Glycogen Accumulation Research Articles

Red rice bran aqueous extract ameliorate diabetic status by inhibiting intestinal glucose transport in high fat diet/STZ-induced diabetic rats

Red rice (Oryza sativa L.) consumption has grown recently, partly due to its potential health benefits in several disease prevention. The impact of red rice bran aqueous extract (RRBE) on intestinal glucose uptake and diabetes mellitus (DM) progression has not been thoroughly investigated. This study aimed to evaluate the effect of RRBE on ex vivo intestinal glucose absorption and its potential as an antihyperglycemic compound using a high-fat diet and streptozotocin (STZ)-induced diabetic rats. High-fat diet/STZ-induced diabetic rats were supplemented with either 1000 mg/kg body weight (BW) of RRBE, 70 mg/kg BW of metformin (Met), or a combination of RRBE and Met for 3 months. Plasma parameters, intestinal glucose transport, morphology, liver and soleus muscle glycogen accumulation were assessed. Treatment with RRBE, metformin, or combination markedly reversed hyperglycemia, hypertriglyceridemia, insulin resistance, and pancreatic morphology changes associated with T2DM. Correspondingly, all supplements effectively downregulated glucose transporters, resulting in a reduction of intestinal glucose transport—additionally, liver and soleus muscle glycogen accumulation was reduced in RRBE + Met treated group. Taken together, RRBE potentially suppressed intestinal glucose transporters' function and expression, reducing diabetic status.

Efficient and reproducible generation of human induced pluripotent stem cell-derived expandable liver organoids for disease modeling

Genetic liver disease modeling is difficult because it is challenging to access patient tissue samples and to develop practical and relevant model systems. Previously, we developed novel proliferative and functional liver organoids from pluripotent stem cells; however, the protocol requires improvement for standardization and reproducible mass production. Here, we improved the method such that it is suitable for scalable expansion and relatively homogenous production, resulting in an efficient and reproducible process. Moreover, three medium components critical for long-term expansion were defined. Detailed transcriptome analysis revealed that fibroblast growth factor signaling, the essential pathway for hepatocyte proliferation during liver regeneration, was mainly enriched in proliferative liver organoids. Short hairpin RNA-mediated knockdown of FGFR4 impaired the generation and proliferation of organoids. Finally, glycogen storage disease type Ia (GSD1a) patient-specific liver organoids were efficiently and reproducibly generated using the new protocol. They well maintained disease-specific phenotypes such as higher lipid and glycogen accumulation in the liver organoids and lactate secretion into the medium consistent with the main pathologic characteristics of patients with GSD1a. Therefore, our newly established liver organoid platform can provide scalable and practical personalized disease models and help to find new therapies for incurable liver diseases including genetic liver diseases.

Histological changes in the liver of rats under the influence of Vipera berus berus venom

Animal venoms contain a whole complex of compounds, among which there are peptides, proteins, as well as other organic molecules and salts. Their toxins are able to cause pronounced disturbances in the functioning of physiological systems, leading to the appearance of pathological conditions, complications, or even death. The aim of the research is to study the histological changes in the liver of rats under the influence of Vipera berus berus venom. Experimental studies were carried out on white non-linear male rats. The animals were conditionally divided into two groups – a control and an experimental group of 10 individuals in each. Experimental rats were injected intraperitoneally with a semi-lethal dose (LD50) (1.576 mg/g-1) of Vipera berus berus venom in saline solution. Animals of the control group were injected intraperitoneally with only saline solution. Rats were removed from the experiment 24 hours after exposure to the venom, anesthetized by cervical dislocation. Liver samples of animals of all groups were taken for microscopic examination. Histological preparations of the liver were stained with hematoxylin and eosin. Histological preparations were studied using a SEO SСAN light microscope. To identify the key enzyme of the citric acid cycle – succinate dehydrogenase, histochemical studies were performed according to the Nakhlas method. To study the features of glycogen accumulation in hepatocytes, sections were stained using Schiff's reagent, after pretreatment with iodic acid (PAS reaction) in Shabadash's modification. An immunohistochemical research method was used to detect a subpopulation of CD86+ cells in the liver of experimental animals. Under the influence of Vipera berus berus venom, the development of alterative changes in the liver parenchyma and vascular disorders were microscopically revealed. The appearance of foci of leukocyte infiltration was established, which indicates the development of inflammatory processes. A histochemical study of the content of succinate dehydrogenase in the liver of animals injected with Vipera berus berus venom showed uneven activity of the mitochondrial enzyme in the lobules. A histochemical study of glycogen in hepatocytes of the liver of rats exposed to Vipera berus berus venom showed a decrease in the content of trophic inclusions. An increase in the population of CD86+ cells indicates reactive inflammatory processes observed in the body as a result of the action of components of Vipera berus berus venom.

