Mitogen-activated Protein Kinase Members Research Articles

Deregulated JNK signaling enhances apoptosis during hyperthermia

Purpose c-Jun N-terminal kinases (JNKs) comprise a subfamily of mitogen-activated protein kinases (MAPKs). The JNK group is known to be activated by a variety of stimuli. However, the molecular mechanism underlying heat-induced JNK activation is largely unknown. The aim of this study was to clarify how JNK activity is stimulated by heat. Methods and materials The expression levels of various MAPK members in HeLa cells, with or without hyperthermia treatment, were evaluated via western blotting. The kinase activity of MAPK members was assessed through in vitro kinase assays. Cell death was assessed in the absence or presence of siRNAs targeting MAPK-related members. Results Hyperthermia decreased the levels of MAP3Ks, such as ASK1 and MLK3 which are JNK kinase kinase members, but not those of the downstream MAP2K/SEK1 and MAPK/JNK. Despite the reduced or transient phosphorylation of ASK1, MLK3, or SEK1, downstream JNK was phosphorylated in a temperature-dependent manner. In vitro kinase assays demonstrated that heat did not directly stimulate SEK1 or JNK. However, the expression levels of DUSP16, a JNK phosphatase, were decreased upon hyperthermia treatment. DUSP16 knockdown enhanced the heat-induced activation of ASK1–SEK1–JNK pathway and apoptosis. Conclusion JNK was activated in a temperature-dependent manner despite reduced or transient phosphorylation of the upstream MAP3K and MAP2K. Hyperthermia-induced degradation of DUSP16 may induce activation of the ASK1–SEK1–JNK pathway and subsequent apoptosis.

Excavation of Genes Response to Heat Resistance by Transcriptome Analysis in Bottle Gourd (Lagenaria siceraria (Mol.) Standl.)

Heat stress, as a negative factor, severely threatens the quality and production of bottle gourd, which prefers to grow in a warm environment. To understand which genes are involved in the resistance to heat stress in bottle gourd (Lagenaria siceraria (Mol.) Standl.), we analyzed the characteristics of two genetic bottle gourd varieties, “Mei feng”-MF (heat resistant) and “Lv long”-LL (heat sensitive). Under heat stress, MF plants exhibited a higher survival rate, lower relative electrolytic leakage, and decreased stomatal aperture compared with LL. In addition, RNA-Seq was carried out on the two varieties under normal conditions and heat stress. The results revealed a total of 1485 up-regulated and 946 down-regulated genes under normal conditions, while 602 genes were up-regulated and 1212 genes were down-regulated under heat stress. Among these genes, several differentially expressed genes (DEGs) involved in the MAPK (mitogen-activated protein kinase) signaling pathway and members of bHLH (basic helix-loop-helix) transcription factors showed significant up- or down-regulation after heat stress. Next, to validate these findings, we conducted quantitative real-time PCR (qRT-PCR) analysis, which confirmed the expression patterns of the genes detected through RNA-Seq. Collectively, the DEGs between the two contrasting cultivars identified in our study provide novel insight into excavating helpful candidate genes associated with heat tolerance in bottle gourd.

Genome-Wide Identification, Evolution, and Expression Analysis of the MAPK Gene Family in Rosaceae Plants

