Site-Specific Clustering of Bioactive Signaling Molecules Predicted In Situ by Space and Time Coherent Mapping for Imaging Mass Spectrometry

Anatomical representation of site-specific clustering of biomolecules is a powerful way of predicting a potential interaction among signaling cascades and orchestrating molecular functions in cells and organs. The greater the number of molecules visualized simultaneously, the deeper we can understand each molecule's role in cellular metabolism and function. In the present study, we investigated site-specific localization of small biomolecules in the slug using Space and Time Coherent Mapping (STCM), a key technology in matrix-assisted laser desorption ionization time-of-flight imaging mass spectrometry. We acquired mass measurements and mass-based molecular images simultaneously under the microscope-mode instrumentation developed specifically in our laboratory. Mass images were generated in the increment of 0.2 in the mass-to-charge ratio (<i>m</i>/<i>z</i>) with spatial resolution of 2 μm. Resultant images were unique in each mass increment and allowed us to predict anatomical site-specific clustering of bioactive signaling molecules. We suggest that STCM is a useful tool to promote the compilation of comprehensive molecular maps and understand the role of individual molecules and their interactive mechanisms in situ.