title: Superoxide dismutase halts cycling of murine erythroid progenitor cells prior to S phase in vitro and possibly in vivo.
abstract: Mice of the C57BL/6 (B6) strain show a much lower proportion of marrow erythroid progenitor cells (BFU-E) in DNA synthesis in vivo than mice of the congeneic B6S strain. However, when assayed in vitro marrow cells from both strains show high proportions of BFU-E in S-phase. BFU-E from normal B6 mice have been previously shown to be specifically inhibited from entering S-phase in vitro by the antioxidant enzyme superoxide dismutase (SOD), however, in this study we have found that BFU-E taken from the marrow of B6S mice or B6 mice which have been subjected to bleeding are insensitive to SOD inhibition in vitro. Comparisons of results from in vivo and in vitro cycling assays done with cells from both strains indicate that a large proportion of marrow BFU-E in normal B6 mice are halted in the pre-S portion of the cell cycle in vivo, and these halted cells are prevented from going into S-phase in vitro by SOD. The insensitivity to SOD inhibition shown by BFU-E from B6S and bled B6 mice can be attributed to the absence of accumulation of SOD-susceptible cells in pre-S phase in these mice in vivo, and there is evidence to suggest that the difference in BFU-E cycling seen in vivo may be due to interactions between SOD and factors which stimulate cycling of BFU-E.
authors.affiliation: Department of Anatomy, University of Toronto, Canada.
authors.forename: F G
authors.initials: FG
authors.lastname: Pluthero
authors.forename: H
authors.initials: H
authors.lastname: van der Gaag
authors.forename: D
authors.initials: D
authors.lastname: Eskinazi
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000187:drug effects; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D003864:Depression, Chemical; D004285:Dogs; D015672:Erythroid Precursor Cells / Q000166:cytology / Q000187:drug effects*; D004920:Erythropoiesis / Q000187:drug effects; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D016196:S Phase / Q000187:drug effects; D013482:Superoxide Dismutase / Q000494:pharmacology*
chemical_list: D004247:DNA; D013482:Superoxide Dismutase