1
|
Ueda R, Hashimoto R, Fujii Y, Menezes JCJMDS, Takahashi H, Takeda H, Sawasaki T, Motokawa T, Tokunaga K, Fujita H. Membrane-Associated Ubiquitin Ligase RING Finger Protein 152 Orchestrates Melanogenesis via Tyrosinase Ubiquitination. MEMBRANES 2024; 14:43. [PMID: 38392670 PMCID: PMC10890620 DOI: 10.3390/membranes14020043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 01/24/2024] [Accepted: 01/27/2024] [Indexed: 02/24/2024]
Abstract
Lysosomal degradation of tyrosinase, a pivotal enzyme in melanin synthesis, negatively impacts melanogenesis in melanocytes. Nevertheless, the precise molecular mechanisms by which lysosomes target tyrosinase have remained elusive. Here, we identify RING (Really Interesting New Gene) finger protein 152 (RNF152) as a membrane-associated ubiquitin ligase specifically targeting tyrosinase for the first time, utilizing AlphaScreen technology. We observed that modulating RNF152 levels in B16 cells, either via overexpression or siRNA knockdown, resulted in decreased or increased levels of both tyrosinase and melanin, respectively. Notably, RNF152 and tyrosinase co-localized at the trans-Golgi network (TGN). However, upon treatment with lysosomal inhibitors, both proteins appeared in the lysosomes, indicating that tyrosinase undergoes RNF152-mediated lysosomal degradation. Through ubiquitination assays, we found the indispensable roles of both the RING and transmembrane (TM) domains of RNF152 in facilitating tyrosinase ubiquitination. In summary, our findings underscore RNF152 as a tyrosinase-specific ubiquitin ligase essential for regulating melanogenesis in melanocytes.
Collapse
Affiliation(s)
- Ryota Ueda
- Faculty of Pharmaceutical Sciences, Nagasaki International University, Sasebo 859-3298, Japan
| | - Rina Hashimoto
- Faculty of Pharmaceutical Sciences, Nagasaki International University, Sasebo 859-3298, Japan
| | - Yuki Fujii
- Faculty of Pharmaceutical Sciences, Nagasaki International University, Sasebo 859-3298, Japan
| | - José C J M D S Menezes
- Faculty of Pharmaceutical Sciences, Nagasaki International University, Sasebo 859-3298, Japan
- Esteem Industries Pvt Ltd., Bicholim 403529, Goa, India
| | | | - Hiroyuki Takeda
- Proteo-Science Center, Ehime University, Matsuyama 790-8577, Japan
| | - Tatsuya Sawasaki
- Proteo-Science Center, Ehime University, Matsuyama 790-8577, Japan
| | - Tomonori Motokawa
- Frontier Research Center, POLA Chemical Industries, Inc., Yokohama 244-0812, Japan
| | - Kenzo Tokunaga
- Department of Pathology, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Hideaki Fujita
- Faculty of Pharmaceutical Sciences, Nagasaki International University, Sasebo 859-3298, Japan
| |
Collapse
|
2
|
Sirés-Campos J, Lambertos A, Delevoye C, Raposo G, Bennett DC, Sviderskaya E, Jiménez-Cervantes C, Olivares C, García-Borrón JC. Mahogunin Ring Finger 1 regulates pigmentation by controlling the pH of melanosomes in melanocytes and melanoma cells. Cell Mol Life Sci 2021; 79:47. [PMID: 34921635 PMCID: PMC8738503 DOI: 10.1007/s00018-021-04053-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 11/18/2021] [Accepted: 11/19/2021] [Indexed: 12/29/2022]
Abstract
Mahogunin Ring Finger 1 (MGRN1) is an E3-ubiquitin ligase absent in dark-furred mahoganoid mice. We investigated the mechanisms of hyperpigmentation in Mgrn1-null melan-md1 melanocytes, Mgrn1-KO cells obtained by CRISPR-Cas9-mediated knockdown of Mgrn1 in melan-a6 melanocytes, and melan-a6 cells depleted of MGRN1 by siRNA treatment. Mgrn1-deficient melanocytes showed higher melanin content associated with increased melanosome abundance and higher fraction of melanosomes in highly melanized maturation stages III-IV. Expression, post-translational processing and enzymatic activity of the rate-limiting melanogenic enzyme tyrosinase measured in cell-free extracts were comparable in control and MGRN1-depleted cells. However, tyrosinase activity measured in situ in live cells and expression of genes associated with regulation of pH increased upon MGRN1 repression. Using pH-sensitive fluorescent probes, we found that downregulation of MGRN1 expression in melanocytes and melanoma cells increased the pH of acidic organelles, including melanosomes, strongly suggesting a previously unknown role of MGRN1 in the regulation of melanosomal pH. Among the pH regulatory genes upregulated by Mgrn1 knockdown, we identified those encoding several subunits of the vacuolar adenosine triphosphatase V-ATPase (mostly Atp6v0d2) and a calcium channel of the transient receptor potential channel family, Mucolipin 3 (Mcoln3). Manipulation of expression of the Mcoln3 gene showed that overexpression of Mcoln3 played a significant role in neutralization of the pH of acidic organelles and activation of tyrosinase in MGRN1-depleted cells. Therefore, lack of MGRN1 led to cell-autonomous stimulation of pigment production in melanocytes mostly by increasing tyrosinase specific activity through neutralization of the melanosomal pH in a MCOLN3-dependent manner.
Collapse
Affiliation(s)
- Julia Sirés-Campos
- University of Murcia, Murcia, Spain.,Institut Curie, UMR144, Structure and Membrane Compartments, PSL Research University, CNRS, 75005, Paris, France
| | | | - Cédric Delevoye
- Institut Curie, UMR144, Structure and Membrane Compartments, PSL Research University, CNRS, 75005, Paris, France.,Institut Curie, UMR144, Cell and Tissue Imaging Facility (PICT-IBiSA), PSL Research University, CNRS, 75005, Paris, France
| | - Graça Raposo
- Institut Curie, UMR144, Structure and Membrane Compartments, PSL Research University, CNRS, 75005, Paris, France.,Institut Curie, UMR144, Cell and Tissue Imaging Facility (PICT-IBiSA), PSL Research University, CNRS, 75005, Paris, France
| | - Dorothy C Bennett
- Molecular and Clinical Sciences Research Institute, St. George's, University of London, London, SW17 0RE, UK
| | - Elena Sviderskaya
- Molecular and Clinical Sciences Research Institute, St. George's, University of London, London, SW17 0RE, UK
| | | | | | | |
Collapse
|
3
|
Bowman SL, Bi-Karchin J, Le L, Marks MS. The road to lysosome-related organelles: Insights from Hermansky-Pudlak syndrome and other rare diseases. Traffic 2020; 20:404-435. [PMID: 30945407 DOI: 10.1111/tra.12646] [Citation(s) in RCA: 120] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 04/02/2019] [Accepted: 04/02/2019] [Indexed: 12/11/2022]
Abstract
Lysosome-related organelles (LROs) comprise a diverse group of cell type-specific, membrane-bound subcellular organelles that derive at least in part from the endolysosomal system but that have unique contents, morphologies and functions to support specific physiological roles. They include: melanosomes that provide pigment to our eyes and skin; alpha and dense granules in platelets, and lytic granules in cytotoxic T cells and natural killer cells, which release effectors to regulate hemostasis and immunity; and distinct classes of lamellar bodies in lung epithelial cells and keratinocytes that support lung plasticity and skin lubrication. The formation, maturation and/or secretion of subsets of LROs are dysfunctional or entirely absent in a number of hereditary syndromic disorders, including in particular the Hermansky-Pudlak syndromes. This review provides a comprehensive overview of LROs in humans and model organisms and presents our current understanding of how the products of genes that are defective in heritable diseases impact their formation, motility and ultimate secretion.
Collapse
Affiliation(s)
- Shanna L Bowman
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania.,Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jing Bi-Karchin
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania.,Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Linh Le
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania.,Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.,Cell and Molecular Biology Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Michael S Marks
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania.,Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| |
Collapse
|
4
|
Bajaj L, Lotfi P, Pal R, di Ronza A, Sharma J, Sardiello M. Lysosome biogenesis in health and disease. J Neurochem 2019; 148:573-589. [PMID: 30092616 PMCID: PMC6368902 DOI: 10.1111/jnc.14564] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 08/01/2018] [Accepted: 08/03/2018] [Indexed: 01/01/2023]
Abstract
This review focuses on the pathways that regulate lysosome biogenesis and that are implicated in numerous degenerative storage diseases, including lysosomal storage disorders and late-onset neurodegenerative diseases. Lysosomal proteins are synthesized in the endoplasmic reticulum and trafficked to the endolysosomal system through the secretory route. Several receptors have been characterized that execute post-Golgi trafficking of lysosomal proteins. Some of them recognize their cargo proteins based on specific amino acid signatures, others based on a particular glycan modification that is exclusively found on lysosomal proteins. Nearly all receptors serving lysosome biogenesis are under the transcriptional control of transcription factor EB (TFEB), a master regulator of the lysosomal system. TFEB coordinates the expression of lysosomal hydrolases, lysosomal membrane proteins, and autophagy proteins in response to pathways sensing lysosomal stress and the nutritional conditions of the cell among other stimuli. TFEB is primed for activation in lysosomal storage disorders but surprisingly its function is impaired in some late-onset neurodegenerative storage diseases like Alzheimer's and Parkinson's, because of specific detrimental interactions that limit TFEB expression or activation. Thus, disrupted TFEB function presumably plays a role in the pathogenesis of these diseases. Multiple studies in animal models of degenerative storage diseases have shown that exogenous expression of TFEB and pharmacological activation of endogenous TFEB attenuate disease phenotypes. These results highlight TFEB-mediated enhancement of lysosomal biogenesis and function as a candidate strategy to counteract the progression of these diseases. This article is part of the Special Issue "Lysosomal Storage Disorders".
