Garcia-Crespo David, Juste Ramón A, Hurtado Ana
Department of Animal Health, Instituto Vasco de Investigación y Desarrollo Agrario (NEIKER), Berreaga, 1. 48160 Derio, Bizkaia, Spain.
BMC Vet Res. 2005 Sep 28;1:3. doi: 10.1186/1746-6148-1-3.
Cellular prion protein expression is essential for the development of transmissible spongiform encephalopathies (TSEs), and in sheep, genetic susceptibility to scrapie has been associated to PrP gene polymorphisms. To test the hypothetical linkage between PrP gene expression and genetic susceptibility, PrP mRNA levels were measured by real-time RT-PCR in six ovine tissues of animals with different genotypes.
Previous to the PrP gene expression analysis the stability of several housekeeping (HK) genes was assessed in order to select the best ones for relative quantification. The normalisation of gene expression was carried out using a minimum of three HK genes in order to detect small expression differences more accurately than using a single control gene. The expression stability analysis of six HK genes showed a large tissue-associated variation reflecting the existence of tissue-specific factors. Thereby, a specific set of HK genes was required for an accurate normalisation of the PrP gene expression within each tissue. Statistical differences in the normalised PrP mRNA levels were found among the tissues, obtaining the highest expression level in obex, followed by ileum, lymph node, spleen, cerebellum and cerebrum. A tendency towards increased PrP mRNA levels and genetic susceptibility was observed in central nervous system. However, the results did not support the hypothesis that PrP mRNA levels vary between genotypes.
The results on PrP gene expression presented here provide valuable baseline data for future studies on scrapie pathogenesis. On the other hand, the results on stability data of several HK genes reported in this study could prove very useful in other gene expression studies carried out in these relevant ovine tissues.
细胞朊蛋白表达对于传染性海绵状脑病（TSEs）的发展至关重要，在绵羊中，瘙痒病的遗传易感性与PrP基因多态性有关。为了测试PrP基因表达与遗传易感性之间的假设联系，通过实时RT-PCR测量了不同基因型动物的六个绵羊组织中的PrP mRNA水平。
在进行PrP基因表达分析之前，评估了几个管家（HK）基因的稳定性，以便选择最佳的基因进行相对定量。使用至少三个HK基因进行基因表达的标准化，以便比使用单个对照基因更准确地检测小的表达差异。六个HK基因的表达稳定性分析显示出与组织相关的巨大差异，反映了组织特异性因子的存在。因此，需要一组特定的HK基因来准确标准化每个组织内的PrP基因表达。在各组织之间发现标准化的PrP mRNA水平存在统计学差异，在延髓中获得最高表达水平，其次是回肠、淋巴结、脾脏、小脑和大脑。在中枢神经系统中观察到PrP mRNA水平和遗传易感性增加的趋势。然而，结果不支持PrP mRNA水平在不同基因型之间变化的假设。
本文给出的PrP基因表达结果为未来瘙痒病发病机制的研究提供了有价值的基线数据。另一方面，本研究报道的几个HK基因稳定性数据的结果可能在这些相关绵羊组织中进行的其他基因表达研究中非常有用。
