N-acetyltransferase 10 mediates cognitive dysfunction through the acetylation of GABABR1 mRNA in sepsis-associated encephalopathy.
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ABSTRACT: Sepsis-associated encephalopathy (SAE) is a critical neurological complication of sepsis and represents a crucial factor contributing to high mortality and adverse prognosis in septic patients. This study explore the influence of NAT10-mediated mRNA acetylation on SAE and the mechanisms underlying cognitive dysfunction in this context. SAE was induced in C57BL/6 J male mice through cecal ligation and puncture (CLP) surgery. In vivo, we observed a significant increase in NAT10 expression in the excitatory neurons of the hippocampal the dentate gyrus (DG) in CLP mice, and this change was accompanied by a trend toward an increase in mRNA acetylation. Specific knockout of Nat10 in neurons led to an improvement in cognitive dysfunction in septic mice. Proteomic analysis and RNA immunoprecipitation and real-time quantitative polymerase chain reaction (RIP-qPCR) revealed GABABR1 as a crucial downstream target of NAT10. Nat10 deletion reduced GABABR1 expression, subsequently weakening inhibitory postsynaptic currents in hippocampal DG neurons. Additionally, RNA sequencing (RNA-seq) revealed an increase in hippocampal inflammation post-CLP, characterized by the excessive activation of microglia and the release of inflammatory mediators. These factors were linked to the increased NAT10 expression in neurons. Treatment with PLX3397, a microglia depleting agent, resulted in a reduction in NAT10 and GABABR1 expression in neurons, which correlated with improvements in cognitive dysfunction induced by SAE. Taken together, our findings revealed that after CLP, NAT10 in neurons of the hippocampal DG region promotes GABABR1 expression by acetylating its mRNA, leading to cognitive dysfunction. These findings provide new insights into the molecular pathogenesis of SAE and suggest potential therapeutic targets for addressing cognitive deficits in septic patients.
Project description:Sepsis-associated encephalopathy (SAE) is an acute cerebral dysfunction caused by sepsis. Neuroinflammation induced by sepsis is considered a potential mechanism of SAE; however, very little is known about the role of the meningeal lymphatic system in SAE. The aged mice with SAE showed a significant decrease in the drainage of OVA-647 into the dCLNs and the coverage of the Lyve-1 in the meningeal lymphatic, indicating that sepsis impaired meningeal lymphatic drainage and morphology. The meningeal lymphatic function of aged mice was more vulnerable to sepsis in comparison to young mice. Sepsis also decreased the protein levels of caspase-3 and PSD95, which was accompanied by reductions in the activity of hippocampal neurons. Microglia were significantly activated in the hippocampus of SAE mice, which was accompanied by an increase in neuroinflammation, as indicated by increases in interleukin-1 beta, interleukin-6 and Iba1 expression. Cognitive function was impaired in aged mice with SAE. However, the injection of AAV1-VEGF-C significantly increased coverage in the lymphatic system and tracer dye uptake in dCLNs, suggesting that AAV1-VEGF-C promotes meningeal lymphangiogenesis and drainage. Furthermore, AAV1-VEGF-C reduced microglial activation and neuroinflammation and improved cognitive dysfunction. Improvement of meningeal lymphatics also reduced sepsis-induced expression of disease-associated genes in aged mice. Pre-existing lymphatic dysfunction by ligating bilateral dCLNs aggravated sepsis-induced neuroinflammation and cognitive impairment.
