PRMT5-mediated homologous recombination repair is essential to maintain genomic integrity of neural progenitor cells.

Maintaining genomic stability is a prerequisite for proliferating NPCs to ensure genetic fidelity. Though histone arginine methylation has been shown to play important roles in safeguarding genomic stability, the underlying mechanism during brain development is not fully understood. Protein arginine N-methyltransferase 5 (PRMT5) is a type II protein arginine methyltransferase that plays a role in transcriptional regulation. Here, we identify PRMT5 as a key regulator of DNA repair in response to double-strand breaks (DSBs) during NPC proliferation. Prmt5F/F; Emx1-Cre (cKO-Emx1) mice show a distinctive microcephaly phenotype, with partial loss of the dorsal medial cerebral cortex and complete loss of the corpus callosum and hippocampus. This phenotype is resulted from DSBs accumulation in the medial dorsal cortex followed by cell apoptosis. Both RNA sequencing and in vitro DNA repair analyses reveal that PRMT5 is required for DNA homologous recombination (HR) repair. PRMT5 specifically catalyzes H3R2me2s in proliferating NPCs in the developing mouse brain to enhance HR-related gene expression during DNA repair. Finally, overexpression of BRCA1 significantly rescues DSBs accumulation and cell apoptosis in PRMT5-deficient NSCs. Taken together, our results show that PRMT5 maintains genomic stability by regulating histone arginine methylation in proliferating NPCs.

Dysregulation of AMPK-mTOR signaling leads to comorbid anxiety in Dip2a KO mice.

Autism is often comorbid with other psychiatric disorders. We have previously shown that Dip2a knockout (KO) induces autism-like behaviors in mice. However, the role of Dip2a in other psychiatric disorders remains unclear. In this paper, we revealed that Dip2a KO mice had comorbid anxiety. Dip2a KO led to a reduction in the dendritic length of cortical and hippocampal excitatory neurons. Molecular mechanism studies suggested that AMPK was overactivated and suppressed the mTOR cascade, contributing to defects in dendritic morphology. Deletion of Dip2a in adult-born hippocampal neurons (Dip2a conditional knockout (cKO)) increased susceptibility to anxiety upon acute stress exposure. Application of (2R,6R)-hydroxynorketamine (HNK), an inhibitor of mTOR, rescued anxiety-like behaviors in Dip2a KO and Dip2a cKO mice. In addition, 6 weeks of high-fat diet intake alleviated AMPK-mTOR signaling and attenuated the severity of anxiety in both Dip2a KO mice and Dip2a cKO mice. Taken together, these results reveal an unrecognized function of DIP2A in anxiety pathophysiology via regulation of AMPK-mTOR signaling.

Netrin-1 Is an Important Mediator in Microglia Migration.

Microglia migrate to the cerebral cortex during early embryonic stages. However, the precise mechanisms underlying microglia migration remain incompletely understood. As an extracellular matrix protein, Netrin-1 is involved in modulating the motility of diverse cells. In this paper, we found that Netrin-1 promoted microglial BV2 cell migration in vitro. Mechanism studies indicated that the activation of GSK3ß activity contributed to Netrin-1-mediated microglia migration. Furthermore, Integrin α6/ß1 might be the relevant receptor. Single-cell data analysis revealed the higher expression of Integrin α6 subunit and ß1 subunit in microglia in comparison with classical receptors, including Dcc, Neo1, Unc5a, Unc5b, Unc5c, Unc5d, and Dscam. Microscale thermophoresis (MST) measurement confirmed the high binding affinity between Integrin α6/ß1 and Netrin-1. Importantly, activation of Integrin α6/ß1 with IKVAV peptides mirrored the microglia migration and GSK3 activation induced by Netrin-1. Finally, conditional knockout (CKO) of Netrin-1 in radial glial cells and their progeny led to a reduction in microglia population in the cerebral cortex at early developmental stages. Together, our findings highlight the role of Netrin-1 in microglia migration and underscore its therapeutic potential in microglia-related brain diseases.

Human antigen R-regulated mRNA metabolism promotes the cell motility of migrating mouse neurons.

