Effects of Docosahexaenoic Acid on Mouse Brain Synaptic Plasma Membrane Proteome Analyzed by Mass Spectrometry and ¹⁶O/¹⁸O Labeling

Docosahexenoic acid (DHA, 22:6n-3) plays an important role in development of proper brain function in mammals. We have previously reported that DHA promotes synaptogenesis and synaptic function in hippocampal neurons while DHA-depletion in the brain due to n-3 fatty acid deficiency produces opposite effects. To gain insight into underlying molecular mechanisms, we investigated whether the brain DHA status affects the synaptic plasma membrane (SPM) proteome by using nanoLC–ESI–MS/MS and ¹⁶O/¹⁸O labeling. The DHA level in mouse brains was lowered by dietary depletion of n-3 fatty acids, and SPM was prepared by differential centrifugation followed by osmotic shock. SPM proteins from DHA-adequate and depleted brains were analyzed by nanoLC–ESI–MS/MS after SDS-PAGE, in-gel digestion, and differential O¹⁸/O¹⁶ labeling. This strategy allowed comparative quantitation of more than 200 distinct membrane or membrane-associated proteins from DHA-adequate or depleted brains. We found that 18 pre- and postsynaptic proteins that are relevant to synaptic physiology were significantly down-regulated in DHA-depleted mouse brains. The protein network analysis suggests involvement of CREB and caspase-3 pathways in the DHA-dependent modulation of synaptic proteome. Reduction of specific synaptic proteins due to brain DHA-depletion may be an important mechanism for the suboptimal brain function associated with n-3 fatty acid deficiency

Analysis of outer membrane vesicle associated proteins isolated from the plant pathogenic bacterium pv. campestris-0

Ernatant of pv campestris strain B100 at a 30 k fold magnification (OMVs highlighted by arrows). (B) Immunogold electron microscopy of 1% (w/v) uranyl acetate stained cell at 14 k fold magnification after incubation with an anti-B100 antibody which was detected by a 10 nm gold particle bound to a goat anti-rabbit antibody (gold-labelled OMV highlighted by arrows). (C) Immunogold electron micrograph of 1% (w/v) uranyl acetate stained OMVs at 27 k fold magnification after incubation with an anti-B100 antibody detected with a 10 nm gold particle bound to an goat anti-rabbit antibody.<p><b>Copyright information:</b></p><p>Taken from "Analysis of outer membrane vesicle associated proteins isolated from the plant pathogenic bacterium pv. campestris"</p><p>http://www.biomedcentral.com/1471-2180/8/87</p><p>BMC Microbiology 2008;8():87-87.</p><p>Published online 2 Jun 2008</p><p>PMCID:PMC2438364.</p><p></p

Analysis of outer membrane vesicle associated proteins isolated from the plant pathogenic bacterium pv. campestris-2

He brackets with numeration indicate the sections taken from the gel for tryptic digestion. (B) Protein profiles of OMVs isolated from cultures grown in M9 medium and the outer membrane (OM) fraction prepared from the same culture.<p><b>Copyright information:</b></p><p>Taken from "Analysis of outer membrane vesicle associated proteins isolated from the plant pathogenic bacterium pv. campestris"</p><p>http://www.biomedcentral.com/1471-2180/8/87</p><p>BMC Microbiology 2008;8():87-87.</p><p>Published online 2 Jun 2008</p><p>PMCID:PMC2438364.</p><p></p

Analysis of outer membrane vesicle associated proteins isolated from the plant pathogenic bacterium pv. campestris-3

Lar location or function. The pie charts indicate the number of proteins in each group isolated from OMVs collected from M9 medium (A) from XVM2 medium (B) and the outer membrane proteins isolated from cells grown in M9 medium (C). The percentage values within the pie chart give the amount of proteins grouped as virulence-associated, which comprise the groups of virulence factors and type III secretion proteins.<p><b>Copyright information:</b></p><p>Taken from "Analysis of outer membrane vesicle associated proteins isolated from the plant pathogenic bacterium pv. campestris"</p><p>http://www.biomedcentral.com/1471-2180/8/87</p><p>BMC Microbiology 2008;8():87-87.</p><p>Published online 2 Jun 2008</p><p>PMCID:PMC2438364.</p><p></p