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Iwanami N, Ozaki Y, Sakaguchi H, Watanabe Y, Meng Q, Matsumoto K, Suzuki T, Hitomi K, Matsuda M. Evolutionarily conserved role of hps1 in melanin production and blood coagulation in medaka fish. G3 GENES|GENOMES|GENETICS 2022; 12:6659099. [PMID: 35944207 PMCID: PMC9526055 DOI: 10.1093/g3journal/jkac204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Accepted: 08/02/2022] [Indexed: 11/16/2022]
Abstract
Hermansky–Pudlak syndrome is an autosomal recessive disease characterized by albinism, visual impairment, and blood platelet dysfunction. One of the genes responsible for Hermansky–Pudlak syndrome, hps1, regulates organelle biogenesis and thus plays important roles in melanin production, blood clotting, and the other organelle-related functions in humans and mice. However, the function of hps1 in other species remains poorly understood. In this study, we discovered albino medaka fish during the maintenance of a wild-derived population and identified hps1 as the responsible gene using positional cloning. In addition to the specific absence of melanophore pigmentation, the hps1 mutant showed reduced blood coagulation, suggesting that hps1 is involved in clotting caused by both mammalian platelets and fish thrombocytes. Together, the findings of our study demonstrate that hps1 has an evolutionarily conserved role in melanin production and blood coagulation. In addition, our study presents a useful vertebrate model for understanding the molecular mechanisms of Hermansky–Pudlak syndrome.
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Affiliation(s)
- Norimasa Iwanami
- Center for Bioscience Research and Education, Utsunomiya University , Utsunomiya 321-8505, Japan
| | - Yuka Ozaki
- Center for Bioscience Research and Education, Utsunomiya University , Utsunomiya 321-8505, Japan
| | - Hiyori Sakaguchi
- Center for Bioscience Research and Education, Utsunomiya University , Utsunomiya 321-8505, Japan
| | - Yuko Watanabe
- Graduate School of Pharmaceutical Sciences, Nagoya University , Nagoya 464-8601, Japan
| | - Qi Meng
- Graduate School of Pharmaceutical Sciences, Nagoya University , Nagoya 464-8601, Japan
| | | | - Tomohiro Suzuki
- Center for Bioscience Research and Education, Utsunomiya University , Utsunomiya 321-8505, Japan
| | - Kiyotaka Hitomi
- Graduate School of Pharmaceutical Sciences, Nagoya University , Nagoya 464-8601, Japan
| | - Masaru Matsuda
- Center for Bioscience Research and Education, Utsunomiya University , Utsunomiya 321-8505, Japan
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Han L, Sun Y, Cao Y, Gao P, Quan Z, Chang Y, Ding J. Analysis of the gene transcription patterns and DNA methylation characteristics of triploid sea cucumbers (Apostichopus japonicus). Sci Rep 2021; 11:7564. [PMID: 33828212 PMCID: PMC8027599 DOI: 10.1038/s41598-021-87278-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 03/26/2021] [Indexed: 02/01/2023] Open
Abstract
Breeding of polyploid aquatic animals is still an important approach and research hotspot for realizing the economic benefits afforded by the improvement of aquatic animal germplasm. To better understand the molecular mechanisms of the growth of triploid sea cucumbers, we performed gene expression and genome-wide comparisons of DNA methylation using the body wall tissue of triploid sea cucumbers using RNA-seq and MethylRAD-seq technologies. We clarified the expression pattern of triploid sea cucumbers and found no dosage effect. DEGs were significantly enriched in the pathways of nucleic acid and protein synthesis, cell growth, cell division, and other pathways. Moreover, we characterized the methylation pattern changes and found 615 differentially methylated genes at CCGG sites and 447 differentially methylated genes at CCWGG sites. Integrative analysis identified 23 genes (such as Guf1, SGT, Col5a1, HAL, HPS1, etc.) that exhibited correlations between promoter methylation and expression. Altered DNA methylation and expression of various genes suggested their roles and potential functional interactions in the growth of triploid sea cucumbers. Our data provide new insights into the epigenetic and transcriptomic alterations of the body wall tissue of triploid sea cucumbers and preliminarily elucidate the molecular mechanism of their growth, which is of great significance for the breeding of fine varieties of sea cucumbers.
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Affiliation(s)
- Lingshu Han
- grid.410631.10000 0001 1867 7333Key Laboratory of Mariculture and Stock Enhancement in North China’s Sea, Ministry of Agriculture and Rural Affairs, Dalian Ocean University, 52 Heishijiao Rd., Dalian, 116023 Liaoning People’s Republic of China ,grid.203507.30000 0000 8950 5267Ningbo University, Ningbo, 315832 Zhejiang People’s Republic of China
| | - Yi Sun
- grid.410631.10000 0001 1867 7333Key Laboratory of Mariculture and Stock Enhancement in North China’s Sea, Ministry of Agriculture and Rural Affairs, Dalian Ocean University, 52 Heishijiao Rd., Dalian, 116023 Liaoning People’s Republic of China
| | - Yue Cao
- grid.410631.10000 0001 1867 7333Key Laboratory of Mariculture and Stock Enhancement in North China’s Sea, Ministry of Agriculture and Rural Affairs, Dalian Ocean University, 52 Heishijiao Rd., Dalian, 116023 Liaoning People’s Republic of China
| | - Pingping Gao
- grid.410631.10000 0001 1867 7333Key Laboratory of Mariculture and Stock Enhancement in North China’s Sea, Ministry of Agriculture and Rural Affairs, Dalian Ocean University, 52 Heishijiao Rd., Dalian, 116023 Liaoning People’s Republic of China
| | - Zijiao Quan
- grid.410631.10000 0001 1867 7333Key Laboratory of Mariculture and Stock Enhancement in North China’s Sea, Ministry of Agriculture and Rural Affairs, Dalian Ocean University, 52 Heishijiao Rd., Dalian, 116023 Liaoning People’s Republic of China
| | - Yaqing Chang
- grid.410631.10000 0001 1867 7333Key Laboratory of Mariculture and Stock Enhancement in North China’s Sea, Ministry of Agriculture and Rural Affairs, Dalian Ocean University, 52 Heishijiao Rd., Dalian, 116023 Liaoning People’s Republic of China
| | - Jun Ding
- grid.410631.10000 0001 1867 7333Key Laboratory of Mariculture and Stock Enhancement in North China’s Sea, Ministry of Agriculture and Rural Affairs, Dalian Ocean University, 52 Heishijiao Rd., Dalian, 116023 Liaoning People’s Republic of China
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Loredana Asztalos M, Schafernak KT, Gray J, Berry A, Paller AS, Mancini AJ. Hermansky-Pudlak syndrome: Report of two patients with updated genetic classification and management recommendations. Pediatr Dermatol 2017; 34:638-646. [PMID: 29044644 DOI: 10.1111/pde.13266] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disorder caused by mutations in one of nine genes involved in the packaging and formation of specialized lysosomes, including melanosomes and platelet-dense granules. The cardinal features are pigmentary dilution, bleeding diathesis, and accumulation of ceroid-like material in reticuloendothelial cells. Pulmonary fibrosis induced by tissue damage is seen in the most severe forms, and one subtype is characterized by immunodeficiency. We describe two patients with HPS type 1 and review the updated gene-based classification, clinical features, and recommendations for evaluation and follow-up.
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Affiliation(s)
- Manuela Loredana Asztalos
- Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA.,Department of Pediatrics, Pathology and Laboratory Medicine , Northwestern University, Chicago, IL, USA.,Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Kristian T Schafernak
- Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA.,Department of Pediatrics, Pathology and Laboratory Medicine , Northwestern University, Chicago, IL, USA.,Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Jayla Gray
- Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA.,Department of Pediatrics, Pathology and Laboratory Medicine , Northwestern University, Chicago, IL, USA.,Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Adam Berry
- Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA.,Department of Pediatrics, Pathology and Laboratory Medicine , Northwestern University, Chicago, IL, USA.,Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Amy S Paller
- Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA.,Department of Pediatrics, Pathology and Laboratory Medicine , Northwestern University, Chicago, IL, USA.,Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Anthony J Mancini
- Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA.,Department of Pediatrics, Pathology and Laboratory Medicine , Northwestern University, Chicago, IL, USA.,Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
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Regulation of mRNA abundance by polypyrimidine tract-binding protein-controlled alternate 5' splice site choice. PLoS Genet 2014; 10:e1004771. [PMID: 25375251 PMCID: PMC4222953 DOI: 10.1371/journal.pgen.1004771] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 09/22/2014] [Indexed: 11/19/2022] Open
Abstract
Alternative splicing (AS) provides a potent mechanism for increasing protein diversity and modulating gene expression levels. How alternate splice sites are selected by the splicing machinery and how AS is integrated into gene regulation networks remain important questions of eukaryotic biology. Here we report that polypyrimidine tract-binding protein 1 (Ptbp1/PTB/hnRNP-I) controls alternate 5' and 3' splice site (5'ss and 3'ss) usage in a large set of mammalian transcripts. A top scoring event identified by our analysis was the choice between competing upstream and downstream 5'ss (u5'ss and d5'ss) in the exon 18 of the Hps1 gene. Hps1 is essential for proper biogenesis of lysosome-related organelles and loss of its function leads to a disease called type 1 Hermansky-Pudlak Syndrome (HPS). We show that Ptbp1 promotes preferential utilization of the u5'ss giving rise to stable mRNAs encoding a full-length Hps1 protein, whereas bias towards d5'ss triggered by Ptbp1 down-regulation generates transcripts susceptible to nonsense-mediated decay (NMD). We further demonstrate that Ptbp1 binds to pyrimidine-rich sequences between the u5'ss and d5'ss and activates the former site rather than repressing the latter. Consistent with this mechanism, u5'ss is intrinsically weaker than d5'ss, with a similar tendency observed for other genes with Ptbp1-induced u5'ss bias. Interestingly, the brain-enriched Ptbp1 paralog Ptbp2/nPTB/brPTB stimulated the u5'ss utilization but with a considerably lower efficiency than Ptbp1. This may account for the tight correlation between Hps1 with Ptbp1 expression levels observed across mammalian tissues. More generally, these data expand our understanding of AS regulation and uncover a post-transcriptional strategy ensuring co-expression of a subordinate gene with its master regulator through an AS-NMD tracking mechanism.
