Guaiacol as a drug candidate for treating adult polyglucosan body disease

Natural history study of hepatic glycogen storage disease type IV and comparison to Gbe1ys/ys model

BackgroundGlycogen storage disease type IV (GSD IV) is an ultrarare autosomal recessive disorder that causes deficiency of functional glycogen branching enzyme and formation of abnormally structured glycogen termed polyglucosan. GSD IV has traditionally been categorized based on primary hepatic or neuromuscular involvement, with hepatic GSD IV subclassified as discrete subtypes: classic (progressive) and nonprogressive.MethodsTo better understand the progression of liver disease in GSD IV, we present clinical and histopathology data from 23 patients from around the world and characterized the liver involvement in the Gbe1ys/ys knockin mouse model.ResultsWe propose an alternative to the established subtype-based terminology for characterizing liver disease in GSD IV and recognize 3 tiers of disease severity: (i) "severe progressive" liver disease, (ii) "intermediate progressive" liver disease, and (iii) "attenuated" liver disease. Analysis of liver pathology revealed that risk for liver failure cannot be predicted from liver biopsy findings alone in individuals affected by GSD IV. Moreover, analysis of postmortem liver pathology from an individual who died over 40 years after being diagnosed with nonprogressive hepatic GSD IV in childhood verified that liver fibrosis did not regress. Last, characterization of the liver involvement in a mouse model known to recapitulate the adult-onset neurodegenerative form of GSD IV (Gbe1ys/ys mouse model) demonstrated hepatic disease.ConclusionOur findings challenge the established subtype-based view of GSD IV and suggest that liver disease severity among patients with GSD IV represents a disease continuum.Trial registrationClinicalTrials.gov NCT02683512FundingNone.

Non-oncogene dependencies: Novel opportunities for cancer therapy

Targeting oncogene addictions have changed the history of subsets of malignancies and continues to represent an excellent therapeutic opportunity. Nonetheless, alternative strategies are required to treat malignancies driven by undruggable oncogenes or loss of tumor suppressor genes and to overcome drug resistance also occurring in cancers addicted to actionable drivers. The discovery of non-oncogene addiction (NOA) uncovered novel therapeutically exploitable "Achilles' heels". NOA refers to genes/pathways not oncogenic per sé but essential for the tumor cell growth/survival while dispensable for normal cells. The clinical success of several classes of conventional and molecular targeted agents can be ascribed to their impact on both tumor cell-associated intrinsic as well as microenvironment-related extrinsic NOA. The integration of genetic, computational and pharmacological high-throughput approaches led to the identification of an expanded repertoire of synthetic lethality interactions implicating NOA targets. Only a few of them have been translated into the clinics as most NOA vulnerabilities are not easily druggable or appealing targets. Nonetheless, their identification has provided in-depth knowledge of tumor pathobiology and suggested novel therapeutic opportunities. Here, we summarize conceptual framework of intrinsic and extrinsic NOA providing exploitable vulnerabilities. Conventional and emerging methodological approaches used to disclose NOA dependencies are reported together with their limits. We illustrate NOA paradigmatic and peculiar examples and outline the functional/mechanistic aspects, potential druggability and translational interest. Finally, we comment on difficulties in exploiting the NOA-generated knowledge to develop novel therapeutic approaches to be translated into the clinics and to fully harness the potential of clinically available drugs.

Severe neuromuscular forms of glycogen storage disease type IV: Histological, clinical, biochemical, and molecular findings in a large French case series

Glycogen storage disease type IV (GSD IV), also called Andersen disease, or amylopectinosis, is a highly heterogeneous autosomal recessive disorder caused by a glycogen branching enzyme (GBE, 1,4-alpha-glucan branching enzyme) deficiency secondary to pathogenic variants on GBE1 gene. The incidence is evaluated to 1:600 000 to 1:800 000 of live births. GBE deficiency leads to an excessive deposition of structurally abnormal, amylopectin-like glycogen in affected tissues (liver, skeletal muscle, heart, nervous system, etc.). Diagnosis is often guided by histological findings and confirmed by GBE activity deficiency and molecular studies. Severe neuromuscular forms of GSD IV are very rare and of disastrous prognosis. Identification and characterization of these forms are important for genetic counseling for further pregnancies. Here we describe clinical, histological, enzymatic, and molecular findings of 10 cases from 8 families, the largest case series reported so far, of severe neuromuscular forms of GSD IV along with a literature review. Main antenatal features are: fetal akinesia deformation sequence or arthrogryposis/joint contractures often associated with muscle atrophy, decreased fetal movement, cystic hygroma, and/or hydrops fetalis. If pregnancy is carried to term, the main clinical features observed at birth are severe hypotonia and/or muscle atrophy, with the need for mechanical ventilation, cardiomyopathy, retrognathism, and arthrogryposis. All our patients were stillborn or died within 1 month of life. In addition, we identified five novel GBE1 variants.

