Hatakeyama Jun, Kageyama Ryoichiro
Institute for Virus Research, Kyoto University, Shogoin-Kawahara, Sakyo-ku, Kyoto 606-8507, Japan.
Semin Cell Dev Biol. 2004 Feb;15(1):83-9. doi: 10.1016/j.semcdb.2003.09.005.
Retinal development is controlled antagonistically by multiple basic helix-loop-helix (bHLH) transcriptional activators and repressors. bHLH repressors suppress bHLH activators and promote maintenance of progenitors and generation of glial cells. In contrast, bHLH activators override activities of bHLH repressors and promote neuronal differentiation. However, bHLH activators alone are not sufficient but homeodomain factors are additionally required for neuronal subtype specification. It is likely that homeodomain factors regulate the layer specificity but not the neuronal fate while bHLH activators determine the neuronal fate within the homedomain factor-specified layers. Thus, combinations of proper bHLH and homeodomain factors are required for neuronal subtype specification.
视网膜发育受多种碱性螺旋-环-螺旋（bHLH）转录激活因子和抑制因子的拮抗调控。bHLH抑制因子抑制bHLH激活因子，并促进祖细胞的维持和神经胶质细胞的生成。相反，bHLH激活因子则会抑制bHLH抑制因子的活性，并促进神经元分化。然而，仅bHLH激活因子并不足以实现这一过程，神经元亚型特异性的确定还需要同源结构域因子。同源结构域因子可能调控层特异性，但不决定神经元命运，而bHLH激活因子则在同源结构域因子指定的层内决定神经元命运。因此，神经元亚型特异性的确定需要合适的bHLH和同源结构域因子的组合。
