Kim Gwang-Jin, Sock Elisabeth, Buchberger Astrid, Just Walter, Denzer Friederike, Hoepffner Wolfgang, German James, Cole Trevor, Mann Jillian, Seguin John H, Zipf William, Costigan Colm, Schmiady Hardi, Rostásy Moritz, Kramer Mildred, Kaltenbach Simon, Rösler Bernd, Georg Ina, Troppmann Elke, Teichmann Anne-Christin, Salfelder Anika, Widholz Sebastian A, Wieacker Peter, Hiort Olaf, Camerino Giovanna, Radi Orietta, Wegner Michael, Arnold Hans-Henning, Scherer Gerd
Institute of Human Genetics, University of Freiburg, Freiburg, Germany Faculty of Biology, University of Freiburg, Freiburg, Germany.
Institute of Biochemistry, University of Erlangen-Nürnberg, Erlangen, Germany.
J Med Genet. 2015 Apr;52(4):240-7. doi: 10.1136/jmedgenet-2014-102864. Epub 2015 Jan 20.
SOX9 mutations cause the skeletal malformation syndrome campomelic dysplasia in combination with XY sex reversal. Studies in mice indicate that SOX9 acts as a testis-inducing transcription factor downstream of SRY, triggering Sertoli cell and testis differentiation. An SRY-dependent testis-specific enhancer for Sox9 has been identified only in mice. A previous study has implicated copy number variations (CNVs) of a 78 kb region 517-595 kb upstream of SOX9 in the aetiology of both 46,XY and 46,XX disorders of sex development (DSD). We wanted to better define this region for both disorders.
By CNV analysis, we identified SOX9 upstream duplications in three cases of SRY-negative 46,XX DSD, which together with previously reported duplications define a 68 kb region, 516-584 kb upstream of SOX9, designated XXSR (XX sex reversal region). More importantly, we identified heterozygous deletions in four families with SRY-positive 46,XY DSD without skeletal phenotype, which define a 32.5 kb interval 607.1-639.6 kb upstream of SOX9, designated XY sex reversal region (XYSR). To localise the suspected testis-specific enhancer, XYSR subfragments were tested in cell transfection and transgenic experiments. While transgenic experiments remained inconclusive, a 1.9 kb SRY-responsive subfragment drove expression specifically in Sertoli-like cells.
Our results indicate that isolated 46,XY and 46,XX DSD can be assigned to two separate regulatory regions, XYSR and XXSR, far upstream of SOX9. The 1.9 kb SRY-responsive subfragment from the XYSR might constitute the core of the Sertoli-cell enhancer of human SOX9, representing the so far missing link in the genetic cascade of male sex determination.
SOX9突变会导致骨骼发育异常综合征——弯肢性发育不良，并伴有XY性反转。对小鼠的研究表明，SOX9作为SRY下游的睾丸诱导转录因子，触发支持细胞和睾丸分化。仅在小鼠中鉴定出了依赖SRY的Sox9睾丸特异性增强子。先前的一项研究表明，SOX9上游517 - 595 kb处一个78 kb区域的拷贝数变异（CNV）与46,XY和46,XX性发育障碍（DSD）的病因有关。我们希望能更明确这两个疾病中该区域的情况。
通过CNV分析，我们在3例SRY阴性的46,XX DSD病例中鉴定出SOX9上游重复，这些重复与先前报道的重复一起确定了一个68 kb的区域，位于SOX9上游516 - 584 kb处，命名为XXSR（XX性反转区域）。更重要的是，我们在4个无骨骼表型的SRY阳性46,XY DSD家族中鉴定出杂合缺失，这些缺失确定了一个32.5 kb的区间，位于SOX9上游607.1 - 639.6 kb处，命名为XY性反转区域（XYSR）。为了定位疑似的睾丸特异性增强子，在细胞转染和转基因实验中对XYSR亚片段进行了测试。虽然转基因实验尚无定论，但一个1.9 kb的SRY反应性亚片段在类支持细胞中特异性驱动表达。
我们的结果表明，孤立的46,XY和46,XX DSD可归因于SOX9上游远处的两个独立调控区域，即XYSR和XXSR。来自XYSR的1.9 kb SRY反应性亚片段可能构成人类SOX9支持细胞增强子的核心，代表了雄性性别决定基因级联中迄今缺失的环节。