A United States-based patient-reported adult polyglucosan body disease registry: initial results

Background

Adult Polyglucosan Body Disease (APBD) is an ultra-rare, genetic neurodegenerative disorder caused by autosomal recessive mutations in the glycogen branching enzyme gene. Knowledge of the demographic and clinical characteristics of APBD patients and the natural history of the disease is lacking. We report here initial results from a patient-reported registry of APBD patients.

Objectives

(1) Maximize the quality of the APBD Registry survey data; (2) provide an initial report on APBD disease progression and natural history using these data; and (3) specify next steps in the process for testing potential new therapies.

Design

Data are from members of the APBD Research Foundation (New York), surveyed from 2014 by the Columbia APBD Patient/Family (CAP) Registry. Inclusion criteria are: disease onset at age 18+ and progressive clinical triad of peripheral neuropathy, spasticity, and neurogenic bladder.

Methods

Genetic testing results were used when available. Respondents found to not have APBD in clinical records were excluded. All changes and exclusions were recorded in a database edit log. Results are reported in frequency tables, bar graphs, time plots, and heat maps.

Results

The 96 respondents meeting inclusion criteria were predominantly (96.8%) White, highly educated (89.3% at least some college education), and mostly (85.1%) of Ashkenazi Jewish descent. 57.1% had at least one parent born in the United States, with at least one grandparent from Europe (excluding Russia; 75.4%), the United States (42.1%), or Russia (33.3%). 37.2% reported a family history of APBD, and 33.3% had an affected sibling. Median APBD onset age was 51 [Interquartile range (IQR) 11], and median age of diagnosis 57 (IQR 10.5). The 75 reported prior misdiagnoses were mainly peripheral neuropathy (43, 60.6%) and spinal stenosis (11, 15.1%).

Conclusion

Although from a demographically constricted survey, the results provide basic clinical information for future studies to develop treatments for APBD.

Case report: Expanding the understanding of the adult polyglucosan body disease continuum: novel presentations, diagnostic pitfalls, and clinical pearls

Introduction: Adult polyglucosan body disease (APBD) has long been regarded as the adult-onset form of glycogen storage disease type IV (GSD IV) and is caused by biallelic pathogenic variants in GBE1. Advances in the understanding of the natural history of APBD published in recent years have led to the use of discrete descriptors ("typical" versus "atypical") based on adherence to traditional symptomatology and homozygosity for the p.Y329S variant. Although these general descriptors are helpful in summarizing common findings and symptoms in APBD, they are inherently limited and may affect disease recognition in diverse populations. Methods: This case series includes three American patients (cases 1-3) and four Brazilian patients (cases 4-7) diagnosed with APBD. Patient-reported outcome (PRO) measures were employed to evaluate pain, fatigue, and quality of life in cases 1-3. Results: We describe the clinical course and diagnostic odyssey of seven cases of APBD that challenge the utility and efficacy of discrete descriptors. Cases 1-3 are compound heterozygotes that harbor the previously identified deep intronic variant in GBE1 and presented with "typical" APBD phenotypically, despite lacking two copies of the pathogenic p.Y329S variant. Patient-reported outcome measures in these three cases revealed the moderate levels of pain and fatigue as well as an impacted quality of life. Cases 4-7 have unique genotypic profiles and emphasize the growing recognition of presentations of APBD in diverse populations with broad neurological manifestations. Conclusion: Collectively, these cases underscore the understanding of APBD as a spectrum disorder existing on the GSD IV phenotypic continuum. We draw attention to the pitfalls of commonly used genetic testing methods when diagnosing APBD and highlight the utility of patient-reported outcome questionnaires in managing this disease.

