PKM2 Nuclear Translocation Promotes Glial Cell Activation and Aggravates the Brain Injury of Intracerebral Hemorrhage.

BACKGROUND: The purpose of this study was to investigate the potential involvement of pyruvate kinase M2 (PKM2), an enzyme acting as a rate-limiting enzyme in the final phase of glycolysis, in the regulation of glial activation and brain damage of intracerebral hemorrhage (ICH). METHODS: Western blotting and immunofluorescence were performed to investigate PKM2 expression, terminal deoxynucleotidyl transferase deoxyurinary triphosphate (dUTP) nick end labeling staining, hematoxylin and eosin staining, and behavioral tests were employed to evaluate the brain damage of ICH mice, and RNA-seq and bioinformatic analyses were performed to detect gene expression changes in ICH mice treated with TEPP-46. RESULTS: Increased PKM2 levels in perihematomal brain tissue were found starting from 3 days following ICH and peaked at 5 and 7 days post ICH. The increased expression of PKM2 was mainly co-localized with glial fibrillary acidic protein (GFAP)+ astrocytes and ionized calcium binding adaptor molecule-1 (IBA-1)+ microglia. Furthermore, we observed a notable increase in the nuclear translocation of PKM2 in glial cells following ICH. TEPP-46 treatment significantly reduced PKM2 nuclear translocation, and effectively attenuated glial activation and brain injury, and improved functional recovery of mice with ICH. RNA-seq data indicated that 91.1% (205/225) of differentially expressed genes (DEGs) were down-regulated in the TEPP-46 treated groups compared with the vehicle-treated groups in ICH brains. Furthermore, bioinformatic analyses revealed that these down-regulated DEGs were involved in a variety of biological processes, including autophagy and metabolic processes. In addition, the majority of these downregulated DEGs had a primary high expression in neurons, with subsequent expression seen in endothelial cells, microglia, and astrocytes. CONCLUSIONS: These results indicate that increased PKM2 nuclear translocation promotes the activation of glial cells after ICH, hence aggravating ICH-induced brain damage, and aggravates the brain injury induced by ICH. This highlights a potential therapeutic target for inhibiting glial activation to attenuate brain injury after ICH.

Deep Succinylproteomics of Brain Tissues from Intracerebral Hemorrhage with Inhibition of Toll-Like Receptor 4 Signaling.

It is unclear how Toll-like receptor (TLR) 4 signaling affects protein succinylation in the brain after intracerebral hemorrhage (ICH). Here, we constructed a mouse ICH model to investigate the changes in ICH-associated brain protein succinylation, following a treatment with a TLR4 antagonist, TAK242, using a high-resolution mass spectrometry-based, quantitative succinyllysine proteomics approach. We characterized the prevalence of approximately 6700 succinylation events and quantified approximately 3500 sites, highlighting 139 succinyllysine site changes in 40 pathways. Further analysis showed that TAK242 treatment induced an increase of 29 succinyllysine sites on 28 succinylated proteins and a reduction of 24 succinyllysine sites on 23 succinylated proteins in the ICH brains. TAK242 treatment induced both protein hypersuccinylations and hyposuccinylations, which were mainly located in the mitochondria and cytoplasm. GO analysis showed that TAK242 treatment-induced changes in the ICH-associated succinylated proteins were mostly located in synapses, membranes and vesicles, and enriched in many cellular functions/compartments, such as metabolism, synapse, and myelin. KEGG analysis showed that TAK242-induced hyposuccinylation was mainly linked to fatty acid metabolism, including elongation and degradation. Moreover, a combined analysis of the succinylproteomic data with previously published transcriptome data revealed that most of the differentially succinylated proteins induced by TAK242 treatment were mainly distributed throughout neurons, astrocytes, and endothelial cells, and the mRNAs of seven and three succinylated proteins were highly expressed in neurons and astrocytes, respectively. In conclusion, we revealed that several TLR4 signaling pathways affect the succinylation processes and pathways in mouse ICH brains, providing new insights on the ICH pathophysiological processes. Data are available via ProteomeXchange with identifier PXD025622.

Ligustilide alleviates neurotoxicity in SH-SY5Y cells induced by Aß25-35 via regulating endoplasmic reticulum stress and autophagy.

