Molecular Pathology and Embryology of HOXD Related Limb Malformations

Hox基因是发育的主基因，控制身体许多部位（包括肢体）的模式和形态发生。Hox基因的突变导致各种肢体畸形，一个突出的例子是Hoxd13中的多聚丙氨酸扩增，这导致并指（SPD）。在这项研究中，我们将调查HOXD相关的肢体畸形的分子病理学结合人类遗传学的方法与发育遗传学使用在体内和体外模型系统。我们将研究先前在鸡细胞培养系统中鉴定的人HOXD 13错义突变，以鉴定改变的靶基因识别。基于我们以前的研究结果，骨和软骨的形成是严重改变Hoxd13突变体，我们将调查的作用，Hox基因在软骨细胞和成骨细胞分化。我们假设Hoxd调控的Wnt基因参与软骨细胞的极化，并将使用原位杂交筛选，基因调控测定和跖骨器官培养来研究这一点。基于我们的表达筛选，我们的目标是确定一个转录网络周围的Hoxd基因，控制骨形成。将研究Hoxd13多聚丙氨酸突变的显性阴性特征。

Hox genes are master genes of development that control patterning and morphogenesis in many parts of the body including the limb. Mutations in Hox genes result in various limb malformations, a prominent example being the poly-Ala expansion in Hoxd13 which causes synpolydactyly (SPD). In this study we will investigate the molecular pathology of HOXD-related limb malformations combining a human genetic approach with developmental genetics using in vivo and in vitro model systems. We will investigate previously identified human HOXD13 missense mutations in chick cell culture systems to identify altered target gene recognition. Based on our previous findings that bone and cartilage formation is severely altered in Hoxd13 mutants we will investigate the role of Hox genes in chondrocyte and osteoblast differentiation. We hypothesize that Hoxd-regulated Wnt genes are involved in the polarization of chondrocytes and will investigate this using in situ hybridization screens, gene regulation assays and metatarsal organ culture. Based on our expression screen we aim at identifying a transcriptional network around the Hoxd-genes that controls bone formation. The dominant negative character of the Hoxd13 poly-Ala mutations will be investigated.