Dynamic changes in lysosome-related pathways in APP/PS1 mice with aging.

Senile plaque, composed of amyloid ß protein (Aß) aggregates, is a critical pathological feature in Alzheimer's disease (AD), leading to cognitive dysfunction. However, how Aß aggregates exert age-dependent toxicity and temporal cognitive dysfunction in APP/PS1 mice remains incompletely understood. In this study, we investigated AD pathogenesis and dynamic alterations in lysosomal pathways within the hippocampus of age-gradient male mice using transcriptome sequencing, molecular biology assays, and histopathological analyses. We observed high levels of ß-amyloid precursor protein (APP) protein expression in the hippocampus at an early stage and age-dependent Aß deposition. Transcriptome sequencing revealed the enrichment of differential genes related to the lysosome pathway. Furthermore, the protein expression of ATP6V0d2 and CTSD associated with lysosomal functions exhibited dynamic changes with age, increasing in the early stage and decreasing later. Similar age-dependent patterns were observed for the endosome function, autophagy pathway, and SGK1/FOXO3a pathway. Nissl and Golgi staining in the hippocampal region showed age-dependent neuronal loss and synaptic damage, respectively. These findings clearly define the age-gradient changes in the autophagy-lysosome system, the endosome/lysosome system, and the SGK1/FOXO3a pathway in the hippocampus of APP/PS1 mice, providing new perspectives and clues for understanding the possible mechanisms of AD, especially the transition from compensatory to decompensated state.

Preventing postoperative cognitive dysfunction using anesthetic drugs in elderly patients undergoing noncardiac surgery: a systematic review and meta-analysis.

Postoperative cognitive dysfunction (POCD) is a common neurological system disorder in surgical patients. The choice of anesthetic can potentially reduce POCD. The authors performed this network meta-analysis to compare different anesthetic drugs in reducing the incidence of POCD for elderly people undergoing noncardiac surgery. We searched MEDLINE, EMBASE, the Cochrane Library, and the Web of Science for randomized controlled trials comparing the different anesthetic drugs for noncardiac surgery in elderly from inception until July, 2022. The protocol was registered on the PROSPERO database (CRD#42020183014). A total of 34 trials involving 4314 patients undergoing noncardiac surgery in elderly were included. The incidence of POCD for each anesthetic drug was placebo (27.7%), dexmedetomidine (12.9%), ketamine (15.2%), propofol (16.8%), fentanyl (23.9%), midazolam (11.3%), sufentanil (6.3%), sevoflurane (24.0%), and desflurane (28.3%). Pairwise and network meta-analysis showed dexmedetomidine was significantly reducing the incidence of POCD when compared with placebo. Network meta-analysis also suggested dexmedetomidine was significantly reducing the incidence of POCD when compared with sevoflurane. Sufentanil and dexmedetomidine ranked the first and second in reducing the incidence of POCD with the surface under the cumulative ranking curve value of 87.4 and 81.5%. Sufentanil and dexmedetomidine had the greatest possibility to reduce the incidence of POCD for elderly people undergoing noncardiac surgery.

Incident Stroke Events in Clinical Trials of Antihypertensive Drugs in Cardiovascular Disease Patients: A Network Meta-analysis of Randomized Controlled Trials.

Antihypertensive drugs are commonly used in cardiovascular diseases (CVD), less is known about the comparative effectiveness of different antihypertensive drugs on stroke events in CVD patients. We searched MEDLINE, EMBASE, the Cochrane Library, and the Web of Science for randomized controlled trails comparing the different antihypertensive drugs for stroke events in CVD patients from inception until November, 2022. Pairwise and network meta-analysis were performed to compare of different antihypertensive drugs for the incidence of stroke events in CVD patients. The protocol was registered on the PROSPERO database (CRD42022375038). 33 trials involving 141,217 CVD patients were included. The incidence of stroke in CVD patients for each antihypertensive drugs was placebo (3.0%), ACEI (2.4%), ARB (4.1%), CCB (1.8%), ß blocker (1.3%), and diuretic (3.6%). Antihypertensive drug was significantly reducing stroke events in CVD patients when compared with placebo (OR 0.82; 95% CI 0.75 to 0.89). Specifically, ACEI (OR 0.82; 95% CI, 0.69-0.97), ARB (OR 0.87; 95% CI, 0.77-0.98), CCB (OR 0.69; 95% CI, 0.54-to 0.87), and diuretic (OR 0.74; 95% CI, 0.57-0.95) were significantly reducing stroke events in CVD patients when compared with placebo. Network meta-analysis suggested CCB and diuretic ranked the first and second in reducing the incidence of stroke events in CVD patients with the SUCRA value of 90.9% and 73.8%. CCB and diuretic had the greatest possibility to reduce the incidence of stroke events in CVD patients, while, ACEI was the worst antihypertensive agents in reducing the incidence of stroke events in CVD patients.

