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Characterization of urinary insulin-like growth factor binding proteins
Y Hasegawa1, P Cohen, P Yorgin
1Division of Pediatric Endocrinology and Metabolism, Tokyo Metropolitan Kiyose Children's Hospital, Japan.
The Journal of Clinical Endocrinology and Metabolism
|April 1, 1992
Summary
Insulin-like growth factor binding proteins (IGFBPs) are found in human urine, with distinct patterns in normal individuals and those with renal disease. These urinary IGFBPs may serve as potential biomarkers for kidney conditions.
Area of Science:
- Endocrinology
- Nephrology
- Biochemistry
Background:
- Insulin-like growth factors (IGFs) are crucial mitogens found in body fluids.
- IGFs typically bind to IGF binding proteins (IGFBPs) in circulation.
- The presence and role of IGFBPs in human urine were previously unclear.
Purpose of the Study:
- To investigate the presence and characteristics of IGFBPs in human urine.
- To compare urinary IGFBP profiles in healthy individuals and patients with renal diseases.
- To assess the potential of urinary IGFBPs as clinical markers for renal conditions.
Main Methods:
- Western ligand blotting of concentrated, dialyzed urine to detect IGF binding activity.
- Deglycosylation using endoglycosidase F to analyze protein structure.
- Immunoprecipitation with specific antibodies (alpha HEC1) for protein identification.
- Comparison of IGFBP profiles in serum and urine from normal individuals and patients with renal disease.
Main Results:
- Two major IGFBP bands were identified in normal urine: hIGFBP-3 (40-44 kDa) and hIGFBP-2 (31 kDa).
- The ratio of hIGFBP-2 to hIGFBP-3 was reversed in urine compared to serum, with hIGFBP-2 being predominant in urine.
- The 150 kDa form of hIGFBP-3 was absent in normal urine.
- Altered urinary IGFBP patterns were observed in patients with renal disease, including elevated hIGFBP-3 in glomerular disease and increased hIGFBP-1 in renal failure.
Conclusions:
- Insulin-like growth factor binding proteins (IGFBPs) are present in the urine of both normal and diseased individuals.
- Urinary IGFBP profiles differ between normal individuals and patients with renal disease, suggesting potential as biomarkers.
- The presence of IGFBPs in urine may impact IGF measurements and warrants further investigation into their origin and clinical significance in renal diseases.