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Cardiovascular Research 2004 63(4):747-755; doi:10.1016/j.cardiores.2004.05.018
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Copyright © 2004, European Society of Cardiology

Lung remodeling and pulmonary hypertension after myocardial infarction: pathogenic role of reduced caveolin expression

Jean-François Jasmina, Isabelle Mercierb, Robert Hnaskoa, Michelle W.-C Cheunga, Herbert B Tanowitzc, Jocelyn Dupuisd and Michael P Lisanti*,a

aDepartment of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
bDepartment of Molecular Cardiology, Albert Einstein College of Medicine, Bronx, NY, USA
cDepartments of Pathology and Medicine, Albert Einstein College of Medicine, Bronx, NY, USA
dDepartment of Medicine, Montreal Heart Institute, Montreal, Canada

* Corresponding author. Tel.: +1-718-430-8828; fax: 1-718-430-8830. Email address: lisanti{at}aecom.yu.edu

Received 26 February 2004; revised 30 April 2004; accepted 13 May 2004


   Abstract
Top
 Abstract
1. Methods
 2. Results
 3. Discussion
 4. Conclusions
 References
 
Objectives: 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. Methods and 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.

KEYWORDS Caveolin proteins; Pulmonary hypertension; Lung remodeling; Cyclins; Myocardial infarction

Congestive heart failure (CHF) leads to an increase in left ventricular filling pressures with subsequent congestion of the pulmonary venous circulation. Hence, secondary pulmonary hypertension (PH) is a frequent complication of CHF [1]. Right ventricular systolic function and pulmonary artery pressure have even been identified as independent prognostic factors in patients with CHF [2]. Moreover, PH has been shown to be a predictor of mortality and morbidity in patients with dilated cardiomyopathy [3]. Furthermore, important lung structural remodeling secondary to CHF has previously been described [4,5]. Indeed, structural remodeling of the lungs, as evidenced by collagen and reticulin deposition, thickening of the alveolar septa and proliferation of myofibroblasts has recently been demonstrated in the rat model of myocardial infarction (MI) [4]. However, the molecular mechanisms involved in CHF-induced PH and lung structural remodeling remain unknown.

Caveolae are 50–100 nm vesicular invaginations of the plasma membrane which play a key role in endocytosis, vesicular trafficking and signal transduction [6–9]. Caveolins (Cavs) represents the principal structural proteins of caveolar membranes [10,11]. The caveolin gene family consists of three distinct genes, namely Cav-1, -2 and -3 [10,12,13]. Cav-1 and -2 are co-expressed in several tissues and are particularly abundant in adipocytes, endothelial cells, epithelial cells, smooth muscle cells and fibroblasts [12,14]. Cav-3, on the other hand, is muscle-specific and is highly expressed in skeletal muscle, cardiac muscle and smooth muscle cells [13,15].

Interestingly, the caveolin proteins have recently been suggested as key regulators in the development of cardiomyopathy, PH and structural remodeling of the lungs [16–18]. Indeed, Cav-1 (–/–)-deficient mice have been shown to develop dilated cardiomyopathy, PH and right ventricular hypertrophy (RVH) [18]. Structural remodeling of the lungs, as demonstrated by hypercellularity and thickening of the alveolar septa, has also been described in Cav-1 (–/–) null mice [16]. However, since Cav-1 null mice also have a near complete ablation of Cav-2 expression, the functional implications of Cav-1 in the development of cardiomyopathy, PH and lung structural remodeling is unclear. Therefore, a Cav-2 (–/–)-deficient mouse was recently generated and showed the same severe pulmonary dysfunction as Cav-1 (–/–)-deficient mice, without defects in caveolar formation and Cav-1 expression, thus, suggesting a selective role for Cav-2 in lung function [17]. Although the pulmonary phenotypes of Cav-1- and Cav-2-deficient mice are now well described, it remains unknown whether the downregulation of caveolins occurs naturally during CHF-induced PH and lung structural remodeling.

Association of caveolins with the signal transducer and activator of transcription (STAT) proteins has previously been described [19,20]. Interestingly, hyperactivation of the Janus Kinase (JAK)/STAT signaling cascade has previously been demonstrated in the mammary glands of Cav-1 (–/–)-deficient mice [20]. Furthermore, Cav-1 has been shown to repress the expression of cyclin D1 [21]. Interestingly, an upregulation of cyclin D1 expression has been described in Cav-1 (–/–)-deficient mice [22]. Thus, down-modulation of caveolin expression could lead to hyperactivation of PY-STAT3 and an upregulation of the cyclins and, ultimately, to the development of lung structural remodeling and PH. Therefore, this study was designed to better define the role of caveolin proteins, as well as the molecular mechanisms involved in the development of PH and lung structural remodeling, by using the rat model of myocardial infarction.


