• The Plant Pathology Journal
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• 제33권2호
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• pp.163-169
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• 2017

$SIMAPKKK{\alpha}$, a tomato (Solanum lycopersicum) mitogen-activated protein kinase kinase kinase, is a positive regulator of Pto-mediated effector-triggered immunity, which elicits programmed cell death (PCD) in plants. In this study, we examined whether putative phosphorylation sites in the conserved activation segment of the $SIMAPKKK{\alpha}$ kinase domain are critical for eliciting PCD. Three amino acids, $threonine^{353}$, $serine^{360}$ ($Ser^{360}$), or $serine^{364}$ ($Ser^{364}$), in the conserved activation segment of $SIMAPKKK{\alpha}$ kinase domain were substituted to alanine (T353A, S360A, or S364A), and these variants were transiently expressed in tomato and Nicotiana benthamiana plants. Two alanine substitutions, S360A and S364A, completely abolished $SIMAPKKK{\alpha}$ PCD-eliciting activity in both plants, while T353A substitution did not affect its PCD-eliciting activity. $SIMAPKKK{\alpha}$ wild type and variant proteins accumulated to similar levels in plant leaves. However, $SIMAPKKK{\alpha}$ protein with the largest size was missed when either S360A or S364A substitutions were expressed, whereas proteins with the smaller masses were more accumulated than those of full-length of $SIMAPKKK{\alpha}$ and T353A. These results suggest that phosphorylation of $SIMAPKKK{\alpha}$ at $Ser^{360}$ and $Ser^{364}$ is critical for PCD elicitation in plants.

• 통합자연과학논문집
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• 제10권2호
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• pp.95-104
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• 2017

Proviral Integration site of Moloney (Pim) murine Leukemia virus kinases is a serine/threonine specific protein kinase. It is largely involved in cell survival and proliferation. Pim-1 phosphorylates multiple cellular substrates to inhibit apoptosis and promote cell cycle progression. Over expression of Pim-1 kinase is observed in a range of malignancies and various solid cancers. High level of Pim-1 expression is seen in myeloma, acute myeloid leukemia, prostate cancer and liver carcinomas. Hence, Pim-1 is considered as an interesting cancer target. In the present study, we have performed region-focused CoMFA study on a series of imidazopyridazine derivatives as Pim-1 kinase inhibitors. A statistically acceptable region-focused CoMFA model ($q^2=0.571$; ONC=3; $r^2=0.909$) was developed. The model was then validated using Bootsrapping and progressive sampling. The contour map highlighted the regions favorable to increase the activity. Bulky substitutions in $R^2$ position of the phenyl ring could increase the activity. Similarly, small negative substitution in the $R^1$ position of the Pyridine ring could increase the activity considerably. Our results will be useful to design novel Pim-1 kinase inhibitors of this series.

• 한국발생생물학회지:발생과생식
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• 제18권1호
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• pp.65-71
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• 2014

Cell cycle process is regulated by a number of protein kinases and among them, serine/threonine kinases carry phosphate group from ATP to substrates. The most important three kinase families are Cyclin-dependent kinase (Cdk), Polo-like kinase (Plk), and Aurora kinase. Polo-like kinase family consists of 5 members (Plk1-Plk5) and they are involved in multiple functions in eukaryotic cell division. It regulates a variety of aspects such as, centrosome maturation, checkpoint recovery, spindle assembly, cytokinesis, apoptosis and many other features. Recently, it has been reported that Plks are related to tumor development and over-expressed in many kinds of tumor cells. When injected the anti-Plk antibody into human cells, the cells show aneuploidy, and if inhibit Plks, most of the mitotic cell division does not proceed properly. For that reasons, many inhibitors of Plk have been recently emerged as new target for remedy of the cancer therapeutic research. In this paper, we reviewed briefly the characteristics of Plk families and how Plks work in regulating cell cycles and cancer formation, and the possibilities of Plks as target for cancer therapy.

