title: Chloramphenicol-induced mitochondrial dysfunction is associated with decreased transferrin receptor expression and ferritin synthesis in K562 cells and is unrelated to IRE-IRP interactions.
abstract: Chloramphenicol is an antibiotic that consistently suppresses the bone marrow and induces sideroblastic anemia. It is also a rare cause of aplastic anemia. These toxicities are thought to be related to mitochondrial dysfunction, since chloramphenicol inhibits mitochondrial protein synthesis. We hypothesized that chloramphenicol-induced mitochondrial impairment alters the synthesis of ferritin and the transferrin receptor. After treating K562 erythroleukemia cells with a therapeutic dose of chloramphenicol (10 microg/ml) for 4 days, there was a marked decrease in cell surface transferrin receptor expression and de novo ferritin synthesis associated with significant decreases in cytochrome c oxidase activity, ATP levels, respiratory activity, and cell growth. Decreases in the transferrin receptor and ferritin were associated with reduced and unchanged message levels, respectively. The mechanism by which mitochondrial dysfunction alters these important proteins in iron homeostasis is not clear. A global decrease in synthetic processes seems unlikely, since the expression of the cellular adhesion proteins VLA4 and CD58 was not significantly decreased by chloramphenicol, nor were the message levels of beta-actin or ferritin. The alterations were not accompanied by changes in binding of the iron response protein (IRP) to the iron-responsive element (IRE), although cytosolic aconitase activity was reduced by 27% in chloramphenicol-treated cells. A disturbance in iron homeostasis due to alterations in the transferrin receptor and ferritin may explain the hypochromic-microcytic anemia and the accumulation of nonferritin iron in the mitochondria in some individuals after chloramphenicol therapy. Also, these studies provide evidence of a link between mitochondrial impairment and iron metabolism in K562 cells.
authors.affiliation: Department of Medicine, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
authors.forename: L M
authors.initials: LM
authors.lastname: Leiter
authors.forename: H S
authors.initials: HS
authors.lastname: Thatte
authors.forename: C
authors.initials: C
authors.lastname: Okafor
authors.forename: P W
authors.initials: PW
authors.lastname: Marks
authors.forename: D E
authors.initials: DE
authors.lastname: Golan
authors.forename: K R
authors.initials: KR
authors.lastname: Bridges
mesh_terms: D000154:Aconitate Hydratase / Q000037:antagonists & inhibitors; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001052:Apoferritins; D018968:CD58 Antigens / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism; D002701:Chloramphenicol / Q000494:pharmacology*; D005293:Ferritins / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D039001:Integrin alpha Chains; D035925:Iron-Regulatory Proteins; D007506:Iron-Sulfur Proteins / Q000502:physiology; D020014:K562 Cells; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D012333:RNA, Messenger / Q000037:antagonists & inhibitors; D016601:RNA-Binding Proteins / Q000502:physiology; D011990:Receptors, Transferrin / Q000235:genetics / Q000378:metabolism*; D016029:Receptors, Very Late Antigen / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D018968:CD58 Antigens; C063493:CDw49d; D039001:Integrin alpha Chains; D035925:Iron-Regulatory Proteins; D007506:Iron-Sulfur Proteins; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011990:Receptors, Transferrin; D016029:Receptors, Very Late Antigen; D002701:Chloramphenicol; D005293:Ferritins; D001052:Apoferritins; D000154:Aconitate Hydratase