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. 2010 Apr 9;5(4):e10077.
doi: 10.1371/journal.pone.0010077.

Mal/SRF is dispensable for cell proliferation in Drosophila

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Mal/SRF is dispensable for cell proliferation in Drosophila

Barry J Thompson. PLoS One. .

Abstract

The Mal/SRF transcription factor is regulated by the level of G-actin in cells and has important roles in cell migration and other actin-dependent processes in Drosophila. A recent report suggests that Mal/SRF and an upstream regulator, Pico, are required for cell proliferation and tissue growth in Drosophila. I find otherwise. Mutation of Mal or SRF does not affect cell proliferation in the fly wing. Furthermore, I cannot reproduce the reported effects of Pico RNAi or Pico overexpression on body size. Nevertheless, I can confirm that overexpression of Pico or Mal causes tissue overgrowth specifically in the fly wing--where SRF is most highly expressed. My results indicate that Mal/SRF can promote tissue growth when abnormally active, but is not normally required for tissue growth during development.

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Conflict of interest statement

Competing Interests: The author has declared that no competing interests exist.

Figures

Figure 1
Figure 1. Mal/SRF is not required for cell proliferation in the fly wing or eye.
(A) Clones of control cells (absence of GFP) and their twin spots (bright GFP) are roughly the same size, indicating normal rates of proliferation. (B) Clones of malS9 mutant cells (absence of GFP) and their twin spots (bright GFP) are roughly the same size, indicating normal rates of proliferation. (C) Clones of bs14 mutant cells (absence of GFP) and their twin spots (bright GFP) are roughly the same size, indicating normal rates of proliferation. (D) A control wing containing wild-type cells in the posterior compartment. Genotype is indicated. (E) A wing containing malS9 mutant cells in the posterior compartment. Genotype is indicated. (F) A wing containing bs14 mutant cells in the posterior compartment. Genotype is indicated. (G) A pupal wing expressing E-cad GFP. (H) A close up of a wing vein from (G). (I) A wild-type fly eye. (J) A malS9 mutant fly eye, genotype indicated, is normally sized.
Figure 2
Figure 2. Overexpression of Mal causes overgrowth in the wing, but not the eye.
(A) A control en.Gal4 wing. (B) Overexpression of Mal in the posterior compartment with en.Gal4 causes overgrowth. (C) A control ms1096.Gal4 wing. (D) Overexpression of Mal in the whole wing with ms1096.Gal4 causes overgrowth. (E) A control ey.Gal4 GMR.Gal4 eye. (F) Overexpression of Mal in the eye with ey.Gal4 GMR.Gal4 does not affect eye size.
Figure 3
Figure 3. Pico is not required to regulate body size or eye size.
(A) A control act.Gal4 fly. (B) A control arm.Gal4 fly. (C) Ubiquitous overexpression of Pico with act.Gal4 does not change body size, but does affect wing morphology. (D) Ubiquitous overexpression of Pico with arm.Gal4 does not change body size, but does affect wing morphology. (E) Ubiquitous RNAi knockdown of Pico with act.Gal4 does not change body size, but does affect wing morphology. (F) Ubiquitous RNAi knockdown of Pico with arm.Gal4 does not change body size, but does affect wing morphology. (G) RNAi knockdown of Pico in the eye with ey.flp act>STOP>Gal4 produces normally sized eyes. (H) Overexpression of Pico in the eye with ey.flp act>STOP>Gal4 produces normally sized eyes.
Figure 4
Figure 4. Pico is required for morphogenesis in the wing and can drive overgrowth when overexpressed.
(A) A control ms1096.Gal4 wing. (B) Overexpression of Pico with ms1096.Gal4 drives overgrowth, similar to overexpression of Mal. (C,D) RNAi knockdown of Pico with ms1096.Gal4 causes blisters (C) or crumpling (D) but does not strongly reduce wing size.

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