Glucose does not influence the insulin-like growth factor (IGF) binding to carrier proteins (IGFBPs): Analysis of rat and human serum by western ligand blotting

S. Cianfarani, V. J. Frost, M. O. Savage, J. M P Holly

Research output: Contribution to journalArticle

Abstract

The insulin-like growth factors (IGFs) circulate bound to specific proteins (termed IGFBP-1 through IGFBP-6) that modulate IGF bioactivity in tissues. The aim of this study was to analyse the effects of glucose on IGF binding to IGFBPs in rat and human serum by means of western ligand blotting. Serum samples were incubated with increasing concentrations of glucose (0 to 50 mmol/l), and EDTA (25 mmol/l) was added to inhibit protease activity. To analyse the effect of glucose on protection of IGFBPs from protease activity, serum from pregnant women (reported to be very rich in proteolytic activity against IGFBPs) was added to rat serum previously incubated with glucose. Glucose did not affect the125I-IGF binding to rat and human serum IGFBPs. The intensity of IGFBP-3 bands decreased considerably during the incubation. This appeared to be due to endogenous protease activity, since the decrease was blocked by addition of EDTA. The incubationi of rat serum with pregnant human serum produced a marked attenuation of IGFBP-3 and disappearance of IGFBP-4 bands. In conclusion, our study shows that glucose does not influence the IGF binding to IGFBP-3 either in rat or in human serum, confirms the presence of endogenous proteolytic activity in normal non-pregnant serum, and demonstrates that glucose has no protective action against protease activity.

Original languageEnglish
Pages (from-to)699-701
Number of pages3
JournalExperientia
Volume49
Issue number8
DOIs
Publication statusPublished - Aug 1993

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Keywords

  • diabetes
  • glucose
  • IGF
  • IGFBP
  • proteases

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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