title: On-tissue protein identification and imaging by MALDI-ion mobility mass spectrometry.
abstract: MALDI imaging mass spectrometry (MALDI-IMS) has become a powerful tool for the detection and localization of drugs, proteins, and lipids on-tissue. Nevertheless, this approach can only perform identification of low mass molecules as lipids, pharmaceuticals, and peptides. In this article, a combination of approaches for the detection and imaging of proteins and their identification directly on-tissue is described after tryptic digestion. Enzymatic digestion protocols for different kinds of tissues--formalin fixed paraffin embedded (FFPE) and frozen tissues--are combined with MALDI-ion mobility mass spectrometry (IM-MS). This combination enables localization and identification of proteins via their related digested peptides. In a number of cases, ion mobility separates isobaric ions that cannot be identified by conventional MALDI time-of-flight (TOF) mass spectrometry. The amount of detected peaks per measurement increases (versus conventional MALDI-TOF), which enables mass and time selected ion images and the identification of separated ions. These experiments demonstrate the feasibility of direct proteins identification by ion-mobility-TOF IMS from tissue. The tissue digestion combined with MALDI-IM-TOF-IMS approach allows a proteomics "bottom-up" strategy with different kinds of tissue samples, especially FFPE tissues conserved for a long time in hospital sample banks. The combination of IM with IMS marks the development of IMS approaches as real proteomic tools, which brings new perspectives to biological studies.
authors.affiliation: FOM Institute for Atomic and Molecular Physics, Amsterdam, The Netherlands.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Stauber
authors.forename: Luke
authors.initials: L
authors.lastname: MacAleese
authors.forename: Julien
authors.initials: J
authors.lastname: Franck
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Claude
authors.forename: Marten
authors.initials: M
authors.lastname: Snel
authors.forename: Basak Kükrer
authors.initials: BK
authors.lastname: Kaletas
authors.forename: Ingrid M V D
authors.initials: IM
authors.lastname: Wiel
authors.forename: Maxence
authors.initials: M
authors.lastname: Wisztorski
authors.forename: Isabelle
authors.initials: I
authors.lastname: Fournier
authors.forename: Ron M A
authors.initials: RM
authors.lastname: Heeren
mesh_terms: D000818:Animals; D020869:Gene Expression Profiling / Q000379:methods*; D008297:Male; D010449:Peptide Mapping / Q000379:methods*; D020543:Proteome / Q000032:analysis* / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D013048:Specimen Handling / Q000379:methods*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D046888:Tissue Array Analysis / Q000379:methods*; D014357:Trypsin / Q000737:chemistry
chemical_list: D020543:Proteome; D014357:Trypsin