Most eukaryotes have telomerase structure to protect the ends of chromosomes. Human telomerase is constituted with subunits such as human telomerase reverse transcriptase (hTERT) and human telomerase RNA (hTR). Especially, hTERT is an important cataly...
Most eukaryotes have telomerase structure to protect the ends of chromosomes. Human telomerase is constituted with subunits such as human telomerase reverse transcriptase (hTERT) and human telomerase RNA (hTR). Especially, hTERT is an important catalytic subunit, regulating telomerase activity. It is usually expressed in continuously proliferating cells such as germ cells. Heat shock protein 90 (Hsp90) is a chaperone which is required for hTERT activation and assembly with hTR. hTERT is ubiquitinated and degraded when the level of Hsp90 gets dirupted. A previous report showed that HIDE acts as a deubiquitinating enzyme, and interacts with Hsp90. In this study, we identified that Hsp90 is polyubiquitinated. In HIDE expressed cells, the level of ubiquitin-conjugated hTERT is decreased in contrast with catalytic mutant HIDE (C506S) expressed cells. Furthermore, the level of hTERT degradation with Hsp90 antagonist geldanamycin (GA) treatment is inhibited with HIDE overexpression. The HIDE functional activity for hTERT rescue was measured by TRAP assay. Overexpression of HIDE in hTERT transfected cells promotes the telomerase activity, and subsequently increases telomere length. This study indicates that HIDE may protect hTERT from proteolysis.