Department of Human Molecular Genetics, University of Heidelberg, 69120 Heidelberg, Germany.
Hum Mol Genet. 2011 Apr 15;20(8):1524-35. doi: 10.1093/hmg/ddr030. Epub 2011 Jan 27.
The short stature homeobox gene SHOX encodes a transcription factor which is important for normal limb development. In humans, SHOX deficiency has been associated with various short stature syndromes including Leri-Weill dyschondrosteosis (LWD), Langer mesomelic dysplasia and Turner syndrome as well as non-syndromic idiopathic short stature. A common feature of these syndromes is disproportionate short stature with a particular shortening of the forearms and lower legs. In our studies employing microarray analyses and cell culture experiments, we revealed a strong positive effect of SHOX on the expression of the fibroblast growth factor receptor gene FGFR3, another well-known factor for limb development. Luciferase reporter gene assays show that SHOX activates the extended FGFR3 promoter, and results from chromatin immunoprecipitation (ChIP)-sequencing, ChIP and electrophoretic mobility shift assay experiments suggest a direct binding of SHOX to multiple upstream sequences of FGFR3. To further investigate these regulations in a cellular system for limb development, the effect of viral overexpression of Shox in limb bud derived chicken micromass cultures was tested. We found that Fgfr3 was negatively regulated by Shox, as demonstrated by quantitative real-time polymerase chain reaction and in situ hybridization. This repressive effect might explain the almost mutually exclusive expression patterns of Fgfr3 and Shox in embryonic chicken limbs. A negative regulation that occurs mainly in the mesomelic segments, a region where SHOX is known to be strongly expressed, offers a possible explanation for the phenotypes seen in patients with FGFR3 (e.g. achondroplasia) and SHOX defects (e.g. LWD). In summary, these data present a link between two frequent short stature phenotypes.
矮小同源盒基因 SHOX 编码一种转录因子，对于正常肢体发育非常重要。在人类中，SHOX 缺乏与各种矮小综合征有关，包括 Leri-Weill 软骨发育不全症（LWD）、Langer 中胚层发育不良和特纳综合征以及非综合征性特发性矮小症。这些综合征的一个共同特征是不成比例的身材矮小，特别是前臂和小腿的缩短。在我们使用微阵列分析和细胞培养实验的研究中，我们揭示了 SHOX 对成纤维细胞生长因子受体基因 FGFR3 表达的强烈正向影响，FGFR3 也是另一种已知的肢体发育因子。荧光素酶报告基因检测表明，SHOX 激活了扩展的 FGFR3 启动子，染色质免疫沉淀（ChIP）-测序、ChIP 和电泳迁移率变动分析实验的结果表明 SHOX 直接与 FGFR3 的多个上游序列结合。为了在肢体发育的细胞系统中进一步研究这些调控作用，测试了病毒过表达 Shox 在肢芽衍生的鸡微团培养物中的作用。我们发现 Fgfr3 受到 Shox 的负调控，这通过定量实时聚合酶链反应和原位杂交得到证实。这种抑制作用可能解释了 Fgfr3 和 Shox 在胚胎鸡肢体中的几乎相互排斥的表达模式。主要发生在中胚层节段的负调控，SHOX 已知在该区域强烈表达，为 FGFR3（例如软骨发育不全症）和 SHOX 缺陷（例如 LWD）患者所见表型提供了可能的解释。总之，这些数据在两种常见的矮小表型之间建立了联系。
