thromboxane-a2 and Hypertrophy

The protective effect of aspirin against myocardial hypertrophy (MH) was studied. Model rats of pressure overload MH were prepared by abdominal aortic coarctation. Rats were randomly divided into the sham group (

Topics: Animals; Apoptosis; Aspirin; Blood Pressure; Body Weight; Cardiotonic Agents; Disease Models, Animal; Fibrillar Collagens; Heart Ventricles; Hypertrophy; Inflammation Mediators; Interleukin-10; Male; Myocardium; Myocytes, Cardiac; Organ Size; Prostaglandins; Rats, Wistar; Thromboxane A2; Tumor Necrosis Factor-alpha

In the present study, we examined the effect of the thromboxane/prostaglandin endoperoxide analogue U46619 on proliferation and hypertrophy in cultured rat vascular smooth muscle cells and the roles of protein kinase C and transforming growth factor-beta (TGF-beta) in the mediation of the hypertrophic response to U46619. Since an increase in basic fibroblast growth factor (bFGF) was previously shown to mediate the hypertrophic response to U46619, we also assessed the relationship between bFGF and TGF-beta in the expression of U46619 actions. U46619 increased [35S]methionine incorporation into protein and protein content of vascular smooth muscle cells but had no effect on cell number. A role for TGF-beta was supported by the following observations: (1) exogenous human TGF-beta 1 increased protein synthesis; (2) antibody to TGF-beta blocked both TGF-beta- and U46619-induced increases in protein content; (3) U46619 increased active and total TGF-beta bioactivities; and (4) the actions of U46619 on protein content and TGF-beta bioactivity were blocked by the thromboxane/prostaglandin endoperoxide receptor antagonist SQ 29,548. Previous observations had demonstrated a role for bFGF in the expression of U46619 actions on protein synthesis. Results of the present study suggest that TGF-beta and bFGF interact in mediating the protein synthetic response to U46619. First, the concentration of exogenous TGF-beta (10 pmol/L) alone required to produce a protein synthetic response equivalent to that induced by U46619 was much higher than the concentration of endogenous active TGF-beta that accumulated in the media in response to U46619 (0.7 pmol/L). Second, bFGF (20 ng/mL) increased total TGF-beta bioactivity and stimulated protein synthesis. The hyper-trophic response to bFGF was blocked by anti-TGF-beta. The ability of U46619 and bFGF to increase protein synthesis and protein content in vascular smooth muscle cells was associated with TGF-beta-induced suppression of proliferation, as evidenced by the ability of antibody to TGF-beta to enhance U46619- and bFGF-induced increases in [3H]thymidine incorporation into DNA. Results of the present study also supported a role for protein kinase C in the expression of U46619 and bFGF actions. U46619 increased protein kinase C activity in the particulate fraction of vascular smooth muscle cells. Moreover, the protein kinase C inhibitors GF109203X and staurosporine blocked U46619- and bFGF-induced increases in protein synthesis

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Cell Division; Cells, Cultured; Dose-Response Relationship, Drug; Fibroblast Growth Factor 2; Humans; Hypertrophy; Male; Muscle, Smooth, Vascular; Prostaglandin Endoperoxides, Synthetic; Protein Biosynthesis; Protein Kinase C; Rats; Rats, Inbred WKY; Thromboxane A2; Transforming Growth Factor beta; Vasoconstrictor Agents

Vascular smooth muscle cells (VSMC) undergo hypertrophy when exposed to thromboxane A2 and hyperplasia when exposed to phorbol 12-myristate 13-acetate (PMA) or platelet-derived growth factor (PDGF). Each of these three agonists stimulate rapid tyrosine phosphorylation of numerous VSMC proteins. The current studies were undertaken to identify proteins that are specifically tyrosine phosphorylated in one or the other growth response. All three agonists increased the phosphotyrosine content of multiple proteins. In Western analysis of phosphotyrosine immunoprecipitates, the hyperplastic agents PDGF and PMA increased tyrosine phosphorylation of phospholipase C-gamma 1 (PLC-gamma 1), GTPase-activating protein (GAP), and phosphatidylinositol-3-kinase (PI-3-kinase), while the hypertrophic agonist thromboxane failed to tyrosine-phosphorylate either of these three substrates. Tyrosine kinase inhibition with herbimycin A (5 microM) prevented agonist-stimulated tyrosine phosphorylation of PLC-gamma 1, GAP, and PI-3-kinase. In growth studies, herbimycin A inhibited PMA- and PDGF-induced hyperplasia but not thromboxane-stimulated hypertrophy. These results indicate that tyrosine phosphorylation of PLC-gamma 1, GAP, and PI-3-kinase are specific responses for VSMC hyperplasia but not thromboxane-stimulated hypertrophy.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Cells, Cultured; Hyperplasia; Hypertrophy; Muscle, Smooth, Vascular; Phosphatidylinositol 3-Kinases; Phosphorylation; Phosphotransferases (Alcohol Group Acceptor); Platelet-Derived Growth Factor; Prostaglandin Endoperoxides, Synthetic; Protein-Tyrosine Kinases; Rats; Tetradecanoylphorbol Acetate; Thromboxane A2; Type C Phospholipases; Tyrosine

