Crosstalk between Regnase-1 and -3 shapes mast cell survival and cytokine expression

Dysregulation of mast cell activation can lead to allergic and anaphylactic reactions. Post-transcriptional regulation of immune-related transcripts by RNA-binding proteins (RBPs) is critical in controlling immune cell responses, including mast cell functionality. The Regnase family of RBPs plays a central role in regulating gene expression and controlling immune responses in both lymphoid and myeloid cells. However, what is the functional role of Regnase proteins in mast cells remains to be understood. Using different approaches of Regnase proteins depletion and deletion as well as overexpression by mRNA delivery, we found that Regnase-1 is a powerful negative regulator of mast cell proliferation, survival and ability to produce inflammatory cytokines. On the other hand, Regnase-3 was essential to modulate Regnase-1 expression in mast cells by direct targeting of the 3’-untranslated region of Regnase-1, leading to the destabilization of the Zc3h12a mRNA. Regnase-1 deletion had widespread effect on mast proliferation and survival even in the absence of stimulation and was at least in part linked to specific nuclear functions of Regnase-1 in modulating the ability of mast cells to withstand DNA damage. Overall, we describe the importance of Regnase proteins in modulating mast cell homeostatic and inflammatory responses and we describe the impact of Regnase-1 in the maintenance of genome stability. Bone marrow-derived mast cells (BMMCs) were in vitro differentiated from 3 mice and transfected with siRNAs targeting Zc3h12a, Zc3h12c, or combined. After 48 hours, cells were stimulated with IgE and antigen complexes for 2 hours. Total RNA was extracted from each sample and used for gene expression profiling using the Nanostring nCounter® Myeloid Innate Immunity Panel.