Polarised expression pattern of focal contact proteins in highly motile antigen presenting dendritic cells

Dendritic cells are professional antigen presenting cells that capture anti gens and migrate to lymphoid tissues to elicit specific T cell responses. H ere we used an in vitro differentiation system for generating highly motile dendritic cells from chicken bone marrow progenitors by employing the cond itional v-Rel estrogen receptor (ER) fusion protein v-RelER, Molecular mech anisms of dendritic cell motility were investigated. Differentiation of v-r elER progenitors into dendritic cells is associated with a reduction in cel l-cell and cell-extracellular matrix interactions as cells acquire motility , We demonstrate that v-relER progenitors and dendritic cells express sever al adhesion receptors and components of adhesion complexes. Differentiation of v-relER cells was accompanied by downregulation of focal adhesion kinas e (FAK), a key molecule of adhesion complexes, but ectopic FAK expression d id not affect cell adhesion and motility, Interestingly, v-relER dendritic cells exhibit a polarised expression pattern of actin and vimentin, with ac tin being highly concentrated at the leading edge of the cells where lamell ipodia are formed. FAK, paxillin and tyrosine phosphorylated proteins are f ound at both poles of the cell and colocalise with actin at the leading edg e, while surface pl integrin is confined to the uropod at the rear. CD34(+) stem cell-derived human dendritic cells also exhibited an elongated bipola r morphology, mode of migration and a polarised pattern of actin-vimentin e xpression similar to v-relER dendritic cells.