Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.11.24 (mitogen-activated protein kinase)
95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Assaying activation of signal transduction is laborious and does not allow the study of large numbers of samples, essential for high-throughput drug screens or for large groups of patients. Using phosphospecific antibodies, we have developed ELISA techniques enabling non-radioactive semi-quantitative assessment of the activation state of p42/p44 mitogen-activated protein kinase (MAPK), p38 MAPK, protein kinase B and the transcription factor cAMP-response-element-binding protein (CREB) in 96-well plates. This assay has been termed PACE (phosphospecific antibody cell-based ELISA) and was used successfully for both adherent and suspension cells. Various stimuli induced dose-dependent enzymic activity of which the kinetics closely correlated with those measured via classical methodology. Using PACE we have now characterized for the first time the concentration-dependent effects of various inflammatory prostaglandins on CREB phosphorylation in macrophages. PACE is a straightforward and novel technique enabling the large-scale analysis of signal transduction.
...
PMID:A new phosphospecific cell-based ELISA for p42/p44 mitogen-activated protein kinase (MAPK), p38 MAPK, protein kinase B and cAMP-response-element-binding protein. 1097 Jul 84

Lefty polypeptides, novel members of the transforming growth factor-beta (TGF-beta) superfamily, are involved in the formation of embryonic lateral patterning. Members of the TGF-beta superfamily require processing for their activation, suggesting cleavage to be an essential step for lefty activation. Transfection of different cell lines with lefty resulted in expression of a 42-kDa protein, which was proteolytically processed to release two polypeptides of 34 and 28 kDa. Since members of the proprotein convertase (PC) family cleave different TGF-beta factors and are involved in the establishment of embryonic laterality, we studied their role in lefty processing. Cotransfection analysis showed that PC5A processed the lefty precursor to the 34-kDa form in vivo, whereas furin, PACE4, PC5B, and PC7 had a limited activity. None of these PCs showed activity in the processing of the lefty polypeptide to the 28-kDa lefty form. The mutation of the consensus sequences for PC cleavage in the lefty protein allowed the lefty cleavage sites to be identified. Mutations of the sequence RGKR to GGKG (amino acids 74-77) and of RHGR to GHGR (amino acids 132-135) prevented the proteolytic processing of the lefty precursor to the 34- and 28-kDa forms, respectively. To identify the biologically active form of lefty, we studied the effect of lefty treatment on pluripotent P19 cells. Lefty did not induce Smad2 or Smad5 phosphorylation, Smad2/Smad4 heterodimerization, or nuclear translocation of Smad2 or Smad4, but activated the MAPK pathway in a time- and dose-dependent fashion. Further analysis showed the 28-kDa (but not the 34-kDa) polypeptide to induce MAPK activity. Surprisingly, the 42-kDa lefty protein was also capable of inducing MAPK activity, indicating that the lefty precursor is biologically active. The data support a molecular model of processing as a mechanism for regulation of lefty signaling.
...
PMID:Lefty proteins exhibit unique processing and activate the MAPK pathway. 1127 22

Furin, a predominant convertase of the cellular constitutive secretory pathway, is known to be involved in the maturation of a number of growth/differentiation factors, but the mechanisms governing its expression remain elusive. We have previously demonstrated that transforming growth factor (TGF) beta 1, through the activation of Smad transducers, regulates its own converting enzyme, furin, creating a unique activation/regulation loop of potential importance in a variety of cell fate and functions. Here we studied the involvement of the p42/p44 MAPK pathway in such regulation. Using HepG2 cells transfected with fur P1 LUC (luciferase) promoter construct, we observed that forced expression of a dominant negative mutant form of the small G protein p21(ras) (RasN17) inhibited TGF beta 1-induced fur gene transcription, suggesting the involvement of the p42/p44 MAPK cascade. In addition, TGF beta induced sustained activation/phosphorylation of endogenous p42/p44 MAPK. Further-more, the role of MAPK cascade in fur gene transcription was highlighted by the use of the MEK1/2 inhibitors, PD98059 or U0126, or co-expression of a p44 antisense construct that repressed the induction of fur promoter transactivation. Conversely, overexpression of a constitutively active form of MEK1 increased unstimulated, TGF beta 1-stimulated, and Smad2-stimulated promoter P1 transactivation, and the universal Smad inhibitor, Smad7, inhibited this effect. Activation of Smad2 by MEK1 or TGF beta 1 resulted in an enhanced nuclear localization of Smad2, which was inhibited upon blocking MEK1 activity. Our findings clearly show that the activation of the p42/p44 MAPK pathway is involved in fur gene expression and led us to propose a co-operative model whereby TGF beta 1-induced receptor activation stimulates not only a Smad pathway but also a parallel p42/p44 MAPK pathway that targets Smad2 for an increased nuclear translocation and enhanced fur gene transactivation. Such an uncovered mechanism may be a key determinant for the regulation of furin in embryogenesis and growth-related physiopathological conditions.
...
PMID:Cross-talk between the p42/p44 MAP kinase and Smad pathways in transforming growth factor beta 1-induced furin gene transactivation. 1144 47