USP10 deubiquitinates Tau, mediating its aggregation.

Normal Tau promotes the assembly and stabilization of microtubules, thus, maintaining axon transport. In Alzheimer's disease (AD), Tau aggregation causes it to lose these above-mentioned functions. However, the molecular mechanism leading to Tau aggregation in AD remains ambiguous. Here, we report that USP10, one of the important deubiquitinases (DUBs), is involved in Tau aggregation. We found that USP10 is upregulated in postmortem human AD and APP/PS1 mice brains, but not in P301S mice brains. Moreover, in primary neuronal cultures, Aß42 induces a dose-dependent USP10 upregulation, an increase in the levels of both total and phosphorylated Tau, as well as a markedly elevated Tau binding with USP10, that is accompanied by a significantly decreased Tau ubiquitination. In addition, overexpression of USP10 directly causes an increase in the levels of total and phosphorylated Tau, induces Tau aggregation, and delays in Tau degradation. Results from mass spectrometry, reciprocal immunoprecipitation, and immunofluorescence assays strongly prove Tau's interaction with USP10. This is further supported by the Tau307-326K and Tau341-378K peptides' competitive inhibition of Tau binding with USP10, attenuating Tau hyperphosphorylation and Tau deubiquitination. Together, our data strongly indicate that USP10 plays a critical role in mediating Tau aggregation via downregulating its ubiquitination and thus slowing down Tau turnover. Inhibition of USP10-Tau interaction might be therapeutically useful in the management of AD and related tauopathies.

Identification of a hippocampal lncRNA-regulating network in cognitive dysfunction caused by chronic cerebral hypoperfusion.

Cognitive dysfunction caused by chronic cerebral hypoperfusion is a common underlying cause of many cognition-related neurodegenerative diseases. The mechanisms of cognitive dysfunction caused by CCH are not clear. Long non-coding RNA is involved in synaptic plasticity and cognitive function, but whether lncRNA is involved in cognitive dysfunction caused by CCH has not yet been reported. In the present study, we identified the altered lncRNAs and mRNAs by deep RNA sequencing. A total of 128 mRNAs and 91 lncRNAs were up-regulated, and 108 mRNAs and 98 lncRNAs were down-regulated. Real-time reverse transcription-polymerase chain reaction verified the reliability of the lncRNA and mRNA sequencing. Gene Ontology and KEGG pathway analyses showed that differentially-expressed mRNAs were related to peptide antigen binding, the extracellular space, the monocarboxylic acid transport, and tryptophan metabolism. The co-expression analysis showed that 161 differentially expressed lncRNAs were correlated with DE mRNAs. By predicting the miRNA in which both DE lncRNAs and DE mRNAs bind together, we constructed a competitive endogenous RNA network. In this lncRNAs-miRNAs-mRNAs network, 559 lncRNA-miRNA-mRNA targeted pairs were identified, including 83 lncRNAs, 67 miRNAs, and 108 mRNAs. Through GO and KEGG pathway analysis, we further analyzed and predicted the regulatory function and potential mechanism of ceRNA network regulation. Our results are helpful for understanding the pathogenesis of cognitive dysfunction caused by CCH and provide direction for further research.

m6A RNA Methylation Regulators Contribute to Malignant Progression and Have Clinical Prognostic Impact in Gastric Cancer.

N6-methyladenosine (m6A) is the most common form of mRNA modification, and is dynamically regulated by the m6A RNA methylation regulators. However, little is known about m6A in gastric cancer. The aim of this work is to investigate the effects of m6A RNA methylation regulators in gastric cancer. Here, we found that most of the 13 main m6A RNA methylation regulators are higher expressed in 375 patients with gastric cancer. We identified two subgroups of gastric cancer (cluster1 and 2) by applying consensus clustering to m6A RNA methylation regulators. Compared with the cluster1 subgroup, the cluster2 subgroup correlates with a poorer prognosis, and most of the 13 main m6A RNA methylation regulators are higher expressed in cluster2. Moreover, the cancer-specific pathways are also significantly enriched in the cluster2 subgroup. This finding indicates that m6A RNA methylation regulators are closely associated with gastric cancer. Based on this finding, we derived a risk signature, using 3 m6A RNA methylation regulators (FTO, RBM15, ALKBH5), that is not only an independent prognostic marker but can also predict the clinicopathological features of gastric cancer. Moreover, FTO is higher expressed in high risk scores subtype in gastric cancer. Thus, this first finding provide us clues to understand epigenetic modification of RNA in gastric cancer.

