Nutrients 2016, 8(5), 272; https://doi.org/10.3390/nu8050272
Polyphenol-Rich Propolis Extracts Strengthen Intestinal Barrier Function by Activating AMPK and ERK Signaling
Kai Wang 1,2,†
, Xiaolu Jin 1,†, Yifan Chen 1, Zehe Song 1, Xiasen Jiang 1, Fuliang Hu 1,*
, Michael A. Conlon 2,*
and David L. Topping 2
, Xiaolu Jin 1,†, Yifan Chen 1, Zehe Song 1, Xiasen Jiang 1, Fuliang Hu 1,*
, Michael A. Conlon 2,*
and David L. Topping 21
College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
2
CSIRO Food and Nutrition, Adelaide 5000, Australia
†
These authors contributed equally to this work.
*
Authors to whom correspondence should be addressed.
Received: 18 March 2016 / Revised: 28 April 2016 / Accepted: 3 May 2016 / Published: 7 May 2016
Abstract
Propolis has abundant polyphenolic constituents and is used widely as a health/functional food. Here, we investigated the effects of polyphenol-rich propolis extracts (PPE) on intestinal barrier function in human intestinal epithelial Caco-2 cells, as well as in rats. In Caco-2 cells, PPE increased transepithelial electrical resistance and decreased lucifer yellow flux. PPE-treated cells showed increased expression of the tight junction (TJ) loci occludin and zona occludens (ZO)-1. Confocal microscopy showed organized expressions in proteins related to TJ assembly, i.e., occludin and ZO-1, in response to PPE. Furthermore, PPE led to the activation of AMPK, ERK1/2, p38, and Akt. Using selective inhibitors, we found that the positive effects of PPE on barrier function were abolished in cells in which AMPK and ERK1/2 signaling were inhibited. Moreover, rats fed a diet supplemented with PPE (0.3% in the diet) exhibited increased colonic epithelium ZO-1 expression. Overall, these data suggest that PPE strengthens intestinal barrier function by activating AMPK and ERK signaling and provide novel insights into the potential application of propolis for human gut health. View Full-TextKeywords:
propolis; tight junctions; Caco-2; AMPK; ERK
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Wang, K.; Jin, X.; Chen, Y.; Song, Z.; Jiang, X.; Hu, F.; Conlon, M.A.; Topping, D.L. Polyphenol-Rich Propolis Extracts Strengthen Intestinal Barrier Function by Activating AMPK and ERK Signaling. Nutrients 2016, 8, 272.
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