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Polonis K, Becari C, Chahal CAA, Zhang Y, Allen AM, Kellogg TA, Somers VK, Singh P. Chronic Intermittent Hypoxia Triggers a Senescence-like Phenotype in Human White Preadipocytes. Sci Rep 2020; 10:6846. [PMID: 32321999 PMCID: PMC7176724 DOI: 10.1038/s41598-020-63761-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 04/03/2020] [Indexed: 12/13/2022] Open
Abstract
Obstructive sleep apnea (OSA) is a common sleep disorder associated with obesity. Emerging evidence suggest that OSA increases the risk of cardiovascular morbidity and mortality partly via accelerating the process of cellular aging. Thus, we sought to examine the effects of intermittent hypoxia (IH), a hallmark of OSA, on senescence in human white preadipocytes. We demonstrate that chronic IH is associated with an increased generation of mitochondrial reactive oxygen species along with increased prevalence of cells with nuclear localization of γH2AX & p16. A higher prevalence of cells positive for senescence-associated β-galactosidase activity was also evident with chronic IH exposure. Intervention with aspirin, atorvastatin or renin-angiotensin system (RAS) inhibitors effectively attenuated IH-mediated senescence-like phenotype. Importantly, the validity of in vitro findings was confirmed by examination of the subcutaneous abdominal adipose tissue which showed that OSA patients had a significantly higher percentage of cells with nuclear localization of γH2AX & p16 than non-OSA individuals (20.1 ± 10.8% vs. 10.3 ± 2.7%, Padjusted < 0.001). Furthermore, the frequency of dual positive γH2AX & p16 nuclei in adipose tissue of OSA patients receiving statin, aspirin, and/or RAS inhibitors was comparable to non-OSA individuals. This study identifies chronic IH as a trigger of senescence-like phenotype in preadipocytes. Together, our data suggest that OSA may be considered as a senescence-related disorder.
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Affiliation(s)
- Katarzyna Polonis
- Department of Cardiovascular Medicine, Mayo Clinic, MN, Rochester, USA
| | - Christiane Becari
- Department of Cardiovascular Medicine, Mayo Clinic, MN, Rochester, USA
- Department of Surgery and Anatomy, Ribeirao Preto Medical School, Ribeirão Preto, SP, Brazil
| | - C Anwar A Chahal
- Department of Cardiovascular Medicine, Mayo Clinic, MN, Rochester, USA
- Mayo Clinic Graduate School of Biomedical Sciences, MN, Rochester, USA
| | - Yuebo Zhang
- Department of Cardiovascular Medicine, Mayo Clinic, MN, Rochester, USA
| | - Alina M Allen
- Division of Gastroenterology and Hepatology, Mayo Clinic, MN, Rochester, USA
| | | | - Virend K Somers
- Department of Cardiovascular Medicine, Mayo Clinic, MN, Rochester, USA
| | - Prachi Singh
- Department of Cardiovascular Medicine, Mayo Clinic, MN, Rochester, USA.
- Pennington Biomedical Research Center, LA, Baton Rouge, USA.
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Pongkorpsakol P, Buasakdi C, Chantivas T, Chatsudthipong V, Muanprasat C. An agonist of a zinc-sensing receptor GPR39 enhances tight junction assembly in intestinal epithelial cells via an AMPK-dependent mechanism. Eur J Pharmacol 2018; 842:306-313. [PMID: 30459126 DOI: 10.1016/j.ejphar.2018.10.038] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Revised: 10/17/2018] [Accepted: 10/25/2018] [Indexed: 02/08/2023]
Abstract
Intestinal barrier function depends on integrity of tight junctions, which serve as barriers to transepithelial influx of noxious substances/microorganisms from gut lumen. The G-protein coupled receptor 39 (GPR39) is a zinc-sensing receptor, which is expressed in several cell types including intestinal epithelial cells (IECs). The main objective of this study was to investigate the effect of GPR39 activation on tight junction assembly in IECs. Treatment with TC-G 1008 (1 μM -10 μM), a GPR39 agonist, and zinc (10 μM -100 μM) increased tight junction assembly in T84 cells. This effect was suppressed by pretreatment with compound C, an inhibitor of AMP-activated protein kinase (AMPK). In addition, western blot analysis revealed that treatment with TC-G 1008 induced AMPK activation in time- and concentration-dependent manners. Interestingly, inhibitors of phospholipase C (PLC) and calcium/calmodulin-dependent protein kinase kinase β (CaMKKβ) abrogated the effect of TC-G 1008 on inducing AMPK activation, tight junction assembly and zonula occludens-1 re-organization. Collectively, this study reveals a novel role of GPR39 in enhancing tight junction assembly in IECs via PLC-CaMKKβ-AMPK pathways. GPR39 agonists may be beneficial in the treatment of diseases associated impaired intestinal barrier function.
