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Cells Jun 2020The glycoprotein disorders are a group of lysosomal storage diseases (α-mannosidosis, aspartylglucosaminuria, β-mannosidosis, fucosidosis, galactosialidosis,... (Review)
Review
The glycoprotein disorders are a group of lysosomal storage diseases (α-mannosidosis, aspartylglucosaminuria, β-mannosidosis, fucosidosis, galactosialidosis, sialidosis, mucolipidosis II, mucolipidosis III, and Schindler Disease) characterized by specific lysosomal enzyme defects and resultant buildup of undegraded glycoprotein substrates. This buildup causes a multitude of abnormalities in patients including skeletal dysplasia, inflammation, ocular abnormalities, liver and spleen enlargement, myoclonus, ataxia, psychomotor delay, and mild to severe neurodegeneration. Pharmacological treatment options exist through enzyme replacement therapy (ERT) for a few, but therapies for this group of disorders is largely lacking. Hematopoietic cell transplant (HCT) has been explored as a potential therapeutic option for many of these disorders, as HCT introduces functional enzyme-producing cells into the bone marrow and blood along with the engraftment of healthy donor cells in the central nervous system (presumably as brain macrophages or a type of microglial cell). The outcome of HCT varies widely by disease type. We report our institutional experience with HCT as well as a review of the literature to better understand HCT and outcomes for the glycoprotein disorders.
Topics: Animals; Enzyme Replacement Therapy; Glycoproteins; Hematopoietic Stem Cell Transplantation; Humans; Lysosomal Storage Diseases
PubMed: 32517081
DOI: 10.3390/cells9061411 -
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 -
Cellular and Molecular Gastroenterology... 2022UNC45A is a myosin (co-)chaperone, and mutations in the UNC45A gene were recently identified in osteo-oto-hepato-enteric (O2HE) syndrome patients presenting with...
BACKGROUND & AIMS
UNC45A is a myosin (co-)chaperone, and mutations in the UNC45A gene were recently identified in osteo-oto-hepato-enteric (O2HE) syndrome patients presenting with congenital diarrhea and intrahepatic cholestasis. Congenital diarrhea and intrahepatic cholestasis are also the prime symptoms in patients with microvillus inclusion disease (MVID) and mutations in MYO5B, encoding the recycling endosome-associated myosin Vb. The aim of this study was to determine whether UNC45A and myosin Vb are functionally linked.
METHODS
CRISPR-Cas9 gene editing and site-directed mutagenesis were performed with intestinal epithelial and hepatocellular cell lines, followed by Western blotting, quantitative polymerase chain reaction, and scanning electron and/or confocal fluorescence microscopy to determine the relationship between (mutants of) UNC45A and myosin Vb.
RESULTS
UNC45A depletion in intestinal and hepatic cells reduced myosin Vb protein expression, and in intestinal epithelial cells, it affected 2 myosin Vb-dependent processes that underlie MVID pathogenesis: rat sarcoma-associated binding protein (RAB)11A-positve recycling endosome positioning and microvilli development. Reintroduction of UNC45A in UNC45A-depleted cells restored myosin Vb expression, and reintroduction of UNC45A or myosin Vb, but not the O2HE patient UNC45A-c.1268T>A variant, restored recycling endosome positioning and microvilli development. The O2HE patient-associated p.V423D substitution, encoded by the UNC45A-c.1268T>A variant, impaired UNC45A protein stability but as such not the ability of UNC45A to promote myosin Vb expression and microvilli development.
CONCLUSIONS
A functional relationship exists between UNC45A and myosin Vb, thereby connecting 2 rare congenital diseases with overlapping enteropathy at the molecular level. Protein instability rather than functional impairment underlies the pathogenicity of the O2HE syndrome-associated UNC45A-p.V423D mutation.
