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Zhang S, Li R, Ma Y, Yan Y, Ma M, Zhang K, Zhou Y, Li L, Pan L, Ying H, Xue Y. Thyroid-stimulating hormone regulates cardiac function through modulating HCN2 via targeting microRNA-1a. FASEB J 2022; 36:e22561. [PMID: 36125044 DOI: 10.1096/fj.202200574r] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 08/11/2022] [Accepted: 09/09/2022] [Indexed: 11/11/2022]
Abstract
Previous studies have found microRNA-1 (miR-1) and hyperpolarization-activated cyclic nucleotide-gated channel 2 (HCN2) may be involved in the pathogenesis of thyroid hormone (TH) induced cardiac hypertrophy. However, little is known about the role of miR-1 and HCN2 in thyroid stimulation hormone (TSH)-induced cardiac dysfunction. In order to investigate the molecular mechanisms of TSH induced cardiac dysfunction and the role of miR-1/HCN2 in that process, we evaluated the expression of miR-1a/HCN2 in the ventricular myocardium of hypothyroid mice and in TSH-stimulated H9c2 cardiomyocytes. Our data revealed that hypothyroidism mice had smaller hearts, ventricular muscle atrophy, and cardiac contractile dysfunction compared with euthyroid controls. The upregulation of miR-1a and downregulation of HCN2 were found in ventricular myocardium of hypothyroid mice and TSH-stimulated H9c2 cardiomyocytes, indicating that miR-1a and HCN2 may be involved in TSH-induced cardiac dysfunction. We also found that the regulation of miR-1a and HCN2 expression and HCN2 channel activity by TSH requires TSHR, while the regulation of HCN2 expression and HCN2 channel function by TSH requires miR-1a. Thus, our data revealed the potential mechanism of TSH-induced cardiac dysfunction and might shed new light on the pathological role of miR-1a/HCN2 in hypothyroid heart disease.
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Affiliation(s)
- Shengjie Zhang
- Department of Endocrinology and Metabolism, Tongji Hospital, School of Medicine, Tongji University, Shanghai, China.,CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Ran Li
- Department of Endocrinology and Metabolism, Tongji Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Yiruo Ma
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Ying Yan
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Mei Ma
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Keqin Zhang
- Department of Endocrinology and Metabolism, Tongji Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Yun Zhou
- Department of Endocrinology and Metabolism, Tongji Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Ling Li
- Department of Endocrinology and Metabolism, Tongji Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Lingling Pan
- Department of Endocrinology and Metabolism, Tongji Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Hao Ying
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Ying Xue
- Department of Endocrinology and Metabolism, Tongji Hospital, School of Medicine, Tongji University, Shanghai, China
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2
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Hadova K, Kralova E, Doka G, Bies Pivackova L, Kmecova Z, Krenek P, Klimas J. Isolated downregulation of HCN2 in ventricles of rats with streptozotocin-induced diabetic cardiomyopathy. BMC Cardiovasc Disord 2021; 21:118. [PMID: 33653265 PMCID: PMC7927235 DOI: 10.1186/s12872-021-01929-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 02/11/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In spite of disrupted repolarization of diabetic heart, some studies report less tendency of diabetic heart to develop ventricular arrhythmias suggesting effective compensatory mechanism. We hypothesized that myocardial alterations in HCN2 and HCN4 channels occur under hyperglycaemia. METHODS Diabetes was induced in rats using a single injection of streptozotocin (STZ; 55 mg/kg body weight, i.p.). Basal ECG was measured. Expression of mRNA for HCN channels, potassium channels and microRNA 1 and 133a were measured in ventricular tissues. Protein expression of HCN2 channel isoform was assessed in five different regions of the heart by western blotting. Differentiated H9c2 cell line was used to examine HCN channels expression under hyperglycaemia in vitro. RESULTS Six weeks after STZ administration, heart rate was reduced, QRS complex duration, QT interval and T-wave were prolonged in diabetic rats compared to controls. mRNA and protein expressions of HCN2 decreased exclusively in the ventricles of diabetic rats. HCN2 expression levels in atria of STZ rats and H9c2 cells treated with excess of glucose were not changed. MicroRNA levels were stable in STZ rat hearts. We found significantly decreased mRNA levels of several potassium channels participating in repolarization, namely Kcnd2 (Ito1), Kcnh2 (IKr), Kcnq1 (IKs) and Kcnj11 (IKATP). CONCLUSIONS This result together with downregulated HCN2 channels suggest that HCN channels might be an integral part of ventricular electric remodelling and might play a role in cardiac repolarization projected in altered arrhythmogenic profile of diabetic heart.
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Affiliation(s)
- Katarina Hadova
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Odbojarov 10, 832 32, Bratislava, Slovakia
| | - Eva Kralova
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Odbojarov 10, 832 32, Bratislava, Slovakia
| | - Gabriel Doka
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Odbojarov 10, 832 32, Bratislava, Slovakia
| | - Lenka Bies Pivackova
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Odbojarov 10, 832 32, Bratislava, Slovakia
| | - Zuzana Kmecova
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Odbojarov 10, 832 32, Bratislava, Slovakia
| | - Peter Krenek
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Odbojarov 10, 832 32, Bratislava, Slovakia
| | - Jan Klimas
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Odbojarov 10, 832 32, Bratislava, Slovakia.
