Crystal structure of a tetrameric RNA G-quadruplex formed by hexanucleotide repeat expansions of C9orf72 in ALS/FTD.

The abnormal GGGGCC hexanucleotide repeat expansions (HREs) in C9orf72 cause the fatal neurodegenerative diseases including amyotrophic lateral sclerosis and frontotemporal dementia. The transcribed RNA HREs, short for r(G4C2)n, can form toxic RNA foci which sequestrate RNA binding proteins and impair RNA processing, ultimately leading to neurodegeneration. Here, we determined the crystal structure of r(G4C2)2, which folds into a parallel tetrameric G-quadruplex composed of two four-layer dimeric G-quadruplex via 5'-to-5' stacking in coordination with a K+ ion. Notably, the two C bases locate at 3'- end stack on the outer G-tetrad with the assistance of two additional K+ ions. The high-resolution structure reported here lays a foundation in understanding the mechanism of neurological toxicity of RNA HREs. Furthermore, the atomic details provide a structural basis for the development of potential therapeutic agents against the fatal neurodegenerative diseases ALS/FTD.

Neuroprotective mechanisms of mangiferin in neurodegenerative diseases.

The central nervous system (CNS) regulates and coordinates an extensive array of complex processes requiring harmonious regulation of specific genes. CNS disorders represent a large burden on society and cause enormous disability and economic losses. Traditional Chinese medicine (TCM) has been used for many years in the treatment of neurological illnesses, such as Alzheimer's disease, Parkinson's disease, stroke, and depression, as the combination of TCM and Western medicine has superior therapeutic efficacy and minimal toxic side effects. Mangiferin (MGF) is an active compound of the traditional Chinese herb rhizome anemarrhenae, which has antioxidant, anti-inflammation, anti-lipid peroxidation, immunomodulatory, and anti-apoptotic functions in the CNS. MGF has been demonstrated to have therapeutic effects in CNS diseases through a multitude of mechanisms. This review outlines the latest research on the neuroprotective ability of MGF and the diverse molecular mechanisms involved.

Dihydroartemisinin ameliorates LPS-induced neuroinflammation by inhibiting the PI3K/AKT pathway.

Neuroinflammation can cause multiple neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). Recent studies have shown that the artemisinin derivative dihydroartemisinin (DHA) can be used as an immunomodulatory, anti-inflammatory and anti-tumor agent. The anti-neuroinflammatory effects of DHA were evaluated in our study, and the underlying mechanisms were explored using the Morris water maze test (MWMT), Open-field test (OFT) and Closed-field test (CFT), Elevated plus maze test (EPMT), Nissl Staining, Immunofluorescence analysis, RT-PCR, and Western Blot. Our results show that DHA significantly inhibits LPS-induced inflammation and attenuates LPS-induced behavioral and memory disorders. 1. Behavioral test results: 1) in the water maze test, the mice in the LPS group showed increased escape latency and length of the movement path on the third day; they also had a decreased number of crossings of the target quadrant after the platform was removed on the 5th day and remained in the target quadrant for less time; 2) in the open- and closed-field experiment, the number of activities and activities in the open-field were significantly reduced; 3) in the elevated cross maze experiment, LPS-treated mice exhibited a significant reduction in the number of times and the time to enter the open arm; the above behavior was reversed after DHA treatment. 2. Nissl staining results: compared with the Control group, the LPS group showed significant damage, and the number of damaged cells in the hippocampal CA1, CA2, CA3 and DG regions was increased; DHA treatment reduced cell damage. 3. RT-PCR results: compared with the Control group, the LPS group showed increased expression of IL-1ß and IL-6 but decreased expression after DHA treatment. 4. GFAP fluorescent staining: compared with the control group, the corresponding reactivity of positive cells in the LPS-induced group was increased in the CA1-CA3 and DG regions of the hippocampus; compared with the LPS-induced mice, cells in the LPS + DHA group showed significantly reduced reactivity (GFAP). 5. Western blot results: compared with the Control group, the LPS group showed increased expression of P-PI3K/PI3K, P-AKT/AKT, IL-6 and TNFα and a decreased expression of P-PI3K/PI3K, IL-6, TNF and P-AKT/AKT after DHA treatment. Our findings provide direct evidence for the potential use of DHA in the treatment of neuroinflammatory diseases.

Inhibition of LPS-induced brain injury by NR2B antagonists through reducing assembly of NR2B-CaMKII-PSD95 signal module.

