Reciprocal, methylation-dependent binding of Zfp57 and Gzf1 safeguards Dlk1-Dio3 imprinting during developmental reprogramming.

GZF1 and ZFP57 reciprocally bind to safeguard Dlk1-Dio3 imprinting, preventing methylation changes that threaten parent-specific gene expression during development.

• Why it matters: Understanding how unmethylated alleles resist de novo methylation is crucial for revealing mechanisms that maintain epigenetic stability and proper gene regulation across generations.
• What they did: The study used an allelic methylation reporter and genome-wide loss-of-function screening to identify GZF1, which binds unmethylated maternal ICRs, and ZFP57, revealing a methylation-dependent reciprocal binding mechanism.
• The result: Loss of either factor causes imprinting failure: GZF1 loss leads to maternal allele methylation and silencing, while ZFP57 loss results in maternalization, highlighting a protective system essential for embryonic development and survival.