Anthrax is primarily a disease of herbivores caused by gram-positive, aerobic, spore-forming Bacillus anthracis. Humans are accidental hosts through the food of animal origin and animal products. Anthrax is prevelant in most parts of the globe, and cases of anthrax have been reported from almost every country. Three forms of the disease have been recognized: cutaneous (through skin), gastrointestinal (through alimentary tract), and pulmonary (by inhalation of spores). The major virulence factors of Bacillus anthracis are a poly-D glutamic acid capsule and a three-component protein exotoxin. The genes coding for the toxin and the enzymes responsible for capsule production are carried on plasmid pXO1 and pXO2, respectively. The three proteins of the exotoxin are protective antigen (PA, 83 kDa), lethal factor (LF, 90 kDa), and edema factor (EF, 89 kDa). The toxins follow the A-B model with PA being the B moeity and LF/EF, the alternative A moeities. LF and EF are individually nontoxic, but in combination with PA form two toxins causing different pathogenic responses in animals and cultured cells. PA + LF forms the lethal toxin and PA + EF forms the edema toxin. During the process of intoxication, PA binds to the cell surface receptor and is cleaved at the sequence RKKR (167) by cell surface proteases such as furin generating a cell-bound, C-terminal 63 kDa protein (PA63). PA63 possesses a binding site to which LF or EF bind with high affinity. The complex is then internalized by receptor-mediated endocytosis. Acidification of the vesicle leads to instertion of PA63 into the endosomal membrane and translocation of LF/EF across the bilayer into the cytosol where they exert their toxic effects. EF has a calcium- and calmodulin-dependent adenylate cyclase activity. Recent reports indicate that LF is a protease that cleaves the amino terminus of mitogen-activated protein kinase kinases 1 and 2 (MAPKK1 and 2), and this cleavage inactivates MAPKK1 and thus inhibits the mitogen-activated protein kinase signal transduction pathway. We describe in detail the studies so far done on unraveling the molecular mechanisms of pathogenesis of Bacillus anthracis.
...
PMID:Anthrax toxin. 1159 78

We have recently demonstrated that furin, PC5, and PC7, members of the subtilisin/kexin-like mammalian proprotein convertases (PCs), are found in rodent aorta. These PCs have been identified to activate several growth factors, adhesion molecules and extracellular matrix compounds by endoproteolytic cleavage. In the present study, we investigated the regulation of PC5 in vascular smooth muscle cells (VSMCs) in vitro and in vivo. Stimulation of rat aortic VSMCs with platelet-derived growth factor (PDGF)-BB (20 ng/mL), angiotensin II (Ang II, 1 micromol/L), or 10% fetal calf serum (FCS) for 48 hours increased DNA synthesis, as assessed by proliferating cell nuclear antigen (PCNA) immunoblotting. PC5 was strongly upregulated by PDGF-BB and 10% FCS (both 8-fold, P<0.05), whereas Ang II had no effect on PC5 protein levels compared with controls. The PCs furin and PC7, which display a comparable subcellular localization and cleavage activity, were found in VSMCs, but their levels did not increase following PDGF-BB, Ang II, or FCS stimulation. Time-course analysis revealed a rapid increase in PC5 levels after 30 minutes of PDGF-stimulation of VSMCs. PDGF-stimulated PC5 induction was inhibited by the PI3-kinase inhibitor wortmannin, and by rapamycin, an inhibitor of mTOR/p70(s6)-kinase (both P<0.05). In contrast, the mitogen-activated protein kinase (MAPK)-pathway inhibitor PD98059 did not inhibit PDGF-stimulated PC5 induction. Immunocytochemistry and in situ hybridization revealed low PC5 protein and mRNA levels in intact rat aorta in vivo. After balloon injury, PC5 protein and mRNA levels were strongly increased in proliferating PCNA-positive VSMCs. The present data demonstrate that PC5 is upregulated during proliferation of VSMCs in vivo and in vitro. We show that PDGF-induced PC5 expression is PI3-kinase/p70(s6)-kinase dependent. Thus, growth factors regulate the proprotein convertase PC5, which may play an important role during VSMC growth.
...
PMID:Proprotein convertase PC5 regulation by PDGF-BB involves PI3-kinase/p70(s6)-kinase activation in vascular smooth muscle cells. 1188 80

