1
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Sekhon S, Barger PM, Abarbanell AM. Outcomes 60 years after surgical valvotomy for isolated congenital pulmonary valve stenosis. J Card Surg 2021; 36:1531-1533. [PMID: 33522622 DOI: 10.1111/jocs.15276] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/30/2020] [Accepted: 12/21/2020] [Indexed: 11/29/2022]
Abstract
Congenital pulmonary valve stenosis (PVS) is a common congenital heart defect. In the infancy of cardiac surgery, open surgical valvotomy or closed surgical transventricular pulmonary valvotomy (Brock procedure) were the mainstays of therapy. We report the longest-known published follow-up of two women who as young children underwent pulmonary valvotomy for PVS and subsequent uncomplicated open pulmonary valve replacement over 60 years later.
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Affiliation(s)
- Subhjit Sekhon
- Department of Obstetrics and Gynecology, University of Missouri-Kansas City School of Medicine, Kansas, Missouri, USA
| | - Philip M Barger
- Cardiovascular Division, Department of Internal Medicine, Center for Adults with Congenital Heart Disease, Washington University in St. Louis School of Medicine, St. Louis, Missouri, USA
| | - Aaron M Abarbanell
- Section of Pediatric Cardiothoracic Surgery, Department of Surgery, Washington University in St. Louis School of Medicine, St. Louis, Missouri, USA
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2
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Soares A, Mansour E, Puritz A, Zhao M, Cao C, Barger PM, Foraker R, Racette SB, Peterson LR. Aerobic Capacity (V̇O2peak) In Congenital Heart Disease Versus Heart Failure: Prognostic Implications. J Card Fail 2020. [DOI: 10.1016/j.cardfail.2020.09.134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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3
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Weinheimer CJ, Kovacs A, Evans S, Matkovich SJ, Barger PM, Mann DL. Load-Dependent Changes in Left Ventricular Structure and Function in a Pathophysiologically Relevant Murine Model of Reversible Heart Failure. Circ Heart Fail 2019; 11:e004351. [PMID: 29716898 DOI: 10.1161/circheartfailure.117.004351] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 03/22/2018] [Indexed: 01/19/2023]
Abstract
BACKGROUND To better understand reverse left ventricular (LV) remodeling, we developed a murine model wherein mice develop LV remodeling after transverse aortic constriction (TAC) and a small apical myocardial infarct (MI) and undergo reverse LV remodeling after removal of the aortic band. METHODS AND RESULTS Mice studied were subjected to sham (n=6) surgery or TAC+MI (n=12). Two weeks post-TAC+MI, 1 group underwent debanding (referred to as heart failure debanding [HF-DB] mice; n=6), whereas the aortic band remained in a second group (heart failure [HF] group; n=6). LV remodeling was evaluated by 2D echocardiography at 1 day, 2 weeks and 6 weeks post-TAC+MI. The hearts were analyzed by transcriptional profiling at 4 and 6 weeks and histologically at 6 weeks. Debanding normalized LV volumes, LV mass, and cardiac myocyte hypertrophy at 6 weeks in HF-DB mice, with no difference in myofibrillar collagen in the HF and HF-DB mice. LV ejection fraction and radial strain improved after debanding; however, both remained decreased in the HF-DB mice relative to sham and were not different from HF mice at 6 weeks. Hemodynamic unloading in the HF-DB mice was accompanied by a 35% normalization of the HF genes at 2 weeks and 80% of the HF genes at 4 weeks. CONCLUSIONS Hemodynamic unloading of a pathophysiologically relevant mouse model of HF results in normalization of LV structure, incomplete recovery of LV function, and incomplete reversal of the HF transcriptional program. The HF-DB mouse model may provide novel insights into mechanisms of reverse LV remodeling.
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Affiliation(s)
- Carla J Weinheimer
- Center for Cardiovascular Research, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO
| | - Attila Kovacs
- Center for Cardiovascular Research, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO
| | - Sarah Evans
- Center for Cardiovascular Research, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO
| | - Scot J Matkovich
- Center for Cardiovascular Research, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO
| | - Philip M Barger
- Center for Cardiovascular Research, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO
| | - Douglas L Mann
- Center for Cardiovascular Research, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO.
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4
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Rocha-Resende C, Weinheimer C, Bajpai G, Adamo L, Matkovich SJ, Schilling J, Barger PM, Lavine KJ, Mann DL. Immunomodulatory role of non-neuronal cholinergic signaling in myocardial injury. JCI Insight 2019; 5:128961. [PMID: 31162139 DOI: 10.1172/jci.insight.128961] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Whereas prior studies have demonstrated an important immunomodulatory role for the neuronal cholinergic system in the heart, the role of the non-neuronal cholinergic system is not well understood. To address the immunomodulatory role of the non-neuronal cholinergic system in the heart we used a previously validated diphtheria toxin (DT)-induced cardiomyocyte ablation model (Rosa26-DTMlc2v-Cre mice). DT-injected Rosa26-DTMlc2v-Cre mice were treated with diluent or Pyridostigmine Bromide (PYR), a reversible cholinesterase inhibitor. PYR treatment resulted in increased survival and decreased numbers of MHC-IIlowCCR2+ macrophages in DT-injected Rosa26-DTMlc2v-Cre mice compared to diluent treated Rosa26-DTMlc2v-Cre mice. Importantly, the expression of CCL2/7 mRNA and protein was reduced in the hearts of PYR-treated mice. Backcrossing Rosa26-DTMlc2v-Cre mice with a transgenic mouse line (Chat-ChR2) that constitutively overexpresses the vesicular acetylcholine transporter (VAChT) resulted in decreased expression of Ccl2/7 mRNA and decreased numbers of CD68+ cells in DT-injured Rosa26-DTMlc2v-Cre/Chat-ChR2 mouse hearts, consistent with the pharmacologic studies with PYR. In vitro studies with cultures of LPS-stimulated peritoneal macrophages revealed a concentration-dependent reduction in CCL2 secretion following stimulation with ACh, nicotine and muscarine. Viewed together, these findings reveal a previously unappreciated immunomodulatory role for the non-neuronal cholinergic system in regulating homeostatic responses in the heart following tissue injury.
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5
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Adamo L, Staloch LJ, Rocha-Resende C, Matkovich SJ, Jiang W, Bajpai G, Weinheimer CJ, Kovacs A, Schilling JD, Barger PM, Bhattacharya D, Mann DL. Modulation of subsets of cardiac B lymphocytes improves cardiac function after acute injury. JCI Insight 2018; 3:120137. [PMID: 29875326 DOI: 10.1172/jci.insight.120137] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 04/24/2018] [Indexed: 12/11/2022] Open
Abstract
Despite the long-standing recognition that the immune response to acute myocardial injury contributes to adverse left ventricular (LV) remodeling, it has not been possible to effectively target this clinically. Using 2 different in vivo models of acute myocardial injury, we show that pirfenidone confers beneficial effects in the murine heart through an unexpected mechanism that depends on cardiac B lymphocytes. Naive hearts contained a large population of CD19+CD11b-CD23-CD21-IgD+IgMlo lymphocytes, and 2 smaller populations of CD19+CD11b+ B1a and B1b cells. In response to tissue injury, there was an increase in neutrophils, monocytes, macrophages, as well as an increase in CD19+ CD11b- B lymphocytes. Treatment with pirfenidone had no effect on the number of neutrophils, monocytes, or macrophages, but decreased CD19+CD11b- lymphocytes. B cell depletion abrogated the beneficial effects of pirfenidone. In vitro studies demonstrated that stimulation with lipopolysaccharide and extracts from necrotic cells activated CD19+ lymphocytes through a TIRAP-dependent pathway. Treatment with pirfenidone attenuated this activation of B cells. These findings reveal a previously unappreciated complexity of myocardial B lymphocytes within the inflammatory infiltrate triggered by cardiac injury and suggest that pirfenidone exerts beneficial effects in the heart through a unique mechanism that involves modulation of cardiac B lymphocytes.