Neocortex development during embryonic stages requires the precise control of mRNA metabolism. Human antigen R (HuR) is a well-studied mRNA-binding protein that regulates mRNA metabolism, and it is highly expressed in the neocortex during developmental stages. Deletion of HuR does not impair neural progenitor cell proliferation or differentiation, but it disturbs the laminar structure of the neocortex. We report that HuR is expressed in postmitotic projection neurons during mouse brain development. Specifically, depletion of HuR in these neurons led to a mislocalization of CDP+ neurons in deeper layers of the cortex. Time-lapse microscopy showed that HuR was required for the promotion of cell motility in migrating neurons. PCR array identified profilin 1 (Pfn1) mRNA as a major binding partner of HuR in neurons. HuR positively mediated the stability of Pfn1 mRNA and influenced actin polymerization. Overexpression of Pfn1 successfully rescued the migration defects of HuR-deleted neurons. Our data reveal a post-transcriptional mechanism that maintains actin dynamics during neuronal migration.

Machine learning prognosis model based on patient-reported outcomes for chronic heart failure patients after discharge.

BACKGROUND: Patient-reported outcomes (PROs) can be obtained outside hospitals and are of great significance for evaluation of patients with chronic heart failure (CHF). The aim of this study was to establish a prediction model using PROs for out-of-hospital patients. METHODS: CHF-PRO were collected in 941 patients with CHF from a prospective cohort. Primary endpoints were all-cause mortality, HF hospitalization, and major adverse cardiovascular events (MACEs). To establish prognosis models during the two years follow-up, six machine learning methods were used, including logistic regression, random forest classifier, extreme gradient boosting (XGBoost), light gradient boosting machine, naive bayes, and multilayer perceptron. Models were established in four steps, namely, using general information as predictors, using four domains of CHF-PRO, using both of them and adjusting the parameters. The discrimination and calibration were then estimated. Further analyze were performed for the best model. The top prediction variables were further assessed. The Shapley additive explanations (SHAP) method was used to explain black boxes of the models. Moreover, a self-made web-based risk calculator was established to facilitate the clinical application. RESULTS: CHF-PRO showed strong prediction value and improved the performance of the models. Among the approaches, XGBoost of the parameter adjustment model had the highest prediction performance with an area under the curve of 0.754 (95% CI: 0.737 to 0.761) for death, 0.718 (95% CI: 0.717 to 0.721) for HF rehospitalization and 0.670 (95% CI: 0.595 to 0.710) for MACEs. The four domains of CHF-PRO, especially the physical domain, showed the most significant impact on the prediction of outcomes. CONCLUSION: CHF-PRO showed strong prediction value in the models. The XGBoost models using variables based on CHF-PRO and the patient's general information provide prognostic assessment for patients with CHF. The self-made web-based risk calculator can be conveniently used to predict the prognosis for patients after discharge. CLINICAL TRIAL REGISTRATION: URL: http://www.chictr.org.cn/index.aspx ; Unique identifier: ChiCTR2100043337.

The Reliability and Quality of Short Videos as a Source of Dietary Guidance for Inflammatory Bowel Disease: Cross-sectional Study.

BACKGROUND: Dietary management is considered a potential adjunctive treatment for inflammatory bowel disease (IBD). Short-video sharing platforms have enabled patients to obtain dietary advice more conveniently. However, accessing useful resources while avoiding misinformation is not an easy task for most patients. OBJECTIVE: This study aimed to evaluate the quality of the information in IBD diet-related videos on Chinese short-video sharing platforms. METHODS: We collected and extracted information from a total of 125 video samples related to the IBD diet on the 3 Chinese short-video sharing platforms with the most users: TikTok, Bilibili, and Kwai. Two independent physicians evaluated each video in terms of content comprehensiveness, quality (rated by Global Quality Score), and reliability (rated by a modified DISCERN tool). Finally, comparative analyses of the videos from different sources were conducted. RESULTS: The videos were classified into 6 groups based on the identity of the uploaders, which included 3 kinds of medical professionals (ie, gastroenterologists, nongastroenterologists, and clinical nutritionists) and 3 types of non-medical professionals (ie, nonprofit organizations, individual science communicators, and IBD patients). The overall quality of the videos was poor. Further group comparisons demonstrated that videos from medical professionals were more instructive in terms of content comprehensiveness, quality, and reliability than those from non-medical professionals. Moreover, IBD diet-related recommendations from clinical nutritionists and gastroenterologists were of better quality than those from nongastroenterologists, while recommendations from nonprofit organizations did not seem to be superior to other groups of uploaders. CONCLUSIONS: The overall quality of the information in IBD diet-related videos is unsatisfactory and varies significantly depending on the source. Videos from medical professionals, especially clinical nutritionists and gastroenterologists, may provide dietary guidance with higher quality for IBD patients.

