Production of phosphatidylinositol 5‐phosphate via PIKfyve and MTMR3 regulates cell migration

Although phosphatidylinositol 5‐phosphate (PtdIns5P) is present in many cell types and its biogenesis is increased by diverse stimuli, its precise cellular function remains elusive. Here we show that PtdIns5P levels increase when cells are stimulated to move and we find PtdIns5P to promote cell migration in tissue culture and in a Drosophila in vivo model. First, class III phosphatidylinositol 3‐kinase, which produces PtdIns3P, was shown to be involved in migration of fibroblasts. In a cell migration screen for proteins containing PtdIns3P‐binding motifs, we identified the phosphoinositide 5‐kinase PIKfyve and the phosphoinositide 3‐phosphatase MTMR3, which together constitute a phosphoinositide loop that produces PtdIns5P via PtdIns(3,5)P₂. The ability of PtdIns5P to stimulate cell migration was demonstrated directly with exogenous PtdIns5P and a PtdIns5P‐producing bacterial enzyme. Thus, the identified phosphoinositide loop defines a new role for PtdIns5P in cell migration.     

Structure of the Atg12–Atg5 conjugate reveals a platform for stimulating Atg8–PE conjugation

Atg12 is conjugated to Atg5 through enzymatic reactions similar to ubiquitination. The Atg12–Atg5 conjugate functions as an E3‐like enzyme to promote lipidation of Atg8, whereas lipidated Atg8 has essential roles in both autophagosome formation and selective cargo recognition during autophagy. However, the molecular role of Atg12 modification in these processes has remained elusive. Here, we report the crystal structure of the Atg12–Atg5 conjugate. In addition to the isopeptide linkage, Atg12 forms hydrophobic and hydrophilic interactions with Atg5, thereby fixing its position on Atg5. Structural comparison with unmodified Atg5 and mutational analyses showed that Atg12 modification neither induces a conformational change in Atg5 nor creates a functionally important architecture. Rather, Atg12 functions as a binding module for Atg3, the E2 enzyme for Atg8, thus endowing Atg5 with the ability to interact with Atg3 to facilitate Atg8 lipidation.     

Prediction of HIV-1 protease inhibitory activity of 4-hydroxy-5,6-dihydropyran-2-ones: QSAR study

Inhibition of human immunodeficiency virus 1 (HIV-1) protease is an important strategy for the treatment of HIV and acquired immune deficiency syndrome (AIDS). Therefore, HIV-1 protease inhibitory activity of dihydropyranone derivatives has been analyzed with different physico-chemical parameters. In the present work, QSAR studies were performed on a series of 4-hydroxy-5,6-dihydropyran-2-ones to explore the physico-chemical parameters responsible for their HIV-1 protease inhibitory activity. Physico-chemical parameters were calculated using WIN CAChe 6.1. Stepwise multiple linear regression analysis was performed to derive QSAR models which were further evaluated for statistical significance and predictive power by internal and external validation. The selected best QSAR model was having correlation coefficient (R)?=?0.875 and cross-validated squared correlation coefficient (Q²)?=?0.707. The developed significant QSAR model indicates that hydrophobicity of whole molecule and the substituent present at sixth position of dihydropyranones play an important role in the HIV-1 protease inhibitory activities of 4-hydroxy-5,6-dihydropyran-2-ones.     

Review ArticleNaphthalene Combretastatin Analogues: Synthesis,Cytotoxicity and Antitubulin Activity

Synthesis and evaluation of new combretastatin analogues with varied modifications on the bridge and the aromatic rings, have shown that the 2-naphthyl moiety is a good surrogate for the 3-hydroxy-4-methoxyphenyl (B-ring) of combretastatin A-4. Other bicyclic systems, such as 6(7)-quinolyl and 5-indolyl, can replace the B-ring, but they produce less potent analogues in the cytotoxicity and tubulin polymerization inhibition assays. Other modifications are detrimentral for the potency of the studied analogues. The 2-naphthyl combretastatin 53 and the related 6-quinolyl combretastatin 106 analogues are the most potent among the derivatives of this type, whereas 92 and 95 are the most potent among the naphthalene derivatives with a heterocycle in the bridge. Previous and new results in this family of combretastatin analogues are discussed.     

Anti-cancer and anti-hepatitis C virus NS5B polymerase activity of etodolac 1,2,4-triazoles

Abstract

Arachidonic acid is an unsaturated fatty acid liberated from phospholipids of cell membranes. NSAIDs are known as targets of cyclooxygenase enzyme (COX-1, COX-2 and COX-3) in arachidonic acid metabolism. This mechanism of COX-2 in carcinogenesis causes cancer. In addition, COX-2 plays a role in the early stages of hepatocarcinogenesis. Hepatitis C virus (HCV) infection is cause of liver cirrhosis and hepatocellular carcinoma (HCC). The aim of our study was to improve effective agents against HCV. A novel series of new etodolac 1,2,4-triazoles derivatives (4a–h) have been synthesized and investigated for their activity against HCV NS5B polymerase. Compound 4a was found to be the most active with IC₅₀ value of 14.8?µM. In accordance with these results, compound 4a was screened for anti-cancer activity on liver cancer cell lines (Huh7, Mahlavu, HepG2, FOCUS). Compound 4a showed anti-cancer activity against Huh7 human hepatoma cell line with IC₅₀ value of 4.29?µM. Therefore, compound 4a could be considered as a new anti-cancer and anti-HCV lead compound.     

