Schnülle V, Antropova O, Gronemeier M, Wedemeyer N, Jockusch H, Bartsch J W
Developmental Biology Unit, University of Bielefeld, Germany.
Mamm Genome. 1997 Oct;8(10):718-25. doi: 10.1007/s003359900553.
Myotonias are muscle diseases in which the function of the muscular chloride channel ClC-1 is impaired. Null alleles of the corresponding Clc1 gene on mouse chromosome (Chr) 6 provide animal models for human myotonias. It was shown that the allele adr (Clc1adr) is due to an insertion of an ETn type transposon that is transcribed and leads to multiple splicing events; the allele mto (Clc1adr-mto) involves a stop codon near the N-terminus. We have determined the genomic organization of the mouse Clc1 gene and the sequence requirements for the transposon insertion in the Clc1adr allele. The mouse Clc1 gene is composed of 23 exons, ranging from 39 to 372 bp, and spans approximately 23 kb of genomic DNA. The exon/intron organization is highly homologous to that of the human CLCN1 gene; the homology of the coding sequence is 97% to rat and 89% to human. In the adr allele the ETn transposon is inserted into intron 12, the largest intron. Whereas the 5' and 3' LTR sequences of the ETn transposon are homologous to those reported for other insertional mutations of the mouse, no consensus motif for an insertion target site could be defined. On the basis of flanking sequences, we provide duplex PCR diagnoses for the adr, adr-mto, and wild-type alleles of Clc1. Close to the 3' end of intron 12, a tetranucleotide repeat (AATC)n was found that is polymorphic between mouse species Mus musculus, M. molossinus, M. castaneus, and M. spretus, and can thus be used for chromosomal mapping studies.
肌强直是一类肌肉疾病，其中肌肉氯离子通道ClC-1的功能受损。小鼠6号染色体（Chr）上相应的Clc1基因的无效等位基因为人类肌强直提供了动物模型。研究表明，adr等位基因（Clc1adr）是由于ETn型转座子的插入，该转座子被转录并导致多种剪接事件；mto等位基因（Clc1adr-mto）在N端附近有一个终止密码子。我们已经确定了小鼠Clc1基因的基因组结构以及Clc1adr等位基因中转座子插入的序列要求。小鼠Clc1基因由23个外显子组成，长度从39到372 bp不等，跨越约23 kb的基因组DNA。外显子/内含子结构与人类CLCN1基因高度同源；编码序列与大鼠的同源性为97%，与人类的同源性为89%。在adr等位基因中，ETn转座子插入到最大的内含子12中。虽然ETn转座子的5'和3' LTR序列与报道的小鼠其他插入突变的序列同源，但无法确定插入靶位点的共有基序。基于侧翼序列，我们提供了针对Clc1的adr、adr-mto和野生型等位基因的双重PCR诊断方法。在内含子12的3'端附近，发现了一个四核苷酸重复序列（AATC）n，它在小家鼠、社鼠、栗鼠和西班牙小鼠之间具有多态性，因此可用于染色体定位研究。
