Differential proteomic analysis of the brain synaptic plasma membrane proteins from DHA‐deficient and adequate mice using 16O/18O labeling

Abstract

Polyunsaturated fatty acids, especially docosahexenoic acid (DHA, 22:6n‐3) plays an important role in normal brain development in mammals. DHA promotes hippocampal neurite growth and synaptogenesis while DHA‐ deficiency causes impairments in hippocampus‐dependent learning and memory. In this study, we compared the synaptic plasma membrane (SPM) proteins obtained from DHA‐adequate and deficient mice using 16O/18O labeling to provide insights into the role of DHA in synaptic protein expression and function. Synaptosomal preparations from DHA‐deficient and adequate mice cortex were subjected to osmotic shock to obtain SPM. The SPM fraction was analysed by SDS‐PAGE coupled to nanoLC‐MS/MS. For quantification, we differentially labeled the peptide samples from DHA‐adequate and deficient mice using O16/O18 labeling technique. The heavy to light ratios (18O/16O) were calculated using Mascot Distiller. This strategy allowed us to detect more than 400 proteins from the SPM fraction including various receptors, kinases and transporter proteins. The 18O/16O ratios revealed differential expression of several pre‐ and postsynaptic proteins involved in neurotransmission. Some of these proteins were validated by western blot analysis. Altered levels of synaptic proteins important for synaptic transmission suggest a role of DHA in proper brain development and function.National Institutes of Health, MD.