Disruption of endothelial-cell caveolin-1alpha/raft scaffolding during development of monocrotaline-induced pulmonary hypertension.
BACKGROUND
In the monocrotaline (MCT)-treated rat, there is marked stimulation of DNA synthesis and megalocytosis of pulmonary arterial endothelial cells (PAECs) within 3 to 4 days, followed by pulmonary hypertension (PH) 10 to 14 days later. Growing evidence implicates caveolin-1 (cav-1) in plasma membrane rafts as a negative regulator of promitogenic signaling. We have investigated the integrity and function of endothelial cell-selective cav-1alpha/raft signaling in MCT-induced PH.


RESULTS
Although PH and right ventricular hypertrophy developed by 2 weeks after MCT, a reduction in cav-1alpha levels in the lung was apparent within 48 hours, declining to approximately 30% by 2 weeks, accompanied by an increase in activation of the promitogenic transcription factor STAT3 (PY-STAT3). Immunofluorescence studies showed a selective loss of cav-1alpha and platelet endothelial cell adhesion molecule-1 in the PAEC layer within 48 hours after MCT but an increase in PY-STAT3. PAECs with cav-1alpha loss displayed high PY-STAT3 and nuclear immunostaining for proliferating cell nuclear antigen (PCNA). Biochemical studies showed a loss of cav-1alpha from the detergent-resistant lipid raft fraction concomitant with hyperactivation of STAT3. Moreover, cultured PAECs treated with MCT-pyrrole for 48 hours developed megalocytosis associated with hypo-oligomerization and reduction of cav-1alpha, hyperactivation of STAT3 and ERK1/2 signaling, and stimulation of DNA synthesis.


CONCLUSIONS
MCT-induced disruption of cav-1alpha chaperone and scaffolding function in PAECs likely accounts for diverse alterations in endothelial cell signaling in this model of PH.
Mathew
Rajamma
R
Department of Pediatrics, New York Medical College, Valhalla, NY 10595, USA.
Huang
Jing
J
Shah
Mehul
M
Patel
Kirit
K
Gewitz
Michael
M
Sehgal
Pravin B
PB
D000818:Animals; D051242:Caveolin 1; D022461:Caveolins / Q000172:deficiency / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000032:analysis / Q000737:chemistry; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000378:metabolism / Q000648:ultrastructure*; D004730:Endothelium, Vascular / Q000473:pathology*; D006360:Heat-Shock Proteins / Q000032:analysis; D006976:Hypertension, Pulmonary / Q000139:chemically induced / Q000150:complications / Q000378:metabolism* / Q000473:pathology; D017380:Hypertrophy, Right Ventricular / Q000209:etiology; D007535:Isomerases / Q000032:analysis; D008297:Male; D021962:Membrane Microdomains / Q000502:physiology*; D008938:Mitosis; D016686:Monocrotaline / Q000031:analogs & derivatives* / Q000633:toxicity; D010766:Phosphorylation; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000032:analysis; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis; D019704:Protein Disulfide-Isomerases; D011499:Protein Processing, Post-Translational; D011651:Pulmonary Artery / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D050796:STAT3 Transcription Factor; D015534:Trans-Activators / Q000032:analysis / Q000737:chemistry; D014841:von Willebrand Factor / Q000032:analysis
C495537:Cav1 protein, rat; D051242:Caveolin 1; D022461:Caveolins; D004268:DNA-Binding Proteins; D006360:Heat-Shock Proteins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D018809:Proliferating Cell Nuclear Antigen; D050796:STAT3 Transcription Factor; C494088:Stat3 protein, rat; D015534:Trans-Activators; D014841:von Willebrand Factor; C014114:monocrotaline pyrrole; D016686:Monocrotaline; D007535:Isomerases; C513196:PDIA3 protein, rat; D019704:Protein Disulfide-Isomerases