Identification Of Mitogen-activated Protein Kinase Research Articles

Identification of Mitogen-activated Protein Kinase from Schizochytrium sp. and Application in Resisting Stress Environments

Identification of Mitogen-activated Protein Kinase from Schizochytrium sp. and Application in Resisting Stress Environments

Genome-wide identification of mitogen-activated protein kinase (MAPK) gene family in yellow catfish (Pelteobagrus fulviadraco) and their expression profiling under the challenge of Aeromonas hydrophila.

As serine/threonine protein kinases, mitogen-activated protein kinases (MAPK) take part in cellular metabolism. This work found 14 MAPK genes in the yellow catfish (Pelteobagrus fulviadraco) genome and evaluated their taxonomy, conserved domains and evolutionary linkages for a better understanding of the MAPK gene family's evolutionary relationship and antibacterial immune response. The findings revealed that several MAPK genes are activated in response to immunological and inflammatory responses. Collinearity research revealed that in yellow catfish and zebrafish, there are six pairs of highly similar MAPK genes, indicating that these genes have been more conserved throughout evolution. The MAPK gene quantification findings revealed that JNK1a, JNK1b, p38delta and p38alpha b expression levels were considerably upregulated, indicating that they act in fish innate immunity. The findings implied that MAPK genes may involve in defence against detrimental microbe in yellow catfish, which will help researchers better understand how MAPK genes work in the innate immune system.

Epigenetic identification of mitogen-activated protein kinase 10 as a functional tumor suppressor and clinical significance for hepatocellular carcinoma.

BackgroundMitogen-activated protein kinase 10 (Mapk10) is a member of the c-jun N-terminal kinases (jnk) subgroup in the MAPK superfamily, and was proposed as a tumor suppressor inactivated epigenetically. Its role in hepatocellular carcinoma (HCC) has not yet been illustrated. We aimed to investigate the expression and epigenetic regulation of mapk10 as well as its clinical significance in HCC.ResultsMapk10 was expressed in almost all the normal tissues including liver, while we found that the protein expression of MAPK10 was significantly downregulated in clinical samples of HCC patients compared with these levels in adjacent normal tissues (29/46, P < 0.0001). Clinical significance of MAPK10 expression was then assessed in a cohort of 59 HCC cases, which indicated its negative expression was significantly correlated with advanced tumor stage (P = 0.001), more microsatellite nodules (P = 0.025), higher serum AFP (P = 0.001) and shorter overall survival time of HCC patients. Methylation was further detected in 58% of the HCC cell lines we tested and in 66% of primary HCC tissues by methylation-specific PCR (MSP), which was proved to be correlated with the silenced or downregulated expression of mapk10. To get the mechanisms more clear, the transcriptional silencing of mapk10 was reversed by pharmacological demethylation, and ectopic expression of mapk10 in silenced HCC cell lines significantly inhibited the colony formation ability, induced apoptosis, or enhanced the chemosensitivity of HCC cells to 5-fluorouracil.ConclusionMapk10 appears to be a functional tumor suppressor gene frequently methylated in HCC, which could be a valuable biomarker or a new diagnosis and therapy target in a clinical setting.

Genome-wide identification of mitogen-activated protein kinase (MAPK) cascade and expression profiling of CmMAPKs in melon (Cucumis melo L.).

Mitogen-activated protein kinase (MAPK) is a form of serine/threonine protein kinase that activated by extracellular stimulation acting through the MAPK cascade (MAPKKK-MAPKK-MAPK). The MAPK cascade gene family, an important family of protein kinases, plays a vital role in responding to various stresses and hormone signal transduction processes in plants. In this study, we identified 14 CmMAPKs, 6 CmMAPKKs and 64 CmMAPKKKs in melon genome. Based on structural characteristics and a comparison of phylogenetic relationships of MAPK gene families from Arabidopsis, cucumber and watermelon, CmMAPKs and CmMAPKKs were categorized into 4 groups, and CmMAPKKKs were categorized into 3 groups. Furthermore, chromosome location revealed an unevenly distribution on chromosomes of MAPK cascade genes in melon, respectively. Eventually, qRT-PCR analysis showed that all 14 CmMAPKs had different expression patterns under drought, salt, salicylic acid (SA), methyl jasmonate (MeJA), red light (RL), and Podosphaera xanthii (P. xanthii) treatments. Overall, the expression levels of CmMAPK3 and CmMAPK7 under different treatments were higher than those in control. Our study provides an important basis for future functional verification of MAPK genes in regulating responses to stress and signal substance in melon.

