Elliott Karen L, Gordy Clayton, Ingvalson Hannah, Holliday Charles, Halyko Jessica, Houston Douglas W, Degnan Bernard M, Fritzsch Bernd
Department of Biology, University of Iowa, Iowa City, IA 52245, USA.
School of Biological Sciences, University of Queensland, Brisbane 4072, Australia.
Int J Mol Sci. 2025 Jun 7;26(12):5487. doi: 10.3390/ijms26125487.
Basic helix-loop-helix (bHLH) transcription factors, such as those in the family, are important in cellular fate determination. The expression of the sponge ortholog of the bHLH gene family, , in previously resulted in the formation of ectodermal ectopic neurons. However, the extent to which these neurons persist through development and the effects on the inner ear and lateral line, which require a critical level and timing of bHLH genes, remains unexplored. To test these long-term effects, we injected various concentrations of mRNA into embryos and assessed neurosensory development at developmental stages coinciding with fully developed neurosensory structures. The expression of mRNA in resulted in a dose-dependent reduction in or loss of ears and the lateral line system without eliminating ectopic neurons. At the lowest concentrations examined, we found that inner ear neurosensory development consisted sometimes of only a few scattered hair cells in a single-layer epithelium. Furthermore, low concentrations of mRNA affected inner ear afferent guidance. Our data suggest that the gene has some anti-neurosensory abilities in frogs and that the overexpression of a single gene may not be sufficient for stable long-term transdifferentiation in cells.
碱性螺旋-环-螺旋（bHLH）转录因子，如该家族中的那些因子，在细胞命运决定中很重要。bHLH基因家族的海绵直系同源基因在之前的研究中，其表达导致了外胚层异位神经元的形成。然而，这些神经元在发育过程中持续存在的程度以及对需要bHLH基因达到关键水平和特定时间的内耳和侧线的影响，仍未得到探索。为了测试这些长期影响，我们将不同浓度的该基因mRNA注射到青蛙胚胎中，并在与完全发育的神经感觉结构相吻合的发育阶段评估神经感觉发育情况。该基因mRNA在青蛙中的表达导致耳朵和侧线系统出现剂量依赖性的减少或缺失，同时并未消除异位神经元。在检测的最低浓度下，我们发现内耳神经感觉发育有时仅由单层上皮中的少数散在毛细胞组成。此外，低浓度的该基因mRNA影响内耳传入神经的导向。我们的数据表明，该基因在青蛙中具有一些抗神经感觉的能力，并且单个基因的过表达可能不足以使细胞实现稳定的长期转分化。
