Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0344329 (collapse)
 28,634 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Microinjection of the purified catalytic subunit of the cAMP-dependent protein kinase (A-kinase) into living rat embryo fibroblasts leads to dramatic changes in vimentin intermediate filament (IF) organization, involving the collapse of the filaments into tight bundles. In some cell types, this rearrangement of the IF proceeds further, leading to an apparent loss of filament integrity, resulting in a punctate staining pattern throughout the cytoplasm. Both these types of IF rearrangement are fully reversible, and similar to structural changes previously described for IF during mitosis. As shown by electron microscopy, in rat embryo fibroblasts these changes in IF structure do not involve the loss of the 10-nM filament structure but instead correspond to the bundling together of 25 or more individual filaments. Metabolic pulse labeling of injected cells reveals that accompanying these changes in IF organization is a dramatic increase in vimentin phosphorylation which appears maximal when the IF are fully rearranged. However, this increase in IF phosphorylation is not accompanied by any significant increase in soluble vimentin. Analysis of the sites of phosphorylation on vimentin from injected cells by either V8 protease cleavage, or two-dimensional tryptic peptide mapping, revealed increased de novo phosphorylation of two vimentin phosphopeptides after microinjection of A-kinase. These data strongly suggest that the site-specific phosphorylation of vimentin by A-kinase is responsible for the dynamic changes in IF organization observed after injection of the kinase into living cells, and may be involved in similar rearrangement of the IF previously described during mitosis or after heat shock.
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PMID:Modulation of vimentin containing intermediate filament distribution and phosphorylation in living fibroblasts by the cAMP-dependent protein kinase. 266 62

Experiments were designed to examine whether calcitonin gene-related peptide (CGRP), a potent adenosine 3',5'-cyclic monophosphate (cAMP)-dependent vasodilator, affects the production of NO evoked by interleukin-1 beta) (IL-1 beta) in cultured rat aortic smooth muscle cells (SMC). CGRP, in a concentration-dependent manner, enhanced the release of nitrite (a stable oxidation product of NO) and the formation of L-citrulline from L-arginine caused by IL-1 beta. Two cAMP-dependent vasodilators, forskolin and isoproterenol, and the activator of the cAMP-dependent protein kinase, Sp-cAMPS, also enhanced the release of nitrite and the formation of L-citrulline evoked by IL-1 beta. The enhancing effect of isoproterenol required the presence of the vasodilator during the induction of NO synthase (NOS). IL-1 beta-treated vascular SMC inhibited the aggregation of indomethacin-treated platelets. Inhibition of platelet aggregation was more marked with SMC exposed to a combination of IL-1 beta and either CGRP or isoproterenol than with cells exposed to IL-1 beta alone. This inhibition was prevented by methylene blue and oxyhemoglobin. IL-1 beta induced the expression of inducible NOS mRNA in vascular SMC, which was enhanced by coincubation of IL-1 beta with either CGRP, isoproterenol, or forskolin. These observations indicate that CGRP via a cAMP-dependent mechanism potentiates the IL-1-beta-induced production of NO by enhancing the expression of inducible NOS. Therefore CGRP may contribute to the substantial production of NO in the vasculature during septic shock, which accounts, at least in part, for the collapse of the vascular system.
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PMID:CGRP enhances induction of NO synthase in vascular smooth muscle cells via a cAMP-dependent mechanism. 752 98

Previously, we utilized small-angle X-ray scattering and neutron scattering with contrast variation to obtain the first low-resolution structure of 4Ca2+.calmodulin (CaM) complexed with a functional enzyme, an enzymatically active truncation mutant of skeletal muscle myosin light chain kinase (MLCK). These experiments showed that, upon binding to MLCK, CaM undergoes a conformational collapse identical to that observed when CaM binds to the isolated peptide corresponding to the CaM binding sequence of MLCK. CaM thereby was shown to release the inhibition of the kinase by inducing a significant movement of its CaM binding and autoinhibitory sequences away from the surface of the catalytic core [Krueger, J. K., Olah, G. A., Rokop, S. E., Zhi, G., Stull, J. T., and Trewhella, J. (1997) Biochemistry 36, 6017-6023]. We report here similar scattering experiments on the CaM.MLCK complex with the addition of substrates; a nonhydrolyzable analogue of adenosine-triphosphate, AMPPNP, and a peptide substrate for MLCK, a phosphorylation sequence from myosin regulatory light chain (pRLC). These substrates are shown to induce an overall compaction of the complex. The separation of the centers-of-mass of the CaM and MLCK components is shortened (by approximately 12 A), thus bringing CaM closer to the catalytic site compared to the complex without substrates. In addition, there appears to be a reorientation of CaM with respect to the kinase upon substrate binding that results in interactions between the N-terminal sequence of CaM and the kinase that were not observed in the complex without substrates. Finally, the kinase itself becomes more compact in the CaM.MLCK.pRLC.AMPPNP complex compared to the complex without substrates. This observed compaction of MLCK upon substrate binding is similar to that arising from the closure of the catalytic cleft in cAMP-dependent protein kinase upon binding pseudosubstrate.
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PMID:Neutron-scattering studies reveal further details of the Ca2+/calmodulin-dependent activation mechanism of myosin light chain kinase. 976 Feb 34

