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Whole-Exome Sequencing Identified a Novel Homozygous Frameshift Mutation of HPS3 in a Consanguineous Family with Hermansky-Pudlak Syndrome. BIOMED RESEARCH INTERNATIONAL 2021; 2021:4535349. [PMID: 34608437 PMCID: PMC8487392 DOI: 10.1155/2021/4535349] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 09/05/2021] [Accepted: 09/11/2021] [Indexed: 11/25/2022]
Abstract
Hermansky-Pudlak syndrome (HPS) is a rare genetic disorder with an autosomal recessive inherited pattern. It is mainly characterized by deficiencies in lysosome-related organelles, such as melanosomes and platelet-dense granules, and leads to albinism, visual impairment, nystagmus, and bleeding diathesis. A small number of patients will present with granulomatous colitis or fatal pulmonary fibrosis. At present, mutations in ten known genetic loci (HPS1–11) have been identified to be the genetic cause of HPS. In this study, we enrolled a consanguineous family who presented with typical HPS phenotypes, such as albinism, visual impairment, nystagmus, and bleeding diathesis. Whole-exome sequencing and Sanger sequencing were applied to explore the genetic lesions of the patient. A novel homozygous frameshift mutation (NM_032383.5, c.1231dupG/p.Aps411GlyfsTer32) of HPS3 was identified and cosegregated in the family members. Furthermore, real-time PCR confirmed that the mutation decreased the expression of HPS3, which has been identified as the disease-causing gene of HPS type 3. According to ACMG guidelines, the novel mutation, resulting in a premature stop codon at amino acid 442, is a pathogenic variant. In summary, we identified a novel mutation (NM_032383.5, c.1231dupG/p.Aps411GlyfsTer32) of HPS3 in a family with HPS. Our study expanded the variant spectrum of the HPS3 gene and contributed to genetic counseling and prenatal genetic diagnosis of the family.
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Baiomi A, Abbas H, Dev A. Hermansky-Pudlak Syndrome: A Rare Cause of Post-polypectomy Bleeding. Cureus 2021; 13:e13781. [PMID: 33842157 PMCID: PMC8030642 DOI: 10.7759/cureus.13781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
A colonoscopy is an effective tool for colorectal cancer screening, which aims at identifying precancerous polyps and removing them. Post-polypectomy bleeding (PPB) is one of the most common complications of endoscopic polypectomy. Here, we report a rare and interesting case of a 68-year-old man known to have Hermansky-Pudlak syndrome (HPS) who presented with two days history of rectal bleeding one day after he had a screening colonoscopy with polypectomy. He had a drop in his hemoglobin count and was admitted to the medicine floor and given 1-desamino-8-D-arginine vasopressin (DDAVP). Later, his bleeding stopped and he reported improvement in his symptoms. This case illustrates the importance of considering platelet transfusion and/or administration during minor surgical procedures for patients with bleeding diathesis such as Hermansky-Pudlak syndrome.
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Affiliation(s)
- Ahmed Baiomi
- Internal Medicine, BronxCare Health System, Bronx, USA
| | - Hafsa Abbas
- Internal Medicine: Gastroenterology, BronxCare Health System, Bronx, USA
| | - Anil Dev
- Gastroenterology, BronxCare Health System, Bronx, USA
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McCarthy L, Bentley‐DeSousa A, Denoncourt A, Tseng Y, Gabriel M, Downey M. Proteins required for vacuolar function are targets of lysine polyphosphorylation in yeast. FEBS Lett 2019; 594:21-30. [DOI: 10.1002/1873-3468.13588] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 08/22/2019] [Accepted: 08/23/2019] [Indexed: 12/15/2022]
Affiliation(s)
- Liam McCarthy
- Department of Cellular and Molecular Medicine University of Ottawa Canada
- Ottawa Institute of Systems Biology University of Ottawa Canada
| | - Amanda Bentley‐DeSousa
- Department of Cellular and Molecular Medicine University of Ottawa Canada
- Ottawa Institute of Systems Biology University of Ottawa Canada
| | - Alix Denoncourt
- Department of Cellular and Molecular Medicine University of Ottawa Canada
- Ottawa Institute of Systems Biology University of Ottawa Canada
| | - Yi‐Chieh Tseng
- Department of Cellular and Molecular Medicine University of Ottawa Canada
- Ottawa Institute of Systems Biology University of Ottawa Canada
| | - Matthew Gabriel
- Department of Cellular and Molecular Medicine University of Ottawa Canada
- Ottawa Institute of Systems Biology University of Ottawa Canada
| | - Michael Downey
- Department of Cellular and Molecular Medicine University of Ottawa Canada
- Ottawa Institute of Systems Biology University of Ottawa Canada
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Rains A, Bryant Y, Dorsett KA, Culver A, Egbaria J, Williams A, Barnes M, Lamere R, Rossi AR, Waldrep SC, Wilder C, Kliossis E, Styers ML. Ypt4 and lvs1 regulate vacuolar size and function in Schizosaccharomyces pombe. CELLULAR LOGISTICS 2017; 7:e1335270. [PMID: 28944093 PMCID: PMC5602425 DOI: 10.1080/21592799.2017.1335270] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 05/18/2017] [Accepted: 05/22/2017] [Indexed: 10/25/2022]
Abstract
The yeast vacuole plays key roles in cellular stress responses. Here, we show that deletion of lvs1, the fission yeast homolog of the Chediak-Higashi Syndrome CHS1/LYST gene, increases vacuolar size, similar to deletion of the Rab4 homolog ypt4. Overexpression of lvs1-YFP rescued vacuolar size in ypt4Δ cells, but ypt4-YFP did not rescue lvs1Δ, suggesting that lvs1 may act downstream of ypt4. Vacuoles were capable of hypotonic shock-induced fusion and recovery in both ypt4Δ and lvs1Δ cells, although recovery may be slightly delayed in ypt4Δ. Endocytic and secretory trafficking were not affected, but ypt4Δ and lvs1Δ strains were sensitive to neutral pH and CaCl2, consistent with vacuolar dysfunction. In addition to changes in vacuolar size, deletion of ypt4 also dramatically increased cell size, similar to tor1 mutants. These results implicate ypt4 and lvs1 in maintenance of vacuolar size and suggest that ypt4 may link vacuolar homeostasis to cell cycle progression.
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Affiliation(s)
- Addison Rains
- Department of Biology, Birmingham-Southern College, Birmingham, AL, USA
| | - Yorisha Bryant
- Department of Biology, Birmingham-Southern College, Birmingham, AL, USA
| | - Kaitlyn A Dorsett
- Department of Biology, Birmingham-Southern College, Birmingham, AL, USA
| | - Austin Culver
- Department of Biology, Birmingham-Southern College, Birmingham, AL, USA
| | - Jamal Egbaria
- Department of Biology, Birmingham-Southern College, Birmingham, AL, USA
| | - Austin Williams
- Department of Biology, Birmingham-Southern College, Birmingham, AL, USA
| | - Matt Barnes
- Department of Biology, Birmingham-Southern College, Birmingham, AL, USA
| | - Raeann Lamere
- Department of Biology, Birmingham-Southern College, Birmingham, AL, USA
| | - Austin R Rossi
- Department of Biology, Birmingham-Southern College, Birmingham, AL, USA
| | | | - Caroline Wilder
- Department of Biology, Birmingham-Southern College, Birmingham, AL, USA
| | - Elliot Kliossis
- Department of Biology, Birmingham-Southern College, Birmingham, AL, USA
| | - Melanie L Styers
- Department of Biology, Birmingham-Southern College, Birmingham, AL, USA
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Abstract
Thiol isomerases are multifunctional enzymes that influence protein structure via their oxidoreductase, isomerase, and chaperone activities. These enzymes localize at high concentrations in the endoplasmic reticulum of all eukaryotic cells where they serve an essential function in folding nascent proteins. However, thiol isomerases can escape endoplasmic retention and be secreted and localized on plasma membranes. Several thiol isomerases including protein disulfide isomerase, ERp57, and ERp5 are secreted by and localize to the membranes of platelets and endothelial cells. These vascular thiol isomerases are released following vessel injury and participate in thrombus formation. Although most of the activities of vascular thiol isomerases that contribute to thrombus formation are yet to be defined at the molecular level, allosteric disulfide bonds that are modified by thiol isomerases have been described in substrates such as αIIbβ3, αvβ3, GPIbα, tissue factor, and thrombospondin. Vascular thiol isomerases also act as redox sensors. They respond to the local redox environment and influence S-nitrosylation of surface proteins on platelets and endothelial cells. Despite our rudimentary understanding of the mechanisms by which thiol isomerases control vascular function, the clinical utility of targeting them in thrombotic disorders is already being explored in clinical trials.
