Unraveling the Mechanism of Immunity and Inflammation Related to Molecular Signatures Crosstalk Among Obesity, T2D, and AD: Insights From Bioinformatics Approaches.

Individuals with type 2 diabetes (T2D) and obesity have a higher risk of developing Alzheimer disease (AD), and increasing evidence indicates a link between impaired immune signaling pathways and the development of AD. However, the shared cellular mechanisms and molecular signatures among these 3 diseases remain unknown. The purpose of this study was to uncover similar molecular markers and pathways involved in obesity, T2D, and AD using bioinformatics and a network biology approach. First, we investigated the 3 RNA sequencing (RNA-seq) gene expression data sets and determined 224 commonly shared differentially expressed genes (DEGs) from obesity, T2D, and AD diseases. Gene ontology and pathway enrichment analyses revealed that mutual DEGs were mainly enriched with immune and inflammatory signaling pathways. In addition, we constructed a protein-protein interactions network for finding hub genes, which have not previously been identified as playing a critical role in these 3 diseases. Furthermore, the transcriptional factors and protein kinases regulating commonly shared DEGs among obesity, T2D, and AD were also identified. Finally, we suggested potential drug candidates as possible therapeutic interventions for 3 diseases. The results of this bioinformatics analysis provided a new understanding of the potential links between obesity, T2D, and AD pathologies.

Exosomal LINC00355 promotes the malignant progression of gastric cancer through histone deacetylase HDAC3-mediated TP53INP1 transcriptional inhibition.

AIMS: Exosomes are a subpopulation of extracellular vesicles (EV) derived from multivesicular body (MVB) that transmit various cellular molecular constituents, including long noncoding RNAs (lncRNAs), to promote intercellular communication. Our aim was to investigate the function and mechanism of exosomal LINC00355 in gastric cancer cells. MAIN METHODS: Exosomal levels of LINC00355 in GC patients and healthy controls were measured by RT-qPCR. The effects of exosomal LINC00355 on GC cell viability, proliferation, migration and invasion were evaluated by CCK8, colony formation, Transwell and wound healing assays. The expression levels of Ki67 in xenograft tumor tissues were confirmed by immunohistochemistry assay, and apoptosis was analyzed by TUNEL apoptosis assay. Western blotting was used to monitor protein expression. RNA immunoprecipitation and RNA pulldown were performed to detect the interaction between LINC00355 and HDAC3. Chromatin immunoprecipitation was used to assess the interaction of HDAC3 with the TP53INP1 promoter. KEY FINDINGS: Exosomal LINC00355 levels were higher in plasma from gastric cancer patients than in plasma from healthy volunteers. Exosomal LINC00355 promoted the proliferation, migration and invasion of gastric cancer cell lines. RNA sequence analysis demonstrated that LINC00355 knockdown downregulated histone deacetylase HDAC3 and upregulated TP53INP1. Mechanistic investigation indicated that exosomal LINC00355 interacted with HDAC3 to suppress TP53INP1 transcription, which promoted epithelial-mesenchymal transition (EMT). SIGNIFICANCE: Exosomal LINC00355 plays a pivotal role in regulating EMT to induce the malignant progression of GC. Exosomal LINC00355 could be a promising biomarker in the early diagnosis and prognosis of GC.

EphA3 deficiency in the hypothalamus promotes high-fat diet-induced obesity in mice.

Erythropoietin-producing hepatocellular carcinoma A3 (EphA3) is a member of the largest subfamily of tyrosine kinase receptors-Eph receptors. Previous studies have shown that EphA3 is associated with tissue development. Recently, we have found that the expression of EphA3 is elevated in the hypothalamus of mice with diet-induced obesity (DIO). However, the role of EphA3 in hypothalamic-controlled energy metabolism remains unclear. In the current study, we demonstrated that the deletion of EphA3 in the hypothalamus by CRISPR/Cas9-mediated gene editing promotes obesity in male mice with high-fat diet feeding rather than those with normal chow diet feeding. Moreover, the deletion of hypothalamic EphA3 promotes high-fat DIO by increasing food intake and reducing energy expenditure. Knockdown of EphA3 leads to smaller intracellular vesicles in GT1-7 cells. The current study reveals that hypothalamic EphA3 plays important roles in promoting DIO.

miR-874-3p mitigates cisplatin resistance through modulating NF-κB/inhibitor of apoptosis protein signaling pathway in epithelial ovarian cancer cells.

