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Effects of cytokines on synthesis and function of the hepatic asialoglycoprotein receptor
Author(s) -
Treichel Ulrich,
Paietta Elisabeth,
Poralla Thomas,
Meyer zum Büschenfelde KarlHermann,
Stockert Richard J.
Publication year - 1994
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041580319
Subject(s) - asialoglycoprotein receptor , function (biology) , receptor , microbiology and biotechnology , chemistry , biology , biochemistry , in vitro , hepatocyte
In this study we have investigated whether cytokines, critical mediators of the immune response, might have a direct effect on the expression and/or function of the human hepatic asialoglycoprotein receptor (ASGPR). Binding and uptake of asialoglycoproteins by the human hepatoma cell line, HepG2, and by freshly isolated rat hepatocytes were inhibited by 50% after 3–6 hours and completely abolished following a 24 hour exposure to tumor necrosis factor (TNF) α, interferon (INF) α or γ, or interleukin‐2 (IL‐2). The loss of ASGPR binding activity mediated by IL‐2 was reversible up to 4 hours of exposure and accompanied by the selective phosphorylatior, of the cell‐surface receptor. Steady‐state levels of total cellular ASGPR protein remained unchanged over the first 6 hours of IL‐2 incubation but declined in a dose dependent manner thereafter. This down regulation of ASGPR expression was due to reduced synthesis as a result of reduced receptor transcript levels. No loss was detected, however, of cell surface‐associated receptor protein even after 24 hours of IL‐2 incubation, suggesting that cytokine induced phosphorvlation constitutes a mechanism to regulate receptor activity. © 1994 Wiley‐Liss, Inc.