Quantitative Analysis of the Intra- and Inter-Individual Variability of the Normal Urinary Proteome

• Published in: Journal of proteome research Vol. 10; no. 2; pp. 637 - 645
• Main Authors: Nagaraj, Nagarjuna, Mann, Matthias
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 04-02-2011
• Subjects: Chromatography, Liquid; Computational Biology; Humans; Peptide Fragments - analysis; Peptide Fragments - metabolism; Proteins - analysis; Proteins - metabolism; Proteinuria - urine; Proteome - analysis; Proteome - metabolism; Reproducibility of Results; Statistics, Nonparametric; Tandem Mass Spectrometry; Urine - chemistry; Urinary proteome; technical and biological variation; absolute quantitation; label-free quantification
• ISSN: 1535-3893; 1535-3907
• DOI: 10.1021/pr100835s

Urine is a readily and noninvasively obtainable body fluid. Mass spectrometry (MS)-based proteomics has shown that urine contains thousands of proteins. Urine is a potential source of biomarkers for diseases of proximal and distal tissues but it is thought to be more variable than the more commonly used plasma. By LC−MS/MS analysis on an LTQ-Orbitrap without prefractionation we characterized the urinary proteome of seven normal human donors over three consecutive days. Label-free quantification of triplicate single runs covered the urinary proteome to a depth of more than 600 proteins. The median coefficient of variation (cv) of technical replicates was 0.18. Interday variability was markedly higher with a cv of 0.48 and the overall variation of the urinary proteome between individuals was 0.66. Thus technical variability in our data was 7.5%, whereas intrapersonal variability contributed 45.5% and interpersonal variability contributed 47.1% to total variability. Determination of the normal fluctuation of individual urinary proteins should be useful in establishing significance thresholds in biomarker studies. Our data also allowed definition of a common and abundant set of 500 proteins that were readily detectable in all studied individuals. This core urinary proteome has a high proportion of secreted, membrane, and relatively high-molecular weight proteins.