β-Casein(94-123)-derived peptides differently modulate production of mucins in intestinal goblet cells

J Dairy Res. 2015 Feb;82(1):36-46. doi: 10.1017/S0022029914000533. Epub 2014 Oct 22.

Abstract

We recently reported the identification of a peptide from yoghurts with promising potential for intestinal health: the sequence (94-123) of bovine β-casein. This peptide, composed of 30 amino acid residues, maintains intestinal homoeostasis through production of the secreted mucin MUC2 and of the transmembrane-associated mucin MUC4. Our study aimed to search for the minimal sequence responsible for the biological activity of β-CN(94-123) by using several strategies based on (i) known bioactive peptides encrypted in β-CN(94-123), (ii) in silico prediction of peptides reactivity and (iii) digestion of β-CN(94-123) by enzymes of intestinal brush border membranes. The revealed sequences were tested in vitro on human intestinal mucus-producing HT29-MTX cells. We demonstrated that β-CN(108-113) (an ACE-inhibitory peptide) and β-CN(114-119) (an opioid peptide named neocasomorphin-6) up-regulated MUC4 expression whereas levels of the secreted mucins MUC2 and MUC5AC remained unchanged. The digestion of β-CN(94-123) by intestinal enzymes showed that the peptides β-CN(94-108) and β-CN(117-123) were present throughout 1·5 to 3 h of digestion, respectively. These two peptides raised MUC5AC expression while β-CN(117-123) also induced a decrease in the level of MUC2 mRNA and protein. In addition, this inhibitory effect was reproduced in airway epithelial cells. In conclusion, β-CN(94-123) is a multifunctional molecule but only the sequence of 30 amino acids has a stimulating effect on the production of MUC2, a crucial factor of intestinal protection.

Keywords: ACE Angiotensin-converting enzyme; BBMV brush border membrane vesicles; BSA bovine serum albumin; CT controls; DPP IV dipeptidyl peptidase IV; ELLA Enzyme-linked lectin assay; FBS foetal bovine serum; Milk bioactive peptides; TFA trifluoroacetic acid; intestinal barrier; intestinal protection; mucus; β-CN β-casein; β-casein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Caseins / chemistry
  • Caseins / pharmacology*
  • Cattle
  • Gene Expression / drug effects
  • Goblet Cells / drug effects
  • Goblet Cells / metabolism*
  • HT29 Cells
  • Humans
  • Intestines / cytology*
  • Microvilli / enzymology
  • Molecular Sequence Data
  • Mucin 5AC / genetics
  • Mucin-2 / biosynthesis
  • Mucin-2 / genetics
  • Mucin-4 / biosynthesis
  • Mucins / biosynthesis*
  • Mucins / drug effects*
  • Peptide Fragments / chemistry
  • Peptide Fragments / pharmacology*
  • Peptide Hydrolases / metabolism
  • RNA, Messenger / analysis
  • Swine
  • Yogurt / analysis

Substances

  • Caseins
  • MUC2 protein, human
  • MUC4 protein, human
  • MUC5AC protein, human
  • Mucin 5AC
  • Mucin-2
  • Mucin-4
  • Mucins
  • Peptide Fragments
  • RNA, Messenger
  • Peptide Hydrolases