Cell type-specific NRBF2 orchestrates autophagic flux and adult hippocampal neurogenesis in chronic stress-induced depression.

Dysfunctional autophagy and impairment of adult hippocampal neurogenesis (AHN) each contribute to the pathogenesis of major depressive disorder (MDD). However, whether dysfunctional autophagy is linked to aberrant AHN underlying MDD remains unclear. Here we demonstrate that the expression of nuclear receptor binding factor 2 (NRBF2), a component of autophagy-associated PIK3C3/VPS34-containing phosphatidylinositol 3-kinase complex, is attenuated in the dentate gyrus (DG) under chronic stress. NRBF2 deficiency inhibits the activity of the VPS34 complex and impairs autophagic flux in adult neural stem cells (aNSCs). Moreover, loss of NRBF2 disrupts the neurogenesis-related protein network and causes exhaustion of aNSC pool, leading to the depression-like phenotype. Strikingly, overexpressing NRBF2 in aNSCs of the DG is sufficient to rescue impaired AHN and depression-like phenotype of mice. Our findings reveal a significant role of NRBF2-dependent autophagy in preventing chronic stress-induced AHN impairment and suggest the therapeutic potential of targeting NRBF2 in MDD treatment.

α-MSH-catabolic enzyme prolylcarboxypeptidase in nucleus accumbens shell ameliorates stress susceptibility in mice through regulating synaptic plasticity.

Emerging evidence demonstrates the vital role of synaptic transmission and structural remodeling in major depressive disorder. Activation of melanocortin receptors facilitates stress-induced emotional behavior. Prolylcarboxypeptidase (PRCP) is a serine protease, which splits the C-terminal amino acid of α-MSH and inactivates it. In this study, we asked whether PRCP, the endogenous enzyme of melanocortin system, might play a role in stress susceptibility via regulating synaptic adaptations. Mice were subjected to chronic social defeat stress (CSDS) or subthreshold social defeat stress (SSDS). Depressive-like behavior was assessed in SIT, SPT, TST and FST. Based on to behavioral assessments, mice were divided into the susceptible (SUS) and resilient (RES) groups. After social defeat stress, drug infusion or viral expression and behavioral tests, morphological and electrophysiological analysis were conducted in PFX-fixed and fresh brain slices containing the nucleus accumbens shell (NAcsh). We showed that PRCP was downregulated in NAcsh of susceptible mice. Administration of fluoxetine (20 mg·kg-1·d-1, i.p., for 2 weeks) ameliorated the depressive-like behavior, and restored the expression levels of PRCP in NAcsh of susceptible mice. Pharmacological or genetic inhibition of PRCP in NAcsh by microinjection of N-benzyloxycarbonyl-L-prolyl-L-prolinal (ZPP) or LV-shPRCP enhanced the excitatory synaptic transmission in NAcsh, facilitating stress susceptibility via central melanocortin receptors. On the contrary, overexpression of PRCP in NAcsh by microinjection of AAV-PRCP alleviated the depressive-like behavior and reversed the enhanced excitatory synaptic transmission, abnormal dendritogenesis and spinogenesis in NAcsh induced by chronic stress. Furthermore, chronic stress increased the level of CaMKIIα, a kinase closely related to synaptic plasticity, in NAcsh. The elevated level of CaMKIIα was reversed by overexpression of PRCP in NAcsh. Pharmacological inhibition of CaMKIIα in NAcsh alleviated stress susceptibility induced by PRCP knockdown. This study has revealed the essential role of PRCP in relieving stress susceptibility through melanocortin signaling-mediated synaptic plasticity in NAcsh.

A thalamic circuit facilitates stress susceptibility via melanocortin 4 receptor-mediated activation of nucleus accumbens shell.

