Proteomic Identification of Urinary Biomarkers of Diabetic Nephropathy
- Paturi V. Rao, MD1,
- Xinfang Lu, MS2,
- Melissa Standley, BS2,
- Patrick Pattee, BS2,
- Gundupalle Neelima, MD1,
- Gudige Girisesh, MD1,
- K.V. Dakshinamurthy, MD3,
- Charles T. Roberts, Jr., PHD2 and
- Srinivasa R. Nagalla, MD2
- 1Department of Endocrinology and Metabolism, Nizam’s Institute of Medical Sciences University, Hyderabad, India
- 2Department of Pediatrics, Oregon Health and Science University, Portland, Oregon
- 3Department of Nephrology, Nizam’s Institute of Medical Sciences University, Hyderabad, India
- Address correspondence and reprint requests to Srinivasa R. Nagalla, MD, Pediatrics (NRC5), Oregon Health and Science University, 3181 S.W. Sam Jackson Park Rd., Portland, OR 97239-3098. E-mail: nagallas{at}ohsu.edu
Abstract
OBJECTIVE—Diabetic nephropathy is a serious complication of both type 1 and type 2 diabetes, and, unless arrested, leads to end-stage renal disease. Current diagnosis consists of urine assays of microalbuminuria, which have inadequate specificity and sensitivity.
RESEARCH DESIGN AND METHODS—We used proteomic analyses to identify novel biomarkers of nephropathy in urine from type 2 diabetic patients with demonstrated normo-, micro-, or macroalbuminuria. Samples were analyzed by fluorescence two-dimensional (2-D) differential in-gel electrophoresis (DIGE), and protein identification was performed by liquid chromatography-tandem mass spectrometry.
RESULTS—2-D DIGE analysis of the urinary proteome in diabetes with nephropathy identified 195 protein spots representing 62 unique proteins. These proteins belonged to several functional groups, i.e., cell development, cell organization, defense response, metabolism, and signal transduction. Comparisons between control and diabetic subjects with different stages of renal dysfunction revealed the differential expression of several proteins. Spot volume quantification identified 7 proteins that were progressively upregulated with increasing albuminuria and 4 proteins that exhibited progressive downregulation. The majority of these potential candidate biomarkers were glycoproteins.
CONCLUSIONS—These data demonstrate the ability of proteomic analyses to reveal potential biomarkers for diabetic nephropathy in urine, an important step forward in advancing accurate diagnosis and our understanding of disease mechanisms.
- A1AT, α1-antitrypsin
- AMBP, α1-microglobulin/bikunin precursor
- DIGE, differential in-gel electrophoresis
- ESRD, end-stage renal disease
- LC, liquid chromatography
- MS, mass spectrometry
- MS/MS, tandem mass spectroscopy
- RBP, retinol-binding protein
- VDBP, vitamin D–binding protein
Footnotes
-
C.T.R. and S.R.N. and Oregon Health and Science University have a significant financial interest in ProteoGenix, Inc., a company that may have a commercial interest in this research and technology. This potential conflict of interest has been reviewed and approved by the Oregon Health and Science University Conflict of Interest Research Committee.
A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C Section 1734 solely to indicate this fact.
-
- Accepted December 1, 2006.
- Received October 12, 2006.
- DIABETES CARE
