Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.24 (mitogen-activated protein kinase)
 95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The functional involvement of bone morphogenetic protein (BMP) system in primary pulmonary hypertension (PPH) remains unclear. Here we demonstrate a crucial role of the BMP type IB receptor, activin receptor-like kinase (ALK)-6 for pulmonary arterial smooth muscle cell (pphPASMC) mitosis isolated from a sporadic PPH patient bearing no mutations in BMPR2 gene. A striking increase in the levels of ALK-6 mRNA was revealed in pphPASMC compared with control PASMCs, in which ALK-6 transcripts were hardly detectable. BMP-2 and -7 stimulated the mitosis of pphPASMCs, which was opposite to their suppressive effects on the mitosis of the control PASMCs. BMP-4 and -6 and activin inhibited pphPASMC mitosis, whereas these did not affect control PASMCs. The presence of BMP signaling machinery in pphPASMCs was elucidated based on the analysis on Id-1 transcription and Smad-reporter genes. Overexpression of a dominant-negative ALK-6 construct revealed that ALK-6 plays a key role in the mitosis as well as intracellular BMP signaling of pphPASMCs. Gene silencing of ALK-6 using small interfering RNA also reduced DNA synthesis as well as Id-1 transcription in pphPASMCs regardless of BMP-2 stimulation. Although Id-1 response was not stimulated by BMP-2 in control PASMCs, the gene delivery of wild-type ALK-6 caused significant increase in the Id-1 transcripts in response to BMP-2. Additionally, inhibitors of ERK and p38 MAPK pathways suppressed pphPASMC mitosis induced by BMP-2, implying that the mitotic action is in part MAPK dependent. Thus, the BMP system is strongly involved in pphPASMC mitosis through ALK-6, which possibly leads to activation of Smad and MAPK, resulting in the progression of vascular remodeling of pulmonary arteries in PPH.
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PMID:Characterization of the bone morphogenetic protein (BMP) system in human pulmonary arterial smooth muscle cells isolated from a sporadic case of primary pulmonary hypertension: roles of BMP type IB receptor (activin receptor-like kinase-6) in the mitotic action. 1519 43

Early spherical Xenopus laevis embryos are transformed into a streamlined shape through convergent extension movements. Here we report that a p75(NTR)-related transmembrane protein, NRH1, has an essential function in the regulation of these movements. NRH1 was expressed in marginal zone tissues of the gastrula and in the posterior ectoderm of the neurula. Attenuation of the NRH1 function inhibited convergent extension movements in the embryo and in activin-treated animal caps. NRH1 activated downstream effectors of the Wnt/planar cell polarity pathway: small GTPases and the cascade of MKK7-JNK. Furthermore, gain- and loss-of-function phenotypes of NRH1 were rescued by co-injection of dominant-negative and constitutively active forms of these downstream effectors, respectively, suggesting that NRH1 functions as a positive modulator of planar cell polarity signalling. Interestingly, NRH1 does not require Dishevelled (Xdsh) for the activation of these downstream effectors or translocation of Xdsh to the membrane, suggesting that NRH1 signalling interacts with planar cell polarity signalling downstream of Xdsh. This demonstrates an essential role for p75(NTR)-related signalling in early embryonic morphogenesis.
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PMID:The neurotrophin-receptor-related protein NRH1 is essential for convergent extension movements. 1530 94

