Proteomic expression clustering of mouse liver developmental stages

Abstract

Liver starts to differentiate as early as in gestation day 8 in mouse and continues to develop till adulthood. It undergoes functional transition from acting as a hematopoietic center in embryo to being the meta-bolic center in adult. During this process, it accompanies with alteration in the protein expressions in liver. As such, it is important to delineate the protein expression profiling during mouse liver development from embryo to adult, aiming to provide information for the study of liver functions. In this study, livers were extracted from prenatal, neonatal, and postnatal livers: embryonic day 13.5 and 16.5 (E13.5 and E16.5), newborn liver, and livers from 3 week-old and adult mice. The patterns and expressions of proteins (spots) were visualized using 2-dimensional gel electrophoresis, accompanied by spot analysis using PDQuest software. Among the 804 spots identified, 396 spots demonstrated statistical significance among different stages by one-way ANOVA analysis (P < 0.01). Based on the distinct spot expression, spots were further segregated into five clusters by unsupervised learning algorithm. By linear regression analysis, we also identified protein species that are associated with developmental changes at pre-, neo, and post-natal livers. About 10–15 spots from each cluster were identified using the MALDI-ToF/MS or MS/MS approach. Information derived from the protein spot identification results advance the knowledge in liver development.