MITOL-mediated DRP1 ubiquitylation and degradation promotes mitochondrial hyperfusion in a CMT2A-linked MFN2 mutant.

Mutations in mitofusin 2 (MFN2) that are associated with the pathology of the debilitating neuropathy Charcot-Marie-Tooth type 2A (CMT2A) are known to alter mitochondrial morphology. One such abundant MFN2 mutation, R364W, results in the generation of elongated, interconnected mitochondria. However, the mechanism leading to this mitochondrial aberration remains poorly understood. Here, we show that mitochondrial hyperfusion in the presence of R364W-MFN2 is due to increased degradation of DRP1 (also known as DNM1L). The E3 ubiquitin ligase MITOL (also known as MARCHF5) is known to ubiquitylate both MFN2 and DRP1. Interaction with and subsequent ubiquitylation by MITOL is stronger in the presence of wild-type MFN2 than with R364W-MFN2. This differential interaction of MITOL with MFN2 in the presence of R364W-MFN2 renders the ligase more available for DRP1 ubiquitylation. Multi-monoubiquitylation and proteasomal degradation of DRP1 in R364W-MFN2 cells in the presence of MITOL eventually leads to mitochondrial hyperfusion. Here, we provide a mechanistic insight into mitochondrial hyperfusion, while also reporting that MFN2 can indirectly modulate DRP1 - an effect not shown previously. This article has an associated First Person interview with the first author of the paper.

EIF4A3 targeted therapeutic intervention in glioblastoma multiforme using phytochemicals from Indian medicinal plants - an integration of phytotherapy into precision onco-medicine.

Glioblastoma Multiforme (GBM), an aggressive brain tumor (grade-IV astrocytoma), poses treatment challenges. Poor prognosis results from the rapid growth, highlighting the role of EIF4A3 in regulating non-coding RNAs. EIF4A3 promotes the expression of several non-coding RNAs, viz, Circ matrix metallopeptidase 9 (MMP9), a prominent oncogene, by interacting with the upstream region of the circMMP9 mRNA transcript and acts on cell proliferation, migration, and invasion of GBM. However, research shows that EIF4A3 knockdown inhibits glioblastoma progression and increases apoptosis. In this study, we explored the efficiency of the phytochemicals from plants like Withania somnifera and Castanea sativa with potential anti-glioblastoma effects as obtained from the Indian Medicinal Plants, Phytochemistry and Therapeutics (IMPPAT) database. Consequently, we have performed a virtual screening of the compounds against the protein EIF4A3. We further investigated the efficiency of the shortlisted compounds based on docking scores evaluated using GOLD, AutoDock4.2, LeDock, and binding free energy analyses using Molecular Mechanics Poisson-Boltzmann Surface Area (MMPBSA). Among the phytochemicals studied so far, several Withania-specific compounds from Withania somnifera and a single dietary compound, viz., Thiamine from Castanea sativa, have exhibited comparatively good blood-brain barrier permeability, significant binding affinity towards the EIF4A3, and good ADMET properties. Furthermore, we have verified the interaction stability of the lead molecules with EIF4A3 using MD simulations. Thus, the present study offers an opportunity to develop drug candidates targeting glioblastoma caused by EIF4A3 over-expression, integrating phytotherapy into precision oncology to create tailored and precise natural treatment strategies for cancer.Communicated by Ramaswamy H. Sarma.

CMT2A-linked MFN2 mutation, T206I promotes mitochondrial hyperfusion and predisposes cells towards mitophagy.

Mutations in Mitofusin2 (MFN2) associated with the pathology of the debilitating neuropathy Charcot-Marie-Tooth type 2A (CMT2A) are known to alter mitochondrial morphology. Previously, such mutations have been shown to elicit two diametrically opposite phenotypes - while some mutations have been causally linked to enhanced mitochondrial fragmentation, others have been shown to induce hyperfusion. Our study identifies one such MFN2 mutant, T206I that causes mitochondrial hyperfusion. Cells expressing this MFN2 mutant have elongated and interconnected mitochondria. T206I-MFN2 mutation in the GTPase domain increases MFN2 stability and renders cells susceptible to stress. We show that cells expressing T206I-MFN2 have a higher predisposition towards mitophagy under conditions of serum starvation. We also detect increased DRP1 recruitment onto the outer mitochondrial membrane, though the total DRP1 protein level remains unchanged. Here we have characterized a lesser studied CMT2A-linked MFN2 mutant to show that its presence affects mitochondrial morphology and homeostasis.

MetaDOCK: A Combinatorial Molecular Docking Approach.

Molecular docking plays a major role in academic and industrial drug screening and discovery processes. Despite the availability of numerous docking software packages, there is a lot of scope for improvement for the docking algorithms in terms of becoming more reliable to replicate the experimental binding results. Here, we propose a combinatorial or consensus docking approach where complementary powers of the existing methods are captured. We created a meta-docking protocol by combining the results of AutoDock4.2, LeDock, and rDOCK programs as these are freely available, easy to use, and suitable for large-scale analysis and produced better performance on benchmarking studies. Rigorous benchmarking analyses were undertaken to evaluate the scoring, posing, and screening capability of our approach. Further, the performance measures were compared against one standard state-of-the-art commercial docking software, GOLD, and one freely available software, PLANTS. Performances of MetaDOCK for scoring, posing, and screening the protein-ligand complexes were found to be quite superior compared to the reference programs. Exhaustive molecular dynamics simulation and molecular mechanics Poisson-Boltzmann and surface area-based free energy estimation also suggest better energetic stability of the docking solutions produced by our meta-approach. We believe that the MetaDOCK approach is a useful packaging of the freely available software and provides a better alternative to the scientific community who are unable to afford costly commercial packages.