The preferential utilization of hepatic glycogen as energy substrates in largemouth bass (Micropterus salmoides) under short-term starvation.

To elucidate the underlying mechanism of the energy metabolism in largemouth bass (Micropterus salmoides), cultured fish (initial body weight: 77.57 ± 0.75 g) in the present study were starved for 0 h, 12 h, 24 h, 48 h, 96 h and 192 h, respectively. The proximate composition analysis showed that short-term starvation induced a significant up-regulation in crude protein proportion in hepatic of cultured fish (P < 0.05). However, short-term starvation significantly decreased the hepatosomatic index and the viscerosomatic index of cultured fish (P < 0.05). The exact hepatic glycogen content in the group starved for 92 h presented remarkable decrease (P < 0.05). Meanwhile, compared with the weight change of lipid and protein (mg) in hepatic (y = 0.0007x2 - 0.2827x + 49.402; y = 0.0013x2 - 0.5666x + 165.31), the decreasing trend of weight in glycogen (mg) was more pronounced (y = 0.0032x2 - 1.817x + 326.52), which suggested the preferential utilization of hepatic glycogen as energy substrates under short-term starvation. Gene expression analysis revealed that the starvation down-regulated the expression of insulin-like growth factor 1 and genes of TOR pathway, such as target of rapamycin (tor) and ribosomal protein S6 (s6) (P < 0.05). In addition, the starvation significantly enhanced expression of lipolysis-related genes, including hormone-sensitive lipase (hsl) and carnitine palmitoyl transferase I (cpt1), but down-regulated lipogenesis as indicated by the inhibited expression of fatty acids synthase (fas), acetyl-CoA carboxylase 1 (acc1) and acetyl-CoA carboxylase 2 (acc2) (P < 0.05). Starvation of 24 h up-regulated the expression of glycolysis genes, glucokinase (gk), phosphofructokinase liver type (pfkl) and pyruvate kinase (pk), and then their expression returned to the normal level. Meanwhile, the expression of gluconeogenesis genes, such as glucose-6-phosphatase catalytic subunit (g6pc), fructose-1,6-bisphosphatase-1 (fbp1) and phosphoenolpyruvate carboxy kinase (pepck), was significantly inhibited with the short-term starvation (P < 0.05). In conclusion, short-term starvation induced an overall decline in growth performance, but it could deplete the hepatic glycogen accumulation and mobilize glycogen for energy effectively.

Dietary inclusion of Clostridium butyricum cultures alleviated impacts of high-carbohydrate diets in largemouth bass (Micropterus salmoides).

A 60-d feeding trial was conducted to explore the potential regulatory effects of dietary Clostridium butyricum cultures (CBC) supplementation in high-carbohydrate diet (HCD) on carbohydrate utilisation, antioxidant capacity and intestinal microbiota of largemouth bass. Triplicate groups of largemouth bass (average weight 35·03 ± 0·04 g), with a destiny of twenty-eight individuals per tank, were fed low-carbohydrate diet and HCD supplemented with different concentration of CBC (0 %, 0·25 %, 0·50 % and 1·00 %). The results showed that dietary CBC inclusion alleviated the hepatic glycogen accumulation induced by HCD intake. Additionally, the expression of hepatic ampkα1 and insulin signaling pathway-related genes (ira, irb, irs, p13kr1 and akt1) increased linearly with dietary CBC inclusion, which might be associated with the activation of glycolysis-related genes (gk, pfkl and pk). Meanwhile, the expression of intestinal SCFA transport-related genes (ffar3 and mct1) was significantly increased with dietary CBC inclusion. In addition, the hepatic antioxidant capacity was improved with dietary CBC supplementation, as evidenced by linear decrease in malondialdehyde concentration and expression of keap1, and linear increase in antioxidant enzyme activities (total antioxidative capacity, total superoxide dismutase and catalase) and expression of antioxidant enzyme-related genes (nrf2, sod1, sod2 and cat). The analysis of bacterial 16S rRNA V3-4 region indicated that dietary CBC inclusion significantly reduced the enrichment of Firmicutes and potential pathogenic bacteria genus Mycoplasma but significantly elevated the relative abundance of Fusobacteria and Cetobacterium. In summary, dietary CBC inclusion improved carbohydrate utilization, antioxidant capacity and intestinal microbiota of largemouth bass fed HCD.

Microplastics cause hepatotoxicity in diabetic mice by disrupting glucolipid metabolism via PP2A/AMPK/HNF4A and promoting fibrosis via the Wnt/β-catenin pathway.

