Hand2 is an essential regulator for two Notch-dependent functions within the embryonic endocardium

Area of Science:

• Cardiovascular Biology
• Developmental Biology
• Molecular Genetics

Background:

• The transcription factor Hand2 is vital for cardiac morphogenesis, acting in myocardial, neural crest, and epicardial cells.
• Notch signaling pathways are essential regulators of cardiac development and cell-cell communication.

Purpose of the Study:

• To elucidate the specific roles of Hand2 within the endocardium during heart development.
• To investigate the molecular mechanisms by which Hand2 influences cardiac morphogenesis and vasculogenesis.

Main Methods:

• Genetic ablation of Hand2 in endocardial cells.
• Analysis of cardiac morphology and valve development.
• Molecular analysis of downstream gene targets and signaling pathways (Notch, VEGF).

Main Results:

• Endocardial Hand2 deficiency causes tricuspid valve defects, septal abnormalities, and hypotrabeculated ventricles, mimicking tricuspid atresia.
• Hand2 is a downstream effector of Notch signaling, regulating Neuregulin1 expression.
• Hand2 influences endocardium-to-endocardium signaling, affecting coronary lumen density and dysregulating VEGF pathway components.

Conclusions:

• Hand2 plays critical, Notch-dependent roles in endocardial cells during cardiogenesis.
• Hand2 is essential for proper valve formation, ventricular development, and coronary vasculogenesis.
• Hand2 acts as a key transcriptional regulator in endocardial signaling pathways impacting heart development.