PI3K-C2α is not required for PtdIns(3)P enrichment or the localization of SARA in the endosomes but for TGFβ-induced increase in PtdIns(3,4)P2 in lamellipodia.
A, GFP-FYVESARA fluorescence. The HUVECs were co-transfected with the GFP-FYVESARA expression vector and either C2α#1 siRNAs or sc-siRNA and stimulated with TGFβ1 (5 ng/ml) for 30 min or left untreated. Nuclei were stained by DAPI. Left panel, representative confocal images. Right panel, quantified data of the numbers of GFP-FYVE fluorescence-positive vesicles per cell that were obtained from 48 cells per group. B, anti-SARA immunofluorescent staining. The HUVECs were transfected with either C2α-siRNAs or sc-siRNA and stimulated with TGFβ1 (5 ng/ml) for 30 min or left untreated. Nuclei were stained by DAPI. Left panel, representative confocal images. Right panel, quantified data of anti-SARA-positive vesicles per cell that were obtained from 48 cells per group. Scale bar, 20 μm. C, GFP-PHTAPP1 fluorescence. The HUVECs were co-transfected with the GFP-PHTAPP1 expression vector and either C2α-siRNAs or sc-siRNA and stimulated with TGFβ1 (5 ng/ml) for 30 min or left untreated. Nuclei were stained by DAPI. Confocal images at 2, 5, and 10 min after the additions of TGFβ1 or vehicle are shown.