Phosphoinositide 3-kinase p110δ promotes lumen formation through the enhancement of apico-basal polarity and basal membrane organization

Abstract

Signalling triggered by adhesion to the extracellular matrix plays a key role in the spatial orientation of epithelial polarity and formation of lumens in glandular tissues. Phosphoinositide 3-kinase signalling in particular is known to influence the polarization process during epithelial cell morphogenesis. Here, using Madin–Darby canine kidney epithelial cells grown in 3D culture, we show that the p110δ isoform of phosphoinositide 3-kinase co-localizes with focal adhesion proteins at the basal surface of polarized cells. Pharmacological, siRNA- or kinase-dead-mediated inhibition of p110δ impair the early stages of lumen formation, resulting in inverted polarized cysts, with no laminin or type IV collagen assembly at cell/extracellular matrix contacts. p110δ also regulates the organization of focal adhesions and membrane localization of dystroglycan. Thus, we uncover a previously unrecognized role for p110δ in epithelial cells in the orientation of the apico-basal axis and lumen formation. Kidney epithelial cells grown in 3D culture form polarized cysts in which basal membranes surround a lumen. Peng et al.show that the p110δ subunit of phosphoinositide 3-kinase contributes to the formation of these structures by influencing focal adhesion at the basal membrane.