1
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Bedard M, van der Niet S, Bernard EM, Babunovic G, Cheng TY, Aylan B, Grootemaat AE, Raman S, Botella L, Ishikawa E, O'Sullivan MP, O'Leary S, Mayfield JA, Buter J, Minnaard AJ, Fortune SM, Murphy LO, Ory DS, Keane J, Yamasaki S, Gutierrez MG, van der Wel N, Moody DB. A terpene nucleoside from M. tuberculosis induces lysosomal lipid storage in foamy macrophages. J Clin Invest 2023; 133:161944. [PMID: 36757797 PMCID: PMC10014106 DOI: 10.1172/jci161944] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 02/03/2023] [Indexed: 02/10/2023] Open
Abstract
Induction of lipid-laden foamy macrophages is a cellular hallmark of tuberculosis (TB) disease, which involves the transformation of infected phagolysosomes from a site of killing into a nutrient-rich replicative niche. Here, we show that a terpenyl nucleoside shed from Mycobacterium tuberculosis, 1-tuberculosinyladenosine (1-TbAd), caused lysosomal maturation arrest and autophagy blockade, leading to lipid storage in M1 macrophages. Pure 1-TbAd, or infection with terpenyl nucleoside-producing M. tuberculosis, caused intralysosomal and peribacillary lipid storage patterns that matched both the molecules and subcellular locations known in foamy macrophages. Lipidomics showed that 1-TbAd induced storage of triacylglycerides and cholesterylesters and that 1-TbAd increased M. tuberculosis growth under conditions of restricted lipid access in macrophages. Furthermore, lipidomics identified 1-TbAd-induced lipid substrates that define Gaucher's disease, Wolman's disease, and other inborn lysosomal storage diseases. These data identify genetic and molecular causes of M. tuberculosis-induced lysosomal failure, leading to successful testing of an agonist of TRPML1 calcium channels that reverses lipid storage in cells. These data establish the host-directed cellular functions of an orphan effector molecule that promotes survival in macrophages, providing both an upstream cause and detailed picture of lysosome failure in foamy macrophages.
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Affiliation(s)
- Melissa Bedard
- Division of Rheumatology, Immunity and Inflammation, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Sanne van der Niet
- Electron Microscopy Centre Amsterdam, Amsterdam University Medical Centre, Amsterdam, Netherlands
| | - Elliott M Bernard
- Host-Pathogen Interactions in Tuberculosis Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Gregory Babunovic
- Division of Rheumatology, Immunity and Inflammation, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Tan-Yun Cheng
- Division of Rheumatology, Immunity and Inflammation, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Beren Aylan
- Host-Pathogen Interactions in Tuberculosis Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Anita E Grootemaat
- Electron Microscopy Centre Amsterdam, Amsterdam University Medical Centre, Amsterdam, Netherlands
| | - Sahadevan Raman
- Division of Rheumatology, Immunity and Inflammation, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Laure Botella
- Host-Pathogen Interactions in Tuberculosis Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Eri Ishikawa
- Department of Molecular Immunology, Research Institute for Microbial Diseases, Osaka University, Suita, Japan
| | - Mary P O'Sullivan
- Department of Clinical Medicine, Trinity Translational Medicine Institute, St. James's Hospital, Trinity College, Dublin, Ireland
| | - Seónadh O'Leary
- Department of Clinical Medicine, Trinity Translational Medicine Institute, St. James's Hospital, Trinity College, Dublin, Ireland
| | - Jacob A Mayfield
- Division of Rheumatology, Immunity and Inflammation, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Jeffrey Buter
- Department of Chemical Biology, Stratingh Institute for Chemistry, Groningen, Netherlands
| | - Adriaan J Minnaard
- Department of Chemical Biology, Stratingh Institute for Chemistry, Groningen, Netherlands
| | - Sarah M Fortune
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | | | - Daniel S Ory
- Casma Therapeutics, Cambridge, Massachusetts, USA
| | - Joseph Keane
- Department of Clinical Medicine, Trinity Translational Medicine Institute, St. James's Hospital, Trinity College, Dublin, Ireland
| | - Sho Yamasaki
- Department of Molecular Immunology, Research Institute for Microbial Diseases, Osaka University, Suita, Japan
| | - Maximiliano G Gutierrez
- Host-Pathogen Interactions in Tuberculosis Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Nicole van der Wel
- Electron Microscopy Centre Amsterdam, Amsterdam University Medical Centre, Amsterdam, Netherlands
| | - D Branch Moody
- Division of Rheumatology, Immunity and Inflammation, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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2
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Kriegler K, Leser C, Mayer P, Bracher F. Effective chiral pool synthesis of both enantiomers of the TRPML inhibitor trans-ML-SI3. Arch Pharm (Weinheim) 2021; 355:e2100362. [PMID: 34738656 DOI: 10.1002/ardp.202100362] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/10/2021] [Accepted: 10/12/2021] [Indexed: 01/05/2023]
Abstract
Two independent chiral pool syntheses of both enantiomers of the TRPML inhibitor, trans-ML-SI3, were developed, starting from commercially available (1S,2R)- and (1R,2S)-configured cis-2-aminocyclohexanols. Both routes lead to the target compounds in excellent enantiomeric purity and good overall yields. For the most attractive (-)-trans-enantiomer, the R,R-configuration was identified by these unambiguous syntheses, and the results were confirmed by single-crystal X-ray structure analysis. These effective synthetic approaches further allow flexible variation of prominent residues in ML-SI3 for future in-depth analysis of structure-activity relationships as both the piperazine and the N-sulfonyl residues are introduced into the molecule at late stages of the synthesis.
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Affiliation(s)
- Katharina Kriegler
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians University of Munich, Munich, Germany
| | - Charlotte Leser
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians University of Munich, Munich, Germany
| | - Peter Mayer
- Department of Chemistry, Ludwig-Maximilians University of Munich, Munich, Germany
| | - Franz Bracher
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians University of Munich, Munich, Germany
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3
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Huang L, Li H, Ye Z, Xu Q, Fu Q, Sun W, Qi W, Yue J. Berbamine inhibits Japanese encephalitis virus (JEV) infection by compromising TPRMLs-mediated endolysosomal trafficking of low-density lipoprotein receptor (LDLR). Emerg Microbes Infect 2021; 10:1257-1271. [PMID: 34102949 PMCID: PMC8238074 DOI: 10.1080/22221751.2021.1941276] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Japanese encephalitis virus (JEV), a member of the Flavivirus genus, is an important pathogen that causes human and animal infectious diseases in Asia. So far, no effective antiviral agents are available to treat JEV infection. Here, we found that LDLR is a host factor required for JEV entry. Berbamine significantly decreases the level of LDLR at the plasma membrane by inducing the secretion of LDLR via extracellular vesicles (EVs), thereby inhibiting JEV infection. Mechanistically, berbamine blocks TRPMLs (Ca2+ permeable non-selective cation channels in endosomes and lysosomes) to compromise the endolysosomal trafficking of LDLR. This leads to the increased secretion of LDLR via EVs and the concomitant decrease in its level at the plasma membrane, thereby rendering cells resistant to JEV infection. Berbamine also protects mice from the lethal challenge of JEV. In summary, these results indicate that berbamine is an effective anti-JEV agent by preventing JEV entry.
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Affiliation(s)
- Lihong Huang
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, People's Republic of China.,Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, People's Republic of China
| | - Huanan Li
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, People's Republic of China
| | - Zuodong Ye
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, People's Republic of China.,Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, People's Republic of China
| | - Qiang Xu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, People's Republic of China
| | - Qiang Fu
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, People's Republic of China.,Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, People's Republic of China.,College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi, People's Republic of China
| | - Wei Sun
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, People's Republic of China.,Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, People's Republic of China
| | - Wenbao Qi
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, People's Republic of China
| | - Jianbo Yue
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, People's Republic of China.,Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, People's Republic of China.,City University of Hong Kong Chengdu Research Institute, Chengdu, People's Republic of China
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4
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Li G, Li PL. Lysosomal TRPML1 Channel: Implications in Cardiovascular and Kidney Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1349:275-301. [PMID: 35138619 PMCID: PMC9899368 DOI: 10.1007/978-981-16-4254-8_13] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Lysosomal ion channels mediate ion flux from lysosomes and regulate membrane potential across the lysosomal membrane, which are essential for lysosome biogenesis, nutrient sensing, lysosome trafficking, lysosome enzyme activity, and cell membrane repair. As a cation channel, the transient receptor potential mucolipin 1 (TRPML1) channel is mainly expressed on lysosomes and late endosomes. Recently, the normal function of TRPML1 channels has been demonstrated to be important for the maintenance of cardiovascular and renal glomerular homeostasis and thereby involved in the pathogenesis of some cardiovascular and kidney diseases. In arterial myocytes, it has been found that Nicotinic Acid Adenine Dinucleotide Phosphate (NAADP), an intracellular second messenger, can induce Ca2+ release through the lysosomal TRPML1 channel, leading to a global Ca2+ release response from the sarcoplasmic reticulum (SR). In podocytes, it has been demonstrated that lysosomal TRPML1 channels control lysosome trafficking and exosome release, which contribute to the maintenance of podocyte functional integrity. The defect or functional deficiency of lysosomal TRPML1 channels has been shown to critically contribute to the initiation and development of some chronic degeneration or diseases in the cardiovascular system or kidneys. Here we briefly summarize the current evidence demonstrating the regulation of lysosomal TRPML1 channel activity and related signaling mechanisms. We also provide some insights into the canonical and noncanonical roles of TRPML1 channel dysfunction as a potential pathogenic mechanism for certain cardiovascular and kidney diseases and associated therapeutic strategies.
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Affiliation(s)
- Guangbi Li
- Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - Pin-Lan Li
- Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA.
