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31.
32.
《Bioorganic & medicinal chemistry》2016,24(19):4647-4651
Human African trypanosomiasis (HAT) is a lethal, vector-borne disease caused by the parasite Trypanosoma brucei. Therapeutic strategies for this neglected tropical disease suffer from disadvantages such as toxicity, high cost, and emerging resistance. Therefore, new drugs with novel modes of action are needed. We screened cultured T. brucei against a focused kinase inhibitor library to identify promising bioactive compounds. Among the ten hits identified from the phenotypic screen, AZ960 emerged as the most promising compound with potent antiparasitic activity (IC50 = 120 nM) and was shown to be a selective inhibitor of an essential gene product, T. brucei extracellular signal-regulated kinase 8 (TbERK8). We report that AZ960 has a Ki of 1.25 μM for TbERK8 and demonstrate its utility in establishing TbERK8 as a potentially druggable target in T. brucei. 相似文献
33.
Dietmar Kültz 《Journal of molecular evolution》1998,46(5):571-588
All currently sequenced stress-activated protein kinases (SAPKs), extracellular signal-regulated kinases (ERKs), and other
mitogen-activated protein kinases (MAPKs) were analyzed by sequence alignment, phylogenetic tree construction, and three-dimensional
structure modeling in order to classify members of the MAPK family. Based on this analysis the MAPK family was divided into
three subgroups (SAPKs, ERKs, and MAPK3) that consist of at least nine subfamilies. Members of a given subfamily were exclusively
from animals, plants, or yeast/fungi. A single signature sequence, [LIVM][TS]XX[LIVM]XT[RK][WY]YRXPX[LIVM] [LIVM], was identified
that is characteristic for all MAPKs and sufficient to distinguish MAPKs from other members of the protein kinase superfamily.
This signature sequence contains the phosphorylation site and is located on loop 12 of the three-dimensional structure of
MAPKs. I also identified signature sequences that are characteristic for each of the nine subfamilies of MAPKs. By modeling
the three-dimensional structure of three proteins for each MAPK subfamily based on the resolved atomic structures of rat ERK2
and murine p38, it is demonstrated that amino acids conserved in all MAPKs are located primarily in the center of the protein
around the catalytic cleft. I conclude that these residues are important for maintaining proper folding into the gross structure
common to all MAPKs. On the other hand, amino acids conserved in a given subfamily are located mainly in the periphery of
MAPKs, indicating their possible importance for defining interactions with substrates, activators, and inhibitors. Within
these subfamily-specific regions, amino acids were identified that represent unique residues occurring in only a single subfamily
and their location was mapped in three-dimensional structure models. These unique residues are likely to be crucial for subfamily-specific
interactions of MAPKs with substrates, inhibitors, or activators and, therefore, represent excellent targets for site-directed
mutagenesis experiments.
Received: 13 August 1997 / Accepted: 21 November 1997 相似文献
34.
35.
Nakajima M Negishi Y Tanaka H Kawashima K 《Biochemical and biophysical research communications》2004,320(4):1069-1075
The embryonal carcinoma-derived cell line, ATDC5, differentiates into chondrocytes in response to insulin or insulin-like growth factor-I stimulation. In this study, we investigated the roles of mitogen-activated protein (MAP) kinases in insulin-induced chondrogenic differentiation of ATDC5 cells. Insulin-induced accumulation of glycosaminoglycan and expression of chondrogenic differentiation markers, type II collagen, type X collagen, and aggrecan mRNA were inhibited by the MEK1/2 inhibitor (U0126) and the p38 MAP kinase inhibitor (SB203580). Conversely, the JNK inhibitor (SP600125) enhanced the synthesis of glycosaminoglycan and expression of chondrogenic differentiation markers. Insulin-induced phosphorylation of ERK1/2 and JNK but not that of p38 MAP kinase. We have previously clarified that the induction of the cyclin-dependent kinase inhibitor, p21(Cip-1/SDI-1/WAF-1), is essential for chondrogenic differentiation of ATDC5 cells. To assess the relationship between the induction of p21 and MAP kinase activity, we investigated the effect of these inhibitors on insulin-induced p21 expression in ATDC5 cells. Insulin-induced accumulation of p21 mRNA and protein was inhibited by the addition of U0126 and SB203580. In contrast, SP600125 enhanced it. Inhibitory effects of U0126 or stimulatory effects of SP600125 on insulin-induced chondrogenic differentiation were observed when these inhibitors exist in the early phase of differentiation, suggesting that MEK/ERK and JNK act on early phase differentiation. SB202580, however, is necessary not only for early phase but also for late phase differentiation, indicating that p38 MAP kinase stimulates differentiation by acting during the entire period of cultivation. These results for the first time demonstrate that up-regulation of p21 expression by ERK1/2 and p38 MAP kinase is required for chondrogenesis, and that JNK acts as a suppressor of chondrogenesis by down-regulating p21 expression. 相似文献
36.
