Propionate and Dietary Fermentable Fibers Upregulate Intestinal Heat Shock protein70 in Intestinal Caco-2 Cells and Mouse Colon

Abstract

Short-chain fatty acids (SCFAs), including propionate, are major metabolites of intestinal microorganisms and play an essential role in regulating intestinal epithelial integrity. Heat shock proteins (HSPs) promote cellular homeostasis under physiological and stressed conditions. This study aimed to investigate the regulation of intestinal HSP70 by propionate in human intestinal Caco-2 cells and the colon of fermentable dietary fiber (DF)-fed mice and germ-free mice. The results showed that propionate increased Hspa1a (HSP70 mRNA) level in Caco-2 cells, upregulated HSP70 protein, and phosphorylation of heat shock factor 1; however, the latter two were reduced by mitogen-activated protein kinases and the mechanistic target of rapamycin inhibitors. Feeding fermentable DFs, such as guar gum (GG) and partially hydrolyzed GG, increased both cecal SCFAs and colonic HSP70 expression, both of which were reduced in germ-free mice than in specific-pathogen-free mice. Collectively, the propionate-induced HSP70 expression was shown to be possibly involved in intestinal homeostasis.

Partially hydrolyzed guar gum upregulates heat shock protein 27 in intestinal Caco‐2 cells and mouse intestine viamTOR and ERK signaling

“…Caco‐2 cells were cultured in Dulbecco's modified Eagle's medium supplemented with 100 mL L −1 fetal bovine serum and penicillin–streptomycin solution. Cells were propagated and maintained as previously described 13 . Cultures from passages 49 and 70 were used in the present study.…”

“…Protein of Caco-2 cells were extracted with an appropriate volume of lysis buffer [30 m mol L −1 Tris containing sodium dodecyl sulfate (10 g L −1 ), Triton X-100 (10 mL L −1 ), and sodium deoxycholate (1 g L −1 ), with protease and phosphatase inhibitor addition at pH 7.4]. 13 Twenty-microgram protein extracts, which were previously mixed with half a volume of Laemmli sample buffer (3×), were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transferred to polyvinylidene difluoride membranes (Immobilon®-P; Merck Millipore, Billerica, MA, USA). Membranes were blocked with 50 mg mL −1 skim milk in Trisbuffered saline with 0.5 mL L −1 Tween (TBS-T) for 1 h, at ambient temperature.…”

“…Cells were propagated and maintained as previously described. 13 Cultures from passages 49 and 70 were used in the present study. The culture mediums were refreshed every 3 days, and the cells were used for the experiment on days 13-15 after seeding.…”

Health Benefits and Side Effects of Short-Chain Fatty Acids

“…Heat shock proteins (HSP) play a crucial role in maintaining and protecting the integrity of intestinal epithelial cells. Propionate contributed to intestinal homeostasis via increasing the level of Hspa1a (a major transcript of HSP70), up-regulating HSP70, and phosphorylating heat shock factor 1 [ 76 ]. Moreover, the transcriptional activation of HSP70 was proven to be related to the activation of mitogen-activated protein kinase (MEK)/ extracellular signal-regulated kinase (ERK) and mTOR pathways, as well as the inhibition of HDAC [ 76 ].…”

“…Propionate contributed to intestinal homeostasis via increasing the level of Hspa1a (a major transcript of HSP70), up-regulating HSP70, and phosphorylating heat shock factor 1 [ 76 ]. Moreover, the transcriptional activation of HSP70 was proven to be related to the activation of mitogen-activated protein kinase (MEK)/ extracellular signal-regulated kinase (ERK) and mTOR pathways, as well as the inhibition of HDAC [ 76 ]. Besides, acetate increased the expression of MUC2 and CDX2, as well as the production of mucin proteins, in mucus-secreting colon epithelial cells (HT29-MTX), which indicated that it could improve the intestinal epithelium protective function [ 77 ].…”