Tat-DJ-1 enhances cell survival by inhibition of oxidative stress, NF-κB and MAPK activation in HepG2 cells

Potential of oligonucleotide- and protein/peptide-based therapeutics in the management of toxicant/stressor-induced diseases

Exposure to toxicants/stressors has been linked to the development of many human diseases. They could affect various cellular components, such as DNA, proteins, lipids, and non-coding RNAs (ncRNA), thereby triggering various cellular pathways, particularly oxidative stress, inflammatory responses, and apoptosis, which can contribute to pathophysiological states. Accordingly, modulation of these pathways has been the focus of numerous investigations for managing related diseases. The involvement of various ncRNAs, such as small interfering RNA (siRNA), microRNAs (miRNA), and long non-coding RNAs (lncRNA), as well as various proteins and peptides in mediating these pathways, provides many target sites for pharmaceutical intervention. In this regard, various oligonucleotide- and protein/peptide-based therapies have been developed to treat toxicity-induced diseases, which have shown promising results in vitro and in vivo. This comprehensive review provides information about various aspects of toxicity-related diseases including their causing factors, main underlying mechanisms and intermediates, and their roles in pathophysiological states. Particularly, it highlights the principles and mechanisms of oligonucleotide- and protein/peptide-based therapies in the treatment of toxicity-related diseases. Furthermore, various issues of oligonucleotides and proteins/peptides for clinical usage and potential solutions are discussed.

Proteomic analysis of aqueous humor reveals novel regulators of diabetic macular edema

Diabetic macular edema (DME) is the most common cause of blindness in patients with diabetic retinopathy. To investigate the proteomic profiles of the aqueous humor (AH) of individuals with diabetic macular edema (DME), AH samples were collected from patients with non-diabetes mellitus (NDM), DM, nonproliferative diabetic retinopathy (NPDR), and DME. We performed comparative proteomic analyses using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and bioinformatics analyses. We identified 425 proteins in these AH samples, of which 113 showed changes in expression in DME compared with NDM, 95 showed changes in expression in DME vs. DM, and 84 showed changes in expression in DME compared with NPDR. The bioinformatics analysis suggested that DME is closely associated with platelet degranulation, oxidative stress-related pathway, and vascular-related pathways. Upregulation of haptoglobin (HP) and downregulation of fibrillin 1 (FBN1) were validated by ELISA. Receiver operating characteristic (ROC) analysis showed that HP and FBN1 could distinguish DME from NPDR with areas under the curve of 0.987 (p = 0.00608) and 0.791 (p = 0.00629), respectively. The findings provide potential clues for further analysis of the molecular mechanisms and the development of new treatments for DME. HP and FBN1 may be potential key proteins and therapeutic targets in human DME. The proteomics dataset generated has been deposited to the ProteomeXchange/iProX Consortium with Identifier: PXD033404/IPX0004353001.

Cell-penetrating peptide-mediated delivery of therapeutic peptides/proteins to manage the diseases involving oxidative stress, inflammatory response and apoptosis

OBJECTIVES

Peptides and proteins represent great potential for modulating various cellular processes including oxidative stress, inflammatory response, apoptosis and consequently the treatment of related diseases. However, their therapeutic effects are limited by their inability to cross cellular barriers. Cell-penetrating peptides (CPPs), which can transport cargoes into the cell, could resolve this issue, as would be discussed in this review.

KEY FINDINGS

CPPs have been successfully exploited in vitro and in vivo for peptide/protein delivery to treat a wide range of diseases involving oxidative stress, inflammatory processes and apoptosis. Their in vivo applications are still limited due to some fundamental issues of CPPs, including nonspecificity, proteolytic instability, potential toxicity and immunogenicity.

SUMMARY

Totally, CPPs could potentially help to manage the diseases involving oxidative stress, inflammatory response and apoptosis by delivering peptides/proteins that could selectively reach proper intracellular targets. More studies to overcome related CPP limitations and confirm the efficacy and safety of this strategy are needed before their clinical usage.

