Inhibition of striatal-enriched protein tyrosine phosphatase by targeting computationally revealed cryptic pockets.

Cryptic pockets, which are not apparent in crystallographic structures, provide promising alternatives to traditional binding sites for drug development. However, identifying cryptic pockets is extremely challenging and the therapeutic potential of cryptic pockets remains unclear. Here, we reported the discovery of novel inhibitors for striatal-enriched protein tyrosine phosphatase (STEP), a potential drug target for multiple neuropsychiatric disorders, based on cryptic pocket detection. By combining the use of molecular dynamics simulations and fragment-centric topographical mapping, we identified transiently open cryptic pockets and identified 12 new STEP inhibition scaffolds through structure-based virtual screening. Site-directed mutagenesis verified the binding of ST3 with the predicted cryptic pockets. Moreover, the most potent and selective inhibitors could modulate the phosphorylation of both ERK1/2 and Pyk2 in PC12 cells.

Arctigenin Attenuates Ischemia/Reperfusion Induced Ventricular Arrhythmias by Decreasing Oxidative Stress in Rats.

BACKGROUND/AIMS: Arctigenin (ATG) has been shown to possess anti-inflammatory, immunemodulatory, anti-viral, anti-microbial, anti-carcinogenic, vasodilatory and anti-platelet aggregation properties. However, the protective role of ATG in prevention of arrhythmias induced by myocardial ischemia/reperfusion is unknown. The aim of this study was to investigate the anti-arrhythmia effect of ATG in an ischemia/reperfusion injured rat heart model and explore the related mechanisms. METHODS: Rats were randomly exposed to sham operation, myocardial ischemia/ reperfusion (MI/R) alone, ATG+ MI/R, pretreated with ATG in low (12.5 mg/kg/day), medium (50 mg/kg/day) and high dose (200 mg/kg/day), respectively. Ventricular arrhythmias were assessed. The activity of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and the level of malondialdehyde (MDA) in myocardial tissue were determined by chemical analysis. RESULTS: Compared to MI/R, rats pretreated with ATG in doses of 50 mg/kg/day and 200 mg/kg/day showed significantly reduced incidence and duration of ventricular fibrillation, ventricular tachycardia and ventricular ectopic beat (VEB), and decreased the arrhythmia score during the 30-min ischemia. Incidence and duration of ventricular tachycardia, infarction size and arrhythmia scores in these groups were significantly decreased during the 120-min reperfusion. No ventricular fibrillation occurred during the period of reperfusion. Rats pretreated with ATG in doses of 50 mg/kg/day and 200 mg/kg/ day markedly enhanced the activities of antioxidant enzymes SOD and GSH-Px, reduced the level of MDA. No differences were observed between the group pretreated with a low dose of ATG and the sham group. Administration of ATG significantly increased the expression of antioxidant stress protein Nrf2, Trx1 and Nox1. CONCLUSION: Our data suggested that ATG plays anti-arrhythmia role in ischemia/reperfusion injury, which is probably associated with attenuating oxidative stress by Nrf2 signaling pathway.

Protein Flexibility in Docking-Based Virtual Screening: Discovery of Novel Lymphoid-Specific Tyrosine Phosphatase Inhibitors Using Multiple Crystal Structures.

Incorporating protein flexibility is a major challenge for docking-based virtual screening. With an increasing number of available crystal structures, ensemble docking with multiple protein structures is an efficient approach to deal with protein flexibility. Herein, we report the successful application of a docking-based virtual screen using multiple crystal structures to discover novel inhibitors of lymphoid-specific tyrosine phosphatase (LYP), a potential drug target for autoimmune diseases. The appropriate use of multiple protein structures allowed a better enrichment than a single structure in the recovery of known inhibitors. Subsequently, an optimal ensemble of LYP structures was selected and used in docking-based virtual screening. Eight novel LYP inhibitors (IC50 ranging from 7.95 to 56.6 µM) were identified among 23 hit compounds. Further studies demonstrated that the most active compound B15 possessed some selectivity over other protein phosphatases and could effectively up-regulate TCR (T cell receptor)-mediated signaling in Jurkat T cells. These novel hits not only provided good starting points for the development of therapeutic agents useful in autoimmune diseases but also demonstrated the advantages of choosing an appropriate ensemble of protein structures in docking-based virtual screening over using a single protein conformation.

FFA4 receptor (GPR120): A hot target for the development of anti-diabetic therapies.

