Ngai J, Bond V C, Wold B J, Lazarides E
Division of Biology, California Institute of Technology, Pasadena 91125.
Mol Cell Biol. 1987 Nov;7(11):3955-70. doi: 10.1128/mcb.7.11.3955-3970.1987.
We studied the expression of transfected chicken and hamster vimentin genes in murine erythroleukemia (MEL) cells. MEL cells normally repress the levels of endogenous mouse vimentin mRNA during inducermediated differentiation, resulting in a subsequent loss of vimentin filaments. Expression of vimentin in differentiating MEL cells reflects the disappearance of vimentin filaments during mammalian erythropoiesis in vivo. In contrast, chicken erythroid cells express high levels of vimentin mRNA and vimentin filaments during terminal differentiation. We demonstrate here that chicken vimentin mRNA levels increase significantly in differentiating transfected MEL cells, whereas similarly transfected hamster vimentin genes are negatively regulated. In conjunction with in vitro nuclear run-on transcription experiments, these results suggest that the difference in vimentin expression in avian and mammalian erythropoiesis is due to a divergence of cis-linked vimentin sequences that are responsible for transcriptional and posttranscriptional regulation of vimentin gene expression. Transfected chicken vimentin genes produce functional vimentin protein and stable vimentin filaments during MEL cell differentiation, further demonstrating that the accumulation of vimentin filaments is determined by the abundance of newly synthesized vimentin.
我们研究了转染的鸡和仓鼠波形蛋白基因在小鼠红白血病（MEL）细胞中的表达。MEL细胞在诱导介导的分化过程中通常会抑制内源性小鼠波形蛋白mRNA的水平，导致波形蛋白丝随后丢失。波形蛋白在分化的MEL细胞中的表达反映了体内哺乳动物红细胞生成过程中波形蛋白丝的消失。相比之下，鸡红细胞在终末分化过程中表达高水平的波形蛋白mRNA和波形蛋白丝。我们在此证明，在分化的转染MEL细胞中鸡波形蛋白mRNA水平显著增加，而类似转染的仓鼠波形蛋白基因则受到负调控。结合体外细胞核连续转录实验，这些结果表明鸟类和哺乳动物红细胞生成中波形蛋白表达的差异是由于负责波形蛋白基因表达转录和转录后调控的顺式连接波形蛋白序列的分歧。转染的鸡波形蛋白基因在MEL细胞分化过程中产生功能性波形蛋白和稳定的波形蛋白丝，进一步证明波形蛋白丝的积累由新合成的波形蛋白的丰度决定。
