Search

Ischemic accumulation of succinate causes cerebral damage by excess production of reactive oxygen species. However, it is unknown whether ischemic accumulation of succinate affects neural stem cell proliferation. In this study, we established a rat model of cerebral ischemia/reperfusion injury by occlusion of the middle cerebral artery. We found that succinate levels increased in serum and brain tissue (cortex and hippocampus) after ischemia/reperfusion injury. Oxygen-glucose deprivation and reoxygenation stimulated primary neural stem cells to produce abundant succinate. Succinate can be converted into diethyl succinate in cells. Exogenous diethyl succinate inhibited the proliferation of mouse-derived C17.2 neural stem cells and increased the infarct volume in the rat model of cerebral ischemia/reperfusion injury. Exogenous diethyl succinate also increased the succinylation of the Rho family GTPase Cdc42 but repressed Cdc42 GTPase activity in C17.2 cells. Increasing Cdc42 succinylation by knockdown of the desuccinylase Sirt5 also inhibited Cdc42 GTPase activity in C17.2 cells. Our findings suggest that ischemic accumulation of succinate decreases Cdc42 GTPase activity by induction of Cdc42 succinylation, which inhibits the proliferation of neural stem cells and aggravates cerebral ischemia/reperfusion injury.

Complement pathway over-activation has been implicated in a variety of neurological diseases. However, the signaling pathways governing astrocytic complement activation in Parkinson's disease (PD) are poorly understood. Kir6.1, a pore-forming subunit of ATP-sensitive potassium (K-ATP) channel, is prominently expressed in astrocytes and exhibits anti-inflammatory effects. Therefore, we hypothesize that Kir6.1/K-ATP channel may regulate astrocytic complement activation in the pathogenesis of PD. In this study, astrocytic Kir6.1 knockout (KO) mice were used to examine the effect of astrocytic Kir6.1/K-ATP channel on astrocytic complement activation triggered by the lipopolysaccharide (LPS). Here, we found that astrocytic Kir6.1 KO mice showed more dopaminergic neuron loss and more astrocyte reactivity in substantia nigra compacta than controls. We also found that astrocytic Kir6.1 KO increased the expression of complement C3 in astrocytes in LPS-induced mouse model of PD. Mechanistically, astrocytic Kir6.1 KO promoted astroglial NF-κB activation to elicit extracellular release of C3, which in turn interacted with neuronal C3aR to induce neuron death. Blocking complement function by NF-κB inhibitor or C3aR antagonist rescued the aggravated neuron death induced by Kir6.1 KO. Collectively, our findings reveal that astrocytic Kir6.1/K-ATP channel prevents neurodegeneration in PD via astrocyte-neuron cross talk through NF-κB/C3/C3aR signaling and suggest that targeting astroglial Kir6.1/K-ATP channel-NF-κB-C3-neuronal C3aR signaling represents a novel therapeutic strategy for PD.

ATP-sensitive potassium (K-ATP) channels, coupling cell metabolism to cell membrane potential, are involved in brain diseases, including Parkinson's disease (PD). Kir6.1, a pore-forming subunit of K-ATP channel, is prominently expressed in astrocytes and participates in regulating its function. However, the precise role of astrocytic Kir6.1-contaning K-ATP channel (Kir6.1/K-ATP) in PD is not well characterized. In this study, astrocytic Kir6.1 knockout (KO) mice were used to examine the effect of astrocytic Kir6.1/K-ATP channel on dopaminergic (DA) neurodegeneration triggered by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. Here, we found that astrocytic Kir6.1 KO mice showed more DA neuron loss in substantia nigra compacta (SNc), lower level of dopamine in the striatum, and more severe motor dysfunction than controls. Interestingly, this companied by increased neuroinflammation and decreased autophagy level in SNc in vivo and astrocytes in vitro. Mechanistically, astrocytic Kir6.1 KO inhibited mitophagy which resulted in an increase in the accumulation of damaged mitochondria, production of reactive oxygen species and neuroinflammation in astrocytes. Restoration of astrocytic mitophagy rescued the deleterious effects of astrocytic Kir6.1 ablation on mitochondrial dysfunction, inflammation and DA neuron death. Collectively, our findings reveal that astrocytic Kir6.1/K-ATP channel protects against DA neurodegeneration in PD via promoting mitophagy and suggest that astrocytic Kir6.1/K-ATP channel may be a promising therapeutic target for PD.

