野生型及启动子区突变的HPFHAγ基因在MEL细胞中的表达

Expression of Wild Type of Human Aγ Globin Gene and HPFH Aγ Gene with Point Mutation in MEL Cells

研究了野生型Ａγ珠蛋白基因、中国型胎儿血红蛋白持续存在综合症（ＨＰＦＨ）Ａγ基因（启动子区─１９６Ｃ→Ｔ突变）及希腊型ＨＰＦＨＡγ基因（─１１７Ｇ→Ａ突变）在鼠红白血病（ＭＥＬ）ＧＭ９７９细胞中的表达。比较每个整合的Ａγ基因表达的ｍＲＮＡ量，─１９６Ｃ→Ｔ突变Ａγ基因未显示比野生型Ａγ基因明显增加的表达水平，而─１１７Ｇ→Ａ突变Ａγ基因在未分化的及ＨＭＢＡ或丁酸钠诱导分化的ＭＥＬＧＭ９７９细胞中的表达水平增加到野生型Ａγ基因相应水平的２．３倍至３．１倍。此结果提供了又一个实验证据，说明启动子─１１７Ｇ→Ａ突变是希腊型ＨＰＦＨ中胎儿Ａγ基因在成人中持续活跃表达的原因，这也为β地中海贫血和镰刀性贫血的基因治疗提供了新途径，即可以考虑用转移─１１７Ｇ→Ａ突变Ａγ基因的方法改善患者的贫血症状。

We constructed three expression plasmids that contain wild type of human A γ globingene or the Chinese hereditary persistence of fetal haemoglobin (HPFH) Aγ gene (─196C→T)or the Greek HPFH Ay genet (─117G→A) and studied expression of the Aγ genes in mouse erythroleukemia (MEL) GM979 cells. No obvious increase of HPFH Aγ 196 (C→T) gene expression in contrast to the wild type of Aγ globin gene was observed when the γmRNA was plotted into integrated Ay gene copy number. However,the expression level of the HPFH Aγ117 (G→A)globin gene was 2. 3,3. 1 and 2. 4 times of that of the wild type of Aγ globin gene in uninduced,HMBA-induced and butyrate-induced MEL GM979 cells respectively. The results provideda further proof that─117 G→A mutation of the Aγ gene promoter is the cause of persistent active expression of the gene in the Greek HPFH syndromes. The results also suggested a new way of gene therapy for β-thalassemias and sickle cell anaemia. It is considerable to transfer the Aγ11 7 (G→A) globin gene into human haematopoietic stem cells to ameliorate the severity of the diseases.