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Sanchez SE, Gu J, Golla A, Martin A, Shomali W, Hockemeyer D, Savage SA, Artandi SE. Digital telomere measurement by long-read sequencing distinguishes healthy aging from disease. bioRxiv 2023:2023.11.29.569263. [PMID: 38077053 PMCID: PMC10705489 DOI: 10.1101/2023.11.29.569263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
Telomere length is an important biomarker of organismal aging and cellular replicative potential, but existing measurement methods are limited in resolution and accuracy. Here, we deploy digital telomere measurement by nanopore sequencing to understand how distributions of human telomere length change with age and disease. We measure telomere attrition and de novo elongation with unprecedented resolution in genetically defined populations of human cells, in blood cells from healthy donors and in blood cells from patients with genetic defects in telomere maintenance. We find that human aging is accompanied by a progressive loss of long telomeres and an accumulation of shorter telomeres. In patients with defects in telomere maintenance, the accumulation of short telomeres is more pronounced and correlates with phenotypic severity. We apply machine learning to train a binary classification model that distinguishes healthy individuals from those with telomere biology disorders. This sequencing and bioinformatic pipeline will advance our understanding of telomere maintenance mechanisms and the use of telomere length as a clinical biomarker of aging and disease.
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Affiliation(s)
- Santiago E. Sanchez
- Stanford Cancer Institute, Stanford University School of Medicine; Stanford, CA, USA
- Cancer Biology Program, Stanford University School of Medicine; Stanford, CA, USA
- Medical Scientist Training Program, Stanford University; Stanford CA, USA
| | - Jessica Gu
- Stanford Cancer Institute, Stanford University School of Medicine; Stanford, CA, USA
- Department of Medicine, Stanford University School of Medicine; Stanford, CA, USA
- Department of Biochemistry, Stanford University School of Medicine; Stanford, CA, USA
| | - Anudeep Golla
- Stanford Cancer Institute, Stanford University School of Medicine; Stanford, CA, USA
| | - Annika Martin
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA
| | - William Shomali
- Department of Medicine, Stanford University School of Medicine; Stanford, CA, USA
| | - Dirk Hockemeyer
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA
- Chan Zuckerberg Biohub, San Francisco, CA
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA
| | - Sharon A. Savage
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland, USA
| | - Steven E. Artandi
- Stanford Cancer Institute, Stanford University School of Medicine; Stanford, CA, USA
- Department of Medicine, Stanford University School of Medicine; Stanford, CA, USA
- Department of Biochemistry, Stanford University School of Medicine; Stanford, CA, USA
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2
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Eguchi A, Gonzalez AFGS, Torres-Bigio SI, Koleckar K, Birnbaum F, Zhang JZ, Wang VY, Wu JC, Artandi SE, Blau HM. TRF2 rescues telomere attrition and prolongs cell survival in Duchenne muscular dystrophy cardiomyocytes derived from human iPSCs. Proc Natl Acad Sci U S A 2023; 120:e2209967120. [PMID: 36719921 PMCID: PMC9963063 DOI: 10.1073/pnas.2209967120] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 12/29/2022] [Indexed: 02/01/2023] Open
Abstract
Duchenne muscular dystrophy (DMD) is a severe muscle wasting disease caused by the lack of dystrophin. Heart failure, driven by cardiomyocyte death, fibrosis, and the development of dilated cardiomyopathy, is the leading cause of death in DMD patients. Current treatments decrease the mechanical load on the heart but do not address the root cause of dilated cardiomyopathy: cardiomyocyte death. Previously, we showed that telomere shortening is a hallmark of DMD cardiomyocytes. Here, we test whether prevention of telomere attrition is possible in cardiomyocytes differentiated from patient-derived induced pluripotent stem cells (iPSC-CMs) and if preventing telomere shortening impacts cardiomyocyte function. We observe reduced cell size, nuclear size, and sarcomere density in DMD iPSC-CMs compared with healthy isogenic controls. We find that expression of just one telomere-binding protein, telomeric repeat-binding factor 2 (TRF2), a core component of the shelterin complex, prevents telomere attrition and rescues deficiencies in cell size as well as sarcomere density. We employ a bioengineered platform to micropattern cardiomyocytes for calcium imaging and perform Southern blots of telomere restriction fragments, the gold standard for telomere length assessments. Importantly, preservation of telomere lengths in DMD cardiomyocytes improves their viability. These data provide evidence that preventing telomere attrition ameliorates deficits in cell morphology, activation of the DNA damage response, and premature cell death, suggesting that TRF2 is a key player in DMD-associated cardiac failure.
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Affiliation(s)
- Asuka Eguchi
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology, Stanford School of Medicine, Stanford, CA94305
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA94305
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
| | - Adriana Fernanda G. S. Gonzalez
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology, Stanford School of Medicine, Stanford, CA94305
| | - Sofía I. Torres-Bigio
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology, Stanford School of Medicine, Stanford, CA94305
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
| | - Kassie Koleckar
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology, Stanford School of Medicine, Stanford, CA94305
| | - Foster Birnbaum
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology, Stanford School of Medicine, Stanford, CA94305
| | - Joe Z. Zhang
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA94305
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
- Division of Cardiology, Department of Medicine, Stanford University School of Medicine, Stanford, CA94305
| | - Vicky Y. Wang
- Stanford Department of Radiology, Stanford University School of Medicine, Stanford, CA94305
| | - Joseph C. Wu
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA94305
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
- Division of Cardiology, Department of Medicine, Stanford University School of Medicine, Stanford, CA94305
| | - Steven E. Artandi
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA94305
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA94035
| | - Helen M. Blau
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology, Stanford School of Medicine, Stanford, CA94305
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA94305
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
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3
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Neuhöfer P, Kim SJ, Charville GW, Artandi SE. Abstract A076: Somatic deletion of Tert inhibits clonal expansion of pancreatic acinar cell stem cells. Cancer Res 2022. [DOI: 10.1158/1538-7445.panca22-a076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Abstract
Tert-expressing cells have been identified within the acinar cell compartment of the pancreas in mice. Lineage tracing experiments indicate that these cells can maintain the exocrine compartment during homeostasis and repopulate the tissue during regeneration. Additional expression of mutant Kras in Tert-expressing acinar cells accelerates acinar clone formation and causes transdifferentiation to pre-invasive pancreatic intraepithelial neoplasms after injury. Here, using a genetic approach, we generated mice where tamoxifen injection leads to simultaneous deletion of TERT in Tert-expressing cells and activation of a reporter allele. We performed lineage tracing experiments to investigate the role of TERT in those cells. We studied the effect of acute deletion of TERT during homeostasis, regeneration and tumorigenesis. Acute deletion of TERT significantly inhibited the clone forming capability of Tert-expressing cells during homeostasis in pancreas after one year. To explore the requirement for TERT in an injury setting, we treated mice with cerulein to induce pancreatitis. Somatic inactivagion of TERT in Tert-expressing acinar stem cells impaired clone formation in mice treated with cerulein. To understand if loss of TERT affected transformation, we deleted TERT in acinar stem cells while specifically expressing activated Kras in these cells. Acute deletion of TERT in the presence of a mutant KrasG12D allele decreased the formation of metaplastic areas and PanIN lesions post-injury. These data suggest that a functional allele of Tert is necessary for the clone forming ability of Tert-expressing cells during homeostasis and regeneration as well as acinar to ductal metaplasia and PanIN formation in tumorigenesis.
Citation Format: Patrick Neuhöfer, Stewart J. Kim, Gregory W. Charville, Steven E. Artandi. Somatic deletion of Tert inhibits clonal expansion of pancreatic acinar cell stem cells [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr A076.
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4
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Jones RC, Karkanias J, Krasnow MA, Pisco AO, Quake SR, Salzman J, Yosef N, Bulthaup B, Brown P, Harper W, Hemenez M, Ponnusamy R, Salehi A, Sanagavarapu BA, Spallino E, Aaron KA, Concepcion W, Gardner JM, Kelly B, Neidlinger N, Wang Z, Crasta S, Kolluru S, Morri M, Pisco AO, Tan SY, Travaglini KJ, Xu C, Alcántara-Hernández M, Almanzar N, Antony J, Beyersdorf B, Burhan D, Calcuttawala K, Carter MM, Chan CKF, Chang CA, Chang S, Colville A, Crasta S, Culver RN, Cvijović I, D'Amato G, Ezran C, Galdos FX, Gillich A, Goodyer WR, Hang Y, Hayashi A, Houshdaran S, Huang X, Irwin JC, Jang S, Juanico JV, Kershner AM, Kim S, Kiss B, Kolluru S, Kong W, Kumar ME, Kuo AH, Leylek R, Li B, Loeb GB, Lu WJ, Mantri S, Markovic M, McAlpine PL, de Morree A, Morri M, Mrouj K, Mukherjee S, Muser T, Neuhöfer P, Nguyen TD, Perez K, Phansalkar R, Pisco AO, Puluca N, Qi Z, Rao P, Raquer-McKay H, Schaum N, Scott B, Seddighzadeh B, Segal J, Sen S, Sikandar S, Spencer SP, Steffes LC, Subramaniam VR, Swarup A, Swift M, Travaglini KJ, Van Treuren W, Trimm E, Veizades S, Vijayakumar S, Vo KC, Vorperian SK, Wang W, Weinstein HNW, Winkler J, Wu TTH, Xie J, Yung AR, Zhang Y, Detweiler AM, Mekonen H, Neff NF, Sit RV, Tan M, Yan J, Bean GR, Charu V, Forgó E, Martin BA, Ozawa MG, Silva O, Tan SY, Toland A, Vemuri VNP, Afik S, Awayan K, Botvinnik OB, Byrne A, Chen M, Dehghannasiri R, Detweiler AM, Gayoso A, Granados AA, Li Q, Mahmoudabadi G, McGeever A, de Morree A, Olivieri JE, Park M, Pisco AO, Ravikumar N, Salzman J, Stanley G, Swift M, Tan M, Tan W, Tarashansky AJ, Vanheusden R, Vorperian SK, Wang P, Wang S, Xing G, Xu C, Yosef N, Alcántara-Hernández M, Antony J, Chan CKF, Chang CA, Colville A, Crasta S, Culver R, Dethlefsen L, Ezran C, Gillich A, Hang Y, Ho PY, Irwin JC, Jang S, Kershner AM, Kong W, Kumar ME, Kuo AH, Leylek R, Liu S, Loeb GB, Lu WJ, Maltzman JS, Metzger RJ, de Morree A, Neuhöfer P, Perez K, Phansalkar R, Qi Z, Rao P, Raquer-McKay H, Sasagawa K, Scott B, Sinha R, Song H, Spencer SP, Swarup A, Swift M, Travaglini KJ, Trimm E, Veizades S, Vijayakumar S, Wang B, Wang W, Winkler J, Xie J, Yung AR, Artandi SE, Beachy PA, Clarke MF, Giudice LC, Huang FW, Huang KC, Idoyaga J, Kim SK, Krasnow M, Kuo CS, Nguyen P, Quake SR, Rando TA, Red-Horse K, Reiter J, Relman DA, Sonnenburg JL, Wang B, Wu A, Wu SM, Wyss-Coray T. The Tabula Sapiens: A multiple-organ, single-cell transcriptomic atlas of humans. Science 2022; 376:eabl4896. [PMID: 35549404 PMCID: PMC9812260 DOI: 10.1126/science.abl4896] [Citation(s) in RCA: 225] [Impact Index Per Article: 112.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Molecular characterization of cell types using single-cell transcriptome sequencing is revolutionizing cell biology and enabling new insights into the physiology of human organs. We created a human reference atlas comprising nearly 500,000 cells from 24 different tissues and organs, many from the same donor. This atlas enabled molecular characterization of more than 400 cell types, their distribution across tissues, and tissue-specific variation in gene expression. Using multiple tissues from a single donor enabled identification of the clonal distribution of T cells between tissues, identification of the tissue-specific mutation rate in B cells, and analysis of the cell cycle state and proliferative potential of shared cell types across tissues. Cell type-specific RNA splicing was discovered and analyzed across tissues within an individual.
