A Peptide Derived from IKK-Interacting Protein Attenuates NF-κB Activation and Inflammation.

The IκB kinase (IKK) complex plays a vital role in regulating the NF-κB activation. Aberrant NF-κB activation is involved in various inflammatory diseases. Thus, targeting IKK activation is an ideal therapeutic strategy to cure and prevent inflammatory diseases related to NF-κB activation. In a previous study, we demonstrated that IKK-interacting protein (IKIP) inhibits the phosphorylation of IKKα/ß and the activation of NF-κB through disruption of the formation of IKK complex. In this study, we identified a 15-aa peptide derived from mouse IKIP (46-60 aa of IKIP), which specifically suppressed IKK activation and NF-κB targeted gene expression via disrupting the association of IKKß and NEMO. Importantly, administration of the peptide reduced LPS-induced acute inflammation and attenuated Zymosan-induced acute arthritis in mice. These findings suggest that this IKIP peptide may be a promising therapeutic reagent in the prevention and treatment of inflammatory diseases.

IKIP Negatively Regulates NF-κB Activation and Inflammation through Inhibition of IKKα/ß Phosphorylation.

Stringent regulation of the transcription factor NF-κB signaling is essential for the activation of host immune responses and maintaining homeostasis, yet the molecular mechanisms involved in its tight regulation are not completely understood. In this study, we report that IKK-interacting protein (IKIP) negatively regulates NF-κB activation. IKIP interacted with IKKα/ß to block its association with NEMO, thereby inhibiting the phosphorylation of IKKα/ß and the activation of NF-κB. Upon LPS, TNF-α, and IL-1ß stimulation, IKIP-deficient macrophages exhibited more and prolonged IKKα/ß phosphorylation, IκB, and p65 phosphorylation and production of NF-κB-responsive genes. Moreover, IKIP-deficient mice were more susceptible to LPS-induced septic shock and dextran sodium sulfate-induced colitis. Our study identifies a previously unrecognized role for IKIP in the negative regulation of NF-κB activation by inhibition of IKKα/ß phosphorylation through the disruption of IKK complex formation.

Real-Time Small Drones Detection Based on Pruned YOLOv4.

To address the threat of drones intruding into high-security areas, the real-time detection of drones is urgently required to protect these areas. There are two main difficulties in real-time detection of drones. One of them is that the drones move quickly, which leads to requiring faster detectors. Another problem is that small drones are difficult to detect. In this paper, firstly, we achieve high detection accuracy by evaluating three state-of-the-art object detection methods: RetinaNet, FCOS, YOLOv3 and YOLOv4. Then, to address the first problem, we prune the convolutional channel and shortcut layer of YOLOv4 to develop thinner and shallower models. Furthermore, to improve the accuracy of small drone detection, we implement a special augmentation for small object detection by copying and pasting small drones. Experimental results verify that compared to YOLOv4, our pruned-YOLOv4 model, with 0.8 channel prune rate and 24 layers prune, achieves 90.5% mAP and its processing speed is increased by 60.4%. Additionally, after small object augmentation, the precision and recall of the pruned-YOLOv4 almost increases by 22.8% and 12.7%, respectively. Experiment results verify that our pruned-YOLOv4 is an effective and accurate approach for drone detection.

CD-NTase family member MB21D2 promotes cGAS-mediated antiviral and antitumor immunity.

cGAS/DncV-like nucleotidyltransferase (CD-NTase) family members are immune sensors that synthesize diverse nucleotide signals to initiate antiviral response in bacteria and animals. As a founding member of CD-NTase enzyme, cGAS has been identified as a key sensor for cytoplasmic DNA and type I interferons (IFNs) signaling in metazoan. However, the functions of other metazoan CD-NTases remain enigmatic. Here, we showed that Mab-21 domain-containing protein 2 (MB21D2), another member of the CD-NTase family, plays a positive role in modulating the cGAS-STING signaling in myeloid cells. Deficiency of MB21D2 in THP-1 cells or mice macrophages led to impaired production of type I interferon upon DNA stimulation. Consistently, Mb21d2-/- mice showed more susceptible to infection with DNA virus and faster growth of melanoma, compared to its counterparts. Mechanistically, MB21D2 specially bound with the N-terminal of cGAS, facilitated its liquid phase condensation and DNA-binding activity, leading to the enhanced production of cGAMP and subsequent IFN-ß production. Thus, our findings unveiled that the CD-NTase family member MB21D2 contributes to host antiviral and antitumor responses by enhancing cGAS activation.

Native-PAGE analysis of protein aggregation upon viral infection in mouse macrophages.

Upon viral infection, several proteins in the innate signaling pathway form aggregates, which in turn promote the activation of innate antiviral immune response. In this protocol, we use herpes simplex virus type 1 (HSV-1) to infect mouse peritoneal macrophages, and show how to detect the aggregation of TBK1 upon viral infection. The protocol is adaptable for other proteins and other viruses. For complete details on the use and execution of this profile, please refer to Yan et al. (2021).

A novel yeast model detects Nrf2 and Keap1 interactions with Hsp90.

