Loss of Elp3 impairs the immune response to helminths by blocking intestinal tuft cell differentiation
Intestinal tuft cells are critical in anti-helminth immunity by producing IL-25, which triggers IL-13 secretion by activated group 2 innate lymphoid cells (ILC2s) in order to ultimately expand both goblet and tuft cells. Translational reprogramming is involved in intestinal tuft cell differentiation but the role of tRNA modifications in this process is unknown. We show here that epithelial Elp3, a tRNA-modifying enzyme, promotes tuft cell differentiation and is consequently critical for IL-25 production, ILC2 activation, goblet cell expansion and control of N. brasiliensis infection in mice. Elp3 is essential for the IL-13-dependent induction of some glycolytic enzymes such as Hexokinase 1 and Aldolase A and consequently links specific metabolic pathways to tuft cell differentiation. Importantly, loss of epithelial Elp3 in the intestine blocks the translation of Nprl2, a mTORC1 inhibitor, which consequently enhances mTORC1 activation and stabilizes Atf4 in both transit amplifying and progenitor cells. Likewise, Atf4 overexpression in mouse intestinal epithelium blocks tuft cell differentiation and impairs the control of intestinal helminth infection. Collectively, our data define Atf4 as a negative regulator of tuft cell differentiation and provide insights into mechanisms through which some tRNA modifications promote a type 2 immune response to parasites in the intestine. Overall design: To investigate the role of the tRNA-modifying enzyme Elp3 in tuft cell differentiation, we performed a Single Cell RNA-sequencing on intestinal epithelial cells from Elp3WT vs Elp3?IEC mice. Mice were treated overnight with rIL-13 in order to induce tuft cell differentiation.