Drosha in mesangial cells regulates Glomerular Capillary Tufts Formation Through Drosha/Ribosome/Gata3 Axis

CAKUT (congenital anomalies of the kidney and the urinary tract) is one of the most prevalent birth defects, affecting around 1% of newborns. However, the genetic factors underlying the majority of CAKUT are unknown. Drosha, the microRNA-processing ribonuclease, has been reported to regulate the nephric cap meschyme development, and its mutations are implicated in Wilms tumor, a pediatric kidney cancer. Here, we investigated the role of Drosha in mesangial cells and its impact on glomerular capillary tuft formation. Deletion of Drosha in mesangial cells (DroshacKO) disrupted the glomerular capillary tufts formation, leading to dysplastic glomeruli, proteinuria, oliguria, reduced looping of glomerular capillaries and capillary dilation. Drosha-knockdown (KD) in mesangial cells (SV40 MES 13) leads to decreased cell proliferation and reduced Gata3 protein level. Transcriptome analysis by RNA-seq shows decreased level of ribosome protein gene (RPG)s but unaltered mRNA level of major genes affecting kidney development, including Gata3, Pax2, Atn1, Wt1 etc. in Drosha-KD compared to Control SV40 MES13 cells. Further analysis indicates Drosha regulates the translation of Gata3 in mesangial cells via regulating RPG transcription. Our work, for the first time, reveals that Drosha in mesangial cells orchestrates the formation of glomerular capillary tufts by regulating Gata3 translation. It identifies the critical role of DROSHA in nephric development and proposes DROSHA as a novel potential causal gene for CAKUT. [miRNA-Seq] This study investigates the role of DROSHA in microRNA biogenesis using the mouse renal mesangial cell line ME13 sv40. Small RNA sequencing was performed to compare microRNA expression profiles between DROSHA knockdown cells and control cells. The results aim to elucidate how DROSHA depletion alters microRNA expression patterns, which may provide insights into post-transcriptional regulation in renal mesangial cells.