In vivo replacement of damaged bladder urothelium by Wolffian duct epithelial cells

The bladder's remarkable regenerative capacity in response to injury had been thought to reside exclusively in its basal and intermediate cells. While examining consequences of DNA methyltransferase 1 (Dnmt1) inactivation in mouse embryonic bladder epithelium, we made the surprising discovery that Wolffian duct epithelial cells also support bladder regeneration. Conditional inactivation of Dnmt1 in mouse urethral and bladder epithelium triggered widespread apoptosis, depleted basal and intermediate bladder cells and disrupted Uroplakin protein expression. These events coincided with recruitment of Wolffian duct epithelial cells into Dnmt1 mutant urethra and bladder where they were reprogrammed to express bladder markers including FOXA1, Keratin 5, P63 and Uroplakin. This is the first evidence that Wolffian duct epithelial cells can be summoned in vivo to replace damaged bladder epithelium and function as a cell reservoir for bladder regeneration. Bladder urothelium were separated from stroma tissues and profiled by RNA-seq. Total 14 samples, from E15.5 embryos with three different genotypes (including conditional Dnmt1 KO in the bladder urothelium) detailed in sample list characteristics: genotypes此前学界曾认为，膀胱在损伤后展现出的卓越再生能力，仅源自其基底细胞与中间细胞。我们在探究小鼠胚胎膀胱上皮（bladder epithelium）中DNA甲基转移酶1（DNA methyltransferase 1, Dnmt1）失活的影响时，意外发现沃尔夫管上皮细胞（Wolffian duct epithelial cells）同样具备支持膀胱再生的能力。在小鼠尿道与膀胱上皮中条件性失活Dnmt1后，会引发广泛的细胞凋亡，耗竭膀胱基底细胞与中间细胞，并破坏尿路上皮特异性蛋白Uroplakin（Uroplakin）的表达。上述过程伴随沃尔夫管上皮细胞被招募至Dnmt1突变的尿道与膀胱组织中，并在此被重编程，表达FOXA1、角蛋白5（Keratin 5）、P63与Uroplakin等膀胱特异性标志物。本研究首次证实，沃尔夫管上皮细胞可在体内被募集以替代受损的膀胱上皮，并作为细胞储库参与膀胱再生。研究人员将膀胱尿路上皮（bladder urothelium）与间质组织分离，并通过RNA-seq进行表达谱分析。本次研究共纳入14份样本，均取自E15.5时期的胚胎，涵盖三种不同基因型（包括膀胱尿路上皮条件性Dnmt1敲除（conditional Dnmt1 KO）），样本特征与基因型的详细信息详见样本列表。