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5
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Himmel NJ, Cox DN. Transient receptor potential channels: current perspectives on evolution, structure, function and nomenclature. Proc Biol Sci 2020; 287:20201309. [PMID: 32842926 DOI: 10.1098/rspb.2020.1309] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The transient receptor potential superfamily of ion channels (TRP channels) is widely recognized for the roles its members play in sensory nervous systems. However, the incredible diversity within the TRP superfamily, and the wide range of sensory capacities found therein, has also allowed TRP channels to function beyond sensing an organism's external environment, and TRP channels have thus become broadly critical to (at least) animal life. TRP channels were originally discovered in Drosophila and have since been broadly studied in animals; however, thanks to a boom in genomic and transcriptomic data, we now know that TRP channels are present in the genomes of a variety of creatures, including green algae, fungi, choanoflagellates and a number of other eukaryotes. As a result, the organization of the TRP superfamily has changed radically from its original description. Moreover, modern comprehensive phylogenetic analyses have brought to light the vertebrate-centricity of much of the TRP literature; much of the nomenclature has been grounded in vertebrate TRP subfamilies, resulting in a glossing over of TRP channels in other taxa. Here, we provide a comprehensive review of the function, structure and evolutionary history of TRP channels, and put forth a more complete set of non-vertebrate-centric TRP family, subfamily and other subgroup nomenclature.
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Affiliation(s)
| | - Daniel N Cox
- Neuroscience Institute, Georgia State University, Atlanta, GA, USA
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6
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Jezela-Stanek A, Ciara E, Stepien KM. Neuropathophysiology, Genetic Profile, and Clinical Manifestation of Mucolipidosis IV-A Review and Case Series. Int J Mol Sci 2020; 21:ijms21124564. [PMID: 32604955 PMCID: PMC7348969 DOI: 10.3390/ijms21124564] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 06/21/2020] [Accepted: 06/23/2020] [Indexed: 12/23/2022] Open
Abstract
Mucolipidosis type IV (MLIV) is an ultra-rare lysosomal storage disorder caused by biallelic mutations in MCOLN1 gene encoding the transient receptor potential channel mucolipin-1. So far, 35 pathogenic or likely pathogenic MLIV-related variants have been described. Clinical manifestations include severe intellectual disability, speech deficit, progressive visual impairment leading to blindness, and myopathy. The severity of the condition may vary, including less severe psychomotor delay and/or ocular findings. As no striking recognizable facial dysmorphism, skeletal anomalies, organomegaly, or lysosomal enzyme abnormalities in serum are common features of MLIV, the clinical diagnosis may be significantly improved because of characteristic ophthalmological anomalies. This review aims to outline the pathophysiology and genetic defects of this condition with a focus on the genotype–phenotype correlation amongst cases published in the literature. The authors will present their own clinical observations and long-term outcomes in adult MLIV cases.
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Affiliation(s)
- Aleksandra Jezela-Stanek
- Department of Genetics and Clinical Immunology, National Institute of Tuberculosis and Lung Diseases, 01-138 Warsaw, Poland;
| | - Elżbieta Ciara
- Department of Medical Genetics, The Children’s Memorial Heath Institute, 04-730 Warsaw, Poland;
| | - Karolina M. Stepien
- Adult Inherited Metabolic Diseases, Salford Royal NHS Foundation Trust, Salford M6 8HD, UK
- Correspondence:
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7
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Wypych D, Pomorski P. Calcium Signaling in Glioma Cells: The Role of Nucleotide Receptors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1202:67-86. [PMID: 32034709 DOI: 10.1007/978-3-030-30651-9_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Calcium signaling is probably one of the evolutionary oldest and the most common way by which the signal can be transmitted from the cell environment to the cytoplasmic calcium binding effectors. Calcium signal is fast and due to diversity of calcium binding proteins it may have a very broad effect on cell behavior. Being a crucial player in neuronal transmission it is also very important for glia physiology. It is responsible for the cross-talk between neurons and astrocytes, for microglia activation and motility. Changes in calcium signaling are also crucial for the behavior of transformed glioma cells. The present chapter summarizes molecular mechanisms of calcium signal formation present in glial cells with a strong emphasis on extracellular nucleotide-evoked signaling pathways. Some aspects of glioma C6 signaling such as the cross-talk between P2Y1 and P2Y12 nucleotide receptors in calcium signal generation will be discussed in-depth, to show complexity of machinery engaged in formation of this signal. Moreover, possible mechanisms of modulation of the calcium signal in diverse environments there will be presented herein. Finally, the possible role of calcium signal in glioma motility is also discussed. This is a very important issue, since glioma cells, contrary to the vast majority of neoplastic cells, cannot spread in the body with the bloodstream and, at least in early stages of tumor development, may expand only by means of sheer motility.
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Affiliation(s)
- Dorota Wypych
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Paweł Pomorski
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland.
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8
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Jimenez J, Sakthivel M, Nischal KK, Fedorchak MV. Drug delivery systems and novel formulations to improve treatment of rare corneal disease. Drug Discov Today 2019; 24:1564-1574. [PMID: 30872110 DOI: 10.1016/j.drudis.2019.03.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/17/2019] [Accepted: 03/05/2019] [Indexed: 02/07/2023]
Abstract
As the field of ocular drug delivery grows so does the potential for novel drug discovery or reformulation in lesser-known diseases of the eye. In particular, rare corneal diseases are an interesting area of research because drug delivery is limited to the outermost tissue of the eye. This review will highlight the opportunities and challenges of drug reformulation and alternative treatment approaches for rare corneal diseases. The barriers to effective drug delivery and proposed solutions in development will be discussed along with an overview of corneal rare disease resources, their current treatments and ophthalmic drug delivery systems that could benefit such cases. The regulatory considerations for effective translation of orphan-designated products will also be discussed.
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Affiliation(s)
- Jorge Jimenez
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Meera Sakthivel
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Kanwal K Nischal
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Morgan V Fedorchak
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA; Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, PA, USA; Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; McGowan Institute for Regenerative Medicine, Pittsburgh, PA, USA.
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9
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Jin W, Dai Y, Li F, Zhu L, Huang Z, Liu W, Li J, Zhang M, Du J, Zhang W, Wen Z. Dysregulation of Microglial Function Contributes to Neuronal Impairment in Mcoln1a-Deficient Zebrafish. iScience 2019; 13:391-401. [PMID: 30897512 PMCID: PMC6426713 DOI: 10.1016/j.isci.2019.02.031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 10/28/2018] [Accepted: 02/26/2019] [Indexed: 01/21/2023] Open
Abstract
Type IV mucolipidosis (ML-IV) is a neurodegenerative lysosome storage disorder caused by mutations in the MCOLN1 gene. However, the cellular and molecular bases underlying the neuronal phenotypes of ML-IV disease remain elusive. Using a forward genetic screening, we identified a zebrafish mutant, biluo, that harbors a hypomorphic mutation in mcoln1a, one of the two zebrafish homologs of mammalian MCOLN1. The mcoln1a-deficient mutants display phenotypes partially recapitulating the key features of ML-IV disorder, including the accumulation of enlarged late endosomes in microglia and aberrant neuronal activities in both spontaneous and visual-evoking conditions in optic tectal neurons. We further show that the accumulation of enlarged late endosomes in microglia is caused by the impairment of late endosome and lysosome fusion and the aberrant neuronal activities can be partially rescued by the reconstitution of Mcoln1a function in microglia. Our findings suggest that dysregulation of microglial function may contribute to the development and progression of ML-IV disease. mcoln1a-deficient fish display microglia impairment and aberrant neuronal activity The aberrant neuronal activity can be rescued by expressing WT mcoln1a in microglia Impairment of microglia-neuron contact contributes to the aberrant neuronal activity
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Affiliation(s)
- Wan Jin
- Division of Life Science, State Key Laboratory of Molecular Neuroscience and Center of Systems Biology and Human Health, the Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR. China
| | - Yimei Dai
- Division of Life Science, State Key Laboratory of Molecular Neuroscience and Center of Systems Biology and Human Health, the Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR. China
| | - Funing Li
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, PR. China
| | - Lu Zhu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience and Center of Systems Biology and Human Health, the Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR. China
| | - Zhibin Huang
- Department of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou 510006, PR. China
| | - Wei Liu
- Department of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou 510006, PR. China
| | - Jianchao Li
- Division of Life Science, State Key Laboratory of Molecular Neuroscience and Center of Systems Biology and Human Health, the Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR. China
| | - Mingjie Zhang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience and Center of Systems Biology and Human Health, the Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR. China
| | - Jiulin Du
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, PR. China
| | - Wenqing Zhang
- Department of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou 510006, PR. China.
| | - Zilong Wen
- Division of Life Science, State Key Laboratory of Molecular Neuroscience and Center of Systems Biology and Human Health, the Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR. China; Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute, Shenzhen Peking University-Hong Kong University of Science and Technology Medical Center, Shenzhen 518036, PR. China.
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10
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Preparation and anticancer effect of pegylated-chlorambucil prodrug nanoparticle for enhanced therapeutic efficiency. J IND ENG CHEM 2018. [DOI: 10.1016/j.jiec.2018.03.040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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11
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Weinstock LD, Furness AM, Herron SS, Smith SS, Sankar SB, DeRosa SG, Gao D, Mepyans ME, Scotto Rosato A, Medina DL, Vardi A, Ferreira NS, Cho SM, Futerman AH, Slaugenhaupt SA, Wood LB, Grishchuk Y. Fingolimod phosphate inhibits astrocyte inflammatory activity in mucolipidosis IV. Hum Mol Genet 2018; 27:2725-2738. [PMID: 29771310 PMCID: PMC6915831 DOI: 10.1093/hmg/ddy182] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/09/2018] [Accepted: 05/08/2018] [Indexed: 12/25/2022] Open
Abstract
Mucolipidosis IV (MLIV) is an orphan neurodevelopmental disease that causes severe neurologic dysfunction and loss of vision. Currently there is no therapy for MLIV. It is caused by loss of function of the lysosomal channel mucolipin-1, also known as TRPML1. Knockout of the Mcoln1 gene in a mouse model mirrors clinical and neuropathologic signs in humans. Using this model, we previously observed robust activation of microglia and astrocytes in early symptomatic stages of disease. Here we investigate the consequence of mucolipin-1 loss on astrocyte inflammatory activation in vivo and in vitro and apply a pharmacologic approach to restore Mcoln1-/- astrocyte homeostasis using a clinically approved immunomodulator, fingolimod. We found that Mcoln1-/- mice over-express numerous pro-inflammatory cytokines, some of which were also over-expressed in astrocyte cultures. Changes in the cytokine profile in Mcoln1-/- astrocytes are concomitant with changes in phospho-protein signaling, including activation of PI3K/Akt and MAPK pathways. Fingolimod promotes cytokine homeostasis, down-regulates signaling within the PI3K/Akt and MAPK pathways and restores the lysosomal compartment in Mcoln1-/- astrocytes. These data suggest that fingolimod is a promising candidate for preclinical evaluation in our MLIV mouse model, which, in case of success, can be rapidly translated into clinical trial.