Topics: Cholestasis, Intrahepatic; Diarrhea; Enterocytes; Humans; Intracellular Signaling Peptides and Proteins; Malabsorption Syndromes; Microvilli; Mucolipidoses; Myosin Heavy Chains; Myosin Type V; Myosins; Rare Diseases
PubMed: 35421597
DOI: 10.1016/j.jcmgh.2022.04.006 -
Cells Nov 2023The recently presented Azalea Hypothesis for Alzheimer's disease asserts that iron becomes sequestered, leading to a functional iron deficiency that contributes to... (Review)
Review
The recently presented Azalea Hypothesis for Alzheimer's disease asserts that iron becomes sequestered, leading to a functional iron deficiency that contributes to neurodegeneration. Iron sequestration can occur by iron being bound to protein aggregates, such as amyloid β and tau, iron-rich structures not undergoing recycling (e.g., due to disrupted ferritinophagy and impaired mitophagy), and diminished delivery of iron from the lysosome to the cytosol. Reduced iron availability for biochemical reactions causes cells to respond to acquire additional iron, resulting in an elevation in the total iron level within affected brain regions. As the amount of unavailable iron increases, the level of available iron decreases until eventually it is unable to meet cellular demands, which leads to a functional iron deficiency. Normally, the lysosome plays an integral role in cellular iron homeostasis by facilitating both the delivery of iron to the cytosol (e.g., after endocytosis of the iron-transferrin-transferrin receptor complex) and the cellular recycling of iron. During a lysosomal storage disorder, an enzyme deficiency causes undigested substrates to accumulate, causing a sequelae of pathogenic events that may include cellular iron dyshomeostasis. Thus, a functional deficiency of iron may be a pathogenic mechanism occurring within several lysosomal storage diseases and Alzheimer's disease.
Topics: Humans; Alzheimer Disease; Iron; Amyloid beta-Peptides; Lysosomal Storage Diseases; Lysosomes; Iron Deficiencies
PubMed: 37998376
DOI: 10.3390/cells12222641 -
Orphanet Journal of Rare Diseases Sep 2021Although the clinical efficacy of laminoplasty in adult cervical spondylotic myelopathy or ossification of posterior longitudinal ligament has been frequently reported,...
BACKGROUND
Although the clinical efficacy of laminoplasty in adult cervical spondylotic myelopathy or ossification of posterior longitudinal ligament has been frequently reported, there are only few reports of laminoplasty for patients with lysosome storage diseases (LSDs). Therefore, this study aimed to report the midterm clinical and radiological outcomes of patients with LSDs after cervical laminoplasty.
METHODS
Six patients with LSD who underwent laminoplasty with/without C1 laminectomy for cervical myelopathy were enrolled. Clinical evaluations, including the cervical Japanese Orthopedic Association (cJOA) score and visual analog scale (VAS) scores for upper extremity numbness, and radiographic parameters, including C2-C7 lordotic angle, atlanto-dens interval (ADI), and ⊿ADI, were evaluated preoperatively, at 2 years postoperatively, and at the final follow-up.
RESULTS
Five patients had mucopolysaccharidoses (type I: n = 1, II: n = 3, VII: n = 1) and one patient had mucolipidoses type III. The mean age of patients at surgery was 27.5 years, and the mean postoperative follow-up period was 61 months. All mucopolysaccharidoses cases required C1 posterior arch resection with C2-C7 laminoplasty. No critical complications were observed postoperatively. There were no significant differences in C2-C7 angle (p = 0.724) and ⊿ADI (p = 0.592) between the preoperative and final follow-ups. The cJOA score and VAS for numbness significantly improved at the final follow-up (p = 0.004 and p = 0.007, respectively).
CONCLUSIONS
The cervical myelopathy in patients with LSD could be safely and effectively treated with laminoplasty with/without C1 posterior arch resection after excluding patients with atlantoaxial instability. Atlantoaxial stability and symptom improvement could be maintained at an average of 5 years postoperatively.
Topics: Adult; Cervical Vertebrae; Humans; Laminoplasty; Lysosomal Storage Diseases; Mucolipidoses; Mucopolysaccharidoses; Retrospective Studies; Spinal Cord Diseases; Treatment Outcome
PubMed: 34583711
DOI: 10.1186/s13023-021-02031-9 -
Diagnostics (Basel, Switzerland) Jul 2021Mucopolysaccharidoses (MPS) and mucolipidosis (ML II/III) are a group of lysosomal storage disorders (LSDs) that occur due to a dysfunction of the lysosomal hydrolases...
