Dainiak N, Tan B J
Department of Medicine, Royal Victoria Hospital, McGill University, Montreal, Quebec, Canada.
Stem Cells. 1995 May;13 Suppl 1:142-52.
In addition to interacting with genomic DNA, ionizing radiation may directly and indirectly alter the structure and function of components of the plasma membrane of eukaryotic cells. Water radiolysis generates reactive species, including superoxide, hypochlorous acid and chloride radicals that may in turn react with biological membranes, as well as with cellular DNA. Reaction of plasma membrane lipids with molecular oxygen results in lipid peroxidation of both reconstituted membranes and biological membranes, an effect that increases with decreasing dose rate. Both ionizing radiation and ultraviolet light alter functions of membrane-anchored molecules, including adhesion molecules, histocompatibility complex antigens and membrane-bound growth factors. The latter growth factors represent a repertoire of growth and differentiation signals that are expressed in a nondiffusible fashion at the cell surface, and in soluble forms appearing after cleavage of their extracellular domain. The importance of cell-cell signaling via the membrane-anchored form of growth factors is becoming increasingly recognized. Expression of membrane-bound hematopoietic cytokines by eukaryotic cells is impaired after exposure to ultraviolet light, a defect in cell-cell signaling that may lead to impaired hematopoiesis. While studies suggest that permanent changes in membrane structure and function may result from radiation-induced injury to the plasma membrane and reconstituted "pure" membranes, reversibility of these defects over time requires additional study.
除了与基因组DNA相互作用外，电离辐射还可能直接或间接改变真核细胞质膜成分的结构和功能。水辐射分解产生活性物质，包括超氧化物、次氯酸和氯自由基，这些物质可能反过来与生物膜以及细胞DNA发生反应。质膜脂质与分子氧的反应会导致重构膜和生物膜的脂质过氧化，这种效应会随着剂量率的降低而增加。电离辐射和紫外线都会改变膜锚定分子的功能，包括黏附分子、组织相容性复合体抗原和膜结合生长因子。后者的生长因子代表了一系列生长和分化信号，它们以不可扩散的方式在细胞表面表达，并以其细胞外结构域裂解后出现的可溶形式存在。通过膜锚定形式的生长因子进行细胞间信号传导的重要性正日益得到认可。真核细胞暴露于紫外线后，其膜结合造血细胞因子的表达会受损，这是一种细胞间信号传导缺陷，可能导致造血功能受损。虽然研究表明，质膜和重构的“纯”膜受到辐射诱导的损伤可能会导致膜结构和功能的永久性变化，但这些缺陷随时间的可逆性还需要进一步研究。
