title: Involvement of CD45 in DNA fragmentation in apoptosis induced by mitochondrial perturbing agents.
abstract: CD45 is a type I transmembrane molecule with phosphatase activity which comprises up to 10% of the cell surface area in nucleated haematopoietic cells. We have previously demonstrated the absence of nuclear apoptosis in CD45-negative T cells after chemical-induced apoptosis. The aim of this study was to characterize the role of CD45 in nuclear apoptosis. In contrast to wild type CD45-positive T cells, the CD45-deficient T cell lines are resistant to the induction of DNA fragmentation and chromatin condensation following tributyltin (TBT) or H2O2 exposure, but not to cycloheximide-induced apoptosis. CD45 transfection in deficient cell lines led to the restoration of chromatin condensation and DNA fragmentation following TBT exposure. In both CD45-positive and negative T cell lines, TBT exposure mediates intracellular calcium mobilization, caspase-3 activation and DFF45 cleavage. Moreover, DNA fragmentation was also induced by TBT in cells deficient in expression of p56lck, ZAP-70 and SHP-1. Subcellular partitioning showed a decrease in nuclear localisation of caspase-3 and DFF40. Together, these results demonstrate for the first time, that CD45 expression plays a key role in internucleosomal DNA fragmentation and chromatin condensation processes during apoptosis. CD45 activity or its substrates' activity, appears to be located downstream of caspase-3 activation and plays a role in retention of DFF40 in the nucleus.
authors.affiliation: INRS-Institut Armand-Frappier, 531 boul. des Prairies, Laval, QC, Canada, H7V 1B7.
authors.forename: Philippe
authors.initials: P
authors.lastname: Desharnais
authors.forename: Geneviève
authors.initials: G
authors.lastname: Dupéré-Minier
authors.forename: Claudine
authors.initials: C
authors.lastname: Hamelin
authors.forename: Patrick
authors.initials: P
authors.lastname: Devine
authors.forename: Jacques
authors.initials: J
authors.lastname: Bernier
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism*; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D045304:Cytochromes c / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects*; D003851:Deoxyribonucleases / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D017493:Leukocyte Common Antigens / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D000075223:Poly-ADP-Ribose Binding Proteins; D013601:T-Lymphocytes / Q000201:enzymology / Q000378:metabolism; D014162:Transfection; D014220:Trialkyltin Compounds / Q000494:pharmacology*
chemical_list: D000075223:Poly-ADP-Ribose Binding Proteins; D014220:Trialkyltin Compounds; C011559:tributyltin; D045304:Cytochromes c; D006861:Hydrogen Peroxide; C113696:DFFB protein, human; D003851:Deoxyribonucleases; D017493:Leukocyte Common Antigens; D053148:Caspase 3; D002118:Calcium