Glycogen Accumulation Research Articles

Morphological changes of liver and spleen under the impact of dextran-polyacrylamide polymers and their effects as carriers of silver and gold nanoparticles

The possibility of usage of polymer nanocomposites is being intensively studied today with a purpose of their application in medicine, espessialy in oncology. At the experimental stage it is important to determine the mechanisms of the influence of such compounds on the body and their own possible undesirable effects. Aim – to study the effect of the treatment with maximal doses of the dextran-polyacrylamide polymers and their effect as carriers of silver and gold nanoparticles on the spleen and liver. Histological examination of micropreparations of the spleen and liver by the standard method with hematoxylin-eosin staining was made. As a result of the treatment with nonionic (D-g-PAA) and anionic (D-g-PAA (PE)) polymer matrices, changes which occurred in the spleen indicate an increase in the production of all blood cells. These phenomena were absent when silver and gold nanoparticles were included in the matrix. In the liver, treatment with D-g-PAA and D-g-PAA (PE) caused a disorder of hepatic circulation, focal infiltration by inflammatory cells and death of hepatocytes by necrosis. The addition of nanoparticles triggered other mechanisms of alteration, which manifested themselves in excessive accumulation of glycogen, fatty infiltration of hepatocytes, and cell death, mainly through apoptosis. However, along with this, signs of an incomplete regenerative response of the liver were revealed. Morphological changes caused by the treatment with maximal doses of the tested substances indicate their toxic effect, especially on the liver. Further researches are needed to establish the optimal doses and the frequency of their administration, which can be used for therapeutic purposes, including the interaction of studied polymers with blood cells.

Combined targeted and untargeted high-resolution mass spectrometry analyses to investigate metabolic alterations in pompe disease

Pompe disease is a rare, lysosomal disorder, characterized by intra-lysosomal glycogen accumulation due to an impaired function of α-glucosidase enzyme. The laboratory testing for Pompe is usually performed by enzyme activity, genetic test, or urine glucose tetrasaccharide (Glc4) screening by HPLC. Despite being a good preliminary marker, the Glc4 is not specific for Pompe. The purpose of the present study was to develop a simple methodology using liquid chromatography-high resolution mass spectrometry (LC-HRMS) for targeted quantitative analysis of Glc4 combined with untargeted metabolic profiling in a single analytical run to search for complementary biomarkers in Pompe disease. We collected 21 urine specimens from 13 Pompe disease patients and compared their metabolic signatures with 21 control specimens. Multivariate statistical analyses on the untargeted profiling data revealed Glc4, creatine, sorbitol/mannitol, L-phenylalanine, N-acetyl-4-aminobutanal, N-acetyl-L-aspartic acid, and 2-aminobenzoic acid as significantly altered in Pompe disease. This panel of metabolites increased sample class prediction (Pompe disease versus control) compared with a single biomarker. This study has demonstrated the potential of combined acquisition methods in LC-HRMS for Pompe disease investigation, allowing for routine determination of an established biomarker and discovery of complementary candidate biomarkers that may increase diagnostic accuracy, or improve the risk stratification of patients with disparate clinical phenotypes.

Polysaccharide storage myopathy in two Percheron horses

Polysaccharide storage myopathy (PSSM) is a genetic disorder or by undetermined cause characterized by the abnormal accumulation of glycogen and polysaccharides in skeletal muscle fibers. The present report describes two Percheron horses, from different properties in the municipality of Pouso Redondo - SC, with locomotor clinical signs that started after work. The clinical signs observed were rigid gait, mainly of the pelvic limbs, muscle weakness, and recumbency. In the first case, the animal was diagnosed with severe multifocal rhabdomyonecrosis, moderate multifocal myoglobin nephrosis and severe diffuse transmural fibrinonecrotic gastritis. PSSM was confirmed by the presence of polysaccharide inclusions in myofiber sarcolemma visualized by periodic acid-Schiff (PAS) staining. In the second case, the horse presented two episodes of muscle disorder after work. The therapeutic protocol was based on penicillin, flunixin meglumine and fluid therapy with ringer lactate. An increase in creatine kinase (669.0 UI/L) and aspartate aminotransferase (669.0 UI/L) was observed in the serum biochemical evaluation. Research for mutation in the GYS1 gene was performed, with a positive heterozygote result. After rest and gradual recovery, the horse was only submitted to light work, with no return of the clinical condition since then. Thus, this report describes two cases of PSSM with distinct clinical evolution and diagnostic methods.

