Haemoglobin switching in human embryos: asynchrony of ζ → α and ε → γ-globin switches in primitive and definitive erythropoietic lineage

摘要: Haemoglobin switching in humans provides a unique model for investigating the mechanisms underlying expression of developmentally regulated gene family. Numerous studies have focused on switch from fetal to adult (that is, gamma----beta) globin, but little is known about embryonic----fetal zeta----alpha and epsilon----gamma) switches, as well transition 'primitive' yolk sac 'definitive' liver erythropoiesis. Here we studied haemoglobin switches sac, circulating blood erythroblasts 25 embryos 6 fetuses. Globin synthesis was also evaluated purified erythroblasts. Primitive synthesize essentially zeta epsilon chains at 5 weeks alpha- epsilon-globin with minor aliquot gamma 6-7 weeks, whereas definitive produce alpha + beta-globin only beta 8 onward. In both lineages epsilon----gamma are asynchronous, former preceding latter. Furthermore, zeta- restricted primitive respectively. These findings discussed terms monoclonal early human ontogeny.