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3
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Wu T, Wang H, Xin X, Yang J, Hou Y, Fang M, Lu X, Xu Y. An MRTF-A-Sp1-PDE5 Axis Mediates Angiotensin-II-Induced Cardiomyocyte Hypertrophy. Front Cell Dev Biol 2020; 8:839. [PMID: 33015041 PMCID: PMC7509415 DOI: 10.3389/fcell.2020.00839] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 08/05/2020] [Indexed: 12/24/2022] Open
Abstract
Cardiac hypertrophy is a critical intermediate step in the pathogenesis of heart failure. A myriad of signaling networks converge on cardiomyocytes to elicit hypertrophic growth in response to various injurious stimuli. In the present study, we investigated the cardiomyocyte-specific role of myocardin-related transcription factor A (MRTF-A) in angiotensin-II (Ang-II)-induced cardiac hypertrophy and the underlying mechanism. We report that conditional MRTF-A deletion in cardiomyocytes attenuated Ang-II-induced cardiac hypertrophy in mice. Similarly, MRTF-A knockdown or inhibition suppressed Ang-II-induced prohypertrophic response in cultured cardiomyocytes. Of note, Ang II treatment upregulated expression of phosphodiesterase 5 (PDE5), a known mediator of cardiac hypertrophy and heart failure, in cardiomyocytes, which was blocked by MRTF-A depletion or inhibition. Mechanistically, MRTF-A activated expression of specificity protein 1 (Sp1), which in turn bound to the PDE5 promoter and upregulated PDE5 transcription to promote hypertrophy of cardiomyocytes in response to Ang II stimulation. Therefore, our data unveil a novel MRTF-A–Sp1–PDE5 axis that mediates Ang-II-induced hypertrophic response in cardiomyocytes. Targeting this newly identified MRTF-A–Sp1–PDE5 axis may yield novel interventional solutions against heart failure.
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Affiliation(s)
- Teng Wu
- Key Laboratory of Targeted Intervention of Cardiovascular Disease and Collaborative Innovation Center for Cardiovascular Translational Medicine, Department of Pathophysiology, Nanjing Medical University, Nanjing, China
| | - Huidi Wang
- Key Laboratory of Targeted Intervention of Cardiovascular Disease and Collaborative Innovation Center for Cardiovascular Translational Medicine, Department of Pathophysiology, Nanjing Medical University, Nanjing, China
| | - Xiaojun Xin
- Department of Geriatrics, Sir Run Run Hospital, Nanjing Medical University, Nanjing, China
| | - Jie Yang
- Key Laboratory of Targeted Intervention of Cardiovascular Disease and Collaborative Innovation Center for Cardiovascular Translational Medicine, Department of Pathophysiology, Nanjing Medical University, Nanjing, China
| | - Yannan Hou
- Key Laboratory of Targeted Intervention of Cardiovascular Disease and Collaborative Innovation Center for Cardiovascular Translational Medicine, Department of Pathophysiology, Nanjing Medical University, Nanjing, China
| | - Mingming Fang
- Laboratory Center for Experimental Medicine, Department of Clinical Medicine, Jiangsu Health Vocational College, Nanjing, China.,Institute of Biomedical Research, Liaocheng University, Liaocheng, China
| | - Xiang Lu
- Department of Geriatrics, Sir Run Run Hospital, Nanjing Medical University, Nanjing, China
| | - Yong Xu
- Key Laboratory of Targeted Intervention of Cardiovascular Disease and Collaborative Innovation Center for Cardiovascular Translational Medicine, Department of Pathophysiology, Nanjing Medical University, Nanjing, China.,Institute of Biomedical Research, Liaocheng University, Liaocheng, China
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4
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Li MCH, O'Brien TJ, Todaro M, Powell KL. Acquired cardiac channelopathies in epilepsy: Evidence, mechanisms, and clinical significance. Epilepsia 2019; 60:1753-1767. [PMID: 31353444 DOI: 10.1111/epi.16301] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [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: 03/17/2019] [Revised: 07/07/2019] [Accepted: 07/07/2019] [Indexed: 12/13/2022]
Abstract
There is growing evidence that cardiac dysfunction in patients with chronic epilepsy could play a pathogenic role in sudden unexpected death in epilepsy (SUDEP). Recent animal studies have revealed that epilepsy secondarily alters the expression of cardiac ion channels alongside abnormal cardiac electrophysiology and remodeling. These molecular findings represent novel evidence for an acquired cardiac channelopathy in epilepsy, distinct from inherited ion channels mutations associated with cardiocerebral phenotypes. Specifically, seizure activity has been shown to alter the messenger RNA (mRNA) and protein expression of voltage-gated sodium channels (Nav 1.1, Nav 1.5), voltage-gated potassium channels (Kv 4.2, Kv 4.3), sodium-calcium exchangers (NCX1), and nonspecific cation-conducting channels (HCN2, HCN4). The pathophysiology may involve autonomic dysfunction and structural cardiac disease, as both are independently associated with epilepsy and ion channel dysregulation. Indeed, in vivo and in vitro studies of cardiac pathology reveal a complex network of signaling pathways and transcription factors regulating ion channel expression in the setting of sympathetic overactivity, cardiac failure, and hypertrophy. Other mechanisms such as circulating inflammatory mediators or exogenous effects of antiepileptic medications lack evidence. Moreover, an acquired cardiac channelopathy may underlie the electrophysiologic cardiac abnormalities seen in chronic epilepsy, potentially contributing to the increased risk of malignant arrhythmias and sudden death. Therefore, further investigation is necessary to establish whether cardiac ion channel dysregulation similarly occurs in patients with epilepsy, and to characterize any pathogenic relationship with SUDEP.
