Hemoglobin switching in culture: evidence for a humoral factor that induces switching in adult and neonatal but not fetal erythroid cells.
AUTOR(ES)
Papayannopoulou, T
RESUMO
An erythropoietic activity that exerts a profound effect on fetal Hb synthesis is present in fetal sheep sera and it attains a peak concentration at the end of the second to the middle of the third trimester of fetal life. The activity consistently inhibits the increased synthesis of fetal Hb in cultures of burst-forming units (BFUes) from normal adults. In cultures of BFUes from homozygous beta+-thalassemias the activity produces a striking decline in gamma chain synthesis, a decline in G gamma/A gamma chain synthesis ratio, and an increase in delta/gamma and alpha/non-alpha ratios--i.e., findings suggesting a genuine gamma-to-beta switch. The activity accelerates Hb F-to-Hb A switching in neonatal BFUe cultures but it has no effect on fetal Hb synthesis in cultures of BFUe obtained from human fetuses. These findings provide direct evidence that (a) humoral factors play a role in the regulation of the switch from fetal to adult Hb formation, and (b) progenitor cells from various stages of ontogeny respond differently to these factors. The results are compatible with the hypothesis that Hb switching during development is mediated through a change in a developmental program which controls the responsiveness of progenitor cells to "switching" activities in their environment.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=347171Documentos Relacionados
- Stochastic expression of fetal hemoglobin in adult erythroid cells.
- Cellular regulation of hemoglobin switching: evidence for inverse relationship between fetal hemoglobin synthesis and degree of maturity of human erythroid cells.
- Hemoglobin switching in sheep and goats: induction of hemoglobin C synthesis in cultures of sheep fetal erythroid cells.
- Direct evidence for interaction between human erythroid progenitor cells and a hemoglobin switching activity present in fetal sheep serum.
- Cellular Mechanisms for Increased Fetal Hemoglobin Production in Culture: EVIDENCE FOR CONTINUOUS COMMITMENT TO FETAL HEMOGLOBIN PRODUCTION DURING BURST FORMATION