We have shown previously that thromboxane A2 stimulates hypertrophy of cultured rat aortic smooth muscle cells defined as protooncogene expression and protein synthesis without DNA synthesis or cellular proliferation (Dorn, G.W., II, Becker, M.W., Davis, M.G. (1992) J. Biol. Chem. 267, 24897-24905). Since endogenous growth modulators could possibly regulate vascular smooth muscle growth to this vasoconstrictor, we tested the hypothesis that thromboxane-stimulated vascular smooth muscle hypertrophy was due to increased expression of endogenously produced basic fibroblast growth factor (bFGF). The thromboxane mimetic (15S)-hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5Z,13E-dienoic acid (U46619) (1 microM) increased cultured rat aorta derived smooth muscle cell immunoreactive bFGF content by 331 +/- 40% over untreated controls after 24 h. Co-incubation of vascular smooth muscle cells with a specific antisense oligodeoxynucleotide (AS) against codon 60 of bFGF coding sequence reduced thromboxane-stimulated bFGF expression by 72 +/- 5% and prevented thromboxane-stimulated hypertrophy (nonsense oligonucleotide had no effects). Addition of exogenous bFGF (20 ng/ml) restored growth to AS-treated/thromboxane-stimulated vascular smooth muscle cells. Furthermore, addition to the culture medium of neutralizing antibody against bFGF inhibited U46619-stimulated vascular smooth muscle hypertrophy by 69 +/- 17%, whereas nonimmune IgG had no effect. Since protein tyrosine phosphorylation is a cell signal associated with growth, thromboxane-stimulated tyrosine phosphorylation was also examined. Exposure to 1 microM U46619 for 10 min increased vascular smooth muscle immunoreactive phosphotyrosine content of 130-144-, 86-, 80-, 75-, and 58-kDa proteins. The tyrosine kinase inhibitor herbimycin A (5 microM) prevented thromboxane-stimulated tyrosine phosphorylation, but not thromboxane-stimulated hypertrophy, suggesting that tyrosine phosphorylation was not required for thromboxane-stimulated vascular smooth muscle growth. These results indicate that increased expression and release of endogenous bFGF, but not direct tyrosine phosphorylation, mediates the hypertrophic vascular smooth muscle response to thromboxane.

Topics: Animals; Base Sequence; Benzoquinones; DNA; Fibroblast Growth Factor 2; Humans; Hypertrophy; Lactams, Macrocyclic; Molecular Sequence Data; Muscle, Smooth, Vascular; Phosphorylation; Protein Kinase Inhibitors; Quinones; Rats; Rifabutin; Thromboxane A2; Tyrosine; Up-Regulation

A prospective study was carried out to assess the possible biochemical background of the AAm production by HVF in accordance with selected histological types and voice disorders. The mass of new tissue forming HVF in different clinical cases led us to suspect, according to our previous results, that PGs, LTs and other AAm may be involved in the pathogenesis of HVF. The level of PGE2 in HFV was lower (0.7 ng/ml) than in control (1.09 ng/ml) but not significantly; the PGI2 level (0.01 ng/ml) in HVF was also nonsignificantly lower than in normals, while thromboxane A2 synthesis by HVF (0.42 ng/ml) was significantly less than in control (0.99 ng/ml). On the basis of these results the hypothesis of a possible role of AAm in the process of HVF could not be confirmed.

Topics: Adult; Dinoprostone; Epoprostenol; Female; Humans; Hypertrophy; Larynx; Male; Radioimmunoassay; Thromboxane A2