Project description:Sepsis-associated encephalopathy (SAE) is a major and frequent complication in patients with sepsis resulting in delirium and premature death. Sepsis survivors commonly suffer from long-term cognitive impairment causing immense burden on patients, caregivers, and economic health systems. Underlying pathophysiology of SAE related cognitive deficits is largely unresolved, Thus treatment options are missing. We report that experimental polymicrobial sepsis in mice induces synaptic pathology in the central nervous system underlying defective long-term potentiation and cognitive dysfunction. Analysis of differentially expressed genes revealed severely affected downregulation of genes related to neuronal and synaptic signaling in the brain, e.g. of the activity-regulated cytoskeleton-associated protein (Arc ), of the transcription-regulatory EGR family, and of the dual-specificity phosphatase 6 (Dusp6). On the protein level, ARC expression and mitogen-activated protein (MAP) kinase signaling in the brain was disturbed during SAE. For targeted rescue of dysregulated synaptic signaling and plasticity, we overexpressed ARC in the hippocampus by bilateral in-vivo stereotactic microinjection of an adeno-associated virus containing a neuron-specific plasmid of the Arc transgene. Hereby, defective synaptic plasticity and signaling in the hippocampus were restored and memory function improved. Accordingly, synaptic plasticity, neuronal spine pathology, and memory dysfunction also improved when post-septic mice were subjected to enriched environment demonstrating the potential for activity-induced recovery of long-term cognitive dysfunction. Together, we identified synaptic pathology of neurocognitive dysfunction after severe systemic infection and provide a proof-of-concept approach to interfere with SAE pathomechanisms leading to cognitive improvement.
Project description:Septic cardiac dysfunction is a key feature of severe sepsis and septic shock, contributing to multiorgan dysfunction syndrome and death. It has been established that persistent beta adrenergic stimulation is detrimental in sepsis, and that specific beta 1 blockade mitigates excessive systemic inflammation and improves myocardial function. The aim of this study was to investigate the effects of specific beta 1 blocker esmolol on septic mouse myocardium by genomic and proteomic techniques. We also evaluated survival of septic mice and systemic inflammation under esmolol treatment. C57BL/6 mice were rendered septic by 2 models: cecal ligature and perforation (CLP) and intraperitoneal injection of lipopolysaccharides (LPS). Effects of esmolol on myocardium were assessed by microarray technique. Total RNA were isolated and purified from a 30mg sample of the heart of 6 groups of 8 animals, depending on the sepsis model and the treatment. The labeled cDNA from the treated animals were hybridized against the labeled cDNA from the untreated animals with 2 dye-swaps done for each sepsis model.
Project description:Sepsis is a complex syndrome characterized by organ dysfunction triggered by dysregulated host response to infection, and the kidney is the most commonly injured organ. To model septic-induced AKI in animal, a well-established mouse model induced by caecal ligation and puncture (CLP) was established.
Project description:Sepsis is a complex syndrome characterized by organ dysfunction triggered by dysregulated host response to infection, and the kidney is the most commonly injured organ. To model septic-induced AKI in animal, a well-established mouse model induced by caecal ligation and puncture (CLP) was established.
Project description:Sepsis induces systemic stress by augmenting inflammatory and pro-coagulant responses resulting in microvascular dysfunction and end organ failure, events modulated by the Protein C pathway. MicroRNAs (miRNAs) are small non-coding RNAs involved in post-transcriptional regulation of gene transcription yet their role in sepsis remains poorly defined. We hypothesized that aPC selectively alters the expression of specific miRNAs implicated in protection of hepatic function during septic shock. Male Sprague-Dawley rats underwent sham surgery or cecal ligation and puncture (CLP). Twenty-four later, animals were randomized and treated with aPC (1mg/kg) or vehicle (0.9% (w/v) saline) via an indwelling venous catheter at 12 hour intervals for 24 hours. Gene array was performed on hepatic RNA to determine miRNA expression, and predicted mRNA targets determined using a bioinformatics approach. Of 351 rat miRNAs examined by microarray hybridization, 17 were highly expressed during sepsis and restored to basal levels after aPC treatment. In silico analysis identified 9 miRNAs significantly regulating target genes of the focal adhesion pathway. These data suggest aPC treatment coordinates beneficial cytoprotective effects during sepsis by modulating miRNA expression. While translational effects remain to be fully elucidated in a clinical setting, we demonstrate herein the potential experimental and computational benefits for use of microRNA analysis in sepsis. 12 samples were analyzed. Microarray experiments were performed, in which liver tissue was harvested from variuous groups (Sham+Vehicle, Sham+aPC, CLP+Vehicle, CLP+aPC; n=3/group) and pooled.