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Affiliation(s)
- Luigi Adamo
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Lora J Staloch
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Cibele Rocha-Resende
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Scot J Matkovich
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Wenlong Jiang
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Geetika Bajpai
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Carla J Weinheimer
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Attila Kovacs
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Joel D Schilling
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Philip M Barger
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | | | - Douglas L Mann
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
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6
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Evans S, Tzeng HP, Veis DJ, Matkovich S, Weinheimer C, Kovacs A, Barger PM, Mann DL. TNF receptor-activated factor 2 mediates cardiac protection through noncanonical NF-κB signaling. JCI Insight 2018; 3:98278. [PMID: 29415884 DOI: 10.1172/jci.insight.98278] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 01/05/2018] [Indexed: 12/29/2022] Open
Abstract
To elucidate the mechanisms responsible for cytoprotective effects of TNF receptor-activated factor 2 (TRAF2) in the heart, we employed genetic gain- and loss-of-function studies ex vivo and in vivo in mice with cardiac-restricted overexpression of TRAF2 (Myh6-TRAF2LC). Crossing Myh6-TRAF2LC mice with mice lacking canonical signaling (Myh6-TRAF2LC/Myh6-IκBαΔN) abrogated the cytoprotective effects of TRAF2 ex vivo. In contrast, inhibiting the JAK/STAT pathway did not abrogate the cytoprotective effects of TRAF2. Transcriptional profiling of WT, Myh6-TRAF2LC, and Myh6-TRAF2LC/Myh6-IκBαΔN mouse hearts suggested that the noncanonical NF-κB signaling pathway was upregulated in the Myh6-TRAF2LC mouse hearts. Western blotting and ELISA for the NF-κB family proteins p50, p65, p52, and RelB on nuclear and cytoplasmic extracts from naive 12-week-old WT, Myh6-TRAF2LC, and Myh6-TRAF2LC/Myh6-IκBαΔN mouse hearts showed increased expression levels and increased DNA binding of p52 and RelB, whereas there was no increase in expression or DNA binding of the p50 and p65 subunits. Crossing Myh6-TRAF2LC mice with RelB-/+ mice (Myh6-TRAF2LC/RelB-/+) attenuated the cytoprotective effects of TRAF2 ex vivo and in vivo. Viewed together, these results suggest that crosstalk between the canonical and noncanonical NF-κB signaling pathways is required for mediating the cytoprotective effects of TRAF2.
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Affiliation(s)
- Sarah Evans
- Center for Cardiovascular Research, Cardiovascular Division and
| | - Huei-Ping Tzeng
- Center for Cardiovascular Research, Cardiovascular Division and
| | - Deborah J Veis
- Division of Bone and Mineral Metabolism, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Scot Matkovich
- Center for Cardiovascular Research, Cardiovascular Division and
| | | | - Attila Kovacs
- Center for Cardiovascular Research, Cardiovascular Division and
| | - Philip M Barger
- Center for Cardiovascular Research, Cardiovascular Division and
| | - Douglas L Mann
- Center for Cardiovascular Research, Cardiovascular Division and
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7
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Carvajal HG, Lindley KJ, Shah T, Brar AK, Barger PM, Billadello JJ, Eghtesady P. Impact of pregnancy on autograft dilatation and aortic valve function following the Ross procedure. CONGENIT HEART DIS 2017; 13:217-221. [PMID: 29250922 DOI: 10.1111/chd.12554] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 11/06/2017] [Indexed: 11/28/2022]
Abstract
OBJECTIVE The effects of pregnancy on autograft dilatation and neoaortic valve function in patients with a Ross procedure have not been studied. We sought to evaluate the effect of pregnancy on autograft dilatation and valve function in these patients with the goal of determining whether pregnancy is safe after the Ross procedure. DESIGN A retrospective chart review of female patients who underwent a Ross procedure was conducted. PATIENTS Medical records for 51 patients were reviewed. Among the 33 patients who met inclusion criteria, 11 became pregnant after surgery and 22 did not. OUTCOME MEASURES Echocardiographic reports were used to record aortic root diameter and aortic insufficiency before, during, and after pregnancy. Patient's charts were reviewed for reinterventions and complications. Primary endpoints included reinterventions, aortic root dilation of ≥5 cm, aortic insufficiency degree ≥ moderate, and death. RESULTS There were 18 pregnancies carried beyond 20 weeks in 11 patients. There was no significant difference in aortic root diameter between nulliparous patients and parous patients prior to their first pregnancy (3.53 ± 0.44 vs 3.57 ± 0.69 cm, P = .74). There was no significant change in aortic root diameter after first pregnancy (3.7 ± 0.4 cm, P = .056) although there was significant dilatation after the second (4.3 ± 0.7 cm, P = .009) and third (4.5 ± 0.7 cm, P = .009) pregnancies. Freedom from combined endpoints was significantly higher for patients in the pregnancy group than those in the nonpregnancy group (P = .002). CONCLUSIONS Pregnancy was not associated with significantly increased adverse events in patients following the Ross procedure. Special care should be taken after the first pregnancy, as multiparity may lead to increased neoaortic dilatation.
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Affiliation(s)
- Horacio G Carvajal
- Section of Pediatric Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA.,Faculty of Health Sciences, Universidad Anahuac Mexico Norte, Huixquilucan, Mexico
| | - Kathryn J Lindley
- Cardiovascular Division, Department of Internal Medicine, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Trupti Shah
- Section of Pediatric Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Anoop K Brar
- Section of Pediatric Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Philip M Barger
- Cardiovascular Division, Department of Internal Medicine, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Joseph J Billadello
- Cardiovascular Division, Department of Internal Medicine, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Pirooz Eghtesady
- Section of Pediatric Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
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8
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Jia Y, Chang HC, Schipma MJ, Liu J, Shete V, Liu N, Sato T, Thorp EB, Barger PM, Zhu YJ, Viswakarma N, Kanwar YS, Ardehali H, Thimmapaya B, Reddy JK. Cardiomyocyte-Specific Ablation of Med1 Subunit of the Mediator Complex Causes Lethal Dilated Cardiomyopathy in Mice. PLoS One 2016; 11:e0160755. [PMID: 27548259 PMCID: PMC4993490 DOI: 10.1371/journal.pone.0160755] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 07/25/2016] [Indexed: 11/19/2022] Open
Abstract
Mediator, an evolutionarily conserved multi-protein complex consisting of about 30 subunits, is a key component of the polymerase II mediated gene transcription. Germline deletion of the Mediator subunit 1 (Med1) of the Mediator in mice results in mid-gestational embryonic lethality with developmental impairment of multiple organs including heart. Here we show that cardiomyocyte-specific deletion of Med1 in mice (csMed1-/-) during late gestational and early postnatal development by intercrossing Med1fl/fl mice to α-MyHC-Cre transgenic mice results in lethality within 10 days after weaning due to dilated cardiomyopathy-related ventricular dilation and heart failure. The csMed1-/- mouse heart manifests mitochondrial damage, increased apoptosis and interstitial fibrosis. Global gene expression analysis revealed that loss of Med1 in heart down-regulates more than 200 genes including Acadm, Cacna1s, Atp2a2, Ryr2, Pde1c, Pln, PGC1α, and PGC1β that are critical for calcium signaling, cardiac muscle contraction, arrhythmogenic right ventricular cardiomyopathy, dilated cardiomyopathy and peroxisome proliferator-activated receptor regulated energy metabolism. Many genes essential for oxidative phosphorylation and proper mitochondrial function such as genes coding for the succinate dehydrogenase subunits of the mitochondrial complex II are also down-regulated in csMed1-/- heart contributing to myocardial injury. Data also showed up-regulation of about 180 genes including Tgfb2, Ace, Atf3, Ctgf, Angpt14, Col9a2, Wisp2, Nppa, Nppb, and Actn1 that are linked to cardiac muscle contraction, cardiac hypertrophy, cardiac fibrosis and myocardial injury. Furthermore, we demonstrate that cardiac specific deletion of Med1 in adult mice using tamoxifen-inducible Cre approach (TmcsMed1-/-), results in rapid development of cardiomyopathy and death within 4 weeks. We found that the key findings of the csMed1-/- studies described above are highly reproducible in TmcsMed1-/- mouse heart. Collectively, these observations suggest that Med1 plays a critical role in the maintenance of heart function impacting on multiple metabolic, compensatory and reparative pathways with a likely therapeutic potential in the management of heart failure.
