The RNA binding protein HNRNPA2B1 regulates IFNG signaling in macrophages
Heterogeneous nuclear ribonucleoprotein A2B1 (HNRNPA2B1) is a well known RNA binding protein but the mechanisms by which it contributes to innate immune gene regulation is poorly understood. Here we report that HNRNPA2B1 functions in macrophages to regulate IFNG signaling through alternative splicing of the IFNG receptor. Specific deletion of HNRNPA2B1 in macrophages using our newly developed conditional mice crossed to LysMCre resulted in altered cytokine responses in both an endotoxic shock model and following Salmonella infection. Interestingly, while HNRNPA2B1 can function as a viability gene, we observed increased macrophage and neutrophil numbers in the KO mice following LPS induced endotoxic shock.  HNRNPA2B1 KO mice were more susceptible to Salmonella and Mycobacterium Tuberculosis infections and failed to effectively clear the pathogens. Mechanistically, loss of HNRNPA2B1 resulted in an increase in No-GO transcripts of the IFNG receptor (Ifngr) leading to lower expression of the receptor at the cell surface impacting the downstream IFNG signaling cascade. Collectively, our data highlights an important role for HNRNPA2B1 in regulating IFNG signaling in macrophages. Overall design: HnrnpA2B1 was knocked out in mouse myeloid lineage cells using a LysM-Cre coupled with a Cre-loxp system with loxp sites flanking exons 2 and 7. Bone marrow derived macrophages from control (loxp/loxp) mice and KO mice were isolated and stimulated with LPS for 0 or 5 hours. Experiments were performed in biological triplicate.