Identification of MAPKs as signal transduction components required for the cell death response during compatible infection by the synergistic pair Potato virus X-Potato virus Y

Systemic necrosis is one of the most severe symptoms caused in compatible plant-virus interactions and shares common features with the hypersensitive response (HR). Mitogen-activated protein kinase (MAPK) cascades are associated with responses to compatible and incompatible host-virus interactions. Here, we show that virus-induced gene silencing of the Nicotiana benthamiana MAPK genes salicylic acid-induced protein kinase (SIPK) and wound-induced protein kinase (WIPK), and the MAPK kinase (MAPKK) genes MEK1 and MKK1, partially compromised the HR-like response induced by the synergistic interaction of Potato virus X with Potato virus Y (PVX-PVY). Nevertheless, ameliorated cell death induced by PVX-PVY in the MAPK(K)-silenced plants did not facilitate virus accumulation in systemically infected leaves. Dual silencing of SIPK and of the oxylipin biosynthetic gene 9-Lipoxygenase showed that the latter was epistatic to SIPK in response to PVX-PVY infection. These findings demonstrate that SIPK, WIPK, MEK1 and MKK1 function as positive regulators of PVX-PVY-induced cell death.

Abstract 557: Identification of mitogen-activated protein kinases which are required for the growth of triple-negative breast cancers.

Abstract Background: Breast cancer is the most frequently diagnosed malignancy (besides non-melanoma skin cancer) and is the second leading cause for cancer-related death among US women. Most breast cancers overexpress the estrogen receptor (ER) or, to a lesser extent, the HER2 receptor and thus are responsive to hormonal therapies. However nearly a quarter of patients do not express ER, HER2, or progesterone receptor (“triple-negative breast cancer”) and are clinically managed as a single disease with nonspecific chemotherapies. Novel targeted therapies are urgently needed to treat these aggressive cancers. Recent large-scale studies integrating multiple dimensions of genomic data have revealed that alterations to the MAP kinase pathways are critical for the development and progression of triple-negative cancers (TNBCs). In particular, mutations in MAP3K genes have been associated with receptor-negative tumors. In this study, we hypothesized that TNBCs depend on unique MAP3K proteins distinct from those required by non-TNBCs to transduce growth signals. Methods: We performed an unbiased screen of the MAP3K family to identify genes critical for growth and tumorigenicity in six TNBC and six ER-positive cell lines. Pools of siRNA were deposited into optical microplates and cell lines were liposomally reverse-transfected. Depending on the growth rate, cells were stained with DAPI at 4 or 6 days post-transfection and nuclei were detected by high-throughput microscopy. To test for inhibition of anchorage-independent growth, cells were transfected with siRNA and the next day seeded in soft agar in 6-well dishes. Colonies were counted by machine at 1-3 weeks and compared to control siRNA-treated cells. For death assays, siRNA-treated cells were grown for 2 days and collected for western blot detection of annexin V and cleaved caspase 3. Results: We determined that MAP3K3 (MEKK3) and TAO2 (MAP3K17) are essential for anchorage-dependent growth of TNBC cells, but are not required for the proliferation of ER-positive cell lines. Among the TNBC cells, there were variable responses to knockdown of these kinases. While the growth of MDA-MB-231, HCC70, and HCC1937 cells were greatly inhibited after MAP3K3 knockdown, the growth of HCC1937 cells was unaffected by MAP3K3 knockdown but was instead suppressed by TAO2 inhibition. Knockdown of MAP3K3 and TAO2 also resulted in a dramatic reduction of anchorage-independent colony formation in these TNBC cells but not in ER-positive lines. We demonstrated that this reduction in growth is due to suppression of proliferation, and not by induction of apoptosis via annexin V apoptotic assay and detection of cleaved caspases. Conclusion: These data suggest that TNBCs evolve a dependence on specific MAP kinase pathways, and that targeting MAP3K3 and TAO2 may be an effective strategy to treat the subset of TNBCs that rely on these molecules to potentiate growth. Citation Format: Graham M. Poage, Abhijit Mazumdar, Ivan P. Uray, Powel H. Brown. Identification of mitogen-activated protein kinases which are required for the growth of triple-negative breast cancers. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 557. doi:10.1158/1538-7445.AM2013-557