Background: Accumulating evidence suggests that inflammation is a contributor to the cause and progression of neurodegenerative disease, such as Alzheimer's disease (AD) and Parkinson disease (PD). However, the exact mechanisms of neuroinflammation are still unclear. Here, we discussed the potential mechanisms of lipopolysaccharide (LPS)-induced brain injury via NR2B antagonists (Ro25-6981) treatment in mice. Methods: Neuroinflammation was induced in mice by virtue of LPS (1 mg/kg) by intraperitoneal injection. Immunoprecipitation was performed to measure the assembly of NR2B-calmodulin dependent protein kinase II (CaMKII)-Postsynaptic density protein 95 (PSD95) signal module in the hippocampus and frontal cortex. Nissl's staining was employed to access neuron injury in the brain. Results: Data demonstrated that LPS could induce neuron damage, and promote the assembly of NR2B-CaMKII-PSD95 signal module and increase the expression of phosphorylated CaMKII and c-Jun N-terminal kinase (JNK) in the frontal cortex and hippocampus. However, NR2B antagonists could protect neuron injury against LPS-induced inflammation, inhibit the assembly of NR2B-CaMKII-PSD95 signal module and decrease the level of phosphorylated CaMKII and JNKs in mice. Conclusions: These findings indicated that the assembly of NR2B-CaMKII-PSD95 signal module is related to LPS-induced neuroinflammation, NR2B plays a key role in the assembly of NR2B-CaMKII-PSD95 signal module and NR2B antagonists could alleviate LPS-related inflammation through the reduced assembly of NR2B-CaMKII-PSD95 signal module in frontal cortex and hippocampus.

Inhibition of HDAC6 alleviating lipopolysaccharide-induced p38MAPK phosphorylation and neuroinflammation in mice.

Context: Researchers in a variety of fields have extensively focused on histone deacetylase 6 (HDAC6) due to its aggravation of inflammatory reaction. However, relevant studies examining whether HDAC6 could exacerbate lipopolysaccharide (LPS)-induced inflammation are still lacking. Objective: We assessed the role of HDAC6 in LPS-induced brain inflammation and used the HDAC6-selective inhibitor Tubastatin A (TBSA) to investigate the potential mechanisms further. Materials and methods: Brain inflammation was induced in Kunming (KM) mice via intraperitoneal (I.P.), injection of Lipopolysaccharide (LPS) (1 mg/kg), the TBSA (0.5 mg/kg) was delivered via intraperitoneal. The phosphorylated p38 (p-p38) Mitogen-activated protein kinases (MAPK) and expression of typical inflammatory mediators, including tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in both the hippocampus and cortex, were examined by immunoblotting. Nissl staining was used to detect the neuronal damage in the hippocampus and the cortex. Results: About 1 mg/kg LPS via daily intraperitoneal (I.P.) injections for 12 days significantly increased p38 MAPK phosphorylation, TNF-α and IL-6 expression, and neuronal loss. However, 0.5 mg/kg TBSA (three days before LPS treatment) by I.P. injections for 15 days could reverse the above results. Conclusions: This present study provided evidence that TBSA significantly suppressed LPS-induced neuroinflammation and the expression of p-p38. Results derived from our study might help reveal the effective targeting strategies of LPS-induced brain inflammation through inhibiting HDAC6.

Inhibition of NF-κB activity by aminoguanidine alleviates neuroinflammation induced by hyperglycemia.

Neuroinflammation is a key feature of cerebral complication which is associated with diabetes mellitus (DM). Inducible nitric oxide synthase (iNOS) is implicated in the pathogenesis of neuroinflammation. However, how iNOS facilitates the development of inflammation in brain is still unidentified. The aim of the present study was to investigate the association of iNOS and neuroinflammation in diabetic mice, and elucidate the potential mechanisms underlying aminoguanidine (AG), the selective inhibitor of iNOS, protected neurons against inflammation in diabetic mice. In present experiment, diabetic mice model were established by a single intraperitoneal injection of streptozotocin (STZ). AG was administered to diabetic mice for ten weeks after this disease induction. Then we measured iNOS activity in the serum and brain, detected the glial fibrillary acidic protein (GFAP) and ionised calcium binding adaptor molecule-1 (Iba-1) expressions in the brain. Moreover, nuclear factor-kappa B (NF-κB) in cytoplasm and nucleus were tested by IP and WB. Results revealed that high expression of iNOS in serum and brain could be reversed by AG treatment. Furthermore, AG could also inhibit GFAP and Iba-1 expressions, and NF-κB nuclear translocation by inhibiting it from binding to iNOS in cytoplasm. Our findings indicated that iNOS can combine with NF-κB in cytoplasm and promote its nuclear transfer in diabetic mice. Furthermore, AG decreased neuroinflammation through inhibiting iNOS activity and reducing NF-κB nuclear translocation by promoting its dissociation with iNOS in cytoplasm.