• Reproductive and Developmental Biology
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• 제35권4호
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• pp.499-502
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• 2011

Aurora A kinase is a mitotic serine/threonine kinase whose proposed functions include the maturation of centrosomes, G2/M transition, alignment of chromosomes at metaphase, and cytokinesis. In this study, we investigated the effect of MLN8237, an aurora A kinase inhibitor, on the postovulatory aging of oocytes based on the frequency of oocyte fragmentation, cdk1 kinase activity, and cyclin B degradation. The fragmentation of ovulated oocytes during prolonged culture was inhibited by treatment with MLN8237 in a concentration-dependent manner. The frequency of fragmented oocytes was significantly lower in oocytes treated with 2 ${\mu}M$ MLN8237 (13%) than in control oocytes (64%) after two days of culture. Most of the control (non-fragmented) oocytes (91%) were activated after two days of culture. In comparison, only 22% of the MLN8237-treated oocytes were activated; the rest of the oocytes (78%) were still in metaphase with an abnormal spindle and dispersed chromosomes. Next, cdk1 activity and the level of cyclin B were examined. The level of cyclin B and cdk1 activity in MLN8237-treated oocytes were nearly equal to those in control oocytes. Our results indicate that MLN8237 inhibited the fragmentation of ovulated oocytes during prolonged culture, although it blocked the spontaneous decrease in activity of cdk1 and degradation of cyclin B. This mechanism of inhibition is different from that in oocytes treated with nocodazole, which have high levels of cdk1 activity and cyclin B.

• Asian Pacific Journal of Cancer Prevention
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• 제15권19호
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• pp.8337-8343
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• 2014

Paclitaxel is one of the best anticancer agents that has been isolated from plants, but its major disadvantage is its dose-limiting toxicity. In this study, we obtained evidence that the active mutant IPP5 ($8-60hIPP5^m$), the latest member of the inhibitory molecules for protein phosphatase 1, sensitizes human cervix carcinoma cells HeLa more efficiently to the therapeutic effects of paclitaxel. The combination of $8-60hIPP5^m$ with paclitaxel augmented anticancer effects as compared to paclitaxel alone as evidenced by reduced DNA synthesis and increased cytotoxicity in HeLa cells. Furthermore, our results revealed that $8-60hIPP5^m$ enhances paclitaxel-induced G2/M arrest and apoptosis, and augments paclitaxel-induced activation of caspases and release of cytochrome C. Evaluation of signaling pathways indicated that this synergism was in part related to downregulation of NF-${\kappa}B$ activation and serine/threonine kinase Akt pathways. We noted that $8-60hIPP5^m$ downregulated the paclitaxel-induced NF-${\kappa}B$ activation, $I{\kappa}B{\alpha}$ degradation, PI3-K activity and phosphorylation of the serine/threonine kinase Akt, a survival signal which in many instances is regulated by NF-${\kappa}B$. Together, our observations indicate that paclitaxel in combination with $8-60hIPP5^m$ may provide a therapeutic advantage for the treatment of human cervical carcinoma.

• The Plant Pathology Journal
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• 제19권5호
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• pp.239-247
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• 2003

In Korea, a local soybean (Glycine max) genotype 56l. was found to be strongly resistant to a virulent bacterial strain of a Pseudomonas sp. SN239. Specific genes involved in the resistance of the soybean genotype 561 were identified and the pattern of gene expression against the Pseudomonas infection was analyzed using differential-display reverse transcription PCR (DDRT-PCR). More than 126 cDNA fragments representing mRNAs were induced within 48 hours of bacteria inoculation. Among them, 28 cDNA fragments were cloned and sequenced. Twelve differentially displayed clones with open reading frames had unknown functions. Sixteen selected cDNA clones were homologous to known genes of other organisms. Some of the identified cDNAs were pathogenesis-related (PR) genes and PR-like genes. These cDNAs included a putative calmodulin-binding protein; an endo-l,3-1,4-$\bate$-D-glucanase; a $\bate$-1,3-endoglucanase; a $\bate$-1,3-exoglucanase; a phytochelatin synthetase-like gene; a thiol protease; a cycloartenol synthase; and a putative receptor-like serine/threonine protein kinase. Among them, four genes were found to be putative PR genes induced significantly by the Pseudomonas infection. These included a calmodulin-binding protein gene, a $\bate$-1,3-endoglucanase gene, a receptor-like serine/threonine protein kinase gene, and pS321 (unknown function). These results suggest that the differentially expressed genes may mediate the strong resistance of soybean 561 to the strain SN239 of Pseudomonas sp.

