Do growth and cell division rates determine cell size in multicellular organisms?

Area of Science:

• Developmental Biology
• Cell Biology
• Genetics

Background:

• Cell size determination is well-studied in unicellular eukaryotes like yeast, but less understood in multicellular organisms.
• Coordination between cell growth and cell division is crucial for maintaining reproducible cell sizes in multicellular tissues.

Purpose of the Study:

• To investigate the role of the insulin/phosphoinositide 3-kinase (PI3K) signaling pathway in regulating cell size and organ growth during Drosophila melanogaster development.
• To explore the relationship between cell growth, cell division, and cell size control in a multicellular context.

Main Methods:

• Utilized Drosophila melanogaster as a model organism.
• Studied mutations in genes encoding homologues of the mammalian insulin/PI3K signaling pathway components.
• Analyzed effects on imaginal disc development, organ growth, and cell size.

Main Results:

• Signaling through the insulin/PI3K pathway impacts organ growth (increase in mass) more than cell division.
• Cell size appears to be a consequence of the relative rates of tissue growth and cell division.
• The pathway can influence cell cycle phasing and cell division, suggesting a mechanism for coordinating growth and division.

Conclusions:

• Cell size in multicellular organisms may be determined by the independent regulation of growth and division, with size being an emergent property.
• The insulin/PI3K pathway plays a significant role in coordinating cell growth and division, potentially ensuring cells divide only when they reach a minimum size.