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Aghamohammadzadeh R, Zhang YY, Stephens TE, Arons E, Zaman P, Polach KJ, Matar M, Yung LM, Yu PB, Bowman FP, Opotowsky AR, Waxman AB, Loscalzo J, Leopold JA, Maron BA. Up-regulation of the mammalian target of rapamycin complex 1 subunit Raptor by aldosterone induces abnormal pulmonary artery smooth muscle cell survival patterns to promote pulmonary arterial hypertension. FASEB J 2016; 30:2511-27. [PMID: 27006450 PMCID: PMC4904292 DOI: 10.1096/fj.201500042] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 03/08/2016] [Indexed: 11/11/2022]
Abstract
Activation of the mammalian target of rapamycin complex 1 (mTORC1) subunit Raptor induces cell growth and is a downstream target of Akt. Elevated levels of aldosterone activate Akt, and, in pulmonary arterial hypertension (PAH), correlate with pulmonary arteriole thickening, which suggests that mTORC1 regulation by aldosterone may mediate adverse pulmonary vascular remodeling. We hypothesized that aldosterone-Raptor signaling induces abnormal pulmonary artery smooth muscle cell (PASMC) survival patterns to promote PAH. Remodeled pulmonary arterioles from SU-5416/hypoxia-PAH rats and monocrotaline-PAH rats with hyperaldosteronism expressed increased levels of the Raptor target, p70S6K, which provided a basis for investigating aldosterone-Raptor signaling in human PASMCs. Aldosterone (10(-9) to 10(-7) M) increased Akt/mTOR/Raptor to activate p70S6K and increase proliferation, viability, and apoptosis resistance in PASMCs. In PASMCs transfected with Raptor-small interfering RNA or treated with spironolactone/eplerenone, aldosterone or pulmonary arterial plasma from patients with PAH failed to increase p70S6K activation or to induce cell survival in vitro Optimal inhibition of pulmonary arteriole Raptor was achieved by treatment with Staramine-monomethoxy polyethylene glycol that was formulated with Raptor-small interfering RNA plus spironolactone in vivo, which decreased arteriole muscularization and pulmonary hypertension in 2 experimental animal models of PAH in vivo Up-regulation of mTORC1 by aldosterone is a critical pathobiologic mechanism that controls PASMC survival to promote hypertrophic vascular remodeling and PAH.-Aghamohammadzadeh, R., Zhang, Y.-Y., Stephens, T. E., Arons, E., Zaman, P., Polach, K. J., Matar, M., Yung, L.-M., Yu, P. B., Bowman, F. P., Opotowsky, A. R., Waxman, A. B., Loscalzo, J., Leopold, J. A., Maron, B. A. Up-regulation of the mammalian target of rapamycin complex 1 subunit Raptor by aldosterone induces abnormal pulmonary artery smooth muscle cell survival patterns to promote pulmonary arterial hypertension.
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Affiliation(s)
- Reza Aghamohammadzadeh
- Department of Medicine, Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Ying-Yi Zhang
- Department of Medicine, Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Thomas E Stephens
- Department of Medicine, Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Elena Arons
- Department of Medicine, Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Paula Zaman
- Department of Medicine, Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | | | - Majed Matar
- Celsion Corporation, Lawrenceville, New Jersey, USA
| | - Lai-Ming Yung
- Department of Medicine, Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Paul B Yu
- Department of Medicine, Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Frederick P Bowman
- Department of Medicine, Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Alexander R Opotowsky
- Department of Medicine, Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA; Department of Cardiology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Aaron B Waxman
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Joseph Loscalzo
- Department of Medicine, Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Jane A Leopold
- Department of Medicine, Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Bradley A Maron
- Department of Medicine, Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA; Department of Cardiology, Boston Veterans Affairs Healthcare System, Boston, Massachusetts, USA
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Ye JX, Wang SS, Ge M, Wang DJ. Suppression of endothelial PGC-1α is associated with hypoxia-induced endothelial dysfunction and provides a new therapeutic target in pulmonary arterial hypertension. Am J Physiol Lung Cell Mol Physiol 2016; 310:L1233-42. [PMID: 27084848 DOI: 10.1152/ajplung.00356.2015] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 04/13/2016] [Indexed: 01/22/2023] Open
Abstract
Endothelial dysfunction plays a principal role in the pathogenesis of pulmonary arterial hypertension (PAH), which is a fatal disease with limited effective clinical treatments. Mitochondrial dysregulation and oxidative stress are involved in endothelial dysfunction. Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) is a key regulator of cellular energy metabolism and a master regulator of mitochondrial biogenesis. However, the roles of PGC-1α in hypoxia-induced endothelial dysfunction are not completely understood. We hypothesized that hypoxia reduces PGC-1α expression and leads to endothelial dysfunction in hypoxia-induced PAH. We confirmed that hypoxia has a negative impact on endothelial PGC-1α in experimental PAH in vitro and in vivo. Hypoxia-induced PGC-1α inhibited the oxidative metabolism and mitochondrial function, whereas sustained PGC-1α decreased reactive oxygen species (ROS) formation, mitochondrial swelling, and NF-κB activation and increased ATP formation and endothelial nitric oxide synthase (eNOS) phosphorylation. Furthermore, hypoxia-induced changes in the mean pulmonary arterial pressure and right heart hypertrophy were nearly normal after intervention. These results suggest that PGC-1α is associated with endothelial function in hypoxia-induced PAH and that improved endothelial function is associated with improved cellular mitochondrial respiration, reduced inflammation and oxygen stress, and increased PGC-1α expression. Taken together, these findings indicate that PGC-1α may be a new therapeutic target in PAH.
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Affiliation(s)
- Jia-Xin Ye
- Department of Cardio-Thoracic Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China; and
| | - Shan-Shan Wang
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Min Ge
- Department of Cardio-Thoracic Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China; and
| | - Dong-Jin Wang
- Department of Cardio-Thoracic Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China; and
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53
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Abeyrathna P, Kovacs L, Han W, Su Y. Calpain-2 activates Akt via TGF-β1-mTORC2 pathway in pulmonary artery smooth muscle cells. Am J Physiol Cell Physiol 2016; 311:C24-34. [PMID: 27099352 DOI: 10.1152/ajpcell.00295.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 04/18/2016] [Indexed: 01/29/2023]
Abstract
Calpain is a family of calcium-dependent nonlysosomal neutral cysteine endopeptidases. Akt is a serine/threonine kinase that belongs to AGC kinases and plays important roles in cell survival, growth, proliferation, angiogenesis, and cell metabolism. Both calpain and Akt are the downstream signaling molecules of platelet-derived growth factor (PDGF) and mediate PDGF-induced collagen synthesis and proliferation of pulmonary artery smooth muscle cells (PASMCs) in pulmonary vascular remodeling. We found that inhibitions of calpain-2 by using calpain inhibitor MDL28170 and calpain-2 small interfering RNA attenuated Akt phosphorylations at serine-473 (S473) and threonine-308 (T308), as well as collagen synthesis and cell proliferation of PASMCs induced by PDGF. Overexpression of calpain-2 in PASMCs induced dramatic increases in Akt phosphorylations at S473 and T308. Moreover, knockout of calpain attenuated Akt phosphorylations at S473 and T308 in smooth muscle of pulmonary arterioles of mice with chronic hypoxic pulmonary hypertension. The cell-permeable-specific transforming growth factor (TGF)-β receptor inhibitor SB431542 attenuated Akt phosphorylations at both S473 and T308 induced by PDGF and by overexpressed calpain-2 in PASMCs. Furthermore, SB-431452 and knocking down activin receptor-like kinase-5 significantly reduced PDGF-induced collagen synthesis and cell proliferation of PASMCs. Nevertheless, neutralizing extracellular TGF-β1 using a cell-impermeable TGF-β1 neutralizing antibody did not affect PDGF-induced Akt phosphorylations at S473 and T308. Furthermore, inhibition of mammalian target of rapamycin complex 2 (mTORC2) by knocking down its component protein Rictor prevented Akt phosphorylations at S473 and T308 induced by PDGF and by overexpressed calpain-2. These data provide first evidence supporting that calpain-2 upregulates PDGF-induced Akt phosphorylation in pulmonary vascular remodeling via an intracrine TGF-β1/mTORC2 mechanism.
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Affiliation(s)
- Prasanna Abeyrathna
- Department of Pharmacology & Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Laszlo Kovacs
- Department of Pharmacology & Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Weihong Han
- Department of Pharmacology & Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Yunchao Su
- Department of Pharmacology & Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia; Department of Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia; Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, Georgia; and Research Service, Charlie Norwood Veterans Affairs Medical Center, Augusta, Georgia
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Song Y, Wu Y, Su X, Zhu Y, Liu L, Pan Y, Zhu B, Yang L, Gao L, Li M. Activation of AMPK inhibits PDGF-induced pulmonary arterial smooth muscle cells proliferation and its potential mechanisms. Pharmacol Res 2016; 107:117-124. [PMID: 26993101 DOI: 10.1016/j.phrs.2016.03.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 02/19/2016] [Accepted: 03/11/2016] [Indexed: 12/30/2022]
Abstract
The aims of the present study were to examine signaling mechanisms for PDGF-induced pulmonary arterial smooth muscle cells (PASMC) proliferation and to determine the effect of AMPK activation on PDGF-induced PASMC proliferation and its underlying mechanisms. PDGF activated PI3K/Akt/mTOR signaling pathway, and this in turn up-regulated Skp2 and consequently reduced p27 leading to PASMC proliferation. Prior incubation of PASMC with metformin induced a dramatic AMPK activation and significantly blocked PDGF-induced cell proliferation. PASMC lacking AMPKα2 were resistant to the inhibitory effect of metformin on PDGF-induced cell proliferation. Metformin did not affect Akt activation but blocked mTOR phosphorylation in response to PDGF; these were accompanied by the reversion of Skp2 up-regulation and p27 reduction. Our study suggests that the activation of AMPK negatively regulates mTOR activity to suppress PASMC proliferation and therefore has a potential value in the prevention and treatment of pulmonary hypertension by negatively modulating pulmonary vascular remodeling.
