Salami Farimah, Qiao Shuhong, Homayouni Ramin
Department of Biological Sciences, University of Memphis, Memphis, TN, United States.
Department of Biological Sciences, University of Memphis, Memphis, TN, United States.
Gene. 2015 Aug 15;568(1):19-24. doi: 10.1016/j.gene.2015.05.012. Epub 2015 May 7.
Dab2ip (DOC-2/DAB2 interacting protein) is a RasGAP protein which shows a growth-inhibitory effect in human prostate cancer cell lines. Recent studies have shown that Dab2ip also plays an important role in regulating dendrite development and neuronal migration during brain development. In this study, we provide a more complete description of the mouse Dab2ip (mDab2ip) gene locus and examined DNA methylation and expression of Dab2ip during cerebellar development. Analysis of cDNA sequences in public databases revealed a total of 20 possible exons for mDab2ip gene, spanning over 172kb. Using Cap Analysis of Gene Expression (CAGE) data available through FANTOM5 project, we deduced five different transcription start sites for mDab2ip. Here, we characterized three different mDab2ip transcript variants beginning with exon 1. These transcripts varied by the presence or absence of exons 3 and 5, which encode a putative nuclear localization signal and the N-terminal region of a PH-domain, respectively. The 5' region of the mDab2ip gene contains three putative CpG islands (CpG131, CpG54, and CpG85). Interestingly, CpG54 and CpG85 are localized on exons 3 and 5. Bisulfate DNA sequencing showed that methylation level of CpG54 remained constant whereas methylation of CpG85 increased during cerebellar development. Real-time PCR analysis showed that the proportion of PH-domain containing mDab2ip transcripts increased during cerebellar development, in correlation with the increase in CpG85 methylation. These data suggest that site-specific methylation of mDab2ip gene during cerebellar development may play a role in inclusion of exon 5, resulting in a Dab2ip transcript variant that encodes a full pleckstrin homology (PH) domain.
Dab2ip（DOC-2/DAB2相互作用蛋白）是一种RasGAP蛋白，在人前列腺癌细胞系中表现出生长抑制作用。最近的研究表明，Dab2ip在大脑发育过程中调节树突发育和神经元迁移方面也起着重要作用。在本研究中，我们对小鼠Dab2ip（mDab2ip）基因座进行了更完整的描述，并研究了小脑发育过程中Dab2ip的DNA甲基化和表达情况。对公共数据库中cDNA序列的分析揭示了mDab2ip基因共有20个可能的外显子，跨越超过172kb。利用通过FANTOM5项目获得的基因表达帽分析（CAGE）数据，我们推断出mDab2ip有五个不同的转录起始位点。在这里，我们鉴定了三种不同的以第1外显子开始的mDab2ip转录变体。这些转录本因第3和第5外显子的存在与否而有所不同，第3和第5外显子分别编码一个假定的核定位信号和一个PH结构域的N端区域。mDab2ip基因的5'区域包含三个假定的CpG岛（CpG131、CpG54和CpG85）。有趣的是，CpG54和CpG85位于第3和第5外显子上。亚硫酸氢盐DNA测序表明，CpG54的甲基化水平保持恒定，而CpG85的甲基化在小脑发育过程中增加。实时PCR分析表明，在小脑发育过程中，含有PH结构域的mDab2ip转录本的比例增加，与CpG85甲基化的增加相关。这些数据表明，小脑发育过程中mDab2ip基因的位点特异性甲基化可能在第5外显子的包含中起作用，从而产生一种编码完整普列克底物蛋白同源（PH）结构域的Dab2ip转录变体。
