title: Proteomic analysis of membrane microdomain-associated proteins in the dorsolateral prefrontal cortex in schizophrenia and bipolar disorder reveals alterations in LAMP, STXBP1 and BASP1 protein expression.
abstract: The dorsolateral prefrontal cortex (dlpfc) is strongly implicated in the pathogenesis of schizophrenia (SCZ) and bipolar disorder (BPD) and, within this region, abnormalities in glutamatergic neurotransmission and synaptic function have been described. Proteins associated with these functions are enriched in membrane microdomains (MM). In the current study, we used two complementary proteomic methods, two-dimensional difference gel electrophoresis and one-dimensional sodium dodecyl sulphate polyacrylamide gel electrophoresis followed by reverse phase-liquid chromatography-tandem mass spectrometry (RP-LC-MS/MS) (gel separation liquid chromatography-tandem mass spectrometry (GeLC-MS/MS)) to assess protein expression in MM in pooled samples of dlpfc from SCZ, BPD and control cases (n=10 per group) from the Stanley Foundation Brain series. We identified 16 proteins altered in one/both disorders using proteomic methods. We selected three proteins with roles in synaptic function (syntaxin-binding protein 1 (STXBP1), brain abundant membrane-attached signal protein 1 (BASP1) and limbic system-associated membrane protein (LAMP)) for validation by western blotting. This revealed significantly increased expression of these proteins in SCZ (STXBP1 (24% difference; P<0.001), BASP1 (40% difference; P<0.05) and LAMP (22% difference; P<0.01)) and BPD (STXBP1 (31% difference; P<0.001), BASP1 (23% difference; P<0.01) and LAMP (20% difference; P<0.01)) in the Stanley brain series (n=20 per group). Further validation in dlpfc from the Harvard brain subseries (n=10 per group) confirmed increased protein expression in SCZ of STXBP1 (18% difference; P<0.0001), BASP1 (14% difference; P<0.0001) but not LAMP (20% difference; P=0.14). No significant differences in STXBP1, BASP1 or LAMP protein expression in BPD dlpfc were observed. This study, through proteomic assessments of MM in dlpfc and validation in two brain series, strongly implicates LAMP, STXBP1 and BASP1 in SCZ and supports the view of a neuritic and synaptic dysfunction in the neuropathology of SCZ.
authors.affiliation: Department of Psychiatry, Royal College of Surgeons in Ireland, RCSI ERC, Smurfit Building, Beaumont Hospital, Dublin 9, Ireland.
authors.forename: A T
authors.initials: AT
authors.lastname: Behan
authors.forename: C
authors.initials: C
authors.lastname: Byrne
authors.forename: M J
authors.initials: MJ
authors.lastname: Dunn
authors.forename: G
authors.initials: G
authors.lastname: Cagney
authors.forename: D R
authors.initials: DR
authors.lastname: Cotter
mesh_terms: D000328:Adult; D000368:Aged; D001714:Bipolar Disorder / Q000378:metabolism*; D015153:Blotting, Western; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism*; D002853:Chromatography, Liquid; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D058851:GPI-Linked Proteins; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D008875:Middle Aged; D051938:Munc18 Proteins / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D017397:Prefrontal Cortex / Q000378:metabolism*; D040901:Proteomics / Q000379:methods / Q000592:standards; D011990:Receptors, Transferrin / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism*; D015203:Reproducibility of Results; D012559:Schizophrenia / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D053719:Tandem Mass Spectrometry
chemical_list: C104089:BASP1 protein, human; D015816:Cell Adhesion Molecules, Neuronal; D058851:GPI-Linked Proteins; D008565:Membrane Proteins; D051938:Munc18 Proteins; D009419:Nerve Tissue Proteins; D011990:Receptors, Transferrin; D012097:Repressor Proteins; C497937:STXBP1 protein, human; C106354:flotillins; C095362:limbic system-associated membrane protein