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Bultema JJ, Boyle JA, Malenke PB, Martin FE, Dell'Angelica EC, Cheney RE, Di Pietro SM. Myosin vc interacts with Rab32 and Rab38 proteins and works in the biogenesis and secretion of melanosomes. J Biol Chem 2014; 289:33513-28. [PMID: 25324551 DOI: 10.1074/jbc.m114.578948] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Class V myosins are actin-based motors with conserved functions in vesicle and organelle trafficking. Herein we report the discovery of a function for Myosin Vc in melanosome biogenesis as an effector of melanosome-associated Rab GTPases. We isolated Myosin Vc in a yeast two-hybrid screening for proteins that interact with Rab38, a Rab protein involved in the biogenesis of melanosomes and other lysosome-related organelles. Rab38 and its close homolog Rab32 bind to Myosin Vc but not to Myosin Va or Myosin Vb. Binding depends on residues in the switch II region of Rab32 and Rab38 and regions of the Myosin Vc coiled-coil tail domain. Myosin Vc also interacts with Rab7a and Rab8a but not with Rab11, Rab17, and Rab27. Although Myosin Vc is not particularly abundant on pigmented melanosomes, its knockdown in MNT-1 melanocytes caused defects in the trafficking of integral membrane proteins to melanosomes with substantially increased surface expression of Tyrp1, nearly complete loss of Tyrp2, and significant Vamp7 mislocalization. Knockdown of Myosin Vc in MNT-1 cells more than doubled the abundance of pigmented melanosomes but did not change the number of unpigmented melanosomes. Together the data demonstrate a novel role for Myosin Vc in melanosome biogenesis and secretion.
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Affiliation(s)
- Jarred J Bultema
- From the Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, the Department of Chemistry and Biochemistry, University of Colorado, Colorado Springs, Colorado Springs, Colorado 80918
| | - Judith A Boyle
- From the Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523
| | - Parker B Malenke
- From the Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523
| | - Faye E Martin
- From the Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523
| | - Esteban C Dell'Angelica
- the Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, California 90095, and
| | - Richard E Cheney
- the Department of Cell Biology and Physiology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Santiago M Di Pietro
- From the Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523,
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Hyperosmotic stress reduces melanin production by altering melanosome formation. PLoS One 2014; 9:e105965. [PMID: 25170965 PMCID: PMC4149489 DOI: 10.1371/journal.pone.0105965] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 07/29/2014] [Indexed: 01/01/2023] Open
Abstract
Many tissues of the human body encounter hyperosmotic stress. The effect of extracellular osmotic changes on melanin production has not yet been elucidated. In this study, we determined that hyperosmotic stress induced by organic osmolytes results in reduced melanin production in human melanoma MNT-1 cells. Under hyperosmotic stress, few pigmented mature melanosomes were detected, but there was an increase in swollen vacuoles. These vacuoles were stained with an anti-M6PR antibody that recognizes late endosomal components and with anti-TA99 and anti-HMB45 antibodies, implying that melanosome formation was affected by hyperosmotic stress. Electron microscopic analysis revealed that the M6PR-positive swollen vacuoles were multi-layered and contained melanized granules, and they produced melanin when L-DOPA was applied, indicating that these vacuoles were still capable of producing melanin, but the inner conditions were not compatible with melanin production. The vacuolation phenomenon induced by hyperosmotic conditions disappeared with treatment with the PI3K activator 740 Y-P, indicating that the PI3K pathway is affected by hyperosmotic conditions and is responsible for the proper formation and maturation of melanosomes. The microarray analysis showed alterations of the vesicle organization and transport under hyperosmotic stress. Our findings suggest that melanogenesis could be regulated by physiological conditions, such as osmotic pressure.
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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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Young LR, Gulleman PM, Bridges JP, Weaver TE, Deutsch GH, Blackwell TS, McCormack FX. The alveolar epithelium determines susceptibility to lung fibrosis in Hermansky-Pudlak syndrome. Am J Respir Crit Care Med 2012; 186:1014-24. [PMID: 23043085 DOI: 10.1164/rccm.201207-1206oc] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
RATIONALE Hermansky-Pudlak syndrome (HPS) is a family of recessive disorders of intracellular trafficking defects that are associated with highly penetrant pulmonary fibrosis. Naturally occurring HPS mice reliably model important features of the human disease, including constitutive alveolar macrophage activation and susceptibility to profibrotic stimuli. OBJECTIVES To decipher which cell lineage(s) in the alveolar compartment is the predominant driver of fibrotic susceptibility in HPS. METHODS We used five different HPS and Chediak-Higashi mouse models to evaluate genotype-specific fibrotic susceptibility. To determine whether intrinsic defects in HPS alveolar macrophages cause fibrotic susceptibility, we generated bone marrow chimeras in HPS and wild-type mice. To directly test the contribution of the pulmonary epithelium, we developed a transgenic model with epithelial-specific correction of the HPS2 defect in an HPS mouse model. MEASUREMENTS AND MAIN RESULTS Bone marrow transplantation experiments demonstrated that both constitutive alveolar macrophage activation and increased susceptibility to bleomycin-induced fibrosis were conferred by the genotype of the lung epithelium, rather than that of the bone marrow-derived, cellular compartment. Furthermore, transgenic epithelial-specific correction of the HPS defect significantly attenuated bleomycin-induced alveolar epithelial apoptosis, fibrotic susceptibility, and macrophage activation. Type II cell apoptosis was genotype specific, caspase dependent, and correlated with the degree of fibrotic susceptibility. CONCLUSIONS We conclude that pulmonary fibrosis in naturally occurring HPS mice is driven by intracellular trafficking defects that lower the threshold for pulmonary epithelial apoptosis. Our findings demonstrate a pivotal role for the alveolar epithelium in the maintenance of alveolar homeostasis and regulation of alveolar macrophage activation.
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Affiliation(s)
- Lisa R Young
- Division of Pulmonary Medicine, Department of Pediatrics, Vanderbilt University School of Medicine, 2200 Children's Way, 11215 Doctor's Office Tower, Nashville, TN 37232, USA.
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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.
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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
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10
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Bultema JJ, Ambrosio AL, Burek CL, Di Pietro SM. BLOC-2, AP-3, and AP-1 proteins function in concert with Rab38 and Rab32 proteins to mediate protein trafficking to lysosome-related organelles. J Biol Chem 2012; 287:19550-63. [PMID: 22511774 DOI: 10.1074/jbc.m112.351908] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lysosome-related organelles (LROs) are synthesized in specialized cell types where they largely coexist with conventional lysosomes. Most of the known cellular transport machinery involved in biogenesis are ubiquitously expressed and shared between lysosomes and LROs. Examples of common components are the adaptor protein complex-3 (AP-3) and biogenesis of lysosome-related organelle complex (BLOC)-2. These protein complexes control sorting and transport of newly synthesized integral membrane proteins from early endosomes to both lysosomes and LROs such as the melanosome. However, it is unknown what factors cooperate with the ubiquitous transport machinery to mediate transport to LROs in specialized cells. Focusing on the melanosome, we show that the ubiquitous machinery interacts with cell type-specific Rab proteins, Rab38 and Rab32, to facilitate transport to the maturing organelle. BLOC-2, AP-3, and AP-1 coimmunoprecipitated with Rab38 and Rab32 from MNT-1 melanocytic cell extracts. BLOC-2, AP-3, AP-1, and clathrin partially colocalized with Rab38 and Rab32 by confocal immunofluorescence microscopy in MNT-1 cells. Rab38- and Rab32-deficient MNT-1 cells displayed abnormal trafficking and steady state levels of known cargoes of the BLOC-2, AP-3, and AP-1 pathways, the melanin-synthesizing enzymes tyrosinase and tyrosinase-related protein-1. These observations support the idea that Rab38 and Rab32 are the specific factors that direct the ubiquitous machinery to mediate transport from early endosomes to maturing LROs. Additionally, analysis of tyrosinase-related protein-2 and total melanin production indicates that Rab32 has unique functions that cannot be carried out by Rab38 in melanosome biogenesis.
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Affiliation(s)
- Jarred J Bultema
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, USA
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11
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Lee HH, Nemecek D, Schindler C, Smith WJ, Ghirlando R, Steven AC, Bonifacino JS, Hurley JH. Assembly and architecture of biogenesis of lysosome-related organelles complex-1 (BLOC-1). J Biol Chem 2011; 287:5882-90. [PMID: 22203680 DOI: 10.1074/jbc.m111.325746] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
BLOC-1 (biogenesis of lysosome-related organelles complex-1) is critical for melanosome biogenesis and has also been implicated in neurological function and disease. We show that BLOC-1 is an elongated complex that contains one copy each of the eight subunits pallidin, Cappuccino, dysbindin, Snapin, Muted, BLOS1, BLOS2, and BLOS3. The complex appears as a linear chain of eight globular domains, ∼300 Å long and ∼30 Å in diameter. The individual domains are flexibly connected such that the linear chain undergoes bending by as much as 45°. Two stable subcomplexes were defined, pallidin-Cappuccino-BLOS1 and dysbindin-Snapin-BLOS2. Both subcomplexes are 1:1:1 heterotrimers that form extended structures as indicated by their hydrodynamic properties. The two subcomplexes appear to constitute flexible units within the larger BLOC-1 chain, an arrangement conducive to simultaneous interactions with multiple BLOC-1 partners in the course of tubular endosome biogenesis and sorting.
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Affiliation(s)
- Hyung Ho Lee
- Department of Bio and Nano Chemistry, Kookmin University, Seoul 136-702, Korea
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Kümmel D, Reinisch KM. Structure of Golgi transport proteins. Cold Spring Harb Perspect Biol 2011; 3:cshperspect.a007609. [PMID: 21813399 DOI: 10.1101/cshperspect.a007609] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The function of the Golgi has long been recognized to critically depend on vesicular transport from, to, and within its cisternae, involving constant membrane fission and fusion. These processes are mediated by Arf GTPases and coat proteins, and Rabs, tethers and SNARE proteins, respectively. In this article, we describe structural studies of Golgi coats and tethers and their interactions with SNAREs and GTPases as well as insights regarding membrane traffic processes that these have provided.
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Affiliation(s)
- Daniel Kümmel
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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Delevoye C, Giordano F, van Niel G, Raposo G. [Biogenesis of melanosomes - the chessboard of pigmentation]. Med Sci (Paris) 2011; 27:153-62. [PMID: 21382323 DOI: 10.1051/medsci/2011272153] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Melanosomes are lysosome-related organelles in retinal pigment epithelial cells and epidermal melanocytes in which melanin pigments are synthesized and stored. Melanosomes are generated by multistep processes in which an immature unpigmented organelle forms and then subsequently matures. Such maturation requires inter-organellar transport of protein cargos required for pigment synthesis but also recruitment of effector proteins necessary for the correct transport of melanosomes to the cell periphery. Several studies have started to unravel the main pathways and mechanisms exploited by melanosomal proteins involved in melanosome structure and melanin synthesis. A major unexpected finding seen early in melanosome biogenesis showed the similarities between the fibrillar sheets of premelanosomes and amyloid fibrils. Late steps of melanosome formation are dependent on pathways regulated by proteins encoded by genes mutated in genetic diseases such as the Hermansky-Pudlak Syndrom (HPS) and different types of albinism. Altogether the findings from the past recent years have started to unravel how specialized cells integrate unique and ubiquitous molecular mechanisms in subverting the endosomal system to generate cell-type specific structures and their associated functions. Further dissection of the melanosomal system will likely shed light not only on the biogenesis of lysosome-related organelles but also on general aspects of vesicular transport in the endosomal system.