Glycophagy mediated glucose-induced changes of hepatic glycogen metabolism via OGT1-AKT1-FOXO1Ser238 pathway

Glycophagy is the autophagy degradation of glycogen. However, the regulatory mechanisms for glycophagy and glucose metabolism remain unexplored. Herein, we demonstrated that high-carbohydrate diet (HCD) and high glucose (HG) incubation induced glycogen accumulation, protein kinase B (AKT)1 expression and AKT1-dependent phosphorylation of forkhead transcription factor O1 (FOXO1) at Ser238 in the liver tissues and hepatocytes. The glucose-induced FOXO1 phosphorylation at Ser238 prevents FOXO1 entry into the nucleus and the recruitment to the GABA(A) receptor-associated protein like 1 (gabarapl1) promoter, reduces the gabarapl1 promoter activity, and inhibits glycophagy and glucose production. The glucose-dependent O-GlcNAcylation of AKT1 by O-GlcNAc transferase (OGT1) enhances the stability of AKT1 protein and promotes its binding with FOXO1. Moreover, the glycosylation of AKT1 is crucial for promoting FOXO1 nuclear translocation and inhibiting glycophagy. Our studies elucidate a novel mechanism for glycophagy inhibition by high carbohydrate and glucose via OGT1-AKT1-FOXO1Ser238 pathway in the liver tissues and hepatocytes, which provides critical insights into potential intervention strategies for glycogen storage disorders in vertebrates, as well as human beings.

The Liver and Glycogen: In Sickness and in Health

The liver is a major store of glycogen and is essential in maintaining systemic glucose homeostasis. In healthy individuals, glycogen synthesis and breakdown in the liver are tightly regulated. Abnormal glycogen metabolism results in prominent pathological changes in the liver, often manifesting as hepatic glycogenosis or glycogen inclusions. This can occur in genetic glycogen storage disease or acquired conditions with insulin dysregulation such as diabetes mellitus and non-alcoholic fatty liver disease or medication effects. Some primary hepatic tumors such as clear cell hepatocellular carcinoma also demonstrate excessive glycogen accumulation. This review provides an overview of the pathological manifestations and molecular mechanisms of liver diseases associated with abnormal glycogen accumulation.

Hepatic leucine carboxyl methyltransferase 1 (LCMT1) contributes to high fat diet-induced glucose intolerance through regulation of glycogen metabolism

Impaired glucose regulation is one of the most important risk factors for type 2 diabetes mellitus (T2DM) and cardiovascular diseases, which have become a major public health issue worldwide. Dysregulation of carbohydrate metabolism in liver has been shown to play a critical role in the development of glucose intolerance but the molecular mechanism has not yet been fully understood. In this study, we investigated the role of hepatic LCMT1 in the regulation of glucose homeostasis using a liver-specific LCMT1 knockout mouse model. The hepatocyte-specific deletion of LCMT1 significantly upregulated the hepatic glycogen synthesis and glycogen accumulation in liver. We found that the liver-specific knockout of LCMT1 improved high fat diet-induced glucose intolerance and insulin resistance. Consistently, the high fat diet-induced downregulation of glucokinase (GCK) and other important glycogen synthesis genes were reversed in LCMT1 knockout liver. In addition, the expression of GCK was significantly upregulated in MIHA cells treated with siRNA targeting LCMT1 and improved glycogen synthesis. In this study, we provided evidences to support the role of hepatic LCMT1 in the development of glucose intolerance induced by high fat diet and demonstrated that inhibiting LCMT1 could be a novel therapeutic strategy for the treatment of glucose metabolism disorders.