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Affiliation(s)
- Michael C H Li
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia.,Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia
| | - Terence J O'Brien
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia.,Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia
| | - Marian Todaro
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia.,Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia.,Department of Neurology, Royal Melbourne Hospital, Parkville, Victoria, Australia
| | - Kim L Powell
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
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5
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Spinelli V, Sartiani L, Mugelli A, Romanelli MN, Cerbai E. Hyperpolarization-activated cyclic-nucleotide-gated channels: pathophysiological, developmental, and pharmacological insights into their function in cellular excitability. Can J Physiol Pharmacol 2018; 96:977-984. [PMID: 29969572 DOI: 10.1139/cjpp-2018-0115] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The hyperpolarization-activated cyclic-nucleotide-gated (HCN) proteins are voltage-dependent ion channels, conducting both Na+ and K+, blocked by millimolar concentrations of extracellular Cs+ and modulated by cyclic nucleotides (mainly cAMP) that contribute crucially to the pacemaker activity in cardiac nodal cells and subsidiary pacemakers. Over the last decades, much attention has focused on HCN current, If, in non-pacemaker cardiac cells and its potential role in triggering arrhythmias. In fact, in addition to pacemakers, HCN current is constitutively present in the human atria and has long been proposed to sustain atrial arrhythmias associated to different cardiac pathologies or triggered by various modulatory signals (catecholamines, serotonin, natriuretic peptides). An atypical If occurs in diseased ventricular cardiomyocytes, its amplitude being linearly related to the severity of cardiac hypertrophy. The properties of atrial and ventricular If and its modulation by pharmacological interventions has been object of intense study, including the synthesis and characterization of new compounds able to block preferentially HCN1, HCN2, or HCN4 isoforms. Altogether, clues emerge for opportunities of future pharmacological strategies exploiting the unique properties of this channel family: the prevalence of different HCN subtypes in organs and tissues, the possibility to target HCN gain- or loss-of-function associated with disease, the feasibility of novel isoform-selective drugs, as well as the discovery of HCN-mediated effects for old medicines.
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Affiliation(s)
- Valentina Spinelli
- Department of Neurosciences, Psychology, Drug Research and Child Health (NeuroFarBa), University of Florence, Florence, Italy.,Department of Neurosciences, Psychology, Drug Research and Child Health (NeuroFarBa), University of Florence, Florence, Italy
| | - Laura Sartiani
- Department of Neurosciences, Psychology, Drug Research and Child Health (NeuroFarBa), University of Florence, Florence, Italy.,Department of Neurosciences, Psychology, Drug Research and Child Health (NeuroFarBa), University of Florence, Florence, Italy
| | - Alessandro Mugelli
- Department of Neurosciences, Psychology, Drug Research and Child Health (NeuroFarBa), University of Florence, Florence, Italy.,Department of Neurosciences, Psychology, Drug Research and Child Health (NeuroFarBa), University of Florence, Florence, Italy
| | - Maria Novella Romanelli
- Department of Neurosciences, Psychology, Drug Research and Child Health (NeuroFarBa), University of Florence, Florence, Italy.,Department of Neurosciences, Psychology, Drug Research and Child Health (NeuroFarBa), University of Florence, Florence, Italy
| | - Elisabetta Cerbai
- Department of Neurosciences, Psychology, Drug Research and Child Health (NeuroFarBa), University of Florence, Florence, Italy.,Department of Neurosciences, Psychology, Drug Research and Child Health (NeuroFarBa), University of Florence, Florence, Italy
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6
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Lee JH, Park JW, Byun JK, Kim HK, Ryu PD, Lee SY, Kim DY. Silencing of voltage-gated potassium channel KV9.3 inhibits proliferation in human colon and lung carcinoma cells. Oncotarget 2016; 6:8132-43. [PMID: 25924237 PMCID: PMC4480740 DOI: 10.18632/oncotarget.3517] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 02/03/2015] [Indexed: 01/12/2023] Open
Abstract
Voltage-gated potassium (Kv) channels are known to be involved in cancer development and cancer cell proliferation. KV9.3, an electronically silent subunit, forms heterotetramers with KV2.1 in excitable cells and modulates its electrophysiological properties. However, the role of KV9.3 alone in non-excitable cancer cells has not been studied. Here, we evaluated the effect of silencing KV9.3 on cancer cell proliferation in HCT15 colon carcinoma cells and A549 lung adenocarcinoma cells. We confirmed the expression of KV9.3 mRNA in HCT15 and A549 cells and showed that silencing KV9.3 using small interfering RNA caused G0/G1 cell cycle arrest and alterations in cell cycle regulatory proteins in both HCT15 and A549 cells without affecting apoptosis. Also, stable knockdown of KV9.3 expression using short-hairpin RNA inhibited tumor growth in SCID mouse xenograft model. Using a bioinformatics approach, we identified Sp1 binding sites in the promoter region of the gene encoding KV9.3. We further found that Sp1 bound to this region and showed that the Sp1 inhibitor, mithramycin A, induced a concentration-dependent decrease in KV9.3 expression. Taken together, these data suggest that knockdown of KV9.3 inhibits proliferation in colon carcinoma and lung adenocarcinoma cell lines and may be regulated by Sp1.
