Imaging of Proteins in Tissue Samples Using Nanospray Desorption Electrospray Ionization Mass Spectrometry.
Chemical maps of tissue samples provide important information on biological processes therein. Recently, advances in tissue imaging have been achieved using ambient ionization techniques, such as desorption electrospray ionization mass spectrometry (DESI-MS), but such techniques have been almost exclusively confined to the mapping of lipids and metabolites. We report here the use of nanospray desorption electrospray ionization (nanoDESI) that allows us to image proteins in tissue samples in a label-free manner at atmospheric pressure with only minimum sample preparation. Multiply charged proteins with masses up to 15 kDa were successfully detected by nanoDESI using an LTQ Orbitrap mass spectrometer. In an adult mice brain section, expression of proteins including ubiquitin, β-thymosin, myelin basic protein, and hemoglobin were spatially mapped and characterized. We also determined the location of methylation on myelin basic protein. This imaging modality was further implemented to MYC-induced lymphomas. We observed an array of truncated proteins in the region where normal thymus cells were infiltrated by tumor cells, in contrast to healthy tissue.
Department of Chemistry, Stanford University , Stanford, California 94305, United States.|Department of Chemistry, National Taiwan University , Taipei 10617, Taiwan.
Cheng-Chih
CC
Hsu
Department of Chemistry, National Taiwan University , Taipei 10617, Taiwan.
Pi-Tai
PT
Chou
Department of Chemistry, Stanford University , Stanford, California 94305, United States.
Richard N
RN
Zare
D000818:Animals; D003952:Diagnostic Imaging; D008223:Lymphoma / Q000378:metabolism*; D051379:Mice; D057054:Molecular Imaging; D036103:Nanotechnology; D011506:Proteins / Q000032:analysis* / Q000235:genetics; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D013950:Thymus Gland / Q000378:metabolism*
D011506:Proteins; D016271:Proto-Oncogene Proteins c-myc