Myc in model organisms: a view from the flyroom

Abstract

The Myc transcription factor regulates fundamental processes in a cell's life: its growth, division, and survival. Myc is conserved throughout metazoan phyla, and its identification in the fruit fly, Drosophila melanogaster has led to new insights in Myc's physiological roles. In this review, we describe recent research on the biology of Myc and its family members in Drosophila, paying particular attention to its role in the control of growth during development.

Fig. 1

dMyc controls animal growth. Flies expressing less dmyc, such as a viable dmyc hypomorph (dmyc^P0), are smaller in overall body size than wildtype flies (yw), and wing size is reduced approximately 15% (a and b). Conversely, flies with increased dmyc expression, from a Tubulin promoter-dmyc transgene (Tub > dmyc), are approximately 30% larger in overall body size than wildtype flies (b and c).

Fig. 2

dMyc regulates nucleolar size and ribosome biogenesis in vivo. Cells of the fly salivary gland overexpressing dMyc have increased ribosome content (dark dots in a and b), and larger nucleolar size (c and d) as visualized by Fibrillarin (red), and nuclear size (c and d) as seen by DAPI (blue). (Adapted from Grewal, et al. 2005 and used with permission of the authors. See Grewal et al. [34] for more details.)

Fig. 3

dMyc provides growing cells with a competitive advantage. Two models that can explain the competitive advantage of dMyc-expressing cells are: (1) that cells expressing more dMyc deprive their neighbors of growth and/or survival factors and (2) that dMyc expressing cells induce a short-range signal that kills nearby cells that express less dMyc.