Ligustilide is a phenolic compound isolated from Asian plants of Umbelliferae family. This study was aimed at exploring the neuroprotective effects of Ligustilide from the perspective of endoplasmic reticulum stress (ERS) and autophagy. The Alzheimer's disease (AD) cell models were constructed by SH-SY5Y cell line, which was exposed to 20 µM Aß25-35 . CCK-8 was used to evaluate the cell viability of Ligustilide on AD cell model. Hoechst staining and LysoTracker Red were used to test the cell apoptosis and Lysosome function, respectively. ERS in living cells were detected by Thioflavin T. The expression of autophagy-related proteins (LC3B-II/I, P62/SQSTM1, Beclin1, and Atg5), ERS marker proteins (PERK, GRP78, and CHOH), and apoptosis proteins (Bax, Bcl-2, and Caspase-12) were analyzed by Western blot analyses. Aß25-35 could induce ERS and autophagy in a time-dependent manner in SH-SY5Y cells. We demonstrated that Ligustilide significantly decreased the rate of apoptosis, and improved the viability of cells. Simultaneously, Ligustilide effectively modulated ERS via inhibiting the over-activation of GRP78/PERK/CHOP signaling pathway. In addition, Ligustilide alleviated the accumulation of autophagy vacuoles, reduced the ratio of LC3B-II/I and the level of P62/SQSTM1. Ligustilide significantly up-regulated lysosomal acidity and the expression of Cathepsin D (CTSD). Ligustilide could rescue lysosomal function to promote autophagy flux and inhibit the over-activation of ERS. This finding may contribute to the development of new therapeutic strategies for AD.

Regulating the Enteric Nervous System against Obesity in Mice by Electroacupuncture.

BACKGROUND AND OBJECTIVES: The enteric nervous system (ENS) dominates the onset of obesity and has been shown to regulate nutrient absorption and energy metabolism. METHODS AND STUDY DESIGN: This study was performed to investigate the role of electroacupuncture in regulating ENS function in obese mice. Obese mice were obtained by high-fat diet. 16S rRNA pyrosequencing, Western blotting, quantitative PCR, and neurotransmitter analysis were used for this purpose. RESULTS: Body weight, Lee index, serum lipid, leptin, and adiponectin levels, and other basic indices were significantly ameliorated after electroacupuncture intervention. The pathological ENS scores, serum neurotransmitter levels, and intestinal transit rate were markedly changed in obese mice. Moreover, electroacupuncture promoted the diversity of gut microbiota. No significant differences were observed 21 and 28 days after electroacupuncture. CONCLUSIONS: These results suggested ENS may be a new treatment approach to obesity.

Astrocyte-derived lactate aggravates brain injury of ischemic stroke in mice by promoting the formation of protein lactylation.

Aim: Although lactate supplementation at the reperfusion stage of ischemic stroke has been shown to offer neuroprotection, whether the role of accumulated lactate at the ischemia phase is neuroprotection or not remains largely unknown. Thus, in this study, we aimed to investigate the roles and mechanisms of accumulated brain lactate at the ischemia stage in regulating brain injury of ischemic stroke. Methods and Results: Pharmacological inhibition of lactate production by either inhibiting LDHA or glycolysis markedly attenuated the mouse brain injury of ischemic stroke. In contrast, additional lactate supplement further aggravates brain injury, which may be closely related to the induction of neuronal death and A1 astrocytes. The contributing roles of increased lactate at the ischemic stage may be related to the promotive formation of protein lysine lactylation (Kla), while the post-treatment of lactate at the reperfusion stage did not influence the brain protein Kla levels with neuroprotection. Increased protein Kla levels were found mainly in neurons by the HPLC-MS/MS analysis and immunofluorescent staining. Then, pharmacological inhibition of lactate production or blocking the lactate shuttle to neurons showed markedly decreased protein Kla levels in the ischemic brains. Additionally, Ldha specific knockout in astrocytes (Aldh1l1 CreERT2; Ldha fl/fl mice, cKO) mice with MCAO were constructed and the results showed that the protein Kla level was decreased accompanied by a decrease in the volume of cerebral infarction in cKO mice compared to the control groups. Furthermore, blocking the protein Kla formation by inhibiting the writer p300 with its antagonist A-485 significantly alleviates neuronal death and glial activation of cerebral ischemia with a reduction in the protein Kla level, resulting in extending reperfusion window and improving functional recovery for ischemic stroke. Conclusion: Collectively, increased brain lactate derived from astrocytes aggravates ischemic brain injury by promoting the protein Kla formation, suggesting that inhibiting lactate production or the formation of protein Kla at the ischemia stage presents new therapeutic targets for the treatment of ischemic stroke.

Metabolomics Analysis of Electroacupuncture Pretreatment Induced Neuroprotection on Mice with Ischemic Stroke.

The brain metabolic changes caused by the interruption of blood supply are the initial factors of brain injury in ischemic stroke. Electroacupuncture (EA) pretreatment has been shown to protect against ischemic stroke, but whether its neuroprotective mechanism involves metabolic regulation remains unclear. Based on our finding that EA pretreatment significantly alleviated ischemic brain injury in mice by reducing neuronal injury and death, we performed a gas chromatography-time of flight mass spectrometry (GC-TOF/MS) to investigate the metabolic changes in the ischemic brain and whether EA pretreatment influenced these changes. First, we found that some glycolytic metabolites in the normal brain tissues were reduced by EA pretreatment, which may lay the foundation of neuroprotection for EA pretreatment against ischemic stroke. Then, 6[Formula: see text]h of cerebral ischemia-induced brain metabolic changes, especially the enhanced glycolysis, were partially reversed by EA pretreatment, which was manifested by the brain levels of 11 of 35 up-regulated metabolites and 18 of 27 down-regulated metabolites caused by cerebral ischemia significantly decreasing and increasing, respectively, due to EA pretreatment. A further pathway analysis showed that these 11 and 18 markedly changed metabolites were mainly involved in starch and sucrose metabolism, purine metabolism, aspartate metabolism, and the citric acid cycle. Additionally, we found that EA pretreatment raised the levels of neuroprotective metabolites in both normal and ischemic brain tissues. In conclusion, our study revealed that EA pretreatment may attenuate the ischemic brain injury by inhibiting glycolysis and increasing the levels of some neuroprotective metabolites.

