Characterization of the mast cell surface proteome leads to the identification of CD98hc as a critical surface molecule for optimal mast cell function

Abstract

Abstract Mast cells are known for their involvement in many distinct pathological conditions, suggesting that mast cells recognize and respond to various stimuli and thus require a rich cell surface protein repertoire. Mast cell surface proteomes have not been comprehensively characterized. In this study, we aimed to further characterize the mast cell surface proteome to obtain a better understanding of how mast cells function in health and disease. We enriched for glycosylated surface proteins expressed in murine bone marrow-derived mast cells (BMCMCs) and identified them using mass spectrometry analysis. This approach resulted in the identification of 1270 proteins in BMCMCs, 403 of which were localized to the plasma membrane. The most common protein classes among plasma membrane proteins are represented by small GTPases, receptors and transporters. Novel surface proteins in mast cells was validated by qPCR and flow cytometry analysis in BMCMCs and peritoneal mast cells (PMCs). Among the novel surface proteins, we found that CD98 heavy chain (CD98hc) encoded by the Slc3a2 gene, was highly expressed in mast cells. Slc3a2 gene disruption by CRISPR/Cas9 gene editing resulted in a significant reduction in CD98hc expression, mast cell degranulation, adhesion and proliferation. Our study indicates that we can use glycoprotein enrichment coupled with mass spectrometry to identify novel surface molecules in mast cells. Moreover, we found that CD98hc plays an important role in mast cell function.