Proteomic investigations of adult polyglucosan body disease: insights into the pathobiology of a neurodegenerative disorder

Inadequate glycogen branching enzyme 1 (GBE1) activity results in different forms of glycogen storage disease type IV, including adult polyglucosan body disorder (APBD). APBD is clinically characterized by adult-onset development of progressive spasticity, neuropathy, and neurogenic bladder and is histologically characterized by the accumulation of structurally abnormal glycogen (polyglucosan bodies) in multiple cell types. How insufficient GBE1 activity causes the disease phenotype of APBD is poorly understood. We hypothesized that proteomic analysis of tissue from GBE1-deficient individuals would provide insights into GBE1-mediated pathobiology. In this discovery study, we utilized label-free LC-MS/MS to quantify the proteomes of lymphoblasts from 3 persons with APBD and 15 age- and gender-matched controls, with validation of the findings by targeted MS. There were 531 differentially expressed proteins out of 3,427 detected between APBD subjects vs. controls, including pronounced deficiency of GBE1. Bioinformatic analyses indicated multiple canonical pathways and protein-protein interaction networks to be statistically markedly enriched in APBD subjects, including: RNA processing/transport/translation, cell cycle control/replication, mTOR signaling, protein ubiquitination, unfolded protein and endoplasmic reticulum stress responses, glycolysis and cell death/apoptosis. Dysregulation of these processes, therefore, are primary or secondary factors in APBD pathobiology in this model system. Our findings further suggest that proteomic analysis of GBE1 mutant lymphoblasts can be leveraged as part of the screening for pharmaceutical agents for the treatment of APBD.

Case 318: Adult Polyglucosan Body Disease

HISTORY

A 72-year-old man sought care for a cognitive deterioration over the past 5 years. There was a documented decline in his performance on the Mini-Mental State Examination (30 of 30 in 2016, 23 of 30 in 2021), with mainly episodic memory impairment. A more detailed history revealed a gait problem, paresthesia in both feet, and nocturnal urinary frequency. Clinical examination findings were suggestive of a length-dependent polyneuropathy. In addition, a right-sided Babinski sign was noted. Electromyography and a nerve conduction study corroborated a peripheral axonal sensorimotor neuropathy. MRI of the brain was performed.

Glycogen storage diseases: An update

Glycogen storage diseases (GSDs), also referred to as glycogenoses, are inherited metabolic disorders of glycogen metabolism caused by deficiency of enzymes or transporters involved in the synthesis or degradation of glycogen leading to aberrant storage and/or utilization. The overall estimated GSD incidence is 1 case per 20000-43000 live births. There are over 20 types of GSD including the subtypes. This heterogeneous group of rare diseases represents inborn errors of carbohydrate metabolism and are classified based on the deficient enzyme and affected tissues. GSDs primarily affect liver or muscle or both as glycogen is particularly abundant in these tissues. However, besides liver and skeletal muscle, depending on the affected enzyme and its expression in various tissues, multiorgan involvement including heart, kidney and/or brain may be seen. Although GSDs share similar clinical features to some extent, there is a wide spectrum of clinical phenotypes. Currently, the goal of treatment is to maintain glucose homeostasis by dietary management and the use of uncooked cornstarch. In addition to nutritional interventions, pharmacological treatment, physical and supportive therapies, enzyme replacement therapy (ERT) and organ transplantation are other treatment approaches for both disease manifestations and long-term complications. The lack of a specific therapy for GSDs has prompted efforts to develop new treatment strategies like gene therapy. Since early diagnosis and aggressive treatment are related to better prognosis, physicians should be aware of these conditions and include GSDs in the differential diagnosis of patients with relevant manifestations including fasting hypoglycemia, hepatomegaly, hypertransaminasemia, hyperlipidemia, exercise intolerance, muscle cramps/pain, rhabdomyolysis, and muscle weakness. Here, we aim to provide a comprehensive review of GSDs. This review provides general characteristics of all types of GSDs with a focus on those with liver involvement.

Glycogen synthase 1 targeting reveals a metabolic vulnerability in triple-negative breast cancer

BACKGROUND

Hypoxia-induced glycogen turnover is implicated in cancer proliferation and therapy resistance. Triple-negative breast cancers (TNBCs), characterized by a hypoxic tumor microenvironment, respond poorly to therapy. We studied the expression of glycogen synthase 1 (GYS1), the key regulator of glycogenesis, and other glycogen-related enzymes in primary tumors of patients with breast cancer and evaluated the impact of GYS1 downregulation in preclinical models.

METHODS

mRNA expression of GYS1 and other glycogen-related enzymes in primary breast tumors and the correlation with patient survival were studied in the METABRIC dataset (n = 1904). Immunohistochemical staining of GYS1 and glycogen was performed on a tissue microarray of primary breast cancers (n = 337). In four breast cancer cell lines and a mouse xenograft model of triple-negative breast cancer, GYS1 was downregulated using small-interfering or stably expressed short-hairpin RNAs to study the effect of downregulation on breast cancer cell proliferation, glycogen content and sensitivity to various metabolically targeted drugs.