Project description:To investigate the role of TSPO in the sequelae of sepsis induced by cecal ligation and puncture (CLP), hippocampal gene expression changes after CLP surgery were examined in wild-type and TSPO KO mice
Project description:Mutations in the JMJD3 (KDM6B) chromatin regulator are causally associated with autism spectrum disorder and syndromic intellectual disability, but the neurodevelopmental roles of this histone 3 lysine 27 (H3K27) demethylase are poorly understood. Neural stem cells (NSCs) in the hippocampal dentate gyrus (DG) generate new granule neurons throughout life, and deficits in DG neurogenesis are associated with cognitive and behavioral problems. Here we show that Jmjd3 is required for the establishment of adult neurogenesis in the mouse DG. Conditional deletion of Jmjd3 in embryonic DG precursors results in an adult hippocampus that is essentially devoid of NSCs. While early postnatal mice with Jmjd3-deletion have near normal numbers of DG NSCs, at later stages, Jmjd3-deleted NSCs fail to propagate normally. In addition to the loss of NSCs during postnatal development, neurogenesis from Jmjd3-deleted NSCs is impaired, corresponding to defective neurogenic gene expression. Without Jmjd3, NeuroD2 and Bcl11b(Ctip2) are not properly expressed and exhibit increased levels of H3K27me3, underscoring the role of Jmjd3 in the regulation of transcription for neuronal differentiation. Thus, these data indicate that Jmjd3 plays dual roles in postnatal DG neurogenesis, being critical for the establishment of the NSC pool as well as the differentiation of young DG granule neurons. More broadly, our results suggest a neurodevelopmental link between JMJD3 mutations and hippocampal dysfunction, providing new insights into how mutations in chromatin regulators may contribute to learning disorders.
Project description:Dysregulated cardiac function after sepsis is common in intensive care unit (ICU) and known to predict poor long-term outcome and increase mortality. Effective therapeutic strategies are largely lacking. Moreover, the pathological feature and the molecular mechanism underlying cardiac dysfunction induced by sepsis remain unclear. Here, by performing echocardiograms on rodents after induction of polymicrobial sepsis with cecum ligation and puncture (CLP), we assessed the temporal dynamics of left ventricular ejection fraction (LVEF) and a serial of hemodynamics parameters on animals at different time point after CLP. Intriguingly, the mean LVEF is comparable in mice induced by CLP and sham, whereas survivors post CLP had stable LVEF and non-survivors had markedly fluctuated LVEF at early phase of CLP induction, suggesting LVEF away from normal range is highly associated with mortality. Consistent with clinical observations of depressed, preserved or hyperdynamic LVEF in septic patients from data compiled using our ICU cohort and from other studies, CLP-induced mice fall into three groups based on LVEF measured at 24 hours after surgery: high LVEF (HEF, LVEF>=90%), low LVEF (LEF, LVEF<65%), and normal LVEF (NEF, 65%=<LVEF<90%). We performed genome-wide transcriptomic and proteomic profiling on left ventricle samples collected from three CLP groups and sham mice. By implementing pathway analysis, gene set enrichment and coexpression network analysis, we identified jointly and distinctively changed genes, proteins and biologically-essential processes and pathways in three CLP groups with different LVEF. Notably, transmission electron microscopy examination shows remarkable mitochondrial and sarcomere defects in three CLP groups with different phenotypes associated with LVEF variances. Together, this study systematically characterizes the molecular, morphological, and functional alterations in CLP-induced cardiac injury, serving as a framework for future research into pathology and molecular mechanism of sepsis-induced cardiomyopathy.
Project description:Lymphocytes are adversely affected during sepsis. Some CD4+ splenocytes undergo apoptosis while others become Th2 polarized. The molecular determinants of these phenotypic changes are not known. Here we compare the transcriptional response of septic CD4 splenocytes to CD4 splenocytes from sham-manipulated animals 6h after sepsis and identify an early transcriptional component to the septic CD4+ splenocyte phenotype. CD4+ splenocytes were isolated 6h after the surgical induction of sepsis for RNA extraction and hybridization on Affymetrix microarrays. We sought to obtain a homogeneous cell population in order to reduce any effects of cellular heterogeneity on expression profiles. To that end, immunomagnetic negative selection was used to enrich CD4+ splenocyte populations to ~91%. (n=5 biological replicates each CLP and sham)