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Soto F, San Martín-Davison A, Salinas-Cornejo J, Madrid-Espinoza J, Ruiz-Lara S. Identification, Classification, and Transcriptional Analysis of Rab GTPase Genes from Tomato ( Solanum lycopersicum) Reveals Salt Stress Response Genes. Genes (Basel) 2024; 15:453. [PMID: 38674387 PMCID: PMC11049601 DOI: 10.3390/genes15040453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 03/27/2024] [Accepted: 03/30/2024] [Indexed: 04/28/2024] Open
Abstract
Salinity in plants generates an osmotic and ionic imbalance inside cells that compromises the viability of the plant. Rab GTPases, the largest family within the small GTPase superfamily, play pivotal roles as regulators of vesicular trafficking in plants, including the economically important and globally cultivated tomato (Solanum lycopersicum). Despite their significance, the specific involvement of these small GTPases in tomato vesicular trafficking and their role under saline stress remains poorly understood. In this work, we identified and classified 54 genes encoding Rab GTPases in cultivated tomato, elucidating their genomic distribution and structural characteristics. We conducted an analysis of duplication events within the S. lycopersicum genome, as well as an examination of gene structure and conserved motifs. In addition, we investigated the transcriptional profiles for these Rab GTPases in various tissues of cultivated and wild tomato species using microarray-based analysis. The results showed predominantly low expression in most of the genes in both leaves and vegetative meristem, contrasting with notably high expression levels observed in seedling roots. Also, a greater increase in gene expression in shoots from salt-tolerant wild tomato species was observed under normal conditions when comparing Solanum habrochaites, Solanum pennellii, and Solanum pimpinellifolium with S. lycopersicum. Furthermore, an expression analysis of Rab GTPases from Solanum chilense in leaves and roots under salt stress treatment were also carried out for their characterization. These findings revealed that specific Rab GTPases from the endocytic pathway and the trans-Golgi network (TGN) showed higher induction in plants exposed to saline stress conditions. Likewise, disparities in gene expression were observed both among members of the same Rab GTPase subfamily and between different subfamilies. Overall, this work emphasizes the high degree of conservation of Rab GTPases, their high functional diversification in higher plants, and the essential role in mediating salt stress tolerance and suggests their potential for further exploration of vesicular trafficking mechanisms in response to abiotic stress conditions.
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Affiliation(s)
| | | | | | | | - Simón Ruiz-Lara
- Laboratorio de Genómica Funcional, Instituto de Ciencias Biológicas, Universidad de Talca, Talca 3460000, Chile; (F.S.); (A.S.M.-D.); (J.S.-C.); (J.M.-E.)
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2
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Fordjour FK, Guo C, Ai Y, Daaboul GG, Gould SJ. A shared, stochastic pathway mediates exosome protein budding along plasma and endosome membranes. J Biol Chem 2022; 298:102394. [PMID: 35988652 PMCID: PMC9512851 DOI: 10.1016/j.jbc.2022.102394] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 08/14/2022] [Accepted: 08/16/2022] [Indexed: 11/19/2022] Open
Abstract
Exosomes are small extracellular vesicles of ∼30 to 150 nm that are secreted by all cells, abundant in all biofluids, and play important roles in health and disease. However, details about the mechanism of exosome biogenesis are unclear. Here, we carried out a cargo-based analysis of exosome cargo protein biogenesis in which we identified the most highly enriched exosomal cargo proteins and then followed their biogenesis, trafficking, and exosomal secretion to test different hypotheses for how cells make exosomes. We show that exosome cargo proteins bud from cells (i) in exosome-sized vesicles regardless of whether they are localized to plasma or endosome membranes, (ii) ∼5-fold more efficiently when localized to the plasma membrane, (iii) ∼5-fold less efficiently when targeted to the endosome membrane, (iv) by a stochastic process that leads to ∼100-fold differences in their abundance from one exosome to another, and (v) independently of small GTPase Rab27a, the ESCRT complex–associated protein Alix, or the cargo protein CD63. Taken together, our results demonstrate that cells use a shared, stochastic mechanism to bud exosome cargoes along the spectrum of plasma and endosome membranes and far more efficiently from the plasma membrane than the endosome. Our observations also indicate that the pronounced variation in content between different exosome-sized vesicles is an inevitable consequence of a stochastic mechanism of small vesicle biogenesis, that the origin membrane of exosome-sized extracellular vesicles simply cannot be determined, and that most of what we currently know about exosomes has likely come from studies of plasma membrane-derived vesicles.
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Affiliation(s)
- Francis K Fordjour
- Department of Biological Chemistry, Johns Hopkins University, Baltimore, MD, USA
| | - Chenxu Guo
- Department of Biological Chemistry, Johns Hopkins University, Baltimore, MD, USA
| | - Yiwei Ai
- Department of Biological Chemistry, Johns Hopkins University, Baltimore, MD, USA
| | | | - Stephen J Gould
- Department of Biological Chemistry, Johns Hopkins University, Baltimore, MD, USA.
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3
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Zeitz C, Nassisi M, Laurent-Coriat C, Andrieu C, Boyard F, Condroyer C, Démontant V, Antonio A, Lancelot ME, Frederiksen H, Kloeckener-Gruissem B, El-Shamieh S, Zanlonghi X, Meunier I, Roux AF, Mohand-Saïd S, Sahel JA, Audo I. CHM mutation spectrum and disease: An update at the time of human therapeutic trials. Hum Mutat 2021; 42:323-341. [PMID: 33538369 DOI: 10.1002/humu.24174] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 12/21/2020] [Accepted: 01/20/2021] [Indexed: 12/15/2022]
Abstract
Choroideremia is an X-linked inherited retinal disorder (IRD) characterized by the degeneration of retinal pigment epithelium, photoreceptors, choriocapillaris and choroid affecting males with variable phenotypes in female carriers. Unlike other IRD, characterized by a large clinical and genetic heterogeneity, choroideremia shows a specific phenotype with causative mutations in only one gene, CHM. Ongoing gene replacement trials raise further interests in this disorder. We describe here the clinical and genetic data from a French cohort of 45 families, 25 of which carry novel variants, in the context of 822 previously reported choroideremia families. Most of the variants represent loss-of-function mutations with eleven families having large (i.e. ≥6 kb) genomic deletions, 18 small insertions, deletions or insertion deletions, six showing nonsense variants, eight splice site variants and two missense variants likely to affect splicing. Similarly, 822 previously published families carry mostly loss-of-function variants. Recurrent variants are observed worldwide, some of which linked to a common ancestor, others arisen independently in specific CHM regions prone to mutations. Since all exons of CHM may harbor variants, Sanger sequencing combined with quantitative polymerase chain reaction or multiplex ligation-dependent probe amplification experiments are efficient to achieve the molecular diagnosis in patients with typical choroideremia features.
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Affiliation(s)
- Christina Zeitz
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Marco Nassisi
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | | | - Camille Andrieu
- CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC1423, Paris, France
| | - Fiona Boyard
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | | | - Vanessa Démontant
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Aline Antonio
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | | | - Helen Frederiksen
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Barbara Kloeckener-Gruissem
- Institute of Medical Molecular Genetics, University of Zurich, Schlieren, Switzerland.,Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Said El-Shamieh
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France.,Department of Medical Laboratory Technology, Faculty of Health Sciences, Beirut Arab University, Beirut, Lebanon
| | - Xavier Zanlonghi
- Clinique Pluridisciplinaire Jules Verne, Institut Ophtalmologique de l'Ouest, Nantes, France
| | - Isabelle Meunier
- National Reference Centre for Inherited Sensory Diseases, University of Montpellier, Montpellier University Hospital, Montpellier, France.,Institute for Neurosciences of Montpellier (INM), University of Montpellier, INSERM, Montpellier, France
| | - Anne-Françoise Roux
- Laboratoire de Génétique Moléculaire, CHU de Montpellier, Université de Montpellier, Montpellier, France
| | - Saddek Mohand-Saïd
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France.,CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC1423, Paris, France
| | - José-Alain Sahel
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France.,CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC1423, Paris, France.,Fondation Ophtalmologique Adolphe de Rothschild, Paris, France.,Académie des Sciences-Institut de France, Paris, France.,Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Isabelle Audo
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France.,CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC1423, Paris, France.,Department of Genetics, UCL-Institute of Ophthalmology, London, UK
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4
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De Silva SR, Arno G, Robson AG, Fakin A, Pontikos N, Mohamed MD, Bird AC, Moore AT, Michaelides M, Webster AR, Mahroo OA. The X-linked retinopathies: Physiological insights, pathogenic mechanisms, phenotypic features and novel therapies. Prog Retin Eye Res 2020; 82:100898. [PMID: 32860923 DOI: 10.1016/j.preteyeres.2020.100898] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 08/07/2020] [Accepted: 08/21/2020] [Indexed: 02/08/2023]
Abstract
X-linked retinopathies represent a significant proportion of monogenic retinal disease. They include progressive and stationary conditions, with and without syndromic features. Many are X-linked recessive, but several exhibit a phenotype in female carriers, which can help establish diagnosis and yield insights into disease mechanisms. The presence of affected carriers can misleadingly suggest autosomal dominant inheritance. Some disorders (such as RPGR-associated retinopathy) show diverse phenotypes from variants in the same gene and also highlight limitations of current genetic sequencing methods. X-linked disease frequently arises from loss of function, implying potential for benefit from gene replacement strategies. We review X-inactivation and X-linked inheritance, and explore burden of disease attributable to X-linked genes in our clinically and genetically characterised retinal disease cohort, finding correlation between gene transcript length and numbers of families. We list relevant genes and discuss key clinical features, disease mechanisms, carrier phenotypes and novel experimental therapies. We consider in detail the following: RPGR (associated with retinitis pigmentosa, cone and cone-rod dystrophy), RP2 (retinitis pigmentosa), CHM (choroideremia), RS1 (X-linked retinoschisis), NYX (complete congenital stationary night blindness (CSNB)), CACNA1F (incomplete CSNB), OPN1LW/OPN1MW (blue cone monochromacy, Bornholm eye disease, cone dystrophy), GPR143 (ocular albinism), COL4A5 (Alport syndrome), and NDP (Norrie disease and X-linked familial exudative vitreoretinopathy (FEVR)). We use a recently published transcriptome analysis to explore expression by cell-type and discuss insights from electrophysiology. In the final section, we present an algorithm for genes to consider in diagnosing males with non-syndromic X-linked retinopathy, summarise current experimental therapeutic approaches, and consider questions for future research.
