Division of Biological Sciences, University of Missouri-Columbia, Columbia, Missouri 65211.
G3 (Bethesda). 2012 Jun;2(6):701-6. doi: 10.1534/g3.112.002071. Epub 2012 Jun 1.
A common modulation of gene expression in aneuploids is an inverse correlation of the monitored gene with the dosage of another segment of the genome. Such effects can be reduced to the action of single genes. One gene previously found to modulate leaky alleles of the white eye color gene in Drosophila is Inverse regulator-a (Inr-a). Heterozygotes of mutations increase the expression of white about 2-fold, and trisomic regions surrounding the gene reduce the expression to about two-thirds of the normal diploid level. Further cytological definition of the location of this gene on the second chromosome led to a candidate pre-mRNA cleavege complex II protein (Pcf11) as the only gene in the remaining region whose mutations exhibit recessive lethality as do alleles of Inr-a. The product of Pcf11 has been implicated in transcriptional initiation, elongation, and termination reactions. Four mutant alleles showed molecular lesions predicted to lead to nonfunctional products of Pcf11. The identification of the molecular lesion of Inr-a provides insight into the basis of this common aneuploidy effect.
在非整倍体中，基因表达的一种常见调节方式是受监测基因与基因组另一部分的剂量呈反比。这种影响可以归结为单个基因的作用。先前在果蝇中发现的一种调节白眼颜色基因渗漏等位基因的基因是反向调节因子-a（Inr-a）。突变杂合体使白色的表达增加约 2 倍，而基因周围的三体区域将表达降低到正常二倍体水平的约三分之二。对该基因在第二染色体上的位置进行进一步的细胞学定义，导致候选前体 mRNA 切割复合物 II 蛋白（Pcf11）成为该区域中唯一的基因，其突变表现为隐性致死性，就像 Inr-a 的等位基因一样。Pcf11 的产物已被牵涉到转录起始、延伸和终止反应中。四个突变等位基因显示出分子病变，预计会导致 Pcf11 的非功能性产物。Inr-a 分子病变的鉴定为这种常见的非整倍体效应提供了基础。
