved process in animals, plays a central role in host defense against pathogens. As reported, Rab6 GTPase was involved in the regulation of hemocytic phagocytosis in invertebrates. However, the role of Rab6 GTPase in mammalian phagocytosis remains to be addressed. In this study, the results showed that Rab6 GTPase took great effects on phagocytosis of mouse leukemic monocyte macrophages (RAW 264.7 cells). It was revealed that Rab6 GTPase was required during the phagosome maturation by its interaction with bicaudal-D1 (BICD1) protein. Further data presented that the Rab6 GTPase-regulated phagocytosis could influence the proliferation of Staphylococcus aureus in macrophages. Therefore, our study demonstrated a novel insight into the mechanism of regulation of mammalian phagocytosis by Rab6 GTPase and a novel strategy for the control of Staphylococcus aureus.
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Affiliation(s)
- Yulei Chen
- Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and College of Life Sciences, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Chunxia Jiang
- Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and College of Life Sciences, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Min Jin
- Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and College of Life Sciences, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Yi Gong
- Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and College of Life Sciences, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Xiaobo Zhang
- Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and College of Life Sciences, Zhejiang University, Hangzhou 310058, People's Republic of China.
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40
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Liu S, Storrie B. How Rab proteins determine Golgi structure. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 315:1-22. [PMID: 25708460 DOI: 10.1016/bs.ircmb.2014.12.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Rab proteins, small GTPases, are key regulators of mammalian Golgi apparatus organization. Based on the effect of Rab activation state, Rab proteins fall into two functional classes. In Class1, inactivation induces Golgi ribbon fragmentation and/or redistribution of Golgi enzymes to the Endoplasmic Reticulum, while overexpression of wild type or activation has little, if any, effect on Golgi ribbon organization. In Class 2, the reverse is true. We give emphasis to Rab6, the most abundant Golgi-associated Rab protein. Rab6 depletion in HeLa cells causes an increase in Golgi cisternal number, longer, more continuous cisternae, and a pronounced accumulation of vesicles; the effect of Rab6 on Golgi ribbon organization is probably through regulation of vesicle transport. In effector studies, motor proteins and their regulators are found to be key Rab6 effectors. A related Rab, Rab41, affects Golgi ribbon organization in a contrasting manner. The balance between minus- and plus-end directed motor recruitment may well be the major Rab-dependent factor in Golgi ribbon organization.
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Affiliation(s)
- Shijie Liu
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Brian Storrie
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
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41
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Galligan J, Martinez-Noël G, Arndt V, Hayes S, Chittenden TW, Harper JW, Howley PM. Proteomic analysis and identification of cellular interactors of the giant ubiquitin ligase HERC2. J Proteome Res 2015; 14:953-66. [PMID: 25476789 PMCID: PMC4324439 DOI: 10.1021/pr501005v] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Indexed: 01/10/2023]
Abstract
HERC2 is a large E3 ubiquitin ligase with multiple structural domains that has been implicated in an array of cellular processes. Mutations in HERC2 are linked to developmental delays and impairment caused by nervous system dysfunction, such as Angelman Syndrome and autism-spectrum disorders. However, HERC2 cellular activity and regulation remain poorly understood. We used a broad proteomic approach to survey the landscape of cellular proteins that interact with HERC2. We identified nearly 300 potential interactors, a subset of which we validated binding to HERC2. The potential HERC2 interactors included the eukaryotic translation initiation factor 3 complex, the intracellular transport COPI coatomer complex, the glycogen regulator phosphorylase kinase, beta-catenin, PI3 kinase, and proteins involved in fatty acid transport and iron homeostasis. Through a complex bioinformatic analysis of potential interactors, we linked HERC2 to cellular processes including intracellular protein trafficking and transport, metabolism of cellular energy, and protein translation. Given its size, multidomain structure, and association with various cellular activities, HERC2 may function as a scaffold to integrate protein complexes and bridge critical cellular pathways. This work provides a significant resource with which to interrogate HERC2 function more deeply and evaluate its contributions to mechanisms governing cellular homeostasis and disease.
