Understanding the role of hnRNPA1 on T cell differentiation and function in the Gut

Abstract

Abstract Regulatory T cells (Treg) play a critical role in preventing autoimmunity diseases and maintaining tolerance in various tissues, particularly the gut. Peripheral derived Tregs (pTregs) are especially crucial in gut homeostasis and tolerance to commensal and food antigens. We have previously shown that knockdown of the RNA-binding protein, heterogeneous nuclear ribonucleoprotein (hnRNP) A1, reduces in vitro pTreg induction upon low TCR stimulation. In addition, we have shown that, under conditions of low TCR stimulation, in which pTreg are induced, hnRNP A1 is phosphorylated by Akt. In order to explore the impact of hnRNP A1 phosphorylation by Akt on pTreg induction in vivo we have generated a mutant mouse model, hnRNPA1-S199 in which the known Akt phosphorylation site on hnRNP A1 is mutated to Alanine. Extensive characterization of immune cells in this mutant mouse revealed no abnormalities in the number or frequency of major immune cell types at steady state. However, we identified abnormalities in the number of Treg in the mesenteric lymph nodes (mLN) in mutant mice, prompting further investigation. Using the Cytex Aurora flow cytometer we developed a 19 color T cell panel to characterize T cells in the mLN, Peyer’s patches and lamina propria. Detailed characterization of the pTreg and tTreg populations in the gut of WT and mutant mice will determine whether the abnormalities observed in the mLN are reflected in different intestinal areas. In addition, we are examining the induction of pTreg using an adoptive transfer model of OT-II TCR transgenic mutant and WT CD4 T cells followed by oral OVA administration. Further studies will focus on the mechanisms by which hnRNP A1 impacts pTreg induction.