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Affiliation(s)
- Laura D Weinstock
- George W. Woodruff School of Mechanical Engineering, Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory, Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, 315 Ferst Dr., Atlanta, GA, USA
| | - Amanda M Furness
- Department of Neurology, Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Harvard Medical School, 185 Cambridge St., Boston, MA, USA
| | - Shawn S Herron
- Department of Neurology, Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Harvard Medical School, 185 Cambridge St., Boston, MA, USA
| | - Sierra S Smith
- Department of Neurology, Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Harvard Medical School, 185 Cambridge St., Boston, MA, USA
| | - Sitara B Sankar
- George W. Woodruff School of Mechanical Engineering, Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory, Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, 315 Ferst Dr., Atlanta, GA, USA
| | - Samantha G DeRosa
- Department of Neurology, Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Harvard Medical School, 185 Cambridge St., Boston, MA, USA
| | - Dadi Gao
- Department of Neurology, Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Harvard Medical School, 185 Cambridge St., Boston, MA, USA
| | - Molly E Mepyans
- Department of Neurology, Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Harvard Medical School, 185 Cambridge St., Boston, MA, USA
| | - Anna Scotto Rosato
- Telethon Institute of Genetics and Medicine (TIGEM), via Campi Flegrei 34, Pozzuoli (NA), Italy
| | - Diego L Medina
- Telethon Institute of Genetics and Medicine (TIGEM), via Campi Flegrei 34, Pozzuoli (NA), Italy
| | - Ayelet Vardi
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Natalia S Ferreira
- Institute of Pharmacology and Toxicology, University of Zurich-Vetsuisse, Winterthurerstrasse 260, Zurich, Switzerland
| | - Soo Min Cho
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Anthony H Futerman
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Susan A Slaugenhaupt
- Department of Neurology, Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Harvard Medical School, 185 Cambridge St., Boston, MA, USA
| | - Levi B Wood
- George W. Woodruff School of Mechanical Engineering, Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory, Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, 315 Ferst Dr., Atlanta, GA, USA
| | - Yulia Grishchuk
- Department of Neurology, Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Harvard Medical School, 185 Cambridge St., Boston, MA, USA
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12
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Sterea AM, Almasi S, El Hiani Y. The hidden potential of lysosomal ion channels: A new era of oncogenes. Cell Calcium 2018; 72:91-103. [PMID: 29748137 DOI: 10.1016/j.ceca.2018.02.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 02/28/2018] [Accepted: 02/28/2018] [Indexed: 01/14/2023]
Abstract
Lysosomes serve as the control centre for cellular clearance. These membrane-bound organelles receive biomolecules destined for degradation from intracellular and extracellular pathways; thus, facilitating the production of energy and shaping the fate of the cell. At the base of their functionality are the lysosomal ion channels which mediate the function of the lysosome through the modulation of ion influx and efflux. Ion channels form pores in the membrane of lysosomes and allow the passage of ions, a seemingly simple task which harbours the potential of overthrowing the cell's stability. Considered the master regulators of ion homeostasis, these integral membrane proteins enable the proper operation of the lysosome. Defects in the structure or function of these ion channels lead to the development of lysosomal storage diseases, neurodegenerative diseases and cancer. Although more than 50 years have passed since their discovery, lysosomes are not yet fully understood, with their ion channels being even less well characterized. However, significant improvements have been made in the development of drugs targeted against these ion channels as a means of combating diseases. In this review, we will examine how Ca2+, K+, Na+ and Cl- ion channels affect the function of the lysosome, their involvement in hereditary and spontaneous diseases, and current ion channel-based therapies.
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Affiliation(s)
- Andra M Sterea
- Departments of Physiology & Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Shekoufeh Almasi
- Departments of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Yassine El Hiani
- Departments of Physiology & Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada.
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13
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Wyatt A, Wartenberg P, Candlish M, Krasteva-Christ G, Flockerzi V, Boehm U. Genetic strategies to analyze primary TRP channel-expressing cells in mice. Cell Calcium 2017; 67:91-104. [DOI: 10.1016/j.ceca.2017.05.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 05/15/2017] [Accepted: 05/15/2017] [Indexed: 11/26/2022]
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Zhang S, Li N, Zeng W, Gao N, Yang M. Cryo-EM structures of the mammalian endo-lysosomal TRPML1 channel elucidate the combined regulation mechanism. Protein Cell 2017; 8:834-847. [PMID: 28936784 PMCID: PMC5676595 DOI: 10.1007/s13238-017-0476-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 09/18/2017] [Indexed: 01/10/2023] Open
Abstract
TRPML1 channel is a non-selective group-2 transient receptor potential (TRP) channel with Ca2+ permeability. Located mainly in late endosome and lysosome of all mammalian cell types, TRPML1 is indispensable in the processes of endocytosis, membrane trafficking, and lysosome biogenesis. Mutations of TRPML1 cause a severe lysosomal storage disorder called mucolipidosis type IV (MLIV). In the present study, we determined the cryo-electron microscopy (cryo-EM) structures of Mus musculus TRPML1 (mTRPML1) in lipid nanodiscs and Amphipols. Two distinct states of mTRPML1 in Amphipols are added to the closed state, on which could represent two different confirmations upon activation and regulation. The polycystin-mucolipin domain (PMD) may sense the luminal/extracellular stimuli and undergo a “move upward” motion during endocytosis, thus triggering the overall conformational change in TRPML1. Based on the structural comparisons, we propose TRPML1 is regulated by pH, Ca2+, and phosphoinositides in a combined manner so as to accommodate the dynamic endocytosis process.
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Affiliation(s)
- Sensen Zhang
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Ningning Li
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Science, Peking University, Beijing, 100871, China
| | - Wenwen Zeng
- Institute for Immunology and School of Medicine, Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Ning Gao
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Science, Peking University, Beijing, 100871, China.
| | - Maojun Yang
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
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Boudewyn LC, Sikora J, Kuchar L, Ledvinova J, Grishchuk Y, Wang SL, Dobrenis K, Walkley SU. N-butyldeoxynojirimycin delays motor deficits, cerebellar microgliosis, and Purkinje cell loss in a mouse model of mucolipidosis type IV. Neurobiol Dis 2017; 105:257-270. [PMID: 28610891 PMCID: PMC5555164 DOI: 10.1016/j.nbd.2017.06.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 06/02/2017] [Accepted: 06/09/2017] [Indexed: 02/07/2023] Open
Abstract
Mucolipidosis type IV (MLIV) is a lysosomal storage disease exhibiting progressive intellectual disability, motor impairment, and premature death. There is currently no cure or corrective treatment. The disease results from mutations in the gene encoding mucolipin-1, a transient receptor potential channel believed to play a key role in lysosomal calcium egress. Loss of mucolipin-1 and subsequent defects lead to a host of cellular aberrations, including accumulation of glycosphingolipids (GSLs) in neurons and other cell types, microgliosis and, as reported here, cerebellar Purkinje cell loss. Several studies have demonstrated that N-butyldeoxynojirimycin (NB-DNJ, also known as miglustat), an inhibitor of the enzyme glucosylceramide synthase (GCS), successfully delays the onset of motor deficits, improves longevity, and rescues some of the cerebellar abnormalities (e.g., Purkinje cell death) seen in another lysosomal disease known as Niemann-Pick type C (NPC). Given the similarities in pathology between MLIV and NPC, we examined whether miglustat would be efficacious in ameliorating disease progression in MLIV. Using a full mucolipin-1 knockout mouse (Mcoln1-/-), we found that early miglustat treatment delays the onset and progression of motor deficits, delays cerebellar Purkinje cell loss, and reduces cerebellar microgliosis characteristic of MLIV disease. Quantitative mass spectrometry analyses provided new data on the GSL profiles of murine MLIV brain tissue and showed that miglustat partially restored the wild type profile of white matter enriched lipids. Collectively, our findings indicate that early miglustat treatment delays the progression of clinically relevant pathology in an MLIV mouse model, and therefore supports consideration of miglustat as a therapeutic agent for MLIV disease in humans.
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Affiliation(s)
- Lauren C Boudewyn
- Dominick P. Purpura Dept. of Neuroscience, Rose F. Kennedy Intellectual and Developmental Disabilities Research Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Jakub Sikora
- Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Ladislav Kuchar
- Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Jana Ledvinova
- Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Yulia Grishchuk
- Center for Genomic Medicine, Massachusetts General Hospital, Harvard Medical School, 185 Cambridge St., Boston, MA 02114, USA
| | - Shirley L Wang
- Center for Genomic Medicine, Massachusetts General Hospital, Harvard Medical School, 185 Cambridge St., Boston, MA 02114, USA
| | - Kostantin Dobrenis
- Dominick P. Purpura Dept. of Neuroscience, Rose F. Kennedy Intellectual and Developmental Disabilities Research Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Steven U Walkley
- Dominick P. Purpura Dept. of Neuroscience, Rose F. Kennedy Intellectual and Developmental Disabilities Research Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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Lloyd-Evans E, Haslett LJ. The lysosomal storage disease continuum with ageing-related neurodegenerative disease. Ageing Res Rev 2016; 32:104-121. [PMID: 27516378 DOI: 10.1016/j.arr.2016.07.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 07/19/2016] [Accepted: 07/29/2016] [Indexed: 12/11/2022]
Abstract
Lysosomal storage diseases and diseases of ageing share many features both at the physiological level and with respect to the mechanisms that underlie disease pathogenesis. Although the exact pathophysiology is not exactly the same, it is astounding how many similar pathways are altered in all of these diseases. The aim of this review is to provide a summary of the shared disease mechanisms, outlining the similarities and differences and how genetics, insight into rare diseases and functional research has changed our perspective on the causes underlying common diseases of ageing. The lysosome should no longer be considered as just the stomach of the cell or as a suicide bag, it has an emerging role in cellular signalling, nutrient sensing and recycling. The lysosome is of fundamental importance in the pathophysiology of diseases of ageing and by comparing against the LSDs we not only identify common pathways but also therapeutic targets so that ultimately more effective treatments can be developed for all neurodegenerative diseases.
