title: Short telomeres, even in the presence of telomerase, limit tissue renewal capacity.
abstract: Autosomal-dominant dyskeratosis congenita is associated with heterozygous mutations in telomerase. To examine the dosage effect of telomerase, we generated a line of mTR+/- mice on the CAST/EiJ background, which has short telomeres. Interbreeding of heterozygotes resulted in progressive telomere shortening, indicating that limiting telomerase compromises telomere maintenance. In later-generation heterozygotes, we observed a decrease in tissue renewal capacity in the bone marrow, intestines, and testes that resembled defects seen in dyskeratosis congenita patients. The progressive worsening of disease with decreasing telomere length suggests that short telomeres, not telomerase level, cause stem cell failure. Further, wild-type mice derived from the late-generation heterozygous parents, termed wt*, also had short telomeres and displayed a germ cell defect, indicating that telomere length determines these phenotypes. We propose that short telomeres in mice that have normal telomerase levels can cause an occult form of genetic disease.
authors.affiliation: Department of Molecular Biology and Genetics, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: Ling-Yang
authors.initials: LY
authors.lastname: Hao
authors.forename: Mary
authors.initials: M
authors.lastname: Armanios
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Strong
authors.forename: Baktiar
authors.initials: B
authors.lastname: Karim
authors.forename: David M
authors.initials: DM
authors.lastname: Feldser
authors.forename: David
authors.initials: D
authors.lastname: Huso
authors.forename: Carol W
authors.initials: CW
authors.lastname: Greider
mesh_terms: D000818:Animals; D020132:Anticipation, Genetic / Q000235:genetics; D001772:Blood Cell Count; D016026:Bone Marrow Transplantation / Q000401:mortality; D003433:Crosses, Genetic; D019871:Dyskeratosis Congenita / Q000235:genetics; D005472:Fluorouracil / Q000494:pharmacology; D005838:Genotype; D006239:Haplotypes / Q000235:genetics; D006413:Hematopoietic System / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006579:Heterozygote; D007413:Intestinal Mucosa / Q000378:metabolism / Q000473:pathology; D007422:Intestines / Q000473:pathology*; D008136:Longevity / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D010641:Phenotype; D012671:Seminiferous Tubules / Q000378:metabolism / Q000473:pathology; D013234:Stem Cells / Q000378:metabolism / Q000473:pathology; D015996:Survival Rate; D019098:Telomerase / Q000235:genetics* / Q000378:metabolism; D016615:Telomere / Q000235:genetics* / Q000378:metabolism; D013737:Testis / Q000378:metabolism / Q000473:pathology*; D013997:Time Factors
chemical_list: D019098:Telomerase; D005472:Fluorouracil