Lee Mi-Heon, Salvaterra Paul M
Division of Neuroscience, Beckman Research Institute of the City of Hope, Duarte, California 91010, USA.
J Neurosci. 2002 Jul 1;22(13):5291-9. doi: 10.1523/JNEUROSCI.22-13-05291.2002.
Cholinergic neurons acquire their neurotransmitter phenotype, in part, by expressing the cholinergic gene locus. Previous studies have indicated that the 5' flanking DNA of the locus contains both positive and negative regulatory elements important for expression in different subsets of cholinergic neurons in Drosophila and other animals. Approximately 300 bases of proximal 5' flanking DNA control expression in Drosophila CNS neurons essential for viability, whereas more distal regulatory elements are important for expression in PNS sensory neurons. In this study we identify the POU domain transcription factor abnormal chemosensory jump 6 (Acj6) as a necessary positive transcriptional regulator for cholinergic locus expression in primary olfactory neurons. Choline acetyltransferase enzyme activity, protein levels, mRNA, and a fluorescent cholinergic reporter gene are all decreased in olfactory neurons of acj6 mutants. Decreased cholinergic expression was observed in both adults and larvae. The presence of a specific Acj6 binding site has been identified in the cholinergic locus 5' flanking DNA, suggesting that Acj6 may play a direct role in specifying the cholinergic neurotransmitter phenotype of most olfactory neurons. Transgenic expression of two different isoforms of Acj6 restricted to olfactory neurons indicates that additional trans factors may be required for cholinergic locus expression. Transgenic expression in all cholinergic neurons, however, results in lethality when a POU IV box element is absent but is essentially benign when present, indicating the importance of this motif in specifying different functional roles for Acj6.
胆碱能神经元部分通过表达胆碱能基因座来获得其神经递质表型。先前的研究表明，该基因座的5'侧翼DNA包含对果蝇和其他动物中不同胆碱能神经元亚群的表达至关重要的正向和负向调控元件。果蝇中枢神经系统神经元中约300个碱基的近端5'侧翼DNA控制着对生存至关重要的表达，而更远端的调控元件对周围神经系统感觉神经元的表达很重要。在本研究中，我们确定POU结构域转录因子异常化学感受跳跃6（Acj6）是初级嗅觉神经元中胆碱能基因座表达所必需的正向转录调节因子。在acj6突变体的嗅觉神经元中，胆碱乙酰转移酶活性、蛋白质水平、mRNA和荧光胆碱能报告基因均降低。在成虫和幼虫中均观察到胆碱能表达降低。在胆碱能基因座5'侧翼DNA中已鉴定出一个特定的Acj6结合位点，这表明Acj6可能在确定大多数嗅觉神经元的胆碱能神经递质表型中起直接作用。限于嗅觉神经元的两种不同Acj6同工型的转基因表达表明，胆碱能基因座表达可能需要其他转录因子。然而，当不存在POU IV盒元件时，在所有胆碱能神经元中的转基因表达会导致致死性，但当存在时基本上是无害的，这表明该基序在确定Acj6的不同功能作用中的重要性。