Collapse
Affiliation(s)
- Lakshya Bajaj
- Department of Molecular and Human Genetics, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX 77030 USA
| | - Parisa Lotfi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX 77030 USA
| | - Rituraj Pal
- Department of Molecular and Human Genetics, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX 77030 USA
| | - Alberto di Ronza
- Department of Molecular and Human Genetics, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX 77030 USA
| | - Jaiprakash Sharma
- Department of Molecular and Human Genetics, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX 77030 USA
| | - Marco Sardiello
- Department of Molecular and Human Genetics, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX 77030 USA
| |
Collapse
|
5
|
Solano F. On the Metal Cofactor in the Tyrosinase Family. Int J Mol Sci 2018; 19:ijms19020633. [PMID: 29473882 PMCID: PMC5855855 DOI: 10.3390/ijms19020633] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 02/13/2018] [Accepted: 02/13/2018] [Indexed: 12/16/2022] Open
Abstract
The production of pigment in mammalian melanocytes requires the contribution of at least three melanogenic enzymes, tyrosinase and two other accessory enzymes called the tyrosinase-related proteins (Trp1 and Trp2), which regulate the type and amount of melanin. The last two proteins are paralogues to tyrosinase, and they appeared late in evolution by triplication of the tyrosinase gene. Tyrosinase is a copper-enzyme, and Trp2 is a zinc-enzyme. Trp1 has been more elusive, and the direct identification of its metal cofactor has never been achieved. However, due to its enzymatic activity and similarities with tyrosinase, it has been assumed as a copper-enzyme. Recently, recombinant human tyrosinase and Trp1 have been expressed in enough amounts to achieve for the first time their crystallization. Unexpectedly, it has been found that Trp1 contains a couple of Zn(II) at the active site. This review discusses data about the metal cofactor of tyrosinase and Trps. It points out differences in the studied models, and it proposes some possible points accounting for the apparent discrepancies currently appearing. Moreover, some proposals about the possible flexibility of the tyrosinase family to uptake copper or zinc are discussed.
Collapse
Affiliation(s)
- Francisco Solano
- Department Biochemistry and Molecular Biology B and Immunology, School of Medicine and LAIB-IMIB, University of Murcia, 30100 Murcia, Spain.
| |
Collapse
|
6
|
Patwardhan A, Bardin S, Miserey-Lenkei S, Larue L, Goud B, Raposo G, Delevoye C. Routing of the RAB6 secretory pathway towards the lysosome related organelle of melanocytes. Nat Commun 2017; 8:15835. [PMID: 28607494 PMCID: PMC5474736 DOI: 10.1038/ncomms15835] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 04/28/2017] [Indexed: 12/23/2022] Open
Abstract
Exocytic carriers convey neo-synthesized components from the Golgi apparatus to the cell surface. While the release and anterograde movement of Golgi-derived vesicles require the small GTPase RAB6, its effector ELKS promotes the targeting and docking of secretory vesicles to particular areas of the plasma membrane. Here, we show that specialized cell types exploit and divert the secretory pathway towards lysosome related organelles. In cultured melanocytes, the secretory route relies on RAB6 and ELKS to directly transport and dock Golgi-derived carriers to melanosomes. By delivering specific cargos, such as MART-1 and TYRP2/ DCT, the RAB6/ELKS-dependent secretory pathway controls the formation and maturation of melanosomes but also pigment synthesis. In addition, pigmentation defects are observed in RAB6 KO mice. Our data together reveal for the first time that the secretory pathway can be directed towards intracellular organelles of endosomal origin to ensure their biogenesis and function. The anterograde movement of Golgi-derived vesicles requires the small GTPase RAB6, while its effector ELKS targets these vesicles to particular areas of the plasma membrane. Here the authors show that RAB6 and ELKS function in the biogenesis of melanosome, demonstrating that the secretory pathway can be directed towards intracellular organelles of endosomal origin.
Collapse
Affiliation(s)
- Anand Patwardhan
- Institut Curie, PSL Research University, CNRS, UMR 144, Structure and Membrane Compartments, Paris F-75005, France
| | - Sabine Bardin
- Institut Curie, PSL Research University, CNRS, UMR 144, Molecular Mechanisms of Intracellular Transport, Paris F-75005, France
| | - Stéphanie Miserey-Lenkei
- Institut Curie, PSL Research University, CNRS, UMR 144, Molecular Mechanisms of Intracellular Transport, Paris F-75005, France
| | - Lionel Larue
- Institut Curie, PSL Research University, INSERM U1021, Normal and Pathological Development of Melanocytes, Orsay 91405, France.,Université Paris-Sud, Université Paris-Saclay, CNRS UMR 3347, Orsay 91405, France.,Equipe Labellisée Ligue Contre le Cancer, Orsay 91405, France
| | - Bruno Goud
- Institut Curie, PSL Research University, CNRS, UMR 144, Molecular Mechanisms of Intracellular Transport, Paris F-75005, France
| | - Graça Raposo
- Institut Curie, PSL Research University, CNRS, UMR 144, Structure and Membrane Compartments, Paris F-75005, France.,Institut Curie, PSL Research University, CNRS, UMR144, Cell and Tissue Imaging Facility (PICT-IBiSA), Paris F-75005, France
| | - Cédric Delevoye
- Institut Curie, PSL Research University, CNRS, UMR 144, Structure and Membrane Compartments, Paris F-75005, France.,Institut Curie, PSL Research University, CNRS, UMR144, Cell and Tissue Imaging Facility (PICT-IBiSA), Paris F-75005, France
| |
Collapse
|
7
|
De Filippo E, Schiedel AC, Manga P. Interaction between G Protein-Coupled Receptor 143 and Tyrosinase: Implications for Understanding Ocular Albinism Type 1. J Invest Dermatol 2016; 137:457-465. [PMID: 27720922 DOI: 10.1016/j.jid.2016.09.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 09/26/2016] [Accepted: 09/27/2016] [Indexed: 12/31/2022]
Abstract
Developmental eye defects in X-linked ocular albinism type 1 are caused by G-protein coupled receptor 143 (GPR143) mutations. Mutations result in dysfunctional melanosome biogenesis and macromelanosome formation in pigment cells, including melanocytes and retinal pigment epithelium. GPR143, primarily expressed in pigment cells, localizes exclusively to endolysosomal and melanosomal membranes unlike most G protein-coupled receptors, which localize to the plasma membrane. There is some debate regarding GPR143 function and elucidating the role of this receptor may be instrumental for understanding neurogenesis during eye development and for devising therapies for ocular albinism type I. Many G protein-coupled receptors require association with other proteins to function. These G protein-coupled receptor-interacting proteins also facilitate fine-tuning of receptor activity and tissue specificity. We therefore investigated potential GPR143 interaction partners, with a focus on the melanogenic enzyme tyrosinase. GPR143 coimmunoprecipitated with tyrosinase, while confocal microscopy demonstrated colocalization of the proteins. Furthermore, tyrosinase localized to the plasma membrane when coexpressed with a GPR143 trafficking mutant. The physical interaction between the proteins was confirmed using fluorescence resonance energy transfer. This interaction may be required in order for GPR143 to function as a monitor of melanosome maturation. Identifying tyrosinase as a potential GPR143 binding protein opens new avenues for investigating the mechanisms that regulate pigmentation and neurogenesis.
Collapse
Affiliation(s)
| | - Anke C Schiedel
- Pharmaceutical Chemistry I, PharmaCenter Bonn, University of Bonn, Bonn, Germany.
| | - Prashiela Manga
- Ronald O. Perelman, Department of Dermatology, New York University School of Medicine, New York, New York, USA.
| |
Collapse
|
8
|
Tyrosinase Depletion Prevents the Maturation of Melanosomes in the Mouse Hair Follicle. PLoS One 2015; 10:e0143702. [PMID: 26619124 PMCID: PMC4664286 DOI: 10.1371/journal.pone.0143702] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 11/08/2015] [Indexed: 01/21/2023] Open
Abstract
The mechanisms that lead to variation in human skin and hair color are not fully understood. To better understand the molecular control of skin and hair color variation, we modulated the expression of Tyrosinase (Tyr), which controls the rate-limiting step of melanogenesis, by expressing a single-copy, tetracycline-inducible shRNA against Tyr in mice. Moderate depletion of TYR was sufficient to alter the appearance of the mouse coat in black, agouti, and yellow coat color backgrounds, even though TYR depletion did not significantly inhibit accumulation of melanin within the mouse hair. Ultra-structural studies revealed that the reduction of Tyr inhibited the accumulation of terminal melanosomes, and inhibited the expression of genes that regulate melanogenesis. These results indicate that color in skin and hair is determined not only by the total amount of melanin within the hair, but also by the relative accumulation of mature melanosomes.
Collapse
|
9
|
Fogal S, Carotti M, Giaretta L, Lanciai F, Nogara L, Bubacco L, Bergantino E. Human tyrosinase produced in insect cells: a landmark for the screening of new drugs addressing its activity. Mol Biotechnol 2015; 57:45-57. [PMID: 25189462 DOI: 10.1007/s12033-014-9800-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Human tyrosinase is the first enzyme of the multistep process of melanogenesis. It catalyzes the hydroxylation of L-tyrosine to L-dihydroxyphenylalanine and the following oxidation of o-diphenol to the corresponding quinone, L-dopaquinone. In spite of its biomedical relevance, its reactivity is far from being fully understood, mostly because of the lack of a suitable expression system. Indeed, until now, studies on substrates and inhibitors of tyrosinases have been performed in vitro almost exclusively using mushroom or bacterial enzymes. We report on the production of a recombinant human tyrosinase in insect cells (Sf9 line). Engineering the protein, improving cell culture conditions, and setting a suitable purification protocol optimized product yield. The obtained active enzyme was truthfully characterized with a number of substrate and inhibitor molecules. These results were compared to those gained from a parallel analysis of the bacterial (Streptomyces antibioticus) enzyme and those acquired from the literature for mushroom tyrosinase, showing that the reactivity of the human enzyme appears unique and pointing out the great bias introduced when using non-human tyrosinases to measure the inhibitory efficacy of new molecules. The described enzyme is therefore an indispensable paradigm in testing pharmaceutical or cosmetic agents addressing tyrosinase activity.
Collapse
Affiliation(s)
- Stefano Fogal
- Department of Biology, University of Padua, Viale G. Colombo 3, 35121, Padua, Italy
| | | | | | | | | | | | | |
Collapse
|
10
|
ZOU JUNRONG, GUO PEI, LV NONGHUA, HUANG DEQIANG. Lipopolysaccharide-induced tumor necrosis factor-α factor enhances inflammation and is associated with cancer (Review). Mol Med Rep 2015; 12:6399-404. [DOI: 10.3892/mmr.2015.4243] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2014] [Accepted: 06/03/2015] [Indexed: 11/06/2022] Open
|
11
|
Burgoyne T, Jolly R, Martin-Martin B, Seabra MC, Piccirillo R, Schiaffino MV, Futter CE. Expression of OA1 limits the fusion of a subset of MVBs with lysosomes - a mechanism potentially involved in the initial biogenesis of melanosomes. J Cell Sci 2013; 126:5143-52. [PMID: 24006264 PMCID: PMC3828590 DOI: 10.1242/jcs.128561] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Multivesicular endosomes/bodies (MVBs) deliver proteins, such as activated EGF receptor (EGFR), to the lysosome for degradation, and, in pigmented cells, MVBs containing PMEL are an initial stage in melanosome biogenesis. The mechanisms regulating numbers and fate of different populations of MVB are unclear. Here, we focus on the role of the G-protein-coupled receptor OA1 (also known as GPR143), which is expressed exclusively in pigmented cells and mutations in which cause the most common type of ocular albinism. When exogenously expressing PMEL, HeLa cells have been shown to form MVBs resembling early stage melanosomes. To focus on the role of OA1 in the initial stages of melanosome biogenesis we take advantage of the absence of the later stages of melanosome maturation in HeLa cells to determine whether OA1 activity can regulate MVB number and fate. Expression of wild-type but not OA1 mutants carrying inactivating mutations or deletions causes MVB numbers to increase. Whereas OA1 expression has no effect on delivery of EGFR-containing MVBs to the lysosome, it inhibits the lysosomal delivery of PMEL and PMEL-containing MVBs accumulate. We propose that OA1 activity delays delivery of PMEL-containing MVBs to the lysosome to allow time for melanin synthesis and commitment to melanosome biogenesis.
