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SenthilKumar G, Hammond ST, Zirgibel Z, Cohen KE, Beyer AM, Freed JK. Is the peripheral microcirculation a window into the human coronary microvasculature? J Mol Cell Cardiol 2024; 193:67-77. [PMID: 38848808 DOI: 10.1016/j.yjmcc.2024.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 05/13/2024] [Accepted: 06/04/2024] [Indexed: 06/09/2024]
Abstract
An increasing body of evidence suggests a pivotal role for the microvasculature in the development of cardiovascular disease. A dysfunctional coronary microvascular network, specifically within endothelial cells-the inner most cell layer of vessels-is considered a strong, independent risk factor for future major adverse cardiac events. However, challenges exist with evaluating this critical vascular bed, as many of the currently available techniques are highly invasive and cost prohibitive. The more easily accessible peripheral microcirculation has surfaced as a potential surrogate in which to study mechanisms of coronary microvascular dysfunction and likewise may be used to predict poor cardiovascular outcomes. In this review, we critically evaluate a variety of prognostic, physiological, and mechanistic studies in humans to answer whether the peripheral microcirculation can add insight into coronary microvascular health. A conceptual framework is proposed that the health of the endothelium specifically may link the coronary and peripheral microvascular beds. This is supported by evidence showing a correlation between human coronary and peripheral endothelial function in vivo. Although not a replacement for investigating and understanding coronary microvascular function, the microvascular endothelium from the periphery responds similarly to (patho)physiological stress and may be leveraged to explore potential therapeutic pathways to mitigate stress-induced damage.
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Affiliation(s)
- Gopika SenthilKumar
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States; Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States; Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Stephen T Hammond
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States; Division of Cardiovascular Medicine, Department of Medicine, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Zachary Zirgibel
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States; Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Katie E Cohen
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States; Division of Cardiovascular Medicine, Department of Medicine, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Andreas M Beyer
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States; Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States; Division of Cardiovascular Medicine, Department of Medicine, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Julie K Freed
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States; Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States; Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States.
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2
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Ali MA, Gioscia-Ryan R, Yang D, Sutton NR, Tyrrell DJ. Cardiovascular aging: spotlight on mitochondria. Am J Physiol Heart Circ Physiol 2024; 326:H317-H333. [PMID: 38038719 DOI: 10.1152/ajpheart.00632.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 11/28/2023] [Accepted: 11/29/2023] [Indexed: 12/02/2023]
Abstract
Mitochondria are cellular organelles critical for ATP production and are particularly relevant to cardiovascular diseases including heart failure, atherosclerosis, ischemia-reperfusion injury, and cardiomyopathies. With advancing age, even in the absence of clinical disease, mitochondrial homeostasis becomes disrupted (e.g., redox balance, mitochondrial DNA damage, oxidative metabolism, and mitochondrial quality control). Mitochondrial dysregulation leads to the accumulation of damaged and dysfunctional mitochondria, producing excessive reactive oxygen species and perpetuating mitochondrial dysfunction. In addition, mitochondrial DNA, cardiolipin, and N-formyl peptides are potent activators of cell-intrinsic and -extrinsic inflammatory pathways. These age-related mitochondrial changes contribute to the development of cardiovascular diseases. This review covers the impact of aging on mitochondria and links these mechanisms to therapeutic implications for age-associated cardiovascular diseases.
