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Stimulator of interferon genes (STING) is critical for cytosolic DNA-triggered innate immunity. STING is modified by several types of polyubiquitin chains. Here, we report that the deubiquitinase CYLD sustains STING signaling by stabilizing the STING protein. CYLD deficiency promoted the K48-linked polyubiquitination and degradation of STING, attenuating the induction of IRF3-responsive genes after HSV-1 infection or the transfection of DNA ligands. Additionally, CYLD knockout mice were more susceptible to HSV-1 infection than their wild-type (WT) littermates. Mechanistically, STING translocated from the ER to the Golgi upon HSV-1 stimulation; CYLD partially accumulated with STING and interacted selectively with K48-linked polyubiquitin chains on STING, specifically removing the K48-linked polyubiquitin chains from STING and ultimately boosting the innate antiviral response. Our study reveals that CYLD is a novel checkpoint in the cGAS-STING signaling pathway and sheds new light on the dynamic regulation of STING activity by ubiquitination. [ABSTRACT FROM AUTHOR]

The cyclic GMP-AMP synthase (cGAS), upon cytosolic DNA stimulation, catalyzes the formation of the second messenger 2′3′-cGAMP, which then binds to stimulator of interferon genes (STING) and activates downstream signaling. It remains to be elucidated how the cGAS enzymatic activity is modulated dynamically. Here, we reported that the ER ubiquitin ligase RNF185 interacted with cGAS during HSV-1 infection. Ectopic-expression or knockdown of RNF185 respectively enhanced or impaired the IRF3-responsive gene expression. Mechanistically, RNF185 specifically catalyzed the K27-linked poly-ubiquitination of cGAS, which promoted its enzymatic activity. Additionally, Systemic Lupus Erythematosus (SLE) patients displayed elevated expression of RNF185 mRNA. Collectively, this study uncovers RNF185 as the first E3 ubiquitin ligase of cGAS, shedding light on the regulation of cGAS activity in innate immune responses. [ABSTRACT FROM AUTHOR]

Stimulator of interferon genes (STING, also known as MITA, ERIS or MPYS) induces the activation of TBK1 kinase and IRF3 transcription factor, upon sensing of microbial DNAs. How IRF3 is recruited onto the STING signalosome remains unknown. We report here that silencing of the ER adaptor SCAP markedly impairs the IRF3-responsive gene expression induced by STING. Scap knockdown mice are more susceptible to HSV-1 infection. Interestingly, SCAP translocates from ER, via Golgi, to perinuclear microsome in a STING-dependent manner. Mechanistically, the N-terminal transmembrane domain of SCAP interacts with STING, and the C-terminal cytosolic domain of SCAP binds to IRF3, thus recruiting IRF3 onto STING signalosome. Mis-localization of SCAP abolishes its antiviral function. Collectively, this study characterizes SCAP as an essential adaptor in the STING signaling pathway, uncovering a critical missing link in DNAs-triggered host antiviral responses. [ABSTRACT FROM AUTHOR]

Background: Recently, an increasing number of human and animal studies have reported that exposure to benzo(a)pyrene (BaP) induces neurological abnormalities and is also associated with adverse effects, such as tumor formation, immunosuppression, teratogenicity, and hormonal disorders. However, the exact mechanisms underlying BaP-induced impairment of neurological function remain unclear. The aim of this study was to examine the regulating mechanisms underlying the impact of chronic BaP exposure on neurobehavioral performance. Methods: C57BL mice received either BaP in different doses (1.0, 2.5, 6.25 mg/kg) or olive oil twice a week for 90 days. Memory and emotional behaviors were evaluated using Y-maze and open-field tests, respectively. Furthermore, levels of mRNA expression were measured by using qPCR, and DNA methylation of NMDA receptor 2B subunit (NR2B) was examined using bisulfate pyrosequencing in the prefrontal cortex and hippocampus. Results: Compared to controls, mice that received BaP (2.5, 6.25 mg/kg) showed deficits in short-term memory and an anxiety-like behavior. These behavioral alterations were associated with a down-regulation of the NR2B gene and a concomitant increase in the level of DNA methylation in the NR2B promoter in the two brain regions. Conclusions: Chronic BaP exposure induces an increase in DNA methylation in the NR2B gene promoter and down-regulates NR2B expression, which may contribute to its neurotoxic effects on behavioral performance. The results suggest that NR2B vulnerability represents a target for environmental toxicants in the brain. [ABSTRACT FROM AUTHOR]