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Affiliation(s)
- Cédric Delevoye
- Institut Curie, Centre de recherche, CNRS UMR144, 26, rue d'Ulm, 75248 Paris, France.
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Dumaresq-Doiron K, Savard MF, Akam S, Costantino S, Lefrancois S. The phosphatidylinositol 4-kinase PI4KIIIalpha is required for the recruitment of GBF1 to Golgi membranes. J Cell Sci 2010; 123:2273-80. [PMID: 20530568 DOI: 10.1242/jcs.055798] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sorting from the Golgi apparatus requires the recruitment of cytosolic coat proteins to package cargo into trafficking vesicles. An important early step in the formation of trafficking vesicles is the activation of Arf1 by the guanine nucleotide exchange factor GBF1. To activate Arf1, GBF1 must be recruited to and bound to Golgi membranes, a process that requires Rab1b. However, the mechanistic details of how Rab1 is implicated in GBF1 recruitment are not known. In this study, we demonstrate that the recruitment of GBF1 also requires phosphatidylinositol 4-phosphate [PtdIns(4)P]. Inhibitors of PtdIns(4)P synthesis or depletion of PI4KIIIalpha, a phosphatidylinositol 4-kinase localized to the endoplasmic reticulum and Golgi, prevents the recruitment of GBF1 to Golgi membranes. Interestingly, transfection of dominant-active Rab1 increased the amount of PtdIns(4)P at the Golgi, as detected by GFP-PH, a PtdIns(4)P-sensing probe. We propose that Rab1 contributes to the specificity and timing of GBF1 recruitment by activating PI4KIIIalpha. The PtdIns(4)P produced then allows GBF1 to bind to Golgi membranes and activate Arf1.
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Affiliation(s)
- Karine Dumaresq-Doiron
- Centre de Recherche de l'Hôpital Maisonneuve-Rosemont et Département de Médecine, Université de Montréal, Montréal, Québec H1T 2M4, Canada
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15
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Mahavadi P, Korfei M, Henneke I, Liebisch G, Schmitz G, Gochuico BR, Markart P, Bellusci S, Seeger W, Ruppert C, Guenther A. Epithelial stress and apoptosis underlie Hermansky-Pudlak syndrome-associated interstitial pneumonia. Am J Respir Crit Care Med 2010; 182:207-19. [PMID: 20378731 DOI: 10.1164/rccm.200909-1414oc] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE The molecular mechanisms underlying Hermansky-Pudlak syndrome-associated interstitial pneumonia (HPSIP) are poorly understood but, as in idiopathic pulmonary fibrosis, may be linked to chronic alveolar epithelial type II cell (AECII) injury. OBJECTIVES We studied the development of fibrosis and the role of AECII injury in various murine models of HPS. METHODS HPS1, HPS2, and HPS6 monomutant mice, and HPS1/2 and HPS1/6 double-mutant and genetic background mice, were killed at 3 and 9 months of age. Quantitative morphometry was undertaken in lung sections stained with hemalaun-eosin. The extent of lung fibrosis was assessed by trichrome staining and hydroxyproline measurement. Surfactant lipids were analyzed by electrospray ionization mass spectrometry. Surfactant proteins, apoptosis, and lysosomal and endoplasmic reticulum stress markers were studied by Western blotting and immunohistochemistry. Cell proliferation was measured by water-soluble tetrazolium salt-1 and bromodeoxyuridine assays. MEASUREMENTS AND MAIN RESULTS Spontaneous and slowly progressive HPSIP was observed in HPS1/2 double mutants, but not in other HPS mutants, with subpleural onset at 3 months and full-blown fibrosis at 9 months. In these mice, extensive surfactant abnormalities were encountered in AECII and were paralleled by early lysosomal stress (cathepsin D induction), late endoplasmic reticulum stress (activating transcription factor-4 [ATF4], C/EBP homologous protein [CHOP] induction), and marked apoptosis. These findings were fully corroborated in human HPSIP. In addition, cathepsin D overexpression resulted in apoptosis of MLE-12 cells and increased proliferation of NIH 3T3 fibroblasts incubated with conditioned medium of the transfected cells. CONCLUSIONS Extensively impaired surfactant trafficking and secretion underlie lysosomal and endoplasmic reticulum stress with apoptosis of AECII in HPSIP, thereby causing the development of HPSIP.
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Affiliation(s)
- Poornima Mahavadi
- Department of Internal Medicine II, University of Giessen Lung Center (UGLC), Klinikstrasse 36, 35392 Giessen, Germany
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16
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Kloer DP, Rojas R, Ivan V, Moriyama K, van Vlijmen T, Murthy N, Ghirlando R, van der Sluijs P, Hurley JH, Bonifacino JS. Assembly of the biogenesis of lysosome-related organelles complex-3 (BLOC-3) and its interaction with Rab9. J Biol Chem 2010; 285:7794-804. [PMID: 20048159 DOI: 10.1074/jbc.m109.069088] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The Hermansky-Pudlak syndrome (HPS) is a genetic hypopigmentation and bleeding disorder caused by defective biogenesis of lysosome-related organelles (LROs) such as melanosomes and platelet dense bodies. HPS arises from mutations in any of 8 genes in humans and 16 genes in mice. Two of these genes, HPS1 and HPS4, encode components of the biogenesis of lysosome-related organelles complex-3 (BLOC-3). Herein we show that recombinant HPS1-HPS4 produced in insect cells can be efficiently isolated as a 1:1 heterodimer. Analytical ultracentrifugation reveals that this complex has a molecular mass of 146 kDa, equivalent to that of the native complex and to the sum of the predicted molecular masses of HPS1 and HPS4. This indicates that HPS1 and HPS4 interact directly in the absence of any other protein as part of BLOC-3. Limited proteolysis and deletion analyses show that both subunits interact with one another throughout most of their lengths with the sole exception of a long, unstructured loop in the central part of HPS4. An interaction screen reveals a specific and strong interaction of BLOC-3 with the GTP-bound form of the endosomal GTPase, Rab9. This interaction is mediated by HPS4 and the switch I and II regions of Rab9. These characteristics indicate that BLOC-3 might function as a Rab9 effector in the biogenesis of LROs.
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Affiliation(s)
- Daniel P Kloer
- Laboratory of Molecular Biology, NIDDK, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892, USA
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17
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Rouhani FN, Brantly ML, Markello TC, Helip-Wooley A, O'Brien K, Hess R, Huizing M, Gahl WA, Gochuico BR. Alveolar macrophage dysregulation in Hermansky-Pudlak syndrome type 1. Am J Respir Crit Care Med 2009; 180:1114-21. [PMID: 19729668 DOI: 10.1164/rccm.200901-0023oc] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
RATIONALE Individuals with Hermansky-Pudlak syndrome type 1 (HPS-1), an autosomal recessive disorder characterized by defective biogenesis of lysosome-related organelles, develop an accelerated form of progressive fibrotic lung disease. The etiology of pulmonary fibrosis associated with HPS-1 is unknown. OBJECTIVES To investigate the potential pathogenesis of pulmonary fibrosis in HPS-1, lung cells and proteins from individuals with HPS-1 were studied. METHODS Forty-one subjects with HPS-1 with and without pulmonary fibrosis were evaluated with pulmonary function tests, high-resolution computed tomography scan, and bronchoscopy. Bronchoalveolar lavage cells and analytes were analyzed. MEASUREMENTS AND MAIN RESULTS Concentrations of total bronchoalveolar lavage cells and alveolar macrophages were significantly higher in epithelial lining fluid from subjects with HPS-1 with and without pulmonary fibrosis compared with healthy research volunteers. Concentrations of cytokines and chemokines (i.e., monocyte chemoattractant protein-1, macrophage inflammatory protein-1alpha, and granulocyte-macrophage colony-stimulating factor) in alveolar epithelial lining fluid were significantly higher in subjects with HPS-1 with and without pulmonary fibrosis compared with healthy research volunteers (P < 0.001). In vitro, HPS-1 pulmonary fibrosis alveolar macrophages, which did not express HPS1 mRNA, secreted significantly higher concentrations of monocyte chemoattractant protein-1, macrophage inflammatory protein-1alpha, and regulated upon activation, normal T cell expressed and secreted (RANTES) protein compared with normal cells (P = 0.001, P = 0.014, and P = 0.011, respectively). Pirfenidone suppressed HPS-1 alveolar macrophage cytokine and chemokine secretion in vitro in a dose-dependent manner. CONCLUSIONS In HPS-1, alveolar inflammation predominantly involves macrophages and is associated with high lung concentrations of cytokines and chemokines. HPS-1 alveolar macrophages provide a model system in which to study the pathogenesis and treatment of HPS pulmonary fibrosis.
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Affiliation(s)
- Farshid N Rouhani
- Pulmonary-Critical Care Medicine Branch, National Heart, Lung, and Blood Institute, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
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18
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Oyama S, Yamakawa H, Sasagawa N, Hosoi Y, Futai E, Ishiura S. Dysbindin-1, a schizophrenia-related protein, functionally interacts with the DNA- dependent protein kinase complex in an isoform-dependent manner. PLoS One 2009; 4:e4199. [PMID: 19142223 PMCID: PMC2614472 DOI: 10.1371/journal.pone.0004199] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Accepted: 12/03/2008] [Indexed: 11/18/2022] Open
Abstract
DTNBP1 has been recognized as a schizophrenia susceptible gene, and its protein product, dysbindin-1, is down-regulated in the brains of schizophrenic patients. However, little is known about the physiological role of dysbindin-1 in the central nervous system. We hypothesized that disruption of dysbindin-1 with unidentified proteins could contribute to pathogenesis and the symptoms of schizophrenia. GST pull-down from human neuroblastoma lysates showed an association of dysbindin-1 with the DNA-dependent protein kinase (DNA-PK) complex. The DNA-PK complex interacts only with splice isoforms A and B, but not with C. We found that isoforms A and B localized in nucleus, where the kinase complex exist, whereas the isoform C was found exclusively in cytosol. Furthermore, results of phosphorylation assay suggest that the DNA-PK complex phosphorylated dysbindin-1 isoforms A and B in cells. These observations suggest that DNA-PK regulates the dysbindin-1 isoforms A and B by phosphorylation in nucleus. Isoform C does not contain exons from 1 to 6. Since schizophrenia-related single nucleotide polymorphisms (SNPs) occur in these introns between exon 1 and exon 6, we suggest that these SNPs might affect splicing of DTNBP1, which leads to impairment of the functional interaction between dysbindin-1 and DNA-PK in schizophrenic patients.
