Tanaka Y, Watanabe T, Chiba N, Niki M, Kuroiwa Y, Nishihira T, Satomi S, Ito Y, Satake M
Department of Molecular Immunology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan.
Oncogene. 1997 Aug 7;15(6):677-83. doi: 10.1038/sj.onc.1201235.
The Pebpb2/Cbfb gene encodes the non-DNA binding beta subunit of the heterodimeric transcription factor, PEBP2/CBF, and has been implicated in a subtype of human acute myeloid leukemia, as well as being indispensable for the development of definitive hematopoiesis in the murine fetal liver. By examining a subcellular localization of the PEBP2beta/CBFbeta protein in tissue culture cells, we could reveal an additional aspect of the protein other than to be a subunit of a transcription factor. Immunoblot and immunocytochemical staining showed that PEBP2beta/CBFbeta was mostly present in the cytoplasm. This PEBP2beta/CBFbeta was free from its DNA-binding partner, the alpha subunit of PEBP2/CBF, as judged by the electrophoretic mobility shift assays. Furthermore, a significant amount of PEBP2beta/CBFbeta was retained in the cytoskeleton preparation after detergent extraction of the cells and was found by double immunofluorescence to colocalize with the F-actin on stress fibers and the vinculin in membrane processes. Thus, the present study extends PEBP2beta/CBFbeta to be a cytoskeleton-affinitive as well as nuclear protein. The implications of these results are discussed.
Pebpb2/Cbfb基因编码异二聚体转录因子PEBP2/CBF的非DNA结合β亚基，它与人类急性髓系白血病的一个亚型有关，并且对小鼠胎儿肝脏中确定性造血的发育不可或缺。通过检测组织培养细胞中PEBP2β/CBFβ蛋白的亚细胞定位，我们发现了该蛋白除作为转录因子亚基之外的其他方面。免疫印迹和免疫细胞化学染色显示，PEBP2β/CBFβ主要存在于细胞质中。通过电泳迁移率变动分析判断，这种PEBP2β/CBFβ与其DNA结合伴侣PEBP2/CBF的α亚基分离。此外，在用去污剂提取细胞后，大量的PEBP2β/CBFβ保留在细胞骨架制剂中，通过双重免疫荧光发现它与应力纤维上的F-肌动蛋白以及膜突中的纽蛋白共定位。因此，本研究表明PEBP2β/CBFβ不仅是一种核蛋白，也是一种与细胞骨架亲和的蛋白。我们对这些结果的意义进行了讨论。
