Crosstalk with renal proximal tubule cells drives acidosis-induced inflammatory response and dedifferentiation of fibroblasts via p38-singaling

BACKGROUND

Tubulointerstitial kidney disease associated microenvironmental dysregulation, like acidification, inflammation and fibrosis, affects tubule cells and fibroblasts. Micromilieu homeostasis influences intracellular signaling and intercellular crosstalk. Cell-cell communication in turn modulates the interstitial microenvironment. We assessed the impact of acidosis on inflammatory and fibrotic responses in proximal tubule cells and fibroblasts as a function of cellular crosstalk. Furthermore, cellular signaling pathways involved were identified.

METHODS

HK-2 (human proximal tubule) and CCD-1092Sk (human fibroblasts), in mono and coculture, were exposed to acidic or control media for 3 or 48 h. Protein expression of inflammation markers (TNF, TGF-ß and COX-2), dedifferentiation markers (N-cadherin, vinculin, ß-catenin and vimentin), fibrosis markers (collagen III and fibronectin) and phospho- as well as total MAPK levels were determined by western blot. Secreted collagen III and fibronectin were measured by ELISA. The impact of MAPK activation was assessed by pharmacological intervention. In addition, necrosis, apoptosis and epithelial permeability were determined.

RESULTS

Independent of culture conditions, acidosis caused a decrease of COX-2, vimentin and fibronectin expression in proximal tubule cells. Only in monoculture, ß-Catenin expression decreased and collagen III expression increased in tubule cells during acidosis. By contrast, in coculture collagen III protein expression of tubule cells was reduced. In fibroblasts acidosis led to an increase of TNF, COX-2, vimentin, vinculin, N-cadherin protein expression and a decrease of TGF-ß expression exclusively in coculture. In monoculture, expression of COX-2 and fibronectin was reduced. Collagen III expression of fibroblasts was reduced by acidosis independent of culture conditions. In coculture, acidosis enhanced phosphorylation of ERK1/2, JNK1/2 and p38 transiently in proximal tubule cells. In fibroblasts, acidosis enhanced phosphorylation of p38 in a sustained and very strong manner. ERK1/2 and JNK1/2 were not affected in fibroblasts. Inhibition of JNK1/2 and p38 under coculture conditions reduced acidosis-induced changes in fibroblasts significantly.

CONCLUSIONS

Our data show that the crosstalk between proximal tubule cells and fibroblasts is crucial for acidosis-induced dedifferentiation of fibroblasts into an inflammatory phenotype. This dedifferentiation is at least in part mediated by p38 and JNK1/2. Thus, cell-cell communication is essential for the pathophysiological impact of tubulointerstitial acidosis.

LCZ696 attenuates sepsis-induced liver dysfunction in rats; the role of oxidative stress, apoptosis, and JNK1/2-P38 signaling pathways

AIM

Sepsis is a serious inflammatory response to infection with an annual incidence rate of >48 million cases and 11 million fatalities worldwide. Furthermore, sepsis remains the world's fifth-greatest cause of death. For the first time, the current study aims to evaluate the possible hepatoprotective benefits of LCZ696, a combination of an angiotensin receptor blocker (valsartan) and a neprilysin inhibitor prodrug (sacubitril), on cecal ligation and puncture (CLP)-induced sepsis in rats.

MAIN METHODS

CLP was employed to induce sepsis. Hepatic malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD), interleukin-6 (IL-6), IL-1β, tumor necrosis factor-alpha (TNF-α), and caspase 3 were assessed using ELISA. Serum alanine transaminase (ALT) and aspartate transaminase (AST) were also measured. Western blot assay was used to determine the expression of JNK1/2 and P38 proteins. The histology of liver tissues was also examined.

KEY FINDINGS

CLP resulted in significant elevation of AST, ALT, MDA, IL-6, IL-1β, TNF-α, and caspase 3 levels, and up-regulation of p/t JNK1/2, and p/t P38 proteins, as compared to the sham group. However, level of GSH, and SOD activity were reduced in CLP group. LCZ696 significantly improved all the previously mentioned biochemical and histological abnormalities better than using valsartan alone.

SIGNIFICANCE

LCZ696 substantially ameliorated CLP-induced liver damage, compared to valsartan, by reducing proinflammatory mediators, inhibiting the JNK1/2 and P38 signaling pathway, and attenuating apoptosis.

Psoralidin, a natural compound from Psoralea corylifolia, induces oxidative damage mediated apoptosis in colon cancer cells

Psoralidin (PSO) is a natural coumarin isolated from the seeds of Psoralea corylifolia Linn. Previous studies have reported that PSO exerts numerous pharmacological bioactivities including antitumor. The present study aimed to investigate its anticancer effect using colon cancer cells. Cultured HT-29 and HCT-116 colon cancer cells were treated with different concentrations of PSO, and the cell viability, the intracellular reactive oxygen species (ROS), the protein expression, and the apoptosis were determined by MTT assay, DCFH₂ -DA fluorescence probe, Western blotting, and Annexin V/7-AAD staining, respectively. The activities of caspase 3/7 were determined by a commercial kit. Our study found that PSO effectively induces apoptotic cell death mediated by caspase 3/7 in HT-29 and HCT-116 colon cancer cells. PSO treatment rapidly boosts the ROS generation, which is responsible for the PSO-triggered DNA damage, mitochondria membrane potential decrease and caspase 3/7 activation, and c-Jun N-terminal kinase 1/2 activation. Collectively, these results showed that PSO triggered oxidative damage mediated apoptosis in colon cancer cells.

Curcumin analog HO-3867 triggers apoptotic pathways through activating JNK1/2 signalling in human oral squamous cell carcinoma cells

Human oral squamous cell carcinoma (OSCC) is the common head and neck malignancy in the world. While surgery, radiotherapy and chemotherapy are emerging as the standard treatment for OSCC patients, the outcome is limited to the recurrence and side effects. Therefore, patients with OSCC require alternative strategies for treatment. In this study, we aimed to explore the therapeutic effect and the mode of action of the novel curcumin analog, HO-3867, against human OSCC cells. We analysed the cytotoxicity of HO-3867 using MTT assay. In vitro mechanic studies were performed to determine whether MAPK pathway is involved in HO-3867 induced cell apoptosis. As the results, we found HO-3867 suppressed OSCC cells growth effectively. The flow cytometry data indicate that HO-3867 induce the sub-G1 phase. Moreover, we found that HO-3867 induced cell apoptosis by triggering formation of activated caspase 3, caspase 8, caspase 9 and PARP. After dissecting MAPK pathway, we found HO-3867 induced cell apoptosis via the c-Jun N-terminal kinase (JNK)1/2 pathway. Our results suggest that HO-3867 is an effective anticancer agent as its induction of cell apoptosis through JNK1/2 pathway in human oral cancer cells.

Magnolol Triggers Caspase-Mediated Apoptotic Cell Death in Human Oral Cancer Cells through JNK1/2 and p38 Pathways

Magnolol is a natural compound extracted from Chinese herbal medicine and can induce apoptosis in numerous types of cancer cells. However, the molecular mechanisms of magnolol in oral cancer are still unclear. In this study, we investigated the anti-cancer effects and underlying mechanisms of magnolol in human oral cancer cell lines. Our results exhibited that magnolol inhibited the cell proliferation via inducing the sub-G1 phase and cell apoptosis of HSC-3 and SCC-9 cells. The human apoptosis array and Western blot assay showed that magnolol increased the expression of cleaved caspase-3 proteins and heme oxygenase-1 (HO-1). Moreover, we proved that magnolol induces apoptosis in oral cancer cell lines via the c-Jun N-terminal kinase (JNK)1/2 and p38 pathways. Overall, the current study supports the role for magnolol as a therapeutic approach for oral cancer through JNK1/2- and p38-mediated caspase activation.