Nrf2 is the master transcriptional regulator of cellular responses against oxidative stress. It is chiefly regulated by Keap1, a substrate adaptor protein that mediates Nrf2 degradation. Nrf2 activity is also influenced by many other protein interactions that provide Keap1-independent regulation. To study Nrf2 regulation, we established and characterized yeast models expressing human Nrf2 (also known as NFE2L2), Keap1 and other proteins that interact with and regulate Nrf2. Yeast models have been well established as powerful tools to study protein function and genetic and physical protein-protein interactions. In this work, we recapitulate previously described Nrf2 interactions in yeast and discover that Nrf2 interacts with the molecular chaperone Hsp90. Our work establishes yeast as a useful tool to study Nrf2 interactions and provides new insight into the crosstalk between the antioxidant response and the heat shock response.

The protein arginine methyltransferase PRMT1 promotes TBK1 activation through asymmetric arginine methylation.

TBK1 is an essential kinase for the innate immune response against viral infection. However, the key molecular mechanisms regulating the TBK1 activation remain elusive. Here, we identify PRMT1, a type I protein arginine methyltransferase, as an essential regulator of TBK1 activation. PRMT1 directly interacts with TBK1 and catalyzes asymmetric methylation of R54, R134, and R228 on TBK1. This modification enhances TBK1 oligomerization after viral infection, which subsequently promotes TBK1 phosphorylation and downstream type I interferon production. More important, myeloid-specific Prmt1 knockout mice are more susceptible to infection with DNA and RNA viruses than Prmt1fl/fl mice. Our findings reveal insights into the molecular regulation of TBK1 activation and demonstrate the essential function of protein arginine methylation in innate antiviral immunity.

TRIM31 facilitates K27-linked polyubiquitination of SYK to regulate antifungal immunity.

Spleen tyrosine kinase (SYK) is a non-receptor tyrosine kinase, which plays an essential role in both innate and adaptive immunity. However, the key molecular mechanisms that regulate SYK activity are poorly understood. Here we identified the E3 ligase TRIM31 as a crucial regulator of SYK activation. We found that TRIM31 interacted with SYK and catalyzed K27-linked polyubiquitination at Lys375 and Lys517 of SYK. This K27-linked polyubiquitination of SYK promoted its plasma membrane translocation and binding with the C-type lectin receptors (CLRs), and also prevented the interaction with the phosphatase SHP-1. Therefore, deficiency of Trim31 in bone marrow-derived dendritic cells (BMDCs) and macrophages (BMDMs) dampened SYK-mediated signaling and inhibited the secretion of proinflammatory cytokines and chemokines against the fungal pathogen Candida albicans infection. Trim31-/- mice were also more sensitive to C. albicans systemic infection than Trim31+/+ mice and exhibited reduced Th1 and Th17 responses. Overall, our study uncovered the pivotal role of TRIM31-mediated K27-linked polyubiquitination on SYK activation and highlighted the significance of TRIM31 in anti-C. albicans immunity.

Neuroprotective Effects of Hydrogen Sulfide Against Early Brain Injury and Secondary Cognitive Deficits Following Subarachnoid Hemorrhage.

Although the neuroprotective effects of hydrogen sulfide (H2 S) have been demonstrated in several studies, whether H2 S protects against early brain injury (EBI) and secondary cognitive dysfunction in subarachnoid hemorrhage (SAH) model remains unknown. This study was undertaken to evaluate the influence of H2 S on both acute brain injury and neurobehavioral changes as well as the underlying mechanisms after SAH. The H2 S donor, NaHS, was administered via an intraperitoneal injection at a dose of 5.6 mg/kg at 2 h, 6 h, 24 h, and 46 h after SAH in rat model. The results showed that NaHS treatment significantly improved brain edema and neurobehavioral function, and attenuated neuronal cell death in the prefrontal cortex, associated with a decrease in Bax/Bcl-2 ratio and suppression of caspase-3 activation at 48 h after SAH. NaHS also promoted phospho-Akt and phospho-ERK levels. Furthermore, NaHS treatment significantly enhanced the levels of brain-derived neurotrophic factor (BDNF) and phospho-CREB. Importantly, NaHS administration improved learning and memory performance in the Morris water maze test at 7 days post-SAH in rats. These results demonstrated that NaHS, as an exogenous H2 S donor, could significantly alleviate the development of EBI and cognitive dysfunction induced by SAH via Akt/ERK-related antiapoptosis pathway, and upregulating BDNF-CREB expression.

Resveratrol exerts antidepressant properties in the chronic unpredictable mild stress model through the regulation of oxidative stress and mTOR pathway in the rat hippocampus and prefrontal cortex.

