Do fragments of the neural cell adhesion molecule NCAM with or without attached polysialic acid differentially regulate transcription?

这项研究的目的是分析跨膜神经细胞黏附分子NCAM及其相关的糖聚唾液酸(PSA)在转录调控中的功能作用。在初步实验中，我们显示了针对NCAM的功能触发抗体引起了基因表达模式的变化，并且蛋白水解性NCAM片段到达了细胞核。这些NCAM片段不仅包括胞内结构域，还包括跨膜结构域和部分胞外结构域。假说是，由于携带和缺失PSA的NCAM片段与转录因子或染色质相关分子的结合不同，在有或没有片段相关PSA的情况下，基因的转录是不同的。我们认为，PSA调节的转录调控依赖于细胞的分化状态-PSA是更多未成熟神经元的特征。我们还提出，携带和缺失PSA的NCAM片段对转录的调控不同于已知的信号转导途径。差异转录基因将在mRNA和蛋白质水平上进行鉴定和验证，并将通过建立的细胞生物学方法在体外分析它们的功能。这些实验应该可以让人们首次深入了解附着在细胞核内黏附分子片段上的多糖的功能潜力。

The aims of the proposed studies are the analysis of the functional roles of the transmembrane neural cell adhesion molecule NCAM and its associated glycan polysialic acid (PSA) in regulating transcription. In preliminary experiments we showed that function-triggering antibodies against NCAM elicit changes in the expression pattern of genes and that proteolytic NCAM fragments reach the nucleus. These NCAM fragments comprise not only the intracellular, but remarkably also the transmembrane and part of the extracellular domains. The hypothesis is that transcription of genes is different in the presence or absence of fragment-associated PSA due to the different association of PSA-carrying and -lacking NCAM fragments with transcription factors or chromatin-associated molecules. We propose that PSA-modulated transcriptional regulation depends on the differentiation state of cells - with PSA being characteristic of more immature neurons. We also propose that transcriptional regulation by PSA-carrying and -lacking NCAM fragments is different from that induced by the known signal transduction pathways. The differentially transcribed genes will be identified and validated at the mRNA and protein levels, and their functions will be analyzed via established cell biological methods in vitro. These experiments should allow first insights into the functional potential of glycans attached to adhesion molecule fragments in the nucleus.