In recent years, microplastics (MPs) have gained significant attention as a persistent environmental pollutant resulting from the decomposition of plastics, leading to their accumulation in the human body. The liver, particularly of individuals with type 2 diabetes mellitus (T2DM), is known to be more susceptible to the adverse effects of environmental pollutants. Therefore, to investigate the potential impact of MPs on the liver of diabetic mice and elucidate the underlying toxicological mechanisms, we exposed db/db mice to 0.5 μm MPs for 3 months. Our results revealed that MPs exposure resulted in several harmful effects, including decreased body weight, disruption of liver structure and function, elevated blood glucose levels, impaired glucose tolerance, and increased glycogen accumulation in the hepatic tissue of the mice. Furthermore, MPs exposure was found to promote hepatic gluconeogenesis by perturbing the PP2A/AMPK/HNF4A signaling pathway. In addition, MPs disrupt redox balance, leading to oxidative damage in the liver. This exposure also disrupted hepatic lipid metabolism, stimulating lipid synthesis while inhibiting catabolism, ultimately resulting in the development of fatty liver. Moreover, MPs were found to induce liver fibrosis by activating the Wnt/β-catenin signaling pathway. Furthermore, MPs influenced adaptive thermogenesis in brown fat by modulating the expression of uncoupling protein 1 (UCP1) and genes associated with mitochondrial oxidative respiration thermogenesis in brown fat. In conclusion, our study demonstrates that MPs induce oxidative damage in the liver, disturb glucose and lipid metabolism, promote hepatic fibrosis, and influence adaptive thermogenesis in brown fat in diabetic mice. These findings underscore the potential adverse effects of MPs on liver health in individuals with T2DM and highlight the importance of further research in this area.

Perturbed glycogen metabolism is an Alzheimer’s disease therapeutic target

AbstractBackgroundThree clinical hallmarks of AD are amyloid beta (Aβ) plaques, neurofibrillary tangles, and glucose hypometabolism. Multiple agents can decrease Aβ and tau levels, such as the recently FDA‐approved Aducanumab. However, improvements in patient cognition are disappointing and this disappointment is potentially due to a failure to normalize cerebral glucose hypometabolism.Clinical AD symptom severity strongly correlates with the degree of glucose hypometabolism. In the brain, one route of glucose metabolism is the biosynthesis of glycogen, a branched molecule that functions as an energy cache in times of energetic stress. Importantly, glycogen is critical for neuronal function and memory formation, and defective glycogen metabolism is an underlying driver of several neurological glycogen storage disorders (GSDs). An excess glycogen phenotype was reported in AD brains in the early 1980s, but to date, little is known about its involvement in AD symptoms.MethodIn this study, we first report that AD brains have an excess glycogen phenotype and that AD glycogen correlates with disease severity in human patient samples. Furthermore, the human excess AD glycogen is phenocopied in multiple AD mouse models and the accumulation of glycogen in these mice precedes cognitive deficits. Based on rigorous and striking data, we propose glycogen as a novel target for AD therapy that warrants additional preclinical development.ResultWe developed the enzyme therapy VAL‐0417 that combines a glycogen‐degrading amylase fused to an antibody fragment that facilitates intracellular delivery of recombinant enzymes. VAL‐0417 ablates excess glycogen and rescues disease phenotypes in a fatal GSD that causes childhood dementia called Lafora disease (LD). LD mice share several phenotypes with AD mouse models, including neurotoxic glycogen accumulation. Excitingly, VAL‐0417 also degrades AD glycogen both in vitro from human patient samples and in vivo in the 5xFAD AD mouse model. Furthermore, VAL‐0417 significantly reduces Ab plaque burden in 5xFAD mice and improves hippocampal long‐term potentiation.ConclusionThese studies suggest that targeting AD glycogen with VAL‐0417, either alone or in combination with other therapies targeting Aβ and/or tau, is an exciting and novel preclinical therapeutic target.

Awareness and developments in the treatment of pompe disease : A review

Pompe disease is a hereditary, uncommon (one in every 40,000 births) and frequently deadly ailment that affects the heart and skeletal muscles. Mutations in a gene that produces an enzyme called acid alpha-glucosidase cause it (GAA). This article is meant to raise awareness among Pompe disease patients. We also talk about new future treatments on the market for the treatment of pompe illness. Pompe disease is an inherited disorder caused by the build-up of a complex sugar called glycogen in the body’s cells. The accumulation of glycogen in certain organs and tissues, especially muscles, impairs their ability to function normally. Researchers have described three types of pompe disease, which differ in severity and the age at which they appear. These types are known as classic infantile-onset, non-classic infantile-onset and late-onset. The classic form of infantileonset pompe disease begins within a few months of birth. Infants with this disorder typically experience muscle weakness (myopathy), poor muscle tone (hypotonia), an enlarged liver (hepatomegaly) and heart defects. Affected infants may also fail to gain weight and grow at the expected rate (failure to thrive) and have breathing problems. If untreated, this form of pompe disease leads to death from heart failure in the first year of life. The non-classic form of infantile-onset pompe disease usually appears by age 1. It is characterized by delayed motor skills (such as rolling over and sitting) and progressive muscle weakness. The heart may be abnormally large (cardiomegaly), but affected individuals usually do not experience heart failure. The muscle weakness in this disorder leads to serious breathing problems and most children with non-classic infantile-onset pompe disease live only into early childhood.

