Genetic variation in T-box binding element functionally affects SCN5A/SCN10A enhancer.

Area of Science:

• Cardiovascular Biology
• Molecular Genetics
• Epigenetics

Background:

• Cardiac conduction relies on precise electrical impulse propagation.
• Disruptions in cardiac conduction are linked to arrhythmias and sudden cardiac arrest.
• Gene expression regulation by transcription factors and enhancers controls cardiac conduction patterns.

Purpose of the Study:

• To map genome-wide binding sites of key cardiac transcription factors (TBX3, NKX2-5, GATA4) and coactivator p300 in the mouse heart.
• To identify cardiac enhancers and their relationship with ion channel genes.
• To investigate the role of specific enhancers and genetic variants in cardiac conduction.

Main Methods:

• Genome-wide ChIP-seq for TBX3, NKX2-5, GATA4, and p300 in mouse hearts.
• Identification and characterization of cardiac enhancers.
• Functional analysis of enhancers in the Scn5a/Scn10a locus.
• In vivo assessment of a human SNP in the SCN10A enhancer.

Main Results:

• Discovered numerous cardiac enhancers across the genome.
• Found colocalization of enhancers with TBX3-repressed ion channel genes, including Scn5a and Scn10a.
• Identified two enhancers in the Scn5a/Scn10a locus regulated by TBX3/TBX5, conserved in humans.
• Demonstrated that a human SNP in an SCN10A enhancer disrupts transcription factor binding and reduces enhancer activity.

Conclusions:

• This study identifies critical regulatory elements controlling cardiac conduction.
• Genetic variants in noncoding DNA can alter cardiac conduction by affecting enhancer function.
• Findings provide insights into the genetic basis of cardiac arrhythmias.