Profiles of gene expression and alternative splicing in K562 cells exposed to 2 mM sodium valproate for 12 hours assessed using exon array

To investigate the effect of valproate (VPA) treatment on K562 cell line, the growth and survival of the K562 cell line were investigated using the Annexin V/PI dual staining method, and global profiles of gene expression and alternative splicing in K562 cells were assessed using exon microarray. A significant increase in cell apoptosis was observed in valproate exposed K562 cells using flow cytometry. A total of 628 transcripts were identified as being significantly differentially expressed. The number of genes demonstrating increased expression levels was greater than the number of genes demonstrating decreased expression levels (445 genes vs. 183 genes, respectively). The significant enrichment analysis of GO terms for the differentially expressed genes revealed that these genes are involved in many important biological processes such as apoptosis. Six of observed differentially expressed genes that might be involved in apoptosis were selected to undergo qRT-PCR validation. In total, 198 candidates of alternative splicing variants were identified. Among them, three alternative splicing events were selected for validation, and CBLC and TBX1 were confirmed as alternative splicing by semi-nested PCR. In conclusion, valproate exposure facilitated cell apoptosis, altered mRNA expression and alternative splicing events in the K562 cell line. Gene expression/alternative splicing in K562 cell line were measured after exposure to 2 mM valproate for 12 hours or left untreated as a control using exon array.

为探究丙戊酸（valproate, VPA）处理对K562细胞系的影响，本研究采用膜联蛋白V/碘化丙啶（Annexin V/PI）双染色法检测K562细胞系的生长与存活状态，并通过外显子微阵列（exon microarray）分析K562细胞的全基因组基因表达与可变剪接整体图谱。通过流式细胞术观察发现，丙戊酸处理后的K562细胞凋亡率显著升高。最终共鉴定得到628个显著差异表达转录本，其中表达水平上调的基因共445个，多于表达水平下调的183个。对差异表达基因进行基因本体（Gene Ontology, GO）功能富集分析显示，这些基因参与了凋亡等诸多重要生物学过程。本研究选取6个可能参与凋亡过程的差异表达基因进行实时荧光定量PCR（qRT-PCR）验证。共鉴定得到198个可变剪接变体候选靶点，从中选取3个可变剪接事件开展验证，最终通过半巢式PCR（semi-nested PCR）证实CBLC与TBX1发生了可变剪接。综上，丙戊酸暴露可促进K562细胞凋亡，改变其mRNA表达模式与可变剪接事件。本数据集通过外显子芯片（exon array）检测了经2 mM丙戊酸处理12小时的K562细胞，以及未做处理的对照组细胞的基因表达与可变剪接水平。