Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.11.18 (MAP)
 7,412 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Phosphorylation of caldesmon was assayed in canine colonic circular smooth muscle strips labelled with 32P and stimulated with 10 microM acetylcholine. Caldesmon was isolated by two-dimensional non-equilibrium pH gel electrophoresis. Stimulation with acetylcholine increased caldesmon phosphorylation significantly from a basal level of 0.6 +/- 0.07 to 1.1 +/- 0.15 mol P1 (mol caldesmon)-1 after 2 min. 2. MAP kinase activities were measured in SDS extracts of muscle by a gel reconstitution method using myelin basic protein. Myelin basic protein kinase activities were observed at 38, 44, 50 and 57 kDa by the gel reconstitution method. Endogenous caldesmon kinase activities were also identified by the gel reconstitution method at 38, 44 and 50 kDa. The 38 and 44 kDa kinases comigrated with proteins labelled by anti-ERK1 MAP kinase antibodies on Western blots. Both 38 and 44 kDa MBP kinase activities increased significantly during contractions induced by 10 microM acetylcholine, 0.1 microM neurokinin A and 70 mM potassium. 3. Phorbol dibutyrate (0.1 microM) potentiated activation of MAP kinases and contraction of depolarized muscles while producing a decrease in fura-2 fluorescence ratio. This suggests that protein kinase C activation is coupled to MAP kinase activity in colonic smooth muscle. 4. MAP kinases isolated form muscle homogenates by Mono Q chromatography were assayed using the specific MAP kinase substrate peptide APRTPGGRR. Stimulation of muscles for 2 min with 10 microM acetylcholine activated both ERK1 and ERK2 MAP kinase activities 2-fold. 5. To determine the effects of caldesmon phosphorylation by MAP kinase on the cross-bridge cycle, actin sliding velocity was measured with an in vitro motility assay. Unphosphorylated turkey gizzard caldesmon (3 microM) significantly reduced mean sliding velocity. Phosphorylation of caldesmon with sea star ERK1 MAP kinase reversed the inhibitory effect of caldesmon on sliding velocity. The results are consistent with a protein kinase cascade being activated by contractile agonists in gastrointestinal smooth muscle which activates ERK MAP kinases leading to phosphorylation of caldesmon. Phosphorylation of caldesmon in vivo may reverse inhibitory influences of caldesmon on cross-bridge cycling.
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PMID:Activation of MAP kinases and phosphorylation of caldesmon in canine colonic smooth muscle. 888 69

We have explored intracellular pathways involved in the urokinase type plasminogen activator (urokinase or uPA)-stimulated migration of human airway smooth muscle cells (hAWSMC). Using a set of uPA mutants we found that protease activity, growth factor-like and kringle domains of uPA differentially contribute to activation of p42/p44erk1,2 and p38 MAP-kinases. Consistent with our earlier data [Mukhina et al., J. Biol. Chem. 275 (2000), 16450-16458], the kringle domain of uPA was sufficient and required to stimulate cell motility. Here we report that uPA mutants containing the kringle domain specifically activate the p38 MAP-kinase pathway and actomyosin by increasing phosphorylation of the critical Ser-19 on the myosin regulatory light chain and MAP-kinase sites of the actin-associated regulatory protein caldesmon. While pharmacological inhibition of p38 MAP-kinase activation did not affect myosin light chain phosphorylation, it blocked the increase in caldesmon phosphorylation and uPA-stimulated migration of hAWSMC on a collagen-coated surface. We conclude that activation of p38 MAP-kinase and downstream phosphorylation of non-muscle caldesmon is essential for urokinase-stimulated smooth muscle cell migration.
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PMID:Activation of p38 MAP-kinase and caldesmon phosphorylation are essential for urokinase-induced human smooth muscle cell migration. 1193 Sep 38

