Exogenous NAD+ Stimulates MUC2 Expression in LS 174T Goblet Cells via the PLC-Delta/PTGES/PKC-Delta/ERK/CREB Signaling Pathway.

Seongho Ma,Jiah Yeom,Young-Hee Lim

doi:10.3390/biom10040580

Seongho Ma, Jiah Yeom + Show 1 more

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https://doi.org/10.3390/biom10040580

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Journal: Biomolecules	Publication Date: Apr 9, 2020
Citations: 7	License type: CC BY 4.0

Affiliation: Korea University, Korea University Medical Center

Abstract

Background: MUC2, a major component of the mucus layer in the intestine, is associated with antimicrobial activity and gut immune system function. Currently, mucin is mainly known for its critical function in defense against toxic molecules and pathogens. In this study, we investigated the stimulatory effects of exogenous nicotinamide adenine dinucleotide (NAD+) on the expression of MUC2 in LS 174T goblet cells. Methods: Genes related to MUC2 synthesis were measured by quantitative real-time PCR (qPCR). To analyze the gene expression profiles of NAD+-treated LS 174T goblet cells, RNA sequencing was performed. MUC2 expression in the cells and secreted MUC2 were measured by immunocytochemistry (ICC) and ELISA, respectively. Results: NAD+ significantly stimulated MUC2 expression at mRNA and protein levels and increased the secretion of MUC2. Through RNA sequencing, we found that the expression of genes involved in arachidonic acid metabolism increased in NAD+-treated cells compared with the negative control cells. NAD+ treatment increased phospholipase C (PLC)-δ and prostaglandin E synthase (PTGES) expression, which was inhibited by the appropriate inhibitors. Among the protein kinase C (PKC) isozymes, PKC-δ was involved in the increase in MUC2 expression. In addition, extracellular signal-regulated kinase (ERK)1/2 and cyclic AMP (cAMP) response element-binding protein (CREB) transcript levels were higher in NAD+-treated cells than in the negative control cells, and the enhanced levels of phosphorylated CREB augmented MUC2 expression. Conclusions: Exogenous NAD+ increases MUC2 expression by stimulating the PLC-δ/PTGES/PKC-δ/ERK/CREB signaling pathway.

Highlights

The mucus layer in the intestine is mainly composed of mucin glycoproteins that are secreted from intestinal goblet cells
We found that oxyresveratrol, an antioxidant stilbenoid, stimulated MUC2 synthesis and increased NAD+ levels by activating enzymes involved in the salvage pathways of NAD+ biosynthesis in LS 174T goblet cells, revealing that NAD+ plays a novel role in the formation of an intact intestinal mucus layer by stimulating mucin production [20]
The results suggested that protein kinase C (PKC)-δ might contribute to MUC2 expression through phospholipase C (PLC) stimulation by exogenous NAD+

Summary

Introduction

The mucus layer in the intestine is mainly composed of mucin glycoproteins that are secreted from intestinal goblet cells. The mucus layer acts as an intestinal barrier and plays a critical role in preventing toxic molecules and pathogens from penetrating into the intestinal mucosae, preventing intestinal inflammation [1]. In addition to damage to the mucus layer, decreases in mucin secretion by intestinal goblet cells can contribute to chronic inflammation in the intestine [3]. Through RNA sequencing, we found that the expression of genes involved in arachidonic acid metabolism increased in NAD+-treated cells compared with the negative control cells. Extracellular signal-regulated kinase (ERK)1/2 and cyclic AMP (cAMP) response element-binding protein (CREB) transcript levels were higher in NAD+-treated cells than in the negative control cells, and the enhanced levels of phosphorylated CREB augmented MUC2 expression. Conclusions: Exogenous NAD+ increases MUC2 expression by stimulating the PLC-δ/PTGES/PKC-δ/ERK/CREB signaling pathway

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Conclusion