202305Tokuyasu

研究発表を行った学会；36th International Mammalian Genome Conference
2023年3月29-31日　（つくば国際会議場/オンライン ハイブリッド開催）
タイトル； Dysregulation of the autoregulatory enhancer region causes ectopic expression of Ptf1a in Danforth’s short tail (Sd) mice..
発表者；徳安　碧氏
（熊本大学　生命資源研究・支援センター　疾患モデル分野）
要旨；
Danforth’s short tail (Sd) is a semidominant mutation on mouse Chromosome 2, characterized by spinal defects, urogenital defects, and anorectal malformations. We have previously showed the nature of the Sd mutation to be the insertion of a copy of endogenous retrovirus, ERV-β2/ETnERV3, causing ectopic expression of Ptf1a in the caudal region from E8.5 in the Sd embryo. Ptf1a is required for pancreatic specification and neurodevelopmental roles, and known to express in the pancreatic primordium and neural tube after E10. Since deletion of the ERV in the Sd allele resulted in disappearance of Sd phonotypes, involvement of the ERV in Sd phenotypes is apparent, but the mechanism of ectopic expression of Ptf1a is still unknown.
The expression of Ptf1a is controlled by several enhancer elements. We focused on an autoregulatory (5’-AR) enhancer located in 13.4 kb upstream of the Ptf1a transcriptional start site, just 1.2 kb upstream of the ERV insertion site and conserved among mammals. Deletion of the 5’-AR conserved region from the Sd allele also resulted in disappearance of Sd phenotypes, showing that this region is essential for ectopic expression of Ptf1a. The 5’-AR region contains two CpG islands, each of which contains one core enhancer elements, E-TC box. We removed 10~15 bps of either or both of the core elements by using CRISPR-Cas9D10A nickase, and found that the proximal E-TC box had a critical role of ectopic expression. We postulate that the inserted ERV affects interaction between the 5’-AR enhancer region and the Ptf1a transcriptional start site.