State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, PR China.
Biochem Biophys Res Commun. 2010 Aug 6;398(4):683-9. doi: 10.1016/j.bbrc.2010.06.136. Epub 2010 Jul 8.
LPTS/PinX1, a telomerase inhibitor composed of 328 amino acids, binds to the telomere associated protein Pin2/TRF1 and to the telomerase catalytic subunit hTERT. However, the mechanism by which LPTS/PinX1 regulates telomerase activity remains unclear. Here we show, for the first time, that LPTS/PinX1 uses different domains to interact with Pin2/TRF1 and hTERT. The LPTS/PinX1(254-289) fragment specifically binds to Pin2/TRF1, and LPTS/PinX1(290-328) can associate with hTERT. Compared with the full-length LPTS/PinX1 protein, LPTS/PinX1(290-328) shows stronger in vitro telomerase inhibitory activity. Moreover, the LPTS/PinX1 protein was recruited to telomeres for binding to Pin2/TRF1. Overexpression of LPTS/PinX1(290-328), which contains a nucleolus localization signal, in cells resulted in telomere shortening and progressive cell death. Conversely, telomere elongation was induced by expression of the dominant-negative LPTS/PinX1(1-289). Our results suggest that the C-terminal fragment of LPTS/PinX1 (LPTS/PinX1(290-328)) contains a telomerase inhibitory domain that is required for the inhibition of telomere elongation and the induction of cell crisis. Our studies also provide evidence that LPTS/PinX1 interaction with Pin2/TRF1 may play a role in the stabilization of telomeres.
LPTS/PinX1，一种由 328 个氨基酸组成的端粒酶抑制剂，与端粒相关蛋白 Pin2/TRF1 和端粒酶催化亚基 hTERT 结合。然而，LPTS/PinX1 调节端粒酶活性的机制尚不清楚。在这里，我们首次表明，LPTS/PinX1 使用不同的结构域与 Pin2/TRF1 和 hTERT 相互作用。LPTS/PinX1(254-289)片段特异性地与 Pin2/TRF1 结合，而 LPTS/PinX1(290-328)可以与 hTERT 结合。与全长 LPTS/PinX1 蛋白相比，LPTS/PinX1(290-328)在体外显示出更强的端粒酶抑制活性。此外，LPTS/PinX1 蛋白被募集到端粒上与 Pin2/TRF1 结合。在细胞中过表达含有核仁定位信号的 LPTS/PinX1(290-328)，导致端粒缩短和细胞死亡的进行性增加。相反，表达显性负性 LPTS/PinX1(1-289)则诱导端粒延长。我们的研究结果表明，LPTS/PinX1 的 C 端片段（LPTS/PinX1(290-328)）包含一个端粒酶抑制结构域，该结构域对于抑制端粒延长和诱导细胞危机是必需的。我们的研究还提供了证据，表明 LPTS/PinX1 与 Pin2/TRF1 的相互作用可能在端粒的稳定中发挥作用。
