Sanquin Research, Department of Hematopoiesis, Amsterdam, The Netherlands, and Landsteiner Laboratory, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.
Sanquin Research, department of Immunohematology Experimental, Amsterdam, The Netherlands, and Landsteiner Laboratory, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.
Sci Rep. 2021 Sep 17;11(1):18557. doi: 10.1038/s41598-021-97149-y.
Beta-hemoglobinopathies become prominent after birth due to a switch from γ-globin to the mutated β-globin. Haploinsufficiency for the erythroid specific indispensable transcription factor Krueppel-like factor 1 (KLF1) is associated with high persistence of fetal hemoglobin (HPFH). The In(Lu) phenotype, characterized by low to undetectable Lutheran blood group expression is caused by mutations within KLF1 gene. Here we screened a blood donor cohort of 55 Lutheran weak or negative donors for KLF1 variants and evaluated their effect on KLF1 target gene expression. To discriminate between weak and negative Lutheran expression, a flow cytometry (FCM) assay was developed to detect Lu antigen expression. The Lu(a-b-) (negative) donor group, showing a significant decreased CD44 (Indian blood group) expression, also showed increased HbF and HbA2 levels, with one individual expressing HbF as high as 5%. KLF1 exons and promoter sequencing revealed variants in 80% of the Lutheran negative donors. Thirteen different variants plus one high frequency SNP (c.304 T > C) were identified of which 6 were novel. In primary erythroblasts, knockdown of endogenous KLF1 resulted in decreased CD44, Lu and increased HbF expression, while KLF1 over-expressing cells were comparable to wild type (WT). In line with the pleiotropic effects of KLF1 during erythropoiesis, distinct KLF1 mutants expressed in erythroblasts display different abilities to rescue CD44 and Lu expression and/or to affect fetal (HbF) or adult (HbA) hemoglobin expression. With this study we identified novel KLF1 variants to be include into blood group typing analysis. In addition, we provide further insights into the regulation of genes by KLF1.
β-地中海贫血症由于从 γ-珠蛋白向突变的 β-珠蛋白的转换而在出生后变得明显。红细胞特异性必需转录因子 Krueppel 样因子 1（KLF1）的单倍体不足与胎儿血红蛋白（HbF）的高度持续存在相关。In(Lu)表型的特征是低至无法检测到的路丁氏血型组表达，是由 KLF1 基因内的突变引起的。在这里，我们筛选了 55 名路丁氏血型弱或阴性献血者的献血者队列，以筛选 KLF1 变体，并评估其对 KLF1 靶基因表达的影响。为了区分弱表达和阴性表达，开发了一种流式细胞术（FCM）检测 Lu 抗原表达的方法。Lu(a-b-)（阴性）供体组显示 CD44（印度血型）表达显著降低，也显示 HbF 和 HbA2 水平增加，其中一个个体的 HbF 表达高达 5%。KLF1 外显子和启动子测序显示，80%的路丁氏阴性供体存在变体。鉴定出 13 种不同的变体加一种高频 SNP（c.304T>C），其中 6 种是新的。在原代红细胞中，内源性 KLF1 的敲低导致 CD44、Lu 减少和 HbF 表达增加，而 KLF1 过表达细胞与野生型（WT）相当。与 KLF1 在红细胞生成过程中的多效性效应一致，在红细胞中表达的不同 KLF1 突变体具有不同的能力来挽救 CD44 和 Lu 表达，和/或影响胎儿（HbF）或成人（HbA）血红蛋白表达。通过这项研究，我们确定了新的 KLF1 变体，以纳入血型分型分析。此外，我们提供了 KLF1 对基因调控的进一步见解。