AIMS: Central melanocortin 4 receptor (MC4R) has been reported to induce anhedonia via eliciting dysfunction of excitatory synapses. It is evident that metabolic signals are closely related to chronic stress-induced depression. Here, we investigated that a neural circuit is involved in melanocortin signaling contributing to susceptibility to stress. METHODS: Chronic social defeat stress (CSDS) was used to develop depressive-like behavior. Electrophysiologic and chemogenetic approaches were performed to evaluate the role of paraventricular thalamus (PVT) glutamatergic to nucleus accumbens shell (NAcsh) circuit in stress susceptibility. Pharmacological and genetic manipulations were applied to investigate the molecular mechanisms of melanocortin signaling in the circuit. RESULTS: CSDS increases the excitatory neurotransmission in NAcsh through MC4R signaling. The enhanced excitatory synaptic input in NAcsh is projected from PVT glutamatergic neurons. Moreover, chemogenetic manipulation of PVTGlu -NAcsh projection mediates the susceptibility to stress, which is dependent on MC4R signaling. Overall, these results reveal that the strengthened excitatory neurotransmission in NAcsh originates from PVT glutamatergic neurons, facilitating the susceptibility to stress through melanocortin signaling. CONCLUSIONS: Our results make a strong case for harnessing a thalamic circuit to reorganize excitatory synaptic transmission in relieving stress susceptibility and provide insights gained on metabolic underpinnings of protection against stress-induced depressive-like behavior.

Long noncoding RNA Gm2694 drives depressive-like behaviors in male mice by interacting with GRP78 to disrupt endoplasmic reticulum homeostasis.

Long noncoding RNAs (lncRNAs) are involved in various biological processes and implicated in the regulation of neuronal activity, but the potential role of lncRNAs in depression remains largely unknown. Here, we identified that lncRNA Gm2694 was increased in the medial prefrontal cortex (mPFC) of male mice subjected to chronic social defeat stress (CSDS). The down-regulation of Gm2694 in the mPFC alleviated CSDS-induced depressive-like behaviors through enhanced excitatory synaptic transmission. Furthermore, we found that Gm2694 preferentially interacted with the carboxyl-terminal domain of 78-kilodalton glucose-regulated protein (GRP78), which abrogated GRP78 function and disrupted endoplasmic reticulum homeostasis, resulting in a reduction of the surface expression of AMPA receptors (AMPARs). Overexpression of GRP78 in the mPFC promoted the surface expression of AMPARs and attenuated the CSDS-induced depressive-like behaviors of mice. Together, our results unraveled a previously unknown role of Gm2694 in regulating endoplasmic reticulum homeostasis and excitatory synaptic transmission in depression.

Repeated vagus nerve stimulation produces anxiolytic effects via upregulation of AMPAR function in centrolateral amygdala of male rats.

Repeated vagus nerve stimulation (rVNS) exerts anxiolytic effect by activation of noradrenergic pathway. Centrolateral amygdala (CeL), a lateral subdivision of central amygdala, receives noradrenergic inputs, and its neuronal activity is positively correlated to anxiolytic effect of benzodiazepines. The activation of ß-adrenergic receptors (ß-ARs) could enhance glutamatergic transmission in CeL. However, it is unclear whether the neurobiological mechanism of noradrenergic system in CeL mediates the anxiolytic effect induced by rVNS. Here, we find that rVNS treatment produces an anxiolytic effect in male rats by increasing the neuronal activity of CeL. Electrophysiology recording reveals that rVNS treatment enhances the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR)-mediated excitatory neurotransmission in CeL, which is mimicked by ß-ARs agonist isoproterenol or blocked by ß-ARs antagonist propranolol. Moreover, chemogenetic inhibition of CeL neurons or pharmacological inhibition of ß-ARs in CeL intercepts both enhanced glutamatergic neurotransmission and the anxiolytic effects by rVNS treatment. These results suggest that the amplified AMPAR trafficking in CeL via activation of ß-ARs is critical for the anxiolytic effects induced by rVNS treatment.

Melatonin decreases androgen-sensitive prostate cancer growth by suppressing SENP1 expression.

