Li Jianzhen, Wu Peng, Liu Yun, Wang Deshou, Cheng Christopher H K
College of Life Sciences, Northwest Normal University, Lanzhou, China.
School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China.
Gene Expr Patterns. 2014 Jul;15(2):104-11. doi: 10.1016/j.gep.2014.05.006. Epub 2014 Jun 11.
The insulin-like growth factor (Igf) family is an evolutionarily conserved system essential for normal growth and development in vertebrates. Unlike mammals, four distinct Igf ligands (Igf1, Igf2a, Igf2b and Igf3) and two Igf type 1 receptors (Igf1ra and Igf1rb) are present in zebrafish. However, the localization of these multiple ligands and receptors especially the recently discovered igf3 during early development of zebrafish is poorly understood. In this study, detailed expression patterns of these components of the Igf system during embryogenesis of zebrafish were analyzed. It was found that igf1 is specifically expressed in the trigeminal ganglia region from 18 hpf to 72 hpf, while igf2a is restricted to the caudal regions of the notochord from 14 hpf to 18 hpf as well as in the midbrain, dorsal hind brain and otic vesicle at 24 hpf. On the other hand, igf2a is highly expressed in the midbrain and pharyngeal arch region at 48 hpf, followed by its appearance in the liver and brain at 72 hpf, while igf2b is restricted to the floor plate and hypochord from 12 hpf to 18 hpf, and strong expression is also detected in the midbrain and dorsal hind brain at 24 hpf. The teleost specific igf3 is highly expressed in the pharyngeal arch region before 24 hpf, but is then restricted to the sternohyoideus after 48 hpf. The receptor subtype igf1ra is ubiquitously expressed before 24 hpf but is confined to the brain at 72 hpf. However, igf1rb is widely expressed before 10 hpf, but is more confined to the brain region at 24 hpf and 72 hpf. This dynamic temporal-spatial expression during embryogenesis of zebrafish, together with the unique and overlapping expression patterns of the Igf ligands and receptors suggest the coordination of the divergent functions of the Igf system during early development in zebrafish.
胰岛素样生长因子（Igf）家族是脊椎动物正常生长和发育所必需的一个进化上保守的系统。与哺乳动物不同，斑马鱼中存在四种不同的Igf配体（Igf1、Igf2a、Igf2b和Igf3）和两种Igf1型受体（Igf1ra和Igf1rb）。然而，这些多种配体和受体的定位，尤其是最近发现的igf3在斑马鱼早期发育过程中的定位，目前了解甚少。在本研究中，分析了斑马鱼胚胎发育过程中Igf系统这些成分的详细表达模式。发现igf1在受精后18小时至72小时在三叉神经节区域特异性表达，而igf2a在受精后14小时至18小时局限于脊索的尾部区域，在24小时时位于中脑、后脑背侧和耳泡。另一方面，igf2a在48小时时在中脑和咽弓区域高表达，随后在72小时时出现在肝脏和大脑中，而igf2b在受精后12小时至18小时局限于底板和下索，在24小时时在中脑和后脑背侧也检测到强表达。硬骨鱼特有的igf3在24小时前在咽弓区域高表达，但在48小时后局限于胸骨舌骨肌。受体亚型igf1ra在24小时前普遍表达，但在72小时时局限于大脑。然而，igf1rb在10小时前广泛表达，但在24小时和72小时时更局限于脑区。斑马鱼胚胎发育过程中的这种动态时空表达，以及Igf配体和受体独特且重叠的表达模式，表明Igf系统在斑马鱼早期发育过程中不同功能的协调。
