GATA2 is an essential transcription factor for epididymal development

Allyssa Fogarty^1,2, Shuai Jia¹, Fei Zhao^1,2 

 ¹Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA

²Comparative Biomedical Sciences Graduate Program, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, US


Abstract Text:

Androgens are known to drive the morphogenesis and differentiation of the Wolffian duct into a highly coiled epididymis, an organ crucial organ for sperm transport, maturation, and storage. This developmental process depends upon interactions between Wolffian duct epithelium and its surrounding mesenchyme. Here, we discovered that the deletion of the mesenchymal transcription factor GATA2 resulted in the defective coiling of the epididymis in the corpus and caudal regions in mice at birth. The loss of epididymal characteristic coiling was accompanied by the reduced expression of its mesenchymal marker ITGA4/Itga4. While Wolffian duct coiling has been linked predominantly with the androgen signaling mediated by androgen receptor (AR), we observed no abnormalities in the testicular morphology or androgen production, and no change in AR/Ar expression in the Wolffian ducts. To conclusively rule out the androgen signaling deficiency as the cause of the phenotype, we supplemented cultured Wolffian ducts with the potent and non-aromatizable androgen, dihydrotestosterone (DHT). However, DHT at the established dose was unable to restore epididymal coiling. These results collectively demonstrated that the defective epididymal coiling in the absence of mesenchymal Gata2 is not due to deficient androgen signaling. Our gene expression comparison between control and Gata2 conditional knockout tissues using bulk RNA-seq and RNAscope revealed the downregulation of Inhba (Inhibin βA), a mesenchyme-secreted factor known to promote epithelial proliferation and govern epididymal coiling. ReducedInhba expression corresponded with a lower percentage of Ki67+ proliferating cells in the epithelium in the absence of mesenchymal Gata2. These results indicate that Inhba is a potential downstream effector of mesenchymal GATA2 in promoting epithelial proliferation during epididymal coiling. The epididymal defects in the absence of mesenchymal Gata2 persisted into adulthood, with the corpus and caudal regions remaining uncoiled and displaying abnormal stratification of their epithelia. The epididymal lumen showed less sperm and excessive extracellular matrix and blood cell accumulation, indicating an unfavorable environment for sperm maturation and storage. In conclusion, our study demonstrates the androgen-independent role of mesenchymal GATA2 in promoting epididymal development, possibly through the induction of Inhba. The persistence of epididymal defects into adulthood supports the hypothesis of fetal origins of adult reproductive diseases and underscores the importance of proper fetal development in male reproduction.