Enhancer architecture sensitizes cell specific responses to Notch gene dose via a bind and discard mechanism
Yi Kuang, Ohad Golan, Kristina Preuße, Brittany Cain, Collin J Christensen, Joseph Salomone, Ian Campbell, FearGod V Okwubido-Williams, Matthew R. Hass, Zhenyu Yuan, Nathanel Eafergan, Kenneth H. Moberg, Rhett A. Kovall, Raphael Kopan, David Sprinzak, Brian Gebelein
Abstract
Notch pathway haploinsufficiency can cause severe developmental syndromes with highly variable penetrance. Currently, we have a limited mechanistic understanding of phenotype variability due to gene dosage. Here, we unexpectedly found that inserting an enhancer containing pioneer transcription factor sites coupled to Notch dimer sites can induce a subset of Notch haploinsufficiency phenotypes in Drosophila with wild type Notch gene dose. Using Drosophila genetics, we show that this enhancer induces Notch phenotypes in a Cdk8-dependent, transcription-independent manner. We further combined mathematical modeling with quantitative trait and expression analysis to build a model that describes how changes in Notch signal production versus degradation differentially impact cellular outcomes that require long versus short signal duration. Altogether, these findings support a ‘bind and discard’ mechanism in which enhancers with specific binding sites promote rapid Cdk8-dependent Notch turnover, and thereby reduce Notch-dependent transcription at other loci and sensitize tissues to gene dose based upon signal duration.