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Affiliation(s)
- Yang Song
- Department of Respiratory and Critical Care Medicine, the First Affiliated Hospital of Medical College, Xian Jiaotong University, Xian, Shaanxi 710061, PR China
| | - Yuanyuan Wu
- Department of Respiratory and Critical Care Medicine, the First Affiliated Hospital of Medical College, Xian Jiaotong University, Xian, Shaanxi 710061, PR China
| | - Xiaofan Su
- Department of Respiratory and Critical Care Medicine, the First Affiliated Hospital of Medical College, Xian Jiaotong University, Xian, Shaanxi 710061, PR China
| | - Yanting Zhu
- Department of Respiratory and Critical Care Medicine, the First Affiliated Hospital of Medical College, Xian Jiaotong University, Xian, Shaanxi 710061, PR China
| | - Lu Liu
- Department of Respiratory and Critical Care Medicine, the First Affiliated Hospital of Medical College, Xian Jiaotong University, Xian, Shaanxi 710061, PR China
| | - Yilin Pan
- Department of Respiratory and Critical Care Medicine, the First Affiliated Hospital of Medical College, Xian Jiaotong University, Xian, Shaanxi 710061, PR China
| | - Bo Zhu
- Department of Respiratory and Critical Care Medicine, the First Affiliated Hospital of Medical College, Xian Jiaotong University, Xian, Shaanxi 710061, PR China
| | - Lan Yang
- Department of Respiratory and Critical Care Medicine, the First Affiliated Hospital of Medical College, Xian Jiaotong University, Xian, Shaanxi 710061, PR China
| | - Li Gao
- Division of Allergy and Clinical Immunology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA
| | - Manxiang Li
- Department of Respiratory and Critical Care Medicine, the First Affiliated Hospital of Medical College, Xian Jiaotong University, Xian, Shaanxi 710061, PR China.
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55
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Lee KY, Lee DH, Choi HC. Mesoglycan attenuates VSMC proliferation through activation of AMP-activated protein kinase and mTOR. Clin Hypertens 2016; 22:2. [PMID: 26893937 PMCID: PMC4750809 DOI: 10.1186/s40885-016-0037-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 01/08/2016] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Vascular smooth muscle cells (VSMC) proliferation contributes significantly to intimal thickening in atherosclerosis and restenosis diseases. Platelet derived growth factor (PDGF) has been implicated in VSMC proliferation though the activation of multiple growth-promoting signals. Mesoglycan, a natural glycosaminoglycans preparation, is reported to show vascular protective effect. However, the mechanisms by which mesoglycan inhibits proliferation of VSMC are not fully understood. Here, we investigated whether mesoglycan exert therapeutic effect via AMP-activated protein kinase (AMPK) and its underlying mechanism. METHODS We cultured VSMC with increasing doses of mesoglycan. AMPK activation was measured by western blot analysis and cell proliferation was measured by flow cytometry. RESULTS Mesoglycan dose- and time- dependently increased the phosphorylation of AMPK (Thr(172)) and its upstream target, LKB1 (Ser(428)) and its downstream, ACC (Ser(79)) in VSMCs. Mesoglycan also blocked the PDGF-stimulated cell cycle progression through the G0/G1 arrest. AMPK DNα1, AMPK DNα2 or AMPK siRNA reduced the mesoglycan-mediated inhibition of VSMC proliferation. AMPK signaling activated by mesoglycan regulates mTOR phosphorylation which closely related to cell proliferation. CONCLUSION These data suggest that mesoglycan-induced AMPK activation suppress the VSMC proliferation via mTOR-dependent mechanism and mesoglycan may have beneficial effects on vascular proliferative disorders such as atherosclerosis.
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Affiliation(s)
- Kyung Young Lee
- Department of Pharmacology, College of Medicine, Yeungnam University, 170 Hyunchung-Ro, Nam-Gu, Daegu, 42415 Republic of Korea ; Smart-aging Convergence Research Center, College of Medicine, Yeungnam University, 170 Hyunchung-Ro, Daegu, 42125 Republic of Korea
| | - Dong Hyup Lee
- Department of Thoracic and Cardiovascular Surgery, College of Medicine, Yeungnam University, 170 Hyunchung-Ro, Nam-Gu, Daegu, 42415 Republic of Korea
| | - Hyoung Chul Choi
- Department of Pharmacology, College of Medicine, Yeungnam University, 170 Hyunchung-Ro, Nam-Gu, Daegu, 42415 Republic of Korea ; Smart-aging Convergence Research Center, College of Medicine, Yeungnam University, 170 Hyunchung-Ro, Daegu, 42125 Republic of Korea
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56
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Abeyrathna P, Su Y. The critical role of Akt in cardiovascular function. Vascul Pharmacol 2015; 74:38-48. [PMID: 26025205 PMCID: PMC4659756 DOI: 10.1016/j.vph.2015.05.008] [Citation(s) in RCA: 288] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 05/07/2015] [Accepted: 05/16/2015] [Indexed: 12/30/2022]
Abstract
Akt kinase, a member of AGC kinases, is important in many cellular functions including proliferation, migration, cell growth and metabolism. There are three known Akt isoforms which play critical and diverse roles in the cardiovascular system. Akt activity is regulated by its upstream regulatory pathways at transcriptional and post-translational levels. Beta-catenin/Tcf-4, GLI1 and Stat-3 are some of few known transcriptional regulators of AKT gene. Threonine 308 and serine 473 are the two critical phosphorylation sites of Akt1. Translocation of Akt to the cell membrane facilitates PDK1 phosphorylation of the threonine site. The serine site is phosphorylated by mTORC2. Ack1, Src, PTK6, TBK1, IKBKE and IKKε are some of the non-canonical pathways which affect the Akt activity. Protein-protein interactions of Akt to actin and Hsp90 increase the Akt activity while Akt binding to other proteins such as CTMP and TRB3 reduces the Akt activity. The action of Akt on its downstream targets determines its function in cardiovascular processes such as cell survival, growth, proliferation, angiogenesis, vasorelaxation, and cell metabolism. Akt promotes cell survival via caspase-9, YAP, Bcl-2, and Bcl-x activities. Inhibition of FoxO proteins by Akt also increases cell survival by transcriptional mechanisms. Akt stimulates cell growth and proliferation through mTORC1. Akt also increases VEGF secretion and mediates eNOS phosphorylation, vasorelaxation and angiogenesis. Akt can increase cellular metabolism through its downstream targets GSK3 and GLUT4. The alterations of Akt signaling play an important role in many cardiovascular pathological processes such as atherosclerosis, cardiac hypertrophy, and vascular remodeling. Several Akt inhibitors have been developed and tested as anti-tumor agents. They could be potential novel therapeutics for the cardiovascular diseases.
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Affiliation(s)
- Prasanna Abeyrathna
- Department of Pharmacology & Toxicology, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912, USA
| | - Yunchao Su
- Department of Pharmacology & Toxicology, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912, USA.
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57
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Wang AP, Li XH, Gong SX, Li WQ, Hu CP, Zhang Z, Li YJ. miR-100 suppresses mTOR signaling in hypoxia-induced pulmonary hypertension in rats. Eur J Pharmacol 2015; 765:565-73. [DOI: 10.1016/j.ejphar.2015.09.031] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Revised: 09/15/2015] [Accepted: 09/21/2015] [Indexed: 12/31/2022]
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Abstract
The efficient delivery of short interfering RNA (siRNA) is an enormous challenge in the field of gene therapy. Herein, we report a delivery nanosystem based on programmed DNA self-assembly mammalian target of rapamycin (mTOR) siRNA-loaded DNA nanotubes (DNA-NTs). We demonstrate that these siRNA-DNA-NTs can be effectively transfected into pulmonary arterial smooth muscle cells (PASMCs) via endocytosis; and that the loaded mTOR siRNA can induce obvious autophagy and inhibit cell growth under both normal and hypoxic conditions. Moreover, we found that mTOR siRNA can control the autophagy and proliferation of PASMCs under hypoxic condition, suggesting a potential therapeutic application for mTOR siRNA in diseases involving abnormal autophagy in PASMCs.
