Growth Versus Differentiation in Human Beta Cells

描述(申请人提供)：了解成熟的内分泌细胞从内分泌前体细胞发育的机制是非常重要的，因为这可能导致糖尿病细胞移植治疗的β细胞的无限来源的发展。糖尿病研究的一个目标是从人的内分泌胰腺培养出细胞系，这种细胞系可以无限生长，并被诱导沿着β细胞谱系分化，从而产生葡萄糖反应性胰岛素分泌。在过去的资助期间，成功地开发了致力于Delta型或Beta细胞系的细胞系。这项提议的重点是探索这种世系承诺的性质。人胰腺内分泌细胞系分化为德尔塔细胞或β细胞系。这一建议的中心假设是，细胞系的不同谱系承诺反映了参与建立和维持成熟内分泌细胞的转录因子表达的差异。 首先，将研究bHLH转录因子NeuroD1在Delta细胞系中抑制生长抑素启动子活性，导致部分转换为β细胞系的机制。我们将利用逆转录病毒载体将基因转移到人胰腺内分泌细胞系中，研究其他已被确定为参与三角洲和β细胞谱系承诺的候选转录因子。将使用DNA微阵列技术确定在Delta和Beta细胞系中差异表达的基因，以及在b细胞发育中重要的转录因子下游的基因。最后，将进行基因筛查，以分离上调胰岛素启动子活性的基因。

DESCRIPTION (provided by applicant): Understanding the mechanism by which mature endocrine cells develop from endocrine precursors is of great importance as it could lead to the development of an unlimited source of beta cells for cell transplantation therapies for diabetes. A goal of diabetes research has been to develop cell lines from the human endocrine pancreas that can be grown in unlimited quantities and induced to differentiate along the beta cell lineage resulting in glucose-responsive insulin secretion. During the past funding period, success was achieved in developing cell lines that are committed to either the delta or beta cell lineages. This proposal is focused on exploring the nature of that lineage commitment. of human pancreatic endocrine cell lines to either the delta or beta cell lineages. The central hypothesis of this proposal is that the differential lineage commitment of the cell lines reflects differences in the expression of transcription factors that are involved in the establishment and maintenance of mature endocrine cells. Initially, the mechanism by which the bHLH transcription factor NeuroD1 acts to repress somatostatin promoter activity in a delta cell line, resulting in a partial switch to the beta cell lineage, will be studied. Other transcription factors that have been identified as candidates for being involved in delta versus beta cell lineage commitment will be studied using retroviral vector-mediated gene transfer into human pancreatic endocrine cell lines. Genes that are differentially expressed in delta versus beta cell lines and that are downstream of transcription factors that are important in b-cell development will be ascertained using DNA microarray technology. Finally, a genetic screen will be undertaken to isolate genes that upregulate insulin promoter activity.