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Affiliation(s)
- Samantha R De Silva
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Gavin Arno
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Anthony G Robson
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Ana Fakin
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK; Ljubljana University Medical Centre, Ljubljana, Slovenia
| | - Nikolas Pontikos
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Moin D Mohamed
- Department of Ophthalmology, Guy's & St Thomas' NHS Foundation Trust, London, UK
| | - Alan C Bird
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Anthony T Moore
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK; Department of Ophthalmology, UCSF School of Medicine, San Francisco, CA, USA
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Andrew R Webster
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Omar A Mahroo
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK; Department of Ophthalmology, Guy's & St Thomas' NHS Foundation Trust, London, UK; Section of Ophthalmology, King's College London, UK; Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK.
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5
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Ying G, Boldt K, Ueffing M, Gerstner CD, Frederick JM, Baehr W. The small GTPase RAB28 is required for phagocytosis of cone outer segments by the murine retinal pigmented epithelium. J Biol Chem 2018; 293:17546-17558. [PMID: 30228185 PMCID: PMC6231133 DOI: 10.1074/jbc.ra118.005484] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 09/12/2018] [Indexed: 12/19/2022] Open
Abstract
RAB28, a member of the RAS oncogene family, is a ubiquitous, farnesylated, small GTPase of unknown function present in photoreceptors and the retinal pigmented epithelium (RPE). Nonsense mutations of the human RAB28 gene cause recessive cone-rod dystrophy 18 (CRD18), characterized by macular hyperpigmentation, progressive loss of visual acuity, RPE atrophy, and severely attenuated cone and rod electroretinography (ERG) responses. In an attempt to elucidate the disease-causing mechanism, we generated Rab28-/- mice by deleting exon 3 and truncating RAB28 after exon 2. We found that Rab28-/- mice recapitulate features of the human dystrophy (i.e. they exhibited reduced cone and rod ERG responses and progressive retina degeneration). Cones of Rab28-/- mice extended their outer segments (OSs) to the RPE apical processes and formed enlarged, balloon-like distal tips before undergoing degeneration. The visual pigment content of WT and Rab28-/- cones was comparable before the onset of degeneration. Cone phagosomes were almost absent in Rab28-/- mice, whereas rod phagosomes displayed normal levels. A protein-protein interaction screen identified several RAB28-interacting proteins, including the prenyl-binding protein phosphodiesterase 6 δ-subunit (PDE6D) and voltage-gated potassium channel subfamily J member 13 (KCNJ13) present in the RPE apical processes. Of note, the loss of PDE6D prevented delivery of RAB28 to OSs. Taken together, these findings reveal that RAB28 is required for shedding and phagocytosis of cone OS discs.
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Affiliation(s)
- Guoxin Ying
- From the Department of Ophthalmology and Visual Sciences, University of Utah Health Science Center, Salt Lake City, Utah 84132,
| | - Karsten Boldt
- the Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Elfriede-Aulhorn-Strasse 7, D-72076 Tübingen, Germany, and
| | - Marius Ueffing
- the Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Elfriede-Aulhorn-Strasse 7, D-72076 Tübingen, Germany, and
| | - Cecilia D Gerstner
- From the Department of Ophthalmology and Visual Sciences, University of Utah Health Science Center, Salt Lake City, Utah 84132
| | - Jeanne M Frederick
- From the Department of Ophthalmology and Visual Sciences, University of Utah Health Science Center, Salt Lake City, Utah 84132
| | - Wolfgang Baehr
- From the Department of Ophthalmology and Visual Sciences, University of Utah Health Science Center, Salt Lake City, Utah 84132,
- the Departments of Neurobiology and Anatomy and
- Biology, University of Utah, Salt Lake City, Utah 84112
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6
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Feng F, Zhang J, Fan X, Yuan F, Jiang Y, Lv R, Ma Y. Downregulation of Rab27A contributes to metformin-induced suppression of breast cancer stem cells. Oncol Lett 2017; 14:2947-2953. [PMID: 28928832 PMCID: PMC5588170 DOI: 10.3892/ol.2017.6542] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Accepted: 04/28/2017] [Indexed: 01/16/2023] Open
Abstract
Cancer stem cells (CSCs) are associated with tumor initiation, therapeutic resistance, relapse and metastasis. However, the underlying mechanisms CSCs use to preserve stemness are not yet fully understood. The present study demonstrated that the expression of RAB27A, member RAS oncogene family (Rab27a), which was reported to promote tumor progression by upregulating exocytosis of extracellular vesicles, was higher in mammosphere cells than in adherent MDA-MB-231 breast cancer cells. Downregulation of Rab27A inhibited mammosphere formation by decreasing the proportion of CD44+CD24-/low cells of the MDA-MB-231 cell line. Furthermore, Rab27A overexpression redistributed the cell cycle of breast (b) CSCs. The present study revealed that downregulation of Rab27A enhanced the capacity of metformin, the most widely used oral hypoglycemic drug for the treatment of type II diabetes, to inhibit mammosphere growth. Metformin reduced the expression of Rab27A dose-dependently. These data suggested that Rab27A acts as a mediator of human bCSCs by promoting the growth of mammospheres and that synergistic suppression of Rab27A, alone or in combination with metformin, holds promise for therapeutically targeting bCSCs.
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Affiliation(s)
- Feixue Feng
- Department of Clinical Laboratory, The Affiliated Hospital of Shaanxi University of Chinese Medicine, Xianyang, Shaanxi 712000, P.R. China
| | - Jianping Zhang
- Department of Clinical Laboratory, The XianYang Central Hospital, Xianyang, Shaanxi 712000, P.R. China
| | - Xiaoxuan Fan
- Department of Clinical Laboratory, The Affiliated Hospital of Shaanxi University of Chinese Medicine, Xianyang, Shaanxi 712000, P.R. China
| | - Fang Yuan
- Department of Clinical Laboratory, The Affiliated Hospital of Shaanxi University of Chinese Medicine, Xianyang, Shaanxi 712000, P.R. China
| | - Yinghao Jiang
- Department of Pharmacogenomics, The School of Pharmacy, Fourth Military Medical University, Xi'an, Shaanxi 710032, P.R. China
| | - Ruihua Lv
- Department of Clinical Laboratory, The Affiliated Hospital of Shaanxi University of Chinese Medicine, Xianyang, Shaanxi 712000, P.R. China
| | - Yanxia Ma
- Department of Clinical Laboratory, The Affiliated Hospital of Shaanxi University of Chinese Medicine, Xianyang, Shaanxi 712000, P.R. China
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7
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Kang SM, Nam KY, Jung SY, Song KH, Kho S, No KT, Choi HK, Song JY. Inhibition of cancer cell invasion by new ((3,4-dihydroxy benzylidene)hydrazinyl)pyridine-3-sulfonamide analogs. Bioorg Med Chem Lett 2015; 26:1322-8. [PMID: 26810259 DOI: 10.1016/j.bmcl.2015.12.093] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 11/23/2015] [Accepted: 12/28/2015] [Indexed: 01/24/2023]
Abstract
Rab GTPases regulate various types of intracellular membrane trafficking in all eukaryotes. Since Rab27a and its multiple effectors are involved in exocytosis of lysosome-related organelles and play a major role in malignancy, compounds targeting Rab27a could be likely used to inhibit invasive growth and tumor metastasis. Thus, we designed and synthesized several compounds based on the previously reported Rab27a-targeting synthetic compounds identified by virtual screening, and investigated their anti-metastatic effects in MDA-MB231 and A375 cells. Among the synthesized compounds, (E)-N-(3-chlorophenyl)-6-(2-(3,4-dihydroxy benzylidene)hydrazinyl)pyridine-3-sulfonamide (3d) and (E)-N-benzyl-6-(2-(3,4-dihydroxy benzylidene)hydrazinyl)-N-methylpyridine-3-sulfonamide (3f) significantly inhibited the invasiveness of both tumor cell lines. Compounds 3d and 3f also decreased the levels of signature extracellular matrix marker proteins (fibronectin, collagen, and α-smooth muscle actin) and representative mesenchymal cell markers (N-cadherin and vimentin). Taken together, our results suggest that novel sulfonamide analogs have anti-metastatic activity in breast and melanoma cancer cell lines and may be used as therapeutic agents to treat malignant cancer.
