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Patterson K, Chong JX, Chung DD, Lisch W, Karp CL, Dreisler E, Lockington D, Rohrbach JM, Garczarczyk-Asim D, Müller T, Tuft SJ, Skalicka P, Wilnai Y, Samra NN, Ibrahim A, Mandel H, Davidson AE, Liskova P, Aldave AJ, Bamshad MJ, Janecke AR. Lisch Epithelial Corneal Dystrophy Is Caused by Heterozygous Loss-of-Function Variants in MCOLN1. Am J Ophthalmol 2024; 258:183-195. [PMID: 37972748 DOI: 10.1016/j.ajo.2023.10.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 10/19/2023] [Accepted: 10/20/2023] [Indexed: 11/19/2023]
Abstract
PURPOSE To report the genetic etiology of Lisch epithelial corneal dystrophy (LECD). DESIGN Multicenter cohort study. METHODS A discovery cohort of 27 individuals with LECD from 17 families, including 7 affected members from the original LECD family, 6 patients from 2 new families and 14 simplex cases, was recruited. A cohort of 6 individuals carrying a pathogenic MCOLN1 (mucolipin 1) variant was reviewed for signs of LECD. Next-generation sequencing or targeted Sanger sequencing were used in all patients to identify pathogenic or likely pathogenic variants and penetrance of variants. RESULTS Nine rare heterozygous MCOLN1 variants were identified in 23 of 27 affected individuals from 13 families. The truncating nature of 7 variants and functional testing of 1 missense variant indicated that they result in MCOLN1 haploinsufficiency. Importantly, in the homozygous and compound-heterozygous state, 4 of 9 LECD-associated variants cause the rare lysosomal storage disorder mucolipidosis IV (MLIV). Autosomal recessive MLIV is a systemic disease and comprises neurodegeneration as well as corneal opacity of infantile-onset with epithelial autofluorescent lysosomal inclusions. However, the 6 parents of 3 patients with MLIV confirmed to carry pathogenic MCOLN1 variants did not have the LECD phenotype, suggesting MCOLN1 haploinsufficiency may be associated with reduced penetrance and variable expressivity. CONCLUSIONS MCOLN1 haploinsufficiency is the major cause of LECD. Based on the overlapping clinical features of corneal epithelial cells with autofluorescent inclusions reported in both LECD and MLIV, it is concluded that some carriers of MCOLN1 haploinsufficiency-causing variants present with LECD.
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Affiliation(s)
- Karynne Patterson
- From the Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA (K.P., M.J.B.)
| | - Jessica X Chong
- Department of Pediatrics and Brotman-Baty Institute for Precision Medicine, University of Washington, Seattle, WA 98195, USA (J.X.C.)
| | - Doug D Chung
- Department of Ophthalmology, Stein Eye Institute, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA (D.D.C., A.J.A.)
| | - Walter Lisch
- Department of Ophthalmology, University Medical Center of the Johannes Gutenberg- University Mainz, 55131 Mainz, Germany (W.L.)
| | - Carol L Karp
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller, School of Medicine, Miami, USA (C.L.K.)
| | - Erling Dreisler
- Independent scholar, N.Jespersensvej 3, DK-2000 Copenhagen, Frederiksberg, Denmark (E.D.)
| | - David Lockington
- Tennent Institute of Ophthalmology, NHS Greater Glasgow and Clyde, Gartnavel General Hospital, 1053 Great Western Road, Glasgow, G12 0YN, UK (D.L.)
| | - Jens M Rohrbach
- Universitäts-Augenklinik, Elfriede-Aulhorn-Str. 7, 72076, Tübingen, Deutschland (J.M.R.)
| | - Dorota Garczarczyk-Asim
- Department of Pediatrics I, Medical University of Innsbruck, 6020 Innsbruck, Austria (D.G.-A., T.M., A.R.J.)
| | - Thomas Müller
- Department of Pediatrics I, Medical University of Innsbruck, 6020 Innsbruck, Austria (D.G.-A., T.M., A.R.J.)
| | - Stephen J Tuft
- Moorfields eye hospital NHS foundation trust, London, UK (S.J.T.); UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK (A.E.D.)
| | - Pavlina Skalicka
- Department of Ophthalmology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic (P.S., P.L.)