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5
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Miller CL, Sagiv-Barfi I, Neuhöfer P, Czerwinski DK, Artandi SE, Bertozzi CR, Levy R, Cochran JR. Systemic delivery of a targeted synthetic immunostimulant transforms the immune landscape for effective tumor regression. Cell Chem Biol 2022; 29:451-462.e8. [PMID: 34774126 PMCID: PMC9134376 DOI: 10.1016/j.chembiol.2021.10.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 07/14/2021] [Accepted: 10/25/2021] [Indexed: 01/07/2023]
Abstract
Promoting immune activation within the tumor microenvironment (TME) is a promising therapeutic strategy to reverse tumor immunosuppression and elicit anti-tumor immunity. To enable tumor-localized immunotherapy following intravenous administration, we chemically conjugated a polyspecific integrin-binding peptide (PIP) to an immunostimulant (Toll-like receptor 9 [TLR9] agonist: CpG) to generate a tumor-targeted immunomodulatory agent, referred to as PIP-CpG. We demonstrate that systemic delivery of PIP-CpG induces tumor regression and enhances therapeutic efficacy compared with untargeted CpG in aggressive murine breast and pancreatic cancer models. Furthermore, PIP-CpG transforms the immune-suppressive TME dominated by myeloid-derived suppressor cells into a lymphocyte-rich TME infiltrated with activated CD8+ T cells, CD4+ T cells, and B cells. Finally, we show that T cells are required for therapeutic efficacy and that PIP-CpG treatment generates tumor-specific CD8+ T cells. These data demonstrate that conjugation to a synthetic tumor-targeted peptide can improve the efficacy of systemically administered immunostimulants and lead to durable anti-tumor immune responses.
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Affiliation(s)
- Caitlyn L Miller
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Idit Sagiv-Barfi
- Division of Oncology, Department of Medicine, Stanford University, Stanford, CA 94305, USA
| | - Patrick Neuhöfer
- Department of Medicine, Stanford University, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University, Stanford, CA 94305, USA; Stanford Cancer Institute, Stanford University, Stanford, CA 94305, USA
| | - Debra K Czerwinski
- Division of Oncology, Department of Medicine, Stanford University, Stanford, CA 94305, USA
| | - Steven E Artandi
- Department of Medicine, Stanford University, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University, Stanford, CA 94305, USA; Stanford Cancer Institute, Stanford University, Stanford, CA 94305, USA
| | - Carolyn R Bertozzi
- Department of Chemistry and Stanford ChEM-H, Stanford University, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Ronald Levy
- Division of Oncology, Department of Medicine, Stanford University, Stanford, CA 94305, USA
| | - Jennifer R Cochran
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA.
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6
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Vaidyanathan S, Baik R, Chen L, Bravo DT, Suarez CJ, Abazari SM, Salahudeen AA, Dudek AM, Teran CA, Davis TH, Lee CM, Bao G, Randell SH, Artandi SE, Wine JJ, Kuo CJ, Desai TJ, Nayak JV, Sellers ZM, Porteus MH. Targeted replacement of full-length CFTR in human airway stem cells by CRISPR-Cas9 for pan-mutation correction in the endogenous locus. Mol Ther 2022; 30:223-237. [PMID: 33794364 PMCID: PMC8753290 DOI: 10.1016/j.ymthe.2021.03.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 02/23/2021] [Accepted: 03/25/2021] [Indexed: 01/07/2023] Open
Abstract
Cystic fibrosis (CF) is a monogenic disease caused by impaired production and/or function of the CF transmembrane conductance regulator (CFTR) protein. Although we have previously shown correction of the most common pathogenic mutation, there are many other pathogenic mutations throughout the CF gene. An autologous airway stem cell therapy in which the CFTR cDNA is precisely inserted into the CFTR locus may enable the development of a durable cure for almost all CF patients, irrespective of the causal mutation. Here, we use CRISPR-Cas9 and two adeno-associated viruses (AAVs) carrying the two halves of the CFTR cDNA to sequentially insert the full CFTR cDNA along with a truncated CD19 (tCD19) enrichment tag in upper airway basal stem cells (UABCs) and human bronchial epithelial cells (HBECs). The modified cells were enriched to obtain 60%-80% tCD19+ UABCs and HBECs from 11 different CF donors with a variety of mutations. Differentiated epithelial monolayers cultured at air-liquid interface showed restored CFTR function that was >70% of the CFTR function in non-CF controls. Thus, our study enables the development of a therapy for almost all CF patients, including patients who cannot be treated using recently approved modulator therapies.
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Affiliation(s)
| | - Ron Baik
- Department of Pediatrics, Stanford University, Stanford, CA 94305, USA
| | - Lu Chen
- Department of Internal Medicine, Stanford University, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA; Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Dawn T Bravo
- Department of Otolaryngology-Head and Neck Surgery, Stanford, CA 94305, USA
| | - Carlos J Suarez
- Department of Pathology, Stanford University, Stanford, CA 94305, USA
| | - Shayda M Abazari
- Department of Pediatrics, Stanford University, Stanford, CA 94305, USA
| | - Ameen A Salahudeen
- Department of Internal Medicine, Stanford University, Stanford, CA 94305, USA
| | - Amanda M Dudek
- Department of Pediatrics, Stanford University, Stanford, CA 94305, USA
| | | | - Timothy H Davis
- Department of Bioengineering, Rice University, Houston, TX 77030, USA
| | - Ciaran M Lee
- Department of Bioengineering, Rice University, Houston, TX 77030, USA
| | - Gang Bao
- Department of Bioengineering, Rice University, Houston, TX 77030, USA
| | - Scott H Randell
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Steven E Artandi
- Department of Internal Medicine, Stanford University, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA; Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Jeffrey J Wine
- Department of Psychology, Stanford University, Stanford, CA 94305, USA
| | - Calvin J Kuo
- Department of Internal Medicine, Stanford University, Stanford, CA 94305, USA
| | - Tushar J Desai
- Department of Internal Medicine, Stanford University, Stanford, CA 94305, USA
| | - Jayakar V Nayak
- Department of Otolaryngology-Head and Neck Surgery, Stanford, CA 94305, USA
| | - Zachary M Sellers
- Department of Pediatrics, Stanford University, Stanford, CA 94305, USA
| | - Matthew H Porteus
- Department of Pediatrics, Stanford University, Stanford, CA 94305, USA.
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7
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Galati A, Scatolini L, Micheli E, Bavasso F, Cicconi A, Maccallini P, Chen L, Roake CM, Schoeftner S, Artandi SE, Gatti M, Cacchione S, Raffa GD. The S-adenosylmethionine analog sinefungin inhibits the trimethylguanosine synthase TGS1 to promote telomerase activity and telomere lengthening. FEBS Lett 2021; 596:42-52. [PMID: 34817067 DOI: 10.1002/1873-3468.14240] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 10/16/2021] [Accepted: 11/09/2021] [Indexed: 12/11/2022]
Abstract
Mutations in many genes that control the expression, the function, or the stability of telomerase cause telomere biology disorders (TBDs), such as dyskeratosis congenita, pulmonary fibrosis, and aplastic anemia. Mutations in a subset of the genes associated with TBDs cause reductions of the telomerase RNA moiety hTR, thus limiting telomerase activity. We have recently found that loss of the trimethylguanosine synthase TGS1 increases both hTR abundance and telomerase activity and leads to telomere elongation. Here, we show that treatment with the S-adenosylmethionine analog sinefungin inhibits TGS1 activity, increases the hTR levels, and promotes telomere lengthening in different cell types. Our results hold promise for restoring telomere length in stem and progenitor cells from TBD patients with reduced hTR levels.
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Affiliation(s)
- Alessandra Galati
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy
| | - Livia Scatolini
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy
| | - Emanuela Micheli
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy
| | - Francesca Bavasso
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy
| | - Alessandro Cicconi
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy
| | - Paolo Maccallini
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy
| | - Lu Chen
- Cancer Signaling and Epigenetics Program-Cancer Epigenetics Institute, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Caitlin M Roake
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Stefan Schoeftner
- Dipartimento di Scienze della Vita, Università degli studi di Trieste, Italy
| | - Steven E Artandi
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Maurizio Gatti
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy.,Istituto di Biologia e Patologia Molecolari del CNR, Roma, Italy
| | - Stefano Cacchione
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy
| | - Grazia D Raffa
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy
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8
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Neuhöfer P, Roake CM, Kim SJ, Lu RJ, West RB, Charville GW, Artandi SE. Acinar cell clonal expansion in pancreas homeostasis and carcinogenesis. Nature 2021; 597:715-719. [PMID: 34526722 DOI: 10.1038/s41586-021-03916-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 08/16/2021] [Indexed: 02/08/2023]
Abstract
Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer deaths worldwide1. Studies in human tissues and in mouse models have suggested that for many cancers, stem cells sustain early mutations driving tumour development2,3. For the pancreas, however, mechanisms underlying cellular renewal and initiation of PDAC remain unresolved. Here, using lineage tracing from the endogenous telomerase reverse transcriptase (Tert) locus, we identify a rare TERT-positive subpopulation of pancreatic acinar cells dispersed throughout the exocrine compartment. During homeostasis, these TERThigh acinar cells renew the pancreas by forming expanding clones of acinar cells, whereas randomly marked acinar cells do not form these clones. Specific expression of mutant Kras in TERThigh acinar cells accelerates acinar clone formation and causes transdifferentiation to ductal pre-invasive pancreatic intraepithelial neoplasms by upregulating Ras-MAPK signalling and activating the downstream kinase ERK (phospho-ERK). In resected human pancreatic neoplasms, we find that foci of phospho-ERK-positive acinar cells are common and frequently contain activating KRAS mutations, suggesting that these acinar regions represent an early cancer precursor lesion. These data support a model in which rare TERThigh acinar cells may sustain KRAS mutations, driving acinar cell expansion and creating a field of aberrant cells initiating pancreatic tumorigenesis.
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Affiliation(s)
- Patrick Neuhöfer
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA.,Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA.,Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
| | - Caitlin M Roake
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA.,Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA.,Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
| | - Stewart J Kim
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA.,Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA.,Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
| | - Ryan J Lu
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA.,Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA.,Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
| | - Robert B West
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
| | - Gregory W Charville
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
| | - Steven E Artandi
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA. .,Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA. .,Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA.
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9
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Abstract
The majority of the mammalian genome is transcribed into non-coding RNAs, many of which co-evolve with RNA-binding proteins (RBPs) to function as biochemically defined and tractable ribonucleoproteins (RNPs). Here, we applied icSHAPE- a robust and versatile RNA structural probing pipeline- to endogenous RNPs purified from nuclei, providing base-resolution structural rationale for RNP activity and subcellular localization. Combining with genetic and biochemical reconstitutions, structural and functional alternations can be directly attributed to a given RBP without ambiguity. For complete details on the use and execution of this protocol, please refer to Chen et al. (2018).
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Affiliation(s)
- Lu Chen
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Howard Y. Chang
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA 94305, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Steven E. Artandi
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
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10
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Chen L, Roake CM, Galati A, Bavasso F, Micheli E, Saggio I, Schoeftner S, Cacchione S, Gatti M, Artandi SE, Raffa GD. Loss of Human TGS1 Hypermethylase Promotes Increased Telomerase RNA and Telomere Elongation. Cell Rep 2021; 30:1358-1372.e5. [PMID: 32023455 PMCID: PMC7156301 DOI: 10.1016/j.celrep.2020.01.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 11/09/2019] [Accepted: 12/31/2019] [Indexed: 02/08/2023] Open
Abstract
Biogenesis of the human telomerase RNA (hTR) involves a complex series of posttranscriptional modifications, including hypermethylation of the 5' mono-methylguanosine cap to a tri-methylguanosine cap (TMG). How the TMG cap affects hTR maturation is unknown. Here, we show that depletion of trimethylguanosine synthase 1 (TGS1), the enzyme responsible for cap hypermethylation, increases levels of hTR and telomerase. Diminished trimethylation increases hTR association with the cap-binding complex (CBC) and with Sm chaperone proteins. Loss of TGS1 causes an increase in accumulation of mature hTR in both the nucleus and the cytoplasm compared with controls. In TGS1 mutant cells, increased hTR assembles with telomerase reverse transcriptase (TERT) protein to yield elevated active telomerase complexes and increased telomerase activity, resulting in telomere elongation in cultured human cells. Our results show that TGS1-mediated hypermethylation of the hTR cap inhibits hTR accumulation, restrains levels of assembled telomerase, and limits telomere elongation.
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Affiliation(s)
- Lu Chen
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Caitlin M Roake
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Alessandra Galati
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Francesca Bavasso
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Emanuela Micheli
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Isabella Saggio
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Stefan Schoeftner
- Cancer Epigenetic Group, Laboratorio Nazionale Consorzio Interuniversitario Biotecnologie, Trieste, Italy
| | - Stefano Cacchione
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Maurizio Gatti
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy; Istituto di Biologia e Patologia Molecolari (IBPM) del CNR, Roma, Italy
| | - Steven E Artandi
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Grazia D Raffa
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy.