The constitutive shedding of BP180 (collagen XVII) from human keratinocytes in culture was totally prevented by batimastat (5 microM), a wide spectrum matrix metalloprotease (MMP) inhibitor. However, keratinocytes did not express active MMP and generation of active Gelatinase A (MMP-2) and Gelatinase B (MMP-9) at the cell plasma membrane by increasing the ceramide content of keratinocytes did not influence BP180 processing to a 120 kDa species. A disintegrin and metalloprotease (ADAM) is probably involved in such a shedding event since release of 120 kDa polypeptide was inhibited by Decanoyl-Arg-Val-Lys-Arg CH2Cl (30 microM), a specific furin convertase inhibitor; culturing cells on to several matrix substrata i.e. type I collagen, type IV collagen, laminin-1 or laminin-5 had no effect on BP180 processing. Overall our data indicated that the metalloprotease-mediated shedding of BP180 from keratinocytes in culture is insensitive either to agents which activate MAP kinase pathway (ceramide) or to cell-matrix interactions.
...
PMID:The metalloprotease-directed shedding of BP 180 (collagen XVII) from human keratinocytes in culture is unaffected by ceramide and cell-matrix interaction. 1197 64

We reported previously that bone marrow granulocytes respond to small amounts of enterobacterial lipopolysaccharide (LPS) via a CD14-independent and TLR4-mediated mechanism by de novo expression of an inducible receptor (CD14) and by down-modulation of a constitutive receptor (L-selectin). In this report we address another effect of LPS: the down-regulation of receptors for tumor necrosis factor-alpha. In mouse bone marrow cells (BMC), this down-regulation is detectable soon (20 min) after exposure of the cells to low levels (0.5 ng/ml) of LPS. This temperature-dependent effect is rather selective for LPS and requires the presence of a conventional lipid A structure in the LPS molecule and a functional TLR4 molecule in the cells. The down-modulation, due to a shedding of the receptors, is blocked by p38 MAPK inhibitors, by a furin inhibitor, and by three metalloproteinase inhibitors (BB-3103, TIMP-2, and TIMP-3). In contrast, inhibitors of MEK, protein kinase C, cAMP-dependent protein kinase, and kinases of the Src family do not block the shedding. Analysis of BMC from mice lacking tumor necrosis factor receptor-1 (CD120a-/-) or tumor necrosis factor receptor-2 (CD120b-/-) indicates that the LPS-induced shedding is specific for CD120b. Thus, exposure of BMC to LPS triggers a rapid shedding of CD120b via a protein kinase C- and Src-independent pathway mediated by p38 MAPK, furin, and metalloproteinase. The additive effects of furin and metalloproteinase inhibitors suggest that these enzymes are involved in parallel shedding pathways.
...
PMID:TLR4-dependent lipopolysaccharide-induced shedding of tumor necrosis factor receptors in mouse bone marrow granulocytes. 1266 67