Pathophysiological mechanisms of adaptation of muscle tissue of descendants of irradiated animals to altering influence of ionizing radiation

Biochemical processes occurring in a living organism take part in the development of radiation-induced structural disorders, realizing primary damage. As a result, morphological manifestations of radiation damage are preceded by chemical shifts determining them. In the descendants of animals irradiated in different doses, a decrease in physical performance is observed, which is due to a violation of the efficiency of the use of the unique biosubstrate of muscle tissue - creatinephosphate, a change in the ratio of the activity of aerobic and anaerobic metabolism, and processes of trans-deamination of amino acids. The purpose of the work is to investigate the the mechanisms of disruption of metabolic processes in the muscle tissue of the descendants of irradiated animals. It was concluded that, unlike skeletal muscle, the activity of the tricarboxylic acid cycle, in particular the NAD-dependent malate dehydrogenase, in the myocardium is quite significant both in the cytoplasm and in the mitochondria of the tissue, as evidenced by the higher level of tricarboxylic acid cycle metabolites acids - malic and oxaloacetic, as well as the activity of NADP-dependent malate dehydrogenase, which performs a connecting role between glycolysis and the cycle of tricarboxylic acids in providing them with metabolites and transferring protons from NADH+H+ to NADP. The author revealed that myocardium is characterized by a larger pool of adenyl nucleotides due to ATP. Tha data obrtained shiowed hyperglycemia which is observed in the blood of the descendants of irradiated animals. Gluconeogenesis is enhanced in the liver of the descendants of irradiated animals and this explains the hyperglycemia and accumulation of glycogen in the liver. At the same time, the penetration of glucose into muscle cells is weakened, which is associated with a decrease in their glycogen content, and this can be explained by the decrease in adaptation to physical exertion in the descendants of irradiated animals. The author made a cionclusion that the pathophysiological mechanisms of radiation-induced energy supply restructuring are aimed at short-term processes of strengthening the supply of energy to vital organs and systems for destroyed biochemical, physiological, functional and regulatory processes restoration and sanogenetic mechanisms activation.

Exercise induced muscle weakness in a young adult: McArdle’s disease unusual presentation

McArdle’s disease (Glycogen storage disease type V) is a rare inherited autosomal recessive disease involving defect in enzyme, glycogen phosphorylase (PYGM) which results in accumulation of glycogen mainly affecting skeletal muscles. It commonly presents in childhood and rarely in adults with symptoms like exercise intolerance, muscle weakness, cramps and fatigue. Herein, we report an unusual case of a 22 years old male in Pakistan with probable McArdle’s Disease presenting with repeated episodes of generalized cramping muscle pain, exercise intolerance and haematuria. The diagnostic approach to identifying this disease as well as the differentials of other rare types of skeletal muscle disorders that should be kept in mind while dealing with a similar clinical picture, irrespective of the age of presentation, have been discussed. Keywords: Glycogen Storage Disease Type V, Myoglobinuria.

Exploring the metabolic and antioxidant potential of solergy: Implications for enhanced animal production

Cell models are indispensable tools in biotechnology when investigating the functional properties of organic compounds. The emergence of various additives designed to enhance animal production has introduced the need for in-depth evaluations, which are often hindered by the complexities of in vivo testing. In this study, we harnessed cell-based models to scrutinize the impact of Solergy as a regulator of cellular metabolism with a particular focus on its modulation of glycogen and antioxidant effects. Our experiment was designed to include assessments of the influence of Solergy on the viability of both terrestrial and aquatic vertebrate cell models, which revealed the benign nature of Solergy and its lack of adverse effects. Furthermore, we examined the capacity of Solergy to modulate intracellular ATP concentrations and enhance glycogen accumulation. Notably, the antioxidant potential of Solergy and its ability to mitigate cellular aging were evaluated within the same cellular frameworks. The outcomes of our investigation suggest that Solergy is a potent metabolic regulator that elevates cellular activity while exerting an antioxidant effect. Importantly, our study demonstrates that Solergy does not induce changes in membrane oxidation. These findings indicate the potential of using Solergy to regulate glycogen synthesis, intracellular ATP concentrations, and oxidative stress in production animals. The multifaceted effects of this additive, which acts as both a metabolism enhancer and an antioxidant, open doors to the creation of custom diets tailored to meet specific production needs while maintaining stable production parameters.

