Deoxynivalenol affects in vitro intestinal epithelial cell barrier integrity through inhibition of protein synthesis.
Deoxynivalenol (DON), one of the most common mycotoxin contaminants of raw and processed cereal food, adversely affects the gastrointestinal tract. Since DON acts as a protein synthesis inhibitor, the constantly renewing intestinal epithelium could be particularly sensitive to DON. We analyzed the toxicological effects of DON on intestinal epithelial protein synthesis and barrier integrity. Differentiated Caco-2 cells, as a widely used model of the human intestinal barrier, were exposed to realistic intestinal concentrations of DON (50, 500 and 5000 ng/ml) during 24h. DON caused a concentration-dependent decrease in total protein content associated with a reduction in the incorporation of [(3)H]-leucine, demonstrating its inhibitory effect on protein synthesis. DON simultaneously increased the paracellular permeability of the monolayer as reflected through a decreased transepithelial electrical resistance associated with an increased paracellular flux of the tracer [(3)H]-mannitol. A concentration-dependent reduction in the expression level of the tight junction constituent claudin-4 was demonstrated by Western blot, which was not due to diminished transcription, increased degradation, or NF-kappaB, ERK or JNK activation, and was also observed for a tight junction independent protein, i.e. intestinal alkaline phosphatase. These results demonstrate a dual toxicological effect of DON on differentiated Caco-2 cells consisting in an inhibition of protein synthesis as well as an increase in monolayer permeability, and moreover suggest a possible link between them through diminished synthesis of the tight junction constituent claudin-4.
De Walle
Jacqueline Van
JV
Institut des Sciences de la Vie & UCLouvain, B 1348 Louvain-la-Neuve, Belgium.
Sergent
Thérèse
T
Piront
Neil
N
Toussaint
Olivier
O
Schneider
Yves-Jacques
YJ
Larondelle
Yvan
Y
D000469:Alkaline Phosphatase / Q000096:biosynthesis; D018938:Caco-2 Cells; D062506:Claudin-4; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D017097:Electric Impedance; D005506:Food Contamination; D058851:GPI-Linked Proteins; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects*; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000378:metabolism; D008353:Mannitol / Q000378:metabolism; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D062793:Occludin; D010539:Permeability; D014176:Protein Biosynthesis / Q000187:drug effects*; D011500:Protein Synthesis Inhibitors / Q000633:toxicity*; D012333:RNA, Messenger / Q000096:biosynthesis; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors; D014255:Trichothecenes / Q000633:toxicity*
C568157:CLDN4 protein, human; D062506:Claudin-4; D058851:GPI-Linked Proteins; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D014255:Trichothecenes; D008353:Mannitol; C063088:ALPI protein, human; D000469:Alkaline Phosphatase; C007262:deoxynivalenol