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Affiliation(s)
- Md Akkas Ali
- Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Rachel Gioscia-Ryan
- Department of Anesthesiology, Michigan Medicine, University of Michigan, Ann Arbor, Michigan, United States
| | - Dongli Yang
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States
| | - Nadia R Sutton
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, United States
| | - Daniel J Tyrrell
- Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama, United States
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3
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Ellis PS, Martins RR, Thompson EJ, Farhat A, Renshaw SA, Henriques CM. A subset of gut leukocytes has telomerase-dependent "hyper-long" telomeres and require telomerase for function in zebrafish. Immun Ageing 2022; 19:31. [PMID: 35820929 PMCID: PMC9277892 DOI: 10.1186/s12979-022-00287-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 06/17/2022] [Indexed: 11/13/2022]
Abstract
BACKGROUND Telomerase, the enzyme capable of elongating telomeres, is usually restricted in human somatic cells, which contributes to progressive telomere shortening with cell-division and ageing. T and B-cells cells are somatic cells that can break this rule and can modulate telomerase expression in a homeostatic manner. Whereas it seems intuitive that an immune cell type that depends on regular proliferation outbursts for function may have evolved to modulate telomerase expression it is less obvious why others may also do so, as has been suggested for macrophages and neutrophils in some chronic inflammation disease settings. The gut has been highlighted as a key modulator of systemic ageing and is a key tissue where inflammation must be carefully controlled to prevent dysfunction. How telomerase may play a role in innate immune subtypes in the context of natural ageing in the gut, however, remains to be determined. RESULTS Using the zebrafish model, we show that subsets of gut immune cells have telomerase-dependent"hyper-long" telomeres, which we identified as being predominantly macrophages and dendritics (mpeg1.1+ and cd45+mhcII+). Notably, mpeg1.1+ macrophages have much longer telomeres in the gut than in their haematopoietic tissue of origin, suggesting that there is modulation of telomerase in these cells, in the gut. Moreover, we show that a subset of gut mpeg1.1+ cells express telomerase (tert) in young WT zebrafish, but that the relative proportion of these cells decreases with ageing. Importantly, this is accompanied by telomere shortening and DNA damage responses with ageing and a telomerase-dependent decrease in expression of autophagy and immune activation markers. Finally, these telomerase-dependent molecular alterations are accompanied by impaired phagocytosis of E. coli and increased gut permeability in vivo. CONCLUSIONS Our data show that limiting levels of telomerase lead to alterations in gut immunity, impacting on the ability to clear pathogens in vivo. These are accompanied by increased gut permeability, which, together, are likely contributors to local and systemic tissue degeneration and increased susceptibility to infection with ageing.
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Affiliation(s)
- Pam S Ellis
- The Bateson Centre, MRC-Arthritis Research UK Centre for Integrated Research Into Musculoskeletal Ageing and Department of Oncology and Metabolism, Healthy Lifespan Institute, University of Sheffield Medical School, Sheffield, UK
| | - Raquel R Martins
- The Bateson Centre, MRC-Arthritis Research UK Centre for Integrated Research Into Musculoskeletal Ageing and Department of Oncology and Metabolism, Healthy Lifespan Institute, University of Sheffield Medical School, Sheffield, UK
| | - Emily J Thompson
- The Bateson Centre, MRC-Arthritis Research UK Centre for Integrated Research Into Musculoskeletal Ageing and Department of Oncology and Metabolism, Healthy Lifespan Institute, University of Sheffield Medical School, Sheffield, UK
| | - Asma Farhat
- The Bateson Centre, MRC-Arthritis Research UK Centre for Integrated Research Into Musculoskeletal Ageing and Department of Oncology and Metabolism, Healthy Lifespan Institute, University of Sheffield Medical School, Sheffield, UK
| | - Stephen A Renshaw
- The Bateson Centre and Department of Infection, Immunity and Cardiovascular Disease, Medical School, University of Sheffield, Sheffield, UK
| | - Catarina M Henriques
- The Bateson Centre, MRC-Arthritis Research UK Centre for Integrated Research Into Musculoskeletal Ageing and Department of Oncology and Metabolism, Healthy Lifespan Institute, University of Sheffield Medical School, Sheffield, UK.
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4
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Kant S, Tran KV, Kvandova M, Caliz AD, Yoo HJ, Learnard H, Dolan AC, Craige SM, Hall JD, Jiménez JM, St. Hilaire C, Schulz E, Kröller-Schön S, Keaney JF. PGC1α Regulates the Endothelial Response to Fluid Shear Stress via Telomerase Reverse Transcriptase Control of Heme Oxygenase-1. Arterioscler Thromb Vasc Biol 2022; 42:19-34. [PMID: 34789002 PMCID: PMC8702461 DOI: 10.1161/atvbaha.121.317066] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
OBJECTIVE Fluid shear stress (FSS) is known to mediate multiple phenotypic changes in the endothelium. Laminar FSS (undisturbed flow) is known to promote endothelial alignment to flow, which is key to stabilizing the endothelium and rendering it resistant to atherosclerosis and thrombosis. The molecular pathways responsible for endothelial responses to FSS are only partially understood. In this study, we determine the role of PGC1α (peroxisome proliferator gamma coactivator-1α)-TERT (telomerase reverse transcriptase)-HMOX1 (heme oxygenase-1) during shear stress in vitro and in vivo. Approach and Results: Here, we have identified PGC1α as a flow-responsive gene required for endothelial flow alignment in vitro and in vivo. Compared with oscillatory FSS (disturbed flow) or static conditions, laminar FSS (undisturbed flow) showed increased PGC1α expression and its transcriptional coactivation. PGC1α was required for laminar FSS-induced expression of TERT in vitro and in vivo via its association with ERRα(estrogen-related receptor alpha) and KLF (Kruppel-like factor)-4 on the TERT promoter. We found that TERT inhibition attenuated endothelial flow alignment, elongation, and nuclear polarization in response to laminar FSS in vitro and in vivo. Among the flow-responsive genes sensitive to TERT status, HMOX1 was required for endothelial alignment to laminar FSS. CONCLUSIONS These data suggest an important role for a PGC1α-TERT-HMOX1 axis in the endothelial stabilization response to laminar FSS.