Anthrax toxin, the major virulence factor of Bacillus anthracis, consists of three polypeptides: protective antigen (PrAg), lethal factor (LF) and oedema factor (EF). To intoxicate mammalian cells, PrAg binds to its cellular receptors and is subsequently activated via proteolysis, yielding a carboxyl-terminal fragment which coordinately assembles to form heptamers that bind and translocate LF and EF into the cytosol to exert their cytotoxic effects. Substantial progress has been made in recent years towards the characterisation of the structure and function of anthrax toxin, and this has greatly facilitated rational drug design of antianthrax agents. There is also emerging evidence that toxins can be manipulated for cancer therapy. LF can efficiently inactivate several mitogen-activated protein kinase kinases (MAPKKs) via cleavage of their amino-terminal sequences. Consequently, antitumour effects of wild type lethal toxin were observed after treatment of mitogen-activated protein kinase (MAPK)-dependent tumours such as human melanomas. Modification of the toxin's proteolytic activation site limits its cytotoxicity to certain cell types and creates a versatile method of treatment. One approach that has successfully achieved specific tumour targeting is the alteration of the furin cleavage of PrAg so that it is not activated by furin, but, alternatively, by proteases that are highly expressed by tumour tissues, including matrix metalloproteases and urokinase.
...
PMID:Anthrax toxin: structures, functions and tumour targeting. 1288 Mar 83

Anthrax toxin consists of three nontoxic proteins that associate in binary or ternary combinations to form toxic complexes at the surface of mammalian cells. One of these proteins, protective antigen (PA), transports the other two, edema factor (EF) and lethal factor (LF), to the cytosol. LF is a Zn2+-protease that cleaves certain MAP kinase kinases, leading to death of the host via a poorly defined sequence of events. EF, a calmodulin- and Ca2+-dependent adenylate cyclase, is responsible for the edema seen in the disease. Both enzymes are believed to benefit the bacteria by inhibiting cells of the host's innate immune system. Assembly of toxic complexes begins after PA binds to cellular receptors and is cleaved into two fragments by furin proteases. The smaller fragment dissociates, allowing the receptor-bound fragment, PA63 (63 kDa), to self-associate and form a ring-shaped, heptameric pore precursor (prepore). The prepore binds up to three molecules of EF and/or LF, and the resulting complexes are endocytosed and trafficked to an acidic compartment. There, the prepore converts to a transmembrane pore, mediating translocation of EF and LF to the cytosol. Recent studies have revealed (a) the identity of receptors; (b) crystallographic structures of the three toxin proteins and the heptameric PA63 prepore; and (c) information about toxin assembly, entry, and action within the cytosol. Knowledge of the structure and mode of action of the toxin has unveiled potential applications in medicine, including approaches to treating anthrax infections.
...
PMID:Anthrax toxin. 1457 May 63

The IGF-1 receptor (IGF-1R) and MT1-MMP are synthesized as larger precursor proproteins, which require endoproteolytic activation by the proprotein convertases (PCs) furin/PC5 to gain full biological activity. The aim of this study was to investigate the contribution of PCs to IGF-1R and/or MT1-MMP activation in vascular smooth muscle cells (VSMCs) as well as VSMC proliferation/migration, which are key elements in vascular remodeling. Furin and PC5 mRNAs and proteins were found in VSMCs. Inhibition of furin-like PCs with the specific pharmacological inhibitor dec-CMK inhibited IGF-1R endoproteolytic activation. Inhibition of IGF-1R maturation abrogated IGF-induced IGF-1R autophosphorylation, PI3-kinase and MAPK induction, as well as VSMC proliferation (p<0.05 vs. controls), whereas it had no effect of PDGF-stimulated signaling pathways or cell growth. Both, IGF-1 and PDGF-BB, induced MT1-MMP expression, but only IGF-1-mediated MT1-MMP induction was inhibited by dec-CMK. Induction of MMP-2 by IGF-1 was inhibited by the PI3-kinase inhibitor wortmannin, but not by the MEK-inhibitor PD98059. Dec-CMK inhibited VSMC chemotaxis comparable to the effects of the MMP-inhibitor GM6001 (both p<0.05 vs. controls), supporting that MMPs are involved. In conclusion, this study demonstrates that targeting furin-like PCs and thus inhibiting IGF-1R activation is a novel target to inhibit IGF-1-mediated signaling and cell functions, such as IGF-1-induced MT1-MMP/MMP-2 in VSMCs.
...
PMID:Proprotein convertases regulate insulin-like growth factor 1-induced membrane-type 1 matrix metalloproteinase in VSMCs via endoproteolytic activation of the insulin-like growth factor-1 receptor. 1535 40


1 2 3 4 5 Next >>

---