Development of an On-Tissue Derivatization Method for MALDI Mass Spectrometry Imaging of Bioactive Lipids Containing Phosphate Monoester Using Phos-tag.

Affiliation

Iwama T(1)(2), Kano K(1)(2)(3), Saigusa D(3)(4)(5), Ekroos K(6), van Echten-Deckert G(7), Vogt J(8), Aoki J(1)(2)(3).
Author information:
(1)Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-8654, Japan.
(2)Laboratory of Molecular and Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai980-8577, Japan.
(3)AMED-LEAP, Tokyo100-0004, Japan.
(4)Department of Integrative Genomics, Tohoku Medical Megabank Organization, Tohoku University, Sendai980-8577, Japan.
(5)Medical Biochemistry, Tohoku University School of Medicine, Sendai 980-8575, Japan.
(6)Lipidomics Consulting Ltd., 02230 Espoo, Finland.
(7)LIMES Institute, Membrane Biology & Lipid Biochemistry, University of Bonn, 53113 Bonn, Germany.
(8)Department of Molecular and Translational Neurosciences, University Medical Hospital, University of Cologne, 50923 Cologne, Germany.

Abstract

Matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) is an emerging label-free method for mapping the distribution of diverse molecular species in tissue sections. Despite recent progress in MALDI-MSI analyses of lipids, it is still difficult to visualize minor bioactive lipids including lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P). Here, we have developed a novel on-tissue derivatization method using Phos-tag, a zinc complex that specifically binds to a phosphate monoester group. MALDI-MSI with Phos-tag derivatization made it possible to image LPA and S1P in the murine brain. Furthermore, we were able to visualize other low-abundance lipids containing phosphate monoester, such as phosphatidic acid and ceramide-1-phosphate. Compared with conventional MALDI-MS, this derivatization produced LPA images with high spatial accuracy discriminating LPA artificially produced during MALDI-MS analysis. In mice with deficiencies in enzymes that degrade LPA and S1P, we observed marked S1P and/or LPA accumulation in specific regions of the brain. Thus, the present study provides a simple and optimal way to reveal the spatial localization of potent bioactive lipid phosphates such as LPA and S1P in tissues.