Tripchlorolide May Improve Spatial Cognition Dysfunction and Synaptic Plasticity after Chronic Cerebral Hypoperfusion.

Chronic cerebral hypoperfusion (CCH) is a common pathophysiological mechanism that underlies cognitive decline and degenerative processes in dementia and other neurodegenerative diseases. Low cerebral blood flow (CBF) during CCH leads to disturbances in the homeostasis of hemodynamics and energy metabolism, which in turn results in oxidative stress, astroglia overactivation, and synaptic protein downregulation. These events contribute to synaptic plasticity and cognitive dysfunction after CCH. Tripchlorolide (TRC) is an herbal compound with potent neuroprotective effects. The potential of TRC to improve CCH-induced cognitive impairment has not yet been determined. In the current study, we employed behavioral techniques, electrophysiology, Western blotting, immunofluorescence, and Golgi staining to investigate the effect of TRC on spatial learning and memory impairment and on synaptic plasticity changes in rats after CCH. Our findings showed that TRC could rescue CCH-induced spatial learning and memory dysfunction and improve long-term potentiation (LTP) disorders. We also found that TRC could prevent CCH-induced reductions in N-methyl-D-aspartic acid receptor 2B, synapsin I, and postsynaptic density protein 95 levels. Moreover, TRC upregulated cAMP-response element binding protein, which is an important transcription factor for synaptic proteins. TRC also prevented the reduction in dendritic spine density that is caused by CCH. However, sham rats treated with TRC did not show any improvement in cognition. Because CCH causes disturbances in brain energy homeostasis, TRC therapy may resolve this instability by correcting a variety of cognitive-related signaling pathways. However, for the normal brain, TRC treatment led to neither disturbance nor improvement in neural plasticity. Additionally, this treatment neither impaired nor further improved cognition. In conclusion, we found that TRC can improve spatial learning and memory, enhance synaptic plasticity, upregulate the expression of some synaptic proteins, and increase the density of dendritic spines. Our findings suggest that TRC may be beneficial in the treatment of cognitive impairment induced by CCH.

Glucagon-Like Peptide-2 Receptor is Involved in Spatial Cognitive Dysfunction in Rats After Chronic Cerebral Hypoperfusion.

Chronic cerebral hypoperfusion (CCH) affects the aging population and especially patients with neurodegenerative diseases, such as Alzheimer's disease or Parkinson's disease. CCH is closely related to the cognitive dysfunction in these diseases. Glucagon-like peptide-2 receptor (GLP2R) mRNA and protein are highly expressed in the gut and in hippocampal neurons. This receptor is involved in the regulation of food intake and the control of energy balance and glucose homeostasis. The present study employed behavioral techniques, electrophysiology, western blotting, immunohistochemistry, quantitative real time polymerase chain reaction (qRT-PCR), and Golgi staining to investigate whether the expression of GLP2R changes after CCH and whether GLP2R is involved in cognitive impairment caused by CCH. Our findings show that CCH significantly decreased hippocampal GLP2R mRNA and protein levels. GLP2R upregulation could prevent CCH-induced cognitive impairment. It also improved the CCH-induced impairment of long-term potentiation and long-term depression. Additionally, GLP2R modulated after CCH the AKT-mTOR-p70S6K pathway in the hippocampus. Moreover, an upregulation of the GLP2R increased the neurogenesis in the dentate gyrus, neuronal activity, and density of dendritic spines and mushroom spines in hippocampal neurons. Our findings reveal the involvement of GLP2R via a modulation of the AKT-mTOR-p70S6K pathway in the mechanisms underlying CCH-induced impairments of spatial learning and memory. We suggest that the GLP2R and the AKT-mTOR-p70S6K pathway in the hippocampus are promising targets to treat cognition deficits in CCH.

Luteolin Could Improve Cognitive Dysfunction by Inhibiting Neuroinflammation.

