Pulmonary arterial hypertension (PAH), a progressive fatal disease, manifests by vascular remodeling of pulmonary arteries (PA), elevated right ventricular afterload, right heart failure and death. Enhanced proliferation and impaired apoptosis of pulmonary arterial vascular smooth muscle cells (PAVSMC) are key pathophysiological components of vascular remodeling in PAH, the molecular mechanisms of which are not fully understood. This proposal focuses on two functionally distinct complexes of mammalian target of rapamycin (mTOR), mTORC1 and mTORC2, as novel regulators of PAVSMC metabolism, growth and survival in PAH. By using PAVSMC from subjects with idiopathic PAH (human PAH PAVSMC) and unused donor lungs, we show that cultured human PAH PAVSMC retain molecular and cellular abnormalities reported in PAH lungs in vivo, such as elevated proliferation, survival, and altered cellular ATP levels due to glycolytic metabolism that provides a unique tool for translational mechanistic studies. Our published study demonstrates that increased PAVSMC proliferation under chronic hypoxia requires activation of both mTORC1 and mTORC2. Our preliminary data show that mTORC1 and mTORC2 signaling pathways are up-regulated in vivo and in vitro in PAVSMC from small PA from subjects with idiopathic PAH and from rats with chronic hypoxia-induced pulmonary vascular remodeling. Our data also show that both mTORC1 and mTORC2 promote proliferation, but only mTORC2 modulates cellular energy levels and cell survival and suggest that inhibition of both mTORC1 and mTORC2 is required to suppress growth, proliferation and promote apoptosis in human PAH PAVSMC. Based on published studies and our data, we hypothesize that increased proliferation and survival of PAVSMC in PAH requires activation of both mTORC1 (promoting protein synthesis and cell growth) and mTORC2 (activating Akt, increasing cellular energy levels, down-regulating AMPK and increasing cell survival). We also propose that targeting mTOR in both mTORC1 and mTORC2 is necessary to inhibit PAVSMC growth, proliferation, promote apoptosis, and prevent or abrogate pulmonary vascular remodeling in PAH. To test this hypothesis, in Aim 1, activation of mTORC1 and mTORC2 signaling pathways will be critically tested using lung tissue samples from PAH patients and healthy donors and cultured PAVSMC from idiopathic PAH patients and unused donor lungs;
in Aim 2, we will determine whether mTORC1 and mTORC2 employ differential molecular mechanisms to modulate growth, proliferation and survival of human PAH PAVSMC. Specific roles of mTORC1 and mTORC2 in regulating cell growth, cellular ATP levels and apoptosis will be examined;
in Aim 3, we will evaluate whether suppression of both mTORC1 and mTORC2 inhibits growth, cellular energy levels, proliferation and induces apoptosis in vitro in human PAH PAVSMC and prevents or abrogates pulmonary vascular remodeling in vivo in a rat chronic hypoxia model of PH. Proposed studies will define the role of mTOR in regulating energy levels, growth, proliferation and survival of PAH PAVSMC and will explore whether mTOR could serve as a potential molecular target for treatment of human PAH.

Public Health Relevance

These studies will define the specific roles of mTORC1 and mTORC2 in regulating energy levels, growth, proliferation and survival of PAVSMC in pulmonary arterial hypertension (PAH);will provide insights into the molecular mechanisms that are important in pathogenesis of PAH;and will explore whether mTOR could serve as a target molecule to inhibit PAVSMC proliferation, induce apoptosis, and prevent or abrogate pulmonary vascular remodeling in pulmonary hypertension.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL113178-03
Application #
8693009
Study Section
Respiratory Integrative Biology and Translational Research Study Section (RIBT)
Program Officer
Peavy, Hannah H
Project Start
2012-09-01
Project End
2016-05-31
Budget Start
2014-06-01
Budget End
2015-05-31
Support Year
3
Fiscal Year
2014
Total Cost
$365,282
Indirect Cost
$120,282
Name
University of Pittsburgh
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
004514360
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Kudryashova, Tatiana V; Shen, Yuanjun; Pena, Andressa et al. (2018) Inhibitory Antibodies against Activin A and TGF-? Reduce Self-Supported, but Not Soluble Factors-Induced Growth of Human Pulmonary Arterial Vascular Smooth Muscle Cells in Pulmonary Arterial Hypertension. Int J Mol Sci 19:
Shen, Yuanjun Steven; Goncharova, Elena A (2018) TWISTed HIF: revisiting smooth muscle HIF-1? signaling in pulmonary hypertension. Am J Physiol Lung Cell Mol Physiol 315:L387-L389
Goncharov, Dmitry A; Goncharova, Elena A; Tofovic, Stevan P et al. (2018) Metformin Therapy for Pulmonary Hypertension Associated with Heart Failure with Preserved Ejection Fraction versus Pulmonary Arterial Hypertension. Am J Respir Crit Care Med 198:681-684
Pullamsetti, Soni Savai; Savai, Rajkumar; Seeger, Werner et al. (2017) Translational Advances in the Field of Pulmonary Hypertension. From Cancer Biology to New Pulmonary Arterial Hypertension Therapeutics. Targeting Cell Growth and Proliferation Signaling Hubs. Am J Respir Crit Care Med 195:425-437
Pena, Andressa; Kobir, Ahasanul; Goncharov, Dmitry et al. (2017) Pharmacological Inhibition of mTOR Kinase Reverses Right Ventricle Remodeling and Improves Right Ventricle Structure and Function in Rats. Am J Respir Cell Mol Biol 57:615-625
Ghouleh, Imad Al; Sahoo, Sanghamitra; Meijles, Daniel N et al. (2017) Endothelial Nox1 oxidase assembly in human pulmonary arterial hypertension; driver of Gremlin1-mediated proliferation. Clin Sci (Lond) 131:2019-2035
Alvarez, Roger A; Miller, Megan P; Hahn, Scott A et al. (2017) Targeting Pulmonary Endothelial Hemoglobin ? Improves Nitric Oxide Signaling and Reverses Pulmonary Artery Endothelial Dysfunction. Am J Respir Cell Mol Biol 57:733-744
Kudryashova, Tatiana V; Goncharov, Dmitry A; Pena, Andressa et al. (2016) HIPPO-Integrin-linked Kinase Cross-Talk Controls Self-Sustaining Proliferation and Survival in Pulmonary Hypertension. Am J Respir Crit Care Med 194:866-877
Kelly, Neil J; Dandachi, Nadine; Goncharov, Dmitry A et al. (2016) Automated Measurement of Blood Vessels in Tissues from Microscopy Images. Curr Protoc Cytom 78:12.44.1-12.44.13
Sahoo, Sanghamitra; Meijles, Daniel N; Al Ghouleh, Imad et al. (2016) MEF2C-MYOCD and Leiomodin1 Suppression by miRNA-214 Promotes Smooth Muscle Cell Phenotype Switching in Pulmonary Arterial Hypertension. PLoS One 11:e0153780

Showing the most recent 10 out of 16 publications