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11
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Chen L, Bellone RR, Wang Y, Singer-Berk M, Sugasawa K, Ford JM, Artandi SE. A novel DDB2 mutation causes defective recognition of UV-induced DNA damages and prevalent equine squamous cell carcinoma. DNA Repair (Amst) 2020; 97:103022. [PMID: 33276309 DOI: 10.1016/j.dnarep.2020.103022] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 09/22/2020] [Accepted: 11/09/2020] [Indexed: 02/06/2023]
Abstract
Squamous cell carcinoma (SCC) occurs frequently in the human Xeroderma Pigmentosum (XP) syndrome and is characterized by deficient UV-damage repair. SCC is the most common equine ocular cancer and the only associated genetic risk factor is a UV-damage repair protein. Specifically, a missense mutation in horse DDB2 (T338M) was strongly associated with both limbal SCC and third eyelid SCC in three breeds of horses (Halflinger, Belgian, and Rocky Mountain Horses) and was hypothesized to impair binding to UV-damaged DNA. Here, we investigate DDB2-T338M mutant's capacity to recognize UV lesions in vitro and in vivo, together with human XP mutants DDB2-R273H and -K244E. We show that the recombinant DDB2-T338M assembles with DDB1, but fails to show any detectable binding to DNA substrates with or without UV lesions, due to a potential structural disruption of the rigid DNA recognition β-loop. Consistently, we demonstrate that the cellular DDB2-T338M is defective in its recruitment to focally radiated DNA damages, and in its access to chromatin. Thus, we provide direct functional evidence indicating the DDB2-T338M recapitulates molecular defects of human XP mutants, and is the causal loss-of-function allele that gives rise to equine ocular SCCs. Our findings shed new light on the mechanism of DNA recognition by UV-DDB and on the initiation of ocular malignancy.
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Affiliation(s)
- Lu Chen
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Rebecca R Bellone
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA; Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA
| | - Yan Wang
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Moriel Singer-Berk
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA; Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA
| | - Kaoru Sugasawa
- Biosignal Research Center, Kobe University, Kobe, Hyogo 657-8501, Japan
| | - James M Ford
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA 94304, USA
| | - Steven E Artandi
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
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12
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Abstract
Telomerase is a ribonucleoprotein complex, the catalytic core of which includes the telomerase reverse transcriptase (TERT) and the non-coding human telomerase RNA (hTR), which serves as a template for the addition of telomeric repeats to chromosome ends. Telomerase expression is restricted in humans to certain cell types, and telomerase levels are tightly controlled in normal conditions. Increased levels of telomerase are found in the vast majority of human cancers, and we have recently begun to understand the mechanisms by which cancer cells increase telomerase activity. Conversely, germline mutations in telomerase-relevant genes that decrease telomerase function cause a range of genetic disorders, including dyskeratosis congenita, idiopathic pulmonary fibrosis and bone marrow failure. In this Review, we discuss the transcriptional regulation of human TERT, hTR processing, assembly of the telomerase complex, the cellular localization of telomerase and its recruitment to telomeres, and the regulation of telomerase activity. We also discuss the disease relevance of each of these steps of telomerase biogenesis.
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Affiliation(s)
- Caitlin M Roake
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA.,Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA.,Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
| | - Steven E Artandi
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA. .,Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA. .,Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA.
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13
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Artandi SE, Neuhöfer P, Roake CM, Kim S, Lu R, Charville G. Abstract 4521: Mutant Kras expression triggers clonal acinar cell expansion as an early step in pancreas cancer. Cancer Res 2019. [DOI: 10.1158/1538-7445.am2019-4521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Pancreatic ductal adenocarcinoma (PDA) is the third leading cause of cancer-related deaths in the United States with the lowest 5-year survival rate of any major cancer, in part due to late detection of the disease. Studies indicate that pre-invasive lesions - pancreatic intraepithelial neoplasias (PanINs) - progress to PDA. The cell of origin for PDA is still under debate. While lineage-tracing experiments in mice indicate that PanINs originate from acinar cells, cell culture studies suggest that ductal cells can give rise to PanINs. In addition to these important questions regarding cancer initiation, mechanisms of cellular renewal in the exocrine pancreas remain poorly understood. The enzyme telomerase is intimately associated with cancer, and with stem cells and tissue renewal. Telomerase is required for long-term cell proliferation through its critical role in maintaining telomeres. The core enzyme consists of the RNA component TERC and the reverse transcriptase TERT. Moreover, telomerase is activated in over 90% human cancers and genome wide association studies have linked polymorphisms in the Tertgene with an increased risk of pancreas cancer. To analyze the role of TERT-expressing cells in the pancreas during homeostasis, regeneration and tumorigenesis, we generated a mouse line that expresses the regulated CreERT2 recombinase under the endogenous TERT promoter (TertCreERT2/+). Crossing these mice to a reporter strain enables the permanent labeling of TERT-expressing cells and their progeny upon tamoxifen injection. We find that rare TERT+ cells exist throughout the pancreas within the acinar and islet cell populations, but not in ductal cells. We show that rare TERT+ acinar cells clonally expand to renew the acinar compartment during homeostasis and during pancreas injury. To understand how these TERT+ acinar progenitor cells respond to mutant Kras, we crossed TertCreERT2/+mice with KrasLoxStopLox-G12D/+mice. We find that activation of KrasG12D in TERT-expressing cells in adult mice promotes accelerated acinar clone formation and these acinar lesions ultimately convert to PanIN pre-invasive lesions. Our data indicate that TERT-expressing cells represent an acinar progenitor cell population. Furthermore, these progenitor cells respond to mutant Kras first through a regenerative response yielding expanding acinar clones, followed by conversion to ductal PanIN lesions. We propose that acinar cell expansion is an early step in pancreatic tumorigenesis that precedes ADM and PanIN formation.
Citation Format: Steven E. Artandi, Patrick Neuhöfer, Caitlin M. Roake, Stewart Kim, Ryan Lu, Greg Charville. Mutant Kras expression triggers clonal acinar cell expansion as an early step in pancreas cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4521.
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Affiliation(s)
| | | | | | - Stewart Kim
- Stanford Univ. School of Medicine, Stanford, CA
| | - Ryan Lu
- Stanford Univ. School of Medicine, Stanford, CA
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14
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Mumbach MR, Granja JM, Flynn RA, Roake CM, Satpathy AT, Rubin AJ, Qi Y, Jiang Z, Shams S, Louie BH, Guo JK, Gennert DG, Corces MR, Khavari PA, Atianand MK, Artandi SE, Fitzgerald KA, Greenleaf WJ, Chang HY. HiChIRP reveals RNA-associated chromosome conformation. Nat Methods 2019; 16:489-492. [PMID: 31133759 DOI: 10.1038/s41592-019-0407-x] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 04/05/2019] [Indexed: 12/25/2022]
Abstract
Modular domains of long non-coding RNAs can serve as scaffolds to bring distant regions of the linear genome into spatial proximity. Here, we present HiChIRP, a method leveraging bio-orthogonal chemistry and optimized chromosome conformation capture conditions, which enables interrogation of chromatin architecture focused around a specific RNA of interest down to approximately ten copies per cell. HiChIRP of three nuclear RNAs reveals insights into promoter interactions (7SK), telomere biology (telomerase RNA component) and inflammatory gene regulation (lincRNA-EPS).
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Affiliation(s)
- Maxwell R Mumbach
- Center for Personal Dynamic Regulomes, Stanford University School of Medicine, Stanford, CA, USA.,Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Jeffrey M Granja
- Center for Personal Dynamic Regulomes, Stanford University School of Medicine, Stanford, CA, USA.,Program in Biophysics, Stanford University School of Medicine, Stanford, CA, USA
| | - Ryan A Flynn
- Center for Personal Dynamic Regulomes, Stanford University School of Medicine, Stanford, CA, USA
| | - Caitlin M Roake
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA.,Cancer Biology Program, Stanford University School of Medicine, Stanford, CA, USA
| | - Ansuman T Satpathy
- Center for Personal Dynamic Regulomes, Stanford University School of Medicine, Stanford, CA, USA.,Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
| | - Adam J Rubin
- Program in Epithelial Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Yanyan Qi
- Center for Personal Dynamic Regulomes, Stanford University School of Medicine, Stanford, CA, USA
| | - Zhaozhao Jiang
- Program in Innate Immunity, University of Massachusetts Medical School, Worcester, MA, USA
| | - Shadi Shams
- Center for Personal Dynamic Regulomes, Stanford University School of Medicine, Stanford, CA, USA
| | - Bryan H Louie
- Center for Personal Dynamic Regulomes, Stanford University School of Medicine, Stanford, CA, USA
| | - Jimmy K Guo
- Center for Personal Dynamic Regulomes, Stanford University School of Medicine, Stanford, CA, USA
| | - David G Gennert
- Center for Personal Dynamic Regulomes, Stanford University School of Medicine, Stanford, CA, USA.,Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - M Ryan Corces
- Center for Personal Dynamic Regulomes, Stanford University School of Medicine, Stanford, CA, USA
| | - Paul A Khavari
- Program in Epithelial Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Maninjay K Atianand
- Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Steven E Artandi
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Katherine A Fitzgerald
- Program in Innate Immunity, University of Massachusetts Medical School, Worcester, MA, USA
| | - William J Greenleaf
- Center for Personal Dynamic Regulomes, Stanford University School of Medicine, Stanford, CA, USA. .,Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA. .,Department of Applied Physics, Stanford University, Stanford, CA, USA. .,Chan Zuckerberg Biohub, San Francisco, CA, USA.
| | - Howard Y Chang
- Center for Personal Dynamic Regulomes, Stanford University School of Medicine, Stanford, CA, USA. .,Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA. .,Program in Epithelial Biology, Stanford University School of Medicine, Stanford, CA, USA. .,Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA, USA.
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15
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Lin S, Nascimento EM, Gajera CR, Chen L, Neuhöfer P, Garbuzov A, Wang S, Artandi SE. Distributed hepatocytes expressing telomerase repopulate the liver in homeostasis and injury. Nature 2018; 556:244-248. [PMID: 29618815 PMCID: PMC5895494 DOI: 10.1038/s41586-018-0004-7] [Citation(s) in RCA: 151] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 02/23/2018] [Indexed: 01/19/2023]
Abstract
Hepatocytes are replenished gradually during homeostasis and robustly
after liver injury1,2. In adults, new hepatocytes originate
from the existing hepatocyte pool3-8, but the
cellular source of renewing hepatocytes remains incompletely understood.
Telomerase is expressed in many stem cell populations, and telomerase pathway
gene mutations are linked to liver diseases9-11. Here, we
identify a subset of hepatocytes that expresses high levels of telomerase and
show that this hepatocyte subset repopulates the liver during homeostasis and
injury. Using lineage tracing from the telomerase reverse transcriptase
(Tert) locus in mice, we demonstrate that rare hepatocytes
with high telomerase expression are distributed throughout the liver lobule.
During homeostasis, these cells regenerate hepatocytes in all lobular zones, and
both self-renew and differentiate to yield expanding hepatocyte clones that
eventually dominate the liver. In injury responses, the repopulating activity of
TERTHigh hepatocytes is accelerated and their progeny cross zonal
boundaries. RNA-seq reveals that metabolic genes are down regulated in
TERTHigh hepatocytes, indicating that metabolic activity and
repopulating activity may be segregated within the hepatocyte lineage. Genetic
ablation of TERTHigh hepatocytes combined with chemical injury causes
a marked increase in stellate cell activation and fibrosis. These results
provide support for a ‘distributed model’ of hepatocyte renewal
in which a subset of hepatocytes dispersed throughout the lobule clonally
expands to maintain liver mass.
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Affiliation(s)
- Shengda Lin
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA.,Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA.,Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA
| | - Elisabete M Nascimento
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA.,Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA.,Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA
| | - Chandresh R Gajera
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA.,Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA.,Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA
| | - Lu Chen
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA.,Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA.,Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA
| | - Patrick Neuhöfer
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA.,Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA.,Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA
| | - Alina Garbuzov
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA.,Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA.,Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA
| | - Sui Wang
- Department of Ophthalmology, Stanford University School of Medicine, Stanford, CA, USA
| | - Steven E Artandi
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA. .,Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA. .,Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA.