   1. Methods
Top
 Abstract
 1. Methods
2. Results
 3. Discussion
 4. Conclusions
 References
 
1.1. Animal studies
This study was conducted according to the guidelines of the National Institute of Health and the Canadian council for the care of laboratory animals. Cav-1 (–/–)- and Cav-2 (–/–)-deficient mice were generated, as we previously described [16,17]. Caveolin-deficient mice were housed in a barrier facility at the Albert Einstein College of Medicine.

1.2. Materials
Caveolin-1, -2 and -3 monoclonal antibodies (mAbs) were the generous gifts of Dr. Roberto Campos-Gonzalez (BD Pharmingen) [14,15,23]. Antibodies to STAT3 and to phospho-tyrosine (PY)-STAT3, as well as horseradish peroxidase (HRP)-conjugated secondary antibodies, were purchased from BD Pharmingen. Rabbit polyclonal antibodies (pAbs) to cyclin D1 and cyclin D3 were purchased from Santa Cruz Biotechnology. A mouse mAb to β-actin was purchased from Sigma-Aldrich.

1.3. Surgical procedures
Myocardial infarction was induced in male Wistar rats (Charles River) weighing between 200 and 250 g, by ligating the left anterior descending coronary artery, as previously described in detail [4]. The sham group was subjected to the exact same procedure, except for the ligation of the coronary artery. To maximize the likelihood of severe PH and lung structural remodeling, only the animals with large MIs were included in this study. The presence of a large MI was defined as a scar/body weight ratio >0.030%. This resulted in two groups: sham (n=6) and MI (n=6).

Two weeks post-MI, rats were anesthetized with xylazine (10 mg/kg)–ketamine (50 mg/kg), and hemodynamic measurements were obtained as previously described [4]. The lower lobe of the right lung and the heart were dissected and weighted to respectively determine pulmonary edema and right ventricular hypertrophy [4]. The upper and median lobes of the right lung were submerged in liquid nitrogen and frozen at –80 °C.

1.4. Immunoblot analysis
Immunoblot analyses were used to investigate the pulmonary expression of Cav-1, Cav-2, Cav-3, STAT3, PY-STAT3, cyclin D1 and cyclin D3. Lungs samples from sham rats (n=6), MI rats (n=6), Cav-1 (–/–)-deficient mice (n=5) and Cav-2 (–/–)-deficient mice (n=5) were homogenized in lysis buffer (RIPA: 50 mM HEPES, 50 mM NaCl, 0.1% SDS, 1% NP-40, 2 mM EGTA, 1 mM PMSF, 5 µg/ml leupeptin, 10 µg/ml aprotinin) containing protease inhibitors. The lysates were then centrifuged at 12,000 x g for 10 min in order to remove the insoluble debris. The BCA reagent (Pierce) was subsequently used to determine the protein concentration of each sample, as well as the volume required for 50 µg of protein. These samples were then separated by SDS-PAGE (12% acrylamide) and transferred to nitrocellulose membranes. The membranes were first stained with Ponceau S and then placed in blocking solution for 30 min. Afterwards, the membranes were washed with 10 mM Tris (pH 8.0), 150 mM NaCl and 0.05% Tween 20 (1 x -TBS-Tween) and incubated with a given primary antibody for 1 h (Cav-1, -2, -3 and β-actin) or 3 h (STAT3, PY-STAT3, cyclin D1 and cyclin D3). Primary antibodies were used at the following dilutions: Cav-1 mAb (1:2000), Cav-2 mAb (1:1000), Cav-3 mAb (1:400), β-actin mAb (1:10000), STAT3 pAb (1:1000), PY-STAT3 pAb (1:1000), cyclin D1 pAb (1:500) and cyclin D3 pAb (1:500). Finally, HRP-conjugated secondary antibodies were used to detect bound primary antibody using the SuperSignal chemiluminescence substrate (Pierce). Western blots for Cav-1, Cav-2, Cav-3, PY-STAT3, cyclin D1 and cyclin D3 were subsequently quantitated using NIH Image J software (using the mean gray value of each band).

