The hepatic interleukin-6 receptor. Down-regulation of the interleukin-6 binding subunit (gp80) by its ligand.
FEBS Lett
; 306(2-3): 219-22, 1992 Jul 20.
Article
em En
| MEDLINE
| ID: mdl-1321736
ABSTRACT
Interleukin-6 (IL6) exerts its action via a cell surface receptor composed of an 80 kDa IL6-binding protein (gp80) and a 130 kDa polypeptide involved in signal transduction (gp130). We studied the role of gp80 in binding, internalization and down-regulation of the hepatic IL6-receptor (IL6R) by its ligand in human hepatoma cells (HepG2). Comparison of transfected HepG2 cells overexpressing gp80 with parental cells indicate that gp80 is responsible for low affinity binding (Kd = 500 pM) of IL6. Furthermore, gp80 is rate-limiting in internalization and degradation of IL6. Internalization resulted in a rapid down-regulation (t1/2 approximately 15-30 min) of IL6-binding sites at the cell surface. More than 80% of the internalized [125I]rhIL6 was degraded. The reappearance of IL6-binding sites at the cell surface required greater than 8 h and was sensitive to cycloheximide, suggesting that gp80 is not recycled after internalization. The down-regulation of the hepatic IL6R by its ligand might play an important role as a protection against overstimulation.
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Base de dados:
MEDLINE
Assunto principal:
Receptores Imunológicos
/
Regulação para Baixo
/
Interleucina-6
/
Fígado
Limite:
Humans
Idioma:
En
Ano de publicação:
1992
Tipo de documento:
Article