Mucopolysaccharidoses (MPS) and mucolipidosis (ML II/III) are a group of lysosomal storage disorders (LSDs) that occur due to a dysfunction of the lysosomal hydrolases responsible for the catabolism of glycosaminoglycans (GAGs). However, ML is caused by a deficiency of the enzyme uridine-diphosphate N-acetylglucosamine:lysosomal-enzyme-N-acetylglucosamine-1-phosphotransferase (GlcNAc-1-phosphotransferase, EC2.7.8.17), which tags lysosomal enzymes with a mannose 6-phosphate (M6P) marker for transport to the lysosome. A timely diagnosis of MPS and ML can lead to appropriate therapeutic options for patients. To improve the accuracy of diagnosis for MPS and ML in a high-risk population, we propose a combination method based on known biomarkers, enzyme activities, and specific GAGs. We measured five lysosomal enzymes (α-L-iduronidase (MPS I), iduronate-2-sulfatase (MPS II), α-N-acetylglucosaminidase (MPS IIIB), N-acetylglucosamine-6-sulfatase (MPS IVA), and N-acetylglucosamine-4-sulfatase (MPS VI)) and five GAGs (two kinds of heparan sulfate (HS), dermatan sulfate (DS), and two kinds of keratan sulfate (KS)) in dried blood samples (DBS) to diagnose suspected MPS patients by five-plex enzyme and simultaneous five GAGs assays. We used liquid chromatography-tandem mass spectrometry (LC-MS/MS) for both assays. These combined assays were tested for 43 patients with suspected MPS and 103 normal control subjects. We diagnosed two MPS I, thirteen MPS II, one MPS IIIB, three MPS IVA, two MPS VI, and six ML patients with this combined method, where enzymes, GAGs, and clinical manifestations were compatible. The remaining 16 patients were not diagnosed with MPS or ML. The five-plex enzyme assay successfully identified MPS patients from controls. Patients with MPS I, MPS II, and MPS IIIB had significantly elevated HS and DS levels in DBS. Compared to age-matched controls, patients with ML and MPS had significantly elevated mono-sulfated KS and di-sulfated KS levels. The results indicated that the combination method could distinguish these affected patients with MPS or ML from healthy controls. Overall, this study has shown that this combined method is effective and can be implemented in larger populations, including newborn screening.
PubMed: 34441282
DOI: 10.3390/diagnostics11081347 -
Cellular and Molecular Gastroenterology... 2018
Topics: Enterocytes; Humans; Inclusion Bodies; Microvilli; Mucolipidoses; Myosin Type V
PubMed: 30364797
DOI: 10.1016/j.jcmgh.2018.08.002 -
Molecular Genetics and Metabolism Mar 2017Mucopolysaccharidoses (MPSs) and mucolipidoses (ML) are groups of lysosomal storage disorders in which lysosomal hydrolases are deficient leading to accumulation of...
UNLABELLED
Mucopolysaccharidoses (MPSs) and mucolipidoses (ML) are groups of lysosomal storage disorders in which lysosomal hydrolases are deficient leading to accumulation of undegraded glycosaminoglycans (GAGs), throughout the body, subsequently resulting in progressive damage to multiple tissues and organs. Assays using tandem mass spectrometry (MS/MS) have been established to measure GAGs in serum or plasma from MPS and ML patients, but few studies were performed to determine whether these assays are sufficiently robust to measure GAG levels in dried blood spots (DBS) of patients with MPS and ML.
MATERIAL AND METHODS
In this study, we evaluated GAG levels in DBS samples from 124 MPS and ML patients (MPS I=16; MPS II=21; MPS III=40; MPS IV=32; MPS VI=10; MPS VII=1; ML=4), and compared them with 115 age-matched controls. Disaccharides were produced from polymer GAGs by digestion with chondroitinase B, heparitinase, and keratanase II. Subsequently, dermatan sulfate (DS), heparan sulfate (HS-0S, HS-NS), and keratan sulfate (mono-sulfated KS, di-sulfated KS, and ratio of di-sulfated KS in total KS) were measured by MS/MS.
RESULTS
Untreated patients with MPS I, II, VI, and ML had higher levels of DS compared to control samples. Untreated patients with MPS I, II, III, VI, and ML had higher levels of HS-0S; and untreated patients with MPS II, III and VI and ML had higher levels of HS-NS. Levels of KS were age dependent, so although levels of both mono-sulfated KS and di-sulfated KS were generally higher in patients, particularly for MPS II and MPS IV, age group numbers were not sufficient to determine significance of such changes. However, the ratio of di-sulfated KS in total KS was significantly higher in all MPS patients younger than 5years old, compared to age-matched controls. MPS I and VI patients treated with HSCT had normal levels of DS, and MPS I, VI, and VII treated with ERT or HSCT had normal levels of HS-0S and HS-NS, indicating that both treatments are effective in decreasing blood GAG levels.