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A Critical Role of the mTOR/eIF2α Pathway in Hypoxia-Induced Pulmonary Hypertension. PLoS One 2015; 10:e0130806. [PMID: 26120832 PMCID: PMC4487252 DOI: 10.1371/journal.pone.0130806] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 05/25/2015] [Indexed: 11/28/2022] Open
Abstract
Enhanced proliferation of pulmonary arterial vascular smooth muscle cells (PASMCs) is a key pathological component of vascular remodeling in hypoxia-induced pulmonary hypertension (HPH). Mammalian targeting of rapamycin (mTOR) signaling has been shown to play a role in protein translation and participate in the progression of pulmonary hypertension. Eukaryotic translation initiation factor-2α (eIF2α) is a key factor in regulation of cell growth and cell cycle, but its role in mTOR signaling and PASMCs proliferation remains unknown. Pulmonary hypertension (PH) rat model was established by hypoxia. Rapamycin was used to treat rats as an mTOR inhibitor. Proliferation of primarily cultured rat PASMCs was induced by hypoxia, rapamycin and siRNA of mTOR and eIF2α were used in loss-of-function studies. The expression and activation of eIF2α, mTOR and c-myc were analyzed. Results showed that mTOR/eIF2α signaling was significantly activated in pulmonary arteries from hypoxia exposed rats and PASMCs cultured under hypoxia condition. Treatment with mTOR inhibitor for 21 days attenuated vascular remodeling, suppressed mTOR and eIF2α activation, inhibited c-myc expression in HPH rats. In hypoxia-induced PASMCs, rapamycin and knockdown of mTOR and eIF2α by siRNA significantly abolished proliferation and increased c-myc expression. These results suggest a critical role of the mTOR/eIF2αpathway in hypoxic vascular remodeling and PASMCs proliferation of HPH.
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60
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Chen X, Walther FJ, Sengers RMA, Laghmani EH, Salam A, Folkerts G, Pera T, Wagenaar GTM. Metformin attenuates hyperoxia-induced lung injury in neonatal rats by reducing the inflammatory response. Am J Physiol Lung Cell Mol Physiol 2015; 309:L262-70. [PMID: 26047641 DOI: 10.1152/ajplung.00389.2014] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 06/02/2015] [Indexed: 01/31/2023] Open
Abstract
Because therapeutic options are lacking for bronchopulmonary dysplasia (BPD), there is an urgent medical need to discover novel targets/drugs to treat this neonatal chronic lung disease. Metformin, a drug commonly used to lower blood glucose in type 2 diabetes patients, may be a novel therapeutic option for BPD by reducing pulmonary inflammation and fibrosis and improving vascularization. We investigated the therapeutic potential of daily treatment with 25 and 100 mg/kg metformin, injected subcutaneously in neonatal Wistar rats with severe experimental BPD, induced by continuous exposure to 100% oxygen for 10 days. Parameters investigated included survival, lung and heart histopathology, pulmonary fibrin and collagen deposition, vascular leakage, right ventricular hypertrophy, and differential mRNA expression in the lungs of key genes involved in BPD pathogenesis, including inflammation, coagulation, and alveolar development. After daily metformin treatment rat pups with experimental BPD had reduced mortality, alveolar septum thickness, lung inflammation, and fibrosis, demonstrated by a reduced influx of macrophages and neutrophils and hyperoxia-induced collagen III and fibrin deposition (25 mg/kg), as well as improved vascularization (100 mg/kg) compared with control treatment. However, metformin did not ameliorate alveolar enlargement, small arteriole wall thickening, vascular alveolar leakage, and right ventricular hypertrophy. In conclusion metformin prolongs survival and attenuates pulmonary injury by reducing pulmonary inflammation, coagulation, and fibrosis but does not affect alveolar development or prevent pulmonary arterial hypertension and right ventricular hypertrophy in neonatal rats with severe hyperoxia-induced experimental BPD.
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Affiliation(s)
- Xueyu Chen
- Department of Pediatrics, Division of Neonatology, Leiden University Medical Center, Leiden, The Netherlands
| | - Frans J Walther
- Department of Pediatrics, Division of Neonatology, Leiden University Medical Center, Leiden, The Netherlands; Department of Pediatrics, Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles Medical Center, Torrance, California
| | - Rozemarijn M A Sengers
- Department of Pediatrics, Division of Neonatology, Leiden University Medical Center, Leiden, The Netherlands
| | - El Houari Laghmani
- Department of Pediatrics, Division of Neonatology, Leiden University Medical Center, Leiden, The Netherlands
| | - Asma Salam
- Department of Pediatrics, Division of Neonatology, Leiden University Medical Center, Leiden, The Netherlands
| | - Gert Folkerts
- Department of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands; and
| | - Tonio Pera
- Department of Pulmonology, Leiden University Medical Center, Leiden, The Netherlands
| | - Gerry T M Wagenaar
- Department of Pediatrics, Division of Neonatology, Leiden University Medical Center, Leiden, The Netherlands;
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Wilson JL, Yu J, Taylor L, Polgar P. Hyperplastic Growth of Pulmonary Artery Smooth Muscle Cells from Subjects with Pulmonary Arterial Hypertension Is Activated through JNK and p38 MAPK. PLoS One 2015; 10:e0123662. [PMID: 25905460 PMCID: PMC4408087 DOI: 10.1371/journal.pone.0123662] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 03/06/2015] [Indexed: 12/20/2022] Open
Abstract
Smooth muscle in the pulmonary artery of PAH subjects, both idiopathic and hereditary, is characterized by hyperplasia. Smooth muscle cells (HPASMC) isolated from subjects with or without PAH retain their in vivo phenotype as illustrated by their expression of alpha-smooth muscle actin and expression of H-caldesmon. Both non PAH and PAH HPASMC display a lengthy, approximately 94h, cell cycle. The HPASMC from both idiopathic and hereditary PAH display an abnormal proliferation characterized by continued growth under non-proliferative, non-growth stimulated conditions. This effector independent proliferation is JNK and p38 MAP kinase dependent. Blocking the activation of either abrogates the HPASMC growth. HPASMC from non PAH donors under quiescent conditions display negligible proliferation but divide upon exposure to growth factors such as PDGF-BB or FGF2 but not EGF. This growth does not involve the MAP kinases. Instead it routes via the tyrosine kinase receptor through mTOR and then 6SK. In the PAH cells PDGF-BB and FGF2 augment the dysregulated cell proliferation, also through mTOR/6SK. Additionally, blocking the activation of mTOR also modulates the MAP kinase promoted dysregulated growth. These results highlight key alterations in the growth of HPASMC from subjects with PAH which contribute to the etiology of the disease and can clearly be targeted at various regulatory points for future therapies.
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Affiliation(s)
- Jamie L. Wilson
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Jun Yu
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Linda Taylor
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Peter Polgar
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail:
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Zhang D, Wei Y, Chen K, Zhang X, Xu X, Shi Q, Han S, Chen X, Gong H, Li X, Zhang J. Biocompatible reactive oxygen species (ROS)-responsive nanoparticles as superior drug delivery vehicles. Adv Healthc Mater 2015; 4:69-76. [PMID: 25147049 DOI: 10.1002/adhm.201400299] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Revised: 07/17/2014] [Indexed: 01/09/2023]
Abstract
A novel reactive oxygen species (ROS)-responsive nanoplatform can be successfully manufactured from a ROS-triggerable β-cyclodextrin material. Extensive in vitro and in vivo studies validate that this nanoscaled system may serve as a new drug delivery vehicle with well-defined ROS-sensitivity and superior biocompatibility. This nanocarrier can be used for ROS-triggered transport of diverse therapeutics and imaging agents.
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Affiliation(s)
- Dinglin Zhang
- Department of Pharmaceutics, College of Pharmacy; Third Military Medical University; Chongqing 400038 China
| | - Yanling Wei
- Department of Gastroenterology, Daping Hospital; Third Military Medical University; Chongqing 400042 China
| | - Kai Chen
- Department of Pharmaceutics, College of Pharmacy; Third Military Medical University; Chongqing 400038 China
| | - Xiangjun Zhang
- Department of Pharmaceutics, College of Pharmacy; Third Military Medical University; Chongqing 400038 China
| | - Xiaoqiu Xu
- Department of Pharmaceutics, College of Pharmacy; Third Military Medical University; Chongqing 400038 China
| | - Qing Shi
- Department of Pharmaceutics, College of Pharmacy; Third Military Medical University; Chongqing 400038 China
| | - Songling Han
- Department of Pharmaceutics, College of Pharmacy; Third Military Medical University; Chongqing 400038 China
| | - Xin Chen
- Institute of Materia Medica; Third Military Medical University; Chongqing 400038 China
| | - Hao Gong
- Department of Gastroenterology, Daping Hospital; Third Military Medical University; Chongqing 400042 China
| | - Xiaohui Li
- Institute of Materia Medica; Third Military Medical University; Chongqing 400038 China
| | - Jianxiang Zhang
- Department of Pharmaceutics, College of Pharmacy; Third Military Medical University; Chongqing 400038 China
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Ryter SW, Choi AMK. Autophagy in lung disease pathogenesis and therapeutics. Redox Biol 2015; 4:215-25. [PMID: 25617802 PMCID: PMC4803789 DOI: 10.1016/j.redox.2014.12.010] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 12/18/2014] [Accepted: 12/18/2014] [Indexed: 12/16/2022] Open
Abstract
Autophagy, a cellular pathway for the degradation of damaged organelles and proteins, has gained increasing importance in human pulmonary diseases, both as a modulator of pathogenesis and as a potential therapeutic target. In this pathway, cytosolic cargos are sequestered into autophagosomes, which are delivered to the lysosomes where they are enzymatically degraded and then recycled as metabolic precursors. Autophagy exerts an important effector function in the regulation of inflammation, and immune system functions. Selective pathways for autophagic degradation of cargoes may have variable significance in disease pathogenesis. Among these, the autophagic clearance of bacteria (xenophagy) may represent a crucial host defense mechanism in the pathogenesis of sepsis and inflammatory diseases. Our recent studies indicate that the autophagic clearance of mitochondria, a potentially protective program, may aggravate the pathogenesis of chronic obstructive pulmonary disease by activating cell death programs. We report similar findings with respect to the autophagic clearance of cilia components, which can contribute to airways dysfunction in chronic lung disease. In certain diseases such as pulmonary hypertension, autophagy may confer protection by modulating proliferation and cell death. In other disorders, such as idiopathic pulmonary fibrosis and cystic fibrosis, impaired autophagy may contribute to pathogenesis. In lung cancer, autophagy has multiple consequences by limiting carcinogenesis, modulating therapeutic effectiveness, and promoting tumor cell survival. In this review we highlight the multiple functions of autophagy and its selective autophagy subtypes that may be of significance to the pathogenesis of human disease, with an emphasis on lung disease and therapeutics. Autophagy may impact the pathogenesis of pulmonary diseases. Mitophagy may exert deleterious effects in the pathogenesis of COPD. Autophagy can exert pleiotropic effects in lung cancer. Targeting autophagy may represent a promising therapeutic strategy in human diseases.