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Affiliation(s)
- Jeffrey
T. Galligan
- Department
of Microbiology and Immunobiology, Harvard
Medical School, 77 Avenue
Louis Pasteur, Boston, Massachusetts 02115, United States
| | - Gustavo Martinez-Noël
- Department
of Microbiology and Immunobiology, Harvard
Medical School, 77 Avenue
Louis Pasteur, Boston, Massachusetts 02115, United States
| | - Verena Arndt
- Department
of Microbiology and Immunobiology, Harvard
Medical School, 77 Avenue
Louis Pasteur, Boston, Massachusetts 02115, United States
| | - Sebastian Hayes
- Department
of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, United States
| | - Thomas W. Chittenden
- Research
Computing Group, Harvard Medical School, 25 Shattuck Street #500, Boston, Massachusetts 02115, United States
- Complex Biological
Systems Alliance, 17 Peterson Road, North Andover, Massachusetts 01845, United States
| | - J. Wade Harper
- Department
of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, United States
| | - Peter M. Howley
- Department
of Microbiology and Immunobiology, Harvard
Medical School, 77 Avenue
Louis Pasteur, Boston, Massachusetts 02115, United States
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Pécot T, Bouthemy P, Boulanger J, Chessel A, Bardin S, Salamero J, Kervrann C. Background fluorescence estimation and vesicle segmentation in live cell imaging with conditional random fields. IEEE TRANSACTIONS ON IMAGE PROCESSING : A PUBLICATION OF THE IEEE SIGNAL PROCESSING SOCIETY 2015; 24:667-80. [PMID: 25531952 DOI: 10.1109/tip.2014.2380178] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Image analysis applied to fluorescence live cell microscopy has become a key tool in molecular biology since it enables to characterize biological processes in space and time at the subcellular level. In fluorescence microscopy imaging, the moving tagged structures of interest, such as vesicles, appear as bright spots over a static or nonstatic background. In this paper, we consider the problem of vesicle segmentation and time-varying background estimation at the cellular scale. The main idea is to formulate the joint segmentation-estimation problem in the general conditional random field framework. Furthermore, segmentation of vesicles and background estimation are alternatively performed by energy minimization using a min cut-max flow algorithm. The proposed approach relies on a detection measure computed from intensity contrasts between neighboring blocks in fluorescence microscopy images. This approach permits analysis of either 2D + time or 3D + time data. We demonstrate the performance of the so-called C-CRAFT through an experimental comparison with the state-of-the-art methods in fluorescence video-microscopy. We also use this method to characterize the spatial and temporal distribution of Rab6 transport carriers at the cell periphery for two different specific adhesion geometries.
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43
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Al-Zeer MA, Al-Younes HM, Kerr M, Abu-Lubad M, Gonzalez E, Brinkmann V, Meyer TF. Chlamydia trachomatis remodels stable microtubules to coordinate Golgi stack recruitment to the chlamydial inclusion surface. Mol Microbiol 2014; 94:1285-97. [PMID: 25315131 DOI: 10.1111/mmi.12829] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/11/2014] [Indexed: 12/31/2022]
Abstract
Chlamydia trachomatis (Ctr), an obligate intracellular bacterium, survives and replicates within a membrane-bound vacuole, termed the inclusion, which intercepts host exocytic pathways to acquire nutrients. Ctr subverts cellular trafficking pathways from the Golgi by targeting small GTPases, including Rab proteins, to sustain intracellular bacterial replication; however, the precise mechanisms involved remain incompletely understood. Here, we show that Chlamydia infection in human epithelial cells induces microtubule remodeling, in particular the formation of detyrosinated stable MTs, to recruit Golgi ministacks, but not recycling endosomes, to the inclusion. These stable microtubules show increased resistance to chemically induced depolymerization, and their selective depletion results in reduced bacterial infectivity. Rab6 knockdown reversibly prevented not only Golgi ministack formation but also detyrosinated microtubule association with the inclusion. Our data demonstrate that Chlamydia co-opts the function of stable microtubules to support its development.
