Lung remodeling and pulmonary hypertension after myocardial infarction: pathogenic role of reduced caveolin expression.
OBJECTIVE
Pulmonary hypertension (PH) and lung structural remodeling are frequent complications of congestive heart failure (CHF). Yet, the molecular mechanisms involved in CHF-induced PH and lung remodeling remain unknown. Caveolins (Cav-1, -2 and -3) are the principal structural proteins of the vesicular invaginations of the plasma membrane, termed caveolae. Mice with homozygous deletion of the caveolin-1 gene (Cav-1(-/-)) have been shown to develop dilated cardiomyopathy, PH and lung structural remodeling, characterized by hypercellularity and thickening of the alveolar septa. However, the physiological relevance of these observations for the pathogenesis of PH and lung remodeling remains to be determined.


RESULTS
Here, we investigate the natural behavior of the endogenous caveolin proteins during the development of PH and lung structural remodeling, using a rat model of myocardial infarction (MI). MI was induced in male Wistar rats by ligating the left anterior coronary artery. Two weeks post-MI, rats were anesthetized and hemodynamic and morphometric measurements were obtained. Rats subjected to MI developed marked PH, lung structural remodeling and right ventricular hypertrophy (RVH). Both immunoblot analysis and immunohistochemistry dramatically show that Cav-1 and Cav-2 expression is downregulated to almost undetectable levels in the lungs of post-MI rats. Mechanistically, the reduced expression of caveolins was associated with the increased tyrosine-phosphorylation of the signal transducer and activator of transcription-3 (STAT3) and the upregulation of cyclin D1 and D3 expression. We also show that STAT3 is hyperphosphorylated, and cyclin D1 and D3 levels are dramatically upregulated, in lung tissue samples derived from Cav-1 (-/-)- and Cav-2 (-/-)-deficient mice.


CONCLUSIONS
Thus, down-modulation of pulmonary Cav-1 and Cav-2 expression in rats subjected to MI may represent an initiating mechanism leading to the activation of the STAT3/Cyclins pathway and, ultimately, to the development of PH and lung structural remodeling.
Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
Jean-François
JF
Jasmin
Isabelle
I
Mercier
Robert
R
Hnasko
Michelle W-C
MW
Cheung
Herbert B
HB
Tanowitz
Jocelyn
J
Dupuis
Michael P
MP
Lisanti
D000818:Animals; D051242:Caveolin 1; D051243:Caveolin 2; D051244:Caveolin 3; D022461:Caveolins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D019938:Cyclin D1 / Q000032:analysis; D056743:Cyclin D3; D016213:Cyclins / Q000032:analysis; D004268:DNA-Binding Proteins / Q000032:analysis / Q000378:metabolism; D006976:Hypertension, Pulmonary / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D015151:Immunoblotting / Q000379:methods; D007150:Immunohistochemistry / Q000379:methods; D008168:Lung / Q000737:chemistry / Q000473:pathology*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D023421:Models, Animal; D009203:Myocardial Infarction / Q000150:complications* / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D050796:STAT3 Transcription Factor; D015398:Signal Transduction / Q000502:physiology*; D015534:Trans-Activators / Q000032:analysis / Q000378:metabolism
C495541:Cav1 protein, mouse; C495537:Cav1 protein, rat; C495548:Cav3 protein, mouse; C495549:Cav3 protein, rat; D051242:Caveolin 1; D051243:Caveolin 2; D051244:Caveolin 3; D022461:Caveolins; C534697:Ccnd3 protein, mouse; C534698:Ccnd3 protein, rat; D056743:Cyclin D3; D016213:Cyclins; D004268:DNA-Binding Proteins; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; C494088:Stat3 protein, rat; D015534:Trans-Activators; D019938:Cyclin D1