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Abstract
Visual defects affect a large proportion of humanity, have a significant negative impact on quality of life, and cause significant economic burden. The wide variety of visual disorders and the large number of gene mutations responsible require a flexible animal model system to carry out research for possible causes and cures for the blinding conditions. With eyes similar to humans in structure and function, zebrafish are an important vertebrate model organism that is being used to study genetic and environmental eye diseases, including myopia, glaucoma, retinitis pigmentosa, ciliopathies, albinism, and diabetes. This review details the use of zebrafish in modeling human ocular diseases.
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Affiliation(s)
- Brian A Link
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin 53226; ,
| | - Ross F Collery
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin 53226; ,
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Lőrincz P, Takáts S, Kárpáti M, Juhász G. iFly: The eye of the fruit fly as a model to study autophagy and related trafficking pathways. Exp Eye Res 2015; 144:90-8. [PMID: 26091788 DOI: 10.1016/j.exer.2015.06.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 05/28/2015] [Accepted: 06/15/2015] [Indexed: 12/21/2022]
Abstract
Autophagy is a process by which eukaryotic cells degrade and recycle their intracellular components within lysosomes. Autophagy is induced by starvation to ensure survival of individual cells, and it has evolved to fulfill numerous additional roles in animals. Autophagy not only provides nutrient supply through breakdown products during starvation, but it is also required for the elimination of damaged or surplus organelles, toxic proteins, aggregates, and pathogens, and is essential for normal organelle turnover. Because of these roles, defects in autophagy have pathological consequences. Here we summarize the current knowledge of autophagy and related trafficking pathways in a convenient model: the compound eye of the fruit fly Drosophila melanogaster. In our review, we present a general introduction of the development and structure of the compound eye. This is followed by a discussion of various neurodegeneration models including retinopathies, with special emphasis on the protective role of autophagy against these diseases.
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Affiliation(s)
- Péter Lőrincz
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pázmány s. 1/C, Budapest H-1117, Hungary
| | - Szabolcs Takáts
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pázmány s. 1/C, Budapest H-1117, Hungary
| | - Manuéla Kárpáti
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pázmány s. 1/C, Budapest H-1117, Hungary
| | - Gábor Juhász
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pázmány s. 1/C, Budapest H-1117, Hungary; Momentum Drosophila Autophagy Research Group, Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, Szeged H-6726, Hungary.
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Zlatic SA, Tornieri K, L'hernault SW, Faundez V. Metazoan cell biology of the HOPS tethering complex. CELLULAR LOGISTICS 2014; 1:111-117. [PMID: 21922076 DOI: 10.4161/cl.1.3.17279] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2011] [Revised: 07/18/2011] [Accepted: 07/20/2011] [Indexed: 01/09/2023]
Abstract
Membrane fusion with vacuoles, the lysosome equivalent of the yeast Saccharomyces cerevisiae, is among the best understood membrane fusion events. Our precise understanding of this fusion machinery stems from powerful genetics and elegant in vitro reconstitution assays. Central to vacuolar membrane fusion is the multi-subunit tether the HO motypic fusion and Protein Sorting (HOPS) complex, a complex of proteins that organizes other necessary components of the fusion machinery. We lack a similarly detailed molecular understanding of membrane fusion with lysosomes or lysosome-related organelles in metazoans. However, it is likely that fundamental principles of how rabs, SNAREs and HOPS tethers work to fuse membranes with lysosomes and related organelles are conserved between Saccharomyces cerevisiae and metazoans. Here, we discuss emerging differences in the coat-dependent mechanisms that govern HOPS complex subcellular distribution between Saccharomyces cerevisiae and metazoans. These differences reside upstream of the membrane fusion event. We propose that the differences in how coats segregate class C Vps/HOPS tethers to organelles and domains of metazoan cells are adaptations to complex architectures that characterize metazoan cells such as those of neuronal and epithelial tissues.
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Affiliation(s)
- Stephanie A Zlatic
- Graduate Program in Biochemistry, Cell and Developmental Biology; Emory University; Atlanta, GA USA
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Kaseda K, Goto T, Emoto K, Hayashi Y. Surgery for secondary pneumothorax caused by Hermansky-Pudlak syndrome. Eur Respir J 2014; 44:1715-7. [PMID: 25234801 DOI: 10.1183/09031936.00107714] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Kaoru Kaseda
- Division of General Thoracic Surgery, Dept of Surgery, School of Medicine, Keio University, Tokyo, Japan
| | - Taichiro Goto
- Division of General Thoracic Surgery, Dept of Surgery, School of Medicine, Keio University, Tokyo, Japan
| | - Katsura Emoto
- Dept of Pathology, School of Medicine, Keio University, Tokyo, Japan
| | - Yuichiro Hayashi
- Dept of Pathology, School of Medicine, Keio University, Tokyo, Japan
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Jing R, Dong X, Li K, Yan J, Chen X, Feng L. The Ap3b1 gene regulates the ocular melanosome biogenesis and tyrosinase distribution differently from the Hps1 gene. Exp Eye Res 2014; 128:57-66. [PMID: 25160823 DOI: 10.1016/j.exer.2014.08.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 07/07/2014] [Accepted: 08/16/2014] [Indexed: 11/29/2022]
Abstract
Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder in humans and mice. The pearl (pe) mouse, a mouse model for the human HPS-2, bears a mutation in Ap3b1 gene. Here we investigated the pigmentation in eyes of pearl (pe) mice, and compared it with our previously published data in pale ear (ep) mice. We revealed that the hypopigmentation in eyes of pearl mice was more severe than pale ear mice, especially in the neural crest-derived tissues. However, the total tyrosinase activity in eyes of pearl mice was stronger than pale ear mice, suggesting that the degradation of aberrantly transported tyrosinase in eyes of pearl mice was weaker than that of pale ear mice. Furthermore, the pigmentation in eyes of mice doubly heterozygous for Hps1 and Ap3b1 genes was similar to the wild-type, while the hypopigmentation in iris of double mutant mice was more severe than either single mutant. Besides, we found several previously reported characters in pale ear mice, including macromelanosomes in the neural crest-derived melanocytes and increased accumulation of lipofuscin in the RPE, were absent in pearl mice. Our study indicates that Ap3b1 gene play distinct roles in melanin production and tyrosinase distribution compared with Hps1 gene.
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Affiliation(s)
- Renwei Jing
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, Institute of Developmental Biology, School of Life Sciences, Shandong University, Jinan, Shandong, 250100, PR China; Basic Medical College, Tianjin Medical University, Qixiangtai Road, Heping District, Tianjin, 300070, PR China.
| | - Xuan Dong
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, Institute of Developmental Biology, School of Life Sciences, Shandong University, Jinan, Shandong, 250100, PR China
| | - Kailin Li
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, Institute of Developmental Biology, School of Life Sciences, Shandong University, Jinan, Shandong, 250100, PR China; Central Research Laboratory, The Second Hospital of Shandong University, Jinan, 250100, PR China
| | - Jie Yan
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, Institute of Developmental Biology, School of Life Sciences, Shandong University, Jinan, Shandong, 250100, PR China
| | - Xiangyuan Chen
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, Institute of Developmental Biology, School of Life Sciences, Shandong University, Jinan, Shandong, 250100, PR China
| | - Lijun Feng
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, Institute of Developmental Biology, School of Life Sciences, Shandong University, Jinan, Shandong, 250100, PR China.
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Martinelli D, Dionisi-Vici C. AP1S1 defect causing MEDNIK syndrome: a new adaptinopathy associated with defective copper metabolism. Ann N Y Acad Sci 2014; 1314:55-63. [DOI: 10.1111/nyas.12426] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Diego Martinelli
- Unit of Metabolism; Department of Pediatrics; Bambino Gesu Children's Hospital; Rome Italy
- Section on Translational Neuroscience; Molecular Medicine Program; NICHD/NIH; Bethesda Maryland
| | - Carlo Dionisi-Vici
- Unit of Metabolism; Department of Pediatrics; Bambino Gesu Children's Hospital; Rome Italy
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Cox K, Price V, Kahr WHA. Inherited platelet disorders: a clinical approach to diagnosis and management. Expert Rev Hematol 2014; 4:455-72. [DOI: 10.1586/ehm.11.41] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Montoliu L, Grønskov K, Wei AH, Martínez-García M, Fernández A, Arveiler B, Morice-Picard F, Riazuddin S, Suzuki T, Ahmed ZM, Rosenberg T, Li W. Increasing the complexity: new genes and new types of albinism. Pigment Cell Melanoma Res 2013; 27:11-8. [PMID: 24066960 DOI: 10.1111/pcmr.12167] [Citation(s) in RCA: 151] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 09/08/2013] [Accepted: 09/17/2013] [Indexed: 12/24/2022]
Abstract
Albinism is a rare genetic condition globally characterized by a number of specific deficits in the visual system, resulting in poor vision, in association with a variable hypopigmentation phenotype. This lack or reduction in pigment might affect the eyes, skin, and hair (oculocutaneous albinism, OCA), or only the eyes (ocular albinism, OA). In addition, there are several syndromic forms of albinism (e.g. Hermansky-Pudlak and Chediak-Higashi syndromes, HPS and CHS, respectively) in which the described hypopigmented and visual phenotypes coexist with more severe pathological alterations. Recently, a locus has been mapped to the 4q24 human chromosomal region and thus represents an additional genetic cause of OCA, termed OCA5, while the gene is eventually identified. In addition, two new genes have been identified as causing OCA when mutated: SLC24A5 and C10orf11, and hence designated as OCA6 and OCA7, respectively. This consensus review, involving all laboratories that have reported these new genes, aims to update and agree upon the current gene nomenclature and types of albinism, while providing additional insights from the function of these new genes in pigment cells.
