Large-scale proteomics and phosphoproteomics of urinary exosomes

J Am Soc Nephrol. 2009 Feb;20(2):363-79. doi: 10.1681/ASN.2008040406. Epub 2008 Dec 3.

Abstract

Normal human urine contains large numbers of exosomes, which are 40- to 100-nm vesicles that originate as the internal vesicles in multivesicular bodies from every renal epithelial cell type facing the urinary space. Here, we used LC-MS/MS to profile the proteome of human urinary exosomes. Overall, the analysis identified 1132 proteins unambiguously, including 177 that are represented on the Online Mendelian Inheritance in Man database of disease-related genes, suggesting that exosome analysis is a potential approach to discover urinary biomarkers. We extended the proteomic analysis to phosphoproteomic profiling using neutral loss scanning, and this yielded multiple novel phosphorylation sites, including serine-811 in the thiazide-sensitive Na-Cl co-transporter, NCC. To demonstrate the potential use of exosome analysis to identify a genetic renal disease, we carried out immunoblotting of exosomes from urine samples of patients with a clinical diagnosis of Bartter syndrome type I, showing an absence of the sodium-potassium-chloride co-transporter 2, NKCC2. The proteomic data are publicly accessible at http://dir.nhlbi.nih.gov/papers/lkem/exosome/.

MeSH terms

  • Adenosine Triphosphatases / chemistry
  • Adult
  • Bartter Syndrome / urine
  • Chromatography, Liquid / methods
  • Exosomes / metabolism
  • Female
  • Humans
  • Male
  • Mass Spectrometry / methods
  • Phosphoproteins / chemistry
  • Phosphorylation
  • Proteome
  • Proteomics / methods*
  • Thiazides / chemistry
  • Urine*

Substances

  • Phosphoproteins
  • Proteome
  • Thiazides
  • Adenosine Triphosphatases