1
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Crowley C, Ekpo EU, Carey BW, Joyce S, Kennedy C, Grey T, Duffy B, Kavanagh R, James K, Moloney F, Normoyle B, Moore N, Chopra R, O'Driscoll JC, McEntee MF, Maher MM, O' Connor OJ. Radiation dose tracking in computed tomography: Red alerts and feedback. Implementing a radiation dose alert system in CT. Radiography (Lond) 2020; 27:67-74. [PMID: 32693990 DOI: 10.1016/j.radi.2020.06.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [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: 03/30/2020] [Revised: 06/05/2020] [Accepted: 06/08/2020] [Indexed: 01/03/2023]
Abstract
INTRODUCTION This study investigates instances of elevated radiation dose on a radiation tracking system to determine their aetiologies. It aimed to investigate the impact of radiographer feedback on these alerts. METHODS Over two six-month periods 11,298 CT examinations were assessed using DoseWatch. Red alerts (dose length products twice the median) were identified and two independent reviewers established whether alerts were true (unjustifiable) or false (justifiable). During the second time period radiographers used a feedback tool to state the cause of the alert. A Chi-Square test was used to assess whether red alert incidence decreased following the implementation of radiographer feedback. RESULTS There were 206 and 357 alerts during the first and second time periods, respectively. These occurred commonly with CT pulmonary angiography, brain, and body examinations. Procedural documentation errors and patient size accounted for 57% and 43% of false alerts, respectively. Radiographer feedback was provided for 17% of studies; this was not associated with a significant change in the number of alerts, but the number of true alerts declined (from 7 to 3) (χ2 = 4.14; p = 0.04). CONCLUSION Procedural documentation errors as well as patient-related factors are associated with false alerts in DoseWatch. Implementation of a radiographer feedback tool reduced true alerts. IMPLICATIONS FOR PRACTICE The implementation of a radiographer feedback tool reduced the rate of true dose alerts. Low uptake with dose alert systems is an issue; the workflow needs to be considered to address this.
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Affiliation(s)
- C Crowley
- Department of Radiology, Cork University Hospital, Wilton, Cork, T12 DC4A, Ireland
| | - E U Ekpo
- Discipline of Medical Radiation Sciences, Faculty of Health Sciences, The University of Sydney, Lidcombe, New South Wales, 2141, Australia
| | - B W Carey
- Department of Radiology, Cork University Hospital, Wilton, Cork, T12 DC4A, Ireland; Department of Radiology, School of Medicine, University College Cork, College Road, Cork, Ireland
| | - S Joyce
- Department of Radiology, School of Medicine, University College Cork, College Road, Cork, Ireland.
| | - C Kennedy
- Department of Radiology, School of Medicine, University College Cork, College Road, Cork, Ireland
| | - T Grey
- Department of Radiology, School of Medicine, University College Cork, College Road, Cork, Ireland
| | - B Duffy
- Department of Radiology, School of Medicine, University College Cork, College Road, Cork, Ireland
| | - R Kavanagh
- Department of Radiology, School of Medicine, University College Cork, College Road, Cork, Ireland
| | - K James
- Department of Radiology, Cork University Hospital, Wilton, Cork, T12 DC4A, Ireland; Department of Radiology, School of Medicine, University College Cork, College Road, Cork, Ireland
| | - F Moloney
- Department of Radiology, Cork University Hospital, Wilton, Cork, T12 DC4A, Ireland; Department of Radiology, School of Medicine, University College Cork, College Road, Cork, Ireland
| | - B Normoyle
- Department of Radiography, Cork University Hospital, Wilton, Cork, T12 DC4A, Ireland
| | - N Moore
- Discipline of Diagnostic Radiography, School of Medicine, University College Cork, College Road, Cork, Ireland
| | - R Chopra