In vivo characterization of glycogen storage disease type III in a mouse model using glycoNOE MRI.

Glycogen storage disease type III (GSD III) is a rare inherited metabolic disease characterized by excessive accumulation of glycogen in liver, skeletal muscle, and heart. Currently, there are no widely available noninvasive methods to assess tissue glycogen levels and disease load. Here, we use glycogen nuclear Overhauser effect (glycoNOE) MRI to quantify hepatic glycogen levels in a mouse model of GSD III. Agl knockout mice (n = 13) and wild-type controls (n = 10) were scanned for liver glycogen content using glycoNOE MRI. All mice were fasted for 12 to 16 h before MRI scans. GlycoNOE signal was quantified by fitting the Z-spectrum using a four-pool Voigt lineshape model. Next, the fitted direct water saturation pool was removed and glycoNOE signal was estimated from the integral of the residual Z spectrum within -0.6 to -1.4 ppm. Glycogen concentration was also measured ex vivo using a biochemical assay. GlycoNOE MRI clearly distinguished Agl knockout mice from wild-type controls, showing a statistically significant difference in glycoNOE signals in the livers across genotypes. There was a linear correlation between glycoNOE signal and glycogen concentration determined by the biochemical assay. The obtained glycoNOE maps of mouse livers also showed higher glycogen levels in Agl knockout mice compared to wild-type mice. GlycoNOE MRI was used successfully as a noninvasive method to detect liver glycogen levels in mice, suggesting the potential of this method to be applied to assess glycogen storage diseases.

Hepatic ChREBP orchestrates intrahepatic carbohydrate metabolism to limit hepatic glucose 6-phosphate and glycogen accumulation in a mouse model for acute Glycogen Storage Disease type Ib

ObjectiveCarbohydrate Response Element Binding Protein (ChREBP) is a glucose 6-phosphate (G6P)-sensitive transcription factor that acts as a metabolic switch to maintain intracellular glucose and phosphate homeostasis. Hepatic ChREBP is well-known for its regulatory role in glycolysis, the pentose phosphate pathway, and de novo lipogenesis. The physiological role of ChREBP in hepatic glycogen metabolism and blood glucose regulation has not been assessed in detail, and ChREBP's contribution to carbohydrate flux adaptations in hepatic Glycogen Storage Disease type 1 (GSD I) requires further investigation. MethodsThe current study aimed to investigate the role of ChREBP as a regulator of glycogen metabolism in response to hepatic G6P accumulation, using a model for acute hepatic GSD type Ib. The immediate biochemical and regulatory responses to hepatic G6P accumulation were evaluated upon G6P transporter inhibition by the chlorogenic acid S4048 in mice that were either treated with a short hairpin RNA (shRNA) directed against ChREBP (shChREBP) or a scrambled shRNA (shSCR). Complementary stable isotope experiments were performed to quantify hepatic carbohydrate fluxes in vivo. ResultsShChREBP treatment normalized the S4048-mediated induction of hepatic ChREBP target genes to levels observed in vehicle- and shSCR-treated controls. In parallel, hepatic shChREBP treatment in S4048-infused mice resulted in a more pronounced accumulation of hepatic glycogen and further reduction of blood glucose levels compared to shSCR treatment. Hepatic ChREBP knockdown modestly increased glucokinase (GCK) flux in S4048-treated mice while it enhanced UDP-glucose turnover as well as glycogen synthase and phosphorylase fluxes. Hepatic GCK mRNA and protein levels were induced by shChREBP treatment in both vehicle- and S4048-treated mice, while glycogen synthase 2 (GYS2) and glycogen phosphorylase (PYGL) mRNA and protein levels were reduced. Finally, knockdown of hepatic ChREBP expression reduced starch domain binding protein 1 (STBD1) mRNA and protein levels while it inhibited acid alpha-glucosidase (GAA) activity, suggesting reduced capacity for lysosomal glycogen breakdown. ConclusionsOur data show that ChREBP activation controls hepatic glycogen and blood glucose levels in acute hepatic GSD Ib through concomitant regulation of glucose phosphorylation, glycogenesis, and glycogenolysis. ChREBP-mediated control of GCK enzyme levels aligns with corresponding adaptations in GCK flux. In contrast, ChREBP activation in response to acute hepatic GSD Ib exerts opposite effects on GYS2/PYGL enzyme levels and their corresponding fluxes, indicating that GYS2/PYGL expression levels are not limiting to their respective fluxes under these conditions.