IL-33-Induced Transcriptional Activation of LPIN1 Accelerates Breast Tumorigenesis

Phospholipids are crucial materials that are not only required for cell membrane construction but also play significant roles as signaling molecules. LPIN1 is an enzyme that displays phosphatidate phosphatase activity in the triglyceride and phospholipid synthesis pathway. Recent studies have shown that overexpression of LPIN1 is involved in breast tumorigenesis, but the underlying mechanism regulating LPIN1 expression has not been elucidated yet. In the present study, we showed that the IL-33-induced COT-JNK1/2 signaling pathway regulates LPIN1 mRNA and protein expression by recruiting c-Jun to the LPIN1 promoter in breast cancer cells. IL-33 dose-dependently and time-dependently increased LPIN1 mRNA and protein expression. Moreover, IL-33 promoted colony formation and mammary tumorigenesis via induction of LPIN1 expression, while inhibition of LPIN1 disturbed IL-33-induced cell proliferation and mammary tumorigenesis. IL-33-driven LPIN1 expression was mediated by the COT-JNK1/2 signaling pathway, and inhibition of COT or JNK1/2 reduced LPIN1 expression. COT-JNK1/2-mediated IL-33 signaling activated c-Jun and promoted its binding to the promoter region of LPIN1 to induce LPIN1 expression. These findings demonstrated the regulatory mechanism of LPIN1 transcription by the IL-33-induced COT/JNK1/2 pathway for the first time, providing a potential mechanism underlying the upregulation of LPIN1 in cancer.

IL-33-Induced Transcriptional Activation of LPIN1 Accelerates Breast Tumorigenesis

Phospholipids are crucial materials that are not only required for cell membrane construction but also play significant roles as signaling molecules. LPIN1 is an enzyme that displays phosphatidate phosphatase activity in the triglyceride and phospholipid synthesis pathway. Recent studies have shown that overexpression of LPIN1 is involved in breast tumorigenesis, but the underlying mechanism regulating LPIN1 expression has not been elucidated yet. In the present study, we showed that the IL-33-induced COT-JNK1/2 signaling pathway regulates LPIN1 mRNA and protein expression by recruiting c-Jun to the LPIN1 promoter in breast cancer cells. IL-33 dose-dependently and time-dependently increased LPIN1 mRNA and protein expression. Moreover, IL-33 promoted colony formation and mammary tumorigenesis via induction of LPIN1 expression, while inhibition of LPIN1 disturbed IL-33-induced cell proliferation and mammary tumorigenesis. IL-33-driven LPIN1 expression was mediated by the COT-JNK1/2 signaling pathway, and inhibition of COT or JNK1/2 reduced LPIN1 expression. COT-JNK1/2-mediated IL-33 signaling activated c-Jun and promoted its binding to the promoter region of LPIN1 to induce LPIN1 expression. These findings demonstrated the regulatory mechanism of LPIN1 transcription by the IL-33-induced COT/JNK1/2 pathway for the first time, providing a potential mechanism underlying the upregulation of LPIN1 in cancer.

Expression of farnesyl pyrophosphate synthase is increased in diabetic cardiomyopathy

Farnesyl pyrophosphate synthase (FPPS)-catalyzed isoprenoid intermediates are involved in diabetic cardiomyopathy. This study investigated the specific role of FPPS in the development of diabetic cardiomyopathy. We demonstrated that FPPS expression was elevated in both in vivo and in vitro models of diabetic cardiomyopathy. FPPS inhibition decreased the expression of proteins related to cardiac fibrosis and cardiomyocytic hypertrophy, including collagen I, collagen III, connective tissue growth factor, natriuretic factor, brain natriuretic peptide, and β-myosin heavy chain. Furthermore, FPPS inhibition and knockdown prevented phosphorylated c-Jun N-terminal kinase 1/2 (JNK1/2) activation in vitro. In addition, a JNK1/2 inhibitor downregulated high-glucose-induced responses to diabetic cardiomyopathy. Finally, immunofluorescence revealed that cardiomyocytic size was elevated by high glucose and was decreased by zoledronate, small-interfering farnesyl pyrophosphate synthase (siFPPS), and a JNK1/2 inhibitor. Taken together, our findings indicate that FPPS and JNK1/2 may be part of a signaling pathway that plays an important role in diabetic cardiomyopathy.

A novel strategy for glioblastoma treatment by induction of noptosis, an NQO1-dependent necrosis

Glioblastoma (GBM) is one of the most prevalent malignant primary tumors in the human brain. Temozolomide (TMZ), the chemotherapeutic drug for GBM treatment, induces apoptosis. Unfortunately, apoptosis-resistance to TMZ results in treatment failure. GBM shows enhanced expression of NAD(P)H: quinone oxidoreductase 1 (NQO1). Recently, noptosis, a type of NQO1-dependent necrosis, was proposed. Here, we identified that tanshindiol B (TSB) inhibits GBM growth by induction of noptosis. TSB triggered significant cell death, which did not fit the criteria of apoptosis but oxidative stress-induced necrosis. Molecular docking, cellular thermal shift assay, and NQO1 activity assay revealed that TSB bind to and promptly activated NQO1 enzyme activity. As the substrate of NQO1, TSB induced oxidative stress, which resulted in dramatic DNA damage, poly (ADP-ribose) polymerase 1 (PARP1) hyperactivation, and NAD⁺ depletion, leading to necrotic cell death. These effects of TSB were completely abolished by specific NQO1 inhibitor dicoumarol (DIC). Furthermore, the c-Jun N-terminal kinase 1/2 (JNK1/2) plays an essential role in mediating TSB-induced cell death. Besides, TSB significantly suppressed tumor growth in a zebrafish xenograft model mediated by NQO1. In conclusion, these results showed that TSB was an NQO1 substrate and triggered noptosis of GBM. TSB exhibited anti-tumor potentials in GBM both in vitro and in vivo. This study provides a novel strategy for fighting GBM through the induction of noptosis.

Electroacupuncture Attenuates Morphine Tolerance in Rats with Bone Cancer Pain by Inhibiting PI3K/Akt/JNK1/2 Signaling Pathway in the Spinal Dorsal Horn

Purpose:

Morphine is often used for the treatment of moderate and severe cancer pain, but long-term use can lead to morphine tolerance. Methods for effectively inhibiting morphine tolerance and the related mechanism of action are of great significance for the treatment of cancer pain. Previous studies have shown that electroacupuncture (EA) can inhibit the occurrence of morphine tolerance, but the mechanism is not yet clear. The aim of the present study was to explore the signaling pathway by which EA attenuates the development of bone cancer pain (BCP)-morphine tolerance (MT).

Materials and methods:

Changes in the paw withdrawal threshold (PWT) of rats with bone cancer pain-morphine tolerance were observed in a study of EA combined with intrathecal injection of a PI3K inhibitor (LY294002) or agonist (insulin-like growth factor-1 [IGF-1]). We also tested the protein expression of phosphorylated phosphatidylinositol 3-kinase (p-PI3K), phosphorylated protein kinase B (p-Akt), phosphorylated c-Jun NH₂-terminal kinase 1/2 (p-JNK1/2), and β-arrestin2 in the L4-6 spinal dorsal horn of rats.

Results:

The protein expression of p-PI3K, p-Akt, p-JNK1/2, and β-arrestin2 was upregulated in the L4-6 spinal dorsal horn of rats with bone cancer pain and bone cancer pain-morphine tolerance. EA delayed the occurrence of morphine tolerance in rats with bone cancer pain and downregulated the protein expression of p-PI3K, p-Akt, p-JNK1/2, and β-arrestin2 in the L4-6 spinal dorsal horn of rats with bone cancer pain-morphine tolerance. Intrathecal injection of LY294002 attenuated the development of morphine tolerance and downregulated the protein expression of p-Akt, p-JNK1/2, and β-arrestin2 in the spinal dorsal horn of rats with bone cancer pain-morphine tolerance. In addition, the inhibitory effect of EA on morphine tolerance was reversed by IGF-1.

Conclusion:

The mechanism underlying the ability of EA to attenuate morphine tolerance may be associated with inhibition of the PI3K/Akt/JNK1/2 signaling pathway.