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16
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Garbuzov A, Pech MF, Hasegawa K, Sukhwani M, Zhang RJ, Orwig KE, Artandi SE. Purification of GFRα1+ and GFRα1- Spermatogonial Stem Cells Reveals a Niche-Dependent Mechanism for Fate Determination. Stem Cell Reports 2018; 10:553-567. [PMID: 29337115 PMCID: PMC5830912 DOI: 10.1016/j.stemcr.2017.12.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 12/08/2017] [Accepted: 12/11/2017] [Indexed: 01/15/2023] Open
Abstract
Undifferentiated spermatogonia comprise a pool of stem cells and progenitor cells that show heterogeneous expression of markers, including the cell surface receptor GFRα1. Technical challenges in isolation of GFRα1+ versus GFRα1– undifferentiated spermatogonia have precluded the comparative molecular characterization of these subpopulations and their functional evaluation as stem cells. Here, we develop a method to purify these subpopulations by fluorescence-activated cell sorting and show that GFRα1+ and GFRα1– undifferentiated spermatogonia both demonstrate elevated transplantation activity, while differing principally in receptor tyrosine kinase signaling and cell cycle. We identify the cell surface molecule melanocyte cell adhesion molecule (MCAM) as differentially expressed in these populations and show that antibodies to MCAM allow isolation of highly enriched populations of GFRα1+ and GFRα1– spermatogonia from adult, wild-type mice. In germ cell culture, GFRα1– cells upregulate MCAM expression in response to glial cell line-derived neurotrophic factor (GDNF)/fibroblast growth factor (FGF) stimulation. In transplanted hosts, GFRα1– spermatogonia yield GFRα1+ spermatogonia and restore spermatogenesis, albeit at lower rates than their GFRα1+ counterparts. Together, these data provide support for a model of a stem cell pool in which the GFRα1+ and GFRα1– cells are closely related but show key cell-intrinsic differences and can interconvert between the two states based, in part, on access to niche factors. A new method to purify GFRα1+ and GFRα1– undifferentiated spermatogonia by FACS GFRα1+ and GFRα1– cells differ in receptor tyrosine kinase signaling Differential surface MCAM expression can distinguish GFRα1+ and GFRα1– cells GFRα1– cells have a third of the transplantation activity of GFRα1+ cells
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Affiliation(s)
- Alina Garbuzov
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Matthew F Pech
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Cancer Biology Program, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Kazuteru Hasegawa
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Meena Sukhwani
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh School of Medicine, Magee-Womens Research Institute, Pittsburgh, PA 15213, USA
| | - Ruixuan J Zhang
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Kyle E Orwig
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh School of Medicine, Magee-Womens Research Institute, Pittsburgh, PA 15213, USA
| | - Steven E Artandi
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Cancer Biology Program, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA.
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17
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Abstract
Functions of the telomeric repeat-containing RNA (TERRA), the long noncoding RNA (lncRNA) transcribed from telomeres, have eluded researchers. In this issue of Cell, Graf el al. and Chu et al. uncover new regulatory roles for TERRA at the telomere and at distant genomic sites.
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Affiliation(s)
- Caitlin M Roake
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Cancer Biology Program, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Steven E Artandi
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Cancer Biology Program, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA.
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18
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Pech MF, Garbuzov A, Hasegawa K, Sukhwani M, Zhang RJ, Benayoun BA, Brockman SA, Lin S, Brunet A, Orwig KE, Artandi SE. High telomerase is a hallmark of undifferentiated spermatogonia and is required for maintenance of male germline stem cells. Genes Dev 2015; 29:2420-34. [PMID: 26584619 PMCID: PMC4691947 DOI: 10.1101/gad.271783.115] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 10/27/2015] [Indexed: 01/15/2023]
Abstract
Telomerase inactivation causes loss of the male germline in worms, fish, and mice, indicating a conserved dependence on telomere maintenance in this cell lineage. Here, using telomerase reverse transcriptase (Tert) reporter mice, we found that very high telomerase expression is a hallmark of undifferentiated spermatogonia, the mitotic population where germline stem cells reside. We exploited these high telomerase levels as a basis for purifying undifferentiated spermatogonia using fluorescence-activated cell sorting. Telomerase levels in undifferentiated spermatogonia and embryonic stem cells are comparable and much greater than in somatic progenitor compartments. Within the germline, we uncovered an unanticipated gradient of telomerase activity that also enables isolation of more mature populations. Transcriptomic comparisons of Tert(High) undifferentiated spermatogonia and Tert(Low) differentiated spermatogonia by RNA sequencing reveals marked differences in cell cycle and key molecular features of each compartment. Transplantation studies show that germline stem cell activity is confined to the Tert(High) cKit(-) population. Telomere shortening in telomerase knockout strains causes depletion of undifferentiated spermatogonia and eventual loss of all germ cells after undifferentiated spermatogonia drop below a critical threshold. These data reveal that high telomerase expression is a fundamental characteristic of germline stem cells, thus explaining the broad dependence on telomerase for germline immortality in metazoans.
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Affiliation(s)
- Matthew F Pech
- Department of Medicine, Stanford University School of Medicine, Stanford, California 94305, USA; Cancer Biology Program, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Alina Garbuzov
- Department of Medicine, Stanford University School of Medicine, Stanford, California 94305, USA; Department of Genetics, Stanford University, California 94305, USA
| | - Kazuteru Hasegawa
- Department of Medicine, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Meena Sukhwani
- Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh School of Medicine, Pittsburgh Pennsylvania 15213, USA; Magee-Womens Research Institute, Pittsburgh, Pennsylvania 15213, USA
| | - Ruixuan J Zhang
- Department of Medicine, Stanford University School of Medicine, Stanford, California 94305, USA
| | | | - Stephanie A Brockman
- Department of Medicine, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Shengda Lin
- Department of Medicine, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Anne Brunet
- Department of Genetics, Stanford University, California 94305, USA
| | - Kyle E Orwig
- Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh School of Medicine, Pittsburgh Pennsylvania 15213, USA; Magee-Womens Research Institute, Pittsburgh, Pennsylvania 15213, USA
| | - Steven E Artandi
- Department of Medicine, Stanford University School of Medicine, Stanford, California 94305, USA; Cancer Biology Program, Stanford University School of Medicine, Stanford, California 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, USA
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19
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Roake CM, Artandi SE. Keeping It in the Family: ATRX Loss Promotes Persistent Sister Telomere Cohesion in ALT Cancer Cells. Cancer Cell 2015; 28:277-9. [PMID: 26373274 DOI: 10.1016/j.ccell.2015.08.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this issue of Cancer Cell, Ramamoorthy and Smith report that cancer cells that maintain their chromosome ends through alternative lengthening of telomeres (ALT) display persistent sister telomere cohesion. This delayed resolution of sister telomere cohesion depends upon the loss of ATRX and its histone-sequestering function and is associated with increased recombination between sister telomeres.
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Affiliation(s)
- Caitlin M Roake
- Cancer Biology Program, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Steven E Artandi
- Cancer Biology Program, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA.
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20
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Pech M, Garbuzov A, Sukhwani M, Benayoun B, Lin S, Brunet A, Orwig K, Artandi SE. Abstract 980: Encoding immortality: Transcriptional control of telomerase in stem cells in vivo. Cancer Res 2015. [DOI: 10.1158/1538-7445.am2015-980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
One of the invariant features of human cancer is unlimited proliferation, a hallmark conferred by telomerase in 90% tumors. Somatic mutations in the telomerase reverse transcriptase (TERT) gene promoter are highly recurrent in human cancers. Telomerase is also critically important in human stem cells, as evidenced by mutations in telomerase, which contribute to degenerative diseases. Despite the importance of telomerase in tissue maintenance, the identity of telomerase-positive cells has remained elusive, owing to low levels of the core telomerase components. The ability to isolate TERT-positive cells in vivo would significantly advance our understanding of telomerase regulation, tissue function and carcinogenesis. To address these issues, we created knock-in transcriptional reporters of TERT expression by replacing the TERT open reading frame with the red fluorescent protein, TdTomato. Among mouse tissues, telomerase activity is most strongly expressed in testis, a tissue in which resident stem cells fuel the continuous generation of male gametes. In human sperm, telomere lengths are preserved with age, although how this is achieved, in contrast to the age-dependent telomere shortening seen in somatic tissues, remains unresolved. Using TERTTdTomato/+ knock-in reporter mice, we found that only a rare subset of cells in mouse testis expresses high levels of TERT. By double immunostaining, these TERTHigh cells were synonymous with undifferentiated spermatogonia, the primitive cell population in which male germline stem cells reside. By FACS of the germ cells in testis, TERTHigh cells and TERTLow cells represent discrete populations that were further studied using additional markers. The undifferentiated spermatogonia in the TERTHigh population were further fractionated into GFRalpha+ and GFRalpha- populations. Cells in the TERTLow population were nearly all cKit+, consistent with their identification as differentiated spermatogonia. We characterized these populations in molecular and functional terms. Using RNAseq, we established a hierarchy among these populations according to which the TERTHigh GFRalpha1+ cells give rise to TERTHigh GFRalpha1- cells, which in turn yield TERTLow cKit+ cells. Surprisingly, in transplantation studies, TERTHigh GFRalpha1+ cells and TERTHigh GFRalpha1- cells possess comparable stem cell activity. These data suggest the existence of stem cell plasticity according to which cells in either primitive population retain stem cell potential. In contrast, TERTLow cKit+ cells fail to reconstitute spermatogenesis in transplantation experiments and therefore lack stem cell activity. These studies reveal marked transcriptional regulation of telomerase in vivo and show a strong concordance between stemness and telomerase levels in rare subsets of tissue stem cells in vivo. These findings indicate the existence of innate signaling pathways controlling TERT expression over a surprising dynamic range.
Citation Format: Matthew Pech, Alina Garbuzov, Meena Sukhwani, Berenice Benayoun, Shengda Lin, Anne Brunet, Kyle Orwig, Steven E. Artandi. Encoding immortality: Transcriptional control of telomerase in stem cells in vivo. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 980. doi:10.1158/1538-7445.AM2015-980
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Affiliation(s)
- Matthew Pech
- 1Stanford University School of Medicine, Stanford, CA
| | | | | | | | - Shengda Lin
- 1Stanford University School of Medicine, Stanford, CA
| | - Anne Brunet
- 1Stanford University School of Medicine, Stanford, CA
| | - Kyle Orwig
- 2University of Pittsburgh, Pittsburgh, PA
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21
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Raval A, Behbehani GK, Nguyen LXT, Thomas D, Kusler B, Garbuzov A, Ramunas J, Holbrook C, Park CY, Blau H, Nolan GP, Artandi SE, Mitchell BS. Reversibility of Defective Hematopoiesis Caused by Telomere Shortening in Telomerase Knockout Mice. PLoS One 2015; 10:e0131722. [PMID: 26133370 PMCID: PMC4489842 DOI: 10.1371/journal.pone.0131722] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 06/04/2015] [Indexed: 01/08/2023] Open
Abstract
Telomere shortening is common in bone marrow failure syndromes such as dyskeratosis congenita (DC), aplastic anemia (AA) and myelodysplastic syndromes (MDS). However, improved knowledge of the lineage-specific consequences of telomere erosion and restoration of telomere length in hematopoietic progenitors is required to advance therapeutic approaches. We have employed a reversible murine model of telomerase deficiency to compare the dependence of erythroid and myeloid lineage differentiation on telomerase activity. Fifth generation Tert-/- (G5 Tert-/-) mice with shortened telomeres have significant anemia, decreased erythroblasts and reduced hematopoietic stem cell (HSC) populations associated with neutrophilia and increased myelopoiesis. Intracellular multiparameter analysis by mass cytometry showed significantly reduced cell proliferation and increased sensitivity to activation of DNA damage checkpoints in erythroid progenitors and in erythroid-biased CD150hi HSC, but not in myeloid progenitors. Strikingly, Cre-inducible reactivation of telomerase activity restored hematopoietic stem and progenitor cell (HSPC) proliferation, normalized the DNA damage response, and improved red cell production and hemoglobin levels. These data establish a direct link between the loss of TERT activity, telomere shortening and defective erythropoiesis and suggest that novel strategies to restore telomerase function may have an important role in the treatment of the resulting anemia.