Knockout of 5‐lipoxygenase prevents dexamethasone‐induced tau pathology in 3xTg mice

Emerging evidence suggests that dysregulation stress hormones, such as glucocorticoids, in aged persons put them at a higher risk to develop Alzheimer's disease (AD). However, the mechanisms underlying such vulnerability remain to be unraveled. Pharmacologic inhibition of 5‐lipoxygenase (5LO), an active player in AD pathogenesis whose protein level increases with aging in the human, has been shown to blunt glucocorticoid‐mediated amyloid β (Ab) formation in vitro. In this article, we investigated the role of this pathway in modulating the development of the corticosteroid‐dependent AD‐like phenotype in the triple transgenic mice (3xTg). Dexamethasone was administered for 1 week to 3xTg or 3xTg genetically deficient for 5LO (3xTg/5LO^?/?) mice, and its effect on memory, amyloid‐β and tau levels, and metabolism assessed. At the end of the treatment, we observed that dexamethasone did not induce changes in behavior. Compared with controls, treated mice did not show significant alterations in brain soluble Aβ levels. While total tau protein levels were unmodified in all groups, we found that dexamethasone significantly increased tau phosphorylation at S396, as recognized by the antibody PHF‐13, which was specifically associated with an increase in the GSK3β activity. Additionally, dexamethasone‐treated mice had a significant increase in the tau insoluble fraction and reduction in the postsynaptic protein PDS‐95. By contrast, these modifications were blunted in the 3xTg/5LO^?/? mice. Our findings highlight the functional role that 5LO plays in stress‐induced AD tau pathology and support the hypothesis that pharmacologic inhibition of this enzyme could be a useful tool for individuals with this risk factor.     

A convenient ‘one-pot’ synthesis and in vitro microbiological evaluation of novel 2,7-diaryl-[1,4]-diazepan-5-ones

A convenient method for the ‘one-pot’ synthesis of novel target molecule 2,7-diaryl-[1,4]-diazepan-5-ones from the respective 2,6-diaryl-piperidin-4-ones was catalyzed by NaHSO₄.Al₂O₃ heterogeneous catalyst in dry media under microwave irradiation in solvent-free conditions. Moreover, the catalyst could be recovered and re-used up to 4 times after washing with ethyl acetate. They were evaluated for potential antibacterial activity against Staphylococcus aureus, β-Haemolytic streptococcus, Vibreo cholerae, Salmonella typhii, Escherichia coli, Klebsiella pneumonia, Pseudomonas and antifungal activity against Aspergillus flavus, Aspergillus fumigatus, Mucor, Candida albicans and Rhizopus. Structure-Activity Relationship (SAR) led to the conclusion that, of all the compounds 25–32 tested, compound 30 exerted strong in vitro antibacterial activity against S. aureus, S. typhii, and Pseudomonas and all the compounds 25–32 were less active against E. coli, whereas all the compounds 25–32 displayed potent in vitro antifungal activity against all the fungal strains used, except compound 30, which was more effectual against Mucor.     

Anti-leukemia Activity of 7-hydroxy-2-substituted-methyl-5 H -oxazolo[3,2- a] pyrimidin-5-one Derivatives

The synthesis of new 7-hydroxy-2-substituted-methyl-5 H -oxazolo[3,2- a] pyrimidin-5-ones derivatives, designed as structural bicyclic analogues of the iron chelator deferiprone, is described. They were tested for their ability to inhibit proliferation in human Bcr-Abl + leukemia cells.     

Potential Inhibitors of Angiogenesis. Part II: 3-(Azolylmethylene)-2,3-dihydrobenzo[b]furan-2-ones

The synthesis and pharmacological evaluation of new 3-(imidazol-4(5)-ylmethylene)-2,3-dihydrobenzo[b]furan-2-ones 8-10 and 3-(3,5-dimethylpyrrol-2-ylmethylene)-2,3-dihydrobenzo[b]furan-2-one 11, analogues of SU-5416, as potential inhibitors of angiogenesis, are reported. Compounds 8 and 11 were prepared by a Knoevenagel reaction starting from 2-hydroxyphenylacetic acid 2 and 4-formylimidazole 5 or 2-formyl-3,5-dimethylpyrrole 7, followed by acid-catalysed cyclodehydration. For compounds 9 and 10, an alternative method was used; it consisted in carrying out the Knoevenagel reaction with the 2,3-dihydrobenzo[b]furan-2-ones 3 and 4. The antiangiogenic activity of these compounds was evaluated in the three-dimensional in vitro rat aortic rings test at 1 μM. At this concentration, compound 11 induced a decrease of angiogenesis comparable to that observed with SU-5416; the vascular density index at 1 μM of 11 and SU-5416 were 30±10 and 22±4% of control, respectively.     

Monoamine Oxidase Activities in Catfish (Parasilurus Asotus) Tissues

Abstract

The substrate- and inhibitor-related characteristics of monoamine oxidase (MAO) were studied for catfish brain and liver. The kinetic constants for MAO in both tissues were determined using 5-hydroxytryptamine (5-HT), tyramine and β-phenylethylamine (PEA) as substrates. For both tissues, the V_max values were highest with 5-HT and lowest with PEA. The K_m value for the brain was highest with 5-HT, followed by tyramine and PEA; but for the liver its value was highest with PEA, followed by 5-HT and tyramine, although all values were in the same order of magnitude. The inhibition of MAO by clorgyline and deprenyl by use of 5-HT, tyramine and PEA as substrates showed that the MAO-A inhibitor clorgyline was more effective than the MAO-B inhibitor deprenyl for both catfish tissues; a single form was present since inhibition by clorgyline or deprenyl with 1000 μM PEA showed single phase sigmoid curves. It is concluded that catfish brain and liver contain a single form of MAO, relatively similar to mammalian MAO-A.