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Affiliation(s)
- Stefan W Ryter
- Joan and Sanford I. Weill Department of Medicine, Weill Cornell Medical College and New York-Presbyterian Hospital, New York, NY, USA.
| | - Augustine M K Choi
- Joan and Sanford I. Weill Department of Medicine, Weill Cornell Medical College and New York-Presbyterian Hospital, New York, NY, USA
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64
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Tang H, Chen J, Fraidenburg DR, Song S, Sysol JR, Drennan AR, Offermanns S, Ye RD, Bonini MG, Minshall RD, Garcia JGN, Machado RF, Makino A, Yuan JXJ. Deficiency of Akt1, but not Akt2, attenuates the development of pulmonary hypertension. Am J Physiol Lung Cell Mol Physiol 2014; 308:L208-20. [PMID: 25416384 DOI: 10.1152/ajplung.00242.2014] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Pulmonary vascular remodeling, mainly attributable to enhanced pulmonary arterial smooth muscle cell proliferation and migration, is a major cause for elevated pulmonary vascular resistance and pulmonary arterial pressure in patients with pulmonary hypertension. The signaling cascade through Akt, comprised of three isoforms (Akt1-3) with distinct but overlapping functions, is involved in regulating cell proliferation and migration. This study aims to investigate whether the Akt/mammalian target of rapamycin (mTOR) pathway, and particularly which Akt isoform, contributes to the development and progression of pulmonary vascular remodeling in hypoxia-induced pulmonary hypertension (HPH). Compared with the wild-type littermates, Akt1(-/-) mice were protected against the development and progression of chronic HPH, whereas Akt2(-/-) mice did not demonstrate any significant protection against the development of HPH. Furthermore, pulmonary vascular remodeling was significantly attenuated in the Akt1(-/-) mice, with no significant effect noted in the Akt2(-/-) mice after chronic exposure to normobaric hypoxia (10% O2). Overexpression of the upstream repressor of Akt signaling, phosphatase and tensin homolog deleted on chromosome 10 (PTEN), and conditional and inducible knockout of mTOR in smooth muscle cells were also shown to attenuate the rise in right ventricular systolic pressure and the development of right ventricular hypertrophy. In conclusion, Akt isoforms appear to have a unique function within the pulmonary vasculature, with the Akt1 isoform having a dominant role in pulmonary vascular remodeling associated with HPH. The PTEN/Akt1/mTOR signaling pathway will continue to be a critical area of study in the pathogenesis of pulmonary hypertension, and specific Akt isoforms may help specify therapeutic targets for the treatment of pulmonary hypertension.
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Affiliation(s)
- Haiyang Tang
- Department of Medicine, Division of Translational and Regenerative Medicine, The University of Arizona College of Medicine, Tucson, Arizona; Department of Physiology, The University of Arizona College of Medicine, Tucson, Arizona; Department of Medicine, Division of Pulmonary, Critical Care, Sleep and Allergy Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Jiwang Chen
- Department of Medicine, Division of Pulmonary, Critical Care, Sleep and Allergy Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Dustin R Fraidenburg
- Department of Medicine, Division of Pulmonary, Critical Care, Sleep and Allergy Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Shanshan Song
- Department of Medicine, Division of Translational and Regenerative Medicine, The University of Arizona College of Medicine, Tucson, Arizona; Department of Physiology, The University of Arizona College of Medicine, Tucson, Arizona; Department of Medicine, Division of Pulmonary, Critical Care, Sleep and Allergy Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Justin R Sysol
- Department of Medicine, Division of Pulmonary, Critical Care, Sleep and Allergy Medicine, University of Illinois at Chicago, Chicago, Illinois; Department of Pharmacology, University of Illinois at Chicago, Chicago, Illinois; and
| | - Abigail R Drennan
- Department of Medicine, Division of Pulmonary, Critical Care, Sleep and Allergy Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Stefan Offermanns
- Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Richard D Ye
- Department of Pharmacology, University of Illinois at Chicago, Chicago, Illinois; and
| | - Marcelo G Bonini
- Department of Pharmacology, University of Illinois at Chicago, Chicago, Illinois; and
| | - Richard D Minshall
- Department of Pharmacology, University of Illinois at Chicago, Chicago, Illinois; and
| | - Joe G N Garcia
- Department of Medicine, Division of Translational and Regenerative Medicine, The University of Arizona College of Medicine, Tucson, Arizona
| | - Roberto F Machado
- Department of Medicine, Division of Pulmonary, Critical Care, Sleep and Allergy Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Ayako Makino
- Department of Physiology, The University of Arizona College of Medicine, Tucson, Arizona
| | - Jason X-J Yuan
- Department of Medicine, Division of Translational and Regenerative Medicine, The University of Arizona College of Medicine, Tucson, Arizona; Department of Physiology, The University of Arizona College of Medicine, Tucson, Arizona; Department of Medicine, Division of Pulmonary, Critical Care, Sleep and Allergy Medicine, University of Illinois at Chicago, Chicago, Illinois; Department of Pharmacology, University of Illinois at Chicago, Chicago, Illinois; and
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65
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Mizumura K, Choi AMK, Ryter SW. Emerging role of selective autophagy in human diseases. Front Pharmacol 2014; 5:244. [PMID: 25414669 PMCID: PMC4220655 DOI: 10.3389/fphar.2014.00244] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 10/23/2014] [Indexed: 01/31/2023] Open
Abstract
Autophagy was originally described as a highly conserved system for the degradation of cytosol through a lysosome-dependent pathway. In response to starvation, autophagy degrades organelles and proteins to provide metabolites and energy for its pro-survival effects. Autophagy is recognized as playing a role in the pathogenesis of disease either directly or indirectly, through the regulation of vital processes such as programmed cell death, inflammation, and adaptive immune mechanisms. Recent studies have demonstrated that autophagy is not only a simple metabolite recycling system, but also has the ability to degrade specific cellular targets, such as mitochondria, cilia, and invading bacteria. In addition, selective autophagy has also been implicated in vesicle trafficking pathways, with potential roles in secretion and other intracellular transport processes. Selective autophagy has drawn the attention of researchers because of its potential importance in clinical diseases. Therapeutic strategies to target selective autophagy rather than general autophagy may maximize clinical benefit by enhancing selectivity. In this review, we outline the principle components of selective autophagy processes and their emerging importance in human disease, with an emphasis on pulmonary diseases.
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Affiliation(s)
- Kenji Mizumura
- Joan and Sanford I. Weill Department of Medicine, Weill Cornell Medical Center, New York-Presbyterian Hospital - Weill Cornell Medical College New York, NY, USA
| | - Augustine M K Choi
- Joan and Sanford I. Weill Department of Medicine, Weill Cornell Medical Center, New York-Presbyterian Hospital - Weill Cornell Medical College New York, NY, USA
| | - Stefan W Ryter
- Joan and Sanford I. Weill Department of Medicine, Weill Cornell Medical Center, New York-Presbyterian Hospital - Weill Cornell Medical College New York, NY, USA
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66
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Jin H, Wang Y, Zhou L, Liu L, Zhang P, Deng W, Yuan Y. Melatonin attenuates hypoxic pulmonary hypertension by inhibiting the inflammation and the proliferation of pulmonary arterial smooth muscle cells. J Pineal Res 2014; 57:442-50. [PMID: 25251287 DOI: 10.1111/jpi.12184] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 09/21/2014] [Indexed: 01/11/2023]
Abstract
Hypoxia-induced inflammation and excessive proliferation of pulmonary artery smooth muscle cells (PASMCs) play important roles in the pathological process of hypoxic pulmonary hypertension (HPH). Melatonin possesses anti-inflammatory and antiproliferative properties. However, the effect of melatonin on HPH remains unclear. In this study, adult Sprague-Dawley rats were exposed to intermittent chronic hypoxia for 4 wk to mimic a severe HPH condition. Hemodynamic and pulmonary pathomorphology data showed that chronic hypoxia significantly increased right ventricular systolic pressures (RVSP), weight of the right ventricle/left ventricle plus septum (RV/LV+S) ratio, and median width of pulmonary arterioles. Melatonin attenuated the elevation of RVSP, RV/LV+S, and mitigated the pulmonary vascular structure remodeling. Melatonin also suppressed the hypoxia-induced high expression of proliferating cell nuclear antigen (PCNA), hypoxia-inducible factor-1α (HIF-1α), and nuclear factor-κB (NF-κB). In vitro, melatonin concentration-dependently inhibited the proliferation of PASMCs and the levels of phosphorylation of Akt and extracellular signal-regulated kinases1/2 (ERK1/2) caused by hypoxia. These results suggested that melatonin might potentially prevent HPH via anti-inflammatory and antiproliferative mechanisms.