| | - Yael Wilnai
- Genetic Institute, Tel Aviv Sourasky Medical Center, Tel Aviv 6423906, Israel (Y.W.)
| | - Nadra Naser Samra
- Genetic Unit, Sieff hospital, Bar Ilan University Faculty of Medicine, Safed, Israel (N.N.S.)
| | - Ali Ibrahim
- Ophthalmology unit, Maccabi and Clalit Health Services, Magdal Shams Medical center, Golan Heights, Israel (A.I.)
| | - Hanna Mandel
- Pediatric Metabolic Clinic, Sieff hospital, Bar Ilan University Faculty of Medicine, Safed, Israel (H.M.)
| | - Alice E Davidson
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK (A.E.D.)
| | - Petra Liskova
- Department of Ophthalmology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic (P.S., P.L.); Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic (P.S.,P.L.)
| | - Anthony J Aldave
- Department of Ophthalmology, Stein Eye Institute, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA (D.D.C., A.J.A.)
| | - Michael J Bamshad
- From the Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA (K.P., M.J.B.); Department of Pediatrics and Brotman-Baty Institute for Precision Medicine, University of Washington, Seattle, WA 98195, USA (J.X.C.)
| | - Andreas R Janecke
- Department of Pediatrics I, Medical University of Innsbruck, 6020 Innsbruck, Austria (D.G.-A., T.M., A.R.J.); Division of Human Genetics, Medical University of Innsbruck, 6020 Innsbruck, Austria (A.R.J.).
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Križaj D, Cordeiro S, Strauß O. Retinal TRP channels: Cell-type-specific regulators of retinal homeostasis and multimodal integration. Prog Retin Eye Res 2023; 92:101114. [PMID: 36163161 PMCID: PMC9897210 DOI: 10.1016/j.preteyeres.2022.101114] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 08/03/2022] [Accepted: 08/08/2022] [Indexed: 02/05/2023]
Abstract
Transient receptor potential (TRP) channels are a widely expressed family of 28 evolutionarily conserved cationic ion channels that operate as primary detectors of chemical and physical stimuli and secondary effectors of metabotropic and ionotropic receptors. In vertebrates, the channels are grouped into six related families: TRPC, TRPV, TRPM, TRPA, TRPML, and TRPP. As sensory transducers, TRP channels are ubiquitously expressed across the body and the CNS, mediating critical functions in mechanosensation, nociception, chemosensing, thermosensing, and phototransduction. This article surveys current knowledge about the expression and function of the TRP family in vertebrate retinas, which, while dedicated to transduction and transmission of visual information, are highly susceptible to non-visual stimuli. Every retinal cell expresses multiple TRP subunits, with recent evidence establishing their critical roles in paradigmatic aspects of vertebrate vision that include TRPM1-dependent transduction of ON bipolar signaling, TRPC6/7-mediated ganglion cell phototransduction, TRP/TRPL phototransduction in Drosophila and TRPV4-dependent osmoregulation, mechanotransduction, and regulation of inner and outer blood-retina barriers. TRP channels tune light-dependent and independent functions of retinal circuits by modulating the intracellular concentration of the 2nd messenger calcium, with emerging evidence implicating specific subunits in the pathogenesis of debilitating diseases such as glaucoma, ocular trauma, diabetic retinopathy, and ischemia. Elucidation of TRP channel involvement in retinal biology will yield rewards in terms of fundamental understanding of vertebrate vision and therapeutic targeting to treat diseases caused by channel dysfunction or over-activation.
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Affiliation(s)
- David Križaj
- Departments of Ophthalmology, Neurobiology, and Bioengineering, University of Utah, Salt Lake City, USA
| | - Soenke Cordeiro
- Institute of Physiology, Faculty of Medicine, Christian-Albrechts-University Kiel, Germany
| | - Olaf Strauß
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, a Corporate Member of Freie Universität, Humboldt-University, The Berlin Institute of Health, Berlin, Germany.
