Prieur Alexandre, Nacerddine Karim, van Lohuizen Maarten, Peeper Daniel S
Department of Molecular Genetics, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
PLoS One. 2009;4(5):e5542. doi: 10.1371/journal.pone.0005542. Epub 2009 May 14.
DRIL1 is an ARID family transcription factor that can immortalize primary mouse fibroblasts, bypass RAS(V12)-induced cellular senescence and collaborate with RAS(V12) or MYC in mediating oncogenic transformation. It also activates immunoglobulin heavy chain transcription and engages in heterodimer formation with E2F to stimulate E2F-dependent transcription. Little, however, is known about the regulation of DRIL1 activity. Recently, DRIL1 was found to interact with the SUMO-conjugating enzyme Ubc9, but the functional relevance of this association has not been assessed. Here, we show that DRIL1 is sumoylated both in vitro and in vivo at lysine 398. Moreover, we provide evidence that PIASy functions as a specific SUMO E3-ligase for DRIL1 and promotes its sumoylation both in vitro and in vivo. Furthermore, consistent with the subnuclear localization of PIASy in the Matrix-Associated Region (MAR), SUMO-modified DRIL1 species are found exclusively in the MAR fraction. This post-translational modification interferes neither with the subcellular localization nor the DNA-binding activity of the protein. In contrast, DRIL1 sumoylation impairs its interaction with E2F1 in vitro and modifies its transcriptional activity in vivo, driving transcription of subset of genes regulating leukocyte fate. Taken together, these results identify sumoylation as a novel post-translational modification of DRIL1 that represents an important mechanism for targeting and modulating DRIL1 transcriptional activity.
DRIL1是一种ARID家族转录因子，它能够使原代小鼠成纤维细胞永生化，绕过RAS（V12）诱导的细胞衰老，并在介导致癌转化过程中与RAS（V12）或MYC协同作用。它还能激活免疫球蛋白重链转录，并与E2F形成异二聚体以刺激E2F依赖性转录。然而，关于DRIL1活性的调节知之甚少。最近，发现DRIL1与SUMO缀合酶Ubc9相互作用，但尚未评估这种关联的功能相关性。在这里，我们表明DRIL1在体外和体内的赖氨酸398处均被SUMO化。此外，我们提供的证据表明PIASy作为DRIL1的特异性SUMO E3连接酶，在体外和体内均促进其SUMO化。此外，与PIASy在基质相关区域（MAR）中的核内亚定位一致，SUMO修饰的DRIL1仅在MAR部分中发现。这种翻译后修饰既不干扰蛋白质的亚细胞定位，也不干扰其DNA结合活性。相反，DRIL1的SUMO化在体外损害其与E2F1的相互作用，并在体内改变其转录活性，驱动调节白细胞命运的基因子集的转录。综上所述，这些结果确定SUMO化是DRIL1一种新的翻译后修饰，代表了靶向和调节DRIL1转录活性的重要机制。
