In most tissues, cell division is coordinated with increases in mass (i.e., growth). To understand this coordination, we altered rates of division in cell clones or compartments of the Drosophila wing and measured the effects on growth. Constitute overproduction of the transcriptional regulator dE2F increased expression of the S- and M-phase initiators Cyclin E and String (Cdc25), thereby accelerating cell proliferation. Loss of dE2F or overproduction of its corepressor, RBF, retarded cell proliferation. These manipulations altered cell numbers over a 4- to 5-fold range but had little effect on clone or compartment sizes. Instead, changes in cell division rates were offset by changes in cell sizes. We infer that dE2F and RBF function specifically in cell control, and that cell cycle acceleration is insufficient to stimulate growth. Variations in dE2F activity could be used to coordinate cell division with growth.
Bibliographical noteFunding Information:
We thank Nick Dyson and Christian Lehner for gifts of flies and reagents; Dara Lehman, Michele Garfinkel, and Bre Holt for their contributions to the early stages of this work; Kristy Seidel for expert help with statistics; and Nick Dyson, Lee Hartwell, Pat O'Farrell, Christian Lehner, and Jim Roberts for comments on the manuscript. Supported by National Institutes of Health GM51186 to B. A. E., American Chemical Society PF-4301 to T. N., and National Institutes of Health GM17373 to L. A. J. Bruce Edgar is a Lucille P. Markey and Rita Allen Scholar.