The Rna-binding Protein Fus/tls Interacts With Spo11 and Provides a Link With Prdm9-dependent Recombination Hotspots

Abstract

Abstract In mammals, meiotic recombination is initiated by the introduction of DNA double strand breaks (DSBs) into narrow segments of the genome, defined as hotspots, which is carried out by the SPO11/TOPOVIBL complex. A major player in hotspots specification is PRDM9, a histone methyltransferase that following sequence-specific DNA binding generates trimethylation on lysine 4 (H3K4me3) and lysine 36 (H3K36me3) of histone H3, thus defining the hotspots. PRDM9 activity is key to successful meiosis, as in its absence DSBs are redirected to functional sites, and synapsis between homologous chromosomes fails. One protein factor recently implicated in guiding PRDM9 activity at hotspots is EWS, a member of the FET family of proteins that also includes TAF15 and FUS/TLS. Here, we demonstrate that FUS/TLS partially co-localizes with PRDM9 on meiotic chromosome axes, marked by the synaptonemal complex component SYCP3, and physically interacts with PRDM9. Furthermore, we show that FUS/TLS also interacts with REC114, one of the axis-bound SPO11-auxiliary factors essential for DSBs formation. This finding suggests FUS/TLS as a component of the protein complex that promotes meiotic recombination initiation. Accordingly, we document that FUS/TLS co-immunoprecipitates with SPO11 in vitro and in vivo. The interaction occurs with both Spo11β and Spo11α splice isoforms, which are thought to play distinct functions in DSB formation onto autosomes and male sex chromosomes, respectively. Finally, by using chromatin immunoprecipitation experiments, we show that FUS/TLS localizes at H3K4me3-marked hotspots onto autosomes and in the pseudo autosomal region, the site of genetic exchange between the XY chromosomes.