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Affiliation(s)
- Shashi Kant
- Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
- Equal contribution
| | - Khanh-Van Tran
- Division of Cardiovascular Medicine, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01655
- Equal contribution
| | - Miroslava Kvandova
- Department of Cardiology, University Medical Center, Mainz, Germany
- Equal contribution
| | - Amada D. Caliz
- Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
| | - Hyung-Jin Yoo
- Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
| | - Heather Learnard
- Division of Cardiovascular Medicine, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01655
| | - Ana C. Dolan
- Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
| | - Siobhan M. Craige
- Department of Human Nutrition, Foods, and Exercise, Virginia Tech, Blackburg, VA 24061
| | - Joshua D. Hall
- Department of Mechanical and Industrial Engineering, University of Massachusetts, Amherst, MA 01003
| | - Juan M. Jiménez
- Department of Mechanical and Industrial Engineering, University of Massachusetts, Amherst, MA 01003
| | - Cynthia St. Hilaire
- Division of Cardiology, Departments of Medicine and Bioengineering, and the Pittsburgh Heart, Lung, and Blood Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261
| | - Eberhard Schulz
- Department of Cardiology, Allgemeines Krankenhaus, Celle, Germany
| | | | - John F. Keaney
- Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
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5
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Beyer AM, Norwood Toro LE, Hughes WE, Young M, Clough AV, Gao F, Medhora M, Audi SH, Jacobs ER. Autophagy, TERT, and mitochondrial dysfunction in hyperoxia. Am J Physiol Heart Circ Physiol 2021; 321:H985-H1003. [PMID: 34559580 PMCID: PMC8616608 DOI: 10.1152/ajpheart.00166.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 08/31/2021] [Accepted: 09/16/2021] [Indexed: 02/06/2023]
Abstract
Ventilation with gases containing enhanced fractions of oxygen is the cornerstone of therapy for patients with hypoxia and acute respiratory distress syndrome. Yet, hyperoxia treatment increases free reactive oxygen species (ROS)-induced lung injury, which is reported to disrupt autophagy/mitophagy. Altered extranuclear activity of the catalytic subunit of telomerase, telomerase reverse transcriptase (TERT), plays a protective role in ROS injury and autophagy in the systemic and coronary endothelium. We investigated interactions between autophagy/mitophagy and TERT that contribute to mitochondrial dysfunction and pulmonary injury in cultured rat lung microvascular endothelial cells (RLMVECs) exposed in vitro, and rat lungs exposed in vivo to hyperoxia for 48 h. Hyperoxia-induced mitochondrial damage in rat lungs [TOMM20, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)], which was paralleled by increased markers of inflammation [myeloperoxidase (MPO), IL-1β, TLR9], impaired autophagy signaling (Beclin-1, LC3B-II/1, and p62), and decreased the expression of TERT. Mitochondrial-specific autophagy (mitophagy) was not altered, as hyperoxia increased expression of Pink1 but not Parkin. Hyperoxia-induced mitochondrial damage (TOMM20) was more pronounced in rats that lack the catalytic subunit of TERT and resulted in a reduction in cellular proliferation rather than cell death in RLMVECs. Activation of TERT or autophagy individually offset mitochondrial damage (MTT). Combined activation/inhibition failed to alleviate hyperoxic-induced mitochondrial damage in vitro, whereas activation of autophagy in vivo decreased mitochondrial damage (MTT) in both wild type (WT) and rats lacking TERT. Functionally, activation of either TERT or autophagy preserved transendothelial membrane resistance. Altogether, these observations show that activation of autophagy/mitophagy and/or TERT mitigate loss of mitochondrial function and barrier integrity in hyperoxia.NEW & NOTEWORTHY In cultured pulmonary artery endothelial cells and in lungs exposed in vivo to hyperoxia, autophagy is activated, but clearance of autophagosomes is impaired in a manner that suggests cross talk between TERT and autophagy. Stimulation of autophagy prevents hyperoxia-induced decreases in mitochondrial metabolism and sustains monolayer resistance. Hyperoxia increases mitochondrial outer membrane (TOMM20) protein, decreases mitochondrial function, and reduces cellular proliferation without increasing cell death.
