CHOP, A NOVEL DEVELOPMENTALLY REGULATED NUCLEAR-PROTEIN THAT DIMERIZES WITH TRANSCRIPTION FACTORS C/EBP AND LAP AND FUNCTIONS AS A DOMINANT-NEGATIVE INHIBITOR OF GENE-TRANSCRIPTION
CHOP, A NOVEL DEVELOPMENTALLY REGULATED NUCLEAR-PROTEIN THAT DIMERIZES WITH TRANSCRIPTION FACTORS C/EBP AND LAP AND FUNCTIONS AS A DOMINANT-NEGATIVE INHIBITOR OF GENE-TRANSCRIPTION
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DOI：
10.1101/gad.6.3.439
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发表时间：
1992-03-01
影响因子：
10.5
通讯作者：
HABENER, JF
中科院分区：
文献类型：
--
作者：
RON, D;HABENER, JF
我们报告的鉴定的核蛋白，作为一个显性负抑制剂的转录因子C/EBP和EBP。使用P-32标记的cDNA结合和二聚化结构域“拉链探针”分离编码新的C/EBP同源蛋白CHOP-10的克隆。CHOP-10在对应于由亮氨酸拉链和碱性区域组成的DNA结合结构域的bZIP区域内与C/EBP样蛋白具有很强的序列相似性。然而，值得注意的是，CHOP-10含有2个脯氨酸取代碱性区域中的2个残基，这对于与DNA结合至关重要。因此，CHOP-10和C/EBP样蛋白的异二聚体不能结合它们的同源DNA增强子元件。CHOP-10 mRNA在许多不同的大鼠组织中表达。针对CHOP-10产生的抗血清识别表观分子量为29 kD的核蛋白。CHOP-10在3 T3-L1成纤维细胞分化为脂肪细胞时被诱导，并且在细胞核CHOP-10的损失之前，胆固醇诱导的脂肪细胞的去分化。从转染的COS-1细胞的CHOP-10和cDNA 3的免疫共沉淀证明了两种蛋白质之间的直接相互作用，在体内。与其有缺陷的碱性区的结构一致，细菌表达的CHOP-10通过形成不能结合DNA的异二聚体来抑制C/EBP和EBP的DNA结合活性。在转染的HepG 2细胞中，CHOP-10的表达减弱了C/EBP和LAP驱动的启动子的激活。我们认为，CHOP-10是一个负调制器的C/EBP样蛋白的活性在某些终末分化的细胞，类似于调节功能的ID上的活动的MyoD和MyoD相关蛋白的重要肌肉细胞的发展。
We report on the identification of a nuclear protein that serves as a dominant-negative inhibitor of the transcription factors C/EBP and LAP. A P-32-labeled LAP DNA-binding and dimerization domain "zipper probe" was used to isolate a clone that encodes a new C/EBP-homologous protein: CHOP-10. CHOP-10 has strong sequence similarity to C/EBP-like proteins within the bZIP region corresponding to the DNA-binding domain consisting of a leucine zipper and a basic region. Notably, however, CHOP-10 contains 2 prolines substituting for 2 residues in the basic region, critical for binding to DNA. Thus, heterodimers of CHOP-10 and C/EBP-like proteins are unable to bind their cognate DNA enhancer element. CHOP-10 mRNA is expressed in many different rat tissues. Antisera raised against CHOP-10 recognize a nuclear protein with an apparent molecular mass of 29 kD. CHOP-10 is induced upon differentiation of 3T3-L1 fibroblasts to adipocytes, and cytokine-induced dedifferentiation of adipocytes is preceded by the loss of nuclear CHOP-10. Coimmunoprecipitation of CHOP-10 and LAP from transfected COS-1 cells demonstrated a direct interaction between the two proteins, in vivo. Consistent with the structure of its defective basic region, bacterially expressed CHOP-10 inhibits the DNA-binding activity of C/EBP and LAP by forming heterodimers that cannot bind DNA. In transfected HepG2 cells, expression of CHOP-10 attenuates activation of C/EBP- and LAP-driven promoters. We suggest that CHOP-10 is a negative modulator of the activity of C/EBP-like proteins in certain terminally differentiated cells, similar to the regulatory function of Id on the activity of MyoD and MyoD-related proteins important in the development of muscle cells.