Mitogen-activated protein kinases (MAPKs) are crucial regulators in coping with abiotic and biotic stresses, including drought, salinity, fungi, and pathogens. However, little is known about the characteristics, evolution process, and functional divergence of the MAPK gene family in Rosaceae plants. A total of 97 MAPK members were identified in six Rosaceae species, including 12 genes in Fragaria vesca, 22 genes in Malus domestica, 23 genes in Pyrus bretschneideri, 12 genes in Prunus mume, 14 genes in Prunus persica, and 14 genes in Rosa chinensis. All MAPK members of six Rosaceae plants were categorized into four clusters by the phylogenetic relationship analysis. Collinearity analysis discovered that both segmental duplication and tandem duplication contributed to the expansion of MAPK family genes in Rosaceae plants. And the analysis of motifs and gene structures indicated that the evolution of the MAPK gene family was highly conserved among phylogenetic clusters in Rosaceae species. In addition, the dN/dS rates of MAPK paralogous gene pairs were below one, suggesting the MAPK gene family in Rosaceae was driven by purifying selective pressure. Furthermore, functional divergence analysis discovered that 14 amino acid residues were detected as potentially key sites for functional divergence of MAPK family genes between different cluster pairs, specifically Type I functional divergence. The analysis of functional distance indicated that cluster C retained more of the original functional features, while cluster B exhibited functional specialization. Moreover, the expression profiles revealed that PmMAPK8, PmMAPK9, and PmMAPK10 were both highly expressed under drought stress and low temperature conditions. This study aims to comprehensively analyze the evolutionary process and functional analyses of the MAPK gene family in Rosaceae plants, which will lay the foundation for future studies into MAPK genes of Rosaceae in response to drought and cold stress.

The Role of BRAF Inhibitors in the Management of Ameloblastoma: A Literature Review.

Ameloblastoma is one of the most prevalent but enigmatic benign odontogenic tumors of the jaw, accounting for approximately 10% of all maxillary and mandibular tumors. This neoplasia is distinguished by exhibiting several clinical and histological variants along with several mutations that affect its behavior. The ameloblastoma treatment plan is determined by the tumor's size, anatomical location, histologic variant, and anatomical involvement. On chromosome 7, there is a proto-oncogene called BRAF. When BRAF is mutated, it becomes an oncogene and continuously produces proteins like MEK and ERK, members of mitogen-activated protein kinase (MAPK). In the signaling pathway, these proteins activate transcription factor inside the nucleus that helps in cell division and growth. Numerous neoplasms have been linked to more than 40 BRAF mutations. The most common one is BRAF proto-oncogene serine/threonine kinase (BRAF) V600E, whose treatment has been linked to a positive outcome. BRAF inhibitors like vemurafenib, dabrafenib, and sorafenib have shown excellent results, especially in metastatic ameloblastoma. BRAF, particularly in the case of metastatic ameloblastoma, inhibitors such as vemurafenib, dabrafenib, and sorafenib, has demonstrated outstanding results. Targeted therapies have been employed as adjuvant therapies to enhance cosmetic outcomes, even though no reports of serial cases demonstrate their effectiveness in ameloblastomas. In the treatment of ameloblastomas, the identification of BRAF V600E and additional mutations as the prime targeted therapies has proven to be a significant breakthrough where surgical treatment was contraindicated. In this article, we review the presence of BRAF V600E mutations, their inhibitors, and targeted therapies in ameloblastoma.

Kaempferol Suppresses Carbon Tetrachloride-Induced Liver Damage in Rats via the MAPKs/NF-κB and AMPK/Nrf2 Signaling Pathways.

Oxidative stress plays a critical role in the development of liver disease, making antioxidants a promising therapeutic approach for the prevention and management of liver injuries. The aim of this study was to investigate the hepatoprotective effects of kaempferol, an antioxidant flavonoid found in various edible vegetables, and its underlying mechanism in male Sprague-Dawley rats with carbon tetrachloride (CCl4)-induced acute liver damage. Oral administration of kaempferol at doses of 5 and 10 mg/kg body weight resulted in the amelioration of CCl4-induced abnormalities in hepatic histology and serum parameters. Additionally, kaempferol decreased the levels of pro-inflammatory mediators, TNF-α and IL-1β, as well as COX-2 and iNOS. Furthermore, kaempferol suppressed nuclear factor-kappa B (NF-κB) p65 activation, as well as the phosphorylation of Akt and mitogen-activated protein kinase members (MAPKs), including extracellular signal-regulated kinase, c-Jun NH2-terminal kinase, and p38 in CCl4-intoxicated rats. In addition, kaempferol improved the imbalanced oxidative status, as evidenced by the reduction in reactive oxygen species levels and lipid peroxidation, along with increased glutathione content in the CCl4-treated rat liver. Administering kaempferol also enhanced the activation of nuclear factor-E2-related factor (Nrf2) and heme oxygenase-1 protein, as well as the phosphorylation of AMP-activated protein kinase (AMPK). Overall, these findings suggest that kaempferol exhibits antioxidative, anti-inflammatory, and hepatoprotective effects through inhibiting the MAPK/NF-κB signaling pathway and activating the AMPK/Nrf2 signaling pathway in CCl4-intoxicated rats.

