To gain insights into the impact of Cav1 on Akt-STAT5 signaling, we transfected murine alveolar epithelial MLE-12 cells with either WT cav1 or a dominant negative
(DN) cav1 expressing plasmid as described previously []. MLE-12 cells are widely used as a model for murine lung epithelial function []. Twenty-four hours after transfection, cells were infected with K. pneumonia for 1 h at 10:1 MOI and lysed in order to evaluate CFUs. As expected, decreased bacterial clearance was observed in cav1 knockdown cells as compared with WT or vector control cells (Fig. 6A). Similarly, blocking STAT5 with a chemical inhibitor WP1066 decreased bacterial clearance, although to a lesser extent than PI3K Inhibitor Library ic50 did cav1 DN transfection (Fig. 6A). Consistent with the in vivo data, the levels of ROS were also elevated in cav1 knockdown cells compared with control cells following K. pneumonia infection (Fig. 6B, p = 0.01) as quantified by the H2DCF assay and similarly increased ROS was also measured with the NBT method (Supporting Information Fig. 3). Furthermore, we determined cell survival after transfection with the cav1 DN plasmid. As assessed by the MTT cell proliferation assay, we saw significantly decreased
survival of cav1 DN transfected cells when compared with WT cells following K. pneumonia infection (Supporting Information Fig. 4). These results indicate Sclareol that more cell death occurred in the cav1 knockdown cells than in WT cells challenged by K. pneumonia. Importantly, mutation of Cav1 resulted in a similar increase in phospho-STAT5 selleck screening library while no apparent increase in total STAT5 protein was observed at 1 h (note that the tissue was obtained 24 h postinfection). Although Cav1 mutation resulted
in significantly decreased β-catenin protein expression following 1 h infection, the WT plasmid transfected cells showed a much greater increase. These results are largely consistent with the data from cav1 KO mice, indicating that Cav1 deficiency altered the expression of STAT5 and Akt. This change may contribute to the dysregulated cytokine profile, resulting in extremely high levels of IL-6 and IL-12a (Fig. 6C). To confirm the role of STAT5, a STAT5 inhibitor (WP1066) was used to pretreat the cav1 DN cells. WP1066 has been demonstrated to inhibit the phosphorylation of STAT5, thereby blocking STAT5 signaling []. Perturbation of STAT5 by WP1066 significantly reduced phospho-STAT5 and downregulated IL-6 and IL-12a expression (Fig. 6D), but did not impact the expression of β-catenin, Akt, and STAT5 protein. These data support the notion that STAT5 plays a crucial regulatory role in the activation of cytokine secretion under Cav1 deficiency. In addition, Cav1 may directly influence the function of β-catenin as Cav1 DN transfection dramatically reduced its expression levels.