title: Effect of cobalt and chromium ions on bcl-2, bax, caspase-3, and caspase-8 expression in human U937 macrophages.
abstract: The bcl-2 and caspase families of proteins play a central role in the modulation of apoptosis. The purpose of this study was to analyze the effect of Co(2+) and Cr(3+) ions on the expression of bcl-2, bax, caspase-3 and caspase-8 to better understand the mechanisms leading to ion-induced apoptosis in macrophages. U937 human macrophages were exposed to Co(2+) and Cr(3+) ions. The expression of proteins was measured by Western blot while caspase activities were measured by colorimetric assay. Results show that Co(2+) ions inhibited bcl-2 expression with significant effect (p<0.05) after 16 h and a maximal 52% inhibitory effect after 24 h. Co(2+) stimulated bax expression with a significant stimulation (p<0.05) after 8 h and a maximal 1.75-fold increase after 16 h. Co(2+) also stimulated the expression of the active fragment of caspase-3 as well as caspase-3 activity maximal increase after 24 h. Co(2+) ions had no effect on caspase-8 expression or activity.Cr(3+) ions inhibited bcl-2 expression with significant effect (p<0.05) after 16 h and a maximal 43% inhibitory effect after 24 h. Cr(3+) stimulated bax expression with significant stimulation (p<0.01) after 8h and a maximal 2.25-fold increase after 24 h. Cr(3+) ions also stimulated the expression of the active fragments of caspase-3 and -8, as well as the activities of both proteases. The effect of Cr(3+) ions on the expression of both caspase active fragments was maximal after 16 h incubation. In conclusion, our results suggest that the modulation of the expression of proteins from the bcl-2 and the caspase families of proteins are implicated in the induction of macrophage apoptosis by Co(2+) and Cr(3+) ions.
authors.affiliation: Division of Orthopaedic Surgery, Lady Davis Institute for Medical Research, McGill University, The SMBD-Jewish General Hospital, 3755 Ch Cote Ste-Catherine, Que, Montreal, Canada H3T 1E2.
authors.forename: Alain
authors.initials: A
authors.lastname: Petit
authors.forename: Fackson
authors.initials: F
authors.lastname: Mwale
authors.forename: David J
authors.initials: DJ
authors.lastname: Zukor
authors.forename: Isabelle
authors.initials: I
authors.lastname: Catelas
authors.forename: John
authors.initials: J
authors.lastname: Antoniou
authors.forename: Olga L
authors.initials: OL
authors.lastname: Huk
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D002857:Chromium / Q000633:toxicity*; D003035:Cobalt / Q000633:toxicity*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D020298:U937 Cells; D051028:bcl-2-Associated X Protein
chemical_list: C494826:BAX protein, human; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D002857:Chromium; D003035:Cobalt; C505407:CASP3 protein, human; C505530:CASP8 protein, human; D053148:Caspase 3; D053181:Caspase 8; D020169:Caspases