Collapse
Affiliation(s)
- Thomas Burgoyne
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | | | | | | | | | | | | |
Collapse
|
12
|
Eaton HE, Ferreira Lacerda A, Desrochers G, Metcalf J, Angers A, Brunetti CR. Cellular LITAF interacts with frog virus 3 75L protein and alters its subcellular localization. J Virol 2013; 87:716-23. [PMID: 23097445 PMCID: PMC3554103 DOI: 10.1128/jvi.01857-12] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 10/17/2012] [Indexed: 02/06/2023] Open
Abstract
Iridoviruses are a family of large double-stranded DNA (dsDNA) viruses that are composed of 5 genera, including the Lymphocystivirus, Ranavirus, Megalocytivirus, Iridovirus, and Chloriridovirus genera. The frog virus 3 (FV3) 75L gene is a nonessential gene that is highly conserved throughout the members of the Ranavirus genus but is not found in other iridoviruses. FV3 75L shows high sequence similarity to a conserved domain found in the C terminus of LITAF, a small cellular protein with unknown function. Here we show that FV3 75L localizes to early endosomes, while LITAF localizes to late endosomes/lysosomes. Interestingly, when FV3 75L and LITAF are cotransfected into cells, LITAF can alter the subcellular localization of FV3 75L to late endosomes/lysosomes, where FV3 75L then colocalizes with LITAF. In addition, we demonstrated that virally produced 75L colocalizes with LITAF. We confirmed a physical interaction between LITAF and FV3 75L but found that this interaction was not mediated by two PPXY motifs in the N terminus of LITAF. Mutation of two PPXY motifs in LITAF did not affect the colocalization of LITAF and FV3 75L but did change the location of the two proteins from late endosomes/lysosomes to early endosomes.
Collapse
Affiliation(s)
- Heather E. Eaton
- Department of Biology, Trent University, Peterborough, Ontario, Canada
| | | | - Guillaume Desrochers
- Département de Sciences Biologiques, Université de Montréal, Montréal, Québec, Canada
| | - Julie Metcalf
- Department of Biology, Trent University, Peterborough, Ontario, Canada
| | - Annie Angers
- Département de Sciences Biologiques, Université de Montréal, Montréal, Québec, Canada
| | - Craig R. Brunetti
- Department of Biology, Trent University, Peterborough, Ontario, Canada
| |
Collapse
|
13
|
Kadam RS, Scheinman RI, Kompella UB. Pigmented-MDCK (P-MDCK) cell line with tunable melanin expression: an in vitro model for the outer blood-retinal barrier. Mol Pharm 2012; 9:3228-35. [PMID: 23003570 DOI: 10.1021/mp300305f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Retinal pigment epithelium, which forms the outer blood-retinal barrier, is a critical barrier for transport of drugs to the retina. The purpose of this study was to develop a pigmented MDCK (P-MDCK) cell line as a rapidly established in vitro model for the outer blood-retinal barrier to assess the influence of melanin pigment on solute permeability. A melanin synthesizing P-MDCK cell line was developed by lentiviral transduction of human tyrosinase and p-protein genes in MDCK (NBL-2) cells. Melanin content, tyrosinase activity (conversion of L-dopa to dopachrome), and transepithelial electrical resistance (TEER) were measured. Expression of tyrosinase protein and p-protein in P-MDCK cells was confirmed by confocal microscopy. Effect of l-tyrosine (0 to 2 mM) in culture medium on melanin synthesis in P-MDCK cells was evaluated. Cell uptake and transepithelial transport of pigment-binding chloroquine (Log D = 1.59) and a negative control salicylic acid (Log D = -1.14) were investigated. P-MDCK cells expressed tyrosinase and p-protein. Tyrosinase activity was 4.5-fold higher in P-MDCK cells compared to wild type MDCK cells. The transepithelial electrical resistance stabilized by day 4 in both cell types, with the TEER being 958 ± 33 and 964 ± 58 Ω·cm(2) for P-MDCK and wild type cells, respectively. Melanin content in P-MDCK cells depended on the concentration of l-tyrosine in culture medium, and increased from 3 to 54 μg/mg protein with an increase in l-tyrosine content from 0 to 2 mM. When the cells were grown in 2 mM l-tyrosine, uptake of chloroquine was 2.3-fold higher and the transepithelial transport was 2.2-fold lower in P-MDCK cells when compared to wild type MDCK cells. No significant difference was observed for both cell uptake and transport of salicylic acid. We developed a P-MDCK cell line with tunable melanin synthesis as a rapidly developing surrogate for retinal pigment epithelium.
Collapse
Affiliation(s)
- Rajendra S Kadam
- Department of Pharmaceutical Sciences, University of Colorado, Anschutz Medical Campus, Aurora, Colorado 80045, United States
| | | | | |
Collapse
|
14
|
Sitaram A, Marks MS. Mechanisms of protein delivery to melanosomes in pigment cells. Physiology (Bethesda) 2012; 27:85-99. [PMID: 22505665 DOI: 10.1152/physiol.00043.2011] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Vertebrate pigment cells in the eye and skin are useful models for cell types that use specialized endosomal trafficking pathways to partition cargo proteins to unique lysosome-related organelles such as melanosomes. This review describes current models of protein trafficking required for melanosome biogenesis in mammalian melanocytes.
Collapse
Affiliation(s)
- Anand Sitaram
- Cell and Molecular Biology Graduate Group, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | |
Collapse
|
15
|
Sitaram A, Dennis MK, Chaudhuri R, De Jesus-Rojas W, Tenza D, Setty SRG, Wood CS, Sviderskaya EV, Bennett DC, Raposo G, Bonifacino JS, Marks MS. Differential recognition of a dileucine-based sorting signal by AP-1 and AP-3 reveals a requirement for both BLOC-1 and AP-3 in delivery of OCA2 to melanosomes. Mol Biol Cell 2012; 23:3178-92. [PMID: 22718909 PMCID: PMC3418312 DOI: 10.1091/mbc.e11-06-0509] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
OCA2 is used as a model melanosome cargo protein to define primary sequence elements required for acidic dileucine–motif binding to adaptors AP-1 and AP-3. OCA2 must bind to AP-3 for melanosome localization. BLOC-1 is also required and thus can cooperate with either adaptor for cargo delivery to lysosome-related organelles. Cell types that generate unique lysosome-related organelles (LROs), such as melanosomes in melanocytes, populate nascent LROs with cargoes that are diverted from endosomes. Cargo sorting toward melanosomes correlates with binding via cytoplasmically exposed sorting signals to either heterotetrameric adaptor AP-1 or AP-3. Some cargoes bind both adaptors, but the relative contribution of each adaptor to cargo recognition and their functional interactions with other effectors during transport to melanosomes are not clear. Here we exploit targeted mutagenesis of the acidic dileucine–based sorting signal in the pigment cell–specific protein OCA2 to dissect the relative roles of AP-1 and AP-3 in transport to melanosomes. We show that binding to AP-1 or AP-3 depends on the primary sequence of the signal and not its position within the cytoplasmic domain. Mutants that preferentially bound either AP-1 or AP-3 each trafficked toward melanosomes and functionally complemented OCA2 deficiency, but AP-3 binding was necessary for steady-state melanosome localization. Unlike tyrosinase, which also engages AP-3 for optimal melanosomal delivery, both AP-1– and AP-3–favoring OCA2 variants required BLOC-1 for melanosomal transport. These data provide evidence for distinct roles of AP-1 and AP-3 in OCA2 transport to melanosomes and indicate that BLOC-1 can cooperate with either adaptor during cargo sorting to LROs.
Collapse
Affiliation(s)
- Anand Sitaram
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Eaton HE, Metcalf J, Lacerda AF, Brunetti CR. Accumulation of endogenous LITAF in aggresomes. PLoS One 2012; 7:e30003. [PMID: 22276139 PMCID: PMC3261850 DOI: 10.1371/journal.pone.0030003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Accepted: 12/08/2011] [Indexed: 11/18/2022] Open
Abstract
LITAF is a 161 amino acid cellular protein which includes a proline rich N-terminus and a conserved C-terminal domain known as the simple-like domain. Mutations in LITAF have been identified in Charcot-Marie tooth disease, a disease characterized by protein aggregates. Cells transfected with cellular LITAF reveal that LITAF is localized to late endosomes/lysosomes. Here we investigated the intracellular localization of endogenous LITAF. We demonstrated that endogenous LITAF accumulates at a discrete cytoplasmic site in BGMK cells that we identify as the aggresome. To determine the domain within LITAF that is responsible for the localization of LITAF to aggresomes, we created a construct that contained the C-terminal simple-like domain of LITAF and found that this construct also localizes to aggresomes. These data suggest the simple-like domain is responsible for targeting endogenous LITAF to the aggresome.