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MESH Headings
- Animals
- Apoptosis
- Cadherins/genetics
- Cadherins/metabolism
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Calcium Signaling
- Cardiomyopathy, Dilated/genetics
- Cardiomyopathy, Dilated/metabolism
- Cardiomyopathy, Dilated/pathology
- Cyclic Nucleotide Phosphodiesterases, Type 1/genetics
- Cyclic Nucleotide Phosphodiesterases, Type 1/metabolism
- Embryo, Mammalian
- Energy Metabolism
- Female
- Gene Deletion
- Gene Expression Profiling
- Gene Expression Regulation
- Genes, Lethal
- Gestational Age
- Heart Failure/genetics
- Heart Failure/metabolism
- Heart Failure/pathology
- Mediator Complex Subunit 1/deficiency
- Mediator Complex Subunit 1/genetics
- Mice
- Mice, Knockout
- Mitochondria/metabolism
- Mitochondria/pathology
- Myocardial Contraction
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Peroxisome Proliferator-Activated Receptors/genetics
- Peroxisome Proliferator-Activated Receptors/metabolism
- Pregnancy
- Ryanodine Receptor Calcium Release Channel/genetics
- Ryanodine Receptor Calcium Release Channel/metabolism
- Sarcoplasmic Reticulum Calcium-Transporting ATPases/genetics
- Sarcoplasmic Reticulum Calcium-Transporting ATPases/metabolism
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Affiliation(s)
- Yuzhi Jia
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Hsiang-Chun Chang
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Matthew J. Schipma
- Next Generation Sequencing Core Facility, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Jing Liu
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Varsha Shete
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Ning Liu
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Tatsuya Sato
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Edward B. Thorp
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Philip M. Barger
- Center for Cardiovascular Research, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Yi-Jun Zhu
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Navin Viswakarma
- Department of Surgery, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Yashpal S. Kanwar
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Hossein Ardehali
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Bayar Thimmapaya
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
- * E-mail: (JKR); (BT)
| | - Janardan K. Reddy
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
- * E-mail: (JKR); (BT)
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9
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Zhang W, Lavine KJ, Epelman S, Evans SA, Weinheimer CJ, Barger PM, Mann DL. Necrotic myocardial cells release damage-associated molecular patterns that provoke fibroblast activation in vitro and trigger myocardial inflammation and fibrosis in vivo. J Am Heart Assoc 2015; 4:e001993. [PMID: 26037082 PMCID: PMC4599537 DOI: 10.1161/jaha.115.001993] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
BACKGROUND Tissue injury triggers inflammatory responses that promote tissue fibrosis; however, the mechanisms that couple tissue injury, inflammation, and fibroblast activation are not known. Given that dying cells release proinflammatory "damage-associated molecular patterns" (DAMPs), we asked whether proteins released by necrotic myocardial cells (NMCs) were sufficient to activate fibroblasts in vitro by examining fibroblast activation after stimulation with proteins released by necrotic myocardial tissue, as well as in vivo by injecting proteins released by necrotic myocardial tissue into the hearts of mice and determining the extent of myocardial inflammation and fibrosis at 72 hours. METHODS AND RESULTS The freeze-thaw technique was used to induce myocardial necrosis in freshly excised mouse hearts. Supernatants from NMCs contained multiple DAMPs, including high mobility group box-1 (HMGB1), galectin-3, S100β, S100A8, S100A9, and interleukin-1α. NMCs provoked a significant increase in fibroblast proliferation, α-smooth muscle actin activation, and collagen 1A1 and 3A1 mRNA expression and significantly increased fibroblast motility in a cell-wounding assay in a Toll-like receptor 4 (TLR4)- and receptor for advanced glycation end products-dependent manner. NMC stimulation resulted in a significant 3- to 4-fold activation of Akt and Erk, whereas pretreatment with Akt (A6730) and Erk (U0126) inhibitors decreased NMC-induced fibroblast proliferation dose-dependently. The effects of NMCs on cell proliferation and collagen gene expression were mimicked by several recombinant DAMPs, including HMGB1 and galectin-3. Moreover, immunodepletion of HMGB1 in NMC supernatants abrogated NMC-induced cell proliferation. Finally, injection of NMC supernatants or recombinant HMGB1 into the heart provoked increased myocardial inflammation and fibrosis in wild-type mice but not in TLR4-deficient mice. CONCLUSIONS These studies constitute the initial demonstration that DAMPs released by NMCs induce fibroblast activation in vitro, as well as myocardial inflammation and fibrosis in vivo, at least in part, through TLR4-dependent signaling.
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Affiliation(s)
- Weili Zhang
- Division of Nephrology, Department of Internal Medicine, Shanghai General Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China (W.Z.)
| | - Kory J Lavine
- Division of Cardiology, Department of Medicine, Center for Cardiovascular Research, Washington University School of Medicine, St. Louis, MO (K.J.L., S.A.E., C.J.W., P.M.B., D.L.M.)
| | - Slava Epelman
- Division of Cardiology, Peter Munk Cardiac Centre, Toronto General Hospital and University Health Network, University of Toronto, Ontario, Canada (S.E.) Faculty of Medicine, University of Toronto, Ontario, Canada (S.E.)
| | - Sarah A Evans
- Division of Cardiology, Department of Medicine, Center for Cardiovascular Research, Washington University School of Medicine, St. Louis, MO (K.J.L., S.A.E., C.J.W., P.M.B., D.L.M.)
| | - Carla J Weinheimer
- Division of Cardiology, Department of Medicine, Center for Cardiovascular Research, Washington University School of Medicine, St. Louis, MO (K.J.L., S.A.E., C.J.W., P.M.B., D.L.M.)
| | - Philip M Barger
- Division of Cardiology, Department of Medicine, Center for Cardiovascular Research, Washington University School of Medicine, St. Louis, MO (K.J.L., S.A.E., C.J.W., P.M.B., D.L.M.)
| | - Douglas L Mann
- Division of Cardiology, Department of Medicine, Center for Cardiovascular Research, Washington University School of Medicine, St. Louis, MO (K.J.L., S.A.E., C.J.W., P.M.B., D.L.M.)
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10
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Abstract
BACKGROUND Tumor necrosis factor (TNF) signaling protects against ischemia/reperfusion-induced cardiomyocyte death, in vitro, ex vivo, and in vivo. TNF-receptor-associated factor 2 (TRAF2), an E3 ubiquitin ligase, coordinates cytoprotective signaling downstream of both TNF receptors, via unclear mechanisms. Noting that TRAF2 is recruited to mitochondria, and that autophagic removal of ubiquitin-tagged damaged mitochondria is cytoprotective, we tested the hypothesis that TRAF2 mediates mitochondrial autophagy. METHODS AND RESULTS TRAF2 localizes to the mitochondria in neonatal rat cardiac myocytes, and TNF treatment transcriptionally upregulates TRAF2 abundance in the mitochondrial subfraction. TRAF2 colocalizes with ubiquitin, p62 adaptor protein, and mitochondria within LC3-bound autophagosomes; and exogenous TRAF2 enhances autophagic removal of mitochondria. TRAF2 knockdown with adenoviral shRNA transduction induces accumulation of depolarized mitochondria in resting neonatal rat cardiac myocytes, as well as in those treated with TNF or uncoupling agent carbonyl cyanide m-chlorophenyl hydrazone, suggesting an essential role for TRAF2 in homeostatic and stress-induced mitochondrial autophagy. TRAF2 also colocalizes and interacts with PARKIN, a previously described E3 ubiquitin ligase and mitophagy effector, on depolarized mitochondria in neonatal rat cardiac myocytes. Exogenous expression of TRAF2, but not its E3 ligase-deficient mutants, is sufficient to partially restore mitophagy in the setting of PARKIN knockdown, suggesting redundancy in their ubiquitin ligase roles. TRAF2 abundance increases in the mitochondrial subfraction of ischemia/reperfusion-modeled hearts; and exogenous TRAF2, but not its E3 ligase-deficient mutants, reduces depolarized mitochondria and rescues cell death in neonatal rat cardiac myocytes subjected to hypoxia/reoxygenation. CONCLUSIONS Taken together, these data indicate an essential role for TRAF2 in concert with PARKIN as a mitophagy effector, which contributes to TRAF2-induced cytoprotective signaling.
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Affiliation(s)
- Kai-Chun Yang
- From the Division of Cardiology and Center for Cardiovascular Research, Department of Internal Medicine (K.-C.Y., X.M., H.L., J.M., P.M.B., D.L.M., A.D.), Department of Cell Biology and Physiology (D.L.M., A.D.), Washington University School of Medicine, St. Louis, MO; and Department of Medicine, John Cochran VA Medical Center, St. Louis, MO (X.M., H.L., A.D.)
| | - Xiucui Ma
- From the Division of Cardiology and Center for Cardiovascular Research, Department of Internal Medicine (K.-C.Y., X.M., H.L., J.M., P.M.B., D.L.M., A.D.), Department of Cell Biology and Physiology (D.L.M., A.D.), Washington University School of Medicine, St. Louis, MO; and Department of Medicine, John Cochran VA Medical Center, St. Louis, MO (X.M., H.L., A.D.)
| | - Haiyan Liu
- From the Division of Cardiology and Center for Cardiovascular Research, Department of Internal Medicine (K.-C.Y., X.M., H.L., J.M., P.M.B., D.L.M., A.D.), Department of Cell Biology and Physiology (D.L.M., A.D.), Washington University School of Medicine, St. Louis, MO; and Department of Medicine, John Cochran VA Medical Center, St. Louis, MO (X.M., H.L., A.D.)
| | - John Murphy
- From the Division of Cardiology and Center for Cardiovascular Research, Department of Internal Medicine (K.-C.Y., X.M., H.L., J.M., P.M.B., D.L.M., A.D.), Department of Cell Biology and Physiology (D.L.M., A.D.), Washington University School of Medicine, St. Louis, MO; and Department of Medicine, John Cochran VA Medical Center, St. Louis, MO (X.M., H.L., A.D.)
| | - Philip M Barger
- From the Division of Cardiology and Center for Cardiovascular Research, Department of Internal Medicine (K.-C.Y., X.M., H.L., J.M., P.M.B., D.L.M., A.D.), Department of Cell Biology and Physiology (D.L.M., A.D.), Washington University School of Medicine, St. Louis, MO; and Department of Medicine, John Cochran VA Medical Center, St. Louis, MO (X.M., H.L., A.D.)
| | - Douglas L Mann
- From the Division of Cardiology and Center for Cardiovascular Research, Department of Internal Medicine (K.-C.Y., X.M., H.L., J.M., P.M.B., D.L.M., A.D.), Department of Cell Biology and Physiology (D.L.M., A.D.), Washington University School of Medicine, St. Louis, MO; and Department of Medicine, John Cochran VA Medical Center, St. Louis, MO (X.M., H.L., A.D.)
| | - Abhinav Diwan
- From the Division of Cardiology and Center for Cardiovascular Research, Department of Internal Medicine (K.-C.Y., X.M., H.L., J.M., P.M.B., D.L.M., A.D.), Department of Cell Biology and Physiology (D.L.M., A.D.), Washington University School of Medicine, St. Louis, MO; and Department of Medicine, John Cochran VA Medical Center, St. Louis, MO (X.M., H.L., A.D.).