Antrodia camphorata polysaccharide improves inflammatory response in liver injury via the ROS/TLR4/NF-κB signal

Antrodia Camphorata Polysaccharide (ACP) refers to a kind of polysaccharide extracted from the natural porous fungus Antrodia camphorata. This study investigated the mechanism of action of ACP in protecting the liver. The results showed that ACP suppressed the LPS‐induced KC cell activation, reduced the expression of inflammatory factors, increased the SOD level and suppressed ROS expression. In addition, N‐acetylcysteine (NAC) was adopted for pre‐treatment to suppress ROS. The results indicated that NAC synergistically exerted its effect with ACP, suggesting that ACP played its role through suppressing ROS. Further detection revealed that ACP activated the Nrf2 signal. It was discovered in the mouse model that, ACP effectively improved liver injury in mice, decreased ALT and AST levels, and suppressed the expression of inflammatory factors. This study suggests that ACP can exert its effect against oxidative stress via the Nrf2‐ARE signalling, which further improves the production of ROS and the activation of TLR4‐NF‐κB signalling, and protects the liver against liver injury.

Tat-indoleamine 2,3-dioxygenase 1 elicits neuroprotective effects on ischemic injury

It is well known that oxidative stress participates in neuronal cell death caused production of reactive oxygen species (ROS). The increased ROS is a major contributor to the development of ischemic injury. Indoleamine 2,3-dioxygenase 1 (IDO-1) is involved in the kynurenine pathway in tryptophan metabolism and plays a role as an anti-oxidant. However, whether IDO-1 would inhibit hippocampal cell death is poorly known. Therefore, we explored the effects of cell permeable Tat-IDO-1 protein against oxidative stress-induced HT-22 cells and in a cerebral ischemia/reperfusion injury model. Transduced Tat-IDO-1 reduced cell death, ROS production, and DNA fragmentation and inhibited mitogen-activated protein kinases (MAPKs) activation in H₂O₂ exposed HT-22 cells. In the cerebral ischemia/reperfusion injury model, Tat-IDO-1 transduced into the brain and passing by means of the blood-brain barrier (BBB) significantly prevented hippocampal neuronal cell death. These results suggest that Tat-IDO-1 may present an alternative strategy to improve from the ischemic injury.

Antiapoptotic activity of Chlamydia trachomatis Pgp3 protein involves activation of the ERK1/2 pathway mediated by upregulation of DJ-1 protein

Chlamydia trachomatis has evolved strategies to prevent host cell apoptosis to evade the host immune defense. However, the precise mechanisms of antiapoptotic activity of C. trachomatis still need to be clarified. Pgp3, one of eight plasmid proteins of C. trachomatis, has been identified to be closely associated with chlamydial virulence. In this study, we attempted to explore the effects and the mechanisms of Pgp3 protein on apoptosis in HeLa cells; the results showed that Pgp3 increased Bcl-2/Bax ratio and prevented caspase-3 activation to suppress apoptosis induced by TNF-α and cycloheximide (CHX) through ERK1/2 pathway activation. Downregulation of DJ-1 with siRNA-DJ-1(si-DJ-1) reduced ERK1/2 phosphorylation and elevated apoptotic rate significantly in Pgp3-HeLa cells. However, inhibition of ERK1/2 signal pathway with ERK inhibitor PD98059 had little effect on DJ-1 expression. These findings confirm that plasmid protein Pgp3 contributes to apoptosis resistance through ERK1/2 signal pathway mediated by upregulation of DJ-1 expression. Therefore, the present study provided novel insights into the role of Pgp3 in apoptosis and suggested that manipulation of the host apoptosis response could be a new approach for the prevention and treatment of C. trachomatis infection.