1.5. Immunohistochemistry
Immunohistochemistry was used to investigate the expression and localization of Cav-1 and Cav-2 in the alveolar septa. A barium-gelatin mixture (60 °C) was perfused into the left pulmonary artery of both sham and MI rats at a pressure of 50 cm H2O for 2 min. The airways were then perfused with a formalin fixative solution (Sigma) at a pressure of 36 cm H2O for 2 min. The left lung was dissected and immersed in formalin for 24 h. Three transverse sections at three different levels were obtained and embedded with paraffin. Sections of 10 µm were cut and stained with hematoxylin and eosin (H&E).

Paraffin from 10-µm-thick sections was removed by immersion in xylene. These sections were then rehydrated with graded alcohol to water and blocked overnight using HenBLKII (1:5 in PBS, Aves Lab). These sections were subsequently incubated with the primary antibody for 1 h. The primary antibodies were used at the following dilutions: Cav-1 mAb (1:500) and Cav-2 mAb (1:500). An HRP-conjugated secondary antibody (goat-anti-mouse IgG (1:1000)) was added to the sections after a 15-min wash in PBS. After 30 min of incubation with the secondary antibody, the sections were washed in PBS for another 15 min. The HRP substrate, diaminobenzidine (DAB), was then added for 1 min and counterstaining was performed using hematoxylin.

1.6. Statistical analysis
Hemodynamic and morphologic variables as well as the mean gray value of each Western blot are expressed as mean±standard deviations and the differences between groups were evaluated by a two-tailed Student's t-test. Statistical significance was assumed at p<0.05.


   2. Results
Top
 Abstract
 1. Methods
 2. Results
3. Discussion
 4. Conclusions
 References
 
2.1. Hemodynamic and morphologic alterations in MI rats
Rats subjected to MI developed left ventricular dysfunction as shown by an increase in the left ventricular end-diastolic pressure (LVEDP) and a decrease in the indices of left ventricular contractility and relaxation ((+)LV dP/dt and (–)LV dP/dt) (Table 1). The post-MI rats also developed marked PH and RVH as respectively shown by increases in right ventricular systolic pressure (RVSP) and in the RV/LV+septum weight ratios (Fig. 1). The lung weight of MI rats was approximately double in the absence of significant edema formation (Table 1). All other hemodynamic and morphometric variables are summarized in Table 1.


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  		Table 1 Hemodynamic and morphometric variables

 

Figure 1
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  		Fig. 1 MI rats develop marked pulmonary hypertension and right ventricular hypertrophy, as shown by increases in the right ventricular systolic pressures (A) and in the right ventricle (RV)/left ventricle (LV)+septum weight ratios (B). Asterisks indicate statistical significance p<0.05 vs. sham group, using a two-tailed Student's t-test.

 
2.2. Decreased expression of caveolin proteins in the lungs of MI rats
Alterations in total lung caveolin expression were first investigated in both sham and MI rats. As demonstrated in Fig. 2, immunoblot analyses showed marked decreases in both Cav-1 (~16-fold, p<0.05) and Cav-2 (~4.5-fold, p<0.05) protein expression, while Cav-3 expression remain unchanged in the lungs of rats subjected to MI. Immunoblotting with β-actin is shown as a control for equal protein loading.


Figure 2
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  		Fig. 2 Western blot analysis of MI rat lungs shows decreased expression of both caveolin-1 (A) and caveolin-2 (B), while the expression of Cav-3 remains unchanged (C) (two of six rats are shown for each group). Quantitation is shown in panels (D), (E) and (F). Immunoblotting with β-actin is shown as a control for equal protein loading. An asterisk (*) indicates statistical significance (p<0.05 vs. sham; n=6 for each group).

 
As previously described [4], H&E staining of lungs sections showed important structural remodeling characterized by thickening of the alveolar septa and hypercellularity in the post-MI group (Fig. 3A–B). Interestingly, this lung structural remodeling is clearly associated with marked decreases in Cav-1 and Cav-2 protein expression (Fig. 3C–F), as seen by immuno-staining.


Figure 3
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  		Fig. 3 Hematoxylin and eosin staining of the lungs of sham (A) and MI (B) rats demonstrates clear lung structural remodeling, characterized by hypercellularity and thickened alveolar septa in the MI group. This lung structural remodeling was associated with decreased expression of Cav-1 and Cav-2. Panels (C) and (D) represent immunostaining of caveolin-1 in lungs of sham and MI rats, respectively. Panels (E) and (F) represent immunostaining of caveolin-2 in lungs of sham and MI rats, respectively. All images in A–F were taken at the same magnification of 20 x .

