Creation and analysis of animal model monitoring abnormal cell replication

DNA错配修复是一种众所周知的管理和控制基因组结构的系统，其从细菌到人类广泛保守，并且其机制是通过具有校正活性的聚合酶将基因组序列的差距替换成准确结构的作用。我们以前在MRL小鼠睾丸中发现了一种独特的表型，即中期特异性凋亡（Msa）。此外，作为睾丸遗传学分析的结果，我们发现外切核酸酶1（Exo1）的突变是Msa的相关因素。本研究的目的是建立和分析MRL小鼠品系细胞复制监测系统的异常模型小鼠，本研究首次阐明了MRL小鼠的几种独特表型，即存在耐热应激的精母细胞、睾丸中出现卵母细胞和卵巢网源性卵巢囊肿。其次，建立携带MRL小鼠1号染色体端粒区的同源小鼠，并进行分析，以确认Msa和自身免疫性疾病的重现。接着，通过导入反义Exo1和截短的Exo1来创建转基因小鼠，以检查睾丸中的异常是否源自其体积或截短。最后，在体外检测了Exo1基因的外显子跳跃，并使用本研究首次制备的特异性抗体通过免疫组织化学方法阐明了Exo1在睾丸中的定位。这些研究表明，MRL小鼠中出现的许多表型是由于异常的细胞复制监测活性，然而，提示与此无关的其他因素也可能影响MRL小鼠的某些表型。还期望使用MRL小鼠作为几种独特的模型以及自身免疫性疾病。

DNA mismatch repair is a well-known system managing and controlling genomic structure that is conserved widely from bacteria to humans, and its mechanism is an action to substitute the gap of the genomic sequence into an accurate structure by the polymerase possessing proofreading activity. We found previously a unique phenotype in MRL mouse testis, i.e. metaphase-specific apoptosis (Msa). In addition, as a result of a genetics analysis of the testis, we found the mutation of Exonuclease 1(Exo1) as a factor associated with Msa. The purpose of this research project is to create and analyze the abnormal model mouse for the cell replication monitoring system paying attention to MRL mouse strain.In this research, we firstly clarified several unique phenotypes in MRL mice, i.e. the existence of heat stress resistant spermatocytes, the appearance of oocytes in the testis and the development of rete ovarii-derived ovarian cysts. Secondarily, the congenic mice carrying telomere region of the chromosome 1 in MRL mice were created and analyzed to confirm the re-appearance of Msa and autoimmune disease. Next, transgenic mice were created by introduction of antisense Exo1 and truncated Exo1 to examine whether the abnormality in the testis was derived from its volume or truncation. Finally, the exon skipping of Exo1 gene was examined in vitro, and the localization of Exo1 in the testis was clarified by immunohistochemistry using a specific antibody originally produced in the present study.These investigations suggest that many phenotypes presented in MRL mice are due to the abnormal activity monitoring cell replication, however, it is revealed that other factors independent on that might effect on some phenotypes in MRL mice. It would be further expected to use MRL mice as several unique models as well as an autoimmune disease.