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Affiliation(s)
- Satoko Oyama
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Hidekuni Yamakawa
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Noboru Sasagawa
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Yoshio Hosoi
- Department of Radiological Technology, School of Health Sciences, Niigata University, Niigata-shi, Niigata, Japan
| | - Eugene Futai
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Shoichi Ishiura
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Meguro-ku, Tokyo, Japan
- * E-mail:
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19
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Bassham DC, Brandizzi F, Otegui MS, Sanderfoot AA. The secretory system of Arabidopsis. THE ARABIDOPSIS BOOK 2008; 6:e0116. [PMID: 22303241 PMCID: PMC3243370 DOI: 10.1199/tab.0116] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Over the past few years, a vast amount of research has illuminated the workings of the secretory system of eukaryotic cells. The bulk of this work has been focused on the yeast Saccharomyces cerevisiae, or on mammalian cells. At a superficial level, plants are typical eukaryotes with respect to the operation of the secretory system; however, important differences emerge in the function and appearance of endomembrane organelles. In particular, the plant secretory system has specialized in several ways to support the synthesis of many components of the complex cell wall, and specialized kinds of vacuole have taken on a protein storage role-a role that is intended to support the growing seedling, but has been co-opted to support human life in the seeds of many crop plants. In the past, most research on the plant secretory system has been guided by results in mammalian or fungal systems but recently plants have begun to stand on their own as models for understanding complex trafficking events within the eukaryotic endomembrane system.
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Affiliation(s)
- Diane C. Bassham
- Department of Genetics, Development and Cell Biology and Plant Sciences Institute, Iowa State University, 455 Bessey Hall, Ames, Iowa 50011
| | - Federica Brandizzi
- MSU-DOE Plant Research Laboratory, Michigan State University, S-238 Plant Biology, East Lansing, Michigan 48824
| | - Marisa S. Otegui
- Department of Botany, University of Wisconsin- Madison, 224 Birge Hall, 430 Lincoln Drive, Madison, Wisconsin 53706
| | - Anton A. Sanderfoot
- Department of Plant Biology, University of Minnesota-Twin Cities, 250 Bioscience Center, 1445 Gortner Ave, St. Paul, Minnesota 55108
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20
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Nazarian R, Huizing M, Helip-Wooley A, Starcevic M, Gahl WA, Dell'Angelica EC. An immunoblotting assay to facilitate the molecular diagnosis of Hermansky-Pudlak syndrome. Mol Genet Metab 2008; 93:134-44. [PMID: 17933573 PMCID: PMC2242292 DOI: 10.1016/j.ymgme.2007.09.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2007] [Revised: 09/01/2007] [Accepted: 09/01/2007] [Indexed: 10/22/2022]
Abstract
Hermansky-Pudlak syndrome (HPS) comprises a constellation of human autosomal recessive disorders characterized by albinism and platelet storage pool deficiency. At least eight types of HPS have been defined based on the identity of the mutated gene. These genes encode components of four ubiquitously expressed protein complexes, named Adaptor Protein (AP)-3 and Biogenesis of Lysosome-related Organelles Complex (BLOC)-1 through -3. In patients of Puerto Rican origin, the molecular diagnosis can be based on analysis of two founder mutations. On the other hand, identification of the HPS type in other patients relies on the sequencing of all candidate genes. In this work, we have developed a biochemical assay to minimize the number of candidate genes to be sequenced per patient. The assay consists of immunoblotting analysis of extracts prepared from skin fibroblasts, using antibodies to one subunit per protein complex. The assay allowed us to determine which complex was defective in each of a group of HPS patients with unknown genetic lesions, thus subsequent sequencing was limited to genes encoding the corresponding subunits. Because no mutations within the two genes encoding BLOC-3 subunits could be found in two patients displaying reduced BLOC-3 levels, the possible existence of additional subunits was considered. Through size-exclusion chromatography and sedimentation velocity analysis, the native molecular mass of BLOC-3 was estimated to be 140+/-30 kDa, a value most consistent with the idea that BLOC-3 is a HPS1HPS4 heterodimer (approximately 156 kDa) albeit not inconsistent with the putative existence of a relatively small third subunit.
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Affiliation(s)
- Ramin Nazarian
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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21
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Abstract
Neurotransmission requires the proper organization and rapid recycling of synaptic vesicles. Rapid retrieval has been suggested to occur either by kiss-and-stay or kiss-and-run mechanisms, whereas classical recycling is mediated by clathrin-dependent endocytosis. Molecular coats are key components in the selection of cargos, AP-2 (adaptor protein 2) playing a prominent role in synaptic vesicle endocytosis. Another coat protein, AP-3, has been implicated in synaptic vesicle biogenesis and in the generation of secretory and lysosomal-related organelles. In the present review, we will particularly focus on the recent data concerning the recycling of synaptic vesicles and the function of AP-3 and the v-SNARE (vesicular soluble N-ethylmaleimide-sensitive fusion protein-attachment protein receptor) TI-VAMP (tetanus neurotoxin-insensitive vesicle-associated membrane protein) in these processes. We propose that AP-3 plays an important regulatory role in neurons which contributes to the basal and stimulated exocytosis of synaptic vesicles.
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Affiliation(s)
- Lydia Danglot
- Membrane Traffic in Neuronal and Epithelial Morphogenesis, INSERM Avenir Team, Paris, France
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22
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Falcón-Pérez JM, Dell'Angelica EC. Zinc transporter 2 (SLC30A2) can suppress the vesicular zinc defect of adaptor protein 3-depleted fibroblasts by promoting zinc accumulation in lysosomes. Exp Cell Res 2007; 313:1473-83. [PMID: 17349999 PMCID: PMC1885236 DOI: 10.1016/j.yexcr.2007.02.006] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2006] [Revised: 01/26/2007] [Accepted: 02/01/2007] [Indexed: 10/23/2022]
Abstract
Zinc accumulation in the lumen of cytoplasmic vesicles is one of the mechanisms by which cells can store significant amounts of this essential but potentially toxic biometal. Previous studies had demonstrated reduced vesicular zinc levels in fibroblasts from mutant mice deficient in adaptor protein 3 (AP-3), a complex involved in protein trafficking to late endosomes and lysosomes. We have observed a similar phenotype in the human fibroblastoid cell line, M1, upon small interference RNA-mediated AP-3 knockdown. A survey of the expression and localization of zinc transporter (ZnT) family members identified ZnT2, ZnT3, and ZnT4 as likely mediators of vesicular zinc accumulation in M1 cells. Expression of green fluorescence protein (GFP)-tagged ZnT2 and ZnT3 promoted accumulation of vesicular zinc as visualized using the indicator zinquin. Moreover, GFP-ZnT2 overexpression elicited a significant accumulation of zinc within mature lysosomes, which in untransfected M1 cells contained little or no chelatable zinc, and restored the zinc storage capability of AP-3-deficient cells. These results suggest that ZnT2 can facilitate vesicular zinc accumulation independently of AP-3 function, and validate the M1 fibroblastoid line as a human cell culture system amenable to the study of vesicular zinc regulation using techniques compatible with functional genomic approaches.
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Affiliation(s)
- Juan M Falcón-Pérez
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.
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23
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Salazar G, Craige B, Styers ML, Newell-Litwa KA, Doucette MM, Wainer BH, Falcon-Perez JM, Dell'Angelica EC, Peden AA, Werner E, Faundez V. BLOC-1 complex deficiency alters the targeting of adaptor protein complex-3 cargoes. Mol Biol Cell 2006; 17:4014-26. [PMID: 16760431 PMCID: PMC1556383 DOI: 10.1091/mbc.e06-02-0103] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Revised: 05/16/2006] [Accepted: 05/31/2006] [Indexed: 01/10/2023] Open
Abstract
Mutational analyses have revealed many genes that are required for proper biogenesis of lysosomes and lysosome-related organelles. The proteins encoded by these genes assemble into five distinct complexes (AP-3, BLOC-1-3, and HOPS) that either sort membrane proteins or interact with SNAREs. Several of these seemingly distinct complexes cause similar phenotypic defects when they are rendered defective by mutation, but the underlying cellular mechanism is not understood. Here, we show that the BLOC-1 complex resides on microvesicles that also contain AP-3 subunits and membrane proteins that are known AP-3 cargoes. Mouse mutants that cause BLOC-1 or AP-3 deficiencies affected the targeting of LAMP1, phosphatidylinositol-4-kinase type II alpha, and VAMP7-TI. VAMP7-TI is an R-SNARE involved in vesicle fusion with late endosomes/lysosomes, and its cellular levels were selectively decreased in cells that were either AP-3- or BLOC-1-deficient. Furthermore, BLOC-1 deficiency selectively altered the subcellular distribution of VAMP7-TI cognate SNAREs. These results indicate that the BLOC-1 and AP-3 protein complexes affect the targeting of SNARE and non-SNARE AP-3 cargoes and suggest a function of the BLOC-1 complex in membrane protein sorting.
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Affiliation(s)
- G Salazar
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA
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24
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Di Pietro SM, Falcón-Pérez JM, Tenza D, Setty SR, Marks MS, Raposo G, Dell’Angelica EC. BLOC-1 interacts with BLOC-2 and the AP-3 complex to facilitate protein trafficking on endosomes. Mol Biol Cell 2006; 17:4027-38. [PMID: 16837549 PMCID: PMC1593172 DOI: 10.1091/mbc.e06-05-0379] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The adaptor protein (AP)-3 complex is a component of the cellular machinery that controls protein sorting from endosomes to lysosomes and specialized related organelles such as melanosomes. Mutations in an AP-3 subunit underlie a form of Hermansky-Pudlak syndrome (HPS), a disorder characterized by abnormalities in lysosome-related organelles. HPS in humans can also be caused by mutations in genes encoding subunits of three complexes of unclear function, named biogenesis of lysosome-related organelles complex (BLOC)-1, -2, and -3. Here, we report that BLOC-1 interacts physically and functionally with AP-3 to facilitate the trafficking of a known AP-3 cargo, CD63, and of tyrosinase-related protein 1 (Tyrp1), a melanosomal membrane protein previously thought to traffic only independently of AP-3. BLOC-1 also interacts with BLOC-2 to facilitate Tyrp1 trafficking by a mechanism apparently independent of AP-3 function. Both BLOC-1 and -2 localize mainly to early endosome-associated tubules as determined by immunoelectron microscopy. These findings support the idea that BLOC-1 and -2 represent hitherto unknown components of the endosomal protein trafficking machinery.