Chlorogenic acid enhances autophagy by upregulating lysosomal function to protect against SH-SY5Y cell injury induced by H2O2.

Autophagy serves an important role in amyloid-ß (Aß) metabolism and τ processing and clearance in Alzheimer's disease. The progression of Aß plaque accumulation and hyperphosphorylation of τ proteins are enhanced by oxidative stress. A hydrogen peroxide (H2O2) injury cell model was established using SH-SY5Y cells. Cells were randomly divided into normal, H2O2 and chlorogenic acid (5-caffeoylquinic acid; CGA) groups. The influence of CGA on cell viability was evaluated using a Cell Counting Kit-8 assay and cell death was assessed using Hoechst 33342 nuclear staining. Autophagy induction and fusion of autophagic vacuoles assays were performed using monodansylcadaverine staining. Additionally, SH-SY5Y cells expressing Ad-mCherry-green fluorescent protein-LC3B were established to detect autophagic flow. LysoTracker Red staining was used to evaluate lysosome function and LysoSensor™ Green staining assays were used to assess lysosomal acidification. The results demonstrated that CGA decreased the apoptosis rate, increased cell viability and improved cell morphology in H2O2-treated SH-SY5Y cells. Furthermore, CGA alleviated the accumulation of autophagic vacuoles, reduced the LC3BII/I ratio and decreased P62 levels, resulting in increased autophagic flux. Additionally, CGA upregulated lysosome acidity and increased the expression levels of cathepsin D. Importantly, these effects of CGA on H2O2-treated SH-SY5Y cells were mediated via the mTOR-transcription factor EB signaling pathway. These results indicated that CGA protected cells against H2O2-induced oxidative damage via the upregulation of autophagosomes, which promoted autophagocytic degradation and increased autophagic flux.

Synaptosomal-associated protein 25 may be an intervention target for improving sensory and locomotor functions after spinal cord contusion.

Synaptosomal-associated protein 25 kDa (SNAP-25) is localized on the synapse and participates in exocytosis and neurotransmitter release. Decreased expression of SNAP-25 is associated with Alzheimer's disease and attention deficit/hyperactivity disorder. However, the expression of SNAP-25 in spinal cord contusion injury is still unclear. We hypothesized that SNAP-25 is associated with sensory and locomotor functions after spinal cord injury. We established rat models of spinal cord contusion injury to detect gene changes with a gene array. A decreased level of SNAP-25 was detected by quantitative real time-polymerase chain reaction and western blot assay at 1, 3, 7, 14 and 28 days post injury. SNAP-25 was localized in the cytoplasm of neurons of the anterior and posterior horns, which are involved in locomotor and sensory functions. Our data suggest that reduced levels of SNAP-25 are associated with sensory and locomotor functions in rats with spinal cord contusion injury.

Lentivirus-mediated inhibition of tumour necrosis factor-α improves motor function associated with PRDX6 in spinal cord contusion rats.

The recovery of motor function in rats is inhibited following contusion spinal cord injury (cSCI). However, the mechanism of tumour necrosis factor α (TNF-α) in motor function after cSCI associated with peroxiredoxin 6 (PRDX6) remains unknown. We randomly divided rats into four groups: sham, cSCI, vector and lentivirus mediating TNF-α RNA interference (TNF-α-RNAi-LV) group. The Basso, Beattie, Bresnahan (BBB) scale was used to evaluate motor function. Real-time quantitative PCR (qRT-PCR) and western blotting were used to detect the expression of TNF-α and PRDX6, which were located in neurons using immunohistochemistry (IHC) and immunofluorescence. Subsequently, lentiviral-mediated TNF-α was used to determine the role of TNF-αand the relationship of PRDX6 and TNF-α in cSCI. After cSCI, the motor capability of hind limbs disappeared and was followed by recovery of function. IHC analysis indicated that TNF-α and PRDX6 were primarily located in spinal cord neurons. TNF-α interference significantly improved neural behaviour and increased expression of PRDX6. Our study suggests that inhibition of TNF-α can promote the recovery of motor function. The underlying mechanism of TNF-α-promoted motor function may be connected with the up-regulation of PRDX6. This provides a new strategy or target for the clinical treatment of SCI in future.