Conformational ensembles of non-peptide ω-conotoxin mimetics and Ca+2 ion binding to human voltage-gated N-type calcium channel Cav2.2

Mechanistic insights into the role of calcium in the allosteric regulation of the calmodulin-regulated death-associated protein kinase

Calcium (Ca²⁺) signaling plays an important role in the regulation of many cellular functions. Ca²⁺-binding protein calmodulin (CaM) serves as a primary effector of calcium function. Ca²⁺/CaM binds to the death-associated protein kinase 1 (DAPK1) to regulate intracellular signaling pathways. However, the mechanism underlying the influence of Ca²⁺ on the conformational dynamics of the DAPK1-CaM interactions is still unclear. Here, we performed large-scale molecular dynamics (MD) simulations of the DAPK1-CaM complex in the Ca²⁺-bound and-unbound states to reveal the importance of Ca²⁺. MD simulations revealed that removal of Ca²⁺ increased the anti-correlated inter-domain motions between DAPK1 and CaM, which weakened the DAPK1-CaM interactions. Binding free energy calculations validated the decreased DAPK1-CaM interactions in the Ca²⁺-unbound state. Structural analysis further revealed that Ca²⁺ removal caused the significant conformational changes at the DAPK1-CaM interface, especially the helices α1, α2, α4, α6, and α7 from the CaM and the basic loop and the phosphate-binding loop from the DAPK1. These results may be useful to understand the biological role of Ca²⁺ in physiological processes.

Benzimidazole Derivatives as New Potential NLRP3 Inflammasome Inhibitors That Provide Neuroprotection in a Rodent Model of Neurodegeneration and Memory Impairment

Objective

The study investigated the effect of newly synthesized benzimidazole derivatives against ethanol-induced neurodegeneration. According to evidence, ethanol consumption may cause a severe insult to the central nervous system (CNS), resulting in mental retardation, neuronal degeneration, and oxidative stress. Targeting neuroinflammation and oxidative stress may be a useful strategy for preventing ethanol-induced neurodegeneration.

Methodology

Firstly, the newly synthesized compounds were subjected to molecular simulation and docking in order to predict ligand binding status. Later, for in vivo observations, adult male Sprague Dawley rats were used for studying behavioral and oxidative stress markers. ELIZA kits were used to analyse tumour necrosis factor-alpha (TNF-), nuclear factor-B (NF-B), interleukin (IL-18), and pyrin domain-containing protein 3 (NLRP3) expression, while Western blotting was used to measure IL-1 and Caspase-1 expression.

Results

Our findings suggested that altered levels of antioxidant enzymes were associated with elevated levels of TNF-α, NF-B, IL-1, IL-18, Caspase-1, and NLRP3 in the ethanol-treated group. Furthermore, ethanol also caused memory impairment in rats, as measured by behavioural tests. Pretreatment using selected benzimidazole significantly increased the combat of the brain against ethanol-induced oxidative stress. The neuroprotective effects of benzimidazole derivatives were promoted by their free radical scavenging activity, augmentation of endogenous antioxidant proteins (GST, GSH), and amelioration of lipid peroxide (LPO) and other pro-inflammatory mediators. Molecular docking and molecular simulation studies further supported our hypothesis that the synthetic compounds Ca and Cb had an excellent binding affinity with proper bond formation with their targets (TNF-α and NLRP3).

Conclusion

It is revealed that these benzimidazole derivatives can reduce ethanol-induced neuronal toxicity by regulating the expression of cytokines, antioxidant enzymes, and the inflammatory cascade.

Carveol a Naturally-Derived Potent and Emerging Nrf2 Activator Protects Against Acetaminophen-Induced Hepatotoxicity

Acetaminophen (N-acetyl p-aminophenol or APAP) is used worldwide for its antipyretic and anti-inflammatory potential. However, APAP overdose sometimes causes severe liver damage. In this study, we elucidated the protective effects of carveol in liver injury, using molecular and in silico approaches. Male BALB/c mice were divided into two experimental cohorts, to identify the best dose and to further assess the role of carveol in the nuclear factor E2-related factor; nuclear factor erythroid 2; p45-related factor 2 (Nrf2) pathway. The results demonstrated that carveol significantly modulated the detrimental effects of APAP by boosting endogenous antioxidant mechanisms, such as nuclear translocation of Nrf2 gene, a master regulator of the downstream antioxidant machinery. Furthermore, an inhibitor of Nrf2, called all-trans retinoic acid (ATRA), was used, which exaggerated APAP toxicity, in addition to abrogating the protective effects of carveol; this effect was accompanied by overexpression of inflammatory mediators and liver = 2ltoxicity biomarkers. To further support our notion, we performed virtual docking of carveol with Nrf2-keap1 target, and the resultant drug-protein interactions validated the in vivo findings. Together, our findings suggest that carveol could activate the endogenous master antioxidant Nrf2, which further regulates the expression of downstream antioxidants, eventually ameliorating the APAP-induced inflammation and oxidative stress.