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Tzeng HP, Evans S, Gao F, Chambers K, Topkara VK, Sivasubramanian N, Barger PM, Mann DL. Dysferlin mediates the cytoprotective effects of TRAF2 following myocardial ischemia reperfusion injury. J Am Heart Assoc 2014; 3:e000662. [PMID: 24572254 PMCID: PMC3959693 DOI: 10.1161/jaha.113.000662] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Background We have demonstrated that tumor necrosis factor (TNF) receptor‐associated factor 2 (TRAF2), a scaffolding protein common to TNF receptors 1 and 2, confers cytoprotection in the heart. However, the mechanisms for the cytoprotective effects of TRAF2 are not known. Methods/Results Mice with cardiac‐restricted overexpression of low levels of TRAF2 (MHC‐TRAF2LC) and a dominant negative TRAF2 (MHC‐TRAF2DN) were subjected to ischemia (30‐minute) reperfusion (60‐minute) injury (I/R), using a Langendorff apparatus. MHC‐TRAF2LC mice were protected against I/R injury as shown by a significant ≈27% greater left ventricular (LV) developed pressure after I/R, whereas mice with impaired TRAF2 signaling had a significantly ≈38% lower LV developed pressure, a ≈41% greater creatine kinase (CK) release, and ≈52% greater Evans blue dye uptake after I/R, compared to LM. Transcriptional profiling of MHC‐TRAF2LC and MHC‐TRAF2DN mice identified a calcium‐triggered exocytotic membrane repair protein, dysferlin, as a potential cytoprotective gene responsible for the cytoprotective effects of TRAF2. Mice lacking dysferlin had a significant ≈39% lower LV developed pressure, a ≈20% greater CK release, and ≈29% greater Evans blue dye uptake after I/R, compared to wild‐type mice, thus phenocopying the response to tissue injury in the MHC‐TRAF2DN mice. Moreover, breeding MHC‐TRAF2LC onto a dysferlin‐null background significantly attenuated the cytoprotective effects of TRAF2 after I/R injury. Conclusion The study shows that dysferlin, a calcium‐triggered exocytotic membrane repair protein, is required for the cytoprotective effects of TRAF2‐mediated signaling after I/R injury.
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Affiliation(s)
- Huei-Ping Tzeng
- Center for Cardiovascular Research, Division of Cardiology, Department of Medicine, Washington University School of Medicine, St. Louis, MO
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12
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Divakaran VG, Evans S, Topkara VK, Diwan A, Burchfield J, Gao F, Dong J, Tzeng HP, Sivasubramanian N, Barger PM, Mann DL. Tumor necrosis factor receptor-associated factor 2 signaling provokes adverse cardiac remodeling in the adult mammalian heart. Circ Heart Fail 2013; 6:535-43. [PMID: 23493088 DOI: 10.1161/circheartfailure.112.000080] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND Tumor necrosis factor superfamily ligands provoke a dilated cardiac phenotype signal through a common scaffolding protein termed tumor necrosis factor receptor-associated factor 2 (TRAF2); however, virtually nothing is known about TRAF2 signaling in the adult mammalian heart. METHODS AND RESULTS We generated multiple founder lines of mice with cardiac-restricted overexpression of TRAF2 and characterized the phenotype of mice with higher expression levels of TRAF2 (myosin heavy chain [MHC]-TRAF2(HC)). MHC-TRAF2(HC) transgenic mice developed a time-dependent increase in cardiac hypertrophy, left ventricular dilation, and adverse left ventricular remodeling, and a significant decrease in LV+dP/dt and LV-dP/dt when compared with littermate controls (P<0.05 compared with littermate). During the early phases of left ventricular remodeling, there was a significant increase in total matrix metalloproteinase activity that corresponded with a decrease in total myocardial fibrillar collagen content. As the MHC-TRAF2(HC) mice aged, there was a significant decrease in total matrix metalloproteinase activity accompanied by an increase in total fibrillar collagen content and an increase in myocardial tissue inhibitor of metalloproteinase-1 levels. There was a significant increase in nuclear factor-κB activation at 4 to 12 weeks and jun N-terminal kinases activation at 4 weeks in the MHC-TRAF2(HC) mice. Transciptional profiling revealed that >95% of the hypertrophic/dilated cardiomyopathy-related genes that were significantly upregulated genes in the MHC-TRAF2(HC) hearts contained κB elements in their promoters. CONCLUSIONS These results show for the first time that targeted overexpression of TRAF2 is sufficient to mediate adverse cardiac remodeling in the heart.
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Affiliation(s)
- Vijay G Divakaran
- Winters Center for Heart Failure Research Section of Cardiology, Baylor College of Medicine, Houston, TX, USA
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13
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Mann DL, Barger PM, Burkhoff D. Myocardial recovery and the failing heart: myth, magic, or molecular target? J Am Coll Cardiol 2012; 60:2465-72. [PMID: 23158527 DOI: 10.1016/j.jacc.2012.06.062] [Citation(s) in RCA: 178] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 06/06/2012] [Accepted: 06/12/2012] [Indexed: 11/17/2022]
Abstract
Medical and device therapies that reduce heart failure morbidity and mortality also lead to decreased left ventricular volume and mass and a more normal elliptical shape of the ventricle. These are due to changes in myocyte size, structure, and organization that have been referred to collectively as reverse remodeling. Moreover, there are subsets of patients whose hearts have undergone reverse remodeling either spontaneously or after medical or device therapies and whose clinical course is associated with freedom from future heart failure events. This phenomenon has been referred to as myocardial recovery. Despite the frequent interchangeable use of the terms "myocardial recovery" and "reverse remodeling" to describe the reversal of various aspects of the heart failure phenotype after medical and device therapy, the literature suggests that there are important differences between these 2 phenomena and that myocardial recovery and reverse remodeling are not synonymous. In this review, we discuss the biology of cardiac remodeling, cardiac reverse remodeling, and myocardial recovery with the intent to provide a conceptual framework for understanding myocardial recovery.
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Affiliation(s)
- Douglas L Mann
- Center for Cardiovascular Research, Division of Cardiology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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14
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Zhang W, Chancey AL, Tzeng HP, Zhou Z, Lavine KJ, Gao F, Sivasubramanian N, Barger PM, Mann DL. The development of myocardial fibrosis in transgenic mice with targeted overexpression of tumor necrosis factor requires mast cell-fibroblast interactions. Circulation 2011; 124:2106-16. [PMID: 22025605 DOI: 10.1161/circulationaha.111.052399] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Transgenic mice with cardiac-restricted overexpression of tumor necrosis factor (MHCsTNF mice) develop progressive myocardial fibrosis, diastolic dysfunction, and adverse cardiac remodeling. Insofar as tumor necrosis factor (TNF) does not directly stimulate fibroblast collagen synthesis, we asked whether TNF-induced fibrosis was mediated indirectly through interactions between mast cells and cardiac fibroblasts. METHODS AND RESULTS Cardiac mast cell number increased 2 to 3 fold (P<0.001) in MHCsTNF mice compared with littermate controls. Outcrossing MHCsTNF mice with mast cell-deficient (c-kit(-/-)) mice showed that the 11-fold increase (P<0.001) in collagen volume fraction in MHCsTNF/c-kit(+/-) mice was abrogated in MHCsTNF/c-kit(-/-) mice, and that the leftward shifted left ventricular pressure-volume curve in the MHCsTNF/c-kit(+/-) mice was normalized in the MHCsTNF/c-kit(-/-) hearts. Furthermore, the increase in transforming growth factor β1 and type I transforming growth factor β receptor messenger RNA levels was significantly (P=0.03, P=0.01, respectively) attenuated in MHCsTNF/c-kit(-/-) when compared with MHCsTNF/c-kit(+/-) mice. Coculture of fibroblasts with mast cells resulted in enhanced α-smooth muscle actin expression, increased proliferation and collagen messenger RNA expression, and increased contraction of 3-dimensional collagen gels in MHCsTNF fibroblasts compared with littermate fibroblasts. The effects of mast cells were abrogated by type I transforming growth factor β receptor antagonist NP-40208. CONCLUSIONS These results suggest that increased mast cell density with resultant mast cell-cardiac fibroblast cross-talk is required for the development of myocardial fibrosis in inflammatory cardiomyopathy. Cardiac fibroblasts exposed to sustained inflammatory signaling exhibit an increased repertoire of profibrotic phenotypic responses in response to mast cell mediators.
