BackgroundThe first pathology observed in Parkinson’s disease (PD) is ‘dying back’ of striatal dopaminergic (DA) terminals. Connexin (Cx)30, an astrocytic gap junction protein, is upregulated in the striatum in PD, but its roles in neurodegeneration remain elusive. We investigated Cx30 function in an acute PD model by administering 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to wild-type (WT) and Cx30 knockout (KO) mice.MethodsOn days 1 and 7 after MPTP administration, we evaluated changes in astrocytic Cx30, Cx43, glial fibrillary acidic protein, and ionised calcium-binding adapter molecule 1 expression by immunostaining and biochemical analysis. Loss of DA neurons was evaluated by tyrosine hydroxylase immunostaining. Gene expression was analysed using A1, A2, pan-reactive astrocyte microarray gene sets, and M1, M2, and M1/M2 mixed microglial microarray gene sets. Real-time PCR and in situ hybridisation were performed to evaluate glial cell-derived neurotrophic factor (Gdnf) and S100a10 expression. Striatal GDNF protein levels were determined by enzyme-linked immunosorbent assay.ResultsMPTP treatment induced upregulation of Cx30 and Cx43 levels in the striatum of WT and KO mice. DA neuron loss was accelerated in Cx30 KO compared with WT mice after MPTP administration, despite no change in the striatal concentration of methyl-4-phenylpyridinium+. Astrogliosis in the striatum of Cx30 KO mice was attenuated by MPTP, whereas microglial activation was unaffected. Microarrays of the striatum showed reduced expression of pan-reactive and A2 astrocyte genes after MPTP treatment in Cx30 KO compared with WT mice, while M1, M2, and M1/M2 mixed microglial gene expression did not change. MPTP reduced the number of striatal astrocytes co-expressing Gdnf mRNA and S100β protein or S100a10 mRNA and S100β protein and also reduced the level of GDNF in the striatum of Cx30 KO compared with WT mice.ConclusionsThese findings indicate that Cx30 plays critical roles in astrocyte neuroprotection in an MPTP PD model.Electronic supplementary materialThe online version of this article (10.1186/s12974-018-1251-0) contains supplementary material, which is available to authorized users.

The thiol/disulfide redox network mediated by the thioredoxin (Trx) system in chloroplasts ensures light-responsive control of diverse crucial functions. Despite the suggested importance of this system, the working dynamics against changing light environments remains largely unknown. Thus, we directly assessed the in vivo redox behavior of chloroplast Trx-targeted thiol enzymes in Arabidopsis thaliana. In a time-course analysis throughout a day period that was artificially mimicked to natural light conditions, thiol enzymes showed a light-dependent shift in redox state, but the patterns were distinct among thiol enzymes. Notably, the ATP synthase CF(1-γ) subunit was rapidly reduced even under low-light conditions, whereas the stromal thiol enzymes fructose 1,6-bisphosphatase, sedoheptulose 1,7-bisphosphatase, and NADP-malate dehydrogenase were gradually reduced/re-oxidized along with the increase/decrease in light intensity. Photo-reduction of thiol enzymes was suppressed by the impairment of photosynthetic linear electron transport using DCMU and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone, but sensitivity to the impairment was uneven between CF(1-γ) and other stromal thiol enzymes. These different dependencies of photo-reduction on electron transport, rather than the redox state of Trx and the circadian clock, could readily explain the distinct diurnal redox behaviors of thiol enzymes. In addition, our results indicate that the cyclic electron transport around PSI is also involved in redox regulation of some thiol enzymes. Based on these findings, we propose an in vivo working model of the redox regulation system in chloroplasts.

Lipids and their metabolites are easily oxidized in chain reactions initiated by lipid radicals, forming lipid peroxidation products that include the electrophiles 4-hydroxynonenal and malondialdehyde. These markers can bind cellular macromolecules, causing inflammation, apoptosis and other damage. Methods to detect and neutralize the initiating radicals would provide insights into disease mechanisms and new therapeutic approaches. We describe the first high-sensitivity, specific fluorescence probe for lipid radicals, 2,2,6-trimethyl-4-(4-nitrobenzo[1,2,5]oxadiazol-7-ylamino)-6-pentylpiperidine-1-oxyl (NBD-Pen). NBD-Pen directly detected lipid radicals in living cells by turn-on fluorescence. In a rat model of hepatic carcinoma induced by diethylnitrosamine (DEN), NBD-Pen detected lipid radical generation within 1 h of DEN administration. The lipid radical scavenging moiety of NBD-Pen decreased inflammation, apoptosis and oxidative stress markers at 24 h after DEN, and liver tumor development at 12 weeks. Thus, we have developed a novel fluorescence probe that provides imaging information about lipid radical generation and potential therapeutic benefits in vivo.

Layered double hydroxides (LDHs) are promising compounds in a wide range of fields. However, exchange of CO 3 2− anions with other anions is necessary, because the CO 3 2− anions are strongly affixed in the LDH interlayer space. To elucidate the reason for the extremely high stability of CO 3 2− anions intercalated in LDHs, we investigated in detail the chemical states of CO 3 2− anions and hydrated water molecules in the LDH interlayer space by synchrotron radiation X-ray diffraction, solid-state NMR spectroscopy, and Raman spectroscopy. We found the rigidity of the network structure formed between the CO 3 2− anions, hydrated water molecules, and the hydroxyl groups on the metal hydroxide layer surface to be a crucial factor underlying the stability of CO 3 2− anions in the LDH interlayer space.

Polarized ethylenes having both electron‐donating (an amino or a methylthio group) and electron‐accepting (cyano, carbamoyl, methyl ester) groups on the adjacent two olefinic carbon atoms were prepared by the condensation of S‐alkylthioamidinium salts or methyl dithiocarboxylates with the corresponding active methylene compounds in good yields. These polarized ethylenes were alternatively synthesized by the reaction of thioamides or methyl dithiocarboxylates with tetracyanoethylene oxide in good yields. Reactions of these polarized ethylenes with hydrazine or guanidine derivatives occurred smoothly to give the corresponding pyrazole and pyrimidine derivatives in good yields. The synthesis of 5‐aza[2.2.3]cyclazine derivatives using polarized ethylenes is also described.

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Although oxidized phosphatidylcholines (oxPCs) play critical roles in numerous pathological events, the type and production sites of endogenous oxPCs remain unknown because of the lack of structural information and dedicated analytical methods. Herein, a library of 465 oxPCs is constructed using high-resolution mass spectrometry-based non-targeted analytical methods and employed to detect 70 oxPCs in mice with acetaminophen-induced acute liver failure. We show that doubly oxygenated polyunsaturated fatty acid (PUFA)-PCs (PC PUFA;O2), containing epoxy and hydroxide groups, are generated in the early phase of liver injury. Hybridization with in-vivo 18O labeling and matrix-assisted laser desorption/ionization-tandem MS imaging reveals that PC PUFA;O2 are accumulated in cytochrome P450 2E1-expressing and glutathione-depleted hepatocytes, which are the major sites of liver injury. The developed library and visualization methodology should facilitate the characterization of specific lipid peroxidation events and enhance our understanding of their physiological and pathological significance in lipid peroxidation-related diseases.

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