A New Model of Spontaneous Colitis in Mice Induced by Deletion of an RNA m6A Methyltransferase Component METTL14 in T Cells
- Cell Mol Gastroenterol Hepatol. 2020;10(4):747-761. doi: 10.1016/j.jcmgh.2020.07.001.
- 1. Section of Gastroenterology, Hepatology, and Nutrition, University of Chicago Medicine, Chicago, Illinois.
- 2. Department of Chemistry, University of Chicago, Chicago, Illinois; Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois.
- 3. Genentech, South San Francisco, California.
- 4. Department of Chemistry, University of Chicago, Chicago, Illinois; Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois; Howard Hughes Medical Institute, Chicago, Illinois. Electronic address: [email protected].
Background and aims: Mouse models of Colitis have been used to study the pathogenesis of Inflammatory Bowel Disease (IBD) and for pre-clinical development of therapeutic agents. Various epigenetic pathways have been shown to play important regulatory roles in IBD. Reversible N6-methyladenosine (m6A) methylation represents a new layer of post-transcriptional gene regulation that affects a variety of biological processes. We aim to study how deletion of a critical component of m6A writer complex, METTL14, in T cells affects the development of Colitis.
Methods: Conditional Mettl14 was lineage specifically deleted with CD4-regulated Cre in T cells. Colitis phenotype was determined by H&E staining, colon weight-to-length ratio and cytokine expression. We additionally utilized T cell transfer model of Colitis and adoptive transfer of regulatory T cells. Mice were treated with Antibiotics to determine if the Colitis could be attenuated.
Results: METTL14 deficiency in T cells induced spontaneous Colitis in mice. This was characterized by increased inflammatory cell infiltration, increased colonic weight-to-length ratio and increased Th1 and Th17 cytokines. The Colitis development was due to dysfunctional regulatory T (Treg) cells, as adoptive transfer of WT Treg cells attenuated the Colitis phenotype. The METTL14-deficient Treg cells have decreased RORγt expression compared with WT controls. METTL14 deficiency caused impaired induction of naïve T cells into induced Treg cells. Antibiotic treatment notably attenuated the Colitis development.
Conclusion: Here we report a new mouse model of spontaneous Colitis based on perturbation of RNA methylation in T cells. The Colitis is T cell-mediated and dependent on the microbiome. This model represents a new tool for elucidating pathogenic pathways, studying the contribution of intestinal microbiome and preclinical testing of therapeutic agents for Inflammatory Bowel Disease.