KLF1基因表达的负调控机制及其对β地中海贫血表型修饰作用研究

Erythroid Krüppel-like factor KLF1 is a master regulator of erythropoiesis and has recently emerged as one of the key regulators of the γ- to β-globin gene switch. Due to little or no production of HbA, expression of HbF becomes the major genetic factor altering the severity of β-thalassemia, which may accounts for the phenotypic diversity of β-thalassemia. Previously, we have reported that haploinsufficiency of KLF1 results in significant increases in fetal hemoglobin (HbF) levels and attenuation of the severity of β-thalassemia, which reflects the underlying dose-respond effect between KLF1 gene expression and phenotype of β-thalassemia. Recently, we proved that the transcriptional activity of KLF1 was inhibited by promoter DNA methylation. In addition, we conducted pre-tests and found that two miRNAs can inhibit KLF1 expression. Given to these findings, we aim to find KLF1 negative regulatory factors and analyze its effects on phenotypic modification in patients with β-thalassemia. It may provide a rationale for epigenetics in phenotypic diversity of β-thalassemia, and new genetic information and data for treatment, pathogenesis as well as genetic counseling in β-thalassemia.

红系特异转录因子KLF1是红细胞发育中关键的细胞因子，直接参与调控了胎儿血红蛋白（HbF）向成人血红蛋白（HbA）转化过程。β地中海贫血（β地贫）患者的临床表型从中间型到重型存在很大差异，由于HbA的生成障碍，HbF的表达水平成为影响β地贫临床表型严重性的主要遗传因素。前期研究中我们已报道：人类KLF1基因变异导致的单倍型不足可以使HbF持续表达，进而缓解β地贫患者的临床表型，这提示KLF1基因对表型的影响存在剂量效应。我们前期研究证明KLF1基因启动子区域甲基化对其表达起到抑制作用，此外预实验初步发现2个miRNA对KLF1表达有抑制作用。因此本研究将以KLF1表达负调控机制为切入点，分析其对β地贫患者临床表型的修饰作用，为解释β地贫临床表型多样性提供表观遗传学基础证据，为β地贫临床诊治、发病机制和遗传咨询提供新的遗传知识和依据。

红系特异转录因子KLF1是γ珠蛋白向β珠蛋白转换的重要开关，我们前期研究中证实人类KLF1基因变异导致的单倍型不足可以使HbF持续表达，进而缓解β-地中海贫血患者的临床表型。随后，我们建立和优化了基于高分辨熔解曲线（HRM）对KLF1突变高通量筛查的体系，为进一步进行KLF1突变群体遗传学研究打下基础。近期，通过建立稳定的KLF1启动子CpG位点甲基化程度检测体系，证明了KLF1基因启动子区域CpG位点甲基化具有组织特异性并直接抑制KLF1基因表达；另一方面，我们研究证实了miRNA-326和miRNA-432-5p可以通过结合KLF1基因3'UTR抑制基因表达，且miRNA-326与β-地贫的HbF表达正相关，这两个miRNA有望成为一个新的预测β-地贫表型的分子标记。因此，我们通过对KLF1基因表达的负调控研究，有助于我们理解为β-地贫临床表型的多样性，为日后的临床诊治、发病机制和遗传咨询提供新的遗传知识和依据。