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Affiliation(s)
- Lluís Montoliu
- Department of Molecular and Cellular Biology, National Centre for Biotechnology (CNB-CSIC), Campus de Cantoblanco, Madrid, Spain; CIBERER, ISCIII, Madrid, Spain
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Reduced glutathione disrupts the intracellular trafficking of tyrosinase and tyrosinase-related protein-1 but not dopachrome tautomerase and Pmel17 to melanosomes, which results in the attenuation of melanization. Arch Dermatol Res 2013; 306:37-49. [PMID: 23764898 DOI: 10.1007/s00403-013-1376-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 06/03/2013] [Indexed: 01/05/2023]
Abstract
We previously reported that treatment of B16 melanotic melanoma cells with reduced glutathione (GSH) converts them to amelanotic cells without any significant down-regulation of tyrosinase activity. To characterize the cellular mechanism(s) involved, we determined the intracellular distribution of melanocyte-specific proteins, especially in melanin synthesis-specific organelles, termed melanosomes by subcellular fractionation followed by Western blotting and confocal laser microscopy (CFLM). In the melanosome-rich large granule fraction and in highly purified melanosome fractions, while GSH-induced amelanotic B16 cells have significantly diminished levels of protein/activity of tyrosinase and tyrosinase-related protein-1 compared with control melanized B16 cells, there was substantially no difference in the distribution and levels of dopachrome tautomerase and the processed isoform of Pmel17 (HMB45) between control melanized and GSH-induced amelanotic B16 cells. Analysis of merged images obtained by CFLM revealed that whereas tyrosinase, Pmel17 and dopachrome tautomerase colocalize with each other in the control melanized B16 cells, tyrosinase does not colocalize with Pmel17 or its processed isoform and with dopachrome tautomerase in GSH-induced amelanotic B16 cells. The sum of these findings suggests that reduced glutathione selectively disrupts the intracellular trafficking of tyrosinase and tyrosinase-related protein-1 but not dopachrome tautomerase and Pmel17 to melanosomes, which results in the attenuation of melanization, probably serving as a putative model for oculocutaneous albinism type 4.
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Fan R, Xie J, Bai J, Wang H, Tian X, Bai R, Jia X, Yang L, Song Y, Herrid M, Gao W, He X, Yao J, Smith GW, Dong C. Skin transcriptome profiles associated with coat color in sheep. BMC Genomics 2013; 14:389. [PMID: 23758853 PMCID: PMC3689618 DOI: 10.1186/1471-2164-14-389] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 06/04/2013] [Indexed: 01/06/2023] Open
Abstract
Background Previous molecular genetic studies of physiology and pigmentation of sheep skin have focused primarily on a limited number of genes and proteins. To identify additional genes that may play important roles in coat color regulation, Illumina sequencing technology was used to catalog global gene expression profiles in skin of sheep with white versus black coat color. Results There were 90,006 and 74,533 unigenes assembled from the reads obtained from white and black sheep skin, respectively. Genes encoding for the ribosomal proteins and keratin associated proteins were most highly expressed. A total of 2,235 known genes were differentially expressed in black versus white sheep skin, with 479 genes up-regulated and 1,756 genes down-regulated. A total of 845 novel genes were differentially expressed in black versus white sheep skin, consisting of 107 genes which were up-regulated (including 2 highly expressed genes exclusively expressed in black sheep skin) and 738 genes that were down-regulated. There was also a total of 49 known coat color genes expressed in sheep skin, from which 13 genes showed higher expression in black sheep skin. Many of these up-regulated genes, such as DCT, MATP, TYR and TYRP1, are members of the components of melanosomes and their precursor ontology category. Conclusion The white and black sheep skin transcriptome profiles obtained provide a valuable resource for future research to understand the network of gene expression controlling skin physiology and melanogenesis in sheep.
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Affiliation(s)
- Ruiwen Fan
- College of Animal Science and Veterinary Medicine, Shanxi Agricultural University, Taigu 030801, China
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Ho H, Ganesan AK. The pleiotropic roles of autophagy regulators in melanogenesis. Pigment Cell Melanoma Res 2011; 24:595-604. [PMID: 21777401 DOI: 10.1111/j.1755-148x.2011.00889.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Melanin pigments protect the skin and eyes from toxic insults and are critical for the normal functioning of multiple organ systems including the skin, eyes, and brain. Biochemical and genetic studies in both human and mice have revealed the molecular machinery controlling the transcription of genes encoding enzymes that produce melanin and the trafficking of these enzymes to the melanosome, a lysosome-related organelle dedicated to melanin synthesis. Recent functional genomic studies have identified a role for genes previously known to regulate autophagy, a cellular process that facilitates nutrient recycling during starvation, in the biogenesis of melanosomes in vitro and in vivo. In this review, we describe the pleiotropic roles of autophagy regulators in multiple vesicle trafficking processes, define a specific role for autophagy regulators in melanosome biogenesis, and shed light on how autophagy and autophagy regulators may play different roles in both the biogenesis of melanosomes and melanosome destruction.
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Affiliation(s)
- Hsiang Ho
- Department of Dermatology and Biological Chemistry, University of California, Irvine, CA, USA
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Chiang PW, Spector E, Thomas M, Frei-Jones M. Novel mutation causing Hermansky-Pudlak Syndrome Type 2. Pediatr Blood Cancer 2010; 55:1438. [PMID: 20981699 DOI: 10.1002/pbc.22793] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Serrant MT, Ramirez SI, Cadilla CL, Ramos-Valencia G, Santiago-Borrero PJ. Newborn screening for hermansky-pudlak syndrome type 3 in Puerto Rico. J Pediatr Hematol Oncol 2010; 32:448-53. [PMID: 20562649 PMCID: PMC3640623 DOI: 10.1097/mph.0b013e3181e5e1f1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder characterized by albinism, mucocutaneous bleeding, and storage of ceroid material in macrophages. Patients who are not easily identified by physical characteristics (mostly HPS-3 patients) may have hemorrhagic complications with trauma or surgery. OBJECTIVE To determine the prevalence of HPS-3 in Puerto Rican newborns using DNA pooling technique. DESIGN/METHODS Twelve percent of annual Puerto Rican births were tested randomly by polymerase chain reaction for the HPS-3 mutation, using pooled DNA extracted from dried blood samples. RESULTS HPS-3 mutation was detected in 75 samples. Two newborns were found to be homozygous. Carrier frequency was 1:85 (1.18%). CONCLUSIONS The HPS-3 carrier frequency found (1.18%) justifies universal newborn screening in Puerto Rico. DNA pooling reduces time and labor in newborn screening thus facilitating early diagnosis and treatment of children with HPS-3 and the provision of genetic counseling to parents and relatives.
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Affiliation(s)
- Maribel Torres Serrant
- Department of Pediatrics Hematology/Oncology Section University of Puerto Rico School of Medicine
| | - Sonia I Ramirez
- Department of Pediatrics University of PR School of Medicine
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de Saint Basile G, Ménasché G, Fischer A. Molecular mechanisms of biogenesis and exocytosis of cytotoxic granules. Nat Rev Immunol 2010; 10:568-79. [PMID: 20634814 DOI: 10.1038/nri2803] [Citation(s) in RCA: 303] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cytotoxic T cells and natural killer cells are crucial for immune surveillance against virus-infected cells and tumour cells. Molecular studies of individuals with inherited defects that impair lymphocyte cytotoxic function have also highlighted the importance of cytotoxicity in the regulation and termination of immune responses. As discussed in this Review, characterization of these defects has contributed to our understanding of the key steps that are required for the maturation of cytotoxic granules and the secretion of their contents at the immunological synapse during target cell killing. This has revealed a marked similarity between cytotoxic granule exocytosis at the immunological synapse and synaptic vesicle exocytosis at the neurological synapse. We explore the possibility that comparison of these two kinetically and spatially regulated secretory pathways will provide clues to uncover additional effectors that regulate the cytotoxic function of lymphocytes.
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Affiliation(s)
- Geneviève de Saint Basile
- Institut National de la Santé et de la Recherche Médicale (INSERM), U768, Hôpital Necker Enfants Malades, 149 rue de Sèvres, 75015 Paris, France.
