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KMID : 0578320150380090814
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Molecules and Cells
2015 Volume.38 No. 9 p.814 ~ p.820
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Increased Stability of Nucleolar PinX1 in the Presence of TERT
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Keo Ponnarath
Choi Joong-Sub
Bae Jae-Man
Shim Yhong-Hee
Oh Bong-Kyeong
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Abstract
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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 PinX1205?328, a nucleolar fragment, was much more stable than the N-terminal of PinX11?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 PinX11?328 and PinX1205?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, PinX11?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.
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KEYWORD
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nucleolus, PinX1, protein stability, TERT
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