Dong Yang, Newman Morgan, Pederson Stephen M, Barthelson Karissa, Hin Nhi, Lardelli Michael
Alzheimer's Disease Genetics Laboratory, School of Biological Sciences, University of Adelaide, North Terrace, Adelaide, SA, 5005, Australia.
Bioinformatics Hub, School of Biological Sciences, University of Adelaide, North Terrace, Adelaide, SA, 5005, Australia.
BMC Genomics. 2021 Mar 24;22(1):211. doi: 10.1186/s12864-021-07509-1.
Early-onset familial Alzheimer's disease (EOfAD) is promoted by dominant mutations, enabling the study of Alzheimer's disease (AD) pathogenic mechanisms through generation of EOfAD-like mutations in animal models. In a previous study, we generated an EOfAD-like mutation, psen1, in zebrafish and performed transcriptome analysis comparing entire brains from 6-month-old wild type and heterozygous mutant fish. We identified predicted effects on mitochondrial function and endolysosomal acidification. Here we aimed to determine whether similar effects occur in 7 day post fertilization (dpf) zebrafish larvae that might be exploited in screening of chemical libraries to find ameliorative drugs.
We generated clutches of wild type and heterozygous psen1 7 dpf larvae using a paired-mating strategy to reduce extraneous genetic variation before performing a comparative transcriptome analysis. We identified 228 differentially expressed genes and performed various bioinformatics analyses to predict cellular functions.
Our analyses predicted a significant effect on oxidative phosphorylation, consistent with our earlier observations of predicted effects on ATP synthesis in adult heterozygous psen1 brains. The dysregulation of minichromosome maintenance protein complex (MCM) genes strongly contributed to predicted effects on DNA replication and the cell cycle and may explain earlier observations of genome instability due to PSEN1 mutation. The upregulation of crystallin gene expression may be a response to defective activity of mutant Psen1 protein in endolysosomal acidification. Genes related to extracellular matrix (ECM) were downregulated, consistent with previous studies of EOfAD mutant iPSC neurons and postmortem late onset AD brains. Also, changes in expression of genes controlling iron ion transport were observed without identifiable changes in the prevalence of transcripts containing iron responsive elements (IREs) in their 3' untranslated regions (UTRs). These changes may, therefore, predispose to the apparent iron dyshomeostasis previously observed in 6-month-old heterozygous psen1 EOfAD-like mutant brains.
早发性家族性阿尔茨海默病（EOfAD）由显性突变引发，这使得通过在动物模型中产生类似EOfAD的突变来研究阿尔茨海默病（AD）的致病机制成为可能。在先前的一项研究中，我们在斑马鱼中产生了一种类似EOfAD的突变体psen1，并对6月龄野生型和杂合突变体鱼的全脑进行了转录组分析比较。我们确定了对线粒体功能和内溶酶体酸化的预测影响。在此，我们旨在确定在受精后7天（dpf）的斑马鱼幼虫中是否会出现类似影响，这可能有助于筛选化学文库以寻找改善药物。
我们采用配对交配策略产生野生型和杂合psen1 7 dpf幼虫的批次，以减少无关的遗传变异，然后进行比较转录组分析。我们鉴定出228个差异表达基因，并进行了各种生物信息学分析以预测细胞功能。
我们的分析预测对氧化磷酸化有显著影响，这与我们早期对成年杂合psen1脑内ATP合成预测影响的观察结果一致。微小染色体维持蛋白复合体（MCM）基因的失调对DNA复制和细胞周期的预测影响有很大贡献，并且可能解释了先前因PSEN1突变导致基因组不稳定的观察结果。晶状体蛋白基因表达的上调可能是对内溶酶体酸化中突变Psen1蛋白活性缺陷的一种反应。与细胞外基质（ECM）相关的基因被下调，这与先前对EOfAD突变诱导多能干细胞（iPSC）神经元和死后晚发性AD脑的研究一致。此外，观察到控制铁离子转运的基因表达发生变化，但其3'非翻译区（UTR）中含有铁反应元件（IRE）的转录本丰度没有明显变化。因此，这些变化可能导致先前在6月龄杂合psen1 EOfAD样突变体脑中观察到的明显铁稳态失调。