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Gibson D, Brar V, Li R, Kalra A, Goodwin A, Couser N. The High Association of Ophthalmic Manifestations in Individuals With Mucolipidosis Type IV. J Pediatr Ophthalmol Strabismus 2022; 59:332-337. [PMID: 35192386 DOI: 10.3928/01913913-20211206-03] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To present a case report of mucolipidosis type IV (ML4) and review the literature for all of the ophthalmic abnormalities associated with this disease. METHODS A systematic review of the literature using PubMed/Medline was conducted, and with the addition of the current case report, the eye and ocular adnexa findings of 93 patients with ML4 are summarized. RESULTS The most common ophthalmic findings reported among the 93 patients included corneal clouding (90.3%), strabismus (58.1%), optic nerve pallor (52.2%), retinal dystrophy/pigmentary changes (50.5%), and retinal vascular attenuation (38.9%). Other less commonly reported findings included nystagmus, photophobia, ocular pain, excessive lacrimation, ptosis, and cataracts. CONCLUSIONS The ophthalmic findings discussed in the current case report and literature review serve as indicators for ML4. Early diagnosis of ML4 is important in forming a multidisciplinary management plan, genetic counseling strategy, and maximizing the visual development of affected individuals. [J Pediatr Ophthalmol Strabimus. 2022;59(5):332-337.].
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Misko AL, Wood LB, DeBono M, Oberman R, Raas-Rothschild A, Grishchuk Y, Eichler F. Cross-sectional Observations on the Natural History of Mucolipidosis Type IV. Neurol Genet 2022; 8:e662. [PMID: 35425852 PMCID: PMC9005048 DOI: 10.1212/nxg.0000000000000662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 01/04/2022] [Indexed: 11/18/2022]
Abstract
Background and Objectives Mucolipidosis type IV (MLIV) is an ultra-rare lysosomal disorder initially described as a static neurodevelopmental condition. However, patient caregivers frequently report progressive muscular hypertonicity and functional decline. We evaluated a cohort of patients with MLIV to determine whether neurologic disability correlates with age. Methods We performed a cross-sectional, observational study of 26 patients with MLIV in the United States and Israel ranging in age from 2 to 40 years. Medical history was obtained from caregivers, and patients underwent a full neurologic examination. The Brief Assessment of Motor Function (BAMF), Gross Motor Function Classification System, and modified Ashworth scales were applied. Caregivers identified developmental skills on the Oregon Project for Visually Impaired and Blind Children checklist that their child had lost the ability to perform. Results Three patients were clinically classified as mildly affected and the remaining 23 patients as typical, severely affected cases. Timing of first symptom onset ranged from 1.5 months to 8 years of age (median 7.25 months). Across typical patients, modified Ashworth scores demonstrated a positive age dependence illustrating worsening spasticity across the lifespan. Signs of extrapyramidal motor dysfunction were also qualitatively observed. In parallel, gross and fine motor function assessed with the BAMF and Gross Motor Function Classification System scales declined across age. All typical patients had restricted tongue mobility and lacked rotary jaw movement when chewing, but BAMF scores for deglutition declined only in the oldest patients. In contrast, scores for articulation were low in all patients and did not correlate with age. Finally, loss of developmental skills frequently occurred in early adolescence. Discussion This cross-sectional natural history study of MLIV demonstrates worse motor function in older patients. These data support a neurodegenerative component of MLIV that manifests as developmental regression in the second decade of life. Whether the emergence of functional decline results from the cumulative, nonlinear interactions of steadily progressive neurodegenerative processes or reflects an inflection from impaired CNS development to degeneration is uncertain. However, understanding the relationship between CNS pathology and clinical course of disease will be imperative to guiding future interventional trials and optimizing patient care.
