Identification of the causative gene for inherited sideroblastic anemia and analysis of sideroblastis induced in vitro

遗传性铁粒幼细胞贫血致病基因的鉴定及体外诱导铁粒幼细胞的分析

基本信息

批准号：
11670977
负责人：
HARIGAE Hideo
金额：
$ 2.3万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

alas2 encodes the erythroid specific 8-aniinoleyuIinate synthase (ALAS2), the first enzyme in heme biosynthesis in erythroid cells. In vivo in mice, alas2-null primitive erythroblasts showed a maturation arrest as well as massive cytoplasmic iron accumulation. However, the effect of ALAS2 deficiency, on definitive erythropoiesis still remains unclear, because alas2-null mice died in utero by embryonic day 11.5 before definitive erythropoiesis developed. To clarity the effect of heme deficiency on differentiation of definitive erythroid cells, ES cells lacking the alas2 gene were induced to differentiate specifically into erythroid lineage in vitro, and phenotypes of definitive erythroblasts were examined. In comparison to red cell pellets of Wild-type erythroblasts, alas2-null definitive erythroblasts were totally white due to a marked deficiency of heme, although the morphology was similar to wild-type erythroblasts. Consistent with their similar morphology, levels of erythroid-specific gene expression such as GATA-1, NF-E2 andTER119 in alas2-null definitive erythroblasts were also similar to those of wild-type cells, indicating that both alas2-null and wild-type erythroblasts developed to the stage of mature definitive erythroblasts. In contrast to their similar morphology, however, iron content in alas2-null definitive erythroblasts was twice more than that of wild-type, cells. Consistent with the aberrant increase in iron content, alas2-null definitive erythroblasts were more oxidized compared with wild-type erythroblasts as judged by increased formation of peroxidized metabolites. These findings suggest that alas2 deficiency does not influence erythroid differentiation per se, but induces aberrant iron accumulation and oxidized condition in definitive erythroblasts.

ALAS2编码红细胞生物合成酶（ALAS2），这是红绿色细胞血红素生物合成的第一种酶。在小鼠体内，Alas2-null原始成红细胞显示成熟的停滞以及大量的细胞质铁积累。然而，Alas2缺乏症对确定性红细胞生成的影响仍然不清楚，因为Alas2-null小鼠在胚胎第11.5天在子宫内死亡。为了清楚血红素缺乏对确定红细胞细胞分化的影响，缺乏ALAS2基因的ES细胞在体外特异性分化为红细胞谱系，并检查了确定的红细胞的表型。与野生型红细胞的红细胞颗粒相比，由于形态明显缺乏血红素，Alas2-Null确定的红细胞完全是白色的，尽管形态类似于野生型红细胞。与它们相似的形态，促红细胞特异性基因表达的水平（例如GATA-1，NF-E2 Andter119）在Alas2-Null确定的确定性红细胞中也与野生型细胞相似，这表明Alas2-Null和野生型成年型成年型红细胞都会发展为Mature eRy的阶段。然而，与它们相似的形态相反，Alas2-null确定的红细胞中铁含量是野生型细胞的两倍。与铁含量的异常增加一致，与野生型红细胞相比，Alas2-Null确定的红细胞被氧化更多，这是通过增加过氧化代谢物的形成来判断的。这些发现表明，Alas2缺乏本身不会影响红系分化，而是在确定的红细胞中诱导异常的铁积累和氧化条件。