Identification of a susceptible gene for the development of nephritis, which locates near the D8 GOT128 marker in rat chromosome 8

局灶性节段性肾小球硬化（FSGS）是慢性肾功能衰竭进展中常见的表现。我们在BUF/Mna大鼠中鉴定了一个FSGS易感基因，位于大鼠13号染色体上。在[（BUF/Mna x WKY/NCrj）F1 x BUF/Mna]回交大鼠中，我们发现在大鼠8号和9号染色体上存在修饰基因。本研究的目的是鉴定大鼠8号染色体上的基因。在F2回交队列中，尿蛋白排泄增加的那些人显示BUF/Mna同源性的D8 Mit 5和ACPH标记。使用NCBI数据库UniSTS站点，挑选DNA标记。部分片段在BUF/Mna和WKY/NCrj株间具有长度多态性，可用于分型。分型结果与Enhancement数据库中的基因信息相结合，构建了大鼠8号染色体上的一个候选区域（81.6-86.6 Mb）的物理图谱。该区域有30个基因。对BUF/Mna和WKY/NCrj株进行PCR直接测序，并测定其基因编码序列。在感光细胞间基质蛋白聚糖1（Impg 1）基因中发现了一个导致亮氨酸-脯氨酸取代的点突变。用DNA合成法制备特异性抗体。然而，抗体不能染色大鼠组织和器官。（Lama 1是大鼠9号染色体上的修饰基因候选者。免疫组织化学分析清楚地表明，Lamal表达在肾小管基底膜。

Focal and segmental glomerulosclerosis (FSGS) is a frequent finding in the progression of chronic renal failure. We identified a FSGS susceptibility gene in the BUF/Mna rat, which locate on rat chromosome 13. In the [(BUF/Mna x WKY/NCrj)F1 x BUF/Mna] backcross rats, we found that there was a modifier gene on rat chromosome 8 and 9. The purpose of the present study is to identify the gene on rat chromosome 8. In the F2 backcross cohort, urinary protein excretion increased in those individuals who showed BUF/Mna homozygousity for the D8Mit5 and ACPH markers. Using the NCBI data base UniSTS site, DNA markers were picked up. Some of them showed length polymorphism between BUF/Mna and WKY/NCrj strains and were used in typing. The results of the typing, together with gene information obtained from Ensemble data base, led us construct a physical map that indicated a candidate region on rat chromosome 8 (81.6-86.6 Mb). There were 30 genes in the region. PCR direct sequencing was performed, and then coding sequence of these genes were determined in the BUF/Mna and WKY/NCrj strains. A point mutation, which results in leucine-prolin substitution, was found in interphotoreceptor matrix proteoglycan 1 (Impg1) gene. Specific antibodies were produced by the use of DNA synthesis method. However, the antibodies were not capable of staining rat tissues and organs. (Lama1 is a modifier gene candidate on rat chromosome 9. Immunohistochemical analysis clearly showed that Lamal is expressed in tubular basement membranes of the kidney.)