RESULTS

High GYS1 mRNA expression was associated with poor patient overall survival (HR 1.20, P = 0.009), especially in the TNBC subgroup (HR 1.52, P = 0.014). Immunohistochemical GYS1 expression in primary breast tumors was highest in TNBCs (median H-score 80, IQR 53-121) and other Ki67-high tumors (median H-score 85, IQR 57-124) (P < 0.0001). Knockdown of GYS1 impaired proliferation of breast cancer cells, depleted glycogen stores and delayed growth of MDA-MB-231 xenografts. Knockdown of GYS1 made breast cancer cells more vulnerable to inhibition of mitochondrial proteostasis.

CONCLUSIONS

Our findings highlight GYS1 as potential therapeutic target in breast cancer, especially in TNBC and other highly proliferative subsets.

Spatial metabolomics reveals glycogen as an actionable target for pulmonary fibrosis

Matrix assisted laser desorption/ionization imaging has greatly improved our understanding of spatial biology, however a robust bioinformatic pipeline for data analysis is lacking. Here, we demonstrate the application of high-dimensionality reduction/spatial clustering and histopathological annotation of matrix assisted laser desorption/ionization imaging datasets to assess tissue metabolic heterogeneity in human lung diseases. Using metabolic features identified from this pipeline, we hypothesize that metabolic channeling between glycogen and N-linked glycans is a critical metabolic process favoring pulmonary fibrosis progression. To test our hypothesis, we induced pulmonary fibrosis in two different mouse models with lysosomal glycogen utilization deficiency. Both mouse models displayed blunted N-linked glycan levels and nearly 90% reduction in endpoint fibrosis when compared to WT animals. Collectively, we provide conclusive evidence that lysosomal utilization of glycogen is required for pulmonary fibrosis progression. In summary, our study provides a roadmap to leverage spatial metabolomics to understand foundational biology in pulmonary diseases.

Diagnosis and management of glycogen storage disease type IV, including adult polyglucosan body disease: A clinical practice resource

Glycogen storage disease type IV (GSD IV) is an ultra-rare autosomal recessive disorder caused by pathogenic variants in GBE1 which results in reduced or deficient glycogen branching enzyme activity. Consequently, glycogen synthesis is impaired and leads to accumulation of poorly branched glycogen known as polyglucosan. GSD IV is characterized by a remarkable degree of phenotypic heterogeneity with presentations in utero, during infancy, early childhood, adolescence, or middle to late adulthood. The clinical continuum encompasses hepatic, cardiac, muscular, and neurologic manifestations that range in severity. The adult-onset form of GSD IV, referred to as adult polyglucosan body disease (APBD), is a neurodegenerative disease characterized by neurogenic bladder, spastic paraparesis, and peripheral neuropathy. There are currently no consensus guidelines for the diagnosis and management of these patients, resulting in high rates of misdiagnosis, delayed diagnosis, and lack of standardized clinical care. To address this, a group of experts from the United States developed a set of recommendations for the diagnosis and management of all clinical phenotypes of GSD IV, including APBD, to support clinicians and caregivers who provide long-term care for individuals with GSD IV. The educational resource includes practical steps to confirm a GSD IV diagnosis and best practices for medical management, including (a) imaging of the liver, heart, skeletal muscle, brain, and spine, (b) functional and neuromusculoskeletal assessments, (c) laboratory investigations, (d) liver and heart transplantation, and (e) long-term follow-up care. Remaining knowledge gaps are detailed to emphasize areas for improvement and future research.

Integrating Network Pharmacology and Transcriptomic Strategies to Explore the Pharmacological Mechanism of Hydroxysafflor Yellow A in Delaying Liver Aging

Aging affects the structure and function of the liver. Hydroxysafflor yellow A (HSYA) effectively improves liver aging (LA) in mice, but the potential mechanisms require further exploration. In this study, an integrated approach combining network pharmacology and transcriptomics was used to elucidate the potential mechanisms of HSYA delay of LA. The targets of HSYA were predicted using the PharmMapper, SwissTargetPrediction, and CTD databases, and the targets of LA were collected from the GeneCards database. An ontology (GO) analysis and a Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway annotation of genes related to HSYA delay of LA were performed using the DAVID database, and Cytoscape software was used to construct an HSYA target pathway network. The BMKCloud platform was used to sequence mRNA from mouse liver tissue, screen differentially expressed genes (DEGs) that were altered by HSYA, and enrich their biological functions and signaling pathways through the OmicShare database. The results of the network pharmacology and transcriptomic analyses were combined. Then, quantitative real-time PCR (qRT-PCR) and Western blot experiments were used to further verify the prediction results. Finally, the interactions between HSYA and key targets were assessed by molecular docking. The results showed that 199 potentially targeted genes according to network pharmacology and 480 DEGs according to transcriptomics were involved in the effects of HSYA against LA. An integrated analysis revealed that four key targets, including HSP90AA1, ATP2A1, NOS1 and CRAT, as well as their three related pathways (the calcium signaling pathway, estrogen signaling pathway and cGMP-PKG signaling pathway), were closely related to the therapeutic effects of HSYA. A gene and protein expression analysis revealed that HSYA significantly inhibited the expressions of HSP90AA1, ATP2A1 and NOS1 in the liver tissue of aging mice. The molecular docking results showed that HSYA had high affinities with the HSP90AA1, ATP2A1 and NOS1 targets. Our data demonstrate that HSYA may delay LA in mice by inhibiting the expressions of HSP90AA1, ATP2A1 and NOS1 and regulating the calcium signaling pathway, the estrogen signaling pathway, and the cGMP-PKG signaling pathway.

