Role of the cold shock domain protein A in the transcriptional regulation of HBG expression.
Impaired switching from fetal haemoglobin (HbF) to adult globin gene expression leads to hereditary persistence of fetal haemoglobin (HPFH) in adult life. This is of prime interest because elevated HbF levels ameliorate β-thalassaemia and sickle cell anaemia. Fetal haemoglobin levels are regulated by complex mechanisms involving factors linked or not to the β-globin gene (HBB) locus. To search for factors putatively involved in the expression of the γ-globin genes (HBG1, HBG2), we examined the reticulocyte transcriptome of three siblings who had different HbF levels and different degrees of β-thalassaemia severity although they had the same ΗBA- and ΗΒB cluster genotypes. By mRNA differential display we isolated the cDNA coding for the cold shock domain protein A (CSDA), also known as dbpA, previously reported to interact in vitro with the HBG2 promoter. Expression studies performed in K562 and in primary erythroid cells showed an inverse relationship between HBG and CSDA expression levels. Functional studies performed by Chromatin Immunoprecipitation and reporter gene assays in K562 cells demonstrated that CSDA is able to bind the HBG2 promoter and suppress its expression. Therefore, our study demonstrated that CSDA is a trans-acting repressor factor of HBG expression and modulates the HPFH phenotype.
Petruzzelli
Raffaella
R
Dipartimento di Biochimica e Biotecnologie Mediche, Università degli Studi di Napoli Federico II, Naples, Italy.
Gaudino
Sara
S
Amendola
Giovanni
G
Sessa
Raffaele
R
Puzone
Stella
S
Di Concilio
Rosanna
R
d'Urzo
Giovanna
G
Amendolara
Maria
M
Izzo
Paola
P
Grosso
Michela
M
D000328:Adult; D022762:CCAAT-Enhancer-Binding Proteins / Q000502:physiology*; D002352:Carrier Proteins / Q000235:genetics; D002478:Cells, Cultured; D005260:Female; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D006360:Heat-Shock Proteins / Q000502:physiology*; D006801:Humans; D020014:K562 Cells; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins / Q000235:genetics; D020626:Oncogene Proteins v-myb / Q000235:genetics; D010375:Pedigree; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic / Q000235:genetics; D034622:RNA Interference; D012097:Repressor Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D014158:Transcription, Genetic; D017086:beta-Thalassemia / Q000235:genetics* / Q000378:metabolism; D055545:gamma-Globins / Q000096:biosynthesis* / Q000235:genetics
C486563:BCL11A protein, human; D022762:CCAAT-Enhancer-Binding Proteins; D002352:Carrier Proteins; D006360:Heat-Shock Proteins; D009687:Nuclear Proteins; D020626:Oncogene Proteins v-myb; D012097:Repressor Proteins; C094867:YBX3 protein, human; D055545:gamma-Globins