PDX-1 IN MAMMALIAN PANCREATIC DEVELOPMENT

我们的长期目标是产生与多潜能胰腺干细胞的鉴定、纯化、扩增和分化相关的信息，这可能导致适用于胰腺替代疗法的材料，并增加我们对II型糖尿病中的细胞缺陷的理解，并最终帮助抵消II型糖尿病中的细胞缺陷。虽然最近在这些领域取得了一些进展，从小鼠的研究与失活的基因编码的转录因子在胰腺中表达，我们的内分泌/外分泌分化在胚胎发育过程中的机制的理解，并在成人的细胞类型和功能的维护，仍然是初步的。我们提出了一套集中的实验，旨在填补这些空白。首先，我们将对一个重要的胰腺基因pdx-1进行精确的功能分析。整体pdx-1失活阻断胰腺发育，我们现在将确定pdx-1在胰腺细胞分化后期，外分泌，β和非β细胞基因中的作用，表明pdx-1转录调控是β细胞功能控制的主要焦点。我们已经确定了可能的pdx-1顺式调控元件，包含转录因子，包括HNF 3 β和最近描述的MODY易感因子的结合位点。我们将确定这些保守的顺式调控元件在体内的作用。第三，我们将发展遗传谱系追踪技术来表征内分泌细胞的个体发生。具体目标是：（1）确定在选定的内分泌和外分泌细胞中灭活pdx-1的效果。(2)为了在体内确定PDX-1中保守的顺式调节序列的作用，开始剖析控制胰腺形成和功能的转录调节网络。(3)发展遗传谱系追踪技术，以严格了解胰腺细胞个体发育，特别是内分泌途径。

Our long-term goals are to produce information relevant to the identification, purification, expansion and differentiation of multi- potential pancreatic stem cells, which may lead to material suitable for pancreas replacement therapy, and increase our understanding of, and eventually help to offset, the cellular defects in type II diabetes. Although some progress in these areas has come recently from studies of mice with inactivated genes that encode transcription factors expressed in the pancreas, our mechanistic understanding of endocrine/exocrine differentiation during embryogenesis, and maintenance of cell type and function in adults, is still rudimentary. We propose a focused set of experiments directed at filling some of these gaps. First, we will carry out a precise functional analysis of an essential pancreatic gene, pdx-1. Global pdx-1 inactivation blocks pancreas development, and we will now determine the role of pdx-1 in later stages of pancreatic cell differentiation, in the exocrine, beta and non-beta cell genes, indicating that pdx-1 transcriptional regulation is a major focus for the control of beta cell function. We have identified likely pdx-1 cis-regulatory elements that contain binding sites for transcription factors that include HNF3beta and the recently described MODY susceptibility factors. We will determine the role of these conserved cis-regulatory elements in vivo. Third, we will develop genetic lineage tracing techniques to characterized endocrine cell ontogeny. Specific aims are: (1) to determine the effect of inactivating pdx-1 in selected endocrine and exocrine cells. (2) to determine in vivo the role of conserved cis-regulatory sequences in pdx-1, to begin to dissect the transcriptional regulatory networks controlling pancreas formation and function. (3) Develop genetic lineage tracing techniques for a rigorous understanding of pancreatic cell ontogeny, with special reference to the endocrine pathway.