Efficacy and Mechanism of Action of Marine Alkaloid 3,10-Dibromofascaplysin in Drug-Resistant Prostate Cancer Cells

Efficacy and mechanism of action of marine alkaloid 3,10-dibromofascaplysin (DBF) were investigated in human prostate cancer (PCa) cells harboring different levels of drug resistance. Anticancer activity was observed across all cell lines examined without signs of cross-resistance to androgen receptor targeting agents (ARTA) or taxane based chemotherapy. Kinome analysis followed by functional investigation identified JNK1/2 to be one of the molecular targets of DBF in 22Rv1 cells. In contrast, no activation of p38 and ERK1/2 MAPKs was observed. Inhibition of the drug-induced JNK1/2 activation or of the basal p38 activity resulted in increased cytotoxicity of DBF, whereas an active ERK1/2 was identified to be important for anticancer activity of the alkaloid. Synergistic effects of DBF were observed in combination with PARP-inhibitor olaparib most likely due to the induction of ROS production by the marine alkaloid. In addition, DBF intensified effects of platinum-based drugs cisplatin and carboplatin, and taxane derivatives docetaxel and cabazitaxel. Finally, DBF inhibited AR-signaling and resensitized AR-V7-positive 22Rv1 prostate cancer cells to enzalutamide, presumably due to AR-V7 down-regulation. These findings propose DBF to be a promising novel drug candidate for the treatment of human PCa regardless of resistance to standard therapy.

Zinc oxide nanoparticles from Corydalis yanhusuo attenuated the mycoplasmal pneumonia in mice through inhibiting the MAPKs signaling pathway

BACKGROUND

The Mycoplasma pneumoniae (M.pneumoniae) was accounted to 3-10% of total pneumonia incidences. In recent decades, metallic nanoparticles were extensively examined as nano-antibiotics.

OBJECTIVE

In this investigation, we intended to inspect the therapeutic potential of Zinc oxide nanoparticles (ZnONPs) from (Corydalis yanhusuo) C. yanhusuo against the mycoplasma infected pneumonia in mice.

METHODOLOGY

The ZnONPs were formulated via green route technique and characterized by UV-vis spectroscopy, transmission electron microscopy, Fourier transform infrared technique, and atomic force microscopy. The antimicrobial activity of formulated ZnONPs was tested by well diffusion method. The total protein, interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-8 (IL-8), tumor necrosis factor alpha (TNF-α) and transforming growth factor (TGF) status in the BALF of M. pneumonia infected animals were investigated via kit method. The expressions of ERK1/2, JNK1/2, and NF-κB were examined through the Western blotting. The Histopathological analysis of lung tissues of experimental animals was done.

RESULTS

The UV-vis spectroscopy and TEM examinations were proved the existence of CY-ZnONPs. The formulated CY-ZnONPs were displayed the potential antimicrobial activity. The supplementation of CY-ZnONPs were noticeably diminished the total protein and IL-6, IL-8, and TNF-α levels in the BALF of pneumonia mice. The ERK1/2, JNK1/2, and NF-κB expressions were appreciably diminished in the CY-ZnONPs supplemented mice. It also reduced the inflammatory cells penetration, and exhibited normal tissue arrangements in the lung tissues of pneumonia mice.

CONCLUSION

The findings of this investigation were proved that the synthesized CY-ZnONPs has the potential to ameliorate the M. pneumoniae infected pneumonia in investigational mice.

MKP1 in the medial prefrontal cortex modulates chronic neuropathic pain via regulation of p38 and JNK1/2

Aim: The medial prefrontal context (mPFC) plays pivotal roles in initiation, development, and maintenance of chronic pain, whereas the underlying molecular mechanisms remain elusive, which invited investigation of potential involvement of MKP1 in mPFC in mice in neuropathic pain, and its cellular and molecular mechanisms.Materials and methods: Neuropathic pain model was established in adult male Kunming mice via chronic constrictive injury (CCI) of the sciatic nerve. Paw withdrawal latency (PWL) was measured at the plantar area by radiant heat test. Stereotaxic microinjection was applied in mice as per the atlas of Mouse Brain in Stereotaxic Coordinates. mRNA levels of MKP1 in mPFC in CCI mice were assessed by RT-PCR; protein expressions of MKP1, p-p38, p-JNK and p-ERK in mPFC in CCI mice were analyzed by Western blotting, and expressions of the c-Fos in mPFC in CCI mice evaluated by immunohistochemistry. Moreover, Lenti-MKP1 particles or BCI treatment was employed to inhibit MKP1 in mPFC contralateral to the injury.Results: MKP1 was activated and persistently upregulated in mPFC neurons in CCI mice. Inhibition of MKP1 in the mPFC contralateral to the injury could reverse CCI-induced pain behavior and neuronal activity either via employment of Lenti-MKP1 particles or BCI treatment. MKP1 in the mPFC modulated neuropathic pain via dephosphorization of p38 and JNK1/2.Conclusion: The findings demonstrated that MKP1 in mPFC could play a paramount role in the modulation of neuropathic pain, which might be associated to the increased neuronal excitability in the mPFC and downregulated p-p38 and p-JNK expression.

Selenium ameliorates cadmium-induced mouse leydig TM3 cell apoptosis via inhibiting the ROS/JNK /c-jun signaling pathway

Despite the well-known acknowledgement of both the toxicity of cadmium (Cd) and the ameliorative effect of selenium (Se), the mechanism of the protective effect of selenium on cadmium-induced Mouse Leydig (TM3) cell apoptosis remains unknown. In this study, we hypothesized that the reactive oxygen species (ROS)-mediated c-jun N-terminal kinase (JNK) signaling pathway is involved in anti-apoptosis of selenium against cadmium in TM3 cells. We found that exposure to cadmium caused evident cytotoxicity, in which cell viability was inhibited, followed by inducement of apoptosis. Moreover, the level of ROS generation was elevated, leading to the phosphorylation of JNK. In addition, following cadmium exposure, the nuclear transcription factor c-jun was significantly activated, which led to increased expression of downstream gene c-jun, resulting in downstream activation of the apoptosis-related protein Caspase3 and upregulation of Cleaved-PARP, as well as inhibition of the anti-apoptosis protein Bcl-2. However, pretreatment with selenium remarkably suppressed cadmium-induced TM3 cell apoptosis. Furthermore, the level of ROS declined, and the JNK signaling pathway was blocked. Following this, the gene expression of c-jun decreased while Bcl-2 increased, which was consistent with the effects on proteins, that Caspase3 activity and Cleaved-PARP were inhibited while Bcl-2 level was restored. In order to explain the relationship between molecules of the signaling pathway, N-acetyl-L-cysteine (NAC), the ROS inhibitor, and JNK1/2 siRNA were administered, which further indicated the mediatory role of the ROS/JNK/c-jun signaling pathway in regulating anti-apoptosis of selenium against cadmium-induced TM3 cell apoptosis.

TGF-β1 activates RSC96 Schwann cells migration and invasion through MMP-2 and MMP-9 activities

Following peripheral nerve injury, remnant Schwann cells adopt a migratory phenotype and remodel the extracellular matrix allowing axonal regrowth. Although much evidence has demonstrated that TGF-β1 promotes glioma cell motility and induces the expression of extracellular matrix proteins, the effects of TGF-β1 on Schwann cell migration has not yet been studied. We therefore investigated the cellular effects and the signal transduction pathways evoked by TGF-β1 in rattus norvegicus neuronal Schwann RSC96 cell. TGF-β1 significantly increased migration and invasion of Schwann cells assessed by the wound-healing assay and by cell invasion assay. TGF-β1-enhanced migration/invasion was blocked by inhibition of MMP-2 and MMP-9. Consistently, by real-time and western blot analyses, we demonstrated that TGF-β1 increased MMP-2 and MMP-9 mRNA and protein levels. TGF-β1 also increased MMPs activities in cell growth medium, as shown by gelatin zymography. The selective TGF-β Type I receptor inhibitor SB431542 completely abrogated any effects by TGF-β1. Indeed, TGF-β1 Type I receptor activation provoked the cytosol-to-nucleus translocation of SMAD2 and SMAD3. SMAD2 knockdown by siRNA blocked MMP-2 induction and cell migration/invasion due to TGF-β1. TGF-β1 also provoked phosphorylation of MAPKs extracellular regulated kinase 1/2 and JNK1/2. Both MAPKs were upstream to p65/NF-kB inasmuch as both MAPKs' inhibitors PD98059 and SP600125 or their down-regulation by siRNA significantly blocked the TGF-β1-induced nuclear translocation of p65/NF-kB. In addition, p65/NF-κB siRNA knockdown inhibited the effects of TGF-β1 on both MMP-9 and cell migration/invasion. We conclude that TGF-β1 controls RSC96 Schwann cell migration and invasion through MMP-2 and MMP-9 activities. MMP-2 is controlled by SMAD2 whilst MMP-9 is controlled via an ERK1/2-JNK1/2-NF-κB dependent pathway.

