PYGL-mediated glucose metabolism reprogramming promotes EMT phenotype and metastasis of pancreatic cancer.

Epithelial-mesenchymal transition (EMT) is closely associated with tumor invasion and metastasis. However, key regulators of EMT in pancreatic ductal adenocarcinoma (PDAC) need to be further studied. Bioinformatics analyses of pancreatic cancer public datasets showed that glycogen phosphorylase L (PYGL) expression is elevated in quasimesenchymal PDAC (QM-PDAC) and positively associated with EMT. In vitro cellular experiments further confirm PYGL as a crucial EMT regulator in PDAC cells. Functionally, PYGL overexpression promotes cell migration and invasion in vitro and facilitates liver metastasis in vivo, while PYGL knockdown has opposite effects. Mechanically, hypoxia induces PYGL expression in a hypoxia inducible factor 1α (HIF1α)-dependent manner and promotes glycogen accumulation. Elevated PYGL mobilizes accumulated glycogen to fuel glycolysis via its activity as a glycogen phosphorylase, thus inducing the EMT process, which could be suppressed by the glycolysis inhibitor 2-deoxy-D-glucose (2-DG). Clinically, PYGL expression is upregulated in PDAC and correlates with its malignant features and poor prognosis. Collectively, the data from our study reveal that the hypoxia/PYGL/glycolysis-induced EMT promotes PDAC metastasis, which establishes the rational for targeting hypoxia/PYGL/glycolysis/EMT signaling pathway against PDAC.

miR-155-5p regulates hypoxia-induced pulmonary artery smooth muscle cell function by targeting PYGL.

Pulmonary arterial hypertension (PAH) is a cardiovascular disease that has high incidence and causes massive deaths. miR-155-5p/PYGL pathway was revealed to play a crucial role in PAH by weighted gene co-expression network analysis (WGCNA). The potential mechanism of miR-155-5p in regulating hypoxia-induced pulmonary artery smooth muscle cell (PASMC) function was analyzed through in vitro experiments. Hypoxia treatment stimulated the proliferation of PASMCs and increased the expression of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1α (HIF-1α). At the same time, revealed by qRT-PCR and western blot, the level of miR-155-5p was raised, and the level of PYGL was decreased in hypoxia-induced PASMCs. Through CCK-8 assay, transwell assay and flow cytometry, it was revealed that miR-155-5p inhibitor remarkably inhibited the cell proliferation and migration and decreased the proportion of hypoxia-stimulated PASMCs in S and G2/M phases. Dual-luciferase reporter system was subsequently applied to validate the straight regulation of miR-155-5p on PYGL based on the analysis of online database. Furthermore, siPYGL was revealed to reverse the influence of miR-155-5p inhibitor on hypoxia-induced PASMCs. These outcomes indicate that the increased level of miR-155-5p in hypoxia-stimulated PASMCs could enhance the cell proliferation, cell migration, and cell cycle progression by targeting PYGL directly. This study may supply novel treatment strategies for PAH.Abbreviations: PH, pulmonary hypertension; PAH, pulmonary arterial hypertension; WGCNA, weighted gene co-expression network analysis; PASMCs, pulmonary artery smooth muscle cells; VEGF, vascular endothelial growth factor; HIF-1α, hypoxia-inducible factor-1α; SMCs, smooth muscle cells; DEGs, differentially expressed genes; GEO, Gene Expression Omnibus; GO, Gene Ontology; KEGG, Kyoto Encyclopedia of Genes and Genomes; FBS, fetal bovine serum; OD, optical density; BCA, bicinchoninic acid; PVDF, polyvinylidene fluoride; PBS, phosphate-buffered saline; BP, biological process; MF, molecular function; CC, cell component.

Identification of PYGL as a key prognostic gene of glioma by integrated bioinformatics analysis.

Aim: PYGL has been reported to have carcinogenic effects in a variety of tumors. This study is the first to reveal the relationship between PYGL and the prognosis of glioma. Materials & methods: Analyzing the Chinese Glioma Genome Atlas database, the authors revealed the expression status and prognostic value of PYGL in gliomas and used quantitative real-time PCR to verify PYGL expression again. Subsequently, they used Gene Set Enrichment Analysis to explore the biological pathways that PYGL may participate in. The authors also used the tumor immune estimation resource database to explore the relationship between PYGL and tumor immune cells. Results: PYGL is involved in the malignant progression of glioma. Conclusions: PYGL can be used as a new biomarker and molecular target for evaluating the prognosis and immunotherapy of glioma.