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Hammel I, Lagunoff D, Galli SJ. Regulation of secretory granule size by the precise generation and fusion of unit granules. J Cell Mol Med 2010; 14:1904-16. [PMID: 20406331 PMCID: PMC2909340 DOI: 10.1111/j.1582-4934.2010.01071.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Accepted: 04/08/2010] [Indexed: 12/31/2022] Open
Abstract
Morphometric evidence derived from studies of mast cells, pancreatic acinar cells and other cell types supports a model in which the post-Golgi processes that generate mature secretory granules can be resolved into three steps: (1) fusion of small, Golgi-derived progranules to produce immature secretory granules which have a highly constrained volume; (2) transformation of such immature granules into mature secretory granules, a process often associated with a reduction in the maturing granule's volume, as well as changes in the appearance of its content and (3) fusion of secretory granules of the smallest size, termed 'unit granules', forming granules whose volumes are multiples of the unit granule's volume. Mutations which perturb this process can cause significant pathology. For example, Chediak-Higashi syndrome / lysosomal trafficking regulator (CHS)/(Lyst) mutations result in giant secretory granules in a number of cell types in human beings with the Chediak-Higashi syndrome and in 'beige' (Lyst(bg)/Lyst(bg)) mice. Analysis of the secretory granules of mast cells and pancreatic acinar cells in Lyst-deficient beige mice suggests that beige mouse secretory granules retain the ability to fuse randomly with other secretory granules no matter what the size of the fusion partners. By contrast, in normal mice, the pattern of granule-granule fusion occurs exclusively by the addition of unit granules, either to each other or to larger granules. The normal pattern of fusion is termed unit addition and the fusion evident in cells with CHS/Lyst mutations is called random addition. The proposed model of secretory granule formation has several implications. For example, in neurosecretory cells, the secretion of small amounts of cargo in granules constrained to a very narrow size increases the precision of the information conveyed by secretion. By contrast, in pancreatic acinar cells and mast cells, large granules composed of multiple unit granules permit the cells to store large amounts of material without requiring the amount of membrane necessary to package the same amount of cargo into small granules. In addition, the formation of mature secretory granules that are multimers of unit granules provides a mechanism for mixing in large granules the contents of unit granules which differ in their content of cargo.
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Affiliation(s)
- Ilan Hammel
- Department of Pathology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
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Mariño G, Fernández AF, Cabrera S, Lundberg YW, Cabanillas R, Rodríguez F, Salvador-Montoliu N, Vega JA, Germanà A, Fueyo A, Freije JMP, López-Otín C. Autophagy is essential for mouse sense of balance. J Clin Invest 2010; 120:2331-44. [PMID: 20577052 DOI: 10.1172/jci42601] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Accepted: 05/05/2010] [Indexed: 01/26/2023] Open
Abstract
Autophagy is an evolutionarily conserved process that is essential for cellular homeostasis and organismal viability in eukaryotes. However, the extent of its functions in higher-order processes of organismal physiology and behavior is still unknown. Here, we report that autophagy is essential for the maintenance of balance in mice and that its deficiency leads to severe balance disorders. We generated mice deficient in autophagin-1 protease (Atg4b) and showed that they had substantial systemic reduction of autophagic activity. Autophagy reduction occurred through defective proteolytic processing of the autophagosome component LC3 and its paralogs, which compromised the rate of autophagosome maturation. Despite their viability, Atg4b-null mice showed unusual patterns of behavior that are common features of inner ear pathologies. Consistent with this, Atg4b-null mice showed defects in the development of otoconia, organic calcium carbonate crystals essential for sense of balance (equilibrioception). Furthermore, these abnormalities were exacerbated in Atg5-/- mice, which completely lack the ability to perform autophagy, confirming that autophagic activity is necessary for otoconial biogenesis. Autophagy deficiency also led to impaired secretion and assembly of otoconial core proteins, thus hampering otoconial development. Taken together, these results describe an essential role for autophagy in inner ear development and equilibrioception and open new possibilities for understanding and treating human balance disorders, which are of growing relevance among the elderly population.
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Affiliation(s)
- Guillermo Mariño
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Instituto Universitario de Oncología, Universidad de Oviedo, 33006 Oviedo, Spain
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Disruption of AP1S1, causing a novel neurocutaneous syndrome, perturbs development of the skin and spinal cord. PLoS Genet 2008; 4:e1000296. [PMID: 19057675 PMCID: PMC2585812 DOI: 10.1371/journal.pgen.1000296] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Accepted: 11/04/2008] [Indexed: 12/19/2022] Open
Abstract
Adaptor protein (AP) complexes regulate clathrin-coated vesicle assembly, protein cargo sorting, and vesicular trafficking between organelles in eukaryotic cells. Because disruption of the various subunits of the AP complexes is embryonic lethal in the majority of cases, characterization of their function in vivo is still lacking. Here, we describe the first mutation in the human AP1S1 gene, encoding the small subunit σ1A of the AP-1 complex. This founder splice mutation, which leads to a premature stop codon, was found in four families with a unique syndrome characterized by mental retardation, enteropathy, deafness, peripheral neuropathy, ichthyosis, and keratodermia (MEDNIK). To validate the pathogenic effect of the mutation, we knocked down Ap1s1 expression in zebrafish using selective antisens morpholino oligonucleotides (AMO). The knockdown phenotype consisted of perturbation in skin formation, reduced pigmentation, and severe motility deficits due to impaired neural network development. Both neural and skin defects were rescued by co-injection of AMO with wild-type (WT) human AP1S1 mRNA, but not by co-injecting the truncated form of AP1S1, consistent with a loss-of-function effect of this mutation. Together, these results confirm AP1S1 as the gene responsible for MEDNIK syndrome and demonstrate a critical role of AP1S1 in development of the skin and spinal cord. We describe a novel genetic syndrome that we named MEDNIK, to designate a disease characterized by mental retardation, enteropathy, deafness, peripheral neuropathy, ichthyosis and keratodermia. This syndrome was found in four French-Canadian families with a common ancestor and is caused by a mutation in the AP1S1 gene. This gene encodes a subunit (σ1A) of an adaptor protein complex (AP-1) involved in the organisation and transport of many other proteins within the cell. By using rapidly developing zebrafish embryos as a model, we observed that the loss of this gene resulted in broad defects, including skin malformation and severe motor deficits due to impairment of spinal cord development. By expressing the human AP1S1 gene instead of the zebrafish ap1s1 gene, we found that the normal human AP1S1 gene could rescue these developmental deficits but not the human AP1S1 gene bearing the disease-related mutation. Together, our results confirm AP1S1 as the gene responsible for MEDNIK syndrome and demonstrate a critical role of AP1S1 in the development of the skin and the spinal cord.
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25
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Huizing M, Helip-Wooley A, Westbroek W, Gunay-Aygun M, Gahl WA. Disorders of lysosome-related organelle biogenesis: clinical and molecular genetics. Annu Rev Genomics Hum Genet 2008; 9:359-86. [PMID: 18544035 DOI: 10.1146/annurev.genom.9.081307.164303] [Citation(s) in RCA: 274] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Lysosome-related organelles (LROs) are a heterogeneous group of vesicles that share various features with lysosomes, but are distinct in function, morphology, and composition. The biogenesis of LROs employs a common machinery, and genetic defects in this machinery can affect all LROs or only an individual LRO, resulting in a variety of clinical features. In this review, we discuss the main components of LRO biogenesis. We also summarize the function, composition, and resident cell types of the major LROs. Finally, we describe the clinical characteristics of the major human LRO disorders.
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Affiliation(s)
- Marjan Huizing
- Cell Biology of Metabolic Disorders Unit, National Institutes of Health, Bethesda, Maryland 20892, USA.
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26
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glo-3, a novel Caenorhabditis elegans gene, is required for lysosome-related organelle biogenesis. Genetics 2008; 180:857-71. [PMID: 18780725 DOI: 10.1534/genetics.108.093534] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Gut granules are specialized lysosome-related organelles that act as sites of fat storage in Caenorhabditis elegans intestinal cells. We identified mutations in a gene, glo-3, that functions in the formation of embryonic gut granules. Some glo-3(-) alleles displayed a complete loss of embryonic gut granules, while other glo-3(-) alleles had reduced numbers of gut granules. A subset of glo-3 alleles led to mislocalization of gut granule contents into the intestinal lumen, consistent with a defect in intracellular trafficking. glo-3(-) embryos lacking gut granules developed into adults containing gut granules, indicating that glo-3(+) function may be differentially required during development. We find that glo-3(+) acts in parallel with or downstream of the AP-3 complex and the PGP-2 ABC transporter in gut granule biogenesis. glo-3 encodes a predicted membrane-associated protein that lacks obvious sequence homologs outside of nematodes. glo-3 expression initiates in embryonic intestinal precursors and persists almost exclusively in intestinal cells through adulthood. GLO-3GFP localizes to the gut granule membrane, suggesting it could play a direct role in the trafficking events at the gut granule. smg-1(-) suppression of glo-3(-) nonsense alleles indicates that the C-terminal half of GLO-3, predicted to be present in the cytoplasm, is not necessary for gut granule formation. Our studies identify GLO-3 as a novel player in the formation of lysosome-related organelles.