Activation of autophagy and IL-10 production are regulated by Jun N-terminal kinase 1 and 2 and p38 mitogen activated protein kinase signaling pathways during Talaromyces marneffei infection within dendritic cells

Previous study have shown that Talaromyces marneffei (T. marneffei) induced activation of autophagy. Therefore, we explore signaling pathway that regulates activation of autophagy by intracellular signaling mechanisms during T. marneffei infection. Further, we examine c-Jun N-terminal kinase 1 and 2 (JNK1/2) and p38 signaling pathways that regulate IL-1β and IL-10 production and activation of autophagy during T. marneffei infection in human dendritic cells (DCs). We found that T. marneffei induced activation of JNK1/2 and p38 in human DCs. Furthermore, the inhibition of JNK1/2 and p38 increased activation of autophagy and decreased the replication of T. marneffei in T. marneffei-infected human DCs. Moreover, IL-1β secretion in T. marneffei-infected human DCs was dependent on JNK1/2 and autophagy pathways, whereas IL-10 secretion was dependent on JNK1/2, p38 and autophagy pathways. These data suggest that JNK1/2 and p38 pathways play critical roles in activation of autophagy, the multiplication of T. marneffei and subsequent cytokine production during T. marneffei infection.

Tobacco smoking aggravates airway inflammation by upregulating endothelin-2 and activating the c-Jun amino terminal kinase pathway in asthma

BACKGROUND

Asthma is closely associated with tobacco smoking (TS) and is more difficult to effectively treat after exposure to TS.

OBJECTIVE

To observe the effects of TS on the expression of endothelin-2 (ET-2) and airway inflammation in asthmatic rats and to explore the related mechanisms.

METHODS

We established an animal model of asthma with ovalbumin (OVA)/Al(OH)₃ and subjected different animal groups to TS and/or dexamethasone/bosentan. The differences in the inflammatory cell infiltration, the pathological changes to the bronchial wall and the bronchial smooth muscle thickness, and the expression of ET-2, c-Jun amino terminal kinase (JNK1/2), malondialdehyde (MDA), and glutathione peroxidase (GSH) in the lung tissue and of interleukin (IL)-7 in bronchoalveolar lavage fluid (BALF) were assessed.

RESULTS

Exposure to TS or OVA caused an obvious increase in the inflammatory cells in the BALF over what was observed in the control group. In asthma models, the expression of ET-1, JNK1/2, MDA, and GSH in the lung tissues, as well as that of IL-17 in the BALF, was increased. After treatment with dexamethasone/bosentan, the expression of IL-17, JNK1/2, MDA, and GSH decreased compared to the smoking group; airway inflammation and the staining intensity in the lung tissue were also reduced.

CONCLUSION

TS exposure can clearly exacerbate airway inflammation in asthmatic rats, while bosentan can alleviate airway inflammation through regulation of the ET-2/JNK1/2 signalling pathway.

Induction Apoptosis of Erinacine A in Human Colorectal Cancer Cells Involving the Expression of TNFR, Fas, and Fas Ligand via the JNK/p300/p50 Signaling Pathway With Histone Acetylation

Erinacine A, which is one of the major bioactive diterpenoid compounds extracted from cultured mycelia of H. erinaceus, displays great antitumorigenic activity. However, the molecular mechanisms underlying erinacine A inducing cancer cell apoptosis in colorectal cancer (CRC) remain unclear. This study found that treatment with erinacine A not only triggers the activation of extrinsic apoptosis pathways (TNFR, Fas, FasL, and caspases) but also suppresses the expression of antiapoptotic molecules Bcl-2 and Bcl-XL via a time-dependent manner in DLD-1 cells. Furthermore, phosphorylation of Jun N-terminus kinase (JNK1/2), NFκB p50, and p300 is involved in erinacine A–induced cancer cell apoptosis. Inhibition of these signaling pathways by kinase inhibitors blocks erinacine A–induced transcriptional activation implicates histone H3K9K14ac (Acetyl Lys9/Lys14) of the TNFR, Fas, and FasL as promoters. Moreover, histochemical and immunohistochemical analyses revealed that erinacine A treatment significantly induced the TNFR, Fas, and FasL levels in the in vivo xenograft mouse model. Together, these results demonstrated an increase in the cellular transcriptional levels of TNFR, Fas, and FasL by erinacine A induction to cell apoptosis via the activation of the JNK, p300, and NFκB p50 signaling modules, thereby providing a new mechanism for erinacine A treatment in vitro and in vivo.

An oral 2-hydroxypropyl-β-cyclodextrin-loaded spirooxindole-pyrrolizidine derivative restores p53 activity via targeting MDM2 and JNK1/2 in hepatocellular carcinoma

Validation of a small molecular compound targeting the oncogenic pathways is the primary approach for the development of the anti-cancer drugs. In the present study, we employed the computational mimic drug targets prediction software to foresee the molecular targets of a series of spirooxindole-pyrrolizidine derivatives, which were synthesized by our laboratory viatargeted combinational chemistry. We found that CPHSP, a novel spirooxindole-pyrrolizidine derivative, can target the MDM2/p53 signaling that is essential for the tumorigenesis of hepatocellular carcinoma (HCC). To validate its anti-tumoral function, we firstly established the soluble receipt of CPHSP through 2-hydroxypropyl-β-cyclodextrin (HBC) loading and showed that oral administration of HBC-loaded CPHSP significantly inhibited the tumor growth and prolonged the survival time of tumor-bearing mice in the subcutaneously human hepatoma cells-xenografted nude mouse model of HCC. Immunohistochemistry staining showed that HBC-loaded CPHSP treatment suppressed the proliferation and induced apoptosis of tumor cells in this model. Our mechanistic studies showed that CPHSP treatment inhibited MDM2 protein expression and up-regulated p53 activity and activated MKK4/MKK7/JNK1/2/C-Jun signaling pathway, which resulted in cell cycle arrest and apoptosis of HepG2 cells in vitro. Moreover, we showed that JNK1/2 activation could also up-regulate p53 expression in CPHSP-treated HepG2 cells. Finally, we documented the antitumor activities of oral administration of the HBC-loaded CPHSP in the ML-1 bearing orthotopic mouse model. In summary, this study suggests that oral administration of HBC-loaded CPHSP is a safe and effective treatment for HCC, of which the clinical potency for patients with HCC warrants further studies.