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Affiliation(s)
- Andreas M Beyer
- Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Laura E Norwood Toro
- Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - William E Hughes
- Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Micaela Young
- Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Anne V Clough
- Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
- Research Service, Zablocki Veterans Affairs Medical Center, Milwaukee Wisconsin
- Department of Mathematics, Statistics and Computer Science, Marquette University, Milwaukee, Wisconsin
| | - Feng Gao
- Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Meetha Medhora
- Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
- Research Service, Zablocki Veterans Affairs Medical Center, Milwaukee Wisconsin
| | - Said H Audi
- Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
- Research Service, Zablocki Veterans Affairs Medical Center, Milwaukee Wisconsin
- Department of Biomedical Engineering, Marquette University, Milwaukee, Wisconsin
| | - Elizabeth R Jacobs
- Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
- Research Service, Zablocki Veterans Affairs Medical Center, Milwaukee Wisconsin
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6
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McCarthy CG, Chakraborty S, Singh G, Yeoh BS, Schreckenberger ZJ, Singh A, Mell B, Bearss NR, Yang T, Cheng X, Vijay-Kumar M, Wenceslau CF, Joe B. Ketone body β-hydroxybutyrate is an autophagy-dependent vasodilator. JCI Insight 2021; 6:e149037. [PMID: 34499623 PMCID: PMC8564907 DOI: 10.1172/jci.insight.149037] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 09/08/2021] [Indexed: 12/14/2022] Open
Abstract
Autophagy has long been associated with longevity, and it is well established that autophagy reverts and prevents vascular deterioration associated with aging and cardiovascular diseases. Currently, our understanding of how autophagy benefits the vasculature is centered on the premise that reduced autophagy leads to the accumulation of cellular debris, resulting in inflammation and oxidative stress, which are then reversed by reconstitution or upregulation of autophagic activity. Evolutionarily, autophagy also functions to mobilize endogenous nutrients in response to starvation. Therefore, we hypothesized that the biosynthesis of the most physiologically abundant ketone body, β-hydroxybutyrate (βHB), would be autophagy dependent and exert vasodilatory effects via its canonical receptor, Gpr109a. To the best of our knowledge, we have revealed for the first time that the biosynthesis of βHB can be impaired by preventing autophagy. Subsequently, βHB caused potent vasodilation via potassium channels but not Gpr109a. Finally, we observed that chronic consumption of a high-salt diet negatively regulates both βHB biosynthesis and hepatic autophagy and that reconstitution of βHB bioavailability prevents high-salt diet–induced endothelial dysfunction. In summary, this work offers an alternative mechanism to the antiinflammatory and antioxidative stress hypothesis of autophagy-dependent vasculoprotection. Furthermore, it reveals a direct mechanism by which ketogenic interventions (e.g., intermittent fasting) improve vascular health.
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7
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Ranadive SM, Dillon GA, Mascone SE, Alexander LM. Vascular Health Triad in Humans With Hypertension-Not the Usual Suspects. Front Physiol 2021; 12:746278. [PMID: 34658930 PMCID: PMC8517241 DOI: 10.3389/fphys.2021.746278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 08/25/2021] [Indexed: 11/13/2022] Open
Abstract
Hypertension (HTN) affects more than one-third of the US population and remains the top risk factor for the development of cardiovascular disease (CVD). Identifying the underlying mechanisms for developing HTN are of critical importance because the risk of developing CVD doubles with ∼20 mmHg increase in systolic blood pressure (BP). Endothelial dysfunction, especially in the resistance arteries, is the primary site for initiation of sub-clinical HTN. Furthermore, inflammation and reactive oxygen and nitrogen species (ROS/RNS) not only influence the endothelium independently, but also have a synergistic influence on each other. Together, the interplay between inflammation, ROS and vascular dysfunction is referred to as the vascular health triad, and affects BP regulation in humans. While the interplay of the vascular health triad is well established, new underlying mechanistic targets are under investigation, including: Inducible nitric oxide synthase, hydrogen peroxide, hydrogen sulfide, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and nuclear factor activated T cells. This review outlines the role of these unusual suspects in vascular health and function in humans. This review connects the dots using these unusual suspects underlying inflammation, ROS and vascular dysfunction especially in individuals at risk of or with diagnosed HTN based on novel studies performed in humans.