Genome-Wide Identification and Analysis of the MAPK and MAPKK Gene Families in Potato (Solanum tuberosum L.)

Mitogen-activated protein kinase (MAPK) is an important component of the signal transduction pathway, which plays important roles in regulating plant growth and development, and abiotic stress. Potato (Solanum tuberosum L.) is one of the most popular tuber crops in the world. Genome-wide identification and analysis of the MAPK and MAPKK gene family in potato is not clear. A total of 20 MAPK genes and 8 MAPKK genes were identified in the potato genome. A conservative motif analysis showed that the MAPK protein contained a typical TxY phosphorylation site, and the MAPKK protein contained a conservative characteristic motif S/T-x5-S/T. Phylogenetic analysis showed that potato MAPK (mitogen-activated protein kinase) and MAPKK (mitogen-activated protein kinase kinase) were similar to Arabidopsis, including four groups of members A, B, C and D. Gene structure and promoter sequence analysis showed that all 28 gene family members of potato Solanum tuberosum MAPK (StMAPK) and StMAPKK have coding regions (CDS), and family members in the same group have similar intron and exon compositions, and that most cis-acting elements upstream of gene promoters elements have related to stress response. Chromosome location analysis found that MAPKs were unevenly distributed on 11 chromosomes, while MAPKKs were only distributed on chromosomes Chr. 03 and Chr. 12. Collinearity analysis showed that StMAPKK3 and StMAPKK6 have the same common ancestors among potato, pepper, and tomato. qRT-PCR results showed that the relative expressions of StMAPK14 and StMAPKK2 were significantly upregulated under low-temperature stress. These results could provide new insights into the characteristics and evolution of the StMAPK and StMAPKK gene family and facilitate further exploration of the molecular mechanism responsible for potato abiotic stress responses.

Novel wiring of the AKT-RSK2 signaling pathway plays an essential role in cancer cell proliferation via a G1/S cell cycle transition

p90 Ribosomal S6 kinase 2 (RSK2), a member of mitogen-activated protein kinase regulating cell proliferation and transformation induced by tumor promoters, such as epidermal growth factor, plays a vital role as a signaling hub to modulate cell proliferation, transformation, cell cycle transition, and chromatin remodeling by tumor promoter stimulation such as epidermal growth factor. On the other hand, the RSK2-mediated signaling networks that regulate cancer cell proliferation are unclear. In this study, SKOV3, an ovarian cancer cell that exhibits chemoresistant properties, and TOV-112D cells showed different sensitivities to colony growth in soft agar. Based on the protein profile shown in a previous report, RSK2 knockdown preferentially and significantly suppressed cell proliferation and colony growth. Moreover, RSK2 interacted with AKTs (AKT 1-3) via the N-terminal kinase domain (NTKD) of RSK2, resulting in the phosphorylation of RSK2. The AKT-mediated phosphorylation consensus sequence, RxRxxS/T, on RSK2 NTKD (Thr115) was well conserved in different species. In particular, an in vitro kinase assay showed that NTKD deleted and Thr115Ala mutants of RSK2 abolished AKT1-mediated phosphorylation. In the physiological assay of RSK2 phosphorylation at Thr115 on cell proliferation, AKT1-mediated RSK2 phosphorylation at Thr115 played an essential role in cell proliferation. The re-introduction of RSK2-T115A to RSK2−/− MEF attenuated the EGF-induced G1/S cell cycle transition compared to RSK2-wt introducing RSK2−/− MEFs. This attenuation was observed by EGF stimulations and insulin-like growth factor-1. Overall, these results show that novel wiring of the AKT/RSKs signaling axis plays an important role in cancer cell proliferation by modulating the G1/S cell cycle transition.