Microscopic and histochemical changes in the liver of adult rats with hyperhomocysteinemia

Violation of amino acids metabolism in the human body is the cause of changes in the structure and functions of almost all vital organs and systems. During the last tens of years, significant efforts of scientists have been directed to the in-depth study of such compound as homocysteine (Hcys), which is a thiol-containing amino acid and is produced endogenously during the exchange of methionine and cysteine. Under the conditions of its normal concentration (5-15 μmol/l), it does not pose a threat to the life and health of living organisms. However, in a number of pathological conditions, a pronounced increase of Hcys in blood plasma and inside cells is registered, which leads to the appearance or progression of diseases, including damage of liver tissue. The aim of the research is to study the microscopic and histochemical changes in the liver of adult rats with hyperhomocysteinemia (HHcys). The experiment was conducted on 22 white non-linear adult male rats aged 6-8 months. During the study, the animals were divided into two groups – control and experimental. Chronic resistance to HHcys was modeled by administering thiolactone Hcys in a dose of 200 mg/kg of body weight intragastrically for 60 days to the rats of the experimental group. Histological preparations were studied using a SEO SСAN light microscope and photo-documented using a Vision CCD Camera with a system of image output from histological preparations. Succinate dehydrogenase was detected histochemically according to the Nakhlas method. These studies were carried out on sections made in a cryostat microtome from unfixed tissue using nitro blue tetrazole. To study the specifics of glycogen accumulation in hepatocytes, sections were stained using Schiff’s reagent, after preliminary treatment with iodic acid (PAS reaction) in the Shabadash modification. It was established that the administration of thiolactone Hcys to young rats at a dose of 200 mg/kg led to an increase in the volume of connective tissue elements around the lobules and in the portal tracts of the liver. Thus, it was established that in the liver of adult rats with HHcys, there is a noticeable thickening of the fibrous connective tissue around the lobules and in the portal tracts, trabeculae dissociation, and the appearance of foci of necrosis of the parenchyma of the organ. Hypertrophy and hyperplasia of smooth myocytes in the middle layer and fibrosis of the outer layer of the wall of interlobular arteries, leukocyte infiltration in the portal tracts are observed. A significant decrease in succinate dehydrogenase activity was established histochemically.

Top 10 Clear Cell Head and Neck Lesions to Contemplate.

Optically clear cytoplasm may occur in neoplastic and non-neoplastic conditions, either as a characteristic feature of a disease entity or as a morphologic rarity, potentially creating diagnostic dilemmas in various organ systems. In the head and neck, clear cell change can occur in lesions of salivary, odontogenic, thyroid, parathyroid, or sinonasal/skull base origin, as well as in metastases to these regions. This review elaborates the top ten clear cell lesions in the head and neck, emphasizing their distinguishing histologic, immunohistochemical, and molecular attributes, and presents a rational approach to arriving at an accurate classification. Cytoplasmic pallor or clearing may be caused by accumulations of glycogen, lipid, mucin, mucopolysaccharides, water, foreign material, hydropic organelles, or immature zymogen granules. Overlapping morphologic features may present a diagnostic challenge to the surgical pathologist. Similarity in immunohistochemical profiles, often due to common cell type, as well as rare non-neoplastic mimics, furthers the diagnostic conundrum. The top ten lesions reviewed in this article are as follows: (1) clear cell carcinoma (salivary and odontogenic), (2) mucoepidermoid carcinoma, (3) myoepithelial and epithelial-myoepithelial carcinoma, (4) oncocytic salivary gland lesions, (5) squamous cell carcinoma, (6) parathyroid water clear cell adenoma, (7) metastatic renal cell carcinoma (especially in comparison to clear cell thyroid neoplasms), (8) sinonasal renal cell-like adenocarcinoma, (9) chordoma, and (10) rhinoscleroma.

