Deep Proteome of the Developing Chick Midbrain

The epithelial-to-mesenchymal transition (EMT) and migration of cranial neural crest cells are critical processes that occur in the early embryo that permit proper craniofacial patterning. Disruptions in these processes not only impair development but also lead to various diseases, underscoring the need for their detailed understanding at the molecular level. The chick embryo has served historically as an excellent model for human embryonic development. While chick cranial neural crest cell EMT and migration have been characterized at the transcript level, studies at the protein level—to allow direct measurement of the active players—have not been undertaken to date. In this study, we applied mass spectrometry (MS)-based proteomics to establish a deep proteomics profile of the midbrain region during early embryonic development. We developed a proteomics method combining optimal lysis conditions and offline fractionation with nanoflow liquid chromatography coupled to high-resolution MS to analyze the tissue from this region, which identified >5,900 proteins involved in key pathways related to neural crest cell EMT and migration such as signaling, proteolysis/extracellular matrix (ECM), and transcriptional regulation. This study offers valuable insight into important developmental processes occurring in the midbrain region and demonstrates the utility of proteomics for characterization of various tissues during chick embryogenesis.