Digestive Diseases and Sciences

, Volume 58, Issue 1, pp 77–87

Zinc Supplementation Modifies Tight Junctions and Alters Barrier Function of CACO-2 Human Intestinal Epithelial Layers

  • Xuexuan Wang
  • Mary Carmen Valenzano
  • Joanna M. Mercado
  • E. Peter Zurbach
  • James M. Mullin
Original Article



Zinc deficiency is known to result in epithelial barrier leak in the GI tract. Precise effects of zinc on epithelial tight junctions (TJs) are only beginning to be described and understood. Along with nutritional regimens like methionine-restriction and compounds such as berberine, quercetin, indole, glutamine and rapamycin, zinc has the potential to function as a TJ modifier and selective enhancer of epithelial barrier function.


The purpose of this study was to determine the effects of zinc-supplementation on the TJs of a well-studied in vitro GI model, CACO-2 cells.


Barrier function was assessed electrophysiologically by measuring transepithelial electrical resistance (Rt), and radiochemically, by measuring transepithelial (paracellular) diffusion of 14C-D-mannitol and 14C-polyethyleneglycol. TJ composition was studied by Western immunoblot analyses of occludin, tricellulin and claudins-1 to -5 and -7.


Fifty- and 100-μM zinc concentrations (control medium is 2 μM) significantly increase Rt but simultaneously increase paracellular leak to D-mannitol. Claudins 2 and 7 are downregulated in total cell lysates, while occludin, tricellulin and claudins-1, -3, -4 and -5 are unchanged. Claudins-2 and -7 as well as tricellulin exhibit decreased cytosolic content as a result of zinc supplementation.


Zinc alters CACO-2 TJ composition and modifies TJ barrier function selectively. Zinc is one of a growing number of “nutraceutical” substances capable of enhancing epithelial barrier function, and may find use in countering TJ leakiness induced in various disease states.


Zinc CACO-2 Tight junction Claudins Paracellular Nutrition Claudin Differentiation Metallothionein 



Tight junction


Potential difference


Short circuit current


Transepithelial electrical resistance

MT 1/2

Metallothionein 1/2




Fetal bovine serum


Phosphate buffered saline


Recommended daily allowance


Standard error of the mean


Lactate dehydrogenase


Tetrazolium dye, sodium 2,3,-bis(2-methoxy-4-nitro-5-sulfophenyl-5-[(phenylamino)-carbonyl]-2H-tetrazolium)


Liquid scintillation counting




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Copyright information

© Springer Science+Business Media, LLC 2012

Authors and Affiliations

  • Xuexuan Wang
    • 1
  • Mary Carmen Valenzano
    • 1
  • Joanna M. Mercado
    • 1
  • E. Peter Zurbach
    • 2
  • James M. Mullin
    • 1
    • 3
  1. 1.Lankenau Institute for Medical ResearchWynnewoodUSA
  2. 2.Department of ChemistrySaint Joseph’s UniversityPhiladelphiaUSA
  3. 3.Division of GastroenterologyLankenau Medical CenterWynnewoodUSA

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