POSITIONAL CLONING OF HEREDITARY CATARACTS IN MICE

我们对在日本发现的两种小鼠遗传性白内障的基因进行了定位克隆。这些基因被认为与器官形成和晶状体透明度的维持有关。根据晶体性白内障破裂（RLC）的精细定位结果，我们在RIKEN开发的小鼠全长cDNA百科全书中获得的图谱位置上对多个cDNA克隆进行了测序。其中一个cDNA克隆rlcl与正常cDNA序列相比，缺失了27 bp。这种缺失是RLC突变体所特有的。兔抗rlcl产物c端肽血清在晶状体中检测到110 kDa的多肽。免疫组化结果显示，该抗血清在晶状体上皮、神经系统等组织中分布独特。白内障发生的机制目前正在研究中。另一方面，在中野白内障（NCT）中，同样的定位方法显示nctl cDNA缺失13 bp。这种缺失在NK11中是保守的，NK11是NEL提供的一种已建立的晶状体上皮细胞系。仔细检查N2交叉到MSM的晶状体，发现两种不同形式的晶状体混浊分布和潜伏期。我们可以在Chr 3和Chr 10定位两个修饰位点，确定NCT白内障的亚型。为了进一步确认这些缺失确实是致病突变，本实验室正在进行正常全尺寸cDNA的修复和靶向实验。

We performed positional cloning of the genes responsible for two mouse hereditary cataracts found in Japan. These genes are supposedly involved in organogenesis and maintenance of transparency of the lens. According to the results of fine mapping of Rupture of lens cataract (RLC), we sequenced a number of the cDNA clones at the map positions obtained from the mouse full-length cDNA encyclopedia developed by RIKEN. One of cDNA clones, rlcl, was found to have deletion of 27 bp, when compared with the normal cDNA sequence. This deletion was specific to RLC mutant. Rabbit antiserum to the C-terminus peptide of rlcl product detected a 110 kDa polypeptide in the lens. Immunohistochemistry with this antiseum revealed unique distribution in lens epithelium, nervous system and other tissues. Mechanism of cataractgenesis is now under investigation. On the other hand, the same positional approach in Nakano cataract (NCT) demonstrated a 13 bp deletion in nctl cDNA. This deletion was conserved in NK11, an established cell line of lens epithelium provided from NEL Careful examination of the lenses in N2 cross to MSM revealed two distinct forms of lens opacity in respect to distribution of cloudiness and latent period. We could map two modifier loci determining the subtypes of NCT cataract on Chr. 3 and 10.To further confirm that these deletions are indeed causative mutation, rescue with normal full size cDNA and targeting experiments are now in progress in this laboratory.