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Affiliation(s)
- Weili Zhang
- Division of Cardiology, Washington University School of Medicine, 660 S Euclid Avenue, St. Louis, MO 63110, USA.
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15
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Topkara VK, Evans S, Zhang W, Epelman S, Staloch L, Barger PM, Mann DL. Therapeutic targeting of innate immunity in the failing heart. J Mol Cell Cardiol 2010; 51:594-9. [PMID: 21074541 DOI: 10.1016/j.yjmcc.2010.11.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 10/22/2010] [Accepted: 11/02/2010] [Indexed: 12/22/2022]
Abstract
Recent studies suggest that the heart possesses an intrinsic system that is intended to delimit tissue injury, as well as orchestrate homoeostatic responses within the heart. The extant literature suggests that this intrinsic stress response is mediated, at least in part, by a family of pattern recognition receptors that belong to the innate immune system, including CD14, the soluble pattern recognition receptor for lipopolysaccharide, and Toll-like receptors 2, 3, 4, 5, 6, 7, and 9. Although this intrinsic stress response system provides a short-term adaptive response to tissue injury, the beneficial effects of this phylogenetically ancient system may be lost if myocardial expression of these molecules either becomes sustained and/or excessive, in which case the salutary effects of activation of these pathways are contravened by the known deleterious effects of inflammatory signaling. Herein we present new information with regard to activation of innate immune gene expression in the failing human heart, as well as review the novel TLR antagonists that are being developed for other indications outside of heart failure. This review will discuss the interesting possibility that the TLR pathway may represent a new target for the development of novel heart failure therapeutics. This article is part of a special issue entitled "Key Signaling Molecules in Hypertrophy and Heart Failure."
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Affiliation(s)
- Veli K Topkara
- Center for Cardiovascular Research, Division of Cardiology, Department of Medicine, Washington University School of Medicine, 660 S. Euclid Ave, Campus Box 8086, St. Louis, MO 63110, USA
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16
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Topkara VK, Wang W, Tzeng HP, Gao F, Camp A, Gu C, Robbins J, Barger PM, Mann DL. Myocardial Recovery Is Associated with Molecular Hysteresis in a Model of Conditional Transgenesis. J Card Fail 2010. [DOI: 10.1016/j.cardfail.2010.06.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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17
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Mann DL, Topkara VK, Evans S, Barger PM. Innate immunity in the adult mammalian heart: for whom the cell tolls. Trans Am Clin Climatol Assoc 2010; 121:34-51. [PMID: 20697548 PMCID: PMC2917144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Recent studies suggest that the heart possesses an intrinsic system that is intended to delimit tissue injury, as well as orchestrate homoeostatic responses within the heart. The extant literature suggests that this intrinsic stress response is mediated, at least in part, by a family of pattern recognition receptors that belong to the innate immune system, including CD14, the soluble pattern recognition receptor for lipopolysaccharide, and Toll like receptors-2, 3, 4, and 6. Although this intrinsic stress response system provides a short-term adaptive response to tissue injury, the beneficial effects of this phylogenetically ancient system may be lost if myocardial expression of these molecules either becomes sustained and/or excessive, in which case the salutary effects of activation of these pathways may be contravened by the known deleterious effects of inflammatory signaling. Herein we present new information with regard to activation of innate immune gene expression in the failing human heart. Taken together, these new observations provide provisional evidence that the innate immune system is activated in human heart failure, raising the interesting possibility that this pathway may represent a target for the development of novel heart failure therapeutics.
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Affiliation(s)
- Douglas L Mann
- Division of Cardiology, 660 S. Euclid Ave, Campus Box 8086, St. Louis, MO 63110, USA.
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18
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Thakker GD, Frangogiannis NG, Zymek PT, Sharma S, Raya JL, Barger PM, Taegtmeyer H, Entman ML, Ballantyne CM. Increased myocardial susceptibility to repetitive ischemia with high-fat diet-induced obesity. Obesity (Silver Spring) 2008; 16:2593-600. [PMID: 18833212 PMCID: PMC3049112 DOI: 10.1038/oby.2008.414] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Obesity and diabetes are frequently associated with cardiovascular disease. When a normal heart is subjected to brief/sublethal repetitive ischemia and reperfusion (I/R), adaptive responses are activated to preserve cardiac structure and function. These responses include but are not limited to alterations in cardiac metabolism, reduced calcium responsiveness, and induction of antioxidant enzymes. In a model of ischemic cardiomyopathy inducible by brief repetitive I/R, we hypothesized that dysregulation of these adaptive responses in diet-induced obese (DIO) mice would contribute to enhanced myocardial injury. DIO C57BL/6J mice were subjected to 15 min of daily repetitive I/R while under short-acting anesthesia, a protocol that results in the development of fibrotic cardiomyopathy. Cardiac lipids and candidate gene expression were analyzed at 3 days, and histology at 5 days of repetitive I/R. Total free fatty acids (FFAs) in the cardiac extracts of DIO mice were significantly elevated, reflecting primarily the dietary fatty acid (FA) composition. Compared with lean controls, cardiac FA oxidation (FAO) capacity of DIO mice was significantly higher, concurrent with increased expression of FA metabolism gene transcripts. Following 15 min of daily repetitive I/R for 3 or 5 days, DIO mice exhibited increased susceptibility to I/R and, in contrast to lean mice, developed microinfarction, which was associated with an exaggerated inflammatory response. Repetitive I/R in DIO mice was associated with more profound significant downregulation of FA metabolism gene transcripts and elevated FFAs and triglycerides. Maladaptive metabolic changes of FA metabolism contribute to enhanced myocardial injury in diet-induced obesity.
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Affiliation(s)
- Geeta D. Thakker
- Section of Atherosclerosis and Vascular Medicine, Baylor College of Medicine, Houston, TX
| | | | - Pawel T. Zymek
- Section of Cardiovascular Sciences, Baylor College of Medicine, Houston, TX
| | - Saumya Sharma
- Division of Cardiology, Department of Internal Medicine, The University of Texas Medical School at Houston, Houston, TX
| | - Joe L. Raya
- Section of Atherosclerosis and Vascular Medicine, Baylor College of Medicine, Houston, TX
| | - Philip M. Barger
- Section of Cardiology, Department of Medicine, Baylor College of Medicine, Houston, TX
| | - Heinrich Taegtmeyer
- Division of Cardiology, Department of Internal Medicine, The University of Texas Medical School at Houston, Houston, TX
| | - Mark L. Entman
- Section of Cardiovascular Sciences, Baylor College of Medicine, Houston, TX
| | - Christie M. Ballantyne
- Section of Atherosclerosis and Vascular Medicine, Baylor College of Medicine, Houston, TX
- Center for Cardiovascular Disease Prevention, Methodist DeBakey Heart Center, Houston, TX
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Ramabadran RS, Chancey A, Vallejo JG, Barger PM, Sivasubramanian N, Mann DL. Targeted gene silencing of tumor necrosis factor attenuates the negative inotropic effects of lipopolysaccharide in isolated contracting cardiac myocytes. Tex Heart Inst J 2008; 35:16-21. [PMID: 18427645 PMCID: PMC2322883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Bacterial endotoxin (lipopolysaccharide) depresses cardiovascular function; however, the mediators and signaling pathways that are responsible for the negative inotropic effects of lipopolysaccharide are not fully known. We used RNA interference to determine the relative role of tumor necrosis factor with respect to mediating the negative inotropic effects of lipopolysaccharide in isolated cardiac myocytes. Cardiac myocyte cultures were treated with lipopolysaccharide in the presence or absence of small interfering RNAs (siRNA) for tumor necrosis factor. We examined the effects of tumor necrosis factor siRNA on lipopolysaccharide-induced tumor necrosis factor messenger RNA (mRNA) and protein biosynthesis, as well as the negative inotropic effects of lipopolysaccharide in isolated contracting cardiac myocytes. Treatment of adult cardiac myocyte cultures with tumor necrosis factor siRNA significantly attenuated lipopolysaccharide-induced tumor necrosis factor mRNA and protein biosynthesis, whereas transfection with a double-stranded RNA that does not target mammalian mRNA had no effect. Pretreatment with tumor necrosis factor siRNA significantly attenuated, but did not abrogate, the lipopolysaccharide-induced decrease in sarcomere shortening in isolated contracting cardiac myocytes. In contrast, tumor necrosis factor siRNA had a comparatively smaller effect on improving sarcomere shortening once the negative inotropic effects of lipopolysaccharide were fully established. These results suggest that tumor necrosis factor plays an important upstream role in lipopolysaccharide-induced negative inotropic effects in isolated contracting cardiac myocytes and that other molecular mechanisms are responsible for the decrease in sarcomere shortening after sustained lipopolysaccharide signaling.