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Affiliation(s)
- Jeong-Ha Lee
- Laboratory of Veterinary Pathology, Seoul National University, Seoul, Korea
| | - Jun-Won Park
- Biomolecular Function Research Branch, National Cancer Center, Goyang, Gyeonggi, Korea
| | - Jun Kyu Byun
- Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, Korea
| | - Hark Kyun Kim
- Biomolecular Function Research Branch, National Cancer Center, Goyang, Gyeonggi, Korea
| | - Pan Dong Ryu
- Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, Korea
| | - So Yeong Lee
- Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, Korea
| | - Dae-Yong Kim
- Laboratory of Veterinary Pathology, Seoul National University, Seoul, Korea
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7
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Sun C, Yu D, Ye W, Liu C, Gu S, Sinsheimer NR, Song Z, Li X, Chen C, Song Y, Wang S, Schrader L, Chen Y. The short stature homeobox 2 (Shox2)-bone morphogenetic protein (BMP) pathway regulates dorsal mesenchymal protrusion development and its temporary function as a pacemaker during cardiogenesis. J Biol Chem 2014; 290:2007-23. [PMID: 25488669 DOI: 10.1074/jbc.m114.619007] [Citation(s) in RCA: 25] [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] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The atrioventricular (AV) junction plays a critical role in chamber septation and transmission of cardiac conduction pulses. It consists of structures that develop from embryonic dorsal mesenchymal protrusion (DMP) and the embryonic AV canal. Despite extensive studies on AV junction development, the genetic regulation of DMP development remains poorly understood. In this study we present evidence that Shox2 is expressed in the developing DMP. Intriguingly, this Shox2-expressing domain possesses a pacemaker-specific genetic profile including Hcn4 and Tbx3. This genetic profile leads to nodal-like electrophysiological properties, which is gradually silenced as the AV node becomes matured. Phenotypic analyses of Shox2(-/-) mice revealed a hypoplastic and defectively differentiated DMP, likely attributed to increased apoptosis, accompanied by dramatically reduced expression of Bmp4 and Hcn4, ectopic activation of Cx40, and an aberrant pattern of action potentials. Interestingly, conditional deletion of Bmp4 or inhibition of BMP signaling by overexpression of Noggin using a Shox2-Cre allele led to a similar DMP hypoplasia and down-regulation of Hcn4, whereas activation of a transgenic Bmp4 allele in Shox2(-/-) background attenuated DMP defects. Moreover, the lack of Hcn4 expression in the DMP of mice carrying Smad4 conditional deletion and direct binding of pSmad1/5/8 to the Hcn4 regulatory region further confirm the Shox2-BMP genetic cascade in the regulation of DMP development. Our results reveal that Shox2 regulates DMP fate and development by controlling BMP signaling through the Smad-dependent pathway to drive tissue growth and to induce Hcn4 expression and suggest a temporal pacemaking function for the DMP during early cardiogenesis.
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Affiliation(s)
- Cheng Sun
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Diankun Yu
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Wenduo Ye
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Chao Liu
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Shuping Gu
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Nathan R Sinsheimer
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Zhongchen Song
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Xihai Li
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Chun Chen
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Yingnan Song
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Shusheng Wang
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Laura Schrader
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - YiPing Chen
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
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8
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D'Souza A, Bucchi A, Johnsen AB, Logantha SJRJ, Monfredi O, Yanni J, Prehar S, Hart G, Cartwright E, Wisloff U, Dobryznski H, DiFrancesco D, Morris GM, Boyett MR. Exercise training reduces resting heart rate via downregulation of the funny channel HCN4. Nat Commun 2014; 5:3775. [PMID: 24825544 PMCID: PMC4024745 DOI: 10.1038/ncomms4775] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Accepted: 04/01/2014] [Indexed: 12/14/2022] Open
Abstract
Endurance athletes exhibit sinus bradycardia, that is a slow resting heart rate, associated with a higher incidence of sinus node (pacemaker) disease and electronic pacemaker implantation. Here we show that training-induced bradycardia is not a consequence of changes in the activity of the autonomic nervous system but is caused by intrinsic electrophysiological changes in the sinus node. We demonstrate that training-induced bradycardia persists after blockade of the autonomous nervous system in vivo in mice and in vitro in the denervated sinus node. We also show that a widespread remodelling of pacemaker ion channels, notably a downregulation of HCN4 and the corresponding ionic current, If. Block of If abolishes the difference in heart rate between trained and sedentary animals in vivo and in vitro. We further observe training-induced downregulation of Tbx3 and upregulation of NRSF and miR-1 (transcriptional regulators) that explains the downregulation of HCN4. Our findings provide a molecular explanation for the potentially pathological heart rate adaptation to exercise training. Endurance athletes are known to have a low resting heart rate. Here, D'Souza et al. propose that training-induced bradycardia is the result of electrophysiological changes in the sinus node, challenging the classical view that training-induced bradycardia is caused by increased activity of the autonomic nervous system.
