Regulation of stress-associated scaffold proteins JIP1 and JIP3 on the c-Jun NH2-terminal kinase in ischemia-reperfusion

iTRAQ-derived quantitative proteomics uncovers the neuroprotective property of bexarotene in a mice model of cerebral ischemia-reperfusion injury

Bexarotene, a FDA-approved drug for cutaneous lymphoma, has been shown to exert brain protective effects. In previous study, we demonstrated that Bexarotene protects against cerebral ischemic stroke by suppressing the JNK/Caspase-3 signaling pathway. However, the molecular mechanisms by which Bexarotene-mediated neuroprotective are not fully understood. Based on the isobaric tags for relative and absolute quantification (iTRAQ)-derived proteomics and bioinformatics analysis, 4,454 differentially expressed proteins (DEPs) were identified in upstream of the JNK signaling pathway. Among them, 149 DEPs showed aberrant expression in the vehicle-versus Bexarotene-treated mice. DEPs were primarily enriched in the metabolism, calcium, and MAPK signaling pathways. The largest DEP increase was seen with heat shock protein HSP 70, whereas the largest DEP decrease was seen with JNK scaffold protein JIP3, both of which are involved in the MAPK network. Furthermore, we illustrated the Bexarotene obviously abolished oxygen and glucose deprivation/reperfusion (OGD/R)- induced LDH leakage, cells apoptosis, and the protein expression level of the JIP3,p-ASK1, p-JNK, and Cleaved Caspase3. Together, these results suggest a potential neuroprotective role of Bexarotene via inhibition of the JIP3/ASK1/JNK/Caspase 3 signaling pathway.

JIP1 Deficiency Protects Retinal Ganglion Cells From Apoptosis in a Rotenone-Induced Injury Model

Retinal ganglion cells (RGCs) undergo apoptosis after injury. c-Jun N-terminal kinase (JNK)-interacting protein 1 (JIP1) is a scaffold protein that is relevant to JNK activation and a key molecule known to regulate neuronal apoptosis. However, the specific role of JIP1 in the apoptosis of RGCs is currently undefined. Here, we used JIP1 gene knockout (KO) mice to investigate the importance of JIP1-JNK signaling in the apoptosis of RGCs in a rotenone-induced injury model. In adult JIP1 KO mice, the number and electrophysiological functions of RGCs were not different from those of wild-type (WT) mice. Ablation of JIP1 attenuated the activation of JNK and the cleavage of caspase-3 in the retina after rotenone injury and contributed to a lower number of TUNEL-positive RGCs, a greater percentage of surviving RGCs, and a significant reduction in the electrophysiological functional loss of RGCs when compared to those in WT controls. We also found that JIP1 was located in the neurites of primary RGCs, but accumulated in soma in response to rotenone treatment. Moreover, the number of TUNEL-positive RGCs, the level of activation of JNK and the rate of cleavage of caspase-3 were reduced in primary JIP1-deficient RGCs after rotenone injury than in WT controls. Together, our results demonstrate that the JIP1-mediated activation of JNK contributes to the apoptosis of RGCs in a rotenone-induced injury model in vitro and in vivo, suggesting that JIP1 may be a potential therapeutic target for RGC degeneration.

The potential role of HO-1 in regulating the MLK3-MKK7-JNK3 module scaffolded by JIP1 during cerebral ischemia/reperfusion in rats

Heme oxygenase (HO-1), which may be induced by Cobaltic protoporphyrin IX chloride (CoPPIX) or Rosiglitazone (Ros), is a neuroprotective agent that effectively reduces ischemic stroke. Previous studies have shown that the neuroprotective mechanisms of HO-1 are related to JNK signaling. The expression of HO-1 protects cells from death through the JNK signaling pathway. This study aimed to ascertain whether the neuroprotective effect of HO-1 depends on the assembly of the MLK3-MKK7-JNK3 signaling module scaffolded by JIP1 and further influences the JNK signal transmission through HO-1. Prior to the ischemia-reperfusion experiment, CoPPIX was injected through the lateral ventricle for 5 consecutive days or Ros was administered via intraperitoneal administration in the week prior to transient ischemia. Our results demonstrated that HO-1 could inhibit the assembly of the MLK3-MKK7-JNK3 signaling module scaffolded by JIP1 and could ultimately diminish the phosphorylation of JNK3. Furthermore, the inhibition of JNK3 phosphorylation downregulated the level of p-c-Jun and elevated neuronal cell death in the CA1 of the hippocampus. Taken together, these findings suggested that HO-1 could ameliorate brain injury by regulating the MLK3-MKK7-JNK3 signaling module, which was scaffolded by JIP1 and JNK signaling during cerebral ischemia/reperfusion.

