PIAS1 interacts with FLASH and enhances its co-activation of c-Myb.
PIAS1 interacts with FLASH and enhances its co-activation of c-Myb.
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DOI：
10.1186/1476-4598-10-21
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发表时间：
2011-02-21
期刊：
影响因子：
37.3
通讯作者：
Gabrielsen OS
中科院分区：
文献类型：
--
作者：
Alm-Kristiansen AH;Lorenzo PI;Molværsmyr AK;Matre V;Ledsaak M;Sæther T;Gabrielsen OS
FLASH是一种巨大的核蛋白，参与多种细胞功能，如凋亡信号传导、NF-κB激活、S期调节、组蛋白前mRNA加工和转录共调节。最近，我们确定FLASH作为转录因子c-Myb的共激活因子，并发现FLASH与活跃的转录灶紧密相关。作为一个巨大的多功能蛋白，FLASH被认为有许多相互作用的伙伴，其中一些可能揭示其作为转录调控因子的功能。为了找到更多的FLASH相关蛋白，我们用FLASH作为诱饵进行了酵母双杂交（Y2 H）筛选，并鉴定了SUMO E3连接酶PIAS 1作为相互作用伴侣。这种关联似乎涉及FLASH中两个不同的相互作用表面。我们通过Y2 H配对、GST下拉、co-IP和ChIP验证了相互作用。FLASH和PIAS 1被发现共定位于核斑点。功能分析表明，PIAS 1增强内在的转录活性的FLASH在一个环指依赖性的方式。PIAS 1还能增强c-Myb的比活性，并与FLASH协同作用，进一步激活c-Myb。这三种蛋白质，FLASH，PIAS 1和c-Myb，都与活性RNA聚合酶II病灶共定位，类似于转录工厂。我们的结论是PIAS 1是两种癌症相关核因子c-Myb和FLASH的共同伙伴。我们的研究结果表明，FLASH和PIAS 1在增强活性核灶中的c-Myb活性方面存在功能性合作。
FLASH is a huge nuclear protein involved in various cellular functions such as apoptosis signalling, NF-κB activation, S-phase regulation, processing of histone pre-mRNAs, and co-regulation of transcription. Recently, we identified FLASH as a co-activator of the transcription factor c-Myb and found FLASH to be tightly associated with active transcription foci. As a huge multifunctional protein, FLASH is expected to have many interaction partners, some which may shed light on its function as a transcriptional regulator. To find additional FLASH-associated proteins, we performed a yeast two-hybrid (Y2H) screening with FLASH as bait and identified the SUMO E3 ligase PIAS1 as an interaction partner. The association appears to involve two distinct interaction surfaces in FLASH. We verified the interaction by Y2H-mating, GST pulldowns, co-IP and ChIP. FLASH and PIAS1 were found to co-localize in nuclear speckles. Functional assays revealed that PIAS1 enhances the intrinsic transcriptional activity of FLASH in a RING finger-dependent manner. Furthermore, PIAS1 also augments the specific activity of c-Myb, and cooperates with FLASH to further co-activate c-Myb. The three proteins, FLASH, PIAS1, and c-Myb, are all co-localized with active RNA polymerase II foci, resembling transcription factories. We conclude that PIAS1 is a common partner for two cancer-related nuclear factors, c-Myb and FLASH. Our results point to a functional cooperation between FLASH and PIAS1 in the enhancement of c-Myb activity in active nuclear foci.
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