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Nature Communications Sep 2022The mannose-6-phosphate (M6P) biosynthetic pathway for lysosome biogenesis has been studied for decades and is considered a well-understood topic. However, whether this...
The mannose-6-phosphate (M6P) biosynthetic pathway for lysosome biogenesis has been studied for decades and is considered a well-understood topic. However, whether this pathway is regulated remains an open question. In a genome-wide CRISPR/Cas9 knockout screen, we discover TMEM251 as the first regulator of the M6P modification. Deleting TMEM251 causes mistargeting of most lysosomal enzymes due to their loss of M6P modification and accumulation of numerous undigested materials. We further demonstrate that TMEM251 localizes to the Golgi and is required for the cleavage and activity of GNPT, the enzyme that catalyzes M6P modification. In zebrafish, TMEM251 deletion leads to severe developmental defects including heart edema and skeletal dysplasia, which phenocopies Mucolipidosis Type II. Our discovery provides a mechanism for the newly discovered human disease caused by TMEM251 mutations. We name TMEM251 as GNPTAB cleavage and activity factor (GCAF) and its related disease as Mucolipidosis Type V.
Topics: Animals; Humans; Lysosomes; Mannosephosphates; Membrane Proteins; Mucolipidoses; Transferases (Other Substituted Phosphate Groups); Zebrafish
PubMed: 36096887
DOI: 10.1038/s41467-022-33025-1 -
Science (New York, N.Y.) Oct 2022Lysosomes are key degradative compartments of the cell. Transport to lysosomes relies on GlcNAc-1-phosphotransferase-mediated tagging of soluble enzymes with mannose...
Lysosomes are key degradative compartments of the cell. Transport to lysosomes relies on GlcNAc-1-phosphotransferase-mediated tagging of soluble enzymes with mannose 6-phosphate (M6P). GlcNAc-1-phosphotransferase deficiency leads to the severe lysosomal storage disorder mucolipidosis II (MLII). Several viruses require lysosomal cathepsins to cleave structural proteins and thus depend on functional GlcNAc-1-phosphotransferase. We used genome-scale CRISPR screens to identify lysosomal enzyme trafficking factor (LYSET, also named TMEM251) as essential for infection by cathepsin-dependent viruses including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). LYSET deficiency resulted in global loss of M6P tagging and mislocalization of GlcNAc-1-phosphotransferase from the Golgi complex to lysosomes. knockout mice exhibited MLII-like phenotypes, and human pathogenic LYSET alleles failed to restore lysosomal sorting defects. Thus, LYSET is required for correct functioning of the M6P trafficking machinery and mutations in LYSET can explain the phenotype of the associated disorder.
Topics: Animals; COVID-19; Cathepsins; Humans; Lysosomes; Mannose; Mice; Mice, Knockout; Mucolipidoses; Proteins; Transferases (Other Substituted Phosphate Groups)
PubMed: 36074821
DOI: 10.1126/science.abn5648 -
Proceedings of the National Academy of... Aug 2022The mannose-6-phosphate (M6P) pathway is responsible for the transport of hydrolytic enzymes to lysosomes. N-acetylglucosamine-1-phosphotransferase (GNPT) catalyzes the...
The mannose-6-phosphate (M6P) pathway is responsible for the transport of hydrolytic enzymes to lysosomes. N-acetylglucosamine-1-phosphotransferase (GNPT) catalyzes the first step of tagging these hydrolases with M6P, which when recognized by receptors in the Golgi diverts them to lysosomes. Genetic defects in the GNPT subunits, GNPTAB and GNPTG, cause the lysosomal storage diseases mucolipidosis types II and III. To better understand its function, we determined partial three-dimensional structures of the GNPT complex. The catalytic domain contains a deep cavity for binding of uridine diphosphate--acetylglucosamine, and the surrounding residues point to a one-step transfer mechanism. An isolated structure of the gamma subunit of GNPT reveals that it can bind to mannose-containing glycans in different configurations, suggesting that it may play a role in directing glycans into the active site. These findings may facilitate the development of therapies for lysosomal storage diseases.
Topics: Catalytic Domain; Humans; Lysosomal Storage Diseases; Lysosomes; Mannosephosphates; Mucolipidoses; Transferases (Other Substituted Phosphate Groups)
PubMed: 35939698
DOI: 10.1073/pnas.2203518119 -
Zhonghua Yi Xue Yi Chuan Xue Za Zhi =... Aug 2022To analyze the characteristics of lysosomal enzymes in mucolipidosis (ML) type II α/β and type III α/β for the choice of enzyme evaluating indicators.
