N-redundant genes in the human urine exosome, and 9,706 non-redundant genes in human plasma. The genes in human urine and the urine exosome were pooled, which resulted in 6,084 non-redundant genes in normal human urine and the urinary exosome. The 1,233 human orthologs, which account for 1,278 human orthologous genes, were compared at the gene level with human kidney gene expression, the pooled human urine and urinary exosome proteome, and the human plasma proteome (Figure 2). Of the 1,278 genes, 982 were expressed in the kidney. These genes corresponded to 981 human orthologs. The 981 humanFigure 2. The human orthologs Title Loaded From File identified from the rat proteins in perfusion-driven urine were compared with human kidney expression data (Kidney expr), the pooled human urine and urinary exosome proteome (UriANDexo), and the human plasma proteome (Plasma). The protein identifiers were standardized using the Ensembl Gene ID(s). The comparison was performed at the gene level. doi:10.1371/journal.pone.0066911.gorthologs with gene expression in the kidney were considered to be potential human kidney proteins in urine (Table S2). Of the 981 human orthologs, 613 had been identified both in the urine (including urinary exosome) proteome and the plasma proteome; 240 had only been identified in the urine (including urinary exosome) proteome but not in the plasma proteome; 71 had only been identified in the plasma proteome but not in the urine (including urinary exosome) proteome; and 57 had not been identified in either the urine (including urinary exosome) proteome or the plasma proteome (Figure 2). There are a total of 128 human orthologs (57 plus 71) that were expressed in the kidney but were not Title Loaded From File present in normal urine (including the urinary exosome). They are potential biomarkers with zero background in pathological conditions. There are a total of 297 human orthologs (57 plus 240) that were expressed in the kidney but were not present in the plasma. They are likely not influenced by other normal organs, including the plasma, and therefore have the potential to specifically reflect functional changes in the kidney. The 57 human orthologs could be sensitive markers because they were not present in normal urine or the urinary exosome and were not influenced by other normal organs, including plasma.2.4 Comparing the ranking of human kidney origin proteins in the normal and perfusion-driven urine. Alarge-scale dataset of the human normal urine proteome has been provided by another team at our institution (data not published). They used the same TripleTOF 5600 system and the same MASCOT search engine as in this study. The Exponentially Modified Protein Abundance Index (emPAI), which offers approximate, label-free, relative quantitation of the proteins in a mixture based on protein coverage by peptide matches, has been incorporated into the MASCOT search engine [29]. Therefore, each identified urine protein had an emPAI value, which can be used to approximately estimate the absolute protein contents in urine. Of the 981 human orthologs that were considered to be potential human kidney origin proteins in urine, 775 wereIdentifying Kidney Origin Proteins in Urineidentified in this normal human urine dataset. The emPAI values of these human orthologs were extracted from the normal human urine proteome, and these proteins were sorted from most to least abundant in the normal human urine. Proteins not identified in the human urine were at the end. The order of thes.N-redundant genes in the human urine exosome, and 9,706 non-redundant genes in human plasma. The genes in human urine and the urine exosome were pooled, which resulted in 6,084 non-redundant genes in normal human urine and the urinary exosome. The 1,233 human orthologs, which account for 1,278 human orthologous genes, were compared at the gene level with human kidney gene expression, the pooled human urine and urinary exosome proteome, and the human plasma proteome (Figure 2). Of the 1,278 genes, 982 were expressed in the kidney. These genes corresponded to 981 human orthologs. The 981 humanFigure 2. The human orthologs identified from the rat proteins in perfusion-driven urine were compared with human kidney expression data (Kidney expr), the pooled human urine and urinary exosome proteome (UriANDexo), and the human plasma proteome (Plasma). The protein identifiers were standardized using the Ensembl Gene ID(s). The comparison was performed at the gene level. doi:10.1371/journal.pone.0066911.gorthologs with gene expression in the kidney were considered to be potential human kidney proteins in urine (Table S2). Of the 981 human orthologs, 613 had been identified both in the urine (including urinary exosome) proteome and the plasma proteome; 240 had only been identified in the urine (including urinary exosome) proteome but not in the plasma proteome; 71 had only been identified in the plasma proteome but not in the urine (including urinary exosome) proteome; and 57 had not been identified in either the urine (including urinary exosome) proteome or the plasma proteome (Figure 2). There are a total of 128 human orthologs (57 plus 71) that were expressed in the kidney but were not present in normal urine (including the urinary exosome). They are potential biomarkers with zero background in pathological conditions. There are a total of 297 human orthologs (57 plus 240) that were expressed in the kidney but were not present in the plasma. They are likely not influenced by other normal organs, including the plasma, and therefore have the potential to specifically reflect functional changes in the kidney. The 57 human orthologs could be sensitive markers because they were not present in normal urine or the urinary exosome and were not influenced by other normal organs, including plasma.2.4 Comparing the ranking of human kidney origin proteins in the normal and perfusion-driven urine. Alarge-scale dataset of the human normal urine proteome has been provided by another team at our institution (data not published). They used the same TripleTOF 5600 system and the same MASCOT search engine as in this study. The Exponentially Modified Protein Abundance Index (emPAI), which offers approximate, label-free, relative quantitation of the proteins in a mixture based on protein coverage by peptide matches, has been incorporated into the MASCOT search engine [29]. Therefore, each identified urine protein had an emPAI value, which can be used to approximately estimate the absolute protein contents in urine. Of the 981 human orthologs that were considered to be potential human kidney origin proteins in urine, 775 wereIdentifying Kidney Origin Proteins in Urineidentified in this normal human urine dataset. The emPAI values of these human orthologs were extracted from the normal human urine proteome, and these proteins were sorted from most to least abundant in the normal human urine. Proteins not identified in the human urine were at the end. The order of thes.
