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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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Huizing M, Gahl WA. Inherited disorders of lysosomal membrane transporters. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2020; 1862:183336. [PMID: 32389669 PMCID: PMC7508925 DOI: 10.1016/j.bbamem.2020.183336] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 04/01/2020] [Accepted: 04/28/2020] [Indexed: 02/07/2023]
Abstract
Disorders caused by defects in lysosomal membrane transporters form a distinct subgroup of lysosomal storage disorders (LSDs). To date, defects in only 10 lysosomal membrane transporters have been associated with inherited disorders. The clinical presentations of these diseases resemble the phenotypes of other LSDs; they are heterogeneous and often present in children with neurodegenerative manifestations. However, for pathomechanistic and therapeutic studies, lysosomal membrane transport defects should be distinguished from LSDs caused by defective hydrolytic enzymes. The involved proteins differ in function, localization, and lysosomal targeting, and the diseases themselves differ in their stored material and therapeutic approaches. We provide an overview of the small group of disorders of lysosomal membrane transporters, emphasizing discovery, pathomechanism, clinical features, diagnostic methods and therapeutic aspects. We discuss common aspects of lysosomal membrane transporter defects that can provide the basis for preclinical research into these disorders.
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Affiliation(s)
- Marjan Huizing
- Human Biochemical Genetics Section, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA.
| | - William A Gahl
- Human Biochemical Genetics Section, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Grishchuk Y, Stember KG, Matsunaga A, Olivares AM, Cruz NM, King VE, Humphrey DM, Wang SL, Muzikansky A, Betensky RA, Thoreson WB, Haider N, Slaugenhaupt SA. Retinal Dystrophy and Optic Nerve Pathology in the Mouse Model of Mucolipidosis IV. THE AMERICAN JOURNAL OF PATHOLOGY 2015; 186:199-209. [PMID: 26608452 DOI: 10.1016/j.ajpath.2015.09.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 08/31/2015] [Accepted: 09/10/2015] [Indexed: 11/19/2022]
Abstract
Mucolipidosis IV is a debilitating developmental lysosomal storage disorder characterized by severe neuromotor retardation and progressive loss of vision, leading to blindness by the second decade of life. Mucolipidosis IV is caused by loss-of-function mutations in the MCOLN1 gene, which encodes the transient receptor potential channel protein mucolipin-1. Ophthalmic pathology in patients includes corneal haze and progressive retinal and optic nerve atrophy. Herein, we report ocular pathology in Mcoln1(-/-) mouse, a good phenotypic model of the disease. Early, but non-progressive, thinning of the photoreceptor layer, reduced levels of rhodopsin, disrupted rod outer segments, and widespread accumulation of the typical storage inclusion bodies were the major histological findings in the Mcoln1(-/-) retina. Electroretinograms showed significantly decreased functional response (scotopic a- and b-wave amplitudes) in the Mcoln1(-/-) mice. At the ultrastructural level, we observed formation of axonal spheroids and decreased density of axons in the optic nerve of the aged (6-month-old) Mcoln1(-/-) mice, which indicates progressive axonal degeneration. Our data suggest that mucolipin-1 plays a role in postnatal development of photoreceptors and provides a set of outcome measures that can be used for ocular therapy development for mucolipidosis IV.
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Affiliation(s)
- Yulia Grishchuk
- Department of Neurology, Center for Human Genetic Research, Harvard Medical School, Boston, Massachusetts.