Combined Blockade of Smad3 and JNK Pathways Ameliorates Progressive Fibrosis in Folic Acid Nephropathy

Acute kidney injury leading to chronic kidney disease through tubulointerstitial fibrosis is a major challenge in nephropathy. Several signaling pathways promote interstitial fibrosis; however, effective suppression of fibrosis may require blockade of more than one pathway. This study investigated whether blockade of Smad3 and c-Jun N-terminal kinase (JNK) signaling gives added suppression of interstitial fibrosis in folic acid nephropathy. A single high dose of folic acid (FA) causes acute tubular damage in C57BL/6J mice followed by interstitial fibrosis and chronic renal impairment. Co-activations of Smad3 and JNK signaling occur in both tubular epithelial cells and myofibroblasts in areas of tubulointerstitial damage and fibrosis in both murine FA-induced nephropathy and human IgA nephropathy. Groups of mice were treated with a Smad3 inhibitor (SIS3), a JNK inhibitor (SP600125), or a combination from day 6 after FA administration until being killed on day 28. Each drug efficiently inhibited its specific target (Smad3 phosphorylation or c–Jun phosphorylation) without affecting the other pathway. Given alone, each drug partially reduced renal fibrosis, whereas the combination therapy gave an additive and profound protection from renal fibrosis and improved renal function. Inhibition of Smad3 and/or JNK signaling activities prevented down-regulation of PGC-1α in tubular epithelial cells and up-regulation of PGC-1α in myofibroblasts during FA-induced renal fibrosis and inflammation. The expression of PGC-1α was upregulated in Smad3^−/− NRK52E cells while downregulated in Smad3^−/−NRK49F cells, suggesting that Smad3 signaling may regulate expression of PGC-1α in renal tubular epithelial cells and fibroblasts in distinct fashion. In vivo and cell culture studies also indicate that Smad3 and JNK signaling cooperate to cause mitochondrial dysfunction and cell damage in tubular epithelial cells via direct actions on the transcription of PGC-1α. These pathways also act cooperatively to promote renal fibroblast proliferation in tempo-spatial fashion. In conclusion, we have identified a potential combination therapy for progressive renal fibrosis which operates, in part, through modifying mitochondrial function.

The role of angiopoietin-like protein 4 in phenylephrine-induced cardiomyocyte hypertrophy

Angiopoietin-like protein 4 (ANGPTL4) is a multifunctional secreted protein that can be induced by fasting, hypoxia and glucocorticoids. ANGPTL4 has been associated with a variety of diseases; however, the role of ANGPTL4 in cardiac hypertrophy remains poorly understood. In our study, we aimed to explore the effect of ANGPTL4 on phenylephrine-induced cardiomyocyte hypertrophy. Our results showed that knockdown of ANGPTL4 expression significantly exacerbated cardiomyocyte hypertrophy, as demonstrated by increased hypertrophic marker expression, including ANP and cell surface area. Moreover, significantly reduced fatty acid oxidation, as featured by decreased CPT-1 levels, was observed in hypertrophic cardiomyocytes following ANGPTL4 down-regulation. Furthermore, knockdown of ANGPLT4 led to down-regulated expression of peroxisome proliferator-activated receptor α (PPARα), which is the key regulator of cardiac fatty acid oxidation. In addition, ANGPTL4 silencing promoted the activation of JNK1/2, and JNK1/2 signaling blockade could restore the level of PPARα and significantly ameliorate the ANGPTL4 knockdown-induced cardiomyocyte hypertrophy. Therefore, our study demonstrated that ANGPTL4 regulates PPARα through JNK1/2 signaling and is required for the inhibition of cardiomyocyte hypertrophy.

1-O-Hexyl-2,3,5-Trimethylhydroquinone Ameliorates l-DOPA-Induced Cytotoxicity in PC12 Cells

1-O-Hexyl-2,3,5-trimethylhydroquinone (HTHQ) has previously been found to have effective anti-oxidant and anti-lipid-peroxidative activity. We aimed to elucidate whether HTHQ can prevent dopaminergic neuronal cell death by investigating the effect on l-DOPA-induced cytotoxicity in PC12 cells. HTHQ protected from both l-DOPA-induced cell death and superoxide dismutase activity reduction. When assessing the effect of HTHQ on oxidative stress-related signaling pathways, HTHQ inhibited l-DOPA-induced phosphorylation of sustained extracellular signal-regulated kinases (ERK1/2), p38 mitogen-activated protein kinase (MAPK), and c-Jun N-terminal kinase (JNK1/2). HTHQ also normalized l-DOPA-reduced Bcl-2-associated death protein (Bad) phosphorylation and Bcl-2-associated X protein (Bax) expression, promoting cell survival. Taken together, HTHQ exhibits protective effects against l-DOPA-induced cell death through modulation of the ERK1/2-p38MAPK-JNK1/2-Bad-Bax signaling pathway in PC12 cells. These results suggest that HTHQ may show ameliorative effects against oxidative stress-induced dopaminergic neuronal cell death, although further studies in animal models of Parkinson’s disease are required to confirm this.

LIMD1 phosphorylation in mitosis is required for mitotic progression and its tumor-suppressing activity

LIM domains containing 1 (LIMD1) is a member of the Zyxin family proteins and functions as a tumor suppressor in lung cancer. LIMD1 has been shown to regulate Hippo-YAP signaling activity. Here, we report a novel regulatory mechanism for LIMD1. We found that cyclin-dependent kinase 1 (CDK1) and c-Jun NH2-terminal kinases 1/2 (JNK1/2) phosphorylate LIMD1 in vitro and in cells during anti-tubulin drug-induced mitotic arrest. Phosphorylation also occurs during normal mitosis. S272, S277, S421, and S424 were identified as the main phosphorylation sites in LIMD1. Deletion of LIMD1 resulted in a shortened mitotic cell cycle and phosphorylation of LIMD1 is required for proper mitotic progression. We further showed that the phosphorylation-deficient mutant LIMD1-4A is less active in suppressing cell proliferation, anchorage-independent growth, cell migration, and invasion in lung cancer cells. Together, our findings suggest that LIMD1 is a key regulator of mitotic progression, and that dysregulation of LIMD1 contributes to tumorigenesis.

Diethyl Blechnic, a Novel Natural Product Isolated from Salvia miltiorrhiza Bunge, Inhibits Doxorubicin-Induced Apoptosis by Inhibiting ROS and Activating JNK1/2

Doxorubicin (DOX) is a widely used antineoplastic agent in clinics. However, its clinical application is largely limited by its cardiotoxicity. Diethyl blechnic (DB) is a novel compound isolated from Salvia miltiorrhiza Bunge. Here, we study the effect of DB on DOX-induced cardiotoxicity and its underlying mechanisms. Cellular viability was tested by 3-[-4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and protein level was evaluated by Western blotting. 5,5’,6,6’-tetrachloro-1,1’,3,3’-tetraethylbenzimidazolylcarbocyanine iodide (JC-1) staining was performed to determine the mitochondrial membrane potential (MMP). Hoechst 33342 staining and TUNEL staining was performed to test the apoptosis. Reactive oxygen species (ROS) generation was investigated by using flow cytometry. DB significantly inhibited DOX-induced apoptosis in H9c2 cells and primary cultured cardiomyocytes. Moreover, DB decreased cell apoptotic morphological changes and reversed the mitochondrial membrane potential induced by DOX. Meanwhile, pre-treatment with DB increased the expression levels of B-cell lymphoma 2 (Bcl-2), B-cell lymphoma-extra-large (Bcl-xl), and survivin and reduced the expression levels of Bcl-2-associated X protein (Bax), p-p53, cytochrome c (cyt c), and cleaved-caspase 3, 7, 8, 9 in the protein levels in DOX-treated H9c2 cells. Furthermore, DB suppressed ROS generation. The DB-mediated protective effects were accompanied by increased c-Jun N-terminal kinase1/2 (JNK1/2) expression. In addition, SP600125, the inhibitor of JNK1/2, abolished the protective effect of DB. We concluded that DB protected cardiomyocytes against DOX-induced cytotoxicity by inhibiting ROS and activating the JNK1/2 pathway. Therefore, DB is a promising candidate as a cardioprotective agent against DOX-induced cardiotoxicity.

MAPK signaling has stage-dependent osteogenic effects on human adipose-derived stem cells in vitro

OVERVIEW

The use of pro-osteogenic growth factors, such as BMP2, in human adipose-derived stem cell (ASC) osteogenesis is well described. Because these growth factors work via signal transduction pathways, such as the mitogen-activated protein kinase (MAPK) cascade, a study of the relationship between MAPK signaling and ASC osteogenesis was conducted.

