Dataset Information

Smooth muscle proliferation and role of the prostacyclin (IP) receptor in idiopathic pulmonary arterial hypertension.

ABSTRACT:

Rationale

Prostacyclin analogs, used to treat idiopathic pulmonary arterial hypertension (IPAH), are assumed to work through prostacyclin (IP) receptors linked to cyclic AMP (cAMP) generation, although the potential to signal through peroxisome proliferator-activated receptor-? (PPAR?) exists.

Objectives

IP receptor and PPAR? expression may be depressed in IPAH. We wished to determine if pathways remain functional and if analogs continue to inhibit smooth muscle proliferation.

Methods

We used Western blotting to determine IP receptor expression in peripheral pulmonary arterial smooth muscle cells (PASMCs) from normal and IPAH lungs and immunohistochemistry to evaluate IP receptor and PPAR? expression in distal arteries.

Measurements and main results

Cell proliferation and cAMP assays assessed analog responses in human and mouse PASMCs and HEK-293 cells. Proliferative rates of IPAH cells were greater than normal human PASMCs. IP receptor protein levels were lower in PASMCs from patients with IPAH, but treprostinil reduced replication and treprostinil-induced cAMP elevation appeared normal. Responses to prostacyclin analogs were largely dependent on the IP receptor and cAMP in normal PASMCs, although in IP(-/-) receptor cells analogs inhibited growth in a cAMP-independent, PPAR?-dependent manner. In IPAH cells, antiproliferative responses to analogs were insensitive to IP receptor or adenylyl cyclase antagonists but were potentiated by a PPAR? agonist and inhibited (? 60%) by the PPAR? antagonist GW9662. This coincided with increased PPAR? expression in the medial layer of acinar arteries.

Conclusions

The antiproliferative effects of prostacyclin analogs are preserved in IPAH despite IP receptor down-regulation and abnormal coupling. PPAR? may represent a previously unrecognized pathway by which these agents inhibit smooth muscle proliferation.

SUBMITTER: Falcetti E

PROVIDER: S-EPMC3001258 | biostudies-literature | 2010 Nov

REPOSITORIES: biostudies-literature

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Publications

Smooth muscle proliferation and role of the prostacyclin (IP) receptor in idiopathic pulmonary arterial hypertension.

Falcetti Emilia E Hall Susan M SM Phillips Peter G PG Patel Jigisha J Morrell Nicholas W NW Haworth Sheila G SG Clapp Lucie H LH

American journal of respiratory and critical care medicine 20100709 9

<h4>Rationale</h4>Prostacyclin analogs, used to treat idiopathic pulmonary arterial hypertension (IPAH), are assumed to work through prostacyclin (IP) receptors linked to cyclic AMP (cAMP) generation, although the potential to signal through peroxisome proliferator-activated receptor-γ (PPARγ) exists.<h4>Objectives</h4>IP receptor and PPARγ expression may be depressed in IPAH. We wished to determine if pathways remain functional and if analogs continue to inhibit smooth muscle proliferation.<h4> ...[more]

PMID: 20622039

Similar Datasets

Project description:RationalePulmonary arterial hypertension (PAH) is a rare progressive pulmonary vascular disorder associated with vascular remodeling and right heart failure. Vascular remodeling involves numerous signaling cascades governing pulmonary arterial smooth muscle cell (PASMC) proliferation, migration and differentiation. Glycogen synthase kinase 3beta (GSK3ß) is a serine/threonine kinase and can act as a downstream regulatory switch for numerous signaling pathways. Hence, we hypothesized that GSK3ß plays a crucial role in pulmonary vascular remodeling.MethodsAll experiments were done with lung tissue or isolated PASMCs in a well-established monocrotaline (MCT)-induced PAH rat model. The mRNA expression of Wnt ligands (Wnt1, Wnt3a, Wnt5a), upstream Wnt signaling regulator genes (Frizzled Receptors 1, 2 and secreted Frizzled related protein sFRP-1) and canonical Wnt intracellular effectors (GSK3ß, Axin1) were assessed by real-time polymerase chain reaction and protein levels of GSK3ß, phospho-GSK3ß (ser 9) by western blotting and localization by immunohistochemistry. The role of GSK3ß in PASMCs proliferation was assessed by overexpression of wild-type GSK3ß (WT) and constitutively active GSK3ß S9A by [(3)H]-thymidine incorporation assay.ResultsIncreased levels of total and phosphorylated GSK3ß (inhibitory phosphorylation) were observed in lungs and PASMCs isolated from MCT-induced PAH rats compared to controls. Further, stimulation of MCT-PASMCs with growth factors induced GSK3ß inactivation. Most importantly, treatment with the PDGFR inhibitor, Imatinib, attenuated PDGF-BB and FCS induced GSK3ß phosphorylation. Increased expression of GSK3ß observed in lungs and PASMC isolated from MCT-induced PAH rats was confirmed to be clinically relevant as the same observation was identified in human iPAH lung explants. Overexpression of GSK3ß significantly increased MCT-PASMCs proliferation by regulating ERK phosphorylation. Constitutive activation of GSK3ß (GSK3ß S9A, 9th serine replaced to alanine) inhibited MCT-PASMCs proliferation by decreasing ERK phosphorylation.ConclusionThis study supports a central role for GSK3ß in vascular remodeling processes and suggests a novel therapeutic opportunity for the treatment of PAH.

Dataset Information

Smooth muscle proliferation and role of the prostacyclin (IP) receptor in idiopathic pulmonary arterial hypertension.

Rationale

Objectives

Methods

Measurements and main results

Conclusions

Publications

Smooth muscle proliferation and role of the prostacyclin (IP) receptor in idiopathic pulmonary arterial hypertension.

Similar Datasets

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