Long noncoding RNA KCNMB2-AS1 promotes the development of esophageal cancer by modulating the miR-3194-3p/PYGL axis.

Esophageal cancer (ESCA), as a common cancer worldwide, is a main cause of cancer-related mortality. Comprehensive studies on molecular mechanism of ESCA have been carried out. Though numerous long noncoding RNAs (lncRNAs) was reported to participate in the occurrence and development of ESCA, the potential role of lncRNA potassium calcium-activated channel subfamily M regulatory beta subunit 2 (KCNMB2) antisense RNA 1 (KCNMB2-AS1) in ESCA remains to be discovered. This study intends to investigate the detailed function and molecular mechanism of KCNMB2-AS1 in ESCA. Gene expression was evaluated by reverse transcription quantitative polymerase chain reaction (RT-qPCR). Cell proliferation was examined by Cell Counting Kit-8 (CCK-8) assay and colony formation assay. Cell invasion and migration were measured by wound healing assay and Transwell assay. Luciferase reporter assay was adopted to validate the interaction between KCNMB2-AS1 and miR-3194-3p. Western blotting was performed to assess protein levels. We discovered that KCNMB2-AS1 was significantly upregulated in ESCA. KCNMB2-AS1 downregulation suppressed the growth, invasion, migration and stemness of ESCA cells. KCNMB2-AS1 bound with miR-3194-3p, and glycogen phosphorylase L (PYGL) was a direct target of miR-3194-3p. KCNMB2-AS1 upregulated PYGL expression by directly binding with miR-3194-3p. Additionally, PYGL overexpression abolished the inhibitory influence of KCNMB2-AS1 depletion on ESCA cell behaviors. Collectively, lncRNA KCNMB2-AS1 promotes ESCA development through targeting the miR-3194-3p/ PYGL axis, which might provide theoretical basis to explore novel biomarkers for ESCA treatment.

The vitamin B6-regulated enzymes PYGL and G6PD fuel NADPH oxidases to promote skin inflammation.

Psoriasis is a skin inflammatory disorder that affects 3% of the human population. Although several therapies based on the neutralization of proinflammatory cytokines have been used with relative success, additional treatments are required. The in silico analysis of gene expression data of psoriasis lesional skin and an analysis of vitamin B6 metabolites in the sera of psoriasis patients point to altered vitamin B6 metabolism at both local and systemic levels. Functional studies showed that vitamin B6 vitamers reduced skin neutrophil infiltration, oxidative stress and Nfkb activity in two zebrafish models of skin inflammation. Strikingly, inhibition of glycogen phosphorylase L (Pygl) and glucose-6-phosphate dehydrogenase (G6pd), two vitamin B6-regulated enzymes, alleviated oxidative-stress induced inflammation in zebrafish skin inflammation models. Despite the central role of G6pd in antioxidant defenses, the results of the study demonstrate that glycogen stores and G6pd fuel NADPH oxidase to promote skin inflammation, revealing novel targets for the treatment of skin inflammatory disorders.

The architecture of hydrogen and sulfur σ-hole interactions explain differences in the inhibitory potency of C-ß-d-glucopyranosyl thiazoles, imidazoles and an N-ß-d glucopyranosyl tetrazole for human liver glycogen phosphorylase and offer new insights to structure-based design.

C-Glucopyranosyl imidazoles, thiazoles, and an N-glucopyranosyl tetrazole were assessed in vitro and ex vivo for their inhibitory efficiency against isoforms of glycogen phosphorylase (GP; a validated pharmacological target for the development of anti-hyperglycaemic agents). Imidazoles proved to be more potent inhibitors than the corresponding thiazoles or the tetrazole. The most potent derivative has a 2-naphthyl substituent, a Ki value of 3.2 µM for hepatic glycogen phosphorylase, displaying also 60% inhibition of GP activity in HepG2 cells, compared to control vehicle treated cells, at 100 µM. X-Ray crystallography studies of the protein - inhibitor complexes revealed the importance of the architecture of inhibitor associated hydrogen bonds or sulfur σ-hole bond interactions to Asn284 OD1, offering new insights to structure-based design efforts. Moreover, while the 2-glucopyranosyl-tetrazole seems to bind differently from the corresponding 1,2,3-triazole compound, the two inhibitors are equipotent.