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Affiliation(s)
| | | | - Danièle Tenza
- Institut Curie, Centre National de la Recherche Scientifique-Unité Mixte de Recherche 144, Paris 75248, France; and
| | - Subba R.G. Setty
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Michael S. Marks
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Graça Raposo
- Institut Curie, Centre National de la Recherche Scientifique-Unité Mixte de Recherche 144, Paris 75248, France; and
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25
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Wang N, Hebert DN. Tyrosinase maturation through the mammalian secretory pathway: bringing color to life. ACTA ACUST UNITED AC 2006; 19:3-18. [PMID: 16420243 DOI: 10.1111/j.1600-0749.2005.00288.x] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Tyrosinase has been extensively utilized as a model substrate to study the maturation of glycoproteins in the mammalian secretory pathway. The visual nature of its enzymatic activity (melanin production) has facilitated the identification and characterization of the proteins that assist it becoming a functional enzyme, localized to its proper cellular location. Here, we review the steps involved in the maturation of tyrosinase from when it is first synthesized by cytosolic ribosomes until the mature protein reaches its post-Golgi residence in the melanosomes. These steps include protein processing, covalent modifications, chaperone binding, oligomerization, and trafficking. The disruption of any of these steps can lead to a wide range of pigmentation disorders.
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Affiliation(s)
- Ning Wang
- Program in Molecular and Cellular Biology, Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA, USA
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26
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Abstract
The Hermansky-Pudlak syndrome (HPS) is a collection of related autosomal recessive disorders which are genetically heterogeneous. There are eight human HPS subtypes, characterized by oculocutaneous albinism and platelet storage disease; prolonged bleeding, congenital neutropenia, pulmonary fibrosis, and granulomatous colitis can also occur. HPS is caused primarily by defects in intracellular protein trafficking that result in the dysfunction of intracellular organelles known as lysosome-related organelles. HPS gene products are all ubiquitously expressed and all associate in various multi-protein complexes, yet HPS has cell type-specific disease expression. Impairment of specialized secretory cells such as melanocytes, platelets, lung alveolar type II epithelial cells and cytotoxic T cells are observed in HPS. This review summarizes recent molecular, biochemical and cell biological analyses together with clinical studies that have led to the correlation of molecular pathology with clinical manifestations and led to insights into such diverse disease processes such as albinism, fibrosis, hemorrhage, and congenital neutropenia.
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Affiliation(s)
- Maria L Wei
- Department of Dermatology, Veterans Affairs Medical Center 190, University of California, 4150 Clement St., San Francisco, USA.
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27
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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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Helip-Wooley A, Westbroek W, Dorward H, Mommaas M, Boissy RE, Gahl WA, Huizing M. Association of the Hermansky-Pudlak syndrome type-3 protein with clathrin. BMC Cell Biol 2005; 6:33. [PMID: 16159387 PMCID: PMC1249560 DOI: 10.1186/1471-2121-6-33] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2005] [Accepted: 09/13/2005] [Indexed: 11/29/2022] Open
Abstract
Background Hermansky-Pudlak syndrome (HPS) is a disorder of lysosome-related organelle biogenesis characterized by oculocutaneous albinism and prolonged bleeding. These clinical findings reflect defects in the formation of melanosomes in melanocytes and dense bodies in platelets. HPS type-3 (HPS-3) results from mutations in the HPS3 gene, which encodes a 1004 amino acid protein of unknown function that contains a predicted clathrin-binding motif (LLDFE) at residues 172–176. Results Clathrin was co-immunoprecipitated by HPS3 antibodies from normal but not HPS3 null melanocytes. Normal melanocytes expressing a GFP-HPS3 fusion protein demonstrated partial co-localization of GFP-HPS3 with clathrin following a 20°C temperature block. GFP-HPS3 in which the predicted clathrin-binding domain of HPS3 was mutated (GFP-HPS3-delCBD) did not co-localize with clathrin under the same conditions. Immunoelectron microscopy of normal melanocytes expressing GFP-HPS3 showed co-localization of GFP-HPS3 with clathrin, predominantly on small vesicles in the perinuclear region. In contrast, GFP-HPS3-delCBD did not co-localize with clathrin and exhibited a largely cytoplasmic distribution. Conclusion HPS3 associates with clathrin, predominantly on small clathrin-containing vesicles in the perinuclear region. This association most likely occurs directly via a functional clathrin-binding domain in HPS3. These results suggest a role for HPS3 and its protein complex, BLOC-2, in vesicle formation and trafficking.
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Affiliation(s)
- Amanda Helip-Wooley
- Section on Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, NIH, Bethesda MD, USA
| | - Wendy Westbroek
- Section on Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, NIH, Bethesda MD, USA
| | - Heidi Dorward
- Section on Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, NIH, Bethesda MD, USA
| | - Mieke Mommaas
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, Netherlands
| | - Raymond E Boissy
- Department of Dermatology, University of Cincinnati College of Medicine, OH, USA
| | - William A Gahl
- Section on Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, NIH, Bethesda MD, USA
| | - Marjan Huizing
- Section on Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, NIH, Bethesda MD, USA
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Janvier K, Bonifacino JS. Role of the endocytic machinery in the sorting of lysosome-associated membrane proteins. Mol Biol Cell 2005; 16:4231-42. [PMID: 15987739 PMCID: PMC1196333 DOI: 10.1091/mbc.e05-03-0213] [Citation(s) in RCA: 172] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2005] [Accepted: 06/20/2005] [Indexed: 01/05/2023] Open
Abstract
The limiting membrane of the lysosome contains a group of transmembrane glycoproteins named lysosome-associated membrane proteins (Lamps). These proteins are targeted to lysosomes by virtue of tyrosine-based sorting signals in their cytosolic tails. Four adaptor protein (AP) complexes, AP-1, AP-2, AP-3, and AP-4, interact with such signals and are therefore candidates for mediating sorting of the Lamps to lysosomes. However, the role of these complexes and of the coat protein, clathrin, in sorting of the Lamps in vivo has either not been addressed or remains controversial. We have used RNA interference to show that AP-2 and clathrin-and to a lesser extent the other AP complexes-are required for efficient delivery of the Lamps to lysosomes. Because AP-2 is exclusively associated with plasma membrane clathrin coats, our observations imply that a significant population of Lamps traffic via the plasma membrane en route to lysosomes.
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Affiliation(s)
- Katy Janvier
- Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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30
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Tang X, Yamanaka S, Miyagi Y, Nagashima Y, Nakatani Y. Lung pathology of pale ear mouse (model of Hermansky-Pudlak syndrome 1) and beige mouse (model of Chediak-Higashi syndrome): severity of giant lamellar body degeneration of type II pneumocytes correlates with interstitial inflammation. Pathol Int 2005; 55:137-43. [PMID: 15743322 DOI: 10.1111/j.1440-1827.2005.01811.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The authors have recently reported the presence of characteristic foamy swelling/degeneration (giant lamellar body degeneration, GLBD) of type II pneumocytes in the lungs affected by Hermansky-Pudlak syndrome (HPS)-associated interstitial pneumonia (HPSIP), and proposed the hypothesis that GLBD may be the triggering factor in the development of HPSIP (Virchows Arch 2000; 437: 304-13). The purpose of the present paper was to investigate the lung pathology of pale ear (ep) mouse, a mouse model of HPS1, and of beige (bg) mouse, a mouse model of Chediak-Higashi syndrome (CHS) with a reference to GLBD and associated pathologic changes. GLBD was found in both ep and bg mice soon after birth, and increased in severity as the mice grew older. Younger mice had only GLBD with no evidence of interstitial change. Aged bg mice showed the most prominent GLBD and patchy areas of alveolar collapse accompanied by lymphocytic infiltration and slight fibrosis. Aged ep mice with less severe GLBD than bg mice of comparable ages also had a slight tendency to develop interstitial inflammation but no fibrosis. The pneumocytes with GLBD were immunoreactive for surfactant protein B and composed of giant lamellar bodies ultrastructurally, findings which were almost identical to those of human GLBD. The results of the present study support the hypothesis that GLBD may play an important role in the development of HPSIP. Ep and bg mice, especially the latter, may be useful mouse models of HPSIP.
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Affiliation(s)
- Xiaoyan Tang
- Department of Pathology, Tokyo Hospital, Tokai University School of Medicine, Tokyo, Japan.
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31
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Iwakawa J, Matsuyama W, Watanabe M, Yamamoto M, Oonakahara KI, Machida K, Higashimoto I, Niiyama T, Osame M, Arimura K. Hermansky-Pudlak syndrome with a novel mutation. Intern Med 2005; 44:733-8. [PMID: 16093596 DOI: 10.2169/internalmedicine.44.733] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We report a case of Hermansky-Pudlak syndrome (HPS) with a novel mutation in the HPS1 gene. This case showed oculocutaneous albinism and lysosomal ceroid accumulation, however platelet dysfunction was not observed. Histopathological findings of the biopsied lung tissue were compatible with HPS. Sequencing analysis showed the insertion of C in the codon 178 (739 bp) of the HPS1 gene forming a stop codon at codon 181. To the best of our knowledge, this is a novel HPS1 gene mutation.
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Affiliation(s)
- Jun Iwakawa
- Division of Respiratory Medicine, Respiratory and Stress Care Center, Kagoshima University Hospital, Kagoshima
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32
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Dong X, Li H, Derdowski A, Ding L, Burnett A, Chen X, Peters TR, Dermody TS, Woodruff E, Wang JJ, Spearman P. AP-3 directs the intracellular trafficking of HIV-1 Gag and plays a key role in particle assembly. Cell 2005; 120:663-74. [PMID: 15766529 DOI: 10.1016/j.cell.2004.12.023] [Citation(s) in RCA: 190] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2004] [Revised: 12/21/2004] [Accepted: 12/23/2004] [Indexed: 12/26/2022]
Abstract
Gag proteins direct the process of retroviral particle assembly and form the major protein constituents of the viral core. The matrix region of the HIV-1 Gag polyprotein plays a critical role in the transport of Gag to the plasma membrane assembly site. Recent evidence indicates that Gag trafficking to late endosomal compartments, including multivesicular bodies, occurs prior to viral particle budding from the plasma membrane. Here we demonstrate that the matrix region of HIV-1 Gag interacts directly with the delta subunit of the AP-3 complex, and that this interaction plays an important functional role in particle assembly. Disruption of this interaction eliminated Gag trafficking to multivesicular bodies and diminished HIV particle formation. These studies illuminate an early step in retroviral particle assembly and provide evidence that the trafficking of Gag to late endosomes is part of a productive particle assembly pathway.