A Nucleus Accumbens Tac1 Neural Circuit Regulates Avoidance Responses to Aversive Stimuli.

Neural circuits that control aversion are essential for motivational regulation and survival in animals. The nucleus accumbens (NAc) plays an important role in predicting aversive events and translating motivations into actions. However, the NAc circuits that mediate aversive behaviors remain elusive. Here, we report that tachykinin precursor 1 (Tac1) neurons in the NAc medial shell regulate avoidance responses to aversive stimuli. We show that NAcTac1 neurons project to the lateral hypothalamic area (LH) and that the NAcTac1→LH pathway contributes to avoidance responses. Moreover, the medial prefrontal cortex (mPFC) sends excitatory inputs to the NAc, and this circuit is involved in the regulation of avoidance responses to aversive stimuli. Overall, our study reveals a discrete NAc Tac1 circuit that senses aversive stimuli and drives avoidance behaviors.

Maltol ameliorates intervertebral disc degeneration through inhibiting PI3K/AKT/NF-κB pathway and regulating NLRP3 inflammasome-mediated pyroptosis.

OBJECTIVES: As one of the major causes of low back pain, intervertebral disc degeneration (IDD) has caused a huge problem for humans. Increasing evidence indicates that NLRP3 inflammasome-mediated pyroptosis of NP cells displays an important role in the progression of IDD. Maltol (MA) is a flavoring agent extracted from red ginseng. Due to its anti-inflammatory and antioxidant effects, MA has been widely considered by researchers. Therefore, we hypothesized that MA may be a potential IVD protective agent by regulating NP cells and their surrounding microenvironment. METHODS: In vitro, qRT-PCR, and Western blot were used to explore the effect of MA on the transcription and protein expression of the anabolic protein (ADAMTS5, MMP3, MMP9) catabolic protein (Aggrecan), and pro-inflammatory factor (iNOS COX-2). Next, the effects of MA on PI3K/AKT/NF-κB pathway and pyroptosis pathway were analyzed by Western blot and immunofluorescence. Molecular docking was used to investigate the relationship between PI3K and MA. Moreover, ELISA was also used to detect the effects of MA on inflammatory factors (TNF-α, PGE2, IL-1ß, and IL-18). In vivo, the effects of MA on the vertebral structure of IDD mice were studied by HE and SO staining and the effects of MA on ECM and PI3K/AKT/NF-κB and pyroptosis pathway of IDD mice were studied by immunohistochemical staining. RESULTS: MA can ameliorate intervertebral disc degeneration in vivo and in vitro. Specifically, the molecular docking results showed that the binding degree of MA and PI3K was significant. Second, in vitro studies showed that MA inhibited the degradation of ECM and inflammatory response by inhibiting the PI3K/AKT/NF-κB pathway and the pyroptosis mediated by NLRP3 inflammasome, which increased the expression of anabolic proteins, decreased the expression of catabolic proteins, and decreased the secretion of inflammatory mediators such as IL-18 and IL-1ß. In addition, according to the study results of the mouse lumbar instability model, MA also improved the tissue disorder and degradation of the intervertebral disc, reduced the loss of proteoglycan and glycosaminoglycan, and inhibited intervertebral disc inflammation, indicating that MA has a protective effect on the intervertebral disc to intervertebral disc in mice. CONCLUSIONS: Our results suggest that MA slowed IDD development through the PI3K/AKT/NF-κB signaling pathway and NLRP3 inflammasome-mediated pyroptosis, indicating that MA appeared to be a viable medication for IDD treatment.

Autism candidate gene DIP2A regulates spine morphogenesis via acetylation of cortactin.

Dendritic spine development is crucial for the establishment of excitatory synaptic connectivity and functional neural circuits. Alterations in spine morphology and density have been associated with multiple neurological disorders. Autism candidate gene disconnected-interacting protein homolog 2 A (DIP2A) is known to be involved in acetylated coenzyme A (Ac-CoA) synthesis and is primarily expressed in the brain regions with abundant pyramidal neurons. However, the role of DIP2A in the brain remains largely unknown. In this study, we found that deletion of Dip2a in mice induced defects in spine morphogenesis along with thin postsynaptic density (PSD), and reduced synaptic transmission of pyramidal neurons. We further identified that DIP2A interacted with cortactin, an activity-dependent spine remodeling protein. The binding activity of DIP2A-PXXP motifs (P, proline; X, any residue) with the cortactin-Src homology 3 (SH3) domain was critical for maintaining the level of acetylated cortactin. Furthermore, Dip2a knockout (KO) mice exhibited autism-like behaviors, including excessive repetitive behaviors and defects in social novelty. Importantly, acetylation mimetic cortactin restored the impaired synaptic transmission and ameliorated repetitive behaviors in these mice. Altogether, our findings establish an initial link between DIP2A gene variations in autism spectrum disorder (ASD) and highlight the contribution of synaptic protein acetylation to synaptic processing.

