MODULATION OF THE ALPHA(2) MACROGLOBULIN RECEPTOR LOW-DENSITY-LIPOPROTEIN RECEPTOR-RELATED PROTEIN BY INTERFERON-GAMMA IN HUMAN ASTROGLIAL CELLS

Alpha(2)macroglobulin receptor/low density lipoprotein receptor-relate d protein (alpha(2)Mr/LRP) is a multi-functional cell surface receptor that has been implicated in important processes, such as atherogenesi s, cellular migration, immune response and degenerative diseases. Its expression increases in human brain during Alzheimer's disease, tissue injury and neoplastic transformation. In the present paper we studied the regulation of alpha(2)Mr expression by interferon-gamma (IFN gamm a) in human astrocytoma cell lines and in fetal astrocytes. Western bl ots demonstrated an increase of the alpha(2)Mr expression after 24 h o f IFN gamma treatment. This effect paralleled the up-regulation of alp ha(2)Mr mRNA, as detected by PCR. By prolonging incubation with IFN ga mma, we observed a decrement of alpha(2)Mr in IFN gamma treated cells, both by western blot and cytometric analysis. Since in the same cells IFN gamma also up-regulates alpha(2)macroglobulin, this effect may be due to an augmented degradation of the receptor during its recycling.