Fig 6. Rbf/E2F1 regulates EcR protein levels in SCs.
(A-G) Images show distal tip of AGs from 6-day-old adult virgin males expressing nuclear GFP alone (control; this also stains the cytosol; A) or in combination with additional transgenes in SCs under the control of the esgtsF/O driver and stained with a pan-EcR antibody (red). Nuclei are stained with DAPI (blue). Red arrows mark SCs expressing EcR. Yellow arrows mark muscle cells expressing EcR as a control for EcR staining in glands that do not have EcR expression in SCs (B, C). Rbf negatively regulates EcR protein levels in SCs (C, D). Although overexpression of E2F1/DP results in an increase in EcR expression in SCs (E), which is completely suppressed by EcR knockdown (G), expression of E2F1-RNAi does not have a strong effect on EcR protein levels (F). (H) Schematic showing that for endoreplication-independent growth in mated males and for growth in virgin males, CycD and Rbf appear to control growth at least partly through the regulation of EcR levels via a mechanism that does not appear to involve E2F1. By contrast, endoreplication and associated growth are driven by CycD/Rbf/E2F1 signalling and also appear to involve increased EcR levels (new findings shown in red). Scale bars correspond to 50 μm.