大鼠耳蜗α_(1D)L-型电压门控钙通道组织特异性异构体的剪切方式及其意义

目的　研究α1DL 型电压门控钙通道基因在大鼠耳蜗的剪切 (splicing )方式及其意义。 方法　以显微解剖取材的大鼠耳蜗基底膜为起始材料 ,利用外显子特异性 (exon specific)引物的RT PCR扩增和序列测定确定耳蜗表达的α1DL 型电压门控钙通道的剪切方式。结果　耳蜗表达的α1D钙通道cDNA剪切部位发生在功能域Ⅰ、Ⅱ之间的细胞内连接区和羧基末端。结论　大鼠耳蜗存在α1D钙通道组织特异性的剪切异构体 ,选择性剪切可能是内耳基因表达调控的重要机制

The alternative tissue specific splicing pattern of α1DL-type voltage-gated Ca2+ channel in the rat cochlea

Objective To investigate the tissue specific sp li cing pattern of α 1D L-type of voltage-gated Ca 2+ chan nel in cochlea. Methods A relatively pure preparation of the organ of Corti was obtained by microdissection. The possible alternative splicing exons were a mplified by exon-specific RT-PCR. The products were cloned and sequenced to de termine the splicing pattern in cochlea. Results The α 1D mRNA in rat cochlea was spli ced in a tissue-specific manner: 63bp was exluded from mature mRNA in exon3 and the exon12 was deleted in Ⅰ-Ⅱ loop. There were three splicing patterns in ca rboxyl terminus: one (type A) was similar to the isoform cloning from pancreatic β cell, but the isoform expressed in β cell lacked exon46; the second splicing variant (type B) existed predominantly in cochlea which lacked 153bp a t the beginning of exon48; the third splicing pattern (type C) only exited in co chlea and exon44-46 were excluded, which could produce a mRNA with a short carb oxyl ternimus. Conclusion The splicing of the α 1DmRNA contributes to the unusual dynamics of the hair cell s voltage-gated Ca 2+ channels, and alternative splicing is an important way to regulate the gene expression in cochlea.