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Reinach PS, Mergler S, Okada Y, Saika S. Ocular transient receptor potential channel function in health and disease. BMC Ophthalmol 2015; 15 Suppl 1:153. [PMID: 26818117 PMCID: PMC4895786 DOI: 10.1186/s12886-015-0135-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Transient receptor potential (TRP) channels sense and transduce environmental stimuli into Ca(2+) transients that in turn induce responses essential for cell function and adaptation. These non-selective channels with variable Ca(2+) selectivity are grouped into seven different subfamilies containing 28 subtypes based on differences in amino acid sequence homology. Many of these subtypes are expressed in the eye on both neuronal and non-neuronal cells where they affect a host of stress-induced regulatory responses essential for normal vision maintenance. This article reviews our current knowledge about the expression, function and regulation of TRPs in different eye tissues. We also describe how under certain conditions TRP activation can induce responses that are maladaptive to ocular function. Furthermore, the possibility of an association between TRP mutations and disease is considered. These findings contribute to evidence suggesting that drug targeting TRP channels may be of therapeutic benefit in a clinical setting. We point out issues that must be more extensively addressed before it will be possible to decide with certainty that this is a realistic endeavor. Another possible upshot of future studies is that disease process progression can be better evaluated by profiling changes in tissue specific functional TRP subtype activity as well as their gene and protein expression.
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Affiliation(s)
- Peter S Reinach
- Department of Ophthalmology and Optometry, Wenzhou Medical University, 270 Xuejuan Road, Wenzhou, Zhejiang, 325027, P. R. China.
| | - Stefan Mergler
- Department of Ophthalmology, Charité-University Medicine Berlin, Campus Virchow-Clinic, Augustenburger Platz 1, 13353, Berlin, Germany.
| | - Yuka Okada
- Department of Ophthalmology, Wakayama Medical University School of Medicine, Wakayama, Japan.
| | - Shizuya Saika
- Department of Ophthalmology, Wakayama Medical University School of Medicine, Wakayama, Japan.
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18
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Reinach PS, Chen W, Mergler S. Polymodal roles of transient receptor potential channels in the control of ocular function. EYE AND VISION 2015; 2:5. [PMID: 26605361 PMCID: PMC4655450 DOI: 10.1186/s40662-015-0016-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 02/15/2015] [Indexed: 12/05/2022]
Abstract
Maintenance of intracellular Ca2+ levels at orders of magnitude below those in the extracellular environment is a requisite for preserving cell viability. Membrane channels contribute to such control through modulating their time-dependent opening and closing behaviour. Such regulation requires Ca2+ to serve as a second messenger mediating receptor control of numerous life-sustaining responses. Transient receptor potential (TRP) channels signal transduce a wide variety of different sensory stimuli to induce responses modulating cellular function. These channels are non-selective cation channels with variable Ca2+ selectivity having extensive sequence homology. They constitute a superfamily made up of 28 different members that are subdivided into 7 different subfamilies based on differences in sequence homology. Some of these TRP channel isotypes are expressed in the eye and localized to both neuronal and non-neuronal cell membranes. Their activation generates intracellular Ca2+ transients and other downstream-linked signalling events that affect numerous responses required for visual function. As there is an association between changes in functional TRP expression in various ocular diseases, there are efforts underway to determine if these channels can be used as drug targets to reverse declines in ocular function. We review here our current knowledge about the expression, function and regulation of TRPs in different eye tissues in health and disease. Furthermore, some of the remaining hurdles are described to developing safe and efficacious TRP channel modulators for use in a clinical setting.
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Affiliation(s)
- Peter S Reinach
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang 325027 P.R. China
| | - Weiwei Chen
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang 325027 P.R. China
| | - Stefan Mergler
- Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Klinik für Augenheilkunde, Augustenburger Platz 1, D-13353 Berlin, Germany
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19
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Tóth BI, Szallasi A, Bíró T. Transient receptor potential channels and itch: how deep should we scratch? Handb Exp Pharmacol 2015; 226:89-133. [PMID: 25861776 DOI: 10.1007/978-3-662-44605-8_6] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Over the past 30 years, transient receptor potential (TRP) channels have evolved from a somewhat obscure observation on how fruit flies detect light to become the center of drug discovery efforts, triggering a heated debate about their potential as targets for therapeutic applications in humans. In this review, we describe our current understanding of the diverse mechanism of action of TRP channels in the itch pathway from the skin to the brain with focus on the peripheral detection of stimuli that elicit the desire to scratch and spinal itch processing and sensitization. We predict that the compelling basic research findings on TRP channels and pruritus will be translated into the development of novel, clinically useful itch medications.
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Affiliation(s)
- Balázs I Tóth
- DE-MTA "Lendület" Cellular Physiology Research Group, Department of Physiology, University of Debrecen, Debrecen, 4032, Hungary
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21
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Feng X, Xiong J, Lu Y, Xia X, Zhu MX. Differential mechanisms of action of the mucolipin synthetic agonist, ML-SA1, on insect TRPML and mammalian TRPML1. Cell Calcium 2014; 56:446-56. [PMID: 25266962 DOI: 10.1016/j.ceca.2014.09.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 09/08/2014] [Accepted: 09/10/2014] [Indexed: 10/24/2022]
Abstract
Mucolipin synthetic agonist 1 (ML-SA1) was recently identified to activate mammalian TRPML channels and shown to alleviate lipid accumulation in lysosomes of cellular models of lysosome storage diseases, mucolipidosis type IV (MLIV) and Niemann-Pick's disease type C (NPC). Owning to its potential use in complimenting genetic studies in Drosophila melanogaster to elucidate the cellular and physiological functions of TRPML channels, we examined the effect of ML-SA1 on Drosophila TRPML expressed in HEK293 cells using whole-cell, inside-out, and whole-lysosome electrophysiological recordings. We previously showed that when expressed in HEK293 cells, Drosophila TRPML was localized and functional on both plasma membrane and endolysosome. We show here that in both inside-out patches excised from the plasma membrane and whole-lysosome recordings from enlarged endolysosome vacuoles, ML-SA1 failed to activate TRPML unless exogenous phosphatidylinositol 3,5-bisphosphate [PI(3,5)P2] was applied. At 1 μM ML-SA1, the sensitivity of TRPML to PI(3,5)P2 increased approximately by 10-fold and at 10 μM ML-SA1, the deactivation of PI(3,5)P2-evoked TRPML currents was markedly slowed. On the other hand, constitutive activation of TRPML by a mutation that mimics the varitint-waddler (Va) mutation of mouse TRPML3 rendered the insect channel sensitive to activation by ML-SA1 alone. Moreover, different from the insect TRPML, mouse TRPML1 was readily activated by ML-SA1 independent of PI(3,5)P2. Thus, our data reveal that while ML-SA1 acts as a true agonist at mouse TRPML1, it behaves as an allosteric activator of the Drosophila TRPML, showing dependence on and the ability to stabilize open conformation of the insect channels.
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Affiliation(s)
- Xinghua Feng
- The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou 510150, China; Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Jian Xiong
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Graduate Program in Cell and Regulatory Biology, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Yungang Lu
- The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou 510150, China; Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Xuefeng Xia
- The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou 510150, China; Center for Genomic Medicine, Houston Methodist Research Institute, Houston, TX 77030, USA.
| | - Michael X Zhu
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Graduate Program in Cell and Regulatory Biology, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
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22
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Feng X, Huang Y, Lu Y, Xiong J, Wong CO, Yang P, Xia J, Chen D, Du G, Venkatachalam K, Xia X, Zhu MX. Drosophila TRPML forms PI(3,5)P2-activated cation channels in both endolysosomes and plasma membrane. J Biol Chem 2013; 289:4262-72. [PMID: 24375408 DOI: 10.1074/jbc.m113.506501] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transient Receptor Potential mucolipin (TRPML) channels are implicated in endolysosomal trafficking, lysosomal Ca(2+) and Fe(2+) release, lysosomal biogenesis, and autophagy. Mutations in human TRPML1 cause the lysosome storage disease, mucolipidosis type IV (MLIV). Unlike vertebrates, which express three TRPML genes, TRPML1-3, the Drosophila genome encodes a single trpml gene. Although the trpml-deficient flies exhibit cellular defects similar to those in mammalian TRPML1 mutants, the biophysical properties of Drosophila TRPML channel remained uncharacterized. Here, we show that transgenic expression of human TRPML1 in the neurons of Drosophila trpml mutants partially suppressed the pupal lethality phenotype. When expressed in HEK293 cells, Drosophila TRPML was localized in both endolysosomes and plasma membrane and was activated by phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2) applied to the cytoplasmic side in whole lysosomes and inside-out patches excised from plasma membrane. The PI(3,5)P2-evoked currents were blocked by phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), but not other phosphoinositides. Using TRPML A487P, which mimics the varitint-waddler (Va) mutant of mouse TRPML3 with constitutive whole-cell currents, we show that TRPML is biphasically regulated by extracytosolic pH, with an optimal pH about 0.6 pH unit higher than that of human TRPML1. In addition to monovalent cations, TRPML exhibits high permeability to Ca(2+), Mn(2+), and Fe(2+), but not Fe(3+). The TRPML currents were inhibited by trivalent cations Fe(3+), La(3+), and Gd(3+). These features resemble more closely to mammalian TRPML1 than TRPML2 and TRPML3, but with some obvious differences. Together, our data support the use of Drosophila for assessing functional significance of TRPML1 in cell physiology.
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Affiliation(s)
- Xinghua Feng
- From the Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China, 510150
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Loss of TRPML1 promotes production of reactive oxygen species: is oxidative damage a factor in mucolipidosis type IV? Biochem J 2013; 457:361-8. [DOI: 10.1042/bj20130647] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
TRPML1 is a lysosomal ion channel permeable to cations, including Fe2+. Our data suggest that TRPML1 redistributes Fe2+ between the lysosomes and the cytoplasm. Loss of TRPML1 leads to production of reactive oxygen species, and to mitochondrial deterioration.
