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Shadi Khalil, Maja Holy, Stephen Grado, Robert Fleming, Ryo Kurita, Yukio Nakamura, Adam Goldfarb
Erythroid progenitors are the largest consumers of iron in the human body. In these cells, a high flux of iron must reach the mitochondrial matrix to form sufficient heme to support hemoglobinization. Canonical erythroid iron trafficking occurs via the first transferrin receptor (TfR1)-mediated endocytosis of diferric-transferrin into recycling endosomes, where ferric iron is released, reduced, and exported to the cytosol via DMT1. However, mice lacking TfR1 or DMT1 demonstrate residual erythropoiesis, suggesting additional pathways for iron use...
June 27, 2017: Blood Advances
Marscha Hirschi, Mark A Herzik, Jinhong Wie, Yang Suo, William F Borschel, Dejian Ren, Gabriel C Lander, Seok-Yong Lee
The modulation of ion channel activity by lipids is increasingly recognized as a fundamental component of cellular signalling. The transient receptor potential mucolipin (TRPML) channel family belongs to the TRP superfamily and is composed of three members: TRPML1-TRPML3. TRPMLs are the major Ca(2+)-permeable channels on late endosomes and lysosomes (LEL). They regulate the release of Ca(2+) from organelles, which is important for various physiological processes, including organelle trafficking and fusion. Loss-of-function mutations in the MCOLN1 gene, which encodes TRPML1, cause the neurodegenerative lysosomal storage disorder mucolipidosis type IV, and a gain-of-function mutation (Ala419Pro) in TRPML3 gives rise to the varitint-waddler (Va) mouse phenotype...
October 19, 2017: Nature
Irfan V Düzen, Fethi Yavuz, Ertan Vuruskan, Erhan Saracoglu, Fatih Poyraz, Hüseyin Göksülük, Basar Candemir, Seniz Demiryürek
Atrial fibrillation (AF) is the most common arrhythmia in clinical practice and is a major cause of morbidity and mortality. The upregulation of TRP channels is believed to mediate the progression of electrical remodelling and the arrhythmogenesis of the diseased heart. However, there is limited data about the contribution of the TRP channels to development of AF. The aim of this study was to investigate leukocyte TRP channels gene expressions in non-valvular atrial fibrillation (NVAF) patients. The study included 47 NVAF patients and 47 sex and age matched controls...
August 24, 2017: Scientific Reports
Yuho Kim, David A Hood
Skeletal muscle is adaptable to exercise stimuli via the upregulation of mitochondrial biogenesis, and recent studies have suggested that autophagy also plays a role in exercise-induced muscle adaptations. However, it is still obscure how muscle regulates autophagy over the time course of training adaptations. This study examined the expression of autophagic proteins in skeletal muscle of rats exposed to chronic contractile activity (CCA; 6 h/day, 9V, 10 Hz continuous, 0.1 msec pulse duration) for 1, 3, and 7 days (n = 8/group)...
July 2017: Physiological Reports
Simone Di Paola, Anna Scotto-Rosato, Diego Luis Medina
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...
June 24, 2017: Cell Calcium
Lauren C Boudewyn, Jakub Sikora, Ladislav Kuchar, Jana Ledvinova, Yulia Grishchuk, Shirley L Wang, Kostantin Dobrenis, Steven U Walkley
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...
September 2017: Neurobiology of Disease
Huiqing Li, Wuhong Pei, Sivia Vergarajauregui, Patricia M Zerfas, Nina Raben, Shawn M Burgess, Rosa Puertollano
Mucolipidosis type IV (MLIV) is a lysosomal storage disease characterized by neurologic and ophthalmologic abnormalities. There is currently no effective treatment. MLIV is caused by mutations in MCOLN1, a lysosomal cation channel from the transient receptor potential (TRP) family. In this study, we used genome editing to knockout the two mcoln1 genes present in Danio rerio (zebrafish). Our model successfully reproduced the retinal and neuromuscular defects observed in MLIV patients, indicating that this model is suitable for studying the disease pathogenesis...
July 15, 2017: Human Molecular Genetics
Juliet R Foote, Philippe Behe, Mathew Frampton, Adam P Levine, Anthony W Segal
Neutrophils phagocytosing bacteria and fungi exhibit a burst of non-mitochondrial respiration that is required to kill and digest the engulfed microbes. This respiration is accomplished by the movement of electrons across the wall of the phagocytic vacuole by the neutrophil NADPH oxidase, NOX2. In this study, we have attempted to identify the non-proton ion channels or transporters involved in charge compensation by examining the effect of inhibitors on vacuolar pH and cross-sectional area, and on oxygen consumption...
