Restriction of sulfur-containing amino acids alters claudin composition and improves tight junction barrier function

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2007-09, Vol.293 (3), p.R1046-R1055
• Main Authors: Skrovanek, S, Valenzano, M. C, Mullin, J. M
• Format: Article
• Language: English
• Subjects: Aging; Aging - physiology; Amino acids; Amino Acids - metabolism; Amino Acids, Sulfur - physiology; Animals; Blotting, Western; Cell growth; Culture Media; Diet; DNA - biosynthesis; Electrophysiology; Epithelial Cells - physiology; Epithelial Cells - ultrastructure; Fluorescent Antibody Technique; Kidney Tubules, Proximal - cytology; Kidney Tubules, Proximal - metabolism; LLC-PK1 Cells; Membrane Proteins - biosynthesis; Membrane Proteins - chemistry; Membrane Proteins - metabolism; Occludin; Proteins; RNA - biosynthesis; Swine; Tight Junctions - drug effects; Tight Junctions - metabolism
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.00072.2007

1 Department of Biology, Saint Joseph's University, Philadelphia, Pennsylvania; 2 The Lankenau Institute for Medical Research, Wynnewood, Pennsylvania; and 3 Division of Gastroenterology, Lankenau Hospital, Wynnewood, Pennsylvania Submitted 31 January 2007 ; accepted in final form 11 June 2007 Restriction of sulfur-containing amino acids (SCAA) has been shown to elicit a similar increase in life span and decrease in age-related morbidity as caloric restriction. The singular importance of epithelial barrier function in both physiological homeostasis and prevention of inflammation raised the issue of examining the effect of SCAA restriction on epithelial tight junction structure and permeability. Using a well-described in vitro, epithelial model, the LLC-PK 1 renal epithelial cell line, we studied the effects of SCAA restriction in culture medium. Reduction of methionine by 90%, cysteine by 50%, and total elimination of cystine resulted in dramatically lower intracellular pools of these amino acids and their metabolite, taurine, but the intracellular pools of the non-SCAA were all elevated. Cell growth and differentiation were maintained, and both confluent cell density and transepithelial short circuit current were unaffected. Certain tight junctional proteins, such as occludin and claudins-1 and -2 were not altered. However, claudins-3 and -7 were significantly decreased in abundance, whereas claudins-4 and -5 were markedly increased in abundance. The functional result of these structural changes was improved barrier function, as evidenced by increased transepithelial electrical resistance and decreased transepithelial (paracellular) diffusion of D -mannitol. caloric restriction; diet; aging; permeability; methionine Address for reprint requests and other correspondence: J. M. Mullin, The Lankenau Institute for Medical Research, 100 Lancaster Ave., Wynnewood, PA 19096 (e-mail: mullinj{at}mlhs.org )