Schleef M, Zühlke C, Schöffl F, Jockusch H
University of Bielefeld, Developmental Biology Unit, Germany.
Neuromuscul Disord. 1994 May;4(3):205-17. doi: 10.1016/0960-8966(94)90021-3.
In myotonic ADR mice that are homozygous for a defect in the muscular chloride channel gene adr/Clc-1, the hyperexcitability of fast muscles is associated with secondary changes in gene expression and fibre type composition. cDNA clones derived from a set of genes down regulated in fast muscles of the myotonic ADR mouse were isolated by a subtractive cloning procedure. A total of 1200 clones were analysed for high expression in fast muscle of wild type and low expression in mutant mouse. Differential transcript levels were verified by northern blot hybridizations. The identities of the corresponding transcripts were determined by sequencing as myosin heavy chain IIB, alpha-tropomyosin, troponin C, a Ca2+ ATPase and parvalbumin mRNAs. Of these, mRNAs for parvalbumin and myosin heavy chain IIB were drastically downregulated in myotonic muscle (to < 10% of control). A full length cDNA clone for skeletal muscle alpha-tropomyosin was homologous to the mouse fibroblast tropomyosin isoform 2, except for the portion encoding the alpha-tropomyosin specific amino acids 258-284. A cDNA derived from the 1100 nucleotide parvalbumin transcript was cloned and the sequence for the as yet unknown 3' extended trailer, generated by alternative polyadenylation, was determined.
在肌强直ADR小鼠中，其肌肉氯离子通道基因adr/Clc-1存在缺陷且为纯合子，快肌的兴奋性过高与基因表达和纤维类型组成的继发性变化相关。通过消减克隆程序，从肌强直ADR小鼠快肌中下调的一组基因衍生出的cDNA克隆被分离出来。总共分析了1200个克隆，以确定其在野生型快肌中的高表达和在突变小鼠中的低表达情况。通过Northern印迹杂交验证了差异转录水平。通过测序确定相应转录本的身份为肌球蛋白重链IIB、α-原肌球蛋白、肌钙蛋白C、一种Ca2+ATP酶和小白蛋白mRNA。其中，小白蛋白和肌球蛋白重链IIB的mRNA在肌强直肌肉中显著下调（降至对照的<10%）。骨骼肌α-原肌球蛋白的全长cDNA克隆与小鼠成纤维细胞原肌球蛋白同工型2同源，除了编码α-原肌球蛋白特异性氨基酸258-284的部分。克隆了源自1100个核苷酸小白蛋白转录本的cDNA，并确定了由可变聚腺苷酸化产生的尚未知的3'延伸尾的序列。