BACKGROUND: Melatonin is a hormone naturally produced by the pineal gland in the brain. In addition to modulating circadian rhythms, it has pleiotropic biological effects including antioxidant, immunomodulatory, and anti-cancer effects. Herein, we report that melatonin has the ability to decrease the growth and metastasis of androgen-dependent prostate cancer. METHODS: To evaluate the anti-cancer effect of melatonin on androgen-sensitive prostate cancer in vitro or in vivo, the effects of cell proliferation, apoptosis, migration and invasion were analyzed by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), colony formation, flow cytometry, Transwell assay, and immunohistochemistry (IHC), respectively. Next, the interaction between androgen receptor (AR) and SUMO specific protease 1 (SENP1) was detected by real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and western blotting, and confirmed by luciferase reporter assay. Furthermore, the Small Ubiquitin-like Modifier (SUMO) proteins are a group of small proteins that are covalently attached to and detached from other proteins in cells to modify their function. (SUMOylation) of histone deacetylases 1 (HDAC1) was measured by proximity ligation assay (PLA). RESULTS: The treatment of melatonin cripples the transcriptional activity of AR, which is essential for the growth of the androgen-dependent prostate cancer cell, LNCaP. The lower activity of AR was dependent on melatonin induced SUMOylation of HDAC1, which has been established as a key factor for the transcriptional activity of AR. Mechanistically, the effect of melatonin on AR was due to the decreased SENP1 protein level and the subsequent increased HDAC1 SUMOylation level. The overexpression of SENP1 abrogated the anti-cancer ability of melatonin on LNCaP cells. CONCLUSIONS: These findings indicate that melatonin is a suppressor of androgen-dependent prostate cancer tumorigenesis.

Targeting HNRNPU to overcome cisplatin resistance in bladder cancer.

PURPOSE: The overall response of cisplatin-based chemotherapy in bladder urothelial carcinoma (BUC) remains unsatisfactory due to the complex pathological subtypes, genomic difference, and drug resistance. The genes that associated with cisplatin resistance remain unclear. Herein, we aimed to identify the cisplatin resistance associated genes in BUC. EXPERIMENTAL DESIGN: The cytotoxicity of cisplatin was evaluated in six bladder cancer cell lines to compare their responses to cisplatin. The T24 cancer cells exhibited the lowest sensitivity to cisplatin and was therefore selected to explore the mechanisms of drug resistance. We performed genome-wide CRISPR screening in T24 cancer cells in vitro, and identified that the gene heterogeneous nuclear ribonucleoprotein U (HNRNPU) was the top candidate gene related to cisplatin resistance. Epigenetic and transcriptional profiles of HNRNPU-depleted cells after cisplatin treatment were analyzed to investigate the relationship between HNRNPU and cisplatin resistance. In vivo experiments were also performed to demonstrate the function of HNRNPU depletion in cisplatin sensitivity. RESULTS: Significant correlation was found between HNRNPU expression level and sensitivity to cisplatin in bladder cancer cell lines. In the high HNRNPU expressing T24 cancer cells, knockout of HNRNPU inhibited cell proliferation, invasion, and migration. In addition, loss of HNRNPU promoted apoptosis and S-phase arrest in the T24 cells treated with cisplatin. Data from The Cancer Genome Atlas (TCGA) demonstrated that HNRNPU expression was significantly higher in tumor tissues than in normal tissues. High HNRNPU level was negatively correlated with patient survival. Transcriptomic profiling analysis showed that knockout of HNRNPU enhanced cisplatin sensitivity by regulating DNA damage repair genes. Furthermore, it was found that HNRNPU regulates chemosensitivity by affecting the expression of neurofibromin 1 (NF1). CONCLUSIONS: Our study demonstrated that HNRNPU expression is associated with cisplatin sensitivity in bladder urothelial carcinoma cells. Inhibition of HNRNPU could be a potential therapy for cisplatin-resistant bladder cancer.

Identification of C3 and FN1 as potential biomarkers associated with progression and prognosis for clear cell renal cell carcinoma.

