蛋白质代谢通路对鸡雄性生殖细胞分化的调控

【目的】探究蛋白质代谢在鸡雄性生殖细胞分化过程中的作用机制,为完善鸡胚胎干细胞(embryonic stem cell,ESC)体外向雄性生殖细胞诱导分化体系研究提供依据。【方法】采用流式分选的方法获取高纯度的ESC、原始生殖细胞(primordial germ cells,PGCs)和精原干细胞(spermatogonia stem cell,SSCs),分别提取细胞的总RNA,采用RNA-Seq方法对3种细胞的转录本进行深度测序,然后进行WEGO(web gene ontology)和KEGG(kyoto encyclopedia of genes and genomes)通路富集分析,筛选出鸡雄性生殖细胞分化过程中参与蛋白质代谢的关键通路及其关键基因,RT-q PCR(Real time Quantitative PCR)检测部分关键差异基因的表达变化,并与RNA-Seq(RNA sequencing)结果进行比较分析,同时分别从体内和体外水平对关键基因NOS2进行抑制,观察各分组不同天数的细胞形态变化及检测NOS2和C-kit、Cvh、Stra8、Dazl、integrinα6和integrinβ1等生殖标记基因表达变化情况。【结果】在雄性生殖细胞分化的整个阶段,有697个差异基因参与生物代谢,显著富集于精氨酸-脯氨酸代谢通路、酪氨酸代谢通路以及色氨酸代谢通路,在这3条通路上筛选出NOS2、FAH和IDO等关键性基因,这些基因的在ESCs向SSCs分化过程中表达变化趋势与其在RNA-Seq中的结果一致。体内抑制NOS2基因后,NOS2及C-kit、Cvh、Stra8、Dazl、integrinα6和integrinβ1等生殖标记基因在空白组和对照组之间无显著性的差异,而在抑制剂组中,NOS2及C-kit、Cvh、Stra8、Dazl、integrinα6和integrinβ1等生殖标记基因的m RNA表达量均出现了降低;而体外抑制NOS2基因后,对照组中的ESCs在2、4、6、8和10d内细胞不断增殖,但是未出现类胚体;RA诱导组中,2d出现小的类胚体,4d类胚体增大,且数量增多,6d类胚体边缘开始出现破裂,8d类胚体解体,10d出现类精原样细胞;抑制剂组中,ESCs在2、4、6、8和10d内无类胚体出现,且相较于对照组细胞增殖缓慢;RA+抑制剂组中,2和4d内无类胚体出现,细胞增殖缓慢,6d出现小的类胚体,8d类胚体数量少量增多,且体积稍显增大,10d类胚体开始裂解。并且经过抑制剂的抑制后,NOS2及C-kit、Cvh、Stra8、Dazl、integrinα6和integrinβ1等生殖标记基因的表达量在RA诱导组、抑制剂组和RA+抑制剂组中相对于对照组均呈显著性或极显著性的下调趋势。【结论】基于RNA-Seq技术及生物信息学方法筛选出ESCs向雄性生殖细胞分化过程中精氨酸-脯氨酸代谢通路及关键基因NOS2的基础上,通过对NOS2基因在鸡体内和体外的抑制,发现NOS2在被抑制后,ESCs向雄性生殖细胞分化的过程受到抑制。说明了精氨酸-脯氨酸代谢通路及关键基因NOS2对ESCs向雄性生殖细胞分化过程中起到重要的调节作用。

Regulatory Study of Protein Metabolism During the Differentiation Process of Chicken Male Germ Cells

【Objective】 The aim of this study was to explore the regulatory mechanism of protein metabolism during the differentiation process of chicken male germ cells and provide a basis for improving the induction system of chicken embryonic stem cells (ESCs) differentiation to male germ cells in vitro. 【Method】RNA sequencing was performed using FACS-sorted cells from ESCs, PGCs(primordial germ cells) and SSCs(spermatogonial stem cells), and enrichment analysis, WEGO (Web Gene ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes), were carried out to find out the relevant pathways and the key genes, the expression level of which was analyzed by qRT-PCR. Moreover, NOS2 both in vitro and in vivo with NOS2 inhibitor was inhibited, and the morphologic changes of ESCs were observed and the mRNA expressions of NOS2 and other germ genes, C-kit, Cvh, Stra8, Dazl, integrin α6 and integrin β1 were detectedin different groups and in different days with RT-qPCR. 【Result】 Final results showed that 697 differentially expressed genes were involved in biological metabolism and significantly enriched in arginine-proline metabolic pathway, tyrosine metabolic pathway and tryptophan metabolic pathway and screened some key genes, like NOS2, FAH and IDO. It was found that the expression trends of NOS2, FAH and IDO were the same as that of RNA-Seq. In inhibitory experiment in vivo, the mRNA expression of NOS2, C-kit, Cvh, Stra8, Dazl, integrin α6 and integrin β1 between blank group and control group showed no significant difference. However, in inhibited group, NOS2, C-kit, Cvh, Stra8, Dazl, integrin α6 and integrin β1 expressions were down-regulated inordinately. Moreover, in inhibitory experiment in vitro, ESCs always proliferated on the 2, 4, 6, 8 and 10d, but disappeared the embryonic bodies in the control group. In induced group, small embryonic bodies appeared on the 2d and became bigger and increased on the 4d. Embryonic bodies started to burst in edges on the 6d, break up on the 8d and appeared spermatogonia-like cells. In inhibited group, no embryonic body appeared in the whole process and ESCs proliferated more slow than the control group. In induced-inhibited group, no embryonic body appeared on the 2d and 4d and ESCs proliferated slowly. Small embryonic bodies appeared on the 6d and the number and volume increased slightly on the 8d. On the 10d, the embryonic bodies started to break up. In vitro, NOS2, C-kit, Cvh, Stra8, Dazl, integrin α6 and integrin β1 expressions in induced group, inhibited group and induced-inhibited group were significantly down-regulated compared with the control group. 【Conclusion】In this study, based on the screening of arginine-proline metabolic pathway and NOS2 with RNA-Seq and Bioinformatics, it was found that the process of ESCs differentiation to male germ cell was inhibited after the inhibition of NOS2，which suggested that arginine-proline metabolic pathway and NOS2 has an important regulatory effect on differentiation of ESCs to male germ cells.