Rakowicz-Szulczynska E M
Wistar Institute of Anatomy and Biology, Philadelphia, Pennsylvania 19104.
J Cell Physiol. 1993 Jan;154(1):64-70. doi: 10.1002/jcp.1041540109.
125I-nerve growth factor (NGF) was found to be internalized and translocated to the nucleus of SKBr5 breast carcinoma cells. The cytoplasm and chromatin isolated from nonmitotic cells accumulated two- and five-fold, respectively, more of 125I-NGF than the cells undergoing mitosis. MAb 20.4 developed against the NGF cell surface receptor immunoprecipitated the 80,000 M(r) receptor from plasma membrane and two protein species from the chromatin; 90,000 M(r) (major band) and 200,000 M(r) (minor band). In SKBr5 cells, binding of NGF to the chromatin did not affect synthesis of rRNA. Proliferation of SKBr5 cells was slightly stimulated by NGF. In control melanoma A875 cells, which express the 230,000 M(r) chromatin receptor, NGF inhibited both rRNA synthesis and cell proliferation. We suggest that the 90,000 M(r) chromatin receptor expressed by SKBr5 cells represents a "nonactive," ligand-binding subunit of the high molecular weight receptor for NGF. The critical role of the chromatin receptor for NGF in rRNA-dependent cell proliferation is discussed.
发现125I-神经生长因子（NGF）被内化并转移至SKBr5乳腺癌细胞的细胞核。从非有丝分裂细胞中分离出的细胞质和染色质积累的125I-NGF分别比处于有丝分裂的细胞多两倍和五倍。针对NGF细胞表面受体产生的单克隆抗体20.4从质膜免疫沉淀出80,000 M（r）受体，并从染色质中免疫沉淀出两种蛋白质；90,000 M（r）（主要条带）和200,000 M（r）（次要条带）。在SKBr5细胞中，NGF与染色质的结合不影响rRNA的合成。NGF对SKBr5细胞的增殖有轻微刺激作用。在表达230,000 M（r）染色质受体的对照黑色素瘤A875细胞中，NGF抑制rRNA合成和细胞增殖。我们认为，SKBr5细胞表达的90,000 M（r）染色质受体代表了NGF高分子量受体的“非活性”配体结合亚基。文中讨论了NGF染色质受体在依赖rRNA的细胞增殖中的关键作用。
