DS6: anticandidal,antibiofilm peptide against Candida tropicalis and exhibit synergy with commercial drug

Antifungal peptides have gained interest as therapeutic agents in recent years because of increased multidrug resistance against present antifungal drugs. This study designed, synthesized and characterized antifungal activity of a small peptide analogue, DS6. This peptide was designed using the template from the N‐terminal part of the antifungal protein, Aspergillus giganteous. DS6 inhibited Candida tropicalis (ATCC 13803), as well as its clinical isolates. DS6 was found to be a fungicidal, killing the fungus very rapidly. DS6 is also non‐toxic to human cells. Synergistic interactions of DS6 with amphotericin B and fluconazole were also evident. DS6 is membrane lytic and exhibits antibiofilm activity against C. tropicalis. In conclusion, DS6 may have utility as an alternative antifungal therapy for C. tropicalis. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.     

Epidermal Growth Factor Receptor activation promotes ADA3 acetylation through the AKT-p300 pathway

The ADA3 (Alteration/Deficiency in Activation 3) protein is an essential adaptor component of several Lysine Acetyltransferase (KAT) complexes involved in chromatin modifications. Previously, we and others have demonstrated a crucial role of ADA3 in cell cycle progression and in maintenance of genomic stability. Recently, we have shown that acetylation of ADA3 is key to its role in cell cycle progression. Here, we demonstrate that AKT activation downstream of Epidermal Growth Factor Receptor (EGFR) family proteins stimulation leads to phosphorylation of p300, which in turn promotes the acetylation of ADA3. Inhibition of upstream receptor tyrosine kinases (RTKs), HER1 (EGFR)/HER2 by lapatinib and the accompanying reduction of phospho-AKT levels led to a decrease in p300 phosphorylation and ADA3 protein levels. The p300/PCAF inhibitor garcinol also destabilized the ADA3 protein in a proteasome-dependent manner and an ADA3 mutant with K→R mutations exhibited a marked increase in half-life, consistent with opposite role of acetylation and ubiquitination of ADA3 on shared lysine residues. ADA3 knockdown led to cell cycle inhibitory effects, as well as apoptosis similar to those induced by lapatinib treatment of HER2+ breast cancer cells, as seen by accumulation of CDK inhibitor p27, reduction in mitotic marker pH3(S10), and a decrease in the S-phase marker PCNA, as well as the appearance of cleaved PARP. Taken together our results reveal a novel RTK-AKT-p300-ADA3 signaling pathway involved in growth factor-induced cell cycle progression.     

A novel autophagy modulator 6-Bio ameliorates SNCA/α-synuclein toxicity

Parkinson disease (PD) is a life-threatening neurodegenerative movement disorder with unmet therapeutic intervention. We have identified a small molecule autophagy modulator, 6-Bio that shows clearance of toxic SNCA/α-synuclein (a protein implicated in synucleopathies) aggregates in yeast and mammalian cell lines. 6-Bio induces autophagy and dramatically enhances autolysosome formation resulting in SNCA degradation. Importantly, neuroprotective function of 6-Bio as envisaged by immunohistology and behavior analyses in a preclinical model of PD where it induces autophagy in dopaminergic (DAergic) neurons of mice midbrain to clear toxic protein aggregates suggesting that it could be a potential therapeutic candidate for protein conformational disorders.     

Comparative molecular docking and simulation analysis of molnupiravir and remdesivir with SARS-CoV-2 RNA dependent RNA polymerase (RdRp)

Treatment of SARS-CoV-2 targeting its RNA dependent RNA polymerase (RdRp) is of current interest. Remdesivir has been approved for the treatment of COVID-19 around the world. However, the drug has been linked with pharmacological limitations like adverse effects and reduced efficiency. Nevertheless, recent advancements have depicted molnupiravir as an effective therapeutic agent to target the SARS-CoV-2 RdRp. The drug has cleared both in vitro and in vivo screening. It is in phase-III clinical trial. Nonetheless, there are no data on themolecular binding interaction of molnupiravir with RdRp. Therefore, it is of interest to report the binding interaction of molnupiravir using molecular docking. It is also of interest to show its stability during interaction using molecular dynamics and binding free energy calculations along with drug likeliness and pharmacokinetic properties in comparison with remdesivir.     

