title: Post-transcriptional effects of interleukin-3, interferon-gamma, erythropoietin and butyrate on in vitro hemoglobin chain synthesis in congenital hemolytic anemia.
abstract: OBJECTIVE
  Various agents modulate hemoglobin synthesis. In vitro modulation of translation in hemoglobin chain synthesis was analysed in patients with congenital hemolytic anemia (n=32) and healthy controls (n=17).
  
  
  METHODS
  Enriched reticulocytes were co-incubated with (3)H-leucine and cytokines or butyrate. Reversed-phase chromatography enabled separation of alpha-, beta- and gamma-globin chains. Globin chain synthesis was calculated from measured (3)H-leucine incorporation. Transferrin, erythropoietin, interleukin-3 and interferon-gamma receptors were detected by flow cytometry. Reverse-transcription polymerase chain reaction (RT PCR) was used to demonstrate changes of RNA stability.
  
  
  CONCLUSIONS
  Interleukin-3, interferon-gamma and butyrate caused a significant 2-fold increase (range 1.8-2.4; p<0.01) of the alpha- and beta-chain synthesis in congenital hemolytic anaemias. Analysis of gamma-globin chain synthesis revealed a lower, i.e. 1.4 fold increase (range 1.32 to 1.41; p<0.03). The absolute amount of globin synthesis was calculated to be 2.9 x 10(-12) g/reticulocyte/24h. After incubation with interleukin-3 the absolute additional synthesis of the alpha-globin chain reached 1.31 x 10(-12) g/reticulocyte/24h, of the beta-globin chain, 1.15 x 10(-12) g/reticulocyte/24h and of the gamma-globin chain, 0.26 x 10(-12) g/reticulocyte/24h. Butyrate and interferon-gamma had no or even an inhibiting effect on reticulocytes from normal controls, while interleukin-3 stimulated alpha- and gamma-chain synthesis (1.4 and 2.4 fold, respectively; p<0.03) suggesting an increase of fetal hemoglobin (HbF). Erythropoietin showed no stimulating influence. Membrane associated interleukin-3 receptors were detected in 0.78+/-0.14%, and interferon-gamma receptors in 0.1+/-0.015% of the red cells. Erythropoietin receptors were extremely rare (0.05+/-0.015%). The expression of transferrin receptors (CD71) correlated with the extent of globin chain stimulation. The alpha-, and beta-globin mRNA content of the reticulocytes after interleukin-3 incubation, as measured by RT-PCR, increased.
  
  
  CONCLUSIONS
  Hemoglobin chain synthesis could be modulated post-transcriptionally by interleukin-3, interferon-gamma and butyrate. Transferrin receptor and globin RNA stability might be involved in this phenomenon.
authors.affiliation: Children's Hospital University Goettingen, Germany. dreinh@uni-muenster.de
authors.forename: D
authors.initials: D
authors.lastname: Reinhardt
authors.forename: R
authors.initials: R
authors.lastname: Ridder
authors.forename: W
authors.initials: W
authors.lastname: Kugler
authors.forename: A
authors.initials: A
authors.lastname: Pekrun
mesh_terms: D000293:Adolescent; D000328:Adult; D000745:Anemia, Hemolytic, Congenital / Q000097:blood*; D002087:Butyrates / Q000494:pharmacology; D016022:Case-Control Studies; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D016207:Cytokines / Q000494:pharmacology*; D004921:Erythropoietin / Q000494:pharmacology; D005914:Globins / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics; D006454:Hemoglobins / Q000096:biosynthesis* / Q000187:drug effects; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D007377:Interleukin-3 / Q000494:pharmacology; D007930:Leucine / Q000493:pharmacokinetics; D008875:Middle Aged; D020871:RNA Stability; D012333:RNA, Messenger / Q000032:analysis; D012156:Reticulocytes / Q000187:drug effects / Q000378:metabolism; D014316:Tritium
chemical_list: D002087:Butyrates; D016207:Cytokines; D006454:Hemoglobins; D007377:Interleukin-3; D012333:RNA, Messenger; D014316:Tritium; D004921:Erythropoietin; D007371:Interferon-gamma; D005914:Globins; D007930:Leucine