OBJECTIVE
To analyze the characteristics of lysosomal enzymes in mucolipidosis (ML) type II α/β and type III α/β for the choice of enzyme evaluating indicators.
METHODS
Multiple lysosomal enzymes including α-iduronidase (IDUA), α -N-acetylglucosaminidase (NAGLU), β-galactosidase-1 (GLB1), β-glucuronidase (GUSB), α-galactosidase A (GLA), glucocerebrosidase (GBA) and arylsulphatase A (ASA) in plasma and leukocyte of two Chinese pedigrees with ML type II α/β and type III α/β and healthy controls were determined. Previous publications on ML type II α/β and type III α/β during the last five years were retrieved from PubMed, CNKI and WanFang databases by using "mucolipidosis" as key word.
RESULTS
The activities of several lysosomal enzymes were increased in the plasma of both patients: ASA, IDUA (20-fold) > GUSB (10-fold) > GLB1, GLA (5-fold) > NAGLU (2-fold), whilst there was no significant change in GBA. The activities of several lysosomal enzymes in the leukocyte of the two patients were normal. 15 lysosomal enzymes have been used in 22 previous studies, the most frequently used were hexosaminidase A and B (Hex A+B) (12 papers), α-mannosidase (α-man) (11 papers) and GUSB (10 papers). The degree of Hex A+B and α-man elevation was most obvious (24.4-fold and 24.7-fold on average respectively), followed by ASA (22.4-fold on average), GUSB is 18.8-fold on average.
CONCLUSION
Based on the lysosomal enzyme analysis of the two cases and literature review, ASA, GUSB, Hex A+B and α-man are recommended as the evaluating indicators for lysosomal enzyme analysis of ML type II α/β and type III α/β.
Topics: China; Hexosaminidase A; Humans; Iduronidase; Lysosomes; Mucolipidoses; Pedigree
PubMed: 35929931
DOI: 10.3760/cma.j.cn511374-20210830-00706 -
EMBO Molecular Medicine Sep 2022Lysosomes are cell organelles that degrade macromolecules to recycle their components. If lysosomal degradative function is impaired, e.g., due to mutations in lysosomal...
Lysosomes are cell organelles that degrade macromolecules to recycle their components. If lysosomal degradative function is impaired, e.g., due to mutations in lysosomal enzymes or membrane proteins, lysosomal storage diseases (LSDs) can develop. LSDs manifest often with neurodegenerative symptoms, typically starting in early childhood, and going along with a strongly reduced life expectancy and quality of life. We show here that small molecule activation of the Ca -permeable endolysosomal two-pore channel 2 (TPC2) results in an amelioration of cellular phenotypes associated with LSDs such as cholesterol or lipofuscin accumulation, or the formation of abnormal vacuoles seen by electron microscopy. Rescue effects by TPC2 activation, which promotes lysosomal exocytosis and autophagy, were assessed in mucolipidosis type IV (MLIV), Niemann-Pick type C1, and Batten disease patient fibroblasts, and in neurons derived from newly generated isogenic human iPSC models for MLIV and Batten disease. For in vivo proof of concept, we tested TPC2 activation in the MLIV mouse model. In sum, our data suggest that TPC2 is a promising target for the treatment of different types of LSDs, both in vitro and in-vivo.
Topics: Animals; Child, Preschool; Humans; Lysosomal Storage Diseases; Lysosomes; Mice; Mucolipidoses; Neuronal Ceroid-Lipofuscinoses; Quality of Life
PubMed: 35929194
DOI: 10.15252/emmm.202115377 -
Frontiers in Cellular Neuroscience 2022: Protein aggregates are degraded the autophagy-lysosome pathway and alterations in the lysosomal system leading to the accumulation of pathogenic proteins, including...
