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Exogenous NAD+ induces mucin secretion in LS 174T goblet cells via the PLC-delta/PTGES/PKC-delta/ERK1/2/CREB signalling pathway

ABSTRACT: Mucin, one of family of glycoprotein that is 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 defence against toxic molecules and pathogens. In this study, we investigated the stimulatory effects of exogenous nicotinamide adenine dinucleotide (NAD+) on the expression of MUC2, the main mucin subtype in the intestine, in LS 174T goblet cells. NAD+ significantly stimulated MUC2 expression at the transcriptional and translational levels. Through RNA sequencing, we found that the expression of genes involved in arachidonic acid metabolism was increased in NAD+-treated cells compared with the negative control cells. For example, 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. In conclusion, exogenous NAD+ increases MUC2 expression by stimulating the PLC-δ/PTGES/PKC-δ/ERK1/2/CREB signalling pathway.

ORGANISM(S): Homo sapiens

PROVIDER: GSE140116 | GEO | 2020/05/21

REPOSITORIES: GEO

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Project description:Background; MUC2 mucin produced by intestinal goblet cells is the major component of the intestinal mucus barrier. MUC2 homo-oligomerizes intracellularly into large secreted polymers which give mucus its viscous properties. The inflammatory bowel disease (IBD) ulcerative colitis is characterized by depleted goblet cells and a reduced mucus layer, whereas goblet cells and the mucus layer are increased in the other major inflammatory bowel disease, Crohnâs disease. Methods and Findings; By murine N-ethyl-N-nitrosourea-mutagenesis we identified two distinct non-complementing missense mutations in Muc2 exons encoding N- and C-terminal homo-oligomerization domains causing an ulcerative colitis-like phenotype. Both strains developed mild spontaneous distal intestinal inflammation, chronic diarrhea, rectal bleeding and prolapse, increased susceptibility to acute and chronic colitis induced by a luminal toxin, aberrant Muc2 biosynthesis, smaller goblet cell thecae (less stored mucin) and a diminished mucus barrier. Enhanced local production of IL-1beta, TNF-alpha and IFN-gamma was seen in the distal colon. The number of leukocytes within mesenteric lymph nodes was increased five-fold and leukocytes cultured in vitro produced both Th1 and Th2 cytokines (IFN-gamma, TNF-alpha and IL-13). Intestinal permeability was increased and the luminal bacterial flora were more heavily coated with immunoglobulin as occurs in IBD. This pathology was accompanied by accumulation of the Muc2 precursor and ultrastructural and biochemical evidence of endoplasmic reticulum (ER) stress in goblet cells, activation of the unfolded protein response, and altered intestinal expression of genes involved in ER stress, inflammation, apoptosis and wound repair. Expression of mutated Muc2 oligomerization domains in vitro demonstrated that aberrant Muc2 oligomerization underlies the ER stress. These models show that mutations in Muc2 oligomerization domains can lead to aberrant assembly of the Muc2 complex leading to ER stress, a depleted mucus barrier and intestinal inflammation. In ulcerative colitis we demonstrate similar accumulation of non-glycosylated MUC2 precursor in goblet cells together with ultrastructural and biochemical evidence of ER stress even in non-inflamed intestinal tissue. Conclusions; The observations that mucin misfolding and ER stress lead directly to intestinal inflammation and that ER stress and goblet cell pathology occur in ulcerative colitis suggest that ER stress-related mucin depletion could be a fundamental component of the pathogenesis of colitis. Experiment Overall Design: 3 individual mice from the Eeyore, Winnie or Wild-type strains were compared as groups. An Affymetrix ID was compared between groups if the ID was Present within two of the three mice within each grouping. IDs were compared by calculating the log2 of Group One average signal divided by Group 2 average signal.