MATERIALS AND METHODS

ERK, JNK, and p38MAPK activation were measured in ASCs osteo-induced using either dexamethasone or vitamin D3 and correlated with mineralization. Activation and mineralization were also measured without dexamethasone or using the glucocorticoid, cortisone. The expression of the MAPK phosphatase, MKP1, and its relationship to mineralization was also assessed. The effect of decreasing MAPK activation on mineralization through the use of exogenous inhibitors was examined along with siRNA-knockdown and adenoviral overexpression of ERK1/2. Finally, the effect of ERK1/2 overexpression on ASCs induced on PLGA scaffolds was assessed.

RESULTS

ASC mineralization in dexamethasone or vitamin D3-induced ASCs correlated with both increased ERK1/2 and JNK1/2 activation. ASCs induced without dexamethasone also mineralized, with JNK1/2 signaling possibly mediating this event. No link between cortisone induction and MAPK signaling could be ascertained. ASCs treated with ERK, JNK, or p38MAPK inhibitors showed decreased osteogenic gene expression and diminished mineralization. Mineralization levels were also affected by viruses designed to inhibit or augment ERK1/2 expression and activity. Finally, ASC mineralization appeared to be a balance between the MAPK kinase activity and MKP1.

CONCLUSIONS

It is likely that MAPK signaling plays a significant role in ASC osteogenesis, affecting differentiation in kinase- and stage-specific manners.

Astragalus polysaccharides increase the sensitivity of SKOV3 cells to cisplatin

BACKGROUND

Multidrug resistance in malignant tumours hinders the treatment of tumours. Studies showed that astragalus polysaccharides (APS), one major active ingredient of astragalus, enhanced the sensitivity of non-small cell lung cancer and liver cancer cells to chemotherapeutic drug. However, the effect of APS on ovarian cancer is still unclear. In this study, we will examine the sensitizing effect of APS on SKOV3 cells to cisplatin and explore the possible mechanism.

METHODS

MTT assay was employed to examine the viability of SKOV3 after treatment with APS and cisplatin. The cell apoptosis rate was determined by flow cytometry. The expression of Bax, Bcl-2, Caspase-3, and c-Jun N-terminal kinases 1/2 (JNK1/2) was measured using Western blotting and RT-PCR.

RESULTS

APS synergistically promoted the inhibitory effect of cisplatin on SKOV3 cell viability. Flow cytometry showed that APS promoted cisplatin-induced apoptosis of SKOV3 cell lines. Further studies showed that APS down-regulated the expression of Bcl2, increased the expression of Bax and caspase 3 and activated JNK1/2 signalling pathway. The JNK inhibitors significantly rescued the proliferation inhibition induced by the drugs.

CONCLUSIONS

Astragalus polysaccharides increased the sensitivity of SKOV3 cells to cisplatin potentially by activating the JNK pathway. The apoptosis-related genes may contribute to the process. Thus, APS may be useful for the treatment of ovarian cancer as an enhancer of chemosensitivity.

DUSPs as critical regulators of cardiac hypertrophy

This commentary highlights the research presented by Li et al. [15]. In this issue of Clinical Science, which demonstrates that dual specific phosphatase 12 (DUSP12), through JNK1/2 inhibition, alleviates cardiac hypertrophy in response to pressure overload, making it a potential therapeutic target.

A Novel Zak Knockout Mouse with a Defective Ribotoxic Stress Response

Ricin activates the proinflammatory ribotoxic stress response through the mitogen activated protein 3 kinase (MAP3K) ZAK, resulting in activation of mitogen activated protein kinases (MAPKs) p38 and JNK1/2. We had a novel zak−/− mouse generated to study the role of ZAK signaling in vivo during ricin intoxication. To characterize this murine strain, we intoxicated zak−/− and zak+/+ bone marrow–derived murine macrophages with ricin, measured p38 and JNK1/2 activation by Western blot, and measured zak, c-jun, and cxcl-1 expression by qRT-PCR. To determine whether zak−/− mice differed from wild-type mice in their in vivo response to ricin, we performed oral ricin intoxication experiments with zak+/+ and zak−/− mice, using blinded histopathology scoring of duodenal tissue sections to determine differences in tissue damage. Unlike macrophages derived from zak+/+ mice, those derived from the novel zak−/− strain fail to activate p38 and JNK1/2 and have decreased c-jun and cxcl-1 expression following ricin intoxication. Furthermore, compared with zak+/+ mice, zak−/− mice have decreased duodenal damage following in vivo ricin challenge. zak−/− mice demonstrate a distinct ribotoxic stress–associated phenotype in response to ricin and therefore provide a new animal model for in vivo studies of ZAK signaling.

JNK1/2 expression and modulation of STAT3 signaling in oral cancer

Mitogen-activated protein kinases (MAPKs) are a family of protein kinases that link extracellular stimuli with intracellular responses and participate in numerous cellular processes such as growth, proliferation, differentiation, inflammation and apoptosis. Persistent activation of signal transducer and activator of transcription 3 (STAT3), which is accompanied by increases in STAT3 tyrosine phosphorylation, is associated with cell proliferation, differentiation and apoptosis in oral squamous cell carcinoma (OSCC). The role and significance of the activation of MAPKs, particularly of c-Jun N-terminal kinase (JNK), on STAT3 signaling in OSCC have not been thoroughly investigated. The present study examines the effects of JNK1/2 modulation on STAT3 signaling and cellular activities in OSCC cells. The expression levels of STAT3 [total, tyrosine phosphorylated (p-Tyr) and serine phosphorylated (p-Ser)], JNK, c-Jun and cyclin D1 were assessed in the OSCC cell lines SCC25 and SCC9. Inhibition of JNK1/2 was achieved by pharmacological agents (SP600125) and by small interfering RNA (siRNA) silencing, while JNK1/2 was induced by active MAPK kinase 7. Cell proliferation and viability rates were also evaluated. Inhibition of JNK1/2 with either SP600125 treatment or specific siRNA silencing resulted in decreased levels of p-Ser STAT3 and increased levels of p-Tyr STAT3 and cyclin D1 in both cell lines. Furthermore, JNK1/2 inhibition resulted in a dose-dependent increase in cell growth and viability in both cell lines. Opposite results were observed with JNK1/2 induction in both cell lines. The present results are supportive of a potential tumor suppressive role of JNK1/2 signaling in OSCC, which may be mediated through negative crosstalk with the oncogenic STAT3 signaling pathway. The possible therapeutic implications of JNK1/2 inhibition for patients with OSCC require to be investigated.

JNK and p38 mitogen-activated protein kinase pathways contribute to porcine epidemic diarrhea virus infection

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PEDV infection activated p38 MAPK and JNK1/2 in vitro.

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UV-inactivated virus failed to induce p38 MAPK and JNK1/2 activation.

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Pharmacological inhibition of p38 MAPK or JNK activation impaired PEDV replication.

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SAPK cascades do not affect the apoptosis pathway during PEDV infection.

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PEDV exploits the p38 MAPK and JNK signaling pathways for optimal replication.

The mitogen-activated protein kinase (MAPK) pathways, which are central building blocks in the intracellular signaling network, are often manipulated by viruses of diverse families to favor their replication. Among the MAPK family, the extracellular signal-regulated kinase (ERK) pathway is known to be modulated during the infection with porcine epidemic diarrhea virus (PEDV); however, involvement of stress-activated protein kinases (SAPKs) comprising p38 MAPK and c-Jun NH₂-terminal kinase (JNK) remains to be determined. Therefore, in the present study, we investigated whether activation of p38 MAPK and JNK cascades is required for PEDV replication. Our results showed that PEDV activates p38 MAPK and JNK1/2 up to 24 h post-infection, whereas, thereafter their phosphorylation levels recede to baseline levels or even fall below them. Notably, UV-irradiated inactivated PEDV, which can enter cells but cannot replicate inside them, failed to induce phosphorylation of p38 MAPK and JNK1/2 suggesting that viral biosynthesis is essential for activation of these kinases. Treatment of cells with selective p38 or JNK inhibitors markedly impaired PEDV replication in a dose-dependent manner and these antiviral effects were found to be maximal during the early times of the infection. Furthermore, direct pharmacological inhibition of p38 MAPK or JNK1/2 activation resulted in a significant reduction of viral RNA synthesis, viral protein expression, and progeny release. However, independent treatments with either SAPK inhibitor did not inhibit PEDV-induced apoptotic cell death mediated by activation of mitochondrial apoptosis-inducing factor (AIF) suggesting that SAPKs are irrelevant to the apoptosis pathway during PEDV infection. In summary, our data demonstrated critical roles of the p38 and JNK1/2 signaling pathways in facilitating successful viral infection during the post-entry steps of the PEDV life cycle.

