Increased Stability of Nucleolar PinX1 in the Presence of TERT

  • Keo, Ponnarath (Department of Bioscience and Biotechnology, Konkuk University) ;
  • Choi, Joong Sub (Department of Obstetrics and Gynecology, Hanyang University College of Medicine) ;
  • Bae, Jaeman (Department of Obstetrics and Gynecology, Hanyang University College of Medicine) ;
  • Shim, Yhong-Hee (Department of Bioscience and Biotechnology, Konkuk University) ;
  • Oh, Bong-Kyeong (Institute of Medical Science, Hanyang University College of Medicine)
  • Received : 2015.05.22
  • Accepted : 2015.05.29
  • Published : 2015.09.30


PinX1, a nucleolar protein of 328 amino acids, inhibits telomerase activity, which leads to the shortening of telomeres. The C-terminal region of PinX1 is responsible for its nucleolar localization and binding with TERT, a catalytic component of telomerase. A fraction of TERT localizes to the nucleolus, but the role of TERT in the nucleolus is largely unknown. Here, we report a functional connection between PinX1 and TERT regarding PinX1 stability. The C-terminal of $PinX1^{205-328}$, a nucleolar fragment, was much more stable than the N-terminal of $PinX1^{1-204}$, a nuclear fragment. Interestingly, PinX1 was less stable in TERT-depleted cells and more stable in TERT-myc expressing cells. Stability assays for PinX1 truncation forms showed that both $PinX1^{1-328}$ and $PinX1^{205-328}$, nucleolar forms, were more rapidly degraded in TERT-depleted cells, while they were more stably maintained in TERT-overexpressing cells, compared to each of the controls. However, $PinX1^{1-204}$ was degraded regardless of the TERT status. These results reveal that the stability of PinX1 is maintained in nucleolus in the presence of TERT and suggest a role of TERT in the regulation of PinX1 steady-state levels.


Supported by : National Research Foundation of Korea (NRF)


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