Exploring modulations in T-cell receptor-mediated T-cell signaling events in systemic circulation and at local disease site of patients with tubercular pleural effusion: An attempt to understand tuberculosis pathogenesis at the local disease site.

T cells are crucial for pathogenesis as well as control for tuberculosis (TB). Although much is known about the signaling pathways which are required for the activation of T cells during acute infection but the way these cells respond during persistent of infection still remained elusive. Therefore, it is rationale to understand T cell activation during tuberculous pleural effusion (TPE), which is similar to bacterial persistency system. Herein, we will employ T cell receptor (TCR) based approaches for studying events of T cell activation pathways in cells of blood and pleural fluid among patients with TPE. We performed spectrofluorimetric analysis to study effect of M. tuberculosis antigens, ESAT-6 and Ag85A stimulation on intracellular calcium levels, Phosphorylation levels of ZAP-70 (Zeta-chain-associated protein kinase 70), PKC-θ (Protein kinase C theta), Erk1/2 (Extracellular signal-regulated kinase 1 and 2) and p-38 two important members of MAPKs (Mitogen activated Protein kinases) in CD3 and CD28 induced cells of blood and pleural fluid of same patients with TPE by western blotting. Patients with non-TPE were also included as matching disease controls in this study. We observed significantly higher intracellular calcium levels, Phosphorylation levels of ZAP-70, Erk1/2 and p-38 in CD3 and CD28 induced cells of pleural fluid as compared to the blood cells of same patients with TPE. Alteration in the activation of these events has also been noted after stimulation of ESAT-6 and Ag85A. Present study demonstrated up-regulated activation of TCR mediated T cell signaling events at local disease site (Pleural fluid) as compared to the blood sample of TB pleurisy patients which could be involved in T-cell dysfunctioning during the progression of the disease and also could be responsible for Th 1 dominance at local disease site in patients with TPE.

Evolution of mitogen-activated protein kinase family and their immune function in Apostichopus japonicus

The mitogen-activated protein kinase family plays an important role in cell differentiation, growth, proliferation, and survival. However, the current research on the mitogen-activated protein kinase (MAPK) family in invertebrates is limited to the individual gene, and the analysis has not been conducted at the family level. In the present study, echinoderm MAPK family was identified by genomic screening, and five members, including three ERK subfamily members, one c-Jun N-terminal kinase (JNK) subfamily, and one p38-MAPK member were detected. Phylogenetic analysis showed that three MAPK subfamilies were separated into three separated clusters, and ERK subfamily appeared earlier than the other two subfamilies. Synteny analysis revealed that the p38 subfamily might be derived from the continuous gene duplication events of MAPK14 subfamily in invertebrates, which displayed genome expansion via gene duplication in vertebrates. The role of MAPK family in echinoderm immune defense was determined by investigating the expression profiles of MAPKs in Vibrio splendidus-challenged Apostichopus japonicus and LPS-exposed coelomocytes. The result showed that five MAPK members displayed induced expression profiles both in vitro and in vivo, and the peak expression was detected at different time points. Our study provides new insights into the evolutionary history of the MAPK family and show the similar immune function among MAPK members.

Regulatory Mechanisms of Mitogen-Activated Protein Kinase Cascades in Plants: More than Sequential Phosphorylation.

Mitogen-activated protein kinase (MAPK) cascades play crucial roles in almost all biological processes in plants. They transduce extracellular cues into cells, typically through linear and sequential phosphorylation and activation of members of the signaling cascades. However, accumulating data suggest various regulatory mechanisms of plant MAPK cascades in addition to the traditional phosphorylation pathway, in concert with their large numbers and coordinated roles in plant responses to complex ectocytic signals. Here, we highlight recent studies that describe the uncanonical mechanism of regulation of MAPK cascades, regarding the activation of each tier of the signaling cascades. More particularly, we discuss the unusual role for MAPK kinase kinases (MAPKKKs) in the regulation of MAPK cascades, as accumulating data suggest the non-MAPKKK function of many MAPKKKs. In addition, future work on the biochemical activation of MAPK members that needs attention will be discussed.

