A control mechanism of gene expression in red cell membranes

(1)红细胞异常表型的表征：在我们2年的研究期间（1998年和1999年），我们研究了135个先天性红细胞异常家族175例，其中遗传性球形红细胞增多症（HS） 100个家族118例。临床表型由临床血液学研究、膜蛋白生物化学、分子电子显微镜和生物物理分析确定。（II） HS基因型分析：在3带基因（EPB3）上检测到12个致病突变：移码突变4个，错义突变8个，基因多态性7个。在锚蛋白基因（ANK1）上，鉴定出16个致病突变（4个无义突变、8个移码突变和4个异常剪接）和17个基因多态性（2个错义突变和15个沉默突变）。在蛋白4.2基因（ELB42）上发现3个病理错义突变。（III）红细胞分化过程中膜蛋白的顺序表达：在人红细胞中，光谱蛋白和条带3在早期红细胞前体中表达，蛋白4.1随后表达，蛋白4.2最终在很晚的红细胞中依次表达。（IV） EPB3、SPTB和elb42启动子区域的5′-CpG-3′位点的甲基化状态。在SPTB中，所有的5′-CpG-3′位点都完全未甲基化，而EPB3中几乎完全甲基化。在ELB42中，虽然在成熟的红细胞中所有位点几乎完全甲基化，但在非常早期的红母细胞中没有甲基化。

(I) Characterization of the phenotypes of red cell membrane disorders :During our research term for 2 years (1998 and 1999), we have studied 175 cases from 135 kindred of congenital red cell membrane disorders including 118 patients from 100 kindred of hereditary spherocytosis (HS). Clinical phenotypes were determined by clinical hematology studies, membrane protein biochemistry, molecular electron microscopy, and biophysical analyses.(II) Genotypic analyses in HS :On the band 3 gene (EPB3), 12 pathognomonic mutations were detected : 4 frameshift mutations and 8 missense mutations with 7 gene polymorphisms. On the ankyrin gene (ANK1), 16 pathognomonic mutations (4 nonsense mutations, 8 frameshift mutations, and 4 abnormal splicings) with 17 gene polymorphisms (2 missense mutations and 15 silent mutations) were identified. On the protein 4.2 gene (ELB42), 3 pathognomonic missense mutations had been found.(III) Sequential expression of membrane proteins during erythroid differentiation :In human red cell membranes, spectrins and band 3 were expressed in early erythroid precursors, protein 4.1 followed, and protein 4.2 was finally expressed at the very late erythroblasts sequentially.(IV) The state of methylation of 5'-CpG-3' sites of the promoter regions of EPB3, SPTB, and ELB42In SPTB, all of the 5'-CpG-3' sites were totally unmethylated, in contrast to nearly total methylation in EPB3. In ELB42, methylation was absent in very early erythroblasts, although all the sites were nearly completely methylated in mature erythroid cells.