Expanding the proteome two-dimensional gel electrophoresis reference map of human renal cortex by peptide mass fingerprinting.

Proteomics methodologies hold great promise in basic renal research and clinical nephrology. The classical approach for proteomic analysis couples two-dimensional gel electrophoresis (2-DE) with protein identification by mass spectrometry, to produce more global information regarding normal protein expression and alterations in different physiological and pathological states. In this report we have expanded the identification of proteins in the renal cortex, improving the previously published map to facilitate the study of different diseases affecting the human kidney. About 250 spots were analyzed by peptide mass fingerprinting, 89 proteins and 74 isoforms for some of them were identified and implemented in the normal human renal cortex 2-DE reference map. This more comprehensive view of the proteome of the human renal cortex could be of invaluable help to the differential proteomic display of urological diseases.

Expression of heat shock protein 27 in human renal cell carcinoma.

Heat shock protein 27 (HSP27, Swiss-Prot accession number P04792) is a component of the large and heterogeneous group of chaperone proteins, and its main functions are inhibition of apoptosis and prevention of aggregation of actin intermediate filament. Modified expression of HSP27 has been described in several cancers including testis, breast, and ovaric cancer. In the present work, 18 renal cell carcinoma (RCC) tissues and homologous normal kidney tissues have been investigated for HSP27 expression by combination of two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) separation and Western blotting immunodetection. The results showed significant differences either in expression and in HSP27 isoform numbers in RCC compared to normal kidney. The average number of isoforms was 21 in RCC and 15 in normal tissues with 4.5-5.9 pI range and 18-29 kDa M(r) range. The overexpression was also observed by immunohistochemistry on tissue sections. Only two of RCC samples showed less isoforms than homologous normal samples. Two isoforms were not detected using anti-Ser82 phosphorylated HSP27 antibody, neither in normal nor in RCC samples. Five of all the immunodetected isoforms were confirmed by mass spectrometry as HSP27, but no evidence of post-translational modifications was pointed out. The numerous isoforms observed in RCC are not consistent with data reported in the literature so far, and they might be due to different post-translational modifications such as phosphorylation and S-thiolation. Since activation of HSP27 seems to be involved in tumor proliferation and drug resistance, it would be crucial to correlate the severity of disease with the different isoforms from RCC samples to generate diagnostic and prognostic markers.