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Affiliation(s)
- Xinhong Dong
- Department of Pediatrics and Microbiology and Immunology, Vanderbilt University, Nashville, TN 37232, USA
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33
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Hermann GJ, Schroeder LK, Hieb CA, Kershner AM, Rabbitts BM, Fonarev P, Grant BD, Priess JR. Genetic analysis of lysosomal trafficking in Caenorhabditis elegans. Mol Biol Cell 2005; 16:3273-88. [PMID: 15843430 PMCID: PMC1165410 DOI: 10.1091/mbc.e05-01-0060] [Citation(s) in RCA: 198] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The intestinal cells of Caenorhabditis elegans embryos contain prominent, birefringent gut granules that we show are lysosome-related organelles. Gut granules are labeled by lysosomal markers, and their formation is disrupted in embryos depleted of AP-3 subunits, VPS-16, and VPS-41. We define a class of gut granule loss (glo) mutants that are defective in gut granule biogenesis. We show that the glo-1 gene encodes a predicted Rab GTPase that localizes to lysosome-related gut granules in the intestine and that glo-4 encodes a possible GLO-1 guanine nucleotide exchange factor. These and other glo genes are homologous to genes implicated in the biogenesis of specialized, lysosome-related organelles such as melanosomes in mammals and pigment granules in Drosophila. The glo mutants thus provide a simple model system for the analysis of lysosome-related organelle biogenesis in animal cells.
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Affiliation(s)
- Greg J Hermann
- Department of Biology, Lewis and Clark College, Portland, OR 97219, USA.
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34
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Abstract
Platelet dense granules form using mechanisms shared by melanosomes in melanocytes and by subsets of lysosomes in more generalized cells. Consequently, disorders of platelet dense granules can reveal how organelles form and move within cells. Models for the study of new vesicle formation include isolated delta-storage pool deficiency, combined alphadelta-storage pool deficiency, Hermansky-Pudlak syndrome (HPS), Chediak-Higashi syndrome, Griscelli syndrome, thrombocytopenia absent radii syndrome, and Wiskott-Aldrich syndrome. The molecular bases of dense granule deficiency are known for the seven subtypes of HPS, as well as for Chediak-Higashi syndrome, Griscelli syndrome, and Wiskott-Aldrich syndrome. The gene products involved in these disorders help elucidate the generalized process of the formation of vesicles from extant membranes such as the Golgi.
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Affiliation(s)
- Meral Gunay-Aygun
- Section on Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland
| | - Marjan Huizing
- Section on Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland
| | - William A. Gahl
- Section on Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland
- Clinical Director, National Human Genome Research Institute. Published in 2004 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA
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35
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Huizing M, Hess R, Dorward H, Claassen DA, Helip-Wooley A, Kleta R, Kaiser-Kupfer MI, White JG, Gahl WA. Cellular, molecular and clinical characterization of patients with Hermansky-Pudlak syndrome type 5. Traffic 2005; 5:711-22. [PMID: 15296495 DOI: 10.1111/j.1600-0854.2004.00208.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Hermansky-Pudlak syndrome (HPS) is a disorder of lysosome-related organelles such as melanosomes and platelet dense granules. Seven genes are now associated with HPS in humans. An accurate diagnosis of each HPS subtype has important prognostic and treatment implications. Here we describe the cellular, molecular, and clinical aspects of the recently identified HPS-5 subtype. We first analyzed the genomic organization and the RNA expression pattern of HPS5, located on chromosome 11p14, and demonstrated tissue-specific expression of at least three alternatively spliced HPS5 mRNA transcripts, coding for HPS5A and HPS5B proteins, that differ at their 5'-ends. Genetic screening of 15 unassigned HPS patients yielded six new HPS5 mutations in four patients. Clinically, our HPS-5 patients exhibited iris transillumination, variable hair and skin pigmentation, and absent platelet dense bodies, but not pulmonary fibrosis or granulomatous colitis. In two patients with homozygous missense mutations, hemizygosity was ruled out by gene-dosage multiplex polymerase chain reaction, and immunocytochemical analyses of their fibroblasts supported the HPS-5 diagnosis. Specifically, LAMP-3 distribution was restricted to the perinuclear region in HPS-5 fibroblasts, in contrast to the normal LAMP-3 distribution, which extended to the periphery. This specific intracellular vesicle distribution in fibroblasts, in combination with the clinical features, will improve the characterization of the HPS-5 subtype.
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Affiliation(s)
- Marjan Huizing
- Section on Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, Bethesda, MD, USA.
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36
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Boissy RE, Richmond B, Huizing M, Helip-Wooley A, Zhao Y, Koshoffer A, Gahl WA. Melanocyte-specific proteins are aberrantly trafficked in melanocytes of Hermansky-Pudlak syndrome-type 3. THE AMERICAN JOURNAL OF PATHOLOGY 2005; 166:231-40. [PMID: 15632015 PMCID: PMC1602298 DOI: 10.1016/s0002-9440(10)62247-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Hermansky-Pudlak Syndrome-type 3 (HPS-3) is a relatively mild subtype of HPS with minimal cutaneous and ocular depigmentation. The HPS-3 gene encodes a novel protein of unknown function with a predicted molecular weight of 114 kd. To assess the role of the HPS3 protein in melanization, cultured melanocytes developed from HPS-3 patients were evaluated biochemically and histologically for activity and localization of melanocyte-specific proteins. Endogenous tyrosinase activity of HPS-3 melanocytes was substantial, but tyrosinase activity and melanin synthesis was suppressed in intact melanocytes. However, the level of suppression, as well as extent to which up-regulation by isobutylmethylxanthine and cholera toxin was muted, was less that in HPS-1 melanocytes. Ultrastructurally, HPS-3 melanocytes contained morphologically normal melanosomes, predominantly of stage I and II with minimal stage III and few stage IV melanosomes. Dihydroxyphenylalanine (DOPA) histochemistry demonstrated an increase in melanization of melanosomes. Unique to HPS-3 melanocytes were numerous DOPA-positive 50-nm vesicles and tubular elements present throughout the cell body and dendrites. Tyrosinase, tyrosinase-related protein-1 (Tyrp1), dopachrome tautomerase (Dct), and LAMP1 and 3 localization in HPS-3 melanocytes, as evaluated by immunocytochemistry and confocal microscopy, demonstrated a fine, floccular distribution in contrast to the coarse, granular distribution characteristic of control melanocytes. The localization profile of other proteins expressed by melanocytes (ie, Silver/Pmel17, Melan-A/MART-1, LAMP2, Rab 27, transferrin, c-kit, adaptin-3, and the HPS1 protein) appeared normal. These results suggest that a specific subset of melanocyte proteins are aberrantly trafficked throughout the HPS-3 melanocyte and may be responsible for the reduction in melanin synthesis.
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Affiliation(s)
- Raymond E Boissy
- Department of Dermatology, University of Cincinnati College of Medicine, 231 Albert Sabin Way, ML-0592, Cincinnati, OH 45267-0592, USA.
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37
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Richmond B, Huizing M, Knapp J, Koshoffer A, Zhao Y, Gahl WA, Boissy RE. Melanocytes derived from patients with Hermansky-Pudlak Syndrome types 1, 2, and 3 have distinct defects in cargo trafficking. J Invest Dermatol 2005; 124:420-7. [PMID: 15675963 PMCID: PMC1635963 DOI: 10.1111/j.0022-202x.2004.23585.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Hermansky-Pudlak Syndrome (HPS) is a genetically heterogeneous disorder in which mutations in one of several genes interrupts biogenesis of melanosomes, platelet dense bodies, and lysosomes. Affected patients have oculocutaneous albinism, a bleeding diathesis, and sometimes develop granulomatous colitis or pulmonary fibrosis. In order to assess the role of HPS genes in melanosome biogenesis, melanocytes cultured from patients with HPS subtypes 1, 2, or 3 were assessed for the localization of various melanocyte proteins. Tyrosinase, Tyrp1, and Dct/Tyrp2 were atypically and distinctly expressed in HPS-1 and HPS-3 melanocytes, whereas only tyrosinase showed an atypical distribution in HPS-2 melanocytes. The HPS1 and AP3B1 (i.e., HPS-2) gene products showed no expression in HPS-1 and HPS-2 melanocytes, respectively, whereas HPS-3 melanocytes exhibited normal expression for both proteins. In normal human melanocytes, the HPS1 protein was expressed as an approximately 80 kDa molecule with both granular and reticular intracellular profiles. In HPS-1, lysosome associated membrane protein 1 (LAMP1), and LAMP3 were localized to abnormal large granules; in HPS-2, all LAMPs exhibited a normal granular expression; and in HPS-3, LAMP1, and LAMP3 exhibited a distinct less granular and more floccular pattern. In contrast, the expressions of Rab 27, transferrin, and cKit were unaffected in all three HPS genotypes. These data demonstrate that the three initially identified subtypes of human HPS exhibit distinct defects in the trafficking of various melanocyte-specific proteins.
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Affiliation(s)
- Bonnie Richmond
- Department of Dermatology, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Marjan Huizing
- Section on Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Jill Knapp
- Department of Dermatology, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Amy Koshoffer
- Department of Dermatology, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Yang Zhao
- Department of Dermatology, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - William A. Gahl
- Section on Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Raymond E. Boissy
- Department of Dermatology, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
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38
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Gwynn B, Martina JA, Bonifacino JS, Sviderskaya EV, Lamoreux ML, Bennett DC, Moriyama K, Huizing M, Helip-Wooley A, Gahl WA, Webb LS, Lambert AJ, Peters LL. Reduced pigmentation (rp), a mouse model of Hermansky-Pudlak syndrome, encodes a novel component of the BLOC-1 complex. Blood 2004; 104:3181-9. [PMID: 15265785 DOI: 10.1182/blood-2004-04-1538] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractHermansky-Pudlak syndrome (HPS), a disorder of organelle biogenesis, affects lysosomes, melanosomes, and platelet dense bodies. Seven genes cause HPS in humans (HPS1-HPS7) and at least 15 nonallelic mutations cause HPS in mice. Where their function is known, the HPS proteins participate in protein trafficking and vesicle docking/fusion events during organelle biogenesis. HPS-associated genes participate in at least 4 distinct protein complexes: the adaptor complex AP-3; biogenesis of lysosome-related organelles complex 1 (BLOC-1), consisting of 4 HPS proteins (pallidin, muted, cappuccino, HPS7/sandy); BLOC-2, consisting of HPS6/ruby-eye, HPS5/ruby-eye-2, and HPS3/cocoa; and BLOC-3, consisting of HPS1/pale ear and HPS4/light ear. Here, we report the cloning of the mouse HPS mutation reduced pigmentation (rp). We show that the wild-type rp gene encodes a novel, widely expressed 195-amino acid protein that shares 87% amino acid identity with its human orthologue and localizes to punctate cytoplasmic structures. Further, we show that phosphorylated RP is part of the BLOC-1 complex. In mutant rp/rp mice, a premature stop codon truncates the protein after 79 amino acids. Defects in all the 5 known components of BLOC-1, including RP, cause severe HPS in mice, suggesting that the subunits are nonredundant and that BLOC-1 plays a key role in organelle biogenesis.