In situ mass spectrometry imaging reveals heterogeneous glycogen stores in human normal and cancerous tissues

Glycogen dysregulation is a hallmark of aging, and aberrant glycogen drives metabolic reprogramming and pathogenesis in multiple diseases. However, glycogen heterogeneity in healthy and diseased tissues remains largely unknown. Herein, we describe a method to define spatial glycogen architecture in mouse and human tissues using matrix-assisted laser desorption/ionization mass spectrometry imaging. This assay provides robust and sensitive spatial glycogen quantification and architecture characterization in the brain, liver, kidney, testis, lung, bladder, and even the bone. Armed with this tool, we interrogated glycogen spatial distribution and architecture in different types of human cancers. We demonstrate that glycogen stores and architecture are heterogeneous among diseases. Additionally, we observe unique hyperphosphorylated glycogen accumulation in Ewing sarcoma, a pediatric bone cancer. Using preclinical models, we correct glycogen hyperphosphorylation in Ewing sarcoma through genetic and pharmacological interventions that ablate in vivo tumor growth, demonstrating the clinical therapeutic potential of targeting glycogen in Ewing sarcoma.

Inhibition of Glycogen Metabolism Induces Reactive Oxygen Species-Dependent Cytotoxicity in Anaplastic Thyroid Cancer in Female Mice

Anaplastic thyroid cancer (ATC) is one of the most lethal solid tumors, yet there are no effective, long-lasting treatments for ATC patients. Most tumors, including tumors of the endocrine system, exhibit an increased consumption of glucose to fuel cancer progression, and some cancers meet this high glucose requirement by metabolizing glycogen. Our goal was to determine whether ATC cells metabolize glycogen and if this could be exploited for treatment. We detected glycogen synthase and glycogen phosphorylase (PYG) isoforms in normal thyroid and thyroid cancer cell lines and patient-derived biopsy samples. Inhibition of PYG using CP-91,149 induced apoptosis in ATC cells but not normal thyroid cells. CP-91,149 decreased NADPH levels and induced reactive oxygen species accumulation. CP-91,149 severely blunted ATC tumor growth in vivo. Our work establishes glycogen metabolism as a novel metabolic process in thyroid cells, which presents a unique, oncogenic target that could offer an improved clinical outcome.

What's new and what's next for gene therapy in Pompe disease?

INTRODUCTION

Pompe disease is an autosomal recessive disorder caused by a deficiency of acid-α-glucosidase (GAA), an enzyme responsible for hydrolyzing lysosomal glycogen. A lack of GAA leads to accumulation of glycogen in the lysosomes of cardiac, skeletal, and smooth muscle cells, as well as in the central and peripheral nervous system. Enzyme replacement therapy has been the standard of care for 15 years and slows disease progression, particularly in the heart, and improves survival. However, there are limitations of ERT success, which gene therapy can overcome.

AREAS COVERED

Gene therapy offers several advantages including prolonged and consistent GAA expression and correction of skeletal muscle as well as the critical CNS pathology. We provide a systematic review of the preclinical and clinical outcomes of adeno-associated viral mediated gene therapy and alternative gene therapy strategies, highlighting what has been successful.

EXPERT OPINION

Although the preclinical and clinical studies so far have been promising, barriers exist that need to be addressed in gene therapy for Pompe disease. New strategies including novel capsids for better targeting, optimized DNA vectors, and adjuctive therapies will allow for a lower dose, and ameliorate the immune response.