Depression is one of the most common neuropsychiatric disorders and has been associated with oxidative stress and brain protein alterations. Resveratrol is a natural polyphenol enriched in Polygonum cuspidatum and has diverse biological activities including potent antidepressant-like effects. The present study attempts to explore the mechanisms underlying the antidepressant-like action of resveratrol by measuring oxidative stress parameters and phosphorylation of AKT/mTOR pathway in the rat hippocampus and prefrontal cortex (PFC) exposed to the chronic unpredictable mild stress (CUMS). Male Wistar rats were subjected to CUMS protocol for a period of 4 weeks to induce depressive-like behavior. The results showed that resveratrol treatment (80 mg/kg/i.p. 4 weeks) significantly reversed the CUMS-induced behavioral abnormalities (reduced sucrose preference, increased immobility time and decreased locomotor activity) and biochemical changes (increased lipid peroxidation and decreased superoxide dismutase). Additionally, CUMS exposure significantly decreased phosphorylation of Akt and mTOR in the hippocampus and PFC, while resveratrol treatment normalized these parameters. In conclusion, our study showed that resveratrol exerted antidepressant-like effects in CUMS rats, which was mediated in part by its antioxidant action, up-regulation of phosphor-Akt and mTOR levels in the hippocampus and PFC.

Resveratrol reverses chronic restraint stress-induced depression-like behaviour: Involvement of BDNF level, ERK phosphorylation and expression of Bcl-2 and Bax in rats.

Chronic stress occurs in everyday life and induces depression-like behaviors, associated with proteins alterations and apoptosis in brain. Resveratrol is a natural polyphenol enriched in polygonum cuspidatum and has diverse biological activities, including potent antidepressant-like effects. The aim of this study was to determine whether resveratrol administration influences chronic restraint stress (CRS) - induced depression-like behaviors and explores underlying mechanisms. Male Wistar rats were subjected to CRS protocol for a period of 3 weeks to induce depressive-like behavior. The results showed that resveratrol (80mg/kg/i.p) administrated for 3 weeks significantly reversed the CRS-induced behavioral abnormalities (reduced sucrose preference and increased immobility time) in stressed rats. CRS exposure significantly decreased BDNF levels and phosphorylation of extracellular signal-regulated kinase (pERK) in hippocampus and prefrontal cortex (PFC), accompanied by decreased Bcl-2 mRNA expression and increased Bax mRNA expression, while resveratrol treatment normalized these levels. All of these effects of resveratrol were essentially identical to that observed with fluoxetine. In conclusion, our studies showed that resveratrol exerted antidepressant-like effects in CRS rats, mediated in part by the apoptotic machinery and up-regulating BDNF and pERK levels in the brain region.

Preconditioning of bone marrow mesenchymal stem cells with hydrogen sulfide improves their therapeutic potential.

Bone marrow mesenchymal stem cells (BMSCs) transplantation has shown great promises for treating various brain diseases. However, poor viability of transplanted BMSCs in injured brain has limited the therapeutic efficiency. Hypoxia-ischemic injury is one of major mechanisms underlying the survival of transplanted BMSCs. We investigated the mechanism of preconditioning of BMSCs with hydrogen sulfide (H2S), which has been proposed as a novel therapeutic strategy for hypoxia-ischemic injury. In this study, we demonstrated that preconditioning of NaHS, a H2S donor, effectively suppressed hypoxia-ischemic-induced apoptosis whereby the rise in Bax/Bcl-2 ratio. Further analyses revealed Akt and ERK1/2 pathways were involved in the protective effects of NaHS. In addition, NaHS preconditioning increased secretion of BDNF and VEGF in BMSCs. Consistent with in vitro data, transplantation of NaHS preconditioned BMSCs in vivo further enhanced the therapeutic effects of BMSCs on neuronal injury and neurological recovery, associated with increased vessel density and upregulation of BDNF and VEGF in the ischemic tissue. These findings suggest that H2S could enhance the therapeutic effects of BMSCs. The underlying mechanisms might be due to enhanced capacity of BMSCs and upregulation of protective cytokines in the hypoxia tissue.

Resveratrol abrogates lipopolysaccharide-induced depressive-like behavior, neuroinflammatory response, and CREB/BDNF signaling in mice.

Current evidence supports that depression is accompanied by the activation of the inflammatory-response system, and overproduction of pro-inflammatory cytokines may play a role in the pathophysiology of depressive disorders. Resveratrol has anti-inflammatory, antioxidant and anti-depressant-like properties. Using an animal model of depression induced by a single administration of lipopolysaccharide (LPS), the present study investigated the effects of resveratrol on LPS-induced depressive-like behavior and inflammatory-response in adult mice. Our results showed that pretreatment with resveratrol (80mg/kg, i.p.) for 7 consecutive days reversed LPS-increased the immobility time in the forced swimming test and tail suspension test, and LPS-reduced sucrose preference test. Moreover, the antidepressant action of resveratrol was paralleled by significantly reducing the expression levels of pro-inflammatory cytokines, and up-regulating phosphorylated cAMP response-element-binding protein (pCREB)/brain-derived neurotrophic factor (BDNF) expression in prefrontal cortex (PFC) and hippocampus. In addition, resveratrol ameliorated LPS-induced NF-κB activation in the PFC and hippocampus. The results demonstrate that resveratrol may be an effective therapeutic agent for LPS-induced depressive-like behavior, partially due to its anti-inflammatory aptitude and by modulating pCREB and BDNF expression in the brain region of mice.