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Yan Y, Wang Y, Ding J, Lu L, Ke GJ, Dong K. TRPML1 Inhibited Photoreceptor Apoptosis and Protected the Retina by Activation of Autophagy in Experimental Retinal Detachment. Ophthalmic Res 2020; 64:587-594. [PMID: 33027790 DOI: 10.1159/000512104] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 09/23/2020] [Indexed: 11/19/2022]
Abstract
OBJECTIVE In this study, we used a rat model of retinal detachment (RD) to investigate the effects of transient receptor potential mucolipin 1 (TRPML1) on photoreceptor cells and the underlying mechanism. METHODS An RD model was established by subretinal injection of sodium hyaluronate, and mucolipin synthetic agonist 1 (ML-SA1) and dimethyl sulphoxide were subretinally injected after RD induction. Retinal morphology was observed using haematoxylin-eosin staining, and the apoptosis of photoreceptor cells was detected by transmission electron microscopy. Reactive oxygen species (ROS) were examined with an ROS detection kit. The retinal expression levels of TRPML1, the autophagy-related protein microtubule-associated protein 1 light chain 3 (LC3), Beclin 1, and cleaved caspase 3 were detected by Western blotting. The Morris water maze was used to test vision-dependent behaviour. RESULTS We found that retinal structure and the outer nuclear layer were improved and that the apoptosis of photoreceptor cells was reduced after ML-SA1 injection. The expression of ROS was reduced, and the loss of TRPML1 was inhibited after ML-SA1 treatment. The LC3-II to LC3-I ratio and Beclin 1 expression were enhanced, and cleaved caspase 3 expression was decreased after ML-SA1 treatment. Treatment with ML-SA1 also improved vision-dependent behaviour. CONCLUSIONS Our findings suggest that ML-SA1 attenuates photoreceptor apoptosis and improves vision-dependent behaviour by activation of autophagy.
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Affiliation(s)
- Yuanye Yan
- Department of Ophthalmology, Eye Center, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Yisai Wang
- Department of Ophthalmology, Anhui Medical University, Hefei, China
| | - Jie Ding
- Department of Ophthalmology, The Second People's Hospital of Hefei, Hefei, China
| | - Li Lu
- Department of Ophthalmology, Eye Center, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Gen-Jie Ke
- Department of Ophthalmology, Eye Center, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.,Shanghai General Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Kai Dong
- Department of Ophthalmology, Eye Center, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
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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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Boudewyn LC, Walkley SU. Current concepts in the neuropathogenesis of mucolipidosis type IV. J Neurochem 2019; 148:669-689. [PMID: 29770442 PMCID: PMC6239999 DOI: 10.1111/jnc.14462] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 04/29/2018] [Accepted: 05/02/2018] [Indexed: 12/11/2022]
Abstract
Mucolipidosis type IV (MLIV) is an autosomal recessive, lysosomal storage disorder causing progressively severe intellectual disability, motor and speech deficits, retinal degeneration often culminating in blindness, and systemic disease causing a shortened lifespan. MLIV results from mutations in the gene MCOLN1 encoding the transient receptor potential channel mucolipin-1. It is an ultra-rare disease and is currently known to affect just over 100 diagnosed individuals. The last decade has provided a wealth of research focused on understanding the role of the enigmatic mucolipin-1 protein in cell and brain function and how its absence causes disease. This review explores our current understanding of the mucolipin-1 protein in relation to neuropathogenesis in MLIV and describes recent findings implicating mucolipin-1's important role in mechanistic target of rapamycin and TFEB (transcription factor EB) signaling feedback loops as well as in the function of the greater endosomal/lysosomal system. In addition to addressing the vital role of mucolipin-1 in the brain, we also report new data on the question of whether haploinsufficiency as would be anticipated in MCOLN1 heterozygotes is associated with any evidence of neuron dysfunction or disease. Greater insights into the role of mucolipin-1 in the nervous system can be expected to shed light not only on MLIV disease but also on numerous processes governing normal brain function. This article is part of the Special Issue "Lysosomal Storage Disorders".