The resistance to cisplatin, the most common platinum chemotherapy drug, may confine the efficacy of treatment in epithelial ovarian cancer patients. Aberrant expression of inhibitor of apoptosis proteins set the stage for resistance to cisplatin in EOC; besides, chemosensitivity in EOC can be chalked up to dysregulation of specific miRNAs. Herein, we investigated whether there is a potential correlation between miR-874-3p and the X-chromosome-linked inhibitor of apoptosis, a member of the IAP protein family in cisplatin-resistant EOC cells. The lower expression of miR-874-3p was found in SKOV3-DDP cells; it was also in association with cisplatin-resistance in EOC cells. XIAP was found to contribute to developing platinum resistance and is an authentic target for miR-874-3p in SKOV3-DDP cells. Consistently, restoration of miR-874-3p expression reversed cisplatin resistance in such cells by modulating XIAP and NF-κB/Survivin signaling pathway. Besides, siRNA knock down of XIAP in SKOV3-DDP cells had an anti-migratory effect like those with miR-874 overexpression. Importantly, the enforced expression of XIAP rescued SKOV3-DDP cells from the cytotoxic effects of miR-874-3p. Finally, miR-874-3p sensitized EOC cells to cisplatin-induced apoptosis, at least in part, through targeting XIAP. The cytotoxic effects of miR-874-3p can be attributed to the targeting XIAP in cisplatin-resistant EOC cells. We believe that the combination of cisplatin with miR-874-3p may make a potential strategy to reverse cisplatin resistance.

NGPF2 triggers synaptic scaling up through ALK-LIMK-cofilin-mediated mechanisms.

Synaptic scaling is an extensively studied form of homeostatic plasticity critically involved in various brain functions. Although it is accepted that synaptic scaling is expressed through the postsynaptic accumulation of AMPA receptors (AMPARs), the induction mechanism remains elusive. In this study, we show that TTX treatment induces rapid but transient release of the neurite growth-promoting factor 2 (NGPF2), and this release is necessary and sufficient for TTX-induced scaling up. In addition, we show that inhibition of the anaplastic lymphoma kinase (ALK)-LIMK-cofilin signaling pathway blocks TTX- and NGPF2-induced synaptic scaling up. Furthermore, we show that TTX-induced release of NGPF2 is protein synthesis dependent and requires fragile X mental retardation protein 1 (FMRP1). These results indicate that activity blockade induces NGPF2 synthesis and release to trigger synaptic scaling up through LIMK-cofilin-dependent actin reorganization, spine enlargement, and stabilization of AMPARs at the synapse.

Reversal of prolonged obesity-associated cerebrovascular dysfunction by inhibiting microglial Tak1.

Prolonged obesity is associated with cerebrovascular dysfunction; however, the underlying mechanisms remain largely unclear. In the present study, using a prolonged obesity mouse model that suffers from basilar artery (BA) abnormalities, we find that microglial transforming growth factor ß-activated kinase 1 (Tak1) is over-activated in the brainstem. Both pharmacological inhibition primarily in the brainstem and genetic microglia-selective deletion of Tak1 ameliorated BA vascular dysfunction. Conversely, microglia-specific activation of Tak1 in the brainstem was sufficient to cause an impairment in BA function in chow-fed mice. Mechanistically, Tak1 activation leads to increased interleukin-18 (IL-18) production, whereas blockade of IL-18 receptor in the brain helped protect against cerebrovascular dysfunction despite prolonged obesity. Microglia-selective deletion of Tak1 also protects against ischemic stroke in prolonged obesity. Taken together, these findings provide evidence that microglial Tak1 in the brain, and particularly the brainstem, contributes to the pathogenesis of obesity-associated cerebrovascular dysfunction.

Regulation of hippocampal long term depression by Neuroligin 1.

