Conserved Chamber-Specific Polyploidy Maintains Heart Function in Drosophila

Area of Science:

• Developmental Biology
• Cardiovascular Biology
• Genetics

Background:

• Developmentally programmed polyploidy (whole-genome duplication) in cardiomyocytes is evolutionarily conserved but its function remains largely unknown.
• Cardiac tissue exhibits chamber-specific polyploidy levels, suggesting specialized roles.
• Understanding polyploidy's function is critical for addressing heart failure and injury recovery.

Approach:

• Investigated the role of polyploidy in cardiac function using *Drosophila* models.
• Analyzed differential Insulin Receptor (InR) sensitivity to understand polyploidy regulation.
• Examined nuclear volume and insulin signaling in human donor hearts to assess cross-species conservation.

Key Points:

• A conserved asymmetry in polyploidy levels exists between cardiac chambers in *Drosophila* and humans.
• Differential InR sensitivity drives higher polyploidy and cell size in the *Drosophila* heart chamber compared to the aorta.
• Reduced polyploidy in *Drosophila* leads to phenotypes mimicking human heart failure, including reduced cardiac output.

Conclusions:

• Precise polyploidy levels play essential, conserved roles in cardiac chamber development and function.
• Polyploidy asymmetry is a key feature sculpted during the development of many tissues.
• These findings challenge the notion of blocking developmental polyploidy for heart injury recovery and highlight its productive roles.