Zhao Ziyi, Dai Xuantong, Jiang Gengru, Lin Fujun
Renal Division, Department of Internal Medicine, Xin Hua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Centre for Rare Disease, Shanghai, China.
J Am Soc Nephrol. 2025 May 1;36(5):798-811. doi: 10.1681/ASN.0000000600. Epub 2025 Jan 7.
Deficits in nephron numbers are associated with higher risk of adult-onset kidney disease seen in congenital anomalies of the kidney and urinary tract. Mouse model experiments suggested that absent, small, or homeotic 2-like was vital for kidney development by activating cell cycle genes through histone methylation. Our findings identified absent, small, or homeotic 2-like–regulated genes as a potential target for treating congenital anomalies of the kidney and urinary tract.
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 CKD later in life. Prior work has implicated histone modifications in regulating kidney lineage–specific gene transcription and nephron endowment. Our earlier study suggested that absent, small, or homeotic 2-like (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.
To investigate the role of ASH2L in nephron development, we inactivated specifically in nephron progenitor cells by crossing -e(Kozak-GFPCre-Wpre-polyA)1 mice with mice. We used 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 culture explants.
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-/suppressor of mothers against decapentaplegic signaling pathway partially rescued the dysplastic phenotype of the mutants.
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.
肾单位数量不足与先天性肾脏和尿路异常中所见的成人期肾病高风险相关。小鼠模型实验表明，无、小或同源异型2样蛋白（ASH2L）通过组蛋白甲基化激活细胞周期基因，对肾脏发育至关重要。我们的研究结果确定ASH2L调控的基因是治疗先天性肾脏和尿路异常的潜在靶点。
许多先天性肾脏和尿路异常涉及肾单位数量不足，这与晚年患高血压和慢性肾脏病的风险较高有关。先前的研究表明组蛋白修饰在调节肾系特异性基因转录和肾单位数量方面起作用。我们早期的研究表明，H3K4甲基转移酶复合物的核心亚基无、小或同源异型2样蛋白（ASH2L）在哺乳动物肾脏发育过程中的输尿管芽形态发生中起作用。然而，ASH2L在肾单位形成中的潜在作用仍是一个悬而未决的问题。
为了研究ASH2L在肾单位发育中的作用，我们通过将-e(Kozak-GFPCre-Wpre-polyA)1小鼠与小鼠杂交，在肾单位祖细胞中特异性地使ASH2L失活。我们使用RNA测序结合靶向切割和标签化测序来筛选基因和表观基因组变化，并通过对培养外植体进行的挽救实验进一步验证。
在肾单位祖细胞中使ASH2L失活会破坏控制肾单位祖细胞干性、分化和细胞周期的基因启动子处的H3K4三甲基化建立，抑制它们通过细胞周期的进程以及分化为形成肾单位所需的上皮细胞类型。抑制TGF-β/抗五体不全信号通路的母亲抑制因子部分挽救了突变体的发育异常表型。
ASH2L介导的H3K4甲基化被确定为肾脏发育的一种新型表观遗传调节因子。ASH2L表达下调或H3K4三甲基化可能与先天性肾脏和尿路异常有关。