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Lam AK, Galione A. The endoplasmic reticulum and junctional membrane communication during calcium signaling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2542-59. [DOI: 10.1016/j.bbamcr.2013.06.004] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 06/03/2013] [Accepted: 06/03/2013] [Indexed: 12/13/2022]
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Li PL, Zhang Y, Abais JM, Ritter JK, Zhang F. Cyclic ADP-Ribose and NAADP in Vascular Regulation and Diseases. ACTA ACUST UNITED AC 2013; 2:63-85. [PMID: 24749015 DOI: 10.1166/msr.2013.1022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cyclic ADP-ribose (cADPR) and nicotinic acid adenine dinucleotide phosphate (NAADP), two intracellular Ca2+ mobilizing second messengers, have been recognized as a fundamental signaling mechanism regulating a variety of cell or organ functions in different biological systems. Here we reviewed the literature regarding these ADP-ribosylcyclase products in vascular cells with a major focus on their production, physiological roles, and related underlying mechanisms mediating their actions. In particular, several hot topics in this area of research are comprehensively discussed, which may help understand some of the controversial evidence provided by different studies. For example, some new models are emerging for the agonist receptor coupling of CD38 or ADP-ribosylcyclase and for the formation of an acidic microenvironment to facilitate the production of NAADP in vascular cells. We also summarized the evidence regarding the NAADP-mediated two-phase Ca2+ release with a slow Ca2+-induced Ca2+ release (CICR) and corresponding physiological relevance. The possibility of a permanent structural space between lysosomes and sarcoplasmic reticulum (SR), as well as the critical role of lysosome trafficking in phase 2 Ca2+ release in response to some agonists are also explored. With respect to the molecular targets of NAADP within cells, several possible candidates including SR ryanodine receptors (RyRs), lysosomal transient receptor potential-mucolipin 1 (TRP-ML1) and two pore channels (TPCs) are presented with supporting and opposing evidence. Finally, the possible role of NAADP-mediated regulation of lysosome function in autophagy and atherogenesis is discussed, which may indicate a new direction for further studies on the pathological roles of cADPR and NAADP in the vascular system.
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Affiliation(s)
- Pin-Lan Li
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, VA 23298, USA
| | - Yang Zhang
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, VA 23298, USA
| | - Justine M Abais
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, VA 23298, USA
| | - Joseph K Ritter
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, VA 23298, USA
| | - Fan Zhang
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, VA 23298, USA
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Calcium signaling in glioma cells--the role of nucleotide receptors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 986:61-79. [PMID: 22879064 DOI: 10.1007/978-94-007-4719-7_4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Calcium signaling is probably one of the evolutionary oldest and the most common way by which the signal can be transmitted from the cell environment to the cytoplasmic calcium binding effectors. Calcium signal is fast and due to diversity of calcium binding proteins it may have a very broad effect on cell behavior. Being a crucial player in neuronal transmission it is also very important for glia physiology. It is responsible for the cross-talk between neurons and astrocytes, for microglia activation and motility. Changes in calcium signaling are also crucial for the behavior of transformed glioma cells. The present Chapter summarizes molecular mechanisms of calcium signal formation present in glial cells with a strong emphasis on extracellular nucleotide-evoked signaling pathways. Some aspects of glioma C6 signaling such as the cross-talk between P2Y(1) and P2Y(12) nucleotide receptors in calcium signal generation will be discussed in-depth, to show complexity of machinery engaged in formation of this signal. Moreover, possible mechanisms of modulation of the calcium signal in diverse environments there will be presented herein. Finally, the possible role of calcium signal in glioma motility is also discussed. This is a very important issue, since glioma cells, contrary to the vast majority of neoplastic cells, cannot spread in the body with the bloodstream and, at least in early stages of tumor development, may expand only by means of sheer motility.
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Abstract
Described by the Belgian cytologist Christian De Duve in 1949,1 lysosomes (from the Greek “digestive bodies”) are ubiquitous specialized intracellular organelles that ensure the degradation/recycling of macromolecules (proteins, lipids, membranes) through the activity of specific enzymes (i.e., acid hydrolases). They receive their substrates through different internalization pathways (i.e., endocytosis, phagocytosis and autophagy) and are involved in a wide range of physiological functions from cell death and signaling to cholesterol homeostasis and plasma membrane repair.2 In Mammals, 50 soluble lysosomal hydrolases have been described, each targeting specific substrates. They are confined in the lumen of the lysosome and require an optimum pH (i.e., pH 4.5) to work. This acidic pH compared with the slightly alkaline pH of the cytosol (i.e., ~pH 7.2) is maintained by the activity of integral lysosomal membrane proteins (LMPs, that represent the second class of lysosomal proteins), including the V-type proton (H+)-ATPase3 and the chloride ion channel CLC74 that pumps protons from the cytosol across the lysosomal membrane.
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Affiliation(s)
- Norbert Weiss
- Hotchkiss Brain Institute; Department of Physiology and Pharmacology; University of Calgary; Calgary, AB Canada
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28
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Mergler S, Garreis F, Sahlmüller M, Lyras EM, Reinach PS, Dwarakanath A, Paulsen F, Pleyer U. Calcium regulation by thermo- and osmosensing transient receptor potential vanilloid channels (TRPVs) in human conjunctival epithelial cells. Histochem Cell Biol 2012; 137:743-61. [PMID: 22327830 DOI: 10.1007/s00418-012-0924-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/19/2012] [Indexed: 11/28/2022]
Abstract
Transient receptor potential vanilloid (TRPV) channels respond to polymodal stresses to induce pain, inflammation and tissue fibrosis. In this study, we probed for their functional expression in human conjunctival epithelial (HCjE) cells and ex vivo human conjunctivas. Notably, patients suffering from dry eye syndrome experience the same type of symptomology induced by TRPV channel activation in other ocular tissues. TRPV gene and protein expression were determined by RT-PCR and immunohistochemistry in HCjE cells and human conjunctivas (body donors). The planar patch-clamp technique was used to record nonselective cation channel currents. Ca(2+) transients were monitored in fura-2 loaded cells. Cultivated HCjE cells and human conjunctiva express TRPV1, TRPV2, and TRPV4 mRNA. TRPV1 and TRPV4 localization was identified in human conjunctiva. Whereas the TRPV1 agonist capsaicin (CAP) (5-20 μM) -induced Ca(2+) transients were blocked by capsazepine (CPZ) (10 μM), the TRPV4 activator 4α-PDD (10 μM) -induced Ca(2+) increases were reduced by ruthenium-red (RuR) (20 μM). Different heating (<40°C or >43°C) led to Ca(2+) increases, which were also reduced by RuR. Hypotonic challenges of either 25 or 50% induced Ca(2+) transients and nonselective cation channel currents. In conclusion, conjunctiva express TRPV1, TRPV2, and TRPV4 channels which may provide novel drug targets for dry eye therapeutics. Their usage may have fewer side effects than those currently encountered with less selective drugs.
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Affiliation(s)
- Stefan Mergler
- Department of Ophthalmology, Campus Virchow-Clinic, Charité, Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany.
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Mergler S, Cheng Y, Skosyrski S, Garreis F, Pietrzak P, Kociok N, Dwarakanath A, Reinach PS, Kakkassery V. Altered calcium regulation by thermosensitive transient receptor potential channels in etoposide-resistant WERI-Rb1 retinoblastoma cells. Exp Eye Res 2012; 94:157-73. [DOI: 10.1016/j.exer.2011.12.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2011] [Revised: 11/04/2011] [Accepted: 12/03/2011] [Indexed: 10/14/2022]
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Molecular mechanisms of endolysosomal Ca2+ signalling in health and disease. Biochem J 2011; 439:349-74. [PMID: 21992097 DOI: 10.1042/bj20110949] [Citation(s) in RCA: 295] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Endosomes, lysosomes and lysosome-related organelles are emerging as important Ca2+ storage cellular compartments with a central role in intracellular Ca2+ signalling. Endocytosis at the plasma membrane forms endosomal vesicles which mature to late endosomes and culminate in lysosomal biogenesis. During this process, acquisition of different ion channels and transporters progressively changes the endolysosomal luminal ionic environment (e.g. pH and Ca2+) to regulate enzyme activities, membrane fusion/fission and organellar ion fluxes, and defects in these can result in disease. In the present review we focus on the physiology of the inter-related transport mechanisms of Ca2+ and H+ across endolysosomal membranes. In particular, we discuss the role of the Ca2+-mobilizing messenger NAADP (nicotinic acid adenine dinucleotide phosphate) as a major regulator of Ca2+ release from endolysosomes, and the recent discovery of an endolysosomal channel family, the TPCs (two-pore channels), as its principal intracellular targets. Recent molecular studies of endolysosomal Ca2+ physiology and its regulation by NAADP-gated TPCs are providing exciting new insights into the mechanisms of Ca2+-signal initiation that control a wide range of cellular processes and play a role in disease. These developments underscore a new central role for the endolysosomal system in cellular Ca2+ regulation and signalling.
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31
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Mergler S, Valtink M, Taetz K, Sahlmüller M, Fels G, Reinach PS, Engelmann K, Pleyer U. Characterization of transient receptor potential vanilloid channel 4 (TRPV4) in human corneal endothelial cells. Exp Eye Res 2011; 93:710-9. [DOI: 10.1016/j.exer.2011.09.021] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 08/29/2011] [Accepted: 09/07/2011] [Indexed: 11/26/2022]
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Lloyd-Evans E, Platt FM. Lysosomal Ca(2+) homeostasis: role in pathogenesis of lysosomal storage diseases. Cell Calcium 2011; 50:200-5. [PMID: 21724254 DOI: 10.1016/j.ceca.2011.03.010] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 03/21/2011] [Accepted: 03/24/2011] [Indexed: 01/07/2023]
Abstract
Disrupted cellular Ca(2+) signaling is believed to play a role in a number of human diseases including lysosomal storage diseases (LSD). LSDs are a group of ∼50 diseases caused predominantly by mutations in lysosomal proteins that result in accumulation of macromolecules within the lysosome. We recently reported that Niemann-Pick type C (NPC) is the first human disease to be associated with defective lysosomal Ca(2+) uptake and defective NAADP-mediated lysosomal Ca(2+) release. These defects in NPC cells leads to the disruption in endocytosis and subsequent lipid storage that is a feature of this disease. In contrast, Chediak-Higashi Syndrome cells have been reported to have enhanced lysosomal Ca(2+) uptake whilst the TRPML1 protein defective in mucolipidosis type IV is believed to function as a Ca(2+) channel. In this review we provide a summary of the current knowledge on the role of lysosomal Ca(2+) signaling in the pathogenesis of this group of diseases.
