Global protein expression profiling of zebrafish organs based on in vivo incorporation of stable isotopes

The zebrafish has become a widely used model organism employed for developmental studies, live cell imaging, and genetic screens. High-resolution transcriptional profiles of different developmental and adult stages of the fish and of its various organs were generated, which are readily accessible via the ZFIN database. In contrast, quantitative proteomic studies of zebrafish organs are still in their infancy. Here, we used the SILAC (stable isotope labeling by amino acids in cell culture) zebrafish as a "spike-in" reference to generate a protein atlas of nine organs including gills, brain, heart, muscle, liver, spleen, skin, swim bladder, and testis. Single-shot 4 h LC gradients coupled to a Quadrupole-Orbitrap (QExactive) instrument allowed identification of over 5000 proteins in less than 5 days, of which more than 70% were quantified in triplicate. Identified proteins were subjected to BLAST searches and Gene Ontology classification to improve annotation of zebrafish proteins and obtain insights into potential functions. Comparison to mouse tissue proteome data sets revealed differences and similarities in the protein composition of zebrafish versus mouse organs. We reason that the data set will be helpful for the proteomic characterization of zebrafish organs and identification of tissue-specific proteins that might serve as biomarkers. Our approach provides a complementary view into the biochemistry of zebrafish models and will assist large-scale protein quantification in zebrafish disease models.