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Brooks BP, Larson DM, Chan CC, Kjellstrom S, Smith RS, Crawford MA, Lamoreux L, Huizing M, Hess R, Jiao X, Hejtmancik JF, Maminishkis A, John SWM, Bush R, Pavan WJ. Analysis of ocular hypopigmentation in Rab38cht/cht mice. Invest Ophthalmol Vis Sci 2007; 48:3905-13. [PMID: 17724166 PMCID: PMC1989767 DOI: 10.1167/iovs.06-1464] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To characterize the ocular phenotype resulting from mutation of Rab38, a candidate gene for Hermansky-Pudlak syndrome. METHODS Chocolate mice (cht, Rab38(cht/cht)) and control heterozygous (Rab38(cht/)(+)) and wild-type mice were examined clinically, histologically, ultrastructurally, and electrophysiologically. Mice homozygous for both the Rab38(cht) and the Tyrp1(b) alleles were similarly examined. RESULTS Rab38(cht/cht) mice showed variable peripheral iris transillumination defects at 2 months of age. Patches of RPE hypopigmentation were noted clinically in 57% of Rab38(cht/cht) eyes and 6% of Rab38(cht/)(+) eyes. Rab38(cht/cht) mice exhibited thinning of the iris and RPE and larger b-wave amplitudes in the scotopic range when compared with the control animals. Compared with wild-type mice, Rab38(cht/cht) melanosomes were smaller and there were fewer in neuroectodermally derived retinal pigment epithelium; in neural crest-derived choroid melanocytes, they were smaller in size only. Mutation of both Rab38 and Tyrp1 produced mice with ocular and coat color pigment dilution greater than that seen with either mutation alone. Comprehensive clinical and pathologic analyses showed no other organ system or blood defects in Rab38(cht/cht) mice. CONCLUSIONS Rab38(cht/cht) mice show ocular characteristics reminiscent of human oculocutaneous albinism, as well as iris and RPE thinning. The synergistic effects of the Rab38(cht) and Tyrp1(b) alleles suggest that TYRP1 is not the only target of RAB38 trafficking. This mouse line provides a useful model for studying melanosome biology and its role in human ocular diseases.
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Affiliation(s)
- Brian P Brooks
- National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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Baxter LL, Hsu BJ, Umayam L, Wolfsberg TG, Larson DM, Frith MC, Kawai J, Hayashizaki Y, Carninci P, Pavan WJ. Informatic and genomic analysis of melanocyte cDNA libraries as a resource for the study of melanocyte development and function. ACTA ACUST UNITED AC 2007; 20:201-9. [PMID: 17516927 DOI: 10.1111/j.1600-0749.2007.00372.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
As part of the RIKEN mouse encyclopedia project, two cDNA libraries were prepared from melanocyte-derived cell lines, using techniques of full-length clone selection and subtraction/normalization to enrich for rare transcripts. End sequencing showed that these libraries display over 83% complete coding sequence at the 5' end and 96-97% complete coding sequence at the 3' end. Evaluation of the libraries, derived from B16F10Y tumor cells and melan-c cells, revealed that they contain clones for a majority of the genes previously demonstrated to function in melanocyte biology. Analysis of genomic locations for transcripts revealed that the distribution of melanocyte genes is non-random throughout the genome. Three genomic regions identified that showed significant clustering of melanocyte-expressed genes contain one or more genes previously shown to regulate melanocyte development or function. A catalog of genes expressed in these libraries is presented, providing a valuable resource of cDNA clones and sequence information that can be used for identification of new genes important for melanocyte development, function, and disease.
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Affiliation(s)
- Laura L Baxter
- Genetic Disease Research Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20855, USA
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Syrzycka M, McEachern LA, Kinneard J, Prabhu K, Fitzpatrick K, Schulze S, Rawls JM, Lloyd VK, Sinclair DAR, Honda BM. Thepinkgene encodes theDrosophilaorthologue of the human Hermansky–Pudlak syndrome 5 (HPS5) gene. Genome 2007; 50:548-56. [PMID: 17632576 DOI: 10.1139/g07-032] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hermansky–Pudlak syndrome (HPS) consists of a set of human autosomal recessive disorders, with symptoms resulting from defects in genes required for protein trafficking in lysosome-related organelles such as melanosomes and platelet dense granules. A number of human HPS genes and rodent orthologues have been identified whose protein products are key components of 1 of 4 different protein complexes (AP-3 or BLOC-1, -2, and -3) that are key participants in the process. Drosophila melanogaster has been a key model organism in demonstrating the in vivo significance of many genes involved in protein trafficking pathways; for example, mutations in the “granule group” genes lead to changes in eye colour arising from improper protein trafficking to pigment granules in the developing eye. An examination of the chromosomal positioning of Drosophila HPS gene orthologues suggested that CG9770, the Drosophila HPS5 orthologue, might correspond to the pink locus. Here we confirm this gene assignment, making pink the first eye colour gene in flies to be identified as a BLOC complex gene.
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Affiliation(s)
- Monika Syrzycka
- Simon Fraser University, Department of Molecular Biology and Biochemistry, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
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30
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Huizing M, Parkes JM, Helip-Wooley A, White JG, Gahl WA. Platelet alpha granules in BLOC-2 and BLOC-3 subtypes of Hermansky-Pudlak syndrome. Platelets 2007; 18:150-7. [PMID: 17365864 DOI: 10.1080/13576500600936039] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Hermansky-Pudlak syndrome (HPS) is a disorder of lysosome-related organelle biogenesis that displays genetic locus heterogeneity. The eight known HPS proteins combine in functional complexes, two of which are called BLOC-2 and BLOC-3; a BLOC is a Biogenesis of Lysosome-related Organelles Complex. Organelles affected in HPS include the melanosome, resulting in hypopigmentation, and the platelet delta (dense) granule, resulting in prolonged bleeding times. Whole mount electron microscopy (EM) detects the absence of platelet delta granules and confirms the diagnosis of HPS. To date, the status of other organelles and granules in HPS platelets has not been documented. We performed ultrastructural studies on platelets of patients with different genetic forms of HPS, specifically those comprising the BLOC-2 and BLOC-3 subtypes. No differences in distribution, size or quantity of other platelet organelles and membrane structures could be detected in our patients. Since alpha and delta granules are formed from multivesicular bodies in the megakaryocyte, and since only delta granules are defective in HPS, we conclude that HPS genes function within the portion of delta granule biogenesis that has diverged from that of alpha granules. Thus, it is unlikely that the generalized bleeding diathesis of HPS is attributed to a deficiency of alpha granules.
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Affiliation(s)
- Marjan Huizing
- National Human Genome Research Institute, National Institutes of Health, Section on Human Biochemical Genetics, Medical Genetics Branch, Bethesda, MD 20892-1851, USA.
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31
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Freimoser FM, Hürlimann HC, Jakob CA, Werner TP, Amrhein N. Systematic screening of polyphosphate (poly P) levels in yeast mutant cells reveals strong interdependence with primary metabolism. Genome Biol 2007; 7:R109. [PMID: 17107617 PMCID: PMC1794592 DOI: 10.1186/gb-2006-7-11-r109] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2006] [Revised: 10/04/2006] [Accepted: 11/15/2006] [Indexed: 11/30/2022] Open
Abstract
A systematic analysis of polyphosphate levels in yeast knockout strains for almost every non-essential gene identified 255 genes involved in the maintenance of normal polyphosphate content and provides insights into phosphate homeostasis. Background Inorganic polyphosphate (poly P) occurs universally in all organisms from bacteria to man. It functions, for example, as a phosphate and energy store, and is involved in the activation and regulation of proteins. Despite its ubiquitous occurrence and important functions, it is unclear how poly P is synthesized or how poly P metabolism is regulated in higher eukaryotes. This work describes a systematic analysis of poly P levels in yeast knockout strains mutated in almost every non-essential gene. Results After three consecutive screens, 255 genes (almost 4% of the yeast genome) were found to be involved in the maintenance of normal poly P content. Many of these genes encoded proteins functioning in the cytoplasm, the vacuole or in transport and transcription. Besides reduced poly P content, many strains also exhibited reduced total phosphate content, showed altered ATP and glycogen levels and were disturbed in the secretion of acid phosphatase. Conclusion Cellular energy and phosphate homeostasis is suggested to result from the equilibrium between poly P, ATP and free phosphate within the cell. Poly P serves as a buffer for both ATP and free phosphate levels and is, therefore, the least essential and consequently most variable component in this network. However, strains with reduced poly P levels are not only affected in their ATP and phosphate content, but also in other components that depend on ATP or free phosphate content, such as glycogen or secreted phosphatase activity.