Skeletal Muscle Involvement in Patients With Truncations of Titin and Familial Dilated Cardiomyopathy

BackgroundGenetic variants in titin (TTN) are associated with dilated cardiomyopathy (DCM) and skeletal myopathy. However, the skeletal muscle phenotype in individuals carrying heterozygous truncating TTN variants (TTNtv), the leading cause of DCM, is understudied. ObjectivesThis study aimed to assess the skeletal muscle phenotype associated with TTNtv. MethodsParticipants with TTNtv were included in a cross-sectional study. Skeletal muscle fat fraction was evaluated by magnetic resonance imaging (compared with healthy controls and controls with non-TTNtv DCM). Muscle strength was evaluated by dynamometry and muscle biopsy specimens were analyzed. ResultsTwenty-five TTNtv participants (11 women, mean age 51 ± 15 years, left ventricular ejection fraction 45% ± 10%) were included (19 had DCM). Compared to healthy controls (n = 25), fat fraction was higher in calf (12.5% vs 9.9%, P = 0.013), thigh (12.2% vs 9.3%, P = 0.004), and paraspinal muscles (18.8% vs 13.9%, P = 0.008) of TTNtv participants. Linear mixed effects modelling found higher fat fractions in TTNtv participants compared to healthy controls (2.5%; 95% CI: 1.4-3.7; P < 0.001) and controls with non-TTNtv genetic DCM (n = 7) (1.5%; 95% CI: 0.2-2.8; P = 0.025). Muscle strength was within 1 SD of normal values. Biopsy specimens from 21 participants found myopathic features in 13 (62%), including central nuclei. Electron microscopy showed well-ordered Z-lines and T-tubuli but uneven and discontinuous M-lines and excessive glycogen depositions flanked by autophagosomes, lysosomes, and abnormal mitochondria with mitophagy. ConclusionsMild skeletal muscle involvement was prevalent in patients with TTNtv. The phenotype was characterized by an increased muscle fat fraction and excessive accumulation of glycogen, possibly due to reduced autophagic flux. These findings indicate an impact of TTNtv beyond the heart.

Glycogen storage disease type Ib: modern understanding of the pathogenesis of neutropenia and prospects for its treatment with empagliflozin

Glycogen storage disease type Ib (GSD Ib) — is a disease from the group of hereditary metabolic diseases caused by insufficiency of the glucose-6-phosphate transporter (G6PT, SLC37A4), which leads to a violation of both glycogenolysis and gluconeogenesis and, as a consequence, to excessive accumulation of glycogen and fat in the liver, kidneys and intestinal mucosa. The main clinical manifestations and laboratory data include growth retardation, hepatomegaly, hypoglycemia, lactic acidosis, hyperuricemia and hyperlipidemia. Complications of this disease are hepatocellular adenoma with a possible risk of malignancy, nephropathy and osteoporosis. A specific sign of GSD Ib is neutropenia with impaired neutrophil function, which creates prerequisites for recurrent infections and the development of inflammatory bowel disease. Until the present, enzyme replacement therapy of GSD Ib has not been developed, therefore, the main methods of treatment are a specialized diet with the addition of raw corn starch (for relief of hypoglycemia) and the use of granulocyte colony stimulating factor (for relief of neutropenia). However, the recent establishment of the role of 1,5-anhydroglucitol in the pathogenesis of neutrophil dysfunction in GSD Ib has led to a reprofiling of indications for the use of empagliflozin, a type 2 renal sodium—glucose cotransporter inhibitor (SGLT2). In the modern literature, it is reported about a minor, but very successful experience of its use in patients with GSD Ib (outside the framework of official indications for use) and a beneficial effect on neutrophil dysfunction and its clinical consequences. Oddly enough, this hypoglycemic drug improved not only metabolic, but also glycemic control in patients with GSD Ib, despite the fact that the pathology is based on chronic hypoglycemia. More and more evidence points to the role of empagliflozin in the regulation of cellular homeostasis (for example, fatty acid metabolism, glucose, cholesterol, apoptosis and cell proliferation, in particular in the liver) by influencing the activity of sirtuin 1 (SIRT1), AMP-activated protein kinase (AMPK) and signal molecules such as -serine/threonine protein kinase (Akt) and a mechanical target of rapamycin (mTOR), which leads to an improvement in the structure and function of mitochondria, stimulation of autophagy, reducing oxidative stress and suppressing inflammation. Modulation of these pathways shifts oxidative metabolism from carbohydrates to lipids and leads to a key decrease in insulin levels, resistance to it, glucose and lipotoxicity. This review presents current data on the pathogenesis of neutropenia and the possibility of using empagliflozin for its relief in patients with GSD Ib.