Molecular basis for the regulation of human glycogen synthase by phosphorylation and glucose-6-phosphate

Glycogen synthase (GYS1) is the central enzyme in muscle glycogen biosynthesis. GYS1 activity is inhibited by phosphorylation of its amino (N) and carboxyl (C) termini, which is relieved by allosteric activation of glucose-6-phosphate (Glc6P). We present cryo-EM structures at 3.0-4.0 Å resolution of phosphorylated human GYS1, in complex with a minimal interacting region of glycogenin, in the inhibited, activated and catalytically competent states. Phosphorylations of specific terminal residues are sensed by different arginine clusters, locking the GYS1 tetramer in an inhibited state via intersubunit interactions. The Glc6P activator promotes conformational change by disrupting these interactions and increases the flexibility of GYS1, such that it is poised to adopt a catalytically competent state when the sugar donor UDP-glucose (UDP-glc) binds. We also identify an inhibited-like conformation that has not transitioned into the activated state, in which the locking interaction of phosphorylation with the arginine cluster impedes subsequent conformational changes due to Glc6P binding. Our results address longstanding questions regarding the mechanism of human GYS1 regulation.

The Antioxidant Guaiacol Exerts Fungicidal Activity Against Fungal Growth and Deoxynivalenol Production in Fusarium graminearum

The main component of creosote obtained from dry wood distillation—guaiacol—is a natural antioxidant that has been widely used in pharmaceutical and food preservation applications. However, the antifungal mechanism of guaiacol against phytopathogens remains unclear. In this study, we found that guaiacol exerts inhibitory effects against mycelial growth, conidial formation and germination, and deoxynivalenol (DON) biosynthesis in Fusarium graminearum in a dose-dependent manner. The median effective concentration (EC₅₀) value of guaiacol for the standard F. graminearum strain PH-1 was 1.838 mM. Guaiacol strongly inhibited conidial production and germination. The antifungal effects of guaiacol may be attributed to its capability to cause damage to the cell membrane by disrupting Ca²⁺ transport channels. In addition, the decreased malondialdehyde (MDA) levels and catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) activity by guaiacol treatment indicate that guaiacol displays activity against DON production by modulating the oxidative response in F. graminearum. Taken together, this study revealed the potentials of antioxidant in inhibiting mycotoxins in F. graminearum.

Lipids in Pathophysiology and Development of the Membrane Lipid Therapy: New Bioactive Lipids

Membranes are mainly composed of a lipid bilayer and proteins, constituting a checkpoint for the entry and passage of signals and other molecules. Their composition can be modulated by diet, pathophysiological processes, and nutritional/pharmaceutical interventions. In addition to their use as an energy source, lipids have important structural and functional roles, e.g., fatty acyl moieties in phospholipids have distinct impacts on human health depending on their saturation, carbon length, and isometry. These and other membrane lipids have quite specific effects on the lipid bilayer structure, which regulates the interaction with signaling proteins. Alterations to lipids have been associated with important diseases, and, consequently, normalization of these alterations or regulatory interventions that control membrane lipid composition have therapeutic potential. This approach, termed membrane lipid therapy or membrane lipid replacement, has emerged as a novel technology platform for nutraceutical interventions and drug discovery. Several clinical trials and therapeutic products have validated this technology based on the understanding of membrane structure and function. The present review analyzes the molecular basis of this innovative approach, describing how membrane lipid composition and structure affects protein-lipid interactions, cell signaling, disease, and therapy (e.g., fatigue and cardiovascular, neurodegenerative, tumor, infectious diseases).

One-Pot Synthesis of Al-P-O Catalysts and Their Catalytic Properties for O-Methylation of Catechol and Methanol

A series of Al-P-O catalysts (Al-xP-O) were prepared using a P123-assisted one-pot method at different P/Al molar ratios and used for O-methylation of catechol and methanol. The influences of the P/Al molar ratio and P123 addition on catalyst structure and surface acid-base characteristics were investigated in detail. Increasing the P/Al molar ratio more favored crystalline aluminophosphate. The P123-assisted Al³⁺ and PO₄³⁻ are known to be stabilized through weak steric force so that the formation of crystalline aluminophosphate could be inhibited at higher P/Al molar ratios. The results showed that the prepared Al-P-O catalysts possessed appropriate weak acid and weak base sites, which was beneficial to the reaction of catechol and methanol. The Al-1.1P-O catalyst synthesized with the assistance of P123 exhibited superior catalytic performances, with 52.5% catechol conversion and higher guaiacol selectivity of 97.6%.