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Affiliation(s)
- Emyr Lloyd-Evans
- School of Biosciences, Biomedical Sciences Building, Cardiff University, Museum Avenue, Cardiff CF10 3AX, United Kingdom.
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33
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Abstract
The transient receptor potential (TRP) multigene superfamily encodes integral membrane proteins that function as ion channels. Members of this family are conserved in yeast, invertebrates and vertebrates. The TRP family is subdivided into seven subfamilies: TRPC (canonical), TRPV (vanilloid), TRPM (melastatin), TRPP (polycystin), TRPML (mucolipin), TRPA (ankyrin) and TRPN (NOMPC-like); the latter is found only in invertebrates and fish. TRP ion channels are widely expressed in many different tissues and cell types, where they are involved in diverse physiological processes, such as sensation of different stimuli or ion homeostasis. Most TRPs are non-selective cation channels, only few are highly Ca2+ selective, some are even permeable for highly hydrated Mg2+ ions. This channel family shows a variety of gating mechanisms, with modes of activation ranging from ligand binding, voltage and changes in temperature to covalent modifications of nucleophilic residues. Activated TRP channels cause depolarization of the cellular membrane, which in turn activates voltage-dependent ion channels, resulting in a change of intracellular Ca2+ concentration; they serve as gatekeeper for transcellular transport of several cations (such as Ca2+ and Mg2+), and are required for the function of intracellular organelles (such as endosomes and lysosomes). Because of their function as intracellular Ca2+ release channels, they have an important regulatory role in cellular organelles. Mutations in several TRP genes have been implicated in diverse pathological states, including neurodegenerative disorders, skeletal dysplasia, kidney disorders and pain, and ongoing research may help find new therapies for treatments of related diseases.
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Affiliation(s)
- Bernd Nilius
- Department of Molecular Cell Biology, Laboratory of Ion Channel Research, Campus Gasthuisberg, KU Leuven, Herestraat 49, B-3000 Leuven, Belgium
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Abstract
Until recently, the mechanisms that regulate endolysosomal calcium homoeostasis were poorly understood. The discovery of the molecular target of NAADP (nicotinic acid-adenine dinucleotide phosphate) as the two-pore channels resident in the endolysosomal system has highlighted this compartment as an important calcium store. The recent findings that dysfunctional NAADP release leads to defective endocytic function which in turn results in secondary lipid accumulation in the lysosomal storage disease Niemann-Pick type C, is the first evidence of a direct connection between a human disease and defective lysosomal calcium release. In the present review, we provide a summary of the current knowledge on mechanisms of calcium homoeostasis within the endolysosomal system and how these mechanisms may be affected in human metabolic disorders.
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Abstract
MLIV (mucolipidosis type IV) is a neurodegenerative lysosomal storage disorder caused by mutations in MCOLN1, a gene that encodes TRPML1 (mucolipin-1), a member of the TRPML (transient receptor potential mucolipin) cation channels. Two additional homologues are TRPML2 and TRPML3 comprising the TRPML subgroup in the TRP superfamily. The three proteins play apparently key roles along the endocytosis process, and thus their cellular localization varies among the different group members. Thus TRPML1 is localized exclusively to late endosomes and lysosomes, TRPML2 is primarily located in the recycling clathrin-independent GPI (glycosylphosphatidylinositol)-anchored proteins and early endosomes, and TRPML3 is primarily located in early endosomes. Apparently, all three proteins' main physiological function underlies Ca2+ channelling, regulating the endocytosis process. Recent findings also indicate that the three TRPML proteins form heteromeric complexes at least in some of their cellular content. The physiological role of these complexes in lysosomal function remains to be elucidated, as well as their effect on the pathophysiology of MLIV. Another open question is whether any one of the TRPMLs bears additional function in channel activity
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Yu W, Hill WG, Apodaca G, Zeidel ML. Expression and distribution of transient receptor potential (TRP) channels in bladder epithelium. Am J Physiol Renal Physiol 2010; 300:F49-59. [PMID: 20943764 DOI: 10.1152/ajprenal.00349.2010] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The urothelium is proposed to be a sensory tissue that responds to mechanical stress by undergoing dynamic membrane trafficking and neurotransmitter release; however, the molecular basis of this function is poorly understood. Transient receptor potential (TRP) channels are ideal candidates to fulfill such a role as they can sense changes in temperature, osmolarity, and mechanical stimuli, and several are reported to be expressed in the bladder epithelium. However, their complete expression profile is unknown and their cellular localization is largely undefined. We analyzed expression of all 33 TRP family members in mouse bladder and urothelium by RT-PCR and found 22 specifically expressed in the urothelium. Of the latter, 10 were chosen for closer investigation based on their known mechanosensory or membrane trafficking functions in other cell types. Western blots confirmed urothelial expression of TRPC1, TRPC4, TRPV1, TRPV2, TRPV4, TRPM4, TRPM7, TRPML1, and polycystins 1 and 2 (PKD1 and PKD2) proteins. We further defined the cellular and subcellular localization of all 10 TRP channels. TRPV2 and TRPM4 were prominently localized to the umbrella cell apical membrane, while TRPC4 and TRPV4 were identified on their abluminal surfaces. TRPC1, TRPM7, and TRPML1 were localized to the cytoplasm, while PKD1 and PKD2 were expressed on the apical and basolateral membranes of umbrella cells as well as in the cytoplasm. The cellular location of TRPV1 in the bladder has been debated, but colocalization with neuronal marker calcitonin gene-related peptide indicated clearly that it is present on afferent neurons that extend into the urothelium, but may not be expressed by the urothelium itself. These findings are consistent with the hypothesis that the urothelium acts as a sentinel and by expressing multiple TRP channels it is likely it can detect and presumably respond to a diversity of external stimuli and suggest that it plays an important role in urothelial signal transduction.
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Affiliation(s)
- Weiqun Yu
- Department of Medicine, Renal-Electrolyte Division, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
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Zeevi DA, Lev S, Frumkin A, Minke B, Bach G. Heteromultimeric TRPML channel assemblies play a crucial role in the regulation of cell viability models and starvation-induced autophagy. J Cell Sci 2010; 123:3112-24. [PMID: 20736310 PMCID: PMC2931605 DOI: 10.1242/jcs.067330] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/05/2010] [Indexed: 11/20/2022] Open
Abstract
The mucolipin (TRPML) subfamily of transient receptor potential (TRP) cation channels consists of three members that play various roles in the regulation of membrane and protein sorting along endo-lysosomal pathways. Loss-of-function mutations in TRPML1 cause the neurodegenerative lysosomal storage disorder, mucolipidosis type IV (MLIV), whereas a gain-of-function mutation in TRPML3 is principally implicated in the hearing-impaired and abnormally pigmented varitint-waddler mouse. Currently, TRPML2 is not implicated in any pathological disorder, but we have recently shown that it is a functional cation channel that physically interacts with TRPML1 and TRPML3 to potentially regulate lysosomal integrity. Here, we show that mutant TRPMLs heteromultimerize with other mutant and wild-type TRPMLs to regulate cell viability and starvation-induced autophagy, a process that mediates macromolecular and organellar turnover under cell starvation conditions. Heteromultimerization of dominant-negative TRPMLs with constitutively active TRPMLs rescues cells from the cytotoxic effects of TRPML constitutive activity. Moreover, dominant-negative TRPML1 channels, including a mutant channel directly implicated in MLIV pathology, also inhibit starvation-induced autophagy by interacting with and affecting native TRPML channel function. Collectively, our results indicate that heteromultimerization of TRPML channels plays a role in various TRPML-regulated mechanisms.
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Affiliation(s)
- David A. Zeevi
- Monique and Jacques Roboh Department of Genetic Research, Institute of Medical Research Israel-Canada (IMRIC), Faculty of Medicine of the Hebrew University and Hadassah Hebrew University Hospital, Jerusalem 91120, Israel
| | - Shaya Lev
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada (IMRIC), Faculty of Medicine of the Hebrew University and Hadassah Hebrew University Hospital, Jerusalem 91120, Israel
- The Kühne Minerva Center for Studies of Visual Transduction, Institute of Medical Research Israel-Canada (IMRIC), Faculty of Medicine of the Hebrew University and Hadassah Hebrew University Hospital, Jerusalem 91120, Israel
| | - Ayala Frumkin
- Monique and Jacques Roboh Department of Genetic Research, Institute of Medical Research Israel-Canada (IMRIC), Faculty of Medicine of the Hebrew University and Hadassah Hebrew University Hospital, Jerusalem 91120, Israel
| | - Baruch Minke
- Department of Medical Neurobiology, Institute of Medical Research Israel-Canada (IMRIC), Faculty of Medicine of the Hebrew University and Hadassah Hebrew University Hospital, Jerusalem 91120, Israel
- The Kühne Minerva Center for Studies of Visual Transduction, Institute of Medical Research Israel-Canada (IMRIC), Faculty of Medicine of the Hebrew University and Hadassah Hebrew University Hospital, Jerusalem 91120, Israel
| | - Gideon Bach
- Monique and Jacques Roboh Department of Genetic Research, Institute of Medical Research Israel-Canada (IMRIC), Faculty of Medicine of the Hebrew University and Hadassah Hebrew University Hospital, Jerusalem 91120, Israel
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Schröder B, Wrocklage C, Hasilik A, Saftig P. Molecular characterisation of ‘transmembrane protein 192’ (TMEM192), a novel protein of the lysosomal membrane. Biol Chem 2010; 391:695-704. [DOI: 10.1515/bc.2010.062] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Abstract
Transmembrane protein 192 (TMEM192) has been previously identified in proteomic analyses of lysosomal membranes. TMEM192 does not exhibit any significant homology to known protein families and possesses four potential transmembrane segments. To approach the molecular role of TMEM192, a detailed biochemical characterisation of this protein was performed. Expression constructs of fusion proteins containing TMEM192 and appended epitope tags were constructed. In HeLa cells these proteins were detected in membranes of lysosomes/late endosomes. To examine endogenous TMEM192, a TMEM192-specific antibody was generated and validated. With this antibody colocalisation of endogenous TMEM192 with lysosomal and late endosomal markers was demonstrated. Using Percoll density gradient centrifugation and immunoblotting, co-sedimentation of major portions of both TMEM192 and the lysosomal proteins LAMP-2 and cathepsin D into high-density fractions was observed. Interestingly, in contrast to many other lysosomal proteins no N-glycosylation of TMEM192 could be detected. Western blotting of reduced and non-reduced samples and co-immunoprecipitation experiments indicated TMEM192 to be a homodimer with one or more interchain disulphide bridges. TMEM192 was found to be strongly expressed in human kidney, liver, lung and pancreas tissue. The widespread tissue distribution could suggest an important role of TMEM192 for lysosomal function.
