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Related Concept Videos

Conduction System of the Heart01:20

Conduction System of the Heart

The cardiac conduction system produces and transmits electrical impulses that prompt myocardial contraction, ensuring efficient heart function. This intricate system ensures that the heart beats in a coordinated and efficient manner, beginning with the atria and then the ventricles. The conduction system optimizes cardiac output by maintaining this precise sequence, which is crucial for adequate blood circulation.
This system relies on the unique properties of nodal and Purkinje cells:...
Conduction System of the Heart01:19

Conduction System of the Heart

Autorhythmicity is a term that refers to the heart's inherent ability to generate electrical signals and instigate muscle contractions. This self-regulating conduction system within the heart consists of two key components: the pacemaker cells and specialized conducting cells.
The pacemaker cells are located in two primary nodes: the sinoatrial (SA) node and the atrioventricular (AV) node. The SA node pacemaker cells can autonomously depolarize, triggering an action potential that leads to the...
Mechanism of Cardiac Arrhythmias01:28

Mechanism of Cardiac Arrhythmias

Arrhythmias are irregular heart rhythms occurring when the heart's electrical impulses become abnormal. These disturbances can lead to various symptoms, depending on their severity and the underlying cause. Some common factors contributing to arrhythmias include hypoxia, ischemia, electrolyte imbalances, excessive catecholamine exposure, drug toxicity, and muscle overstretching. Arrhythmias can be classified into two main types based on the rate and site of origin of abnormal heart rhythms.
General Transcription Factors01:30

General Transcription Factors

Tissue-specific transcription factors contribute to diverse cellular functions in mammals. For example, the gene for beta globin, a major component of hemoglobin, is present in all cells of the body. However, it is only expressed in red blood cells because the transcription factors that can bind to the promoter sequences of the beta globin gene are only expressed in these cells. Tissue-specific transcription factors also ensure that mutations in these factors may impair only the function of...
Cardiac Action Potential01:30

Cardiac Action Potential

Cardiac action potentials are essential for proper heart function, enabling the rhythmic contractions needed for adequate blood circulation. Nodal cells and Purkinje fibers, specialized for electrical conduction, generate these action potentials.
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials
Transcription Factors02:16

Transcription Factors

Tissue-specific transcription factors contribute to diverse cellular functions in mammals. For example, the gene for beta globin, a major component of hemoglobin, is present in all cells of the body. However, it is only expressed in red blood cells because the transcription factors that can bind to the promoter sequences of the beta globin gene are only expressed in these cells. Tissue-specific transcription factors also ensure that mutations in these factors may impair only the function of...

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Related Experiment Video

Updated: May 21, 2026

Generation of Murine Cardiac Pacemaker Cell Aggregates Based on ES-Cell-Programming in Combination with Myh6-Promoter-Selection
08:52

Generation of Murine Cardiac Pacemaker Cell Aggregates Based on ES-Cell-Programming in Combination with Myh6-Promoter-Selection

Published on: February 17, 2015

TBX5 drives Scn5a expression to regulate cardiac conduction system function.

David E Arnolds1, Fang Liu, John P Fahrenbach

  • 1Department of Pediatrics, University of Chicago, Chicago, IL, USA.

The Journal of Clinical Investigation
|June 26, 2012
PubMed
Summary
This summary is machine-generated.

TBX5 is crucial for maintaining the function of the mature cardiac conduction system (CCS). Deleting TBX5 severely disrupts conduction, leading to arrhythmias and sudden death, highlighting its role in CCS disease.

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Area of Science:

  • Cardiovascular Biology
  • Molecular Cardiology
  • Genetics

Background:

  • Cardiac conduction system (CCS) diseases cause significant morbidity and mortality.
  • Limited treatments necessitate understanding molecular networks for regenerative therapies.
  • Genome-wide association studies (GWAS) identified TBX5 and SCN5A as loci associated with CCS function.

Purpose of the Study:

  • To investigate the role of TBX5 in regulating transcriptional networks essential for mature cardiac conduction system (CCS) function.
  • To determine the impact of TBX5 deletion on the mature ventricular conduction system (VCS).

Main Methods:

  • Generated VCS-specific Tbx5 knockouts in mice.
  • Assessed VCS function, ventricular contractile function, and VCS fate mapping.
  • Analyzed the expression of key conduction mediators like Nav1.5 (encoded by Scn5a) and connexin 40 (Cx40).
  • Identified and characterized a TBX5-responsive enhancer downstream of Scn5a.

Main Results:

  • Tbx5 deletion in the mature VCS caused severe conduction defects, arrhythmias, and sudden death.
  • Ventricular contractile function and VCS fate mapping were unaffected by Tbx5 deletion.
  • TBX5 directly regulates the expression of Nav1.5 and Cx40 in the VCS.
  • A TBX5-responsive enhancer downstream of Scn5a drives VCS expression.

Conclusions:

  • TBX5 is essential for mature cardiac conduction system (CCS) function.
  • Establishes a direct molecular link between TBX5 and Scn5a in the VCS.
  • Provides a paradigm for understanding the molecular pathology of CCS disease and human GWAS loci hierarchy.