 
2.3. Hyperactivation of the JAK/STAT cascade in the lungs of MI rats
We next evaluated the possible role of JAK/STAT pathway activation in sham and post-MI rat lungs. As predicted, immunoblot analysis showed increased levels of PY-STAT3 in the lungs of rats subjected to MI (~60-fold, p<0.05), while no differences were observed in the expression of total STAT3 (Fig. 4).


Figure 4
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  		Fig. 4 Western blot analysis of MI rat lungs shows increased activation of phospho-STAT3 (PY-STAT3), while no differences were observed in total STAT3 (A). Quantitation is show in panel (B). An asterisk (*) indicates statistical significance (p<0.05 vs. sham; n=6 for each group).

 
2.4. Upregulation of cyclin D1 and D3 expression in the lungs of MI rats
Immunoblot analysis of rat lungs dramatically demonstrated the increased expression of cyclin D1 and cyclin D3 in the post-MI rats (Fig. 5A). Quantitation is presented in Fig. 5B. Immunoblotting with β-actin is also shown as a control for equal protein loading.


Figure 5
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  		Fig. 5 Western blot analysis of post-MI rat lungs shows increased expression of cyclin D1 and cyclin D3 (A). Quantitation is show in panel (B). Immunoblotting with β-actin is shown as a control for equal protein loading. An asterisk (*) indicates statistical significance (p<0.05 vs. sham; n=6 for each group).

 
2.5. Caveolin knockout mice show hyperactivation of JAK/STAT signaling and cyclin D1/D3 upregulation in lung tissue
Immunoblot analysis of lung tissue samples from Cav-1 (–/–)-deficient mice clearly demonstrates the hyperphosphorylation of STAT3 and the increased expression of cyclin D1 and D3 (Fig. 6). Virtually identical results were obtained with Cav-2 (–/–)-deficient mice, strongly implicating the loss of Cav-2 in the dysregulation of these signal transduction events in lung tissue (Fig. 6).


Figure 6
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  		Fig. 6 Western blot analysis of Cav-1 (–/–)- and Cav-2 (–/–)-deficient mouse lungs show the hyperphosphorylation of STAT3 (PY-STAT3), and the upregulation of cyclin D1 and D3 expression (four of five mice are shown for each group). Virtually identical results were obtained with five mice from each group. However, no differences were observed in total STAT3 levels. Immunoblot analysis with anti-Cav-1 and anti-Cav-2 antibodies is also shown to illustrate the loss of caveolin expression in these Cav-1 (–/–) and Cav-2 (–/–) knockout mice. Immunoblotting with β-actin is shown as a control for equal protein loading.

 
Immunoblot analysis with anti-Cav-1 and anti-Cav-2 antibodies is also shown to illustrate the loss of caveolin expression in these Cav-1 and Cav-2 knockout mice. As we have previously shown, Cav-1 (–/–)-deficient mice are also deficient in Cav-2 expression; in contrast, Cav-2 (–/–)-deficient mice continue to express Cav-1, albeit at mildly reduced levels [16,17]. Finally, immunoblotting with β-actin is shown as a control for equal protein loading.


   3. Discussion
Top
 Abstract
 1. Methods
 2. Results
 3. Discussion
4. Conclusions
 References
 
Our present results demonstrate a marked decrease in Cav-1 and -2 expression in the lungs of rats subjected to MI. This decreased expression was associated with hyperactivation of the STAT3 pathway and upregulation of cyclin D1 and D3.

3.1. Decreased expression of Cav-1 and Cav-2 in pulmonary hypertensive rats
Caveolin proteins have recently been suggested as key regulators of the development of PH and lung structural remodeling. Indeed, Cav-1 (–/–) null mice develop dilated cardiomyopathy, PH and RVH [18]. Furthermore, the lungs of Cav-1 (–/–)- and Cav-2 (–/–)-deficient mice show hypercellularity and thickened alveolar septa [16,17]. Although the pulmonary phenotype of the caveolin-deficient mice is now well described, the actual implications of caveolin proteins in the development of PH and lung structural remodeling remain to be clarified.