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Affiliation(s)
- Alicia D'Souza
- 1] Institute of Cardiovascular Sciences, University of Manchester, Manchester M13 9NT, UK [2]
| | - Annalisa Bucchi
- 1] Department of Biosciences, University of Milano, Milano 20133, Italy [2]
| | - Anne Berit Johnsen
- 1] Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim 7491, Norway [2]
| | - Sunil Jit R J Logantha
- 1] Institute of Cardiovascular Sciences, University of Manchester, Manchester M13 9NT, UK [2]
| | - Oliver Monfredi
- Institute of Cardiovascular Sciences, University of Manchester, Manchester M13 9NT, UK
| | - Joseph Yanni
- Institute of Cardiovascular Sciences, University of Manchester, Manchester M13 9NT, UK
| | - Sukhpal Prehar
- Institute of Cardiovascular Sciences, University of Manchester, Manchester M13 9NT, UK
| | - George Hart
- Institute of Cardiovascular Sciences, University of Manchester, Manchester M13 9NT, UK
| | - Elizabeth Cartwright
- Institute of Cardiovascular Sciences, University of Manchester, Manchester M13 9NT, UK
| | - Ulrik Wisloff
- Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim 7491, Norway
| | - Halina Dobryznski
- Institute of Cardiovascular Sciences, University of Manchester, Manchester M13 9NT, UK
| | - Dario DiFrancesco
- Department of Biosciences, University of Milano, Milano 20133, Italy
| | - Gwilym M Morris
- Institute of Cardiovascular Sciences, University of Manchester, Manchester M13 9NT, UK
| | - Mark R Boyett
- Institute of Cardiovascular Sciences, University of Manchester, Manchester M13 9NT, UK
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9
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González-Ramírez R, Martínez-Hernández E, Sandoval A, Felix R. Transcription factor Sp1 regulates T-type Ca(2+) channel CaV 3.1 gene expression. J Cell Physiol 2014; 229:551-60. [PMID: 23868804 DOI: 10.1002/jcp.24432] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 07/11/2013] [Indexed: 01/30/2023]
Abstract
Voltage-gated T-type Ca(2+) (CaV 3) channels mediate a number of physiological events in developing and mature cells, and are implicated in neurological and cardiovascular diseases. In mammals, there are three distinct T-channel genes (CACNA1G, CACNA1H, and CACNA1I) encoding proteins (CaV 3.1-CaV 3.3) that differ in their localization as well as in molecular, biophysical, and pharmacological properties. The CACNA1G is a large gene that contains 38 exons and is localized in chromosome 17q22. Only basic characteristics of the CACNA1G gene promoter region have been investigated classifying it as a TATA-less sequence containing several potential transcription factor-binding motifs. Here, we cloned and characterized a proximal promoter region and initiated the analysis of transcription factors that control CaV 3.1 channel expression using the murine Cacna1g gene as a model. We isolated a ∼1.5 kb 5'-upstream region of Cacna1g and verified its transcriptional activity in the mouse neuroblastoma N1E-115 cell line. In silico analysis revealed that this region possesses a TATA-less minimal promoter that includes two potential transcription start sites and four binding sites for the transcription factor Sp1. The ability of one of these sites to interact with the transcription factor was confirmed by electrophoretic mobility shift assays. Consistent with this, Sp1 over-expression enhanced promoter activity while siRNA-mediated Sp1 silencing significantly decreased the level of CaV 3.1 protein and reduced the amplitude of whole-cell T-type Ca(2+) currents expressed in the N1E-115 cells. These results provide new insights into the molecular mechanisms that control CaV 3.1 channel expression.