Free Fatty Acid 4 receptor (FFA4 receptor or GPR120), a rhodopsin-like G protein coupled receptor (GPCR) subfamily member, is a receptor that senses specific fatty acids such as ω-3 fatty acid in fish oil or the endogenous signaling lipid, PHASA. FFA4 receptor is enriched in lung, colon and adipose tissue but is also detected in many other tissues and cells. The activation of FFA4 receptor has multiple effects, including but not limited to inhibition of inflammation, improving insulin sensitivity and adipogenesis, and regulating hormone secretion from the gastro-intestinal system and pancreatic islets. The important role of FFA4 receptor in maintaining metabolic homeostasis strongly indicates the great potential of selective FFA4 receptor agonizts to treat diabetes and inflammation. In this review, we summarize recent research progress in the physiological and biochemical studies of FFA4 receptor and highlight its underlying signaling mechanisms and ligand identification to assist future research to exploit FFA4 receptor as a drug target.

Fast identification of novel lymphoid tyrosine phosphatase inhibitors using target-ligand interaction-based virtual screening.

Lymphoid-specific tyrosine phosphatase (Lyp), a critical signaling regulator of immune cells, is associated with various autoimmune diseases, including type 1 diabetes, rheumatoid arthritis, and systemic lupus erythematosus. Recent research suggests that Lyp is a potential drug target for autoimmune diseases. Herein, we applied a target-ligand interaction-based virtual screening method to identify novel Lyp inhibitors. Nine Lyp inhibitors with novel scaffolds were identified with eight reversible inhibitors (Ki values ranged from 2.87 to 28.03 µM) and one covalent inhibitor (Ki = 40.98 ± 13.19 µM). The top four compounds (A2, A15, A19, and A26) displayed selectivity over other phosphatases in preliminary experiments, and kinetic analysis indicated that these compounds are competitive inhibitors of Lyp. Compounds A15 and A19 up-regulated TCR (T cell receptor) mediated signaling and transcriptional activation through inhibition of Lyp activity in T cells. The new chemotypes of Lyp selective inhibitors identified through the target-ligand interaction-based virtual screening may provide new leads for Lyp targeted therapeutic development.

The effect of mud therapy on pain relief in patients with knee osteoarthritis: a meta-analysis of randomized controlled trials.

OBJECTIVES: A meta-analysis was conducted to examine the effect of mud therapy on pain relief in patients with knee osteoarthritis (OA). METHODS: A detailed search of PubMed®/MEDLINE® was undertaken to identify randomized controlled trials and prospective comparative studies published before 9 March 2013 that compared mud therapy with control group treatments in patients with knee OA. RESULTS: A quantitative meta-analysis of seven studies (410 patients) was performed. There was a significant difference between the groups in the visual analogue scale pain score (standardized mean difference [SMD] -0.73) and Western Ontario and McMaster Universities Osteoarthritis Index pain score (SMD -0.30), with differences in favour of mud therapy. CONCLUSIONS: Mud therapy is a favourable option for pain relief in patients with knee OA. Additional high-quality randomized controlled trials need to be conducted to explore this issue further and to confirm this conclusion.

Effect of epimedium pubescen flavonoid on bone mineral status and bone turnover in male rats chronically exposed to cigarette smoke.

BACKGROUND: Epimedii herba is one of the most frequently used herbs in formulas that are prescribed for the treatment of osteoporosis in China and its main constituent is Epimedium pubescen flavonoid (EPF). However, it is unclear whether EPF during chronic exposure to cigarette smoke may have a protective influence on the skeleton. The present study investigated the effect of EPF on bone mineral status and bone turnover in a rat model of human relatively high exposure to cigarette smoke. METHODS: Fifty male Wistar rats were randomized into five groups: controls, passive smoking groups and passive smoking rats administered EPF at three dosage levels (75, 150 or 300 mg/kg/day) in drinking water for 4 months. A rat model of passive smoking was prepared by breeding male rats in a cigarette-smoking box. Bone mineral content (BMC), bone mineral density (BMD), bone turnover markers, bone histomorphometric parameters and biomechanical properties were examined. RESULTS: Smoke exposure decreased BMC and BMD, increased bone turnover (inhibited bone formation and stimulated its resorption), affected bone histomorphometry (increased trabecular separation and osteoclast surface per bone surface; decreased trabecular bone volume, trabecular thickness, trabecular number, cortical thickness, bone formation rate and osteoblast surface per bone surface), and reduced mechanical properties. EPF supplementation during cigarette smoke exposure prevented smoke-induced changes in bone mineral status and bone turnover. CONCLUSION: The results suggest that EPF can prevent the adverse effects of smoke exposure on bone by stimulating bone formation and inhibiting bone turnover and bone resorption.