Project description:The proteolytic activation of protein kinase C delta generates a catalytic fragment called PKC delta-CF, which induces cell death. However, the mechanisms underlying PKC delta-CF-mediated cell death are largely unknown. On the basis of an engineering leukemic cell line with inducible expression of PKC delta-CF, here we employ SILAC-based quantitative phosphoproteomics to systematically and dynamically investigate the overall phosphorylation events during cell death triggered by PKC delta-CF expression. Totally, 3000 phosphorylation sites were analyzed. We combined SILAC for quantitation, strong-cation exchange chromatography and titanium dioxide chromatography for phosphopeptide enrichment, and high-accuracy mulistage MS. All MS/MS ion spectra were analyzed using Sequest version v.27, rev. 1146 (Thermo Fisher Scientific, San Jose, CA) which were incorporated into the Sorcerer engine version 4.0.4 build (Sage-N Research). Sequest were set up to search the ipi.HUMAN.v3.65 database (86379 entries) (ftp.ebi.ac.uk/pub/data bases/IPI/current) with its target-decoy database as a reversed complement assuming the semi-enzyme tryptic digestion allowed for three missed tryptic cleavages with full mass from 600 to 4600. The precursor ion tolerance was set to ±10 p.p.m and MS2 ions tolerance was set to 1 Da. Searches parameters for non-phosphopeptides were allowed for a static modification of Carbamidomethyl cysteine (C, +57.021465) and dynamic modifications of oxidized methionine (M, +15.99492) on, SILAC-labeled lysine (K, 6C2N, +8.014199) on and SILAC-labeled arginine (R, 6C4N, +10.008269) with up to 4 total dynamic modifications and up to 3 of any particular dynamic modification. In addition, searches for phosphopeptides were allowed for dynamic modifications of phosphorylation serine (S), threonine (T), and tyrosine (Y) (+79.966331) with up to 6 total dynamic modifications and up to 4 of any particular dynamic modification. The ASCORE algorithm was selected to assess the possibility of phosphorylation sites. DATSelect 2.0.39 was used to filter and group the data files derived from SORCERER-SEQUEST. The filter thresholds were set to XCorr 2+, 3+, 4+: > 2.5, > 3.0, > 3.5 and DeltaCN > 0.08. For protein identification, two peptides were required with estimated false-discovery rates (FDR) < 1%. For phosphopeptide identification, only unique peptide was required with FDR <2%, whereas DeltaCN should be adjusted to >0.125 if the FDR for phosphopeptide assignments was >2%. Furthermore, additional filtering was used to remove those indubitably false phosphopeptides, including sequences that contained both heavy and light isotopic variants of arginine and lysine. Finally, the FDR fall within 1%.

Project description:Background MUC2 mucin produced by intestinal goblet cells is the major component of the intestinal mucus barrier. MUC2 homo-oligomerizes intracellularly into large secreted polymers which give mucus its viscous properties. The inflammatory bowel disease (IBD) ulcerative colitis is characterized by depleted goblet cells and a reduced mucus layer, whereas goblet cells and the mucus layer are increased in the other major inflammatory bowel disease, Crohn’s disease. Methods and Findings By murine N-ethyl-N-nitrosourea-mutagenesis we identified two distinct non-complementing missense mutations in Muc2 exons encoding N- and C-terminal homo-oligomerization domains causing an ulcerative colitis-like phenotype. Both strains developed mild spontaneous distal intestinal inflammation, chronic diarrhea, rectal bleeding and prolapse, increased susceptibility to acute and chronic colitis induced by a luminal toxin, aberrant Muc2 biosynthesis, smaller goblet cell thecae (less stored mucin) and a diminished mucus barrier. Enhanced local production of IL-1beta, TNF-alpha and IFN-gamma was seen in the distal colon. The number of leukocytes within mesenteric lymph nodes was increased five-fold and leukocytes cultured in vitro produced both Th1 and Th2 cytokines (IFN-gamma, TNF-alpha and IL-13). Intestinal permeability was increased and the luminal bacterial flora were more heavily coated with immunoglobulin as occurs in IBD. This pathology was accompanied by accumulation of the Muc2 precursor and ultrastructural and biochemical evidence of endoplasmic reticulum (ER) stress in goblet cells, activation of the unfolded protein response, and altered intestinal expression of genes involved in ER stress, inflammation, apoptosis and wound repair. Expression of mutated Muc2 oligomerization domains in vitro demonstrated that aberrant Muc2 oligomerization underlies the ER stress. These models show that mutations in Muc2 oligomerization domains can lead to aberrant assembly of the Muc2 complex leading to ER stress, a depleted mucus barrier and intestinal inflammation. In ulcerative colitis we demonstrate similar accumulation of non-glycosylated MUC2 precursor in goblet cells together with ultrastructural and biochemical evidence of ER stress even in non-inflamed intestinal tissue. Conclusions The observations that mucin misfolding and ER stress lead directly to intestinal inflammation and that ER stress and goblet cell pathology occur in ulcerative colitis suggest that ER stress-related mucin depletion could be a fundamental component of the pathogenesis of colitis. Keywords: Single gene, multiple mutant comparison

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Exogenous NAD+ induces mucin secretion in LS 174T goblet cells via the PLC-delta/PTGES/PKC-delta/ERK1/2/CREB signalling pathway

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