BACKGROUND: Clear cell renal cell carcinoma (ccRCC) is one of the most lethal urological malignancies, but the pathogenesis and prognosis of ccRCC remain obscure, which need to be better understand. METHODS: Differentially expressed genes were identified and function enrichment analyses were performed using three publicly available ccRCC gene expression profiles downloaded from the Gene Expression Omnibus database. The protein-protein interaction and the competing endogenous RNA (ceRNA) networks were visualized by Cytoscape. Multivariate Cox analysis was used to predict an optimal risk mode, and the survival analysis was performed with the Kaplan-Meier curve and log-rank test. Protein expression data were downloaded from Clinical Proteomic Tumor Analysis Consortium database and Human Protein Atlas database, and the clinical information as well as the corresponding lncRNA and miRNA expression data were obtained via The Cancer Genome Atlas database. The co-expressed genes and potential function of candidate genes were explored using data exacted from the Cancer Cell Line Encyclopedia database. RESULTS: Of the 1044 differentially expressed genes shared across the three datasets, 461 were upregulated, and 583 were downregulated, which significantly enriched in multiple immunoregulatory-related biological process and tumor-associated pathways, such as HIF-1, PI3K-AKT, P53 and Rap1 signaling pathways. In the most significant module, 36 hub genes were identified and were predominantly enriched in inflammatory response and immune and biotic stimulus pathways. Survival analysis and validation of the hub genes at the mRNA and protein expression levels suggested that these genes, particularly complement component 3 (C3) and fibronectin 1 (FN1), were primarily responsible for ccRCC tumorigenesis and progression. Increased expression of C3 or FN1 was also associated with advanced clinical stage, high pathological grade, and poor survival in patients with ccRCC. Univariate and multivariate Cox regression analysis qualified the expression levels of the two genes as candidate biomarkers for predicting poor survival. FN1 was potentially regulated by miR-429, miR-216b and miR-217, and constructed a bridge to C3 and C3AR1 in the ceRNA network, indicating a critical position of FN1. CONCLUSIONS: The biomarkers C3 and FN1 could provide theoretical support for the development of a novel prognostic tool to advance ccRCC diagnosis and targeted therapy.

Role of NRP1 in Bladder Cancer Pathogenesis and Progression.

Bladder urothelial carcinoma (BC) is a fatal invasive malignancy and the most common malignancy of the urinary system. In the current study, we investigated the function and mechanisms of Neuropilin-1 (NRP1), the co-receptor for vascular endothelial growth factor, in BC pathogenesis and progression. The expression of NRP1 was evaluated using data extracted from GEO and HPA databases and examined in BC cell lines. The effect on proliferation, apoptosis, angiogenesis, migration, and invasion of BC cells were validated after NRP1 knockdown. After identifying differentially expressed genes (DEGs) induced by NRP1 silencing, GO/KEGG and IPA® bioinformatics analyses were performed and specific predicted pathways and targets were confirmed in vitro. Additionally, the co-expressed genes and ceRNA network were predicted using data downloaded from CCLE and TCGA databases, respectively. High expression of NRP1 was observed in BC tissues and cells. NRP1 knockdown promoted apoptosis and suppressed proliferation, angiogenesis, migration, and invasion of BC cells. Additionally, after NRP1 silencing the activity of MAPK signaling and molecular mechanisms of cancer pathways were predicted by KEGG and IPA® pathway analysis and validated using western blot in BC cells. NRP1 knockdown also affected various biological functions, including antiviral response, immune response, cell cycle, proliferation and migration of cells, and neovascularisation. Furthermore, the main upstream molecule of the DEGs induced by NRP1 knockdown may be NUPR1, and NRP1 was also the downstream target of NUPR1 and essential for regulation of FOXP3 expression to activate neovascularisation. DCBLD2 was positively regulated by NRP1, and PPAR signaling was significantly associated with low NRP1 expression. We also found that NRP1 was a predicted target of miR-204, miR-143, miR-145, and miR-195 in BC development. Our data provide evidence for the biological function and molecular aetiology of NRP1 in BC and for the first time demonstrated an association between NRP1 and NUPR1, FOXP3, and DCBLD2. Specifically, downregulation of NRP1 contributes to BC progression, which is associated with activation of MAPK signaling and molecular mechanisms involved in cancer pathways. Therefore, NRP1 may serve as a target for new therapeutic strategies to treat BC and other cancers.

