bims-glecem 2022-06-26 papers

bims-glecem

Biomed News

on Glycogen metabolism in exercise, cancer and energy metabolism

Issue of 2022–06–26
fourteen papers selected by
Dipsikha Biswas, Københavns Universitet

Glycogen phosphorylase isoform regulation of glucose and Energy Sensor expression in male versus female rat hypothalamic astrocyte primary cultures.
Glycogen storage diseases with liver involvement: a literature review of GSD type 0, IV, VI, IX and XI.
HM-chromanone suppresses hepatic glucose production via activation of AMP-activated protein kinase in HepG2 cell.
Early synaptic deficits in GSK-3β overexpressing mice.
Correction to: Acute arm and leg muscle glycogen and metabolite responses to small-sided football games in healthy young men.
Energy Metabolism in Mouse Sciatic Nerve A Fibres during Increased Energy Demand.
Many faces and functions of GSKIP: a temporospatial regulation view.
Nutritional co-therapy with 1,3-butanediol and multi-ingredient antioxidants enhances autophagic clearance in Pompe disease.
Discovery of GSK3β Inhibitors through In Silico Prediction-and-Experiment Cycling Strategy, and Biological Evaluation.
TCR activation directly stimulates PYGB-dependent glycogenolysis to fuel the early recall response in CD8+ memory T cells.
Selective GSK3β Inhibition Mediates an Nrf2-Independent Anti-inflammatory Microglial Response.
Taurine Ameliorates Streptozotocin-Induced Diabetes by Modulating Hepatic Glucose Metabolism and Oxidative Stress in Mice.
GSK3B Overexpression Alleviates Posttraumatic Osteoarthritis in Mice by Promoting DNMT1-Mediated Hypermethylation of NR4A3 Promoter.
Duchenne Muscular Dystrophy With Low Acidic α-Glucosidase Activity: Two Case Reports and Literature Review.

Mol Cell Endocrinol. 2022 Jun 16. pii: S0303-7207(22)00146-0. [Epub ahead of print] 111698

Glycogen phosphorylase isoform regulation of glucose and Energy Sensor expression in male versus female rat hypothalamic astrocyte primary cultures.

Abdulrahman Alhamyani, Prabhat R Napit, Khaggeswar Bheemanapally, Mostafa M H Ibrahim, Paul W Sylvester, Karen P Briski.

  Astrocyte glycogen constitutes the primary energy fuel reserve in the brain. Current research investigated the novel premise that glycogen turnover governs astrocyte responsiveness to critical metabolic and neurotransmitter (i.e. norepinephrine) regulatory signals in a sex-dimorphic manner. Here, rat hypothalamic astrocyte glycogen phosphorylase (GP) gene expression was silenced by short-interfering RNA (siRNA) to investigate how glycogen metabolism controlled by GP-brain type (GPbb) or GP-muscle type (GPmm) activity affects glucose [glucose transporter-2 (GLUT2)] and energy [5'-AMP-activated protein kinase (AMPK)] biomarker and adrenergic receptor (AR) proteins in each sex. Results show that in the presence of glucose, glycogen turnover is regulated by GPbb in the male or by GPmm in the female, yet in the absence of glucose, glycogen breakdown is controlled by GPbb in each sex. GLUT2 expression is governed by GPmm-mediated glycogen breakdown in glucose-supplied astrocytes of each sex, but glycogenolysis regulates sex-specific glucoprivic GLUT2 up-regulation in the male. GPbb-mediated glycogen disassembly regulates total AMPK and phosphoAMPK levels in male, but not female. During glucoprivation, glycogenolysis up-regulates AMPK content in male astrocytes by GPbb- and GPmm-dependent mechanisms, whereas GPbb-mediated glycogen breakdown inhibits phosphoAMPK expression in female. GPbb and GPmm activity governs alpha2-AR and beta1-AR protein levels in male, but has no effect on these profiles in the female. Outcomes provide novel evidence for sex-specific glycogen regulation of glucose- and energy-sensory protein expression in hypothalamic astrocytes, and identify GP isoforms that mediate such control in each sex. Results also show that glycogen regulation of hypothalamic astrocyte receptivity to norepinephrine is male-specific. Further studies are needed to characterize the molecular mechanisms that underlie sex differences in glycogen control of astrocyte protein expression.