Butylphthalide Suppresses Neuronal Cells Apoptosis and Inhibits JNK-Caspase3 Signaling Pathway After Brain Ischemia /Reperfusion in Rats.

Although Butylphthalide (BP) has protective effects that reduce ischemia-induced brain damage and neuronal cell death, little is known about the precise mechanisms occurring during cerebral ischemia/reperfusion (I/R). Therefore, the aim of this study was to investigate the neuroprotective mechanisms of BP against ischemic brain injury induced by cerebral I/R through inhibition of the c-Jun N-terminal kinase (JNK)-Caspase3 signaling pathway. BP in distilled non-genetically modified Soybean oil was administered intragastrically three times a day at a dosage of 15 mg/(kg day) beginning at 20 min after I/R in Sprague-Dawley rats. Immunohistochemical staining and Western blotting were performed to examine the expression of related proteins, and TUNEL-staining was used to detect the percentage of neuronal apoptosis in the hippocampal CA1 region. The results showed that BP could significantly protect neurons against cerebral I/R-induced damage. Furthermore, the expression of p-JNK, p-Bcl2, p-c-Jun, FasL, and cleaved-caspase3 was also decreased in the rats treated with BP. In summary, our results imply that BP could remarkably improve the survival of CA1 pyramidal neurons in I/R-induced brain injury and inhibit the JNK-Caspase3 signaling pathway.

Anti-inflammatory Effect of Astaxanthin on the Sickness Behavior Induced by Diabetes Mellitus.

Chronic inflammation appears to play a critical role in sickness behavior caused by diabetes mellitus. Astaxanthin has been used in treating diabetes mellitus and diabetic complications because of its neuroprotective and anti-inflammatory actions. However, whether astaxanthin can improve sickness behavior induced by diabetes and its potential mechanisms are still unknown. The aim of this study was to investigate the effects of astaxanthin on diabetes-elicited abnormal behavior in mice and its corresponding mechanisms. An experimental diabetic model was induced by streptozotocin (150 mg/kg) and astaxanthin (25 mg/kg/day) was provided orally for 10 weeks. Body weight and water consumption were measured, and the sickness behavior was evaluated by the open field test (OFT) and closed field test (CFT). The expression of glial fibrillary acidic protein (GFAP) was measured, and the frontal cortical cleaved caspase-3 positive cells, interleukin-6 (IL-6), and interleukin-1ß (IL-1ß) expression levels were also investigated. Furthermore, cystathionine ß-synthase (CBS) in the frontal cortex was detected to determine whether the protective effect of astaxanthin on sickness behavior in diabetic mice is closely related to CBS. As expected, we observed that astaxanthin improved general symptoms and significantly increase horizontal distance and the number of crossings in the OFT and CFT. Furthermore, data showed that astaxanthin could decrease GFAP-positive cells in the brain and down-regulate the cleaved caspase-3, IL-6, and IL-1ß, and up-regulate CBS in the frontal cortex. These results suggest that astaxanthin provides neuroprotection against diabetes-induced sickness behavior through inhibiting inflammation, and the protective effects may involve CBS expression in the brain.

Mangiferin regulates interleukin-6 and cystathionine-b-synthase in lipopolysaccharide-induced brain injury.

Mangiferin has been extensively applied in different fields due to its anti-inflammatory properties. However, the precise mechanism used by mangiferin on lipopolysaccharide (LPS)-induced inflammation has not been elucidated. Here, we discuss the potential mechanism of mangiferin during a LPS-induced brain injury. Brain injury was induced in ICR mice via intraperitoneal LPS injection (5 mg/kg). Open- and closed-field tests were used to detect the behaviors of mice, while immunoblotting was performed to measure the expression of interleukin-6 (IL-6) and cystathionine-b-synthase (CBS) in the hippocampus after mangiferin was orally administered (p.o.). Mangiferin relieved LPS-induced sickness 6 and 24 h after LPS injection; in addition, this compound suppressed LPS-induced IL-6 production after 24 h of LPS induction as well as the downregulation of LPS-induced CBS expression after 6 and 24 h of LPS treatment in the hippocampus. Therefore, mangiferin attenuated sickness behavior by regulating the expression of IL-6 and CBS.

