Glycosylated and non-glycosylated NT-IGFBP-4 in circulation of acute coronary syndrome patients.
Clin Biochem
; 55: 56-62, 2018 May.
Article
em En
| MEDLINE
| ID: mdl-29526675
ABSTRACT
BACKGROUND:
N-terminal and C-terminal proteolytic fragments of IGF binding protein 4 (NT-IGFBP-4 and CT-IGFBP-4) were recently shown to predict adverse cardiac events in acute coronary syndrome (ACS) patients. NT-IGFBP-4 and CT-IGFBP-4 are products of the pregnancy-associated plasma protein-A (PAPP-A)-mediated cleavage of IGFBP-4. It has been demonstrated that circulating IGFBP-4 is partially glycosylated in its N-terminal region, although the influence of this glycosylation on PAPP-A-mediated proteolysis and the ratio of glycosylated/non-glycosylated IGFBP-4 fragments in human blood remain unrevealed. The aims of this study were to investigate i) the presence of glycosylated NT-IGFBP-4 in the circulation, ii) the influence of the glycosylation of IGFBP-4 on its susceptibility to PAPP-A-mediated cleavage, and iii) the influence of glycosylation on NT-IGFBP-4 immunodetection.METHODS:
Affinity purification was used for the extraction of IGFBP-4 and NT-IGFBP-4 from plasma samples. Purified proteins were quantified by Western blotting and specific sandwich immunoassays, while molecular masses were determined using mass spectrometry.RESULTS:
Glycosylated NT-IGFBP-4 was identified in the blood of ACS patients. The fraction of glycosylated NT-IGFBP-4 in individual plasma samples was 9.8%-23.5% of the total levels of NT-IGFBP-4. PAPP-A-mediated proteolysis of glycosylated IGFBP-4 was 3-4 times less efficient (pâ¯<â¯0.001) than proteolysis of non-glycosylated protein. A sandwich fluoroimmunoassay that was designed for quantitative NT-IGFBP-4 measurements recognized both protein forms with the same efficiency.CONCLUSIONS:
Although glycosylation suppresses PAPP-A-mediated IGFBP-4 cleavage, a considerable amount of glycosylated NT-IGFBP-4 is present in blood. Glycosylation does not influence NT-IGFBP-4 measurements using a specific sandwich immunoassay.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteína 4 de Ligação a Fator de Crescimento Semelhante à Insulina
/
Síndrome Coronariana Aguda
Tipo de estudo:
Prognostic_studies
Limite:
Female
/
Humans
/
Male
Idioma:
En
Revista:
Clin Biochem
Ano de publicação:
2018
Tipo de documento:
Article