Laszlo A, Wright W, Roti Roti J L
Section of Cancer Biology, Mallinckrodt Institute of Radiology, Washington University Medical Center, St. Louis, Missouri 63108.
J Cell Physiol. 1992 Jun;151(3):519-32. doi: 10.1002/jcp.1041510311.
Exposure of mammalian cells to hyperthermia is known to cause protein aggregation in the nucleus. The presence of such aggregates has been detected as the relative increase in the protein mass that is associated with nuclei isolated from heated cells. We have characterized these excess nuclear proteins from the nuclei of heated HeLa cells by two-dimensional gel electrophoresis. The abundance of cytoskeletal elements which co-purify with the nuclei did not increase with exposure to hyperthermia, indicating that these proteins are not part of the excess nuclear proteins. In contrast, several specific polypeptides become newly bound or increase in abundance in nuclei isolated from heated cells. Members of the hsp 70 family were identified as a major component of the excess nuclear proteins. Among the other excess nuclear proteins we identified ten that had apparent molecular weights of 130, 95, 75, 58, 53, 48, 46, 37, 28, and 26 kilodaltons. Since hsp 70 is mainly cytoplasmic in non-heated cells, its association with nuclei in heated cells indicates that one mechanism accounting for the heat-induced excess nuclear proteins is the movement of cytoplasmic proteins to the nucleus. We also obtained evidence that increased binding of nuclear proteins is another mechanism for this effect. No overall increase or decrease in the phosphorylation of nuclear proteins was found to be associated with such altered binding or movement from the cytoplasm to the nucleus.
已知将哺乳动物细胞暴露于高温会导致细胞核内蛋白质聚集。已检测到此类聚集体的存在表现为与从受热细胞中分离出的细胞核相关的蛋白质质量相对增加。我们通过二维凝胶电泳对受热的HeLa细胞核中的这些过量核蛋白进行了表征。与细胞核共同纯化的细胞骨架成分的丰度不会因暴露于高温而增加，这表明这些蛋白质不是过量核蛋白的一部分。相反，在从受热细胞中分离出的细胞核中，几种特定的多肽会新结合或丰度增加。热休克蛋白70（hsp 70）家族成员被鉴定为过量核蛋白的主要成分。在其他过量核蛋白中，我们鉴定出十种表观分子量分别为130、95、75、58、53、48、46、37、28和26千道尔顿的蛋白。由于hsp 70在未受热的细胞中主要存在于细胞质中，其在受热细胞中与细胞核的结合表明，导致热诱导过量核蛋白的一种机制是细胞质蛋白向细胞核的移动。我们还获得了证据，表明核蛋白结合增加是造成这种效应的另一种机制。未发现核蛋白磷酸化的总体增加或减少与这种结合改变或从细胞质向细胞核的移动有关。