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Affiliation(s)
- Seong-Mook Kang
- Division of Radiation Cancer Research, Korea Institute of Radiological & Medical Sciences, Seoul 139-706, Republic of Korea
| | - Ky-Youb Nam
- Center for Development and Commercialization Anti-Cancer Therapeutics, Asan Medical Center, Seoul 138-736, Republic of Korea
| | - Seung-Youn Jung
- Division of Radiation Cancer Research, Korea Institute of Radiological & Medical Sciences, Seoul 139-706, Republic of Korea
| | - Kyung-Hee Song
- Division of Radiation Cancer Research, Korea Institute of Radiological & Medical Sciences, Seoul 139-706, Republic of Korea
| | - Seongho Kho
- Division of Radiation Cancer Research, Korea Institute of Radiological & Medical Sciences, Seoul 139-706, Republic of Korea
| | - Kyoung Tai No
- Department of Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea
| | - Hyun Kyung Choi
- Department of Medicinal Chemistry, Jungwon University, Goesan 367-805, Republic of Korea.
| | - Jie-Young Song
- Division of Radiation Cancer Research, Korea Institute of Radiological & Medical Sciences, Seoul 139-706, Republic of Korea.
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8
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Chen TC, Hsieh CH, Sarnow P. Supporting Role for GTPase Rab27a in Hepatitis C Virus RNA Replication through a Novel miR-122-Mediated Effect. PLoS Pathog 2015; 11:e1005116. [PMID: 26305877 PMCID: PMC4549268 DOI: 10.1371/journal.ppat.1005116] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 07/28/2015] [Indexed: 12/12/2022] Open
Abstract
The small GTPase Rab27a has been shown to control membrane trafficking and microvesicle transport pathways, in particular the secretion of exosomes. In the liver, high expression of Rab27a correlates with the development of hepatocellular carcinoma. We discovered that low abundance of Rab27a resulted in decreased hepatitis C virus (HCV) RNA and protein abundances in virus-infected cells. Curiously, both cell-associated and extracellular virus yield decreased in Rab27a depleted cells, suggesting that reduced exosome secretion did not cause the observed effect. Instead, Rab27a enhanced viral RNA replication by a mechanism that involves the liver-specific microRNA miR-122. Rab27a surrounded lipid droplets and was enriched in membrane fractions that harbor viral replication proteins, suggesting a supporting role for Rab27a in viral gene expression. Curiously, Rab27a depletion decreased the abundance of miR-122, whereas overexpression of miR-122 in Rab27a-depleted cells rescued HCV RNA abundance. Because intracellular HCV RNA abundance is enhanced by the binding of two miR-122 molecules to the extreme 5’ end of the HCV RNA genome, the diminished amounts of miR-122 in Rab27a-depleted cells could have caused destabilization of HCV RNA. However, the abundance of HCV RNA carrying mutations on both miR-122-binding sites and whose stability was supported by ectopically expressed miR-122 mimetics with compensatory mutations also decreased in Rab27a-depleted cells. This result indicates that the effect of Rab27a depletion on HCV RNA abundance does not depend on the formation of 5’ terminal HCV/miR-122 RNA complexes, but that miR-122 has a Rab27a-dependent function in the HCV lifecycle, likely the downregulation of a cellular inhibitor of HCV gene expression. These findings suggest that the absence of miR-122 results in a vulnerability not only to exoribonucleases that attack the viral genome, but also to upregulation of one more cellular factor that inhibit viral gene expression. Eukaryotic cells constantly expel a variety of small vesicles that are loaded with proteins, nucleic acids and other small compounds that were produced inside the cell. One particular kind of vesicle is called exosome. Exosomes are initially located in multivesicular compartments inside cells and are docked at the cell surface membrane by the small GTPase Rab27a. In the liver, high expression of Rab27a correlates with the development of hepatocellular carcinoma, suggesting a high trafficking capacity for exosomes. Also, it has been shown that hepatitis C virus (HCV) can spread from cell to cell via exosomes. We discovered that Rab27a abundance affects HCV virion abundance that independent from its role in exosome secretion. The presence of Rab27a in membrane-enriched replication complexes and nearby lipid droplets points to functions of Rab27a in the viral life cycle. Depletion of Rab27a resulted in a lower abundance of the liver-specific microRNA miR-122. It is known that two molecules of miR-122 form an oligomeric complex with the 5’ end of the viral RNA leading to protection of the viral RNA against cellular nucleases. However, we show that the Rab27a-mediated loss of miR-122 was independent of its role in protecting the viral RNA, very likely by the downregulation of a cellular inhibitor of HCV gene expression. These findings argue for novel, hitherto undetected roles for miR-122 in the viral life cycle.
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Affiliation(s)
- Tzu-Chun Chen
- Department of Microbiology & Immunology, School of Medicine, Stanford University, Stanford, California, United States of America
| | - Chung-Han Hsieh
- Department of Neurosurgery, School of Medicine, Stanford University, Stanford, California, United States of America
| | - Peter Sarnow
- Department of Microbiology & Immunology, School of Medicine, Stanford University, Stanford, California, United States of America
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9
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Dimopoulos IS, Chan S, MacLaren RE, MacDonald IM. Pathogenic mechanisms and the prospect of gene therapy for choroideremia. Expert Opin Orphan Drugs 2015; 3:787-798. [PMID: 26251765 PMCID: PMC4522943 DOI: 10.1517/21678707.2015.1046434] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
INTRODUCTION Choroideremia is a rare, X-linked disorder recognized by its specific ocular phenotype as a progressive degenerative retinopathy resulting in blindness. New therapeutic approaches, primarily based on genetic mechanisms, have emerged that aim to prevent the progressive vision loss. AREAS COVERED This article will review the research that has progressed incrementally over the past two decades from mapping to gene discovery, uncovering the presumed mechanisms triggering the retinopathy to preclinical testing of potential therapies. EXPERT OPINION While still in an evaluative phase, the introduction of gene replacement as a potential therapy has been greeted with great enthusiasm by patients, advocacy groups and the medical community.
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Affiliation(s)
- Ioannis S Dimopoulos
- University of Alberta, Department of Ophthalmology and Visual Sciences, Edmonton, Alberta, Canada
| | - Stephanie Chan
- University of Alberta, Department of Ophthalmology and Visual Sciences, Edmonton, Alberta, Canada
| | - Robert E MacLaren
- Oxford Eye Hospital and Nuffield Laboratory of Ophthalmology, John Radcliffe Hospital, Oxford, UK
- Moorfields Eye Hospital Foundation Trust, NIHR Ophthalmology Biomedical Research Centre, London, UK
| | - Ian M MacDonald
- University of Alberta, Department of Ophthalmology and Visual Sciences, Edmonton, Alberta, Canada
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10
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Barnard AR, Groppe M, MacLaren RE. Gene therapy for choroideremia using an adeno-associated viral (AAV) vector. Cold Spring Harb Perspect Med 2014; 5:a017293. [PMID: 25359548 DOI: 10.1101/cshperspect.a017293] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Choroideremia is an outer retinal degeneration with a characteristic clinical appearance that was first described in the nineteenth century. The disorder begins with reduction of night vision and gradually progresses to blindness by middle age. The appearance of the fundus in sufferers is recognizable by the characteristic pale color caused by the loss of the outer retina, retinal-pigmented epithelium, and choroidal vessels, leading to exposure of the underlying sclera. Choroideremia shows X-linked recessive inheritance and the choroideremia gene (CHM) was one of the first to be identified by positional cloning in 1990. Subsequent identification and characterization of the CHM gene, which encodes Rab escort protein 1 (REP1), has led to better comprehension of the disease and enabled advances in genetic diagnosis. Despite several decades of work to understand the exact pathogenesis, no established treatments currently exist to stop or even slow the progression of retinal degeneration in choroideremia. Encouragingly, several specific molecular and clinical features make choroideremia an ideal candidate for treatment with gene therapy. This work describes the considerations and challenges in the development of a new clinical trial using adeno-associated virus (AAV) encoding the CHM gene.