Skeletal muscle involvement in patients with truncations of titin and familial dilated cardiomyopathy

Abstract Background Variants in TTN are associated with dilated cardiomyopathy (DCM) and skeletal myopathy with or without cardiac affection. However, the skeletal muscle phenotype has not been systematically evaluated in patients with predisposition to or manifest cardiac involvement due to heterozygous truncating TTN variants (TTNtv), the most common cause of DCM. Purpose Assess the skeletal muscle phenotype associated with TTNtv. Methods This cross-sectional study examined skeletal muscle involvement in individuals with TTNtv by quantifying and comparing fat fraction from muscle magnetic resonance imaging to controls (matched on body-size, sex, and age), and evaluating muscle strength by dynamometry and features from muscle biopsies. Results Twenty-five participants (11 women, age 51±15 years, left ventricular ejection fraction 45±10%) with TTNtv were included (19 had DCM). Compared to controls, participants with TTNtv had higher fat fraction in calf- (12.5% vs 9.9%, p=0.013), thigh- (12.2% vs 9.3%, p=0.004) and paraspinal muscles (18.8% vs 13.9%, p=0.008), see figure. Muscle strength was relatively intact (within 1 SD of normal values). Muscle biopsies in 21 participants showed that 13 (62%) displayed myopathic features, most notably an increased proportion of central nuclei. Electron microscopy showed well-ordered Z-lines and T-tubuli but uneven and discontinuous M-lines and excessive glycogen depositions flanked by large autophagosomes, lysosomes, and abnormal mitochondria with mitophagy. Conclusion Skeletal muscle involvement is prevalent in patients with cardiac involvement or predisposition to DCM due to TTNtv and is characterized by an increased muscle fat fraction, and excessive accumulation of glycogen, possibly due to reduced autophagic flux. This emphasizes the need for specialized diagnostic work-up in patients with TTNtv, especially if reporting symptoms or objective signs of muscle involvement.

Improved lipid production and component of mycosporine-like amino acids by co-overexpression of amt1 and aroB genes in Synechocystis sp. PCC6803

Implementing homologous overexpression of the amt1 (A) and aroB (B) genes involved in ammonium transporter and the synthesis of mycosporine-like amino acids (MAAs) and aromatic amino acids, respectively, we created three engineered Synechocystis sp. PCC6803 strains, including Ox-A, Ox-B, and Ox-AB, to study the utilization of carbon and nitrogen in cyanobacteria for the production of valuable products. With respect to amt1 overexpression, the Ox-A and Ox-AB strains had a greater growth rate under (NH4)2SO4 supplemented condition. Both the higher level of intracellular accumulation of lipids in Ox-A and Ox-AB as well as the increased secretion of free fatty acids from the Ox-A strain were impacted by the late-log phase of cell growth. It is noteworthy that among all strains, the Ox-B strain undoubtedly spotted a substantial accumulation of glycogen as a consequence of aroB overexpression. Additionally, the ammonium condition drove the potent antioxidant activity in Ox strains with a late-log phase, particularly in the Ox-B and Ox-AB strains. This was probably related to the altered MAA component inside the cells. The higher proportion of P4-fraction was induced by the ammonium condition in both Ox-B and Ox-AB, while the noted increase of the P1 component was found in the Ox-A strain.

Abstract 18811: Heart Failure in a Carrier of Danon Disease

Background: Danon Disease is a rare X-linked dominant genetic condition characterized by hypertrophic cardiomyopathy, skeletal muscle myopathy, and intellectual disability, among other serious complications. The disease is a lysosomal storage disorder in which a mutation in the LAMP-2 gene causes a defect in the lysosome membrane and an accumulation of glycogen in vital tissue including cardiac muscle cells. It occurs more commonly in males, who are also more severely affected than females with this condition. There are no specific treatments available, although studies involving gene therapy have been ongoing. Patients with Danon Disease often require heart transplantation as treatment for end-stage heart failure. Description of Case: A 37-year-old female with a known family history of Danon Disease was discovered to be a carrier of the LAMP-2 mutation after presenting to the hospital with dizziness and palpitations. An echocardiogram obtained at the time of diagnosis revealed left ventricular hypertrophy and left ventricular apical thrombus with normal ejection fraction. She was started on anticoagulation and began following closely with a heart failure clinic. Since diagnosis, she has had multiple echocardiograms which have shown a steady decline in her ejection fraction to 25% and biventricular failure. An ICD was placed, with no shocks ever administered. She has had multiple hospital admissions for exacerbations of heart failure since diagnosis. Telemetry monitoring during these admissions revealed frequent premature ventricular contractions attributed to the patient’s severe cardiomyopathy. Despite continuation of guideline-directed medical treatment, this patient’s systolic heart failure is anticipated to continue worsening. She will likely require heart transplant, for which evaluation has already been initiated. Discussion: Danon Disease is a rare lysosomal storage disorder that often involves progressively worsening cardiomyopathy. Individuals with a known family history of this condition should be referred early for genetic testing. If found to have the condition or be a carrier, they should begin following with a heart failure specialist and consideration for advanced therapies, like transplant, should be initiated.