Neuroinflammation and oxidative stress play an important role in cognition deficit following chronic cerebral hypoperfusion (CCH). Luteolin, a natural flavonoid found in many plants, is known for a variety of pharmacological activities, such as its anti-inflammatory, anti-allergy, urate, anti-tumor, antibacterial, and antiviral effects. To assess whether luteolin could prevent CCH-induced cognitive dysfunction, through its anti-inflammatory and anti-oxidative-stress effects, we used enzyme-linked immunosorbent assays, enzyme activity assays, behavioral methods, immunohistochemistry, and electrophysiology to detect neuroinflammation and oxidative stress, cognition alterations, and long-term potential (LTP), in a bilateral common carotid arteries ligation (2VO) rat model. We demonstrated that CCH increased tumor necrosis factor α (TNF-α), interleukin 1ß (IL-1ß), interleukin 6 (IL-6), and malondialdehyde (MDA), and decreased superoxide dismutase (SOD) and glutathione peroxidase (GPx) levels. Further, it caused microglia over-activation and astrogliosis, learning and short-term memory dysfunction, and an LTP deficit. Luteolin treatment reversed CCH-induced changes. Specifically, luteolin prevented the increase of TNF-α and IL-1ß, IL-6, and MDA, improved the activity of SOD and GPx, inhibited microglia over-activation and astrogliosis (particularly in the hippocampus and cortex), and ameliorated learning and short-term memory dysfunction, and LTP deficit. Thus, our study suggested that luteolin could be a preferable anti-inflammatory agent to protect cognitive function and synaptic plasticity following CCH. Luteolin could also be putative therapeutic candidate for other inflammation-related brain diseases.

Ginkgo biloba Extract EGb761 Attenuates Hyperhomocysteinemia-induced AD Like Tau Hyperphosphorylation and Cognitive Impairment in Rats.

BACKGROUND: Ginkgo biloba extract EGb761 has shown the neuroprotective effects on Alzheimer's disease (AD) through the protection against the Aß-induced neurotoxicity. However, it is not completedly clear whether EGb761 attenuates tau hyperphosphorylation, another of the most prominent mechanisms underlying the pathology of AD. METHODS: we employed hyperhomocysteinemia (HHcy) to mimic AD like pathological alterations and memory deficits in rats as model, and injected EGb761 with or after HHcy injection as prevention and treatment, injected saline as control. We measured the status of oxidative damage and spatial and learning memory in rats. Then we detected the level of memory-related proteins, tau phosphorylation and the level and activity of tau kinase (GSK-3ß) and phosphatase (PP2A) by Western blotting and Immunohistochemistry. RESULTS: We found that EGb761 could significantly antagonize HHcy-induced oxidative damage, recover PP2Ac and GSK3ß activities deregulated by HHcy. Furthermore, tau was hyperphosphorylated at Thr231, Ser262, Ser396, and Ser404, most common PP2Ac and GSK3ß targeted sites in the hippocampus and prefrontal cortex of HHcy rats, whereas EGb761 recovered the tau phosphorylation at those sites. Behavioral tests revealed that EGb761 rescued HHcy-induced spatial reference memory deficit and upregulated the expression of synapse-associated protein PSD95 and synapsin-1. CONCLUSION: EGb761 might be a promising drug to treat AD through its anti-oxidative activity and decreasing tau hyperphosphorylation besides the protection against the Aß-induced neurotoxicity.

miR-132 Down-regulates Methyl CpG Binding Protein 2 (MeCP2) During Cognitive Dysfunction Following Chronic Cerebral Hypoperfusion.