Development of cell death-based method for the selectivity screening of caspase-1 inhibitors

Caspase-1 selective inhibitors are novel therapeutic agents for inflammatory diseases. Selectivity assays for caspases can be initiated with purified enzyme, making these assays very costly and time consuming. Therefore, there is a need to develop a fast and reliable cell-based assay, which can be used for the selectivity screening of multiple caspases in a biologically relevant context in a single assay. In this study, we have developed an assay in which DNA fragmentation, a hallmark of apoptosis, of Jurkat cell line was examined post induction with etoposide in the presence or absence of inhibitors of caspases 1, 3, 8, 9 and pan-caspase inhibitors. We observed that caspases-3, -8, -9 and pan caspase inhibitors resulted in significant inhibition of etoposide-induced DNA fragmentation. However, caspase-1 specific inhibitor failed to prevent DNA fragmentation, suggesting that either caspases belonging to caspase-1 family (1, 4 and 5) are not present in the Jurkat cells or might not be involved in the etoposide-induced DNA fragmentation. Since the inhibition of caspases 3, 8 and 9 is accompanied by the down regulation of the activity of a cascade of caspases (caspases 2, 6, 7, 9 and 10), selectivity of caspase-I inhibitors can be ascertained for the above panel (caspases 2, 6, 7, 8, 9 and 10) of caspases from this single assay.     

Lesions of the Lateral Habenula Increase Voluntary Ethanol Consumption and Operant Self-Administration,Block Yohimbine-Induced Reinstatement of Ethanol Seeking,and Attenuate Ethanol-Induced Conditioned Taste Aversion

The lateral habenula (LHb) plays an important role in learning driven by negative outcomes. Many drugs of abuse, including ethanol, have dose-dependent aversive effects that act to limit intake of the drug. However, the role of the LHb in regulating ethanol intake is unknown. In the present study, we compared voluntary ethanol consumption and self-administration, yohimbine-induced reinstatement of ethanol seeking, and ethanol-induced conditioned taste aversion in rats with sham or LHb lesions. In rats given home cage access to 20% ethanol in an intermittent access two bottle choice paradigm, lesioned animals escalated their voluntary ethanol consumption more rapidly than sham-lesioned control animals and maintained higher stable rates of voluntary ethanol intake. Similarly, lesioned animals exhibited higher rates of responding for ethanol in operant self-administration sessions. In addition, LHb lesion blocked yohimbine-induced reinstatement of ethanol seeking after extinction. Finally, LHb lesion significantly attenuated an ethanol-induced conditioned taste aversion. Our results demonstrate an important role for the LHb in multiple facets of ethanol-directed behavior, and further suggest that the LHb may contribute to ethanol-directed behaviors by mediating learning driven by the aversive effects of the drug.     

Computational investigation of binding mechanism of substituted pyrazinones targeting corticotropin releasing factor-1 receptor deliberated for anti-depressant drug design

In spite of various research investigations towards anti-depressant drug discovery program, no one drug has not yet launched last 20 years. Corticotropin-releasing factor-1 (CRF-1) is one of the most validated targets for the development of antagonists against depression, anxiety and post-traumatic stress disorders. Various research studies suggest that pyrazinone based CRF-1 receptor antagonists were found to be highly potent and efficacious. In this research investigation, we identified the pharmacophore and binding pattern through 2D and 3D-QSAR and molecular docking respectively. Molecular dynamics studies were also performed to explore the binding pattern recognition. We establish the relationship between activity and pharmacophoric features to design new potent compounds. The best 2D-QSAR model was generated through multiple linear regression method with r² value of 0.97 and q² value of 0.89. Also 3D-QSAR model was obtained through k-nearest neighbor molecular field analysis method with q² value of 0.52 and q²_se value of 0.36. Molecular docking and binding energy were also evaluated to define binding patterns and pharmacophoric groups, including (i) hydrogen bond with residue Asp284, Glu305 and (ii) π–π stacking with residue Trp9. Compound 11i has the highest binding affinity compared to reference compounds, so this compound could be a potent drug for stress related disorders. Most of the compounds, including reference compounds were found within acceptable range of physicochemical parameters. These observations could be provided the leads for the design and optimization of novel CRF-1 receptor antagonists.

Communicated by Ramaswamy H. Sarma