TRB3: an oxidant stress-induced pseudokinase with a potential to negatively modulate MCP-1 cytokine in diabetic nephropathy

Proteomics reveals that Di Dang decoction can regulate the Jak2/Stat5 signaling pathway and inhibit apoptosis by reducing the oxidative stress response in rats with acute intracerebral hemorrhagic stroke

ETHNOPHARMACOLOGICAL RELEVANCE

Di Dang decoction (DDD) is a prescription used for the treatment of cerebral hemorrhage. Its use is derived from the theory of typhoid fever, it has an obvious clinical effect and it has been used in the clinic for a long time. The results of early quantitative proteomics and targeted proteomics studies showed that the administration of high-dose DDD 7 days may regulate the expression of the proteins S100A8, S100A9, Col1a1 and Col1a2. The first 3 days after bleeding begins is the critical period for intervention, what occurs within approximately 3 days after AICH is unclear.

AIM OF THE STUDY

To explore the effects of Di Dang decoction (DDD) on the Jak2/Stat5 signaling pathway and apoptosis-related gene expression in rats with acute hemorrhagic stroke via the oxidative stress response by proteomics to reveal its neuroprotective mechanism.

MATERIALS AND METHODS

Ninety healthy Sprague-Dawley (SD) rats were randomly divided into the control, model, and low-, medium-, and high-dose DDD groups, with 18 rats in each group. An acute intracerebral hemorrhage (AICH) model was established by injecting autologous blood into the caudate nucleus. The low-, medium- and high-dose groups were intragastrically administered 0.15625 g/mL, 0.3125 g/mL and 0.625 g/mL DDD, respectively, for 1 or 3 days. The control and model groups were given the same amount of normal saline. Neurological deficits were evaluated by the modified neurological severity score (mNSS) test, brain water content was measured to assess brain tissue damage, and pathological changes in the lesion site were observed by hematoxylin and eosin (HE) staining. The cerebral cortex was selected for quantitative proteomics, and >1.2/1 and <1/1.2 were used as the thresholds for upregulated and downregulated proteins, respectively. KEGG pathway and Gene Ontology (GO) enrichment analyses of the differentially expressed proteins were conducted. The levels of the oxidative stress markers malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) were measured by enzyme-linked immunosorbent assay (ELISA). Western blotting was used to assess p-Jak2, Jak2, p-Stat5, Stat5, Bax, Bcl-2, and Caspase-3 protein expression.

RESULTS

Compared with the model group, the group treated with high-dose DDD for 3 days exhibited significant improvements in neurological defects, brain histopathology, and brain edema; reduced the level of MDA and significantly increased the levels of CAT and SOD; significantly decreased p-Jak2 and p-Stat5 protein expression and expression of the pro-apoptotic genes Bax and c-Caspase-3; and significantly increased expression of the anti-apoptotic gene Bcl-2 (all p＜0.05).

CONCLUSIONS

High-dose DDD administration for 3 days reduces the oxidative stress response, regulates the Jak2/Stat5 signaling pathway and inhibits apoptosis to exert a neuroprotective effect in rats with acute hemorrhagic stroke.

Secretome-Mediated Interactions with Intestinal Epithelial Cells: A Role for Secretome Components from Lactobacillus rhamnosus R0011 in the Attenuation of Salmonella enterica Serovar Typhimurium Secretome and TNF-α-Induced Proinflammatory Responses

Recent evidence suggests that lactic acid bacteria communicate with host cells via secretome components to influence immune responses but less is known about gut-pathogen secretomes, impact of lactic acid bacteria secretomes on host-pathogen interactions, and the mechanisms underlying these interactions. Genome-wide microarrays and cytokine profiling were used to interrogate the impact of the Lactobacillus rhamnosus R0011 secretome (LrS) on TNF-α and Salmonella enterica subsp. enterica serovar Typhimurium secretome (STS)-induced outcomes in human intestinal epithelial cells. The LrS attenuated both TNF-α- and STS-induced gene expression involved in NF-κB and MAPK activation, as well as expression of genes involved in other immune-related signaling pathways. Specifically, the LrS induced the expression of dual specificity phosphatase 1 (DUSP1), activating transcription factor 3 (ATF3), and tribbles pseudokinase 3 (TRIB3), negative regulators of innate immune signaling, in HT-29 intestinal epithelial cells challenged with TNF-α or STS. TNF-α- and STS-induced acetylation of H3 and H4 histones was attenuated by the LrS, as was the production of TNF-α- and STS-induced proinflammatory cytokines and chemokines. Interestingly, the LrS induced production of macrophage migration inhibitory factor (MIF), a cytokine involved in host-microbe interactions at the gut interface. We propose that the LrS attenuates proinflammatory mediator expression through increased transcription of negative regulators of innate immune activity and changes in global H3 and H4 histone acetylation. To our knowledge, these findings provide novel insights into the complex multifaceted mechanisms of action behind secretome-mediated interdomain communication at the gut-mucosal interface.

