Search

Ubiquitination plays essential roles in eukaryotic cellular processes. The effector protein CteC from Chromobacterium violaceumblocks host ubiquitination by mono-ADP-ribosylation of ubiquitin (Ub) at residue T66. However, the structural basis for this modification is unknown. Here we report three crystal structures of CteC in complexes with Ub, NAD+or ADP-ribosylated Ub, which represent different catalytic states of CteC in the modification. CteC adopts a special ‘D-E’ catalytic motif for catalysis and binds NAD+in a half-ligand binding mode. The specific recognition of Ub by CteC is determined by a relatively separate Ub-targeting domain and a long loop L6, not the classic ADP-ribosylating turn–turn loop. Structural analyses with biochemical results reveal that CteC represents a large family of poly (ADP-ribose) polymerase (PARP)-like ADP-ribosyltransferases, which harbors chimeric features from the R-S-E and H-Y-E classes of ADP-ribosyltransferases. The family of CteC-like ADP-ribosyltransferases has a common ‘D-E’ catalytic consensus and exists extensively in bacteria and eukaryotic microorganisms.

Geniposide (GEN), a main compound extracted from Gardenia jasminoidesfruit, has various biological activities including anti-inflammation, cellular damage alleviation, neuroprotection, and others. However, the effect of GEN on oxidative stress in hepatic cells is yet to be investigated. Our study uncovered that GEN eliminated excess intracellular free radicals by activating the Nrf2/ARE signaling pathway in H2O2-treated hepatocytes, while the protective effect was blocked by ML385 (an inhibitor of Nrf2). Moreover, H2O2led to upregulation of miR-27b-3p in L02 cells, which was restrained by GEN. Overexpression of miR-27b-3p greatly weakened the antioxidant capacity of GEN in hepatocytes via directly targeting the Nrf2 gene. Our findings indicated that GEN treatment recovered H2O2-induced oxidative stress via targeting miR-27b-3p and thereby enhanced the antioxidant capacity by stimulating nuclear translocation and accumulation of Nrf2. These findings suggest that inhibition of miR-27b-3p to activate the Nrf2/ARE pathway by GEN is a potential alternative for hepatic oxidative damage alleviation.

Microplastics derived from plastic waste have emerged as a pervasive environmental pollutant with potential transfer and accumulation through the food chain, thus posing risks to both ecosystems and human health. The gut microbiota, tightly intertwined with metabolic processes, exert substantial influences on host physiology by utilizing dietary compounds and generating bacterial metabolites such as tryptophan and bile acid. Our previous studies have demonstrated that exposure to microplastic polystyrene (PS) disrupts the gut microbiota and induces colonic inflammation. Meanwhile, intervention with cyanidin-3-O-glucoside (C3G), a natural anthocyanin derived from red bayberry, could mitigate colonic inflammation by reshaping the gut bacterial composition. Despite these findings, the specific influence of gut bacteria and their metabolites on alleviating colonic inflammation through C3G intervention remains incompletely elucidated. Therefore, employing a C57BL/6 mouse model, this study aims to investigate the mechanisms underlying how C3G modulates gut bacteria and their metabolites to alleviate colonic inflammation. Notably, our findings demonstrated the efficacy of C3G in reversing the elevated levels of pro-inflammatory cytokines (IL-6, IL-1β, and TNF-α) and the upregulation of mRNA expression (Il-6, Il-1β, and Tnf-α) induced by PS exposure. Meanwhile, C3G effectively inhibited the reduction in levels (IL-22, IL-10, and IL-4) and the downregulation of mRNA expression (Il-22, Il-10, and Il-4) of anti-inflammatory cytokines induced by PS exposure. Moreover, PS-induced phosphorylation of the transcription factor NF-κB in the nucleus, as well as the increased level of protein expression of iNOS and COX-2 in the colon, were inhibited by C3G. Metabolisms of gut bacterial tryptophan and bile acids have been extensively implicated in the regulation of inflammatory processes. The 16S rRNA high-throughput sequencing disclosed that PS treatment significantly increased the abundance of pro-inflammatory bacteria (Desulfovibrio, norank_f_Oscillospiraceae, Helicobacter, and Lachnoclostridium) while decreasing the abundance of anti-inflammatory bacteria (Dubosiella, Akkermansia, and Alistipes). Intriguingly, C3G intervention reversed these pro-inflammatory changes in bacterial abundances and augmented the enrichment of bacterial genes involved in tryptophan and bile acid metabolism pathways. Furthermore, untargeted metabolomic analysis revealed the notable upregulation of metabolites associated with tryptophan metabolism (shikimate, l-tryptophan, indole-3-lactic acid, and N-acetylserotonin) and bile acid metabolism (3b-hydroxy-5-cholenoic acid, chenodeoxycholate, taurine, and lithocholic acid) following C3G administration. Collectively, these findings shed new light on the protective effects of dietary C3G against PS exposure and underscore the involvement of specific gut bacterial metabolites in the amelioration of colonic inflammation.

