Molecular Mechanisms of Pancreas Development in Xenopus

脊椎动物胰腺发育的分子调控是一个激烈的研究活动的主题，也是因为更好地了解这一过程可能会导致定义的实验方案，从前体细胞在体外产生胰腺组织，这可能是在胰腺功能障碍的细胞治疗。在过去的两年中，我们已经制定了工具和协议的肝脏和胰腺发育的分子分析，以及胰腺（和肝脏）基因表达的诱导在非洲爪蟾多能胚胎前体细胞。我们还发现视黄酸（RA）作为一个关键的信号，基本上是reequired的早期内胚层图案对胰腺的命运在非洲爪蟾，此外，我们观察到，过多的RA促进形成内分泌胰腺细胞的外分泌细胞的费用。在这些研究的扩展中，我们现在打算鉴定参与原始内胚层模式化的RA应答基因。此外，我们希望研究三种不同的转录调节因子，即p48/Ptf 1a，ESR-10和ngnr 1，在胰腺内分泌与外分泌分化的背景下，通过使用获得和功能丧失的方法在转基因青蛙的活动。我们还打算进一步推进我们的实验方案，通过采用相关的转录调节因子，从多能胚胎前体细胞产生内分泌和外分泌胰腺细胞。最后，我们希望通过SAGE和基于微阵列的方法来定义纯化的GFP标记的胰腺前体细胞的转录组，以确定参与早期胰腺发育的新的候选调控活动。

Molecular regulation of pancreas development in vertebrates is a topic of intense research activities, also because a better understanding of this process may lead to the definition of experimental protocols for the generation of pancreatic tissue from precursor cells in vitro, which could be employed in cell therapy of pancreas malfunction. During the past two years, we have worked out tools and protocols for the molecular analysis of liver and pancreas development, as well as for the induction of pancreas (and liver) gene expression in pluripotent embryonic precursor cells in Xenopus. We have also found retinoic acid (RA) to act as a key signal that is essentially reequired for the early endodermal patterning towards a pancreatic fate in Xenopus; furthermore, we observed that excessive RA promotes the formation of endocrine pancreatic cells at the expense of exocrine cells. In extension of these studies, we now intend to identify the RA-responcive genes that are involved in the patterning of the primitive endoderm. Furthermore, we wish to study the activity of three different transcription regulators, namely p48/Ptf1a, ESR-10 and ngnr1, in the context of endocrine-versus-exocrine pancreatic differentiation by use of gain- and loss-of-function approaches in transgenic frogs. We also intend to further advance our experimental protocol for the generation of endocrine and exocrine pancreatic cells from pluripotent embryonic precursor cells by employing relevant transcription regulators. Finally, we wish to define the transcriptome of purified, GFP-tagged pancreatic precursor cells by SAGE and microarray based approaches in order to identify novel candidate regulatory activities that are involved in early pancreas development.