title: Zinc enhances intestinal epithelial barrier function through the PI3K/AKT/mTOR signaling pathway in Caco-2 cells.
abstract: Zinc plays an important role in maintaining intestinal barrier function as well as modulating cellular signaling recognition and protein kinase activities. The phosphatidylinositol 3-kinase (PI3K) cascade has been demonstrated to affect intercellular integrity and tight junction (TJ) proteins. The current study investigated the hypothesis that zinc regulates intestinal intercellular junction integrity through the PI3K/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway. A transwell model of Caco-2 cell was incubated with 0, 50 and 100 μM of zinc at various time points. Transepithelial electrical resistance (TEER), paracellular permeability, TJ proteins, cell proliferation, differentiation and cell damage were measured. Compared with controls, 50 and 100 μM of zinc increased cell growth at 6, 12 and 24 h and the expression of proliferating cell nuclear antigen at 24 h. Zinc (100 μM) significantly elevated TEER at 6-24 h and reduced TJ permeability at 24 h, accompanied by the up-regulation of alkaline phosphatase (AP) activity and zonula occludens (ZO)-1 expression. In addition, zinc (100 μM) affected the PI3K/AKT/mTOR pathway by stimulating phosphorylation of AKT and the downstream target mTOR. Inhibition of PI3K signaling by LY294002 counteracted zinc promotion, as shown by a decrease in AP activity, TEER, the abundance of ZO-1 and phosphorylation of AKT and mTOR. Additionally, TJ permeability and the expression of caspase-3 and LC3II (markers of cell damage) were increased by addition of PI3K inhibitor. In conclusion, the activation of PI3K/AKT/mTOR signaling by zinc is involved in improving intestinal barrier function by enhancing cell differentiation and expression of TJ protein ZO-1.
authors.affiliation: State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Yuanmingyuan West Road, Haidian District, Beijing, 100193, China.
authors.forename: Yuxin
authors.initials: Y
authors.lastname: Shao
authors.affiliation: Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, 1207 W. Gregory Ave., Urbana, IL, 61801, USA.
authors.forename: Patricia G
authors.initials: PG
authors.lastname: Wolf
authors.affiliation: State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Yuanmingyuan West Road, Haidian District, Beijing, 100193, China.
authors.forename: Shuangshuang
authors.initials: S
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Yuanmingyuan West Road, Haidian District, Beijing, 100193, China.
authors.forename: Yuming
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, 1207 W. Gregory Ave., Urbana, IL, 61801, USA; Department of Animal Sciences, University of Illinois at Urbana-Champaign, 1207 W. Gregory Ave., Urbana, IL, 61801, USA; Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1207 W. Gregory Ave., Urbana, IL, 61801, USA.
authors.forename: H Rex
authors.initials: HR
authors.lastname: Gaskins
authors.affiliation: State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Yuanmingyuan West Road, Haidian District, Beijing, 100193, China. Electronic address: bingkunzhang@126.com.
authors.forename: Bingkun
authors.initials: B
authors.lastname: Zhang
mesh_terms: D018938:Caco-2 Cells; D049109:Cell Proliferation / Q000187:drug effects; D002867:Chromones / Q000494:pharmacology; D019587:Dietary Supplements; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000166:cytology / Q000187:drug effects; D009025:Morpholines / Q000494:pharmacology; D062793:Occludin / Q000235:genetics / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D015032:Zinc / Q000494:pharmacology*; D062826:Zonula Occludens-1 Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D002867:Chromones; D004791:Enzyme Inhibitors; D009025:Morpholines; D062793:Occludin; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D015032:Zinc; D062826:Zonula Occludens-1 Protein; C568985:OCLN protein, human; C569042:TJP1 protein, human; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C546842:MTOR protein, human
keywords: Barrier function; Caco-2 cells; PI3K/AKT/mTOR; Tight junction protein; Zinc