Evidence of evolutionary up-regulation of the single active X chromosome in mammals based on Clc4 expression levels in Mus spretus and Mus musculus
Evidence of evolutionary up-regulation of the single active X chromosome in mammals based on Clc4 expression levels in Mus spretus and Mus musculus
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DOI：
10.1073/pnas.94.17.9244
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发表时间：
1997-08-19
影响因子：
11.1
通讯作者：
Disteche, CM
中科院分区：
文献类型：
--
作者：
Adler, DA;Rugarli, EI;Disteche, CM
先前的研究已经表明，氯离子通道基因Clc 4是X连锁的，并且在小鼠中经历X失活，但是相同的基因在实验室品系的小鼠中是常染色体的。利用两种可交配小鼠物种之一中的X染色体连锁保守性的这种例外来比较来自X染色体的Clc 4表达与来自常染色体的Clc 4表达，Clc 4在两种小鼠的脑组织中均高度表达。spretus X实验室菌株杂交，证明每个常染色体基因座具有与单个活性X连锁基因座相比一半的CIc 4表达水平。与此相反，在两种小鼠物种中常染色体的另一种氯离子通道基因Clc 3的表达在F-I动物的等位基因之间相等。没有证据表明Clc 4常染色体基因座的印记。这些结果与Ohno的假说一致，即进化需要单个活性X染色体上的基因的更高表达以维持与常染色体基因表达的平衡[Ohno，S.（1967）Sex Chromosomes and Sex-Linked Genes（Springer，柏林）]。
Previous studies have shown that the chloride channel gene Clc4 is X-linked and subject to X inactivation in Mus spretus, but that the same gene is autosomal in laboratory strains of mice, This exception to the conservation of linkage of the X chromosome in one of two interfertile mouse species was exploited to compare expression of Clc4 from the X chromosome to that from the autosome, Clc4 mas found to be highly expressed in brain tissues of both mouse species, Quantitative analyses of species-specific expression of Clc4 in brain tissues from mice resulting from M. spretus x laboratory strain crosses, demonstrate that each autosomal locus has half the level of CIc4 expression as compared with the single active X-linked locus. In contrast expression of another chloride channel gene, Clc3, which is autosomal in both mouse species is equal between alleles in F-I animals, There is no evidence of imprinting of the CIc4 autosomal locus, These results are consistent with Ohno's hypothesis of an evolutionary requirement for a higher expression of genes on the single active X chromosome to maintain balance with autosomal gene expression [Ohno, S. (1967) Sex Chromosomes and Sex-Linked Genes (Springer, Berlin)].