Identification of urinary biomarkers for type 2 diabetes using bead-based proteomic approach.

Aims: To seek urinary peptides as biomarkers distinguishing type 2 diabetes mellitus (T2DM) patients from healthy controls.
Methods: Random urine samples obtained from 28 patients with T2DM and 29 healthy individuals were analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) after purification using weak cationic-exchange magnetic beads (MB-WCX). Then the generated mass spectra of peptides were analyzed by ClinProTools2.1 bioinformatics software. Subsequently, the amino acid sequences of differently expressed peptides were identified by a nano-liquid chromatography-tandem mass spectrometry and a Sequest search found the corresponding protein name.
Results: Three differently expressed peptides and their mass to charge ratios (m/z) were found. Compared with healthy controls, the peak areas of the three differently expressed peptides were all reduced in T2DM, and the m/z were 1056.1 (m/z), 1963.5 (m/z), 2123.5 (m/z), respectively. The above-mentioned peptides were further identified as fragments of histidine triad nucleotide-binding protein 1 (HINT1), bifunctional aminoacyl-tRNA synthetase (EPRS), and clusterin precursor protein (CLU).
Conclusions: Histidine triad nucleotide-binding protein 1, bifunctional aminoacyl-tRNA synthetase, and clusterin precursor protein may serve as potential biomarkers distinguishing type 2 diabetes mellitus patients from healthy controls.
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