The histone demethylase LSD1 regulates inner ear progenitor differentiation through interactions with Pax2 and the NuRD repressor complex

The histone demethylase LSD1 plays a pivotal role in cellular differentiation, particularly in silencing lineage-specific genes. However, little is known about how LSD1 regulates neurosensory differentiation in the inner ear. Here we show that LSD1 interacts directly with the transcription factor Pax2 to form the NuRD co-repressor complex at the Pax2 target gene loci in a mouse otic neuronal progenitor cell line (VOT-N33). VOT-N33 cells expressing a Pax2-response element reporter were GFP-negative when untreated, but became GFP positive after forced differentiation or treatment with a potent LSD inhibitor. Pharmacological inhibition of LSD1 activity resulted in the enrichment of mono- and di-methylation of H3K4, upregulation of sensory neuronal genes and an increase in the number of sensory neurons in mouse inner ear organoids. Together, these results identify the LSD1/NuRD complex as a previously unrecognized modulator for Pax2-mediated neuronal differentiation in the inner ear.

组蛋白去甲基化酶LSD1（histone demethylase LSD1）在细胞分化过程中发挥关键调控作用，尤其参与谱系特异性基因的沉默。目前学界对于LSD1如何调控内耳神经感觉分化的机制仍知之甚少。本研究发现，在小鼠耳神经元祖细胞系（VOT-N33）中，LSD1可直接与转录因子Pax2结合，在Pax2靶基因位点形成NuRD共抑制复合物。当用携带Pax2应答元件报告基因的载体转染VOT-N33细胞时，未处理的细胞呈绿色荧光蛋白（GFP，green fluorescent protein）阴性；但经诱导分化或强效LSD抑制剂处理后，细胞转为GFP阳性。对LSD1活性进行药物抑制后，可使H3K4单甲基化与二甲基化修饰水平升高，上调感觉神经元基因的表达，并增加小鼠内耳类器官中感觉神经元的数量。综上，本研究证实LSD1/NuRD复合物是此前未被发现的、介导Pax2调控内耳神经元分化的调控因子。