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Affiliation(s)
- Alun R Barnard
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences and Oxford Biomedical Research Centre, University of Oxford, The John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom
| | - Markus Groppe
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences and Oxford Biomedical Research Centre, University of Oxford, The John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom Moorfields Eye Hospital and NIHR Biomedical Research Centre for Ophthalmology, London EC1V 2PD, United Kingdom
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences and Oxford Biomedical Research Centre, University of Oxford, The John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom Moorfields Eye Hospital and NIHR Biomedical Research Centre for Ophthalmology, London EC1V 2PD, United Kingdom
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Dong WW, Mou Q, Chen J, Cui JT, Li WM, Xiao WH. Differential expression of Rab27A/B correlates with clinical outcome in hepatocellular carcinoma. World J Gastroenterol 2012; 18:1806-13. [PMID: 22553406 PMCID: PMC3332295 DOI: 10.3748/wjg.v18.i15.1806] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 02/28/2012] [Accepted: 03/20/2012] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the association of Rab27A and Rab27B expression with clinicopathological characteristics and prognosis of hepatocellular carcinoma (HCC).
METHODS: We used reverse transcription polymerase chain reaction (RT-PCR), real-time PCR, and Western blotting to detect Rab27A and Rab27B mRNA and protein expression in 5 human HCC lines and the immortalized hepatic HL-7702 cell line. We further examined 148 primary HCC samples matched with adjacent normal tissue and 80 non-HCC specimens by immunohistochemistry to evaluate the correlation of Rab27A and Rab27B expression with clinicopathological features and prognosis.
RESULTS: Our data showed that Rab27A and Rab27B were differentially expressed in cell lines and primary HCC tumors. Rab27A mRNA and protein were detected in 67% (4/6) of human cell lines and 80% (4/5) of HCC cell lines, while Rab27B was found in 50% (3/6) of human lines and 40% (2/5) of HCC lines. Rab27A expression was higher in primary HCC (46.2%, 66/143) than in matched adjacent tissue (24.3%, 33/136, P < 0.001), whereas immunopositivity for Rab27B was lower in primary HCC (57.4%, 81/141) than in matched adjacent tissue (87.5%, 119/136, P < 0.001). Analysis of clinicopathological characteristics of 148 HCC specimens revealed significant correlations between Rab27A and Rab27B expression and tumor tumor-node-metastasis (TNM) classification (P = 0.046 and P = 0.027, respectively), and between strong Rab27A expression and tumor differentiation grade (P = 0.008). Survival analyses revealed that patients with Rab27A+ or Rab27B+ tumors had significantly reduced overall survival compared with that of patients with Rab27A- or Rab27B- tumors (P = 0.015 and P = 0.005, respectively). Risk analyses revealed that Rab27B+ and TNM III-IV were independent poor prognosis factors associated with a 3.36- and 3.37- fold higher relative risk of death, respectively.
CONCLUSION: Rab27A and Rab27B expression were closely correlated with tumor progression and can be valuable prognostic indicators for HCC patients.
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Pazienza V. Ophthalmological complications in hepatitis C virus infection: side effect of interferon therapy or a direct role of HCV? Biomed Pharmacother 2011; 65:317-8. [PMID: 21705184 DOI: 10.1016/j.biopha.2011.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Accepted: 04/19/2011] [Indexed: 10/18/2022] Open
Abstract
Several clinical studies have demonstrated that retinopathy and ophthalmic complications are features that appear mostly as side effects in HCV patients undergoing interferon (IFN) therapy. Here we underline that HCV itself is also able to modulate genes involved in ocular pathologies. Presently an in vitro model of ocular tissue derived cells infected with HCV is missing. The establishment of such in vitro models would be helpful to better understand the mechanisms through which HCV induces optical pathologies in order to specifically target the causes of ocular disease.
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Vincent LM, Gilbert F, DiPace JI, Ciccone C, Markello TC, Jeong A, Dorward H, Westbroek W, Gahl WA, Bussel JB, Huizing M. Novel 47.5-kb deletion in RAB27A results in severe Griscelli Syndrome Type 2. Mol Genet Metab 2010; 101:62-5. [PMID: 20591709 PMCID: PMC2922439 DOI: 10.1016/j.ymgme.2010.05.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Revised: 05/10/2010] [Accepted: 05/10/2010] [Indexed: 02/08/2023]
Abstract
Griscelli syndrome (GS), a rare autosomal recessive disorder characterized by partial albinism and immunological impairment and/or severe neurological impairment, results from mutations in the MYO5A (GS1), RAB27A (GS2), or MLPH (GS3) genes. We identified a Hispanic patient born of a consanguineous union who presented with immunodeficiency, partial albinism, hepatic dysfunction, hemophagocytosis, neurological impairment, nystagmus, and silvery hair indicative of Griscelli Syndrome Type 2 (GS2). We screened for point mutations, but only exons 2-6 of the patient's DNA could be PCR-amplified. Whole genome analysis using the Illumina 1M-Duo DNA Analysis BeadChip identified a homozygous deletion in the patient's DNA. The exact breakpoints of the 47.5-kb deletion were identified as chr15q15-q21.1: g.53332432_53379990del (NCBI Build 37.1); the patient lacks the promoter and 5'UTR regions of RAB27A, thus confirming the diagnosis of GS2.
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Affiliation(s)
- Lisa M. Vincent
- Section on Human Biochemical Genetics, Medical Genetics Branch, NHGRI, NIH, Bethesda, MD 20892, USA
| | - Fred Gilbert
- Department of Pediatrics, Division of Human Genetics, Weill Cornell Medical College and the New York Presbyterian-Weill Cornell Medical Center, New York, NY 10021, USA
| | - Jennifer I. DiPace
- Department of Pediatrics, Division of Hematology-Oncology, Weill Cornell Medical College and the New York Presbyterian-Weill Cornell Medical Center, New York, NY 10021, USA
| | - Carla Ciccone
- Section on Human Biochemical Genetics, Medical Genetics Branch, NHGRI, NIH, Bethesda, MD 20892, USA
| | - Thomas C. Markello
- Section on Human Biochemical Genetics, Medical Genetics Branch, NHGRI, NIH, Bethesda, MD 20892, USA
| | - Andrew Jeong
- Section on Human Biochemical Genetics, Medical Genetics Branch, NHGRI, NIH, Bethesda, MD 20892, USA
| | - Heidi Dorward
- Section on Human Biochemical Genetics, Medical Genetics Branch, NHGRI, NIH, Bethesda, MD 20892, USA
| | - Wendy Westbroek
- Section on Human Biochemical Genetics, Medical Genetics Branch, NHGRI, NIH, Bethesda, MD 20892, USA
| | - William A. Gahl
- Section on Human Biochemical Genetics, Medical Genetics Branch, NHGRI, NIH, Bethesda, MD 20892, USA
- Intramural Office of Rare Diseases, Office of the Director, NIH, Bethesda, MD 20892, USA
| | - James B. Bussel
- Department of Pediatrics, Division of Hematology-Oncology, Weill Cornell Medical College and the New York Presbyterian-Weill Cornell Medical Center, New York, NY 10021, USA
| | - Marjan Huizing
- Section on Human Biochemical Genetics, Medical Genetics Branch, NHGRI, NIH, Bethesda, MD 20892, USA
- Address correspondence to: Marjan Huizing, PhD, 10 Center Drive, Bldg. 10, Rm 10C103, MSC1851, Bethesda, Maryland 20892-1851, Phone: 301-402-2797, Fax: 301-480-7825,
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Vachtenheim J, Borovanský J. “Transcription physiology” of pigment formation in melanocytes: central role of MITF. Exp Dermatol 2010; 19:617-27. [PMID: 20201954 DOI: 10.1111/j.1600-0625.2009.01053.x] [Citation(s) in RCA: 263] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Meschede IP, Santos TO, Izidoro-Toledo TC, Gurgel-Gianetti J, Espreafico EM. Griscelli syndrome-type 2 in twin siblings: case report and update on RAB27A human mutations and gene structure. Braz J Med Biol Res 2009; 41:839-48. [PMID: 19030707 DOI: 10.1590/s0100-879x2008001000002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2008] [Accepted: 10/09/2008] [Indexed: 11/22/2022] Open
Abstract
Griscelli syndrome (GS) is a rare autosomal recessive disorder caused by mutation in the MYO5A (GS1, Elejalde), RAB27A (GS2) or MLPH (GS3) genes. Typical features of all three subtypes of this disease include pigmentary dilution of the hair and skin and silvery-gray hair. Whereas the GS3 phenotype is restricted to the pigmentation dysfunction, GS1 patients also show primary neurological impairment and GS2 patients have severe immunological deficiencies that lead to recurrent infections and hemophagocytic syndrome. We report here the diagnosis of GS2 in 3-year-old twin siblings, with silvery-gray hair, immunodeficiency, hepatosplenomegaly and secondary severe neurological symptoms that culminated in multiple organ failure and death. Light microscopy examination of the hair showed large, irregular clumps of pigments characteristic of GS. A homozygous nonsense mutation, C-T transition (c.550C>T), in the coding region of the RAB27A gene, which leads to a premature stop codon and prediction of a truncated protein (R184X), was found. In patient mononuclear cells, RAB27A mRNA levels were the same as in cells from the parents, but no protein was detected. In addition to the case report, we also present an updated summary on the exon/intron organization of the human RAB27A gene, a literature review of GS2 cases, and a complete list of the human mutations currently reported in this gene. Finally, we propose a flow chart to guide the early diagnosis of the GS subtypes and Chédiak-Higashi syndrome.