Neuroprotective Effects of Anthraquinones from Rhubarb in Central Nervous System Diseases

Rhubarb is a well-known traditional Chinese medicine; it has been used in China for thousands of years. Rhubarb anthraquinones are the major medicinal ingredients derived from rhubarb including emodin, aloe-emodin, chrysophanol, rhein, physcion, and danthron. These different anthraquinone derivatives alone or in combination play a therapeutic role in central nervous system diseases (CNSD), such as cerebral ischemic stroke, intracerebral hemorrhage, traumatic brain injury, brain tumor, Alzheimer's disease, depression, and others. We review the experimental studies on these six anthraquinones in the treatment of CNSD by consulting literature published in the last 20 years in PubMed and then give a future perspective on it. In the end of this paper some deficiencies related to these studies also have been pointed out.

Metallothionein Preserves Akt2 Activity and Cardiac Function via Inhibiting TRB3 in Diabetic Hearts

Cardiac insulin resistance is a key pathogenic factor for diabetic cardiomyopathy (DCM), but the mechanism remains largely unclear. We found that diabetic hearts exhibited decreased phosphorylation of total Akt and isoform Akt2 but not Akt1 in wild-type (WT) male FVB mice, which was accompanied by attenuation of Akt downstream glucose metabolic signal. All of these signal changes were not observed in metallothionein cardiac-specific transgenic (MT-TG) hearts. Furthermore, insulin-induced glucose metabolic signals were attenuated only in WT diabetic hearts. In addition, diabetic hearts exhibited increased Akt-negative regulator tribbles pseudokinase 3 (TRB3) expression only in WT mice, suggesting that MT may preserve Akt2 function via inhibiting TRB3. Moreover, MT prevented tert-butyl hydroperoxide (tBHP)-reduced insulin-stimulated Akt2 phosphorylation in MT-TG cardiomyocytes, which was abolished by specific silencing of Akt2. Specific silencing of TRB3 blocked tBHP inhibition of insulin-stimulated Akt2 phosphorylation in WT cardiomyocytes, whereas overexpression of TRB3 in MT-TG cardiomyocytes and hearts abolished MT preservation of insulin-stimulated Akt2 signals and MT prevention of DCM. Most importantly, supplementation of Zn to induce MT preserved cardiac Akt2 signals and prevented DCM. These results suggest that diabetes-inhibited cardiac Akt2 function via TRB3 upregulation leads to aberrant cardiac glucose metabolism. MT preservation of cardiac Akt2 function by inhibition of TRB3 prevents DCM.

Prolonged insulin treatment sensitizes apoptosis pathways in pancreatic β cells

Insulin resistance results from impaired insulin signaling in target tissues that leads to increased levels of insulin required to control plasma glucose levels. The cycle of hyperglycemia and hyperinsulinemia eventually leads to pancreatic cell deterioration and death by a mechanism that is yet unclear. Insulin induces ROS formation in several cell types. Furthermore, death of pancreatic cells induced by oxidative stress could be potentiated by insulin. Here, we investigated the mechanism underlying this phenomenon. Experiments were done on pancreatic cell lines (Min-6, RINm, INS-1), isolated mouse and human islets, and on cell lines derived from nonpancreatic sources. Insulin (100nM) for 24h selectively increased the production of ROS in pancreatic cells and isolated pancreatic islets, but only slightly affected the expression of antioxidant enzymes. This was accompanied by a time- and dose-dependent decrease in cellular reducing power of pancreatic cells induced by insulin and altered expression of several ER stress response elements including a significant increase in Trb3 and a slight increase in iNos The effect on iNos did not increase NO levels. Insulin also potentiated the decrease in cellular reducing power induced by H2O2 but not cytokines. Insulin decreased the expression of MCL-1, an antiapoptotic protein of the BCL family, and induced a modest yet significant increase in caspase 3/7 activity. In accord with these findings, inhibition of caspase activity eliminated the ability of insulin to increase cell death. We conclude that prolonged elevated levels of insulin may prime apoptosis and cell death-inducing mechanisms as a result of oxidative stress in pancreatic cells.

Emodin-induced microglial apoptosis is associated with TRB3 induction

Emodin (1,3,8-trihydroxy-6-methylanthraquinone), a natural anthraquinone compound isolated from the rhizome of rhubarb, has been reported to treat brain injury after intracerebral hemorrhage. Treatment of neurons with emodin is able to decrease glutamate excitotoxicity, modulate calcium homeostasis, and induce Bcl-2 expression. However, the effects of emodin on the brain-resident innate immune cells are unclear. In the present study, the mouse microglial cell line, BV-2, was selected to investigate the effects of emodin on microglial activation and apoptosis. Cell viability and apoptosis were sequentially measured with the CellTiter-Glo Luminescent Cell Viability Assay, YOPRO-1 and Caspase-Glo 3/7 Assay Systems. The degree of microglial activation was evaluated using quantitative RT-PCR to measure expression of inflammatory markers. Treatment of BV-2 cells with emodin caused caspase-mediated apoptosis in a dose-dependent manner, and emodin augmented LPS-induced microglial apoptosis to repress inflammatory activation. In response to emodin treatment, reactive oxygen species (ROS) production was increased, and TRB3 was markedly activated. siRNA knockdown of TRB3 attenuated emodin-induced microglial apoptosis. Ectopic overexpression of TRB3 decreased cell viability and was associated with dysregulation of the prosurvival Akt/FOXO3 pathway. These results demonstrate that emodin induces BV-2 cell apoptosis through TRB3 and consequently eliminates inflammatory microglia. Our findings provide a novel molecular basis through which emodin exerts neuroprotective effects, treating brain injury after intracerebral hemorrhage.