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Affiliation(s)
- Sushant M Ranadive
- Department of Kinesiology, University of Maryland, College Park, College Park, MD, United States
| | - Gabrielle A Dillon
- Department of Kinesiology, The Pennsylvania State University, University Park, PA, United States.,Center for Healthy Aging, The Pennsylvania State University, University Park, PA, United States
| | - Sara E Mascone
- Department of Kinesiology, University of Maryland, College Park, College Park, MD, United States
| | - Lacy M Alexander
- Department of Kinesiology, The Pennsylvania State University, University Park, PA, United States.,Center for Healthy Aging, The Pennsylvania State University, University Park, PA, United States
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8
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Reho JJ, Guo DF, Beyer AM, Wegman-Points L, Pierce GL, Rahmouni K. Vascular effects of disrupting endothelial mTORC1 signaling in obesity. Am J Physiol Regul Integr Comp Physiol 2021; 321:R228-R237. [PMID: 34189960 PMCID: PMC8409911 DOI: 10.1152/ajpregu.00113.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 06/11/2021] [Accepted: 06/28/2021] [Indexed: 11/22/2022]
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) signaling complex is emerging as a critical regulator of cardiovascular function with alterations in this pathway implicated in cardiovascular diseases. In this study, we used animal models and human tissues to examine the role of vascular mTORC1 signaling in the endothelial dysfunction associated with obesity. In mice, obesity induced by high-fat/high-sucrose diet feeding for ∼2 mo resulted in aortic endothelial dysfunction without appreciable changes in vascular mTORC1 signaling. On the other hand, chronic high-fat diet feeding (45% or 60% kcal: ∼9 mo) in mice resulted in endothelial dysfunction associated with elevated vascular mTORC1 signaling. Endothelial cells and visceral adipose vessels isolated from obese humans display a trend toward elevated mTORC1 signaling. Surprisingly, genetic disruption of endothelial mTORC1 signaling through constitutive or tamoxifen inducible deletion of endothelial Raptor (critical subunit of mTORC1) did not prevent or rescue the endothelial dysfunction associated with high-fat diet feeding in mice. Endothelial mTORC1 deficiency also failed to reverse the endothelial dysfunction evoked by a high-fat/high-sucrose diet in mice. Taken together, these data show increased vascular mTORC1 signaling in obesity, but this vascular mTORC1 activation appears not to be required for the development of endothelial impairment in obesity.
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Affiliation(s)
- John J Reho
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, Iowa
| | - Deng-Fu Guo
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, Iowa
- Obesity Research and Education Initiative, University of Iowa, Iowa City, Iowa
| | - Andreas M Beyer
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | | | - Gary L Pierce
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa
- Department of Health and Human Physiology, University of Iowa, Iowa City, Iowa
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa
| | - Kamal Rahmouni
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, Iowa
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa
- Obesity Research and Education Initiative, University of Iowa, Iowa City, Iowa
- Iowa City Veterans Affairs Health Care System, Iowa City, Iowa
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9
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Blasiak J, Szczepanska J, Fila M, Pawlowska E, Kaarniranta K. Potential of Telomerase in Age-Related Macular Degeneration-Involvement of Senescence, DNA Damage Response and Autophagy and a Key Role of PGC-1α. Int J Mol Sci 2021; 22:ijms22137194. [PMID: 34281248 PMCID: PMC8268995 DOI: 10.3390/ijms22137194] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 06/29/2021] [Accepted: 07/01/2021] [Indexed: 02/07/2023] Open
Abstract
Age-related macular degeneration (AMD), the main cause of vision loss in the elderly, is associated with oxidation in the retina cells promoting telomere attrition. Activation of telomerase was reported to improve macular functions in AMD patients. The catalytic subunit of human telomerase (hTERT) may directly interact with proteins important for senescence, DNA damage response, and autophagy, which are impaired in AMD. hTERT interaction with mTORC1 (mTOR (mechanistic target of rapamycin) complex 1) and PINK1 (PTEN-induced kinase 1) activates macroautophagy and mitophagy, respectively, and removes cellular debris accumulated over AMD progression. Ectopic expression of telomerase in retinal pigment epithelium (RPE) cells lengthened telomeres, reduced senescence, and extended their lifespan. These effects provide evidence for the potential of telomerase in AMD therapy. Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) may be involved in AMD pathogenesis through decreasing oxidative stress and senescence, regulation of vascular endothelial growth factor (VEGF), and improving autophagy. PGC-1α and TERT form an inhibitory positive feedback loop. In conclusion, telomerase activation and its ectopic expression in RPE cells, as well as controlled clinical trials on the effects of telomerase activation in AMD patients, are justified and should be assisted by PGC-1α modulators to increase the therapeutic potential of telomerase in AMD.