WITHDRAWN: JIP3 deficiency protects mice from high fat diet-induced liver injury

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Supplementing diet with Manitoba lingonberry juice reduces kidney ischemia-reperfusion injury

BACKGROUND

Lingonberry (Vaccinium vitis-idaea L.) contains high levels of anthocyanins which are bioavailable in the kidney and may be protective against ischemia-reperfusion (IR)-induced acute kidney injury. This study investigated the effect of lingonberry juice on the IR-induced stress-activated signalling pathway and inflammatory response in the kidney.

RESULTS

Sprague-Dawley rats subjected to kidney IR had significantly impaired kidney function, with increased activation of the JNK signalling pathway and increased inflammatory response, measured using a multiplex panel containing an extensive array of inflammatory biomarkers. In rats fed 1 mL lingonberry juice daily for 3 weeks prior to IR, kidney function was protected and attenuation of inflammatory response and JNK signalling was reflected in the reduction of the measured biomarkers. In vitro results in cultured HK-2 cells confirmed that lingonberry anthocyanins reduced JNK signalling and inflammatory gene expression after IR.

CONCLUSION

This study shows, for the first time, that daily supplementation with lingonberry juice may protect against loss of kidney function induced by IR injury by modulating JNK signalling and inhibiting the subsequent inflammatory response. © 2017 Her Majesty the Queen in Right of Canada. Journal of the Science of Food and Agriculture © 2017 Society of Chemical Industry.

Manitoba Lingonberry (Vaccinium vitis-idaea) Bioactivities in Ischemia-Reperfusion Injury

Evidence for the efficacy of dietary interventions in protecting against cardiovascular disease has grown significantly, with flavonoids and anthocyanins receiving special attention. Lingonberry (Vaccinium vitis-idaea L.) is a good source of these compounds, and this study examined the protective effects of wild lingonberry found in Manitoba, Canada, against ischemia-reperfusion (IR) injury. Manitoba lingonberry contained 3793 ± 27 mg gallic acid equiv, 120,501 ± 7651 μmol trolox equiv, and 575 ± 20 mg cyanidin-3-glucoside equiv per 100 g dry weight, which correspond with high total phenolic content, antioxidant activity, and anthocyanin content, respectively. A complete methanolic extract and both anthocyanin-rich and phenolic-rich fractions inhibited apoptosis in H9c2 cells during simulated IR. Lingonberry extract and fractions significantly inhibited several markers of apoptosis induced by IR, including nuclei condensation, caspase-3 activation, and MAP kinase signaling. These results provide the first analysis of Manitoba lingonberry and highlight the mechanistic importance of dietary berry compounds for cardiovascular health.

Effects of JIP3 on epileptic seizures: Evidence from temporal lobe epilepsy patients, kainic-induced acute seizures and pentylenetetrazole-induced kindled seizures

JNK-interacting protein 3 (JIP3), also known as JNK stress-activated protein kinase-associated protein 1 (JSAP1), is a scaffold protein mainly involved in the regulation of the pro-apoptotic signaling cascade mediated by c-Jun N-terminal kinase (JNK). Overexpression of JIP3 in neurons in vitro has been reported to lead to accelerated activation of JNK and enhanced apoptosis response to cellular stress. However, the occurrence and the functional significance of stress-induced modulations of JIP3 levels in vivo remain elusive. In this study, we investigated the expression of JIP3 in temporal lobe epilepsy (TLE) and in a kainic acid (KA)-induced mouse model of epileptic seizures, and determined whether down-regulation of JIP3 can decrease susceptibility to seizures and neuron damage induced by KA. We found that JIP3 was markedly increased in TLE patients and a mouse model of epileptic seizures; mice underexpressing JIP3 through lentivirus bearing LV-Letm1-RNAi showed decreased susceptibility, delayed first seizure and decreased seizure duration response to the epileptogenic properties of KA. Subsequently, a decreased activation of JNK following seizure induction was observed in mice underexpressing JIP3, which also exhibited less neuronal apoptosis in the CA3 region of the hippocampus, as assessed three days after KA administration. We also found that mice underexpressing JIP3 exhibited a delayed pentylenetetrazole (PTZ)-induced kindling seizure process.

acal is a long non-coding RNA in JNK signaling in epithelial shape changes during drosophila dorsal closure