A Novel Netrin-1-Derived Peptide Enhances Protection against Neuronal Death and Mitigates of Intracerebral Hemorrhage in Mice.

It has been reported that Netrin-1 is involved in neuroprotection following injury to the central nervous system. However, the minimal functional domain of Netrin-1 which can preserve the neuroprotection but avoid the major side effects of Netrin remains elusive. Here, we investigated the neuroprotective effect of a peptide E1 derived from Netrin-1's EGF3 domain (residues 407-422). We found that it interacts with deleted colorectal carcinoma (DCC) to activate focal adhesion kinase phosphorylation exhibiting neuroprotection. The administration of the peptide E1 was able to improve functional recovery through reduced apoptosis in an experimental murine model of intracerebral hemorrhage (ICH). In summary, we reveal a functional sequence of Netrin-1 that is involved in the recovery process after ICH and identify a candidate peptide for the treatment of ICH.

HuR in the Medial Prefrontal Cortex is Critical for Stress-Induced Synaptic Dysfunction and Depressive-Like Symptoms in Mice.

Chronic stress has been observed to increase the risk of developing depression and induce neuronal alterations of synaptic plasticity, yet the underlying molecular mechanisms remain unclear. Here, we found that the ubiquitously expressed RNA-binding protein HuR was up-regulated in the medial prefrontal cortex (mPFC) of mice following chronic stress. In adult mice, AAV-Cre-mediated knockout of HuR in the mPFC prevented anxiety-like and depression-like behaviors induced by chronic stress. HuR was also required for the stress-induced dendritic spine loss and synaptic transmission deficits. Moreover, HuRflox/flox;Nex-Cre mice, which induce HuR loss of function from embryonic development, exhibited enhanced synaptic functions. Notably, we ascertained RhoA signaling to be regulated by HuR and involved in the modulation of structural synaptic plasticity in response to chronic stress. Our results demonstrate HuR is a critical modulator for the regulation of stress-induced synaptic plasticity alterations and depression, providing a potential therapeutic target for the treatment of depressive disorders.

Substance P plays a critical role in synaptic transmission in striatal neurons.

Substance P is one of the major neuropeptides released by striatal neurons; however, its function in the striatum remains unclear. In this study, we found substance P triggers spontaneous neurotransmitter release and rapid synaptic vesicle exocytosis in cultured striatal neurons, as substance P knockdown in these neurons impaired spontaneous neurotransmitter release and calcium-dependent rapid synaptic neurotransmission. Furthermore, treatment with exogenous substance P completely rescued the synaptic dysfunction phenotype in striatal neurons lacking this neuropeptide. On the other hand, substance P knockdown had no effect on the size of the readily releasable pool of synaptic vesicles, but decreased the probability of presynaptic release of synaptic vesicles in cultured striatal neurons. Treatment with CP96345, a NK1 receptor antagonist, also resulted in synaptic defects in cultured striatal neurons. In summary, we propose substance P is critical for synaptic transmission in striatal neurons.

Functional prediction and characterization of Dip2 gene in mice.

Disconnected interacting protein 2 (DIP2) is a highly conserved protein family among invertebrates and vertebrates, but its function remains unclear. In this paper, we summarized the conservation of gene sequences and protein domains of DIP2 family members and predicted that they may have a similar functional role in acetyl-coenzyme A (acetyl-CoA) synthesis. We then used the most characterized member, disconnected interacting protein 2 homolog A (DIP2A), for further study. DIP2A is a cytoplasmic protein that is preferentially localized to mitochondria, and its acetyl-CoA synthetase activity has been demonstrated in vitro. Furthermore, the level of acetyl-CoA in HEK293 cells overexpressing DIP2A was increased, which is consistent with its metabolically related function. Together, these data enrich the evolutionary and functional characterization of dip2 genes and provide significant insights into the identification and application of other homologs of DIP2.