Surface Redistribution of Interferon γ-Receptor and its Colocalization with the Actin Cytoskeleton

Background ic antibodies for human IFNγ-R1 were used to examine its mobilization in Colo 205 cells. s ort here that antibody-IFNγ-R1 complex induced capping and actin colocalization. Pretreatment with cytochalasin D abolished this capping. To define the role of the IFNγ-R1 in the possible interaction with actin, transfected murine fibroblasts cell line with human cDNA IFNγ-R1 were used. s hose cells expressing the full receptor and cultured in suspension polarized the receptor and this colocalized with actin filaments. Nevertheless, cells truncated in their intracellular domain displayed no capping and actin remained unaltered either in suspension or in monolayer culture conditions. A mutant bearing an IFNγ-R1 with substitutions in positions 270–271 of the intracellular domain redistributed both IFNγ-R1 and actin as micropatches instead of capping. Mutation in 256–303 residues resulted in IFNγ-R1 microaggregates but actin remained unchanged. sions experimental models allowed us to highlight an apparent receptor-microfilament association through the intracellular domain of IFNγ-R1, and to specifically locate it within the intracellular region 256–303 that has been identified as relevant for ligand-receptor internalization and biological function.