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A MicroRNA-Transcription Factor Blueprint for Early Atrial Arrhythmogenic Remodeling.

Torrado M, Franco D, Lozano-Velasco E, Hernández-Torres F, Calviño R, Aldama G, Centeno A, Castro-Beiras A, Mikhailov A - Biomed Res Int (2015)

Bottom Line: The downregulation of Pitx2, Tbx5, and Myocd was inversely correlated with upregulation of the corresponding targeting miRNAs (miR-21, miR-10a/10b, and miR-1, resp.) in the LA of paced animals.Through in vitro transient transfections of HL-1 atrial myocytes, we further showed that upregulation of miR-21 did result in downregulation of Pitx2 in cardiomyocyte background.The results suggest that immediate-early miRNA remodeling coupled with deregulation of TF expression underlies the onset of AF.

View Article: PubMed Central - PubMed

Affiliation: Institute of Health Sciences, University of La Coruña, 15006 La Coruña, Spain.

ABSTRACT
Spontaneous self-terminating atrial fibrillation (AF) is one of the most common heart rhythm disorders, yet the regulatory molecular mechanisms underlying this syndrome are rather unclear. MicroRNA (miRNA) transcriptome and expression of candidate transcription factors (TFs) with potential roles in arrhythmogenesis, such as Pitx2, Tbx5, and myocardin (Myocd), were analyzed by microarray, qRT-PCR, and Western blotting in left atrial (LA) samples from pigs with transitory AF established by right atrial tachypacing. Induced ectopic tachyarrhythmia caused rapid and substantial miRNA remodeling associated with a marked downregulation of Pitx2, Tbx5, and Myocd expression in atrial myocardium. The downregulation of Pitx2, Tbx5, and Myocd was inversely correlated with upregulation of the corresponding targeting miRNAs (miR-21, miR-10a/10b, and miR-1, resp.) in the LA of paced animals. Through in vitro transient transfections of HL-1 atrial myocytes, we further showed that upregulation of miR-21 did result in downregulation of Pitx2 in cardiomyocyte background. The results suggest that immediate-early miRNA remodeling coupled with deregulation of TF expression underlies the onset of AF.

No MeSH data available.


Related in: MedlinePlus

An electrical pacing assay. (a) Anaesthetized piglet (with automatic artificial lung ventilation) in the animal operating room. (b) Placing a pacing catheter in the right atrium (RA) using fluoroscopic guidance. (c) Representative telemetry ECG recordings monitored before, during, and after RA burst pacing.
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fig1: An electrical pacing assay. (a) Anaesthetized piglet (with automatic artificial lung ventilation) in the animal operating room. (b) Placing a pacing catheter in the right atrium (RA) using fluoroscopic guidance. (c) Representative telemetry ECG recordings monitored before, during, and after RA burst pacing.

Mentions: “Large white” 3-month-old pigs were obtained from a local commercial breeder (La Coruña, Spain) and randomly divided into two groups: (1) sham (n = 5; mean body weight, 25.2 ± 1.2 kg) and (2) atrial tachypacing (n = 5; mean body weight, 25.7 ± 0.8 kg). A close-chest tachyarrhythmia model was established in animals via rapid atrial electrical stimulation with a controlled ventricular response rate. To control anaesthesia, ventilation, and oxygenation, ECG, heart rhythm, and blood pressure were continuously monitored. The right femoral vein was dissected and cannulated with a multielectrode catheter (Medtronic, Minneapolis, USA) connected with an external pulse stimulator (A-M Systems, UK) for programmed pacing rates. Under fluoroscopic guidance, the catheter was passed into the right atrium (Figure 1). To avoid tachycardia-induced ventricular dysfunction (ventricular arrhythmias), esmolol hydrochloride (a beta adrenergic receptor blocker) was given before pacing. After a 5-minute stabilization of sinus rate, a three-burst-pacing (at 800 bpm) protocol was performed in each animal of the paced group. Occurrence and duration of rhythm disturbances were characterized by ECG (Figure 1). The duration of induced self-terminating paroxysms of AF was measured from the end of the last stimulus of the burst pacing to the first P-wave upon spontaneous reversion to normal sinus rhythm. Burst pacing was not performed in the sham-operated group. Animals were euthanized 20–24 hours after cessation of pacing to harvest cardiac tissues for RNA and protein isolation and histology. Animals were used in accordance with the European Commission Directive 86/609/EEC and all protocols were approved by the Institutional Animal Care and Use Ethics Committee (permit number: CE 012/2012; University of La Coruña, La Coruña, Spain).