Growth inhibition effect of HMME-mediated PDT on hepatocellular carcinoma HepG2 cells.

Photodynamic therapy (PDT) is considered a promising new strategy for liver cancer treatment. Three elements of PDT--optical output power, irradiation time, and photosensitizer concentration--play important roles in promoting cell death. This research aimed to characterize the effects of hematoporphyrin monomethyl ether (HMME)-based PDT on hepatocellular carcinoma cells HepG2 and thus elucidate the relationship between cell death and the three elements mentioned earlier. Furthermore, in this study, we present a parameter that represents the cumulative effects of these elements. The accumulation of HMME in HepG2 cells was observed by fluorescence microscopy. The absorption spectrum of HMME was detected using fluorescence spectral analysis. The viability of the treated cells was determined using the MTT assay, and cell apoptosis was evaluated using flow cytometry. We found that the fluorescence intensity was positively correlated with the incubation time for up to 2 h. The cell growth inhibition rate was significantly high and gradually increased with increasing concentrations of HMME or increasing light intensity, which was calculated as optical output power × irradiation time. Further analysis revealed an e-exponential decay of the cell survival rate to the product of the HMME concentration and the light intensity. We defined the product as parameter B (B = optical output power × irradiation time × HMME concentration). Similarly, the rate of cell apoptosis showed roughly e-exponential growth to parameter B. In conclusion, HMME-mediated PDT can significantly kill HepG2 cells, and the killing effect was related to the cumulative effects of the optical output power, the irradiation time, and the HMME concentration. Therefore, the newly defined parameter B, as a comprehensive physical quantity, may be of great significance for the regulation of light and photosensitizer according to patient-specific conditions in clinical practice.

Binding of RAGE and RIPK1 induces cognitive deficits in chronic hyperglycemia-derived neuroinflammation.

AIMS: Chronic hyperglycemia-induced inflammation of the hippocampus is an important cause of cognitive deficits in diabetic patients. The receptor for advanced glycation end products (RAGE), which is widely expressed in the hippocampus, is a crucial factor in this inflammation and the associated cognitive deficits. We aimed to reveal the underlying mechanism by which RAGE regulates neuroinflammation in the pathogenesis of diabetes-induced cognitive impairment. METHODS: We used db/db mice as a model for type 2 diabetes to investigate whether receptor-interacting serine/threonine protein kinase 1 (RIPK1), which is expressed in microglia in the hippocampal region, is a key protein partner for RAGE. GST pull-down assays and AutoDock Vina simulations were performed to identify the key structural domain in RAGE that binds to RIPK1. Western blotting, co-immunoprecipitation (Co-IP), and immunofluorescence (IF) were used to detect the levels of key proteins or interaction between RAGE and RIPK1. Cognitive deficits in the mice were assessed with the Morris water maze (MWM) and new object recognition (NOR) and fear-conditioning tests. RESULTS: RAGE binds directly to RIPK1 via the amino acid sequence (AAs) 362-367, thereby upregulating phosphorylation of RIPK1, which results in activation of the NLRP3 inflammasome in microglia and ultimately leads to cognitive impairments in db/db mice. We mutated RAGE AAs 362-367 to reverse neuroinflammation in the hippocampus and improve cognitive function, suggesting that RAGE AAs 362-367 is a key structural domain that binds directly to RIPK1. These results also indicate that hyperglycemia-induced inflammation in the hippocampus is dependent on direct binding of RAGE and RIPK1. CONCLUSION: Direct interaction of RAGE and RIPK1 via AAs 362-367 is an important mechanism for enhanced neuroinflammation in the hyperglycemic environment and is a key node in the development of cognitive deficits in diabetes.

TLR4/Rac1/NLRP3 Pathway Mediates Amyloid-ß-Induced Neuroinflammation in Alzheimer's Disease.