Lactobacillus plantarum is known beneficial for the fish to defend against Aeromonas hydrophila infection which causes major disease outbreaks and severe economic losses for aquaculture. However, the mechanisms remain unclear. In the present study, 240 zebrafish with an average body weights of 0.33 ± 0.01 g were randomly divided into 4 groups. The zebrafish were fed a basal diet supplemented with 3.3 × 108 CFU L. plantarum WCFS1/g or not for 1 week. They were then exposed to water supplementation with or without 1.5 × 108 CFU A. hydrophila NJ-1/mL for 1 day. Finally, all the fish were transferred to fresh water and fed the basal diets for 5 days. The results showed that dietary supplementation with L. plantarum WCFS1 attenuated mortality, A. hydrophila NJ-1 colonization, histological damage, and inflammation in the intestine, liver, gill, and muscle of zebrafish challenged with A. hydrophila NJ-1. In addition, the suppressive effect of L. plantarum WCFS1 on pro-inflammatory genes expression (interleukin 1β and tumor necrosis factor-α) was associated with altered mRNA levels for autophagy (lysosomal-associated membrane protein 1, lysosomal-associated membrane protein 2, autophagy-related gene 6, and autophagy-related gene 5) and hypoxia-inducible factors (hypoxia-inducible factors - 1αa, hypoxia-inducible factors - 1αb, and hypoxia-inducible factors-3α). Furthermore, L. plantarum WCFS1 alleviated A. hydrophila NJ-1-induced muscle loss by down-regulation of mRNA expression for myostatin and F-box protein 32, and up-regulation of mRNA expression for myogenin and myogenic determination 1. Collectively, L. plantarum WCFS1 holds great potential in aquaculture to defend against A. hydrophila infection. [Display omitted] • WCFS1 reduced zebrafish mortality and histological damage induced by A. hydrophila. • WCFS1 reduced A. hydrophila colonization in zebrafish challenged by A. hydrophila. • WCFS1 inhibited A. hydrophila -induced inflammation by regulation of autophagy and hypoxia-inducible factors. [ABSTRACT FROM AUTHOR]

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase catalyzes the transfer of electrons from NADPH to O2, which is the main source of reactive oxygen species (ROS) in nonphagocytic cells. Excess ROS are toxic; therefore, keeping ROS in homeostasis in cells can protect cells from oxidative damage. It is meaningful to further understand the molecular mechanism by which ROS homeostasis is mediated. Human protein HSCARG is a newly identified oxidative sensor and a negative regulator of NF-κB. Here, we find that HSCARG represses the cellular ROS generation through inhibiting mRNA and protein expression of p47phox, a subunit of NADPH oxidase. In contrast, shRNA-mediated HSCARG knockdown increases endogenous p47phox expression level. And HSCARG has no obvious effect on ROS production in p47phox-depleted cells. Furthermore, HSCARG regulates p47phox through inhibition of NF-κB activity. Our findings identify HSCARG as a novel regulator in regulation of the activity of NADPH oxidase and ROS homeostasis. [ABSTRACT FROM AUTHOR]

ShengMai-Yin and Ganmaidazao decoction are classic formulas in traditional Chinese medicine. Individually, Shengmai-Yin is used to treat cardiovascular diseases, and Ganmaidazao decoction for therapy of mental disorders. The combination of Shengmai-Yin and Ganmaidazao decoction (SGD) is normally used as adjuvant therapy for type 2 diabetes mellitus (T2DM). The central aim is to elucidate the pharmacological efficacy of SGD and its mechanism in the treatment of T2DM with non-alcoholic fatty liver disease (NAFLD). Active ingredients in SGD and their drug targets were identified using network analysis followed by experimental validation. First, existing databases were mined for information relevant to SGD, including pharmacological actions, chemical components, physicochemical characteristics, potential targets, and implicated diseases. Candidate patterns obtained with the network analysis were then tested in a KKAy mouse model of T2DM with NAFLD. Various doses of SGD were administered, followed by measurements of fasting blood glucose, oral glucose tolerance tests, insulin tolerance tests, markers of lipid metabolism - including free fatty acids (FFA), triglycerides (TG), and total cholesterol (TC) - liver histology, and expression levels of implicated molecules including PI3K/AKT and PPARα. Over 300 potential active compounds with their physicochemical characteristics and 562 candidate targets were collected, and then the network of them was constructed. Follow-up pathway and functional enrichment analyses indicated that SGD influences metabolism-related signaling pathways including PI3K-Akt, AMPK, and PPAR. In validation experiments, treatment of KKAy mice with SGD reduced serum levels of glucose, TC, TG, and FFA, decreased numbers of crown-like structures in visceral adipose tissue, reduced adipocyte size, and lowered liver lipid deposits. Further, SGD improved liver metabolism by increasing the expressions of PPARα, HSL, and PI3K/Akt, and decreasing expressions of SREBP-1 and FASN, inhibiting lipid biosynthesis, and increasing insulin sensitivity. Experimental validation of network analysis revealed anti-diabetic effects of the plant product SGD, manifested most notably by improved serum profiles and diminished insulin resistance. These experimental results may have clinical implications. Image 1 [ABSTRACT FROM AUTHOR]