Low-doses of aspirin promote the growth of human PC-9 lung cancer cells through activation of the MAPK family.

Aspirin has been reported for its anti-tumor activity, however, there are few studies on its effects in lung cancer. The present study found that aspirin had a dual role in the proliferation of human lung cancer PC-9 (formerly known as PC-14) and A549 cells, and in human colon cancer HCT116 cells. The cells were treated with 0, 1, 2, 4, 8 and 16 mM aspirin for 24-72 h or 7-12 days and cell proliferation was examined by MTT and colony formation assay. In order to explore the relationship between the proliferation-enhancing effect of low-dose aspirin and mitogen-activated protein kinase (MAPK) signaling activation, PC-9 cells were pretreated with 10 µM PD98059 (a specific inhibitor of ERK), SB203580 (a specific inhibitor of p38) and SP600125 (a specific inhibitor of JNK) for 30 min respectively. Western blot assay was performed to detect the activation of MAPK members in PC-9 cells. Cellular apoptosis was detected using flow cytometer-based Annexin V/propidium iodide dual staining. An assessment of MAPK inhibitors was performed to further validate the role of JNK, p38 and ERK in aspirin-promoted PC-9 cell growth. It was demonstrated that aspirin could promote the growth of human PC-9 lung cancer cells and induced MAPK activation at low concentrations. All the MAPK inhibitors tested (PD98059, SB203580 and SP600125) were able to inhibit the aspirin-induced proliferation of PC-9 cells.

F-box Protein βTrCP1 Is a Substrate of Extracellular Signal-regulated Kinase 2.

F-box proteins, consisting of 69 members which are organized into the three subclasses FBXW, FBXL, and FBXO, are the substrate specific recognition subunits of the SKP1-Cullin 1-F-box protein E3 ligase complex. Although βTrCP 1 and 2, members of the FBXW subfamily, are known to regulate some protein stability, molecular mechanisms by which these proteins can recognize proper substrates are unknown. In this study, it was found that βTrCP1 showed strong interaction with members of mitogen-activated protein kinases. Although extracellular signal-regulated kinase (ERK) 3, p38β, and p38δ showed weak interactions, ERK2 specifically interacted with βTrCP1 as assessed by immunoprecipitation. In interaction domain determination experiments, we found that ERK2 interacted with two independent ERK docking sites located in the F-box domain and linker domain, but not the WD40 domain, of βTrCP1. Notably, mutations of βTrCP1 at the ERK docking sites abolished the interaction with ERK2. βTrCP1 underwent phosphorylation by EGF stimulation, while the presence of the mitogen-activated protein kinase kinases inhibitor U0126, genetic silencing by sh-ERK2, and mutation of the ERK docking site of βTrCP1 inhibited phosphorylation. This inhibition of βTrCP1 phosphorylation resulted in a shortened half-life and low protein levels. These results suggest that ERK2-mediated βTrCP1 phosphorylation may induce the destabilization of βTrCP1.

Anti-inflammation of epicatechin mediated by TMEM35A and TMPO in bovine mammary epithelial cell line cells and mouse mammary gland