Two recent studies investigating alterations in nitric oxide production showed conflicting results concerning Cav-1 expression. Indeed, Murata et al. [24] recently reported that there was absolutely no change in caveolin expression in the pulmonary artery isolated from 1-week hypoxia-induced pulmonary hypertensive rats [24]. However, a study of Black et al. [25] showed decreased expression of Cav-1 in the peripheral lung tissue of 8-week-old lambs subjected to aortopulmonary vascular graft placement [25]. In order to clarify this issue, we investigated the expression of caveolin proteins in the lungs of rats with MI-induced secondary PH.

The MI rat model is the most frequently used model of CHF and its relevance to human CHF and secondary PH has been clearly demonstrated [4]. In this model of secondary PH, we demonstrate marked decreases in both Cav-1 and -2 expression, while Cav-3 expression remain unchanged in the lungs of rats subjected to MI. Since Cav-3 is a muscle-specific isoform, it is not surprising to find that its pulmonary expression remained the same after an MI. Indeed, as previously described [4], the structural remodeling present in this model of PH is mainly localized to the alveolar septa.

Our present results, combined with the pulmonary phenotype of Cav-1 (–/–)- and Cav-2 (–/–)-deficient mice, strongly suggest that Cav-1 and Cav-2 proteins are key physiologically-relevant regulators in the development of PH and lung structural remodeling. The exact mechanism(s) leading to decreased expression of these caveolin proteins in the lungs of pulmonary hypertensive rats still remains unknown. Hypoxia and elevated catecholamines could play an important role in such a decrease, since they have both been associated with the downregulation of caveolin expression in the heart [26,27].

3.2. Hyperactivation of the STAT3 signaling cascade in pulmonary hypertensive rats
Activation of cardiac STAT3 following MI in rats has previously been described [28]. Whether pulmonary STAT3 is activated following an MI is however unknown. We thus investigated the activation of pulmonary STAT3 in the MI rat model. Our present results demonstrate the dramatic hyperactivation of STAT3 in the lungs of rats subjected to an MI. Interestingly, the JAK/STAT signaling proteins have previously been shown to be localized in endothelial caveolae [29]. Moreover, Cav-1 has been reported to negatively regulate the phosphorylation of STAT5a in mammary epithelial cells [20]. Furthermore, hyperactivation of the Jak/STAT signaling cascade has been described in the mammary glands of Cav-1 (–/–)-deficient mice [20]. The modulation of caveolin expression in the lungs of MI rats could thus be responsible for the hyperactivation of STAT3 signaling cascade. This is strongly supported by our observation of increased PY-STAT3 levels in the lungs of Cav-1 (–/–)- and -2 (–/–)-deficient mice. Our present results suggest that the down-modulation of Cav-1 and Cav-2 expression may represent an initiating mechanism, leading to lung structural remodeling and PH in rats subjected to an MI.

3.3. Upregulation of cyclin D1 and D3 expression in pulmonary hypertensive rats
Cav-1 was recently reported to transcriptionally repress the cyclin D1 gene [21]. Furthermore, upregulation of the cyclin D1 expression has been described in the mammary glands of Cav-1 (–/–)-deficient mice [22]. Thus, we investigated if modulation of the caveolin expression could regulate the expression of cyclin D1 and cyclin D3 in the lungs of MI rats. Here, we demonstrate marked increases in pulmonary cyclin D1 and cyclin D3 following an MI. We further demonstrate marked upregulation of pulmonary cyclin D1 and D3 expression in Cav-1 (–/–)- and -2 (–/–)-deficient mice. These observations strongly suggest that modulation of pulmonary Cav-1 and Cav-2 expression could be responsible for the upregulation of cyclins expression. Interestingly, the STAT3 signaling cascade was also recently reported to regulate the expression of cyclin D1 [30]. Indeed, expression of a dominant negative STAT3 construct was demonstrated to inhibit proliferation and cyclin D1 expression in human oncogenic cell lines [30]. The JAK/STAT signaling cascade was also shown to regulate cyclin D3 expression [31]. Inhibitors of JAK, which decrease the phosphorylation of STAT3, have been shown to downregulate cyclin D3 expression in oncogenic cell lines. Modulation of the caveolin/STAT3/cyclins pathway could, thus, represent a new physiologically relevant mechanism for the development of MI-induced lung structural remodeling and PH.

3.4. Clinical relevance and limitations of this study
Down-modulation of caveolin protein expression has been demonstrated in different models of hypertension and hypertrophy. Indeed, decreased expression of Cav-3 has been observed in the hearts of rabbits raised in a hypoxic environment [32]. Both Cav-1 and -3 were decreased in the hypertrophic hearts of perinephritic hypertensive dogs [33]. Furthermore, the expression of Cav-3 was significantly reduced in 6-month-old spontaneously hypertensive rats, compared to age-matched Wistar Kyoto rats [34].