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39
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Geer JS, Skinner SA, Goldin E, Holden KR. Mucolipidosis type IV: a subtle pediatric neurodegenerative disorder. Pediatr Neurol 2010; 42:223-6. [PMID: 20159435 PMCID: PMC2824620 DOI: 10.1016/j.pediatrneurol.2009.10.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Revised: 09/22/2009] [Accepted: 10/12/2009] [Indexed: 11/28/2022]
Abstract
The mucolipidoses are a heterogeneous group of autosomal recessive neurodegenerative lysosomal storage disorders. Mucolipidosis type IV is rare; it is seen predominantly in the Ashkenazi Jewish population and usually presents with global neurodevelopmental delays in infancy, subtle corneal opacifications or clouding, and very slowly progressive neurodegeneration over many years. Elevation of serum gastrin is reported; findings from x-rays of bone and joints and lysosomal studies are normal. Reported here are two cases of mucolipidosis type IV in children not of Ashkenazi Jewish origin who presented during infancy with nonspecific global psychomotor delays, generalized hypotonia, and mild corneal abnormalities, but remained undiagnosed for years. A rare gene mutation in MCOLN1 was confirmed in one of the two patients, in addition to abnormal serum gastrin levels. More striking was the length of time that these children eluded detection of their final diagnosis.
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Affiliation(s)
| | | | - Ehud Goldin
- Developmental and Metabolic Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Kenton R. Holden
- Greenwood Genetic Center, Greenwood, South Carolina, Departments of Neurosciences and Pediatrics, Medical University of South Carolina, Charleston, South Carolina
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40
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Transient receptor potential channelopathies. Pflugers Arch 2010; 460:437-50. [PMID: 20127491 DOI: 10.1007/s00424-010-0788-2] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Accepted: 01/12/2010] [Indexed: 12/31/2022]
Abstract
In the past years, several hereditary diseases caused by defects in transient receptor potential channels (TRP) genes have been described. This review summarizes our current knowledge about TRP channelopathies and their possible pathomechanisms. Based on available genetic indications, we will also describe several putative pathological conditions in which (mal)function of TRP channels could be anticipated.
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41
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Lev S, Zeevi DA, Frumkin A, Offen-Glasner V, Bach G, Minke B. Constitutive activity of the human TRPML2 channel induces cell degeneration. J Biol Chem 2010; 285:2771-82. [PMID: 19940139 PMCID: PMC2807332 DOI: 10.1074/jbc.m109.046508] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2009] [Revised: 11/19/2009] [Indexed: 01/01/2023] Open
Abstract
The mucolipin (TRPML) ion channel proteins represent a distinct subfamily of channel proteins within the transient receptor potential (TRP) superfamily of cation channels. Mucolipin 1, 2, and 3 (TRPML1, -2, and -3, respectively) are channel proteins that share high sequence homology with each other and homology in the transmembrane domain with other TRPs. Mutations in the TRPML1 protein are implicated in mucolipidosis type IV, whereas mutations in TRPML3 are found in the varitint-waddler mouse. The properties of the wild type TRPML2 channel are not well known. Here we show functional expression of the wild type human TRPML2 channel (h-TRPML2). The channel is functional at the plasma membrane and characterized by a significant inward rectification similar to other constitutively active TRPML mutant isoforms. The h-TRPML2 channel displays nonselective cation permeability, which is Ca(2+)-permeable and inhibited by low extracytosolic pH but not Ca(2+) regulated. In addition, constitutively active h-TRPML2 leads to cell death by causing Ca(2+) overload. Furthermore, we demonstrate by functional mutation analysis that h-TRPML2 shares similar characteristics and structural similarities with other TRPML channels that regulate the channel in a similar manner. Hence, in addition to overall structure, all three TRPML channels also share common modes of regulation.
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Affiliation(s)
- Shaya Lev
- From the Department of Medical Neurobiology and the Kühne Minerva Center for Studies of Visual Transduction, Faculty of Medicine of the Hebrew University, and
| | - David A. Zeevi
- the Department of Human Genetics, Hadassah Hebrew University Hospital, Jerusalem 91120, Israel
| | - Ayala Frumkin
- the Department of Human Genetics, Hadassah Hebrew University Hospital, Jerusalem 91120, Israel
| | - Vered Offen-Glasner
- the Department of Human Genetics, Hadassah Hebrew University Hospital, Jerusalem 91120, Israel
| | - Gideon Bach
- the Department of Human Genetics, Hadassah Hebrew University Hospital, Jerusalem 91120, Israel
| | - Baruch Minke
- From the Department of Medical Neurobiology and the Kühne Minerva Center for Studies of Visual Transduction, Faculty of Medicine of the Hebrew University, and
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Vergarajauregui S, Martina JA, Puertollano R. Identification of the penta-EF-hand protein ALG-2 as a Ca2+-dependent interactor of mucolipin-1. J Biol Chem 2009; 284:36357-36366. [PMID: 19864416 DOI: 10.1074/jbc.m109.047241] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Loss of function mutations in mucolipin-1 (MCOLN1) have been linked to mucolipidosis type IV (MLIV), a recessive lysosomal storage disease characterized by severe neurological and ophthalmological abnormalities. MCOLN1 is an ion channel that regulates membrane transport along the endolysosomal pathway. It has been suggested that MCOLN1 participates in several Ca(2+)-dependent processes, including fusion of lysosomes with the plasma membrane, fusion of late endosomes and autophagosomes with lysosomes, and lysosomal biogenesis. Here, we searched for proteins that interact with MCOLN1 in a Ca(2+)-dependent manner. We found that the penta-EF-hand protein ALG-2 binds to the NH-terminal cytosolic tail of MCOLN1. The interaction is direct, strictly dependent on Ca(2+), and mediated by a patch of charged and hydrophobic residues located between MCOLN1 residues 37 and 49. We further show that MCOLN1 and ALG-2 co-localize to enlarged endosomes induced by overexpression of an ATPase-defective dominant-negative form of Vps4B (Vps4B(E235Q)). In agreement with the proposed role of MCOLN1 in the regulation of fusion/fission events, we found that overexpression of MCOLN1 caused accumulation of enlarged, aberrant endosomes that contain both early and late endosome markers. Interestingly, aggregation of abnormal endosomes was greatly reduced when the ALG-2-binding domain in MCOLN1 was mutated, suggesting that ALG-2 regulates MCOLN1 function. Overall, our data provide new insight into the molecular mechanisms that regulate MCOLN1 activity. We propose that ALG-2 acts as a Ca(2+) sensor that modulates the function of MCOLN1 along the late endosomal-lysosomal pathway.
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Affiliation(s)
- Silvia Vergarajauregui
- Laboratory of Cell Biology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892
| | - Jose A Martina
- Laboratory of Cell Biology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892
| | - Rosa Puertollano
- Laboratory of Cell Biology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892.
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Zeevi DA, Frumkin A, Offen-Glasner V, Kogot-Levin A, Bach G. A potentially dynamic lysosomal role for the endogenous TRPML proteins. J Pathol 2009; 219:153-62. [PMID: 19557826 DOI: 10.1002/path.2587] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Accepted: 05/28/2009] [Indexed: 11/10/2022]
Abstract
Lysosomal storage disorders (LSDs) constitute a diverse group of inherited diseases that result from lysosomal storage of compounds occurring in direct consequence to deficiencies of proteins implicated in proper lysosomal function. Pathology in the LSD mucolipidosis type IV (MLIV), is characterized by lysosomal storage of lipids together with water-soluble materials in cells from every tissue and organ of affected patients. Mutations in the mucolipin 1 (TRPML1) protein cause MLIV and TRPML1 has also been shown to interact with two of its paralogous proteins, mucolipin 2 (TRPML2) and mucolipin 3 (TRPML3), in heterologous expression systems. Heterogeneous lysosomal storage is readily identified in electron micrographs of MLIV patient cells, suggesting that proper TRPML1 function is essential for the maintenance of lysosomal integrity. In order to investigate whether TRPML2 and TRPML3 also play a role in the maintenance of lysosomal integrity, we conducted gene-specific knockdown assays against these protein targets. Ultrastructural analysis revealed lysosomal inclusions in both TRPML2 and TRPML3 knockdown cells, suggestive of a common mechanism for these proteins, in parallel with TRPML1, in the regulation of lysosomal integrity. However, co-immunoprecipitation assays revealed that physical interactions between each of the endogenous TRPML proteins are quite limited. In addition, we found that all three endogenous proteins only partially co-localize with each other in lysosomal as well as extra-lysosomal compartments. This suggests that native TRPML2 and TRPML3 might participate with native TRPML1 in a dynamic form of lysosomal regulation. Given that depletion of TRPML2/3 led to lysosomal storage typical to an LSD, we propose that depletion of these proteins might also underlie novel LSD pathologies not described hitherto.