Collapse
Affiliation(s)
- Heather E Eaton
- Department of Biology, Trent University, Peterborough, Ontario, Canada
| | | | | | | |
Collapse
|
17
|
Fujita H, Hongo M, Mochizuki M, Yokoyama K, Tanaka Y. Inhibitory effects of 16-hydroxy-9-oxo-10E,12E,14E-octadecatrienoic acid (Corchorifatty acid B) isolated from Melissa officinalis Linné on melanogenesis. Exp Dermatol 2011; 20:420-4. [DOI: 10.1111/j.1600-0625.2010.01241.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
|
18
|
Mattera R, Boehm M, Chaudhuri R, Prabhu Y, Bonifacino JS. Conservation and diversification of dileucine signal recognition by adaptor protein (AP) complex variants. J Biol Chem 2011; 286:2022-30. [PMID: 21097499 PMCID: PMC3023499 DOI: 10.1074/jbc.m110.197178] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Indexed: 12/22/2022] Open
Abstract
The clathrin-associated, heterotetrameric adaptor protein (AP) complexes, AP-1, AP-2, and AP-3, recognize signals in the cytosolic domains of transmembrane proteins, leading to their sorting to endosomes, lysosomes, lysosome-related organelles, and/or the basolateral membrane of polarized epithelial cells. One type of signal, referred to as "dileucine-based," fits the consensus motif (D/E)XXXL(L/I). Previous biochemical analyses showed that (D/E)XXXL(L/I) signals bind to a combination of two subunits of each AP complex, namely the AP-1 γ-σ1, AP-2 α-σ2, and AP-3 δ-σ3 hemicomplexes, and structural studies revealed that an imperfect variant of this motif lacking the (D/E) residue binds to a site straddling the interface of α and σ2. Herein, we report mutational and binding analyses showing that canonical (D/E)XXXL(L/I) signals bind to this same site on AP-2, and to similar sites on AP-1 and AP-3. The strength and amino acid requirements of different interactions depend on the specific signals and AP complexes involved. We also demonstrate the occurrence of diverse AP-1 heterotetramers by combinatorial assembly of various γ and σ1 subunit isoforms encoded by different genes. These AP-1 variants bind (D/E)XXXL(L/I) signals with marked preferences for certain sequences, implying that they are not functionally equivalent. Our results thus demonstrate that different AP complexes share a conserved binding site for (D/E)XXXL(L/I) signals. However, the characteristics of the binding site on each complex vary, providing for the specific recognition of a diverse repertoire of (D/E)XXXL(L/I) signals.
Collapse
Affiliation(s)
- Rafael Mattera
- From the Cell Biology and Metabolism Program, NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Markus Boehm
- From the Cell Biology and Metabolism Program, NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Rittik Chaudhuri
- From the Cell Biology and Metabolism Program, NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Yogikala Prabhu
- From the Cell Biology and Metabolism Program, NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Juan S. Bonifacino
- From the Cell Biology and Metabolism Program, NICHD, National Institutes of Health, Bethesda, Maryland 20892
| |
Collapse
|
19
|
Hasegawa T. Tyrosinase-expressing neuronal cell line as in vitro model of Parkinson's disease. Int J Mol Sci 2010; 11:1082-9. [PMID: 20480001 PMCID: PMC2869230 DOI: 10.3390/ijms11031082] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Accepted: 03/03/2010] [Indexed: 11/24/2022] Open
Abstract
Oxidized metabolites of dopamine known as dopamine quinone derivatives are thought to play a pivotal role in the degeneration of nigrostriatal dopaminergic neurons in Parkinson’s disease. Although such quinone derivatives are usually produced via the autoxidation of catecholamines, tyrosinase, which is a key enzyme in melanin biosynthesis via the production of DOPA and subsequent molecules, can potentially accelerate the induction of catecholamine quinone derivatives by its oxidase activity. We have developed neuronal cell lines in which the expression of human tyrosinase was inducible. Overexpression of tyrosinase resulted in increased intracellular dopamine content in association with the formation of melanin pigments in neuronal somata, which eventually causes apoptotic cell death. This cellular model will provide a useful tool for detailed analyses of the neurotoxicity of oxidized catechol metabolites.
Collapse
Affiliation(s)
- Takafumi Hasegawa
- Department of Neurology Tohoku University School of Medicine, Aobaku, Sendai, Miyagi, Japan.
| |
Collapse
|
20
|
Fujita H, Motokawa T, Katagiri T, Yokota S, Yamamoto A, Himeno M, Tanaka Y. Inulavosin, a Melanogenesis Inhibitor, Leads to Mistargeting of Tyrosinase to Lysosomes and Accelerates its Degradation. J Invest Dermatol 2009; 129:1489-99. [DOI: 10.1038/jid.2008.376] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
|
21
|
Tomihari M, Hwang SH, Chung JS, Cruz PD, Ariizumi K. Gpnmb is a melanosome-associated glycoprotein that contributes to melanocyte/keratinocyte adhesion in a RGD-dependent fashion. Exp Dermatol 2009; 18:586-95. [PMID: 19320736 DOI: 10.1111/j.1600-0625.2008.00830.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Gpnmb is a glycosylated transmembrane protein implicated in the development of glaucoma in mice and melanoma in humans. It shares significant amino acid sequence homology with the melanosome protein Pmel-17. Its extracellular domain contains a RGD motif for binding to integrin and its intracellular domain has a putative endosomal and/or melanosomal-sorting motif. These features led us to posit that Gpnmb is associated with melanosomes and involved in cell adhesion. We showed that human Gpnmb is expressed constitutively by melanoma cell lines, primary-cultured melanocytes and epidermal melanocytes in situ, with most of it found intracellularly within melanosomes and to a lesser degree in lysosomes. Our newly developed monoclonal antibody revealed surface expression of Gpnmb on these pigment cells, albeit to a lesser degree than the intracellular fraction. Gpnmb expression was upregulated by UVA (but not UVB) irradiation and by alpha-melanocyte-stimulating hormone (MSH) (but not beta-MSH); its cell surface expression on melanocytes (but not on melanoma cells) was increased markedly by IFN-gamma and TNF-alpha. PAM212 keratinocytes adhered to immobilized Gpnmb in a RGD-dependent manner. These results indicate that Gpnmb is a melanosome-associated glycoprotein that contributes to the adhesion of melanocytes with keratinocytes.
Collapse
Affiliation(s)
- Mizuki Tomihari
- Department of Dermatology, The University of Texas Southwestern Medical Center and Dermatology Section (Medical Service), Dallas Veterans Affairs Medical Center, Dallas, TX 75390-9069, USA
| | | | | | | | | |
Collapse
|
22
|
Sitaram A, Piccirillo R, Palmisano I, Harper DC, Dell'Angelica EC, Schiaffino MV, Marks MS. Localization to mature melanosomes by virtue of cytoplasmic dileucine motifs is required for human OCA2 function. Mol Biol Cell 2008; 20:1464-77. [PMID: 19116314 DOI: 10.1091/mbc.e08-07-0710] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Oculocutaneous albinism type 2 is caused by defects in the gene OCA2, encoding a pigment cell-specific, 12-transmembrane domain protein with homology to ion permeases. The function of the OCA2 protein remains unknown, and its subcellular localization is under debate. Here, we show that endogenous OCA2 in melanocytic cells rapidly exits the endoplasmic reticulum (ER) and thus does not behave as a resident ER protein. Consistently, exogenously expressed OCA2 localizes within melanocytes to melanosomes, and, like other melanosomal proteins, localizes to lysosomes when expressed in nonpigment cells. Mutagenized OCA2 transgenes stimulate melanin synthesis in OCA2-deficient cells when localized to melanosomes but not when specifically retained in the ER, contradicting a proposed primary function for OCA2 in the ER. Steady-state melanosomal localization requires a conserved consensus acidic dileucine-based sorting motif within the cytoplasmic N-terminal region of OCA2. A second dileucine signal within this region confers steady-state lysosomal localization in melanocytes, suggesting that OCA2 might traverse multiple sequential or parallel trafficking routes. The two dileucine signals physically interact in a differential manner with cytoplasmic adaptors known to function in trafficking other proteins to melanosomes. We conclude that OCA2 is targeted to and functions within melanosomes but that residence within melanosomes may be regulated by secondary or alternative targeting to lysosomes.
Collapse
Affiliation(s)
- Anand Sitaram
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | | | | | | | | | | |
Collapse
|
23
|
Callahan JW, Bagshaw RD, Mahuran DJ. The integral membrane of lysosomes: its proteins and their roles in disease. J Proteomics 2008; 72:23-33. [PMID: 19068244 DOI: 10.1016/j.jprot.2008.11.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Revised: 10/30/2008] [Accepted: 11/11/2008] [Indexed: 12/18/2022]
Abstract
The protein composition of the integral lysosomal membrane and the membrane-associated compartment have been defined in part by proteomics approaches. While the role of its constituent hydrolases in a large array of human disorders has been well-documented, the manner in which membrane proteins are integrated into the organelle, the multiprotein complexes that form at the organelle's cytosolic surface and their roles in the biogenesis and functional control of the organelle are now emerging. Defining cytosolic targeting complexes that affect the function of the lysosomal/endosomal compartment may help to identify the lysosome's role in a variety of human pathologies.
Collapse
Affiliation(s)
- John W Callahan
- Research Institute, The Hospital for Sick Children, Toronto, Canada.
| | | | | |
Collapse
|
24
|
Tribl F, Arzberger T, Riederer P, Gerlach M. Tyrosinase is not detected in human catecholaminergic neurons by immunohistochemistry and Western blot analysis. JOURNAL OF NEURAL TRANSMISSION. SUPPLEMENTUM 2007:51-5. [PMID: 17982878 DOI: 10.1007/978-3-211-73574-9_8] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Catecholaminergic neurons of the primate substantia nigra (SN) pars compacta (SNc) and the locus coeruleus contain neuromelanin (NM) granules as characteristic structures underlying the pigmentation of these brain areas. Due to a phylogenetic appearance NM granules are absent in the rodent brain, but gradually become present in primates until they reach a maximal expression in humans. Although a possible mechanism of pigment formation may be autoxidation of the NM precursors dopamine or noradrenalin, several groups have suggested an enzymatic formation of NM mediated by tyrosinase or a related enzyme. Since tyrosinase mRNA is suggested to be expressed in the SN of mice and humans, we reinvestigated the expression of tyrosinase in the human SNc and the locus coeruleus at the protein level by immunohistochemistry and Western blot analysis, but could not detect tyrosinase in these brain regions.
Collapse
Affiliation(s)
- F Tribl
- Laboratory of Clinical Neurochemistry, Clinic and Policlinic for Psychiatry and Psychotherapy, Bayerische Julius-Maximilians-Universität Würzburg, Würzburg, Germany.
| | | | | | | |
Collapse
|
25
|
Raposo G, Marks MS. Melanosomes--dark organelles enlighten endosomal membrane transport. Nat Rev Mol Cell Biol 2007; 8:786-97. [PMID: 17878918 PMCID: PMC2786984 DOI: 10.1038/nrm2258] [Citation(s) in RCA: 382] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Melanosomes are tissue-specific lysosome-related organelles of pigment cells in which melanins are synthesized and stored. Analyses of the trafficking and fate of melanosomal components are beginning to reveal how melanosomes are formed through novel pathways from early endosomal intermediates. These studies unveil generalized structural and functional modifications of the endosomal system in specialized cells, and provide unexpected insights into the biogenesis of multivesicular bodies and how compartmentalization regulates protein refolding. Moreover, genetic disorders that affect the biogenesis of melanosomes and other lysosome-related organelles have shed light onto the molecular machinery that controls specialized endosomal sorting events.
