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Cadmium disorganises the scaffolding of gap and tight junction proteins in the hepatic cell line WIF B9
Author(s) -
Boucherie Sylviane,
Decaens Catherine,
Verbavatz JeanMarc,
Grosse Brigitte,
Erard Marie,
Merola Fabienne,
Cassio Doris,
Combettes Laurent
Publication year - 2013
Publication title -
biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 85
eISSN - 1768-322X
pISSN - 0248-4900
DOI - 10.1111/boc.201200092
Subject(s) - tight junction , claudin , occludin , gap junction , paracellular transport , biology , microbiology and biotechnology , cell junction , bone canaliculus , cadmium chloride , cell culture , cell signaling , cadmium , intracellular , biophysics , cell , signal transduction , materials science , biochemistry , permeability (electromagnetism) , anatomy , genetics , metallurgy , membrane
Background Information Hepatocytes, which perform the main functions of the liver, are particularly vulnerable to toxic agents such as cadmium, an environmental pollutant. To identify the molecular targets for cadmium in hepatocytes, we have studied the effects of CdCl 2 on the hybrid cell line WIF‐B9 that exhibits stable structural and functional hepatocytic polarity. Results We showed that the toxicity of CdCl 2 (1 µM, 24 h) resulted in a reduction in direct intercellular communication (via gap junctions) and in an increase in paracellular permeability (decrease in the sealing of tight junctions). These effects were not related to changes in the expression of the key proteins involved, Cx32 and claudin 2, the first being constitutive of gap junctions and the second of tight junctions in this cell line. Using immunofluorescence experiments, we observed a change in the location of Cx32 and claudin 2: these two proteins were less often found in the tight junction network that closes the bile canaliculi (BC). In control cells, ‘Proximity Ligation Assay’ (PLA Duolink®) has confirmed in situ that molecules of claudin 2 and Cx32 are very close to each other at the BC (probably less than 16 nm). This was no longer the case after treatment with CdCl 2 . Localisation of occludin and Cx32 relative to each other was not modified by CdCl 2 , but CdCl 2 increased the PLA signal between molecules of JAM‐A and Cx32. Finally, examination of freeze‐fracture replicas obtained from cultures treated with CdCl 2 showed the disruption of the network of tight junctions and the depletion or the disintegration of the junctional plaques associated with tight junctions. Conclusions This study demonstrates in situ the changes induced by cadmium on the organisation of cell–cell junctions and points out the importance of the association Cx32/claudin 2 for the maintenance of normal hepatocyte functions.