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Affiliation(s)
- Haifeng Jin
- Institute of Cancer Stem Cell, The First Affiliated Hospital, Dalian Medical University Cancer Center, Dalian, China; Department of Anatomy, Qiqihar Medical University, Qiqihar, China
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67
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Schieber M, Chandel NS. TOR signaling couples oxygen sensing to lifespan in C. elegans. Cell Rep 2014; 9:9-15. [PMID: 25284791 DOI: 10.1016/j.celrep.2014.08.075] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 07/07/2014] [Accepted: 08/27/2014] [Indexed: 12/21/2022] Open
Abstract
Metazoans adapt to a low-oxygen environment (hypoxia) through activation of stress-response pathways. Here, we report that transient hypoxia exposure extends lifespan in C. elegans through mitochondrial reactive oxygen species (ROS)-dependent regulation of the nutrient-sensing kinase target of rapamycin (TOR) and its upstream activator, RHEB-1. The increase in lifespan during hypoxia requires the intestinal GATA-type transcription factor ELT-2 downstream of TOR signaling. Using RNA sequencing (RNA-seq), we describe an ELT-2-dependent hypoxia response that includes an intestinal glutathione S-transferase, GSTO-1, and uncover that GSTO-1 is required for lifespan under hypoxia. These results indicate mitochondrial ROS-dependent TOR signaling integrates metabolic adaptations in order to confer survival under hypoxia.
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Affiliation(s)
- Michael Schieber
- Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Navdeep S Chandel
- Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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68
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Wang W, Liu J, Ma A, Miao R, Jin Y, Zhang H, Xu K, Wang C, Wang J. mTORC1 Is Involved in Hypoxia-Induced Pulmonary Hypertension Through the Activation of Notch3. J Cell Physiol 2014; 229:2117-25. [PMID: 24825564 DOI: 10.1002/jcp.24670] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 05/09/2014] [Indexed: 11/06/2022]
Affiliation(s)
- Wang Wang
- Department of Physiology; Capital Medical University; Beijing P.R. China
| | - Jie Liu
- Department of Physiology; Capital Medical University; Beijing P.R. China
| | - Aiping Ma
- Department of Respiratory Medicine; Peking Union Medical College Hospital; Beijing P.R. China
| | - Ran Miao
- Beijing Key Laboratory of Respiratory and Pulmonary Circulation Disorders; Capital Medical University; Beijing P.R. China
| | - Yuling Jin
- Department of Physiology; Capital Medical University; Beijing P.R. China
| | - Hongbing Zhang
- Department of Physiology and Pathophysiology; State Key Laboratory of Medical Molecular Biology; Institute of Basic Medical Sciences and School of Basic Medicine; Chinese Academy of Medical Sciences and Peking Union Medical College; Beijing P.R. China
| | - Kaifeng Xu
- Department of Respiratory Medicine; Peking Union Medical College Hospital; Beijing P.R. China
| | - Chen Wang
- Beijing Key Laboratory of Respiratory and Pulmonary Circulation Disorders; Capital Medical University; Beijing P.R. China
- Beijing Hospital; Ministry of Health; Beijing P.R. China
| | - Jun Wang
- Department of Physiology; Capital Medical University; Beijing P.R. China
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69
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Baicalin inhibits hypoxia-induced pulmonary artery smooth muscle cell proliferation via the AKT/HIF-1α/p27-associated pathway. Int J Mol Sci 2014; 15:8153-68. [PMID: 24821539 PMCID: PMC4057725 DOI: 10.3390/ijms15058153] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 04/27/2014] [Accepted: 04/30/2014] [Indexed: 12/30/2022] Open
Abstract
Baicalin, a flavonoid compound purified from the dry roots of Scutellaria baicalensis Georgi, has been shown to possess various pharmacological actions. Previous studies have revealed that baicalin inhibits the growth of cancer cells through the induction of apoptosis. Pulmonary arterial hypertension (PAH) is a devastating disease characterized by enhanced pulmonary artery smooth muscle cell (PASMCs) proliferation and suppressed apoptosis. However, the potential mechanism of baicalin in the regulation of PASMC proliferation and the prevention of cardiovascular diseases remains unexplored. To test the effects of baicalin on hypoxia, we used rats treated with or without baicalin (100 mg·kg−1 each rat) at the beginning of the third week after hypoxia. Hemodynamic and pulmonary pathomorphology data showed that right ventricular systolic pressures (RVSP), the weight of the right ventricle/left ventricle plus septum (RV/LV + S) ratio and the medial width of pulmonary arterioles were much higher in chronic hypoxia. However, baicalin treatment repressed the elevation of RVSP, RV/LV + S and attenuated the pulmonary vascular structure remodeling (PVSR) of pulmonary arterioles induced by chronic hypoxia. Additionally, baicalin (10 and 20 μmol·L−1) treatment suppressed the proliferation of PASMCs and attenuated the expression of hypoxia-inducible factor-α (HIF-α) under hypoxia exposure. Meanwhile, baicalin reversed the hypoxia-induced reduction of p27 and increased AKT/protein kinase B phosphorylation p-AKT both in vivo and in vitro. These results suggested that baicalin could effectively attenuate PVSR and hypoxic pulmonary hypertension.
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70
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Ibe JCF, Zhou Q, Chen T, Tang H, Yuan JXJ, Raj JU, Zhou G. Adenosine monophosphate-activated protein kinase is required for pulmonary artery smooth muscle cell survival and the development of hypoxic pulmonary hypertension. Am J Respir Cell Mol Biol 2014; 49:609-18. [PMID: 23668615 DOI: 10.1165/rcmb.2012-0446oc] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Human pulmonary artery smooth muscle cells (HPASMCs) express both adenosine monophosphate-activated protein kinase (AMPK) α1 and α2. We investigated the distinct roles of AMPK α1 and α2 in the survival of HPASMCs during hypoxia and hypoxia-induced pulmonary hypertension (PH). The exposure of HPASMCs to hypoxia (3% O2) increased AMPK activation and phosphorylation, and the inhibition of AMPK with Compound C during hypoxia decreased their viability and increased lactate dehydrogenase activity and apoptosis. Although the suppression of either AMPK α1 or α2 expression led to increased cell death, the suppression of AMPK α2 alone increased caspase-3 activity and apoptosis in HPASMCs exposed to hypoxia. It also resulted in the decreased expression of myeloid cell leukemia sequence 1 (MCL-1). The knockdown of MCL-1 or MCL-1 inhibitors increased caspase-3 activity and apoptosis in HPASMCs exposed to hypoxia. On the other hand, the suppression of AMPK α1 expression alone prevented hypoxia-mediated autophagy. The inhibition of autophagy induced cell death in HPASMCs. Our results suggest that AMPK α1 and AMPK α2 play differential roles in the survival of HPASMCs during hypoxia. The activation of AMPK α2 maintains the expression of MCL-1 and prevents apoptosis, whereas the activation of AMPK α1 stimulates autophagy, promoting HPASMC survival. Moreover, treatment with Compound C, which inhibits both isoforms of AMPK, prevented and partly reversed hypoxia-induced PH in mice. Taking these results together, our study suggests that AMPK plays a key role in the pathogenesis of pulmonary arterial hypertension, and AMPK may represent a novel therapeutic target for the treatment of pulmonary arterial hypertension.
