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是一种新发现的伴有小眼球的先天性白内障小鼠，在SJL/J品系中发现了一种自发的隐性突变，出生后2天，晶状体上皮细胞出现了细小但明显的组织学改变。3~3.5月龄时可见晶状体混浊。该白内障由染色体(Chr.)4和5上的两个隐性基因RCT和MRCT(RCT的修饰)控制。RCT基因在白内障的发病中是必不可少的(前田，YY。埃特。艾尔，曼。基因组，2001)。为了克隆RCT基因，我们在RCT和日本野鼠近交系MSM/MS之间产生了2,161个F2代个体，并对RCT基因进行了精细定位。结果发现，该基因座存在于约1.09 Mbps的DNA片段上。然后，我们构建了一个同源品系(N_&lt；13&gt；)，其中含有RCT位点的DNA片段被替换为MSM/MS小鼠的相应DNA，发现该品系中的小鼠晶状体正常。接下来，我们使用几个BAC克隆进行了BAC转基因拯救，其中一些克隆可能包括RCT基因座。我们获得了几个转基因(TG)小鼠品系，表型调查正在进行中。在chr.1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。初步结果表明，mrct1和mrct2分别位于相应染色体上3 cM和15 cM的DNA片段上，mrct1的作用比mrct2强。两种改性剂也显示出协同效应。

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.