| HRA000957
(Open Access)
|
We uncover that L1s can enrich transcribing RNA polymerase IIs (Pol IIs), express L1 chimeric transcripts and separate chromatin into topologically associating domains (TADs). The activity of L1s as TAD boundary elements is restricted by the nuclear matrix-associated protein Scaffold Attachment Factor B (SAFB), which binds these L1s to inhibit Pol II enrichment and reduces TAD boundary strength. Acute inhibition of Pol II transcription abolishes the L1-associated TAD boundaries, indicating a manner that depends on ongoing transcription. Moreover, genetic deletion of L1 impairs TAD boundary formation, and the persistent L1 insertion during evolution has introduced species-specific TAD boundaries. Our results reveal the role of pervasive L1s as transcription-dependent TAD boundary elements. |
