Vitamin D differentially regulates Salmonella-induced intestine epithelial autophagy and interleukin-1β expression

Figure 6 Involvement of vitamin D receptor in the enhanced effect of 1,25D3 on autophagy expression in Salmonella-infected Caco-2 cells. Caco-2 cells were transfected with control siRNA and vitamin D receptor (VDR) siRNA (siVDR: siRNA to VDR) for 48 h. The transfected cells were left uninfected (CON) or infected by wild-type S. typhimurium strain SL1344 (SL) in the absence or presence of 1,25D3 (D3). Immunoblots were performed on whole cell lysates with antibody to detect autophagy LC3-I/II protein expression. The results shown are representative of three separate experiments. GAPDH was detected for normalization of cytosolic protein. Representative immunoblots (A) and densitometric quantification of immunoreactive bands are shown. The relative band intensities of LC3-II in Caco-2 cells are quantified as fold-increases compared with the control cells (B). The cells were fixed, permeabilized and stained with anti-LC3 (red), and LC3 puncta formation was detected by a confocal microscope. Representative images of LC3 punctae are depicted (C). Scale bar = 10 μm. The percentage of cells showing accumulation of LC3 punctae is reported (D). Each value represents the mean ± SEM of three independent experiments. ^aP < 0.05.