Recent studies support the assumption that mutation of the X-linked Pig-a gene is most likely responsible for the mutant phenotype of the cells deficient in glycosylphosphatidylinositol (GPI)-anchored proteins quantified in the rodent Pig-a gene mutation assay. In humans, however, mutations in both alleles of one of the 30 other genes involved in GPI-anchor synthesis, e.g., PIG-L and PIG-O, cause reduced expression of surface GPI-anchored proteins. Here, we investigated the possibility that the loss of the GPI-anchor detected by the rat Pig-a assay also could be caused by mutation in other GPI-biosynthesis genes. 31 samples were obtained from 8 inbred and outbred rat strains commonly used for genetic toxicology assays. In order to investigate possible sources of variation in the Pig-a assay, variant DNA sequences were evaluated in Cd59 and 24 GPI-biosynthesis genes. In some genes, such as Pig-n and Pig-u, homozygous variations occurred in all animals, suggesting that these variations are due to deviations in the reference genome. Heterozygous Pig-s, Pig-w, Pig-o, Pig-c, Pgap1, Pgap2, Pig-k and Pig-t variations were found, however, indicating that these genes could serve as targets for mutation in the assay. Protein alignment for these altered genes was conducted with possible human, mouse and rat phenotypic mutants from the literature; this analysis demonstrated that many of the variations that we detected were in non-conserved sequences and that no phenotypes for any of these variants could be inferred from known mutants from the literature. All heterozygous variants were in outbred rats. Overall, the findings of this study cannot totally rule out the possibility that mutations in GPI-biosynthesis genes other than Pig-a are detected in the Pig-a assay, but suggest that if it occurs, it must occur only rarely and therefore mutations in genes other than Pig-a have little impact on rat-based experiments.

最近的研究支持这样的假设，即 X 连锁Pig-a基因的突变最有可能是在啮齿动物Pig-a基因突变测定中量化的缺乏糖基磷脂酰肌醇 (GPI) 锚定蛋白的细胞的突变表型的原因。在人类中，然而，在涉及在GPI锚合成中的其他30个基因中的一个，的两个等位基因的突变例如，PIG-L和PIG-O ，原因减少的表面GPI锚定蛋白的表达。在这里，我们研究了大鼠Pig-a检测到 GPI-anchor 丢失的可能性检测也可能由其他 GPI 生物合成基因的突变引起。从通常用于遗传毒理学分析的 8 个近交和远交大鼠品系中获得了 31 个样品。为了研究Pig-a测定中可能的变异来源，在Cd59和 24 GPI 生物合成基因中评估了变异 DNA 序列。在一些基因中，例如Pig-n和Pig-u，所有动物都发生了纯合变异，这表明这些变异是由于参考基因组的偏差造成的。杂合Pig-s、Pig-w、Pig-o、Pig-c、Pgap1、Pgap2、Pig-k和Pig-t然而，发现了变异，表明这些基因可以作为测定中突变的靶标。这些改变基因的蛋白质比对是用文献中可能的人类、小鼠和大鼠表型突变体进行的；该分析表明，我们检测到的许多变异都在非保守序列中，并且无法从文献中的已知突变体推断出任何这些变异的表型。所有杂合变体都在远交大鼠中。总体而言，这一研究结果并不能完全排除在GPI生物合成基因突变比其他的可能性PIG-A在检测到猪一个试验，但建议，如果真的发生了，它必须发生在只有很少，因此突变Pig-a以外的基因 对基于大鼠的实验影响不大。