Undifferentiated granulosa cells from prehierarchal (6- to 8-mm-diameter) hen follicles express very low to undetectable levels of LH receptor (LH-R) mRNA, P450 cholesterol side chain cleavage (P450scc) enzyme activity, and steroidogenic acute regulatory (StAR) protein, and produce negligible progesterone, in vitro, following an acute (3-h) challenge with either FSH or LH. It has previously been established that culturing such cells with FSH for 18-20 h induces LH-R, P450scc, and StAR expression, which enables the initiation of progesterone production. The present studies were conducted to characterize the ability of activin and transforming growth factor (TGF) beta, both alone and in combination with FSH, to promote hen granulosa cell differentiation, in vitro. A 20-h culture of prehierarchal follicle granulosa cells with activin A or transforming growth factor beta (TGFbeta)1 increased LH-R mRNA levels compared with control cultured cells. Activin A and TGFbeta1 also promoted FSH-receptor (FSH-R) mRNA expression when combined with FSH treatment. Neither activin A nor TGFbeta1 alone stimulated progesterone production after 20 h culture. However, preculture with either factor for 20 h (to induce gonadotropin receptor mRNA expression) followed by a 3-h challenge with FSH or LH potentiated StAR expression and progesterone production compared with cells challenged with gonadotropin in the absence of activin A or TGFbeta1 preculture. Significantly, activation of the mitogen-activated protein (MAP) kinase pathway with transforming growth factor alpha (TGFalpha) (monitored by Erk phosphorylation) blocked TGFbeta1-induced LH-R expression, and this effect was associated with the inhibition of Smad2 phosphorylation. We conclude that a primary differentiation-inducing action of activin A and TGFbeta1 on hen granulosa cells from prehierarchal follicles is directed toward LH-R expression. Enhanced LH-R levels subsequently sensitize granulosa cells to LH, which in turn promotes StAR plus P450scc expression and subsequently an increase in P4 production. Significantly, the finding that TGFbeta signaling is negatively regulated by MAP kinase signaling is proposed to represent a mechanism that prevents premature differentiation of granulosa cells.
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PMID:Cellular mechanisms and modulation of activin A- and transforming growth factor beta-mediated differentiation in cultured hen granulosa cells. 1526 4

Tissue morphogenesis during development is regulated by growth factors and cytokines, and is characterized by constant remodeling of extracellular matrix in response to signaling molecules. MEK kinase 1 (MEKK1) is a mitogen-activated protein kinase (MAPK) kinase kinase originally identified as an upstream activator for several MAPK pathways. During mouse embryogenesis, MEKK1 controls cell shape changes and formation of actin stress fibers that are required for sealing epidermis in the embryos in a process known as eyelid closure. MEKK1-null mice display eye-open at birth (EOB), a phenotype found also in mice impaired in activin, a subgroup of the transforming growth factor beta (TGFbeta) family, or in epidermal growth factor receptor (EGFR) or its ligand TGFalpha, or in transcription factor c-Jun. Molecular analyses have revealed at least two signaling mechanisms in the control of eyelid closure. One is originated from the activins and is transduced through MEKK1, leading to transcription-independent actin stress fiber formation and transcription-dependent keratinocyte migration. Another is the TGFalpha/EGFR signal that is transduced through a MEKK1-independent pathway to the activation of the ERK MAPK, which also leads to keratinocyte migration. c-Jun might serve as a connection between the two pathways. As embryonic eyelid closure is a specific morphogenetic process that is easily detectable, genetic mutant mice with EOB will be ideal models to understand the signaling mechanisms in the control of epithelial cell migration and the morphogenetic process of epithelial sheet movement.
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PMID:The signaling pathways in tissue morphogenesis: a lesson from mice with eye-open at birth phenotype. 1531 93

