Project description:Carotenoids are naturally occurring pigments in plants responsible for the orange, yellow, and red color of fruits and vegetables. Carrots are one of the primary dietary sources of carotenoids. The biological activities of carotenoids in higher organisms are well documented in most tissues but not the large intestine. The gastrointestinal barrier acts as a line of defense against the systemic invasion of pathogenic bacteria, especially at the colonic level. Proteins involved in tight junction assembly between epithelial cells and mucus secretion from goblet cells are essential for maintaining intestinal barrier homeostasis. A high-fat diet can cause gut impairment by inducing barrier permeability, leading to low-grade chronic inflammation via metabolic endotoxemia. Our hypothesis for this study is that the dietary intake of carotenoid-rich foods can alleviate obesity-associated gut inflammation and strengthen the intestinal barrier function. Male C57BL/6J mice were randomized to one of four experimental diets for 20 weeks (n = 20 animals/group): Low-fat diet (LFD, 10% calories from fat), high-fat diet (HFD, 45% calories from fat), HFD with white carrot powder (HFD + WC), or HFD with orange carrot powder (HFD + OC). Colon tissues were harvested to analyze the biochemical effects of carotenoids in carrots. The distal sections were subjected to isobaric labeling-based quantitative proteomics in which tryptic peptides were labeled with tandem mass tags, followed by fractionation and LC-MS/MS analysis in an Orbitrap Eclipse Tribrid instrument. High-performance liquid chromatography results depicted that the HFD+WC pellets were carotenoid-deficient, and the HFD+OC pellets contained high concentrations of provitamin A carotenoids, specifically α-carotene and β-carotene. As a result of the quantitative proteomics, a total of 4410 differentially expressed proteins were identified. Intestinal barrier-associated proteins were highly upregulated in the HFD+OC group, particularly mucin-2 (MUC-2). Upon closer investigation into mucosal activity, other proteins related to MUC-2 functionality and tight junction management were upregulated by the HFD+OC dietary intervention. Carotenoid-rich foods may prevent high-fat diet-induced intestinal barrier disruption by promoting colonic mucus synthesis and secretion in mammalian organisms.

Project description:Inflammatory bowel disease (IBD) is a complex and relapsing inflammatory disease, and patients with IBD exhibit a higher risk of developing colorectal cancer (CRC). Epithelial barrier disruption is one of the major causes of inflammatory bowel disease (IBD) in which epigenetic modulations are pivotal elements. However, the epigenetic mechanisms underlying the epithelial barrier integrity regulation remain largely unexplored. Here, we investigated how SETD2, a histone H3K36 trimethyltransferase, maintains intestinal epithelial homeostasis under inflammatory conditions. GEO public database and IBD tissues were used to investigate the clinical relevance of SetD2 in IBD. To define the role of SetD2 in the colitis, we generated mice with epithelial-specific deletion of Setd2 (Setd2Vil-KO mice). Acute colitis was induced by 2% dextran sodium sulfate (DSS), and colitis-associated CRC was induced by injecting azoxymethane (AOM), followed by three cycles of 2% DSS treatments. Colon tissues were collected from mice and analyzed by histology, immunohistochemistry and immunoblots. Organoids were generated from Setd2Vil-KO and control mice, and were stained with 7-AAD to detect apoptosis. We isolated intestinal epithelial cells (IECs), performed RNA-seq and H3K36me3 ChIP-seq analysis to uncover the mechanism. Results were validated in functional rescue experiments by N-acetyl-l-cysteine (NAC) treatment and transgenes expression in IECs. SETD2 expression was decreased in IBD patients and DSS-treated colitis mice. Setd2Vil-KO mice had abnormal loss of mucosa-producing goblet cells and antimicrobial peptide (AMP)-producing Paneth cells, and promoted early intestinal inflammation development. Consistent with the reduced SETD2 expression in IBD patients, Setd2Vil-KO mice exhibited increased susceptibility to DSS-induced colitis, accompanied by more severe epithelial barrier disruption. Intestinal permeability was markedly increased in Setd2Vil-KO mice. Setd2 ablation drived inﬂammation-associated CRC. Deletion of Setd2 resulted in excess reactive oxygen species (ROS), which led to cellular apoptosis and the defects in barrier integrity. N-acetyl-l-cysteine (NAC) treatment in Setd2Vil-KO mice rescued epithelial barrier injury and apoptosis. Moreover, overexpression of antioxidase PRDX6 in Setd2Vil-KO IECs largely alleviated the overproductions of ROS and improved the cellular survival. Deficiency of Setd2 specifically in the intestine aggravates epithelial barrier disruption and inflammatory response in colitis via a mechanism dependent on oxidative stress. More importantly, we show that Setd2 depletion results in excess ROS by directly down-regulating PRDX6, an antioxidant protein that inhibit excess ROS. Thus, our results highlight an epigenetic mechanism by which Setd2 mediates oxidative stress to modulate intestinal epithelial homeostasis.

			Action	DRS
	23P06840001.mgf	Mgf
	23P06840001.raw	Raw
	23P06840002.mgf	Mgf
	23P06840002.raw	Raw
	23P06840003.mgf	Mgf

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F-actin dynamics couples sphingolipid metabolism to epithelial barrier integrity in chronic colitis (proteomics)

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