| | - Katherine G Stember
- Department of Neurology, Center for Human Genetic Research, Harvard Medical School, Boston, Massachusetts
| | - Aya Matsunaga
- Department of Neurology, Center for Human Genetic Research, Harvard Medical School, Boston, Massachusetts
| | - Ana M Olivares
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts
| | - Nelly M Cruz
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts
| | - Victoria E King
- Department of Neurology, Center for Human Genetic Research, Harvard Medical School, Boston, Massachusetts
| | - Daniel M Humphrey
- Department of Neurology, Center for Human Genetic Research, Harvard Medical School, Boston, Massachusetts
| | - Shirley L Wang
- Department of Neurology, Center for Human Genetic Research, Harvard Medical School, Boston, Massachusetts
| | - Alona Muzikansky
- Massachusetts General Hospital Biostatistics Center, Massachusetts General Hospital, Boston, Massachusetts
| | - Rebecca A Betensky
- Department of Biostatistics, Harvard School of Public Health, Boston, Massachusetts
| | - Wallace B Thoreson
- Department of Ophthalmology & Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska
| | - Neena Haider
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts
| | - Susan A Slaugenhaupt
- Department of Neurology, Center for Human Genetic Research, Harvard Medical School, Boston, Massachusetts
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The role of TRPMLs in endolysosomal trafficking and function. Cell Calcium 2014; 58:48-56. [PMID: 25465891 DOI: 10.1016/j.ceca.2014.10.008] [Citation(s) in RCA: 140] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 10/15/2014] [Accepted: 10/17/2014] [Indexed: 12/24/2022]
Abstract
Members of the Transient Receptor Potential-Mucolipin (TRPML) constitute a family of evolutionarily conserved cation channels that function predominantly in endolysosomal vesicles. Whereas loss-of-function mutations in human TRPML1 were first identified as being causative for the lysosomal storage disease, Mucolipidosis type IV, most mammals also express two other TRPML isoforms called TRPML2 and TRPML3. All three mammalian TRPMLs as well as TRPML related genes in other species including Caenorhabditis elegans and Drosophila exhibit overlapping functional and biophysical properties. The functions of TRPML proteins include roles in vesicular trafficking and biogenesis, maintenance of neuronal development, function, and viability, and regulation of intracellular and organellar ionic homeostasis. Biophysically, TRPML channels are non-selective cation channels exhibiting variable permeability to a host of cations including Na(+), Ca(2+), Fe(2+), and Zn(2+), and are activated by a phosphoinositide species, PI(3,5)P2, that is mostly found in endolysosomal membranes. Here, we review the functional and biophysical properties of these enigmatic cation channels, which represent the most ancient and archetypical TRP channels.
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Abstract
Membrane proteins remain challenging targets for structural biologists, despite recent technical developments regarding sample preparation and structure determination. We review recent progress towards a structural understanding of TRP channels and the techniques used to that end. We discuss available low-resolution structures from electron microscopy (EM), X-ray crystallography, and nuclear magnetic resonance (NMR) and review the resulting insights into TRP channel function for various subfamily members. The recent high-resolution structure of TRPV1 is discussed in more detail in Chapter 11. We also consider the opportunities and challenges of using the accumulating structural information on TRPs and homologous proteins for deducing full-length structures of different TRP channel subfamilies, such as building homology models. Finally, we close by summarizing the outlook of the "holy grail" of understanding in atomic detail the diverse functions of TRP channels.
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Taylor MC, McLatchie AP, Kelly JM. Evidence that transport of iron from the lysosome to the cytosol in African trypanosomes is mediated by a mucolipin orthologue. Mol Microbiol 2013; 89:420-32. [PMID: 23750752 PMCID: PMC3828870 DOI: 10.1111/mmi.12285] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/02/2013] [Indexed: 11/28/2022]
Abstract
Bloodstream-form Trypanosoma brucei acquire iron by receptor-mediated endocytosis of host transferrin. However, the mechanism(s) by which iron is then transferred from the lysosome to the cytosol are unresolved. Here, we provide evidence for the involvement of a protein (TbMLP) orthologous to the mammalian endolysosomal cation channel Mucolipin 1. In T. brucei, we show that this protein is localized to the single parasite lysosome. TbMLP null mutants could only be generated in the presence of an expressed ectopic copy, suggesting that the protein is essential. RNAi-mediated ablation resulted in a growth defect in vitro and led to a sevenfold increase in susceptibility to the iron-chelators deferoxamine and salicylhydroxamic acid. Conditional null mutants remained viable when the ectopic copy was repressed, but were hypersensitive to deferoxamine and displayed a growth defect similar to that observed following RNAi. The conditional nulls also retained virulence in vivo in the absence of the doxycycline inducer. These data provide strong evidence that TbMLP has a role in import of iron into the cytosol of African trypanosomes. They also indicate that even when expression is greatly reduced, there is sufficient protein, or an alternative mechanism, to provide the parasite with an adequate supply of cytosolic iron.
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Affiliation(s)
- Martin C Taylor
- Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, Keppel St., London, WC1E 7HT, UK.
