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  • 1
    Publication Date: 2010-11-30
    Description: An ageing world population has fuelled interest in regenerative remedies that may stem declining organ function and maintain fitness. Unanswered is whether elimination of intrinsic instigators driving age-associated degeneration can reverse, as opposed to simply arrest, various afflictions of the aged. Such instigators include progressively damaged genomes. Telomerase-deficient mice have served as a model system to study the adverse cellular and organismal consequences of wide-spread endogenous DNA damage signalling activation in vivo. Telomere loss and uncapping provokes progressive tissue atrophy, stem cell depletion, organ system failure and impaired tissue injury responses. Here, we sought to determine whether entrenched multi-system degeneration in adult mice with severe telomere dysfunction can be halted or possibly reversed by reactivation of endogenous telomerase activity. To this end, we engineered a knock-in allele encoding a 4-hydroxytamoxifen (4-OHT)-inducible telomerase reverse transcriptase-oestrogen receptor (TERT-ER) under transcriptional control of the endogenous TERT promoter. Homozygous TERT-ER mice have short dysfunctional telomeres and sustain increased DNA damage signalling and classical degenerative phenotypes upon successive generational matings and advancing age. Telomerase reactivation in such late generation TERT-ER mice extends telomeres, reduces DNA damage signalling and associated cellular checkpoint responses, allows resumption of proliferation in quiescent cultures, and eliminates degenerative phenotypes across multiple organs including testes, spleens and intestines. Notably, somatic telomerase reactivation reversed neurodegeneration with restoration of proliferating Sox2(+) neural progenitors, Dcx(+) newborn neurons, and Olig2(+) oligodendrocyte populations. Consistent with the integral role of subventricular zone neural progenitors in generation and maintenance of olfactory bulb interneurons, this wave of telomerase-dependent neurogenesis resulted in alleviation of hyposmia and recovery of innate olfactory avoidance responses. Accumulating evidence implicating telomere damage as a driver of age-associated organ decline and disease risk and the marked reversal of systemic degenerative phenotypes in adult mice observed here support the development of regenerative strategies designed to restore telomere integrity.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3057569/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3057569/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jaskelioff, Mariela -- Muller, Florian L -- Paik, Ji-Hye -- Thomas, Emily -- Jiang, Shan -- Adams, Andrew C -- Sahin, Ergun -- Kost-Alimova, Maria -- Protopopov, Alexei -- Cadinanos, Juan -- Horner, James W -- Maratos-Flier, Eleftheria -- Depinho, Ronald A -- R01 CA084628/CA/NCI NIH HHS/ -- R01 CA084628-19/CA/NCI NIH HHS/ -- R01CA84628/CA/NCI NIH HHS/ -- U01 CA141508/CA/NCI NIH HHS/ -- U01 CA141508-01/CA/NCI NIH HHS/ -- U01CA141508/CA/NCI NIH HHS/ -- England -- Nature. 2011 Jan 6;469(7328):102-6. doi: 10.1038/nature09603. Epub 2010 Nov 28.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Belfer Institute for Applied Cancer Science and Departments of Medical Oncology, Medicine and Genetics, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21113150" target="_blank"〉PubMed〈/a〉
    Keywords: Aging/drug effects/*metabolism/*pathology ; Animals ; Avoidance Learning/drug effects ; Brain/anatomy & histology/cytology/drug effects/pathology ; Cell Differentiation/drug effects ; Cell Proliferation/drug effects ; Cells, Cultured ; DNA Damage/drug effects ; Enzyme Activation/drug effects ; Enzyme Reactivators/pharmacology ; Mice ; Mice, Inbred C57BL ; Models, Animal ; Myelin Sheath/metabolism ; Neural Stem Cells/cytology/drug effects/enzymology/pathology ; Organ Size/drug effects ; Phenotype ; Receptors, Estrogen/genetics/metabolism ; Recombinant Fusion Proteins/genetics/metabolism ; Regenerative Medicine ; Smell/drug effects/physiology ; Tamoxifen/analogs & derivatives/pharmacology ; Telomerase/*deficiency/genetics/*metabolism ; Telomere/drug effects/metabolism/pathology
