Association studies identified BCL11A transcription factor as the master regulator of fetal hemoglobin (HbF) expression as well as a key modifier of both ?-thalassemia and sickle cell anemia (SCA) phenotypes. Recently, we refined the association signal at this locus by GWAS on 5903 individuals from the SardiNIA project, integrating, with imputation procedure, DNA microarray data and low pass whole-genome sequencing of 2120 Sardinians. Our results revealed two independent SNPs within intron 2 of the BCL11A gene, leading the strongest haplotypic signals and fully accounting for the association observed at this locus. Given that intron 2 shows chromatin signatures of genomic elements with a potential regulatory activity, we carried out functional and expression analysis to asses the specific impact of associated variants in gene action. Preliminary luciferase reporter assays on erythroleukemia cell lines (K562, HEL) have shown a promoter/enhancer activity embedded in the regions encompassing two of them. Notably for one SNP, EMSA on human primary erythroid cells (BFUe) also detected a differential binding pattern showing developmental stage and allele specificity. Furthermore, RT-qPCR and allelic specific expression assays (ASE) conducted on BFUe cells derived from ?-thalassemia patients suggest that the associated SNPs, might function as cis-acting regulatory variants, affecting its expression in a temporal and tissue specific manner. Overall our results support that genetic variants at intron 2 of BCL11A play a crucial role in modulating its function controlling HbF levels with consequent amelioration of ?-thalassemia severity.
Post GWAS analysis of a BCL11A intronic region to define its role in regulating HbF levels
Francesca Anedda;Sonia Sanna;Isadora Asunis;Gianluca Usala;Cristian Antonio Caria;Alessia Loi;Maria Giuseppina Marini;Maria Franca Marongiu;Carlo Sidore;Mauro Pala;Angius Andrea;Fabio Busonero;Andrea Maschio;Maria Serafina Ristaldi;Francesco Cucca;Serena Sanna;Uda Manuela
2013
Abstract
Association studies identified BCL11A transcription factor as the master regulator of fetal hemoglobin (HbF) expression as well as a key modifier of both ?-thalassemia and sickle cell anemia (SCA) phenotypes. Recently, we refined the association signal at this locus by GWAS on 5903 individuals from the SardiNIA project, integrating, with imputation procedure, DNA microarray data and low pass whole-genome sequencing of 2120 Sardinians. Our results revealed two independent SNPs within intron 2 of the BCL11A gene, leading the strongest haplotypic signals and fully accounting for the association observed at this locus. Given that intron 2 shows chromatin signatures of genomic elements with a potential regulatory activity, we carried out functional and expression analysis to asses the specific impact of associated variants in gene action. Preliminary luciferase reporter assays on erythroleukemia cell lines (K562, HEL) have shown a promoter/enhancer activity embedded in the regions encompassing two of them. Notably for one SNP, EMSA on human primary erythroid cells (BFUe) also detected a differential binding pattern showing developmental stage and allele specificity. Furthermore, RT-qPCR and allelic specific expression assays (ASE) conducted on BFUe cells derived from ?-thalassemia patients suggest that the associated SNPs, might function as cis-acting regulatory variants, affecting its expression in a temporal and tissue specific manner. Overall our results support that genetic variants at intron 2 of BCL11A play a crucial role in modulating its function controlling HbF levels with consequent amelioration of ?-thalassemia severity.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