- Department of Radiography, Cork University Hospital, Wilton, Cork, T12 DC4A, Ireland
| | - J C O'Driscoll
- Discipline of Diagnostic Radiography, School of Medicine, University College Cork, College Road, Cork, Ireland
| | - M F McEntee
- Discipline of Diagnostic Radiography, School of Medicine, University College Cork, College Road, Cork, Ireland
| | - M M Maher
- Department of Radiology, Cork University Hospital, Wilton, Cork, T12 DC4A, Ireland; Department of Radiology, School of Medicine, University College Cork, College Road, Cork, Ireland
| | - O J O' Connor
- Department of Radiology, Cork University Hospital, Wilton, Cork, T12 DC4A, Ireland; Department of Radiology, School of Medicine, University College Cork, College Road, Cork, Ireland
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2
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Abstract
Most rapidly proliferating mammalian cells rely on the oxidation of exogenous glutamine to support cell proliferation. We previously found that culture of mouse embryonic stem cells (ESCs) in the presence of inhibitors against MEK and GSK3β to maintain pluripotency reduces cellular reliance on glutamine for tricarboxylic acid (TCA) cycle anaplerosis, enabling ESCs to proliferate in the absence of exogenous glutamine. Here we show that reduced dependence on exogenous glutamine is a generalizable feature of pluripotent stem cells. Enhancing self-renewal, through either overexpression of pluripotency-associated transcription factors or altered signal transduction, decreases the utilization of glutamine-derived carbons in the TCA cycle. As a result, cells with the highest potential for self-renewal can be enriched by transient culture in glutamine-deficient media. During pluripotent cell culture or reprogramming to pluripotency, transient glutamine withdrawal selectively leads to the elimination of non-pluripotent cells. These data reveal that reduced dependence on glutamine anaplerosis is an inherent feature of self-renewing pluripotent stem cells and reveal a simple, non-invasive mechanism to select for mouse and human pluripotent stem cells within a heterogeneous population during both ESC passage and induced pluripotent cell reprogramming.
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Affiliation(s)
- Santosha A. Vardhana
- Cancer Biology and Genetics Program, Memorial Sloan
Kettering Cancer Center, New York, New York, USA
- Center for Epigenetics Research, Memorial Sloan Kettering
Cancer Center, New York, New York, USA
| | - Paige K. Arnold
- Center for Epigenetics Research, Memorial Sloan Kettering
Cancer Center, New York, New York, USA
- Cell Biology Program, Memorial Sloan Kettering Cancer
Center, New York, New York, USA
- Louis V. Gerstner, Jr., Graduate School of Biomedical
Sciences, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Bess P. Rosen
- Developmental Biology Program, Memorial Sloan Kettering
Cancer Center, New York, New York, USA
| | - Yanyang Chen
- Center for Epigenetics Research, Memorial Sloan Kettering
Cancer Center, New York, New York, USA
- Cell Biology Program, Memorial Sloan Kettering Cancer
Center, New York, New York, USA
| | - Bryce W. Carey
- Laboratory of Chromatin Biology and Epigenetics, The
Rockefeller University, New York, New York, USA
| | - Danwei Huangfu
- Developmental Biology Program, Memorial Sloan Kettering
Cancer Center, New York, New York, USA
| | - Carlos Carmona-Fontaine
- Center for Genomics & Systems Biology, Department of
Biology, New York University, New York, New York, USA
| | - Craig B. Thompson
- Cancer Biology and Genetics Program, Memorial Sloan
Kettering Cancer Center, New York, New York, USA
- Center for Epigenetics Research, Memorial Sloan Kettering
Cancer Center, New York, New York, USA
| | - Lydia W.S. Finley
- Center for Epigenetics Research, Memorial Sloan Kettering
Cancer Center, New York, New York, USA
- Cell Biology Program, Memorial Sloan Kettering Cancer
Center, New York, New York, USA
- Correspondence should be addressed to L.W.S.F.