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Affiliation(s)
- I P Meschede
- Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
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Wang JS, Wang FB, Zhang QG, Shen ZZ, Shao ZM. Enhanced expression of Rab27A gene by breast cancer cells promoting invasiveness and the metastasis potential by secretion of insulin-like growth factor-II. Mol Cancer Res 2008; 6:372-82. [PMID: 18337447 DOI: 10.1158/1541-7786.mcr-07-0162] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In addition to the functions of transporting melanosome in melanocytes and releasing contents of lytic granules in CTLs, Rab27A was recently shown to be involved in exocytosis of insulin and chromaffin granules in endocrine cells; it was also reported to be expressed in an exceptionally broad range of specialized secretory cells. As autocrine and paracrine cytokines are essential for invasion and metastasis in some solid tumors, blocking them may be an effective strategy to prevent tumor dissemination. In the present study, we show that Rab27A is associated with invasive and metastatic potentials of human breast cancer cells. The overexpression of Rab27A protein redistributed the cell cycle and increased the invasive and metastatic abilities in breast cancer cells both in vitro and in vivo. We also certified that Rab27A conferred the invasive and metastatic phenotypes on breast cancer cells by promoting the secretion of insulin-like growth factor-II (IGF-II), which regulates the expression of p16, vascular endothelial growth factor, matrix metalloproteinase-9, cathepsin D, cyclin D1, and urokinase-type plasminogen activator. These data provide functional evidence that Rab27A acts as a novel mediator of invasion and metastasis promotion in human breast cancer cells, at least in part, through regulating the secretion of IGF-II, suggesting that synergistic suppression of Rab27A and IGF-II activities holds a promise for preventing breast cancer invasion and metastasis.
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Affiliation(s)
- Jin-Song Wang
- Department of Oncology, Breast Cancer Institute, Cancer Hospital, Fudan University, Shanghai 200032, PR China
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Mamishi S, Modarressi MH, Pourakbari B, Tamizifar B, Mahjoub F, Fahimzad A, Alyasin S, Bemanian MH, Hamidiyeh AA, Fazlollahi MR, Ashrafi MR, Isaeian A, Khotaei G, Yeganeh M, Parvaneh N. Analysis of RAB27A gene in griscelli syndrome type 2: novel mutations including a deletion hotspot. J Clin Immunol 2008; 28:384-9. [PMID: 18350256 DOI: 10.1007/s10875-008-9192-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2007] [Accepted: 02/19/2008] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Griscelli syndrome type 2 is an autosomal recessive disorder characterized by pigmentary dilution and occurrence of acute phases of hemophagocytosis. The disease is caused by mutations in RAB27A gene, coding a small GTPase involved in terminal phases of cytotoxic granule/melanosome exocytosis. MATERIALS AND METHODS We describe the result of mutation analysis among nine patients from seven non-related Persian families. We present four novel mutations including a deletion hot spot (514del 5). CONCLUSION This hot spot is flanked by "direct repeats" of nucleotides, which are previously shown to be associated with areas of recurrent small deletions.
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Affiliation(s)
- Setareh Mamishi
- Infectious Disease Research Center, Children's Medical Center, 62 Gharib St, 14194 Tehran, Iran
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Chiaverini C, Beuret L, Flori E, Busca R, Abbe P, Bille K, Bahadoran P, Ortonne JP, Bertolotto C, Ballotti R. Microphthalmia-associated transcription factor regulates RAB27A gene expression and controls melanosome transport. J Biol Chem 2008; 283:12635-42. [PMID: 18281284 DOI: 10.1074/jbc.m800130200] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Melanosomes are lysosome-related organelles specialized in melanin synthesis and transport. In this study, we show that microphthalmia-associated transcription factor (MITF) silencing induces melanosome gathering around the nucleus and causes the relocalization of Rab27A, Slac2a-Mlph, and Myo5a that control the transport of melanosomes on the actin network. In an attempt to elucidate the mechanism by which MITF controls melanosome distribution, we identify RAB27A as a new MITF target gene. Indeed, MITF silencing leads to a dramatic decrease in Rab27A expression and blocks the stimulation of Rab27A expression evoked by cAMP. Further, forced expression of MITF increases Rab27A expression, indicating that MITF is required and sufficient for Rab27A expression in melanoma cells. MITF binds to two E-boxes in the proximal region of the Rab27A promoter and stimulates its transcriptional activity. Finally, re-expression of Rab27A, in MITF-depleted cells, restores the transport of melanosomes to the cell periphery. These results show that RAB27A is a new direct transcriptional target of MITF and link MITF to melanosome transport, another key parameter of melanocyte differentiation and skin pigmentation. Interestingly, Rab27A is involved in other fundamental physiological functions, such as the transport of lytic granules and insulin secretion. Thus our results, deciphering the mechanism of Rab27A transcriptional regulation, have an interest that goes beyond the skin pigmentation field.
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Affiliation(s)
- Christine Chiaverini
- INSERM U895, Biologie et Pathologies des Cellules Mélanocytaires de la Pigmentation Cutanée au Mélanome 28, avenue de Valombrose, 06107 Nice Cedex 2, France
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Ménasché G, Feldmann J, Fischer A, de Saint Basile G. Primary hemophagocytic syndromes point to a direct link between lymphocyte cytotoxicity and homeostasis. Immunol Rev 2005; 203:165-79. [PMID: 15661029 DOI: 10.1111/j.0105-2896.2005.00224.x] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Hemophagocytic syndrome (HS) is a severe and often fatal syndrome resulting from potent and uncontrolled activation and proliferation of T-lymphocytes, leading to excessive macrophage activation and multiple deleterious effects. The onset of HS characterizes several inherited disorders in humans. In each condition, the molecular defect impairs the granule-dependent cytotoxic activity of lymphocytes, thus highlighting the determinant role of this function in driving the immune system to a state of equilibrium following infection. It has also been shown that some of the proteins required for lytic granule secretion are required for melanocyte function, leading to associated hypopigmentation in these conditions. This review focuses on several effectors of this secretory pathway, recently identified, because their defects cause these disorders, and discusses their role and molecular interactions in granule-dependent cytotoxic activity.
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Affiliation(s)
- Gael Ménasché
- INSERM U429, Hôpital Necker Enfants-Malades, Paris, France
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Imai A, Yoshie S, Nashida T, Shimomura H, Fukuda M. The small GTPase Rab27B regulates amylase release from rat parotid acinar cells. J Cell Sci 2004; 117:1945-53. [PMID: 15039459 DOI: 10.1242/jcs.01048] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Small GTPase Rab is a large family of putative membrane trafficking proteins, and each member is thought to regulate a specific type(s) of membrane trafficking. However, little is known about the involvement of Rab protein(s) in secretory granule exocytosis in exocrine cells or the molecular mechanism underlying this process. We show that Rab27B, a closely related isoform of Rab27A that regulates lysosome-related granule exocytosis in cytotoxic T lymphocytes, is abundantly expressed on amylase-containing secretory granules in rat parotid gland acinar cells. We also identify the putative Rab27B effector protein, Slac2-c (Slp homologue lacking C2 domains-c)/MyRIP, which was originally described as a myosin Va/VIIa and actin binding protein, in rat parotid glands. The results of subcellular fractionation, immunoprecipitation and immunohistochemical studies indicate that the Rab27B-Slac2-c complex is formed on secretory granules in vivo. The introduction of either a specific Rab27 binding domain (i.e. a recombinant Slp homology domain of Slac2-b that specifically binds Rab27A/B but not other Rabs) or functionally blocking antibodies that specifically disrupt Rab27B-Slac2-c complex in vitro strongly inhibited isoproterenol-stimulated amylase release from streptolysin O-permeabilized parotid acinar cells. Our results indicate that the Rab27B-Slac2-c complex is an important constituent of secretory granule exocytosis in parotid acinar cells.