Both activin and GnRH can independently stimulate expression of the FSHbeta subunit gene. In this study, we used the gonadotrope-derived LbetaT2 cell line to investigate the potential interaction between activin and GnRH in regulating the transcriptional activity of the rat FSHbeta gene promoter. Activin A and GnRH synergistically enhanced rat FSHbeta transcriptional activity. Overexpression of SMAD3 (mediator of decapentaplegic-related protein 3), but not of SMAD2, increased transcriptional activation of the rat (r) FSHbeta gene promoter, which was further enhanced by the combined overexpression of SMAD3 and 4 (3+4). The stimulatory effects of SMAD3 overexpression were localized to -472/-256 of the rFSHbeta gene promoter, and activin- and GnRH-responsive proteins were shown to bind to region -284/-252. Sequence analysis identified a consensus palindromic SMAD-binding site at -266/-259 of the rFSHbeta gene promoter. Mutation of two bases located in the center of this palindrome effectively abrogated SMAD4 binding, markedly reduced SMAD3 and 3+4 stimulation of the rFSHbeta gene promoter, and significantly decreased the synergistic enhancement of promoter activity by both activin A and GnRH, and SMAD3 and GnRH. Blockade of the MAPK-signaling pathway did not significantly affect the response to combined stimulation with activin and GnRH. In contrast, interference with SMAD3 signaling caused a significant reduction in activin and GnRH synergy. The results indicate that SMAD3 plays an important role in the synergistic effects of activin and GnRH and demonstrate that this synergy is mediated by a palindromic cis-element located at -266/-259 of the rFSHbeta gene promoter.
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PMID:Synergy between activin A and gonadotropin-releasing hormone in transcriptional activation of the rat follicle-stimulating hormone-beta gene. 1537 86

Activins and other members of the transforming growth factor beta family play a critical role in morphological changes of the epidermis that require epithelial cell movement. We investigated the molecular pathways in the transmission of activin signals that lead to actin reorganization and epithelial cell migration. We found that activins cause the activation of RhoA but not of Rac and CDC42, leading to MEKK1-dependent phosphorylation of JNK and transcription factor c-Jun. Through a RhoA-independent mechanism, the activins also induce p38 activity in keratinocytes from wild-type but not from MEKK1-deficient mice. Although neither pathway is dependent on Smad activation, the MEKK1-mediated JNK and p38 activities are both essential for activin-stimulated and transcription-dependent keratinocyte migration. Only JNK is involved in transcription-independent actin stress fiber formation, which needs also the activity of ROCK. Because ROCK is required for JNK activation by RhoA and its overexpression leads to MEKK1 activation, we propose a RhoA-ROCK-MEKK1-JNK pathway and a MEKK1-p38 pathway as Smad-independent mechanisms in the transmission of activin signals. Together, these pathways lead to the control of actin cytoskeleton reorganization and epithelial cell migration, contributing to the physiologic and pathological effects of activins on epithelial morphogenesis.
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PMID:MEKK1 transduces activin signals in keratinocytes to induce actin stress fiber formation and migration. 1560 30

Activin has previously been shown to act as a nerve cell survival factor and to have neurotrophic effects on neurons. However, the role of activin in regulating neurotransmitter expression in the central nervous system and the exact mechanisms involved in this process are poorly understood. In the present study, we report that activin A and basic fibroblast growth factor (bFGF) synergistically increased the protein level of tyrosine hydroxylase (TH), and also greatly increased the TH mRNA level, in both mouse E14 striatal primary cell cultures and the hippocampal neuronal cell line HT22. Activin A and bFGF cooperatively stimulated nuclear translocation of Smad3 and specifically activated ERK1/2, but not p38 or JNK. Interestingly, a specific inhibitor for MEK, U0126, efficiently blocked the induction of TH promoter activity by activin A and bFGF, indicating that activin A collaborated with bFGF signaling to induce the TH gene through selective activation of ERK-type MAP kinase in mouse striatal and HT22 cells. These data suggest that activin A may act in concert with bFGF for the development of TH-positive neurons.
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PMID:Synergistic activity of activin A and basic fibroblast growth factor on tyrosine hydroxylase expression through Smad3 and ERK1/ERK2 MAPK signaling pathways. 1574 8

