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)

The effects of cGMP-dependent protein kinase (G-kinase), a major cellular receptor of cGMP, were investigated in activated human neutrophils. Immunocytochemistry demonstrated that G-kinase translocated from a diffuse localization in the cytoplasm to the cytoskeleton and nucleus after stimulation with N-formyl-methionyl-leucyl-phenylalanine (fMLP), and transiently co-localized with the intermediate filament protein, vimentin. During this time period, the most remarkable co-localization of G-kinase and vimentin was observed between 1-2.5 min stimulation with fMLP. At that time co-localization of G-kinase and vimentin was predominantly confined to filaments which extended from regions adjacent to the nucleus into the uropod. Distinctive localization for only G-kinase was observed at the microtubule organizing center and euchromatin of the nucleus. The filamentous staining pattern for G-kinase and vimentin was enhanced in the presence of 8-Br-cGMP. Coincident with co-localization of G-kinase and vimentin in adherent neutrophils was a transient increase in cGMP levels and an increase in the phosphorylation of vimentin in fMLP-stimulated cells. The increase in cGMP levels was dependent upon cell adherence, was enhanced by preincubating neutrophils with L-arginine (the precursor for nitric oxide synthesis), and attenuated with the nitric oxide synthase inhibitor, NG-monomethyl-L-arginine. Phosphorylation of vimentin in the fMLP-stimulated neutrophil was observed in the presence or absence of exogenous cGMP, although in the presence of low concentrations of 8-Br-cGMP a more rapid phosphorylation of vimentin was observed that correlated with the enhanced co-localization of G-kinase and vimentin. Phosphorylation of vimentin was not observed in non-activated cells treated with 8-Br-cGMP, suggesting that phosphorylation only occurs when G-kinase is co-localized with vimentin. The presence of the protein kinase C inhibitors, staurosporine or H-7, did not inhibit vimentin phosphorylation during fMLP stimulation, while 8-Br-cGMP enhanced phosphorylation in fMLP-treated cells. This suggests that neither protein kinase C nor cAMP-dependent protein kinase catalyze the phosphorylation of vimentin in neutrophils activated by fMLP. These results indicate that vimentin and G-kinase are co-localized in neutrophils and that vimentin is phosphorylated by G-kinase in response to the co-localization of the two proteins. A model for the targeting of G-kinase and vimentin is presented which hypothesizes that the transient redistribution of G-kinase may regulate neutrophil activation.
 ...
PMID:Vimentin is transiently co-localized with and phosphorylated by cyclic GMP-dependent protein kinase in formyl-peptide-stimulated neutrophils. 165 55

Evidence is shown that vimentin, the intermediate filament protein, is a substrate for protein kinase C: (a) Purified vimentin from Chinese hamster ovary cells can be phosphorylated by protein kinase C prepared from rabbit peritoneal neutrophils. Tryptic peptic analysis reveals multiple sites of phosphorylation distinct from those phosphorylated by cAMP-dependent protein kinase. (b) phosphorylation of membrane associated vimentin is stimulated in phorbol 12-myristate 13-acetate treated neutrophil membranes, suggesting that vimentin can be a substrate for membrane associated protein kinase C and (c) phorbol 12-myristate 13-acetate also stimulates the phosphorylation of vimentin in 32P-labeled intact neutrophils.
 ...
PMID:Vimentin, a cytoskeletal substrate of protein kinase C. 282 88

The intermediate filament protein vimentin was phosphorylated with cAMP-dependent protein kinase under conditions that induce filament disassembly. Digestion of phosphorylated vimentin with lysine-specific endoprotease and subsequent tryptic peptide mapping indicated that a 12 kDa N-terminal fragment contained all the phosphorylation sites found in the intact molecule. Analysis of cyanogen bromide digests indicated that two phosphorylated peptides were produced, with the major 32P-labeled species representing amino acid position 14-72, and a minor 32P-labeled peptide representing amino acid positions 1-13. These results demonstrate that phosphorylation of sites within the N-terminal head domain of vimentin are associated with phosphorylation induced filament disassembly.
 ...
PMID:Cyclic AMP-dependent protein kinase-induced vimentin filament disassembly involves modification of the N-terminal domain of intermediate filament subunits. 283 68