DJ-1/PARK7 inhibits high glucose-induced oxidative stress to prevent retinal pericyte apoptosis via the PI3K/AKT/mTOR signaling pathway

Reactive oxygen species (ROS) act through multiple pathways to induce apoptosis of retinal capillary pericytes, which is an early marker and the primary cause of the progression of diabetic retinopathy. However, the specific molecular mechanisms behind ROS-induced retinal capillary pericyte loss in diabetic retinopathy remains elusive. In this study, we investigated the molecular regulation and effects of DJ-1/PARK7 on oxidative stress and injury of rat retinal pericytes (RRPs). To perform the research, RRPs were isolated from rat retina and cultured in medium with for 2 days: control group (5.6 mM glucose), high glucose group (30 mM glucose), hypertonic group (5.6 mM glucose + 24.4 mM mannitol). We found decreased expression of DJ-1 and increased apoptosis of RRPs in high glucose group. To further study the role of DJ-1, four groups were divided as follows: normal control group (5.6 mM glucose), high glucose (30 mM glucose), empty vector control group (pcDNA3.1,30 mM glucose), DJ-1 overexpression group (pcDNA3.1-myc-DJ-1,30 mM glucose). DJ-1, P53, p-P53, cleaved caspase-3, manganese superoxide dismutase (MnSOD), catalase (CAT) and PI3K/Akt/mTOR signaling pathway in each group was detected by Western Blot. RRPs apoptosis was detected by Terminal-deoxynucleoitidyl Transferase mediated Nick End Labeling (TUNEL) and 4'6- diamidino-2-phenylindole (DAPI). Mitochondrial function was detected by jc-1 and fluorescent probes DCFH-DA was used to determine reactive oxygen species (ROS). We found that high glucose (30 mM) lasting two days can induce significant apoptosis of RRPs, increase ROS production and expressions of p-p53 and active caspase-3, impair mitochondrial function, decrease the activities of MnSOD and CAT, and decrease expression of DJ-1, p-AKT and p-mTOR. In contrast, DJ-1/PARK7 overexpression significantly increases expression of DJ-1, p-AKT and p-mTOR, increases expression and activities of MnSOD and CAT, improves mitochondrial function, decreases expression of apoptotic gene protein p-p53 and active caspase-3, reduces ROS production and reduces the apoptotic rate of RRPs induced by high glucose. These results suggest that DJ-1 may play a role in protecting RRPs from high glucose induced-oxidative injury. DJ-1 might improve mitochondrial function, inhibit ROS production and enhance antioxidant capacity to reduce apoptosis of retinal pericytes through the PI3K/AKT/mTOR signaling pathway which may be related to early pathogenesis of diabetic retinopathy.

Niacin and Selenium Attenuate Brain Injury After Cardiac Arrest in Rats by Up-Regulating DJ-1-Akt Signaling

OBJECTIVES

To determine neuroprotective effects and mechanism of the combination therapy of niacin and selenium in cardiac arrest rats.

DESIGN

Prospective laboratory study.

SETTING

University laboratory.

SUBJECTS

Rat cortex neurons and male Sprague-Dawley rats (n = 68).

INTERVENTIONS

In rat cortex neurons underwent 90 minutes of oxygen-glucose deprivation and 22.5 hours of reoxygenation, effects of the combination therapy of niacin (0.9 mM) and selenium (1.5 μM) were investigated. The role of DJ-1 was determined using DJ-1 knockdown cells. In cardiac arrest rats, posttreatment effects of the combination therapy of niacin (360 mg/kg) and selenium (60 μg/kg) were evaluated.

MEASUREMENTS AND MAIN RESULTS

In oxygen-glucose deprivation and 22.5 hours of reoxygenation cells, combination therapy synergistically activated the glutathione redox cycle by a niacin-induced increase in glutathione reductase and a selenium-induced increase in glutathione peroxidase activities and reduced hydrogen peroxide level. It increased phosphorylated Akt and intranuclear Nuclear factor erythroid 2-related factor 2 expression and attenuated neuronal injury. However, these benefits were negated by DJ-1 knockdown. In cardiac arrest rats, combination therapy increased DJ-1, phosphorylated Akt, and intranuclear nuclear factor erythroid 2-related factor 2 expression, suppressed caspase 3 cleavage, and attenuated histologic injury in the brain tissues. It also improved the 7-day Neurologic Deficit Scales from 71.5 (66.0-74.0) to 77.0 (74.-80.0) (p = 0.02).

