Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.11 (AMPK)
 12,425 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Endothelial cell (EC) cytoskeletal proteins are one of the earliest primary targets of second messenger cascades generated in response to inflammatory agonists. Actin binding proteins, by modulating actin gelation-solation state and membrane-cytoskeleton interactions, in part regulate cell motility and cell-cell apposition. This in turn can also modulate interendothelial junctional diameter and permeability. Nonmuscle filamin (ABP-280), a dimeric actin-crosslinking protein, promotes orthogonal branching of F-actin and links microfilaments to membrane glycoproteins. In the present study, immunoblot analysis demonstrates that filamin protein levels are low in sparse EC cultures, increase once cell-cell contact is initiated and then decrease slightly at post-confluency. Both bradykinin and ionomycin cause filamin redistribution from the peripheral cell border to the cytosol of confluent EC. Forskolin, an activator of adenylate cyclase, blocks filamin translocation. Bradykinin activation of EC is not accompanied by significant proteolytic cleavage of filamin. Instead, intact filamin is recycled back to the membrane within 5-10 min of bradykinin stimulation. Inhibitors of calcium/calmodulin dependent protein kinase (KT-5926 and KN-62) attenuate bradykinin-induced filamin translocation. H-89, an inhibitor of cAMP-dependent protein kinase, causes translocation of filamin in unstimulated cells. Calyculin A, an inhibitor of protein phosphatases, also causes translocation of filamin in the absence of an inflammatory agent. ML-7, an inhibitor of myosin light chain kinase and phorbol myristate acetate, an activator of protein kinase C, do not cause filamin movement into the cytosol, indicating that these pathways do not modulate the translocation. Pharmacological data suggest that filamin translocation is initiated by the calcium/calmodulin-dependent protein kinase whereas the cAMP-dependent protein kinase pathway prevents translocation. Inflammatory agents therefore may increase vascular junctional permeability by increasing cytoplasmic calcium, which disassembles the microfilament dense peripheral band by releasing filamin from F-actin.
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PMID:Filamin translocation is an early endothelial cell inflammatory response to bradykinin: regulation by calcium, protein kinases, and protein phosphatases. 887 9

Hypoxia/reoxygenation injury in vitro causes endothelial cell cytoskeletal rearrangement that is related to increased monolayer permeability. Nonmuscle filamin (ABP-280) promotes orthogonal branching of F-actin and links microfilaments to membrane glycoproteins. Human umbilical vein endothelial cell monolayers are exposed to H2O2 (100 microM) for 1-60 min, with or without modulators of cAMP-dependent second-messenger pathways, and evaluated for changes in filamin distribution, cAMP levels, and the formation of gaps at interendothelial junctions. Filamin translocates from the membrane-cytoskeletal interface to the cytosol within 1 min of exposure to H2O2. This is associated with a decrease in endothelial cell cAMP levels from 83 pmoles/mg protein to 15 pmoles/mg protein. Intercellular gaps form 15 min after H2O2 treatment and progressively increase in number and diameter through 60 min. Both filamin redistribution and actin redistribution are associated with decreased phosphorylation of filamin and are prevented by activation of the cAMP-dependent protein kinase pathway. A synthetic peptide corresponding to filamin's C-terminal, cAMP-dependent, protein kinase phosphorylation site effectively induces filamin translocation and intercellular gap formation, which suggests that decreased phosphorylation of filamin at this site causes filamin redistribution and destabilization of junctions. These data indicate that H2O2-induced filamin redistribution and interendothelial cell gap formation result from inhibition of the cAMP-dependent protein kinase pathway.
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PMID:H2O2-induced filamin redistribution in endothelial cells is modulated by the cyclic AMP-dependent protein kinase pathway. 928 57

Three different C-terminal regions of human endothelial actin-binding protein-280 (ABP-280 or ABP; nonmuscle filamin) were subcloned and efficiently expressed in the Escherichia coli BL21 (DE3) system as indicated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. As predicted by the aminoacid sequence one of the fragments, a 109-kDa peptide (residues 1671-2647), contained a calpain cleavage site and two potential cAMP-dependent protein kinase (PKA) phosphorylation sites (serine 2152 and threonine 2336). A second fragment, a 74-kDa peptide (residues 1671-2331), contained a calpain cleavage site and one of the three presumptive PKA phosphorylation sites (serine 2152). The third fragment, a 48-kDa peptide (residues 2223-2647), contained only one of the PKA sites (threonine 2336). Phosphorylation of these truncated peptides indicated that only the fragments containing serine 2152 incorporated phosphate after PKA treatment. Site-directed mutagenesis analysis confirmed that serine 2152 is the unique substrate for PKA in the C-terminal region of ABP. The functional significance of phosphorylation of this residue, which belongs to a serine-proline motif, is discussed.
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PMID:Determination of a cAMP-dependent protein kinase phosphorylation site in the C-terminal region of human endothelial actin-binding protein. 1077 44

A C-terminal region of human endothelial actin-binding protein-280 (ABP-280 or ABP, non-muscle filamin) was subcloned and efficiently expressed in a mammalian cells system as indicated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting analysis. As predicted by the aminoacid sequence, the fragment, a 79 kD peptide (residues 1671-2361, plus 3.9 kD from an N-terminal fusion peptide included in the expression plasmid), contained the two potential cAMP-dependent protein kinase (PKA) phosphorylation sites (serine 2152 and threonine 2336) predicted to be present in this region of the molecule. Incubation of cells in the presence of cAMP-elevating agents enhanced 32P uptake into the fragment. Site-directed mutagenesis analysis indicated that serine 2152 is the unique substrate in the C-terminal region of ABP for endogenously activated PKA. The functional implications of phosphorylation of this residue, which belongs to a serine-proline motif, are discussed in terms of the role of filamin in cytoskeleton reorganization.
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PMID:In situ determination of a PKA phosphorylation site in the C-terminal region of filamin. 1522 85