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Affiliation(s)
- Ricardo González-Ramírez
- Department of Molecular Biology and Histocompatibility, "Dr. Manuel Gea González" General Hospital, Mexico City, Mexico
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10
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Luo X, Pan Z, Shan H, Xiao J, Sun X, Wang N, Lin H, Xiao L, Maguy A, Qi XY, Li Y, Gao X, Dong D, Zhang Y, Bai Y, Ai J, Sun L, Lu H, Luo XY, Wang Z, Lu Y, Yang B, Nattel S. MicroRNA-26 governs profibrillatory inward-rectifier potassium current changes in atrial fibrillation. J Clin Invest 2013; 123:1939-51. [PMID: 23543060 DOI: 10.1172/jci62185] [Citation(s) in RCA: 202] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 02/07/2013] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) is a highly prevalent arrhythmia with pronounced morbidity and mortality. Inward-rectifier K+ current (IK1) is believed to be an important regulator of reentrant-spiral dynamics and a major component of AF-related electrical remodeling. MicroRNA-26 (miR-26) is predicted to target the gene encoding KIR2.1, KCNJ2. We found that miR-26 was downregulated in atrial samples from AF animals and patients and this downregulation was accompanied by upregulation of IK1/KIR2.1 protein. miR-26 overexpression suppressed expression of KCNJ2/KIR2.1. In contrast, miR-26 knockdown, inhibition, or binding-site mutation enhanced KCNJ2/KIR2.1 expression, establishing KCNJ2 as a miR-26 target. Knockdown of endogenous miR-26 promoted AF in mice, whereas adenovirus-mediated expression of miR-26 reduced AF vulnerability. Kcnj2-specific miR-masks eliminated miR-26-mediated reductions in Kcnj2, abolishing miR-26's protective effects, while coinjection of a Kcnj2-specific miR-mimic prevented miR-26 knockdown-associated AF in mice. Nuclear factor of activated T cells (NFAT), a known actor in AF-associated remodeling, was found to negatively regulate miR-26 transcription. Our results demonstrate that miR-26 controls the expression of KCNJ2 and suggest that this downregulation may promote AF.
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Affiliation(s)
- Xiaobin Luo
- Research Center, Montreal Heart Institute, Montreal, Quebec, Canada
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11
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Martínez-hernández E, González-ramírez R, Sandoval A, Cisneros B, Delgado-lezama R, Felix R. Isolation and characterization of the 5´-upstream region of the human voltage-gated Ca2+ channel α2δ-1 auxiliary subunit gene: promoter analysis and regulation by transcription factor Sp1. Pflugers Arch 2013; 465:819-28. [DOI: 10.1007/s00424-012-1194-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 11/07/2012] [Accepted: 11/29/2012] [Indexed: 01/07/2023]
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12
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Vedantham V, Evangelista M, Huang Y, Srivastava D. Spatiotemporal regulation of an Hcn4 enhancer defines a role for Mef2c and HDACs in cardiac electrical patterning. Dev Biol 2012; 373:149-62. [PMID: 23085412 DOI: 10.1016/j.ydbio.2012.10.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [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: 07/02/2012] [Revised: 10/11/2012] [Accepted: 10/12/2012] [Indexed: 11/17/2022]
Abstract
Regional differences in cardiomyocyte automaticity permit the sinoatrial node (SAN) to function as the leading cardiac pacemaker and the atrioventricular (AV) junction as a subsidiary pacemaker. The regulatory mechanisms controlling the distribution of automaticity within the heart are not understood. To understand regional variation in cardiac automaticity, we carried out an in vivo analysis of cis-regulatory elements that control expression of the hyperpolarization-activated cyclic-nucleotide gated ion channel 4 (Hcn4). Using transgenic mice, we found that spatial and temporal patterning of Hcn4 expression in the AV conduction system required cis-regulatory elements with multiple conserved fragments. One highly conserved region, which contained a myocyte enhancer factor 2C (Mef2C) binding site previously described in vitro, induced reporter expression specifically in the embryonic non-chamber myocardium and the postnatal AV bundle in a Mef2c-dependent manner in vivo. Inhibition of histone deacetylase (HDAC) activity in cultured transgenic embryos showed expansion of reporter activity to working myocardium. In adult animals, hypertrophy induced by transverse aortic constriction, which causes translocation of HDACs out of the nucleus, resulted in ectopic activation of the Hcn4 enhancer in working myocardium, recapitulating pathological electrical remodeling. These findings reveal mechanisms that control the distribution of automaticity among cardiomyocytes during development and in response to stress.
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Affiliation(s)
- Vasanth Vedantham
- Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, CA 94158, USA.
