The Role of IKZF3 Expression in T Cells of Patients with Multiple Myeloma

Abstract

In my dissertation, I investigated the role of IKZF protein family in T cells by establishing a CRISPR Cas9 model in CD8+ T cells. I analysed the down-stream signaling pathway of IKZF3 by high-throughput RNA bulk sequencing method and proteomics analysis, including co-immunoprecipitation and protein binding analysis, to identify function and regulatory mechanisms of this protein family in T cells. I demonstrated that IKZF3 regulates the IFN-inducible gene expression, and thus, IKZF3 KO CD8+ T cells showed increased expression of cell surface markers for T cell activation and exhaustion. In addition, I showed that IKZF3 binds to IKZF1 at the C’ terminal for heterodimerization in exhausted CD8+ T cells. Whereas in the absence of IKZF1, IKZF3 forms heterodimer complexes with MX1 and DTX3L. Single KO of IKZF1 in CD8+ T cells showed that the transcription factor regulates gene expression involved in T cell activation on transcriptomic level and on functional level, I found increased cell surface marker expression of T cell activation. In MM patients, I found that newly diagnosed MM patients with high IKZF3 expression levels have significantly higher amount of effector T cells. In conclusion, I found evidence of IKZFs playing a superior role in T cell activation and drive T cells to exhaustion, and gave preliminary conclusions of the IKZF protein family functionality in CD8+ T cells. Previously, studies were mainly focusing on IKZF within the B cell compartment as a critical regulator of B cell development and functionality. My findings indicate novel IKZF regulatory mechanisms within the CD8+ T cell compartement, providing new insights in T cell modulation, and therefore, making the transcription factor protein family a promising target for cancer immunotherapy