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Affiliation(s)
- Aparna Raval
- Stanford Cancer Institute and Division of Hematology, Department of Medicine, Stanford University, Stanford, CA, 94305, United States of America
| | - Gregory K. Behbehani
- Stanford Cancer Institute and Division of Hematology, Department of Medicine, Stanford University, Stanford, CA, 94305, United States of America
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology Stanford University, School of Medicine, Stanford, CA, 94305, United States of America
| | - Le Xuan Truong Nguyen
- Stanford Cancer Institute and Division of Hematology, Department of Medicine, Stanford University, Stanford, CA, 94305, United States of America
| | - Daniel Thomas
- Stanford Cancer Institute and Division of Hematology, Department of Medicine, Stanford University, Stanford, CA, 94305, United States of America
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA, 94035, United States of America
| | - Brenda Kusler
- Stanford Cancer Institute and Division of Hematology, Department of Medicine, Stanford University, Stanford, CA, 94305, United States of America
| | - Alina Garbuzov
- Department of Genetics, Stanford University, Stanford, CA, 94305, United States of America
| | - John Ramunas
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology Stanford University, School of Medicine, Stanford, CA, 94305, United States of America
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA, 94035, United States of America
| | - Colin Holbrook
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology Stanford University, School of Medicine, Stanford, CA, 94305, United States of America
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA, 94035, United States of America
| | - Christopher Y. Park
- Human Oncology and Pathogenesis Program and Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, United States of America
| | - Helen Blau
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology Stanford University, School of Medicine, Stanford, CA, 94305, United States of America
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA, 94035, United States of America
| | - Garry P. Nolan
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology Stanford University, School of Medicine, Stanford, CA, 94305, United States of America
| | - Steven E. Artandi
- Departments of Medicine and Biochemistry, Stanford University, Stanford, CA, 94305, United States of America
| | - Beverly S. Mitchell
- Stanford Cancer Institute and Division of Hematology, Department of Medicine, Stanford University, Stanford, CA, 94305, United States of America
- * E-mail:
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22
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Harel I, Benayoun BA, Machado B, Singh PP, Hu CK, Pech MF, Valenzano DR, Zhang E, Sharp SC, Artandi SE, Brunet A. A platform for rapid exploration of aging and diseases in a naturally short-lived vertebrate. Cell 2015; 160:1013-1026. [PMID: 25684364 DOI: 10.1016/j.cell.2015.01.038] [Citation(s) in RCA: 146] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 01/15/2015] [Accepted: 01/23/2015] [Indexed: 12/20/2022]
Abstract
VIDEO ABSTRACT Aging is a complex process that affects multiple organs. Modeling aging and age-related diseases in the lab is challenging because classical vertebrate models have relatively long lifespans. Here, we develop the first platform for rapid exploration of age-dependent traits and diseases in vertebrates, using the naturally short-lived African turquoise killifish. We provide an integrative genomic and genome-editing toolkit in this organism using our de-novo-assembled genome and the CRISPR/Cas9 technology. We mutate many genes encompassing the hallmarks of aging, and for a subset, we produce stable lines within 2-3 months. As a proof of principle, we show that fish deficient for the protein subunit of telomerase exhibit the fastest onset of telomere-related pathologies among vertebrates. We further demonstrate the feasibility of creating specific genetic variants. This genome-to-phenotype platform represents a unique resource for studying vertebrate aging and disease in a high-throughput manner and for investigating candidates arising from human genome-wide studies.
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Affiliation(s)
- Itamar Harel
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | | | - Ben Machado
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Param Priya Singh
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Chi-Kuo Hu
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Matthew F Pech
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Biochemistry Department, Stanford University School of Medicine, Stanford, CA 94305, USA
| | | | - Elisa Zhang
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Sabrina C Sharp
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Steven E Artandi
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Biochemistry Department, Stanford University School of Medicine, Stanford, CA 94305, USA; Glenn Laboratories for the Biology of Aging at Stanford, Stanford, CA 94305, USA
| | - Anne Brunet
- Department of Genetics, Stanford University, Stanford, CA 94305, USA; Glenn Laboratories for the Biology of Aging at Stanford, Stanford, CA 94305, USA.
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Freund A, Zhong FL, Venteicher AS, Meng Z, Veenstra TD, Frydman J, Artandi SE. Proteostatic control of telomerase function through TRiC-mediated folding of TCAB1. Cell 2014; 159:1389-403. [PMID: 25467444 DOI: 10.1016/j.cell.2014.10.059] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 09/29/2014] [Accepted: 10/30/2014] [Indexed: 12/13/2022]
Abstract
Telomere maintenance by telomerase is impaired in the stem cell disease dyskeratosis congenita and during human aging. Telomerase depends upon a complex pathway for enzyme assembly, localization in Cajal bodies, and association with telomeres. Here, we identify the chaperonin CCT/TRiC as a critical regulator of telomerase trafficking using a high-content genome-wide siRNA screen in human cells for factors required for Cajal body localization. We find that TRiC is required for folding the telomerase cofactor TCAB1, which controls trafficking of telomerase and small Cajal body RNAs (scaRNAs). Depletion of TRiC causes loss of TCAB1 protein, mislocalization of telomerase and scaRNAs to nucleoli, and failure of telomere elongation. DC patient-derived mutations in TCAB1 impair folding by TRiC, disrupting telomerase function and leading to severe disease. Our findings establish a critical role for TRiC-mediated protein folding in the telomerase pathway and link proteostasis, telomere maintenance, and human disease.
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Affiliation(s)
- Adam Freund
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Franklin L Zhong
- Cancer Biology Program, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Andrew S Venteicher
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Zhaojing Meng
- Laboratory of Proteomics and Analytical Technologies, Science Applications International Corporation-Frederick, National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - Timothy D Veenstra
- Laboratory of Proteomics and Analytical Technologies, Science Applications International Corporation-Frederick, National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - Judith Frydman
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Steven E Artandi
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Cancer Biology Program, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA.
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24
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Kareta MS, Gorges LL, Hafeez S, Benayoun BA, Marro S, Zmoos AF, Cecchini MJ, Spacek D, Batista LFZ, O'Brien M, Ng YH, Ang CE, Vaka D, Artandi SE, Dick FA, Brunet A, Sage J, Wernig M. Inhibition of pluripotency networks by the Rb tumor suppressor restricts reprogramming and tumorigenesis. Cell Stem Cell 2014; 16:39-50. [PMID: 25467916 DOI: 10.1016/j.stem.2014.10.019] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 08/18/2014] [Accepted: 10/24/2014] [Indexed: 12/15/2022]
Abstract
Mutations in the retinoblastoma tumor suppressor gene Rb are involved in many forms of human cancer. In this study, we investigated the early consequences of inactivating Rb in the context of cellular reprogramming. We found that Rb inactivation promotes the reprogramming of differentiated cells to a pluripotent state. Unexpectedly, this effect is cell cycle independent, and instead reflects direct binding of Rb to pluripotency genes, including Sox2 and Oct4, which leads to a repressed chromatin state. More broadly, this regulation of pluripotency networks and Sox2 in particular is critical for the initiation of tumors upon loss of Rb in mice. These studies therefore identify Rb as a global transcriptional repressor of pluripotency networks, providing a molecular basis for previous reports about its involvement in cell fate pliability, and implicate misregulation of pluripotency factors such as Sox2 in tumorigenesis related to loss of Rb function.
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Affiliation(s)
- Michael S Kareta
- Department of Pediatrics, Stanford University, Stanford, CA 94305, USA; Department of Genetics, Stanford University, Stanford, CA 94305, USA; Department of Pathology, Stanford University, Stanford, CA 94305, USA; Stanford Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305, USA
| | - Laura L Gorges
- Department of Pediatrics, Stanford University, Stanford, CA 94305, USA; Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Sana Hafeez
- Department of Pathology, Stanford University, Stanford, CA 94305, USA; Stanford Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305, USA
| | - Bérénice A Benayoun
- Department of Genetics, Stanford University, Stanford, CA 94305, USA; Paul F. Glenn Laboratories for the Biology of Aging, Stanford University, Stanford, CA 94305, USA
| | - Samuele Marro
- Department of Pathology, Stanford University, Stanford, CA 94305, USA; Stanford Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305, USA
| | - Anne-Flore Zmoos
- Department of Pediatrics, Stanford University, Stanford, CA 94305, USA; Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Matthew J Cecchini
- London Regional Cancer Program, Children's Research Institute, Western University, London, ON N6A 4L6, Canada
| | - Damek Spacek
- Department of Pediatrics, Stanford University, Stanford, CA 94305, USA; Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Luis F Z Batista
- Department of Medicine, Stanford University, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University, Stanford, CA 94305, USA; Stanford Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305, USA
| | - Megan O'Brien
- Department of Pediatrics, Stanford University, Stanford, CA 94305, USA; Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Yi-Han Ng
- Department of Pathology, Stanford University, Stanford, CA 94305, USA; Stanford Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305, USA
| | - Cheen Euong Ang
- Department of Pathology, Stanford University, Stanford, CA 94305, USA; Stanford Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305, USA
| | - Dedeepya Vaka
- Department of Pediatrics, Stanford University, Stanford, CA 94305, USA; Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Steven E Artandi
- Department of Medicine, Stanford University, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University, Stanford, CA 94305, USA; Stanford Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305, USA
| | - Frederick A Dick
- London Regional Cancer Program, Children's Research Institute, Western University, London, ON N6A 4L6, Canada
| | - Anne Brunet
- Department of Genetics, Stanford University, Stanford, CA 94305, USA; Paul F. Glenn Laboratories for the Biology of Aging, Stanford University, Stanford, CA 94305, USA
| | - Julien Sage
- Department of Pediatrics, Stanford University, Stanford, CA 94305, USA; Department of Genetics, Stanford University, Stanford, CA 94305, USA.
| | - Marius Wernig
- Department of Pathology, Stanford University, Stanford, CA 94305, USA; Stanford Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305, USA.
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25
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Zhong FL, Batista LFZ, Freund A, Pech MF, Venteicher AS, Artandi SE. TPP1 OB-fold domain controls telomere maintenance by recruiting telomerase to chromosome ends. Cell 2012; 150:481-94. [PMID: 22863003 DOI: 10.1016/j.cell.2012.07.012] [Citation(s) in RCA: 215] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 07/02/2012] [Accepted: 07/13/2012] [Indexed: 11/29/2022]
Abstract
Telomere synthesis in cancer cells and stem cells involves trafficking of telomerase to Cajal bodies, and telomerase is thought to be recruited to telomeres through interactions with telomere-binding proteins. Here, we show that the OB-fold domain of the telomere-binding protein TPP1 recruits telomerase to telomeres through an association with the telomerase reverse transcriptase TERT. When tethered away from telomeres and other telomere-binding proteins, the TPP1 OB-fold domain is sufficient to recruit telomerase to a heterologous chromatin locus. Expression of a minimal TPP1 OB-fold inhibits telomere maintenance by blocking access of telomerase to its cognate binding site at telomeres. We identify amino acids required for the TPP1-telomerase interaction, including specific loop residues within the TPP1 OB-fold domain and individual residues within TERT, some of which are mutated in a subset of pulmonary fibrosis patients. These data define a potential interface for telomerase-TPP1 interaction required for telomere maintenance and implicate defective telomerase recruitment in telomerase-related disease.
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Affiliation(s)
- Franklin L Zhong
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
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26
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Sebastiano V, Maeder ML, Angstman JF, Haddad B, Khayter C, Yeo DT, Goodwin MJ, Hawkins JS, Ramirez CL, Batista LFZ, Artandi SE, Wernig M, Joung JK. In situ genetic correction of the sickle cell anemia mutation in human induced pluripotent stem cells using engineered zinc finger nucleases. Stem Cells 2012; 29:1717-26. [PMID: 21898685 DOI: 10.1002/stem.718] [Citation(s) in RCA: 264] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The combination of induced pluripotent stem cell (iPSC) technology and targeted gene modification by homologous recombination (HR) represents a promising new approach to generate genetically corrected, patient-derived cells that could be used for autologous transplantation therapies. This strategy has several potential advantages over conventional gene therapy including eliminating the need for immunosuppression, avoiding the risk of insertional mutagenesis by therapeutic vectors, and maintaining expression of the corrected gene by endogenous control elements rather than a constitutive promoter. However, gene targeting in human pluripotent cells has remained challenging and inefficient. Recently, engineered zinc finger nucleases (ZFNs) have been shown to substantially increase HR frequencies in human iPSCs, raising the prospect of using this technology to correct disease causing mutations. Here, we describe the generation of iPSC lines from sickle cell anemia patients and in situ correction of the disease causing mutation using three ZFN pairs made by the publicly available oligomerized pool engineering method (OPEN). Gene-corrected cells retained full pluripotency and a normal karyotype following removal of reprogramming factor and drug-resistance genes. By testing various conditions, we also demonstrated that HR events in human iPSCs can occur as far as 82 bps from a ZFN-induced break. Our approach delineates a roadmap for using ZFNs made by an open-source method to achieve efficient, transgene-free correction of monogenic disease mutations in patient-derived iPSCs. Our results provide an important proof of principle that ZFNs can be used to produce gene-corrected human iPSCs that could be used for therapeutic applications.
