Reduced expression of APC-1B but not APC-1A by the deletion of promoter 1B is responsible for familial adenomatous polyposis.
Reduced expression of APC-1B but not APC-1A by the deletion of promoter 1B is responsible for familial adenomatous polyposis.
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DOI：
10.1038/srep26011
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发表时间：
2016-05-24
影响因子：
4.6
通讯作者：
Furukawa Y
中科院分区：
文献类型：
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作者：
Yamaguchi K;Nagayama S;Shimizu E;Komura M;Yamaguchi R;Shibuya T;Arai M;Hatakeyama S;Ikenoue T;Ueno M;Miyano S;Imoto S;Furukawa Y
抑癌基因 APC 的种系突变与家族性腺瘤性息肉病 (FAP) 相关。在这里，我们对一名散发性 FAP 患者的 DNA 应用了全基因组测序 (WGS)，通过直接测序我们没有发现任何病理性 APC 突变。 WGS 鉴定出大约 10 kb 的启动子缺失，包括 APC 的启动子 1B 和外显子 1B。通过深度 cDNA 测序进行的额外等位基因特异性表达分析表明，缺失使 APC 总转录本中突变 APC 等位基因的表达降低至低至 11.2%，这表明残留的突变转录本是由其他启动子驱动的。此外，基因表达帽分析 (CAGE) 表明，删除的启动子 1B 区域负责除大脑以外的许多组织中的绝大多数 APC 转录。与健康对照相比，该缺失使患者的 APC-1B 转录物减少至 39-45%，但并没有减少 APC-1A 的转录物。 FAP 患者中已报道了包括启动子 1B 在内的不同缺失。总而言之，我们的结果强化了证据，即对于常规直接测序无法识别病理突变的 FAP 患者，应考虑对启动子 1B 的结构变异进行分析。
Germline mutations in the tumor suppressor gene APC are associated with familial adenomatous polyposis (FAP). Here we applied whole-genome sequencing (WGS) to the DNA of a sporadic FAP patient in which we did not find any pathological APC mutations by direct sequencing. WGS identified a promoter deletion of approximately 10 kb encompassing promoter 1B and exon1B of APC. Additional allele-specific expression analysis by deep cDNA sequencing revealed that the deletion reduced the expression of the mutated APC allele to as low as 11.2% in the total APC transcripts, suggesting that the residual mutant transcripts were driven by other promoter(s). Furthermore, cap analysis of gene expression (CAGE) demonstrated that the deleted promoter 1B region is responsible for the great majority of APC transcription in many tissues except the brain. The deletion decreased the transcripts of APC-1B to 39–45% in the patient compared to the healthy controls, but it did not decrease those of APC-1A. Different deletions including promoter 1B have been reported in FAP patients. Taken together, our results strengthen the evidence that analysis of structural variations in promoter 1B should be considered for the FAP patients whose pathological mutations are not identified by conventional direct sequencing.