HPF Modulates the Differentiation of BMSCs into HLCs and Promotes the Recovery of Acute Liver Injury in Mice

Bone marrow-derived mesenchymal stem cells (BMSCs) can differentiate into hepatocyte-like cells (HLCs) to alleviate acute liver injury (ALI). Herpetfluorenone (HPF), as an active ingredient in the dried, mature seeds Herpetospermum caudigerum Wall, used in Tibetan medicine, has been proven to effectively alleviate ALI. Therefore, the purpose of this study was to determine whether HPF can promote the differentiation of BMSCs into HLCs and promote ALI recovery. Mouse BMSCs were isolated, and the BMSCs' differentiation into HLCs was induced by HPF and hepatocyte growth factor (HGF). Under the induction of HPF and HGF, the expression of hepatocellular specific markers and the accumulation of glycogen and lipids in the BMSCs increased, indicating that BMSCs successfully differentiated into HLCs. Then, the ALI mouse model was established, using carbon tetrachloride, followed by an intravenous injection of BMSCs. Then, only HPF was injected intraperitoneally, in order to verify the effect of HPF in vivo. In vivo imaging was used to detect the homing ability of HPF-BMSCs, and it was detected that HPF-BMSCs significantly increased the levels of serum AST, ALT and ALP in the liver of ALI mice, and alleviated liver cell necrosis, oxidative stress and liver pathology. In conclusion, HPF can promote the differentiation of BMSCs into HLCs and promote the recovery of ALI in mice.

MATERNAL DIABETES LEADS TO VIOLATION OF THE STRUCTURAL ORGANIZATION OF OFFSPRING CARDIOMYOCYTES IN POSTNATAL ONTOGENESIS

Often, women with diabetes mellitus give birth to children with diabetic fetopathy, which is characterized by a high incidence of defects in the development of the cardiovascular system. The aim of the study was an experimental analysis of the structural and functional features of the contractile cardiomyocytes of the left ventricle of 70-day-old adult offspring obtained from mothers with type I diabetes mellitus induced before pregnancy. Diabetes mellitus was modeled in adult sexually mature female rats using streptozotocin. The apex of the wall of the left ventricle of their sexually mature offspring was subjected to histological examination. The control group was animals obtained from mothers with uncomplicated physiological pregnancy. During the study, it was found that in experimental animals there is a decrease in the specific area of the parenchyma of the left ventricular myocardium with a simultaneous increase in the area of the stroma, a decrease in the number of contractile cardiomyocytes and their nuclear- cytoplasmic ratio, a significant decrease in the content of binuclear cardiomyocytes and the increase of accumulation of glycogen in them. The results obtained allow us to conclude that experimental type I diabetes mellitus in pregnant female laboratory rats causes a violation of the structural and functional formation of the contractile apparatus of the heart of their offspring and leads to persistent structural myocardial disorders in the late period of postnatal ontogenesis.

Transcriptomic characterization of clinical skeletal muscle biopsy from late-onset Pompe patients.

Pompe disease is a rare lysosomal storage disorder arising from recessive mutations in the acid α-glucosidase gene and resulting in the accumulation of glycogen, particularly in the cardiac and skeletal muscle. The current standard of care is administration of enzyme replacement therapy in the form of alglucosidase alfa or the recently approved avalglucosidase alfa. In order to better understand the underlying cellular processes that are disrupted in Pompe disease, we conducted gene expression analysis on skeletal muscle biopsies obtained from late-onset Pompe disease patients (LOPD) prior to treatment and following six months of enzyme replacement with avalglucosidase alfa. The LOPD patients had a distinct transcriptomic signature as compared to control patient samples, largely characterized by perturbations in pathways involved in lysosomal function and energy metabolism. Although patients were highly heterogeneous, they collectively exhibited a strong trend towards attenuation of the dysregulated genes following just six months of treatment. Notably, the enzyme replacement therapy had a strong stabilizing effect on gene expression, with minimal worsening in genes that were initially dysregulated. Many of the cellular process that were altered in LOPD patients were also affected in the more clinically severe infantile-onset (IOPD) patients. Additionally, both LOPD and IOPD patients demonstrated enrichment across several inflammatory pathways, despite a lack of overt immune cell infiltration. This study provides further insight into Pompe disease biology and demonstrates the positive effects of avalglucosidase alfa treatment.

