Modeling of mutant superoxide dismutase 1 octamers with cross-linked disulfide bonds.

Mutant superoxide dismutase 1 (SOD1) may form cyclic structures due to its greater instability from aberrant demetallization and oxidation of cysteine bonds. This cyclic structure may allow SOD1 to form ion channels on membranes such as the mitochondrial membrane, causing imbalances in the concentration of intracellular ions as a potential mechanism for the progressive neuron death involved in amyotrophic lateral sclerosis (ALS). Using docking programs within modeling software, models of mutant SOD1 dimers and eventually ring oligomers were constructed based on known descriptions of such structures in addition to information on the orientation of the models associated with a membrane. The resulting structure consists of a ring of four demetallated mutant SOD1 dimers with cross-linked disulfide bonds. Stability of the octamer model was supported by the molecular dynamics simulations. Further analysis of the octamer model indicated that its inner- and outer-pore diameters were stable, matching the dimensions of known SOD1 ion channels.

Potential COVID-19 papain-like protease PLpro inhibitors: repurposing FDA-approved drugs.

Using the crystal structure of SARS-CoV-2 papain-like protease (PLpro) as a template, we developed a pharmacophore model of functional centers of the PLpro inhibitor-binding pocket. With this model, we conducted data mining of the conformational database of FDA-approved drugs. This search identified 147 compounds that can be potential inhibitors of SARS-CoV-2 PLpro. The conformations of these compounds underwent 3D fingerprint similarity clusterization, followed by docking of possible conformers to the binding pocket of PLpro. Docking of random compounds to the binding pocket of protease was also done for comparison. Free energies of the docking interaction for the selected compounds were lower than for random compounds. The drug list obtained includes inhibitors of HIV, hepatitis C, and cytomegalovirus (CMV), as well as a set of drugs that have demonstrated some activity in MERS, SARS-CoV, and SARS-CoV-2 therapy. We recommend testing of the selected compounds for treatment of COVID-19.

Gastrodin Inhibits Inflammasome Through the STAT3 Signal Pathways in TNA2 Astrocytes and Reactive Astrocytes in Experimentally Induced Cerebral Ischemia in Rats.

This study was aimed to determine Gastrodin (GAS) and its underlying signaling pathway involved in suppression of inflammasome specifically in reactive astrocytes that are featured prominently in different neurological conditions or diseases including cerebral ischemia. For this purpose, TNA2 astrocytes in cultures were exposed to oxygen-glucose-deprivation (OGD) mimicking hypoxic cerebral ischemia. Separately, TNA2 cells were pretreated with GAS prior to OGD exposure. Additionally, Stattic, an inhibitor of STAT3 signaling pathway, was used to ascertain its involvement in regulating inflammasome in astrocytes exposed to OGD. In parallel to the above, adult rats subjected to middle cerebral artery occlusion (MCAO) with or without GAS pretreatment were sacrificed at different time points to determine the effects of GAS on astrocyte inflammasome. TNA2 astrocytes in different treatments as well as reactive astrocytes in MCAO were processed for immunofluorescence labeling and Western blot analysis for various protein markers. In the latter, protein expression levels of p-STAT3, NLRP3, and NLRC4 were markedly increased in TNA2 astrocytes exposed to OGD. Remarkably, the expression levels of these biomarkers were significantly suppressed by GAS. Of note, GAS especially at dose 20 µM inhibited NLRP3 and NLRC4 expression levels most substantially. Moreover, GAS inhibited the downstream proteins caspase-1 and IL-18. Concomitantly, GAS significantly suppressed the expression of STAT3 and NF-κB signaling pathway. It is noteworthy that Stattic at dose 100 µM inhibited STAT3 pathway and NF-κB activation in TNA2 astrocytes, an effect that was shared by GAS. In MCAO, GAS was found to effectively attenuate p-STAT3 immunofluorescence intensity in reactive astrocytes. Arising from the above, it is concluded that GAS is anti-inflammatory as it effectively suppresses inflammasome in OGD-stimulated astrocytes as well as in reactive astrocytes in MCAO via STAT3 and NF-κB signaling expression coupled with decreased expression of caspase-1 and IL-18.

Gastrodin pretreatment alleviates rat brain injury caused by cerebral ischemic-reperfusion.

Brain damage, including blood-brain barrier (BBB) dysfunction, neurological behavior deficit, cerebral infarction and inflammation, is commonly caused by ischemic-reperfusion (I/R) injury. Prevention of the above biological process defects is considered beneficial for patient recovery after I/R injury. This study was aimed to assess the neuroprotective effect of Gastrodin (GAS), an herbal agent, in experimentally induced cerebral ischemia. Sprague-Dawley adult rats were randomly divided into six groups: Sham-operated control group (Sham), middle cerebral artery occlusion (MCAO) group, GAS (50, 100, and 200 mg/kg) pretreatment + MCAO groups (GAS) and Nimodipine (NIM) + MCAO, namely, the NIM group. Additionally, an OGD/R model using BV-2 microglia was established in vitro to simulate I/R injury. We showed here that the neurological scores of rats in the GAS groups were significantly improved compared with the MCAO group. Moreover, the area of cerebral infarction in the GAS pretreatment groups and the NIM group was significantly reduced. Furthermore, Evans blue leakage volume was significantly reduced with GAS pretreatment notably at dose 100 mg/kg. Expression of matrix metalloproteinase 2 (MMP2) and MMP9 in GAS groups was markedly decreased when compared with MCAO group. In BV-2 microglia exposed to OGD/R given GAS pretreatment, MMP2 and MMP9 positive cells were reduced in numbers. The present results have shown that GAS pretreatment significantly compensated for neurological behavior defects in rats with I/R-induced injury, reduced brain infarction size, reversed BBB impairment, and attenuated inflammation. It is suggested that pretreatment with GAS before surgery is beneficial during recovery from I/R injury.