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Affiliation(s)
- David A Zeevi
- Department of Human Genetics, Hadassah Hebrew University Hospital, Jerusalem, Israel
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44
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Kogot-Levin A, Zeigler M, Ornoy A, Bach G. Mucolipidosis type IV: the effect of increased lysosomal pH on the abnormal lysosomal storage. Pediatr Res 2009; 65:686-90. [PMID: 19247216 DOI: 10.1203/pdr.0b013e3181a1681a] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Mucolipidosis type IV (MLIV) is a neurodegenerative channelopathy that is caused by the deficiency of TRPML1 activity, a nonselective cation channel. TRPML1 is a lysosomal membrane protein, and thus, MLIV is a lysosomal storage disorder. The basic, specific function of TRPML1 has not been yet clarified. A recent report (Soyombo AA, Tjon-Kon-Sang S, Rbaibi Y, Bashllari E, Bisceglia J, Muallem S, Kiselyov K: J Biol Chem 281:7294-7301, 2006) indicated that TRPML1 functions as an outwardly proton channel whose function is the prevention of overacidification of these organelles. Thus, in MLIV the lysosomal pH is lower than normal. Furthermore, attempts by these investigators to increase slightly the lysososmal pH with either Nigericin or Chloroquine suggested corrective effect of the abnormal storage in MLIV cells. We investigated this approach using these agents with cultured fibroblasts from severely affected and milder patients. Our data indicated that there was no reduction in the total number of storage vesicles by either agent, although Nigericin resulted in a change in the nature of the storage materials, reducing the presence of lamellated substances (lipids) so that the storage vesicles contained predominantly granulated substances. On the other hand, transfection with the normal MCOLN1 cDNA (the gene coding for TRPML1) resulted in the removal of almost all the storage materials.
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Affiliation(s)
- Aviram Kogot-Levin
- Department of Human Genetics, Hadassah University Hospital, Jerusalem, Israel
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45
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Ruivo R, Anne C, Sagné C, Gasnier B. Molecular and cellular basis of lysosomal transmembrane protein dysfunction. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1793:636-49. [DOI: 10.1016/j.bbamcr.2008.12.008] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2008] [Revised: 12/10/2008] [Accepted: 12/11/2008] [Indexed: 02/04/2023]
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A double TRPtych: six views of transient receptor potential channels in disease and health. J Neurosci 2009; 28:11778-84. [PMID: 19005039 DOI: 10.1523/jneurosci.3929-08.2008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
At the 2008 Annual Meeting of the Society for Neuroscience, a Mini-Symposium entitled "Contributions to TRP Channels to Neurological Disease" included talks from six heads of newly established laboratories, each with a unique research focus, model system, and set of experimental tools. Some of the questions addressed in these talks include the following. What is the role of transient receptor potential (TRP) channels in pain perception? How do normally functioning TRP channels contribute to cell death pathways? What are the characteristics of TRPpathies, disease states that result from overactive or underactive TRP channels? How are TRP channels regulated by signal transduction cascades? This review summarizes recent results from those laboratories and provides six perspectives on the subject of TRP channels and disease.
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Venkatachalam K, Long AA, Elsaesser R, Nikolaeva D, Broadie K, Montell C. Motor deficit in a Drosophila model of mucolipidosis type IV due to defective clearance of apoptotic cells. Cell 2008; 135:838-51. [PMID: 19041749 DOI: 10.1016/j.cell.2008.09.041] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Revised: 07/25/2008] [Accepted: 09/17/2008] [Indexed: 11/27/2022]
Abstract
Disruption of the Transient Receptor Potential (TRP) mucolipin 1 (TRPML1) channel results in the neurodegenerative disorder mucolipidosis type IV (MLIV), a lysosomal storage disease with severe motor impairments. The mechanisms underlying MLIV are poorly understood and there is no treatment. Here, we report a Drosophila MLIV model, which recapitulates the key disease features, including abnormal intracellular accumulation of macromolecules, motor defects, and neurodegeneration. The basis for the buildup of macromolecules was defective autophagy, which resulted in oxidative stress and impaired synaptic transmission. Late-apoptotic cells accumulated in trpml mutant brains, suggesting diminished cell clearance. The accumulation of late-apoptotic cells and motor deficits were suppressed by expression of trpml(+) in neurons, glia, or hematopoietic cells. We conclude that the neurodegeneration and motor defects result primarily from decreased clearance of apoptotic cells. Since hematopoietic cells in humans are involved in clearance of apoptotic cells, our results raise the possibility that bone marrow transplantation may limit the progression of MLIV.
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Affiliation(s)
- Kartik Venkatachalam
- Departments of Biological Chemistry and Neuroscience, Center for Sensory Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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Zhang F, Jin S, Yi F, Li PL. TRP-ML1 functions as a lysosomal NAADP-sensitive Ca2+ release channel in coronary arterial myocytes. J Cell Mol Med 2008; 13:3174-85. [PMID: 18754814 PMCID: PMC3752374 DOI: 10.1111/j.1582-4934.2008.00486.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Nicotinic acid adenine dinucleotide phosphate (NAADP) is a potent intracellular Ca2+ signalling second messenger, but the mechanism of NAADP-induced Ca2+ release is still poorly understood. The present study tested the hypothesis that NAADP induces Ca2+ release from the lysosomal store via a TRP-ML1 (transient receptor potential-mucolipin 1)-mediated Ca2+ release channel in coronary arterial myocytes (CAMs). RT-PCR and Western blot analyses demonstrated that TRP-ML1 was present in CAMs, and fluorescence resonance energy transfer (FRET) detection revealed that the TRP-ML1 was closely associated with some lysosomal proteins in these CAMs. ET-1, a well-known NAADP stimulator, was found to induce a local Ca2+ burst from lysosomes followed by a global Ca2+ release. This lysosome-associated Ca2+ release was significantly inhibited in the TRP-ML1 siRNA pre-treated CAMs by 46.8 ± 12.6% in the local Ca2+ burst and 73.3 ± 14.9% in the global Ca2+ wave. In the reconstituted lysosomal channels from CAMs, NAADP activated Ca2+ release channels at concentrations of 1–1000 nM, but neither activators (1 μM IP3, 5 μM Rya) nor blockers (100 μM 2-APB, 50 μM Rya) of sarcoplasmic reticulum (SR) Ca2+ release channels had effect on the channel activity. Moreover, TRP-ML1 gene silencing reduced this NAADP-sensitive Ca2+ release channel activity in lysosomes by 71.5 ± 18.5%. Immunoprecipitation or blockade of TRP-ML1 by anti-TRP-ML1 antibodies almost abolished NAADP-induced activation of lysosomal Ca2+ channels (to 14.0 ± 4.4% of control). These results for the first time provide direct evidence that an NAADP-sensitive Ca2+ release channel is characteristic of TRP-ML1 channels.
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Affiliation(s)
- Fan Zhang
- Department of Pharmacology and Toxicology, Medical College of Virginia CampusVirginia Commonwealth University, Richmond, VA, USA
| | - Si Jin
- Department of Pharmacology and Toxicology, Medical College of Virginia CampusVirginia Commonwealth University, Richmond, VA, USA
| | - Fan Yi
- Department of Pharmacology and Toxicology, Medical College of Virginia CampusVirginia Commonwealth University, Richmond, VA, USA
| | - Pin-Lan Li
- Department of Pharmacology and Toxicology, Medical College of Virginia CampusVirginia Commonwealth University, Richmond, VA, USA
- * Correspondence to: Pin-Lan LI, M.D., Ph.D, Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, 410 North 12th Street, P.O. Box 980613, Richmond, VA 23298, USA. Tel.: (804) 828-4793; Fax: (804) 828-4794 E-mail:
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Pedersen SF, Owsianik G, Nilius B. TRP channels: an overview. Cell Calcium 2008; 38:233-52. [PMID: 16098585 DOI: 10.1016/j.ceca.2005.06.028] [Citation(s) in RCA: 544] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2005] [Accepted: 06/28/2005] [Indexed: 12/12/2022]
Abstract
The TRP ("transient receptor potential") family of ion channels now comprises more than 30 cation channels, most of which are permeable for Ca2+, and some also for Mg2+. On the basis of sequence homology, the TRP family can be divided in seven main subfamilies: the TRPC ('Canonical') family, the TRPV ('Vanilloid') family, the TRPM ('Melastatin') family, the TRPP ('Polycystin') family, the TRPML ('Mucolipin') family, the TRPA ('Ankyrin') family, and the TRPN ('NOMPC') family. The cloning and characterization of members of this cation channel family has exploded during recent years, leading to a plethora of data on the roles of TRPs in a variety of tissues and species, including mammals, insects, and yeast. The present review summarizes the most pertinent recent evidence regarding the structural and functional properties of TRP channels, focusing on the regulation and physiology of mammalian TRPs.
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Affiliation(s)
- Stine Falsig Pedersen
- Department of Biochemistry, Institute for Molecular Biology and Physiology, University of Copenhagen, Denmark
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Sagné C, Gasnier B. Molecular physiology and pathophysiology of lysosomal membrane transporters. J Inherit Metab Dis 2008; 31:258-66. [PMID: 18425435 DOI: 10.1007/s10545-008-0879-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2008] [Revised: 02/19/2008] [Accepted: 02/20/2008] [Indexed: 10/22/2022]
Abstract
In contrast to lysosomal hydrolytic enzymes, the lysosomal membrane remains poorly characterized. In particular, although the genetic study of cystinosis and sialic acid storage disorders led to the identification of two lysosomal transporters for cystine and sialic acids, respectively, ten years ago, most transporters responsible for exporting lysosomal hydrolysis products to the cytosol are still unknown at the molecular level. However, two lines of investigation recently started to fill this gap in the knowledge of lysosomal biology. First, novel proteomic approaches are now able to provide a reliable inventory of lysosomal membrane proteins. On the other hand, a novel functional approach based on intracellular trafficking mechanisms allows direct transport measurement in whole cells by redirecting recombinant lysosomal transporters to the cell surface. After surveying the current state of knowledge in this field, the review focuses on the sialic acid transporter sialin and shows how recent functional data using the above whole-cell approach shed new light on the pathogenesis of sialic acid storage disorders by revealing the existence of a residual transport activity associated with Salla disease.
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Affiliation(s)
- C Sagné
- Institut de Biologie Physico-Chimique, Centre National de la Recherche Scientifique, Université Paris 7 Denis Diderot, Paris, France
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