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71
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Liu X, Wang G, You Z, Qian P, Chen H, Dou Y, Wei Z, Chen Y, Mao C, Zhang J. Inhibition of hypoxia-induced proliferation of pulmonary arterial smooth muscle cells by a mTOR siRNA-loaded cyclodextrin nanovector. Biomaterials 2014; 35:4401-16. [PMID: 24582377 DOI: 10.1016/j.biomaterials.2014.02.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Accepted: 02/06/2014] [Indexed: 01/05/2023]
Abstract
The proliferation of pulmonary arterial smooth muscle cells (PASMCs) is a key pathophysiological component of vascular remodeling in pulmonary arterial hypertension (PAH), an intractable disease, for which pharmacotherapy is limited and only slight improvement in survival outcomes have achieved over the past few decades. RNA interference provides a highly promising strategy to the treatment of this chronic lung disease, while efficient delivery of small interfering RNA (siRNA) remains a key challenge for the development of clinically acceptable siRNA therapeutics. With the aim to construct useful nanomedicines, the mammalian target of rapamycin (mTOR) siRNA was loaded into hybrid nanoparticles based on low molecular weight (Mw) polyethylenimine (PEI) and a pH-responsive cyclodextrin material (Ac-aCD) or poly(lactic-co-glycolic acid) (PLGA). This hybrid nanoplatform gave rise to desirable siRNA loading, and the payload release could be modulated by the hydrolysis characteristics of carrier materials. Fluorescence observation and flow cytometry quantification suggested that both Ac-aCD and PLGA nanovectors (NVs) may enter PASMCs under either normoxia or hypoxia conditions as well as in the presence of serum, with uptake and transfection efficiency significantly higher than those of cationic vectors such as PEI with Mw of 25 kDa (PEI25k) and Lipofectamine 2000 (Lipo 2k). Hybrid Ac-aCD or PLGA NV containing siRNA remarkably inhibited proliferation and activated apoptosis of hypoxic PASMCs, largely resulting from effective suppression of mTOR signaling as evidenced by significantly lowered expression of mTOR mRNA and phosphorylated protein. Moreover, these hybrid nanomedicines were more effective than commonly used cationic vectors like PEI25k and Lipo 2k, with respect to cell growth inhibition, apoptosis activation, and expression attenuation of mTOR mRNA and protein. Therefore, mTOR siRNA nanomedicines based on hybrid Ac-aCD or PLGA NV may be promising therapeutics for diseases related to hypoxic abnormal growth of PASMCs.
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Affiliation(s)
- Xueping Liu
- Institute of Respiratory Diseases, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Guansong Wang
- Institute of Respiratory Diseases, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
| | - Zaichun You
- Institute of Respiratory Diseases, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Pin Qian
- Institute of Respiratory Diseases, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Huaping Chen
- Institute of Respiratory Diseases, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Yin Dou
- Department of Pharmaceutics, College of Pharmacy, Third Military Medical University, Chongqing 400038, China
| | - Zhenghua Wei
- Institute of Respiratory Diseases, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Yan Chen
- Institute of Respiratory Diseases, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Chengde Mao
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA.
| | - Jianxiang Zhang
- Department of Pharmaceutics, College of Pharmacy, Third Military Medical University, Chongqing 400038, China.
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A cell permeable peptide targeting the intracellular loop 2 of endothelin B receptor reduces pulmonary hypertension in a hypoxic rat model. PLoS One 2013; 8:e81309. [PMID: 24312288 DOI: 10.1371/journal.pone.0081309] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 10/10/2013] [Indexed: 11/19/2022] Open
Abstract
Cell permeable peptides (CPP) aid cellular uptake of targeted cargo across the hydrophobic plasma membrane. CPP-mediated cargo delivery of receptor signaling motifs provides an opportunity to regulate specific receptor initiated signaling cascades. Both endothelin-1 receptors, ETA and ETB, have been targets of antagonist therapies for individuals with pulmonary arterial hypertension (PAH). These therapies have had success but have been accompanied by adverse reactions. Also, unlike the CPP which target specific signaling cascades, the antagonists target the entire function of the receptor. Using the CPP strategy of biased antagonism of the ETB receptor's intracellular loop 2 (ICB2), we demonstrate blunting of hypoxic pulmonary hypertension (HPH) in the rat, including indices of pulmonary arterial pressure, right ventricular hypertrophy and pulmonary vascular remodeling. Further, ex vivo analysis of the pulmonary artery treated with the IC2B peptide upon injection manifests marked reductions in Akt and ERK activation. Both kinases have been intimately related to cell proliferation and vascular contraction, the hallmarks of PAH. These observations in sum illustrate an involvement of the ETB receptor in HPH and furthermore provide a basis for a novel, CPP-based, strategy in the treatment of PAH, ultimately able to target not only ET-1, but also other factors involved in the development of PAH.
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73
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Goncharov DA, Kudryashova TV, Ziai H, Ihida-Stansbury K, DeLisser H, Krymskaya VP, Tuder RM, Kawut SM, Goncharova EA. Mammalian target of rapamycin complex 2 (mTORC2) coordinates pulmonary artery smooth muscle cell metabolism, proliferation, and survival in pulmonary arterial hypertension. Circulation 2013; 129:864-74. [PMID: 24270265 DOI: 10.1161/circulationaha.113.004581] [Citation(s) in RCA: 151] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Enhanced proliferation, resistance to apoptosis, and metabolic shift to glycolysis of pulmonary arterial vascular smooth muscle cells (PAVSMCs) are key pathophysiological components of pulmonary vascular remodeling in idiopathic pulmonary arterial hypertension (PAH). The role of the distinct mammalian target of rapamycin (mTOR) complexes mTORC1 (mTOR-Raptor) and mTORC2 (mTOR-Rictor) in PAVSMC proliferation and survival in PAH and their therapeutic relevance are unknown. METHODS AND RESULTS Immunohistochemical and immunoblot analyses revealed that mTORC1 and mTORC2 pathways are markedly upregulated in small remodeled pulmonary arteries and isolated distal PAVSMCs from subjects with idiopathic PAH that have increased ATP levels, proliferation, and survival that depend on glycolytic metabolism. Small interfering RNA- and pharmacology-based analysis showed that although both mTORC1 and mTORC2 contribute to proliferation, only mTORC2 is required for ATP generation and survival of idiopathic PAH PAVSMCs. mTORC2 downregulated the energy sensor AMP-activated protein kinase, which led to activation of mTORC1-S6 and increased proliferation, as well as a deficiency of the proapoptotic protein Bim and idiopathic PAH PAVSMC survival. NADPH oxidase 4 (Nox4) protein levels were increased in idiopathic PAH PAVSMCs, which was necessary for mTORC2 activation, proliferation, and survival. Nox4 levels and mTORC2 signaling were significantly upregulated in small pulmonary arteries from hypoxia-exposed rats at days 2 to 28 of hypoxia. Treatment with the mTOR kinase inhibitor PP242 at days 15 to 28 suppressed mTORC2 but not Nox4, induced smooth muscle-specific apoptosis in small pulmonary arteries, and reversed hypoxia-induced pulmonary vascular remodeling in rats. CONCLUSIONS These data provide a novel mechanistic link of Nox4-dependent activation of mTORC2 via the energy sensor AMP-activated protein kinase to increased proliferation and survival of PAVSMCs in PAH, which suggests a new potential pathway for therapeutic interventions.
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Affiliation(s)
- Dmitry A Goncharov
- Pulmonary, Allergy & Critical Care Division (D.A.G., T.V.K., H.Z., H.D., V.P.K., S.M.K., E.A.G.), Department of Pathology and Laboratory Medicine (K.I.-S.), Pulmonary Vascular Disease Program (K.I.-S., H.D., V.P.K., S.M.K., E.A.G.), Center for Clinical Epidemiology and Biostatistics (S.M.K.), and Abramson Cancer Center (V.P.K.), Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA; Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Denver, Aurora, CO (R.M.T.); and Division of Pulmonary, Allergy and Critical Care Medicine, Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA (D.A.G., T.V.K.). Dr Goncharova's current affiliation is the Division of Pulmonary, Allergy and Critical Care Medicine, Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA
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Abstract
World Health Organization (WHO) group 5 pulmonary hypertension (PH) entails a heterogeneous group of disorders that may cause PH by unclear and/or multiple mechanisms. In particular, group 5 includes PH caused by hematologic disorders, systemic diseases, metabolic disorders, chronic renal failure, and disorders leading to pulmonary vascular occlusion or compression. This article discusses common pathogenic mechanisms leading to group 5 PH, followed by a detailed overview of epidemiology, pathogenesis, and disease-specific management of the individual group 5 conditions. Off-label use of vasomodulatory therapies, typically indicated for pulmonary arterial hypertension (WHO group 1 PH), in group 5 conditions is also discussed.
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Affiliation(s)
- Tim Lahm
- Division of Pulmonary, Allergy, Critical Care, Occupational and Sleep Medicine, Department of Medicine, Richard L. Roudebush VA Medical Center, Center for Immunobiology, Indiana University School of Medicine, 980 West Walnut Street, Room C400, Indianapolis, IN 46202, USA.
