López-Casillas F, Kim K H
Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907.
J Biol Chem. 1989 May 5;264(13):7176-84.
Multiple forms of acetyl-CoA carboxylase mRNA were previously detected in the mammary gland (Lopez-Casillas, F., Luo, X., Kong, I.-S., and Kim, K.-H. (1989) Gene, in press). We have now established that the rat liver also contains heterogeneous acetyl-CoA carboxylase mRNA populations that differ in the 5'-untranslated region. In addition, the liver contains a unique form of acetyl-CoA carboxylase mRNA in which the 5'-nontranslated end differs from the species in mammary gland. The 5' end of this unique species was characterized using a procedure for cloning minute amounts of primer extension products (pAU clones). This procedure should also be useful for obtaining full length clones of other mRNAs. The DNA sequence of pAU clones indicates that this liver-specific acetyl-CoA carboxylase mRNA has a 315-base long untranslated region. The first 242 nucleotides replace the 5' end of the predominant acetyl-CoA carboxylase mRNA found in the mammary gland (FL56 type). Under lipogenic conditions the unique liver acetyl-CoA carboxylase mRNA increases and is the major species of acetyl-CoA carboxylase mRNA. Livers from rats fed a normal diet and the mammary glands of lactating rats do not contain detectable amounts of the pAU type mRNA. On the other hand, the epididymal adipose tissue from these animals contains mainly the pAU type and only minimal amounts of the FL56 type. The multiple forms of acetyl-CoA carboxylase mRNA appear to be generated by differential splicing. In addition, transcription appears to be physiologically regulated by the use of tissue-specific acetyl-CoA carboxylase gene promoters.
先前在乳腺中检测到多种形式的乙酰辅酶A羧化酶mRNA（洛佩斯 - 卡西利亚斯，F.，罗，X.，孔，I.-S.，和金，K.-H.（1989年）《基因》，即将发表）。我们现已确定，大鼠肝脏也含有在5'非翻译区不同的异质乙酰辅酶A羧化酶mRNA群体。此外，肝脏含有一种独特形式的乙酰辅酶A羧化酶mRNA，其5'非翻译末端与乳腺中的不同。使用克隆微量引物延伸产物的方法（pAU克隆）对这种独特类型的5'末端进行了表征。该方法对于获得其他mRNA的全长克隆也应该是有用的。pAU克隆的DNA序列表明，这种肝脏特异性乙酰辅酶A羧化酶mRNA具有315个碱基长的非翻译区。前242个核苷酸取代了乳腺中发现的主要乙酰辅酶A羧化酶mRNA（FL56型）的5'末端。在生脂条件下，独特的肝脏乙酰辅酶A羧化酶mRNA增加，并且是乙酰辅酶A羧化酶mRNA的主要类型。喂食正常饮食的大鼠肝脏和泌乳大鼠的乳腺中不含可检测量的pAU型mRNA。另一方面，这些动物的附睾脂肪组织主要含有pAU型，仅含有极少量的FL56型。乙酰辅酶A羧化酶mRNA的多种形式似乎是由差异剪接产生的。此外，转录似乎在生理上受组织特异性乙酰辅酶A羧化酶基因启动子的使用调节。
