Prominin-1 (CD133) modulates the architecture and dynamics of microvilli

Abstract

Prominin-1 is a cell surface biomarker that allows the identification of stem and cancer stemcells from different organs. It is also expressed in several differentiated epithelial and non-epithelial cells. Irrespective of the cell type, prominin-1 is associated with plasma membraneprotrusions. Here, we investigate its impact on the architecture of membrane protrusions usingmicrovilli of Madin-Darby canine kidney cells as the main model. Our high-resolution analysisrevealed that upon the overexpression of prominin-1 the number of microvilli and clusters ofthem increased. Microvilli with branched and/or knob-like morphologies were observed andstimulated by mutations in the ganglioside-binding site of prominin-1. The altered phenotypeswere caused by the interaction of prominin-1 with phosphoinositide 3-kinase and Arp2/3 com-plex. Mutation of tyrosine 828 of prominin-1 impaired its phosphorylation and thereby inhibitedthe aforementioned interactions abolishing altered microvilli. This suggests that the interplay ofprominin-1-ganglioside membrane complexes, phosphoinositide 3-kinase and cytoskeleton com-ponents regulates microvillar architecture. Lastly, the expression of prominin-1 and its mutantsmodified the structure of filopodia emerging from fibroblast-like cells and silencing humanprominin-1 in primary hematopoietic stem cells resulted in the loss of uropod-associated micro-villi. Altogether, these findings strengthen the role of prominin-1 as an organizer of cellularprotrusions.