title: Multiple Mechanisms Contribute to the Cell Growth Defects Imparted by Human Telomerase Insertion in Fingers Domain Mutations Associated with Premature Aging Diseases.
abstract: Normal human stem cells rely on low levels of active telomerase to sustain their high replicative requirements. Deficiency in telomere maintenance mechanisms leads to the development of premature aging diseases, such as dyskeratosis congenita and aplastic anemia. Mutations in the unique "insertion in fingers domain" (IFD) in the human telomerase reverse transcriptase catalytic subunit (hTERT) have previously been identified and shown to be associated with dyskeratosis congenita and aplastic anemia. However, little is known about the molecular mechanisms impacted by these IFD mutations. We performed comparative functional analyses of disease-associated IFD variants at the molecular and cellular levels. We report that hTERT-P721R- and hTERT-R811C-expressing cells exhibited growth defects likely due to impaired TPP1-mediated recruitment of these variant enzymes to telomeres. We showed that activity and processivity of hTERT-T726M failed to be stimulated by TPP1-POT1 overexpression and that dGTP usage by this variant was less efficient compared with the wild-type enzyme. hTERT-P785L-expressing cells did not show growth defects, and this variant likely confers cell survival through increased DNA synthesis and robust activity stimulation by TPP1-POT1. Altogether, our data suggest that multiple mechanisms contribute to cell growth defects conferred by the IFD variants.
authors.affiliation: From the Bloomfield Centre for Research in Aging, Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal H3T 1E2, Canada, Department of Medicine, McGill University, Montréal H4A 3J1, Canada, and.
authors.forename: Tsz Wai
authors.initials: TW
authors.lastname: Chu
authors.affiliation: From the Bloomfield Centre for Research in Aging, Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal H3T 1E2, Canada, Department of Anatomy and Cell Biology, McGill University, Montréal H3A 0C7, Canada.
authors.forename: Deanna Elise
authors.initials: DE
authors.lastname: MacNeil
authors.affiliation: From the Bloomfield Centre for Research in Aging, Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal H3T 1E2, Canada, Department of Medicine, McGill University, Montréal H4A 3J1, Canada, and Department of Anatomy and Cell Biology, McGill University, Montréal H3A 0C7, Canada chantal.autexier@mcgill.ca.
authors.forename: Chantal
authors.initials: C
authors.lastname: Autexier
mesh_terms: D019588:Aging, Premature / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D019943:Amino Acid Substitution; D000626:Aminopeptidases / Q000235:genetics / Q000378:metabolism; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D020125:Mutation, Missense; D017434:Protein Structure, Tertiary; D057057:Serine Proteases / Q000235:genetics / Q000378:metabolism; D000089804:Shelterin Complex; D019098:Telomerase / Q000235:genetics / Q000378:metabolism*; D034501:Telomere-Binding Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: C495876:ACD protein, human; C440849:POT1 protein, human; D000089804:Shelterin Complex; D034501:Telomere-Binding Proteins; C509186:TERT protein, human; D019098:Telomerase; D057057:Serine Proteases; D000626:Aminopeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases
keywords: DNA damage response; RNA-protein interaction; cell death; telomerase; telomerase reverse transcriptase (TERT); telomere