Two farnesoid X receptor alpha isoforms in Japanese medaka (Oryzias latipes) are differentially activated in vitro.
Two farnesoid X receptor alpha isoforms in Japanese medaka (Oryzias latipes) are differentially activated in vitro.
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DOI：
10.1016/j.aquatox.2010.02.020
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发表时间：
2010-07-01
影响因子：
4.5
通讯作者：
Kullman, Seth W.
中科院分区：
文献类型：
--
作者：
Howarth, Deanna L.;Hagey, Lee R.;Law, Sheran H. W.;Ai, Ni;Krasowski, Matthew D.;Ekins, Sean;Moore, John T.;Kollitz, Erin M.;Hinton, David E.;Kullman, Seth W.
核受体法尼醇X受体α(FxRα，NR1H4)在小鼠、大鼠和人等多种物种中都被胆汁酸激活，在本研究中，我们在日本青竹(Oryzias Latipe)中鉴定了FXRα的两种亚型。这两种异构体都与哺乳动物的FXRα有很高的氨基酸序列同源性(约70%在配体结合区)。FXRα1和FXRα2在AF1结构域中不同，这是由于在第四内含子-外显子边界的选择性剪接。这一过程导致FXRα1的N末端比FXRα2更长。在瞬时反式激活试验中，鹅去氧胆酸、胆酸、脱氧胆酸和石胆酸以及合成激动剂GW4064激活了α-FXR LBD融合结构。滴定实验表明，加入α-1α可增强Gal4DBD-FXR PGC-1 LBD融合构建体的活性。令人惊讶的是，当在瞬时转染实验中比较两种FXRα亚型的全长版本时，FXRα2可被C24胆汁酸和GW4064激活，而FXRα1不被所测试的任何化合物显著激活。由于全长构建物之间唯一显著的差异是AF1域的序列，这些实验突出了FXRαAF1域中的一个关键功能区。此外，哺乳动物双杂交研究表明，FxRα2，而不是FxRα1，能够与pGC-1α和sRC-1相互作用，并支持瞬时转染报告基因激活实验的结果。这些数据表明，哺乳动物和硬骨鱼FXR(FXRα2亚型)都被初级和次级胆汁酸激活。
The nuclear receptor farnesoid X receptor alpha (FXRα, NR1H4) is activated by bile acids in multiple species including mouse, rat, and human and in this study we have identified two isoforms of Fxrα in Japanese medaka (Oryzias latipes), a small freshwater teleost. Both isoforms share a high amino acid sequence identity to mammalian FXRα (~70% in the ligand-binding domain). Fxrα1 and Fxrα2 differ within the AF1 domain due to alternative splicing at the fourth intron-exon boundary. This process results in Fxrα1 having an extended N-terminus compared to Fxrα2. A Gal4DBD-FxrαLBD fusion construct was activated by chenodeoxycholic, cholic, deoxycholic and lithocholic acids, and the synthetic agonist GW4064 in transient transactivation assays. Activation of the Gal4DBD-FxrαLBD fusion construct was enhanced by addition of PGC-1α, as demonstrated through titration assays. Surprisingly, when the full-length versions of the two Fxrα isoforms were compared in transient transfection assays, Fxrα2 was activated by C24 bile acids and GW4064, while Fxrα1 was not significantly activated by any of the compounds tested. Since the only significant difference between the full-length constructs was sequence in the AF1 domain, these experiments highlight a key functional region in the Fxrα AF1 domain. Furthermore, mammalian two-hybrid studies demonstrated the ability of Fxrα2, but not Fxrα1, to interact with PGC-1α and SRC-1, and supported our results from the transient transfection reporter gene activation assays. These data demonstrate that both mammalian and teleost FXR (Fxrα2 isoform) are activated by primary and secondary bile acids.
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影响因子：
7.4
作者：
Chatman, K;Hollenbeck, T;Siuzdak, G
通讯作者：
Siuzdak, G
影响因子：
4.5
作者：
Bertrand S;Thisse B;Tavares R;Sachs L;Chaumot A;Bardet PL;Escrivà H;Duffraisse M;Marchand O;Safi R;Thisse C;Laudet V
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Howarth DL;Law SH;Law JM;Mondon JA;Kullman SW;Hinton DE
通讯作者：
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29.4
作者：
Denson, LA;Sturm, E;Karpen, SJ
通讯作者：
Karpen, SJ
影响因子：
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作者：
Kassam, A;Miao, B;Mukherjee, R
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Mukherjee, R