Epicatechin (EC) has significant antiinflammation, antioxidation, and anticancer activities. It also provides a new alternative treatment for mastitis, which can result in great economic losses in the dairy industry if left untreated. The purpose of this study was to investigate the anti-inflammatory effects of EC on mastitis and the underlying mechanism using in vivo and in vitro systems. The use of ELISA and immunohistochemistry assays showed that EC treatment at 1.5, 7.5, 15, and 30 mg/mL decreased protein expression of inflammatory mediators, including cyclooxygenase-2 and inducible nitric oxide synthase; inflammatory cytokines, which were composed of IL-1β, TNF-α, and IL-6 in lipopolysaccharide (LPS)-stimulated bovine mammary epithelial cell line (MAC-T); and mouse mammary gland, together with reduced filtration of T lymphocytes in the mouse mammary gland. Furthermore, EC treatment reduced LPS-induced phosphorylation levels of p65 and inhibitor of NF-κB, and blocked nuclear translocation of p65 as revealed by western blot and immunofluorescence test in MAC-T cells and the mouse mammary gland. Epicatechin also attenuated LPS-induced phosphorylation levels of mitogen-activated protein kinase members (i.e., p38, c-Jun N-terminal kinase 1/2 and extracellular regulated protein kinases 1/2). Using RNA-seq and tandem mass tag analyses, upregulation of TMEM35A and TMPO proteins was disclosed in MAC-T cells cotreated with LPS and EC. Although clustered regularly interspaced short palindromic repeats/Cas9-based knockdown of TMEM35A and TMPO attenuated abundance of phosphorylated (p)-p65, p-p38, TNF-α, and iNOS, overexpression of TMEM35A reversed EC-mediated effects in TMPO knockdown cells. Moreover, interaction between TMEM35A and TMPO was detected using the co-immunoprecipitation method. In conclusion, our data demonstrated that EC inhibited LPS-induced inflammatory response in MAC-T cells and the mouse mammary gland. Importantly, TMEM35A mediated the transmembrane transport of EC, and the interaction between TMEM35A and TMPO inhibited MAPK and NF-κB pathways.

Association analysis of GmMAPKs and functional characterization of GmMMK1 to salt stress response in soybean.

Salinity is one of the major abiotic constraints affecting the growth and yield of plants including soybean. In this context, the previous studies have documented the role of the mitogen-activated protein kinase (MAPK) cascade in the regulation of salt signaling in model plants. However, there is not a systematic analysis of salt-related MAPKs in soybean. Hence, in this study, we identified a total of 32 GmMAPKs via., genome-wide reanalysis of the MAPK family using the soybean genome v4.0. Based on the transcriptome datasets in the public database, we observed that GmMAPKs are induced by different abiotic stresses, especially salt stress. Furthermore, based on the candidate gene association mapping and haplotype analysis of the GmMAPKs, we identified a salt-related MAPK member, GmMMK1. GmMMK1 possesses significant sequence variations, which affect salt tolerance in soybean at the germination stage. Besides, the overexpression of the GmMMK1 in soybean hairy roots has a significant negative effect on the root growth, leading to increased sensitivity of the GmMMK1-OE plants to salt stress. Moreover, the heterologous expression of the GmMMK1 in Arabidopsis has been also observed to have a negative effect on the germination and root growth under salt stress. The transcriptome analysis and yeast two-hybrid screening showed that hormone signaling and the homeostasis of reactive oxygen species are involved in the GmMMK1 regulation network. In conclusion, the results of this work demonstrated that GmMMK1 is an important negative regulator of the salt stress response, and provides better insights for understanding the role of the MAPKs in soybean salt signaling.

A novel JNK induces innate immune response by activating the expression of antimicrobial peptides in Chinese mitten crab Eriocheir sinensis