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Affiliation(s)
- Pawin Pongkorpsakol
- Translational Medicine Graduate Program, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Rama VI Road, Rajathevi, Bangkok 10400, Thailand
| | - Chavin Buasakdi
- College of Agricultural and Life Science, University of Wisconsin-Madison, 1450 Linden Dr, Madison, WI 53706, USA
| | - Thanyatorn Chantivas
- Faculty of Medicine Ramathibodi Hospital, Mahidol University, Rama VI Road, Rajathevi, Bangkok 10400, Thailand
| | - Varanuj Chatsudthipong
- Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Rajathevi, Bangkok 10400, Thailand
| | - Chatchai Muanprasat
- Translational Medicine Graduate Program, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Rama VI Road, Rajathevi, Bangkok 10400, Thailand; Department of Physiology, Faculty of Science, Mahidol University, Rama VI Road, Rajathevi, Bangkok 10400, Thailand; Excellent Center for Drug Discovery, Faculty of Science, Mahidol University, Rama VI Road, Rajathevi, Bangkok 10400, Thailand; Research Center of Transport Protein for Medical Innovation, Faculty of Science, Mahidol University, Rama VI Road, Rajathevi, Bangkok 10400, Thailand.
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Briddon SJ, Kilpatrick LE, Hill SJ. Studying GPCR Pharmacology in Membrane Microdomains: Fluorescence Correlation Spectroscopy Comes of Age. Trends Pharmacol Sci 2017; 39:158-174. [PMID: 29277246 DOI: 10.1016/j.tips.2017.11.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 11/13/2017] [Accepted: 11/14/2017] [Indexed: 12/17/2022]
Abstract
G protein-coupled receptors (GPCRs) are organised within the cell membrane into highly ordered macromolecular complexes along with other receptors and signalling proteins. Understanding how heterogeneity in these complexes affects the pharmacology and functional response of these receptors is crucial for developing new and more selective ligands. Fluorescence correlation spectroscopy (FCS) and related techniques such as photon counting histogram (PCH) analysis and image-based FCS can be used to interrogate the properties of GPCRs in these membrane microdomains, as well as their interaction with fluorescent ligands. FCS analyses fluorescence fluctuations within a small-defined excitation volume to yield information about their movement, concentration and molecular brightness (aggregation). These techniques can be used on live cells with single-molecule sensitivity and high spatial resolution. Once the preserve of specialist equipment, FCS techniques can now be applied using standard confocal microscopes. This review describes how FCS and related techniques have revealed novel insights into GPCR biology.
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Affiliation(s)
- Stephen J Briddon
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK; Centre for Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, UK
| | - Laura E Kilpatrick
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK; Centre for Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, UK
| | - Stephen J Hill
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK; Centre for Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, UK.
