Physiologic Functions of Polyamines

在这个项目中，我们对通常存在于细胞中的大量多胺的生理功能特别感兴趣。为此，在一个正在进行的项目中，我们对酵母多胺进行了微阵列研究，要求突变体找出精胺或精胺添加或缺失对全局基因表达的特定影响（在NIDDK微阵列设备的帮助下）。数据分析表明，精胺对酵母基因转录的影响大于精胺。在一项缺失的spe3 S. cerevisiae营养不良的研究中，我们发现亚精胺的添加导致73个基因的诱导超过4倍，包括一些转录因子（MET28, GAT1）。基因的功能分类显示，诱导转运相关基因（16%）和氨基酸代谢，特别是蛋氨酸生物合成（19%）。亚精胺对28个基因的抑制作用超过4倍。相比之下，只有少数基因（14个）对精胺有显著反应。对少数代表性基因的实时PCR分析显示了与微阵列实验相似的趋势。

In this project we have been paricularly interested in thephysiologic function of the large amount of polyamines normally present in cells. For this purpose in an ongoing project we have performed microarray studies in yeast polyamine requiring mutants to find out specific effects of spermidine or spermine addition or depletion on global gene expression (with the help of the NIDDK Microarray Facility). The analysis of the data revealed that spermudine has more effect on transcription of yeast genes than spermine. In a study with a deleted spe3 S. cerevisiae auxotroph we found that spermidine addition resulted in more than a4-fold induction of 73 genes including some of the transcription factors (MET28, GAT1). Functional categorization of the genes showed induction of transport related genes (16%), and amino acid metabolism, in particular methionine biosynthesis (19%). Spermidine also repressed 28 genes more than 4-fold. In contrast, only few genes (14) were significantly responsive to spermine. Real time PCR analysis o fa few represetnative genes showed a similar trend to that found in the microarray experiments. Further characterization of specific pathways and their metabolites affected by spermidine addition are under investigation using other mutants deleted in polyamine biosynthesis with a particular interest in studing why yeast cells normally contain much higher concentrations of polyamines than needed for growth.. In particular we have recently carried out such studies on the early and late responses of spermidine additions using a yeast double mutants (deleted spe1-deleted spe 2) We have detected several interesting targets of spermidine, which include several transcripts of heat shock proteins, zinc and copper transporters, zinc finger transcription factors, TyA (Gag protein) and TyB (Gag-Pol) proteins. We are also continuing our studies on the role of spermidine in protecting polyamine auxotrophs from oxygen toxicity, with particular interest in the level of spermidine required.