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Affiliation(s)
| | | | - Claude A Jakob
- Institute of Microbiology, ETH Zurich, Zurich, Switzerland
| | - Thomas P Werner
- Institute of Plant Sciences, ETH Zurich, 8092 Zurich, Switzerland
| | - Nikolaus Amrhein
- Institute of Plant Sciences, ETH Zurich, 8092 Zurich, Switzerland
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Helip-Wooley A, Westbroek W, Dorward HM, Koshoffer A, Huizing M, Boissy RE, Gahl WA. Improper trafficking of melanocyte-specific proteins in Hermansky-Pudlak syndrome type-5. J Invest Dermatol 2007; 127:1471-8. [PMID: 17301833 PMCID: PMC8369813 DOI: 10.1038/sj.jid.5700737] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Hermansky-Pudlak syndrome (HPS) is a disorder of lysosome-related organelle biogenesis resulting in melanosome dysfunction and absent platelet dense bodies. HPS patients have oculocutaneous albinism, bruising, and bleeding. HPS-5 results from deficiency of the HPS5 protein, a component of the biogenesis of lysosome-related organelles complex-2 (BLOC-2). HPS5 has an unknown function and lacks homology to known proteins. We performed ultrastructural studies of HPS-5 melanocytes revealing predominantly early-stage melanosomes with many small 3,4(OH)2-phenylalanine-positive vesicles throughout the cell body and dendrites. These findings resemble the distinct ultrastructural features of HPS-3 melanocytes; HPS3 is also a BLOC-2 component. Immunofluorescence and immunoEM studies showed decreased TYRP1 labeling in the dendrites of HPS-5 melanocytes, and the overall abundance of TYRP1 was reduced. No substantial differences were observed in the distribution or abundance of Pmel17 in HPS-5 melanocytes. In normal melanocytes, endogenous tyrosinase colocalized with Pmel17 and TYRP1 in the perinuclear area and dendritic tips; this was much reduced in HPS-5 melanocytes, particularly in the tips. We conclude that early stage melanosome formation and Pmel17 trafficking are preserved in HPS5-deficient cells. Tyrosinase and TYRP1 are mistrafficked, however, and fail to be efficiently delivered to melanosomes of HPS-5 melanocytes.
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Affiliation(s)
- Amanda Helip-Wooley
- Section on Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, Maryland 20892-1851, USA.
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Schroeder LK, Kremer S, Kramer MJ, Currie E, Kwan E, Watts JL, Lawrenson AL, Hermann GJ. Function of the Caenorhabditis elegans ABC transporter PGP-2 in the biogenesis of a lysosome-related fat storage organelle. Mol Biol Cell 2007; 18:995-1008. [PMID: 17202409 PMCID: PMC1805080 DOI: 10.1091/mbc.e06-08-0685] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Caenorhabditis elegans gut granules are intestine specific lysosome-related organelles with birefringent and autofluorescent contents. We identified pgp-2, which encodes an ABC transporter, in screens for genes required for the proper formation of gut granules. pgp-2(-) embryos mislocalize birefringent material into the intestinal lumen and are lacking in acidified intestinal V-ATPase-containing compartments. Adults without pgp-2(+) function similarly lack organelles with gut granule characteristics. These cellular phenotypes indicate that pgp-2(-) animals are defective in gut granule biogenesis. Double mutant analysis suggests that pgp-2(+) functions in parallel with the AP-3 adaptor complex during gut granule formation. We find that pgp-2 is expressed in the intestine where it functions in gut granule biogenesis and that PGP-2 localizes to the gut granule membrane. These results support a direct role of an ABC transporter in regulating lysosome biogenesis. Previously, pgp-2(+) activity has been shown to be necessary for the accumulation of Nile Red-stained fat in C. elegans. We show that gut granules are sites of fat storage in C. elegans embryos and adults. Notably, levels of triacylglycerides are relatively normal in animals defective in the formation of gut granules. Our results provide an explanation for the loss of Nile Red-stained fat in pgp-2(-) animals as well as insight into the specialized function of this lysosome-related organelle.
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Affiliation(s)
| | - Susan Kremer
- Program in Biochemistry and Molecular Biology, Lewis and Clark College, Portland, OR 97219; and
| | - Maxwell J. Kramer
- Program in Biochemistry and Molecular Biology, Lewis and Clark College, Portland, OR 97219; and
| | - Erin Currie
- *Department of Biology and
- Program in Biochemistry and Molecular Biology, Lewis and Clark College, Portland, OR 97219; and
| | - Elizabeth Kwan
- Program in Biochemistry and Molecular Biology, Lewis and Clark College, Portland, OR 97219; and
| | - Jennifer L. Watts
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164
| | | | - Greg J. Hermann
- *Department of Biology and
- Program in Biochemistry and Molecular Biology, Lewis and Clark College, Portland, OR 97219; and
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Lettau M, Schmidt H, Kabelitz D, Janssen O. Secretory lysosomes and their cargo in T and NK cells. Immunol Lett 2006; 108:10-9. [PMID: 17097742 DOI: 10.1016/j.imlet.2006.10.001] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2006] [Accepted: 10/10/2006] [Indexed: 11/22/2022]
Abstract
Secretory lysosomes are specialized organelles that combine catabolic functions of conventional lysosomes with an inducible secretory potential. They are present in various hematopoietic cell types commonly characterized by the need for rapid mobilization and secretion of effector proteins. As an example, the cytotoxic effector function of T cells and natural killer cells strictly depends on the activation-dependent mobilization of such vesicles to the cytotoxic immunological synapse. This review focuses on some molecules that have been identified as cargo of secretory lysosomes and which play a major role in effector function of CTL and NK cells. We also briefly point to the fact that the dysregulation of formation and transport of secretory vesicles is causative for severe immunodeficiencies and autoimmunity observed in patients and also in mice that have been used as representative model systems to analyze the pathophysiological relevance of secretory vesicles in vivo.
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Affiliation(s)
- Marcus Lettau
- Institute of Immunology, Medical Center Schleswig-Holstein Campus Kiel, Michaelisstr. 5, D-24105 Kiel, Germany
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35
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Horwitz MS, Duan Z, Korkmaz B, Lee HH, Mealiffe ME, Salipante SJ. Neutrophil elastase in cyclic and severe congenital neutropenia. Blood 2006; 109:1817-24. [PMID: 17053055 PMCID: PMC1801070 DOI: 10.1182/blood-2006-08-019166] [Citation(s) in RCA: 197] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Mutations in ELA2 encoding the neutrophil granule protease, neutrophil elastase (NE), are the major cause of the 2 main forms of hereditary neutropenia, cyclic neutropenia and severe congenital neutropenia (SCN). Genetic evaluation of other forms of neutropenia in humans and model organisms has helped to illuminate the role of NE. A canine form of cyclic neutropenia corresponds to human Hermansky-Pudlak syndrome type 2 (HPS2) and results from mutations in AP3B1 encoding a subunit of a complex involved in the subcellular trafficking of vesicular cargo proteins (among which NE appears to be one). Rare cases of SCN are attributable to mutations in the transcriptional repressor Gfi1 (among whose regulatory targets also include ELA2). The ultimate biochemical consequences of the mutations are not yet known, however. Gene targeting of ELA2 has thus far failed to recapitulate neutropenia in mice. The cycling phenomenon and origins of leukemic transformation in SCN remain puzzling. Nevertheless, mutations in all 3 genes are capable of causing the mislocalization of NE and may also induce the unfolded protein response, suggesting that there might a convergent pathogenic mechanism focusing on NE.
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Affiliation(s)
- Marshall S Horwitz
- Division of Medical Genetics, Department of Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA.
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Song Y, Dayalu R, Matthews SA, Scharenberg AM. TRPML cation channels regulate the specialized lysosomal compartment of vertebrate B-lymphocytes. Eur J Cell Biol 2006; 85:1253-64. [PMID: 17050035 DOI: 10.1016/j.ejcb.2006.08.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2005] [Revised: 08/23/2006] [Accepted: 08/23/2006] [Indexed: 10/24/2022] Open
Abstract
B-lymphocytes possess a specialized lysosomal compartment, the regulated transformation of which has been implicated in B-cell antigen presentation. Members of the mucolipin (TRPML) family of cation channels have been implicated in regulated vesicular transport in several tissues, but a role for TRPML function in lymphocyte vesicular transport physiology has not been previously described. To address the role of TRPML proteins in lymphocyte vesicular transport, we analyzed the lysosomal compartment in cultured B-lymphocytes engineered to lack TRPML1 or after expression of N- or C-terminal GFP fusion proteins of TRPML1 or TRPML2. Consistent with previous analyses of lymphocytes derived from human patients with mutations in TRPML1, we were not able to detect abnormalities in the lysosomes of TRPML1-deficient DT40 B-lymphocytes. However, while N-terminal GFP fusions of TRPML2 localized to normal appearing lysosomes, C-terminal GFP fusions of either TRPML1 or TRPML2 acted to antagonize endogenous TRPML function, localizing to large vesicular structures, the histological properties of which were indistinguishable from the enlarged lysosomes observed in affected tissues of TRPML1-deficient humans. Endocytosed B-cell receptors were delivered to these enlarged lysosomes, demonstrating that a TRPML-dependent process is required for normal regulation of the specialized lysosome compartment of vertebrate B-lymphocytes.