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13
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Becher PM, Lindner D, Miteva K, Savvatis K, Zietsch C, Schmack B, Van Linthout S, Westermann D, Schultheiss HP, Tschöpe C. Role of Heart Rate Reduction in the Prevention of Experimental Heart Failure. Hypertension 2012; 59:949-57. [DOI: 10.1161/hypertensionaha.111.183913] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Peter Moritz Becher
- From the Department of Cardiology and Pneumology (P.M.B., D.L., K.S., C.Z., D.W., H.-P.S., C.T.) and Berlin-Brandenburg Center for Regenerative Therapies (K.M., S.V.L., C.T.), Charité-Universitätsmedizin Berlin, Berlin, Germany; Department of Cardiac Surgery (B.S.), University of Heidelberg, Heidelberg, Germany
| | - Diana Lindner
- From the Department of Cardiology and Pneumology (P.M.B., D.L., K.S., C.Z., D.W., H.-P.S., C.T.) and Berlin-Brandenburg Center for Regenerative Therapies (K.M., S.V.L., C.T.), Charité-Universitätsmedizin Berlin, Berlin, Germany; Department of Cardiac Surgery (B.S.), University of Heidelberg, Heidelberg, Germany
| | - Kapka Miteva
- From the Department of Cardiology and Pneumology (P.M.B., D.L., K.S., C.Z., D.W., H.-P.S., C.T.) and Berlin-Brandenburg Center for Regenerative Therapies (K.M., S.V.L., C.T.), Charité-Universitätsmedizin Berlin, Berlin, Germany; Department of Cardiac Surgery (B.S.), University of Heidelberg, Heidelberg, Germany
| | - Konstantinos Savvatis
- From the Department of Cardiology and Pneumology (P.M.B., D.L., K.S., C.Z., D.W., H.-P.S., C.T.) and Berlin-Brandenburg Center for Regenerative Therapies (K.M., S.V.L., C.T.), Charité-Universitätsmedizin Berlin, Berlin, Germany; Department of Cardiac Surgery (B.S.), University of Heidelberg, Heidelberg, Germany
| | - Christin Zietsch
- From the Department of Cardiology and Pneumology (P.M.B., D.L., K.S., C.Z., D.W., H.-P.S., C.T.) and Berlin-Brandenburg Center for Regenerative Therapies (K.M., S.V.L., C.T.), Charité-Universitätsmedizin Berlin, Berlin, Germany; Department of Cardiac Surgery (B.S.), University of Heidelberg, Heidelberg, Germany
| | - Bastian Schmack
- From the Department of Cardiology and Pneumology (P.M.B., D.L., K.S., C.Z., D.W., H.-P.S., C.T.) and Berlin-Brandenburg Center for Regenerative Therapies (K.M., S.V.L., C.T.), Charité-Universitätsmedizin Berlin, Berlin, Germany; Department of Cardiac Surgery (B.S.), University of Heidelberg, Heidelberg, Germany
| | - Sophie Van Linthout
- From the Department of Cardiology and Pneumology (P.M.B., D.L., K.S., C.Z., D.W., H.-P.S., C.T.) and Berlin-Brandenburg Center for Regenerative Therapies (K.M., S.V.L., C.T.), Charité-Universitätsmedizin Berlin, Berlin, Germany; Department of Cardiac Surgery (B.S.), University of Heidelberg, Heidelberg, Germany
| | - Dirk Westermann
- From the Department of Cardiology and Pneumology (P.M.B., D.L., K.S., C.Z., D.W., H.-P.S., C.T.) and Berlin-Brandenburg Center for Regenerative Therapies (K.M., S.V.L., C.T.), Charité-Universitätsmedizin Berlin, Berlin, Germany; Department of Cardiac Surgery (B.S.), University of Heidelberg, Heidelberg, Germany
| | - Heinz-Peter Schultheiss
- From the Department of Cardiology and Pneumology (P.M.B., D.L., K.S., C.Z., D.W., H.-P.S., C.T.) and Berlin-Brandenburg Center for Regenerative Therapies (K.M., S.V.L., C.T.), Charité-Universitätsmedizin Berlin, Berlin, Germany; Department of Cardiac Surgery (B.S.), University of Heidelberg, Heidelberg, Germany
| | - Carsten Tschöpe
- From the Department of Cardiology and Pneumology (P.M.B., D.L., K.S., C.Z., D.W., H.-P.S., C.T.) and Berlin-Brandenburg Center for Regenerative Therapies (K.M., S.V.L., C.T.), Charité-Universitätsmedizin Berlin, Berlin, Germany; Department of Cardiac Surgery (B.S.), University of Heidelberg, Heidelberg, Germany
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Ferrero GB, Picco G, Baldassarre G, Flex E, Isella C, Cantarella D, Corà D, Chiesa N, Crescenzio N, Timeus F, Merla G, Mazzanti L, Zampino G, Rossi C, Silengo M, Tartaglia M, Medico E. Transcriptional hallmarks of Noonan syndrome and Noonan-like syndrome with loose anagen hair. Hum Mutat 2012; 33:703-9. [PMID: 22253195 PMCID: PMC3332054 DOI: 10.1002/humu.22026] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Accepted: 01/04/2012] [Indexed: 11/29/2022]
Abstract
Noonan syndrome (NS) is among the most common nonchromosomal disorders affecting development and growth. NS is genetically heterogeneous, being caused by germline mutations affecting various genes implicated in the RAS signaling network. This network transduces extracellular signals into intracellular biochemical and transcriptional responses controlling cell proliferation, differentiation, metabolism, and senescence. To explore the transcriptional consequences of NS-causing mutations, we performed global mRNA expression profiling on peripheral blood mononuclear cells obtained from 23 NS patients carrying heterozygous mutations in PTPN11 or SOS1. Gene expression profiling was also resolved in five subjects with Noonan-like syndrome with loose anagen hair (NS/LAH), a condition clinically related to NS and caused by an invariant mutation in SHOC2. Robust transcriptional signatures were found to specifically discriminate each of the three mutation groups from 21 age- and sex-matched controls. Despite the only partial overlap in terms of gene composition, the three signatures showed a notable concordance in terms of biological processes and regulatory circuits affected. These data establish expression profiling of peripheral blood mononuclear cells as a powerful tool to appreciate differential perturbations driven by germline mutations of transducers involved in RAS signaling and to dissect molecular mechanisms underlying NS and other RASopathies. Hum Mutat 33:703–709, 2012. © 2012 Wiley Periodicals, Inc.
