ABSTRACT
Post-transcriptional regulation of immune-related transcripts by RNA-binding proteins (RBPs) impacts immune cell responses, including mast cell functionality. Despite their importance in immune regulation, the functional role of most RBPs remains to be understood. By manipulating the expression of specific RBPs in murine mast cells, coupled with mass spectrometry and transcriptomic analyses, we found that the Regnase family of proteins acts as a potent regulator of mast cell physiology. Specifically, Regnase-1 is required to maintain basic cell proliferation and survival, whereas both Regnase-1 and -3 cooperatively regulate the expression of inflammatory transcripts upon activation, with Tnf being a primary target in both human and mouse cells. Furthermore, Regnase-3 directly interacts with Regnase-1 in mast cells and is necessary to restrain Regnase-1 expression through the destabilization of its transcript. Overall, our study identifies protein interactors of endogenously expressed Regnase factors, characterizes the regulatory interplay between Regnase family members in mast cells, and establishes their role in the control of mast cell homeostasis and inflammatory responses.
Subject(s)
Cell Survival , Cytokines , Mast Cells , Mast Cells/metabolism , Animals , Mice , Humans , Cytokines/metabolism , Cell Survival/genetics , Ribonuclease, Pancreatic/metabolism , Ribonuclease, Pancreatic/genetics , Ribonucleases/metabolism , Ribonucleases/genetics , Gene Expression Regulation , RNA-Binding Proteins/metabolism , RNA-Binding Proteins/genetics , Mice, Inbred C57BL , Cell Proliferation , Inflammation/metabolism , Transcription FactorsABSTRACT
Roquin and Regnase-1 proteins bind and post-transcriptionally regulate proinflammatory target messenger RNAs to maintain immune homeostasis. Either the sanroque mutation in Roquin-1 or loss of Regnase-1 cause systemic lupus erythematosus-like phenotypes. Analyzing mice with T cells that lack expression of Roquin-1, its paralog Roquin-2 and Regnase-1 proteins, we detect overlapping or unique phenotypes by comparing individual and combined inactivation. These comprised spontaneous activation, metabolic reprogramming and persistence of T cells leading to autoimmunity. Here, we define an interaction surface in Roquin-1 for binding to Regnase-1 that included the sanroque residue. Mutations in Roquin-1 impairing this interaction and cooperative regulation of targets induced T follicular helper cells, germinal center B cells and autoantibody formation. These mutations also improved the functionality of tumor-specific T cells by promoting their accumulation in the tumor and reducing expression of exhaustion markers. Our data reveal the physical interaction of Roquin-1 with Regnase-1 as a hub to control self-reactivity and effector functions in immune cell therapies.
Subject(s)
Autoimmunity , Cytotoxicity, Immunologic , Immunotherapy, Adoptive , Melanoma, Experimental/therapy , Repressor Proteins/metabolism , Ribonucleases/metabolism , Skin Neoplasms/therapy , T-Lymphocytes/transplantation , Ubiquitin-Protein Ligases/metabolism , Animals , Female , HEK293 Cells , HeLa Cells , Humans , Immunity, Humoral , Male , Melanoma, Experimental/genetics , Melanoma, Experimental/immunology , Melanoma, Experimental/metabolism , Mice, Inbred C57BL , Mice, Transgenic , Mutation , Phenotype , Protein Binding , Repressor Proteins/genetics , Ribonucleases/genetics , Skin Neoplasms/genetics , Skin Neoplasms/immunology , Skin Neoplasms/metabolism , T-Lymphocytes/immunology , T-Lymphocytes/metabolism , Tumor Microenvironment , Ubiquitin-Protein Ligases/geneticsABSTRACT
Post-transcriptional gene regulation in T cells is dynamic and complex as targeted transcripts respond to various factors. This is evident for the Icos mRNA encoding an essential costimulatory receptor that is regulated by several RNA-binding proteins (RBP), including Roquin-1 and Roquin-2. Here, we identify a core RBPome of 798 mouse and 801 human T cell proteins by utilizing global RNA interactome capture (RNA-IC) and orthogonal organic phase separation (OOPS). The RBPome includes Stat1, Stat4 and Vav1 proteins suggesting unexpected functions for these transcription factors and signal transducers. Based on proximity to Roquin-1, we select ~50 RBPs for testing coregulation of Roquin-1/2 targets by induced expression in wild-type or Roquin-1/2-deficient T cells. Besides Roquin-independent contributions from Rbms1 and Cpeb4 we also show Roquin-1/2-dependent and target-specific coregulation of Icos by Celf1 and Igf2bp3. Connecting the cellular RBPome in a post-transcriptional context, we find contributions from multiple RBPs to the prototypic regulation of mRNA targets by individual trans-acting factors.