Keywords:  AMPK; Adrenergic receptor; GLUT2; Glycogen; Glycogen phosphorylase; Sex differences

DOI:  https://doi.org/10.1016/j.mce.2022.111698
Orphanet J Rare Dis. 2022 06 20. 17(1): 241

Glycogen storage diseases with liver involvement: a literature review of GSD type 0, IV, VI, IX and XI.

Miriam Massese, Francesco Tagliaferri, Carlo Dionisi-Vici, Arianna Maiorana.

   BACKGROUND: Glycogen storage diseases (GSDs) with liver involvement are classified into types 0, I, III, IV, VI, IX and XI, depending on the affected enzyme. Hypoglycemia and hepatomegaly are hallmarks of disease, but muscular and renal tubular involvement, dyslipidemia and osteopenia can develop. Considering the paucity of literature available, herein we provide a narrative review of these latter forms of GSDs.
MAIN BODY: Diagnosis is based on clinical manifestations and laboratory test results, but molecular analysis is often necessary to distinguish the various forms, whose presentation can be similar. Compared to GSD type I and III, which are characterized by a more severe impact on metabolic and glycemic homeostasis, GSD type 0, VI, IX and XI are usually known to be responsive to the nutritional treatment for achieving a balanced metabolic homeostasis in the pediatric age. However, some patients can exhibit a more severe phenotype and an important progression of the liver and muscular disease. The effects of dietary adjustments in GSD type IV are encouraging, but data are limited.
CONCLUSIONS: Early diagnosis allows a good metabolic control, with improvement of quality of life and prognosis, therefore we underline the importance of building a proper knowledge among physicians about these rare conditions. Regular monitoring is necessary to restrain disease progression and complications.

Keywords:  GSDs; Glycogen storage diseases; Hypoglycemia

DOI:  https://doi.org/10.1186/s13023-022-02387-6
Eur J Pharmacol. 2022 Jun 16. pii: S0014-2999(22)00369-7. [Epub ahead of print] 175108

HM-chromanone suppresses hepatic glucose production via activation of AMP-activated protein kinase in HepG2 cell.

Jae Eun Park, Ji Sook Han.

  We investigated whether (E)-5-hydroxy-7-methoxy-3-(2-hydroxybenzyl)-4-chromanone (HM-chromanone) could suppress the transcription factors expression and enzymes involved in glucose production by activating AMPK in hepatocytes. HepG2 cells were treated with a medium containing HM-chromanone (5-100 μM), compound C (10 μM) and insulin (100 nM). Glucose production and glycogen synthesis assay were determined using a glucose assay kit and glycogen assay kit, respectively. Activities of AMP-activated protein kinase (AMPK), acetyl CoA carboxylase (ACC), cAMP response element-binding protein (CREB), PPAR coactivator-1α (PGC1α), CREB-regulated transcription coactivator 2 (CRTC2), Glycogen synthase kinase (GSK3β), Phosphoenolpyruvate carboxykinase (PEPCK), glycogen synthase (GS), Glucose 6-phosphatase (G6pase) and β-actin were determined by Western blot analysis. HM-chromanone significantly inhibited hepatic glucose production and increased glycogen synthesis by activating glycogen synthase. HM-chromanone induced the phosphorylation of CRTC2 and GSK-3β by phosphorylating AMPK in HepG2 cells, which was confirmed by compound C. Furthermore, it significantly decreased the phosphorylation of CREB in a time- and concentration-dependent manner, and the effect was reversed in the presence of compound C. Therefore, the complex formation of CRTC2 and CREB was inhibited. HM-chromanone inhibited the expression of PGC-1α, PEPCK, and G6Pase genes involved in production of hepatic glucose. The results showed that HM-chromanone activates AMPK in a time and concentration dependent manner, thus suppressing hepatic glucose production and increasing glycogen synthesis in HepG2 cells.

Keywords:  AMPK; HM-Chromanone; HepG2 cell; Hepatic glucose production; Portulaca oleracea L.