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Affiliation(s)
- Akane Imai
- Department of Biochemistry, The Nippon Dental University, School of Dentistry at Niigata, 1-8, Hamaura-cho, Niigata 951-8580, Japan
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Affiliation(s)
- Shinya IKENO
- Department of Biological Functions and Engineering, Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology
- CREST, Japan Science and Technology Agency
| | - Tetsuya HARUYAMA
- Department of Biological Functions and Engineering, Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology
- CREST, Japan Science and Technology Agency
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Tolmachova T, Anders R, Stinchcombe J, Bossi G, Griffiths GM, Huxley C, Seabra MC. A general role for Rab27a in secretory cells. Mol Biol Cell 2003; 15:332-44. [PMID: 14617806 PMCID: PMC307551 DOI: 10.1091/mbc.e03-07-0452] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Vesicular transport is a complex multistep process regulated by distinct Rab GTPases. Here, we show for the first time that an EGFP-Rab fusion protein is fully functional in a mammalian organism. We constructed a PAC-based transgenic mouse, which expresses EGFP-Rab27a under the control of endogenous Rab27a promoter. The EGFP-Rab27a transgene was fully functional and rescued the two major defects of the ashen Rab27a knockout mouse. We achieved cell-specific expression of EGFP-Rab27a, which faithfully followed the pattern of expression of endogenous Rab27a. We found that Rab27a is expressed in an exceptionally broad range of specialized secretory cells, including exocrine (particularly in mucin- and zymogen-secreting cells), endocrine, ovarian, and hematopoietic cells, most of which undergo regulated exocytosis. We suggest that Rab27a acts in concert with Rab3 proteins in most regulated secretory events. The present strategy represents one way in which the complex pattern of expression and function of proteins involved in specialized cell types may be unraveled.
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Affiliation(s)
- Tanya Tolmachova
- Cell and Molecular Biology, Division of Biomedical Sciences, Faculty of Medicine, Imperial College London, London SW7 2AZ, United Kingdom
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Anikster Y, Huizing M, Anderson PD, Fitzpatrick DL, Klar A, Gross-Kieselstein E, Berkun Y, Shazberg G, Gahl WA, Hurvitz H. Evidence that Griscelli syndrome with neurological involvement is caused by mutations in RAB27A, not MYO5A. Am J Hum Genet 2002; 71:407-14. [PMID: 12058346 PMCID: PMC379173 DOI: 10.1086/341606] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2002] [Accepted: 05/06/2002] [Indexed: 11/03/2022] Open
Abstract
Griscelli syndrome (GS), a rare autosomal recessive disorder, is characterized by partial albinism, along with immunologic abnormalities or severe neurological impairment or both. Mutations in one of two different genes on chromosome 15q can cause the different subtypes of GS. Most patients with GS display the hemophagocytic syndrome and have mutations in RAB27A, which codes for a small GTPase. Two patients with neurological involvement have mutations in MYO5A, which codes for an actin-based molecular motor. The RAB27A and MYO5A gene products interact with each other and function in vesicle trafficking. We report the molecular basis of GS in a Muslim Arab kindred whose members have extremely variable neurological involvement, along with the hemophagocytic syndrome and immunologic abnormalities. The patients have normal MYO5A genes but exhibit a homozygous 67.5-kb deletion that eliminates RAB27A mRNA and immunocytofluorescence-detectable protein. We also describe the molecular organization of RAB27A and a multiplex polymerase chain reaction assay for the founder deletion in this kindred. Finally, we propose that all patients with GS have RAB27A mutations and immunologic abnormalities that sometimes result in secondary neurological involvement. The two patients described elsewhere who have MYO5A mutations and neurological complications but no immunologic defects may not have GS but instead may have Elejalde syndrome, a condition characterized by mild hypopigmentation and severe, primary neurological abnormalities.
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Affiliation(s)
- Yair Anikster
- Heritable Disorders Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda; and Department of Pediatrics, Bikur Cholim General Hospital and Hebrew University–Hadassah Medical School, Jerusalem
| | - Marjan Huizing
- Heritable Disorders Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda; and Department of Pediatrics, Bikur Cholim General Hospital and Hebrew University–Hadassah Medical School, Jerusalem
| | - Paul D. Anderson
- Heritable Disorders Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda; and Department of Pediatrics, Bikur Cholim General Hospital and Hebrew University–Hadassah Medical School, Jerusalem
| | - Diana L. Fitzpatrick
- Heritable Disorders Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda; and Department of Pediatrics, Bikur Cholim General Hospital and Hebrew University–Hadassah Medical School, Jerusalem
| | - Aharon Klar
- Heritable Disorders Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda; and Department of Pediatrics, Bikur Cholim General Hospital and Hebrew University–Hadassah Medical School, Jerusalem
| | - Eva Gross-Kieselstein
- Heritable Disorders Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda; and Department of Pediatrics, Bikur Cholim General Hospital and Hebrew University–Hadassah Medical School, Jerusalem
| | - Yackov Berkun
- Heritable Disorders Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda; and Department of Pediatrics, Bikur Cholim General Hospital and Hebrew University–Hadassah Medical School, Jerusalem
| | - Gila Shazberg
- Heritable Disorders Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda; and Department of Pediatrics, Bikur Cholim General Hospital and Hebrew University–Hadassah Medical School, Jerusalem
| | - William A. Gahl
- Heritable Disorders Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda; and Department of Pediatrics, Bikur Cholim General Hospital and Hebrew University–Hadassah Medical School, Jerusalem
| | - Haggit Hurvitz
- Heritable Disorders Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda; and Department of Pediatrics, Bikur Cholim General Hospital and Hebrew University–Hadassah Medical School, Jerusalem
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Chen Y, Samaraweera P, Sun TT, Kreibich G, Orlow SJ. Rab27b association with melanosomes: dominant negative mutants disrupt melanosomal movement. J Invest Dermatol 2002; 118:933-40. [PMID: 12060386 DOI: 10.1046/j.1523-1747.2002.01754.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The movement of melanosomes from post-Golgi compartments to the periphery of melanocytes is known to be regulated by factors including myosin Va and at least one Rab protein, Rab27a. Mutations in the genes encoding either protein in the mouse result in a hypopigmented phenotype mimicking the human disease Griscelli syndrome. Rab27b and Rab27a share 72% identity and they belong to the same melanocyte/platelet subfamily of Rab proteins. Rab27a orchestrates the transport of melanosomes by recruitment of the actin motor, myosin Va, onto melanosomes. By contrast, the function of Rab27b has remained elusive. In this study, we found that Rab27b mRNA is present in melanocytes and demonstrated the intrinsic GTPase activity of Rab27b protein. We explored the function of Rab27b by overexpression of two dominant negative mutants as well as the wild-type Rab27b in melan-a melanocytes. Green-fluorescent-protein-tagged Rab27b colocalizes with the melanosome marker tyrosinase-related protein 1 and with myosin Va at the cell periphery, whereas Rab27b mutants do not decorate melanosomes, and melanosomes in these mutant transfected cells redistribute from cell periphery to the perinuclear region. Furthermore, transient overexpression of the dominant negative forms of Rab27b caused diminution in both numbers and length of dendrites of melan-a cells. Our results suggest that Rab27b may regulate the outward movement of melanosomes and the formation or maintenance of dendritic extensions in melanocytes.
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Affiliation(s)
- Yanru Chen
- Department of Cell Biology, New York University School of Medicine, New York, New York 10016, USA
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Kuroda TS, Fukuda M, Ariga H, Mikoshiba K. Synaptotagmin-like protein 5: a novel Rab27A effector with C-terminal tandem C2 domains. Biochem Biophys Res Commun 2002; 293:899-906. [PMID: 12051743 DOI: 10.1016/s0006-291x(02)00320-0] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Synaptotagmin-like proteins 1-4 (Slp1-4) are new members of the carboxyl-terminal-type (C-type) tandem C2 proteins and are classified as a subfamily distinct from the synaptotagmin and the Doc2 families, because the Slp family contains a unique homology domain at the amino terminus, referred to as the Slp homology domain (SHD). We previously showed that the SHD functions as a binding site for Rab27A, which is associated with human hemophagocytic syndrome (Griscelli syndrome) [J. Biol. Chem. 277 (2002) 9212; J. Biol. Chem. 277 (2002) 12432]. In the present study, we identified a novel member of the Slp family, Slp5. The same as other Slp family members, the SHD of Slp5 preferentially interacted with the GTP-bound form of Rab27A and marginally with Rab3A and Rab6A, both in vitro and in intact cells, but not with other Rabs tested (Rab1, Rab2, Rab4A, Rab5A, Rab7, Rab8, Rab9, Rab10, Rab11A, Rab17, Rab18, Rab20, Rab22, Rab23, Rab25, Rab28, and Rab37). However, unlike other members of the Slp family, expression of Slp5 mRNA was highly restricted to human placenta and liver. Expression of Slp5 protein and in vivo association of Slp5 with Rab27A in the mouse liver were further confirmed by immunoprecipitation. The results suggest that Slp5 might be involved in Rab27A-dependent membrane trafficking in specific tissues.
