Surface redistribution of interferon gamma-receptor and its colocalization with the actin cytoskeleton.
BACKGROUND
Specific antibodies for human IFN gamma-R1 were used to examine its mobilization in Colo 205 cells.


METHODS
We report here that antibody-IFN gamma-R1 complex induced capping and actin colocalization. Pretreatment with cytochalasin D abolished this capping. To define the role of the IFN gamma-R1 in the possible interaction with actin, transfected murine fibroblasts cell line with human cDNA IFN gamma-R1 were used.


RESULTS
Only those 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 IFN gamma-R1 with substitutions in positions 270-271 of the intracellular domain redistributed both IFN gamma-R1 and actin as micropatches instead of capping. Mutation in 256-303 residues resulted in IFN gamma-R1 microaggregates but actin remained unchanged.


CONCLUSIONS
These experimental models allowed us to highlight an apparent receptor-microfilament association through the intracellular domain of IFN gamma-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.
Cruz
M
M
Unidad de Investigación Médica en Bioquímica, Instituto Mexicano del Instituto Mexicano del Seguro Social (IMSS), D.F., México.
Hernández
J M
JM
Calderón
J
J
D000199:Actins / Q000378:metabolism*; D015703:Antigens, CD / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism*; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism*; D017471:Receptors, Interferon / Q000378:metabolism*; D013499:Surface Properties; D014407:Tumor Cells, Cultured; D000096743:Interferon gamma Receptor
D000199:Actins; D015703:Antigens, CD; D007371:Interferon-gamma; D017471:Receptors, Interferon; D000096743:Interferon gamma Receptor