Hao Shi

CD8⁺ T cell exhaustion impedes control of chronic viral infection and cancer. This hypofunctional state is characterized by downregulation of the high-affinity IL-2 receptor (IL-2R) and STAT5 signalling, and differentiation from progenitor exhausted to terminally exhausted T cells rather than cytotoxic effector-like cells^1,2,3. The epigenetic mechanisms and regulatory networks that mediate IL-2R–STAT5 signal attenuation and loss of effector-like cell differentiation remain unknown. Here, using in vivo single-cell CRISPR screens of epigenetic factors and IL-2 signalling regulators, we reveal that the chromatin reader ZMYND8 antagonizes IL-2R–STAT5 signals to restrain effector-like states while promoting terminal exhaustion. ZMYND8 expression was upregulated by chronic antigen stimulation, and targeting ZMYND8 in CD8⁺ T cells promoted both intermediate exhausted T cells and killer cell lectin-like receptor-expressing exhausted T cells. Accordingly, ZMYND8-deficient CD8⁺ T cells had markedly improved antiviral and antitumour effects, especially in combination with IL-2 therapy or immune checkpoint blockade. Mechanistically, ZMYND8 bound to the active enhancer regions of the Il2ra gene locus that were co-occupied by histone acetyltransferase p300 and suppressed p300 activity. Co-deletion of p300 reversed increased IL-2R expression and effector-like cell differentiation in ZMYND8-deficient cells, suggesting that ZMYND8 represses p300-mediated transcriptional activation to curtail IL-2R–STAT5 signalling. These findings establish an epigenetic rheostat imposing ‘signal 1’ (chronic antigen stimulation)-induced suppression of ‘signal 3’ (IL-2 signalling) to enforce T cell exhaustion, with ZMYND8 deletion unleashing effector-like over terminally exhausted states and enhancing immunotherapeutic efficacy.

AmpliconArchitect reconstructions of MYC-amplified G3-MB cell models.

Post-MAGeCK analysis CRISPRi screen results.

AmpliconArchitect reconstructions of D425 ecDNA after ecMYC E1 silencing.

List of sgRNA sequences for validation experiments.

Dependency Map results for MYC and OTX2 in the G3-MB D425 and D458 cell lines.

PVT1 promoter and MYC transcription in ecDNA-amplified G3-MB.

List of primary and secondary antibodies.