DOI:  https://doi.org/10.1016/j.ejphar.2022.175108
Neurosci Lett. 2022 Jun 16. pii: S0304-3940(22)00305-6. [Epub ahead of print] 136744

Early synaptic deficits in GSK-3β overexpressing mice.

Ewa Banach, Tomasz Jaworski, Joanna Urban-Ciećko.

  Synaptic dysfunction is the prominent feature of many neuropsychiatric and neurological diseases, in which glycogen synthase kinase 3β (GSK-3β) has been shown to play a role. Overexpression of constitutively active form of GSK-3β (GSK-3β[S9A]) in mice recapitulates the cognitive and structural brain deficits characteristic for manic phase of bipolar disorder (BD). Yet, the mechanisms underlying GSK-3β-induced synaptic dysfunction have not been fully elucidated. The aim of the present study was to dissect the effect of GSK-3β overactivity on synaptic function in adolescent (3-week-old) mice. We found that overactivity of GSK-3β in adolescent transgenic mice leads to an alteration in dendritic spines morphology of granule cells in dentate gyrus (DG) without changes in overall spine density. There was an increase in the number of thin, presumably immature dendritic spines in GSK-3β[S9A] mice. Subsequent electrophysiological analysis showed changes in excitatory synaptic transmission manifested by an increase of inter-event intervals of miniature excitatory postsynaptic currents (mEPSCs) in DG granule cells and an increase in the number of silent (unfunctional) synapses at the perforant path-DG pathway in GSK-3β[S9A] mice. Altogether, our data indicate that GSK-3β overactivity leads to synaptic deficits in adolescent, GSK-3β[S9A] mice. These data might provide potential mechanisms underlying GSK-3β-induced synaptic dysfunction in psychiatric disorders.

Keywords:  GSK-3β; glycogen synthase kinase 3β; mEPSCs; synaptic plasticity

DOI:  https://doi.org/10.1016/j.neulet.2022.136744
Eur J Appl Physiol. 2022 Jun 24.

Correction to: Acute arm and leg muscle glycogen and metabolite responses to small-sided football games in healthy young men.

Jeppe Panduro, Jeppe F Vigh-Larsen, Georgios Ermidis, Susana Póvoas, Jakob Friis Schmidt, Karen Søgaard, Peter Krustrup, Magni Mohr, Morten Bredsgaard Randers.

DOI: https://doi.org/10.1007/s00421-022-04984-6
Metabolites. 2022 May 31. pii: 505. [Epub ahead of print]12(6):

Energy Metabolism in Mouse Sciatic Nerve A Fibres during Increased Energy Demand.

Laura R Rich, Bruce R Ransom, Angus M Brown.

  The ability of sciatic nerve A fibres to conduct action potentials relies on an adequate supply of energy substrate, usually glucose, to maintain necessary ion gradients. Under our ex vivo experimental conditions, the absence of exogenously applied glucose triggers Schwann cell glycogen metabolism to lactate, which is transported to axons to fuel metabolism, with loss of the compound action potential (CAP) signalling glycogen exhaustion. The CAP failure is accelerated if tissue energy demand is increased by high-frequency stimulation (HFS) or by blocking lactate uptake into axons using cinnemate (CIN). Imposing HFS caused CAP failure in nerves perfused with 10 mM glucose, but increasing glucose to 30 mM fully supported the CAP and promoted glycogen storage. A combination of glucose and lactate supported the CAP more fully than either substrate alone, indicating the nerve is capable of simultaneously metabolising each substrate. CAP loss resulting from exposure to glucose-free artificial cerebrospinal fluid (aCSF) could be fully reversed in the absence of glycogen by addition of glucose or lactate when minimally stimulated, but imposing HFS resulted in only partial CAP recovery. The delayed onset of CAP recovery coincided with the release of lactate by Schwann cells, suggesting that functional Schwann cells are a prerequisite for CAP recovery.

Keywords:  glucose; glycogen; lactate; recovery

DOI:  https://doi.org/10.3390/metabo12060505
Cell Signal. 2022 Jun 18. pii: S0898-6568(22)00153-X. [Epub ahead of print] 110391

Many faces and functions of GSKIP: a temporospatial regulation view.

