Identifizierung funktioneller Untereinheiten des Transkriptionsfaktors interferon regulatory factor 4
Interferon regulatory factor 4 is a crucial factor in adaptive immunity in both T and B cell mediated processes. Knockout mice lacking IRF4 show severe defects in developing functional T cell subsets, including Th2, Th9 and Th17, as well as B cells arrested in early development stages, which l...
|PDF Full Text
No Tags, Be the first to tag this record!
|Interferon regulatory factor 4 is a crucial factor in adaptive immunity in both T and B cell
mediated processes. Knockout mice lacking IRF4 show severe defects in developing
functional T cell subsets, including Th2, Th9 and Th17, as well as B cells arrested in early
development stages, which leads to absence of IgM in the serum. In T cells, IRF4 serves as
an initiation factor conveying TCR signals, priming cells for proliferation and inducing
master transcriptional regulators such as GATA3, T-bet and RORγt. To fulfil this central
role, interaction with several partners is required, among them BATF and PU.1. We
hypothesize that through precise alterations in IRF4, its functionality can be altered to
achieve selective modification of its immunoregulatory effects. Based on literature results
from binding assays, structural analysis and recurring mutations in cancer patients, we tested
many point mutations in IRF4 for their functionality in Th2, Th9 and Th17 differentiation.
Several mutations show immunomodulatory potential. Most prominent among them is
L116R, which induces Th9 differentiation and IL-9 production in Th2 cells, while at the
same time reducing Th2 and Th17 differentiation. Further, we could show that autoinhibition
of IRF4 is differentially affecting helper T cell subtypes, acting much stronger on Th9 and
Th17 cells compared to Th2 differentiated cells. In addition, tumors emerging in old IRF4
knockout mice allowed us to further study leukemogenesis and B cell development in the
context of IRF4 deficiency, leading to a disease similar to human Ph-like B-ALL. Treatment
of this disease with the JAK inhibitor Ruxolitinib increased survival by reducing blast
infiltration in the central nervous system and solid organs.
Here we show that immunomodulation via point mutations is possible and that IRF4 has
subdomains that differentially affect helper T cell subtypes, further scrutinize the effects of
autoinhibition in IRF4 and establish a potential mouse model for human Ph-like B-ALL.