Hanspal M, Yoon S H, Yu H, Hanspal J S, Lambert S, Palek J, Prchal J T
Department of Biomedical Research, St. Elizabeth's Hospital of Boston, MA 02135.
Blood. 1991 Jan 1;77(1):165-73.
While varying degrees of spectrin deficiency have been found in the majority of patients with hereditary spherocytosis (HS), a combined severe deficiency of both spectrin and the spectrin-binding protein, ankyrin, has been reported only in two patients with severe HS. To elucidate the molecular basis of these protein deficiencies, we have studied the synthesis, assembly, and the mRNA levels of spectrin and ankyrin in peripheral blood reticulocytes in one of the previously reported probands. Pulse-labeling studies showed that in HS reticulocytes, the synthesis of alpha-spectrin was comparable with control reticulocytes while that of beta-spectrin was increased about fourfold, presumably reflecting increased erythropoietic drive. On the HS reticulocyte membrane, the amount of newly assembled spectrin was reduced to about half of the control values, presumably reflecting a decrease in the synthesis of the spectrin binding protein, ankyrin: the ankyrin synthesis was nearly absent in the cytosol and the amounts of membrane-associated ankyrin were reduced to about half of the normal values. The changes in the amounts of spectrin and ankyrin mRNAs quantitated by slot blot and Northern blot analyses were comparable with changes in the synthesis of these proteins: The alpha spectrin mRNA was within a control range and the beta-spectrin mRNA was slightly increased, while the amounts of ankyrin mRNA were reduced to about 50% of control values. We conclude that the primary defect underlying the combined spectrin and ankyrin deficiency is a deficiency of ankyrin mRNA leading to a reduced synthesis of ankyrin which, in turn, underlies the decreased assembly of spectrin on the membrane.
虽然在大多数遗传性球形红细胞增多症（HS）患者中发现了不同程度的血影蛋白缺乏，但仅在两名重症HS患者中报道了血影蛋白和血影蛋白结合蛋白锚蛋白均严重缺乏的情况。为了阐明这些蛋白质缺乏的分子基础，我们研究了先前报道的一名先证者外周血网织红细胞中血影蛋白和锚蛋白的合成、组装及mRNA水平。脉冲标记研究表明，在HS网织红细胞中，α-血影蛋白的合成与对照网织红细胞相当，而β-血影蛋白的合成增加了约四倍，这可能反映了红细胞生成驱动力的增加。在HS网织红细胞膜上，新组装的血影蛋白量减少至对照值的约一半，这可能反映了血影蛋白结合蛋白锚蛋白合成的减少：锚蛋白在胞质溶胶中几乎不合成，膜相关锚蛋白的量减少至正常值的约一半。通过狭缝印迹和Northern印迹分析定量的血影蛋白和锚蛋白mRNA量的变化与这些蛋白质合成的变化相当：α-血影蛋白mRNA在对照范围内，β-血影蛋白mRNA略有增加，而锚蛋白mRNA量减少至对照值的约50%。我们得出结论，血影蛋白和锚蛋白联合缺乏的主要缺陷是锚蛋白mRNA缺乏，导致锚蛋白合成减少，进而导致血影蛋白在膜上的组装减少。
