Diabetes susceptibility in the Canadian Oji-Cree population is moderated by abnormal mRNA processing of HNF1A G319S transcripts
Diabetes susceptibility in the Canadian Oji-Cree population is moderated by abnormal mRNA processing of HNF1A G319S transcripts
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DOI：
10.2337/db07-1633
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发表时间：
2008-07-01
期刊：
影响因子：
7.7
通讯作者：
Ellard, Sian
中科院分区：
文献类型：
--
作者：
Harries, Lorna W.;Sloman, Melissa J.;Ellard, Sian
G319 S HNF 1A valiant与加拿大Oji-Cree人群2型糖尿病风险增加相关。我们假设外显子4的3'端的变异位点可能影响剪接和mRNA转录的特征，以研究这种易感性的突变机制，从而对diabetes.RESEARCH设计和方法，我们建立了淋巴母细胞样细胞系从G319 S纯合子和控制。通过RT-PCR产物的序列分析和使用实时PCR的定量来表征细胞系和胰腺组织中的HNF 1A转录物。用放线菌酮对mRNA监测的敏感性进行了研究。在纯合的G319 S细胞系中，G319 S全长mRNA占mRNA转录本的24%。与对照细胞系（33%）和人胰腺组织（17%）相比，一种缺乏外显子4末端12个碱基的新型亚型上调（55%的mRNA转录本）。两个异常的成绩单只存在于G319 S细胞系包括提前终止密码子作为一个结果，包括7个核苷酸从内含子4或外显子8的缺失。放线菌酮治疗增加了这两个transcriptions.CONCLUSIONS-The G319 S valiant的结果在生产两个异常的转录和正常剪接产物的相对平衡的改变的水平。预计这将导致总HNF 1A转录水平的降低，但G319 S纯合子中残留的肝细胞核因子-lot蛋白活性仍可能达到正常水平的66%。异常剪接和G319 S蛋白活性降低的组合可以解释糖尿病易感性。
OBJECTIVE-The G319S HNF1A valiant is associated with an increased risk of type 2 diabetes in the Canadian Oji-Cree population. We hypothesized that the variant site at the 3' end of exon 4 might influence splicing and characterized mRNA transcripts to investigate the mutational mechanism underlying this susceptibility to diabetes.RESEARCH DESIGN AND METHODS-We established lymphoblastoid cell lines from a G319S homozygote and controls. HNF1A transcripts were characterized in the cell lines and pancreatic tissue by sequence analysis of RT-PCR products and quantification using real-time PCR. Susceptibility to mRNA surveillance was investigated using cycloheximide.RESULTS-Full-length G319S mRNA accounted for 24% of mRNA transcripts in the homozygous G319S cell line. A novel isoform lacking the terminal 12 bases of exon 4 was upregulated (55% of mRNA transcripts) compared with control cell lines (33%) and human pancreatic tissue (17%). Two abnormal transcripts present only in the G319S cell line included premature termination codons as a result of the inclusion of seven nucleotides from intron 4 or the deletion of exon 8. Cycloheximide treatment increased the levels of both transcripts.CONCLUSIONS-The G319S valiant results in the production of two abnormal transcripts and an alteration in the relative balance of normal splicing products. This is predicted to lead to a reduction in total HNF1A transcript levels, but residual hepatocyte nuclear factor-lot protein activity in G319S homozygotes may still reach up to 66% of normal levels. A combination of abnormal splicing and reduced activity of the G319S protein may explain the diabetes susceptibility.