However, the modulation of caveolin protein expression in PH and lung structural remodeling still remained unknown. The present study is the first to describe the down-modulation of Cav-1 and Cav-2 in the rat MI model. Our findings could have implications for the human disease, since that the MI rat model has previously been shown to be relevant to human CHF and secondary PH [4,5]. Thus, caveolin proteins might play a key role in the development of human CHF-induced PH and lung structural remodeling.

However, the present results cannot be generalized to other models of PH. Pulmonary hypertension has recently been divided into five classes consisting of (1) pulmonary arterial hypertension, (2) pulmonary venous hypertension, (3) PH associated with disorders of the respiratory system and/or hypoxemia, (4) PH due to chronic thrombotic and/or embolic disease, and (5) PH due to disorders affecting the pulmonary vasculature. Whereas the MI rat model of PH is a model of pulmonary venous hypertension, other models such as the chronically hypoxic rat or the monocrotaline rat respectively mimic PH associated with hypoxemia and pulmonary arterial hypertension. Thus, it could be possible that different mechanisms may underlie the different types of PH. Indeed, Cav-3 may especially be differentially regulated depending on if there is the presence or not of pulmonary artery medial hypertrophy.


   4. Conclusions
Top
 Abstract
 1. Methods
 2. Results
 3. Discussion
 4. Conclusions
References
 
Both caveolin-1 and caveolin-2 expression levels are significantly decreased in the lungs of rats with myocardial infarction-induced lung structural remodeling and pulmonary hypertension. This decrease in caveolin expression is associated with the hyperactivation of STAT3 signaling and the upregulation of cyclin D1 and cyclin D3 in lung tissue. Lung tissue harvested from Cav-1 (–/–)- and Cav-2 (–/–)-deficient mouse models also showed the hyperphosphorylation of STAT3 and the upregulation of cyclin D1/D3 expression, directly supporting our results from MI rats. Thus, the modulation of caveolin protein expression could represent a novel initiating mechanism, leading to lung structural remodeling and PH in rats subjected to myocardial infarction.


   Acknowledgements
 
This work was supported by grants of the National Institutes of Health (to MPL), the American Heart Association (to MPL), the Canadian Institute of Health Research (to JD) and the Canadian Heart and Stroke Foundation (to JD).

JFJ was supported by fellowship grants from the "Fonds de la Recherche en Santé du Québec" (FRSQ)and the Canadian Heart and Stroke Foundation.


   Notes
 
Time for primary review 22 days


   References
Top
 Abstract
 1. Methods
 2. Results
 3. Discussion
 4. Conclusions
 References
 