c-Jun NH2-terminal kinase (JNK) is a member of mitogen-activated protein kinases (MAPKs) that participates in the regulation of various physiological and pathological processes. In this study, we identified a novel JNK (EsJNK) and determined the cDNA sequence of its isoform (EsJNK-a) from the Chinese mitten crab Eriocheir sinensis. The open reading frame (ORF) of EsJNK was predicted to encode 421 peptides with a serine/threonine protein kinase, a catalytic (S_TKc) domain, and a low complexity region. The ORF of EsJNK-a was 1380 bp encoding a protein with 459 amino acids, which was 38 amino acids more than that of EsJNK. The predicted tertiary structure of EsJNK was conserved and contained 15 α-helices and 10 β-sheets. Phylogenetic tree analysis revealed that EsJNK was clustered with the JNK homologs of other crustaceans. Quantitative real-time PCR assays showed that EsJNK was expressed in all the tissues examined, but it was relatively higher in hemocytes, muscles, and intestines. The expression of EsJNK mRNA in the hemocytes was upregulated by lipopolysaccharides and peptidoglycans, as well as by Staphylococcus aureus or Vibrio parahaemolyticus challenge. Functionally, after silencing EsJNK by siRNA in crabs, the expression levels of two antimicrobial peptides (AMPs), namely, anti-lipopolysaccharide factor and crustin, were significantly inhibited. The purified recombinant EsJNK protein with His-tag accelerated the elimination of the aforementioned bacteria in vivo. However, knockdown of EsJNK had an opposite effect. These findings suggested that EsJNK might be involved in the antibacterial immune defense of crabs by regulating the transcription of AMPs.

Role of extracellular signal-regulated kinase 1/2 signaling underlying cardiac hypertrophy.

Cardiac hypertrophy is the result of increased myocardial cell size responding to an increased workload and developmental signals. These extrinsic and intrinsic stimuli as key drivers of cardiac hypertrophy have spurred efforts to target their associated signaling pathways. The extracellular signal-regulated kinases 1/2 (ERK1/2), as an essential member of mitogen-activated protein kinases (MAPKs), has been widely recognized for promoting cardiac growth. Several modified transgenic mouse models have been generated through either affecting the upstream kinase to change ERK1/2 activity, manipulating the direct role of ERK1/2 in the heart, or targeting phosphatases or MAPK scaffold proteins to alter total ERK1/2 activity in response to an increased workload. Using these models, both regulation of the upstream events and modulation of each isoform and indirect effector could provide important insights into how ERK1/2 modulates cardiomyocyte biology. Furthermore, a plethora of compounds, inhibitors, and regulators have emerged in consideration of ERK, or its MAPK kinases, are possible therapeutic targets against cardiac hypertrophic diseases. Herein, is a review of the available evidence regarding the exact role of ERK1/2 in regulating cardiac hypertrophy and a discussion of pharmacological strategy for treatment of cardiac hypertrophy.

JNK signaling as a target for anticancer therapy.

The JNKs are members of mitogen-activated protein kinases (MAPK) which regulate many physiological processes including inflammatory responses, macrophages, cell proliferation, differentiation, survival, and death. It is increasingly clear that the continuous activation of JNKs has a role in cancer development and progression. Therefore, JNKs represent attractive oncogenic targets for cancer therapy using small molecule kinase inhibitors. Studies showed that the two major JNK proteins JNK1 and JNK2 have opposite functions in different types of cancers, which need more specification in the design of JNK inhibitors. Some of ATP- competitive and ATP non-competitive inhibitors have been developed and widely used in vitro, but this type of inhibitors lack selectivity and inhibits phosphorylation of all JNK substrates and may lead to cellular toxicity. In this review, we summarized and discussed the strategies of JNK binding inhibitors and the role of JNK signaling in the pathogenesis of different solid and hematological malignancies.

RhTSG-6 inhibits IL-1β-induced extracellular matrix degradation and apoptosis by suppressing the p38, and JNK pathways in nucleus pulposus cells.

