脆性X智力低下1(Fmr1)的缺乏导致其编码蛋白FMRP的丢失,并通过以与年龄相关的方式失调其靶基因表达而引起脆性X综合征(FXS)。使用比较蛋白质组学分析,这项研究确定了出生后第7天(P7)Fmr1-/y小鼠海马中的105种差异表达蛋白(DEP)和P90Fmr1-/y小鼠的306种DEP。我们发现P90海马中的大多数DEP在FMRP缺失后在P7海马中没有改变,一些P90DEP表现出不同的蛋白表型,蛋白亚型或等位基因变体表达异常。生物信息学分析表明,P7DEP主要富集在脂肪酸代谢和氧化还原酶活性以及营养响应中;而P90PEP(尤其是下调的DEP)主要富集在突触后密度(PSD)中。神经元投射发育和突触可塑性。有趣的是,在最富集的蛋白质与蛋白质相互作用网络中存在的30种下调的PSD蛋白中,有25种和其中6个(ANK3,ATP2B2,DST,GRIN1,SHANK2和SYNGAP1)都是FMRP靶标和自闭症候选者。因此,本研究提示FMRP缺失后海马蛋白质组的年龄依赖性改变,这可能与FXS及其相关疾病的发病机制有关.意义:众所周知,由Fmr1缺乏导致的FMRP丧失导致脆性X综合征(FXS),一种常见的神经发育障碍,伴有智力障碍和自闭症谱系障碍(ASD)。FMRP在早期发育和成年期之间的海马中表现出明显的时空模式,在两个年龄阶段FMRP丢失后,导致基因表达的明显失调,这可能与年龄相关的表型有关。因此,比较婴儿期和成年期之间的海马蛋白质组对于了解FXS和ASD的早期原因和成人依赖性后果很有价值。使用比较蛋白质组学分析,这项研究鉴定了出生后第7天(P7)和P90Fmr1-/y小鼠海马中的105和306个差异表达蛋白(DEP),分别。在P7和P90阶段之间很少发现重叠的DEP,P7DEPs主要富集在脂肪酸代谢和氧化还原的调节中,而P90DEP优先富集在突触形成和可塑性的调节中。特别是,上调的P90蛋白主要参与免疫反应和神经变性,下调的P90蛋白与突触后密度有关,神经元投射和突触可塑性。我们的发现表明,婴儿期和成年期之间缺乏FMRP的海马中明显变化的蛋白质可能有助于FXS和ASD的年龄依赖性发病机理。
Deficiency in fragile X mental retardation 1 (Fmr1) leads to loss of its encoded protein FMRP and causes fragile X syndrome (FXS) by dysregulating its target gene expression in an age-related fashion. Using comparative proteomic analysis, this study identified 105 differentially expressed proteins (DEPs) in the hippocampus of postnatal day 7 (P7) Fmr1-/y mice and 306 DEPs of P90 Fmr1-/y mice. We found that most DEPs in P90 hippocampus were not changed in P7 hippocampus upon FMRP absence, and some P90 DEPs exhibited diverse proteophenotypes with abnormal expression of protein isoform or allele variants. Bioinformatic analyses showed that the P7 DEPs were mainly enriched in fatty acid metabolism and oxidoreductase activity and nutrient responses; whereas the P90 PEPs (especially down-regulated DEPs) were primarily enriched in postsynaptic density (PSD), neuronal projection development and synaptic plasticity. Interestingly, 25 of 30 down-regulated PSD proteins present in the most enriched protein to protein interaction network, and 6 of them (ANK3, ATP2B2, DST, GRIN1, SHANK2 and SYNGAP1) are both FMRP targets and autism candidates. Therefore, this study suggests age-dependent alterations in hippocampal proteomes upon loss of FMRP that may be associated with the pathogenesis of FXS and its related disorders. SIGNIFICANCE: It is well known that loss of FMRP resulted from Fmr1 deficiency leads to fragile X syndrome (FXS), a common neurodevelopmental disorder accompanied by intellectual disability and autism spectrum disorder (ASD). FMRP exhibits distinctly spatiotemporal patterns in the hippocampus between early development and adulthood, which lead to distinct dysregulations of gene expression upon loss of FMRP at the two age stages potentially linked to age-related phenotypes. Therefore, comparison of hippocampal proteomes between infancy and adulthood is valuable to provide insights into the early causations and adult-dependent consequences for FXS and ASD. Using a comparative proteomic analysis, this study identified 105 and 306 differentially expressed proteins (DEPs) in the hippocampi of postnatal day 7 (P7) and P90 Fmr1-/y mice, respectively. Few overlapping DEPs were identified between P7 and P90 stages, and the P7 DEPs were mainly enriched in the regulation of fatty acid metabolism and oxidoreduction, whereas the P90 DEPs were preferentially enriched in the regulation of synaptic formation and plasticity. Particularly, the up-regulated P90 proteins are primarily involved in immune responses and neurodegeneration, and the down-regulated P90 proteins are associated with postsynaptic density, neuron projection and synaptic plasticity. Our findings suggest that distinctly changed proteins in FMRP-absence hippocampus between infancy and adulthood may contribute to age-dependent pathogenesis of FXS and ASD.