Background: Neuroinflammation plays a crucial part in the initial onset and progression of Alzheimer's disease (AD). NLRP3 inflammasome was demonstrated to get involved in amyloid-ß (Aß)-induced neuroinflammation. However, the mechanism of Aß-triggered activation of NLRP3 inflammasome remains poorly understood. Objective: Based on our previous data, the study aimed to identify the downstream signals that bridge the activation of TLR4 and NLRP3 inflammasome associated with Aß. Methods: BV-2 cells were transfected with TLR4siRNA or pretreated with a CLI-095 or NSC23766, followed by Aß1-42 treatment. APP/PS1 mice were injected intraperitoneally with CLI-095 or NSC23766. NLRP3 inflammasome and microglia activation was detected with immunostaining and western blot. G-LISA and Rac1 pull-down activation test were performed to investigate the activation of Rac1. Real-time PCR and ELISA were used to detect the inflammatory cytokines. Aß plaques were assessed by western blotting and immunofluorescence staining. Morris water maze test was conducted to determine the spatial memory in mice. Results: Rac1 and NLRP3 inflammasome were activated by Aß in both in vitro and in vivo experiments. Inhibition of TLR4 reduced the activity of Rac1 and NLRP3 inflammasome induced by Aß1-42. Furthermore, inhibition of Rac1 blocked NLRP3 inflammasome activation mediated by TLR4. Blocking the pathway by CLI095 or NSC23766 suppressed Aß1-42-triggered activation of microglia, reduced the expression of pro-inflammatory mediators and ameliorated the cognition deficits in APP/PS1 mice. Conclusions: Our study demonstrated that TLR4/Rac1/NLRP3 pathway mediated Aß-induced neuroinflammation, which unveiled a novel pathway and key contributors underlying the pathogenic mechanism of Aß.

MKK3 K329 Mutation Attenuates Diabetes-Associated Cognitive Dysfunction by Blocking the MKK3-RAGE Interaction and Inhibiting Neuroinflammation.

The receptor for advanced glycation end products (RAGE) contributes to diabetes-associated cognitive dysfunction (DACD) through the interaction of its C-terminal AAs 2-5 with mitogen-activated protein kinase kinase 3 (MKK3). However, the associated MKK3 binding site is unknown. Here, db/db mice were used as a model for type 2 diabetes. GST pull-down assays and AutoDock Vina simulations were conducted to identify the key RAGE binding site in MKK3. This binding site was mutated to investigate its effects on DACD and to elucidate the underlying mechanisms. The interaction of MKK3 and RAGE, the levels of inflammatory factors, and the activation of microglia and astrocytes were tested. Synaptic morphology and plasticity in hippocampal neurons were assessed via electrophysiological recordings and Golgi staining. Behavioral tests were used to assess cognitive function. In this study, MKK3 bound directly to RAGE via its lysine 329 (K329), leading to the activation of the nuclear factor-κB (NF-κB) signaling pathway, which in turn triggered neuroinflammation and synaptic dysfunction, and ultimately contributed to DACD. MKK3 mutation at K329 reversed synaptic dysfunction and cognitive deficits by downregulating the NF-κB signaling pathway and inhibiting neuroinflammation. These results confirm that neuroinflammation and synaptic dysfunction in the hippocampus rely on the direct binding of MKK3 and RAGE. We conclude that MKK3 K329 binding to C-terminal RAGE (ct-RAGE) is a key mechanism by which neuroinflammation and synaptic dysfunction are induced in the hippocampus. This study presents a novel mechanism for DACD and proposes a novel therapeutic avenue for neuroprotection in DACD.

TAT-W61 peptide attenuates neuronal injury through blocking the binding of S100b to the V-domain of Rage during ischemic stroke.

Ischemic stroke is a devastative nervous system disease associated with high mortality and morbidity rates. Unfortunately, no clinically effective neuroprotective drugs are available now. In ischemic stroke, S100 calcium-binding protein b (S100b) binds to receptor for advanced glycation end products (Rage), leading to the neurological injury. Therefore, disruption of the interaction between S100B and Rage can rescue neuronal cells. Here, we designed a peptide, termed TAT-W61, derived from the V domain of Rage which can recognize S100b. Intriguingly, TAT-W61 can reduce the inflammatory caused by ischemic stroke through the direct binding to S100b. The further investigation demonstrated that TAT-W61 can improve pathological infarct volume and reduce the apoptotic rate. Particularly, TAT-W61 significantly improved the learning ability, memory, and motor dysfunction of the mouse in the ischemic stroke model. Our study provides a mechanistic insight into the abnormal expression of S100b and Rage in ischemic stroke and yields an invaluable candidate for the development of drugs in tackling ischemic stroke. KEY MESSAGES: S100b expression is higher in ischemic stroke, in association with a high expression of many genes, especially of Rage. S100b is directly bound to the V-domain of Rage. Blocking the binding of S100b to Rage improves the injury after ischemic stroke.