To identify phosphoproteins that might play a role in naringin-sensitive hepatocellular cytoskeletal disruption and apoptosis induced by algal toxins, hepatocyte extracts were separated by gel electrophoresis and immunostained with a phosphothreonine-directed antibody. Use of dilute (5%) polyacrylamide gels containing 6 m urea allowed the resolution of one very large (approximately 500-kDa) okadaic acid- and naringin-sensitive phosphoprotein, identified by tryptic fingerprinting, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and immunostaining as the cytolinker protein, plectin. The naringin-sensitive phosphorylation induced by okadaic acid and microcystin-LR probably reflected inhibition of a type 2A protein phosphatase, whereas the naringin-resistant phosphorylation induced by calyculin A, tautomycin, and cantharidin probably involved a type 1 phosphatase. Okadaic acid caused a collapse of the plectin-immunostaining bile canalicular sheaths and the general cytoskeletal plectin network into numerous medium-sized plectin aggregates. Inhibitors of protein kinase C, cAMP-dependent protein kinase, or Ca(2+)/calmodulin-dependent kinase II had moderate or no protective effects on plectin network disruption, whereas naringin offered 86% protection. Okadaic acid induced a naringin-sensitive phosphorylation of AMP-activated protein kinase (AMPK), the stress-activated protein kinases SEK1 and JNK, and S6 kinase. The AMPK-activating kinase (AMPKK) is likely to be the target of inhibition by naringin, the other kinases serving as downstream components of an AMPKK-initiated signaling pathway.
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PMID:Naringin-sensitive phosphorylation of plectin, a cytoskeletal cross-linking protein, in isolated rat hepatocytes. 1209 91

Verrucotoxin is the major component of venom from the stonefish (Synanceia verrucosa). Stings from the dorsal spines of the stonefish produce intensive pain, convulsions, hypotension, paralysis, respiratory weakness and collapse of the cardiovascular system, occasionally leading to death. It has been reported that verrucotoxin might modulate ATP-sensitive K+ (KATP) current in frog atrial fibers. However, the mechanism by which verrucotoxin acts on KATP current remains unclear. In this study, we examined whether verrucotoxin inhibited KATP current in guinea pig ventricular myocytes, using the patch clamp method. Verrucotoxin suppressed KATP current induced by pinacidil (KATP channel opener) in a concentration-dependent manner, with a half maximum concentration of 16.3 microg/ml. The effect of verrucotoxin on KATP current was suppressed by atropine (1 microM), a muscarinic receptor antagonist, or by 4-diphenylacetoxy-N-methylpiperidine (100 nM), a muscarinic M3 receptor antagonist. Furthermore, the effect of verrucotoxin on KATP current was attenuated by the protein kinase C (PKC) inhibitor chelerythrine (10 microM) and calphostin C (10 microM), yet not by the cAMP-dependent protein kinase (PKA) inhibitor H-89 (0.5 microM). These results suggest that verrucotoxin inhibits KATP current through the muscarinic M3 receptor-PKC pathway. These findings enhance our understanding of the toxic effects of verrucotoxin from the stonefish.
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PMID:Verrucotoxin inhibits KATP channels in cardiac myocytes through a muscarinic M3 receptor-PKC pathway. 1736 22

Optogenetic tools provide a level of spatial and temporal resolution needed to shed new light on dynamic intercellular processes. In this chapter we outline specific protocols for applying these tools to cell motility (optogenetic cofilin), apoptosis [optogenetic Bcl-like protein 4 (Bax)], and protein kinase-mediated signaling pathways [optogenetic cAMP-dependent protein kinase (PKA)]. The activity of these optogenetic species is regulated by the light-mediated dimerization of a cryptochrome/Cib protein pair, which controls the intracellular positioning of the protein of interest. The light induced recruitment of cofilin to the cytoskeleton is utilized for directed migration studies and filopodial dynamics. Light-triggered migration of Bax to the outer mitochondrial membrane induces cellular collapse and eventual apoptosis. Finally, the light-mediated movement of PKA to specific intracellular compartments offers the means to assess the consequences of PKA activity in a site-specific fashion via phosphoproteomic analysis.
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PMID:Optogenetic perturbation of the biochemical pathways that control cell behavior. 3115 59