Collapse
Affiliation(s)
- Graça Raposo
- Institut Curie, Centre de Recherche, Paris, F-75248 France.
| | | |
Collapse
|
26
|
Lopes VS, Wasmeier C, Seabra MC, Futter CE. Melanosome maturation defect in Rab38-deficient retinal pigment epithelium results in instability of immature melanosomes during transient melanogenesis. Mol Biol Cell 2007; 18:3914-27. [PMID: 17671165 PMCID: PMC1995718 DOI: 10.1091/mbc.e07-03-0268] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Pathways of melanosome biogenesis in retinal pigment epithelial (RPE) cells have received less attention than those of skin melanocytes. Although the bulk of melanin synthesis in RPE cells occurs embryonically, it is not clear whether adult RPE cells continue to produce melanosomes. Here, we show that progression from pmel17-positive premelanosomes to tyrosinase-positive mature melanosomes in the RPE is largely complete before birth. Loss of functional Rab38 in the "chocolate" (cht) mouse causes dramatically reduced numbers of melanosomes in adult RPE, in contrast to the mild phenotype previously shown in skin melanocytes. Choroidal melanocytes in cht mice also have reduced melanosome numbers, but a continuing low level of melanosome biogenesis gradually overcomes the defect, unlike in the RPE. Partial compensation by Rab32 that occurs in skin melanocytes is less effective in the RPE, presumably because of the short time window for melanosome biogenesis. In cht RPE, premelanosomes form but delivery of tyrosinase is impaired. Premelanosomes that fail to deposit melanin are unstable in both cht and tyrosinase-deficient RPE. Together with the high levels of cathepsin D in immature melanosomes of the RPE, our results suggest that melanin deposition may protect the maturing melanosome from the activity of lumenal acid hydrolases.
Collapse
Affiliation(s)
- Vanda S. Lopes
- *Molecular and Cellular Medicine, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ, United Kingdom; and
| | - Christina Wasmeier
- *Molecular and Cellular Medicine, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ, United Kingdom; and
| | - Miguel C. Seabra
- *Molecular and Cellular Medicine, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ, United Kingdom; and
| | - Clare E. Futter
- Institute of Ophthalmology, University College London, London EC1V 9EL, United Kingdom
| |
Collapse
|
27
|
Ray K, Chaki M, Sengupta M. Tyrosinase and ocular diseases: Some novel thoughts on the molecular basis of oculocutaneous albinism type 1. Prog Retin Eye Res 2007; 26:323-58. [PMID: 17355913 DOI: 10.1016/j.preteyeres.2007.01.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Tyrosinase (TYR) is a multifunctional copper-containing glycoenzyme (approximately 80 kDa), which plays a key role in the rate-limiting steps of the melanin biosynthetic pathway. This membrane-bound protein, possibly evolved by the fusion of two different copper-binding proteins, is mainly expressed in epidermal, ocular and follicular melanocytes. In the melanocytes, TYR functions as an integrated unit with other TYR-related proteins (TYRP1, TYRP2), lysosome-associated membrane protein 1 (LAMP1) and melanocyte-stimulating hormone receptors; thus forming a melanogenic complex. Mutations in the TYR gene (TYR, 11q14-21, MIM 606933) cause oculocutaneous albinism type 1 (OCA1, MIM 203100), a developmental disorder having an autosomal recessive mode of inheritance. In addition, TYR can act as a modifier locus for primary congenital glaucoma (PCG) and it also contributes significantly in the eye developmental process. Expression of TYR during neuroblast division helps in later pathfinding by retinal ganglion cells from retina to the dorsal lateral geniculate nucleus. However, mutation screening of TYR is complicated by the presence of a pseudogene-TYR like segment (TYRL, 11p11.2, MIM 191270), sharing approximately 98% sequence identity with the 3' region of TYR. Thus, in absence of a full-proof strategy, any nucleotide variants identified in the 3' region of TYR could actually be present in TYRL. Interestingly, despite extensive search, the second TYR mutation in 15% of the OCA1 cases remains unidentified. Several possible locations of these "uncharacterized mutations" (UCMs) have been speculated so far. Based on the structure of TYR gene, its sequence context and some experimental evidences, we propose two additional possibilities, which on further investigations might shed light on the molecular basis of UCMs in TYR of OCA1 patients; (i) partial deletion of the exons 4 and 5 region of TYR that is homologous with TYRL and (ii) variations in the polymorphic GA complex repeat located between distal and proximal elements of the human TYR promoter that can modulate the expression of the gene leading to disease pathogenesis.
Collapse
Affiliation(s)
- Kunal Ray
- Molecular and Human Genetics Division, Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032, India.
| | | | | |
Collapse
|
28
|
Knisely JM, Li Y, Griffith JM, Geuze HJ, Schwartz AL, Bu G. Slow endocytosis of the LDL receptor-related protein 1B: implications for a novel cytoplasmic tail conformation. Exp Cell Res 2007; 313:3298-307. [PMID: 17658514 PMCID: PMC2002472 DOI: 10.1016/j.yexcr.2007.05.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Revised: 05/09/2007] [Accepted: 05/29/2007] [Indexed: 11/19/2022]
Abstract
The LDL receptor-related protein 1B (LRP1B) is a putative tumor suppressor homologous to LRP1. Both LRP1 and LRP1B contain cytoplasmic tails with several potential endocytosis motifs. Although the positions of these endocytic motifs are similar in both receptors, LRP1B is internalized at a 15-fold slower rate than LRP1. To determine whether the slow endocytosis of LRP1B is due to the utilization of an endocytosis motif other than the YATL motif used by LRP1, we tested minireceptors with mutations in each of the five potential motifs in the LRP1B tail. Only mutation of both NPXY motifs together abolished LRP1B endocytosis, suggesting that LRP1B can use either of these motifs for internalization. LRP1B contains a unique insertion of 33 amino acids not present in LRP1 that could lead to altered recognition of trafficking motifs. Surprisingly, deletion of this insertion had no effect on the endocytosis rate of LRP1B. However, replacing either half of the LRP1B tail with the corresponding LRP1 sequence markedly accelerated LRP1B endocytosis. From these data, we propose that both halves of the LRP1B cytoplasmic tail contribute to a unique global conformation, which results in less efficient recognition by endocytic adaptors and a slow endocytosis rate.
Collapse
Affiliation(s)
- Jane M. Knisely
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA
| | - Yonghe Li
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA
| | - Janice M. Griffith
- Department of Cell Biology and Institute of Biomembranes, University Medical Center Utrecht, Utrecht, Netherlands
| | - Hans J. Geuze
- Department of Cell Biology and Institute of Biomembranes, University Medical Center Utrecht, Utrecht, Netherlands
| | - Alan L. Schwartz
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA
| | - Guojun Bu
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA
- Send correspondence to: Guojun Bu, Department of Pediatrics, Washington University School of Medicine, Campus Box 8208, 660 South Euclid Avenue, St. Louis, MO 63110, Tel: (314)286-2860, Fax: (314)286-2894,
| |
Collapse
|
29
|
Kidd GJ, Yadav VK, Huang P, Brand SL, Low SH, Weimbs T, Trapp BD. A dual tyrosine-leucine motif mediates myelin protein P0 targeting in MDCK cells. Glia 2006; 54:135-45. [PMID: 16788992 DOI: 10.1002/glia.20366] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Differential targeting of myelin proteins to multiple, biochemically and functionally distinct Schwann cell plasma membrane domains is essential for myelin formation. In this study, we investigated whether the myelin protein P0 contains targeting signals using Madin-Darby canine kidney (MDCK) cells. By confocal microscopy, P0 was localized to MDCK cell basolateral membranes. C-terminal deletion resulted in apical accumulation, and stepwise deletions defined a 15-mer region that was required for basolateral targeting. Alanine substitutions within this region identified the YAML sequence as a functional tyrosine-based targeting signal, with the ML sequence serving as a secondary leucine-based signal. Replacement of the P0 ectodomain with green fluorescent protein altered the distribution of constructs lacking the YAML signal. Coexpression of the myelin-associated glycoprotein did not alter P0 distribution in MDCK cells. The results indicate that P0 contains a hierarchy of targeting signals, which may contribute to P0 localization in myelinating Schwann cells and the pathogenesis in human disease.
Collapse
Affiliation(s)
- Grahame J Kidd
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
| | | | | | | | | | | | | |
Collapse
|
30
|
Valencia JC, Hoashi T, Pawelek JM, Solano F, Hearing VJ. Pmel17: controversial indeed but critical to melanocyte function. ACTA ACUST UNITED AC 2006; 19:250-2; author reply 253-7. [PMID: 16704461 DOI: 10.1111/j.1600-0749.2006.00308.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
31
|
Theos AC, Berson JF, Theos SC, Herman KE, Harper DC, Tenza D, Sviderskaya EV, Lamoreux ML, Bennett DC, Raposo G, Marks MS. Dual loss of ER export and endocytic signals with altered melanosome morphology in the silver mutation of Pmel17. Mol Biol Cell 2006; 17:3598-612. [PMID: 16760433 PMCID: PMC1525253 DOI: 10.1091/mbc.e06-01-0081] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Pmel17 is a pigment cell-specific integral membrane protein that participates in the formation of the intralumenal fibrils upon which melanins are deposited in melanosomes. The Pmel17 cytoplasmic domain is truncated by the mouse silver mutation, which is associated with coat hypopigmentation in certain strain backgrounds. Here, we show that the truncation interferes with at least two steps in Pmel17 intracellular transport, resulting in defects in melanosome biogenesis. Human Pmel17 engineered with the truncation found in the mouse silver mutant (hPmel17si) is inefficiently exported from the endoplasmic reticulum (ER). Localization and metabolic pulse-chase analyses with site-directed mutants and chimeric proteins show that this effect is due to the loss of a conserved C-terminal valine that serves as an ER exit signal. hPmel17si that exits the ER accumulates abnormally at the plasma membrane due to the loss of a di-leucine-based endocytic signal. The combined effects of reduced ER export and endocytosis significantly deplete Pmel17 within endocytic compartments and delay proteolytic maturation required for premelanosome-like fibrillogenesis. The ER export delay and cell surface retention are also observed for endogenous Pmel17si in melanocytes from silver mice, within which Pmel17 accumulation in premelanosomes is dramatically reduced. Mature melanosomes in these cells are larger, rounder, more highly pigmented, and less striated than in control melanocytes. These data reveal a dual sorting defect in a natural mutant of Pmel17 and support a requirement of endocytic trafficking in Pmel17 fibril formation.