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Affiliation(s)
- R S Ramabadran
- Winters Center for Heart Failure Research, Section of Cardiology, Department of Medicine, Baylor College of Medicine and the Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, Texas 77030, USA
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20
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Sekiguchi K, Tian Q, Ishiyama M, Burchfield J, Gao F, Mann DL, Barger PM. Inhibition of PPAR-α activity in mice with cardiac-restricted expression of tumor necrosis factor: potential role of TGF-β/Smad3. Am J Physiol Heart Circ Physiol 2007; 292:H1443-51. [PMID: 17098824 DOI: 10.1152/ajpheart.01056.2006] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A shift in energy substrate utilization from fatty acids to glucose has been reported in failing hearts, resulting in improved oxygen efficiency yet perhaps also contributing to a state of energy deficiency. Peroxisome proliferator-activated receptor (PPAR)-α, the principal transcriptional regulator of cardiac fatty acid β-oxidation (FAO) genes, is downregulated in heart failure, and this may contribute to reduced fatty acid utilization. Cardiomyopathic states are also accompanied by elevated levels of circulating cytokines, such as tumor necrosis factor (TNF), as well as increased local production of cytokines and profibrotic factors, such as transforming growth factor (TGF)-β. However, whether these molecular pathways directly modulate cardiac energy metabolism and PPAR-α activity is not known. Therefore, FAO capacity and FAO gene expression were determined in mice with cardiac-restricted overexpression of TNF (MHCsTNF3). MHCsTNF3 hearts had significantly lower FAO capacity and decreased expression of PPAR-α and FAO target genes compared with control hearts. Surprisingly, TNF had little effect on PPAR-α activity and FAO rates in cultured ventricular myocytes, suggesting that TNF acts indirectly on myocyte FAO in vivo. We found that TGF-β expression was upregulated in MHCsTNF3 hearts and that treatment of cultured myocytes with TGF-β significantly suppressed FAO rates and directly impaired PPAR-α activity, a result reproduced by Smad3 overexpression. This work demonstrates that TGF-β signaling pathways directly suppress PPAR-α activity and reduce FAO in cardiac myocytes, perhaps in response to locally elevated TNF. Although speculative, TGF-β-driven repair mechanisms may also include the additional benefit of limiting FAO in injured myocardium.
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Affiliation(s)
- Kenichi Sekiguchi
- Winters Center for Heart Failure Research, Baylor College of Medicine, Houston, TX 77030, USA
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21
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Abstract
Control of energy metabolism in the heart is closely linked to cardiac performance. Dysregulation of energy-generating pathways occurs in many forms of heart disease, including heart failure. Uncertainty exists as to whether these alterations in the way adenosine triphosphate (ATP) is produced serve to protect the heart from excessive oxygen demands or have untoward long-term consequences. Regulation of fatty acid beta-oxidation (FAO), the principal source of ATP in the healthy heart, occurs at multiple levels, including a strong gene transcriptional component. In the heart, members of the peroxisome proliferator-activated receptor (PPAR) family of transcription factors are the primary regulators of FAO gene expression. PPARs are ligand activated by endogenous lipids and synthetic small molecules, thus providing attractive targets for pharmaceutical intervention. This article discusses controversies surrounding our understanding of cardiac energy metabolism in heart failure and the role that PPAR family members may play, either as contributors to or as potential adjunctive therapy for cardiac disease.
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22
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Tian Q, Barger PM. Peroxisome Proliferator-Activated Receptors (PPAR): A Potential Strategy To Combat Lipotoxic Heart Disease. Methodist Debakey Cardiovasc J 2006. [DOI: 10.14797/mdcj-2-1-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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23
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Tian Q, Barger PM. Peroxisome Proliferator-Activated Receptors (PPAR): A Potential Strategy
to Combat Lipotoxic Heart Disease. Methodist Debakey Cardiovasc J 2006. [DOI: 10.14797/mdcvj.80] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Sano M, Wang SC, Shirai M, Scaglia F, Xie M, Sakai S, Tanaka T, Kulkarni PA, Barger PM, Youker KA, Taffet GE, Hamamori Y, Michael LH, Craigen WJ, Schneider MD. Activation of cardiac Cdk9 represses PGC-1 and confers a predisposition to heart failure. EMBO J 2004; 23:3559-69. [PMID: 15297879 PMCID: PMC516624 DOI: 10.1038/sj.emboj.7600351] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2003] [Revised: 07/08/2004] [Indexed: 11/09/2022] Open
Abstract
Hypertrophy allows the heart to adapt to workload but culminates in later pump failure; how it is achieved remains uncertain. Previously, we showed that hypertrophy is accompanied by activation of cyclin T/Cdk9, which phosphorylates the C-terminal domain of the large subunit of RNA polymerase II, stimulating transcription elongation and pre-mRNA processing; Cdk9 activity was required for hypertrophy in culture, whereas heart-specific activation of Cdk9 by cyclin T1 provoked hypertrophy in mice. Here, we report that alphaMHC-cyclin T1 mice appear normal at baseline yet suffer fulminant apoptotic cardiomyopathy when challenged by mechanical stress or signaling by the G-protein Gq. At pathophysiological levels, Cdk9 activity suppresses many genes for mitochondrial proteins including master regulators of mitochondrial function (peroxisome proliferator-activated receptor gamma coactivator 1 (PGC-1), nuclear respiratory factor-1). In culture, cyclin T1/Cdk9 suppresses PGC-1, decreases mitochondrial membrane potential, and sensitizes cardiomyocytes to apoptosis, effects rescued by exogenous PGC-1. Cyclin T1/Cdk9 inhibits PGC-1 promoter activity and preinitiation complex assembly. Thus, chronic activation of Cdk9 causes not only cardiomyocyte enlargement but also defective mitochondrial function, via diminished PGC-1 transcription, and a resulting susceptibility to apoptotic cardiomyopathy.
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Affiliation(s)
- Motoaki Sano
- Center for Cardiovascular Development, Baylor College of Medicine, Houston, TX, USA
- Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Sam C Wang
- Center for Cardiovascular Development, Baylor College of Medicine, Houston, TX, USA
- Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Manabu Shirai
- Center for Cardiovascular Development, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Min Xie
- Center for Cardiovascular Development, Baylor College of Medicine, Houston, TX, USA
- Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Satoshi Sakai
- Center for Cardiovascular Development, Baylor College of Medicine, Houston, TX, USA
- Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Toru Tanaka
- Center for Cardiovascular Development, Baylor College of Medicine, Houston, TX, USA
- Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Prathit A Kulkarni
- Center for Cardiovascular Development, Baylor College of Medicine, Houston, TX, USA
- Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Philip M Barger
- Department of Medicine, Baylor College of Medicine, Houston, TX, USA
- Winters Center for Heart Failure Research, Baylor College of Medicine, Houston, TX, USA
| | - Keith A Youker
- The Methodist Hospital-DeBakey Heart Center, Baylor College of Medicine, Houston, TX, USA
- Department of Surgery, Baylor College of Medicine, Houston, TX, USA
| | - George E Taffet
- Department of Medicine, Baylor College of Medicine, Houston, TX, USA
- The Methodist Hospital-DeBakey Heart Center, Baylor College of Medicine, Houston, TX, USA
| | - Yasuo Hamamori
- Center for Cardiovascular Development, Baylor College of Medicine, Houston, TX, USA
- Department of Medicine, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Lloyd H Michael
- Department of Medicine, Baylor College of Medicine, Houston, TX, USA
- The Methodist Hospital-DeBakey Heart Center, Baylor College of Medicine, Houston, TX, USA
| | - William J Craigen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Michael D Schneider
- Center for Cardiovascular Development, Baylor College of Medicine, Houston, TX, USA
- Department of Medicine, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA
- Center for Cardiovascular Development, Baylor College of Medicine, One Baylor Plaza, Room 506D, Houston, TX 77030, USA. Tel.: +1 713 798 6683; Fax: +1 713 798 7437; E-mail:
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Sekiguchi K, Li X, Coker M, Flesch M, Barger PM, Sivasubramanian N, Mann DL. Cross-regulation between the renin?angiotensin system and inflammatory mediators in cardiac hypertrophy and failure. Cardiovasc Res 2004; 63:433-42. [PMID: 15276468 DOI: 10.1016/j.cardiores.2004.02.005] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2003] [Revised: 02/01/2004] [Accepted: 02/09/2004] [Indexed: 11/21/2022] Open
Abstract
One of the major conceptual advances in our understanding of the pathogenesis of heart failure has been the insight that heart failure may progress as the result of the sustained overexpression of biologically active "neurohormones", such as norepinephrine and angiotensin II, which by virtue of their deleterious effects are sufficient to contribute to disease progression by provoking worsening left ventricular (LV) remodeling and progressive LV dysfunction. Recently, a second class of biologically active molecules, termed cytokines, has also been identified in the setting of heart failure. Analogous to the situation with neurohormones, the overexpression of cytokines is sufficient to contribute to disease progression in heart failure phenotype. Although important interactions between proinflammatory cytokines and the adrenergic system have been recognized in the heart for over a decade, the nature of the important interactions between proinflammatory cytokines and the renin-angiotensin system has become apparent only recently. Accordingly, in the present review, we will discuss the evidence which suggests that there is a functionally significant cross-talk between neurohormonal and inflammatory cytokine signaling in cardiac hypertrophy and failure.
