title: Mycophenolic acid mediated disruption of the intestinal epithelial tight junctions.
abstract: Gastrointestinal toxicity is a common adverse effect of mycophenolic acid (MPA) treatment in organ transplant patients, through poorly understood mechanisms. Phosphorylation of myosin light chain 2 (MLC2) is associated with epithelial tight junction (TJ) modulation which leads to defective epithelial barrier function, and has been implicated in GI diseases. The aim of this study was to investigate whether MPA could induce epithelial barrier permeability via MLC2 regulation. Caco-2 monolayers were exposed to therapeutic concentrations of MPA, and MLC2 and myosin light chain kinase (MLCK) expression were analyzed using PCR and immunoblotting. Epithelial cell permeability was assessed by measuring transepithelial resistance (TER) and the flux of paracellular permeability marker FITC-dextran across the epithelial monolayers. MPA increased the expression of MLC2 and MLCK at both the transcriptional and translational levels. In addition, the amount of phosphorylated MLC2 was increased after MPA treatment. Confocal immunofluorescence analysis showed redistribution of TJ proteins (ZO-1 and occludin) after MPA treatment. This MPA mediated TJ disruption was not due to apoptosis or cell death. Additionally ML-7, a specific inhibitor of MLCK was able to reverse both the MPA mediated decrease in TER and the increase in FITC-dextran influx, suggesting a modulating role of MPA on epithelial barrier permeability via MLCK activity. These results suggest that MPA induced alterations in MLC2 phosphorylation and may have a role in the patho-physiology of intestinal epithelial barrier disruption and may be responsible for the adverse effects (GI toxicity) of MPA on the intestine.
authors: Institute of Clinical Chemistry/UMG-Laboratories, University Medical Centre, Robert Koch Strasse 40, 37075 Goettingen, Germany; Department of Microbiology, Kohat University of Science and Technology, 26000 Kohat, Pakistan.
authors: Muhammad
authors: M
authors: Qasim
authors: Institute of Clinical Chemistry/UMG-Laboratories, University Medical Centre, Robert Koch Strasse 40, 37075 Goettingen, Germany; Department of Microbiology, Kohat University of Science and Technology, 26000 Kohat, Pakistan.
authors: Hazir
authors: H
authors: Rahman
authors: Institute for Applied Science and Clinical Trials GmbH - IFS, Georg-August University, 37075 Goettingen, Germany.
authors: Raees
authors: R
authors: Ahmed
authors: Institute of Clinical Chemistry/UMG-Laboratories, University Medical Centre, Robert Koch Strasse 40, 37075 Goettingen, Germany.
authors: Michael
authors: M
authors: Oellerich
authors: Institute of Clinical Chemistry/UMG-Laboratories, University Medical Centre, Robert Koch Strasse 40, 37075 Goettingen, Germany. Electronic address: asif@med.uni-goettingen.de.
authors: Abdul R
authors: AR
authors: Asif
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis; D015153:Blotting, Western; D018938:Caco-2 Cells; D024722:Cardiac Myosins / Q000235:genetics / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects*; D049109:Cell Proliferation; D003911:Dextrans / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects / Q000473:pathology*; D008856:Microscopy, Fluorescence; D009173:Mycophenolic Acid / Q000494:pharmacology*; D018994:Myosin Light Chains / Q000235:genetics / Q000378:metabolism; D009219:Myosin-Light-Chain Kinase / Q000235:genetics / Q000378:metabolism; D062793:Occludin / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D062826:Zonula Occludens-1 Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D000903:Antibiotics, Antineoplastic; D003911:Dextrans; D018994:Myosin Light Chains; D062793:Occludin; D012333:RNA, Messenger; D062826:Zonula Occludens-1 Protein; C015219:fluorescein isothiocyanate dextran; C107184:myosin light chain 2; D009219:Myosin-Light-Chain Kinase; D053148:Caspase 3; D024722:Cardiac Myosins; D009173:Mycophenolic Acid; D016650:Fluorescein-5-isothiocyanate
keywords: Mycophenolic acid; Myosin light chain 2; Permeability; Tight junctions