Protein expression in warmed human lens epithelium cells using shotgun proteomics

In previous studies, we reported that cumulative thermal dose estimation in crystalline lens, as determined through computer simulation analysis using a supercomputer and a biothermal transport equation, showed a strong correlation with the prevalence of nuclear cataracts. In this study, we have investigated what kind of protein expressed underlying normal (35.0 °C) and warming conditions (37.5 °C) by using the shotgun Liquid chromatography with tandem mass spectrometry (LC-MS/MS)-based global proteomic approach. A total of 615 proteins were identified in the iHLEC-NY2, including 307 (49.9%) present in both lens cultured at 35.0 °C and 37.5 °C, 130 (21.1%) unique to lens cultured at 35.0 °C, and 178 (29.0%) unique to lens cultured at 37.5 °C. Furthermore, we have discussed the changes in protein expression in warmed iHLEC-NY2 cells using Gene Ontology analysis and a label-free semiquantitative method based on spectral counting. Shotgun proteomic analysis revealed that warming decreased the expression of actin, alpha cardiac muscle 1, actin-related protein 2, putative tubulin-like protein alpha-4B, ubiquitin carboxyl-terminal hydrolase 17-like protein 1, ubiquitin-ribosomal protein eL40 fusion protein, ribosome biogenesis protein BMS1 homolog, histone H2B type 1-M, and histone H2A.J. in iHLEC-NY2. Thus, the decrease in specific protein levels of actin, tubulin, ubiquitin, ribosomes, and histones may be related to cataract development under warming conditions. This study may serve as a valuable indicator for elucidating the relationship between temperature and onset of nuclear cataracts.