title: C-terminal amino acids 290-328 of LPTS/PinX1 confer telomerase inhibition.
abstract: 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.
authors.affiliation: State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, PR China.
authors.forename: Guoyuan
authors.initials: G
authors.lastname: Chen
authors.forename: Liang
authors.initials: L
authors.lastname: Da
authors.forename: Ying
authors.initials: Y
authors.lastname: Xu
authors.forename: Mafei
authors.initials: M
authors.lastname: Xu
authors.forename: Li
authors.initials: L
authors.lastname: Song
authors.forename: Tsaiping
authors.initials: T
authors.lastname: Li
authors.forename: Mujun
authors.initials: M
authors.lastname: Zhao
mesh_terms: D000595:Amino Acid Sequence; D017209:Apoptosis; D018797:Cell Cycle Proteins; D002460:Cell Line; D049109:Cell Proliferation; D006801:Humans; D017434:Protein Structure, Tertiary; D019098:Telomerase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D016615:Telomere / Q000235:genetics / Q000378:metabolism*; D035321:Telomeric Repeat Binding Protein 1 / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; C440808:PINX1 protein, human; D035321:Telomeric Repeat Binding Protein 1; D025521:Tumor Suppressor Proteins; D019098:Telomerase