This study examined how cytokine signals reshape 3D chromatin architecture at the *Ets1-Fli1* locus in CD4+ T cells, using single-allele chromatin tracing and epigenomic profiling in double-positive thymocytes and Th1 cells — with genetic deletion of a CTCF boundary and a T cell super-enhancer.
In Th1 cells, cytokines increased multi-way chromatin interactions and repositioned the super-enhancer toward the locus geometric center, activating both *Ets1* and *Fli1*; super-enhancer deletion reverted Th1 cells to a structurally and transcriptionally double-positive–like state, while CTCF boundary deletion decompacted the locus without affecting *Ets1* expression or T cell development.
Findings are based primarily on mouse models; direct translation to human CD4+ T cell biology and autoimmune disease variants requires further validation. Single-locus focus limits generalizability to other super-enhancer–regulated genes. Causal links between noncoding variants at this locus and specific human immune disorders remain inferential.
This study offers a mechanistic framework for how noncoding variants near *Ets1-Fli1* may drive CD4+ T cell–mediated immune disorders — clinicians studying autoimmunity genetics should consider super-enhancer repositioning as a potential mechanism for disease-linked regulatory variants at this locus.
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