Protein synthesis in mucin-producing tissues is conserved when dietary threonine is limiting

Abstract

Mucins in mucus are particularly rich in an indispensable amino acid, threonine, and their continuous synthesis and secretion represent a major use of dietary threonine. In piglets, the small intestine is particularly sensitive to a low threonine intake resulting in compromised mucin production. Other epithelial tissues also synthesize large amounts of mucin but their impact on threonine requirement is not as well known. Yucatan mini-piglets were fed test diets with different threonine intakes and various tissues were analyzed for protein synthesis. The threonine intake at which maximal protein synthesis was reached was lower for mucin-producing tissues, suggesting mucin-producing tissues are conserved when dietary threonine is limiting, compared to muscle, liver and kidney. So if neonates are on a marginal threonine intake, then growth and the functions of other vital tissues are likely compromised at the expense of maintenance of the mucus layer.