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Affiliation(s)
- Taruho S Kuroda
- Fukuda Initiative Research Unit, RIKEN (The Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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26
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Abstract
Rab proteins are small GTP-binding proteins that form the largest family within the Ras superfamily. Rab proteins regulate vesicular trafficking pathways, behaving as membrane-associated molecular switches. Here, we have identified the complete Rab families in the Caenorhabditis elegans (29 members), Drosophila melanogaster (29), Homo sapiens (60) and Arabidopsis thaliana (57), and we defined criteria for annotation of this protein family in each organism. We studied sequence conservation patterns and observed that the RabF motifs and the RabSF regions previously described in mammalian Rabs are conserved across species. This is consistent with conserved recognition mechanisms by general regulators and specific effectors. We used phylogenetic analysis and other approaches to reconstruct the multiplication of the Rab family and observed that this family shows a strict phylogeny of function as opposed to a phylogeny of species. Furthermore, we observed that Rabs co-segregating in phylogenetic trees show a pattern of similar cellular localisation and/or function. Therefore, animal and fungi Rab proteins can be grouped in "Rab functional groups" according to their segregating patterns in phylogenetic trees. These functional groups reflect similarity of sequence, localisation and/or function, and may also represent shared ancestry. Rab functional groups can help the understanding of the functional evolution of the Rab family in particular and vesicular transport in general, and may be used to predict general functions for novel Rab sequences.
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Affiliation(s)
- J B Pereira-Leal
- Cell and Molecular Biology Section, Division of Biomedical Sciences, Faculty of Medicine, Imperial College, London, SW7 2AZ, UK
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27
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Abstract
Choroideremia is an X-chromosome-linked disease that leads to the degeneration of the choriocapillaris, the retinal pigment epithelium and the photoreceptor layer in the eye. The gene product defective in choroideremia, CHM, is identical to Rab escort protein 1 (REP1). CHM/REP1 is an essential component of the catalytic geranylgeranyltransferase II complex (GGTrII) that delivers newly synthesized small GTPases belonging to the RAB gene family to the catalytic complex for post-translational modification. CHM/REP family members are evolutionarily related to members of the guanine nucleotide dissociation inhibitor (GDI) family, proteins involved in the recycling of Rab proteins required for vesicular membrane trafficking through the exocytic and endocytic pathways, forming the GDI/CHM superfamily. Biochemical and structural analyses have now revealed a striking parallel in the organization and function of these two families allowing us to generate a general model for GDI/CHM superfamily function in health and disease.
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Affiliation(s)
- C Alory
- Departments of Cell and Molecular Biology and Institute for Childhood and Neglected Diseases, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA
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28
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Bahadoran P, Aberdam E, Mantoux F, Buscà R, Bille K, Yalman N, de Saint-Basile G, Casaroli-Marano R, Ortonne JP, Ballotti R. Rab27a: A key to melanosome transport in human melanocytes. J Cell Biol 2001; 152:843-50. [PMID: 11266474 PMCID: PMC2195788 DOI: 10.1083/jcb.152.4.843] [Citation(s) in RCA: 185] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Normal pigmentation depends on the uniform distribution of melanin-containing vesicles, the melanosomes, in the epidermis. Griscelli syndrome (GS) is a rare autosomal recessive disease, characterized by an immune deficiency and a partial albinism that has been ascribed to an abnormal melanosome distribution. GS maps to 15q21 and was first associated with mutations in the myosin-V gene. However, it was demonstrated recently that GS can also be caused by a mutation in the Rab27a gene. These observations prompted us to investigate the role of Rab27a in melanosome transport. Using immunofluorescence and immunoelectron microscopy studies, we show that in normal melanocytes Rab27a colocalizes with melanosomes. In melanocytes isolated from a patient with GS, we show an abnormal melanosome distribution and a lack of Rab27a expression. Finally, reexpression of Rab27a in GS melanocytes restored melanosome transport to dendrite tips, leading to a phenotypic reversion of the diseased cells. These results identify Rab27a as a key component of vesicle transport machinery in melanocytes.
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Affiliation(s)
- Philippe Bahadoran
- Unité de Recherches sur la Biologie et la Physiopathologie de la Peau, Institut National de la Santé et de la Recherche Médicale U385, Faculté de Médecine, 06107 Nice Cedex 2, France
| | - Edith Aberdam
- Unité de Recherches sur la Biologie et la Physiopathologie de la Peau, Institut National de la Santé et de la Recherche Médicale U385, Faculté de Médecine, 06107 Nice Cedex 2, France
| | - Frédéric Mantoux
- Unité de Recherches sur la Biologie et la Physiopathologie de la Peau, Institut National de la Santé et de la Recherche Médicale U385, Faculté de Médecine, 06107 Nice Cedex 2, France
| | - Roser Buscà
- Unité de Recherches sur la Biologie et la Physiopathologie de la Peau, Institut National de la Santé et de la Recherche Médicale U385, Faculté de Médecine, 06107 Nice Cedex 2, France
| | - Karine Bille
- Unité de Recherches sur la Biologie et la Physiopathologie de la Peau, Institut National de la Santé et de la Recherche Médicale U385, Faculté de Médecine, 06107 Nice Cedex 2, France
| | - Nevin Yalman
- Istanbûl School of Medicine, Pediatric Hematology/Oncology, 34390 Istanbul, Turkey
| | - Geneviève de Saint-Basile
- Unité de Recherches sur le Développement Normal et Pathologique du Système Immunitaire, Institut National de la Santé et de la Recherche Médicale U429, Hôpital Necker, 75743 Paris Cedex 15, France
| | | | - Jean-Paul Ortonne
- Unité de Recherches sur la Biologie et la Physiopathologie de la Peau, Institut National de la Santé et de la Recherche Médicale U385, Faculté de Médecine, 06107 Nice Cedex 2, France
| | - Robert Ballotti
- Unité de Recherches sur la Biologie et la Physiopathologie de la Peau, Institut National de la Santé et de la Recherche Médicale U385, Faculté de Médecine, 06107 Nice Cedex 2, France
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29
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Hume AN, Collinson LM, Rapak A, Gomes AQ, Hopkins CR, Seabra MC. Rab27a regulates the peripheral distribution of melanosomes in melanocytes. J Cell Biol 2001; 152:795-808. [PMID: 11266470 PMCID: PMC2195786 DOI: 10.1083/jcb.152.4.795] [Citation(s) in RCA: 273] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2000] [Accepted: 11/22/2000] [Indexed: 12/11/2022] Open
Abstract
Rab GTPases are regulators of intracellular membrane traffic. We report a possible function of Rab27a, a protein implicated in several diseases, including Griscelli syndrome, choroideremia, and the Hermansky-Pudlak syndrome mouse model, gunmetal. We studied endogenous Rab27a and overexpressed enhanced GFP-Rab27a fusion protein in several cultured melanocyte and melanoma-derived cell lines. In pigmented cells, we observed that Rab27a decorates melanosomes, whereas in nonpigmented cells Rab27a colocalizes with melanosome-resident proteins. When dominant interfering Rab27a mutants were expressed in pigmented cells, we observed a redistribution of pigment granules with perinuclear clustering. This phenotype is similar to that observed by others in melanocytes derived from the ashen and dilute mutant mice, which bear mutations in the Rab27a and MyoVa loci, respectively. We also found that myosinVa coimmunoprecipitates with Rab27a in extracts from melanocytes and that both Rab27a and myosinVa colocalize on the cytoplasmic face of peripheral melanosomes in wild-type melanocytes. However, the amount of myosinVa in melanosomes from Rab27a-deficient ashen melanocytes is greatly reduced. These results, together with recent data implicating myosinVa in the peripheral capture of melanosomes, suggest that Rab27a is necessary for the recruitment of myosinVa, so allowing the peripheral retention of melanosomes in melanocytes.