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Affiliation(s)
- Munir A Al-Zeer
- Department of Molecular Biology, Max Planck Institute for Infection Biology, Charitèplatz 1, 10117, Berlin, Germany
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44
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Chung S, Andrew DJ. Cadherin 99C regulates apical expansion and cell rearrangement during epithelial tube elongation. Development 2014; 141:1950-60. [PMID: 24718992 DOI: 10.1242/dev.104166] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Apical and basolateral determinants specify and maintain membrane domains in epithelia. Here, we identify new roles for two apical surface proteins - Cadherin 99C (Cad99C) and Stranded at Second (SAS) - in conferring apical character in Drosophila tubular epithelia. Cad99C, the Drosophila ortholog of human Usher protocadherin PCDH15, is expressed in several embryonic tubular epithelial structures. Through loss-of-function and overexpression studies, we show that Cad99C is required to regulate cell rearrangement during salivary tube elongation. We further show that overexpression of either Cad99C or SAS causes a dramatic increase in apical membrane at the expense of other membrane domains, and that both proteins can do this independently of each other and independently of mislocalization of the apical determinant Crumbs (Crb). Overexpression of Cad99C or SAS results in similar, but distinct effects, suggesting both shared and unique roles for these proteins in conferring apical identity.
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Affiliation(s)
- Seyeon Chung
- Department of Cell Biology, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205-2196, USA
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45
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Johns HL, Gonzalez-Lopez C, Sayers CL, Hollinshead M, Elliott G. Rab6 dependent post-Golgi trafficking of HSV1 envelope proteins to sites of virus envelopment. Traffic 2014; 15:157-78. [PMID: 24152084 PMCID: PMC4345966 DOI: 10.1111/tra.12134] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 10/17/2013] [Accepted: 10/23/2013] [Indexed: 12/19/2022]
Abstract
Herpes simplex virus 1 (HSV1) is an enveloped virus that uses undefined transport carriers for trafficking of its glycoproteins to envelopment sites. Screening of an siRNA library against 60 Rab GTPases revealed Rab6 as the principal Rab involved in HSV1 infection, with its depletion preventing Golgi-to-plasma membrane transport of HSV1 glycoproteins in a pathway used by several integral membrane proteins but not the luminal secreted protein Gaussia luciferase. Knockdown of Rab6 reduced virus yield to 1% and inhibited capsid envelopment, revealing glycoprotein exocytosis as a prerequisite for morphogenesis. Rab6-dependent virus production did not require the effectors myosin-II, bicaudal-D, dynactin-1 or rabkinesin-6, but was facilitated by ERC1, a factor involved in linking microtubules to the cell cortex. Tubulation and exocytosis of Rab6-positive, glycoprotein-containing membranes from the Golgi was substantially augmented by infection, resulting in enhanced and targeted delivery to cell tips. This reveals HSV1 morphogenesis as one of the first biological processes shown to be dependent on the exocytic activity of Rab6.
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Affiliation(s)
- Helen L Johns
- Section of Virology, Faculty of Medicine, Imperial College LondonLondon, W2 1PG, UK
| | | | - Charlotte L Sayers
- Section of Virology, Faculty of Medicine, Imperial College LondonLondon, W2 1PG, UK
| | - Michael Hollinshead
- Section of Virology, Faculty of Medicine, Imperial College LondonLondon, W2 1PG, UK
| | - Gillian Elliott
- Section of Virology, Faculty of Medicine, Imperial College LondonLondon, W2 1PG, UK
- Current address: Department of Microbial & Cellular Sciences, Faculty of Health & Medical Sciences, University of SurreyGuildford, GU2 7XH, UK
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Rab41 is a novel regulator of Golgi apparatus organization that is needed for ER-to-Golgi trafficking and cell growth. PLoS One 2013; 8:e71886. [PMID: 23936529 PMCID: PMC3735572 DOI: 10.1371/journal.pone.0071886] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 07/03/2013] [Indexed: 12/13/2022] Open
Abstract
Background The 60+ members of the mammalian Rab protein family group into subfamilies postulated to share common functionality. The Rab VI subfamily contains 5 Rab proteins, Rab6a/a’, Rab6b, Rab6c and Rab41. High-level knockdown of Rab6a/a’ has little effect on the tightly organized Golgi ribbon in HeLa cells as seen by fluorescence microscopy. In striking contrast, we found Rab41 was strongly required for normal Golgi ribbon organization. Methods/Results Treatment of HeLa cells with Rab41 siRNAs scattered the Golgi ribbon into clustered, punctate Golgi elements. Overexpression of GDP-locked Rab41, but not wild type or GTP-locked Rab41, produced a similar Golgi phenotype. By electron microscopy, Rab41 depletion produced short, isolated Golgi stacks. Golgi-associated vesicles accumulated. At low expression levels, wild type and GTP-locked Rab41 showed little concentration in the Golgi region, but puncta were observed and most were in ruffled regions at the cell periphery. There was 25% co-localization of GTP-locked Rab41 with the ER marker, Sec61p. GDP-locked Rab41, as expected, displayed an entirely diffuse cytoplasmic distribution. Depletion of Rab41 or overexpression of GDP-locked Rab41 partially inhibited ER-to-Golgi transport of VSV-G protein. However, Rab41 knockdown had little, if any, effect on endosome-to-Golgi transport of SLTB. Additionally, after a 2-day delay, treatment with Rab41 siRNA inhibited cell growth, while overexpression of GDP-locked Rab41, but not wild type or GTP-locked Rab41, produced a rapid, progressive cell loss. In double knockdown experiments with Rab6, the Golgi ribbon was fragmented, a result consistent with Rab41 and Rab6 acting in parallel. Conclusion We provide the first evidence for distinctive Rab41 effects on Golgi organization, ER-to-Golgi trafficking and cell growth. When combined with the evidence that Rab6a/a’ and Rab6b have diverse roles in Golgi function, while Rab6c regulates mitotic function, our data indicate that Rab VI subfamily members, although related by homology and structure, share limited functional conservation.