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Affiliation(s)
- Vittorio Sebastiano
- Department of Pathology, Institute for Stem Cell Biology & Regenerative Medicine, Stanford University School of Medicine, Stanford California, USA
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27
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Chu C, Qu K, Zhong FL, Artandi SE, Chang HY. Genomic maps of long noncoding RNA occupancy reveal principles of RNA-chromatin interactions. Mol Cell 2011; 44:667-78. [PMID: 21963238 DOI: 10.1016/j.molcel.2011.08.027] [Citation(s) in RCA: 934] [Impact Index Per Article: 71.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 08/29/2011] [Accepted: 08/31/2011] [Indexed: 01/22/2023]
Abstract
Long noncoding RNAs (lncRNAs) are key regulators of chromatin state, yet the nature and sites of RNA-chromatin interaction are mostly unknown. Here we introduce Chromatin Isolation by RNA Purification (ChIRP), where tiling oligonucleotides retrieve specific lncRNAs with bound protein and DNA sequences, which are enumerated by deep sequencing. ChIRP-seq of three lncRNAs reveal that RNA occupancy sites in the genome are focal, sequence-specific, and numerous. Drosophila roX2 RNA occupies male X-linked gene bodies with increasing tendency toward the 3' end, peaking at CES sites. Human telomerase RNA TERC occupies telomeres and Wnt pathway genes. HOTAIR lncRNA preferentially occupies a GA-rich DNA motif to nucleate broad domains of Polycomb occupancy and histone H3 lysine 27 trimethylation. HOTAIR occupancy occurs independently of EZH2, suggesting the order of RNA guidance of Polycomb occupancy. ChIRP-seq is generally applicable to illuminate the intersection of RNA and chromatin with newfound precision genome wide.
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Affiliation(s)
- Ci Chu
- Howard Hughes Medical Institute and Program in Epithelial Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
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28
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Zhong F, Savage SA, Shkreli M, Giri N, Jessop L, Myers T, Chen R, Alter BP, Artandi SE. Disruption of telomerase trafficking by TCAB1 mutation causes dyskeratosis congenita. Genes Dev 2011; 25:11-6. [PMID: 21205863 DOI: 10.1101/gad.2006411] [Citation(s) in RCA: 186] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Dyskeratosis congenita (DC) is a genetic disorder of defective tissue maintenance and cancer predisposition caused by short telomeres and impaired stem cell function. Telomerase mutations are thought to precipitate DC by reducing either the catalytic activity or the overall levels of the telomerase complex. However, the underlying genetic mutations and the mechanisms of telomere shortening remain unknown for as many as 50% of DC patients, who lack mutations in genes controlling telomere homeostasis. Here, we show that disruption of telomerase trafficking accounts for unknown cases of DC. We identify DC patients with missense mutations in TCAB1, a telomerase holoenzyme protein that facilitates trafficking of telomerase to Cajal bodies. Compound heterozygous mutations in TCAB1 disrupt telomerase localization to Cajal bodies, resulting in misdirection of telomerase RNA to nucleoli, which prevents telomerase from elongating telomeres. Our findings establish telomerase mislocalization as a novel cause of DC, and suggest that telomerase trafficking defects may contribute more broadly to the pathogenesis of telomere-related disease.
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Affiliation(s)
- Franklin Zhong
- Department of Medicine, Stanford University School of Medicine, Stanford, California 94305, USA
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29
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Sacco A, Mourkioti F, Tran R, Choi J, Llewellyn M, Kraft P, Shkreli M, Delp S, Pomerantz JH, Artandi SE, Blau HM. Short telomeres and stem cell exhaustion model Duchenne muscular dystrophy in mdx/mTR mice. Cell 2010; 143:1059-71. [PMID: 21145579 DOI: 10.1016/j.cell.2010.11.039] [Citation(s) in RCA: 367] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 09/18/2010] [Accepted: 11/02/2010] [Indexed: 01/10/2023]
Abstract
In Duchenne muscular dystrophy (DMD), dystrophin mutation leads to progressive lethal skeletal muscle degeneration. For unknown reasons, dystrophin deficiency does not recapitulate DMD in mice (mdx), which have mild skeletal muscle defects and potent regenerative capacity. We postulated that human DMD progression is a consequence of loss of functional muscle stem cells (MuSC), and the mild mouse mdx phenotype results from greater MuSC reserve fueled by longer telomeres. We report that mdx mice lacking the RNA component of telomerase (mdx/mTR) have shortened telomeres in muscle cells and severe muscular dystrophy that progressively worsens with age. Muscle wasting severity parallels a decline in MuSC regenerative capacity and is ameliorated histologically by transplantation of wild-type MuSC. These data show that DMD progression results, in part, from a cell-autonomous failure of MuSC to maintain the damage-repair cycle initiated by dystrophin deficiency. The essential role of MuSC function has therapeutic implications for DMD.
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Affiliation(s)
- Alessandra Sacco
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
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30
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Hong JY, Park JI, Cho K, Gu D, Ji H, Artandi SE, McCrea PD. Shared molecular mechanisms regulate multiple catenin proteins: canonical Wnt signals and components modulate p120-catenin isoform-1 and additional p120 subfamily members. J Cell Sci 2010; 123:4351-65. [PMID: 21098636 DOI: 10.1242/jcs.067199] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Wnt signaling pathways have fundamental roles in animal development and tumor progression. Here, employing Xenopus embryos and mammalian cell lines, we report that the degradation machinery of the canonical Wnt pathway modulates p120-catenin protein stability through mechanisms shared with those regulating β-catenin. For example, in common with β-catenin, exogenous expression of destruction complex components, such as GSK3β and axin, promotes degradation of p120-catenin. Again in parallel with β-catenin, reduction of canonical Wnt signals upon depletion of LRP5 and LRP6 results in p120-catenin degradation. At the primary sequence level, we resolved conserved GSK3β phosphorylation sites in the amino-terminal region of p120-catenin present exclusively in isoform-1. Point-mutagenesis of these residues inhibited the association of destruction complex components, such as those involved in ubiquitylation, resulting in stabilization of p120-catenin. Functionally, in line with predictions, p120 stabilization increased its signaling activity in the context of the p120-Kaiso pathway. Importantly, we found that two additional p120-catenin family members, ARVCF-catenin and δ-catenin, associate with axin and are degraded in its presence. Thus, as supported using gain- and loss-of-function approaches in embryo and cell line systems, canonical Wnt signals appear poised to have an impact upon a breadth of catenin biology in vertebrate development and, possibly, human cancers.
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Affiliation(s)
- Ji Yeon Hong
- Department of Biochemistry and Molecular Biology, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA
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31
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Abstract
Myriad genetic and epigenetic alterations are required to drive normal cells toward malignant transformation. These somatic events commandeer many signaling pathways that cooperate to endow aspiring cancer cells with a full range of biological capabilities needed to grow, disseminate and ultimately kill its host. Cancer genomes are highly rearranged and are characterized by complex translocations and regional copy number alterations that target loci harboring cancer-relevant genes. Efforts to uncover the underlying mechanisms driving genome instability in cancer have revealed a prominent role for telomeres. Telomeres are nucleoprotein structures that protect the ends of eukaryotic chromosomes and are particularly vulnerable due to progressive shortening during each round of DNA replication and, thus, a lifetime of tissue renewal places the organism at risk for increasing chromosomal instability. Indeed, telomere erosion has been documented in aging tissues and hyperproliferative disease states-conditions strongly associated with increased cancer risk. Telomere dysfunction can produce the opposing pathophysiological states of degenerative aging or cancer with the specific outcome dictated by the integrity of DNA damage checkpoint responses. In most advanced cancers, telomerase is reactivated and serves to maintain telomere length and emerging data have also documented the capacity of telomerase to directly regulate cancer-promoting pathways. This review covers the role of telomeres and telomerase in the biology of normal tissue stem/progenitor cells and in the development of cancer.
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Affiliation(s)
- Steven E Artandi
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA.
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32
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Abstract
Data from mouse models and from human cancers have supported the idea that telomere shortening leads to chromosomal instability and epithelial carcinogenesis. In this issue of Cancer Cell, Else et al. demonstrate that telomere uncapping-altering a protein that protects chromosome ends without shortening telomeres-also results in epithelial cancers.
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Affiliation(s)
- Luis F Z Batista
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
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33
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Abstract
Telomerase supports the proliferation of progenitor cells and tumor cells by adding telomere repeats to chromosome ends. The low abundance and restricted expression pattern of telomerase have limited our knowledge of this important enzyme. A new telomerase protein, TCAB1, sheds light on the pathway that governs telomerase holoenzyme assembly and function in vivo. TCAB1 is a component of active telomerase and is required for the telomerase holoenzyme to accumulate in Cajal bodies and to elongate telomeres. These findings provide important new insights into how telomerase functions in cancer and in stem cell biology.
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Affiliation(s)
- Andrew S Venteicher
- Department of Medicine, Stanford School of Medicine, Stanford, CA 94305, USA
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Venteicher AS, Abreu EB, Meng Z, McCann KE, Terns RM, Veenstra TD, Terns MP, Artandi SE. A human telomerase holoenzyme protein required for Cajal body localization and telomere synthesis. Science 2009; 323:644-8. [PMID: 19179534 DOI: 10.1126/science.1165357] [Citation(s) in RCA: 389] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Telomerase is a ribonucleoprotein (RNP) complex that synthesizes telomere repeats in tissue progenitor cells and cancer cells. Active human telomerase consists of at least three principal subunits, including the telomerase reverse transcriptase, the telomerase RNA (TERC), and dyskerin. Here, we identify a holoenzyme subunit, TCAB1 (telomerase Cajal body protein 1), that is notably enriched in Cajal bodies, nuclear sites of RNP processing that are important for telomerase function. TCAB1 associates with active telomerase enzyme, established telomerase components, and small Cajal body RNAs that are involved in modifying splicing RNAs. Depletion of TCAB1 by using RNA interference prevents TERC from associating with Cajal bodies, disrupts telomerase-telomere association, and abrogates telomere synthesis by telomerase. Thus, TCAB1 controls telomerase trafficking and is required for telomere synthesis in human cancer cells.
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Affiliation(s)
- Andrew S Venteicher
- Department of Medicine, Stanford School of Medicine, Stanford, CA 94305, USA
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35
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Gao Q, Reynolds GE, Wilcox A, Miller D, Cheung P, Artandi SE, Murnane JP. Telomerase-dependent and -independent chromosome healing in mouse embryonic stem cells. DNA Repair (Amst) 2008; 7:1233-49. [PMID: 18502190 DOI: 10.1016/j.dnarep.2008.04.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Revised: 04/01/2008] [Accepted: 04/03/2008] [Indexed: 01/04/2023]
Abstract
Telomeres play an important role in protecting the ends of chromosomes and preventing chromosome fusion. We have previously demonstrated that double-strand breaks near telomeres in mammalian cells result in either the addition of a new telomere at the site of the break, termed chromosome healing, or sister chromatid fusion that initiates chromosome instability. In the present study, we have investigated the role of telomerase in chromosome healing and the importance of chromosome healing in preventing chromosome instability. In embryonic stem cell lines that are wild type for the catalytic subunit of telomerase (TERT), chromosome healing at I-SceI-induced double-strand breaks near telomeres accounted for 22 of 35 rearrangements, with the new telomeres added directly at the site of the break in all but one instance. In contrast, in two TERT-knockout embryonic stem cell lines, chromosome healing accounted for only 1 of 62 rearrangements, with a 23 bp insertion at the site of the sole chromosome-healing event. However, in a third TERT-knockout embryonic stem cell line, 10PTKO-A, chromosome healing was a common event that accounted for 20 of 34 rearrangements. Although this chromosome healing also occurred at the I-SceI site, differences in the microhomology at the site of telomere addition demonstrated that the mechanism was distinct from that in wild-type embryonic stem cell lines. In addition, the newly added telomeres in 10PTKO-A shortened with time in culture, eventually resulting in either telomere elongation through a telomerase-independent mechanism or loss of the subtelomeric plasmid sequences entirely. The combined results demonstrate that chromosome healing can occur through both telomerase-dependent and -independent mechanisms, and that although both mechanisms can prevent degradation and sister chromatid fusion, neither mechanism is efficient enough to prevent sister chromatid fusion from occurring in many cells experiencing double-strand breaks near telomeres.