The N-terminal region of Cdc6 specifically recognizes human DNA G-quadruplex.

Guanine (G)-rich nucleic acid sequences can form diverse G-quadruplex structures located in functionally significant genome regions, exerting regulatory control over essential biological processes, including DNA replication in vivo. During the initiation of DNA replication, Cdc6 is recruited by the origin recognition complex (ORC) to target specific chromosomal DNA sequences. This study reveals that human Cdc6 interacts with G-quadruplex structure through a distinct region within the N-terminal intrinsically disordered region (IDR), encompassing residues 7-20. The binding region assumes a hook-type conformation, as elucidated by the NMR solution structure in complex with htel21T18. Significantly, mutagenesis and in vivo investigations confirm the highly specific nature of Cdc6's recognition of G-quadruplex. This research enhances our understanding of the fundamental mechanism governing the interaction between G-quadruplex and the N-terminal IDR region of Cdc6, shedding light on the intricate regulation of DNA replication processes.

PRDX1 Interfering Peptide Disrupts Amino Acids 70-90 of PRDX1 to Inhibit the TLR4/NF-κB Signaling Pathway and Attenuate Neuroinflammation and Ischemic Brain Injury.

Ischemic stroke ranks among the leading causes of death and disability in humans and is accompanied by motor and cognitive impairment. However, the precise mechanisms underlying injury after stroke and effective treatment strategies require further investigation. Peroxiredoxin-1 (PRDX1) triggers an extensive inflammatory cascade that plays a pivotal role in the pathology of ischemic stroke, resulting in severe brain damage from activated microglia. In the present study, we used molecular dynamics simulation and nuclear magnetic resonance to detect the interaction between PRDX1 and a specific interfering peptide. We used behavioral, morphological, and molecular experimental methods to demonstrate the effect of PRDX1-peptide on cerebral ischemia-reperfusion (I/R) in mice and to investigate the related mechanism. We found that PRDX1-peptide bound specifically to PRDX1 and improved motor and cognitive functions in I/R mice. In addition, pretreatment with PRDX1-peptide reduced the infarct area and decreased the number of apoptotic cells in the penumbra. Furthermore, PRDX1-peptide inhibited microglial activation and downregulated proinflammatory cytokines including IL-1ß, IL-6, and TNF-α through inhibition of the TLR4/NF-κB signaling pathway, thereby attenuating ischemic brain injury. Our findings clarify the precise mechanism underlying PRDX1-induced inflammation after ischemic stroke and suggest that the PRDX1-peptide can significantly alleviate the postischemic inflammatory response by interfering with PRDX1 amino acids 70-90 and thereby inhibiting the TLR4/NF-κB signaling pathway. Our study provides a theoretical basis for a new therapeutic strategy to treat ischemic stroke.

NR2B-containing NMDA receptors expression and their relationship to apoptosis in hippocampus of Alzheimer's disease-like rats.

Although studies have shown that excitotoxicity mediated by N-methyl-D-aspartate receptors (NMDARs, NR) plays a prominent role in Alzheimer's disease (AD), the precise expression patterns of NMDARs and their relationship to apoptosis in AD have not been clearly established. In this study, we used Abeta (Aß) 1-40 and AlCl(3) to establish AD rat model. The behavioral changes were detected by morris water maze and step-down test. The hippocampal amyloid deposition and pathological changes were determined by congo red and hematoxylin-eosin staining. Immunohistochemistry was used to detect expression of NR1, NR2A and NR2B, and TUNEL staining was used to detect apoptosis. Results showed that water maze testing escape latency of AD-like rats was prolonged significantly. Reaction time, basal number of errors, and number of errors of step-down test were increased significantly; latency period of step-down test was shortened significantly in AD-like rats. Amyloid substance deposition and obvious damage changes could be seen in hippocampus of AD-like rats. These results suggested that AD rat model could be successfully established by Aß1-40 and AlCl(3). Results also showed that expression of NR1 and NR2B were significantly increased, but expression of NR2A had no significant change, in AD-like rat hippocampus. Meanwhile, apoptotic cells were significantly increased in AD-like rat hippocampus, especially in CA1 subfield and followed by dentate gyrus and CA3 subfield. These results implied that NR2B-, not NR2A-, containing NMDARs showed pathological high expression in AD-like rat hippocampus. This pathological high expression with apoptosis and selective vulnerability of hippocampus might be exist a specific relationship.