• 생명과학회지
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• 제20권10호
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• pp.1451-1457
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• 2010

Serotonin (5-hydroxytryptamine (5-HT))는 신경계의 세포-세포 간의 신호전달의 주요한 신경전달물질이다. 세포막에 존재하는 serotonin transporter (SERT)는 연접간격에 존재하는 5-HT를 세포 내로 재흡수 하여 세포외부의 5-HT 농도를 조절하지만 그 기전은 아직 밝혀지지 않았다. 본 연구에서는 yeast two-hybrid system을 사용하여 SERT의 C-말단이 protein kinase C-$\varepsilon$ (PKC-$\varepsilon$)과 특이적으로 결합함을 알았다. PKC-$\varepsilon$는 PKC의 isotype으로 calcium 비의존적이며 phorbol ester/diacylglycerol 민감성 serine/threonine kinase이다. $Na^+/Cl^-$ 의존성 SLC6 gene family의 다른 수송체는 PKC-$\varepsilon$과 결합하지 않았다. Deletion mutant들을 사용하여 SERT는 PKC-$\varepsilon$의 C-말단부위와 결합함을 알았으며, 또한 이 단백질간의 결합을 GST pull-down assay로 확인하였다. PKC-$\varepsilon$는 in vitro에서 SERT의 N-말단의 펩티드를 인산화시켰다. 이러한 결과들은 PKC-$\varepsilon$에 의한 SERT의 인산화가 세포막에 존재하는 SERT의 활성을 조절하는 역할을 할 가능성을 시사한다.

• BMB Reports
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• 제42권1호
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• pp.35-40
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• 2009

Protein kinase D2 (PKD2) is a member of the PKD serine/threonine protein kinase family that has been implicated in the regulation of a variety of cellular processes including proliferation, survival, protein trafficking and immune response. In the present study, we report a novel interaction between PKD2 and Lck, a member of the Src tyrosine protein kinase family that is predominantly expressed in T cells. This interaction involved the C-terminal kinase domains of both PKD2 and Lck. Moreover, co-expression of Lck enhanced the tyrosine phosphorylation of PKD2 and increased its kinase activity. Finally, we report that PKD2 enhanced T cell receptor (TCR)-induced nuclear factor of T cell (NFAT) activity in Jurkat T cells. These results suggested that Lck regulated the activity of PKD2 by tyrosine phosphorylation, which in turn may have modulated the physiological functions of PKD2 during TCR-induced T cell activation.

• BMB Reports
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• 제35권1호
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• pp.106-115
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• 2002

The serine/threonine kinase Akt has been intensely studied for its role in growth factor-mediated cell survival for the past 5 years. On the other hand, the ongoing research effort has recently uncovered novel regulatory mechanisms and downstream effectors of Akt that demonstrate the involvement of Akt in other cellular functions such as cell cycle progression, angiogenesis, and cancer cell invasion/metastasis. Furthermore, recent studies using whole model organisms suggest additional roles for Akt in important diseases such as aging and diabetes. The following review addresses these recent advances in the understanding of Akt function.

• The Plant Pathology Journal
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• 제20권1호
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• pp.7-12
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• 2004

An important recent advance in the field of plant-microbe interactions has been the cloning of genes that confer resistance to specific viruses, bacteria, fungi or insects. Disease resistance (R) genes encode proteins with predicted structural motifs consistent with them having roles in signal recognition and transduction. Plant disease resistance is the result of an innate host defense mechanism, which relies on the ability of plant to recognize pathogen invasion and efficiently mount defense responses. In tomato, resistance to the pathogen Pseudomonas syringae pv. tomato is mediated by the specific recognition between the tomato serine/threonine kinase Pto and bacterial protein AvrPto or AvrPtoB. This recognition event initiates signaling events that lead to defense responses including an oxidative burst, the hypersensitive response (HR), and expression of pathogenesis- related genes.