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Affiliation(s)
- Lauren C. Boudewyn
- Dominick P. Purpura Department of Neuroscience, Rose F. Kennedy Intellectual and Developmental Disabilities Research Center, Albert Einstein College of Medicine, Bronx, New York
| | - Steven U. Walkley
- Dominick P. Purpura Department of Neuroscience, Rose F. Kennedy Intellectual and Developmental Disabilities Research Center, Albert Einstein College of Medicine, Bronx, New York
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Gómez NM, Lu W, Lim JC, Kiselyov K, Campagno KE, Grishchuk Y, Slaugenhaupt SA, Pfeffer BA, Fliesler SJ, Mitchell CH. Robust lysosomal calcium signaling through channel TRPML1 is impaired by lysosomal lipid accumulation. FASEB J 2018; 32:782-794. [PMID: 29030399 PMCID: PMC5888396 DOI: 10.1096/fj.201700220rr] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 09/26/2017] [Indexed: 12/20/2022]
Abstract
The transient receptor potential cation channel mucolipin 1 (TRPML1) channel is a conduit for lysosomal calcium efflux, and channel activity may be affected by lysosomal contents. The lysosomes of retinal pigmented epithelial (RPE) cells are particularly susceptible to build-up of lysosomal waste products because they must degrade the outer segments phagocytosed daily from adjacent photoreceptors; incomplete degradation leads to accumulation of lipid waste in lysosomes. This study asks whether stimulation of TRPML1 can release lysosomal calcium in RPE cells and whether such release is affected by lysosomal accumulations. The TRPML agonist ML-SA1 raised cytoplasmic calcium levels in mouse RPE cells, hesRPE cells, and ARPE-19 cells; this increase was rapid, robust, reversible, and reproducible. The increase was not altered by extracellular calcium removal or by thapsigargin but was eliminated by lysosomal rupture with glycyl-l-phenylalanine-β-naphthylamide. Treatment with desipramine to inhibit acid sphingomyelinase or YM201636 to inhibit PIKfyve also reduced the cytoplasmic calcium increase triggered by ML-SA1, whereas RPE cells from TRPML1-/- mice showed no response to ML-SA1. Cotreatment with chloroquine and U18666A induced formation of neutral, autofluorescent lipid in RPE lysosomes and decreased lysosomal Ca2+ release. Lysosomal Ca2+ release was also impaired in RPE cells from the ATP-binding cassette, subfamily A, member 4-/- mouse model of Stargardt's retinal dystrophy. Neither TRPML1 mRNA nor total lysosomal calcium levels were altered in these models, suggesting a more direct effect on the channel. In summary, stimulation of TRPML1 elevates cytoplasmic calcium levels in RPE cells, but this response is reduced by lysosomal accumulation.-Gómez, N. M., Lu, W. Lim, J. C., Kiselyov, K., Campagno, K. E., Grishchuk, Y., Slaugenhaupt, S. A., Pfeffer, B., Fliesler, S. J., Mitchell, C. H. Robust lysosomal calcium signaling through channel TRPML1 is impaired by lysosomal lipid accumulation.
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Affiliation(s)
- Néstor Más Gómez
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Wennan Lu
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jason C. Lim
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Kirill Kiselyov
- Department of Biological Science, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Keith E. Campagno
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Yulia Grishchuk
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, Massachusetts, USA
- Department of Neurology, Massachusetts General Hospital Research Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Susan A. Slaugenhaupt
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, Massachusetts, USA
- Department of Neurology, Massachusetts General Hospital Research Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Bruce A. Pfeffer
- Department of Ophthalmology, Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York (SUNY)–University at Buffalo, Buffalo, New York, USA
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York (SUNY)–University at Buffalo, Buffalo, New York, USA
- State University of New York (SUNY)–Eye Institute, Buffalo, New York, USA
- Research Service, Veterans Affairs Western New York Healthcare System, Buffalo, New York, USA
| | - Steven J. Fliesler
- Department of Ophthalmology, Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York (SUNY)–University at Buffalo, Buffalo, New York, USA
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York (SUNY)–University at Buffalo, Buffalo, New York, USA
- State University of New York (SUNY)–Eye Institute, Buffalo, New York, USA
- Research Service, Veterans Affairs Western New York Healthcare System, Buffalo, New York, USA
| | - Claire H. Mitchell
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Physiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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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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Di Paola S, Scotto-Rosato A, Medina DL. TRPML1: The Ca (2+)retaker of the lysosome. Cell Calcium 2017; 69:112-121. [PMID: 28689729 DOI: 10.1016/j.ceca.2017.06.006] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 06/16/2017] [Accepted: 06/16/2017] [Indexed: 12/27/2022]
Abstract
Efficient functioning of lysosome is necessary to ensure the correct performance of a variety of intracellular processes such as degradation of cargoes coming from the endocytic and autophagic pathways, recycling of organelles, and signaling mechanisms involved in cellular adaptation to nutrient availability. Mutations in lysosomal genes lead to more than 50 lysosomal storage disorders (LSDs). Among them, mutations in the gene encoding TRPML1 (MCOLN1) cause Mucolipidosis type IV (MLIV), a recessive LSD characterized by neurodegeneration, psychomotor retardation, ophthalmologic defects and achlorhydria. At the cellular level, MLIV patient fibroblasts show enlargement and engulfment of the late endo-lysosomal compartment, autophagy impairment, and accumulation of lipids and glycosaminoglycans. TRPML1 is the most extensively studied member of a small family of genes that also includes TRPML2 and TRPML3, and it has been found to participate in vesicular trafficking, lipid and ion homeostasis, and autophagy. In this review we will provide an update on the latest and more novel findings related to the functions of TRPMLs, with particular focus on the emerging role of TRPML1 and lysosomal calcium signaling in autophagy. Moreover, we will also discuss new potential therapeutic approaches for MLIV and LSDs based on the modulation of TRPML1-mediated signaling.