CONCLUSION
Measurement of GAG levels in DBS is useful for diagnosis and potentially for monitoring the therapeutic efficacy in MPS.
Topics: Adolescent; Adult; Age Factors; Child; Child, Preschool; Chromatography, Liquid; Dermatan Sulfate; Dried Blood Spot Testing; Female; Glycosaminoglycans; Heparitin Sulfate; Humans; Infant; Infant, Newborn; Keratan Sulfate; Male; Mucolipidoses; Mucopolysaccharidoses; Sensitivity and Specificity; Tandem Mass Spectrometry; Young Adult
PubMed: 28065440
DOI: 10.1016/j.ymgme.2016.12.010 -
Pflugers Archiv : European Journal of... Feb 2016The discovery of the TRPML subfamily of ion channels has created an exciting niche in the fields of membrane trafficking, signal transduction, autophagy, and metal... (Review)
Review
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. TRPML1 is associated with the human lysosomal storage disease known as mucolipidosis type IV (MLIV), but TRPML2 and TRPML3 have not been linked with a human disease. Although TRPML1 is expressed in many tissues, TRPML3 is expressed in a varied but limited set of tissues, while TRPML2 has a more limited expression pattern where it is mostly detected in lymphoid and myeloid tissues. This review focuses on TRPML2 because it appears to play an important, yet unrecognized role in the immune system. While the evidence has been mostly indirect, we present and discuss relevant data that strengthen the connection of TRPML2 with cellular immunity. We also discuss the functional redundancy between the TRPML proteins, and how such features could be exploited as a potential therapeutic strategy for MLIV disease. We present evidence that TRPML2 expression may complement certain phenotypic alterations in MLIV cells and briefly examine the challenges of functional complementation. In conclusion, the function of TRPML2 still remains obscure, but emerging data show that it may serve a critical role in immune cell development and inflammatory responses.
Topics: Animals; B-Lymphocytes; Dendritic Cells; Genetic Therapy; Humans; Mucolipidoses; Signal Transduction; Transient Receptor Potential Channels
PubMed: 26336837
DOI: 10.1007/s00424-015-1732-2 -
JCI Insight Oct 2023Sialidosis is an ultra-rare multisystemic lysosomal disease caused by mutations in the neuraminidase 1 (NEU1) gene. The severe type II form of the disease manifests with...
Sialidosis is an ultra-rare multisystemic lysosomal disease caused by mutations in the neuraminidase 1 (NEU1) gene. The severe type II form of the disease manifests with a prenatal/infantile or juvenile onset, bone abnormalities, severe neuropathology, and visceromegaly. A subset of these patients present with nephrosialidosis, characterized by abrupt onset of fulminant glomerular nephropathy. We studied the pathophysiological mechanism of the disease in 2 NEU1-deficient mouse models, a constitutive Neu1-knockout, Neu1ΔEx3, and a conditional phagocyte-specific knockout, Neu1Cx3cr1ΔEx3. Mice of both strains exhibited terminal urinary retention and severe kidney damage with elevated urinary albumin levels, loss of nephrons, renal fibrosis, presence of storage vacuoles, and dysmorphic mitochondria in the intraglomerular and tubular cells. Glycoprotein sialylation in glomeruli, proximal distal tubules, and distal tubules was drastically increased, including that of an endocytic reabsorption receptor megalin. The pool of megalin bearing O-linked glycans with terminal galactose residues, essential for protein targeting and activity, was reduced to below detection levels. Megalin levels were severely reduced, and the protein was directed to lysosomes instead of the apical membrane. Together, our results demonstrated that desialylation by NEU1 plays a crucial role in processing and cellular trafficking of megalin and that NEU1 deficiency in sialidosis impairs megalin-mediated protein reabsorption.
Topics: Animals; Humans; Mice; Kidney Diseases; Kidney Glomerulus; Kidney Tubules, Proximal; Low Density Lipoprotein Receptor-Related Protein-2; Mucolipidoses; Neuraminidase
PubMed: 37698928
DOI: 10.1172/jci.insight.166470