Versatile SMAD2 and SMAD3 epitope-tagged mouse models for genome-wide profiling of TGFβ superfamily signaling: uncovering novel GDF9-SMAD2/3 target genes

Transforming growth factor β (TGFβ) signaling pathways are integral for a plethora of biological processes. SMAD2 and SMAD3 are the principal transcriptional effectors of TGFβ superfamily ligands, yet quantitative, genome-wide mapping of their DNA-associated complexes under physiological contexts has remained limited due to the lack of specific, robust models. Here, we generated two versatile epitope-tagged mouse models in which endogenous SMAD2 and SMAD3 proteins are globally tagged with HA and PA, respectively. To demonstrate the broad application of our models, we evaluated our lines in ovarian biology. By integrating genomic and transcriptomic analyses, we identified direct genes induced by the GDF9-SMAD2/3 axis and discovered gene sets suppressed by this signaling cascade, highlighting a previously underappreciated role of GDF9 in attenuating competing pathways to ensure proper ovarian granulosa cell fate transitions. Together, these epitope-tagged SMAD mouse models provide extensive, applicable in vivo genetic toolkits for tissue-specific dissection of TGFβ family signaling.