Identification of MAPKs and Their Possible MAPK Kinase Activators Involved in the Pto-mediated Defense Response of Tomato

The Pto kinase mediates resistance to bacterial speck disease in tomato by activating host defenses upon recognition of Pseudomonas syringae pv. tomato strains expressing the AvrPto or AvrPtoB proteins. Previous gene-silencing experiments have indicated that mitogen activated protein kinase (MAPK) cascades play a key role downstream of the Pto kinase to activate host defense responses. Here we use biochemical methods to demonstrate that two tomato MAPKs, LeMPK2 and LeMPK3, are activated in leaves in a Pto-specific manner upon expression of AvrPto and AvrPtoB. We show that these same MAPKs are activated upon overexpression of LeMAPKKKalpha, a protein previously demonstrated to be involved in Pto-mediated immunity. We identified two phylogenetically unrelated MAPK kinases (LeMKK2 and LeMKK4) that when overexpressed in leaves elicit cell death and activate LeMPK2 and LeMPK3. In vitro analysis demonstrated that LeMKK2 and LeMKK4 each phosphorylate the same subset of three MAPKs. Together these data provide biochemical evidence for the involvement of MAPK cascades in Pto-mediated resistance.

Differential activation of MAPK signaling pathways by TGF-beta1 forms the molecular mechanism behind its dose-dependent bidirectional effects on hematopoiesis.

We have earlier reported that transforming growth factor-beta1 (TGF-beta1), a well-known inhibitor of hematopoiesis, stimulated colony formation from adult human bone marrow mononuclear cells (BM MNC) when used at low concentrations. We examined the possible molecular mechanism behind this bidirectional effect using CD34+ cells isolated from human BM for clonal assays and the KG1a cell line as a model system for analysis of proteins for signaling pathways by immunoblotting. We found that TGF-beta1 at low doses (picogram levels) stimulated the colony formation from CD34+ cells, indicating that these progenitors form the direct target of stimulatory action of TGF-beta1. CD34+ cells were found to be more sensitive to the TGF-beta1 concentration than the total MNC. We used the KG1a cell line as a model system for identification of mitogen-activated protein kinase (MAPK) and AKT signaling pathways involved in the process. Low doses strongly induced p44/42 MAPK phosphorylation, whereas high doses induced p38 activation. Use of specific p44/42 MAPK inhibitor PD 98059 in the colony assay abrogated the stimulatory effect of low TGF-beta1. On the other hand, use of p38 MAPK inhibitor SB 203580 along with low TGF-beta1 concentrations had a synergistic effect on stimulation of colony formation. Treatment of BM MNC with Anisomycin, which activates stress kinases, resulted in a dose-dependent inhibition of colony formation. This inhibition could not be rescued by stimulatory doses of TGF-beta1. Phosphorylation of AKT was found to occur in a dose-dependent way but declined slightly at the highest concentration used (10 ng/ml). Inhibition of the AKT pathway by LY 294002 strongly suppressed colony formation. These data indicate clearly that sustained activation of p44/42 MAPK perhaps forms the stimulatory signal induced by low TGF-beta1, whereas activation of p38 forms the inhibitory pathway.

Crosstalk between the phosphatidylinositol cycle and MAP kinase signaling pathways in Xenopus mesoderm induction.

Recent studies have established a role for the phosphoinositide (PI) cycle in the early patterning of Xenopus mesoderm. In explants, stimulation of this pathway in the absence of growth factors does not induce mesoderm, but when accompanied by growth factor treatment, simultaneous PI cycle stimulation results in profound morphological and molecular changes in the mesoderm induced by the growth factor. This suggests the possibility that the PI cycle exerts its influence via crosstalk, by modulating some primary mesoderm-inducing pathway. Given recent identification of mitogen-activated protein kinase (MAPK) as an intracellular mediator of some mesoderm-inducing signals, the present study explores MAPK as a potential site of PI cycle-mediated crosstalk. We report that MAPK activity, like PI cycle activity, increases in intact embryos during mesoderm induction. Phosphoinositide cycle stimulation during treatment of explants with basic fibroblast growth factor (bFGF) synergistically increases late-phase MAPK activity and potentiates bFGF-induced expression of Xbra, a MAPK-dependent mesodermal marker.