The gut microbiome interacts with the host to maintain body homeostasis, with gut microbial dysbiosis implicated in many diseases. However, the underlying mechanisms of gut microbe regulation of host behavior and brain functions remain unclear. This study aimed to elucidate the influence of gut microbiota on brain functions via post-translational modification mechanisms in the presence or absence of bacteria without any stimulation. We conducted succinylome analysis of hippocampal proteins in germ-free (GF) and specific pathogen-free (SPF) mice and metagenomic analysis of feces from SPF mice. These results were integrated with previously reported hippocampal acetylome and phosphorylome data from the same batch of mice. Subsequent bioinformatics analyses revealed 584 succinylation sites on 455 proteins, including 54 up-regulated succinylation sites on 91 proteins and 99 down-regulated sites on 51 proteins in the GF mice compared to the SPF mice. We constructed a panoramic map of gut microbiota-regulated succinylation, acetylation, and phosphorylation, and identified cross-talk and relative independence between the different types of post-translational modifications in modulating complicated intracellular pathways. Pearson correlation analysis indicated that 13 taxa, predominantly belonging to the Bacteroidetes phylum, were correlated with the biological functions of post-translational modifications. Positive correlations between these taxa and succinylation and negative correlations between these taxa and acetylation were identified in the modulation of intracellular pathways. This study highlights the hippocampal physiological changes induced by the absence of gut microbiota, and proteomic quantification of succinylation, phosphorylation, and acetylation, contributing to our understanding of the role of the gut microbiome in brain function and behavioral phenotypes.
肠道微生物可与宿主相互作用维持机体稳态，疾病状态下肠道微生物会发生紊乱。然而，肠道微生物调控宿主脑功能和行为的机制仍不清楚。该研究旨在阐明正常小鼠和无菌小鼠在无任何刺激的情况下肠道菌群通过蛋白翻译后修饰对脑功能影响的作用机制。 我们对GF和SPF小鼠的海马组织进行了琥珀酰化蛋白修饰组学检测，并对SPF小鼠的粪便进行了宏基因组分析。同时将这些结果与之前报告的同一批次的小鼠海马乙酰化和磷酸化蛋白组数据进行整合和生物信息学分析。研究发现，与SPF组相比，GF组鉴定到了455个蛋白的584个琥珀酰化位点，其中91个蛋白的54个琥珀酰化位点表达上调，51个蛋白的99个琥珀酰化位点表达下调。进一步构建了受肠道微生物调控的琥珀酰化、乙酰化和磷酸化的蛋白修饰全景图谱，并确定了不同类型的翻译后修饰在调节复杂细胞通路中的“串扰”现象及独立作用。Pearson相关性分析显示，13个拟杆菌门与蛋白翻译后修饰的生物学功能相关。在调节细胞内通路中，这些菌与琥珀酰化修饰水平呈正相关，与乙酰化修饰水平呈负相关。该研究报道了肠道菌群缺失引起的海马生理变化，并通过蛋白修饰组学分析了其海马琥珀酰化、磷酸化和乙酰化修饰变化，将有助于促进我们对肠道微生物调控宿主大脑功能及表型的机制理解。.
Keywords: Acetylation; Gut microbiota; Hippocampal protein; Phosphorylation; Post-translational modifications; Succinylation.