Current status of renal and urinary proteomics: ready for routine clinical application?

Renal and urinary proteomics are among the most rapidly growing subdisciplines of proteomics applied to biomedical research. The rapid growth of this field is evidenced by an increasing number of published articles related to renal and urinary proteome analyses. Using the keywords ‘proteomics’ or ‘proteome’ or ‘proteomic’ together with ‘kidney’ or ‘renal’ or ‘urine’ or ‘urinary’, >1200 articles have been found in PubMed since 1996 to July 2009. This rapid growth reflects much interest of nephrologists and renal physiologists in applying proteomics to address clinical and basic questions. Moreover, urinary proteome analysis offers opportunities for biomarker discovery not only in kidney diseases but also in other organ disorders and systemic diseases [ 1 ]. Together, these have accelerated the progress in this field during the past several years. Commonly used methods for renal and urinary proteome analyses include two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), liquid chromatography coupled to tandem MS (LC-MS/MS), surface-enhanced laser desorption/ionization (SELDI)-TOF MS, capillary electrophoresis (CE) coupled to ESI-TOF MS, and protein microarrays (details of these technologies, including their advantages and limitations, can be found in many recent reviews [ 2,3 ], whereas this article focuses only on the current status of renal and urinary proteomics and their future directions). All of these techniques have been applied to renal and urinary proteomics with the ultimate goals being as follows: (i) to better understand the biology and physiology of the kidney; (ii) to unravel the pathogenic mechanisms and/or pathophysiology of kidney diseases and related disorders; (iii) to identify diagnostic and prognostic biomarkers; and (iv) to define new therapeutic targets, drugs and other treatments. A schematic summary of methodologies and applications of renal and urinary proteomics is shown in Figure 1 . From the efforts made during the past 12 years, some achievements have been made, while further developments are also required. Examples for such achievements are provided as follows.