scholarly journals Truncated IRAG variants modulate cGMP-mediated inhibition of human colonic smooth muscle cell contraction

2011 ◽  
Vol 301 (6) ◽  
pp. C1445-C1457 ◽  
Author(s):  
Alexander von Werder ◽  
Martina Mayr ◽  
Günter Schneider ◽  
Daniela Oesterle ◽  
Ralph M. Fritsch ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Alternative Splicing ◽  
Smooth Muscle Cells ◽  
Single Gene ◽  
Muscle Cells ◽  
Acceptor Site ◽  
Human Tissues ◽  
Mrna Isoforms ◽  
Donor And Acceptor

Nitric oxide (NO) induces relaxation of colonic smooth muscle cells predominantly by cGMP/cGMP-dependent protein kinase I (cGKI)-induced phosphorylation of the inositol 1,4,5-trisphosphate receptor (IP3R)-associated cGMP kinase substrate (IRAG), to block store-dependent calcium signaling. In the present study we analyzed the structure and function of the human IRAG/MRVI1 gene. We describe four unique first exon variants transcribed from individual promoters in diverse human tissues. Tissue-specific alternative splicing with exon skipping and alternative splice donor and acceptor site usage further increases diversity of IRAG mRNA variants that encode for NH2- and COOH-terminally truncated proteins. At the functional level, COOH-terminally truncated IRAG variants lacking both the cGKI phosphorylation and the IP3RI interaction site counteract cGMP-mediated inhibition of calcium transients and relaxation of human colonic smooth muscle cells. Since COOH-terminally truncated IRAG mRNA isoforms are widely expressed in human tissues, our results point to an important role of IRAG variants as negative modulators of nitric oxide/cGKI-dependent signaling. The complexity of alternative splicing of the IRAG gene impressively demonstrates how posttranscriptional processing generates functionally distinct proteins from a single gene.

Thrombin Prevents the Expression of Inducible Nitric Oxide Synthase in Vascular Smooth Muscle Cells by a Proteolytically-Activated Thrombin Receptor

1995 ◽  
Vol 74 (03) ◽  
pp. 980-986 ◽  
Author(s):  
Valérie B Schini-Kerth ◽  
Beate Fißithaler ◽  
Thomas T Andersen ◽  
John W Fenton ◽  
Paul M Vanhoutte ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Inducible Nitric Oxide Synthase ◽  
Muscle Cells ◽  
Thrombin Receptor ◽  
Oxide Synthase ◽  
Inducible Nitric Oxide

SummaryProteolytically active forms of thrombin (α- and γ-thrombin) and thrombin receptor peptides inhibited the release of nitrite, a stable endproduct of nitric oxide, evoked by interleukin-1 β(IL-1 β) in cultured vascular smooth muscle cells while proteolytically inactive forms [D-Phe-Pro-Arg chloromethyl ketone-α-thrombin (PPACK-α- thrombin) and diisopropylphosphoryl-α-thrombin (DIP-α-thrombin)] had either no or only minimal inhibitory effects. Under bioassay conditions, perfusates from columns containing IL-1 β-activated vascular smooth muscle cells or cells treated with IL-1βplus PPACK-α-thrombin relaxed detector blood vessels. These relaxations were abolished by the inhibitor of nitric oxide synthesis, NG-nitro-L arginine. No relaxations were obtained with untreated cells or IL-1 β-treated cells in the presence of α-thrombin. The expression of inducible nitric oxide synthase mRNA and protein in vascular smooth muscle cells by IL-1 β was impaired by α-thrombin. These results demonstrate that thrombin regulates the expression of the inducible nitric oxide synthase at a transcriptional level via the proteolytic activation of the thrombin receptor in vascular smooth muscle cells

Nitric oxide selectively amplifies FGF-2-induced mitogenesis in primary rat aortic smooth muscle cells

1994 ◽  
Vol 267 (3) ◽  
pp. H1040-H1048 ◽  
Author(s):  
A. Hassid ◽  
H. Arabshahi ◽  
T. Bourcier ◽  
G. S. Dhaunsi ◽  
C. Matthews
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Growth Factor ◽  
Smooth Muscle Cells ◽  
Fibroblast Growth Factor ◽  
Thymidine Incorporation ◽  
Muscle Cells ◽  
Fibroblast Growth ◽  
Aortic Smooth Muscle

Fibroblast growth factor is present in blood vessels and is thought to play an important role in promoting vascular cell proliferation in vivo. In the current study, we show that three agents that activate the guanosine 3',5'-cyclic monophosphate (cGMP) system, including the nitric oxide-generating agents S-nitroso-N-acetylpenicillamine (SNAP) and 3-morpholinosydnonimine-N-ethylcarbamide (SIN-1) as well as the stable cGMP analogue 8-bromo-cGMP, increased fibroblast growth factor-2 (FGF-2; basic fibroblast growth factor)-induced [3H]thymidine incorporation by severalfold in primary cultures of rat aortic smooth muscle cells. SNAP increased the efficacy, but not the potency, of FGF-2. The stimulatory effect of SNAP was selective for FGF-2-induced mitogenesis as shown by the lack of a significant effect on [3H]thymidine incorporation induced by several other growth factors. Consistent with thymidine incorporation experiments, SNAP amplified the increase of the cellular DNA content induced by FGF-2 as well as the proliferation of cells. A selective inhibitor of cGMP phosphodiesterases, zaprinast, potentiated the comitogenic effect of SNAP and its ability to increase cGMP levels, supporting the involvement of cGMP as second messenger. Consistent with previous results, and opposite to that found in primary and early subculture, SNAP decreased mitogen-induced [3H]thymidine incorporation in cells in later subculture. Because macrophage- and vascular smooth muscle-derived nitric oxide is likely to be present in relatively large concentrations after vascular injury, we speculate that endogenous nitric oxide may amplify the activity of FGF-2 in vivo.

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