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47
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The jaw of the worm: GTPase-activating protein EAT-17 regulates grinder formation in Caenorhabditis elegans. Genetics 2013; 195:115-25. [PMID: 23792950 DOI: 10.1534/genetics.113.152538] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Constitutive transport of cellular materials is essential for cell survival. Although multiple small GTPase Rab proteins are required for the process, few regulators of Rabs are known. Here we report that EAT-17, a novel GTPase-activating protein (GAP), regulates RAB-6.2 function in grinder formation in Caenorhabditis elegans. We identified EAT-17 as a novel RabGAP that interacts with RAB-6.2, a protein that presumably regulates vesicle trafficking between Golgi, the endoplasmic reticulum, and plasma membrane to form a functional grinder. EAT-17 has a canonical GAP domain that is critical for its function. RNA interference against 25 confirmed and/or predicted RABs in C. elegans shows that RNAi against rab-6.2 produces a phenotype identical to eat-17. A directed yeast two-hybrid screen using EAT-17 as bait and each of the 25 RAB proteins as prey identifies RAB-6.2 as the interacting partner of EAT-17, confirming that RAB-6.2 is a specific substrate of EAT-17. Additionally, deletion mutants of rab-6.2 show grinder defects identical to those of eat-17 loss-of-function mutants, and both RAB-6.2 and EAT-17 are expressed in the terminal bulb of the pharynx where the grinder is located. Collectively, these results suggest that EAT-17 is a specific GTPase-activating protein for RAB-6.2. Based on the conserved function of Rab6 in vesicular transport, we propose that EAT-17 regulates the turnover rate of RAB-6.2 activity in cargo trafficking for grinder formation.
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A new Mint1 isoform, but not the conventional Mint1, interacts with the small GTPase Rab6. PLoS One 2013; 8:e64149. [PMID: 23737971 PMCID: PMC3667844 DOI: 10.1371/journal.pone.0064149] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 04/09/2013] [Indexed: 12/31/2022] Open
Abstract
Small GTPases of the Rab family are important regulators of a large variety of different cellular functions such as membrane organization and vesicle trafficking. They have been shown to play a role in several human diseases. One prominent member, Rab6, is thought to be involved in the development of Alzheimer's Disease, the most prevalent mental disorder worldwide. Previous studies have shown that Rab6 impairs the processing of the amyloid precursor protein (APP), which is cleaved to β-amyloid in brains of patients suffering from Alzheimer's Disease. Additionally, all three members of the Mint adaptor family are implied to participate in the amyloidogenic pathway. Here, we report the identification of a new Mint1 isoform in a yeast two-hybrid screening, Mint1 826, which lacks an eleven amino acid (aa) sequence in the conserved C-terminal region. Mint1 826, but not the conventional Mint1, interacts with Rab6 via the PTB domain. This interaction is nucleotide-dependent, Rab6-specific and influences the subcellular localization of Mint1 826. We were able to detect and sequence a corresponding proteolytic peptide derived from cellular Mint1 826 by mass spectrometry proving the absence of aa 495-505 and could show that the deletion does not influence the ability of this adaptor protein to interact with APP. Taking into account that APP interacts and co-localizes with Mint1 826 and is transported in Rab6 positive vesicles, our data suggest that Mint1 826 bridges APP to the small GTPase at distinct cellular sorting points, establishing Mint1 826 as an important player in regulation of APP trafficking and processing.