A Novel spice-antioxidant-based nano-vehicle as a putative green alternative of synthetic AChE inhibitor drugs.

The present treatment for Alzheimer's disease (AD) involves well known synthetic acetylcholine esterase (AChE) inhibitor drugs which besides having short duration of action also have deleterious impact on human health. Therefore, there is a need for natural plant-based biomolecule(s) with potential AChE inhibition activity (ies). The aim of the work is to design a spice-based nano-vehicle as a novel green alternative of synthetic AD drugs by nanoencapsulating a solvent-less supercritical CO2 extract of small cardamom seeds (SCE) having a synergistic consortium of five antioxidant molecules, using polyethylene glycol and emulsifiers, selected based on Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) analyses. Ellman's assay and enzyme inhibition kinetics of the antioxidant molecules as well as the extract and its nanoliposomal formulation (SCE-NL) were performed, followed by rigorous molecular docking and dynamics studies using MM-PBSA and umbrella sampling. The antioxidants exhibited significant AChE inhibition in vitro, individually with 1, 8-cineole having the least IC50 value of 65.53 ± 0.05 µg/mL. . Although SCE-NL had higher IC50 value (575.67 ± 0.5 µg/mL) vis-à-vis that of rivastigmine (67.52 ± 0.02 µg/mL), it is safer for usage being 'green'.The Lineweaver-Burk plots (Vmax ∼1.04 mM/min) revealed competitive mode(s) of inhibition of AChE with each of these antioxidants. Binding energy analyses suggested very good binding free energies and stable docking/binding complexes (between the antioxidants and AChE). This study has delivered a nanoliposomal vehicle of food antioxidants as a putative 'green' alternative of synthetic AChE inhibitor drugs.Communicated by Ramaswamy H. Sarma.

Virtual screening of natural products inspired in-house library to discover potential lead molecules against the SARS-CoV-2 main protease.

SARS-CoV-2, a new coronavirus emerged in 2019, causing a global healthcare epidemic. Although a variety of drug targets have been identified as potential antiviral therapies, and effective candidate against SARS-CoV-2 remains elusive. One of the most promising targets for combating COVID-19 is SARS-CoV-2 Main protease (Mpro, a protein responsible for viral replication. In this work, an in-house curated library was thoroughly evaluated for druggability against Mpro. We identified four ligands (FG, Q5, P5, and PJ4) as potential inhibitors based on docking scores, predicted binding energies (MMGBSA), in silico ADME, and RMSD trajectory analysis. Among the selected ligands, FG, a natural product from Andrographis nallamalayana, exhibited the highest binding energy of -10.31 kcal/mol close to the docking score of clinical candidates Boceprevir and GC376. Other ligands (P5, natural product from cardiospermum halicacabum and two synthetic molecules Q5 and PJ4) have shown comparable docking scores ranging -7.65 kcal/mol to -7.18 kcal/mol. Interestingly, we found all four top ligands had Pi bond interaction with the main amino acid residues HIS41 and CYS145 (catalytic dyad), H-bonding interactions with GLU166, ARG188, and GLN189, and hydrophobic interactions with MET49 and MET165 in the binding site of Mpro. According to the ADME analysis, Q5 and P5 are within the acceptable range of drug likeliness, compared to FG and PJ4. The interaction stability of the lead molecules with viral protease was verified using replicated MD simulations. Thus, the present study opens up the opportunity of developing drug candidates targeting SARS-CoV-2 main protease (Mpro) to mitigate the disease.Communicated by Ramaswamy H. Sarma.

Structural and Drug Screening Analysis of the Non-structural Proteins of Severe Acute Respiratory Syndrome Coronavirus 2 Virus Extracted From Indian Coronavirus Disease 2019 Patients.

The novel coronavirus 2 (nCoV2) outbreaks took place in December 2019 in Wuhan City, Hubei Province, China. It continued to spread worldwide in an unprecedented manner, bringing the whole world to a lockdown and causing severe loss of life and economic stability. The coronavirus disease 2019 (COVID-19) pandemic has also affected India, infecting more than 10 million till 31st December 2020 and resulting in more than a hundred thousand deaths. In the absence of an effective vaccine, it is imperative to understand the phenotypic outcome of the genetic variants and subsequently the mode of action of its proteins with respect to human proteins and other bio-molecules. Availability of a large number of genomic and mutational data extracted from the nCoV2 virus infecting Indian patients in a public repository provided an opportunity to understand and analyze the specific variations of the virus in India and their impact in broader perspectives. Non-structural proteins (NSPs) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) virus play a major role in its survival as well as virulence power. Here, we provide a detailed overview of the SARS-CoV2 NSPs including primary and secondary structural information, mutational frequency of the Indian and Wuhan variants, phylogenetic profiles, three-dimensional (3D) structural perspectives using homology modeling and molecular dynamics analyses for wild-type and selected variants, host-interactome analysis and viral-host protein complexes, and in silico drug screening with known antivirals and other drugs against the SARS-CoV2 NSPs isolated from the variants found within Indian patients across various regions of the country. All this information is categorized in the form of a database named, Database of NSPs of India specific Novel Coronavirus (DbNSP InC), which is freely available at http://www.hpppi.iicb.res.in/covid19/index.php.