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2011-02-11
    Description: Telomere dysfunction activates p53-mediated cellular growth arrest, senescence and apoptosis to drive progressive atrophy and functional decline in high-turnover tissues. The broader adverse impact of telomere dysfunction across many tissues including more quiescent systems prompted transcriptomic network analyses to identify common mechanisms operative in haematopoietic stem cells, heart and liver. These unbiased studies revealed profound repression of peroxisome proliferator-activated receptor gamma, coactivator 1 alpha and beta (PGC-1alpha and PGC-1beta, also known as Ppargc1a and Ppargc1b, respectively) and the downstream network in mice null for either telomerase reverse transcriptase (Tert) or telomerase RNA component (Terc) genes. Consistent with PGCs as master regulators of mitochondrial physiology and metabolism, telomere dysfunction is associated with impaired mitochondrial biogenesis and function, decreased gluconeogenesis, cardiomyopathy, and increased reactive oxygen species. In the setting of telomere dysfunction, enforced Tert or PGC-1alpha expression or germline deletion of p53 (also known as Trp53) substantially restores PGC network expression, mitochondrial respiration, cardiac function and gluconeogenesis. We demonstrate that telomere dysfunction activates p53 which in turn binds and represses PGC-1alpha and PGC-1beta promoters, thereby forging a direct link between telomere and mitochondrial biology. We propose that this telomere-p53-PGC axis contributes to organ and metabolic failure and to diminishing organismal fitness in the setting of telomere dysfunction.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3741661/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3741661/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sahin, Ergun -- Colla, Simona -- Liesa, Marc -- Moslehi, Javid -- Muller, Florian L -- Guo, Mira -- Cooper, Marcus -- Kotton, Darrell -- Fabian, Attila J -- Walkey, Carl -- Maser, Richard S -- Tonon, Giovanni -- Foerster, Friedrich -- Xiong, Robert -- Wang, Y Alan -- Shukla, Sachet A -- Jaskelioff, Mariela -- Martin, Eric S -- Heffernan, Timothy P -- Protopopov, Alexei -- Ivanova, Elena -- Mahoney, John E -- Kost-Alimova, Maria -- Perry, Samuel R -- Bronson, Roderick -- Liao, Ronglih -- Mulligan, Richard -- Shirihai, Orian S -- Chin, Lynda -- DePinho, Ronald A -- P30 DK046200/DK/NIDDK NIH HHS/ -- P30DK079638/DK/NIDDK NIH HHS/ -- R01 CA084628/CA/NCI NIH HHS/ -- R01 DK035914/DK/NIDDK NIH HHS/ -- R01 DK056690/DK/NIDDK NIH HHS/ -- R01 DK063356/DK/NIDDK NIH HHS/ -- R01 DK089185/DK/NIDDK NIH HHS/ -- U24 DK-59635/DK/NIDDK NIH HHS/ -- England -- Nature. 2011 Feb 17;470(7334):359-65. doi: 10.1038/nature09787. Epub 2011 Feb 9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Belfer Institute for Applied Cancer Science, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21307849" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/biosynthesis ; Aging/metabolism/pathology ; Animals ; Cardiomyopathies/chemically induced/metabolism/pathology/physiopathology ; Cell Proliferation ; DNA, Mitochondrial/analysis ; Doxorubicin/toxicity ; Gluconeogenesis ; Hematopoietic Stem Cells/metabolism/pathology ; Liver/cytology/metabolism ; Mice ; Mitochondria/*metabolism/*pathology ; Myocardium/cytology/metabolism ; RNA/genetics ; Reactive Oxygen Species/metabolism ; Telomerase/deficiency/genetics ; Telomere/enzymology/genetics/*metabolism/*pathology ; Transcription Factors/antagonists & inhibitors/metabolism ; Tumor Suppressor Protein p53/deficiency/genetics/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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