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Affiliation(s)
- Babette Gwynn
- The Jackson Laboratory, 600 Main St, Bar Harbor, ME 04609, USA
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39
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Ihrke G, Kyttälä A, Russell MRG, Rous BA, Luzio JP. Differential Use of Two AP-3-mediated Pathways by Lysosomal Membrane Proteins. Traffic 2004; 5:946-62. [PMID: 15522097 DOI: 10.1111/j.1600-0854.2004.00236.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The adaptor protein complex AP-3 is involved in the sorting of lysosomal membrane proteins to late endosomes/lysosomes. It is unclear whether AP-3-containing vesicles form at the trans-Golgi network (TGN) or early endosomes. We have compared the trafficking routes of endolyn/CD164 and 'typical' lysosomal membrane glycoproteins (lgp120/lamp-1 and CD63/lamp-3) containing cytosolic YXXPhi-targeting motifs preceded by asparagine and glycine, respectively. Endolyn, which has a NYHTL-motif, is concentrated in lysosomes, but also occurs in endosomes and at the cell surface. We observed predominant interaction of the NYHTL-motif with the mu-subunits of AP-3 in the yeast two-hybrid system. Endolyn was mislocalized to the cell surface in AP-3-deficient pearl cells, confirming a major role of AP-3 in endolyn traffic. However, lysosomal delivery of endolyn (or a NYHTL-reporter), but not GYXXPhi-containing proteins, was practically abolished when AP-2-mediated endocytosis or traffic from early to late endosomes was inhibited in NRK and 3T3 cells. This indicates that endolyn is mostly transported along the indirect lysosomal pathway (via the cell surface), rather than directly from the TGN to late endosomes/lysosomes. Our results suggest that AP-3 mediates lysosomal sorting of some membrane proteins in early endosomes in addition to sorting of proteins with intrinsically strong AP-3-interacting lysosomal targeting motifs at the TGN.
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Affiliation(s)
- Gudrun Ihrke
- Cambridge Institute for Medical Research, Department of Clinical Biochemistry, University of Cambridge, Wellcome Trust/MRC Building, Cambridge CB2 2XY, UK.
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40
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Styers ML, Salazar G, Love R, Peden AA, Kowalczyk AP, Faundez V. The endo-lysosomal sorting machinery interacts with the intermediate filament cytoskeleton. Mol Biol Cell 2004; 15:5369-82. [PMID: 15456899 PMCID: PMC532017 DOI: 10.1091/mbc.e04-03-0272] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Cytoskeletal networks control organelle subcellular distribution and function. Herein, we describe a previously unsuspected association between intermediate filament proteins and the adaptor complex AP-3. AP-3 and intermediate filament proteins cosedimented and coimmunoprecipitated as a complex free of microtubule and actin binding proteins. Genetic perturbation of the intermediate filament cytoskeleton triggered changes in the subcellular distribution of the adaptor AP-3 and late endocytic/lysosome compartments. Concomitant with these architectural changes, and similarly to AP-3-null mocha cells, fibroblasts lacking vimentin were compromised in their vesicular zinc uptake, their organellar pH, and their total and surface content of AP-3 cargoes. However, the total content and surface levels, as well as the distribution of the transferrin receptor, a membrane protein whose sorting is AP-3 independent, remained unaltered in both AP-3- and vimentin-null cells. Based on the phenotypic convergence between AP-3 and vimentin deficiencies, we predicted and documented a reduced autophagosome content in mocha cells, a phenotype previously reported in cells with disrupted intermediate filament cytoskeletons. Our results reveal a novel role of the intermediate filament cytoskeleton in organelle/adaptor positioning and in regulation of the adaptor complex AP-3.
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Affiliation(s)
- Melanie L Styers
- Graduate Division of Biological and Biomedical Sciences, Emory University, Atlanta, GA 30322, USA
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41
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Ganley IG, Carroll K, Bittova L, Pfeffer S. Rab9 GTPase regulates late endosome size and requires effector interaction for its stability. Mol Biol Cell 2004; 15:5420-30. [PMID: 15456905 PMCID: PMC532021 DOI: 10.1091/mbc.e04-08-0747] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Rab9 GTPase resides in a late endosome microdomain together with mannose 6-phosphate receptors (MPRs) and the tail-interacting protein of 47 kDa (TIP47). To explore the importance of Rab9 for microdomain establishment, we depleted the protein from cultured cells. Rab9 depletion decreased late endosome size and reduced the numbers of multilamellar and dense-tubule-containing late endosomes/lysosomes, but not multivesicular endosomes. The remaining late endosomes and lysosomes were more tightly clustered near the nucleus, implicating Rab9 in endosome localization. Cells displayed increased surface MPRs and lysosome-associated membrane protein 1. In addition, cells showed increased MPR synthesis in conjunction with MPR missorting to the lysosome. Surprisingly, Rab9 stability on late endosomes required interaction with TIP47. Rabs are thought of as independent, prenylated entities that reside either on membranes or in cytosol, bound to GDP dissociation inhibitor. These data show that Rab9 stability is strongly influenced by a specific effector interaction. Moreover, Rab9 and the proteins with which it interacts seem critical for the maintenance of specific late endocytic compartments and endosome/lysosome localization.
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Affiliation(s)
- Ian G Ganley
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305-5307, USA
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42
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Ma J, Plesken H, Treisman JE, Edelman-Novemsky I, Ren M. Lightoid and Claret: a rab GTPase and its putative guanine nucleotide exchange factor in biogenesis of Drosophila eye pigment granules. Proc Natl Acad Sci U S A 2004; 101:11652-7. [PMID: 15289618 PMCID: PMC511034 DOI: 10.1073/pnas.0401926101] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
To elucidate the biogenetic pathways for the generation of lysosome-related organelles, we have chosen to study the Drosophila eye pigment granules because they are lysosome-related and the fruit fly provides the advantages of a genetic system in which many mutations affect eye color. Here, we report the molecular identification of two classic Drosophila eye-color genes required for pigment granule biogenesis, claret and lightoid; the former encodes a protein containing seven repeats with sequence similarity to those that characterize regulator of chromosome condensation 1 (RCC1, a guanine nucleotide exchange factor for the small GTPase, Ran), and the latter encodes a rab GTPase, Rab-RP1. We demonstrate in transfected cells that Claret, through its RCC1-like domain, interacts preferentially with the nucleotide-free form of Rab-RP1, and this interaction involves Claret's first three RCC1-like repeats that are also critical for Claret's function in pigment granule biogenesis in transgenic rescue experiments. In addition, double-mutant analyses suggest that the gene products of claret and lightoid function in the same pathway, which is different from that of garnet and ruby (which encode the delta- and beta-subunit of the tetrameric adaptor protein 3 complex, respectively). Taken together, our results suggest that Claret functions as a guanine nucleotide exchange factor for Lightoid/Rab-RP1 in an adaptor protein 3-independent vesicular trafficking pathway of pigment granule biogenesis.
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Affiliation(s)
- Jinping Ma
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
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43
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Nie Z, Boehm M, Boja ES, Vass WC, Bonifacino JS, Fales HM, Randazzo PA. Specific regulation of the adaptor protein complex AP-3 by the Arf GAP AGAP1. Dev Cell 2003; 5:513-21. [PMID: 12967569 DOI: 10.1016/s1534-5807(03)00234-x] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Arf1 regulates membrane trafficking at several membrane sites by interacting with at least seven different vesicle coat proteins. Here, we test the hypothesis that Arf1-dependent coats are independently regulated by specific interaction with Arf GAPs. We find that the Arf GAP AGAP1 directly associates with and colocalizes with AP-3, a coat protein complex involved in trafficking in the endosomal-lysosomal system. Binding is mediated by the PH domain of AGAP1 and the delta and sigma3 subunits of AP-3. Overexpression of AGAP1 changes the cellular distribution of AP-3, and reduced expression of AGAP1 renders AP-3 resistant to brefeldin A. AGAP1 overexpression does not affect the distribution of other coat proteins, and AP-3 distribution is not affected by overexpression of other Arf GAPs. Cells overexpressing AGAP1 also exhibit increased LAMP1 trafficking via the plasma membrane. Taken together, these results support the hypothesis that AGAP1 directly and specifically regulates AP-3-dependent trafficking.
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Affiliation(s)
- Zhongzhen Nie
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Building 37, Room 4118, Bethesda, MD 20892, USA
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Martina JA, Moriyama K, Bonifacino JS. BLOC-3, a protein complex containing the Hermansky-Pudlak syndrome gene products HPS1 and HPS4. J Biol Chem 2003; 278:29376-84. [PMID: 12756248 DOI: 10.1074/jbc.m301294200] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Hermansky-Pudlak syndrome (HPS) is a genetic disorder characterized by defective lysosome-related organelles. HPS results from mutations in either one of six human genes named HPS1 to HPS6, most of which encode proteins of unknown function. Here we report that the human HPS1 and HPS4 proteins are part of a complex named BLOC-3 (for biogenesis of lysosome-related organelles complex 3). Co-immunoprecipitation experiments demonstrated that epitope-tagged and endogenous HPS1 and HPS4 proteins assemble with each other in vivo. The HPS1.HPS4 complex is predominantly cytosolic, with a small amount being peripherally associated with membranes. Size exclusion chromatography and sedimentation velocity analyses of the cytosolic fraction indicate that HPS1 and HPS4 form a moderately asymmetric protein complex with a molecular mass of approximately 175 kDa. HPS4-deficient fibroblasts from light ear mice display normal distribution and trafficking of the lysosomal membrane protein, Lamp-2, in contrast to fibroblasts from AP-3-deficient pearl mice (HPS2), which exhibit increased trafficking of this lysosomal protein via the plasma membrane. Similarly, light ear fibroblasts display an apparently normal accumulation of Zn2+ in intracellular vesicles, unlike pearl fibroblasts, which exhibit a decreased intracellular Zn2+ storage. Taken together, these observations demonstrate that the HPS1 and HPS4 proteins are components of a cytosolic complex that is involved in the biogenesis of lysosomal-related organelles by a mechanism distinct from that operated by AP-3 complex.
