bims-glecem 2022-10-16 papers

Issue of 2022‒10‒16
five papers selected by
Dipsikha Biswas, Københavns Universitet

IUBMB Life. 2022 Oct 14.

Phosphorylase Phosphatase and Flash Activation of Skeletal Muscle Glycogen Phosphorylase - A Tribute to Edmond H. Fischer.

David L Brautigan.

Glycogen is a polymerized form of glucose that serves as an energy reserve in all types of organisms. In animals glycogen synthesis and degradation, especially in liver and skeletal muscle, are regulated by hormonal and physiological signals that reciprocally control the opposing activities of glycogen synthase and glycogen phosphorylase. These enzymes are under allosteric control by binding of metabolites (e.g. ATP, AMP, G6P) and covalent control by reversible phosphorylation by kinase and phosphatase all assembled together on glycogen. More than 50 years ago Edmond Fischer and colleagues showed "flash activation" of phosphorylase in glycogen particles. This involved transient and extensive inhibition of protein phosphatase but even today the phenomenon is not understood. Phosphatase regulation is known to rely on regulatory subunits including glycogen binding subunits that serve as scaffolds, binding catalytic subunit, glycogen, and substrates.. This tribute article to Edmond Fischer highlights his thoughts and ideas about the transient inhibition of phosphorylase phosphatase during flash activation of phosphorylase and speculates that phosphatase regulation in glycogen particles might involve a/b hybrids of phosphorylase.

DOI: https://doi.org/10.1002/iub.2683

Endocrinology. 2022 Oct 14. pii: bqac169. [Epub ahead of print]

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

Cole D Davidson, Jennifer A Tomczak, Eyal Amiel, Frances E Carr.

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 if 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 that presents a unique, oncogenic target that could offer an improved clinical outcome.

Keywords: 149; Anaplastic thyroid cancer; CP-91; cancer metabolism; glycogen; reactive oxygen species; sorafenib

DOI: https://doi.org/10.1210/endocr/bqac169

Molecules. 2022 Sep 26. pii: 6333. [Epub ahead of print]27(19):

A Novel 5-Chloro-N-phenyl-1H-indole-2-carboxamide Derivative as Brain-Type Glycogen Phosphorylase Inhibitor: Potential Therapeutic Effect on Cerebral Ischemia.

Yatao Huang, Shuai Li, Youde Wang, Zhiwei Yan, Yachun Guo, Liying Zhang.

Brain-type glycogen phosphorylase inhibitors are potential new drugs for treating ischemic brain injury. In our previous study, we reported compound 1 as a novel brain-type glycogen phosphorylase inhibitor with cardioprotective properties. We also found that compound 1 has high blood-brain barrier permeability through the ADMET prediction website. In this study, we deeply analyzed the protective effect of compound 1 on hypoxic-ischemic brain injury, finding that compound 1 could alleviate the hypoxia/reoxygenation (H/R) injury of astrocytes by improving cell viability and reducing LDH leakage rate, intracellular glucose content, and post-ischemic ROS level. At the same time, compound 1 could reduce the level of ATP in brain cells after ischemia, improve cellular energy metabolism, downregulate the degree of extracellular acidification, and improve metabolic acidosis. It could also increase the level of mitochondrial aerobic energy metabolism during brain cell reperfusion, reduce anaerobic glycolysis, and inhibit apoptosis and the expression of apoptosis-related proteins. The above results indicated that compound 1 is involved in the regulation of glucose metabolism, can control cell apoptosis, and has protective and potential therapeutic effects on cerebral ischemia-reperfusion injury, which provides a new reference and possibility for the development of novel drugs for the treatment of ischemic brain injury.

Keywords: apoptosis; brain-type glycogen phosphorylase inhibitor; glycolysis; mouse astrocytes; oxidative phosphorylation

DOI: https://doi.org/10.3390/molecules27196333

J Agric Food Chem. 2022 Oct 10.

Modulation of Flexible Loops in Catalytic Cavities Reveals the Thermal Activation Mechanism of a Glycogen-Debranching Enzyme.

Yixiong Tian, Xiaofeng Ban, Caiming Li, Zhengbiao Gu, Zhaofeng Li.

Some thermophilic enzymes not only exhibit high thermostability at high temperatures but also have an activation effect by thermal incubation. However, the correlations between temperature-induced structural modulation and thermal activation are still unclear. In this study, we selected a thermophilic glycogen-debranching enzyme from Saccharolobus solfataricus STB09 (SsGDE), which was a promising starch-debranching enzyme with a thermal activation property at temperatures ranging from 50 to 70 °C, to explore the thermal activation mechanism. Molecular dynamics simulations were performed for SsGDE at 30, 50, or 70 °C to reveal the temperature dependence of structure modulation and catalytic function. The results revealed that four loops (loop1 313-337, loop2 399-418, loop3 481-513, and loop4 540-574) in SsGDE were reshaped, which made the catalytic cavity more open. The internal residues, including the catalytic triad Asp3631, Glu399, and Asp471, could be exposed, due to the structural modulation, to exert catalytic functions. We proposed that the thermal activation effect of SsGDE was closely associated with the temperature-induced modulation of the catalytic cavity, which paved the way for further engineering enzymes to achieve higher catalytic performance and stability.

Keywords: glycogen-debranching enzyme; molecular dynamics simulations; structure modulation; thermal activation; thermophilic enzyme

DOI: https://doi.org/10.1021/acs.jafc.2c04487

Stem Cell Res. 2022 Oct 03. pii: S1873-5061(22)00283-5. [Epub ahead of print]64 102934

Generation of two heterozygous GAA mutation-carrying human induced pluripotent stem cell lines (XACHi005-A, XACHi006-A) from parents of an infant with Pompe disease.

Wenjun Huang, Yafei Zhou, Jie Wang, Congshan Jiang, Yanmin Zhang, Rui Zhou.

Pompe disease results from GAA mutations that leads to lysosomal glycogen accumulation and cardiac and skeletal muscle pathology. We have previously generated an infantile-onset Pompe disease patient-derived human-induced pluripotent stem cells (iPSCs) line carrying compound GAA mutations (R608X and E888X). Using his parents' peripheral blood mononuclear cells (PBMCs), we here generated two iPSCs lines which carry mutations of R608X E888X respectively. Both lines show typical cell morphology, high expressed pluripotent and self-renewal markers, normal karyotype, and trilineage differentiation potential. These two lines are valuable re-sources for studying the pathological mechanisms of GAA mutation-caused Pompe disease.

DOI: https://doi.org/10.1016/j.scr.2022.102934