Dynamic Interaction- and Phospho-Proteomics Reveal Lck as a Major Signaling Hub of CD147 in T Cells.

Numerous publications have addressed CD147 as a tumor marker and regulator of cytoskeleton, cell growth, stress response, or immune cell function; however, the molecular functionality of CD147 remains incompletely understood. Using affinity purification, mass spectrometry, and phosphopeptide enrichment of isotope-labeled peptides, we examined the dynamic of the CD147 microenvironment and the CD147-dependent phosphoproteome in the Jurkat T cell line upon treatment with T cell stimulating agents. We identified novel dynamic interaction partners of CD147 such as CD45, CD47, GNAI2, Lck, RAP1B, and VAT1 and, furthermore, found 76 CD147-dependent phosphorylation sites on 57 proteins. Using the STRING protein network database, a network between the CD147 microenvironment and the CD147-dependent phosphoproteins was generated and led to the identification of key signaling hubs around the G proteins RAP1B and GNB1, the kinases PKCβ, PAK2, Lck, and CDK1, and the chaperone HSPA5. Gene ontology biological process term analysis revealed that wound healing-, cytoskeleton-, immune system-, stress response-, phosphorylation- and protein modification-, defense response to virus-, and TNF production-associated terms are enriched within the microenvironment and the phosphoproteins of CD147. With the generated signaling network and gene ontology biological process term grouping, we identify potential signaling routes of CD147 affecting T cell growth and function.