title: Characterization of the human cerebrospinal fluid phosphoproteome by titanium dioxide affinity chromatography and mass spectrometry.
abstract: Biomarkers in the cerebrospinal fluid (CSF) may be important for the diagnosis of chronic degenerative disorders in the central nervous system including dementia. Existing CSF biomarkers for dementia, however, are relatively nonspecific. More specific markers may be found by targeting investigations based on knowledge of the molecular pathology of the disease in question. In Alzheimer's disease, hyperphosphorylation of the tau protein is a characteristic feature and thus a comprehensive characterization of the phosphoproteome of the CSF may be pursued to obtain a complete picture of phosphorylation aberrations in health and disease. Toward that goal we here describe a method for a comprehensive isolation and identification of phosphorylated tryptic peptides derived from CSF proteins using a simple sample preparation step and titanium dioxide-affinity chromatography followed by MALDI-TOF or LC-MS/MS linear ion-trap-FT mass spectrometry. Whereas not all previously reported phosphoproteins were found in normal CSF, we detected 56 putative novel phosphorylation sites in 38 proteins in addition to known sites. The approach seems to be a promising foundation for the discovery of new biomarkers embedded in the CSF phosphoproteome.
authors.affiliation: Department of Clinical Biochemistry and Autoimmunology, Statens Serum Institut, Artillerivej 5, DK-2300 Copenhagen S, Denmark. jmc@ssi.dk
authors.forename: Justyna Maria Czarna
authors.initials: JM
authors.lastname: Bahl
authors.forename: Søren Skov
authors.initials: SS
authors.lastname: Jensen
authors.forename: Martin R
authors.initials: MR
authors.lastname: Larsen
authors.forename: Niels H H
authors.initials: NH
authors.lastname: Heegaard
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000032:analysis; D002556:Cerebrospinal Fluid Proteins / Q000134:cerebrospinal fluid*; D002846:Chromatography, Affinity / Q000379:methods*; D002853:Chromatography, Liquid / Q000379:methods; D019295:Computational Biology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009422:Nervous System Diseases / Q000134:cerebrospinal fluid* / Q000175:diagnosis; D010449:Peptide Mapping; D010750:Phosphoproteins / Q000032:analysis* / Q000302:isolation & purification; D020543:Proteome / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D014025:Titanium / Q000737:chemistry* / Q000378:metabolism
chemical_list: D015415:Biomarkers; D002556:Cerebrospinal Fluid Proteins; D010750:Phosphoproteins; D020543:Proteome; C009495:titanium dioxide; D014025:Titanium