A MicroRNA-Transcription Factor Blueprint for Early Atrial Arrhythmogenic Remodeling.

Torrado M, Franco D, Lozano-Velasco E, Hernández-Torres F, Calviño R, Aldama G, Centeno A, Castro-Beiras A, Mikhailov A - Biomed Res Int (2015)

An electrical pacing assay. (a) Anaesthetized piglet (with automatic artificial lung ventilation) in the animal operating room. (b) Placing a pacing catheter in the right atrium (RA) using fluoroscopic guidance. (c) Representative telemetry ECG recordings monitored before, during, and after RA burst pacing.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4499376&req=5

fig1: An electrical pacing assay. (a) Anaesthetized piglet (with automatic artificial lung ventilation) in the animal operating room. (b) Placing a pacing catheter in the right atrium (RA) using fluoroscopic guidance. (c) Representative telemetry ECG recordings monitored before, during, and after RA burst pacing.
Mentions: “Large white” 3-month-old pigs were obtained from a local commercial breeder (La Coruña, Spain) and randomly divided into two groups: (1) sham (n = 5; mean body weight, 25.2 ± 1.2 kg) and (2) atrial tachypacing (n = 5; mean body weight, 25.7 ± 0.8 kg). A close-chest tachyarrhythmia model was established in animals via rapid atrial electrical stimulation with a controlled ventricular response rate. To control anaesthesia, ventilation, and oxygenation, ECG, heart rhythm, and blood pressure were continuously monitored. The right femoral vein was dissected and cannulated with a multielectrode catheter (Medtronic, Minneapolis, USA) connected with an external pulse stimulator (A-M Systems, UK) for programmed pacing rates. Under fluoroscopic guidance, the catheter was passed into the right atrium (Figure 1). To avoid tachycardia-induced ventricular dysfunction (ventricular arrhythmias), esmolol hydrochloride (a beta adrenergic receptor blocker) was given before pacing. After a 5-minute stabilization of sinus rate, a three-burst-pacing (at 800 bpm) protocol was performed in each animal of the paced group. Occurrence and duration of rhythm disturbances were characterized by ECG (Figure 1). The duration of induced self-terminating paroxysms of AF was measured from the end of the last stimulus of the burst pacing to the first P-wave upon spontaneous reversion to normal sinus rhythm. Burst pacing was not performed in the sham-operated group. Animals were euthanized 20–24 hours after cessation of pacing to harvest cardiac tissues for RNA and protein isolation and histology. Animals were used in accordance with the European Commission Directive 86/609/EEC and all protocols were approved by the Institutional Animal Care and Use Ethics Committee (permit number: CE 012/2012; University of La Coruña, La Coruña, Spain).

Bottom Line: The downregulation of Pitx2, Tbx5, and Myocd was inversely correlated with upregulation of the corresponding targeting miRNAs (miR-21, miR-10a/10b, and miR-1, resp.) in the LA of paced animals.Through in vitro transient transfections of HL-1 atrial myocytes, we further showed that upregulation of miR-21 did result in downregulation of Pitx2 in cardiomyocyte background.The results suggest that immediate-early miRNA remodeling coupled with deregulation of TF expression underlies the onset of AF.

View Article: PubMed Central - PubMed

Affiliation: Institute of Health Sciences, University of La Coruña, 15006 La Coruña, Spain.

ABSTRACT
Spontaneous self-terminating atrial fibrillation (AF) is one of the most common heart rhythm disorders, yet the regulatory molecular mechanisms underlying this syndrome are rather unclear. MicroRNA (miRNA) transcriptome and expression of candidate transcription factors (TFs) with potential roles in arrhythmogenesis, such as Pitx2, Tbx5, and myocardin (Myocd), were analyzed by microarray, qRT-PCR, and Western blotting in left atrial (LA) samples from pigs with transitory AF established by right atrial tachypacing. Induced ectopic tachyarrhythmia caused rapid and substantial miRNA remodeling associated with a marked downregulation of Pitx2, Tbx5, and Myocd expression in atrial myocardium. The downregulation of Pitx2, Tbx5, and Myocd was inversely correlated with upregulation of the corresponding targeting miRNAs (miR-21, miR-10a/10b, and miR-1, resp.) in the LA of paced animals. Through in vitro transient transfections of HL-1 atrial myocytes, we further showed that upregulation of miR-21 did result in downregulation of Pitx2 in cardiomyocyte background. The results suggest that immediate-early miRNA remodeling coupled with deregulation of TF expression underlies the onset of AF.

No MeSH data available.


Related in: MedlinePlus