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Houssaini A, Abid S, Mouraret N, Wan F, Rideau D, Saker M, Marcos E, Tissot CM, Dubois-Randé JL, Amsellem V, Adnot S. Rapamycin reverses pulmonary artery smooth muscle cell proliferation in pulmonary hypertension. Am J Respir Cell Mol Biol 2013; 48:568-77. [PMID: 23470622 DOI: 10.1165/rcmb.2012-0429oc] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Pulmonary artery (PA) smooth muscle cell (SMC) proliferation in pulmonary hypertension (PH) may be linked to dysregulated mammalian target of rapamycin (mTOR) signaling. The mTOR pathway involves two independent complexes, mTORC1 and mTORC2, which phosphorylate S6 kinase (S6K) and serine/threonine kinase (Akt), respectively, and differ in their sensitivity to rapamycin. Here, we evaluated rapamycin-sensitive mTOR substrates and PA-SMC proliferation in rats with monocrotaline (MCT)-induced PH (MCT-PH). Compared with cells from control rats, cultured PA-SMCs from MCT-PH rats exhibited increased growth responses to platelet-derived growth factor, serotonin (5-hydroxytryptophan), IL-1β, insulin-like growth factor-1, or fetal calf serum (FCS), with increases in phosphorylated (Ser-473)Akt, (Thr-308)Akt, glycogen synthase kinase (GSK)3, and S6K reflecting activated mTORC1 and mTORC2 signaling. Treatment with rapamycin (0.5 μM) or the Akt inhibitor, A-443654 (0.5 μM), reduced FCS-stimulated growth of PA-SMCs from MCT-PH rats to the level in control rats while inhibiting Akt, GSK3, and S6K activation. Neither the tyrosine kinase inhibitor, imatinib (0.1 μM), nor the 5-hydroxytryptophan transporter inhibitor, fluoxetine (5 μM), normalized the increased PA-SMC growth response to FCS. Rapamycin treatment (5 mg/kg/d) of MCT-PH rats from Day 21 to Day 28 markedly reduced phoshop (p)-Aky, p-GSK3, and p-S6K in PAs, and normalized growth of derived PA-SMCs. This effect was not observed after 1 week of imatinib (100 mg/kg/d) or fluoxetine (20 mg/kg/d). Rapamycin given preventively (Days 1-21) or curatively (Days 21-42) inhibited MCT-PH to a greater extent than did imatinib or fluoxetine. Experimental PH in rats is associated with a sustained proliferative PA-SMC phenotype linked to activation of both mTORC1 and mTORC2 signaling and is suppressed by rapamycin treatment.
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Affiliation(s)
- Amal Houssaini
- INSERM U955 Team 8 and Département de Physiologie, Créteil, France
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Lee I, Dodia C, Chatterjee S, Zagorski J, Mesaros C, Blair IA, Feinstein SI, Jain M, Fisher AB. A novel nontoxic inhibitor of the activation of NADPH oxidase reduces reactive oxygen species production in mouse lung. J Pharmacol Exp Ther 2013; 345:284-96. [PMID: 23475902 DOI: 10.1124/jpet.112.201079] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
1-Hexadecyl-3-trifluoroethylglycero-sn-2-phosphomethanol (MJ33) is a fluorinated phospholipid analog that inhibits the phospholipase A2 (PLA2) activity of peroxiredoxin 6 (Prdx6). Prdx6 PLA2 activity is required for activation of NADPH oxidase 2 and subsequent generation of reactive oxygen species (ROS). In vitro, MJ33 inhibited agonist-stimulated production of ROS by the isolated perfused mouse lung, lung microvascular endothelial cells, and polymorphonuclear leukocytes. MJ33 (0.02-0.5 µmol MJ33/kg body weight) in mixed unilamellar liposomes was administered to C57BL/6 mice by either intratracheal (i.t.) or i.v. routes. Lung MJ33 content, measured by liquid chromatography/mass spectroscopy, showed uptake of 67-87% of the injected dose for i.t. and 23-42% for i.v. administration at 4 hours postinjection. PLA2 activity of lung homogenates was markedly inhibited (>85%) at 4 hours postadministration. Both MJ33 content and PLA2 activity gradually returned to near control levels over the subsequent 24-72 hours. Mice treated with MJ33 at 12.5-25 µmol/kg did not show changes (compared with control) in clinical symptomatology, body weight, hematocrit, and histology of lung, liver, and kidney during a 30- to 50-day observation period. Thus, the toxic dose of MJ33 was >25 µmol/kg, whereas the PLA2 inhibitory dose was approximately 0.02 µmol/kg, indicating a high margin of safety. MJ33 administered to mice prior to lung isolation markedly reduced ROS production and tissue lipid and protein oxidation during ischemia followed by reperfusion. Thus, MJ33 could be useful as a therapeutic agent to prevent ROS-mediated tissue injury associated with lung inflammation or in harvested lungs prior to transplantation.
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Affiliation(s)
- Intae Lee
- Institute for Environmental Medicine, University of Pennsylvania, 3620 Hamilton Walk, 1 John Morgan Building, Philadelphia, PA 19104, USA
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Goncharova EA. mTOR and vascular remodeling in lung diseases: current challenges and therapeutic prospects. FASEB J 2013; 27:1796-807. [PMID: 23355268 DOI: 10.1096/fj.12-222224] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Mammalian target of rapamycin (mTOR) is a major regulator of cellular metabolism, proliferation, and survival that is implicated in various proliferative and metabolic diseases, including obesity, type 2 diabetes, hamartoma syndromes, and cancer. Emerging evidence suggests a potential critical role of mTOR signaling in pulmonary vascular remodeling. Remodeling of small pulmonary arteries due to increased proliferation, resistance to apoptosis, and altered metabolism of cells forming the pulmonary vascular wall is a key currently irreversible pathological feature of pulmonary hypertension, a progressive pulmonary vascular disorder with high morbidity and mortality. In addition to rare familial and idiopathic forms, pulmonary hypertension is also a life-threatening complication of several lung diseases associated with hypoxia. This review aims to summarize our current knowledge and recent advances in understanding the role of the mTOR pathway in pulmonary vascular remodeling, with a specific focus on the hypoxia component, a confirmed shared trigger of pulmonary hypertension in lung diseases. We also discuss the emerging role of mTOR as a promising therapeutic target and mTOR inhibitors as potential pharmacological approaches to treat pulmonary vascular remodeling in pulmonary hypertension.
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Affiliation(s)
- Elena A Goncharova
- University of Pennsylvania Perelman School of Medicine, Translational Research Laboratories, Rm. 1214, 125 South 31st St., Philadelphia, PA 19104, USA.
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Malik AR, Urbanska M, Macias M, Skalecka A, Jaworski J. Beyond control of protein translation: what we have learned about the non-canonical regulation and function of mammalian target of rapamycin (mTOR). BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1834:1434-48. [PMID: 23277194 DOI: 10.1016/j.bbapap.2012.12.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Accepted: 12/15/2012] [Indexed: 12/19/2022]
Abstract
Mammalian target of rapamycin (mTOR) is a serine-threonine kinase involved in almost every aspect of mammalian cell function. This kinase was initially believed to control protein translation in response to amino acids and trophic factors, and this function has become a canonical role for mTOR. However, mTOR can form two separate protein complexes (mTORCs). Recent advances clearly demonstrate that both mTORCs can respond to various stimuli and change myriad cellular processes. Therefore, our current view of the cellular roles of TORCs has rapidly expanded and cannot be fully explained without appreciating recent findings about the new modes of mTOR regulation and identification of non-canonical effectors of mTOR that contribute to transcription, cytoskeleton dynamics, and membrane trafficking. This review discusses the molecular details of these newly discovered non-canonical functions that allow mTORCs to control the cellular environment at multiple levels. This article is part of a Special Issue entitled: Inhibitors of Protein Kinases (2012).
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Affiliation(s)
- Anna R Malik
- Laboratory of Molecular and Cellular Neurobiology, International Institute of Molecular and Cell Biology in Warsaw, 4 Ks. Trojdena St., 02-109 Warsaw, Poland
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Goncharova EA, Khavin IS, Goncharov DA, Krymskaya VP. Differential effects of formoterol on thrombin- and PDGF-induced proliferation of human pulmonary arterial vascular smooth muscle cells. Respir Res 2012. [PMID: 23186269 PMCID: PMC3545871 DOI: 10.1186/1465-9921-13-109] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Background Increased pulmonary arterial vascular smooth muscle (PAVSM) cell proliferation is a key pathophysiological component of pulmonary vascular remodeling in pulmonary arterial hypertension (PH). The long-acting β2-adrenergic receptor (β2AR) agonist formoterol, a racemate comprised of (R,R)- and (S,S)-enantiomers, is commonly used as a vasodilator in chronic obstructive pulmonary disease (COPD). PH, a common complication of COPD, increases patients’ morbidity and reduces survival. Recent studies demonstrate that formoterol has anti-proliferative effects on airway smooth muscle cells and bronchial fibroblasts. The effects of formoterol and its enantiomers on PAVSM cell proliferation are not determined. The goals of this study were to examine effects of racemic formoterol and its enantiomers on PAVSM cell proliferation as it relates to COPD-associated PH. Methods Basal, thrombin-, PDGF- and chronic hypoxia-induced proliferation of primary human PAVSM cells was examined by DNA synthesis analysis using BrdU incorporation assay. ERK1/2, mTORC1 and mTORC2 activation were determined by phosphorylation levels of ERK1/2, ribosomal protein S6 and S473-Akt using immunoblot analysis. Results We found that (R,R) and racemic formoterol inhibited basal, thrombin- and chronic hypoxia-induced proliferation of human PAVSM cells while (S,S) formoterol had lesser inhibitory effect. The β2AR blocker propranolol abrogated the growth inhibitory effect of formoterol. (R,R), but not (S,S) formoterol attenuated basal, thrombin- and chronic hypoxia-induced ERK1/2 phosphorylation, but had little effect on Akt and S6 phosphorylation levels. Formoterol and its enantiomers did not significantly affect PDGF-induced DNA synthesis and PDGF-dependent ERK1/2, S473-Akt and S6 phosphorylation in human PAVSM cells. Conclusions Formoterol inhibits basal, thrombin-, and chronic hypoxia-, but not PDGF-induced human PAVSM cell proliferation and ERK1/2, but has little effect on mTORC1 and mTORC2 signaling. Anti-proliferative effects of formoterol depend predominantly on its (R,R) enantiomer and require the binding with β2AR. These data suggest that (R,R) formoterol may be considered as potential adjuvant therapy to inhibit PAVSM cell proliferation in COPD-associated PH.
