アクティブボード・２０１１年　８月
　　　　　・・・・・２０１１年　８月　９日更新・・・・・

研究発表を行った学会；
・23rd International Symposium on Pediatric Surgical Research in 2010
　２０１０年　９月１４日（東京）

タイトル；The Skt gene, required for the anorectal development, is a candidate for a molecular marker of cloacal plate.

発表者；須田　博子　氏
　　　（熊本大学　大学院生命科学研究部　運動骨格病態学分野、生命資源研究・支援センター　疾患モデル分野）

Abstract；
Background and aims:
Anorectal malformations (ARMs) are one of the common birth defects. Although the etiology of ARMs remains unclear, it has been reported that the defect of dorsal cloacal plate was associated with ARMs. However, there is little information about the Cloacal plate. Danforth’s short tail (Sd) mutant mice show ARMs. Interestingly, Skt-LacZ mutant, in which Skt gene was disrupted by the gene trap vector (LacZ), made the incident rate of ARMs of Sd mutant 100%. Therefore, Skt-LacZ mutation has a noticeable effect on ARMs of Sd mutant and the [Sd Skt-LacZ/+ Skt-LacZ] mutant may be an ideal ARMs model for the analysis of the anorectal development. In this study, Skt expression around the cloaca during the anorectal development and ARMs of [Sd Skt-LacZ/+ Skt-LacZ] mutant are described.

Methods:
The [Sd Skt-LacZ/+ Skt-LacZ] embryos were produced through in vitro fertilization between Skt-LacZ homozygotes and [Sd Skt-LacZ/+ +] mice. Embryos were dissected out from embryonic day 9.5 (E9.5) to E12.5. After X-gal staining, embryos were embedded in paraffin according to standard procedures. Sections of 8 μm were prepared and counter-stained.

Results:
In normal control embryos, Skt expression was detected both at the endoderm and ectoderm of the cloacal plate from E9.5 onward. At E12.5, Skt expression was detected not only at the cloacal plate, but also at mesenchymal cells neighboring dorsal cloacal plate. In [Sd Skt-LacZ/+ Skt-LacZ] mutant embryos, the cloacal plate failed to extend proximodistally and, consequently, the dorsal part of cloacal plate was apparently defective at E11.5. The mesenchymal tissue neighboring dorsal cloacal plate was thick at E12.5. In addition, Skt expressing cells in mutant were detected at the shortened cloacal plate and thick mesenchyme dorsal to it.

Conclusions:
In current study, we propose that Skt is a marker for cloacal plate during the anorectal development, and ARMs in [Sd Skt-LacZ /+ Skt-LacZ] mutant embryos is caused by defect of dorsal cloacal plate. Furthermore, Skt expressing cells in the mutant were detected at the malformed cloacal plate and neighboring mesenchyme, suggesting that these tissues might be associated with ARMs.