CONCLUSIONS

The combination therapy of clinically relevant doses of niacin and selenium attenuated brain injury and improved neurologic outcome in cardiac arrest rats. Its benefits were associated with reactive oxygen species reduction and subsequent DJ-1-Akt signaling up-regulation.

The protective effect of glutaredoxin 1/DJ-1/HSP70 signaling in renal tubular epithelial cells injury induced by ischemia

AIMS

Gluaredoxin1 (GRX1) is an important protein of the cellular antioxidant defense system, but its role in renal epithelial cell injury caused by ischemia remains unclear. In this study, we aimed to gain insight into the role of GRX1 in HK-2 cells with oxygen glucose deprivation (OGD) injury, which served as an in vitro cell model of renal epithelial cell ischemic injury. We investigated the underlying regulation of GRX1, DJ-1, and HSP70 as well as the role of the GRX1/DJ-1/HSP70 signaling pathway in this model.

MATERIALS AND METHODS

The protein and mRNA expressions were measured by Western blot and qRT-PCR assays, respectively. GRX1 was overexpressed by transfection of pcDNA.3.1-GRX1 and DJ-1 was inhibited by transfection with DJ-1 siRNA. Cell apoptosis, caspase-3 activity, lactate dehydrogenase (LDH) leakage, or superoxide dismutase (SOD) content was tested by the related detection kit. Reactive oxygen species (ROS) level was detected via carboxy-H₂DCF-DA.

KEY FINDINGS

We found that GRX1 was distinctly down-regulated in HK-2 cells after incubation under the OGD condition. GRX1 overexpression markedly constrained cell apoptosis, caspase-3 activity, LDH leakage, and the ROS level, while SOD content was elevated. GRX1 up-regulation increased DJ-1 and HSP70 protein expression, while DJ-1 inhibition significantly offset the effect of GRX1 overexpression on HSP70, indicating that GRX1 could regulate HSP70 via control of DJ-1. Moreover, we observed that HSP70 inhibition removed the constraints imposed by GRX1 overexpression on ROS level, LDH leakage, and caspase-3 activity.

SIGNIFICANCE

Overall, this study showed that GRX1 minimizes cell injury and apoptosis in HK-2 cells under OGD conditions via regulation of DJ-1 and HSP70 expression.

Protective effects of Tat-DJ-1 protein against streptozotocin-induced diabetes in a mice model

A major feature of type 1 diabetes mellitus (T1DM) is hyperglycemia and dysfunction of pancreatic β-cells. In a previous study, we have shown that Tat-DJ-1 protein inhibits pancreatic RINm5F β-cell death caused by oxidative stress. In this study, we examined effects of Tat-DJ-1 protein on streptozotocin (STZ)-induced diabetic mice. Wild type (WT) Tat-DJ-1 protein transduced into pancreas where it markedly inhibited pancreatic β-cell destruction and regulated levels of serum parameters including insulin, alkaline phosphatase (ALP), and free fatty acid (FFA) secretion. In addition, transduced WT Tat-DJ-1 protein significantly inhibited the activation of NF-κB and MAPK (ERK and p38) expression as well as expression of COX-2 and iNOS in STZ exposed pancreas. In contrast, treatment with C106A mutant Tat-DJ-1 protein showed no protective effects. Collectively, our results indicate that WT Tat-DJ-1 protein can significantly ameliorate pancreatic tissues in STZ-induced diabetes in mice. [BMB Reports 2018; 51(7): 362-367].

