Dantzer Françoise, Giraud-Panis Marie-Josèphe, Jaco Isabel, Amé Jean-Christophe, Schultz Inès, Blasco Maria, Koering Catherine-Elaine, Gilson Eric, Ménissier-de Murcia Josiane, de Murcia Gilbert, Schreiber Valérie
UPR 9003 du Centre National de la Recherche Scientifique, Université Louis Pasteur, Ecole Supérieure de Biotechnologie de Strasbourg, 67412 Illkirch Cedex, France.
Mol Cell Biol. 2004 Feb;24(4):1595-607. doi: 10.1128/MCB.24.4.1595-1607.2004.
The DNA damage-dependent poly(ADP-ribose) polymerase-2 (PARP-2) is, together with PARP-1, an active player of the base excision repair process, thus defining its key role in genome surveillance and protection. Telomeres are specialized DNA-protein structures that protect chromosome ends from being recognized and processed as DNA strand breaks. In mammals, telomere protection depends on the T(2)AG(3) repeat binding protein TRF2, which has been shown to remodel telomeres into large duplex loops (t-loops). In this work we show that PARP-2 physically binds to TRF2 with high affinity. The association of both proteins requires the N-terminal domain of PARP-2 and the myb domain of TRF2. Both partners colocalize at promyelocytic leukemia bodies in immortalized telomerase-negative cells. In addition, our data show that PARP activity regulates the DNA binding activity of TRF2 via both a covalent heteromodification of the dimerization domain of TRF2 and a noncovalent binding of poly(ADP-ribose) to the myb domain of TRF2. PARP-2(-/-) primary cells show normal telomere length as well as normal telomerase activity compared to wild-type cells but display a spontaneously increased frequency of chromosome and chromatid breaks and of ends lacking detectable T(2)AG(3) repeats. Altogether, these results suggest a functional role of PARP-2 activity in the maintenance of telomere integrity.
DNA损伤依赖性聚（ADP - 核糖）聚合酶2（PARP - 2）与PARP - 1一起，是碱基切除修复过程的积极参与者，因此在基因组监测和保护中发挥关键作用。端粒是特殊的DNA - 蛋白质结构，可保护染色体末端不被识别并作为DNA链断裂进行处理。在哺乳动物中，端粒保护依赖于T(2)AG(3)重复结合蛋白TRF2，该蛋白已被证明可将端粒重塑为大的双链环（t - 环）。在这项研究中，我们表明PARP - 2以高亲和力与TRF2发生物理结合。两种蛋白质的结合需要PARP - 2的N末端结构域和TRF2的myb结构域。在永生化的端粒酶阴性细胞中，这两种蛋白在早幼粒细胞白血病小体中共定位。此外，我们的数据表明，PARP活性通过TRF2二聚化结构域的共价异源修饰以及聚（ADP - 核糖）与TRF2的myb结构域的非共价结合来调节TRF2的DNA结合活性。与野生型细胞相比，PARP - 2(-/-)原代细胞显示出正常的端粒长度以及正常的端粒酶活性，但染色体和染色单体断裂以及缺乏可检测到的T(2)AG(3)重复序列的末端的自发频率增加。总之，这些结果表明PARP - 2活性在维持端粒完整性方面具有功能作用。