Alleviation of a polyglucosan storage disorder by enhancement of autophagic glycogen catabolism

This work employs adult polyglucosan body disease (APBD) models to explore the efficacy and mechanism of action of the polyglucosan-reducing compound 144DG11. APBD is a glycogen storage disorder (GSD) caused by glycogen branching enzyme (GBE) deficiency causing accumulation of poorly branched glycogen inclusions called polyglucosans. 144DG11 improved survival and motor parameters in a GBE knockin (Gbeys/ys ) APBD mouse model. 144DG11 reduced polyglucosan and glycogen in brain, liver, heart, and peripheral nerve. Indirect calorimetry experiments revealed that 144DG11 increases carbohydrate burn at the expense of fat burn, suggesting metabolic mobilization of pathogenic polyglucosan. At the cellular level, 144DG11 increased glycolytic, mitochondrial, and total ATP production. The molecular target of 144DG11 is the lysosomal membrane protein LAMP1, whose interaction with the compound, similar to LAMP1 knockdown, enhanced autolysosomal degradation of glycogen and lysosomal acidification. 144DG11 also enhanced mitochondrial activity and modulated lysosomal features as revealed by bioenergetic, image-based phenotyping and proteomics analyses. As an effective lysosomal targeting therapy in a GSD model, 144DG11 could be developed into a safe and efficacious glycogen and lysosomal storage disease therapy.

C2orf69 mutations disrupt mitochondrial function and cause a multisystem human disorder with recurring autoinflammation

BACKGROUNDDeciphering the function of the many genes previously classified as uncharacterized open reading frame (ORF) would complete our understanding of a cell's function and its pathophysiology.METHODSWhole-exome sequencing, yeast 2-hybrid and transcriptome analyses, and molecular characterization were performed in this study to uncover the function of the C2orf69 gene.RESULTSWe identified loss-of-function mutations in the uncharacterized C2orf69 gene in 8 individuals with brain abnormalities involving hypomyelination and microcephaly, liver dysfunction, and recurrent autoinflammation. C2orf69 contains an N-terminal signal peptide that is required and sufficient for mitochondrial localization. Consistent with mitochondrial dysfunction, the patients showed signs of respiratory chain defects, and a CRISPR/Cas9-KO cell model of C2orf69 had similar respiratory chain defects. Patient-derived cells revealed alterations in immunological signaling pathways. Deposits of periodic acid-Schiff-positive (PAS-positive) material in tissues from affected individuals, together with decreased glycogen branching enzyme 1 (GBE1) activity, indicated an additional impact of C2orf69 on glycogen metabolism.CONCLUSIONSOur study identifies C2orf69 as an important regulator of human mitochondrial function and suggests that this gene has additional influence on other metabolic pathways.

GBE1-related disorders: Adult polyglucosan body disease and its neuromuscular phenotypes

Adult polyglucosan body disease (APBD) represents a complex autosomal recessive inherited neurometabolic disorder due to homozygous or compound heterozygous pathogenic variants in GBE1 gene, resulting in deficiency of glycogen-branching enzyme and secondary storage of glycogen in the form of polyglucosan bodies, involving the skeletal muscle, diaphragm, peripheral nerve (including autonomic fibers), brain white matter, spinal cord, nerve roots, cerebellum, brainstem and to a lesser extent heart, lung, kidney, and liver cells. The diversity of new clinical presentations regarding neuromuscular involvement is astonishing and transformed APBD in a key differential diagnosis of completely different clinical conditions, including axonal and demyelinating sensorimotor polyneuropathy, progressive spastic paraparesis, motor neuronopathy presentations, autonomic disturbances, leukodystrophies or even pure myopathic involvement with limb-girdle pattern of weakness. This review article aims to summarize the main clinical, biochemical, genetic, and diagnostic aspects regarding APBD with special focus on neuromuscular presentations.

Adult polyglucosan body disease: an acute presentation leading to unmasking of this rare disorder

Introduction: Adult polyglucosan body disease (APBD) is an autosomal recessive leukodystrophy caused by abnormal intracellular accumulation of glycogen byproducts. This disorder is linked to a deficiency in glycogen branching enzyme-1 (GBE-1). Neurologic manifestations include upper and lower motor neuron signs, dementia, and peripheral neuropathy. APBD is typically a progressive disease. In this report, we discuss a novel case of APBD in a patient who had a sudden onset of spastic quadriparesis preceded by gradual difficulty with gait. Genetic and postmortem analysis confirmed the diagnosis of APBD.Case report: A 65-year-old man was evaluated for a new-onset of spastic quadriparesis, right-gaze preference, and left-sided beat nystagmus. Magnetic resonance imaging (MRI) of the brain revealed areas of white matter hyperintensities most prominent in the brainstem and periventricular regions. MRI of the cervical spine showed marked cord atrophy. Laboratory workup and cerebrospinal fluid analysis were unremarkable. Genetic testing supported the diagnosis of APBD due to GBE-1 deficiency. Postmortem analysis showed multiple white matter abnormalities suggestive of a leukodystrophy syndrome, and histopathologic testing revealed abnormal accumulation of polyglucosan bodies in samples from the patient's central nervous system supporting the diagnosis of APBD.Conclusion: APBD is a rare disorder that can affect the nervous system. The diagnosis can be confirmed with a combination of genetic testing and pathologic analysis of affected brain tissue.

