Transcriptional Control of Cell Growth : The E2F Gene Family

It is of critical importance to maintain an appropriate balance between proliferation and quiescence or differentiation through- out the lifespan of all animals.

An important control point in this balance occurs in the G, phase of the cell cycle.

On the basis of environmental cues a cell in G, must decide whether to continue through the proliferative cycle and enter S phase (where DNA replication occurs) or to exit from the proliferative cycle into a nonreplicating state.

Alterations in the mechanisms that nor- mally control this decision can lead to cancer, cell death, or loss of differentiated cellular phenotypes.

The identification of the E2F gene family of transcription factors has allowed a more complete understanding of how the cell maintains an appropri- ate proliferative state.

This volume provides an up-to-date ac- count of present reports concerning E2F as well as a framework for future investigations.

E2F activity requires heterodimerization of two partners.

Either partner can be one of several different transcription factors; E2Fl, E2F2, E2F3, E2F4, or E2F5 can heterodimerize with either DPl or DP2.

Cellular promoters whose E2F sites mediate a link between transcription and proliferation drive genes whose products are required for DNA synthesis and genes that encode regulators of cell growth.

A detailed analY$is of the role that E2F family members play in transcription from these promoters is presented in the chapter by J.

E. SLANSKY and P. J. FARNHAM.