Motor neurons with limb-innervating character in the cervical spinal cord are sculpted by apoptosis based on the Hox code in chick embryo

Motor neurons with limb-innervating character in the cervical spinal cord are sculpted by apoptosis based on the Hox code in chick embryo
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DOI：
10.1242/dev.158873
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发表时间：
2017-12-15
期刊：
DEVELOPMENT
影响因子：
4.6
通讯作者：
Yaginuma, Hiroyuki
Yaginuma, Hiroyuki
中科院分区：
生物学2区
文献类型：
--
作者：
Mukaigasa, Katsuki;Sakuma, Chie;Yaginuma, Hiroyuki

文献摘要

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在发育中的鸡胚中，非肢体神经支配的颈脊髓中的某些运动神经元 (MN) 在胚胎第 4 天和第 5 天之间发生凋亡。然而，这些凋亡 MN 的特征仍不清楚。在这里，通过检查正常或凋亡抑制鸡胚中细胞凋亡和 MN 亚型标记物表达的时空分布，我们发现该细胞凋亡群体可通过 Foxp1 表达来区分。当细胞凋亡受到抑制时，Foxp1(+) MNs 存活并表现出侧向运动柱 (LMC) 神经元的特征，属于肢体神经亚型，表明颈部 Foxp1(+) MNs 是 LMC 的吻端延续。 Foxp1 的敲低和错误表达并不影响细胞凋亡进程，但揭示了 Foxp1 在赋予宫颈 MN LMC 身份方面的作用。此外，通常在臂区表达的Hox基因的异位表达可防止细胞凋亡，并将Foxp1(+) MN引导至颈部水平的LMC神经元。这些结果表明，颈髓细胞凋亡在塑造 Foxp1(+) MN 向 LMC 神经元的塑造过程中发挥着重要作用，具体取决于 Hox 的表达模式。
In the developing chick embryo, a certain population of motor neurons (MNs) in the non-limb-innervating cervical spinal cord undergoes apoptosis between embryonic days 4 and 5. However, the characteristics of these apoptotic MNs remain undefined. Here, by examining the spatiotemporal profiles of apoptosis and MN subtype marker expression in normal or apoptosis-inhibited chick embryos, we found that this apoptotic population is distinguishable by Foxp1 expression. When apoptosis was inhibited, the Foxp1(+) MNs survived and showed characteristics of lateral motor column (LMC) neurons, which are of a limb-innervating subtype, suggesting that cervical Foxp1(+) MNs are the rostral continuation of the LMC. Knockdown and misexpression of Foxp1 did not affect apoptosis progression, but revealed the role of Foxp1 in conferring LMC identity on the cervical MNs. Furthermore, ectopic expression of Hox genes that are normally expressed in the brachial region prevented apoptosis, and directed Foxp1(+) MNs to LMC neurons at the cervical level. These results indicate that apoptosis in the cervical spinal cord plays a role in sculpting Foxp1(+) MNs committed to LMC neurons, depending on the Hox expression pattern.