Astrocytes are involved in the neuroinflammation of neurodegenerative diseases, such as Parkinson’s disease (PD). Among the numerous inflammatory cytokines, interleukin-1β (IL-1β) produced by astrocytic Nod-like receptor protein (NLRP) inflammasome is crucial in the pathogenesis of PD. β-arrestin2-mediated dopamine D2 receptor (Drd2) signal transduction has been regarded as a potential anti-inflammatory target. Our previous study revealed that astrocytic Drd2 suppresses neuroinflammation in the central nervous system. However, the role of Drd2 in astrocytic NLRP3 inflammasome activation and subsequent IL-1β production remains unclear. In the present study, we used 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced PD mouse model to investigate whether Drd2 could suppress astrocytic NLRP3 inflammasome activation. We showed that Drd2 agonist inhibited NLRP3 inflammasome activation, evidenced by decreased caspase-1 expression and reduced IL-1β release in the midbrain of wild type mice. The anti-inflammasome effect of Drd2 was abolished in β-arrestin2 knockout and β-arrestin2 small interfering RNA-injected mice, suggesting a critical role of β-arrestin2 in Drd2-regulated NLRP3 inflammasome activation. We also found that Drd2 agonists suppressed the upregulation of caspase-1 and IL-1β expression in primary cultured mouse astrocytes in response to the activation of NLRP3 inflammasome induced by lipopolysaccharide plus adenosine triphosphate. Furthermore, we demonstrated that β-arrestin2 mediated the inhibitory effect of Drd2 on NLRP3 inflammasome activation via interacting with NLRP3 and interfering the inflammasome assembly. Collectively, our study illustrates that astrocytic Drd2 inhibits NLRP3 inflammasome activation through a β-arrestin2-dependent mechanism, and provides a new strategy for treatment of PD.

Classical activation (M1 phenotype) and alternative activation (M2 phenotype) are the two polars of microglial activation states that can produce either neurotoxic or neuroprotective effects in the immune pathogenesis of Parkinson’s disease (PD). Exploiting the beneficial properties of microglia cells by modulating their polarization states provides great potential for the treatment of PD. However, the mechanism that regulates microglia polarization remains elusive. Here we demonstrated that Kir6.1-containing ATP-sensitive potassium (Kir6.1/K-ATP) channel switched microglia from the detrimental M1 phenotype toward the beneficial M2 phenotype. Kir6.1 knockdown inhibited M2 polarization and simultaneously exaggerated M1 microglial inflammatory responses, while Kir6.1 overexpression promoted M2 polarization and synchronously alleviated the toxic phase of M1 microglia polarization. Furthermore, we observed that the Kir6.1 deficiency dramatically exacerbated dopaminergic neuron death companied by microglia activation in mouse model of PD. Mechanistically, Kir6.1 deficiency enhanced the activation of p38 MAPK–NF-κB pathway and increased the ratio of M1/M2 markers in the substantia nigra compacta of mouse model of PD. Suppression of p38 MAPK in vivo partially rescued the deleterious effects of Kir6.1 ablation on microglia phenotype and dopaminergic neuron death. Collectively, our findings reveal that Kir6.1/K-ATP channel modulates microglia phenotypes transition via inhibition of p38 MAPK–NF-κB signaling pathway and Kir6.1/K-ATP channel may be a promising therapeutic target for PD.

Diethylhexyl phthalate (DEHP) is a kind of plasticizers which is generally used in plastics packaging materials to provide the flexibility. Especially in PVC films, a large amount of DEHP used makes it possibility of the widespread usage of PVC in the fresh food packaging market. But recent researches proved that DEHP can be easily migration into food and food stimulant. It causes reproductive disorders, mutation, carcinogenicity, and other genetic toxicity to all mammals. Hence blocking the migration of DEHP from the plastic to the foods becomes very important issue for the food safety. In this work, the migration kinetics of DEHP was explored. We achieved that the migration of DEHP can be well controlled through coated nano-scale SiOxbarrier layer on the surface of PVC films, and the plasma enhanced chemical vapor deposition (PECVD) process is a very efficient way to prepare SiOxcoatings on the plastic surface. It is also noticed that there is a relationship between the migration-resistance properties and coating structure through Fourier transform infrared spectroscopy (FTIR) for the chemical composition analysis, scanning electron microscope (SEM) for the topography investigation of the coating surfaces, surface profilemeter for the thickness measurement of coatings, and high-performance liquid chromatography (HPLC) for the barrier property evaluation of coatings at last. We conclude that the coatings can perfectly block the migration of the DEHP from plastics to their contents. When the deposition conditions of SiOxcoatings were optimized, i.e. 50W of the discharge power, 4:1 of ratio of O2: HMDSO, and ca.100 nm thickness of SiOx, the 71.2% DEHP, compared to the control PVC film, was effectively barriered.

To construct a novel baculovirus expression system of Spodoptera litura multicapsid nucleopolyhedrovirus, the 5' end and 3' end-flanking fragments of ph gene were amplified from the genome DNA of SpltMNPV, Japan-C3 strain using two pairs of primers synthesized according to SpltMNPV China-G2 strain genome DNA sequence published in GenBank. To obtain the transfer vector pSplt-gfp, the fragment of gfp gene was inserted into this vector between two fragments tandem linked into pUC18. The spli cells were cotransfected with pSplt-gfp and the wild SpltMNPV genome DNA. The recombinant virus containing gfp was selected with the limited dilution method. The fluorescence can be observed in the spli cells and the 3rd instar larvae after 24 and 48 hours by infection of the recombinant virus, respectively. The result showed that the recombinant virus was obtained successfully. It will be helpful to establish Spodoptera litura multicapsid nucleopolyhedrovirus expression system and more effective pesticide for Spodoptera litura.