Loss of transketolase promotes the anti-diabetic role of brown adipose tissues.

Transketolase (TKT), an enzyme in the non-oxidative branch of the pentose phosphate pathway (PPP), bi-directionally regulates the carbon flux between the PPP and glycolysis. Loss of TKT in adipose tissues decreased glycolysis and increased lipolysis and uncoupling protein-1 (UCP1) expression, protecting mice from high-fat diet-induced obesity. However, the role of TKT in brown adipose tissue (BAT)-dependent glucose homeostasis under normal chow diet remains to be elucidated. We found that TKT ablation increased levels of glucose transporter 4 (GLUT4), promoting glucose uptake and glycogen accumulation in BAT. Using the streptozotocin (STZ)-induced diabetic mouse model, we discovered that enhanced glucose uptake due to TKT deficiency in BAT contributed to decreasing blood glucose and weight loss, protecting mice from STZ-induced diabetes. Mechanistically, TKT deficiency decreased the level of thioredoxin-interacting protein, a known inhibitor for GLUT4, by decreasing NADPH and glutathione levels and inducing oxidative stress in BAT. Therefore, our data reveal a new role of TKT in regulating the anti-diabetic function of BAT as well as glucose homeostasis.

Histological and histochemical changes in liver tissue of young rats with hyperhomocysteinemia

Annotation. The decisive place in the synthesis and subsequent metabolism of homocysteine (Hcy) belongs to the liver, where, in particular, transsulfation and remethylation processes take place. It has been proven that organ tissue damage can cause hyperhomocysteinemia (HHcy). Changes in the structural and functional parameters of the liver tissue under the conditions of a significant and long-term increase in blood serum Hcy are still insufficiently studied. Modeling the state of chronic HHcy and studying the features of histological changes in liver tissue at different levels of structural organization is an urgent task. The aim of the research is to study morphological and histochemical changes in the liver tissue of young rats with HHcy. The experiment was carried out on 22 white non-linear young – aged 1-2 months, male rats. During the study, the animals were divided into two groups – control and experimental. Chronic persistent HHcy was modeled by administering thiolactone Hcy in a dose of 200 mg/kg of body weight intragastrically for 60 days to the rats of the experimental group. Histological preparations were studied using a SEO SСAN light microscope and photo-documented using a Vision CCD Camera. Succinate dehydrogenase was detected histochemically according to the Nakhlas method. To study the specifics of glycogen accumulation in hepatocytes, sections were stained using Schiff's reagent, after preliminary treatment with iodic acid (PAS reaction) in the Shabadash modification. It was established that the administration of thiolactone Hcy to young rats at a dose of 200 mg/kg led to impaired blood supply, destructive changes and growth of connective tissue in the liver. Moderate changes in the hepatocyte plates organization, a decrease in the mitotic activity of hepatocytes, and the development of fatty and vacuole-hydropic dystrophy were recorded. Histochemical studies of the liver of animals of the research group established a decrease in the activity of the succinate dehydrogenase enzyme and glycogen content in hepatocytes.

Role of Astrocytes in the Pathophysiology of Lafora Disease and Other Glycogen Storage Disorders.

Lafora disease is a rare disorder caused by loss of function mutations in either the EPM2A or NHLRC1 gene. The initial symptoms of this condition are most commonly epileptic seizures, but the disease progresses rapidly with dementia, neuropsychiatric symptoms, and cognitive deterioration and has a fatal outcome within 5-10 years after onset. The hallmark of the disease is the accumulation of poorly branched glycogen in the form of aggregates known as Lafora bodies in the brain and other tissues. Several reports have demonstrated that the accumulation of this abnormal glycogen underlies all the pathologic traits of the disease. For decades, Lafora bodies were thought to accumulate exclusively in neurons. However, it was recently identified that most of these glycogen aggregates are present in astrocytes. Importantly, astrocytic Lafora bodies have been shown to contribute to pathology in Lafora disease. These results identify a primary role of astrocytes in the pathophysiology of Lafora disease and have important implications for other conditions in which glycogen abnormally accumulates in astrocytes, such as Adult Polyglucosan Body disease and the buildup of Corpora amylacea in aged brains.

