Components of the protein quality control system are expressed in a strain-dependent manner in the mouse hippocampus

Inbred mouse strains are used in forward-genetic experiments, designed to uncover genes contributing to their highly distinct neurophenotypes and multiple reports of variations in mutant phenotypes due to genetic background differences in reverse-genetic approaches have been published. Information on strain-specific protein expression-phenotypes however, is limited and a comprehensive screen of an effect of strain on brain protein levels has not yet been carried out. Herein a proteomic approach, based upon two-dimensional gel electrophoresis (2-DE) coupled to mass spectrometry (MALDI-TOF/TOF) was used to show significant genetic variation in hippocampal protein levels between five mouse strains. Considering recent evidence for the importance of the intracellular protein quality control system for synaptic plasticity-related mechanism we decided to focus on the analysis of molecular chaperones and components of the ubiquitin-proteasome system. Sixty-six spots, depicting 36 proteins have been unambiguously identified by mass spectrometry. Quantification revealed strain-dependent levels of 18 spots, representing 12 individual gene products. We thus present proteome analysis of hippocampal tissues of several mouse strains as suitable tool to address fundamental questions about genetic control of protein levels and to demonstrate molecular networks of protein metabolism and chaperoning. The findings are useful for designing future studies on these cascades and interpretation of results show that data on brain protein levels cannot be simply extrapolated among different mouse strains.