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Affiliation(s)
- Kenichi Sekiguchi
- Cardiology Section of the Department of Medicine, Winters Center for Heart Failure Research, Houston VAMC and Baylor College of Medicine, 6565 Fannin, MS 524, Houston, TX 77030, USA
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Finck BN, Lehman JJ, Barger PM, Kelly DP. Regulatory networks controlling mitochondrial energy production in the developing, hypertrophied, and diabetic heart. Cold Spring Harb Symp Quant Biol 2003; 67:371-82. [PMID: 12858562 DOI: 10.1101/sqb.2002.67.371] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- B N Finck
- Center for Cardiovascular Research, Department of Medicine, Departments of Molecular Biology & Pharmacology and Pediatrics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Barger PM, Browning AC, Garner AN, Kelly DP. p38 mitogen-activated protein kinase activates peroxisome proliferator-activated receptor alpha: a potential role in the cardiac metabolic stress response. J Biol Chem 2001; 276:44495-501. [PMID: 11577087 DOI: 10.1074/jbc.m105945200] [Citation(s) in RCA: 192] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The expression of enzymes involved in fatty acid beta-oxidation (FAO), the principal source of energy production in the adult mammalian heart, is controlled at the transcriptional level via the nuclear receptor peroxisome proliferator-activated receptor alpha (PPARalpha). Evidence has emerged that PPARalpha activity is activated as a component of an energy metabolic stress response. The p38 mitogen-activated protein kinase (MAPK) pathway is activated by cellular stressors in the heart, including ischemia, hypoxia, and hypertrophic growth stimuli. We show here that PPARalpha is phosphorylated in response to stress stimuli in rat neonatal cardiac myocytes; in vitro kinase assays demonstrated that p38 MAPK phosphorylates serine residues located within the NH(2)-terminal A/B domain of the protein. Transient transfection studies in cardiac myocytes and in CV-1 cells utilizing homologous and heterologous PPARalpha target element reporters and mammalian one-hybrid transcription assays revealed that p38 MAPK phosphorylation of PPARalpha significantly enhanced ligand-dependent transactivation. Cotransfection studies performed with several known coactivators of PPARalpha demonstrated that p38 MAPK markedly increased coactivation specifically by PGC-1, a transcriptional coactivator implicated in myocyte energy metabolic gene regulation and mitochondrial biogenesis. These results identify PPARalpha as a downstream effector of p38 kinase-dependent stress-activated signaling in the heart, linking extracellular stressors to alterations in energy metabolic gene expression.
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Affiliation(s)
- P M Barger
- Center for Cardiovascular Research, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Kelly DP, Lehman JJ, Barger PM, Huss JM, Weinheimer CJ, Kovacs A, Courtois MR, Leone TC. PPAR signaling in the control of cardiac energy metabolism: Lessons from genetically altered mice. J Mol Cell Cardiol 2001. [DOI: 10.1016/s0022-2828(01)90610-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Lehman JJ, Barger PM, Kovacs A, Saffitz JE, Medeiros DM, Kelly DP. Peroxisome proliferator-activated receptor gamma coactivator-1 promotes cardiac mitochondrial biogenesis. J Clin Invest 2000; 106:847-56. [PMID: 11018072 PMCID: PMC517815 DOI: 10.1172/jci10268] [Citation(s) in RCA: 991] [Impact Index Per Article: 41.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2000] [Accepted: 08/15/2000] [Indexed: 12/15/2022] Open
Abstract
Cardiac mitochondrial function is altered in a variety of inherited and acquired cardiovascular diseases. Recent studies have identified the transcriptional coactivator peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) as a regulator of mitochondrial function in tissues specialized for thermogenesis, such as brown adipose. We sought to determine whether PGC-1 controlled mitochondrial biogenesis and energy-producing capacity in the heart, a tissue specialized for high-capacity ATP production. We found that PGC-1 gene expression is induced in the mouse heart after birth and in response to short-term fasting, conditions known to increase cardiac mitochondrial energy production. Forced expression of PGC-1 in cardiac myocytes in culture induced the expression of nuclear and mitochondrial genes involved in multiple mitochondrial energy-transduction/energy-production pathways, increased cellular mitochondrial number, and stimulated coupled respiration. Cardiac-specific overexpression of PGC-1 in transgenic mice resulted in uncontrolled mitochondrial proliferation in cardiac myocytes leading to loss of sarcomeric structure and a dilated cardiomyopathy. These results identify PGC-1 as a critical regulatory molecule in the control of cardiac mitochondrial number and function in response to energy demands.
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Affiliation(s)
- J J Lehman
- Department of Medicine, and. Department of Pathology, Center for Cardiovascular Research, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Abstract
Cardiac energy metabolic shifts occur as a normal response to diverse physiologic and dietary conditions and as a component of the pathophysiologic processes which accompany cardiac hypertrophy, heart failure, and myocardial ischemia. The capacity to produce energy via the utilization of fats by the mammalian postnatal heart is controlled in part at the level of expression of nuclear genes encoding enzymes involved in mitochondrial fatty acid beta-oxidation (FAO). The principal transcriptional regulator of FAO enzyme genes is the peroxisome proliferator-activated receptor alpha (PPARalpha), a member of the ligand-activated nuclear receptor superfamily. Among the ligand activators of PPARalpha are long-chain fatty acids; therefore, increased uptake of fatty acid substrate into the cardiac myocyte induces a transcriptional response leading to increased expression of FAO enzymes. PPARalpha-mediated control of cardiac metabolic gene expression is activated during postnatal development, short-term starvation, and in response to exercise training. In contrast, certain pathophysiologic states, such as pressure overload-induced hypertrophy, result in deactivation of PPARalpha and subsequent dysregulation of FAO enzyme gene expression, which sets the stage for abnormalities in cardiac lipid homeostasis and energy production, some of which are influenced by gender. Thus, PPARalpha not only serves a critical role in normal cardiac metabolic homeostasis, but alterations in PPARalpha signaling likely contribute to the pathogenesis of a variety of disease states. PPARalpha as a ligand-activated transcription factor is a potential target for the development of new therapeutic strategies aimed at the prevention of pathologic cardiac remodeling.
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Affiliation(s)
- P M Barger
- Center for Cardiovascular Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
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Barger PM, Brandt JM, Leone TC, Weinheimer CJ, Kelly DP. Deactivation of peroxisome proliferator-activated receptor-alpha during cardiac hypertrophic growth. J Clin Invest 2000; 105:1723-30. [PMID: 10862787 PMCID: PMC378509 DOI: 10.1172/jci9056] [Citation(s) in RCA: 354] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
We sought to delineate the molecular regulatory events involved in the energy substrate preference switch from fatty acids to glucose during cardiac hypertrophic growth. alpha(1)-adrenergic agonist-induced hypertrophy of cardiac myocytes in culture resulted in a significant decrease in palmitate oxidation rates and a reduction in the expression of the gene encoding muscle carnitine palmitoyltransferase I (M-CPT I), an enzyme involved in mitochondrial fatty acid uptake. Cardiac myocyte transfection studies demonstrated that M-CPT I promoter activity is repressed during cardiac myocyte hypertrophic growth, an effect that mapped to a peroxisome proliferator-activated receptor-alpha (PPARalpha) response element. Ventricular pressure overload studies in mice, together with PPARalpha overexpression studies in cardiac myocytes, demonstrated that, during hypertrophic growth, cardiac PPARalpha gene expression falls and its activity is altered at the posttranscriptional level via the extracellular signal-regulated kinase mitogen-activated protein kinase pathway. Hypertrophied myocytes exhibited reduced capacity for cellular lipid homeostasis, as evidenced by intracellular fat accumulation in response to oleate loading. These results indicate that during cardiac hypertrophic growth, PPARalpha is deactivated at several levels, leading to diminished capacity for myocardial lipid and energy homeostasis.