Collapse
Affiliation(s)
- Alexander C. Theos
- *Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Joanne F. Berson
- *Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Sarah C. Theos
- *Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Kathryn E. Herman
- *Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Dawn C. Harper
- *Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Danièle Tenza
- Institut Curie, UMR-144, Centre National de la Recherche Scientifique, Paris, France 75005
| | - Elena V. Sviderskaya
- Division of Basic Medical Sciences, St. George’s, University of London, London SW17 0RE, United Kingdom; and
| | - M. Lynn Lamoreux
- Comparative Genetics Program, Texas A&M University, College Station, TX 77843
| | - Dorothy C. Bennett
- Division of Basic Medical Sciences, St. George’s, University of London, London SW17 0RE, United Kingdom; and
| | - Graça Raposo
- Institut Curie, UMR-144, Centre National de la Recherche Scientifique, Paris, France 75005
| | - Michael S. Marks
- *Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104
| |
Collapse
|
32
|
Piccirillo R, Palmisano I, Innamorati G, Bagnato P, Altimare D, Schiaffino MV. An unconventional dileucine-based motif and a novel cytosolic motif are required for the lysosomal and melanosomal targeting of OA1. J Cell Sci 2006; 119:2003-14. [PMID: 16621890 PMCID: PMC1475362 DOI: 10.1242/jcs.02930] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The protein product of the gene responsible for ocular albinism type 1, named OA1, is a pigment-cell-specific membrane glycoprotein, displaying features of G-protein-coupled receptors, yet exclusively localized to late endosomes, lysosomes and melanosomes. To dissect the signals responsible for the intracellular localization of OA1, we generated chimeric proteins consisting of the cytosolic domains of OA1 fused to the lumenal and transmembrane domains of LAMP1; in addition, we generated missense and deletion mutants of full-length OA1. Using this approach, we identified two separate sorting signals that are both necessary and sufficient for intracellular retention, as well as lysosomal and melanosomal localization, in melanocytic and non-melanocytic cells. These sorting signals are an unconventional dileucine motif within the third cytosolic loop and a novel motif, characterized by a tryptophan-glutamic acid doublet, within the C-terminal tail. Both motifs must be mutated to promote the plasma membrane localization of OA1, suggesting that they can independently drive its intracellular targeting. In addition, both motifs act similarly as lysosomal sorting signals in non-melanocytic cells, but appear to carry different specificities in melanocytic cells. Our findings indicate that OA1 contains multiple unconventional signals responsible for its lysosomal and melanosomal localization, and reveal a remarkable and unforeseen complexity in the regulation of polytopic protein sorting to specialized secretory organelles.
Collapse
Affiliation(s)
- Rosanna Piccirillo
- San Raffalele Scientific Institute, DIBIT, Via Olgettina 58, 20132 Milan, Italy
| | | | | | | | | | | |
Collapse
|
33
|
Lepage S, Lapointe R. Melanosomal targeting sequences from gp100 are essential for MHC class II-restricted endogenous epitope presentation and mobilization to endosomal compartments. Cancer Res 2006; 66:2423-32. [PMID: 16489049 DOI: 10.1158/0008-5472.can-05-2516] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
CD4+ T lymphocytes play an important role in CD8+ T cell-mediated responses against tumors. Considering that approximately 20% of melanomas express MHC class II, it is plausible that concomitant presentation by MHC class I and class II shapes positive (helper T cells) or negative (regulatory T cells) antitumor responses. Interestingly, gp100, a melanoma antigen, can be presented by both MHC class I and class II when expressed endogenously, suggesting that it can reach endosomal/MHC class II compartments (MIIC). Here, we showed that gp100 putative NH2-terminal signal sequence and the last 70 residues in COOH terminus are essential for MIIC localization and MHC class II presentation. Confocal microscopy analyses confirmed that gp100 was localized in LAMP-1+/HLA-DR+ endosomal/MIIC. Gp100 targeting sequences were characterized by deleting different sections in the COOH terminus (last 70 residues). Transfection in 293T cells, expressing MHC class I and class II molecules, revealed that specific deletions in COOH terminus resulted in decreased MHC class II presentation, without effects on class I presentation, suggesting a role in MIIC trafficking for these deleted sections. Then, we used these gp100 targeting sequences to mobilize green fluorescent protein to endosomal compartments and to allow MHC class II and class I presentation of minimal endogenous epitopes. We conclude that these specific sequences are MIIC-targeting motifs, which could be included in expression cassettes for endogenously expressed tumor or viral antigens for MHC class II and class I presentation and optimize in vivo T-cell responses or as an in vitro tool for characterization of new MHC class II epitopes.
Collapse
Affiliation(s)
- Stéphanie Lepage
- Research Centre, Centre Hospitalier de l'Université de Montréal, Hôpital Notre Dame, Université de Montréal and Institut du Cancer de Montréal, Montréal, Québec, Canada
| | | |
Collapse
|
34
|
Wang R, Tang P, Wang P, Boissy RE, Zheng H. Regulation of tyrosinase trafficking and processing by presenilins: partial loss of function by familial Alzheimer's disease mutation. Proc Natl Acad Sci U S A 2005; 103:353-8. [PMID: 16384915 PMCID: PMC1326180 DOI: 10.1073/pnas.0509822102] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Presenilins (PS) are required for gamma-secretase cleavage of multiple type I membrane proteins including the amyloid precursor protein and Notch and also have been implicated in regulating intracellular protein trafficking and turnover. Using genetic and pharmacological approaches, we reveal here a unique function of PS in the pigmentation of retinal pigment epithelium and epidermal melanocytes. PS deficiency leads to aberrant accumulation of tyrosinase (Tyr)-containing 50-nm post-Golgi vesicles that are normally destined to melanosomes. This trafficking is gamma-secretase-dependent, and abnormal localization of Tyr in the absence of PS is accompanied by the simultaneous accumulation of its C-terminal fragment. Furthermore, we show that the PS1M146V familial Alzheimer's disease mutation exhibits a partial loss-of-function in pigment synthesis. Our results identify Tyr and related proteins as physiological substrates of PS and link gamma-secretase activity with intracellular protein transport.
Collapse
Affiliation(s)
- Runsheng Wang
- Huffington Center on Aging and Departments of Molecular and Human Genetics and Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | | | | | | | | |
Collapse
|
35
|
Theos AC, Truschel ST, Raposo G, Marks MS. The Silver locus product Pmel17/gp100/Silv/ME20: controversial in name and in function. ACTA ACUST UNITED AC 2005; 18:322-36. [PMID: 16162173 PMCID: PMC2788625 DOI: 10.1111/j.1600-0749.2005.00269.x] [Citation(s) in RCA: 172] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mouse coat color mutants have led to the identification of more than 120 genes that encode proteins involved in all aspects of pigmentation, from the regulation of melanocyte development and differentiation to the transcriptional activation of pigment genes, from the enzymatic formation of pigment to the control of melanosome biogenesis and movement [Bennett and Lamoreux (2003) Pigment Cell Res. 16, 333]. One of the more perplexing of the identified mouse pigment genes is encoded at the Silver locus, first identified by Dunn and Thigpen [(1930) J. Heredity 21, 495] as responsible for a recessive coat color dilution that worsened with age on black backgrounds. The product of the Silver gene has since been discovered numerous times in different contexts, including the initial search for the tyrosinase gene, the characterization of major melanosome constituents in various species, and the identification of tumor-associated antigens from melanoma patients. Each discoverer provided a distinct name: Pmel17, gp100, gp95, gp85, ME20, RPE1, SILV and MMP115 among others. Although all its functions are unlikely to have yet been fully described, the protein clearly plays a central role in the biogenesis of the early stages of the pigment organelle, the melanosome, in birds, and mammals. As such, we will refer to the protein in this review simply as pre-melanosomal protein (Pmel). This review will summarize the structural and functional aspects of Pmel and its role in melanosome biogenesis.
Collapse
Affiliation(s)
- Alexander C. Theos
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Steven T. Truschel
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Graça Raposo
- Institut Curie, Centre National de la Recherche Scientifique, UMR-144, Paris Cedex, France
| | - Michael S. Marks
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Address correspondence to Michael S. Marks,
| |
Collapse
|
36
|
Beermann F, Orlow SJ, Lamoreux ML. The Tyr (albino) locus of the laboratory mouse. Mamm Genome 2005; 15:749-58. [PMID: 15520878 DOI: 10.1007/s00335-004-4002-8] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2002] [Accepted: 05/24/2004] [Indexed: 11/30/2022]
Abstract
The albino mouse was already known in ancient times and was apparently selectively bred in Egypt, China, and Japan. Thus, it is not surprising that the c or albino locus (now the Tyr locus) was among the first used to demonstrate Mendelian inheritance in mammals at the dawn of the past century. This locus is now known to encode tyrosinase, the rate-limiting enzyme in the production of melanin pigment, and the molecular basis of the albino ( Tyr(c)) mutation is known. Here we describe the congenic series of Tyr-locus alleles, from wild type to null ( albino). We compare eye and skin pigmentation phenotypes and the genetic lesions that cause each. We suggest that this panel of congenic mutants contains rich, untapped resources for the study of many questions of basic cell biological interest.
Collapse
Affiliation(s)
- Friedrich Beermann
- ISREC, National Center of Competence in Research (NCCR)Molecular Oncology, Chemin des Boveresses 155, 1066 Epalinges, Switzerland.
| | | | | |
Collapse
|
37
|
Ni-Komatsu L, Orlow SJ. Heterologous expression of tyrosinase recapitulates the misprocessing and mistrafficking in oculocutaneous albinism type 2: effects of altering intracellular pH and pink-eyed dilution gene expression. Exp Eye Res 2005; 82:519-28. [PMID: 16199032 DOI: 10.1016/j.exer.2005.08.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2005] [Revised: 08/09/2005] [Accepted: 08/11/2005] [Indexed: 11/17/2022]
Abstract
The processing and trafficking of tyrosinase, a melanosomal protein essential for pigmentation, was investigated in a human epithelial 293 cell line that stably expresses the protein. The effects of the pink-eyed dilution (p) gene product, in which mutations result in oculocutaneous albinism type 2 (OCA2), on the processing and trafficking of tyrosinase in this cell line were studied. The majority of tyrosinase was retained in the endoplasmic reticulum-Golgi intermediate compartment and the early Golgi compartment in the 293 cells expressing the protein. Coexpression of p could partially correct the mistrafficking of tyrosinase in 293 cells. Tyrosinase was targeted to the late endosomal and lysosomal compartments after treatment of the cells with compounds that correct the tyrosinase mistrafficking in albino melanocytes, most likely through altering intracellular pH, while the substrate tyrosine had no effect on the processing of tyrosinase. Remarkably, this heterologous expression system recapitulates the defective processing and mistrafficking of tyrosinase observed in OCA2 albino melanocytes and certain amelanotic melanoma cells. Coexpression of other melanosomal proteins in this heterologous system may further aid our understanding of the details of normal and pathologic processing of melanosomal proteins.