ABSTRACTFine particulate matter (PM2.5) in the atmosphere is easily accompanied by toxic and harmful substances, causing serious harm to human health, including cognitive impairment. Vitamin B12 (VitB12) is an essential micronutrient that is synthesized by bacteria and contributes to neurotransmitter synthesis as a nutrition and signaling molecule. However, the relationship between VitB12 attenuation of cognitive impairment and intestinal microbiota regulation in PM2.5exposure has not been elucidated. In this study, we demonstrated that PM2.5caused behavioral defects and neuronal damage in Caenorhabditis elegans(C. elegans), along with significant gene expression changes in neurotransmitter receptors and a decrease in VitB12 content, causing behavioral defects and neuronal damage in C. elegans. Methylcobalamin (MeCbl), a VitB12 analog, alleviated PM2.5-induced neurotoxicity in C. elegans. Moreover, using in vivoand in vitromodels, we discovered that long-term exposure to PM2.5led to changes in the structure of the gut microbiota, resulting in an imbalance of the VitB12-associated metabolic pathway followed by cognitive impairment. MeCbl supplementation could increase the diversity of the bacteria, reduce harmful substance contents, and restore the concentration of short-chain fatty acids (SCFAs) and neurotransmitters to the level of the control group to some degree. Here, a new target to mitigate the harm caused by PM2.5was discovered, supplying MeCbl for relieving intestinal and intracellular neurotransmitter disorders. Our results also provide a reference for the use of VitB12 to target the adjustment of the human intestinal microbiota to improve metabolic disorders in people exposed to PM2.5.

Since 2012, as a renewable energy collection and utilization technology, the triboelectric nanogenerator (TENG) has ushered in a new wave in the development of wearable electronic devices, portable self-powered systems, and human-computer interfaces. Electrospun fibers have the advantages of good uniformity, large porosity, and large surface area, which provide a new choice for the triboelectric layer of TENG and can significantly improve the triboelectric effect and wearability of TENG. In this review, the structures and fundamental mechanisms of TENGs were introduced, along with the introduction of the preparation and influencing factors of the formation of electrospun fibers and their advantages as friction electrode of TENGs. More emphasis was placed on the applications of electrospun nanofiber based TENGs, such as acoustic sensors, human motion sensors, anti-counterfeiting and encryption, gas detection, and air filters. Furthermore, the electrospun nanofibers mixed with 2D nanomaterials as electrodes to improve the output performance of TENGs were also discussed, which can contribute to promoting further development of the field.

Microencapsulation is a promising and feasible method to help probiotics against adverse situation and overcome storage instability. In this study, we prepared Bacillus smithiiXY1 microcapsules by spray drying. Firstly, wall materials of the microcapsules were screened and the ratio between wall materials and protective agent was optimized. The results showed that 9% gum arabic and 5% soluble starch along with 4% skim milk powder were the best condition for spray drying through response surface method. Through scanning electron microscope (SEM), bacteria were successfully encapsuled in the wall materials and microcapsules presented complete structure without cracks. Compared to non-encapsulated bacteria, encapsulation increased tolerance of B. smithiiXY1 in gastrointestinal environment, improved shelf time and showed a better effect on alleviating intestine inflammation of zebrafish induced by dextran dulfate sodium (DSS). Thus, this encapsulation approach may have the potential application for improving efficacy of B. smithiiXY1 and other probiotics.

Curcumin (CUR), the main compound extracted from Curcuma longa, has various biological actions, including hepatoprotective, anti-infective, anti-inflammatory, antioxidant, and neurotrophic properties. But it has not yet been clarified how CUR affects the accumulation of fatty in hepatic cells. Our study uncovered that CUR decreased the lipid deposition in free fat acids (FFAs)-treated hepatocytes, which could be blocked by Compound C (an AMPK inhibitor). This result suggests that protective effect was associated with the AMPK pathway activation. MiR-3666 directly targets the AMPK gene, and overexpression of miR-3666 greatly weakens the hypolipidemic effect of CUR. Our results showed that CUR reduced FFAs-induced lipid deposition by targeting miR-3666. This boosted AMPK phosphorylation and inhibited its downstream targets, including ACC and SREBP1. These findings together confirm that CUR-mediated inhibition of miR-3666 to activate the AMPK pathway is a potential alternative for alleviation of hepatic lipid deposition.

Fructus Gardeniae (FG) is the dried ripe fruit of Gardenia jasminoidesEllis, having beneficial effects for human health. In this study, we discovered that the most relevant pathway influenced by Fructus Gardeniae extract (FGE) is lipid metabolism according to the analysis of network pharmacology. Furthermore, the protective effect of FGE against palmitic acid-induced lipotoxicity was investigated. In L02 cells, FGE significantly promoted cellular proliferation after being treated with palmitic acid, and reduced the accumulation of lipid droplets and triglyceride level. Palmitic acid led to an increase of ROS content, which was reduced by FGE. Additionally, FGE could facilitate Nrf2 localized to nuclear and followed by activating its downstream targets. ML385 (a Nrf2 inhibitor) treatment further proved that FGE attenuated lipotoxicity through regulating Nrf2/ARE pathway. Consequently, we demonstrated for the first time FGE could be regarded as potential functional food materials for hepatic protection.

Chlorogenic acid (CGA) is a phenylpropanoid compound in chrysanthemum, which has a variety of biological activities. Nevertheless, CGA has not yet been studied concerning oxidative stress in hepatocytes. Our research aims to investigate whether chlorogenic acid can improve hepatic oxidative stress, and further illustrated its detailed mechanism. The results of free radicals measurement and Western blot showed that CGA suppressed the activation of JNK (c-Jun NH2-teminal kinase) signaling pathway by ameliorating endoplasmic reticulum stress in H2O2-treated hepatocytes, thereby eliminating excess intracellular free radicals. In addition, through RT-qPCR, we found that miR-199a-5p down-regulated in H2O2-induced L02 cells, which was restored by CGA. By inhibiting the expression of miR-199a-5p to promote the transcription of GRP78 gene, the antioxidant capacity of CGA was greatly weakened in hepatocytes. Our findings suggest that CGA treatment alleviated the H2O2-induced oxidative stress by targeting miR-199a-5p, thereby ameliorating ER stress and inhibiting JNK phosphorylation for antioxidant capacity enhancement. Based on our available results, CGA may be an alternative compound to mitigate hepatic oxidative damage through the miR-199a-5p/GPR78 axis.