Nian-Siou Wu, Yi-Fan Lin, I Chu Ma, Huey-Jiun Ko, Yi-Ren Hong.

  Glycogen synthase kinase 3 (GSK3)-β (GSK3β) interaction protein (GSKIP) is one of the smallest A-kinase anchoring proteins that possesses a binding site for GSK3β. Recently, our group identified the protein kinase A (PKA)-GSKIP-GSK3β-X axis; knowledge of this axis may help us decipher the many roles of GSKIP and perhaps help explain the evolutionary reason behind the interaction between GSK3β and PKA. In this review, we highlight the critical and multifaceted role of GSKIP in facilitating PKA kinase activity and its function as a scaffolding protein in signaling pathways. We also highlight how these pivotal PKA and GSK3 kinases can control context-specific functions and interact with multiple target proteins, such as β-catenin, Drp1, Tau, and other proteins. GSKIP is a key regulator of multiple mechanisms because of not only its location at certain subcellular compartments but also its serial changes during the developmental process. Moreover, the involvement of critical upstream regulatory signaling pathways in GSKIP signaling in various cancers, such as miRNA (microRNA) and lncRNA (long noncoding RNA), may help in the identification of therapeutic targets in the era of precision medicine and personalized therapy. Finally, we emphasize on the model of the early stage of pathogenesis of Alzheimer Disease (AD). Although the model requires validation, it can serve as a basis for diagnostic biomarkers development and drug discovery for early-stage AD.

Keywords:  AKAP; GSK3; GSKIP; PKA; PKA–GSKIP–GSK3 axis

DOI:  https://doi.org/10.1016/j.cellsig.2022.110391
Mol Genet Metab. 2022 Jun 11. pii: S1096-7192(22)00337-7. [Epub ahead of print]

Nutritional co-therapy with 1,3-butanediol and multi-ingredient antioxidants enhances autophagic clearance in Pompe disease.

Mats I Nilsson, Michael Crozier, Alessia Di Carlo, Donald Xhuti, Katherine Manta, Liza J Roik, Adam L Bujak, Joshua P Nederveen, Milla G Tarnopolsky, Bart Hettinga, Naresh K Meena, Nina Raben, Mark A Tarnopolsky.

  Alglucosidase alpha is an orphan drug approved for enzyme replacement therapy (ERT) in Pompe disease (PD); however, its efficacy is limited in skeletal muscle because of a partial blockage of autophagic flux that hinders intracellular trafficking and enzyme delivery. Adjunctive therapies that enhance autophagic flux and protect mitochondrial integrity may alleviate autophagic blockage and oxidative stress and thereby improve ERT efficacy in PD. In this study, we compared the benefits of ERT combined with a ketogenic diet (ERT-KETO), daily administration of an oral ketone precursor (1,3-butanediol; ERT-BD), a multi-ingredient antioxidant diet (ERT-MITO; CoQ10, α-lipoic acid, vitamin E, beetroot extract, HMB, creatine, and citrulline), or co-therapy with the ketone precursor and multi-ingredient antioxidants (ERT-BD-MITO) on skeletal muscle pathology in GAA-KO mice. We found that two months of 1,3-BD administration raised circulatory ketone levels to ≥1.2 mM, attenuated autophagic buildup in type 2 muscle fibers, and preserved muscle strength and function in ERT-treated GAA-KO mice. Collectively, ERT-BD was more effective vs. standard ERT and ERT-KETO in terms of autophagic clearance, dampening of oxidative stress, and muscle maintenance. However, the addition of multi-ingredient antioxidants (ERT-BD-MITO) provided the most consistent benefits across all outcome measures and normalized mitochondrial protein expression in GAA-KO mice. We therefore conclude that nutritional co-therapy with 1,3-butanediol and multi-ingredient antioxidants may provide an alternative to ketogenic diets for inducing ketosis and enhancing autophagic flux in PD patients.