促分裂原活化蛋白激酶(mitogen-activated protein kinase,MAPK)是生物体内信号转导途径MAPK级联反应的重要组分,通过传递胞内外信号,介导生物及非生物胁迫反应、激素反应、调控细胞分化和发育过程.对水稻(Oryza sativa L.)MAPK家族的结构、作用机制、分类以及在抗逆应答、生长发育中的作用进行了综述,为水稻MAPK的深入研究和应用提供参考. 相似文献
37.
38.
Liu J Chakraborty C Graham CH Barbin YP Dixon SJ Lala PK 《Experimental cell research》2003,286(1):138-151
The serine protease urokinase-type plasminogen activator (uPA) promotes matrix degradation by many cell types, including the invasive extravillous trophoblast (EVT) of the human placenta. The noncatalytic amino-terminal end of uPA binds to uPA receptors (uPARs) expressed by these cells. A highly polarized expression of uPAR-bound uPA at the migration front of EVT cells in situ suggests a functional role of uPA:uPAR interaction in EVT cell migration. The present study examined whether uPA stimulates EVT cell migration, independent of proteolytic function, and investigated some of the signaling pathways involved. Using in vitro-propagated EVT cells in Transwell migration assays, both uPA and its noncatalytic amino-terminal fragment (ATF) were shown to stimulate migration through multiporous polycarbonate (pore size 8 microm) membranes. A uPAR-blocking antibody inhibited basal and ATF-stimulated migration. Migration was found to be stimulated by hypoxic conditions, which upregulates uPAR expression; this stimulation was abrogated with the uPAR-blocking antibody, indicating the role of endogenous uPA in EVT cell migration. Spectrofluorometric measurement of cytosolic calcium in cells treated with uPA and ATF demonstrated a rapid rise in [Ca2+](i), which was prevented by pretreatment of cells with thapsigargin, indicating a release from intracellular stores. Both basal and ATF-mediated migratory responses were suppressed in the presence of selective pharmacological inhibitors LY294002, U73122, and U0126, implicating the respective roles of phosphatidinylinositol 3-kinase (PI 3-K), phospholipase C (PLC), and MEK1/2 in basal and ATF-stimulated migratory capacity. Taken together, these results demonstrate that uPA:uPAR interaction stimulates EVT cell migration, independent of uPA enzymatic activity, using the mitogen-activated protein kinase pathway and calcium signaling events including the participation of PI 3-K and PLC. These findings are relevant to clinical conditions of aberrant trophoblast migration, including spontaneous abortion, preeclampsia, and choriocarcinoma. 相似文献
39.
Excessive generation of reactive oxygen species (ROS) in the central nervous system (CNS) is a leading cause of neuronal injury. Despite yet unknown mechanisms, oxidant compounds such as H2O2 have been shown to stimulate the release of arachidonic acid (AA) in a number of cell systems. In this study, H2O2 and menadione, a compound known to release H2O2 intracellularly, were used to examine the phospholipases A2 (PLA2) responsible for AA release from primary murine astrocytes. Both H2O2 and menadione dose-dependently stimulated AA release, and the release mediated by H2O2 was completely inhibited by catalase. H2O2 also stimulated phosphorylation of extracellular signal-regulated kinases (ERK1/2) and cytosolic phospholipase A2 (cPLA2). However, complete inhibition of cPLA2 phosphorylation by U0126, an inhibitor for mitogen-activated protein kinase kinase (MEK) and GF109203x, a nonselective PKC inhibitor preferring the conventional and novel isoforms, only reduced H2O2-stimulated AA release by 50%. MAFP, a selective, active, site-directed, irreversible inhibitor of both cPLA2 and the Ca2+-independent iPLA2, nearly completely inhibited H2O2-mediated AA release; but, HELSS, a potent irreversible inhibitor of iPLA2, only inhibited H2O2-mediated AA release by 40%. Along with the observation that H2O2-mediated AA release was only partially inhibited upon chelating intracellular Ca2+ by BAPTA, these results indicate the involvement of both cPLA2 and iPLA2 in H2O2-mediated AA release in murine astrocytes. 相似文献
40.
Regulator of G protein signaling (RGS) proteins are GTPase-activating proteins for heterotrimeric G proteins. One of the best-studied RGS proteins, RGS4, accelerates the rate of GTP hydrolysis by all G(i) and G(q) alpha subunits yet has been shown to exhibit receptor selectivity. Although RGS4 is expressed primarily in brain, its effect on modulating the activity of serotonergic receptors has not yet been reported. In the present study, transfected BE(2)-C human neuroblastoma cells expressing human 5-HT(1B) receptors were used to demonstrate that RGS4 can inhibit the coupling of 5-HT(1B) receptors to cellular signals. Serotonin and sumatriptan were found to stimulate activation of extracellular signal-regulated kinase. This activation was attenuated, but not completely inhibited, by RGS4. Similar inhibition by RGS4 of the protein kinase Akt was also observed. As RGS4 is expressed at high levels in brain, these results suggest that it may play a role in regulating serotonergic pathways. 相似文献