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Affiliation(s)
- Simone Di Paola
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, 80078 Pozzuoli ,NA, Italy
| | - Anna Scotto-Rosato
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, 80078 Pozzuoli ,NA, Italy
| | - Diego Luis Medina
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, 80078 Pozzuoli ,NA, Italy.
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Lacritin and other autophagy associated proteins in ocular surface health. Exp Eye Res 2015; 144:4-13. [PMID: 26318608 DOI: 10.1016/j.exer.2015.08.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 07/20/2015] [Accepted: 08/18/2015] [Indexed: 12/19/2022]
Abstract
Advantage may be taken of macroautophagy ('autophagy') to promote ocular health. Autophagy continually captures aged or damaged cellular material for lysosomal degradation and recyling. When autophagic flux is chronically elevated, or alternatively deficient, health suffers. Chronic elevation of flux and stress are the consequence of inflammatory cytokines or of dry eye tears but not normal tears invitro. Exogenous tear protein lacritin transiently accelerates flux to restore homeostasis invitro and corneal health invivo, and yet the monomeric active form of lacritin appears to be selectively deficient in dry eye. Tissue transglutaminase-dependent cross-linking of monomer decreases monomer quantity and monomer affinity for coreceptor syndecan-1 thereby abrogating activity. Tissue transglutaminase is elevated in dry eye. Mutation of arylsulfatase A, arylsulfatase B, ceroid-lipofuscinosis neuronal 3, mucolipin, or Niemann-Pick disease type C1 respectively underlie several diseases of apparently insufficient autophagic flux that affect the eye, including: metachromatic leukodystrophy, mucopolysaccharidosis type VI, juvenile-onset Batten disease, mucolipidosis IV, and Niemann-Pick type C associated with myelin sheath destruction of corneal sensory and ciliary nerves and of the optic nerve; corneal clouding, ocular hypertension, glaucoma and optic nerve atrophy; accumulation of 'ceroid-lipofuscin' in surface conjunctival cells, and in ganglion and neuronal cells; decreased visual acuity and retinal dystrophy; and neurodegeneration. For some, enzyme or gene replacement, or substrate reduction, therapy is proving to be successful. Here we discuss examples of restoring ocular surface homeostasis through alteration of autophagy, with particular attention to lacritin.
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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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Dong XP, Wang X, Shen D, Chen S, Liu M, Wang Y, Mills E, Cheng X, Delling M, Xu H. Activating mutations of the TRPML1 channel revealed by proline-scanning mutagenesis. J Biol Chem 2009; 284:32040-52. [PMID: 19638346 PMCID: PMC2797275 DOI: 10.1074/jbc.m109.037184] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Indexed: 11/06/2022] Open
Abstract
The mucolipin TRP (TRPML) proteins are a family of endolysosomal cation channels with genetically established importance in humans and rodent. Mutations of human TRPML1 cause type IV mucolipidosis, a devastating pediatric neurodegenerative disease. Our recent electrophysiological studies revealed that, although a TRPML1-mediated current can only be recorded in late endosome and lysosome (LEL) using the lysosome patch clamp technique, a proline substitution in TRPML1 (TRPML1(V432P)) results in a large whole cell current. Thus, it remains unknown whether the large TRPML1(V432P)-mediated current results from an increased surface expression (trafficking), elevated channel activity (gating), or both. Here we performed systemic Pro substitutions in a region previously implicated in the gating of various 6 transmembrane cation channels. We found that several Pro substitutions displayed gain-of-function (GOF) constitutive activities at both the plasma membrane (PM) and endolysosomal membranes. Although wild-type TRPML1 and non-GOF Pro substitutions localized exclusively in LEL and were barely detectable in the PM, the GOF mutations with high constitutive activities were not restricted to LEL compartments, and most significantly, exhibited significant surface expression. Because lysosomal exocytosis is Ca(2+)-dependent, constitutive Ca(2+) permeability due to Pro substitutions may have resulted in stimulus-independent intralysosomal Ca(2+) release, hence the surface expression and whole cell current of TRPML1. Indeed, surface staining of lysosome-associated membrane protein-1 (Lamp-1) was dramatically increased in cells expressing GOF TRPML1 channels. We conclude that TRPML1 is an inwardly rectifying, proton-impermeable, Ca(2+) and Fe(2+)/Mn(2+) dually permeable cation channel that may be gated by unidentified cellular mechanisms through a conformational change in the cytoplasmic face of the transmembrane 5 (TM5). Furthermore, activation of TRPML1 in LEL may lead to the appearance of TRPML1 proteins at the PM.