Keywords:  1,3-butanediol; Antioxidants; Autophagy; GAA; Galectin-3; Glycogen; Ketogenic diet; Ketone precursor; Ketones; Lysosome; Mitochondria; Myozyme; Oxidative Stress; Pompe; ROS; SQSTM1; Skeletal muscle; p62

DOI:  https://doi.org/10.1016/j.ymgme.2022.06.001
Molecules. 2022 Jun 14. pii: 3825. [Epub ahead of print]27(12):

Discovery of GSK3β Inhibitors through In Silico Prediction-and-Experiment Cycling Strategy, and Biological Evaluation.

Yuno Lee, Sae-Bom Yoon, Hyowon Hong, Hyun Young Kim, Daeyoung Jung, Byoung-San Moon, Woo-Kyu Park, Sunkyung Lee, Hyukjin Kwon, Jihyeong Park, Heeyeong Cho.

  Direct inhibitors of glycogen synthase kinase 3β (GSK3β) have been investigated and reported for the past 20 years. In the search for novel scaffold inhibitors, 3000 compounds were selected through structure-based virtual screening (SBVS), and then high-throughput enzyme screening was performed. Among the active hit compounds, pyrazolo [1,5-a]pyrimidin-7-amine derivatives showed strong inhibitory potencies on the GSK3β enzyme and markedly activated Wnt signaling. The result of the molecular dynamics (MD) simulation, enhanced by the upper-wall restraint, was used as an advanced structural query for the SBVS. In this study, strong inhibitors designed to inhibit the GSK3β enzyme were discovered through SBVS. Our study provides structural insights into the binding mode of the inhibitors for further lead optimization.

Keywords:  GSK3β; HTRF; MD simulation; pyrazolopyrimidine

DOI:  https://doi.org/10.3390/molecules27123825
Mol Cell. 2022 Jun 17. pii: S1097-2765(22)00538-X. [Epub ahead of print]

TCR activation directly stimulates PYGB-dependent glycogenolysis to fuel the early recall response in CD8+ memory T cells.

Huafeng Zhang, Jincheng Liu, Zhuoshun Yang, Liping Zeng, Keke Wei, Liyan Zhu, Liang Tang, Dianheng Wang, Yabo Zhou, Jiadi Lv, Nannan Zhou, Ke Tang, Jingwei Ma, Bo Huang.

  Glycolysis facilitates the rapid recall response of CD8+ memory T (Tm) cells. However, it remains unclear whether Tm cells uptake exogenous glucose or mobilize endogenous sugar to fuel glycolysis. Here, we show that intracellular glycogen rather than extracellular glucose acts as the major carbon source for the early recall response. Following antigenic stimulation, Tm cells exhibit high glycogen phosphorylase (brain form, PYGB) activity, leading to glycogenolysis and release of glucose-6-phosphate (G6P). Elevated G6P mainly flows to glycolysis but is also partially channeled to the pentose phosphate pathway, which maintains the antioxidant capacity necessary for later recall stages. Mechanistically, TCR signaling directly induces phosphorylation of PYGB by LCK-ZAP70. Functionally, the glycogenolysis-fueled early recall response of CD8+ Tm cells accelerates the clearance of OVA-Listeria monocytogenes in an infected mouse model. Thus, we uncover a specific dependency on glycogen for the initial activation of memory T cells, which may have therapeutic implications for adaptive immunity.

Keywords:  CD8(+) memory T cells; PYGB; ZAP70; glycogen; recall response

DOI:  https://doi.org/10.1016/j.molcel.2022.06.002
Mol Neurobiol. 2022 Jun 23.

Selective GSK3β Inhibition Mediates an Nrf2-Independent Anti-inflammatory Microglial Response.

Mohamed H Yousef, Mohamed Salama, Hassan A N El-Fawal, Anwar Abdelnaser.