2017: Frontiers in Pharmacology
Si Ming Man, Thirumala-Devi Kanneganti
Cysteine cathepsins are responsible for driving proteolytic degradation within the lysosome and in the extralysosomal milieu. They also have an integral role in autophagy, antigen presentation, cellular stress signaling, metabolism and lysosome-dependent cell death. Here, we discuss our findings on the role of CTSB (cathepsin B), a member of the cysteine cathepsin family, in regulating the bioavailability of lysosomes and autophagosomes and consider how this regulatory response influences host susceptibility to infectious agents...
December 2016: Autophagy
Xiaoli Zhang, Lu Yu, Haoxing Xu
Lysosomes, the cell's recycling center, undergo nutrient-sensitive adaptive changes in function and biogenesis, i.e., lysosomal adaptation. We recently discovered that lysosomes also mediate the cell's "survival" response (i.e., autophagy) to oxidative stress through the activation of TFEB (transcription factor EB), a master regulator of lysosome biogenesis and autophagy. MCOLN1/TRPML1, the principal Ca(2+) release channel on the lysosomal membrane, serves as the redox sensor in this process. Increasing reactive oxygen species (ROS) levels, either endogenously by mitochondrial damage or exogenously, directly activates MCOLN1 to induce lysosomal Ca(2+) release, triggering PPP3/calcineurin-dependent TFEB nuclear translocation to enhance autophagy...
October 2, 2016: Autophagy
Xiaoli Zhang, Xiping Cheng, Lu Yu, Junsheng Yang, Raul Calvo, Samarjit Patnaik, Xin Hu, Qiong Gao, Meimei Yang, Maria Lawas, Markus Delling, Juan Marugan, Marc Ferrer, Haoxing Xu
Cellular stresses trigger autophagy to remove damaged macromolecules and organelles. Lysosomes 'host' multiple stress-sensing mechanisms that trigger the coordinated biogenesis of autophagosomes and lysosomes. For example, transcription factor (TF)EB, which regulates autophagy and lysosome biogenesis, is activated following the inhibition of mTOR, a lysosome-localized nutrient sensor. Here we show that reactive oxygen species (ROS) activate TFEB via a lysosomal Ca(2+)-dependent mechanism independent of mTOR...
June 30, 2016: Nature Communications
Harumi Saijo, Masaharu Hayashi, Takanori Ezoe, Chihiro Ohba, Hirotomo Saitsu, Kiyoko Kurata, Naomichi Matsumoto
Mucolipidosis type IV (MLIV) is a rare neurodegenerative disorder characterized by severe psychomotor delay and visual impairment. We report the brain pathology in the first Japanese patient of MLIV with a novel homozygous missense mutation in MCOLN1. We detected the localized increase in p62-reactive astrocytes in the basal ganglia.
May 2016: Clinical Case Reports
Takashi Shiihara, Mio Watanabe, Kengo Moriyama, Yasuhiro Maruyama, Atsuo Kikuchi, Natsuko Arai-Ichinoi, Mitsugu Uematsu, Kiyoko Sameshima
BACKGROUND: Mucolipidosis IV (MLIV; OMIM #252650) is an autosomal recessive lysosomal storage disorder, frequently observed in the Ashkenazi Jewish population. MLIV typically results in intellectual disability, corneal opacities, and delayed motor milestones during infancy, with a relatively static course. To date, reports of MLIV in other ethnic groups have been sparse. PATIENT: The present study is a case report of a 9-year-old Japanese boy, diagnosed via whole-exome sequencing, with compound heterozygous mutations of MCOLN1 (OMIM(*)605248): c...
September 2016: Brain & Development
Yulia Grishchuk, Katherine G Stember, Aya Matsunaga, Ana M Olivares, Nelly M Cruz, Victoria E King, Daniel M Humphrey, Shirley L Wang, Alona Muzikansky, Rebecca A Betensky, Wallace B Thoreson, Neena Haider, Susan A Slaugenhaupt
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...
January 2016: American Journal of Pathology
Natsuko Arai-Ichinoi, Mitsugu Uematsu, Ryo Sato, Tasuku Suzuki, Hiroki Kudo, Atsuo Kikuchi, Naomi Hino-Fukuyo, Mitsuyo Matsumoto, Kazuhiko Igarashi, Kazuhiro Haginoya, Shigeo Kure
T2 hyperintensity of brain white matter lesions detected by magnetic resonance imaging (MRI) are characteristic of a heterogeneous group of diseases. Persistent T2 high intensity in combination with T1 iso- or high intensity of white matter in infants indicates a lack of normal myelination, that is, hypomyelination. However, the precise diagnosis of hypomyelinating leukodystrophy based solely on MRI findings can be difficult, especially in the early stage of the disease. We studied 26 patients who were diagnosed with hypomyelinating leukodystrophy according to MRI findings and clinical features to uncover their genetic etiology through chromosomal analyses, targeted gene analyses, and an array comparative genomic hybridization (aCGH) assay...