Collapse
Affiliation(s)
- Li Ni-Komatsu
- The Ronald O. Perelman Department of Dermatology and Cell Biology, New York University School of Medicine, Dermatology Room H-100, NYU School of Medicine, 560 First Avenue, New York, NY 10016, USA
| | | |
Collapse
|
38
|
Theos AC, Tenza D, Martina JA, Hurbain I, Peden AA, Sviderskaya EV, Stewart A, Robinson MS, Bennett DC, Cutler DF, Bonifacino JS, Marks MS, Raposo G. Functions of adaptor protein (AP)-3 and AP-1 in tyrosinase sorting from endosomes to melanosomes. Mol Biol Cell 2005; 16:5356-72. [PMID: 16162817 PMCID: PMC1266432 DOI: 10.1091/mbc.e05-07-0626] [Citation(s) in RCA: 194] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Specialized cells exploit adaptor protein complexes for unique post-Golgi sorting events, providing a unique model system to specify adaptor function. Here, we show that AP-3 and AP-1 function independently in sorting of the melanocyte-specific protein tyrosinase from endosomes to the melanosome, a specialized lysosome-related organelle distinguishable from lysosomes. AP-3 and AP-1 localize in melanocytes primarily to clathrin-coated buds on tubular early endosomes near melanosomes. Both adaptors recognize the tyrosinase dileucine-based melanosome sorting signal, and tyrosinase largely colocalizes with each adaptor on endosomes. In AP-3-deficient melanocytes, tyrosinase accumulates inappropriately in vacuolar and multivesicular endosomes. Nevertheless, a substantial fraction still accumulates on melanosomes, concomitant with increased association with endosomal AP-1. Our data indicate that AP-3 and AP-1 function in partially redundant pathways to transfer tyrosinase from distinct endosomal subdomains to melanosomes and that the AP-3 pathway ensures that tyrosinase averts entrapment on internal membranes of forming multivesicular bodies.
Collapse
Affiliation(s)
- Alexander C Theos
- Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust, Cambridge CB2 2XY, United Kingdom
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
39
|
Nappi AJ, Christensen BM. Melanogenesis and associated cytotoxic reactions: applications to insect innate immunity. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2005; 35:443-459. [PMID: 15804578 DOI: 10.1016/j.ibmb.2005.01.014] [Citation(s) in RCA: 377] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2004] [Revised: 01/05/2005] [Accepted: 01/07/2005] [Indexed: 05/24/2023]
Abstract
Insects transmit the causative agents for such debilitating diseases as malaria, lymphatic filariases, sleeping sickness, Chagas' disease, leishmaniasis, river blindness, Dengue, and yellow fever. The persistence of these diseases provides testimony to the genetic capacity of parasites to evolve strategies that ensure their successful development in two genetically diverse host species: insects and mammals. Current efforts to address the problems posed by insect-borne diseases benefit from a growing understanding of insect and mammalian immunity. Of considerable interest are recent genomic investigations that show several similarities in the innate immune effector responses and associated regulatory mechanisms manifested by insects and mammals. One notable exception, however, is the nearly universal presence of a brown-black pigment accompanying cellular innate immunity in insects. This response, which is unique to arthropods and certain other invertebrates, has focused attention on the elements involved in pigment synthesis as causing or contributing to the death of the parasite, and has even prompted speculation that the enzyme cascade mediating melanogenesis constitutes an ill-defined recognition mechanism. Experimental evidence defining the role of melanin and its precursors in insect innate immunity is severely lacking. A great deal of what is known about melanogenesis comes from studies of the process occurring in mammalian systems, where the pigment is synthesized by such diverse cells as those comprising portions of the skin, hair, inner ear, brain, and retinal epithelium. Fortunately, many of the components in the metabolic pathways leading to the formation of melanin have been found to be common to both insects and mammals. This review examines some of the factors that influence enzyme-mediated melanogenic responses, and how these responses likely contribute to blood cell-mediated, target-specific cytotoxicity in immune challenged insects.
Collapse
Affiliation(s)
- A J Nappi
- Department of Animal Health and Biomedical Sciences, University of Wisconsin-Madison, WI 53706, USA.
| | | |
Collapse
|
40
|
Storch S, Pohl S, Braulke T. A dileucine motif and a cluster of acidic amino acids in the second cytoplasmic domain of the batten disease-related CLN3 protein are required for efficient lysosomal targeting. J Biol Chem 2004; 279:53625-34. [PMID: 15469932 DOI: 10.1074/jbc.m410930200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The juvenile form of ceroid lipofuscinosis (Batten disease) is a neurodegenerative lysosomal storage disorder caused by mutations in the CLN3 gene. CLN3 encodes a multimembrane-spanning protein of unknown function, which is mainly localized in lysosomes in non-neuronal cells and in endosomes in neuronal cells. For this study we constructed chimeric proteins of three CLN3 cytoplasmic domains fused to the lumenal and transmembrane domains of the reporter proteins LAMP-1 and lysosomal acid phosphatase to identify lysosomal targeting motifs and to determine the intracellular transport and subcellular localization of the chimera in transfected cell lines. We report that a novel type of dileucine-based sorting motif, EEEX(8)LI, present in the second cytoplasmic domain of CLN3, is sufficient for proper targeting to lysosomes. The first cytoplasmic domain of CLN3 and the mutation of the dileucine motif resulted in a partial missorting of chimeric proteins to the plasma membrane. At equilibrium, 4-13% of the different chimera are present at the cell surface. Analysis of lysosome-specific proteolytic processing revealed that lysosomal acid phosphatase chimera containing the second cytoplasmic domain of CLN3 showed the highest rate of lysosomal delivery, whereas the C terminus of CLN3 was found to be less efficient in lysosomal targeting. However, none of these cytosolic CLN3 domains was able to interact with AP-1, AP-3, or GGA3 adaptor complexes. These data revealed that lysosomal sorting motifs located in an intramolecular cytoplasmic domain of a multimembrane-spanning protein have different structural requirements for adaptor binding than sorting signals found in the C-terminal cytoplasmic domains of single- or dual-spanning lysosomal membrane proteins.
Collapse
Affiliation(s)
- Stephan Storch
- Department of Biochemistry, Children's Hospital, University of Hamburg, D-20246 Hamburg, Germany
| | | | | |
Collapse
|
41
|
Brück J, Steitz J, Strand D, Tüting T. Altered intracellular sorting signals do not influence the efficacy of genetic melanoma vaccines incorporating helper determinants in mice. J Gene Med 2004; 7:613-20. [PMID: 15580620 DOI: 10.1002/jgm.702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND A genetic melanoma vaccine consisting of cDNA encoding the model self-antigen tyrosinase-related protein 2 (TRP2) fused in-frame to the immunogenic enhanced green fluorescent protein (EGFP) was able to break immune tolerance and stimulate CD8+ T cells in vivo. In the present study we investigated whether alteration of the intracellular antigen localization as a result of the linkage with immune-enhancing helper proteins affects the resulting immune response. METHODS Expression plasmids and recombinant adenoviruses were constructed encoding various fusion proteins with different intracellular sorting signals which direct the antigen to the cytosol, the endoplasmic reticulum or the endosomal compartments. Genetic immunization of C57BL/6 mice was performed with all constructs using particle-bombardment of the skin and injection of recombinant adenoviruses. The resulting immune response was analyzed using ELISPOT and tumor rejection assays. RESULTS Induction of TRP2-specific CD8+ T cells in vivo and autoimmune-mediated destruction of melanocytes in the bombarded area of the skin were observed with all constructs expressing fusion proteins between TRP2 and EGFP. Importantly, injections of the different recombinant adenoviruses all mediated protective immunity against transplanted B16 melanoma cells. CONCLUSIONS Altered intracellular sorting signals do not significantly influence the efficacy of genetic melanoma vaccines incorporating helper determinants in our model system. These results further support the concept that linkage of immunogenic helper sequences can be successfully applied for antigen-specific immunotherapy of melanoma and provide a scientific basis for the translation of this strategy in future clinical applications.
Collapse
Affiliation(s)
- Jürgen Brück
- Laboratory of Experimental Dermatology, Department of Dermatology, University of Bonn, Germany
| | | | | | | |
Collapse
|
42
|
Chen K, Minwalla L, Ni L, Orlow SJ. Correction of defective early tyrosinase processing by bafilomycin A1 and monensin in pink-eyed dilution melanocytes. ACTA ACUST UNITED AC 2004; 17:36-42. [PMID: 14717843 DOI: 10.1046/j.1600-0749.2003.00106.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mutations in the human P gene result in oculocutaneous albinism type 2, the most common form of albinism. Mouse melan-p1 melanocytes, cultured from mice null at the homologous pink-eyed dilution (p) locus, exhibit defective melanin production. A variety of compounds including tyrosine, NH4Cl, bafilomycin A1, concanamycin, monensin, and nigericin are capable of restoring melanin synthesis in these cells. In the current study, we investigated the subcellular effects of bafilomycin A1 and monensin treatment of melan-p1 cells. Both agents play two roles in the processing of tyrosinase (Tyr) in melan-p1 cells. First, combined glycosidase digestion and immunoblotting analysis showed that these agents reduce levels of Tyr retained in the endoplasmic reticulum (ER) and facilitate the release of Tyr from the ER to the Golgi. Secondly, treatment with these compounds resulted in the stabilization of Tyr. Surprisingly, induction of melanin synthesis corresponds more closely with diminution of ER-retained Tyr, rather than the absolute amount of Tyr. Our results suggest that bafilomycin A1 and monensin induce melanin synthesis in melan-p1 cells mainly by facilitating Tyr processing from the ER to the Golgi by increasing the pH in either the ER or the ER-Golgi intermediate compartment.
Collapse
Affiliation(s)
- Kun Chen
- The Ronald O. Perelman Department of Dermatology, New York University School of Medicine, New York, NY10016, USA
| | | | | | | |
Collapse
|
43
|
Kamada A, Nagaya H, Tamura T, Kinjo M, Jin HY, Yamashita T, Jimbow K, Kanoh H, Wada I. Regulation of Immature Protein Dynamics in the Endoplasmic Reticulum. J Biol Chem 2004; 279:21533-42. [PMID: 14976197 DOI: 10.1074/jbc.m401403200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The quality of nascent protein folding in vivo is influenced by the microdynamics of the proteins. Excessive collisions between proteins may lead to terminal misfolding, and the frequency of protein interactions with molecular chaperones determines their folding rates. However, it is unclear how immature protein dynamics are regulated. In this study, we analyzed the diffusion of immature tyrosinase in the endoplasmic reticulum (ER) of non-pigmented cells by taking advantage of the thermal sensitivity of the tyrosinase. The diffusion of tyrosinase tagged with yellow fluorescence protein (YFP) in living cells was directly measured using fluorescent correlation spectroscopy. The diffusion of folded tyrosinase in the ER of cells treated with brefeldin A, as measured by fluorescent correlation spectroscopy, was critically affected by the expression level of tyrosinase-YFP. Under defined conditions in which random diffusional motion of folded protein was allowed, we found that the millisecond-order diffusion rate observed for folded tyrosinase almost disappeared for the misfolded molecules synthesized at a nonpermissive high temperature. This was not because of enhanced aggregation at the high temperature, as terminally misfolded tyrosinase synthesized in the absence of calnexin interactions showed comparable, albeit slightly slower, diffusion. Yet, the thermally misfolded tyrosinase was not immobilized when measured by fluorescence recovery after photobleaching. In contrast, terminally misfolded tyrosinase synthesized in cells in which alpha-glucosidases were inhibited showed extensive immobilization. Hence, we suggest that the ER represses random fluctuations of immature tyrosinase molecules while preventing their immobilization.