Intervertebral disc degeneration (IDD) is one of the major causes of low back pain (LBP) which seriously affects health and normal physical activity. Recombinant human tumor necrosis factor-a (TNF-a) induced protein 6 (rhTSG-6) has been reported to have therapeutic effects on a variety of inflammatory diseases, but the effect and mechanism of rhTSG-6 action in IDD are not fully understood. The present study was aimed to explore the functional role of rhTSG-6 in interleukin (IL)-1b-induced nucleus pulposus (NP) cell model. Experimental human NP cells were isolated from the patients with idiopathic scoliosis and treated with culture medium containing IL-1b (10 ng/mL) for 24 hours to induce extracellular matrix degradation and apoptosis, simulating an IDD model in vitro. The viability of NP cells was analyzed by the CCK-8 assay. The relevant mRNA and protein levels were measured by RT-qPCR and western blot. The apoptosis of NP cells was determined by flow cytometry analysis and western blot. Compared with the NP cells without IL-1b treatment, IL-1b caused approximately 70% reduction in the viability of NP cells, while RhTSG-6 partly increased the decrease of IL-1b on cell viabilities. Moreover, treatment with rhTSG-6 considerably attenuated the upregulation of extracellular matrix (ECM)-catabolic factors (MMP-3, MMP-13, ADAMTS-4, and ADAMTS-5), and increased the downregulation of ECM-anabolic factor (collagen II) in NP cells induced by IL-1b, indicating that ECM degradation was suppressed. Furthermore, rhTSG-6 also protected NP cells from IL-1b-induced apoptosis. Mechanically, rhTSG-6 inhibited the activation of members of mitogen-activated protein kinase (MAPK) pathway by blocking the phosphorylation of p38, c-Jun N-terminal kinase (JNK) and ERK in IL-1b-induced NP cells. RhTSG-6 can attenuate ECM degradation and apoptosis in IL-1b-induced NP cells by inhibiting the p38, JNK and ERK pathways, which may contribute to its potential application in the therapy of IDD.

Impact of Conventional and Atypical MAPKs on the Development of Metabolic Diseases.

The family of mitogen-activated protein kinases (MAPKs) consists of fourteen members and has been implicated in regulation of virtually all cellular processes. MAPKs are divided into two groups, conventional and atypical MAPKs. Conventional MAPKs are further classified into four sub-families: extracellular signal-regulated kinases 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK1, 2 and 3), p38 (α, β, γ, δ), and extracellular signal-regulated kinase 5 (ERK5). Four kinases, extracellular signal-regulated kinase 3, 4, and 7 (ERK3, 4 and 7) as well as Nemo-like kinase (NLK) build a group of atypical MAPKs, which are activated by different upstream mechanisms than conventional MAPKs. Early studies identified JNK1/2 and ERK1/2 as well as p38α as a central mediators of inflammation-evoked insulin resistance. These kinases have been also implicated in the development of obesity and diabetes. Recently, other members of conventional MAPKs emerged as important mediators of liver, skeletal muscle, adipose tissue, and pancreatic β-cell metabolism. Moreover, latest studies indicate that atypical members of MAPK family play a central role in the regulation of adipose tissue function. In this review, we summarize early studies on conventional MAPKs as well as recent findings implicating previously ignored members of the MAPK family. Finally, we discuss the therapeutic potential of drugs targeting specific members of the MAPK family.

Time course study of ERK1/2 activity and cell viability in lipopolysaccharide challenged PC12 cells

Introduction: Extracellular signal-regulated kinase 1 and 2 (ERK1/2) are important members of mitogen-activated protein kinases (MAPK), which are actively involved in the shaping of cellular responses to different stimuli; however, these responses are somehow contradicting. It is believed that time is a crucial factor in the determination of these effects. Therefore, the present work was designed to obtain a more vivid view about the effect of time on ERK activity and its relation to cell viability. Methods: In the first step, we challenged cultured PC12 cells with different doses of lipopolysaccharides (LPS) for different time intervals (3, 6, 24 and 48h) and the cell viability was checked by MTT test. Thereafter, we cultured the cells in 6-well plates and treated them with the effective dose (10μg/ml) for the abovementioned intervals and the level of ERK phosphorylation, as the active form, was assessed in the Western blotting analysis. Results: The results showed that treating cells with 10μg/ml LPS reduces cell viability after 48h. While being ineffective in shorter periods of time, ERK activity has a fluctuating trend, so that it reaches the highest level at 6h, thereafter it declines to the lowest level at 24h and partially increases again at 48h. Conclusion: These results imply that time is a determinant factor in the activity of ERK and single-point assessments may result in misinterpretation.