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Affiliation(s)
- Xian-ping Dong
- From the Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 and
| | - Xiang Wang
- From the Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 and
| | - Dongbiao Shen
- From the Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 and
| | - Su Chen
- From the Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 and
| | - Meiling Liu
- From the Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 and
| | - Yanbin Wang
- From the Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 and
| | - Eric Mills
- From the Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 and
| | - Xiping Cheng
- From the Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 and
| | - Markus Delling
- the Department of Cardiology, Children's Hospital Boston, Boston, Massachusetts 02115
| | - Haoxing Xu
- From the Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 and
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Neuropathology of the Mcoln1(-/-) knockout mouse model of mucolipidosis type IV. J Neuropathol Exp Neurol 2009; 68:125-35. [PMID: 19151629 DOI: 10.1097/nen.0b013e3181942cf0] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The recently developed Mcoln1(-/-) knockout mouse provides a novel model for analyzing mucolipin 1 function and mucolipidosis type IV disease. Here we characterize the neuropathology of Mcoln1(-/-) mouse at the end stage. Evidence of ganglioside accumulation, including increases in GM2, GM3, and GD3 and redistribution of GM1, was found throughout the central nervous system (CNS) independent of significant cholesterol accumulation. Unexpectedly, colocalization studies using immunofluorescence confocal microscopy revealed that GM1 and GM2 were present in separate vesicles within individual neurons. While GM2 was significantly colocalized with LAMP2, consistent with late-endosomal/lysosomal processing, some GM2-immunoreactivity occurred in LAMP2-negative sites, suggesting involvement of other vesicular systems. P62/Sequestosome 1 (P62/SQSTM1) inclusions were also identified in the CNS of the Mcoln1(-/-) mouse, suggesting deficiencies in protein degradation. Glial cell activation was increased in brain, and there was evidence of reduced myelination in cerebral and cerebellar white matter tracts. Autofluorescent material accumulated throughout the brains of the knockout mice. Finally, axonal spheroids were prevalent in white matter tracts and Purkinje cell axons. This neuropathological characterization of the Mcoln1(-/-) mouse provides an important step in understanding how mucolipin 1 loss of function affects the CNS and contributes to mucolipidosis type IV disease.
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Abstract
TRPML1, TRPML2 and TRPML3 belong to the mucolipin family of the TRP superfamily of ion channels. The founding member of this family, TRPML1, was cloned during the search for the genetic determinants of the lysosomal storage disease mucolipidosis type IV (MLIV). Mucolipins are predominantly expressed within the endocytic pathway, where they appear to regulate membrane traffic and/or degradation. The physiology of mucolipins raises some of the most interesting questions of modern cell biology. Their traffic and localization is a multistep process involving a system of adaptor proteins, while their ion channel activity possibly exemplifies the rare cases of regulation of endocytic traffic and hydrolysis by ion channels. Finally, dysregulation of mucolipins results in cell death leading to neurodegenerative phenotypes of MLIV and of the varitint-waddler mouse model of familial deafness. The present review discusses current knowledge and questions regarding this novel family of disease-relevant ion channels with a specific focus on mucolipin regulation and their role in membrane traffic and cell death. Since mucolipins are ubiquitously expressed, this review may be useful for a wide audience of basic biologists and clinicians.
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Affiliation(s)
- Rosa Puertollano
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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