C/EBPβ reprograms white 3T3-L1 preadipocytes to a brown adipocyte pattern of gene expression
C/EBPβ reprograms white 3T3-L1 preadipocytes to a brown adipocyte pattern of gene expression
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DOI：
10.1074/jbc.m703101200
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发表时间：
2007-08-24
影响因子：
4.8
通讯作者：
Lomax, Michael A.
中科院分区：
文献类型：
--
作者：
Karamanlidis, Georgios;Karamitri, Angeliki;Lomax, Michael A.
cAMP依赖性蛋白激酶诱导PPAR γ共激活因子-1 α（PGC-1 α）和解偶联蛋白1（UCP 1）表达是前脂肪细胞向棕色脂肪组织（BAT）谱系定型的重要步骤。我们研究了PGC-1 α在HIB 1B（BAT）和3 T3-L1白色脂肪组织（WAT）前体细胞系中差异表达的分子机制。在HIB 1B细胞中，PGC-1 α和UCP 1的表达是cAMP诱导的，但在3 T3-L1细胞中，表达降低并且是cAMP不敏感的。一个近端264 bp的PGC-1 α报告基因构建体仅在HIB 1B细胞中是cAMP诱导型的，并通过近端cAMP反应元件（CRE）的定点诱变而被抑制。在电泳迁移率变动分析中，转录因子CREB和C/EBP β，而不是C/EBP α和C/EBP β，与HIB 1B和3 T3-L1细胞中PGC-1 α启动子区域上的CRE结合。染色质免疫沉淀研究表明，在HIB 1B和3 T3-L1细胞裂解物中，C/EBP β和CREB与CRE区域结合。cAMP仅在HIB 1B细胞中诱导C/EBP α表达，而在3 T3-L1细胞中，C/EBP β的过表达拯救了cAMP诱导的PGC-1 α和UCP 1表达。这些数据表明，前脂肪细胞向BAT而不是WAT表型的分化部分是由C/EBP β对PGC-1 α近端启动子中的CRE的作用控制的。
cAMP-dependent protein kinase induction of PPAR gamma coactivator-1 alpha (PGC-1 alpha) and uncoupling protein 1 (UCP1) expression is an essential step in the commitment of preadipocytes to the brown adipose tissue (BAT) lineage. We studied the molecular mechanisms responsible for differential expression of PGC-1 alpha in HIB1B (BAT) and 3T3-L1 white adipose tissue (WAT) precursor cell lines. In HIB1B cells PGC-1 alpha and UCP1 expression is cAMP-inducible, but in 3T3-L1 cells, expression is reduced and is cAMP-insensitive. A proximal 264-bp PGC-1 alpha reporter construct was cAMP-inducible only in HIB1B cells and was suppressed by site-directed mutagenesis of the proximal cAMP response element (CRE). In electrophoretic mobility shift assays, the transcription factors CREB and C/EBP beta, but not C/EBP alpha and C/EBP beta, bound to the CRE on the PGC-1 alpha promoter region in HIB1B and 3T3-L1 cells. Chromatin immuno-precipitation studies demonstrated that C/EBP beta and CREB bound to the CRE region in HIB1B and 3T3-L1 cell lysates. C/EBP alpha expression was induced by cAMP only in HIB1B cells, and overexpression of C/EBP beta rescued cAMP-inducible PGC-1 alpha and UCP1 expression in 3T3-L1 cells. These data demonstrate that differentiation of preadipocytes toward the BAT rather than the WAT phenotype is controlled in part by the action of C/EBP beta on the CRE in PGC-1 alpha proximal promoter.