PI3K & Rbsn-5 in Drosophila Figure 5. Subcellular localization defects of b-integrin and Fas III in PI3K (III)-knockdown pupal wings. Confocal immunodetection showing XY and XZ sections in the plane of pupal wings at 30 h APF. Double-headed arrows indicate the regions where the dsRNA for dVps15 was expressed by dpp-Gal4 driver. b-integrin [b-int] (red) was localized to the basal plasma membrane in the wild-type prospective intervein regions but was only rarely localized to the basal plasma membrane while it accumulated in the cytoplasm in dVps15-knockdown cells. b-integrin was not degraded in the knockdown vein region neither was it observed in the wild-type vein region. By contrast, Fas III (red) was localized only to the SJ (indicated by brackets) in the wild-type while in the dVps15-knockdown cells it was accumulated to both the SJ and BLPM regions. The scale bars represent 10 mm. doi:10.1371/journal.pone.0007306.g005 down, b-integrin remained dispersed in the cytoplasm with small intracellular vesicles, and it failed to form basal junctions in the intervein region, even at 30 h APF (Fig. 5). This suggests that PI3K (III) might contribute either to the translocation of b-integrin to the basal membrane, or to the suppression of endocytosis of b- integrin, or both. The b-integrin disappeared in prospective vein cells by 30 h APF since they are devoid of basal junctions (Fig. 5). Interestingly, b-integrin clearly accumulated at the intracellular vesicles in the cytoplasm, even in the prospective vein region (Fig. 5), suggesting that its degradation of might be compromised by the knockdown of dVps15. Fas III is present at high levels at the septate junction (SJ), lateral cell junction, and at low levels in the remaining lateral membrane domain [39]. Fas III is first localized to both the SJ and more basal regions where Discs Large (Dlg), another component of the SJ, is absent. By 50 h APF, most of the adhesion structures in the lateral plasma membrane apparently disappear [38], probably because PLoS ONE | www.plosone.org 6 October 2009 | Volume 4 | Issue 10 | e7306