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Affiliation(s)
- Qing Gao
- Department of Radiation Oncology, University of California, San Francisco, CA 94103, USA
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36
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Venteicher AS, Meng Z, Mason PJ, Veenstra TD, Artandi SE. Identification of ATPases pontin and reptin as telomerase components essential for holoenzyme assembly. Cell 2008; 132:945-57. [PMID: 18358808 DOI: 10.1016/j.cell.2008.01.019] [Citation(s) in RCA: 260] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2007] [Revised: 11/29/2007] [Accepted: 01/09/2008] [Indexed: 11/27/2022]
Abstract
Telomerase is a multisubunit ribonucleoprotein (RNP) complex that adds telomere repeats to the ends of chromosomes. Three essential telomerase components have been identified thus far: the telomerase reverse transcriptase (TERT), the telomerase RNA component (TERC), and the TERC-binding protein dyskerin. Few other proteins are known to be required for human telomerase function, limiting our understanding of both telomerase regulation and mechanisms of telomerase action. Here, we identify the ATPases pontin and reptin as telomerase components through affinity purification of TERT from human cells. Pontin interacts directly with both TERT and dyskerin, and the amount of TERT bound to pontin and reptin peaks in S phase, evidence for cell-cycle-dependent regulation of TERT. Depletion of pontin and reptin markedly impairs telomerase RNP accumulation, indicating an essential role in telomerase assembly. These findings reveal an unanticipated requirement for additional enzymes in telomerase biogenesis and suggest alternative approaches for inhibiting telomerase in cancer.
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Affiliation(s)
- Andrew S Venteicher
- Department of Medicine, Stanford School of Medicine, Stanford, CA 94305, USA
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37
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Sarin KY, Artandi SE. Aging, graying and loss of melanocyte stem cells. ACTA ACUST UNITED AC 2008; 3:212-7. [PMID: 17917134 DOI: 10.1007/s12015-007-0028-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 02/04/2023]
Abstract
Hair graying is one of the prototypical signs of human aging. Maintenance of hair pigmentation is dependent on the presence and functionality of melanocytes, neural crest derived cells which synthesize pigment for growing hair. The melanocytes, themselves, are maintained by a small number of stem cells which reside in the bulge region of the hair follicle. The recent characterization of the melanocyte lineage during aging has significantly accelerated our understanding of how age-related changes in the melanocyte stem cell compartment contribute to hair graying. This review will discuss our current understanding of hair graying, drawing on evidence from human and mouse studies, and consider the contribution of melanocyte stem cells to this process. Furthermore, using the melanocyte lineage as an example, it will discuss common theories of tissue and stem cell aging.
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Affiliation(s)
- Kavita Y Sarin
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
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Choi J, Southworth LK, Sarin KY, Venteicher AS, Ma W, Chang W, Cheung P, Jun S, Artandi MK, Shah N, Kim SK, Artandi SE. TERT promotes epithelial proliferation through transcriptional control of a Myc- and Wnt-related developmental program. PLoS Genet 2007; 4:e10. [PMID: 18208333 PMCID: PMC2211538 DOI: 10.1371/journal.pgen.0040010] [Citation(s) in RCA: 245] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Accepted: 12/06/2007] [Indexed: 12/17/2022] Open
Abstract
Telomerase serves a critical role in stem cell function and tissue homeostasis. This role depends on its ability to synthesize telomere repeats in a manner dependent on the reverse transcriptase (RT) function of its protein component telomerase RT (TERT), as well as on a novel pathway whose mechanism is poorly understood. Here, we use a TERT mutant lacking RT function (TERTci) to study the mechanism of TERT action in mammalian skin, an ideal tissue for studying progenitor cell biology. We show that TERTci retains the full activities of wild-type TERT in enhancing keratinocyte proliferation in skin and in activating resting hair follicle stem cells, which triggers initiation of a new hair follicle growth phase and promotes hair synthesis. To understand the nature of this RT-independent function for TERT, we studied the genome-wide transcriptional response to acute changes in TERT levels in mouse skin. We find that TERT facilitates activation of progenitor cells in the skin and hair follicle by triggering a rapid change in gene expression that significantly overlaps the program controlling natural hair follicle cycling in wild-type mice. Statistical comparisons to other microarray gene sets using pattern-matching algorithms revealed that the TERT transcriptional response strongly resembles those mediated by Myc and Wnt, two proteins intimately associated with stem cell function and cancer. These data show that TERT controls tissue progenitor cells via transcriptional regulation of a developmental program converging on the Myc and Wnt pathways. Stem cells and progenitor cells within a tissue are required to maintain tissue homeostasis and to repair tissues after injury by giving rise to differentiated daughter cells. Many progenitor cells express telomerase, a reverse transcriptase enzyme that adds DNA repeats to telomeres, the protective structures that cap chromosome ends. Telomere addition by telomerase is important for normal progenitor cell function and is crucial for enabling cancer cells to divide an unlimited number of times. In addition to its telomere-lengthening function, telomerase reverse transcriptase (TERT) can directly activate quiescent epidermal stem cells. However, the mechanism underlying this novel function for TERT is still not understood. In this study, we demonstrate that the catalytic activity of TERT is dispensable for its ability to activate tissue progenitor cells in vivo. Furthermore, using gene microarrays, we show that TERT controls a developmental program that overlaps the natural transcriptional program of hair follicle cycling in mouse skin. Using pattern-matching algorithms, we find that the TERT-controlled genetic program significantly resembles programs regulated by Myc and Wnt, two pathways critical for stem cell function and tumorigenesis. This paper reveals critical new insights into novel mechanisms of non-telomerase functions of TERT, identifying TERT as a developmental regulator linked to control of transcriptional responses.
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Affiliation(s)
- Jinkuk Choi
- Department of Medicine, Stanford School of Medicine, Stanford, California, United States of America
- Cancer Biology Program, Stanford School of Medicine, Stanford, California, United States of America
| | - Lucinda K Southworth
- Department of Genetics, Stanford School of Medicine, Stanford, California, United States of America
- Biomedical Informatics Program, Stanford School of Medicine, Stanford, California, United States of America
| | - Kavita Y Sarin
- Department of Medicine, Stanford School of Medicine, Stanford, California, United States of America
- Department of Genetics, Stanford School of Medicine, Stanford, California, United States of America
| | - Andrew S Venteicher
- Department of Medicine, Stanford School of Medicine, Stanford, California, United States of America
| | - Wenxiu Ma
- Department of Computer Science, Stanford University, Stanford, California, United States of America
| | - Woody Chang
- Department of Medicine, Stanford School of Medicine, Stanford, California, United States of America
| | - Peggie Cheung
- Department of Medicine, Stanford School of Medicine, Stanford, California, United States of America
| | - Sohee Jun
- Department of Medicine, Stanford School of Medicine, Stanford, California, United States of America
| | - Maja K Artandi
- Department of Medicine, Stanford School of Medicine, Stanford, California, United States of America
| | - Naman Shah
- Department of Medicine, Stanford School of Medicine, Stanford, California, United States of America
| | - Stuart K Kim
- Department of Genetics, Stanford School of Medicine, Stanford, California, United States of America
- Department of Developmental Biology, Stanford School of Medicine, Stanford, California, United States of America
| | - Steven E Artandi
- Department of Medicine, Stanford School of Medicine, Stanford, California, United States of America
- Cancer Biology Program, Stanford School of Medicine, Stanford, California, United States of America
- * To whom correspondence should be addressed. E-mail:
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39
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Maser RS, Wong KK, Sahin E, Xia H, Naylor M, Hedberg HM, Artandi SE, DePinho RA. DNA-dependent protein kinase catalytic subunit is not required for dysfunctional telomere fusion and checkpoint response in the telomerase-deficient mouse. Mol Cell Biol 2006; 27:2253-65. [PMID: 17145779 PMCID: PMC1820500 DOI: 10.1128/mcb.01354-06] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Telomeres are key structural elements for the protection and maintenance of linear chromosomes, and they function to prevent recognition of chromosomal ends as DNA double-stranded breaks. Loss of telomere capping function brought about by telomerase deficiency and gradual erosion of telomere ends or by experimental disruption of higher-order telomere structure culminates in the fusion of defective telomeres and/or the activation of DNA damage checkpoints. Previous work has implicated the nonhomologous end-joining (NHEJ) DNA repair pathway as a critical mediator of these biological processes. Here, employing the telomerase-deficient mouse model, we tested whether the NHEJ component DNA-dependent protein kinase catalytic subunit (DNA-PKcs) was required for fusion of eroded/dysfunctional telomere ends and the telomere checkpoint responses. In late-generation mTerc(-/-) DNA-PKcs(-/-) cells and tissues, chromosomal end-to-end fusions and anaphase bridges were readily evident. Notably, nullizygosity for DNA Ligase4 (Lig4)--an additional crucial NHEJ component--was also permissive for chromosome fusions in mTerc(-/-) cells, indicating that, in contrast to results seen with experimental disruption of telomere structure, telomere dysfunction in the context of gradual telomere erosion can engage additional DNA repair pathways. Furthermore, we found that DNA-PKcs deficiency does not reduce apoptosis, tissue atrophy, or p53 activation in late-generation mTerc(-/-) tissues but rather moderately exacerbates germ cell apoptosis and testicular degeneration. Thus, our studies indicate that the NHEJ components, DNA-PKcs and Lig4, are not required for fusion of critically shortened telomeric ends and that DNA-PKcs is not required for sensing and executing the telomere checkpoint response, findings consistent with the consensus view of the limited role of DNA-PKcs in DNA damage signaling in general.
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Affiliation(s)
- Richard S Maser
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
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40
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41
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Middleman EJ, Choi J, Venteicher AS, Cheung P, Artandi SE. Regulation of cellular immortalization and steady-state levels of the telomerase reverse transcriptase through its carboxy-terminal domain. Mol Cell Biol 2006; 26:2146-59. [PMID: 16507993 PMCID: PMC1430280 DOI: 10.1128/mcb.26.6.2146-2159.2006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Telomerase maintains cell viability and chromosomal stability through the addition of telomere repeats to chromosome ends. The reactivation of telomerase through the upregulation of TERT, the telomerase protein subunit, is an important step during cancer development, yet TERT protein function and regulation remain incompletely understood. Despite its close sequence similarity to human TERT (hTERT), we find that mouse TERT (mTERT) does not immortalize primary human fibroblasts. Here we exploit these differences in activity to understand TERT protein function by creating chimeric mouse-human TERT proteins. Through the analysis of these chimeric TERT proteins, we find that sequences in the human carboxy-terminal domain are critical for telomere maintenance in human fibroblasts. The substitution of the human carboxy-terminal sequences into the mouse TERT protein is sufficient to confer immortalization and maintenance of telomere length and function. Strikingly, we find that hTERT protein accumulates to markedly higher levels than does mTERT protein and that the sequences governing this difference in protein regulation also reside in the carboxy-terminal domain. These elevated protein levels, which are characteristic of hTERT, are necessary but not sufficient for telomere maintenance because stabilized mTERT mutants cannot immortalize human cells. Thus, the TERT carboxy terminus contains sequences that regulate TERT protein levels and determinants that are required for productive action on telomere ends.
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Affiliation(s)
- Elaine J Middleman
- Department of Medicine, Division of Hematology, Stanford University, 269 Campus Drive, Stanford, CA 94305-5156, USA
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42
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Abstract
Telomerase, the enzyme that elongates our telomeres, is crucial for cancer development based on extensive analyses of human cells, human cancers, and mouse models. New data now suggest that a viral telomerase RNA gene encoded by Marek's disease virus (MDV), an oncogenic herpesvirus of chickens, promotes tumor formation. These findings highlight the importance of telomerase in cancer and raise new questions regarding the mechanisms by which the telomerase RNA component supports tumorigenesis.
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Affiliation(s)
- Steven E Artandi
- Department of Medicine, Division of Hematology, and Cancer Biology Program, Stanford School of Medicine, Stanford, CA 94305, USA.