De-palmitoylation by N-(tert-Butyl) hydroxylamine inhibits AMPAR-mediated synaptic transmission via affecting receptor distribution in postsynaptic densities.

AIMS: Palmitoylation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) subunits or their "scaffold" proteins produce opposite effects on AMPAR surface delivery. Considering AMPARs have long been identified as suitable drug targets for central nervous system (CNS) disorders, targeting palmitoylation signaling to regulate AMPAR function emerges as a novel therapeutic strategy. However, until now, much less is known about the effect of palmitoylation-deficient state on AMPAR function. Herein, we set out to determine the effect of global de-palmitoylation on AMPAR surface expression and its function, using a special chemical tool, N-(tert-Butyl) hydroxylamine (NtBuHA). METHODS: BS3 protein cross-linking, Western blot, immunoprecipitation, patch clamp, and biotin switch assay. RESULTS: Bath application of NtBuHA (1.0 mM) reduced global palmitoylated proteins in the hippocampus of mice. Although NtBuHA (1.0 mM) did not affect the expression of ionotropic glutamate receptor subunits, it preferentially decreased the surface expression of AMPARs, not N-methyl-d-aspartate receptors (NMDARs). Notably, NtBuHA (1.0 mM) reduces AMPAR-mediated excitatory postsynaptic currents (mEPSCs) in the hippocampus. This effect may be largely due to the de-palmitoylation of postsynaptic density protein 95 (PSD95) and protein kinase A-anchoring proteins, both of which stabilized AMPAR synaptic delivery. Furthermore, we found that changing PSD95 palmitoylation by NtBuHA altered the association of PSD95 with stargazin, which interacted directly with AMPARs, but not NMDARs. CONCLUSION: Our data suggest that the palmitoylation-deficient state initiated by NtBuHA preferentially reduces AMPAR function, which may potentially be used for the treatment of CNS disorders, especially infantile neuronal ceroid lipofuscinosis (Batten disease).

Gephyrin Palmitoylation in Basolateral Amygdala Mediates the Anxiolytic Action of Benzodiazepine.

BACKGROUND: Benzodiazepines (BZDs) have been used to treat anxiety disorders for more than five decades as the allosteric modulator of the gamma-aminobutyric acid A receptor (GABAAR). Little is known about other mechanisms of BZDs. Here, we describe how the rapid stabilization of postsynaptic GABAAR is essential and sufficient for the anxiolytic effect of BZDs via a palmitoylation-dependent mechanism. METHODS: Palmitoylated proteins in the basolateral amygdala (BLA) of rats with different anxious states were assessed by a biotin exchange protocol. Both pharmacological and genetic approaches were used to investigate the role of palmitoylation in anxiety behavior. Electrophysiological recording, reverse transcription polymerase chain reaction, Western blotting, and coimmunoprecipitation were used to investigate the mechanisms. RESULTS: Highly anxious rats were accompanied by the deficiency of gephyrin palmitoylation and decreased the synaptic function of GABAAR in the BLA. We then identified that the dysfunction of DHHC12, a palmitoyl acyltransferase that specifically palmitoylates gephyrin, contributed to the high-anxious state. Furthermore, diazepam, as an anxiolytic drug targeting GABAARs, was found to increase gephyrin palmitoylation in the BLA via a GABAAR-dependent manner to activate DHHC12. The anxiolytic effect of diazepam was nearly abolished by the DHHC12 knockdown. Specifically, similar to the effect of BZD, the overexpression of DHHC12 in the BLA exerted a significant anxiolytic action, which was prevented by flumazenil. CONCLUSIONS: Our results support the view that the strength of inhibitory synapse was controlled by gephyrin palmitoylation in vivo and proposes a previously unknown palmitoylation-centered mode of BZD's action.