Effect of Jun N-terminal kinase 1 and 2 on the replication of Penicillium marneffei in human macrophages

Penicillium marneffei (P. marneffei) is a human pathogen which persists in macrophages and threatens the immunocompromised patients. To clarify the mechanisms involved, we evaluated the effect of c-Jun N-terminal kinase 1 and 2 (JNK1/2) on cytokine expression, phagosomal maturation and multiplication of P. marneffei in P. marneffei-stimulated human macrophages. P. marneffei induced the rapid phosphorylation of JNK1/2. Using the specific inhibitor of JNK1/2 (SP600125), we found that the inhibition of JNK1/2 suppressed P. marneffei-induced tumor necrosis factor-α and IL-10 production. In addition, the presence of SP600125 increased phagosomal acidification and maturation and decreased intracellular replication. These data suggest that JNK1/2 may play an important role in promoting the replication of P. marneffei. Our findings further indicate that the pathogen through the JNK1/2 pathway may attenuate the immune response and macrophage antifungal function.

Calpain-1 induces endoplasmic reticulum stress in promoting cardiomyocyte apoptosis following hypoxia/reoxygenation

Both calpain activation and endoplasmic reticulum (ER) stress are implicated in ischemic heart injury. However, the role of calpain in ER stress remains largely elusive. This study investigated whether calpain activation causes ER stress, thereby mediating cardiomyocyte apoptosis in an in vitro model of hypoxia/re-oxygenation (H/R). In neonatal mouse cardiomyocytes and rat cardiomyocyte-like H9c2 cells, up-regulation of calpain-1 sufficiently induced ER stress, c-Jun N-terminal protein kinase1/2 (JNK1/2) activation and apoptosis. Inhibition of ER stress or JNK1/2 prevented apoptosis induced by calpain-1. In an in vitro model of H/R-induced injury in cardiomyocytes, H/R was induced by a 24-hour hypoxia followed by a 24-hour re-oxygenation. H/R activated calpain-1, induced ER stress and JNK1/2 activation, and triggered apoptosis. Inhibition of calpain and ER stress blocked JNK1/2 activation and prevented H/R-induced apoptosis. Furthermore, blockade of JNK1/2 signaling inhibited apoptosis following H/R. The role of calpain in ER stress was also demonstrated in an in vivo model of ischemia/reperfusion using transgenic mice over-expressing calpastatin. In summary, calpain-1 induces ER stress and JNK1/2 activation, thereby mediating apoptosis in cardiomyocytes. Accordingly, inhibition of calpain prevents ER stress, JNK1/2 activation and apoptosis in H/R-induced cardiomyocytes. Thus, ER stress/JNK1/2 activation may represent an important mechanism linking calpain-1 to ischemic injury.

Sub-chronic agmatine treatment modulates hippocampal neuroplasticity and cell survival signaling pathways in mice

Agmatine is an endogenous neuromodulator which, based on animal and human studies, is a putative novel antidepressant drug. In this study, we investigated the ability of sub-chronic (21 days) p.o. agmatine administration to produce an antidepressant-like effect in the tail suspension test and examined the hippocampal cell signaling pathways implicated in such an effect. Agmatine at doses of 0.01 and 0.1 mg/kg (p.o.) produced a significant antidepressant-like effect in the tail suspension test and no effect in the open-field test. Additionally, agmatine (0.001-0.1 mg/kg, p.o.) increased the phosphorylation of protein kinase A substrates (237-258% of control), protein kinase B/Akt (Ser(473)) (116-127% of control), glycogen synthase kinase-3β (Ser(9)) (110-113% of control), extracellular signal-regulated kinases 1/2 (119-137% and 121-138% of control, respectively) and cAMP response elements (Ser(133)) (127-152% of control), and brain-derived-neurotrophic factor (137-175% of control) immunocontent in a dose-dependent manner in the hippocampus. Agmatine (0.001-0.1 mg/kg, p.o.) also reduced the c-jun N-terminal kinase 1/2 phosphorylation (77-71% and 65-51% of control, respectively). Neither protein kinase C nor p38(MAPK) phosphorylation was altered under any experimental conditions. Taken together, the present study extends the available data on the mechanisms that underlie the antidepressant action of agmatine by showing an antidepressant-like effect following sub-chronic administration. In addition, our results are the first to demonstrate the ability of agmatine to elicit the activation of cellular signaling pathways associated with neuroplasticity/cell survival and the inhibition of signaling pathways associated with cell death in the hippocampus.

Electroacupuncture attenuates mechanical allodynia by suppressing the spinal JNK1/2 pathway in a rat model of inflammatory pain

BACKGROUND

Electroacupuncture (EA) has a substantial analgesic effect on inflammatory pain induced by complete Freund's adjuvant (CFA). The activation of the c-Jun N-terminal kinase 1/2 (JNK1/2) signal transduction pathway in the spinal cord is associated with inflammatory pain. However, the relationship between EA's analgesic effect and the JNK1/2 signal transduction pathway in the inflammatory pain remain unclear. In the present study, we used the established rat model of CFA-induced inflammatory pain to investigate the role of the spinal JNK1/2 pathway in EA-mediated analgesia.

RESULTS

We observed a decrease in paw withdrawal thresholds and an increase in paw edema at 1 and 3 days after injecting CFA into the right hindpaw. CFA, 3 days after injection, upregulated expression of phospho-c-Jun N-terminal kinase1/2 (p-JNK1/2) protein and its downstream targets, the transcriptional regulators p-c-Jun and activator protein-1 (AP-1), as well as cyclooxygenase-2 (COX-2) and the transient receptor potential vanilloid 1 (TRPV1). EA significantly alleviated CFA-induced inflammatory pain. In addition, EA reduced p-JNK1/2 protein levels and COX-2 mRNA expressions, a degree of down-regulated p-c-Jun protein level and AP-1 DNA binding activity in the spinal dorsal horn of CFA-administered animals, but it had no effect on TRPV1 mRNA expression. Furthermore, EA and the JNK inhibitor SP600125 synergistically inhibited CFA-induced hyperalgesia and suppressed the COX-2 mRNA expression in the spinal dorsal horn.

CONCLUSIONS

Our findings indicate that EA alleviates inflammatory pain behavior, at least in part, by reducing COX-2 expression in the spinal cord via the JNK1/2 signaling pathway. Inactivation of the spinal JNK1/2 signal transduction pathway maybe the potential mechanism of EA's antinociception in the inflammatory pain model.

Exploring the effects of tert-butylhydroperoxide induced liver injury using proteomic approach

Tert-butyl hydroperoxide (t-BHP), an organic lipid hydroperoxide analog, has been demonstrated to exert pro-oxidant effects to evaluate mechanisms involving oxidative stress in hepatocyte cells and rat liver. Herein, we present an investigation of the event of molecular mechanism of t-BHP related acute liver injury. A proteomic approach was used to identify proteins which are differentially expressed in liver cells following t-BHP treatment and the mechanism of its action in apoptotic and endoplasmic reticulum stress pathways. Our results demonstrate that the t-BHP treatment of liver cells increased cell cytoxicity and apoptosis. t-BHP dose-dependent induction of cell apoptosis and stained liver sections relieved the acute rat liver injury were accompanied by sustained phosphorylation of JNK1/2 and p65. In addition, there were 13 differentially displayed proteins between the t-BHP-induced and untreated were assayed and validated in vivo. Furthermore, we demonstrated that t-BHP induced human Chang liver cell viability and apoptosis properties by up-regulating the levels of ETFA (electron transfer flavoprotein subunit alpha). This study demonstrated that there was an increase in the cellular levels of ETFA in the t-BHP induction in viability and apoptosis via the activation of JNK1/2 and NFκB signaling modules. NAC administration and shRNA ETFA conferred resistance to t-BHP-increased ETFA and CHOP expression via IRE1-alpha/TRAF2 complex formation, activation of JNK1/2 and p50. We concluded that the mechanism of t-BHP-induced an apoptosis cascade and endoplasmic reticulum stress in hepatocyte cells by up-regulation of ETFA, providing a new mechanism for liver injury.