Pompe disease - What do we currently know about the disease?


 Introduction: Pompe disease (PD) is a rare metabolic disorder caused by a partial or complete deficiency of acid α-glucosidase (GAA) which leads to lysosomal accumulation of glycogen. Excessive amounts of glycogen accumulate mainly in the cells of the heart and skeletal muscles and cause dysfunction of these tissues. It is inherited in an autosomal recessive manner. The most common diagnostic methods include genetic tests and the measurement of enzyme activity in leukocytes or fibroblasts. A screening test is also available that tests the enzyme activity in dried blood spot (DBS). The treatment of PD is mostly based on synthetic GAA enzyme supply to the patients. The therapy reduces glycogen storage and improves muscle function, decreases heart size and prolongs the lives of those with infantile form of PD. In the adult onset of the disease treatment increases physical efficiency and reduces the progression of respiratory failure.
 
 
 Aim of the study: Systematization of current knowledge about Pompe disease with particular emphasis on possible clinical presentations, diagnostics and therapeutic options.
 Material and methods: Literature review based on PubMed data using the following keywords: Pompe disease, Glycogenosis type ii, glucosidase alpha
 Summary : Pompe disease is a rare disease with many problems related to diagnosis and possible therapies. Its symptoms can be very misleading and cause a delay in diagnosis . It is critical to start the therapy as soon as possible to best manage the disease. The prognosis of PD is poor, especially in children under 12 months of age. Gene therapy research is currently underway and early results are very promising. There is still much to learn about dealing with this disease.

Effects of Ventromedial Hypothalamic Nucleus (VMN) Aromatase Gene Knockdown on VMN Glycogen Metabolism and Glucoregulatory Neurotransmission

The enzyme aromatase is expressed at high levels in the ventromedial hypothalamic nucleus (VMN), a principal component of the brain gluco-regulatory network. Current research utilized selective gene knockdown tools to investigate the premise that VMN neuroestradiol controls glucostasis. Intra-VMN aromatase siRNA administration decreased baseline aromatase protein expression and tissue estradiol concentrations and either reversed or attenuated the hypoglycemic regulation of these profiles in a VMN segment-specific manner. Aromatase gene repression down-regulated protein biomarkers for gluco-stimulatory (nitric oxide; NO) and -inhibitory (gamma-aminobutyric acid; GABA) neurochemical transmitters. Insulin-induced hypoglycemia (IIH) up- or down-regulated neuronal nitric oxide synthase (nNOS) and glutamate decarboxylase65/67 (GAD), respectively, throughout the VMN. Interestingly, IIH caused divergent changes in tissue aromatase and estradiol levels in rostral (diminished) versus middle and caudal (elevated) VMN. Aromatase knockdown prevented hypoglycemic nNOS augmentation in VMN middle and caudal segments, but abolished the GAD inhibitory response to IIH throughout this nucleus. VMN nitrergic and GABAergic neurons monitor stimulus-specific glycogen breakdown. Here, glycogen synthase (GS) and phosphorylase brain- (GPbb; AMP-sensitive) and muscle- (GPmm; noradrenergic -responsive) type isoform responses to aromatase siRNA were evaluated. Aromatase repression reduced GPbb and GPmm content in euglycemic controls and prevented hypoglycemic regulation of GPmm but not GPbb expression while reversing glycogen accumulation. Aromatase siRNA elevated baseline glucagon and corticosterone secretion and abolished hypoglycemic hyperglucagonemia and hypercorticosteronemia. Outcomes document the involvement of VMN neuroestradiol signaling in brain control of glucose homeostasis. Aromatase regulation of VMN gluco-regulatory signaling of hypoglycemia-associated energy imbalance may entail, in part, control of GP variant-mediated glycogen disassembly.

