Endothelin ETA receptor regulates signaling and ANF gene expression via multiple G protein-linked pathways

Abstract

We have characterized the interaction of endothelin (ET) with cultured neonatal rat ventricular myocytes. Binding studies indicate a single population of ETA receptors [53,000 sites/cell, apparent dissociation constant (Kd) for ET-1 approximately 0.07 nM]. Analysis of mRNA levels for ET receptors using 35 cycles of reverse transcriptase-polymerase chain reaction demonstrates the presence of only ETA-receptor message. Studies with ET-1 and a variety of congeners and antagonists indicate that ETA receptors couple to both the stimulation of phosphoinositide turnover and the inhibition of adenylyl cyclase. In myocytes transfected with an atrial natriuretic factor (ANF) promoter linked to a luciferase reporter gene, ET-1 stimulates luciferase expression through an ETA receptor. These data indicate that the ETA receptor is the exclusive receptor on neonatal ventricular myocytes and that this receptor couples to both phosphoinositide hydrolysis and adenylyl cyclase. ET-1 also induces a threefold increase in mitogen-activated protein kinase (MAPK) activity, an effect that is not sensitive to pertussis toxin (PTx). By contrast, ET-stimulated ANF-luciferase expression is partially inhibited by treatment of cells with PTx, suggesting that both PTx-sensitive (Gi) and PTx-insensitive (Gq) pathways mediate the effects of ET-1 on ANF gene expression in neonatal myocytes and that hormonal regulation of ANF expression may utilize pathways in addition to the activation of MAPK.

Endothelin downregulates SERCA2 gene and protein expression in adult rat ventricular myocytes: regulation by pertussis toxin-sensitive Giprotein and cAMP

“…This is in agreement with our previous findings that ET binds and mediates its effects in myocytes through a single population of ET A receptors (17,18). The involvement of the ET A receptor in mediating myocyte hypertrophy is supported by experimental and clinical studies showing that antagonism of the ET A rather than the ET B receptor is effective in reducing left ventricular hypertrophy and in improving cardiac function (21,25).…”

“…ET induces hypertrophic or growth responses in neonatal cardiac myocytes marked by increase in cell size, organization of the actin filaments, and enhanced protein synthesis (18,37). In adult rat ventricular myocytes, the effect of ET on cell size and organization is less prominent, so we employed [ 3 H]phenylalanine incorporation as a measure of increased protein synthesis and thus of a hypertrophic response.…”

The Vascular Endothelin System in Hypertension - Recent Patents and Discoveries

“…ET receptor activation leads to diverse cellular responses through interaction with pertussis toxin-sensitive and insensitive pathways, indicating that multiple G-proteins are involved [51][52][53] (Fig. 3).…”

G-proteins in growth and apoptosis: lessons from the heart

“…G i activation can contribute to the hypertrophic response to these agonists. For example, inhibition of G i signaling with pertussis toxin partially inhibits ET-1 stimulated hypertrophy in cultured neonatal rat ventricular myocytes (Hilal-Dandan et al, 1997). Similarly, sphingosylphosphorylcholine (SPC) induced cardiomyocyte hypertrophy is attenuated by pertussis toxin treatment (Sekiguchi et al, 1999).…”