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43
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Sarin KY, Cheung P, Gilison D, Lee E, Tennen RI, Wang E, Artandi MK, Oro AE, Artandi SE. Conditional telomerase induction causes proliferation of hair follicle stem cells. Nature 2005; 436:1048-52. [PMID: 16107853 PMCID: PMC1361120 DOI: 10.1038/nature03836] [Citation(s) in RCA: 315] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2005] [Accepted: 05/06/2005] [Indexed: 12/17/2022]
Abstract
TERT, the protein component of telomerase, serves to maintain telomere function through the de novo addition of telomere repeats to chromosome ends, and is reactivated in 90% of human cancers. In normal tissues, TERT is expressed in stem cells and in progenitor cells, but its role in these compartments is not fully understood. Here we show that conditional transgenic induction of TERT in mouse skin epithelium causes a rapid transition from telogen (the resting phase of the hair follicle cycle) to anagen (the active phase), thereby facilitating robust hair growth. TERT overexpression promotes this developmental transition by causing proliferation of quiescent, multipotent stem cells in the hair follicle bulge region. This new function for TERT does not require the telomerase RNA component, which encodes the template for telomere addition, and therefore operates through a mechanism independent of its activity in synthesizing telomere repeats. These data indicate that, in addition to its established role in extending telomeres, TERT can promote proliferation of resting stem cells through a non-canonical pathway.
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Affiliation(s)
- Kavita Y. Sarin
- Department of Medicine, Division of Hematology, Stanford School of Medicine, Stanford, CA 94305
- Department of Genetics, Stanford School of Medicine, Stanford, CA 94305
| | - Peggie Cheung
- Department of Medicine, Division of Hematology, Stanford School of Medicine, Stanford, CA 94305
| | - Daniel Gilison
- Department of Medicine, Division of Hematology, Stanford School of Medicine, Stanford, CA 94305
- Department of Genetics, Stanford School of Medicine, Stanford, CA 94305
| | - Eunice Lee
- Department of Medicine, Division of Hematology, Stanford School of Medicine, Stanford, CA 94305
| | - Ruth I. Tennen
- Department of Medicine, Division of Hematology, Stanford School of Medicine, Stanford, CA 94305
- Cancer Biology Program, Stanford School of Medicine, Stanford, CA 94305
| | - Estee Wang
- Department of Medicine, Division of Hematology, Stanford School of Medicine, Stanford, CA 94305
| | - Maja K. Artandi
- Department of Medicine, Division of Hematology, Stanford School of Medicine, Stanford, CA 94305
| | - Anthony E. Oro
- Cancer Biology Program, Stanford School of Medicine, Stanford, CA 94305
- Department of Dermatology, Stanford School of Medicine, Stanford, CA 94305
| | - Steven E. Artandi
- Department of Medicine, Division of Hematology, Stanford School of Medicine, Stanford, CA 94305
- Cancer Biology Program, Stanford School of Medicine, Stanford, CA 94305
- Correspondence and requests should be addressed to S.E.A. ()
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Abstract
The ends of eukaryotic chromosomes are protected by specialized structures termed telomeres that serve in part to prevent the chromosome end from activating a DNA damage response. However, this important function for telomeres in chromosome end protection can be lost as telomeres shorten with cell division in culture or in self-renewing tissues with advancing age. Impaired telomere function leads to induction of a DNA damage response and activation of the tumor suppressor protein p53. p53 serves a critical role in enforcing both senescence and apoptotic responses to dysfunctional telomeres. Loss of p53 creates a permissive environment in which critically short telomeres are inappropriately joined to generate chromosomal end-to-end fusions. These fused chromosomes result in cycles of chromosome fusion-bridge-breakage, which can fuel cancer initiation, especially in epithelial tissues, by facilitating changes in gene copy number.
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Affiliation(s)
- Steven E Artandi
- Department of Medicine, Division of Hematology and Cancer Biology Program, Stanford University School of Medicine, Stanford, CA 94305, USA.
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45
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Abstract
Telomerase - an enzyme that endows cells with unlimited proliferative potential - is differentially expressed in cancer cells and in normal cells. Although most primary human cells lack telomerase, the enzyme is upregulated in more than 90% of invasive breast cancers. As a result, much of breast cancer development occurs before telomerase is reactivated during a critical transition from a telomerase-negative to a telomerase-positive state. During this transition, the telomere shortening that accompanies cell division may either prevent or facilitate tumorigenesis by activating checkpoints and impairing chromosomal stability. In mature cancers, telomerase probably serves a crucial role in tumor progression and maintenance by stabilizing telomeres and supporting the immortal growth of breast cancer cells.
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Affiliation(s)
- Steven E Artandi
- Department of Medicine/Hematology, Cancer Biology Program, Stanford University School of Medicine, Stanford, California, USA.
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46
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Abstract
Telomere dysfunction and associated fusion-breakage in the mouse encourages epithelial carcinogenesis and a more humanized genomic profile that includes nonreciprocal translocations (NRTs). Here, array comparative genomic hybridization was used to determine the pathogenic significance of NRTs and to determine whether telomere dysfunction also drives amplifications and deletions of cancer-relevant loci. Compared to tumors arising in mice with intact telomeres, tumors with telomere dysfunction possessed higher levels of genomic instability and showed numerous amplifications and deletions in regions syntenic to human cancer hotspots. These observations suggest that telomere-based crisis provides a mechanism of chromosomal instability, including regional amplifications and deletions, that drives carcinogenesis. This model provides a platform for discovery of genes responsible for the major cancers affecting aged humans.
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Affiliation(s)
- Rónán C O'Hagan
- Department of Adult Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA
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47
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Artandi SE, Alson S, Tietze MK, Sharpless NE, Ye S, Greenberg RA, Castrillon DH, Horner JW, Weiler SR, Carrasco RD, DePinho RA. Constitutive telomerase expression promotes mammary carcinomas in aging mice. Proc Natl Acad Sci U S A 2002; 99:8191-6. [PMID: 12034875 PMCID: PMC123043 DOI: 10.1073/pnas.112515399] [Citation(s) in RCA: 249] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Telomerase is up-regulated in the vast majority of human cancers and serves to halt the progressive telomere shortening that ultimately blocks would-be cancer cells from achieving a full malignant phenotype. In contrast to humans, the laboratory mouse possesses long telomeres and, even in early generation telomerase-deficient mice, the level of telomere reserve is sufficient to avert telomere-based checkpoint responses and to permit full malignant progression. These features in the mouse provide an opportunity to determine whether enforced high-level telomerase activity can serve functions that extend beyond its ability to sustain telomere length and function. Here, we report the generation and characterization of transgenic mice that express the catalytic subunit of telomerase (mTERT) at high levels in a broad variety of tissues. Expression of mTERT conferred increased telomerase enzymatic activity in several tissues, including mammary gland, splenocytes, and cultured mouse embryonic fibroblasts. In mouse embryonic fibroblasts, mTERT overexpression extended telomere lengths but did not prevent culture-induced replicative arrest, thus reinforcing the view that this phenomenon is not related to occult telomere shortening. Robust telomerase activity, however, was associated with the spontaneous development of mammary intraepithelial neoplasia and invasive mammary carcinomas in a significant proportion of aged females. These data indicate that enforced mTERT expression can promote the development of spontaneous cancers even in the setting of ample telomere reserve.
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Affiliation(s)
- Steven E Artandi
- Department of Adult Oncology, Dana-Farber Cancer Institute, Harvard Medical School, 44 Binney Street (M413), Boston, MA 02115, USA
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48
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Abstract
Cell division in the absence of telomerase leads to telomere shortening that can activate checkpoint responses and impair chromosomal stability. The absence of telomerase in primary human cells and its near universal reactivation in human cancers has highlighted the importance of telomere shortening and telomerase reactivation during tumor development. Data from telomerase-deficient mouse models of cancer have indicated that telomere shortening can exert profoundly different influences on cell fates in developing cancers, limiting tumorigenesis by enhancing cell death or facilitating carcinogenesis by compromising chromosomal stability. These alternate fates depend on the integrity of the p53 pathway and on cell type.
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Affiliation(s)
- Steven E Artandi
- Dept of Hematology, Cancer Biology Program, Stanford University School of Medicine, Stanford, CA 94304, USA.
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49
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Wong KK, Chang S, Weiler SR, Ganesan S, Chaudhuri J, Zhu C, Artandi SE, Rudolph KL, Gottlieb GJ, Chin L, Alt FW, DePinho RA. Telomere dysfunction impairs DNA repair and enhances sensitivity to ionizing radiation. Nat Genet 2000; 26:85-8. [PMID: 10973255 DOI: 10.1038/79232] [Citation(s) in RCA: 247] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Telomeres are specialized nucleoprotein complexes that serve as protective caps of linear eukaryotic chromosomes. Loss of telomere function is associated with rampant genetic instability and loss of cellular viability and renewal potential. The telomere also participates in processes of chromosomal repair, as evidenced by the 'capture' or de novo synthesis of telomere repeats at double-stranded breaks and by the capacity of yeast telomeres to serve as repositories of essential components of the DNA repair machinery, particularly those involved in non-homologous end-joining (NHEJ). Here we used the telomerase-deficient mouse, null for the essential telomerase RNA gene (Terc), to assess the role of telomerase and telomere function on the cellular and organismal response to ionizing radiation. Although the loss of telomerase activity per se had no discernable impact on the response to ionizing radiation, the emergence of telomere dysfunction in late-generation Terc-/- mice imparted a radiosensitivity syndrome associated with accelerated mortality. On the cellular level, the gastrointestinal crypt stem cells and primary thymocytes showed increased rates of apoptosis, and mouse embryonic fibroblasts (MEFs) showed diminished dose-dependent clonogenic survival. The radiosensitivity of telomere dysfunctional cells correlated with delayed DNA break repair kinetics, persistent chromosomal breaks and cytogenetic profiles characterized by complex chromosomal aberrations and massive fragmentation. Our findings establish a intimate relationship between functionally intact telomeres and the genomic, cellular and organismal response to ionizing radiation.
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Affiliation(s)
- K K Wong
- Department of Adult Oncology, Dana Farber Cancer Institute, Boston, Massachusetts, USA
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50
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Artandi SE, Chang S, Lee SL, Alson S, Gottlieb GJ, Chin L, DePinho RA. Telomere dysfunction promotes non-reciprocal translocations and epithelial cancers in mice. Nature 2000; 406:641-5. [PMID: 10949306 DOI: 10.1038/35020592] [Citation(s) in RCA: 790] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Aged humans sustain a high rate of epithelial cancers such as carcinomas of the breast and colon, whereas mice carrying common tumour suppressor gene mutations typically develop soft tissue sarcomas and lymphomas. Among the many factors that may contribute to this species variance are differences in telomere length and regulation. Telomeres comprise the nucleoprotein complexes that cap the ends of eukaryotic chromosomes and are maintained by the reverse transcriptase, telomerase. In human cells, insufficient levels of telomerase lead to telomere attrition with cell division in culture and possibly with ageing and tumorigenesis in vivo. In contrast, critical reduction in telomere length is not observed in the mouse owing to promiscuous telomerase expression and long telomeres. Here we provide evidence that telomere attrition in ageing telomerase-deficient p53 mutant mice promotes the development of epithelial cancers by a process of fusion-bridge breakage that leads to the formation of complex non-reciprocal translocations--a classical cytogenetic feature of human carcinomas. Our data suggest a model in which telomere dysfunction brought about by continual epithelial renewal during life generates the massive ploidy changes associated with the development of epithelial cancers.
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MESH Headings
- Adenocarcinoma/enzymology
- Adenocarcinoma/genetics
- Aging/genetics
- Animals
- Disease Models, Animal
- Female
- Genes, p53
- Humans
- Karyotyping
- Lymphoma/enzymology
- Lymphoma/genetics
- Male
- Mammary Neoplasms, Experimental/enzymology
- Mammary Neoplasms, Experimental/genetics
- Mice
- Mutation
- Neoplasms, Glandular and Epithelial/enzymology
- Neoplasms, Glandular and Epithelial/genetics
- Neoplasms, Glandular and Epithelial/pathology
- Sarcoma, Experimental/enzymology
- Sarcoma, Experimental/genetics
- Telomerase/deficiency
- Telomerase/genetics
- Telomerase/metabolism
- Telomere
- Translocation, Genetic
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Affiliation(s)
- S E Artandi
- Department of Adult Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA
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