title: Accelerated internalization of junctional membrane proteins (connexin 43, N-cadherin and ZO-1) within endocytic vacuoles: an early event of DDT carcinogenicity.
abstract: Stability of cell-to-cell interactions and integrity of junctional membrane proteins are essential for biological processes including cancer prevention. The present study shows that DDT, a non-genomic carcinogen used at a non-cytotoxic dose (1 microM), rapidly disrupted the cell-cell contacts and concomitantly induced the formation of cytoplasmic vacuoles close to the plasma membrane in the SerW3 Sertoli cell line. High-resolution deconvolution microscopy reveals that this vacuolization process was clathrin-dependent since a hyperosmotic media (0.2 M sucrose) blocked rhodamine-dextran endocytosis. In response to DDT, junctional proteins such as Cx43, N-Cadherin and ZO-1 were internalized and present in vacuoles. In Cx43-GFP transfected cells, time lapse videomicroscopy demonstrates that DDT rapidly enhanced fragmentation of the gap junction plaques and abolished the gap junction coupling without major modification of Cx43 phosphorylation status. Repeated exposure to DDT resulted in chronic gap junction coupling injury. The present results demonstrate that one of the early effect of DDT is to interfere with the plasma membrane and to perturb its function, specifically its ability to establish cell-cell junctions that are essential for tissue homeostasis and control of cell proliferation and differentiation. Such an alteration may play a specific role during carcinogenesis.
authors.affiliation: INSERM U 670, Faculté de Médecine, 28 Avenue de Valombrose, 06107 Nice cedex 02, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Fiorini
authors.forename: Jérome
authors.initials: J
authors.lastname: Gilleron
authors.forename: Diane
authors.initials: D
authors.lastname: Carette
authors.forename: Astrid
authors.initials: A
authors.lastname: Valette
authors.forename: Anne
authors.initials: A
authors.lastname: Tilloy
authors.forename: Stephan
authors.initials: S
authors.lastname: Chevalier
authors.forename: Dominique
authors.initials: D
authors.lastname: Segretain
authors.forename: Georges
authors.initials: G
authors.lastname: Pointis
mesh_terms: D000818:Animals; D015820:Cadherins / Q000378:metabolism; D002273:Carcinogens / Q000633:toxicity*; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D018031:Connexin 43 / Q000378:metabolism; D003634:DDT / Q000633:toxicity*; D004705:Endocytosis / Q000187:drug effects*; D017629:Gap Junctions / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D012708:Sertoli Cells / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D014617:Vacuoles / Q000187:drug effects* / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein
chemical_list: D015820:Cadherins; D002273:Carcinogens; D018031:Connexin 43; D008565:Membrane Proteins; D010750:Phosphoproteins; D062826:Zonula Occludens-1 Protein; D003634:DDT