Yamashita Satoshi, Wakazono Kuniko, Nomoto Tomoko, Tsujino Yoshimi, Kuramoto Takashi, Ushijima Toshikazu
Carcinogenesis Division, National Cancer Center Research Institute, Chuo-ku, Tokyo 104-0045, Japan.
Genetics. 2005 Nov;171(3):1231-8. doi: 10.1534/genetics.104.038174. Epub 2005 Aug 3.
Differential expression of mRNA among animal strains is one of the mechanisms for their diversity. cDNA microarray analysis of the prostates of BUF/Nac (BUF) and ACI/N (ACI) rats, which show different susceptibility to prostate cancers, found 195 differentially expressed genes. To identify loci that control differential expression of 13 genes with diverse expression levels, their expression levels were measured by quantitative RT-PCR in 89 backcross rats, and expression quantitative trait locus (eQTL) analysis was performed. Nine genes [Aldh1a1, Aldr1, Bmp6, Cdkn1a (p21), Cntn6, Ghr, Jund, Nupr1, and RT1-M3] were controlled by cis-acting loci. Cdkn1a, a cell cycle regulator and a candidate for a prostate cancer susceptibility gene, was mapped to its own locus and had polymorphisms, including a 119-bp insertion in the 5' upstream region in BUF rats. Four genes (Kclr, Pbsn, Psat1, and Ptn) were controlled by trans-acting loci. Pbsn, a prostate-specific gene on chromosome X, was controlled by a QTL on chromosome 8. Depending upon which gene that we selected from the genes widely used for normalization (Actb, Gapd, or Ppia), different QTL were mapped for Kclr, Psat1, and Ptn. Normalization using Actb most appropriately explained the expression levels in a congenic strain for chromosome 3. eQTL analysis with precise measurement of expression levels and appropriate normalization was shown to be effective for mapping loci that control gene expression in vivo.
动物品系间mRNA的差异表达是其多样性的机制之一。对患前列腺癌易感性不同的BUF/Nac（BUF）大鼠和ACI/N（ACI）大鼠的前列腺进行cDNA微阵列分析，发现了195个差异表达基因。为了鉴定控制13个表达水平各异的基因差异表达的基因座，通过定量RT-PCR在89只回交大鼠中测量了它们的表达水平，并进行了表达定量性状基因座（eQTL）分析。9个基因[醛脱氢酶1家族成员A1（Aldh1a1）、醛还原酶1（Aldr1）、骨形态发生蛋白6（Bmp6）、细胞周期蛋白依赖性激酶1A（Cdkn1a，即p21）、接触蛋白6（Cntn6）、生长激素受体（Ghr）、原癌基因蛋白Jun（Jund）、核仁素1（Nupr1）和RT1-M3]受顺式作用基因座控制。Cdkn1a是一种细胞周期调节因子，也是前列腺癌易感基因的候选基因，它被定位到自身基因座上，并且存在多态性，包括BUF大鼠5'上游区域的119 bp插入。4个基因[钾通道亚家族K成员18（Kclr）、前列腺分泌蛋白（Pbsn）、磷酸丝氨酸转氨酶1（Psat1）和多效生长因子（Ptn）]受反式作用基因座控制。Pbsn是X染色体上的一个前列腺特异性基因，受8号染色体上的一个QTL控制。根据我们从广泛用于标准化的基因（β-肌动蛋白（Actb）、甘油醛-3-磷酸脱氢酶（Gapd）或肽基脯氨酰异构酶A（Ppia））中选择的基因不同，Kclr, Psat1和Ptn的QTL定位也不同。使用Actb进行标准化最恰当地解释了3号染色体同源导入系中的表达水平。对表达水平进行精确测量并进行适当标准化的eQTL分析被证明对于定位体内控制基因表达的基因座是有效的。