Collapse
Affiliation(s)
- Asako Kamada
- Department of Dermatology, Sapporo Medical University School of Medicine, Sapporo 060-8556, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Mao Q, Xia H, Davidson BL. Intracellular trafficking of CLN3, the protein underlying the childhood neurodegenerative disease, Batten disease. FEBS Lett 2004; 555:351-7. [PMID: 14644441 DOI: 10.1016/s0014-5793(03)01274-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Juvenile neuronal ceroid lipofuscinoses (Batten disease) is a progressive neurodegenerative disorder resulting from mutations in the CLN3 gene, which encodes a hydrophobic 438 amino acid protein of unknown function. Prior studies have shown that CLN3 is expressed in multiple tissues, with highest levels in brain and testis. Experiments using cells overexpressing CLN3 indicate that CLN3 is a lysosomal resident protein. However, studies to date have not addressed trafficking of endogenous CLN3. As such, the purpose of the present study was two-fold. First, to develop a culture model to allow evaluation of native CLN3 transport. Second, to utilize available epitope-specific antibodies to determine if CLN3 reaches the plasma membrane en route to the lysosome. Our data using a NCCIT (embryonic testicular carcinoma) cell model coupled with surface biotinylation and antibody trapping demonstrated that at least a proportion of CLN3 trafficks to the lysosome via the cell membrane. Moreover, inhibition of the micro3A subunit of the AP-3 adapter protein complex increased levels of CLN3 at the cell surface.
Collapse
Affiliation(s)
- Qinwen Mao
- Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, IA 52242, USA
| | | | | |
Collapse
|
45
|
Hasegawa T, Matsuzaki M, Takeda A, Kikuchi A, Furukawa K, Shibahara S, Itoyama Y. Increased dopamine and its metabolites in SH-SY5Y neuroblastoma cells that express tyrosinase. J Neurochem 2003; 87:470-5. [PMID: 14511124 DOI: 10.1046/j.1471-4159.2003.02008.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Oxidized metabolites of dopamine, known as dopamine quinone derivatives, are thought to play a pivotal role in the degeneration of dopaminergic neurons. Although such quinone derivatives are usually produced via the autoxidation of catecholamines, tyrosinase, which is a key enzyme in melanin biosynthesis via the production of DOPA and subsequent molecules, may potentially accelerate the induction of catecholamine quinone derivatives by its oxidase activity. In the present study, we developed neuronal cell lines in which the expression of human tyrosinase was inducible. Overexpression of tyrosinase in cultured cell lines resulted in (i) increased intracellular dopamine content; (ii) induction of oxidase activity not only for DOPA but also for dopamine; (iii) formation of melanin pigments in cell soma; and (iv) increased intracellular reactive oxygen species. Interestingly, the expressed tyrosinase protein was initially distributed in the entire cytoplasm and then accumulated to form catecholamine-positive granular structures by 3 days after the induction. The granular structures consisted of numerous rounded, dark bodies of melanin pigments and were largely coincident with the distribution of lysosomes. This cellular model that exhibits increased dopamine production will provide a useful tool for detailed analyses of the potentially noxious effects of oxidized catecholamine metabolites.
Collapse
Affiliation(s)
- Takafumi Hasegawa
- Department of Neurology, Tohoku University School of Medicine, Sendai, Miyaga, Japan
| | | | | | | | | | | | | |
Collapse
|
46
|
Setaluri V. The Melanosome: Dark Pigment Granule Shines Bright Light on Vesicle Biogenesis and More. J Invest Dermatol 2003; 121:650-60. [PMID: 14632178 DOI: 10.1046/j.1523-1747.2003.12500.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Vijayasaradhi Setaluri
- Department of Dermatology, Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA
| |
Collapse
|
47
|
Jaanson N, Möll K, Kulla A, Ustav M. Identification of the immunodominant regions of the melanoma antigen tyrosinase by anti-tyrosinase monoclonal antibodies. Melanoma Res 2003; 13:473-82. [PMID: 14512789 DOI: 10.1097/00008390-200310000-00006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Tyrosinase, the critical enzyme in melanin synthesis, is also found to be expressed in most malignant melanomas and can serve as a target for the immune response by both CD4+ and CD8+ T-cells. Therefore it could be used as a potential target for therapeutic intervention in tyrosinase-positive melanomas. In order to develop serological reagents for the immunodetection of human tyrosinase and to find the most immunogenic region of the protein, we have raised a panel of monoclonal antibodies (MAbs) against recombinant tyrosinase expressed and purified from bacteria. Epitope mapping revealed the 79 amino acid long stretch between 163 and 241 residues to be the most immunodominant region of the tyrosinase. This region could be further divided into three parts by binding different MAbs. These MAbs were very useful tools for the detection of tyrosinase expression from different constructs in tissue culture cells by immunocytochemistry and in melanocytes by immunohistochemistry. Some of the MAbs that recognized epitopes between 163 and 204 amino acids also recognized an additional distinct protein of about 70 kDa seen on Western blot analysis of transfected and non-transfected COS-7 cells. One of these, the MAb 4B1, was used in immunohistochemistry, and cross reaction with the basement membrane of the human tissue was observed. The analysis of the 4B1 MAb epitope showed that the C-terminal part of that region almost entirely overlaps with the sequence of the recently reported basement membrane protein beta-netrin.
Collapse
Affiliation(s)
- Nele Jaanson
- Department of Microbiology and Virology, Tartu University, Estonia and Department of Pathology and Neuropathology, Tartu University Clinics, Tartu, Estonia
| | | | | | | |
Collapse
|
48
|
Wang W, Loh HH, Law PY. The intracellular trafficking of opioid receptors directed by carboxyl tail and a di-leucine motif in Neuro2A cells. J Biol Chem 2003; 278:36848-58. [PMID: 12851402 DOI: 10.1074/jbc.m301540200] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mu- and delta-opioid receptors (MOR and DOR) differ significantly in their intracellular trafficking. MORs recycle back to the cell surface upon agonist treatment, whereas most internalized DORs are targeted to lysosomes for degradation. By exchanging the carboxyl tail domains of MOR and DOR and expressing the receptor chimeras in mouse neuroblastoma Neuro2A cells, it could be demonstrated that the carboxyl tail domain is not the sole determinant in directing the intracellular trafficking in these Neuro2A cells. Deletion of the dileucine motif (Leu245-Leu246) within the third intracellular loop of DOR or the mutation of Leu245 to Met slowed the lysosomal targeting of these delta-opioid receptors. Meanwhile the mutation of Met264 to Leu increased the rate of agonist-induced receptor internalization and the lysosomal targeting of the wild type and the delta-opioid receptor carboxyl tail chimera of the mu-opioid receptor. These studies suggest interplay between a di-leucine motif and the carboxyl tail in the lysosomal targeting of the receptor.
Collapse
Affiliation(s)
- Wei Wang
- Department of Pharmacology, Medical School, University of Minnesota, Minneapolis, Minnesota 55455-0217, USA
| | | | | |
Collapse
|
49
|
Raposo G, Fevrier B, Stoorvogel W, Marks MS. Lysosome-related organelles: a view from immunity and pigmentation. Cell Struct Funct 2002; 27:443-56. [PMID: 12576637 DOI: 10.1247/csf.27.443] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Lysosomes are ubiquitous organelles that carry out essential household functions. Certain cell types, however, contain lysosome-related organelles with specialized functions. Their specialized functions are usually reflected by specific morphological and compositional features. A number of diseases that develop due to genetic mutations, pathogen exposure or cell transformation are characterized by dysfunctional lysosomes and/or lysosome-related organelles. In this review we highlight adaptations and malfunction of the endosomal/lysosomal system in normal and pathological situations with special focus on MHC class II compartments in antigen presenting cells and melanosomes in pigment cells.
Collapse
Affiliation(s)
- Graça Raposo
- Centre National de la Recherche Scientifique, UMR 144, Institut Curie, 75005 Paris, France.
| | | | | | | |
Collapse
|
50
|
De Mazière AM, Muehlethaler K, van Donselaar E, Salvi S, Davoust J, Cerottini JC, Lévy F, Slot JW, Rimoldi D. The melanocytic protein Melan-A/MART-1 has a subcellular localization distinct from typical melanosomal proteins. Traffic 2002; 3:678-93. [PMID: 12191019 DOI: 10.1034/j.1600-0854.2002.30909.x] [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: 11/23/2022]
Abstract
To delineate the role of the melanocyte lineage-specific protein Melan-A/MART-1 in melanogenic functions, a set of biochemical and microscopical studies was performed. Biochemical analysis revealed that Melan-A/MART-1 is post-translationally acylated and undergoes a rapid turnover in a pigmented melanoma cell line. Immunofluorescence and immunoelectron microscopy analyses indicated that Melan-A/MART-1 is mainly located in the Golgi area and only partially colocalizes with melanosomal proteins. Quantitative immunoelectron microscopy showed that the highest proportion of the cellular content of Melan-A/MART-1 was found in small vesicles and tubules throughout the cell, whereas the concentration was maximal in the Golgi region, particularly the trans-Golgi network. Substantial labeling was also present on melanosomes, endosomes, ER, nuclear envelope, and plasma membrane. In early endosomes, Melan-A was enriched in areas of the limiting membrane covered by a bi-layered coat, a structural characteristic of melanosomal precursor compartments. Upon melanosome maturation, Melan-A concentration decreased and its predominant localization shifted from the limiting membrane to internal vesicle membranes. In conjunction with its acylation, the high expression levels of Melan-A in the trans-Golgi network, in dispersed vesicles, and on the limiting membrane of premelanosomes indicate that the protein may play a role during the early stage of melanosome biogenesis.
Collapse
Affiliation(s)
- Ann M De Mazière
- Department of Cell Biology, University Medical Center, Institute of Biomembranes, Utrecht, the Netherlands.
| | | | | | | | | | | | | | | | | |
Collapse
|