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

本研究的目的是分析跨膜神经细胞粘附分子NCAM及其相关的多糖聚唾液酸（PSA）在调节转录中的功能作用。在初步实验中，我们发现NCAM的功能触发抗体会引起基因表达模式的变化，并且蛋白水解的NCAM片段会到达细胞核。这些NCAM片段不仅包括胞内，而且显著地包括跨膜和部分胞外结构域。假设是，片段相关PSA存在或不存在时，基因的转录是不同的，这是由于携带和缺乏PSA的NCAM片段与转录因子或染色质相关分子的不同关联。我们提出PSA调节的转录调节取决于细胞的分化状态- PSA是更多未成熟神经元的特征。我们还提出，携带psa和缺乏psa的NCAM片段的转录调控与已知信号转导途径诱导的转录调控不同。差异转录基因将在mRNA和蛋白质水平上进行鉴定和验证，并通过体外建立的细胞生物学方法分析其功能。这些实验应该可以让我们第一次了解聚糖附着在细胞核粘附分子片段上的功能潜力。

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.