  1. Butler J., Chomsky D.B., Wilson J.R. Pulmonary hypertension and exercise intolerance in patients with heart failure. J. Am. Coll. Cardiol. (1999) 34:1802–1806.[Abstract/Free Full Text]
  2. Ghio S., Gavazzi A., Campana C., Inserra C., Klersy C., Sebastiani R., et al. Independent and additive prognostic value of right ventricular systolic function and pulmonary artery pressure in patients with chronic heart failure. J. Am. Coll. Cardiol. (2001) 37:183–188.[Abstract/Free Full Text]
  3. Abramson S.V., Burke J.F., Kelly J.J. Jr., Kitchen J.G. III, Dougherty M.J., Yih D.F., et al. Pulmonary hypertension predicts mortality and morbidity in patients with dilated cardiomyopathy. Ann. Intern. Med. (1992) 116:888–895.[ISI][Medline]
  4. Jasmin J.F., Calderone A., Leung T.K., Villeneuve L., Dupuis J. Lung structural remodeling and pulmonary hypertension after myocardial infarction: complete reversal with irbesartan. Cardiovasc. Res. (2003) 58:621–631.[Abstract/Free Full Text]
  5. Kapanci Y., Burgan S., Pietra G.G., Conne B., Gabbiani G. Modulation of actin isoform expression in alveolar myofibroblasts (contractile interstitial cells) during pulmonary hypertension. Am. J. Pathol. (1990) 136:881–889.[Abstract]
  6. Razani B., Schlegel A., Lisanti M.P. Caveolin proteins in signaling, oncogenic transformation and muscular dystrophy. J. Cell Sci. (2000) 113:2103–2109.[Abstract]
  7. Lisanti M.P., Scherer P.E., Tang Z.L., Sargiacomo M. Caveolae, caveolin and caveolin-rich membrane domains: a signalling hypothesis. Trends Cell Biol. (1994) 4:231–235.[CrossRef][Medline]
  8. Okamoto T., Schlegel A., Scherer P.E., Lisanti M.P. Caveolins, a family of scaffolding proteins for organizing "preassembled signaling complexes" at the plasma membrane. J. Biol. Chem. (1998) 273:5419–5422.[Free Full Text]
  9. Smart E.J., Graf G.A., McNiven M.A., Sessa W.C., Engelman J.A., Scherer P.E., et al. Caveolins, liquid-ordered domains, and signal transduction. Mol. Cell. Biol. (1999) 19:7289–7304.[Free Full Text]
  10. Rothberg K.G., Heuser J.E., Donzell W.C., Ying Y.S., Glenney J.R., Anderson R.G. Caveolin, a protein component of caveolae membrane coats. Cell (1992) 68:673–682.[CrossRef][ISI][Medline]
  11. Glenney J.R., Soppet D. Sequence and expression of caveolin, a protein component of caveolae plasma membrane domains phosphorylated on tyrosine in Rous sarcoma virus-transformed fibroblasts. Proc. Natl. Acad. Sci. (1992) 89:10517–10521.[Abstract/Free Full Text]
  12. Scherer P.E., Okamoto T., Chun M., Nishimoto I., Lodish H.F., Lisanti M.P. Identification, sequence, and expression of caveolin-2 defines a caveolin gene family. Proc. Natl. Acad. Sci. (1996) 93:131–135.[Abstract/Free Full Text]
  13. Tang Z., Scherer P.E., Okamoto T., Song K., Chu C., Kohtz D.S., et al. Molecular cloning of caveolin-3, a novel member of the caveolin gene family expressed predominantly in muscle. J. Biol. Chem. (1996) 271:2255–2261.[Abstract/Free Full Text]
  14. Scherer P.E., Lewis R.Y., Volonte D., Engelman J.A., Galbiati F., Couet J., et al. Cell-type and tissue-specific expression of caveolin-2. Caveolins 1 and 2 co-localize and form a stable hetero-oligomeric complex in vivo. J. Biol. Chem. (1997) 272:29337–29346.[Abstract/Free Full Text]
  15. Song K.S., Li S., Okamoto T., Quilliam L.A., Sargiacomo M., Lisanti M.P. Co-purification and direct interaction of Ras with caveolin, an integral membrane protein of caveolae microdomains. Detergent-free purification of caveolae microdomains. J. Biol. Chem. (1996) 271:9690–9697.[Abstract/Free Full Text]
  16. Razani B., Engelman J.A., Wang X.B., Schubert W., Zhang X.L., Marks C.B., et al. Caveolin-1 null mice are viable but show evidence of hyperproliferative and vascular abnormalities. J. Biol. Chem. (2001) 276:38121–38128.[Abstract/Free Full Text]
  17. Razani B., Wang X.B., Engelman J.A., Battista M., Lagaud G., Zhang X.L., et al. Caveolin-2-deficient mice show evidence of severe pulmonary dysfunction without disruption of caveolae. Mol. Cell. Biol. (2002) 22:2329–2344.[Abstract/Free Full Text]
  18. Zhao Y.Y., Liu Y., Stan R.V., Fan L., Gu Y., Dalton N., et al. Defects in caveolin-1 cause dilated cardiomyopathy and pulmonary hypertension in knockout mice. Proc. Natl. Acad. Sci. (2002) 99:11375–11380.[Abstract/Free Full Text]