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Affiliation(s)
- P M Barger
- Center for Cardiovascular Research, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
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Abstract
During the development of cardiac hypertrophy and in the failing heart, the chief myocardial energy source switches from fatty acid beta-oxidation to glycolysis: a reversion to the fetal energy substrate preference pattern. This review describes recent molecular studies aimed at delineating the gene regulatory pathway involved in the energy metabolic switch in the hypertrophied heart and the potential role of the attendant metabolic consequences in the pathogenesis of heart failure. Studies have been performed with the 'spontaneous hypertensive and heart failure' rat strain and with human cardiomyopathic tissue. These studies have demonstrated that expression of the gene that encodes medium-chain acyl-coenzyme A dehydrogenase (MCAD), a key fatty acid beta-oxidation enzyme, is down-regulated during the progression from cardiac hypertrophy to ventricular dysfunction. A series of studies performed in mice transgenic for the human MCAD gene promoter have identified a transcriptional regulatory pathway involved in the repression of MCAD gene expression in the hypertrophied mouse heart. Two categories of transcription factors, nuclear hormone receptors and Sp factors, bind MCAD gene promoter regulatory elements in response to pressure overload to reactivate a fetal metabolic gene program. Studies are under way to manipulate this transcriptional regulatory pathway in mice using genetic engineering strategies to determine whether this energy metabolic derangement plays a primary role in the development of cardiac hypertrophy and heart failure.
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Affiliation(s)
- P M Barger
- Center for Cardiovascular Research, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Barger PM, Kelly DP. Identification of a retinoid/chicken ovalbumin upstream promoter transcription factor response element in the human retinoid X receptor gamma2 gene promoter. J Biol Chem 1997; 272:2722-8. [PMID: 9006910 DOI: 10.1074/jbc.272.5.2722] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
To investigate the mechanisms involved in the transcriptional control of retinoid X receptor (RXR) gene expression, the 5'-flanking region of the human RXRgamma2 isoform was characterized. An imperfect hexamer repeat (gamma retinoid X response element; gammaRXRE) with a single nucleotide spacer (GGTTGAaAGGTCA) was identified immediately upstream of the RXRgamma2 gene transcription start site. Cotransfection studies in CV-1 cells with expression vectors for the retinoid receptors RXRalpha and retinoic acid receptor beta (RARbeta) demonstrated that the gammaRXRE confers retinoid-mediated transcriptional activation with preferential activation by RXR in the presence of its cognate ligand, 9-cis-retinoic acid (RA). Electrophoretic mobility shift assays demonstrated that RXR homodimer binding to gammaRXRE is markedly enhanced by 9-cis-RA, whereas RAR.RXR heterodimer binding is ligand-independent. DNA binding studies and cell cotransfection experiments also demonstrated that the nuclear receptor, chicken ovalbumin upstream promoter transcription factor (COUP-TF), repressed transcription via the gammaRXRE. Cotransfection experiments revealed that COUP-TF and RXRalpha compete at the gammaRXRE to modulate transcription bidirectionally over a wide range. These results demonstrate that the human RXRgamma2 gene promoter contains a novel imperfect repeat element capable of mediating RXR-dependent transcriptional autoactivation and COUP-TF-dependent repression.
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Affiliation(s)
- P M Barger
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Disch DL, Rader TA, Cresci S, Leone TC, Barger PM, Vega R, Wood PA, Kelly DP. Transcriptional control of a nuclear gene encoding a mitochondrial fatty acid oxidation enzyme in transgenic mice: role for nuclear receptors in cardiac and brown adipose expression. Mol Cell Biol 1996; 16:4043-51. [PMID: 8754802 PMCID: PMC231400 DOI: 10.1128/mcb.16.8.4043] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Expression of the gene encoding medium-chain acyl coenzyme A dehydrogenase (MCAD), a nuclearly encoded mitochondrial fatty acid beta-oxidation enzyme, is regulated in parallel with fatty acid oxidation rates among tissues and during development. We have shown previously that the human MCAD gene promoter contains a pleiotropic element (nuclear receptor response element [NRRE-1]) that confers transcriptional activation or repression by members of the nuclear receptor superfamily. Mice transgenic for human MCAD gene promoter fragments fused to a chloramphenicol acetyltransferase gene reporter were produced and characterized to evaluate the role of NRRE-1 and other promoter elements in the transcriptional control of the MCAD gene in vivo. Expression of the full-length MCAD promoter-chloramphenicol acetyltransferase transgene (MCADCAT.371) paralleled the known tissue-specific differences in mitochondrial beta-oxidation rates and MCAD expression. MCADCAT.371 transcripts were abundant in heart tissue and brown adipose tissue, tissues with high-level MCAD expression. During perinatal cardiac developmental stages, expression of the MCADCAT.371 transgene paralleled mouse MCAD mRNA levels. In contrast, expression of a mutant MCADCAT transgene, which lacked NRRE-1 (MCADCATdeltaNRRE-1), was not enriched in heart or brown adipose tissue and did not exhibit appropriate postnatal induction in the developing heart. Transient-transfection studies with MCAD promoter-luciferase constructs containing normal or mutant NRRE-1 sequences demonstrated that the nuclear receptor binding sequences within NRRE-1 are necessary for high-level transcriptional activity in primary rat cardiocytes. Electrophoretic mobility shift assays demonstrated that NRRE-1 was bound by several cardiac and brown adipose nuclear proteins and that these interactions required the NRRE-1 receptor binding hexamer sequences. Antibody supershift studies identified the orphan nuclear receptor COUP-TF as one of the endogenous cardiac proteins which bound NRRE-1. These results dictate an important role for nuclear receptors in the transcriptional control of a nuclear gene encoding a mitochondrial fatty acid oxidation enzyme and identify a gene regulatory pathway involved in cardiac energy metabolism.
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Affiliation(s)
- D L Disch
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
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Tomlinson BL, Barger PM. A test of the punctuated-cycling hypothesis in Ambystoma forelimb regenerates: the roles of animal size, limb innervation, and the aneurogenic condition. Differentiation 1987; 35:6-15. [PMID: 3428513 DOI: 10.1111/j.1432-0436.1987.tb00145.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The punctuated-cycling (PC) hypothesis [39] predicts that the proportion of actively cycling (AC) cells within the blastema influences the rate of limb regeneration in urodele amphibians. To test this, we compared the rate of regeneration and the parameters of the PC hypothesis in small and large Ambystoma mexicanum larvae and in aneurogenic limbs of Ambystoma maculatum. Aneurogenic limbs regenerated more slowly than limbs of small axolotls, but considerably faster than limbs of large axolotls. Regardless of regeneration rates, virtually all blastema cells were in the proliferative fraction (Pf) (ranging from 92.3% +/- 4.2% to 96.2% +/- 3.4%). As predicted, in the blastemata of more rapidly regenerating small axolotls, 86% of the proliferative fraction was actively cycling, but as regeneration slowed, the proportion of the proliferative fraction that was actively cycling decreased (the AC of aneurogenic limbs being 69.5%, and that of large axolotl limbs being 57.3%) and the proportion of transiently quiescent cells increased. The parameters of the PC hypothesis were also examined in small axolotls at two different times during regeneration. During dedifferentiation and initial blastema formation, 61% of the cells in the proliferative fraction were actively cycling and 34% were transiently quiescent. During the rapid-growth phase of the blastema, 88% of the cells in the proliferative fraction were actively cycling and only 7% of the cells were transiently quiescent. It therefore appears that dedifferentiated cells do not immediately begin active cycling and that the transiently quiescent population is relatively large; however, during the period of rapid growth the proportion of transiently quiescent cells is small. In amputated/denervated limbs of small axolotls, the size of the proliferative fraction decreased as the length of the denervation interval increased. Furthermore, with prolonged denervation the total proportion of actively cycling blastema cells also declined (to about 15%). The failure of denervated limbs to regenerate was correlated with an increased nonproliferative fraction and a reduced proportion of actively cycling cells.
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Affiliation(s)
- B L Tomlinson
- Ohio State University, Department of Zoology, Columbus 43210-1293
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Abstract
Cells of amputated, denervated larval Ambystoma forelimbs dedifferentiate and enter the cell cycle but do not subsequently proliferate sufficiently to form a blastema. The denervated limb stump resorbs slowly until reinnervation stimulates regeneration. We used this system to investigate the fate of cells in denervated limbs which undergo early but limited cycling in response to amputation. In Experiment 1, cells were labeled with [3H]thymidine (3H-T) on Day 4 postamputation (PA)/Day 3 postdenervation (PD). Labeled cells were still present on Day 7 PA, but were less frequently observed on Day 13 PA when the limbs were reinnervated and beginning to regenerate. In Experiment 2 we denervated 1 day preamputation to obtain earlier reinnervation and prevent loss of Day 4 PA labeled cells. Cells labeled with 3H-T on Day 4 PA/Day 5 PD were present throughout the denervation period and most were still present on Day 13 PA. Little or no mitotic activity was found among the labeled cells after the initial round of cycling. The apparent cell cycle block was released upon reinnervation on Days 12 and 13 PA when cycling resumed. Labeled mitotic figures were present on Day 13 PA, and the mitotic index of the labeled population increased as a result of reinnervation. These results demonstrate that blocked cells are rescued by nerves, re-enter the cell cycle, and thus contribute to the reinnervation blastema.
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