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Saleem M, Pokkunuri I, Asghar M. Superoxide increases angiotensin II AT1 receptor function in human kidney-2 cells. FEBS Open Bio 2017; 6:1273-1284. [PMID: 28203527 PMCID: PMC5302058 DOI: 10.1002/2211-5463.12148] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 09/19/2016] [Accepted: 10/17/2016] [Indexed: 01/11/2023] Open
Abstract
The redox-sensitive Sp family transcription factor has been linked to the regulation of angiotensin II type 1 receptor (AT1R). However, the exact mechanism of AT1R regulation in renal cells is poorly understood. We tested the specificity of reactive oxygen species (ROS), superoxide vs. hydrogen peroxide (H2O2), and the specific role of Sp3 transcription factor, if any, in the regulation of AT1R in human kidney cells (HK2 cells). Superoxide dismutase (SOD) inhibitor diethyldithiocarbamate (DETC), but not H2O2 treatment, increased fluorescence levels of superoxide probe dihydroethidium (DHE). H2O2, but not DETC, treatment increased the fluorescence of the H2O2-sensitive probe dichloro-dihydro-fluorescein (DCFH). These data suggest that SOD inhibition by DETC increases the superoxide but not H2O2 and exogenously added H2O2 is not converted to superoxide in renal cells. Furthermore, DETC, but not H2O2, treatment increased nuclear accumulation of Sp3, which was attenuated with the superoxide dismutase (SOD)-mimetic tempol. DETC treatment also increased AT1R mRNA and protein levels that were attenuated with tempol, whereas H2O2 did not have any effects on AT1R mRNA. Moreover, Sp3 overexpression increased, while Sp3 depletion by siRNA decreased, protein levels of AT1R. In addition, Sp3 siRNA in the presence of DETC decreased AT1R protein expression. Furthermore, DETC treatment increased the levels of cell surface AT1R as measured by biotinylation and immunofluorescence studies. Angiotensin II increased PKC activity in vehicle-treated cells that further increased in DETC-treated cells, which was attenuated by AT1R blocker candesartan and SOD-mimetic tempol. Taken together, our results suggest that superoxide, but not H2O2, via Sp3 up-regulates AT1R expression and function in the renal cells.
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Affiliation(s)
- Mohammad Saleem
- Pharmacological and Pharmaceutical Sciences Heart and Kidney Institute College of Pharmacy University of Houston TX USA
| | - Indira Pokkunuri
- Pharmacological and Pharmaceutical Sciences Heart and Kidney Institute College of Pharmacy University of Houston TX USA
| | - Mohammad Asghar
- Pharmacological and Pharmaceutical Sciences Heart and Kidney Institute College of Pharmacy University of Houston TX USA
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Low-protein diet supplemented with ketoacids ameliorates proteinuria in 3/4 nephrectomised rats by directly inhibiting the intrarenal renin-angiotensin system. Br J Nutr 2016; 116:1491-1501. [PMID: 27753426 DOI: 10.1017/s0007114516003536] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Low-protein diet plus ketoacids (LPD+KA) has been reported to decrease proteinuria in patients with chronic kidney diseases (CKD). However, the mechanisms have not been clarified. As over-activation of intrarenal renin-angiotensin system (RAS) has been shown to play a key role in the progression of CKD, the current study was performed to investigate the direct effects of LPD+KA on intrarenal RAS, independently of renal haemodynamics. In this study, 3/4 subtotal renal ablated rats were fed 18 % normal-protein diet (Nx-NPD), 6 % low-protein diet (Nx-LPD) or 5 % low-protein diet plus 1 % ketoacids (Nx-LPD+KA) for 12 weeks. Sham-operated rats fed NPD served as controls. The level of proteinuria and expression of renin, angiotensin II (AngII) and its type 1 receptors (AT1R) in the renal cortex were markedly higher in Nx-NPD group than in the sham group. LPD+KA significantly decreased the proteinuria and inhibited intrarenal RAS activation. To exclude renal haemodynamic impact on intrarenal RAS, the serum samples derived from the different groups were added to the culture medium of mesangial cells. It showed that the serum from Nx-NPD directly induced higher expression of AngII, AT1R, fibronectin and transforming growth factor-β1 in the mesangial cells than in the control group. Nx-LPD+KA serum significantly inhibited these abnormalities. Then, proteomics and biochemical detection suggested that the mechanisms underlying these beneficial effects of LPD+KA might be amelioration of the nutritional metabolic disorders and oxidative stress. In conclusion, LPD+KA could directly inhibit the intrarenal RAS activation, independently of renal haemodynamics, thus attenuating the proteinuria in CKD rats.
