Apoptosis of human erythroid colony-forming cells is decreased by stem cell factor and insulin-like growth factor I as well as erythropoietin.
To clarify the manner by which erythropoietin (EP), stem cell factor (SCF), or insulin-like growth factor I (IGF-I) regulate erythropoiesis, apoptosis of human erythroid progenitor cells was investigated. Human burst-forming units-erythroid (BFU-E) partially purified from peripheral blood were cultured for 6 days to generate erythroid colony-forming cells (ECFC), which consist mainly of colony-forming units-erythroid (CFU-E). The cells were labeled with [3H]thymidine, incubated in serum-free liquid media, at 37 degrees C, for 16 h, and the pattern of DNA breakdown was analyzed by agarose gel electrophoresis. When these cells were incubated without EP, 70% of the total cellular DNA was broken down into DNA fragments of less than 5 kilobases and nuclear condensation and fragmentation, characteristic of apoptosis, were evident. While EP greatly reduced the amount of DNA breakdown to 23%, SCF and IGF-I each reduced the amount of DNA breakdown to 38-46% and, when added together, to 24%. Dose-response experiments with SCF and IGF-I showed a dose-dependent reduction in DNA fragmentation at concentrations that stimulate colony formation in serum-free semisolid cultures. Finally, assays of ECFC performed by the plasma clot method, after serum-free liquid culture, at 37 degrees C, for 16 h, demonstrated marked protection of erythroid colony-forming capacity by SCF or IGF-I in the absence of EP, as well as by EP itself. These data indicate that human erythroid progenitor cells undergo apoptosis which is reduced by SCF and IGF-I as well as EP and suggest that the control of apoptosis by each of these factors has a prominent role in the regulation of erythropoiesis.
Muta
K
K
Department of Medicine, Nashville Department of Veterans Affairs Medical Center, Tennessee.
Krantz
S B
SB
D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002455:Cell Division; D002478:Cells, Cultured; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D015672:Erythroid Precursor Cells / Q000166:cytology* / Q000378:metabolism / Q000502:physiology; D004920:Erythropoiesis / Q000502:physiology; D004921:Erythropoietin / Q000494:pharmacology* / Q000502:physiology; D016298:Hematopoietic Cell Growth Factors / Q000494:pharmacology* / Q000502:physiology; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology* / Q000502:physiology; D019089:Stem Cell Factor; D013936:Thymidine / Q000378:metabolism; D014316:Tritium
D016895:Culture Media, Serum-Free; D016298:Hematopoietic Cell Growth Factors; D019089:Stem Cell Factor; D014316:Tritium; D004921:Erythropoietin; D007334:Insulin-Like Growth Factor I; D004247:DNA; D013936:Thymidine