ZSCAN20

ZSCAN20 is a transcription factor that selectively governs the differentiation of terminally exhausted CD8+ T cells (TEXterm), a program it drives in a manner decoupled from protective tissue-resident memory T cell (TRM) formation (PMID:41639465). Targeted deletion of ZSCAN20 enhances tumor control, reduces expression of inhibitory receptors, and improves effector function in human T cells, with loss synergizing with immune checkpoint blockade (PMID:41639465). Beyond this transcriptional control of the exhaustion program, no direct target genes, DNA-binding sites, or protein partners have been characterized in the available corpus.

1. 2025 Medium

   Before this work it was unknown which transcription factors selectively control the terminally exhausted CD8+ T cell state versus protective memory programs; an in vivo perturbation screen nominated ZSCAN20 as a selective driver of TEXterm differentiation whose loss improves anti-tumor immunity.

   Evidence In vivo CRISPR screening with in vivo Perturb-seq plus targeted deletion and human T cell effector assays (preprint)

   PMID:36711632

   Open questions at the time

   • Preprint not yet peer-reviewed at time of entry
   • Direct transcriptional targets and DNA-binding sites of ZSCAN20 not defined
   • Mechanism by which ZSCAN20 distinguishes TEXterm from TRM programming unresolved
2. 2026 High

   Peer-reviewed confirmation established that ZSCAN20 deletion enhances tumor control and synergizes with checkpoint blockade while sparing TRM formation, defining it as a selective, druggable node in the exhaustion program.

   Evidence In vivo CRISPR screen integrated with single-cell RNA sequencing and targeted deletion with functional readouts in human T cells

   PMID:41639465

   Open questions at the time

   • No identified ZSCAN20 target genes or cis-regulatory elements
   • No structural or biochemical characterization of its DNA-binding or zinc-finger/SCAN domains
   • Cofactors and chromatin context through which it specifies the TEXterm fate are unknown

• How ZSCAN20 mechanistically enforces the terminally exhausted transcriptional program — its direct target genes, binding sites, and protein partners — remains undefined.
• No direct transcriptional targets identified
• No partner transcription factors or chromatin regulators mapped
• No structural basis for fate selectivity (TEXterm vs TRM)