Abstract 17085: An Unusual Case of Severe Hypertrophic Cardiomyopathy in a 23-Year-Old Systemic Lupus Erythematosus Patient on Hydroxychloroquine

A 23-year-old female with Systemic lupus erythematosus (SLE), lupus nephritis, antiphospholipid syndrome, venous thromboembolism, stroke, Libman-Sacks endocarditis, and hypertension presented with right upper and lower extremity weakness, right facial droop, and aphasia. Her home medications included hydroxychloroquine, mycophenolate, apixaban, and losartan. ECG showed normal sinus rhythm, left atrial enlargement, ST and T wave abnormalities in V5 and V6. Computed tomography angiography of the brain showed left middle cerebral artery occlusion. Transthoracic echocardiogram (TTE) showed left ventricular ejection fraction of 65%, severe left ventricular hypertrophy, moderate pericardial effusion, and moderately thickened mitral valve (MV) leaflets. Transesophageal echocardiogram showed large vegetations on atrial aspect of both MV leaflets concerning for Libman-Sacks endocarditis. We attempt to investigate the cause of this hypertrophic cardiomyopathy (HCM) in a young patient with SLE. Few reported cases of HCM in patients with SLE were medication induced. Tacrolimus has been observed to induced HCM in a Japanese patient with dermatomyositis. Hydroxychloroquine has been associated with myocardial thickening. Its use can lead to enlarged myocardiocytes with intracytoplasmic vacuoles consisting of concentric lamellar myelin figures in single membrane bound vesicles, curvilinear bodies, glycogen accumulation and fused mitochondria. Hydroxychloroquine use led to reversible inhibition of lysosomal enzyme activity. Cessation of medication use in both cases led to reduction in left ventricle thickness. These patients, like our own, has no family history of aortic valve stenosis, mitral valve prolapse, or HCM. However, this patient’s use of hydroxychloroquine to treat her SLE can be assumed to be a contributing factor to her HCM. This could suggest possible screening with ECG and TTE in patients taking hydroxychloroquine.

Abstract 16957: PRKAG2 Directly Interacts With Myosin Heavy Chains to Modulate Myocyte Electrical and Morphological Changes in Cardiac Hypertrophy

Introduction: Mutations in the PRKAG2 gene cause a complex myocardial disorder characterized by hypertrophic cardiomyopathy (HCM) and conduction disturbances. While prior studies associated PRKAG2 -linked hypertrophy with increased glycogen storage, many HCM phenotypes in the disorder remain unexplained by this effect alone. We aimed to uncover the molecular mechanisms by which PRKAG2 mutations induce myocyte hypertrophy and electrical changes during cardiac development. Methods: We created transgenic zebrafish expressing WT (Tg WT ) and pathological mutant (Tg R299Q ) murine Prkag2 cDNA under a myocardium-specific promoter. Using these models, we studied the impact of Prkag2 variant on myocyte electrical activity, metabolism, and cytoarchitecture across cardiogenesis and in mature hearts. Results: Tg R299Q adult fish showed hypertrophic cardiomyocytes, swollen mitochondria, and shortened sarcomere length compared to Tg WT and WT, mirroring human HCM phenotypes. The glycogen content was elevated in adult hearts but not during early cardiogenesis. Despite the absence of glycogen accumulation at 6-day post fertilization, Tg R299Q hearts showed electrical abnormalities, including a reduced conduction velocity, decreased Ca 2+ amplitude, and prolonged action potential durations in both atria and ventricles, compared to Tg WT and WT. Co-immunoprecipitation and proximity ligation assay revealed physical interactions between Prkag2 and myosin heavy chain (MYH), with the R299Q variant enhancing this interaction and altering the subcellular localization of Prkag2 from mitochondria to sarcomeres. Knockdown of the fish homolog of MYH7 ( vmhcl ) restored the early electrical disturbances caused by Tg R299Q . This abnormal MYH-Prkag2 interaction disturbed mitochondria and sarcomere organization contributing to altered myocyte cytoarchitecture observed in Tg R299Q . Conclusions: Mutant PRKAG2 altered cardiac excitability and Ca 2+ handling during embryogenesis, preceding glycogen accumulation. Enhanced binding between Prkag2 and MYHs contributed to these early changes. Our study revealed a novel link between sarcomere proteins and metabolic regulators in cardiac hypertrophy, suggesting a new therapeutic avenue for treating HCM.