Transforming growth factor-beta1 (TGF-beta) regulates cellular functions like proliferation, differentiation, and apoptosis. On the cell surface, TGF-beta binds to receptor complexes consisting of TGF-beta receptor type II (TbetaRII) and activin-like kinase receptor-5 (Alk5), and the downstream signaling is transduced by Smad and MAPK proteins. Recent data have shown that alternative receptor combinations aside from the classical pairing of TbetaRII/Alk5 can be relevant for TGF-beta signaling. We have screened for alternative receptors for TGF-beta and also for gene targets of TGF-beta signaling, by performing functional assays and microarray analysis in murine embryonic fibroblast (MEF) cell lines lacking Alk5. Data from TGF-beta-stimulated Alk5(-/-) cells show them to be completely unaffected by TGF-beta. Additionally, 465 downstream targets of Alk5 signaling were identified when comparing Alk5(-/-) or TGF-beta-stimulated Alk5(+/+) MEFs with unstimulated Alk5(+/+) cells. Our results demonstrate that, in MEFs, TGF-beta signals exclusively through complexes involving Alk5, and give insight to its downstream effector genes.
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PMID:Gene expression profiling demonstrates that TGF-beta1 signals exclusively through receptor complexes involving Alk5 and identifies targets of TGF-beta signaling. 1576 4

Bone morphogenetic protein (BMP) ligands signal by binding the BMP type II receptor (BMPR2) or the activin type II receptors (ActRIIa and ActRIIb) in conjunction with type I receptors to activate SMADs 1, 5, and 8, as well as members of the mitogen-activated protein kinase family. Loss-of-function mutations in Bmpr2 have been implicated in tumorigenesis and in the etiology of primary pulmonary hypertension. Because several different type II receptors are known to recognize BMP ligands, the specific contribution of BMPR2 to BMP signaling is not defined. Here we report that the ablation of Bmpr2 in pulmonary artery smooth muscle cells, using an ex vivo conditional knock-out (Cre-lox) approach, as well as small interfering RNA specific for Bmpr2, does not abolish BMP signaling. Disruption of Bmpr2 leads to diminished signaling by BMP2 and BMP4 and augmented signaling by BMP6 and BMP7. Using small interfering RNAs to inhibit the expression of other BMP receptors, we found that wild-type cells transduce BMP signals via BMPR2, whereas BMPR2-deficient cells transduce BMP signals via ActRIIa in conjunction with a set of type I receptors distinct from those utilized by BMPR2. These findings suggest that disruption of Bmpr2 leads to the net gain of signaling by some, but not all, BMP ligands via the activation of ActRIIa.
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PMID:Bone morphogenetic protein (BMP) type II receptor deletion reveals BMP ligand-specific gain of signaling in pulmonary artery smooth muscle cells. 1588 58

Wnt signaling pathways are essential in various developmental processes including differentiation, proliferation, cell migration, and cell polarity. Wnt proteins execute their multiple functions by activating distinct intracellular signaling cascades, although the mechanisms underlying this activation are not fully understood. We identified a novel Daple-like protein in Xenopus and named it xDal (Xenopus Daple-like). As with Daple, xDal contains several leucine zipper-like regions (LZLs) and a putative PDZ domain-binding motif, and can interact directly with the dishevelled protein. In contrast to mDaple, injection of xDal mRNA into the dorso-vegetal blastomere does not induce ventralization and acted synergistically with xdsh in secondary axis induction. XDal also induced expression of siamois and xnr-3, suggesting that XDal functions as a positive regulator of the Wnt/beta-catenin pathway. Injection of xDal mRNA into the dorso-animal blastomere, however, induced gastrulation-defective phenotypes in a dose-dependent manner. In addition, xDal inhibited activin-induced elongation of animal caps and enhanced c-jun phosphorylation. Based on these findings, xDal is also thought to function in the Wnt/JNK pathway. Moreover, functional domain analysis with several deletion mutants indicated that xDal requires both a putative PDZ domain-binding motif and at least one LZL for its activity. These findings with xDal will provide new information on the Wnt signaling pathways.
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PMID:Novel Daple-like protein positively regulates both the Wnt/beta-catenin pathway and the Wnt/JNK pathway in Xenopus. 1602 68


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