Mukherjee Richa S, Hausman Robert E
Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, USA.
Brain Res Mol Brain Res. 2004 Oct 22;129(1-2):54-66. doi: 10.1016/j.molbrainres.2004.06.014.
The enzyme choline acetyltransferase [EC 2.3.1.6] (ChAT) synthesizes the neurotransmitter acetylcholine that plays a key morphogenic role in vertebrate retina development. As the embryonic avian retina is particularly useful for morphogenetic studies, we cloned the complete coding region of chicken ChAT cDNA. At the deduced amino acid level, chicken ChAT is approximately 76% identical to mammalian ChAT proteins. We also report here the cloning of the complete 5' end of the complex cholinergic locus. This locus contains both the ChAT gene and the nested intronless gene for the vesicular acetylcholine transporter (VAChT). The genomic organization of the 5' end of the chicken cholinergic locus is similar to that reported in other vertebrate species. A 5.7 kb mRNA corresponding to the ChAT message was detected in both embryonic retina and post-hatch brain. An analysis of the ChAT mRNA in embryonic chick retina shows that the message can be detected by E6 and its level increased during early retinal development. Vertebrate ChAT mRNAs can contain one or more of three non-coding exons, M, N or R and by RT-PCR we demonstrate, at least, a chicken ChAT mRNA containing exon M.
胆碱乙酰转移酶EC 2.3.1.6可合成神经递质乙酰胆碱，该递质在脊椎动物视网膜发育中发挥关键的形态发生作用。由于胚胎期禽类视网膜对形态发生研究特别有用，我们克隆了鸡ChAT cDNA的完整编码区。在推导的氨基酸水平上，鸡ChAT与哺乳动物ChAT蛋白的相似度约为76%。我们在此还报告了复杂胆碱能基因座完整5'端的克隆情况。该基因座既包含ChAT基因，也包含囊泡乙酰胆碱转运体(VAChT)的嵌套无内含子基因。鸡胆碱能基因座5'端的基因组组织与其他脊椎动物物种中报道的相似。在胚胎视网膜和孵化后大脑中均检测到了一条与ChAT信息相对应的5.7 kb mRNA。对胚胎期鸡视网膜中ChAT mRNA的分析表明，在胚胎第6天(E6)即可检测到该信息，且其水平在视网膜早期发育过程中有所增加。脊椎动物ChAT mRNA可包含三个非编码外显子M、N或R中的一个或多个，通过逆转录聚合酶链反应(RT-PCR)我们证明，至少有一种鸡ChAT mRNA包含外显子M。
