Proteolysis of insulin-like growth factors (IGF) and IGF binding proteins by cathepsin D.
Endocrinology
; 138(9): 3797-803, 1997 Sep.
Article
em En
| MEDLINE
| ID: mdl-9275067
ABSTRACT
Various proteinases have been postulated to function in limited proteolysis of insulin-like growth factor binding proteins (IGFBPs) contributing to the regulation of IGF bioavailability. In this study, we report on the in vitro degradation of IGFs and IGFBPs by the purified acidic aspartylprotease cathepsin D that has been shown to proteolyze IGFBP-3. Recombinant human [125I] IGFBP-1 to -5 were processed by cathepsin D to fragments of defined sizes in a concentration dependent manner, whereas IGFBP-6 was not degraded. Ligand blotting revealed that none of the IGFBP-1 or -3 fragments formed by cathepsin D retain their ability to bind IGF. By N-terminal sequence analysis of nonglycosylated IGFBP-3 fragments produced by cathepsin D, at least four different cleavage sites were identified. Some of these cleavage sites were identical or differed by one amino acid from sites used by other IGFBP proteases described. The IGFBP-3 and -4 cleavage sites produced by cathepsin D are located in the nonconserved central region. IGF-I and -II, but not the unrelated platelet-derived growth factor BB, were degraded by cathepsin D in a time and concentration-dependent manner. We speculate that the major functional site of cathepsin D is intracellular and may be involved 1) in the selected clearance either of IGFBP or IGFs via different endocytic pathways or 2) in the general lysosomal inactivation of the IGF system.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fator de Crescimento Insulin-Like I
/
Fator de Crescimento Insulin-Like II
/
Catepsina D
/
Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina
Tipo de estudo:
Prognostic_studies
Limite:
Animals
/
Humans
Idioma:
En
Revista:
Endocrinology
Ano de publicação:
1997
Tipo de documento:
Article
País de afiliação:
Alemanha