Zuo Qisheng, Zhang Chen, Jin Kai, Jing Jin, Sun Changhua, Ahmed Mahmoud F, Song Jiuzhou, Zhang Yani, Chen Guohong, Li Bichun
1Key Laboratory of Animal Breeding Reproduction and Molecular Design for Jiangsu Province, College of Animal Science and Technology, Yangzhou University, 88 South University Ave, Yangzhou, Jiangsu 225009 People's Republic of China.
4Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, 88 South University Ave, Yangzhou, 225009 Jiangsu People's Republic of China.
Cell Biosci. 2018 Jun 19;8:40. doi: 10.1186/s13578-018-0238-y. eCollection 2018.
Notch signaling is mainly regulated by Notch1 during development of chicken germ stem cells; however, the molecular mechanisms that contribute to generation of these germ stem cells have not been thoroughly investigated.
In our studies, Overexpression of the Notch1 NICD promoted development of the reproductive ridge, but inhibited the formation of seminiferous tubules. The formation efficiency of PGCs in the reproductive ridge following overexpression of NICD (7.5% ± 0.11) was significantly higher than that (4.9% ± 0.17, < 0.05) following inhibition of NICD, While the formation efficiency of spermatogonial stem cells (SSCs) in the testes (12.7% ± 0.08) was significantly lower after NICD overexpression than that after inhibition of NICD (16.3% ± 0.16, < 0.05). Using co-immunoprecipitation, we found that this anomaly stemmed from the reversal of dissociation of the Notch-regulated transcription factor CBF-1/RBP co-suppression complex during the differentiation of PGCs into SSCs. This dissociation of the CBF-1/RBP co-suppressing complex during the differentiation of ESCs into PGCs resulted in the release of HDAC1 and HDAC2 and the recruitment of mastermind-like 1 to form a coactive complex to promote the expression of the downstream transcription suppressor hairy/enhancer of split-1. Dynamic expression of transducin-like enhancer of split 3, TLE4, and C-terminal binding protein 2 during further differentiation of PGCs inhibited the dissociation of the CBF-1/RBP co-suppression complex and inhibited the expression of the downstream genes.
In summary, Notch signaling plays diametrically opposing roles during normal development of chicken PGCs and SSCs, and these functions was determined by the expression of NICD, changes in the CBF-1/RBP complex composition, and histone modification.
在鸡生殖干细胞发育过程中，Notch信号主要由Notch1调控；然而，促成这些生殖干细胞产生的分子机制尚未得到充分研究。
在我们的研究中，Notch1胞内结构域（NICD）的过表达促进了生殖嵴的发育，但抑制了生精小管的形成。NICD过表达后生殖嵴中原始生殖细胞（PGC）的形成效率（7.5%±0.11）显著高于NICD抑制后（4.9%±0.17，<0.05），而NICD过表达后睾丸中精原干细胞（SSC）的形成效率（12.7%±0.08）显著低于NICD抑制后（16.3%±0.16，<0.05）。通过免疫共沉淀，我们发现这种异常源于PGC向SSC分化过程中Notch调节的转录因子CBF-1/RBP共抑制复合物解离的逆转。在胚胎干细胞向PGC分化过程中CBF-1/RBP共抑制复合物的这种解离导致组蛋白去乙酰化酶1（HDAC1）和组蛋白去乙酰化酶2（HDAC2）的释放以及招募类主脑蛋白1形成共激活复合物，以促进下游转录抑制因子毛状/分裂增强子1（hairy/enhancer of split-1）的表达。在PGC进一步分化过程中，转导素样分裂增强子3（TLE4）和C端结合蛋白2的动态表达抑制了CBF-1/RBP共抑制复合物的解离并抑制了下游基因的表达。
总之，Notch信号在鸡PGC和SSC的正常发育过程中发挥着截然相反的作用，并且这些功能由NICD的表达、CBF-1/RBP复合物组成的变化以及组蛋白修饰所决定。
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