Background: Many congenital anomalies of the kidney and urinary tract involve deficits in the number of nephrons, which are associated with a higher risk of hypertension and chronic kidney disease later in life. Prior work has implicated histone modifications in regulating kidney lineage-specific gene transcription and nephron endowment. Our earlier study suggested that ASH2L, a core subunit of the H3K4 methyltransferase complex, plays a role in ureteric bud morphogenesis during mammalian kidney development. However, the potential involvement of ASH2L in nephron formation remains an open question.
Methods: To investigate the role of ASH2L in nephron development, we inactivated Ash2l specifically in nephron progenitor cells by crossing Six2-e(Kozak-GFPCre-Wpre-polyA)1 mice with Ash2lfl/fl mice. We utilized RNA sequencing combined with Cleavage Under Targets and Tagmentation sequencing to screen for gene and epigenomic changes, which were further verified by rescue experiments conducted on ex vivo culture explants.
Results: Inactivating ASH2L in nephron progenitor cells disrupted H3K4 trimethylation establishment at promoters of genes controlling nephron progenitor cell stemness, differentiation and cell cycle, inhibiting their progression through the cell cycle and differentiation into epithelial cell types needed to form nephrons. Inhibition of the TGF-β/SMAD signaling pathway partially rescued the dysplastic phenotype of the mutants.
Conclusions: ASH2L-mediated H3K4 methylation was identified as a novel epigenetic regulator of kidney development. Downregulation of ASH2L expression or H3K4 trimethylation may be linked to congenital anomalies of the kidney and urinary tract.
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