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Affiliation(s)
- Elena A Goncharova
- Pulmonary, Allergy & Critical Care Division, Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
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80
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Taniguchi M, Kitatani K, Kondo T, Hashimoto-Nishimura M, Asano S, Hayashi A, Mitsutake S, Igarashi Y, Umehara H, Takeya H, Kigawa J, Okazaki T. Regulation of autophagy and its associated cell death by "sphingolipid rheostat": reciprocal role of ceramide and sphingosine 1-phosphate in the mammalian target of rapamycin pathway. J Biol Chem 2012; 287:39898-910. [PMID: 23035115 DOI: 10.1074/jbc.m112.416552] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The role of "sphingolipid rheostat" by ceramide and sphingosine 1-phosphate (S1P) in the regulation of autophagy remains unclear. In human leukemia HL-60 cells, amino acid deprivation (AA(-)) caused autophagy with an increase in acid sphingomyleinase (SMase) activity and ceramide, which serves as an autophagy inducing lipid. Knockdown of acid SMase significantly suppressed the autophagy induction. S1P treatment counteracted autophagy induction by AA(-) or C(2)-ceramide. AA(-) treatment promoted mammalian target of rapamycin (mTOR) dephosphorylation/inactivation, inducing autophagy. S1P treatment suppressed mTOR inactivation and autophagy induction by AA(-). S1P exerts biological actions via cell surface receptors, and S1P(3) among five S1P receptors was predominantly expressed in HL-60 cells. We evaluated the involvement of S1P(3) in suppressing autophagy induction. S1P treatment of CHO cells had no effects on mTOR inactivation and autophagy induction by AA(-) or C(2)-ceramide. Whereas S1P treatment of S1P(3) overexpressing CHO cells resulted in activation of the mTOR pathway, preventing cells from undergoing autophagy induced by AA(-) or C(2)-ceramide. These results indicate that S1P-S1P(3) plays a role in counteracting ceramide signals that mediate mTOR-controlled autophagy. In addition, we evaluated the involvement of ceramide-activated protein phosphatases (CAPPs) in ceramide-dependent inactivation of the mTOR pathway. Inhibition of CAPP by okadaic acid in AA(-)- or C(2)-ceramide-treated cells suppressed dephosphorylation/inactivation of mTOR, autophagy induction, and autophagy-associated cell death, indicating a novel role of ceramide-CAPPs in autophagy induction. Moreover, S1P(3) engagement by S1P counteracted cell death. Taken together, these results indicated that sphingolipid rheostat in ceramide-CAPPs and S1P-S1P(3) signaling modulates autophagy and its associated cell death through regulation of the mTOR pathway.
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Affiliation(s)
- Makoto Taniguchi
- Division of Clinical Laboratory Medicine, Faculty of Medicine, Tottori University, 86 Nishi-Machi, Yonago 683-8503, Japan
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Ogawa A, Firth AL, Smith KA, Maliakal MV, Yuan JXJ. PDGF enhances store-operated Ca2+ entry by upregulating STIM1/Orai1 via activation of Akt/mTOR in human pulmonary arterial smooth muscle cells. Am J Physiol Cell Physiol 2011; 302:C405-11. [PMID: 22031597 DOI: 10.1152/ajpcell.00337.2011] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Platelet-derived growth factor (PDGF) and its receptor are known to be substantially elevated in lung tissues and pulmonary arterial smooth muscle cells (PASMC) isolated from patients and animals with pulmonary arterial hypertension. PDGF has been shown to phosphorylate and activate Akt and mammalian target of rapamycin (mTOR) in PASMC. In this study, we investigated the role of PDGF-mediated activation of Akt signaling in the regulation of cytosolic Ca(2+) concentration and cell proliferation. PDGF activated the Akt/mTOR pathway and, subsequently, enhanced store-operated Ca(2+) entry (SOCE) and cell proliferation in human PASMC. Inhibition of Akt attenuated the increase in cytosolic Ca(2+) concentration due to both SOCE and PASMC proliferation. This effect correlated with a significant downregulation of stromal interacting molecule (STIM) and Orai, proposed molecular correlates for SOCE in many cell types. The data from this study present a novel pathway for the regulation of Ca(2+) signaling and PASMC proliferation involving activation of Akt in response to upregulated expression of PDGF. Targeting this pathway may lead to the development of a novel therapeutic option for the treatment of pulmonary arterial hypertension.
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Affiliation(s)
- Aiko Ogawa
- Department of Clinical Science, National Hospital Organization Okayama Medical Center, Japan
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Kramer EL, Hardie WD, Mushaben EM, Acciani TH, Pastura PA, Korfhagen TR, Hershey GK, Whitsett JA, Le Cras TD. Rapamycin decreases airway remodeling and hyperreactivity in a transgenic model of noninflammatory lung disease. J Appl Physiol (1985) 2011; 111:1760-7. [PMID: 21903885 DOI: 10.1152/japplphysiol.00737.2011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Airway hyperreactivity (AHR) and remodeling are cardinal features of asthma and chronic obstructive pulmonary disease. New therapeutic targets are needed as some patients are refractory to current therapies and develop progressive airway remodeling and worsening AHR. The mammalian target of rapamycin (mTOR) is a key regulator of cellular proliferation and survival. Treatment with the mTOR inhibitor rapamycin inhibits inflammation and AHR in allergic asthma models, but it is unclear if rapamycin can directly inhibit airway remodeling and AHR, or whether its therapeutic effects are entirely mediated through immunosuppression. To address this question, we utilized transforming growth factor-α (TGF-α) transgenic mice null for the transcription factor early growth response-1 (Egr-1) (TGF-α Tg/Egr-1(ko/ko) mice). These mice develop airway smooth muscle thickening and AHR in the absence of altered lung inflammation, as previously reported. In this study, TGF-α Tg/Egr-1(ko/ko) mice lost body weight and developed severe AHR after 3 wk of lung-specific TGF-α induction. Rapamycin treatment prevented body weight loss, airway wall thickening, abnormal lung mechanics, and increases in airway resistance to methacholine after 3 wk of TGF-α induction. Increases in tissue damping and airway elastance were also attenuated in transgenic mice treated with rapamycin. TGF-α/Egr-1(ko/ko) mice on doxycycline for 8 wk developed severe airway remodeling. Immunostaining for α-smooth muscle actin and morphometric analysis showed that rapamycin treatment prevented airway smooth muscle thickening around small airways. Pentachrome staining, assessments of lung collagen and fibronectin mRNA levels, indicated that rapamycin also attenuated fibrotic pathways induced by TGF-α expression for 8 wk. Thus rapamycin reduced airway remodeling and AHR, demonstrating an important role for mTOR signaling in TGF-α-induced/EGF receptor-mediated reactive airway disease.
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Affiliation(s)
- Elizabeth L Kramer
- Section of Neonatology, Perinatal and Pulmonary Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA
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Abstract
Mutational inactivation of the tumor suppressor tuberous sclerosis complex 2 (TSC2) constitutively activates mTORC1, increases cell proliferation, and induces the pathological manifestations observed in tuberous sclerosis (TS) and in pulmonary lymphangioleiomyomatosis (LAM). While the role of mTORC1 in TSC2-dependent growth has been extensively characterized, little is known about the role of mTORC2. Our data demonstrate that mTORC2 modulates TSC2-null cell proliferation and survival through RhoA GTPase and Bcl2 proteins. TSC2-null cell proliferation was inhibited not only by reexpression of TSC2 or small interfering RNA (siRNA)-induced downregulation of Rheb, mTOR, or raptor, but also by siRNA for rictor. Increased RhoA GTPase activity and P-Ser473 Akt were inhibited by siRNA for rictor. Importantly, constitutively active V14RhoA reversed growth inhibition induced by siRNA for rictor, siRNA TSC1, reexpression of TSC2, or simvastatin. While siRNA for RhoA had a modest effect on growth inhibition, downregulation of RhoA markedly increased TSC2-null cell apoptosis. Inhibition of RhoA activity downregulated antiapoptotic Bcl2 and upregulated proapoptotic Bim, Bok, and Puma. In vitro and in vivo, simvastatin alone or in combination with rapamycin inhibited cell growth and induced TSC2-null cell apoptosis, abrogated TSC2-null tumor growth, improved animal survival, and prevented tumor recurrence by inhibiting cell growth and promoting apoptosis. Our data demonstrate that mTORC2-dependent activation of RhoA is required for TSC2-null cell growth and survival and suggest that targeting both mTORC2 and mTORC1 by a combination of proapoptotic simvastatin and cytostatic rapamycin shows promise for combinational therapeutic intervention in diseases with TSC2 dysfunction.
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