BACKGROUND: Chronic Cerebral Hypoperfusion (CCH) is an important vascular risk factor for vascular-related dementia cognitive impairment and there are no effective measures for the prevention and treatment of cognitive deficit by CCH and the underlying mechanisms are still poorly understood. Methyl cytidine-phosphate-guanosine (CpG) binding protein 2 (MeCP2), regulated by microRNA 132 (miR-132), is as a transcriptional repressor in high concentrations in the brain, which regulates the expression of synaptic proteins and neuroplasticity, and may be involved in the cognitive deficit after CCH. But no relevant studies have been reported. The aim of this study is to investigate the status of MeCP2 expression after CCH and explore whether MeCP2 changes is associated with cognitive deficits after CCH. METHODS: We investigated MeCP2 expression after CCH using Western blotting, quantitative Real- Time Polymerase Chain Reaction (qRT-PCR) analysis and immunofluorescence technique in a rat model of permanent bilateral common carotid artery occlusion (2VO) to mimic CCH. We determined the effect of MeCP2 expression on cognitive deficits and neuroplasticity after CCH through lenti-virus stereotaxic injection, the Morris water maze and electrophysiology. RESULTS: CCH contributed to the down-regulation of MeCP2 and mecp2 expressions in the hippocampus and cortex. miR-132 up-regulated by 2VO was distinctly negatively correlated with MeCP2 down-regulation by miR-132 inhibitors. MeCP2 over-expression improved learning and memory impairment, as well as neuroplasticity after 2VO. Brain-Derived Neurotrophic Factor (BDNF) and the activities of its downstream pathways moleculars, tropomyosin receptor kinase B (TrkB) and the cAMP Response Element Binding Protein (CREB) were down-regulated by 2VO and rescued by MeCP2 over-expression. CONCLUSION: Our study found that miR-132 may participate in the down-regulation of MeCP2 after CCH and MeCP2 down-regulation was possibly involved in the cognitive deficit through regulation of BDNF and its downstream pathways after 2VO. Our findings expounded the underlying mechanisms of cognition deficit after CCH, which contributes to understanding the mechanisms of vascular dementia.

Long noncoding RNA MEG3 activation of p53 mediates ischemic neuronal death in stroke.

Maternally expressed gene 3 (MEG3) is suggested to function as a long non-coding RNA (lncRNA) and to play roles in various human cancers. However, the functional properties of MEG3 in ischemic stroke remain unknown. Here, we report that expression of MEG3 is upregulated following ischemia in adult mice. Moreover, cerebral ischemia recruits p53 into the MEG3 complex in ischemic tissues. MEG3 directly binds with the p53 DNA binding domain (DBD) consisting of amino acids 271-282 (p53-DBD271-282), which stimulates p53-mediated transactivation and mediates ischemic neuronal death. Administration of the membrane-permeable peptide inhibitor Tat-p53-DBD271-282 uncouples p53 from MEG3 in vivo and protects against cerebral ischemic insults in vitro and in vivo. Our data demonstrate that MEG3 functions as a cell death promoter in ischemia and physically and functionally interacts with p53 to mediate ischemic damage. Intervention in the MEG3-p53 interaction presents a new target for the therapeutic treatment of ischemic insults.

Novel multipotent AChEI-CCB attenuates hyperhomocysteinemia-induced memory deficits and Neuropathologies in rats.

Alzheimer's disease (AD) has multiple etiopathogenic factors, yet the definitive cause remains unclear and the therapeutic strategies have been elusive. Combination therapy, as one of the promising treatments, has been studied for years and may exert synergistic beneficial effects on AD through polytherapeutic targets. In this study, we tested the effects of a synthesized juxtaposition (named SCR1693) composed of an acetylcholinesterase inhibitor (AChEI) and a calcium channel blocker (CCB) on the hyperhomocysteinemia (HHcy)-induced AD rat model, and found that SCR1693 remarkably improved the HHcy-induced memory deficits and preserved dendrite morphologies as well as spine density by upregulating synapse-associated proteins PSD95 and synapsin-1. In addition, SCR1693 attenuated HHcy-induced tau hyperphosphorylation at multiple AD-associated sites by regulating the activity of protein phosphatase-2A and glycogen synthase kinase-3ß. Furthermore, SCR1693 was more effective than individual administration of both donepezil and nilvadipine which were used as AChEI and CCB, respectively, in the clinical practice. In conclusion, our data suggest that the polytherapeutic targeting juxtaposition SCR1693 (AChEI-CCB) is a promising therapeutic candidate for AD.

Losartan-induced hypotension leads to tau hyperphosphorylation and memory deficit.

Recent studies have reported a correlation between dementia and low blood pressure. How hypotension is associated with the increased risk of Alzheimer's disease (AD) remains unclear. Here we show that one month treatment of losartan, an angiotensin II type 1 (AT1) receptor antagonist, causes chronic and sustained hypotension, along with oxidative stress in adult male Sprague-Dawley rats. Furthermore, we show that losartan treatment increases the level of inactivated protein phosphatase 2A (PP2A) and the hyperphosphorylation of tau at Ser 199 and Ser 396. Rats treated with losartan present memory deficits and decreases in spine-density. These findings suggest that losartan-induced hypotension may increase the risk of AD-like pathological alteration and behavioral impairment through oxidative stress which leads to tau hyperphosphorylation and loss of dendritic spines.