Generation of point-mutant FAK knockin mice.

Focal adhesion kinase is a non-receptor protein tyrosine kinase with signaling functions downstream of integrins and growth factor receptors. In addition to its role in adhesion, migration, and proliferation it also has non-kinase scaffolding functions in the nucleus. Focal adhesion kinase (FAK) activation involves the following: (1) ligand bound growth factors or clustered integrins activate FAK kinase domain; (2) FAK autophosphorylates tyrosine (Y) 397; (3) Src binds pY397 and phosphorylates FAK at various other sites including Y861; (4) downstream signaling of activated FAK elicits changes in cellular behavior. Although many studies have demonstrated roles for the kinase domain, Y397 and Y861 sites, in vitro much less is known about their functions in vivo. Here, we report the generation of a series of FAK-mutant knockin mice where mutant FAK, either kinase dead, non-phosphorylatable mutants Y397F and Y861F, or mutant Y397E-containing a phosphomimetic site that results in a constitutive active Y397, can be expressed in a Cre inducible fashion driven by the ROSA26 promoter. In future studies, intercrossing these mice with FAKflox/flox mice and inducible cre-expressing mice will enable the in vivo study of mutant FAK function in the absence of endogenous FAK in a spatially and temporally regulated fashion within the whole organism.

Endothelin-1 synthesis reduced by red wine.

Statistical evidence of reduced coronary heart disease in areas of high wine consumption has led to the widespread belief that wine affords a protective effect. Although moderate drinking of any alcohol helps to reduce the incidence of coronary heart disease, there is no clear evidence that red wine confers an additional benefit. Here we show that red wines strongly inhibit the synthesis of endothelin-1, a vasoactive peptide that is crucial in the development of coronary atherosclerosis. Our findings indicate that components specific to red wine may help to prevent coronary heart disease.

Relationship between soluble intracellular endothelin-converting enzyme and endothelin-1 synthesis: effect of inhibitors of the secretory pathway.

The relationship between soluble and membrane-bound endothelin-converting enzyme (ECE) activity with the level of endothelin-1 (ET-1) synthesis was investigated in cultured endothelial cells. Escherichia coli lipopolysaccharide (LPS) was used to stimulate ET-1 synthesis, and brefeldin A, monensin, colchicine or cytochalasin B, which disrupt peptide biosynthetic pathways in a variety of ways, were tested for their ability to modify changes in ET-1 synthesis and ECE levels. LPS increased ET-1 secretion by more than twofold. Levels of soluble ECE activity, but not those of membrane-bound ECE activity, correlated with ET-1 synthesis. These results suggest the soluble ECE activity is likely to play a role in ET-1 biosynthesis.

Endothelin-2 synthesis is stimulated by the type-1 tumour necrosis factor receptor and cAMP: comparison with endothelin-converting enzyme-1 expression.

ABSTRACT The synthesis of the vasoconstrictor peptide endothelin-2 (ET-2) is dependent on hydrolysis of the biologically inactive intermediate big ET-2 by an endothelin-converting enzyme (ECE). Here, mechanisms inducing ET-2 synthesis have been investigated using the human renal adenocarcinoma cell line (ACHN). Synthesis of ET-2 by ACHN cells was inhibited by phosphoramidon (IC(50( congruent with11 microM). To determine whether ET-2 synthesis occurs in parallel with the metallopeptidase ECE-1, a putative processing peptidase for big ET-2, changes in the levels of their mRNAs were compared by semi-quantitative RT-PCR under conditions causing the upregulation of ET-2 synthesis. Tumour necrosis factor-alpha (TNFalpha), forskolin and a cell-permeable cAMP analogue (dibutyryl cAMP) caused concentration-dependent increases in ET-2 synthesis. Combination of forskolin or dibutyryl cAMP with TNFalpha produced a significantly greater increase in ET-2 production than these agents alone, indicating that adenylate cyclase and TNFalpha induce ET-2 synthesis by separate signalling pathways. Studies using receptor selective TNFalpha mutants, (125(I-TNFalpha binding and TNF receptor mRNA showed that type-1 TNF receptors mediate the ET-2 response to TNFalpha. PreproET-2 mRNA levels were increased by TNFalpha at 1 h and 2 h, but returned to control levels at 4 h. Treatment with forskolin significantly increased preproET-2 mRNA levels after 1 h and 4 h. ACHN cells expressed ECE-1b and ECE-1c, but not the ECE-1a isoform of this peptidase. RT-PCR for the combined isoforms ECE-1b/c/d showed TNFalpha to increase mRNA levels at 2 h and 4 h. Forskolin had no effect on ECE-1b/c/d mRNA levels. Thus, expression of ET-2 and ECE-1b/c/d mRNAs in ACHN cells do not display the co-ordinated regulation observed with typical peptide prohormone processing enzymes and their substrates.

The p55 tumor necrosis factor receptor (CD120a) induces endothelin-1 synthesis in endothelial and epithelial cells.

Synthesis of the vasoconstrictor peptide endothelin-1 by endothelial and epithelial cells is strongly induced by tumor necrosis factor alpha (TNF-alpha). The actions of TNF-alpha are mediated by two transmembrane receptors of approximately 55 (p55, CD120a) and 75 kDa (p75, CD120b). Reagents activating selectively these receptor subtypes have been used to identify which TNF receptor mediates the induction of endothelin-1 synthesis. Stimulation of bovine aortic endothelial cells or human HEp-2 epithelial cells with a p55-selective mutant of human TNF-alpha (R32W-S86T) induced significant and concentration-dependent increases in endothelin-1 release. A p75 receptor-selective TNF-alpha mutant (D143N-A145R) was ineffective alone or in combination with the p55-selective mutant. Competitive binding experiments with [125I]TNF-alpha showed the p55-selective mutant, but not the p75-selective mutant, to inhibit the binding of [125I]TNF-alpha to endothelial and HEp-2 cells. Similar results were obtained with the p55 agonist antibody htr1 in both cell lines. These results establish the p55 TNF receptor as the main receptor involved in the induction of endothelin-1 synthesis by TNF-alpha.