Analysis of Caenorhabditis elegans acetylcholine synthesis mutants reveals a temperature-sensitive requirement for cholinergic neuromuscular function.
Analysis of Caenorhabditis elegans acetylcholine synthesis mutants reveals a temperature-sensitive requirement for cholinergic neuromuscular function.
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对秀丽隐杆线虫乙酰胆碱合成突变体的分析揭示了胆碱能神经肌肉功能对温度敏感的要求。
DOI：
10.1093/genetics/iyab078
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发表时间：
2021
期刊：
影响因子：
3.3
通讯作者：
Rand,JamesB
中科院分区：
文献类型：
--
作者：
Duerr,JanetS;McManus,JohnR;Crowell,JohnA;Rand,JamesB
在秀丽隐杆线虫中，CHA-1基因编码胆碱乙酰转移酶(ChAT)，该酶合成神经递质乙酰胆碱。我们已经分析了大量的CHA-1亚型突变，其中大部分是错义等位基因。一些纯合子Gouscha-1突变体具有大致正常的ChAT免疫反应性；许多其他等位基因导致突触免疫染色持续减少，尽管残留蛋白似乎是稳定的。无论蛋白质水平如何，几乎所有突变体的神经肌肉功能都是温度敏感的，即25°时神经肌肉功能比14°时差。我们发现温度效应与乙酰胆碱的释放无关，而是与乙酰胆碱合成过程中的变化有关。这不是一种依赖温度的发育表型，因为在20°到幼年饲养的动物，然后转移到14°或25°的2 h，其游泳和咽部泵送速率分别与在14°或25°下生长和测试的动物相似。我们还表明，温度敏感的表型并不局限于错义等位基因；相反，它们是大多数或所有严重的ha-1亚型的属性。我们认为我们的数据在物理上与突触小泡相关的ChAT蛋白模型是一致的，但不是共价的；并且囊泡相关的ChAT和细胞质(即可溶的)ChAT之间存在温度依赖的平衡。据推测，在严重的HA-1亚型中，升高温度将促进一些突变的ChAT蛋白从突触小泡中解离，从而将乙酰胆碱合成(ChAT)的位置从囊泡乙酰胆碱运输的位置上移除。这反过来会降低囊泡充盈的速度和程度，从而增加行为缺陷的严重性。
InCaenorhabditis elegans, thecha-1gene encodes choline acetyltransferase (ChAT), the enzyme that synthesizes the neurotransmitter acetylcholine. We have analyzed a large number ofcha-1hypomorphic mutants, most of which are missense alleles. Some homozygouscha-1mutants have approximately normal ChAT immunoreactivity; many other alleles lead to consistent reductions in synaptic immunostaining, although the residual protein appears to be stable. Regardless of protein levels, neuromuscular function of almost all mutants is temperature-sensitive,i.e., neuromuscular function is worse at 25°than at 14°. We show that the temperature effects are not related to acetylcholine release, but specifically to alterations in acetylcholine synthesis. This is not a temperature-dependent developmental phenotype, because animals raised at 20° to young adulthood and then shifted for 2 h to either 14° or 25° had swimming and pharyngeal pumping rates similar to animals grown and assayed at either 14° or 25°, respectively. We also show that the temperature-sensitive phenotypes are not limited to missense alleles; rather, they are a property of most or all severecha-1hypomorphs. We suggest that our data are consistent with a model of ChAT protein physically, but not covalently, associated with synaptic vesicles; and there is a temperature-dependent equilibrium between vesicle-associated and cytoplasmic (i.e., soluble) ChAT. Presumably, in severecha-1hypomorphs, increasing the temperature would promote dissociation of some of the mutant ChAT protein from synaptic vesicles, thus removing the site of acetylcholine synthesis (ChAT) from the site of vesicular acetylcholine transport. This, in turn, would decrease the rate and extent of vesicle-filling, thus increasing the severity of the behavioral deficits.