Blau H M, Chiu C P, Webster C
Cell. 1983 Apr;32(4):1171-80. doi: 10.1016/0092-8674(83)90300-8.
We have induced the stable expression of muscle-specific genes in human nonmuscle cells. Normal diploid human amniocytes were fused with differentiated mouse muscle cells by using polyethylene glycol. The fusion product, a stable heterocaryon in which the parental cell nuclei remained distinct, did not undergo division and retained a full complement of chromosomes. This is in contrast with typical interspecific hybrids (syncaryons), in which the parental nuclei are combined and chromosomes are progressively lost during cell division. The human muscle proteins, myosin light chains 1 and 2, MB and MM creatine kinase and a functional mouse-human hybrid MM enzyme molecule were detected in the heterocaryons. Synthesis of these proteins was evident 24 hr after fusion and increased in a time-dependent manner thereafter. Our results indicate that differentiated mouse muscle nuclei can activate human muscle genes in the nuclei of a cell type in which they are not normally expressed, and that this activation occurs via the cytoplasm. The activators are still present in cells which have already initiated differentiation, are recognized by nuclei of another species, and do not diffuse between unfused cells. The reprogrammed amniocyte nuclei of stable heterocaryons provide a unique system in which to study the mechanisms regulating gene expression during cell specialization.
我们已在人类非肌肉细胞中诱导了肌肉特异性基因的稳定表达。通过使用聚乙二醇，将正常的二倍体人类羊膜细胞与分化的小鼠肌肉细胞融合。融合产物是一种稳定的异核体，其中亲代细胞核保持明显区分，不进行分裂并保留完整的染色体组。这与典型的种间杂种（合核体）形成对比，在种间杂种中，亲代细胞核合并，并且在细胞分裂过程中染色体逐渐丢失。在异核体中检测到了人类肌肉蛋白，肌球蛋白轻链1和2、MB和MM肌酸激酶以及一种功能性的小鼠 - 人类杂种MM酶分子。这些蛋白质的合成在融合后24小时就很明显，此后以时间依赖性方式增加。我们的结果表明，分化的小鼠肌肉细胞核可以在一种它们通常不表达的细胞类型的细胞核中激活人类肌肉基因，并且这种激活是通过细胞质发生的。激活剂仍然存在于已经开始分化的细胞中，能被另一个物种的细胞核识别，并且不会在未融合的细胞之间扩散。稳定异核体中重编程的羊膜细胞核提供了一个独特的系统，用于研究细胞特化过程中调节基因表达的机制。