Interactions Between Intestinal Microbiota and Neural Mitochondria: A New Perspective on Communicating Pathway From Gut to Brain.

Many studies shown that neurological diseases are associated with neural mitochondrial dysfunctions and microbiome composition alterations. Since mitochondria emerged from bacterial ancestors during endosymbiosis, mitochondria, and bacteria had analogous genomic characteristics, similar bioactive compounds and comparable energy metabolism pathways. Therefore, it is necessary to rationalize the interactions of intestinal microbiota with neural mitochondria. Recent studies have identified neural mitochondrial dysfunction as a critical pathogenic factor for the onset and progress of multiple neurological disorders, in which the non-negligible role of altered gut flora composition was increasingly noticed. Here, we proposed a new perspective of intestinal microbiota - neural mitochondria interaction as a communicating channel from gut to brain, which could help to extend the vision of gut-brain axis regulation and provide additional research directions on treatment and prevention of responsive neurological disorders.

Mitochondrial DNA polymorphisms in COX1 affect the lifespan of Caenorhabditis elegans through nuclear gene dct-15.

Mutations in the mitochondrial DNA (mtDNA) are closely related to age and age-related complex diseases, but the exact regulatory mechanism of mtDNA natural variation or polymorphism and ageing remains unclear. Recently, nuclear genes that regulate mitochondrial functions and thereby influence ageing have been widely studied. In this study, the relationship between the retrograde communication from the mitochondria to the nucleus and its ultimate effect on ageing has been elucidated. This study found that the natural variations in COX1 of the mitochondria in the Caenorhabditis elegans population do not correlate with multiple phenotypes, except for a mild correlation with lifespan. After excluding the differences in the nuclear genome, the correlation between natural mitochondrial variation and lifespan increased significantly. Moreover, mtDNA variation downregulated the nuclear dct-15 gene expression, which consequently reduced the lifespan, development rate and motility of C. elegans. dct-15 mutations decreased mitochondria copy number but increased ATP content and mitochondrial ultrastructure. Thus, the results indicated that dct-15 interacted with the mitochondrial DNA polymorphisms in COX1 and is associated with ageing. Finally, bioinformatic analyses revealed that mtDNA variation regulated the structural constituent of the cuticle via dct-15 and suggested that the structural constituent of the cuticle could have an important role in the development and ageing processes. These results provide insights into the mtDNA mechanism that can alter the nuclear gene and thereby regulate ageing and ageing-related diseases.

Receptor for advanced glycation end products aggravates cognitive deficits in type 2 diabetes through binding of C-terminal AAs 2-5 to mitogen-activated protein kinase kinase 3 (MKK3) and facilitation of MEKK3-MKK3-p38 module assembly.

In this study, we explored the precise mechanisms underlying the receptor for advanced glycation end products (RAGE)-mediated neuronal loss and behavioral dysfunction induced by hyperglycemia. We used immunoprecipitation (IP) and GST pull-down assays to assess the interaction between RAGE and mitogen-activated protein kinase kinase 3 (MKK3). Then, we investigated the effect of specific mutation of RAGE on plasticity at hippocampal synapses and behavioral deficits in db/db mice through electrophysiological recordings, morphological assays, and behavioral tests. We discovered that RAGE binds MKK3 and that this binding is required for assembly of the MEKK3-MKK3-p38 signaling module. Mechanistically, we found that activation of p38 mitogen-activated protein kinase (MAPK)/NF-κB signaling depends on mediation of the RAGE-MKK3 interaction by C-terminal RAGE (ctRAGE) amino acids (AAs) 2-5. We found that ctRAGE R2A-K3A-R4A-Q5A mutation suppressed neuronal damage, improved synaptic plasticity, and alleviated behavioral deficits in diabetic mice by disrupting the RAGE-MKK3 conjugation. High glucose induces direct binding of RAGE and MKK3 via ctRAGE AAs 2-5, which leads to assembly of the MEKK3-MKK3-p38 signaling module and subsequent activation of the p38MAPK/NF-κB pathway, and ultimately results in diabetic encephalopathy (DE).