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Marks DL, Holicky EL, Wheatley CL, Frumkin A, Bach G, Pagano RE. Role of protein kinase d in Golgi exit and lysosomal targeting of the transmembrane protein, Mcoln1. Traffic 2012; 13:565-75. [PMID: 22268962 DOI: 10.1111/j.1600-0854.2012.01331.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 01/19/2012] [Accepted: 01/23/2012] [Indexed: 11/27/2022]
Abstract
The targeting of lysosomal transmembrane (TM) proteins from the Golgi apparatus to lysosomes is a complex process that is only beginning to be understood. Here, the lysosomal targeting of mucolipin-1 (Mcoln1), the TM protein defective in the autosomal recessive disease, mucolipidosis type IV, was studied by overexpressing full-length and truncated forms of the protein in human cells, followed by detection using immunofluorescence and immunoblotting. We demonstrated that a 53-amino acid C-terminal region of Mcoln1 is required for efficient exit from the Golgi. Truncations lacking this region exhibited reduced delivery to lysosomes and decreased proteolytic cleavage of Mcoln1 into characteristic ∼35-kDa fragments, suggesting that this cleavage occurs in lysosomes. In addition, we found that the co-expression of full-length Mcoln1 with kinase-inactive protein kinase D (PKD) 1 or 2 inhibited Mcoln1 Golgi exit and transport to lysosomes and decreased Mcoln1 cleavage. These studies suggest that PKDs play a role in the delivery of some lysosomal resident TM proteins from the Golgi to the lysosomes.
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Affiliation(s)
- David L Marks
- Department of Medicine, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA.
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Wakabayashi K, Gustafson AM, Sidransky E, Goldin E. Mucolipidosis type IV: an update. Mol Genet Metab 2011; 104:206-13. [PMID: 21763169 PMCID: PMC3205274 DOI: 10.1016/j.ymgme.2011.06.006] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Revised: 06/09/2011] [Accepted: 06/09/2011] [Indexed: 11/28/2022]
Abstract
Mucolipidosis type IV (MLIV) is a neurodevelopmental as well as neurodegenerative disorder with severe psychomotor developmental delay, progressive visual impairment, and achlorydria. It is characterized by the presence of lysosomal inclusions in many cell types in patients. MLIV is an autosomal recessive disease caused by mutations in MCOLN1, which encodes for mucolipin-1, a member of the transient receptor potential (TRP) cation channel family. Although approximately 70-80% of patients identified are Ashkenazi Jewish, MLIV is a pan-ethnic disorder. Importantly, while MLIV is thought to be a rare disease, its frequency may be greater than currently appreciated, for its common presentation as a cerebral palsy-like encephalopathy can lead to misdiagnosis. Moreover, patients with milder variants are often not recognized as having MLIV. This review provides an update on the ethnic distribution, clinical manifestations, laboratory findings, methods of diagnosis, molecular genetics, differential diagnosis, and treatment of patients with MLIV. An enhanced awareness of the manifestations of this disorder may help to elucidate the true frequency and range of symptoms associated with MLIV, providing insight into the pathogenesis of this multi-system disease.
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Affiliation(s)
| | | | - Ellen Sidransky
- Section on Molecular Neurogenetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Building 35, Room 1A213, 35 Convent Dr., MSC 3708, Bethesda, MD 20892-3708
| | - Ehud Goldin
- Section on Molecular Neurogenetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Building 35, Room 1A213, 35 Convent Dr., MSC 3708, Bethesda, MD 20892-3708
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Invertebrate models of lysosomal storage disease: what have we learned so far? INVERTEBRATE NEUROSCIENCE 2011; 11:59-71. [PMID: 22038288 DOI: 10.1007/s10158-011-0125-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 10/08/2011] [Indexed: 01/17/2023]
Abstract
The lysosomal storage diseases (LSDs) collectively account for death in 1 in 8,000 children. Although some forms are treatable, they are essentially incurable and usually are lethal in the first decade of life. The most intractable forms of LSD are those with neuronal involvement. In an effort to identify the pathological signaling driving pathology in the LSDs, invertebrate models have been developed. In this review, we outline our current understanding of LSDs and recent findings using invertebrate models. We outline strategies and pitfalls for the development of such models. Available models of LSD in Drosophila and Caenorhabditis elegans are uncovering roles for LSD-related proteins with previously unknown function using both gain-of-function and loss-of-function strategies. These models of LSD in Drosophila and C. elegans have identified potential pathogenic signaling cascades that are proving critical to our understanding of these lethal diseases.
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