The Expression Pattern of α6 and β4 Integrin Receptor Subunits in Cultured Chick Forebrain Neurons

Abstract

Previous data suggest that a laminin receptor is localized in the axons of chick forebrain neurons mediating the axon-growth promoting properties of laminin. Many heterodimers from the integrin family of proteins have previously been identified as laminin receptors, including the α6β4 heterodimer. We tested the role of β4, β1, and α6 integrins in laminin-induced increases in axonal growth using function blocking antibodies. Axons of neurons grown on laminin treated with β4 integrin function blocking antibodies or α6 integrin function blocking antibodies were significantly shorter compared to untreated cultures or cultures treated with a β1 integrin function-blocking antibody. These data are consistent with the hypothesis that the α6β4 heterodimer acts as the axonal laminin receptor in embryonic chick forebrain neurons and is important in axonal development and growth. To directly test whether α6 or β4 integrin was localized to axons, we transfected cultured forebrain neurons from embryonic chick with DNA constructs encoding both α6 and β4 integrin genes. Immunostaining was performed to both α6 and β4 integrins and visualized via fluorescent microscopy. Preliminary results show α6 and β4 integrin expression in axons as well as dendrites