: Protein aggregates are degraded the autophagy-lysosome pathway and alterations in the lysosomal system leading to the accumulation of pathogenic proteins, including aggregates of α-synuclein in Parkinson's disease (PD). The importance of the endolysosomal transient receptor potential cation channel, mucolipin subfamily 1 (TRPML1) for the lysosomal function is highlighted by the fact that TRPML1 mutations cause the lysosomal storage disease mucolipidosis type IV. In this study, we investigated the mechanism by which activation of TRPML1 affects the degradation of α-synuclein. : As a model of α-synuclein pathology, we expressed the pathogenic A53Tα-synuclein mutant in HEK293T cells. These cells were treated with the synthetic TRPML1 agonist ML-SA1. The amount of α-synuclein protein was determined by immunoblots. The abundance of aggregates and autolysosomal vesicles was determined by fluorescence microscopy and immunocytochemistry. Findings were confirmed by life-cell imaging and by application of ML-SA1 and the TRPML1 antagonist ML-SI3 to human dopaminergic neurons and human stem cell-derived neurons. : ML-SA1 reduced the percentage of HEK293T cells with α-synuclein aggregates and the amount of α-synuclein protein. The effect of ML-SA1 was blocked by pharmacological and genetic inhibition of autophagy. Consistent with TRPML function, it required the membrane lipid PI(3,5)P and cytosolic calcium. ML-SA1 shifted the composition of autophagosomes towards a higher fraction of mature autolysosomes, also in presence of α-synuclein. In neurons, inhibition of TRPML1 by its antagonist ML-SI3 blocked autophagosomal clearance, whereas the agonist ML-SA1 shifted the composition of a-synuclein particles towards a higher fraction of acidified particles. ML-SA1 was able to override the effect of Bafilomycin A1, which blocks the fusion of the autophagosome and lysosome and its acidification. : These findings suggest, that activating TRPML1 with ML-SA1 facilitates clearance of α-synuclein aggregates primarily by affecting the late steps of the autophagy, i.e., by promoting autophagosome maturation. In agreement with recent work by others, our findings indicate that TRPML1 might constitute a plausible therapeutic target for PD, that warrants further validation in rodent models of α-synuclein pathology.
PubMed: 35875350
DOI: 10.3389/fncel.2022.861202 -
Journal of Clinical Medicine Jun 2022Mucolipidosis (ML) type II, intermediate, and III are lysosomal storage disorders with progressive multiorgan manifestations predisposing patients to a high risk of...
Anaesthesia-Relevant Disease Manifestations and Perianaesthetic Complications in Patients with Mucolipidosis-A Retrospective Analysis of 44 Anaesthetic Cases in 12 Patients.
Mucolipidosis (ML) type II, intermediate, and III are lysosomal storage disorders with progressive multiorgan manifestations predisposing patients to a high risk of perioperative morbidity. The aims of the study were to systematically assess disease manifestations relevant to anaesthesia as well as anaesthesia-related complications. This retrospective study includes ML patients who underwent anaesthesia in two centres between 2008 and 2022. We reviewed patients' demographics, medical history, disease manifestations, as well as procedure- and outcome-related data. A total of 12 patients (7 MLII, 2 ML intermediate, 3 MLIII) underwent 44 anaesthesia procedures (per patient: median 3, range 1-11). The median age was 3.3 years (range 0.1-19.1). At least one complication occurred in 27.3% of the anaesthesia procedures. The vast majority of complications (94%) occurred in children with MLII and ML intermediate. A predicted difficult airway was found in 100% and 80% of the MLII and ML intermediate patients, respectively. Accordingly, most complications (59%) occurred during the induction of anaesthesia. Altogether, respiratory complications were the most frequent (18%), followed by difficult airway management (14%). The risk for anaesthesia-related complications is alarmingly high in patients with ML, particularly in those with MLII and ML intermediate. Multidisciplinary risk-benefit analysis and thoughtful anaesthesia planning are crucial in these patients.
PubMed: 35806935
DOI: 10.3390/jcm11133650 -
Gene Aug 2022Neu1 is a lysosomal glycosidase that catalyzes the removal of sialic acids from glycoconjugates. Although Neu1 sialidase is highly conserved among vertebrates, the role...
Neu1 is a lysosomal glycosidase that catalyzes the removal of sialic acids from glycoconjugates. Although Neu1 sialidase is highly conserved among vertebrates, the role of fish Neu1 is not fully understood because of its unique aquatic living situation. Compared to land animals, fish have a higher chance of bacterial infection, and to understand the role of fish Neu1, the susceptibility of Neu1 knockout zebrafish (Neu1-KO) was evaluated using Edwardsiella piscicida, a fish pathogen. Neu1-KO larvae showed high susceptibility to E. piscicida, despite the activation of macrophages, and presented increased lysosomal signals induced by the accumulation of Sia α2-3 linked oligosaccharides. The accumulation coincided with the signal of the macrophage marker, suggesting that the dysfunction of lysosomes in macrophages would result in a high susceptibility of Neu1-KO to E. piscicida. Chloroquine, an inhibitor of lysosomal degradation, induced high mortality of wild type zebrafish with E. piscicida infection accompanied by increased lysosomal accumulation, similar to Neu1-KO zebrafish. This study revealed that Neu1 sialidase plays a crucial role in the lysosomal degradation of macrophages with a bacterial infection.