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Anupama V, George M, Dhanesh SB, Chandran A, James J, Shivakumar K. Molecular mechanisms in H2O2-induced increase in AT1 receptor gene expression in cardiac fibroblasts: A role for endogenously generated Angiotensin II. J Mol Cell Cardiol 2016; 97:295-305. [PMID: 27208880 DOI: 10.1016/j.yjmcc.2016.05.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 04/25/2016] [Accepted: 05/17/2016] [Indexed: 01/11/2023]
Abstract
The AT1 receptor (AT1R) mediates the manifold actions of angiotensin II in the cardiovascular system. This study probed the molecular mechanisms that link altered redox status to AT1R expression in cardiac fibroblasts. Real-time PCR and western blot analysis showed that H2O2 enhances AT1R mRNA and protein expression via NADPH oxidase-dependent reactive oxygen species induction. Activation of NF-κB and AP-1, demonstrated by electrophoretic mobility shift assay, abolition of AT1R expression by their inhibitors, Bay-11-7085 and SR11302, respectively, and luciferase and chromatin immunoprecipitation assays confirmed transcriptional control of AT1R by NF-κB and AP-1 in H2O2-treated cells. Further, inhibition of ERK1/2, p38 MAPK and c-Jun N-terminal kinase (JNK) using chemical inhibitors or by RNA interference attenuated AT1R expression. Inhibition of the MAPKs showed that while ERK1/2 and p38 MAPK suffice for NF-κB activation, all three kinases are required for AP-1 activation. H2O2 also increased collagen type I mRNA and protein expression. Interestingly, the AT1R antagonist, candesartan, attenuated H2O2-stimulated AT1R and collagen mRNA and protein expression, suggesting that H2O2 up-regulates AT1R and collagen expression via local Angiotensin II generation, which was confirmed by real-time PCR and ELISA. To conclude, oxidative stress enhances AT1R gene expression in cardiac fibroblasts by a complex mechanism involving the redox-sensitive transcription factors NF-κB and AP-1 that are activated by the co-ordinated action of ERK1/2, p38 MAPK and JNK. Importantly, by causally linking oxidative stress to Angiotensin II and AT1R up-regulation in cardiac fibroblasts, this study offers a novel perspective on the pathogenesis of cardiovascular diseases associated with oxidative stress.
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Affiliation(s)
- V Anupama
- Division of Cellular and Molecular Cardiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum 695011, Kerala, India
| | - Mereena George
- Division of Cellular and Molecular Cardiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum 695011, Kerala, India
| | - Sivadasan Bindu Dhanesh
- Neuro Stem Cell Biology, Neurobiology Division, Rajiv Gandhi Center for Biotechnology, Trivandrum 695014, Kerala, India
| | - Aneesh Chandran
- Bacterial and Parasite Disease Biology, Tropical Disease Biology, Rajiv Gandhi Center for Biotechnology, Trivandrum 695014, Kerala, India
| | - Jackson James
- Neuro Stem Cell Biology, Neurobiology Division, Rajiv Gandhi Center for Biotechnology, Trivandrum 695014, Kerala, India
| | - K Shivakumar
- Division of Cellular and Molecular Cardiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum 695011, Kerala, India.
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Sungkaworn T, Jiarpinitnun C, Chaiyakunvat P, Chatsudthipong V. Bivalent angiotensin II suppresses oxidative stress-induced hyper-responsiveness of angiotensin II receptor type I. Eur J Med Chem 2013; 63:629-34. [DOI: 10.1016/j.ejmech.2013.02.041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Revised: 01/07/2013] [Accepted: 02/25/2013] [Indexed: 11/16/2022]
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Robertson C, George SC. Theory and practical recommendations for autocorrelation-based image correlation spectroscopy. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:080801-1. [PMID: 23224160 PMCID: PMC3414238 DOI: 10.1117/1.jbo.17.8.080801] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 07/18/2012] [Accepted: 07/20/2012] [Indexed: 05/18/2023]
Abstract
Image correlation spectroscopy (ICS) is a powerful technique for detecting arrangement of fluorophores in images. This tutorial gives background into the mathematical underpinnings of ICS, specifically image autocorrelation. The effects of various artifacts and image processing steps, including background subtraction, noise, and image morphology were examined analytically and their effects on ICS analysis modeled. A series of recommendations was built based on this analysis.
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Affiliation(s)
- Claire Robertson
- University of California, Irvine, Department of Biomedical Engineering, Irvine, California 92697
- University of California, Irvine, The Edwards Lifesciences Center for Advanced Cardiovascular Technology, Irvine, California 92697
| | - Steven C. George
- University of California, Irvine, Department of Biomedical Engineering, Irvine, California 92697
- University of California, Irvine, The Edwards Lifesciences Center for Advanced Cardiovascular Technology, Irvine, California 92697
- University of California, Irvine, Department of Chemical Engineering and Materials, Irvine, California 92697
- University of California, Irvine, Department of Medicine, Irvine, California 92697
- Address all correspondence to: Steven C. George, University of California, 2121 Engineering Hall, Irvine, California 92697. Tel:+(949) 824-8744; E-mail:
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