Models for the assessment of glycogen accumulation and depletion in various tissues

models for the assessment of glycogen accumulation and depletion in various tissues

Glycogenic Hepatopathy in a Teenage Girl with Diabetes Mellitus Type 1

Glycogenic hepatopathy (GH) refers to a relatively rare complication of diabetes mellitus (DM) type 1 which constitutes of reversible accumulation of excess hepatic glycogen, usually manifesting in the form of liver enzyme elevation along with hepatomegaly. The occurrence of the disorder is most commonly related to inadequate control of blood sugars. Herein, we report upon a case of an 18-year-old girl presenting with severe transaminase elevations owing to poor metabolic control, as well as the progression of her enzymes and general condition during and after her hospitalization.

Pompe disease, a rare condition in two patients, case reports

Pompe disease, or type II glycogen storage disease, is a lysosomal storage disorder in which a deficiency in alpha-glucosidase results in the accumulation of glycogen, which eventually causes weakness to progressively increase and heart enlargement.
 Infantile-onset and late-onset forms of Pompe illness are distinguished. The heart is the organ most impacted by glycogen buildup in infantile-onset Pompe illness. A late-onset form, however, frequently presents as a weakening of the skeletal muscles that worsens over time.
 The key factor used to make the diagnosis of Pompe illness is enzymology, which shows a lack of lysosomal acid alpha-glucosidase (GAA) activity, although molecular genetic testing for GAA mutations can also be used to confirm the diagnosis.
 Recombinant human a glucosidase alfa and a large multidisciplinary team are required for the treatment of patients with Pompe disease (rhGAA, MyozymeR).
 Two cases of Pompe disease are presented in this case-report. A 13-year-old female patient who is still alive and receiving enzyme replacement therapy, and a 5-month-old newborn who died from cardiomyopathy.

AAV-based gene therapy prevents and halts the progression of dilated cardiomyopathy in a mouse model of phosphoglucomutase 1 deficiency (PGM1-CDG)

Phosphoglucomutase 1 (PGM1) deficiency is recognized as the third most common N-linked congenital disorders of glycosylation (CDG) in humans. Affected individuals present with liver, musculoskeletal, endocrine, and coagulation symptoms; however, the most life-threatening complication is the early onset of dilated cardiomyopathy (DCM). Recently, we discovered that oral D-galactose supplementation improved liver disease, endocrine, and coagulation abnormalities, but does not alleviate the fatal cardiomyopathy and the associated myopathy. Here we report on left ventricular ejection fraction (LVEF) in 6 individuals with PGM1-CDG. LVEF was pathologically low in most of these individuals and varied between 10% and 65%. To study the pathobiology of the cardiac disease observed in PGM1-CDG, we constructed a novel cardiomyocyte-specific conditional Pgm2 gene (mouse ortholog of human PGM1) knockout (Pgm2 cKO) mouse model. Echocardiography studies corroborated a DCM phenotype with significantly reduced ejection fraction and left ventricular dilation similar to those seen in individuals with PGM1-CDG. Histological studies demonstrated excess glycogen accumulation and fibrosis, while ultrastructural analysis revealed Z-disk disarray and swollen/fragmented mitochondria, which was similar to the ultrastructural pathology in the cardiac explant of an individual with PGM1-CDG. In addition, we found decreased mitochondrial function in the heart of KO mice. Transcriptomic analysis of hearts from mutant mice demonstrated a gene signature of DCM. Although proteomics revealed only mild changes in global protein expression in left ventricular tissue of mutant mice, a glycoproteomic analysis unveiled broad glycosylation changes with significant alterations in sarcolemmal proteins including different subunits of laminin-211, which was confirmed by immunoblot analyses. Finally, augmentation of PGM1 in KO mice via AAV9-PGM1 gene replacement therapy prevented and halted the progression of the DCM phenotype.