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Live imaging and biophysical modeling support a button-based mechanism of somatic homolog pairing in Drosophila.
Elife, 10.
Three-dimensional eukaryotic genome organization provides the structural basis forgene regulation. In Drosophila melanogaster, genome folding is characterized bysomatic homolog pairing, where homologous chromosomes are intimately paired from endto end; however, how homologs identify one another and pair has remained mysterious.Recently, this process has been proposed to be driven by specifically interacting'buttons' encoded along chromosomes. Here, we turned this hypothesis into aquantitative biophysical model to demonstrate that a button-based mechanism can leadto chromosome-wide pairing. We tested our model using live-imaging measurements ofchromosomal loci tagged with the MS2 and PP7 nascent RNA labeling systems. We showsolid agreement between model predictions and experiments in the pairing dynamics ofindividual homologous loci. Our results strongly support a button-based mechanism ofsomatic homolog pairing in Drosophila and provide a theoretical framework forrevealing the molecular identity and regulation of buttons.
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