Growth and migration of vascular smooth muscle cells (VSMCs) are responses to arterial injury which are critical to the processes of atherosclerosis, pulmonary hypertension and restenosis after percutaneous transluminal coronary angioplasty. Proliferation is associated with alteration in gene expression of the VSMCs ranging from a quiescent/differentiated phenotype to a proliferating/dedifferentiated one. The protein phosphatase 1 (PP1), the main regulator of the transcription factor CREB, is strongly involved in the control of cell proliferation via p53 and p21. PP1 is regulated by phosphatase inhibitor-1 (I-1), which is activated by PKA phosphorylation and inhibited by protein phosphatase PP2A and PP2B (calcineurin). I-1 is expressed in vascular smooth muscle cells (VSMC), but does not appear to play a significant role in contractile or relaxant response. Since calcineurin strongly controls VSMC proliferation, we tested whether I-1 is involved in proliferation-related pathways. In order to conduct this project, we used human coronary artery smooth muscle cells and rat aortic VSMCs, and a rat carotid injury model for in vivo studies. Confocal immunofluorescence and Western blot analysis showed that I-1 protein is expressed in the media layer of healthy human coronary arteries and mammary arteries, and is down-regulated in the media of human atherosclerotic plaques;whereas PP1 expression is up-regulated in proliferating human smooth muscle cells compared to coronary artery tissue samples. Real time PCR showed that I-1 mRNA is 1000 fold lower in proliferating human coronary artery smooth muscle cells and in proliferating VSMCs, indicating a proliferative (synthetic) phenotype. Adenovirus gene transfer of constitutively active I-1 (I-1c) and transfection of siRNA-PP1 inhibited VSMC proliferation and migration in vitro. I-1c overexpression increased CREB phosphorylation on Ser133 and downstream transcription factors p53 and p21. In samples obtained two weeks after carotid artery injury in the rat model, the expression of I-1 was absent in the injured vessels, this finding is in concordance with vascular remodelling during neointimal proliferation. Furthermore, adenoviral gene transfer of I-1c, prevented neointimal proliferation in the carotid injury model. In conclusion, in VSMCs the phosphatase inhibitor I-1 is the marker of quiescent phenotype and is involved in the control of VSMC proliferation and migration via transcription factor CREB. Despite the previously described findings, the role of I-1 in VSMC proliferation and remodelling is not well understood. To elucidate the mechanisms by which I-1 is involved in VSMC proliferation, we propose the following specific aims: 1) determine if I-1 is a molecular determinant in modulating VSMC proliferation, 2) determine the mechanism by which I-1 regulates VSMC proliferation and migration and 3) define the physiological consequences of the overexpression and ablation of I-1 in vivo after vascular injury. Defining the mechanisms of I-1 and its physiological consequences, will be of great relevance in the analysis and future proposal of therapies to prevent and perhaps reverse neointima formation after angioplasty.

Public Health Relevance

Protein Phosphatase Inhibitor-1 and vascular smooth muscle cell function. The key mechanisms of restenosis after percutaneous angioplasty or stent implantation are the growth and migration of vascular smooth muscle cells (VSMC). Inhibitor-1 is a critical protein that regulates calcium cycling in VSMCs, which significantly changes when VSMCs proliferate. Our goal is to focus on strategies that inhibit VSMC proliferation and migration and enhance re-endothelization by using somatic gene therapy carrying I-1 to provide a treatment that prevents restonosis.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Scientist Development Award - Research & Training (K01)
Project #
Application #
Study Section
Special Emphasis Panel (ZHL1-CSR-H (M1))
Program Officer
Meadows, Tawanna
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Icahn School of Medicine at Mount Sinai
Internal Medicine/Medicine
Schools of Medicine
New York
United States
Zip Code
Evrard, Solene M; Lecce, Laura; Michelis, Katherine C et al. (2016) Endothelial to mesenchymal transition is common in atherosclerotic lesions and is associated with plaque instability. Nat Commun 7:11853
Aguero, Jaume; Ishikawa, Kiyotake; Hadri, Lahouaria et al. (2016) Intratracheal Gene Delivery of SERCA2a Ameliorates Chronic Post-Capillary Pulmonary Hypertension: A Large Animal Model. J Am Coll Cardiol 67:2032-46
Lipskaia, Larissa; Bobe, Regis; Chen, Jiqiu et al. (2014) Synergistic role of protein phosphatase inhibitor 1 and sarco/endoplasmic reticulum Ca2+ -ATPase in the acquisition of the contractile phenotype of arterial smooth muscle cells. Circulation 129:773-85
Lipskaia, Larissa; Hadri, Lahouaria; Lopez, Jose J et al. (2013) Benefit of SERCA2a gene transfer to vascular endothelial and smooth muscle cells: a new aspect in therapy of cardiovascular diseases. Curr Vasc Pharmacol 11:465-79
Hadri, Lahouaria; Kratlian, Razmig G; Benard, Ludovic et al. (2013) Therapeutic efficacy of AAV1.SERCA2a in monocrotaline-induced pulmonary arterial hypertension. Circulation 128:512-23
Fish, Kenneth M; Ladage, Dennis; Kawase, Yoshiaki et al. (2013) AAV9.I-1c delivered via direct coronary infusion in a porcine model of heart failure improves contractility and mitigates adverse remodeling. Circ Heart Fail 6:310-7
Lompré, A-M; Hadri, L; Merlet, E et al. (2013) Efficient transduction of vascular smooth muscle cells with a translational AAV2.5 vector: a new perspective for in-stent restenosis gene therapy. Gene Ther 20:901-12
Lipskaia, L; Hadri, L; Le Prince, P et al. (2013) SERCA2a gene transfer prevents intimal proliferation in an organ culture of human internal mammary artery. Gene Ther 20:396-406
Merlet, E; Lipskaia, L; Marchand, A et al. (2013) A calcium-sensitive promoter construct for gene therapy. Gene Ther 20:248-54
Karakikes, Ioannis; Hadri, Lahouaria; Rapti, Kleopatra et al. (2012) Concomitant intravenous nitroglycerin with intracoronary delivery of AAV1.SERCA2a enhances gene transfer in porcine hearts. Mol Ther 20:565-71

Showing the most recent 10 out of 21 publications