{"title":"Erythropoiesis","authors":"V. Sankaran","doi":"10.1093/med/9780198746690.003.0531","DOIUrl":null,"url":null,"abstract":"Erythropoiesis is a highly regulated, multistep process in which stem cells, after a series of amplification divisions, generate multipotential progenitor cells, then oligo- and finally unilineage erythroid progenitors, and then morphologically recognizable erythroid precursors and mature red cells. The ontogeny of erythropoiesis involves a series of well-coordinated events during embryonic and early fetal life. In the fetus, the main site of erythropoiesis is the liver, which initially produces mainly fetal haemoglobin (HbF, α2γ2) and a small component (10–15%) of adult haemoglobin (HbA, α2β2), with the fraction of HbA rising to about 50% at birth. After birth, the site of erythroid cell production maintained throughout life is the bone marrow, with the final adult erythroid pattern (adult Hb with <1% fetal Hb) being reached a few months after birth. Regulation of erythropoiesis—the main regulator is erythropoietin, a sialoglycoprotein that is produced by interstitial cells in the kidney in response to tissue hypoxia and exerts its effect by binding to a specific receptor on erythroid burst-forming units, erythroid colony-forming units, and proerythroblasts. Abnormal erythropoietin production—anaemia can be caused by acquired or congenital deficiency in erythropoietin production, most commonly in chronic kidney disease. Impaired tissue oxygen delivery is a common cause of erythropoietin-driven secondary erythrocytosis. Some kidney cancers increase erythropoietin production and hence cause secondary erythrocytosis. Other causes of abnormal erythroid production include (1) acquired and congenital defects in erythropoietin signalling; (2) acquired and congenital defects in the transcription factors GATA1 or EKLF; (3) acquired or congenital abnormalities in ribosome synthesis or splicing factors; and (4) factors that lead to premature red cell destruction.","PeriodicalId":347739,"journal":{"name":"Oxford Textbook of Medicine","volume":"1 1","pages":"0"},"PeriodicalIF":0.0000,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Oxford Textbook of Medicine","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1093/med/9780198746690.003.0531","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Erythropoiesis is a highly regulated, multistep process in which stem cells, after a series of amplification divisions, generate multipotential progenitor cells, then oligo- and finally unilineage erythroid progenitors, and then morphologically recognizable erythroid precursors and mature red cells. The ontogeny of erythropoiesis involves a series of well-coordinated events during embryonic and early fetal life. In the fetus, the main site of erythropoiesis is the liver, which initially produces mainly fetal haemoglobin (HbF, α2γ2) and a small component (10–15%) of adult haemoglobin (HbA, α2β2), with the fraction of HbA rising to about 50% at birth. After birth, the site of erythroid cell production maintained throughout life is the bone marrow, with the final adult erythroid pattern (adult Hb with <1% fetal Hb) being reached a few months after birth. Regulation of erythropoiesis—the main regulator is erythropoietin, a sialoglycoprotein that is produced by interstitial cells in the kidney in response to tissue hypoxia and exerts its effect by binding to a specific receptor on erythroid burst-forming units, erythroid colony-forming units, and proerythroblasts. Abnormal erythropoietin production—anaemia can be caused by acquired or congenital deficiency in erythropoietin production, most commonly in chronic kidney disease. Impaired tissue oxygen delivery is a common cause of erythropoietin-driven secondary erythrocytosis. Some kidney cancers increase erythropoietin production and hence cause secondary erythrocytosis. Other causes of abnormal erythroid production include (1) acquired and congenital defects in erythropoietin signalling; (2) acquired and congenital defects in the transcription factors GATA1 or EKLF; (3) acquired or congenital abnormalities in ribosome synthesis or splicing factors; and (4) factors that lead to premature red cell destruction.