PDF(Pubmed)
Abstract：
Several probiotic-derived factors have been identified as effectors of probiotics for exerting beneficial effects on the host. However, there is a paucity of studies to elucidate mechanisms of their functions. p40, a secretory protein, is originally isolated from a probiotic bacterium, Lactobacillus rhamnosus GG. Thus, this study aimed to apply structure-functional analysis to define the functional peptide of p40 that modulates the epigenetic program in intestinal epithelial cells for sustained prevention of colitis. In silico analysis revealed that p40 is composed of a signal peptide (1-28 residues) followed by a coiled-coil domain with uncharacterized function on the N-terminus, a linker region, and a β-sheet domain with high homology to CHAP on the C-terminus. Based on the p40 three-dimensional structure model, two recombinant p40 peptides were generated, p40N120 (28-120 residues) and p40N180 (28-180 residues) that contain first two and first three coiled coils, respectively. Compared to full-length p40 (p40F) and p40N180, p40N120 showed similar or higher effects on up-regulating expression of Setd1b (encoding a methyltransferase), promoting mono- and trimethylation of histone 3 on lysine 4 (H3K4me1/3), and enhancing Tgfb gene expression and protein production that leads to SMAD2 phosphorylation in human colonoids and a mouse colonic epithelial cell line. Furthermore, supplementation with p40F and p40N120 in early life increased H3K4me1, Tgfb expression and differentiation of regulatory T cells (Tregs) in the colon, and mitigated disruption of epithelial barrier and inflammation induced by DSS in adult mice. This study reveals the structural feature of p40 and identifies a functional peptide of p40 that could maintain intestinal homeostasis.
摘要：
几种益生菌衍生因子已被鉴定为益生菌对宿主发挥有益作用的效应物。然而,缺乏阐明其功能机制的研究。p40，一种分泌蛋白，最初是从益生菌中分离出来的，鼠李糖乳杆菌GG。因此，本研究旨在应用结构功能分析来定义p40的功能肽，该肽可调节肠上皮细胞的表观遗传程序，以持续预防结肠炎。计算机分析显示，p40由信号肽（1-28个残基）组成，然后是在N端具有未表征功能的卷曲螺旋结构域。一个接头区，和在C末端与CHAP具有高度同源性的β-折叠结构域。基于p40三维结构模型,产生了两种重组p40肽，p40N120（28-120个残基）和p40N180（28-180个残基）含有前两个和前三个卷曲螺旋，分别。与全长p40（p40F）和p40N180相比，p40N120对Sett1b（编码甲基转移酶）的上调表达显示出相似或更高的作用，促进组蛋白3在赖氨酸4（H3K4me1/3）上的单-和三甲基化，并增强Tgfb基因表达和蛋白质产生，从而导致人结肠样细胞和小鼠结肠上皮细胞系的SMAD2磷酸化。此外，在生命早期补充p40F和p40N120会增加H3K4me1，Tgfb的表达和结肠中调节性T细胞（Tregs）的分化，减轻DSS诱导的成年小鼠上皮屏障破坏和炎症反应。这项研究揭示了p40的结构特征，并鉴定了p40的功能肽，可以维持肠道稳态。