DJ‑1 alleviates high glucose‑induced endothelial cells injury via PI3K/Akt‑eNOS signaling pathway

Hyperglycemia mediated endothelial cells (ECs) injury is closely associated with diabetic vascular complications. It was revealed that DJ‑1 possesses cellular protective effects by suppressing oxidative stress. The present study aimed to investigate the beneficial effects of DJ‑1 on high glucose (HG)‑induced human umbilical vein endothelial cell (HUVEC) injury and to elucidate its underlying mechanisms. HUVECs were incubated under 5.5 mM (control group) or 25 mM D‑glucose (HG group) and then transfected with recombinant adenoviral vectors to overexpression of DJ‑1. Cell proliferation and apoptosis were measured using the EdU incorporation assay and flow cytometry with Annexin V-FITC/propidium iodide double staining, respectively. Apoptotic‑related proteins were determined using western blot analysis. Reactive oxygen species (ROS) production, lactate dehydrogenase (LDH) and nitric oxide (NO) levels, the content of malondialdehyde (MDA), and the activities of superoxide dismutase (SOD) were measured. Results demonstrated that overexpression of DJ‑1 promoted cell proliferation and inhibited HUVECs apoptosis stimulated by HG. DJ‑1 also suppressed the HG‑induced reduction in the Bcl‑2/Bax ratio and HG activated ROS generation in HUVECs. Furthermore, HG significantly increased the levels of LDH and MDA, and reduced the level of SOD; however, these effects were reversed by Ad‑DJ‑1 transfection. Furthermore, the cellular protective effect of overexpression of DJ‑1 enhanced p‑Akt/Akt ratio, eNOS activation and NO production, and these trends were partially reversed by a phosphatidylinositol‑4,5‑bisphosphate 3‑kinase (PI3K) inhibitor (LY294002). Taken together, the present study highlighted the involvement of DJ‑1 in HG‑related EC injury and identified that DJ‑1 exerts a cellular protective effect in HUVECs exposed to HG induced oxidative stress via activation of the PI3K/Akt‑eNOS signaling pathway.

Polysaccharides of Dendrobium officinale Kimura & Migo protect gastric mucosal cell against oxidative damage-induced apoptosis in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Dendrobium officinale Kimura & Migo (DO) is a valuable Traditional Chinese Medicine to nourish stomach, in which polysaccharides are identified as active ingredients. However, limited scientific evidences have been reported on the gastroprotective efficacy of DO. The aim of the current study was to investigate the protective effects and underlying mechanism of polysaccharides from DO(DOP) on gastric mucosal injury.

MATERIAL AND METHODS

For in vitro study, HFE145 cells were pretreated with DOP before induction of cell apoptosis by H₂O₂. Cell apoptosis and related proteins expression were detected. In the in vivo study, absolute ethanol was administered orally to induce gastric mucosal injury in rat. The gastric mucosal injury area and histological examination were used to evaluate the effects of DOP treatment on the recovery of the gastric mucosal injury.

RESULTS

H₂O₂ treatment for 6h significantly induced cell apoptosis in HFE145 cells. However, the destructive effects of H₂O₂ on HFE 145 cells could be reversed by the pretreatment with DOP. The increased ROS level induced by H₂O₂ for 4h was reduced after DOP pretreatment. The number of apoptotic cells in both early and late apoptosis stages decreased significantly and the nuclei morphology changes were improved with DOP pretreatment. Furthermore, DOP inhibited caspase 3 activation and PARP cleavage, downregulated Bax expression and upregulated Bcl2 expression in cell model. Further study revealed that pretreatment of DOP inhibited p -NF-κBp65/NF-κBp65 level, indicating DOP inhibited H₂O₂-mediated apoptosis via suppression of NF-κB activation. In addition, DOP treatment could ameliorate gastric mucosal injury and inhibit mucin loss induced by ethanol in animal model. DOP treatment also interfered with ethanol-induced apoptosis process by downregulating Bax/Bcl2 ratio in gastric mucosa.

CONCLUSIONS

The present study was the first one to demonstrate the gastroprotective effect of DOP through inhibiting oxidative stress-induced apoptosis. This study provided a solid evidence for the potential use of DO as a therapy or health supplement for gastric mucosal diseases.