Neuroligins (NLGs) are postsynaptic adhesion molecules known to play essential roles in synapse development and maturation, but their effects on synaptic plasticity at mature synapses remain unclear. In this study, we investigate the involvement of NLG1 in hippocampal long-term depression (LTD), a key form of long lasting synaptic plasticity, critical for memory formation and brain disorders, by using mice deficient in the expression of NLG1. We find that although NLG1 homozygous (NLG1-/-) mice show no impairments in either NMDA receptor- (NMDAR-LTD) or metabotropic glutamate receptor-dependent LTD (mGluR-LTD), the heterozygous (NLG1+/-) mice are significantly altered in both forms of LTD characterized by the absence of NMDAR-LTD but enhanced mGluR-LTD. Accordingly, the NLG1+/-, but not the NLG1-/- mice are altered in synaptic proteins, including PSD95, GluA2 and phosphorylated GluA1 at serine 845, all of which are involved in the expression of LTD. The NLG1+/- mice also exhibit autistic-like behaviors including increased grooming and impaired recognition memory. We further show that the expression of NLG3, a close family member of NLG1, is elevated in the NLG1-/-, but not in NLG1+/- mice, suggesting that the lack of LTD deficits in the NLG1-/- mice might be due to the increased NLG3. Our results reveal a gene dosage dependent role for NLG1 in the regulation of LTD and suggest that moderate changes in NLG1 protein level may be sufficient to cause synaptic and behavior deficits in brain disorders where copy number variants and hemizygosity of gene mutations are common.

Publisher Correction: The C-terminal tails of endogenous GluA1 and GluA2 differentially contribute to hippocampal synaptic plasticity and learning.

In the version of this article initially published, the wrong version of Supplementary Fig. 10 was posted and the city for affiliation 4, the Co-innovation Center of Neuroregeneration, Nantong University, was given as Nanjing instead of Nantong. The errors have been corrected in the HTML and PDF versions of the article.

The C-terminal tails of endogenous GluA1 and GluA2 differentially contribute to hippocampal synaptic plasticity and learning.

Long-term potentiation (LTP) and depression (LTD) at glutamatergic synapses are intensively investigated processes for understanding the synaptic basis for learning and memory, but the underlying molecular mechanisms remain poorly understood. We have made three mouse lines where the C-terminal domains (CTDs) of endogenous AMPA receptors (AMPARs), the principal mediators of fast excitatory synaptic transmission, are specifically exchanged. These mice display profound deficits in synaptic plasticity without any effects on basal synaptic transmission. Our study reveals that the CTDs of GluA1 and GluA2, the key subunits of AMPARs, are necessary and sufficient to drive NMDA receptor-dependent LTP and LTD, respectively. In addition, these domains exert differential effects on spatial and contextual learning and memory. These results establish dominant roles of AMPARs in governing bidirectional synaptic and behavioral plasticity in the CNS.

Cdk7 Is Required for Activity-Dependent Neuronal Gene Expression, Long-Lasting Synaptic Plasticity and Long-Term Memory.

In the brain, de novo gene expression driven by learning-associated neuronal activities is critical for the formation of long-term memories. However, the signaling machinery mediating neuronal activity-induced gene expression, especially the rapid transcription of immediate-early genes (IEGs) remains unclear. Cyclin-dependent kinases (Cdks) are a family of serine/threonine kinases that have been firmly established as key regulators of transcription processes underling coordinated cell cycle entry and sequential progression in nearly all types of proliferative cells. Cdk7 is a subunit of transcriptional initiation factor II-H (TFIIH) and the only known Cdk-activating kinase (CAK) in metazoans. Recent studies using a novel Cdk7 specific covalent inhibitor, THZ1, revealed important roles of Cdk7 in transcription regulation in cancer cells. However, whether Cdk7 plays a role in the regulation of transcription in neurons remains unknown. In this study, we present evidence demonstrating that, in post-mitotic neurons, Cdk7 activity is positively correlated with neuronal activities in cultured primary neurons, acute hippocampal slices and in the brain. Cdk7 inhibition by THZ1 significantly suppressed mRNA levels of IEGs, selectively impaired long-lasting synaptic plasticity induced by 4 trains of high frequency stimulation (HFS) and prevented the formation of long-term memories.

Fbxl4 Serves as a Clock Output Molecule that Regulates Sleep through Promotion of Rhythmic Degradation of the GABAA Receptor.

The timing of sleep is tightly governed by the circadian clock, which contains a negative transcriptional feedback loop and synchronizes the physiology and behavior of most animals to daily environmental oscillations. However, how the circadian clock determines the timing of sleep is largely unclear. In vertebrates and invertebrates, the status of sleep and wakefulness is modulated by the electrical activity of pacemaker neurons that are circadian regulated and suppressed by inhibitory GABAergic inputs. Here, we showed that Drosophila GABAA receptors undergo rhythmic degradation in arousal-promoting large ventral lateral neurons (lLNvs) and their expression level in lLNvs displays a daily oscillation. We also demonstrated that the E3 ligase Fbxl4 promotes GABAA receptor ubiquitination and degradation and revealed that the transcription of fbxl4 in lLNvs is CLOCK dependent. Finally, we demonstrated that Fbxl4 regulates the timing of sleep through rhythmically reducing GABA sensitivity to modulate the excitability of lLNvs. Our study uncovered a critical molecular linkage between the circadian clock and the electrical activity of pacemaker neurons and demonstrated that CLOCK-dependent Fbxl4 expression rhythmically downregulates GABAA receptor level to increase the activity of pacemaker neurons and promote wakefulness.