1,2-Dichloroethane impairs glucose and lipid homeostasis in the livers of NIH Swiss mice.

Excessive exposure to 1,2-Dichloroethane (1,2-DCE), a chlorinated organic toxicant, can lead to liver dysfunction. To fully explore the mechanism of 1,2-DCE-induced hepatic abnormalities, 30 male National Institutes of Health (NIH) Swiss mice were exposed to 0, 350, or 700mg/m3 of 1,2-DCE, via inhalation, 6h/day for 28days. Increased liver/body weight ratios, as well as serum AST and serum ALT activity were observed in the 350 and 700mg/m3 1,2-DCE exposure group mice, compared with the control group mice. In addition, decreased body weights were observed in mice exposed to 700mg/m3 1,2-DCE, compared with control mice. Exposure to 350 and 700mg/m3 1,2-DCE also led to significant accumulation of hepatic glycogen, free fatty acids (FFA) and triglycerides, elevation of blood triglyceride and FFA levels, and decreases in blood glucose levels. Results from microarray analysis indicated that the decreases in glucose-6-phosphatase catalytic subunit (G6PC) and liver glycogen phosphorylase (PYGL) expression, mediated by the activation of AKT serine/threonine kinase 1 (Akt1), might be responsible for the hepatic glycogen accumulation and steatosis. Further in vitro study demonstrated that 2-chloroacetic acid (1,2-DCE metabolite), rather than 1,2-DCE, up-regulated Akt1 phosphorylation and suppressed G6PC and PYGL expression, resulting in hepatocellular glycogen accumulation. These results suggest that hepatic glucose and lipid homeostasis are impaired by 1,2-DCE exposure via down-regulation of PYGL and G6PC expression, which may be primarily mediated by the 2-chloroacetic acid-activated Akt1 pathway.

Expression profile based gene clusters for ischemic stroke detection.

In microarray studies alterations in gene expression in circulating leukocytes have shown utility for ischemic stroke diagnosis. We studied forty candidate markers identified in three gene expression profiles to (1) quantitate individual transcript expression, (2) identify transcript clusters and (3) assess the clinical diagnostic utility of the clusters identified for ischemic stroke detection. Using high throughput next generation qPCR 16 of the 40 transcripts were significantly up-regulated in stroke patients relative to control subjects (p<0.05). Six clusters of between 5 and 7 transcripts were identified that discriminated between stroke and control (p values between 1.01e-9 and 0.03). A 7 transcript cluster containing PLBD1, PYGL, BST1, DUSP1, FOS, VCAN and FCGR1A showed high accuracy for stroke classification (AUC=0.854). These results validate and improve upon the diagnostic value of transcripts identified in microarray studies for ischemic stroke. The clusters identified show promise for acute ischemic stroke detection.

Molecular recognition of the protein phosphatase 1 glycogen targeting subunit by glycogen phosphorylase.

Disrupting the interaction between glycogen phosphorylase and the glycogen targeting subunit (G(L)) of protein phosphatase 1 is emerging as a novel target for the treatment of type 2 diabetes. To elucidate the molecular basis of binding, we have determined the crystal structure of liver phosphorylase bound to a G(L)-derived peptide. The structure reveals the C terminus of G(L) binding in a hydrophobically collapsed conformation to the allosteric regulator-binding site at the phosphorylase dimer interface. G(L) mimics interactions that are otherwise employed by the activator AMP. Functional studies show that G(L) binds tighter than AMP and confirm that the C-terminal Tyr-Tyr motif is the major determinant for G(L) binding potency. Our study validates the G(L)-phosphorylase interface as a novel target for small molecule interaction.

Glutathione-dependent reduction of arsenate by glycogen phosphorylase responsiveness to endogenous and xenobiotic inhibitors.

