Krukenberg Kristin A, Jiang Ruomu, Steen Judith A, Mitchison Timothy J
Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA.
Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA.
Cell Rep. 2014 Sep 25;8(6):1808-1818. doi: 10.1016/j.celrep.2014.08.009. Epub 2014 Sep 4.
Poly(ADP-ribose) polymerases (PARPs) catalyze poly(ADP-ribose) addition onto proteins, an important posttranslational modification involved in transcription, DNA damage repair, and stem cell identity. Previous studies established the activation of PARP1 in response to DNA damage, but little is known about PARP1 regulation outside of DNA repair. We developed an assay for measuring PARP activity in cell lysates and found that the basal activity of PARP1 was highly variable across breast cancer cell lines, independent of DNA damage. Sucrose gradient fractionation demonstrated that PARP1 existed in at least three biochemically distinct states in both high- and low-activity lines. A discovered complex containing the NuA4 chromatin-remodeling complex and PARP1 was responsible for high basal PARP1 activity, and NuA4 subunits were required for this activity. These findings present a pathway for PARP1 activation and a direct link between PARP1 and chromatin remodeling outside of the DNA damage response.
聚（ADP-核糖）聚合酶（PARPs）催化蛋白质上聚（ADP-核糖）的添加，这是一种参与转录、DNA损伤修复和干细胞特性的重要翻译后修饰。先前的研究证实了PARP1在DNA损伤反应中的激活，但对于DNA修复之外的PARP1调控知之甚少。我们开发了一种用于测量细胞裂解物中PARP活性的检测方法，发现PARP1的基础活性在乳腺癌细胞系中高度可变，与DNA损伤无关。蔗糖密度梯度分级分离表明，PARP1在高活性和低活性细胞系中至少以三种生物化学上不同的状态存在。发现的一种包含NuA4染色质重塑复合物和PARP1的复合物导致了PARP1的高基础活性，并且该活性需要NuA4亚基。这些发现揭示了PARP1激活的一条途径以及PARP1与DNA损伤反应之外的染色质重塑之间的直接联系。
