Cell-division control protein 42 homolog controls microvilli formation during T cell development

Abstract

Unlike microvilli on epithelial cells, microvilli on the surface of T cells have the characteristics of filopodia, serving as the structural scaffold for clustering molecules responsible in sensing and cell migration. However, little is known how microvilli are organized during T-cell developments. Electron microscopy demonstrated that thymocytes in the double-positive stage have short and few microvilli, whereas thymocytes in single-positive (SP) stage have much longer and higher numbers of microvilli. Interestingly, the number and length of microvilli in SP thymocytes were considerably reduced by Cdc42-knockout, which resulted in reduced cell mass and downregulation of surface TCR, CCR7, and LFA-1. These features were linked to the decreased T-cell adhesion to high-endothelial venules and weakened T-cell activation following antigen recognition while not affecting the intrinsic migratory trait. Taken together, we present the first evidence that small Rho family Cdc42 is critical for organizing surface microvilli during early T-cell development.