Rabbit muscle glycogen phosphorylase-a (GPa) reduces arsenate (As(V)) to the more toxic arsenite (As(III)) in a glutathione (GSH)-dependent fashion. To determine whether reduction of As(V) by GPa is countered by compounds known to inhibit GP-catalyzed glycogenolysis, the effects of thiol reagents, endogenous compounds (glucose, ATP, ADP) as well as nonspecific glycogen phosphorylase inhibitors (GPIs; caffeine, quercetin, flavopiridol [FP]), and specific GPIs (1,4-dideoxy-1,4-imino-D-arabinitol [DAB], BAY U6751, CP320626) were tested on reduction of As(V) by rabbit muscle GPa in the presence of glycogen (substrate), AMP (activator), and GSH, and the As(III) formed from As(V) was quantified by high-performance liquid chromatography-hydride generation-atomic fluorescence spectrometry. The As(V)-reducing activity of GPa was moderately sensitive to thiol reagents. Glucose above 5mM and ADP or ATP at physiological levels diminished GPa-catalyzed As(V) reduction. All GPIs inhibited As(V) reduction by GPa in a concentration-dependent fashion; however, their effects were differentially affected by glucose (10mM) or AMP (200microM instead of 25microM), known modulators of the action of some GPIs on the GP-catalyzed glycogenolysis. Inhibition of As(V) reduction by DAB and quercetin was not influenced by glucose or AMP. Glucose that potentiates the inhibitory effects of caffeine, BAY U6751, and CP320626 on the glycogenolytic activity of GPa also enhanced the inhibitory effects of these GPIs on GPa-catalyzed As(V) reduction. AMP at high concentration alleviated the inhibition by BAY U6751 and CP320626 (whose antagonistic effect on GP-catalyzed glycogen breakdown is also AMP sensitive), whereas the inhibition in As(V) reduction by FP or caffeine was little affected by AMP. Thus, GPIs inhibit both the glycogenolytic and As(V)-reducing activities of GP, supporting that the latter is coupled to glycogenolysis. It was also shown that a GPa-rich extract of rat liver contained GSH-dependent As(V)-reducing activity that was inhibited by specific GPIs, suggesting that the liver-type GPa can also catalyze reduction of As(V).

Crystallographic studies on acyl ureas, a new class of glycogen phosphorylase inhibitors, as potential antidiabetic drugs.

Acyl ureas were discovered as a novel class of inhibitors for glycogen phosphorylase, a molecular target to control hyperglycemia in type 2 diabetics. This series is exemplified by 6-{2,6-Dichloro- 4-[3-(2-chloro-benzoyl)-ureido]-phenoxy}-hexanoic acid, which inhibits human liver glycogen phosphorylase a with an IC(50) of 2.0 microM. Here we analyze four crystal structures of acyl urea derivatives in complex with rabbit muscle glycogen phosphorylase b to elucidate the mechanism of inhibition of these inhibitors. The structures were determined and refined to 2.26 Angstroms resolution and demonstrate that the inhibitors bind at the allosteric activator site, where the physiological activator AMP binds. Acyl ureas induce conformational changes in the vicinity of the allosteric site. Our findings suggest that acyl ureas inhibit glycogen phosphorylase by direct inhibition of AMP binding and by indirect inhibition of substrate binding through stabilization of the T' state.

Modeling aided design of potent glycogen phosphorylase inhibitors.

Molecular modeling has been used to assist in the development of a novel series of potent glycogen phosphorylase inhibitors based on a phenyl diacid lead, compound 1. In the absence of suitable competitive binding assays, compound 1 was predicted to bind at the AMP allosteric site based on superposition onto known inhibitors which bind at different sites in the enzyme and analyses of the surrounding protein environment associated with these distinct sites. Possible docking modes of compound 1 at the AMP allosteric site were further explored using the crystal structure of rabbit muscle glycogen phosphorylase complexed with a Bayer diacid compound W1807 (PDB entry 3AMV). Compound 1 was predicted to interact with positively charged arginines at the AMP allosteric site in the docking model. Characterization of the binding pocket by a grid-based surface calculation of the docking model revealed a large unfilled hydrophobic region near the central phenyl ring, suggesting that compounds with larger hydrophobic groups in this region would improve binding. A series of naphthyl diacid compounds were designed and synthesized to access this hydrophobic cleft, and showed significantly improved potency.