Dorsal closure is an epithelial remodeling process taking place during Drosophila embryogenesis. JNK signaling coordinates dorsal closure. We identify and characterize acal as a novel negative dorsal closure regulator. acal represents a new level of JNK regulation. The acal locus codes for a conserved, long, non-coding, nuclear RNA. Long non-coding RNAs are an abundant and diverse class of gene regulators. Mutations in acal are lethal. acal mRNA expression is dynamic and is processed into a collection of 50 to 120 bp fragments. We show that acal lies downstream of raw, a pioneer protein, helping explain part of raw functions, and interacts genetically with Polycomb. acal functions in trans regulating mRNA expression of two genes involved in JNK signaling and dorsal closure: Connector of kinase to AP1 (Cka) and anterior open (aop). Cka is a conserved scaffold protein that brings together JNK and Jun, and aop is a transcription factor. Misregulation of Cka and aop can account for dorsal closure phenotypes in acal mutants.

Changes in cell shape affect many critical cellular and bodily processes, like wound healing and developmental events, and when gone awry, metastatic processes in cancer. Evolutionarily conserved signaling pathways govern regulation of these cellular changes. The Jun-N-terminal kinase pathway regulates cell stretching during wound healing and normal development. An extensively studied developmental process is embryonic dorsal closure in fruit flies, a well-established model for the regulation and manner of this cell shape changes. Here we describe and characterize a processed, long non-coding RNA locus, acal, that adds a new layer of complexity to the Jun-N-terminal kinase signaling, acting as a negative regulator of the pathway. acal modulates the expression of two key genes in the pathway: the scaffold protein Cka, and the transcription factor Aop. Together, they enable the proper level of Jun-N-terminal kinase pathway activation to occur to allow cell stretching and closure.

Salidroside and tyrosol from Rhodiola protect H9c2 cells from ischemia/reperfusion-induced apoptosis

AIMS

Heart disease is the leading cause of death worldwide. Ischemia-reperfusion injury can lead to apoptotic death of heart cells and subsequently heart failure. Rhodiola is an herbal medicine with two main bioactive compounds--salidroside (SAL) and tyrosol (TYR). This study aimed to investigate whether these two compounds can prevent ischemia/reperfusion-induced apoptosis in H9c2 cells.

MAIN METHODS

Assays for total phenolics assay and Oxygen Radical Absorbance Capacity showed high antioxidant capacity of SAL and TYR. H9c2 cells were subjected to simulated ischemia/reperfusion (IR) in the presence and absence of SAL and/or TYR, and nuclei condensation, caspase-3 activity, cytochrome c release and JNK phosphorylation were determined.

KEY FINDINGS

In H9c2 cells, IR can lead to a 5-fold increase in p-JNK level. Apoptotic nuclei condensation, caspase-3 activity and cytochrome c release were markedly elevated, indicating the occurrence of apoptosis. SAL and TYR caused a dose-dependent inhibition of nuclear condensation. Furthermore, SAL and TYR, separately and in combination, significantly reduced caspase-3 activity, cytochrome c release and JNK activation. The anti-apoptotic effect of the combination was markedly higher than that of SAL or TYR alone.

SIGNIFICANCE

The inhibition of the JNK signaling pathway is the key mechanism for the cytoprotective effect of SAL and TYR in IR-induced apoptosis.

JNK/stress-activated protein kinase associated protein 1 is required for early development of telencephalic commissures in embryonic brains

We previously reported that mice lacking JSAP1 (jsap1-/-) were lethal and the brain of jsap1-/- at E18.5 exhibited multiple types of developmental defects, which included impaired axon projection of the corpus callosum and anterior commissures. In the current study, we examined whether the early telencephalic commissures were formed abnormally from the beginning of initial development or whether they arose normally, but have been progressively lost their maintenance in the absence of JSAP1. The early corpus callosum in the brain of jsap1+/+ at E15.5-E16.5 was found to cross the midline with forming a distinct U-shaped tract, whereas the early axonal tract in jsap1-/- appeared to cross the midline in a diffuse manner, but the lately arriving axons did not cross the midline. In the brain of jsap1-/- at E17.5, the axon terminals of lately arriving collaterals remained within each hemisphere, forming an early Probst's bundle-like shape. The early anterior commissure in the brain of jsap1+/+ at E14.5-E15.5 crossed the midline, whereas the anterior commissure in jsap1-/- developed, but was deviated from their normal path before approaching the midline. The axon tracts of the corpus callosum and anterior commissure in the brain of jsap1-/- at E16.5-E17.5 expressed phosphorylated forms of FAK and JNK, however, their expression levels in the axonal tracts were reduced compared to the respective controls in jsap1+/+. Considering the known scaffolding function of JSAP1 for the FAK and JNK pathways, these results suggest that JSAP1 is required for the pathfinding of the developing telencephalic commissures in the early brains.