GYS1 or PPP1R3C deficiency rescues murine adult polyglucosan body disease

OBJECTIVE

Adult polyglucosan body disease (APBD) is an adult-onset neurological variant of glycogen storage disease type IV. APBD is caused by recessive mutations in the glycogen branching enzyme gene, and the consequent accumulation of poorly branched glycogen aggregates called polyglucosan bodies in the nervous system. There are presently no treatments for APBD. Here, we test whether downregulation of glycogen synthesis is therapeutic in a mouse model of the disease.

METHODS

We characterized the effects of knocking out two pro-glycogenic proteins in an APBD mouse model. APBD mice were crossed with mice deficient in glycogen synthase (GYS1), or mice deficient in protein phosphatase 1 regulatory subunit 3C (PPP1R3C), a protein involved in the activation of GYS1. Phenotypic and histological parameters were analyzed and glycogen was quantified.

RESULTS

APBD mice deficient in GYS1 or PPP1R3C demonstrated improvements in life span, morphology, and behavioral assays of neuromuscular function. Histological analysis revealed a reduction in polyglucosan body accumulation and of astro- and micro-gliosis in the brains of GYS1- and PPP1R3C-deficient APBD mice. Brain glycogen quantification confirmed the reduction in abnormal glycogen accumulation. Analysis of skeletal muscle, heart, and liver found that GYS1 deficiency reduced polyglucosan body accumulation in all three tissues and PPP1R3C knockout reduced skeletal muscle polyglucosan bodies.

INTERPRETATION

GYS1 and PPP1R3C are effective therapeutic targets in the APBD mouse model. These findings represent a critical step toward the development of a treatment for APBD and potentially other glycogen storage disease type IV patients.

Sensitive quantification of α-glucans in mouse tissues, cell cultures, and human cerebrospinal fluid

The soluble α-polyglucan glycogen is a central metabolite enabling transient glucose storage to suit cellular energy needs. Glycogen storage diseases (GSDs) comprise over 15 entities caused by generalized or tissue-specific defects in enzymes of glycogen metabolism. In several, e.g. in Lafora disease caused by the absence of the glycogen phosphatase laforin or its interacting partner malin, degradation-resistant abnormally structured insoluble glycogen accumulates. Sensitive quantification methods for soluble and insoluble glycogen are critical to research, including therapeutic studies, in such diseases. This paper establishes methodological advancements relevant to glycogen metabolism investigations generally, and GSDs. Introducing a pre-extraction incubation method, we measure degradation-resistant glycogen in as little as 30 mg of skeletal muscle or a single hippocampus from Lafora disease mouse models. The digestion-resistant glycogen correlates with the disease-pathogenic insoluble glycogen and can readily be detected in very young mice where glycogen accumulation has just begun. Second, we establish a high-sensitivity glucose assay with detection of ATP depletion, enabling 1) quantification of α-glucans in cell culture using a medium-throughput assay suitable for assessment of candidate glycogen synthesis inhibitors, and 2) discovery of α-glucan material in healthy human cerebrospinal fluid, establishing a novel methodological platform for biomarker analyses in Lafora disease and other GSDs.

Skeletal Muscle Glycogen Chain Length Correlates with Insolubility in Mouse Models of Polyglucosan-Associated Neurodegenerative Diseases

Lafora disease (LD) and adult polyglucosan body disease (APBD) are glycogen storage diseases characterized by a pathogenic buildup of insoluble glycogen. Mechanisms causing glycogen insolubility are poorly understood. Here, in two mouse models of LD (Epm2a^-/- and Epm2b^-/-) and one of APBD (Gbe1^ys/ys), the separation of soluble and insoluble muscle glycogen is described, enabling separate analysis of each fraction. Total glycogen is increased in LD and APBD mice, which, together with abnormal chain length and molecule size distributions, is largely if not fully attributed to insoluble glycogen. Soluble glycogen consists of molecules with distinct chain length distributions and differential corresponding solubility, providing a mechanistic link between soluble and insoluble glycogen in vivo. Phosphorylation states differ across glycogen fractions and mouse models, demonstrating that hyperphosphorylation is not a basic feature of insoluble glycogen. Lastly, model-specific variances in protein and activity levels of key glycogen synthesis enzymes suggest uninvestigated regulatory mechanisms.