size control

A key difference between yeast and metazoans is the need of the latter to regulate cell proliferation and growth to create organs (and organisms) of reproducible size and shape. Great progress has been made in understanding how growth, cell size and the cell cycle are controlled in metazoans.

Disruption of conserved components of the insulin and mTOR kinase (FRAP1) pathways can alter organ size, indicating that the normal functioning of these pathways is essential for organ size control.

However, disruption of genes that regulate patterning and of genes that control cell adhesion and cell polarity has a much more dramatic effect on final organ size than does manipulation of the cell cycle or of basal growth control mechanisms.

These data point to an ’organ-size checkpoint’ that regulates cell division, cell growth and apoptosis. Recent data suggests that cell competition may play an important role in implementing the organ-size checkpoint.

Types

 cell size
 organ size
 organism size and body size

References

 Leevers SJ, McNeill H. Controlling the size of organs and organisms. Curr Opin Cell Biol. 2005 Dec;17(6):604-9. PMID: 16226450

 Umen JG. The elusive sizer. Curr Opin Cell Biol. 2005 Aug;17(4):435-41. PMID: 15978795

 Kozma SC, Thomas G: Regulation of cell size in growth, development and human disease: PI3K, PKB and S6K. Bioessays 24:65, 2002.