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Affiliation(s)
- Yumei Song
- Department of Pediatrics and Immunology, University of Washington and Children's Hospital and Regional Medical Center, Seattle, WA 98195, USA
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37
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Affiliation(s)
- Hiroshi Ohno
- Laboratory for Epithelial Immunobiology, Research Center for Allergy and Immunology (RCAI), RIKEN, International Graduate School of Arts and Sciences, Yokohama City University, Yokohama, Japan.
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Zhou M, Gradstein L, Gonzales JA, Tsilou ET, Gahl WA, Chan CC. Ocular pathologic features of Hermansky-Pudlak syndrome type 1 in an adult. ACTA ACUST UNITED AC 2006; 124:1048-51. [PMID: 16832032 PMCID: PMC2478744 DOI: 10.1001/archopht.124.7.1048] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Min Zhou
- National Eye Institute, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA
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39
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Ohno H. Physiological Roles of Clathrin Adaptor AP Complexes: Lessons from Mutant Animals. ACTA ACUST UNITED AC 2006; 139:943-8. [PMID: 16788044 DOI: 10.1093/jb/mvj120] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Clathrin-associated adaptor protein (AP) complexes play a key role in the transport of proteins, by regulating the formation of transport vesicles as well as cargo selection, between organelles of the post-Golgi network, namely, the trans-Golgi network (TGN), endosomes, lysosomes and the plasma membrane. Evidence has been accumulating for the physiological importance of AP complexes. Deficiency in AP-1A or AP-2 results in embryonic lethality in mice, indicating that these AP complexes are essential for normal development of embryos in mammals. In contrast, mutations in the genes encoding subunits of AP-3A cause an autosomal recessive disorder, Hermansky-Pudlak syndrome in human and its disease models in mice. Knockout mice for the neuron-specific AP-3B suffer from epileptic seizure. Further studies on the physiological and pathological aspects of AP complexes will not only be beneficial for better understanding of developmental biology and medical sciences, but also deepen our insight into the molecular mechanisms of vesicular traffic.
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Affiliation(s)
- Hiroshi Ohno
- Laboratory for Epithelial Immunobiology, Research Center for Allergy and Immunology (RCAI), RIKEN, Yokohama.
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40
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Hughes I, Thalmann I, Thalmann R, Ornitz DM. Mixing model systems: using zebrafish and mouse inner ear mutants and other organ systems to unravel the mystery of otoconial development. Brain Res 2006; 1091:58-74. [PMID: 16529728 PMCID: PMC2100415 DOI: 10.1016/j.brainres.2006.01.074] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2005] [Revised: 01/16/2006] [Accepted: 01/19/2006] [Indexed: 12/11/2022]
Abstract
Human vestibular dysfunction is an increasing clinical problem. Degeneration or displacement of otoconia is a significant etiology of age-related balance disorders and Benign Positional Vertigo (BPV). In addition, commonly used antibiotics, such as aminoglycoside antibiotics, can lead to disruption of otoconial structure and function. Despite such clinical significance, relatively little information has been compiled about the development and maintenance of otoconia in humans. Recent studies in model organisms and other mammalian organ systems have revealed some of the proteins and processes required for the normal biomineralization of otoconia and otoliths in the inner ear of vertebrates. Orchestration of extracellular biomineralization requires bringing together ionic and proteinaceous components in time and space. Coordination of these events requires the normal formation of the otocyst and sensory maculae, specific secretion and localization of extracellular matrix proteins, as well as tight regulation of the endolymph ionic environment. Disruption of any of these processes can lead to the formation of abnormally shaped, or ectopic, otoconia, or otoconial agenesis. We propose that normal generation of otoconia requires a complex temporal and spatial control of developmental and biochemical events. In this review, we suggest a new hypothetical model for normal otoconial and otolith formation based on matrix vesicle mineralization in bone which we believe to be supported by information from existing mutants, morphants, and biochemical studies.
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Affiliation(s)
- Inna Hughes
- Department of Molecular Biology and Pharmacology, Rm. 3902 South Building (Campus Box 8103), Washington University in St. Louis, School of Medicine, 660 S. Euclid Ave, St. Louis, MO 63110, USA
| | - Isolde Thalmann
- Department of Otolaryngology, Washington University in St. Louis, School of Medicine, St. Louis, MO 63110, USA
| | - Ruediger Thalmann
- Department of Otolaryngology, Washington University in St. Louis, School of Medicine, St. Louis, MO 63110, USA
| | - David M. Ornitz
- Department of Molecular Biology and Pharmacology, Rm. 3902 South Building (Campus Box 8103), Washington University in St. Louis, School of Medicine, 660 S. Euclid Ave, St. Louis, MO 63110, USA
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Abstract
Skin pigmentation is accomplished by production of melanin in specialized membrane-bound organelles termed melanosomes and by transfer of these organelles from melanocytes to surrounding keratinocytes. The mechanism by which these cells transfer melanin is yet unknown. A central role has been established for the protease-activated receptor-2 of the keratinocyte which effectuates melanin transfer via phagocytosis. What exactly is being phagocytosed - naked melanin, melanosomes or melanocytic cell parts - remains to be defined. Analogy of melanocytes to neuronal cells and cells of the haemopoietic lineage suggests exocytosis of melanosomes and subsequent phagocytosis of naked melanin. Otherwise, microscopy studies demonstrate cytophagocytosis of melanocytic dendrites. Other plausible mechanisms are transfer via melanosome-containing vesicles shed by the melanocyte or transfer via fusion of keratinocyte and melanocyte plasma membranes with formation of tunnelling nanotubes. Molecules involved in transfer are being identified. Transfer is influenced by the interactions of lectins and glycoproteins and, probably, by the action of E-cadherin, SNAREs, Rab and Rho GTPases. Further clues as to what mechanism and molecular machinery will arise with the identification of the function of specific genes which are mutated in diseases that affect transfer.
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Grimes P, Nordlund JJ, Pandya AG, Taylor S, Rendon M, Ortonne JP. Increasing our understanding of pigmentary disorders. J Am Acad Dermatol 2006; 54:S255-61. [PMID: 16631966 DOI: 10.1016/j.jaad.2005.12.042] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
This article focuses on developments in pigmentary disorders that extend dermatologists' understanding of the field. Areas that are reviewed include the basic biochemistry, pharmacology, and physiology of the melanocortin system; melanosome development; genetic diseases associated with pigmentary disorders; pigmentary disorders secondary to systemic disease; drug-induced hyperpigmentation; environmental exposure to chemicals; and primary disorders of hyperpigmentation such as melasma and lentigines. Basic, clinical, and epidemiological research, along with a number of clinical case reports, were included in the review. This article also reports on the new health-related quality-of-life instrument (MELASQOL) that has been developed for women with melasma.
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Affiliation(s)
- Pearl Grimes
- Vitiligo & Pigmentation Institute of Southern California, Division of Dermatology, University of California, Los Angeles, CA, USA
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Leung KF, Baron R, Seabra MC. Thematic review series: Lipid Posttranslational Modifications. Geranylgeranylation of Rab GTPases. J Lipid Res 2006; 47:467-75. [PMID: 16401880 DOI: 10.1194/jlr.r500017-jlr200] [Citation(s) in RCA: 188] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Rab GTPases require special machinery for protein prenylation, which include Rab escort protein (REP) and Rab geranylgeranyl transferase (RGGT). The current model of Rab geranylgeranylation proposes that REP binds Rab and presents it to RGGT. After geranylgeranylation of Rab C-terminal cysteines, REP delivers the prenylated protein to membranes. The REP-like protein Rab GDP dissociation inhibitor (RabGDI) then recycles the prenylated Rab between the membrane and the cytosol. The recent solution of crystal structures of the Rab prenylation machinery has helped to refine this model and provided further insights. The hydrophobic prenyl binding pocket of RGGT and geranylgeranyl transferase type-I (GGT-I) differs from that of farnesyl transferase (FT). A bulky tryptophan residue in FT restricts the size of the pocket, whereas in RGGT and GGT-I, this position is occupied by smaller residues. A highly conserved phenylalanine in REP, which is absent in RabGDI, is critical for the formation of the REP:RGGT complex. Finally, a geranylgeranyl binding site conserved in REP and RabGDI has been identified within helical domain II. The postprenylation events, including the specific targeting of Rabs to target membranes and the requirement for single versus double geranylgeranylation by different Rabs, remain obscure and should be the subject of future studies.