  19. Sehgal P.B., Guo G.G., Shah M., Kumar V., Patel K. Cytokine signaling: STATS in plasma membrane rafts. J. Biol. Chem. (2002) 277:12067–12074.[Abstract/Free Full Text]
  20. Park D.S., Lee H., Frank P.G., Razani B., Nguyen A.V., Parlow A.F., et al. Caveolin-1-deficient mice show accelerated mammary gland development during pregnancy, premature lactation, and hyperactivation of the Jak2/STAT5a signaling cascade. Mol. Cell. Biol. (2002) 13:3430.
  21. Hulit J., Bash T., Fu M., Galbiati F., Albanese C., Sage D.R., et al. The cyclin D1 gene is transcriptionally repressed by caveolin-1. J. Biol. Chem. (2000) 275:21203–21209.[Abstract/Free Full Text]
  22. Williams T.M., Cheung M.W., Park D.S., Razani B., Cohen A., Muller W.J., et al. Loss of caveolin-1 gene expression accelerates the development of dysplastic mammary lesions in tumor-prone transgenic mice. Mol. Cell. Biol. (2003) 14:1027–1042.[CrossRef]
  23. Scherer P.E., Tang Z., Chun M., Sargiacomo M., Lodish H.F., Lisanti M.P. Caveolin isoforms differ in their N-terminal protein sequence and subcellular distribution. Identification and epitope mapping of an isoform-specific monoclonal antibody probe. J. Biol. Chem. (1995) 270:16395–16401.[Abstract/Free Full Text]
  24. Murata T., Sato K., Hori M., Ozaki H., Karaki H. Decreased endothelial nitric-oxide synthase (eNOS) activity resulting from abnormal interaction between eNOS and its regulatory proteins in hypoxia-induced pulmonary hypertension. J. Biol. Chem. (2002) 277:44085–44092.[Abstract/Free Full Text]
  25. Black S.M., Bekker J.M., McMullan D.M., Parry A.J., Ovadia B., Reinhartz O., et al. Alterations in nitric oxide production in 8-week-old lambs with increased pulmonary blood flow. Pediatr. Res. (2002) 52:233–244.[CrossRef][ISI][Medline]
  26. Shi Y., Pritchard K.A. Jr., Holman P., Rafiee P., Griffith O.W., Kalyanaraman B., et al. Chronic myocardial hypoxia increases nitric oxide synthase and decreases caveolin-3. Free Radic. Biol. Med. (2000) 29:695–703.[CrossRef][ISI][Medline]
  27. Oka N., Asai K., Kudej R.K., Edwards J.G., Toya Y., Schwencke C., et al. Downregulation of caveolin by chronic beta-adrenergic receptor stimulation in mice. Am. J. Physiol. (1997) 273:C1957–C1962.[ISI][Medline]
  28. Omura T., Yoshiyama M., Ishikura F., Kobayashi H., Takeuchi K., Beppu S., et al. Myocardial ischemia activates the JAK/STAT pathway through angiotensin II signaling in in vivo myocardium of rats. J. Mol. Cell. Cardiol. (2001) 33:307–316.[CrossRef][ISI][Medline]
  29. Ju H., Venema V.J., Liang H., Harris M.B., Zou R., Venema R.C. Bradykinin activates the Janus-activated kinase/signal transducer and activators of transcription (JAK/STAT) pathway in vascular endothelial cells: localization of JAK/STAT signalling proteins in plasmalemmal caveolae. Biochem. J. (2000) 351:257–264.[CrossRef][ISI][Medline]
  30. Masuda M., Suzui M., Yasumatu R., Nakashima T., Kuratomi Y., Azuma K., et al. Constitutive activation of signal transducers and activators of transcription 3 correlates with cyclin D1 overexpression and may provide a novel prognostic marker in head and neck squamous cell carcinoma. Cancer Res. (2002) 62:3351–3355.[Abstract/Free Full Text]
  31. Amin H.M., Medeiros L.J., Ma Y., Feretzaki M., Das P., Leventaki V., et al. Inhibition of JAK3 induces apoptosis and decreases anaplastic lymphoma kinase activity in anaplastic large cell lymphoma. Oncogene (2003) 22:5399–5407.[CrossRef][ISI][Medline]
  32. Shi Y., Pritchard K.A. Jr., Holman P., Rafiee P., Griffith O.W., Kalyanaraman B., et al. Chronic myocardial hypoxia increases nitric oxide synthase and decreases caveolin-3. Free Radic. Biol. Med. (2000) 29:695–703.[CrossRef][ISI][Medline]
  33. Piech A., Massart P.E., Dessy C., Feron O., Havaux X., Morel N., et al. Decreased expression of myocardial eNOS and caveolin in dogs with hypertrophic cardiomyopathy. Am. J. Physiol. Heart Circ. Physiol. (2002) 282:H219–H231.[Abstract/Free Full Text]
  34. Fujita T., Toya Y., Iwatsubo K., Onda T., Kimura K., Umemura S., et al. Accumulation of molecules involved in alpha1-adrenergic signal within caveolae: caveolin expression and the development of cardiac hypertrophy. Cardiovasc. Res. (2001) 51:709–716.[Abstract/Free Full Text]

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