Identification and characterization of novel peroxisome proliferator-activated receptor-gamma (PPAR-γ) transcriptional variants in pig and human
Identification and characterization of novel peroxisome proliferator-activated receptor-gamma (PPAR-γ) transcriptional variants in pig and human
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DOI：
10.1111/j.1439-0388.2005.00508.x
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发表时间：
2005-04-01
影响因子：
2.6
通讯作者：
Neuenschwander, S
中科院分区：
文献类型：
--
作者：
Omi, T;Brenig, B;Neuenschwander, S
PPAR-γ是类固醇/甲状腺/维甲酸受体超家族的一员，主要在脂肪组织中表达。到目前为止，在猪中已经鉴定出两种主要的PPAR-Gamma1和PPAR-Gamma2亚型。猪PPAR-Gamma1a由两个前导外显子组成，分别命名为A1和A2，紧随其后的是含有开放阅读框架的六个外显子。在这里，我们报告了三个新的PPAR-Gamma1转录本的分离和鉴定。PPAR-Gamma1b来源于外显子A1，外显子A2被剪接。PPAR-Gamma1c和PPAR-Gamma1d来源于新的外显子A‘，含外显子A2(Gamma1c)或不含外显子A2(Gamma1d)。对包含PPAR-γ基因5‘-非翻译区序列的PAC克隆进行的PCR分析表明，新的A’外显子位于已知的外显子A1和A2之间。我们还从人类脂肪组织中分离了人类外显子A‘的同源物，以及两个新的PPAR-Gamma1c和-Gamma1d剪接变体。实时逆转录聚合酶链式反应对猪PPAR-γ表达的研究表明，来自外显子A1的转录本在内脏脂肪(浆膜下层)或皮下脂肪(背部脂肪、内层和外层)中的表达水平没有显著差异。相反，外显子A‘衍生的转录本在皮下脂肪的内层和外层的表达水平逐渐高于内脏脂肪。PPAR-Gamma2也有相同的表达模式。我们假设有三个启动子，它们根据脂肪组织的特定定位而不同地调节PPAR-Gamma1和PPAR-Gamma2基因的表达。
The peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is a member of the steroid/thyroid/retinoid receptor superfamily, and is primarily expressed in fat tissue. To date, two major PPAR-gamma isoforms have been identified in pig, PPAR-gamma1 and PPAR-gamma2. Porcine PPAR-gamma1a consists of two leader exons, designated A1 and A2, followed by six exons containing the open reading frame. Here, we report the isolation and characterization of three novel PPAR-gamma1 transcripts. PPAR-gamma1b is derived from exon A1, with exon A2 spliced out. PPAR-gamma1c and PPAR-gamma1d are derived from the new exon, A', containing exon A2 (gamma1c) or without exon A2 (gamma1d). Based on PCR analysis of PAC clones that included sequences from the 5'-untranslated region of the PPAR-gamma gene, the new A' exon is located between the known exons A1 and A2. We also isolated the human homologue to exon A', as well as the two new PPAR-gamma1c and -gamma1d splice variants, from human adipose tissue. Studies of the expression of porcine PPAR-gamma by real time reverse transcription-polymerase chain reaction analysis show that transcripts derived from exon A1 were not expressed at significantly different levels in visceral fat (lamina subserosa) or subcutaneous fat (back fat, inner and outer layer). In contrast, exon A'-derived transcripts were expressed at progressively higher levels in the inner and outer layers of subcutaneous fat than in visceral fat. The same expression pattern was also observed for PPAR-gamma2. We hypothesize that there are three promoters, which differentially regulate PPAR-gamma1 and PPAR-gamma2 gene expression, depending on the specific localization of the fat tissue.