PIWI proximity proteome reveals Set1-mediated piRNA biogenesis for transposon silencing at telomeres.

Set1 is essential for piRNA production and transposon silencing at telomeres in Drosophila germline, acting independently of its catalytic activity.

• Why it matters: Understanding the mechanisms of transposable element silencing is crucial for maintaining genome integrity in the germline, yet the full range of factors involved remains unclear.
• What they did: Researchers characterized the PIWI proximity proteome in Drosophila ovaries, identified Set1 as a key TE repressor, and demonstrated its association with TE sequences and piRNA loci through genome-wide chromatin profiling.
• The result: Set1's noncanonical role enables antisense TE-targeting piRNA production and transposon repression at telomeres, highlighting a new function for Set1 in Piwi-mediated genome defense.