Smooth muscle contraction is initiated by myosin light chain (MLC) phosphorylation catalyzed by the Ca(2+) dependent MLC kinase. However, many aspects of smooth muscle contraction cannot be accounted for by MLC phosphorylation. One hypothesis that has received experimental support involves the thin filament protein caldesmon. Caldesmon inhibits myosin ATPase activity; phosphorylation of caldesmon relieves this inhibitory effect. The primary candidates for catalysis of caldesmon phosphorylation are the p42/p44 ERK MAP kinases. However, we and others have shown that inhibition of the ERK MAP kinases has no effect on many smooth muscles. The goal of this study was to determine if evidence for a second endogenous caldesmon kinase may be obtained. We used Triton X-100 skinned and intact tissues of the swine carotid artery to address this goal. Caldesmon phosphorylation was evident in resting and Ca(2+) stimulated Triton X-100 skinned fibers. Ca(2+)-dependent caldesmon phosphorylation was partially sensitive to the ERK MAP kinase inhibitor PD98059, whereas all caldesmon phosphorylation was sensitive to the general kinase inhibitor, staurosporine. Histamine increased caldesmon phosphorylation levels in intact swine carotid artery, which was sensitive to both PD98059 and staurosporine. Histamine increased ERK MAP kinase activity, which was reversed by PD98059, staurosporine, and EGTA. Histamine-induced contractions were inhibited by staurosporine but not by PD98059. We interpret these results to suggest that although ERK MAP kinases catalyze caldesmon phosphorylation, a second staurosporine sensitive kinase is also important in caldesmon phosphorylation and it is this pathway that may be more important in contractile regulation.
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PMID:Caldesmon phosphorylation is catalyzed by two kinases in permeabilized and intact vascular smooth muscle. 1475 51

A comparative model been designed to study a contribution of proteinkinase C-(PKC)-activated intracellular signaling pathways in generation of different contractile responses of vascular (tonic) and visceral (phasic) smooth muscles. We have determined that, in tonic smooth muscle, PKC mediates activation of MAP-kinases that phosphorylate key regulatory proteins of the contractile system, myosin light chain kinase and caldesmon, leading to upregulation of actomyosine motor activity. In contrast, the MAP-kinase activation is uncoupled from the contractile machinery in phasic smooth muscles, which also reveal high levels of myosin light chain kinase-related protein KRP that contributes to relaxation. Phosphorylation of KRP following activation of PKC or cyclic nucleotide-dependent protein kinases enhances the KRP activity and further contributes to relaxion in phasic smooth muscle. A possibility is discussed for exploitation of the comparative model described herein for investigation of specific role of other regulatory intracellular pathways in generation of vascular tonic contraction.
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PMID:[Signaling regulatory mechanisms of the contractile activity of smooth muscle]. 1533 61

Smooth muscle in the pulmonary artery of PAH subjects, both idiopathic and hereditary, is characterized by hyperplasia. Smooth muscle cells (HPASMC) isolated from subjects with or without PAH retain their in vivo phenotype as illustrated by their expression of alpha-smooth muscle actin and expression of H-caldesmon. Both non PAH and PAH HPASMC display a lengthy, approximately 94h, cell cycle. The HPASMC from both idiopathic and hereditary PAH display an abnormal proliferation characterized by continued growth under non-proliferative, non-growth stimulated conditions. This effector independent proliferation is JNK and p38 MAP kinase dependent. Blocking the activation of either abrogates the HPASMC growth. HPASMC from non PAH donors under quiescent conditions display negligible proliferation but divide upon exposure to growth factors such as PDGF-BB or FGF2 but not EGF. This growth does not involve the MAP kinases. Instead it routes via the tyrosine kinase receptor through mTOR and then 6SK. In the PAH cells PDGF-BB and FGF2 augment the dysregulated cell proliferation, also through mTOR/6SK. Additionally, blocking the activation of mTOR also modulates the MAP kinase promoted dysregulated growth. These results highlight key alterations in the growth of HPASMC from subjects with PAH which contribute to the etiology of the disease and can clearly be targeted at various regulatory points for future therapies.
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PMID:Hyperplastic Growth of Pulmonary Artery Smooth Muscle Cells from Subjects with Pulmonary Arterial Hypertension Is Activated through JNK and p38 MAPK. 2590 60