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3
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Finley LWS, Vardhana SA, Carey BW, Alonso-Curbelo D, Koche R, Chen Y, Wen D, King B, Radler MR, Rafii S, Lowe SW, Allis CD, Thompson CB. Pluripotency transcription factors and Tet1/2 maintain Brd4-independent stem cell identity. Nat Cell Biol 2018; 20:565-574. [PMID: 29662175 PMCID: PMC5937285 DOI: 10.1038/s41556-018-0086-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [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: 07/27/2017] [Accepted: 03/15/2018] [Indexed: 12/22/2022]
Abstract
A robust network of transcription factors and an open chromatin landscape are hallmarks of the naïve pluripotent state. Recently, the acetyllysine reader Brd4 has been implicated in stem cell maintenance, but the relative contribution of Brd4 to pluripotency remains unclear. Here we show that Brd4 is dispensable for self-renewal and pluripotency of embryonic stem cells (ESCs). When maintained in their ground state, ESCs retain transcription factor binding and chromatin accessibility independent of Brd4 function or expression. In metastable ESCs, Brd4 independence can be achieved by increased expression of pluripotency transcription factors including STAT3, Nanog or Klf4 so long as the DNA methylcytosine oxidases, Tet1 and Tet2, are present. These data reveal that Brd4 is not essential for ESC self-renewal. Rather, the levels of pluripotency transcription factor abundance and Tet1/2 function determine the extent to which bromodomain recognition of protein acetylation contributes to the maintenance of gene expression and cell identity.
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Affiliation(s)
- Lydia W S Finley
- Cell Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.,Center for Epigenetics Research, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Santosha A Vardhana
- Center for Epigenetics Research, Memorial Sloan Kettering Cancer Center, New York, NY, USA.,Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Bryce W Carey
- Laboratory of Chromatin Biology and Epigenetics, The Rockefeller University, New York, NY, USA
| | - Direna Alonso-Curbelo
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Richard Koche
- Center for Epigenetics Research, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Yanyang Chen
- Cell Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.,Center for Epigenetics Research, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Duancheng Wen
- Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medical College, New York, NY, USA
| | - Bryan King
- Center for Epigenetics Research, Memorial Sloan Kettering Cancer Center, New York, NY, USA.,Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Megan R Radler
- Center for Epigenetics Research, Memorial Sloan Kettering Cancer Center, New York, NY, USA.,Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Shahin Rafii
- Ansary Stem Cell Institute and Department of Medicine, Weill Cornell Medical College, New York, NY, USA
| | - Scott W Lowe
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - C David Allis
- Laboratory of Chromatin Biology and Epigenetics, The Rockefeller University, New York, NY, USA.
| | - Craig B Thompson
- Center for Epigenetics Research, Memorial Sloan Kettering Cancer Center, New York, NY, USA. .,Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
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Carey BW, Finley LWS, Cross JR, Allis CD, Thompson CB. Intracellular α-ketoglutarate maintains the pluripotency of embryonic stem cells. Nature 2014; 518:413-6. [PMID: 25487152 PMCID: PMC4336218 DOI: 10.1038/nature13981] [Citation(s) in RCA: 679] [Impact Index Per Article: 67.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 10/20/2014] [Indexed: 12/18/2022]
Abstract
The role of cellular metabolism in regulating cell proliferation and differentiation remains poorly understood. For example, most mammalian cells cannot proliferate without exogenous glutamine supplementation even though glutamine is a non-essential amino acid. Here we show that mouse embryonic stem (ES) cells grown under conditions that maintain naive pluripotency are capable of proliferation in the absence of exogenous glutamine. Despite this, ES cells consume high levels of exogenous glutamine when the metabolite is available. In comparison to more differentiated cells, naive ES cells utilize both glucose and glutamine catabolism to maintain a high level of intracellular α-ketoglutarate (αKG). Consequently, naive ES cells exhibit an elevated αKG to succinate ratio that promotes histone/DNA demethylation and maintains pluripotency. Direct manipulation of the intracellular αKG/succinate ratio is sufficient to regulate multiple chromatin modifications, including H3K27me3 and ten-eleven translocation (Tet)-dependent DNA demethylation, which contribute to the regulation of pluripotency-associated gene expression. In vitro, supplementation with cell-permeable αKG directly supports ES-cell self-renewal while cell-permeable succinate promotes differentiation. This work reveals that intracellular αKG/succinate levels can contribute to the maintenance of cellular identity and have a mechanistic role in the transcriptional and epigenetic state of stem cells.