January 2016: Human Genetics
Julie M Huynh, Hope Dang, Isabel A Munoz-Tucker, Marvin O'Ketch, Ian T Liu, Savannah Perno, Natasha Bhuyan, Allison Crain, Ivan Borbon, Hanna Fares
Mutations in MCOLN1, which encodes the cation channel protein TRPML1, result in the neurodegenerative lysosomal storage disorder Mucolipidosis type IV. Mucolipidosis type IV patients show lysosomal dysfunction in many tissues and neuronal cell death. The ortholog of TRPML1 in Caenorhabditis elegans is CUP-5; loss of CUP-5 results in lysosomal dysfunction in many tissues and death of developing intestinal cells that results in embryonic lethality. We previously showed that a null mutation in the ATP-Binding Cassette transporter MRP-4 rescues the lysosomal defect and embryonic lethality of cup-5(null) worms...
February 2016: Genetics
Yulia Grishchuk, Karina A Peña, Jessica Coblentz, Victoria E King, Daniel M Humphrey, Shirley L Wang, Kirill I Kiselyov, Susan A Slaugenhaupt
Mucolipidosis type IV (MLIV) is a lysosomal storage disease caused by mutations in the MCOLN1 gene, which encodes the lysosomal transient receptor potential ion channel mucolipin-1 (TRPML1). MLIV causes impaired motor and cognitive development, progressive loss of vision and gastric achlorhydria. How loss of TRPML1 leads to severe psychomotor retardation is currently unknown, and there is no therapy for MLIV. White matter abnormalities and a hypoplastic corpus callosum are the major hallmarks of MLIV brain pathology...
December 2015: Disease Models & Mechanisms
Math P Cuajungco, Joshua Silva, Ania Habibi, Jessica A Valadez
The discovery of the TRPML subfamily of ion channels has created an exciting niche in the fields of membrane trafficking, signal transduction, autophagy, and metal homeostasis. The TRPML protein subfamily consists of three members, TRPML1, TRPML2, and TRPML3, which are encoded by MCOLN1, MCOLN2, and MCOLN3 genes, respectively. They are non-selective cation channels with six predicted transmembrane domains and intracellular amino- and carboxyl-terminus regions. They localize to the plasma membrane, endosomes, and lysosomes of cells...
February 2016: Pflügers Archiv: European Journal of Physiology
Rob U Onyenwoke, Jonathan Z Sexton, Feng Yan, María Cristina Huertas Díaz, Lawrence J Forsberg, Michael B Major, Jay E Brenman
Autophagy is a complex pathway regulated by numerous signalling events that recycles macromolecules and may be perturbed in lysosomal storage disorders (LSDs). During autophagy, aberrant regulation of the lysosomal Ca(2+) efflux channel TRPML1 [transient receptor potential mucolipin 1 (MCOLN1)], also known as MCOLN1, is solely responsible for the human LSD mucolipidosis type IV (MLIV); however, the exact mechanisms involved in the development of the pathology of this LSD are unknown. In the present study, we provide evidence that the target of rapamycin (TOR), a nutrient-sensitive protein kinase that negatively regulates autophagy, directly targets and inactivates the TRPML1 channel and thereby functional autophagy, through phosphorylation...
September 15, 2015: Biochemical Journal
Lorraine N Clark, Robin Chan, Rong Cheng, Xinmin Liu, Naeun Park, Nancy Parmalee, Sergey Kisselev, Etty Cortes, Paola A Torres, Gregory M Pastores, Jean P Vonsattel, Roy Alcalay, Karen Marder, Lawrence L Honig, Stanley Fahn, Richard Mayeux, Michael Shelanski, Gilbert Di Paolo, Joseph H Lee
OBJECTIVE: Variants in GBA are associated with Lewy Body (LB) pathology. We investigated whether variants in other lysosomal storage disorder (LSD) genes also contribute to disease pathogenesis. METHODS: We performed a genetic analysis of four LSD genes including GBA, HEXA, SMPD1, and MCOLN1 in 231 brain autopsies. Brain autopsies included neuropathologically defined LBD without Alzheimer Disease (AD) changes (n = 59), AD without significant LB pathology (n = 71), Alzheimer disease and lewy body variant (ADLBV) (n = 68), and control brains without LB or AD neuropathology (n = 33)...
2015: PloS One
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