基于转录组的肝豆状核变性调控网络的构建和分析

Construction and analysis of transcriptome-based hepatolenticular degeneration regulatory network

摘要:

本研究旨在利用生物信息学方法构建经铜诱导的ATP7B基因敲除HepG2细胞系的转录调控网络。探讨关键转录因子在肝豆状核变性发生、发展中的潜在作用机制。收集公共基因表达数据库（gene expression omnibus，GEO）中包含野生型、ATP7B基因敲除型、铜诱导的野生型和铜诱导的ATP7B基因敲除型HepG2细胞系数据。筛选由铜诱导产生的差异表达基因（differentially expressed genes，DEGs）后进行基因本体论（gene ontology，GO）、京都基因和基因组百科全书（Kyoto encyclopedia of genes and genomes，KEGG）富集分析。基于蛋白相互作用网络，识别疾病关键基因和功能模块，并对关键功能模块中的基因进行富集分析。最后，构建转录调控网络，筛选核心转录因子。共筛选出1 034个差异表达基因，其中上调525个，下调509个。上、下调关键功能模块分别包括了3 785个和3 931个基因。关键功能模块中的基因主要定位于细胞-基质连接、染色体、剪接复合体、核糖体等区域，共同参与了mRNA加工、组蛋白修饰、RNA剪切、DNA代谢调节、蛋白磷酸化等生物学过程，且与转录共调控活性、DNA转录因子结合、泛素样蛋白连接酶结合等分子功能相关。KEGG分析表明功能模块中的基因显著富集的通路包括乙型肝炎、有丝分裂原活化蛋白激酶（mitogen-activated protein kinase，MAPK）信号通路、细胞衰老和凋亡、神经营养信号通路和神经变性途径等。肝豆状核变性转录调控网络包括11个差异表达转录因子和96个差异表达基因，其中U2AF1、NFRKB、FUS、MAX、SRSF1、CEBPA和RXRA为核心差异表达转录因子。该研究为肝豆状核变性转录调控相关分子的生物学功能研究提供了重要的参考依据。

Abstract:

A transcriptional regulatory network for wild-type and ATP7B-knockout HepG2 cells exposed to copper was constructed by bioinformatics methods to explore the potential mechanism of key transcription factors in the pathogenesis of hepatolenticular degeneration. The differentially expressed genes (DEGs) for wild-type and ATP7B-knockout HepG2 cell lines without copper and exposed to copper were collected from the gene expression omnibus (GEO) database. Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis were performed for DEGs induced by copper. The key functional modules and genes were identified based on the protein-protein interaction (PPI) network. Moreover, the enrichment analysis of genes in functional modules was performed. Finally, a transcriptional regulatory network was constructed to screen the core transcription factors. A total of 1 034 genes, including 509 down-regulated genes and 525 up-regulated genes, were selected as DEGs. The up-regulated and down-regulated functional modules based on PPI network included 3 785 and 3 931 genes, respectively. Genes in key functional modules were enriched in cell-substrate junction, chromosomal region, spliceosomal complex and ribosome. They were involved in mRNA processing, histone modification, RNA splicing, regulation of DNA metabolic process, protein phosphorylation and other biological processes. Moreover, they were correlated to transcriptional coregulator activity, DNA-binding transcription factor binding, ubiquitin-like protein ligase binding and other molecular functions. KEGG analysis showed that genes in key functional modules were significantly enriched in hepatitis B, MAPK signaling pathway, cellular senescence and apoptosis, neurotrophin signaling pathway and pathways of neurodegeneration-multiple diseases. The transcriptional regulatory network contained 11 differentially expressed transcription factors and 96 DEGs. Among them, U2AF1, NFRKB, FUS, MAX, SRSF1, CEBPA and RXRA were the core transcription factors, which may facilitate the study of the biological function of relevant molecules in transcriptional regulation of hepatolenticular degeneration.