A distal transcribed enhancer of KRAS fine-tunes Tfh-mediated vaccine response 2308711

Abstract

Abstract Introduction Enhancer RNAs (eRNAs) are noncoding transcripts from active enhancers whose functions in adaptive immunity are poorly defined. Because small changes in signaling strength can alter T cell fate and B cell help, we hypothesized that eRNAs act as rheostats for key fate decisions and signaling modules shaping antigen-induced immune responses. Methods We integrated rRNA-depleted RNA-seq, ATAC-seq, and ChIP-seq to map transcribed enhancers in human B, CD4, and CD8 T cells. We then focused on a conserved eRNA ∼140 kb upstream of KRAS (eKRAS) and tested its function using si/shRNA, CRISPR perturbations, and phospho-signaling assays in human T cells, together with eKras—/— mice, mixed bone marrow chimeras, influenza infection, and SARS-CoV-2 mRNA vaccination with downstream cellular and serologic analyses. Results We catalogued and characterized ∼2,000 eRNAs in human adaptive immune cells; eKRAS was among the most highly expressed and conserved and functioned as a cis-acting enhancer of KRAS. Disruption of eKRAS reduced KRAS mRNA and attenuated RAS-ERK activation. Although eKras—/— mice developed normally, immunized mixed chimeras revealed a cell-intrinsic defect in T follicular helper (Tfh) differentiation, with impaired germinal center formation, reduced Tfh effector programs, and defective neutralizing antibody responses to protein antigens and influenza. Following SARS-CoV-2 mRNA vaccination, eKras—/— mice showed reduced class-switched anti-spike antibodies. An eKRAS-dependent Tfh transcriptional program was conserved in human blood and associated with neutralizing antibody titers after COVID-19 vaccination. Conclusion We define a systematic catalog of eRNAs in human adaptive immune cells and identify a distal transcribed enhancer that fine-tunes KRAS signaling in Tfh cells to support effective vaccine responses. These findings establish eRNAs as noncoding regulators of T cell circuits controlling antibody production and nominate the eKRAS-KRAS axis as a target to optimize humoral immunity. Funding Source N/A Topic Categories Immune Response Regulation: Molecular Mechanisms (IRM)