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Affiliation(s)
- Janusz Blasiak
- Department of Molecular Genetics, Faculty of Biology and Environmental Protection, University of Lodz, Pomorska 141/143, 90-236 Lodz, Poland
- Correspondence: (J.B.); (K.K.)
| | - Joanna Szczepanska
- Department of Pediatric Dentistry, Medical University of Lodz, 92-216 Lodz, Poland;
| | - Michal Fila
- Department of Developmental Neurology and Epileptology, Polish Mother’s Memorial Hospital Research Institute, 93-338 Lodz, Poland;
| | - Elzbieta Pawlowska
- Department of Orthodontics, Medical University of Lodz, 92-217 Lodz, Poland;
| | - Kai Kaarniranta
- Department of Ophthalmology, University of Eastern Finland, 70210 Kuopio, Finland
- Department of Ophthalmology, Kuopio University Hospital, 70210 Kuopio, Finland
- Correspondence: (J.B.); (K.K.)
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10
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Hoffmann J, Richardson G, Haendeler J, Altschmied J, Andrés V, Spyridopoulos I. Telomerase as a Therapeutic Target in Cardiovascular Disease. Arterioscler Thromb Vasc Biol 2021; 41:1047-1061. [PMID: 33504179 DOI: 10.1161/atvbaha.120.315695] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Shortened telomeres have been linked to numerous chronic diseases, most importantly coronary artery disease, but the underlying mechanisms remain ill defined. Loss-of-function mutations and deletions in telomerase both accelerate telomere shortening but do not necessarily lead to a clinical phenotype associated with atherosclerosis, questioning the causal role of telomere length in cardiac pathology. The differential extranuclear functions of the 2 main components of telomerase, telomerase reverse transcriptase and telomerase RNA component, offer important clues about the complex relationship between telomere length and cardiovascular pathology. In this review, we critically discuss relevant preclinical models, genetic disorders, and clinical studies to elucidate the impact of telomerase in cardiovascular disease and its potential role as a therapeutic target. We suggest that the antioxidative function of mitochondrial telomerase reverse transcriptase might be atheroprotective, making it a potential target for clinical trials. Graphic Abstract: A graphic abstract is available for this article.
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Affiliation(s)
- Jedrzej Hoffmann
- Department of Medicine, Cardiology, Goethe University Hospital, Frankfurt, Germany (J.H.)
| | - Gavin Richardson
- Institute of Biosciences, Newcastle University, United Kingdom (G.R.)
| | - Judith Haendeler
- Institute of Clinical Chemistry and Laboratory Diagnostic, Medical Faculty and University Hospital Duesseldorf and Heinrich-Heine-University Duesseldorf, Germany (J.H., J.A.)
| | - Joachim Altschmied
- Institute of Clinical Chemistry and Laboratory Diagnostic, Medical Faculty and University Hospital Duesseldorf and Heinrich-Heine-University Duesseldorf, Germany (J.H., J.A.).,IUF - Leibniz Research Institute for Environmental Medicine (J.A.)
| | - Vicente Andrés
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain (V.A.).,Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Spain (V.A.)
| | - Ioakim Spyridopoulos
- Translational and Clinical Research Institute, Newcastle University, United Kingdom (I.S.).,Freeman Hospital, Cardiothoracic Centre, Newcastle Upon Tyne Hospital Trust, United Kingdom (I.S.)
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