Mutations of PQBP1 in Renpenning syndrome promote ubiquitin-mediated degradation of FMRP and cause synaptic dysfunction.

Renpenning syndrome is a group of X-linked intellectual disability syndromes caused by mutations in human polyglutamine-binding protein 1 (PQBP1) gene. Little is known about the molecular pathogenesis of the various mutations that cause the notable variability in patients. In this study, we examine the cellular and synaptic functions of the most common mutations found in the patients: c.461_462delAG, c.459_462delAGAG and c.463_464dupAG in an AG hexamer in PQBP1 exon 4. We discovered that PQBP1 c.459_462delAGAG and c.463_464dupAG mutations encode a new C-terminal epitope that preferentially binds non-phosphorylated fragile X mental retardation protein (FMRP) and promotes its ubiquitin-mediated degradation. Impairment of FMRP function up-regulates its targets such as MAP1B, and disrupts FMRP-dependent synaptic scaling in primary cultured neurons. In Drosophila neuromuscular junction model, PQBP1 c.463_464dupAG transgenic flies showed remarkable defects of synaptic over-growth, which can be rescued by exogenously expressing dFMRP. Our data strongly support a gain-of-function pathogenic mechanism of PQBP1 c.459_462delAGAG and c.463_464dupAG mutations, and suggest that therapeutic strategies to restore FMRP function may be beneficial for those patients.

p21-activated kinase 1 restricts tonic endocannabinoid signaling in the hippocampus.

PAK1 inhibitors are known to markedly improve social and cognitive function in several animal models of brain disorders, including autism, but the underlying mechanisms remain elusive. We show here that disruption of PAK1 in mice suppresses inhibitory neurotransmission through an increase in tonic, but not phasic, secretion of endocannabinoids (eCB). Consistently, we found elevated levels of anandamide (AEA), but not 2-arachidonoylglycerol (2-AG) following PAK1 disruption. This increased tonic AEA signaling is mediated by reduced cyclooxygenase-2 (COX-2), and COX-2 inhibitors recapitulate the effect of PAK1 deletion on GABAergic transmission in a CB1 receptor-dependent manner. These results establish a novel signaling process whereby PAK1 upregulates COX-2, reduces AEA and restricts tonic eCB-mediated processes. Because PAK1 and eCB are both critically involved in many other organ systems in addition to the brain, our findings may provide a unified mechanism by which PAK1 regulates these systems and their dysfunctions including cancers, inflammations and allergies.

Neuroligin 1 regulates spines and synaptic plasticity via LIMK1/cofilin-mediated actin reorganization.

Neuroligin (NLG) 1 is important for synapse development and function, but the underlying mechanisms remain unclear. It is known that at least some aspects of NLG1 function are independent of the presynaptic neurexin, suggesting that the C-terminal domain (CTD) of NLG1 may be sufficient for synaptic regulation. In addition, NLG1 is subjected to activity-dependent proteolytic cleavage, generating a cytosolic CTD fragment, but the significance of this process remains unknown. In this study, we show that the CTD of NLG1 is sufficient to (a) enhance spine and synapse number, (b) modulate synaptic plasticity, and (c) exert these effects via its interaction with spine-associated Rap guanosine triphosphatase-activating protein and subsequent activation of LIM-domain protein kinase 1/cofilin-mediated actin reorganization. Our results provide a novel postsynaptic mechanism by which NLG1 regulates synapse development and function.

Primary epithelioid hemangioendothelioma of the bladder: case report and review of the literature.

Epithelioid hemangioendothelioma (EHE) is a rare tumor of the urinary system. Only three cases of EHE of the bladder have been reported to date, and the biological properties of the tumor in this location remain poorly characterized. We report a case of primary EHE of the urinary bladder in a 58-year-old woman who was treated by transurethral resection and review the existing literature on the diagnosis and treatment of EHE of the bladder.