Submitted on February 3, 2006
Accepted on December 17, 2007
IL-1
, BK and TGF-1 attenuate PGI2 mediated cAMP formation in human pulmonary artery smooth muscle cells by multiple mechanisms involving p38 MAPK and PKA
Hala El-Haroun1, Deborah L Clarke1, Karl Deacon1, Dawn Bradbury1, Andrew Clayton1, Amy M Sutcliffe2, and Alan J. Knox1*
1 Respiratory Medicine, The University of Nottingham, Nottingham, United Kingdom
2 Respiratory Medicine, University of Nottingham, Nottingham, United Kingdom
* To whom correspondence should be addressed. E-mail: alan.knox{at}nottingham.ac.uk.
We have previously shown that interleukin (IL)-1
, transforming growth factor (TGF)-1 or bradykinin (BK) impair cAMP generation in response to prostacyclin analogues in human pulmonary artery smooth muscle (PASM) suggesting that inflammation can impair the effects of prostacyclin analogues on PASM in pulmonary hypertension. Here we explored the biochemical mechanisms involved. We found that IL-1, BK and TGF-1 reduced adenylyl cyclase isoform 1, 2 and 4 mRNA, increased G
i protein levels and reduced IP receptor mRNA expression. In contrast, Gs protein levels were unchanged. Protein kinase A (PKA) (H-89, KT5720, PKIm) and p38 mitogen activated protein (MAP) kinase (SB202190) inhibitors attenuated these effects but protein kinase C (PKC) (BIS) or phosphoinositol 3 (PI3) kinase (LY294002) inhibitors did not. Fluorescent kemptide assay and western blotting confirmed that PKA and p38 MAP kinase were activated by IL-1, BK and TGF-1. These studies suggest that IL-1, BK and TGF-1 impair IP receptor mediated cAMP accumulation by multiple effects on different components of the signalling pathway and that these effects are PKA and p38 MAP kinase dependent.