The accumulation of two polypeptides, SCm1 and SCm2, in the medium of Sertoli cell cultures is enhanced by follicle-stimulating hormone (FSH) but is unaffected by either the cAMP analog, N6,O2'-dibutyrl cAMP or luteinizing hormone. The assigned molecular weights of SCm1 and SCm2 differ from those of androgen-binding protein subunits or any other previously identified Sertoli cell secretory product. Incubation of Sertoli cell cultures with either FSH or N6,O2'-dibutyryl cAMP also stimulates the incorporation of [35S]methionine into two intracellular polypeptides, SCc1 and SCc2. In addition, the phosphorylation of three intracellular polypeptides, SCc3, SCc4, and SCc5, is intensified when Sertoli cell cultures are treated with either FSH or N6,O2'-dibutyryl cAMP. Based on these results and on previous work, we conclude that (i) SCm1 and SCm2 may, like androgen-binding protein, be secreted by Sertoli cells and function extracellularly while SCc1 and SCc2 are involved in FSH-dependent intracellular activity; (ii) SCc3, SCc4, and SCc5 are possible substrates for FSH-stimulated, cAMP-dependent protein kinase activity; and (iii) SCc5 is an isoelectric variant of vimentin-type intermediate filament protein presumably involved in FSH- and N6,O2'-dibutyryl cAMP-induced Sertoli cell shape changes.
 ...
PMID:Hormonal regulation of protein synthesis, secretion, and phosphorylation in cultured rat Sertoli cells. 629 7

Endogenous protein phosphorylation was investigated in cultured rat Sertoli cells after treatment with follicle-stimulating hormone (FSH) and pharmacological agents that activate cAMP-dependent protein kinases. In intact Sertoli cells, both phosphorylation and dephosphorylation of proteins occurred in response to treatment with these agents. Studies using cell-free preparations suggest that four phosphoproteins phosphorylated by cAMP or the catalytic subunit of cAMP-dependent protein kinase were also phosphorylated in a FSH-dependent manner in intact cells. These data suggest that FSH-dependent phosphorylation in Sertoli cells occurs through activation of a cAMP-dependent protein kinase. A FSH-dependent phosphoprotein with a molecular weight of 58,000 was identified as the intermediate filament protein vimentin, based on its migration in two-dimensional gels and its peptide map. The cellular distribution of vimentin was monitored by immunofluorescence in Sertoli cells after treatment with FSH. Results of this study support a role for intermediate filaments in FSH-dependent events in Sertoli cells.
 ...
PMID:Follicle-stimulating hormone-dependent phosphorylation of vimentin in cultures of rat Sertoli cells. 630 79

Rabbit peritoneal neutrophils were reacted for 5-10 s with the chemotactic factors, fMet-Leu-Phe or (5S),(12R)-dihydroxy-6,8,11,14-(cis,trans,trans,cis)-eicosatetraenoic acid and then lysed with a solution of Triton X-100 and [gamma-32P]ATP. They showed an enhanced incorporation of 32P in Mr = 60,000- and 67,000-dalton polypeptides compared to control cells treated similarly. Another chemotactic factor, C5a, produced a similar but much lesser effect. The enhancement was not affected by the addition of the purified catalytic subunit of cAMP-dependent protein kinase, the inhibitor of cAMP-dependent protein kinase, or CaCl2, suggesting that the effect was not mediated by a cAMP-dependent or a Ca2+-dependent protein kinase. When analyzed by two-dimensional gel electrophoresis, the Mr = 60,000 phosphoprotein contained several phosphoproteins with different isoelectric points. The isoelectric point and molecular weight of one of them was similar to those of the intermediate filament protein, vimentin, purified from Chinese hamster ovary cells. Addition of the purified Chinese hamster ovary vimentin and [gamma-32P]ATP to the Triton X-100 lysate of fMet-Leu-Phe-treated neutrophils resulted as an enhanced incorporation of 32P into the vimentin. Addition of fMet-Leu-Phe to 32P-labeled intact neutrophils also enhanced incorporation of 32P into the vimentin of neutrophils. The results suggest that chemotactic factors stimulate vimentin phosphorylation in rabbit neutrophils.
 ...
PMID:Chemotactic factors induced vimentin phosphorylation in rabbit peritoneal neutrophil. 669 9

Purified assembly-competent vimentin, an intermediate filament protein, was obtained from bovine lens in this study. The effects of withangulatin A on vimentin assembly with or without phosphorylation were examined by negative-stain electron microscopy. Soluble tetrameric vimentin was assembled into irregular fibrils with lateral associations or short filaments after pretreatment with 50 or 100 microM withangulatin A, respectively. Incubation of assembled vimentin filaments with withangulatin A at 50 or 100 microM resulted in the formation of aggregates, and the degree of aggregation was concentration dependent. The appearance of vimentin filaments was slightly altered after treatment with cAMP-dependent protein kinase or protein kinase C; however, phosphorylation of filamentous vimentin by the protein kinases in the presence of withangulatin A resulted in higher degrees of aggregation of the filaments, compared with those treated only with the drug. Moreover, the level of phosphorylation of filamentous vimentin by the protein kinases was augmented in the presence of withangulatin A. Experimental results indicated that withangulatin A directly and specifically affects the conformation of the vimentin molecules, thereby resulting in alterations in assembly behavior and reactivity toward cAMP-dependent protein kinase and protein kinase C. The data observed further imply that withangulatin A, which directly causes aggregation of vimentin filaments, is a vimentin intermediate filament-targeting drug.
 ...
PMID:Induction of aggregation and augmentation of protein kinase-mediated phosphorylation of purified vimentin intermediate filaments by withangulatin A. 796 40