Ezh2 Conditional Knockout mouse models

Ezh2, ortholog of human EZH2, encodes the SET domain catalytic subunit of polycomb repressive complex 2, which requires EED and SUZ12 for activity and is allosterically stimulated when the EED aromatic cage binds preexisting H3K27 trimethylation, generating the spreading repressive domains that silence developmental and tumor suppressor loci. Disease alleles run in opposite directions: Y646 substitutions in the SET domain shift substrate preference toward the final trimethylation step and hyperactivate the enzyme in germinal center lymphoma, whereas nonsense and missense loss-of-function mutations occur in myelodysplastic syndrome and T cell leukemia. Model design must reflect this, using a conditional inducible Y646 knockin for lymphoma and inhibitor response work and a conditional null for myeloid loss-of-function questions. Constitutive deletion is embryonic lethal near gastrulation, so Cre-dependent alleles are required, and the paralog Ezh1 sustains residual H3K27 methylation in quiescent and postmitotic tissues, meaning compound Ezh1 deletion may be needed to unmask phenotypes.

Tissue restricted knockout of Ezh2 keeps wild type function everywhere else. Breeding is often more robust, and the setup mirrors patient biology where mutations arise in a subset of cells.