ヒト先天性白内症モデルマウス、RCT,の原因遺伝子と修飾遺伝子の単離と機能解析

RCT是一种与小眼相关的先天性白内障新小鼠，在SJL/J株中发现为自发隐性突变，出生后2天晶状体上皮细胞发生微小但清晰的组织学变化。3 ~ 3.5月龄时可见晶状体混浊。这种白内障由染色体（Chr）上的两个隐性基因rct和mrct （rct的一个修饰子）调控。分别是4和5。rct基因对白内障的发病至关重要(Maeda， YY。等等，曼恩。基因组,2001)。为了克隆rct基因，我们将rct与日本野鼠小家鼠（Mus musculus molossinus）的近交系MSM/Ms进行了2161个F_2后代的克隆，并对rct基因位点进行了精细定位。结果发现，该位点存在于约1.09 Mbps的DNA片段上。然后，我们生成了一个同源菌株（N_<13>），将含有rct位点的DNA片段替换为MSM/Ms小鼠的相应DNA，发现菌株中小鼠的晶状体正常。接下来，我们使用几个BAC克隆进行了BAC转基因拯救，其中一些可以包括rct位点。我们获得了几系转基因（Tg）小鼠，表型调查正在进行中。在chr1上发现了一个新的修饰位点mrct2。为了研究mrct2和mrct1在Chr 5上的相互作用，我们现在产生了几个同源菌株。我们的初步结果显示，mrct1和mrct2分别位于相应染色体上3 cM和15 cM的DNA片段上，并且mrct1的作用相对强于mrct2。两种修饰剂均表现出协同作用。

RCT is a new congenital cataract mouse associated with microphthalmia, which has been found in SJL/J strain as a spontaneous recessive mutant Small but clear histological change in epithelial cells of the lens was observed at 2 days after birth. The opacity of the lens could be observed visually at 3 to 3.5 months of the age. This cataract is regulated by two recessive genes, rct and mrct (a modifier of rct), on Chromosome (Chr.) 4 and 5, respectively. The rct gene is essential for the onset of the cataract (Maeda, YY. et. al., Mann. Genome, 2001). To clone the rct gene, we generated 2,161 individuals of F_2 progeny between RCT and MSM/Ms which is an inbred strain established from Japanese wild mouse Mus musculus molossinus, and carried out fine mapping for the rct locus. As the result, the locus was found to be present on a DNA fragment of approximately 1.09 Mbps. Then, we generated a congenic strain (N_<13>), in which the DNA fragment including rct locus was substituted with the corresponding DNA of MSM/Ms mice, and found that mice in the strain have normal lens. Next, we performed BAC-transgenic rescue using several BAC clones, some of which can be expected to include the rct locus. We obtained several lines of transgenic (Tg) mice and phenotype survey is now in progress.A new additional modifier locus, mrct2, was found on Chr.1. To examine the interaction between the mrct2 and mrct1 on Chr 5, we are now generating several congenic strains. Our preliminary results showed that mrct1 and mrct2 were located to be on 3 cM and 15 cM DNA fragments on corresponding chromosomes, respectively, and that the mrct1 showed relatively stronger effect than the mrct2. Both modifiers also showed a synergetic effect.