Shiva Abbasi / Biology / Faculty Mentor: Theodora Koromila
Early heart development requires precise transcriptional regulation to coordinate cell fate decisions during embryogenesis. However, the mechanisms governing the transition from early patterning to cardiac gene activation remain poorly understood. Using Drosophilaembryos as our model, we investigate how Odd-paired (Opa/ZIC3) and Suppressor of Hairless (Su(H)/RBPJ) regulate cardiac gene expression before gastrulation. Our data reveal that Opa functions as a key activator of early cardiac genes, while Su(H) initially acts as a repressor, restricting expression to specific developmental windows. In situ hybridization and quantitative imaging of odd expression show that Opa loss leads to expedited expression of odd right before gastrulation, while Su(H) knockdown results in increased odd expression levels. In the absence of Opa, slp1 showed delayed expression of the 14-stripes before gastrulation. Live imaging of enhancer dynamics further supports a model where Su(H) prevents early activation of cardiac genes, with Opa counteracting this repression at the appropriate stage. By integrating chromatin occupancy and transcriptional readouts with super-resolution imaging, we define a stage-specific regulatory switch that ensures precise timing of cardiac gene expression. These findings highlight a previously unrecognized interplay between Opa and Su(H) in early heart development and provide new insights into the regulatory logic of cardiac gene networks. Funding: STARs program UTA
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