Jen Y, Manova K, Benezra R
Cell Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10021, USA.
Dev Dyn. 1997 Jan;208(1):92-106. doi: 10.1002/(SICI)1097-0177(199701)208:1<92::AID-AJA9>3.0.CO;2-X.
We have performed a detailed comparative in situ hybridization analysis to examine the patterns of expression of all the members of the Id gene family (Id1-4) during murine gastrulation and neurogenesis. During gastrulation, both Id1 and Id3 are expressed in the tissues derived from the inner cell mass from 5.5 dpc onward, whereas Id2 is expressed in tissues derived from trophoblasts. Id4 expression is absent during this period of development. Embryonic Id1 messages are detected during gastrulation on the proximal side of the embryonic ectoderm, which is the border between the embryo proper and the extraembryonic tissues, and the expression of Id3 is found throughout the entire embryo proper. This unique pattern of expression of the different members of the Id family suggests a nonredundant role for these genes in antagonizing the activity of bHLH transcription factors during very early mouse development. During neurogenesis, the expression of each member of the Id family is present in an unique pattern along the dorsal-ventral axis of the neural tube: In the early stages of spinal cord development, both Id1 and Id2 are expressed in the roof plate, whereas Id3 is expressed both in the roof and the floor plates. As development progresses, the expression of both Id1 and Id3 is detected in the dividing neuroblasts, whereas Id2 and 4 are expressed in presumptive neurons which are undergoing maturation. The expression patterns of all the members of the Id gene family persist throughout the entire CNS, both in the spinal cord and in the brain. In addition, the characteristic expression of Id2 and Id4 in more mature neurons is reiterated both in the PNS and in the neurons of some of the sensory organs. These data suggest that the expression of different subgroups of the Id gene family may have different physiological consequences and thereby contributes in unique ways to specify the differentiation state of neuronal cells during development.
我们进行了详细的比较原位杂交分析，以研究Id基因家族（Id1 - 4）所有成员在小鼠原肠胚形成和神经发生过程中的表达模式。在原肠胚形成期间，从胚胎发育第5.5天起，Id1和Id3在源自内细胞团的组织中表达，而Id2在源自滋养层细胞的组织中表达。在此发育阶段未检测到Id4的表达。在原肠胚形成期间，在胚胎外胚层的近端一侧检测到胚胎Id1信息，该区域是胚胎本体与胚外组织之间的边界，并且在整个胚胎本体中都发现了Id3的表达。Id家族不同成员的这种独特表达模式表明，这些基因在小鼠早期发育过程中拮抗bHLH转录因子的活性方面具有非冗余作用。在神经发生过程中，Id家族每个成员的表达沿神经管的背腹轴以独特模式存在：在脊髓发育的早期阶段，Id1和Id2都在顶板中表达，而Id3在顶板和底板中均有表达。随着发育的进行，在分裂的神经母细胞中检测到Id1和Id3的表达，而Id2和Id4在正在成熟的假定神经元中表达。Id基因家族所有成员的表达模式在整个中枢神经系统（CNS）中持续存在，包括脊髓和大脑。此外，Id2和Id4在更成熟神经元中的特征性表达在周围神经系统（PNS）和一些感觉器官的神经元中都有重复。这些数据表明，Id基因家族不同亚组的表达可能具有不同的生理后果，从而以独特方式有助于在发育过程中确定神经元细胞的分化状态。
