Cell cycle-specific behavior of erythropoietin.
The murine erythropoietin-dependent erythroleukemia cell line, HCD-57, was employed to study the cell cycle-specific behavior of erythropoietin. Cell cycle duration for HCD-57 cells was approximately 12 hours and was uninfluenced by erythropoietin. Populations of HCD-57 cells synchronized in G1 by centrifugal elutriation were able to pass through one complete cell cycle in the absence of erythropoietin but, thereafter, arrested in G1 as identified by propidium iodide staining and flow cytometry. Analysis of cell cycle behavior using the metachromic dye acridine orange, however, revealed that HCD-57 cells pass through a G0 cell cycle phase and, like serum-deprived 3T3 cells, actually arrest in G0 when deprived of erythropoietin. Expression of the cell cycle regulatory protein p34cdc2 was invariant throughout the cell cycle in HCD-57 cells. p34cdc2 was constitutively phosphorylated in G0 cells, and this effect was not modified by erythropoietin. Erythropoietin receptor distribution was log normal in HCD-57 cells in each phase of the cell cycle. The affinity of these surface receptors for erythropoietin was essentially invariant throughout the cell cycle, but receptor expression was upregulated in G2M cells as compared with cells in G1 or S phase. Taken together, these data indicate that erythropoietin has an important role in the G0-G1 to S phase transition but, based on receptor expression, is involved in other phases of the cell cycle as well.
Spivak
J L
JL
Division of Hematology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Ferris
D K
DK
Fisher
J
J
Noga
S J
SJ
Isaacs
M
M
Connor
E
E
Hankins
W D
WD
D000818:Animals; D016203:CDC2 Protein Kinase / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects*; D004921:Erythropoietin / Q000494:pharmacology*; D005347:Fibroblasts / Q000187:drug effects; D005434:Flow Cytometry; D016193:G1 Phase / Q000187:drug effects; D004915:Leukemia, Erythroblastic, Acute / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D009363:Neoplasm Proteins / Q000378:metabolism; D017467:Receptors, Erythropoietin / Q000378:metabolism; D016192:Resting Phase, Cell Cycle / Q000187:drug effects; D016196:S Phase / Q000187:drug effects; D014407:Tumor Cells, Cultured / Q000187:drug effects
D009363:Neoplasm Proteins; D017467:Receptors, Erythropoietin; D004921:Erythropoietin; D016203:CDC2 Protein Kinase