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Pla-Martín D, Rueda CB, Estela A, Sánchez-Piris M, González-Sánchez P, Traba J, de la Fuente S, Scorrano L, Renau-Piqueras J, Alvarez J, Satrústegui J, Palau F. Silencing of the Charcot-Marie-Tooth disease-associated gene GDAP1 induces abnormal mitochondrial distribution and affects Ca2+ homeostasis by reducing store-operated Ca2+ entry. Neurobiol Dis 2013; 55:140-51. [PMID: 23542510 DOI: 10.1016/j.nbd.2013.03.010] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 03/04/2013] [Accepted: 03/19/2013] [Indexed: 11/25/2022] Open
Abstract
GDAP1 is an outer mitochondrial membrane protein that acts as a regulator of mitochondrial dynamics. Mutations of the GDAP1 gene cause Charcot-Marie-Tooth (CMT) neuropathy. We show that GDAP1 interacts with the vesicle-organelle trafficking proteins RAB6B and caytaxin, which suggests that GDAP1 may participate in the mitochondrial movement within the cell. GDAP1 silencing in the SH-SY5Y cell line induces abnormal distribution of the mitochondrial network, reduces the contact between mitochondria and endoplasmic reticulum (ER) and alters the mobilization of mitochondria towards plasma membrane upon depletion of ER-Ca(2+) stores. GDAP1 silencing does not affect mitochondrial Ca(2+) uptake, ER-Ca(2+), or Ca(2+) flow from ER to mitochondria, but reduces Ca(2+) inflow through store-operated Ca(2+) entry (SOCE) following mobilization of ER-Ca(2+) and SOCE-driven Ca(2+) entry in mitochondria. Our studies suggest that the pathophysiology of GDAP1-related CMT neuropathies may be associated with abnormal distribution and movement of mitochondria throughout cytoskeleton towards the ER and subplasmalemmal microdomains, resulting in a decrease in SOCE activity and impaired SOCE-driven Ca(2+) uptake in mitochondria.
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Affiliation(s)
- David Pla-Martín
- Laboratory of Genetics and Molecular Medicine, Instituto de Biomedicina de Valencia, CSIC, Valencia, Spain
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Rab6a/a' are important Golgi regulators of pro-inflammatory TNF secretion in macrophages. PLoS One 2013; 8:e57034. [PMID: 23437303 PMCID: PMC3578815 DOI: 10.1371/journal.pone.0057034] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 01/16/2013] [Indexed: 02/06/2023] Open
Abstract
Lipopolysaccharide (LPS)-activated macrophages secrete pro-inflammatory cytokines, including tumor necrosis factor (TNF) to elicit innate immune responses. Secretion of these cytokines is also a major contributing factor in chronic inflammatory disease. In previous studies we have begun to elucidate the pathways and molecules that mediate the intracellular trafficking and secretion of TNF. Rab6a and Rab6a' (collectively Rab6) are trans-Golgi-localized GTPases known for roles in maintaining Golgi structure and Golgi-associated trafficking. We found that induction of TNF secretion by LPS promoted the selective increase of Rab6 expression. Depletion of Rab6 (via siRNA and shRNA) resulted in reorganization of the Golgi ribbon into more compact structures that at the resolution of electron microcopy consisted of elongated Golgi stacks that likely arose from fusion of smaller Golgi elements. Concomitantly, the delivery of TNF to the cell surface and subsequent release into the media was reduced. Dominant negative mutants of Rab6 had similar effects in disrupting TNF secretion. In live cells, Rab6-GFP were localized on trans-Golgi network (TGN)-derived tubular carriers demarked by the golgin p230. Rab6 depletion and inactive mutants altered carrier egress and partially reduced p230 membrane association. Our results show that Rab6 acts on TNF trafficking at the level of TGN exit in tubular carriers and our findings suggest Rab6 may stabilize p230 on the tubules to facilitate TNF transport. Both Rab6 isoforms are needed in macrophages for Golgi stack organization and for the efficient post-Golgi transport of TNF. This work provides new insights into Rab6 function and into the role of the Golgi complex in cytokine secretion in inflammatory macrophages.
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