  Glycogen synthase kinase 3 (GSK3) is associated with the proinflammatory phenotype of microglia and has been shown to act in concert with nuclear factor kappa B (NF-κB). GSK3 is also a suppressor of nuclear factor erythroid 2-related factor 2 (Nrf2), the principal regulator of redox homeostasis. Agreeing with the oxidative paradigm of aging, Nrf2 is often deregulated in parainflammatory and neurodegenerative diseases. In this study, we aimed to explore a multimodal disease-modifying utility of GSK3 inhibition, beyond neuronal proteopathologies. Furthermore, we aimed to underscore the difference in therapeutic value between the two GSK3 paralogs by isoform-selective chemical inhibition. The anti-inflammatory effects of paralog-selective GSK3 inhibitors were evaluated as a function of the reductive capacity of each to mitigate LPS-induced activation of SIM-A9 microglia. The Griess method was employed to detect the nitrate-lowering capacity of selective GSK3 inhibition. Real-time PCR was used to assess post-treatment expression levels of pro-inflammatory markers and antioxidant genes; pro-inflammatory cytokines were assayed by ELISA. Nuclear lysates of treated cells were examined for Nrf2 and NF-κB accumulation by immunoblotting. Finally, to infer whether the counter-inflammatory activity of GSK3 inhibition was Nrf2-dependent, DsiRNA-mediated knockdown of Nrf2 was attempted. Results from our experiments reveal a superior anti-inflammatory and anti-oxidative efficacy for GSK3β-selective inhibition, compared to GSK3α-selective and non-selective pan-inhibition; hence, use of selective GSK3β inhibitors is likely to be more propitious than non-selective dual inhibitors administered at comparable doses. Moreover, our results suggest that the anti-inflammatory effects of GSK3 inhibition are not Nrf2 dependent.

Keywords:  GSK3; Microglia; NF-κB; Neurodegenerative diseases; Neuroinflammation; Nrf2; Oxidative stress; Paralog selectivity

DOI:  https://doi.org/10.1007/s12035-022-02923-2
Metabolites. 2022 Jun 06. pii: 524. [Epub ahead of print]12(6):

Taurine Ameliorates Streptozotocin-Induced Diabetes by Modulating Hepatic Glucose Metabolism and Oxidative Stress in Mice.

Shigeru Murakami, Kohei Funahashi, Natsuki Tamagawa, Ma Ning, Takashi Ito.

  Taurine is a sulfated amino acid derivative that plays an important role in maintaining the cell function of the living body. Although taurine has been shown to ameliorate diabetes, its mechanism of action has not yet been fully elucidated. The present study investigated the effects of taurine on diabetes focusing on glucose metabolism and oxidative stress. Type 1 diabetes was induced by the administration of streptozotocin (STZ) to male C57BL/6J mice. Taurine was dissolved in drinking water at 3% (w/v) and allowed to be freely ingested by diabetic mice. The weight and blood glucose levels were measured weekly. After nine weeks, mice were sacrificed and their serum, liver, and kidney were removed and used for biochemical and histological analyses. A microarray analysis was also performed in normal mice. Taurine alleviated STZ-induced hyperglycemia and hyperketonemia, accompanied by the suppression of the decrease in hepatic glycogen and upregulation of the mRNA expression of hepatic glucose transporter GLUT-2. Furthermore, STZ-induced elevation of oxidative stress in the liver and kidney was suppressed by taurine treatment. These results showed that taurine ameliorated diabetes and diabetic complications by improving hepatic glucose metabolism and reducing oxidative stress.

Keywords:  GLUT-2; diabetes; glucose metabolism; glycogen; oxidative stress; taurine

DOI:  https://doi.org/10.3390/metabo12060524
Dis Markers. 2022 ;2022 4185489

GSK3B Overexpression Alleviates Posttraumatic Osteoarthritis in Mice by Promoting DNMT1-Mediated Hypermethylation of NR4A3 Promoter.

Zhou Lv, Deping Sun, Xin Li, Gang Wu.