The role of DAPK-BimEL pathway in neuronal death induced by oxygen-glucose deprivation

Death-associated protein kinase (DAPK) has been found promoting cell death under stress conditions, including cell death during brain ischemia. However, little is known about the mechanisms how DAPK is involved in the neuronal death-promoting process during ischemia. The present study was to examine the DAPK signal transduction pathways using an ischemia mimicking model, oxygen glucose deprivation (OGD). OGD was induced by incubating SH-SY5Y neuroblastoma cells in glucose-free culture medium flushed with a mixture of N₂ and CO₂. DAPK expression was inhibited by transfection of SH-SY5Y cells with DAPK short hairpin RNA (shRNA). Cell death induced by OGD exposure was assessed by Annexin V-FITC and propidium iodide (PI) assay. Protein expressions were examined by Western blot and protein interactions were detected with immunoprecipitation followed by Western blot. OGD treatment resulted in neuronal death and led to DAPK activation as demonstrated by increase of DAPK (active form) and decrease of phospho-DAPK (inactive form). The activation of DAPK in turn led to BimEL up-regulation and endoplasmic reticulum (ER) stress activation. Further analyses showed that DAPK mediated BimEL expression through extracellular signal-regulated protein kinase1/2 (ERK1/2) inactivation and c-Jun-N-terminal kinase1/2 (JNK1/2) activation. These findings revealed novel signal transduction pathways leading to neuronal death in response to OGD.

Involvement of MAPK signaling pathway in the osteogenic gene expressions of Cervi Pantotrichum Cornu in MG-63 human osteoblast-like cells

AIMS

The purposes of this study were to determine whether Cervi Pantotrichum Cornu (CPC) has osteogenic activities in human osteoblastic MG-63 cells and to investigate the underlying molecular mechanism.

MAIN METHODS

The effects of CPC on alkaline phosphatase activity, collagen synthesis, and calcium deposits were measured. The COL1A1, ALPL, BGLAP, and SPP1 expressions were measured by real-time PCR. Phosphorylated MAP kinases (ERK1/2, JNK1/2, p38, ELK1, and cJUN) were studied by western blot analysis. The involvement of MAPK pathway in osteogenic gene expressions was determined by using each selective MAPK inhibitor (PD98059, SP600125, and SB203580).

KEY FINDINGS

CPC increased alkaline phosphatase activity, collagen synthesis, and calcium deposits. CPC activated ERK1/2, JNK1/2, p38, and ELK1 phosphorylation except cJUN. CPC increased the COL1A1, ALPL, BGLAP, and SPP1 gene expressions. The elevated COL1A1 and BGLAP expressions were inhibited by PD98059, SP600125 or SB203580. The elevated ALPL expression was blocked by SB203580. The elevated SPP1 expression was inhibited by SP600125 or SB203580. CPC increased COL1A1 and BGLAP expressions via ERK1/2, JNK1/2, and p38 MAPKs pathways and SPP1 expression via JNK1/2 and p38 pathways. p38 pathway is needed for ALPL expression.

SIGNIFICANCE

These results imply that MAPK signaling pathway is an indispensable factor for bone matrix genes expression of CPC in MG-63 human osteoblast-like cells.

JNK1 and JNK2 regulate α-SMA in hepatic stellate cells during CCl4 -induced fibrosis in the rat liver

Following liver injuries, hepatic stellate cells (HSCs) express α-SMA. Mitogen activated protein kinase (MAPK) signaling pathways mediate α-SMA expression in distinct cell types. However, the regulation of α-SMA expression by MAPKs in HSCs has been rarely studied. We aimed to study the role of MAPKs in the activation of HSCs during liver fibrosis. Liver fibrosis of rats was induced by carbon tetrachloride. HSC-T6 cells, murine embryonic fibroblasts, JNK1(-/-) and JNK2(-/-) cells were used for in vitro studies. Immunohistochemistry and immunoblot analysis were used. We have found that the expression of JNK and α-SMA co-localized in HSCs during liver fibrosis, but ERK and p38 expressed in macrophages. The expression of α-SMA was up-regulated by JNK1 and JNK2 in non-stress condition. Under TGF-β stimulation, however, the level α-SMA expression was increased by only JNK1, but not significantly changed by JNK2. We suggest that JNKs are responsible for α-SMA regulation, and especially JNK1 has a major role in up-regulation of α-SMA expression in HSCs under stress condition induced by TGF-β during liver fibrosis.

Regulatory role of ASK1 in porcine circovirus type 2-induced apoptosis

Porcine circovirus type 2 (PCV2), a major causative agent of postweaning multisystemic wasting syndrome which is an emerging and important swine disease, can induce apoptotic responses in vitro and in vivo. However, the molecular mechanism of PCV2-induced apoptosis is not well understood. Apoptosis signal-regulating kinase 1 (ASK1), serves as an upstream enzyme that activates the JNK and p38 MAPK pathways, has been shown to play a target role in the regulation of apoptosis. Here, we showed that PCV2 infection induced ASK1 phosphorylation which preceded activation of JNK1/2 and p38 signaling in the cultured cells, and that the phosphatidylinostol 3-kinase (PI3K)/Akt signaling triggered by PCV2 infection limited the extent of JNK1/2 and p38 activation and thereby apoptotic cell death. Furthermore, inhibition of JNK and p38 activation is associated with PI3K-dependent negative-regulation of ASK1 in the PCV2-infected cells. These results indicate an important regulatory role of ASK1 in PCV2-induced apoptotic responses.

Anthrax lethal toxin induces acute diastolic dysfunction in rats through disruption of the phospholamban signaling network

BACKGROUND

Anthrax lethal toxin (LT), secreted by Bacillus anthracis, causes severe cardiac dysfunction by unknown mechanisms. LT specifically cleaves the docking domains of MAPKK (MEKs); thus, we hypothesized that LT directly impairs cardiac function through dysregulation of MAPK signaling mechanisms.

METHODS AND RESULTS

In a time-course study of LT toxicity, echocardiography revealed acute diastolic heart failure accompanied by pulmonary regurgitation and left atrial dilation in adult Sprague-Dawley rats at time points corresponding to dysregulated JNK, phospholamban (PLB) and protein phosphatase 2A (PP2A) myocardial signaling. Using isolated rat ventricular myocytes, we identified the MEK7-JNK1-PP2A-PLB signaling axis to be important for regulation of intracellular calcium (Ca(2+)(i)) handling, PP2A activation and targeting of PP2A-B56α to Ca(2+)(i) handling proteins, such as PLB. Through a combination of gain-of-function and loss-of-function studies, we demonstrated that over-expression of MEK7 protects against LT-induced PP2A activation and Ca(2+)(i) dysregulation through activation of JNK1. Moreover, targeted phosphorylation of PLB-Thr(17) by Akt improved sarcoplasmic reticulum Ca(2+)(i) release and reuptake during LT toxicity. Co-immunoprecipitation experiments further revealed the pivotal role of MEK7-JNK-Akt complex formation for phosphorylation of PLB-Thr(17) during acute LT toxicity.

CONCLUSIONS

Our findings support a cardiogenic mechanism of LT-induced diastolic dysfunction, by which LT disrupts JNK1 signaling and results in Ca(2+)(i) dysregulation through diminished phosphorylation of PLB by Akt and increased dephosphorylation of PLB by PP2A. Integration of the MEK7-JNK1 signaling module with Akt represents an important stress-activated signalosome that may confer protection to sustain cardiac contractility and maintain normal levels of Ca(2+)(i) through PLB-T(17) phosphorylation.