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Affiliation(s)
- Alistair N. Hume
- Cell and Molecular Biology Section, Division of Biomedical Sciences
| | - Lucy M. Collinson
- Department of Biochemistry, Imperial College of Science, Technology and Medicine, London SW7 2AZ, United Kingdom
| | - Andrzej Rapak
- Cell and Molecular Biology Section, Division of Biomedical Sciences
| | - Anita Q. Gomes
- Cell and Molecular Biology Section, Division of Biomedical Sciences
| | - Colin R. Hopkins
- Department of Biochemistry, Imperial College of Science, Technology and Medicine, London SW7 2AZ, United Kingdom
| | - Miguel C. Seabra
- Cell and Molecular Biology Section, Division of Biomedical Sciences
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30
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Ramalho JS, Tolmachova T, Hume AN, McGuigan A, Gregory-Evans CY, Huxley C, Seabra MC. Chromosomal mapping, gene structure and characterization of the human and murine RAB27B gene. BMC Genet 2001; 2:2. [PMID: 11178108 PMCID: PMC29082 DOI: 10.1186/1471-2156-2-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2000] [Accepted: 02/02/2001] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Rab GTPases are regulators of intracellular membrane traffic. The Rab27 subfamily consists of Rab27a and Rab27b. Rab27a has been recently implicated in Griscelli Disease, a disease combining partial albinism with severe immunodeficiency. Rab27a plays a key role in the function of lysosomal-like organelles such as melanosomes in melanocytes and lytic granules in cytotoxic T lymphocytes. Little is known about Rab27b. RESULTS The human RAB27B gene is organised in six exons, spanning about 69 kb in the chromosome 18q21.1 region. Exon 1 is non-coding and is separated from the others by 49 kb of DNA and exon 6 contains a long 3' untranslated sequence (6.4 kb). The mouse Rab27b cDNA shows 95% identity with the human cDNA at the protein level and maps to mouse chromosome 18. The mouse mRNA was detected in stomach, large intestine, spleen and eye by RT-PCR, and in heart, brain, spleen and kidney by Northern blot. Transient over-expression of EGF-Rab27b fusion protein in cultured melanocytes revealed that Rab27b is associated with melanosomes, as observed for EGF-Rab27a. CONCLUSIONS Our results indicate that the Rab27 subfamily of Ras-like GTPases is highly conserved in mammals. There is high degree of conservation in sequence and gene structure between RAB27A and RAB27B genes. Exogenous expression of Rab27b in melanocytes results in melanosomal association as observed for Rab27a, suggesting the two Rab27 proteins are functional homologues. As with RAB27A in Griscelli Disease, RAB27B may be also associated with human disease mapping to chromosome 18.
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Affiliation(s)
- José S Ramalho
- Cell and Molecular Biology, Division of Biomedical Sciences, Imperial College School of Medicine, Sir Alexander Fleming Building, London SW7 2AZ, UK
| | - Tanya Tolmachova
- Cell and Molecular Biology, Division of Biomedical Sciences, Imperial College School of Medicine, Sir Alexander Fleming Building, London SW7 2AZ, UK
| | - Alistair N Hume
- Cell and Molecular Biology, Division of Biomedical Sciences, Imperial College School of Medicine, Sir Alexander Fleming Building, London SW7 2AZ, UK
| | - Amanda McGuigan
- Cell and Molecular Biology, Division of Biomedical Sciences, Imperial College School of Medicine, Sir Alexander Fleming Building, London SW7 2AZ, UK
| | - Cheryl Y Gregory-Evans
- Cell and Molecular Biology, Division of Biomedical Sciences, Imperial College School of Medicine, Sir Alexander Fleming Building, London SW7 2AZ, UK
| | - Clare Huxley
- Cell and Molecular Biology, Division of Biomedical Sciences, Imperial College School of Medicine, Sir Alexander Fleming Building, London SW7 2AZ, UK
| | - Miguel C Seabra
- Cell and Molecular Biology, Division of Biomedical Sciences, Imperial College School of Medicine, Sir Alexander Fleming Building, London SW7 2AZ, UK
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31
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Abstract
As sequencing of the human genome nears completion, the genes that cause many human diseases are being identified and functionally described. This has revealed that many human diseases are due to defects of intracellular trafficking. This 'Toolbox' catalogs and briefly describes these diseases.
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Affiliation(s)
- M Aridor
- Department of Cell Biology and Physiology, University of Pittsburgh, School of Medicine, 3500 Terrace St, Pittsburgh, PA 15261, USA
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32
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Adachi R, Nigam R, Tuvim MJ, DeMayo F, Dickey BF. Genomic organization, chromosomal localization, and expression of the murine RAB3D gene. Biochem Biophys Res Commun 2000; 273:877-83. [PMID: 10891340 DOI: 10.1006/bbrc.2000.3032] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Rab proteins, members of the Ras superfamily of small GTPases, play regulatory roles in intercompartmental vesicular transport. Each step of traffic seems to require the participation of at least one distinct Rab, with the Rab3 subfamily involved in stimulated exocytosis. We report our studies on the murine rab3D gene, one of the four mammalian Rab3 isoforms. We located this gene on chromosome 13, region A(2-3). The rab3D gene consists of 5 exons spanning 10.6 kb, and the structural gene is contained in exons 2 through 5 with one canonical GTP-binding motif in each exon. Organization of the rab3D gene is identical to that of rab3A but different from other rab genes. Alternative poly-A(+) signals in the 3' untranslated region account for the identities of multiple transcripts detected by Northern blot analysis. Rab3D is expressed in all tissues studied, predominantly in heart, lung, and liver, and binding sites for multiple transcription factors are found in the TATA-less promoter region.
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Affiliation(s)
- R Adachi
- Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA.
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33
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Wilson SM, Yip R, Swing DA, O'Sullivan TN, Zhang Y, Novak EK, Swank RT, Russell LB, Copeland NG, Jenkins NA. A mutation in Rab27a causes the vesicle transport defects observed in ashen mice. Proc Natl Acad Sci U S A 2000; 97:7933-8. [PMID: 10859366 PMCID: PMC16648 DOI: 10.1073/pnas.140212797] [Citation(s) in RCA: 336] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The dilute (d), leaden (ln), and ashen (ash) mutations provide a unique model system for studying vesicle transport in mammals. All three mutations produce a lightened coat color because of defects in pigment granule transport. In addition, all three mutations are suppressed by the semidominant dilute-suppressor (dsu), providing genetic evidence that these mutations function in the same or overlapping transport pathways. Previous studies showed that d encodes a major vesicle transport motor, myosin-VA, which is mutated in Griscelli syndrome patients. Here, using positional cloning and bacterial artificial chromosome rescue, we show that ash encodes Rab27a. Rab GTPases represent the largest branch of the p21 Ras superfamily and are recognized as key players in vesicular transport and organelle dynamics in eukaryotic cells. We also show that ash mice have platelet defects resulting in increased bleeding times and a reduction in the number of platelet dense granules. These defects have not been reported for d and ln mice. Collectively, our studies identify Rab27a as a critical gene for organelle-specific protein trafficking in melanocytes and platelets and suggest that Rab27a functions in both MyoVa dependent and independent pathways.
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Affiliation(s)
- S M Wilson
- Mouse Cancer Genetics Program, National Cancer Institute-Frederick Cancer Research and Development Center, Frederick, MD 21702, USA
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34
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Ménasché G, Pastural E, Feldmann J, Certain S, Ersoy F, Dupuis S, Wulffraat N, Bianchi D, Fischer A, Le Deist F, de Saint Basile G. Mutations in RAB27A cause Griscelli syndrome associated with haemophagocytic syndrome. Nat Genet 2000; 25:173-6. [PMID: 10835631 DOI: 10.1038/76024] [Citation(s) in RCA: 698] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Griscelli syndrome (GS, MIM 214450), a rare, autosomal recessive disorder, results in pigmentary dilution of the skin and the hair, the presence of large clumps of pigment in hair shafts and an accumulation of melanosomes in melanocytes. Most patients also develop an uncontrolled T-lymphocyte and macrophage activation syndrome (known as haemophagocytic syndrome, HS), leading to death in the absence of bone-marrow transplantation. In contrast, early in life some GS patients show a severe neurological impairment without apparent immune abnormalities. We previously mapped the GS locus to chromosome 15q21 and found a mutation in a gene (MYO5A) encoding a molecular motor in two patients. Further linkage analysis suggested a second gene associated with GS was in the same chromosomal region. Homozygosity mapping in additional families narrowed the candidate region to a 3.1-cM interval between D15S1003 and D15S962. We detected mutations in RAB27A, which lies within this interval, in 16 patients with GS. Unlike MYO5A, the GTP-binding protein RAB27A appears to be involved in the control of the immune system, as all patients with RAB27A mutations, but none with the MYO5A mutation, developed HS. In addition, RAB27A-deficient T cells exhibited reduced cytotoxicity and cytolytic granule exocytosis, whereas MYO5A-defective T cells did not. RAB27A appears to be a key effector of cytotoxic granule exocytosis, a pathway essential for immune homeostasis.
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Affiliation(s)
- G Ménasché
- [1] Unité de Recherches sur le Dévelopment Normal et Pathologique du Système Immunitaire INSERM U429, Paris, France
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