Aberrant splicing of the C4 gene trans cript of H-2^k mouse strains coused by the insertion of a retroposon, B2.

将逆转录酶B2序列插入到补体C4基因的13个内含子中，获得了低C4产量的H-2^k衍生C4菌株。在这些品系的小鼠中，检测到C4mRNA的异常加工和C4mRNA水平的降低。为了验证H-2^k来源菌株中B2插入与低C4产生之间的可能的因果关系，我们构建了含或不含B2序列的重组C4基因，并将其导入培养的肝癌细胞中。不含B2序列的重组C4基因只产生正常水平的C4mRNA，而含有B2序列的重组C4基因可导致C4基因转录本的异常剪接和正常C4mRNA量的降低。与肝细胞相反，来自H-2^k小鼠品系的腹膜巨噬细胞只产生正常水平的正常加工的C4mRNA。

A retroposon B2 sequence is inserted into the 13 intron of the complement C4 gene of H-2^k derivred C4 strains that are characterized by the low C4 production. Aberrantly processed C4 mRNA and decreased level of C4 mRNA are detected in these mouse strains. To test the possible causal relationship between the B2 insertion and low C4 production in H-2^k derived strains, we constructed recombinant C4 gene with or without the B2 sequence and transfected them into cultured hepatoma cells. The transfection of recombinant C4 gene without the B2 sequence always resulted in the production of only normal C4 mRNA at the normal level, while transfection of recombinant C4 gene with the B2 sequence resulted in the abnormal splicing of C4 gene transcript and devreased level of normal C4 mRNA.Tissue-specific regulation of RNA processing for C4 gene transcript in H-2^k mouse strains are identified by analyzing the C4 mRNA from various tissues. In contrast to hepatic cells, peritoneal macrophages from H-2^k derived mouse strains, produced only normally processed C4 mRNA at the normal level.