Wu Mingxuan, Jia Gaogan, Liu Yaoqian, Lou Yiyun, Li Yunjie, Xia Mingyu, Li Huawei, Li Wenyan
ENT Institute and Otorhinolaryngology Department of Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China.
Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China.
Proc Natl Acad Sci U S A. 2025 Jan 14;122(2):e2410829122. doi: 10.1073/pnas.2410829122. Epub 2025 Jan 8.
Understanding the role of metabolic processes during inner ear development is essential for identifying targets for hair cell (HC) regeneration, as metabolic choices play a crucial role in cell proliferation and differentiation. Among the metabolic processes, growing evidence shows that glucose metabolism is closely related to organ development. However, the role of glucose metabolism in mammalian inner ear development and HC regeneration remains unclear. In this study, we found that glycolytic metabolism is highly active during mouse and human cochlear prosensory epithelium expansion. Using mouse cochlear organoids, we revealed that glycolytic activity in cochlear nonsensory epithelial cells was predominantly dominated by pyruvate kinase M2 (PKM2). Deletion of PKM2 induced a metabolic switch from glycolysis to oxidative phosphorylation, impairing cochlear organoid formation. Furthermore, conditional loss of PKM2 in cochlear progenitors hindered sensory epithelium morphogenesis, as demonstrated in PKM2 knockout mice. Mechanistically, pyruvate is generated by PKM2 catalysis and then converted into lactate, which then lactylates histone H3, regulating the transcription of key genes for cochlear development. Specifically, accumulated lactate causes histone H3 lactylation at lysine 9 (H3K9la), upregulating the expression of family transcription factors through epigenetic modification. Moreover, overexpression of PKM2 in supporting cells (SCs) triggered metabolism reprogramming and enhanced HC generation in cultured mouse and human cochlear explants. Our findings uncover a molecular mechanism of sensory epithelium formation driven by glycolysis-lactate flow and suggest unique approaches for mammalian HC regeneration.
了解内耳发育过程中代谢过程的作用对于确定毛细胞（HC）再生的靶点至关重要，因为代谢选择在细胞增殖和分化中起着关键作用。在众多代谢过程中，越来越多的证据表明葡萄糖代谢与器官发育密切相关。然而，葡萄糖代谢在哺乳动物内耳发育和HC再生中的作用仍不清楚。在本研究中，我们发现糖酵解代谢在小鼠和人类耳蜗前感觉上皮扩张过程中高度活跃。利用小鼠耳蜗类器官，我们发现耳蜗非感觉上皮细胞中的糖酵解活性主要由丙酮酸激酶M2（PKM2）主导。PKM2的缺失诱导了从糖酵解到氧化磷酸化的代谢转变，损害了耳蜗类器官的形成。此外，如PKM2基因敲除小鼠所示，耳蜗祖细胞中PKM2的条件性缺失阻碍了感觉上皮的形态发生。从机制上讲，丙酮酸由PKM2催化生成，然后转化为乳酸，乳酸随后使组蛋白H3乳酸化，调节耳蜗发育关键基因的转录。具体而言，积累的乳酸导致组蛋白H3在赖氨酸9处乳酸化（H3K9la），通过表观遗传修饰上调家族转录因子的表达。此外，在支持细胞（SCs）中过表达PKM2会引发代谢重编程，并增强培养的小鼠和人类耳蜗外植体中的HC生成。我们的研究结果揭示了由糖酵解-乳酸流驱动的感觉上皮形成的分子机制，并为哺乳动物HC再生提出了独特的方法。