Topics: Animals; Edwardsiella; Lysosomes; Mucolipidoses; Neuraminidase; Zebrafish
PubMed: 35714800
DOI: 10.1016/j.gene.2022.146667 -
Cellular and Molecular Gastroenterology... 2022Microvillus inclusion disease (MVID) is a congenital diarrheal disorder resulting in life-threatening secretory diarrhea in newborns. Inactivating and nonsense mutations... (Review)
Review
Microvillus inclusion disease (MVID) is a congenital diarrheal disorder resulting in life-threatening secretory diarrhea in newborns. Inactivating and nonsense mutations in myosin Vb (MYO5B) have been identified in MVID patients. Work using patient tissues, cell lines, mice, and pigs has led to critical insights into the pathology of MVID and a better understanding of both apical trafficking in intestinal enterocytes and intestinal stem cell differentiation. These studies have demonstrated that loss of MYO5B or inactivating mutations lead to loss of apical sodium and water transporters, without loss of apical CFTR, accounting for the major pathology of the disease. In addition, loss of MYO5B expression induces the formation of microvillus inclusions through apical bulk endocytosis that utilizes dynamin and PACSIN2 and recruits tight junction proteins to the sites of bulk endosome formation. Importantly, formation of microvillus inclusions is not required for the induction of diarrhea. Recent investigations have demonstrated that administration of lysophosphatidic acid (LPA) can partially reestablish apical ion transporters in enterocytes of MYO5B KO mice. In addition, further studies have shown that MYO5B loss induces an imbalance in Wnt/Notch signaling pathways that can lead to alterations in enterocyte maturation and tuft cell lineage differentiation. Inhibition of Notch signaling leads to improvements in those cell differentiation deficits. These studies demonstrate that directed strategies through LPA receptor activation and Notch inhibition can bypass the inhibitory effects of MYO5B loss. Thus, effective strategies may be successful in MVID patients and other congenital diarrhea syndromes to reestablish proper apical membrane absorption of sodium and water in enterocytes and ameliorate life-threatening congenital diarrhea.
Topics: Animals; Diarrhea; Humans; Malabsorption Syndromes; Microvilli; Mucolipidoses; Myosin Type V; Sodium; Water
PubMed: 35660026
DOI: 10.1016/j.jcmgh.2022.04.015 -
EJIFCC Apr 2022Lysosomal storage disorders (LSDs) are a group of rare and genetic diseases produced by mutations in genes coding for proteins involved in lysosome functioning. Protein...
Lysosomal storage disorders (LSDs) are a group of rare and genetic diseases produced by mutations in genes coding for proteins involved in lysosome functioning. Protein defect leads to the lysosomal accumulation of undegraded macromolecules including glycoproteins, glycosaminoglycans, lipids, and glycogen. Depending on the stored substrate, several pathogenic cascades may be activated leading to multisystemic and progressive disorders affecting the brain, eye, ear, lungs, heart, liver, spleen, kidney, skin, or bone. In addition, for some of these disorders, hematological findings have been also reported. In this paper, we review the major hematological alterations in LSDs based on 56 case reports published between 2010 and 2020. Hematological alterations were reported in sphingolipidosis, mucopolysaccharidoses, mucolipidoses, neuronal ceroid lipofuscinosis, glycogenosis, glycoproteinosis, cystinosis, and cholesteryl ester storage disease. They were reported alterations in red cell linage and leukocytes, such as anemia and morphology changes in eosinophils, neutrophils, monocytes, and lymphocytes. In addition, changes in platelet counts (thrombocytopenia) and leukocyte abnormalities on non-peripheral blood samples were also reported for some LSDs. Although in most of the cases these hematological alterations are not pathognomonic of a specific disease or group of LSDs, since they can be easily identified in general clinical laboratories, their identification may contribute to the diagnosis of these disorders. In this sense, we hope that this review contributes to the awareness of the importance of hematological alterations in the diagnosis of LSDs.
PubMed: 35645695
DOI: No ID Found