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Chen PS, Ai T. Is c-Src tyrosine kinase a new target for antiarrhythmic drug therapy? J Am Coll Cardiol 2011; 58:2340-1. [PMID: 22093513 DOI: 10.1016/j.jacc.2011.09.005] [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] [Received: 08/23/2011] [Accepted: 09/05/2011] [Indexed: 10/15/2022]
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16
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Lin H, Li Z, Chen C, Luo X, Xiao J, Dong D, Lu Y, Yang B, Wang Z. Transcriptional and post-transcriptional mechanisms for oncogenic overexpression of ether à go-go K+ channel. PLoS One 2011; 6:e20362. [PMID: 21655246 PMCID: PMC3105031 DOI: 10.1371/journal.pone.0020362] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [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: 01/22/2011] [Accepted: 04/30/2011] [Indexed: 11/23/2022] Open
Abstract
The human ether-à-go-go-1 (h-eag1) K+ channel is expressed in a variety of cell lines derived from human malignant tumors and in clinical samples of several different cancers, but is otherwise absent in normal tissues. It was found to be necessary for cell cycle progression and tumorigenesis. Specific inhibition of h-eag1 expression leads to inhibition of tumor cell proliferation. We report here that h-eag1 expression is controlled by the p53−miR-34−E2F1 pathway through a negative feed-forward mechanism. We first established E2F1 as a transactivator of h-eag1 gene through characterizing its promoter region. We then revealed that miR-34, a known transcriptional target of p53, is an important negative regulator of h-eag1 through dual mechanisms by directly repressing h-eag1 at the post-transcriptional level and indirectly silencing h-eag1 at the transcriptional level via repressing E2F1. There is a strong inverse relationship between the expression levels of miR-34 and h-eag1 protein. H-eag1antisense antagonized the growth-stimulating effects and the upregulation of h-eag1 expression in SHSY5Y cells, induced by knockdown of miR-34, E2F1 overexpression, or inhibition of p53 activity. Therefore, p53 negatively regulates h-eag1 expression by a negative feed-forward mechanism through the p53−miR-34−E2F1 pathway. Inactivation of p53 activity, as is the case in many cancers, can thus cause oncogenic overexpression of h-eag1 by relieving the negative feed-forward regulation. These findings not only help us understand the molecular mechanisms for oncogenic overexpression of h-eag1 in tumorigenesis but also uncover the cell-cycle regulation through the p53−miR-34−E2F1−h-eag1 pathway. Moreover, these findings place h-eag1 in the p53−miR-34−E2F1−h-eag1 pathway with h-eag as a terminal effecter component and with miR-34 (and E2F1) as a linker between p53 and h-eag1. Our study therefore fills the gap between p53 pathway and its cellular function mediated by h-eag1.
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Affiliation(s)
- Huixian Lin
- Research Center, Montreal Heart Institute, Montreal, Quebec, Canada
| | - Zhe Li
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
| | - Chang Chen
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
| | - Xiaobin Luo
- Research Center, Montreal Heart Institute, Montreal, Quebec, Canada
- Department of Medicine, Universite de Montreal, Montreal, Quebec, Canada
- Cardiovascular Research Institute (Key Laboratory of Cardiovascular Research, Ministry of Education of China), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
| | - Jiening Xiao
- Research Center, Montreal Heart Institute, Montreal, Quebec, Canada
| | - Deli Dong
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
| | - Yanjie Lu
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
- Cardiovascular Research Institute (Key Laboratory of Cardiovascular Research, Ministry of Education of China), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
| | - Baofeng Yang
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
- Cardiovascular Research Institute (Key Laboratory of Cardiovascular Research, Ministry of Education of China), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
- * E-mail: (ZW); (BY)
| | - Zhiguo Wang
- Research Center, Montreal Heart Institute, Montreal, Quebec, Canada
- Department of Medicine, Universite de Montreal, Montreal, Quebec, Canada
- Cardiovascular Research Institute (Key Laboratory of Cardiovascular Research, Ministry of Education of China), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
- * E-mail: (ZW); (BY)
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17
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Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are expressed in the brain and heart and are essential for physiological functions in cardiac and nervous systems. We identified two Hcn4 mRNA variants with different transcription start sites and differential expression patterns in mouse brain and heart. Only one mRNA variant was detected in the brain, whereas both variants were found in the heart. Patch clamp recordings of these two variants in HEK293H cells revealed different electrophysiological properties in channel activation. Mutagenesis studies showed that three positively charged amino acids (Arg-9, Lys-10, and Lys-22) contribute to the functional difference. Our results demonstrate that HCN4 channels are expressed in different patterns in mouse brain and heart and that the N terminus is important for HCN4 channel activation.
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Affiliation(s)
- He Liu
- Section of Neurobiology, Center for Learning and Memory, University of Texas, Austin, Texas 78712, USA
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