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Affiliation(s)
- José A Martina
- Cell Biology and Metabolism Branch, NICHD, National Institutes of Health, Bethesda, Maryland 20892, USA
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Nazarian R, Falcón-Pérez JM, Dell'Angelica EC. Biogenesis of lysosome-related organelles complex 3 (BLOC-3): a complex containing the Hermansky-Pudlak syndrome (HPS) proteins HPS1 and HPS4. Proc Natl Acad Sci U S A 2003; 100:8770-5. [PMID: 12847290 PMCID: PMC166388 DOI: 10.1073/pnas.1532040100] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2003] [Indexed: 11/18/2022] Open
Abstract
Hermansky-Pudlak syndrome (HPS) defines a group of autosomal recessive disorders characterized by deficiencies in lysosome-related organelles such as melanosomes and platelet-dense granules. Several HPS genes encode proteins of unknown function including HPS1, HPS3, and HPS4. Here we have identified and characterized endogenous HPS3 and HPS4 proteins from HeLa cells. Both proteins were found in soluble and membrane-associated forms. Sedimentation-velocity and coimmunoprecipitation experiments revealed that HPS4 but not HPS3 associates with HPS1 in a complex, which we term biogenesis of lysosome-related organelles complex 3 (BLOC-3). Mutant fibroblasts deficient in either HPS1 or HPS4 displayed abnormal localization of lysosomes and late endosomes, which were less concentrated at the juxtanuclear region in mutant cells than in control fibroblasts. The coat-color phenotype of young homozygous double-mutant mice deficient in subunits of BLOC-3 (HPS1) and BLOC-1 (pallidin) was indistinguishable from that of BLOC-1 single mutants. Taken together, these observations suggest that HPS1 and HPS4 are components of a protein complex that regulates the intracellular localization of lysosomes and late endosomes and may function in a BLOC-1-dependent pathway for melanosome biogenesis.
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Affiliation(s)
- Ramin Nazarian
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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Anderson PD, Huizing M, Claassen DA, White J, Gahl WA. Hermansky-Pudlak syndrome type 4 (HPS-4): clinical and molecular characteristics. Hum Genet 2003; 113:10-7. [PMID: 12664304 DOI: 10.1007/s00439-003-0933-5] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2003] [Accepted: 01/31/2003] [Indexed: 12/17/2022]
Abstract
Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder of oculocutaneous albinism and bleeding attributable to storage-pool-deficient platelets. Although at least 14 mouse models of HPS exist, the human disorders that comprise HPS, i.e., HPS-1, HPS-2, HPS-3, and HPS-4, are recognized to result from mutations in four genes, viz., HPS1, ADTB3A, HPS3, and HPS4, respectively. To characterize further the recently identified HPS-4 disease on molecular and clinical grounds, we first identified the genomic organization of HPS4, located on chromosome 22q11.2-q12.2, including its intron/exon boundaries. We found that HPS4 produces at least two alternatively spliced mRNA transcripts that differ at their 5'-ends. Next, we performed an extensive analysis of 22 unassigned HPS patients (i.e., not having HPS-1, HPS-2, or HPS-3 disease). Using single-strand conformation polymorphism, we determined that seven of the 22 patients had HPS-4. In these seven individuals, we identified five different HPS4 mutations, including one frameshift insertion, one missense, and three nonsense mutations. Three alleles in two patients contained the previously reported Q698insAAGCA frameshift. Three HPS4 mutations were newly described. Four alleles in three patients contained R217X, and two siblings were compound heterozygotes for E138X and E222X. Clinically, our HPS-4 patients exhibited iris transillumination, variable hair and skin pigmentation, absent platelet dense bodies, and occasional pulmonary fibrosis and granulomatous colitis, a severe phenotype similar to that of patients with HPS-1.
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Affiliation(s)
- Paul D Anderson
- Medical Genetics Branch, MSC 1851, Building 10, Room 10C-103, NHGRI, NIH, 10 Center Drive, Bethesda, MD 20892-1851, USA
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Hall AM, Krishnamoorthy L, Orlow SJ. Accumulation of tyrosinase in the endolysosomal compartment is induced by U18666A. PIGMENT CELL RESEARCH 2003; 16:149-58. [PMID: 12622792 DOI: 10.1034/j.1600-0749.2003.00027.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The 3beta-(2-diethylaminoethoxy)-androstenone HCl (U18666A), progesterone and several cationic amphiphilic drugs have been shown to alter the trafficking of a number of intracellular membrane proteins including CD63/Lamp-3, insulin growth factor 2/mannose 6-phosphate receptor (IGF2/MPR), and the Niemann-Pick C1 gene product (NPC1) as well as ganglioside GM1. We have examined the effects of these compounds on cultured melanocytes at concentrations that have been shown to effectively alter intracellular trafficking. Treatment of melanocytes with U18666A (2.5 micro M) or progesterone (15 micro M) for 96 h decreased melanin content an average of 67% as compared with control without lowering the total cellular tyrosinase activity. Steroidal alkaloids that preferentially act on the Sonic Hedgehog signaling pathway showed no related specificity in their ability to decrease pigmentation. In melanocytes treated with U18666A, tyrosinase accumulates in a compartment that contains both lysosome-associated membrane protein-1 (Lamp 1) and MPR, and stains with filipin, consistent with cholesterol-laden late endosomes/lysosomes. Our results suggest that tyrosinase, like the NPC1 gene product, traverses a U18666A-sensitive trafficking pathway.
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Affiliation(s)
- Andrea M Hall
- The Ronald O. Perelman Department of Dermatology, New York University School of Medicine, New York, NY, USA
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Starcevic M, Nazarian R, Dell'Angelica EC. The molecular machinery for the biogenesis of lysosome-related organelles: lessons from Hermansky-Pudlak syndrome. Semin Cell Dev Biol 2003; 13:271-8. [PMID: 12243726 DOI: 10.1016/s1084952102000563] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hermansky-Pudlak syndrome (HPS) defines a group of autosomal recessive disorders characterized by defects in lysosome-related organelles such as melanosomes and platelet dense granules. The genes that are defective in each of the different forms of HPS in humans, or in HPS-like disorders in mice, are thought to encode components of a putative molecular machinery required for the formation of specialized organelles of the lysosomal system. This review discusses the biochemical and functional properties of the products of identified HPS genes, which include subunits of the AP-3 complex and the novel proteins HPS1p, HPS3p, HPS4p, pallidin and muted.
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Affiliation(s)
- Marta Starcevic
- Department of Human Genetics, School of Medicine, University of California at Los Angeles (UCLA), Gonda Center, Room 6357B, Los Angeles, CA 90095-7088, USA
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Moriyama K, Bonifacino JS. Pallidin is a component of a multi-protein complex involved in the biogenesis of lysosome-related organelles. Traffic 2002; 3:666-77. [PMID: 12191018 DOI: 10.1034/j.1600-0854.2002.30908.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The Hermansky-Pudlak syndrome defines a group of genetic disorders characterized by defective lysosome-related organelles such as melanosomes and platelet dense bodies. Hermansky-Pudlak syndrome can be caused by mutations of at least four genes in humans and 15 genes in mice. One of these genes is mutated in the pallid mouse strain and encodes a novel protein named pallidin (L. Huang, Y. M. Kuo and J. Gitschier, Nat Genet 1999; 23: 329-332). Pallidin has no homology to any other known protein and no recognizable functional motifs. We have conducted a biochemical characterization of human pallidin using a newly developed polyclonal antibody. We show that pallidin is a ubiquitously expressed approximately 25 kDa protein found both in the cytosol and peripherally associated to membranes. Sedimentation velocity analyses show that native pallidin has a sedimentation coefficient of approximately 5.1 S, much larger than expected from the molecular mass of the pallidin polypeptide. In line with this observation, cosedimentation and coprecipitation analyses reveal that pallidin is part of a hetero-oligomeric complex. One of the subunits of this complex is the product of another Hermansky-Pudlak syndrome gene, muted. Fibroblasts derived from the muted mouse strain exhibit reduced levels of pallidin, suggesting that the absence of the muted protein destabilizes pallidin. These observations indicate that pallidin is a subunit of a novel multi-protein complex involved in the biogenesis of lysosome-related organelles.
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Affiliation(s)
- Kengo Moriyama
- Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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Falcón-Pérez JM, Starcevic M, Gautam R, Dell'Angelica EC. BLOC-1, a novel complex containing the pallidin and muted proteins involved in the biogenesis of melanosomes and platelet-dense granules. J Biol Chem 2002; 277:28191-9. [PMID: 12019270 DOI: 10.1074/jbc.m204011200] [Citation(s) in RCA: 146] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recent studies have led to the identification of a group of genes required for normal biogenesis of lysosome-related organelles such as melanosomes and platelet-dense granules. Two of these genes, which are defective in the pallid and muted mutant mouse strains, encode small, coiled-coil-forming proteins that display no homology to each other or to any known protein. We report that these two proteins, pallidin and muted, are components of a novel protein complex. We raised antibodies that allow for detection of pallidin from a wide variety of mammalian cells. Endogenous pallidin was distributed in both soluble and peripheral membrane protein fractions. Size-exclusion chromatography and sedimentation velocity analyses indicated that the bulk of cytosolic pallidin is a component of an asymmetric protein complex with a molecular mass of approximately 200 kDa. We named this complex BLOC-1 (for biogenesis of lysosome-related organelles complex 1). Steady-state pallidin protein levels were reduced in fibroblasts derived from muted and reduced pigmentation mice, suggesting that the genes defective in these two mutant strains could encode components of BLOC-1 that are required for pallidin stability. Co-immunoprecipitation and immunodepletion experiments using an antibody to muted confirmed that this protein is a subunit of BLOC-1. Yeast two-hybrid analyses revealed that pallidin is capable of self-association through a region that contains its two coiled-coil forming domains. Unlike AP-3-deficient pearl fibroblasts, which display defects in intracellular zinc storage, zinc distribution was not noticeably affected in pallid or muted fibroblasts. Interestingly, immunofluorescence and in vitro binding experiments demonstrated that pallidin/BLOC-1 is able to associate with actin filaments. We propose that BLOC-1 mediates the biogenesis of lysosome-related organelles by a mechanism that may involve self-assembly and interaction with the actin cytoskeleton.
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Affiliation(s)
- Juan M Falcón-Pérez
- Department of Human Genetics, UCLA School of Medicine, Los Angeles, California 90095, USA
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