April 2009
Volume 50, Issue 13
ARVO Annual Meeting Abstract  |   April 2009
Characterization of Vitreous Insulin-Like Growth Factor Binding Proteins
Author Affiliations & Notes
  • C. Guidry
    Ophthalmology, University of Alabama School of Medicine, Birmingham, Alabama
  • J. L. King
    Ophthalmology, University of Alabama School of Medicine, Birmingham, Alabama
  • Footnotes
    Commercial Relationships  C. Guidry, None; J.L. King, None.
  • Footnotes
    Support  NIH EY013258, International Retinal Research Foundation, Research to Prevent Blindness
Investigative Ophthalmology & Visual Science April 2009, Vol.50, 5359. doi:
  • Views
  • Share
  • Tools
    • Alerts
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      C. Guidry, J. L. King; Characterization of Vitreous Insulin-Like Growth Factor Binding Proteins. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5359.

      Download citation file:

      © ARVO (1962-2015); The Authors (2016-present)

  • Supplements

Purpose: : Previous studies from this laboratory revealed that insulin-like growth factor (IGF) biological activities increase in Proliferative Diabetic Retinopathy and that this activity is normally attenuated by vitreous insulin-like growth factor binding proteins (IGFBPs). The intent of this study was to identify and characterize the IGFBP species involved.

Methods: : Human and porcine vitreous, human and porcine plasma, recombinant IGFBP-2 and recombinant IGFBP-3 were separated by one- and two-dimensional gel electrophoresis. The presence of functional IGFBPs was evaluated by western ligand blotting using biotinylated IGF-II. Individual IGFBPs were identified in western blots using IGFBP-specific monoclonal antibodies. Protein glycosylation was evaluated by digestion with the lyase Endoglycosidase F.

Results: : Western ligand blots of human and porcine vitreous detected two major proteins at ~35kDa and ~30kDa. Bands matching these sizes were also detected in human and porcine plasma. The larger band migrated to a position similar to that of recombinant IGFBP-2, but neither matched recombinant IGFBP-3 at ~45kDa. Western blots of human and porcine vitreous and plasma confirmed the identity of the ~35kDa band as IGFBP-2 and the ~30kDa band as a fragment of IGFBP-3. Western and western ligand blots of vitreous and plasma proteins separated by two-dimensional gel electrophoresis revealed that the IGFBP-3 fragments in vitreous and plasma have virtually identical profiles. Lyase digestion revealed that the ~30kDa IGFBP-3 fragment is a glycoprotein with a peptide core of ~25kDa.

Conclusions: : Normal human and porcine vitreous contain two major IGFBPs that are identified as IGFBP-2 and a previously reported ~30kDa fragment of IGFBP-3. Both vitreous IGFBPs retain biological activity and IGFBP-3 has one or more glycosylation sites with a protein core of ~25kDa. Systematic comparisons between vitreous and plasma indicate that the vitreous IGFBP-3 is similar and perhaps identical to a previously described IGFBP-3 fragment in plasma with reduced growth factor affinities.

Keywords: diabetic retinopathy • vitreous • growth factors/growth factor receptors 

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.