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Affiliation(s)
- Ka Fai Leung
- Molecular and Cellular Medicine, Division of Biomedical Sciences, Imperial College London, London SW7 2AZ, UK
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44
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Pierson DM, Ionescu D, Qing G, Yonan AM, Parkinson K, Colby TC, Leslie K. Pulmonary fibrosis in hermansky-pudlak syndrome. a case report and review. Respiration 2006; 73:382-95. [PMID: 16490934 DOI: 10.1159/000091609] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2005] [Accepted: 12/01/2005] [Indexed: 11/19/2022] Open
Abstract
Hermansky-Pudlak syndrome (HPS) is a rare heterogeneously inherited autosomal recessive group of disorders presenting with oculocutaneous albinism, bleeding diathesis and pulmonary disease. HPS is thought to occur as a consequence of disturbed formation or trafficking of intracellular vesicles, most importantly, melanosomes, platelet dense granules and lysosomes. The latter finding, in particular, contributes much to the morbidity associated with the disease, as ceroid lipofuscin deposits in lysosomes affect many organ systems. This is especially problematic in the lungs where it is often associated with pulmonary fibrosis and premature death. Currently, there are 7 known HPS genes in humans. In the mouse, at least 16 known HPS genes produce HPS-mutant phenotypes. The HPS gene mutation is considered to be one of the most prevalent single-gene disorders in northwest Puerto Rico, home to the largest cohort of known patients. In HPS, interventions addressing the bleeding diathesis and pulmonary fibrosis are often disappointingly ineffectual. Pirfenidone, a novel compound with documented anti-inflammatory, antioxidant and antifibrotic effects, appears to hold promise in delaying or preventing fibrosis. To date, there has been one successful lung transplant performed on a patient with HPS. We present a patient with HPS and review the current literature on our understanding of this rare disorder.
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Affiliation(s)
- Diane M Pierson
- Department of Pathology, University of Manitoba, Winnipeg, Canada.
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45
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Hussain N, Quezado M, Huizing M, Geho D, White JG, Gahl W, Mannon P. Intestinal disease in Hermansky-Pudlak syndrome: occurrence of colitis and relation to genotype. Clin Gastroenterol Hepatol 2006; 4:73-80. [PMID: 16431308 DOI: 10.1016/s1542-3565(05)00858-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS Hermansky-Pudlak syndrome (HPS), a rare autosomal recessive disorder characterized by oculocutaneous albinism and platelet dysfunction, results from mutations in 1 of at least 7 different genes. Some patients develop a fatal pulmonary fibrosis and others a disabling colitis. This study aimed to document the occurrence of colitis among HPS patients, characterize gastrointestinal tract involvement in HPS, and analyze the distribution of colitis among HPS genotypes. METHODS Of the 122 HPS patients followed at the National Institutes of Health Clinical Center between 1993 and 2005, 24 were evaluated by endoscopy for gastrointestinal complaints. The histology of gastrointestinal biopsies was retrospectively examined to assess for inflammatory changes, granulomata, and pigmented macrophages. These data were compared with symptoms and HPS genetic subtypes. RESULTS At colonoscopy, 7 of 23 patients (30%) had endoscopic mucosal abnormalities, including nodularity, erythema, petechiae, or erosions. Six of these 7 patients (86%) had findings of colitis on biopsy. Of the 16 patients with normal-appearing colonic mucosa, 2 patients (12%) had colitis on biopsy. Pigmented macrophages were also observed in the colonic lamina propria in 16 of the 23 patients (70%). Of the 8 patients with confirmed colitis, 7 had the HPS-1 subtype, and 1 had the HPS-4 subtype. CONCLUSIONS There is an increased frequency of colitis in our population of 122 HPS patients (8/122, 7%) and in HPS patients referred specifically for symptom evaluation (8/24, 33%). Colitis was found in patients with HPS-1 and HPS-4 genotypes.
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Affiliation(s)
- Nadeem Hussain
- National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-1851, USA
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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.
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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
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47
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Smith JW, Koshoffer A, Morris RE, Boissy RE. Membranous complexes characteristic of melanocytes derived from patients with Hermansky-Pudlak syndrome type 1 are macroautophagosomal entities of the lysosomal compartment. PIGMENT CELL RESEARCH 2005; 18:417-26. [PMID: 16280007 PMCID: PMC1635962 DOI: 10.1111/j.1600-0749.2005.00265.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder resulting from mutations in a family of genes required for efficient transport of lysosomal-related proteins from the trans-Golgi network to a target organelle. To date, there are several genetically distinct forms of HPS. Many forms of HPS exhibit aberrant trafficking of melanosome-targeted proteins resulting in incomplete melanosome biogenesis responsible for oculocutaneous albinism observed in patients. In HPS-1, melanosome-targeted proteins are localized to characteristic membranous complexes, which have morphologic similarities to macroautophagosomes. In this report, we evaluated the hypothesis that HPS-1-specific membranous complexes comprise a component of the lysosomal compartment of melanocytes. Using indirect immunofluorescence, an increase in co-localization of misrouted tyrosinase with cathepsin-L, a lysosomal cysteine protease, occurred in HPS-1 melanocytes. In addition, ribophorin II, an integral endoplasmic reticulum protein that is also a component of macroautophagosomes, and LC3, a specific marker of macrophagosomes, demonstrated localization to membranous complexes in HPS-1 melanocytes. At the electron microscopic level, the membranous complexes exhibited acid phosphatase activity and localization of exogenously supplied horseradish peroxidase (HRP)-conjugated gold particles, indicating incorporation of lysosomal and endosomal components to membranous complexes, respectively. These results confirm that membranous complexes of HPS-1 melanocytes are macroautophagosomal representatives of the lysosomal compartment.
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Affiliation(s)
| | | | - Randal E. Morris
- Cell Biology, Neurobiology & Anatomy, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Raymond E. Boissy
- Department of Dermatology and
- Cell Biology, Neurobiology & Anatomy, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
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48
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Bonifacino JS. Insights into the biogenesis of lysosome-related organelles from the study of the Hermansky-Pudlak syndrome. Ann N Y Acad Sci 2005; 1038:103-14. [PMID: 15838104 DOI: 10.1196/annals.1315.018] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Lysosome-related organelles (LROs) are a family of cell-type-specific organelles that include melanosomes, platelet dense bodies, and cytotoxic T cell granules. The name, LRO, recognizes the fact that all of these organelles contain subsets of lysosomal proteins in addition to cell-type-specific proteins. The recent identification of genetic disorders that cause combined defects in several of these organelles indicates that they share common biogenetic pathways. Studies of one of these disorders, the Hermansky-Pudlak syndrome (HPS), have provided helpful insights into the molecular machinery involved in LRO biogenesis. HPS is a genetically heterogeneous disorder caused by mutations in any of 7 genes in humans and 15 genes in mice. These genes encode subunits of 4 multi-protein complexes named AP-3, BLOC-1, BLOC-2 and BLOC-3, in addition to miscellaneous components of the general protein trafficking machinery. The AP-3 complex is a coat protein involved in vesicle formation and cargo selection in the endosomal-lysosomal system. One of these cargo molecules is the melanosomal enzyme, tyrosinase, the missorting of which may explain the defective melanosomes in AP-3-deficient humans and mice. The function of the BLOC complexes is unknown, although they are thought to mediate either vesicle tethering/fusion or cytoplasmic dispersal of LROs. Further studies of these complexes should contribute to the elucidation of the mechanisms of LRO biogenesis and the pathogenesis of HPS.
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Affiliation(s)
- Juan S Bonifacino
- Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, Building 18T/Room 101, National Institutes of Health, Bethesda, MD 20892, USA.
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49
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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: 60] [Impact Index Per Article: 3.2] [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.
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Affiliation(s)
- Friedrich Beermann
- ISREC, National Center of Competence in Research (NCCR)Molecular Oncology, Chemin des Boveresses 155, 1066 Epalinges, Switzerland.
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50
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Lederer DJ, Kawut SM, Sonett JR, Vakiani E, Seward SL, White JG, Wilt JS, Marboe CC, Gahl WA, Arcasoy SM. Successful Bilateral Lung Transplantation for Pulmonary Fibrosis Associated With the Hermansky-Pudlak Syndrome. J Heart Lung Transplant 2005; 24:1697-9. [PMID: 16210149 DOI: 10.1016/j.healun.2004.11.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2004] [Revised: 10/12/2004] [Accepted: 11/12/2004] [Indexed: 10/25/2022] Open
Abstract
Hermansky-Pudlak syndrome (HPS) is a genetic disorder characterized by oculocutaneous albinism, a bleeding diathesis, and in a subset of patients, pulmonary fibrosis. Lung transplantation, the only curative therapy for pulmonary fibrosis, has not been previously reported as a successful treatment strategy for patients with HPS because the bleeding diathesis was thought to contraindicate major thoracic surgery. We successfully performed bilateral sequential lung transplantation in a patient with pulmonary fibrosis and HPS after transfusion of 6 units of platelets. Lung transplantation is a viable therapeutic option in patients with pulmonary fibrosis and only a mild bleeding diathesis associated with HPS.
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Affiliation(s)
- David J Lederer
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA
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