Background: Glycogen synthase kinase 3β (GSK3B) is reported to be a protective factor for the degradation of chondrocytes by extracellular mechanisms. Nuclear receptor subfamily 4 group A member 3 (NR4A3) is a proinflammatory factor in osteoarthritis. Their regulation mechanism in posttraumatic osteoarthritis (PTOA) is not fully understood.
Methods: GSK3B expression in the cartilage tissue of PTOA patients was analyzed by western blotting. IL-1β-induced chondrocytes were transfected with pcDNA-GSK3B, and then, the cell viability, apoptosis, expression of the chondrocyte extracellular matrix degradation-related genes MMP13, aggrecan, and type II collagen, and secretion of inflammatory factors TNF-α and IL-6 were detected. Co-IP was used to analyze the interaction between GSK3B and DNMT1. Ch-IP and methylation-specific PCR assays were used for methylation. Also, cells were transfected with pcDNA-GSK3B or together with pcDNA-NR4A3, as well as transfected with si-NR4A3, and then, cell functions were tested. Then, the mice subjected to destabilization of medial meniscus (DMM) surgery were intra-articular injected with 100 μL of the following adeno-related virus vectors (empty vector, Ad-GSK3B, scrambled shRNA, and sh-NR4A3), respectively, and the virus titer was 2 × 108 TU/mL. Cartilage integrity was evaluated by safranin O/fast green staining, HE staining, and Osteoarthritis Research Society International (OARSI) score.
Results: The expression of GSK3B protein was downregulated in PTOA patients. GSK3B overexpression alleviated IL-1β-induced chondrocyte apoptosis and extracellular matrix degradation, as well as cartilage mineralization in PTOA model mice. NR4A3 overexpression reversed the effect of GSK3B on IL-1β-induced chondrocyte functions. GSK3B could recruit DNMT1 to the NR4A3 promoter region to promote the methylation of NR4A3 and inhibit the expression of NR4A3 protein. Similarly, NR4A3 interference alleviated cartilage degradation under stimulating conditions by inhibiting the activation of the JAK2/STAT3 signaling pathway.
Conclusion: GSK3B recruits DNMT1 to the NR4A3 promoter region and inhibits the activation of the NR4A3-mediated JAK2/STAT3 signaling pathway, thereby alleviating PTOA.

DOI: https://doi.org/10.1155/2022/4185489
Front Pediatr. 2022 ;10 855510

Duchenne Muscular Dystrophy With Low Acidic α-Glucosidase Activity: Two Case Reports and Literature Review.

Xiufang He, Xuandi Li, Yuese Lin, Hongjun Ba, Huimin Peng, Lili Zhang, Ling Zhu, Youzhen Qin, Shujuan Li.

   Background: Pompe disease is usually considered in children with elevated creatine kinase (CK) levels and decreased acidic α-glucosidase (GAA) enzyme activity. However, there are exceptions, such as GAA pseudo deficiency alleles, which result in lower GAA enzyme activity but do not cause Pompe disease. Here, we report two cases presenting with high CK levels and low GAA activity who were ultimately diagnosed with Duchenne muscular dystrophy (DMD).
Case Presentation: Case 1 patient was a 2-month-old boy who presented with an extremely high serum CK level (5,480∼11,880 U/L) and low GAA activity (2.72 nmol/1 h/mg). The whole-exome sequencing did not find the pathogenic GAA gene mutation, however, there was a DMD gene hemizygous variation (c. 7657C > T, p. Arg2553Ter) inherited from his mother, which was verified by the first-generation sequencing. Further genetic analysis of GAA identified two homozygous pseudo deficiency alleles (c.1726G > A, p. Gly576Ser and c.2065G > A, p. Glu689Lys), which were believed to induce the patient's low GAA activity. Therefore, the boy was diagnosed with DMD, although he had extremely low GAA activity. Case 2 patient was also a 2-month-old boy presenting with a significant increase in CK level (12,408∼24,828 U/L). His blood GAA activity (colorimetric method) was 9.02 nmol/1 h/mg. Similarly, his whole-exome sequencing did not find the pathogenic mutation of the GAA gene, but a DMD gene hemizygous variation (c.5571del, p. Lys1857AsnfsTer8), hence he was diagnosed with DMD as well. Regarding GAA activity, the case 2 patient was not as low as the case 1 patient, mainly because his two GAA pseudo deficiency alleles were heterozygous.
Conclusion: Pompe disease is usually screened in infants with high CK levels. We should be aware that pseudo deficiency alleles can cause low GAA activities but not Pompe disease. Genetic tests would be helpful to distinguish cases with GAA pseudo deficiency alleles from patients with some muscular disorder diseases such as DMD.

Keywords:  Duchenne muscular dystrophy; acid α-glucosidase; child; creatine kinase; pseudodeficiency alleles

DOI:  https://doi.org/10.3389/fped.2022.855510