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Affiliation(s)
- Bryce W Carey
- Laboratory of Chromatin Biology and Epigenetics, The Rockefeller University, New York, New York 10065, USA
| | - Lydia W S Finley
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Justin R Cross
- Donald B. and Catherine C. Marron Cancer Metabolism Center, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - C David Allis
- Laboratory of Chromatin Biology and Epigenetics, The Rockefeller University, New York, New York 10065, USA
| | - Craig B Thompson
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
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5
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Carey BW, Markoulaki S, Hanna JH, Faddah DA, Buganim Y, Kim J, Ganz K, Steine EJ, Cassady JP, Creyghton MP, Welstead GG, Gao Q, Jaenisch R. Reprogramming factor stoichiometry influences the epigenetic state and biological properties of induced pluripotent stem cells. Cell Stem Cell 2012; 9:588-98. [PMID: 22136932 DOI: 10.1016/j.stem.2011.11.003] [Citation(s) in RCA: 257] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Revised: 11/01/2011] [Accepted: 11/08/2011] [Indexed: 12/12/2022]
Abstract
We compared two genetically highly defined transgenic systems to identify parameters affecting reprogramming of somatic cells to a pluripotent state. Our results demonstrate that the level and stoichiometry of reprogramming factors during the reprogramming process strongly influence the resulting pluripotency of iPS cells. High expression of Oct4 and Klf4 combined with lower expression of c-Myc and Sox2 produced iPS cells that efficiently generated "all-iPSC mice" by tetraploid (4n) complementation, maintained normal imprinting at the Dlk1-Dio3 locus, and did not create mice with tumors. Loss of imprinting (LOI) at the Dlk1-Dio3 locus did not strictly correlate with reduced pluripotency though the efficiency of generating "all-iPSC mice" was diminished. Our data indicate that stoichiometry of reprogramming factors can influence epigenetic and biological properties of iPS cells. This concept complicates efforts to define a "generic" epigenetic state of iPSCs and ESCs and should be considered when comparing different iPS and ES cell lines.
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Affiliation(s)
- Bryce W Carey
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
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6
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Carey BW, Markoulaki S, Beard C, Hanna J, Jaenisch R. Single-gene transgenic mouse strains for reprogramming adult somatic cells. Nat Methods 2009; 7:56-9. [PMID: 20010831 DOI: 10.1038/nmeth.1410] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Accepted: 11/05/2009] [Indexed: 11/09/2022]
Abstract
We report transgenic mouse models in which three or four reprogramming factors are expressed from a single genomic locus using a drug-inducible transgene. Multiple somatic cell types can be directly reprogrammed to generate induced pluripotent stem cells (iPSCs) by culture in doxycycline. Because reprogramming factors are carried on a single polycistronic construct, the mice can be easily maintained, and the transgene can be easily transferred into other genetic backgrounds.
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Affiliation(s)
- Bryce W Carey
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, USA
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7
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Hanna J, Markoulaki S, Mitalipova M, Cheng AW, Cassady JP, Staerk J, Carey BW, Lengner CJ, Foreman R, Love J, Gao Q, Kim J, Jaenisch R. Metastable Pluripotent States in NOD-Mouse-Derived ESCs. Cell Stem Cell 2009. [DOI: 10.1016/j.stem.2009.06.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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8
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Hanna J, Markoulaki S, Mitalipova M, Cheng AW, Cassady JP, Staerk J, Carey BW, Lengner CJ, Foreman R, Love J, Gao Q, Kim J, Jaenisch R. Metastable pluripotent states in NOD-mouse-derived ESCs. Cell Stem Cell 2009; 4:513-24. [PMID: 19427283 DOI: 10.1016/j.stem.2009.04.015] [Citation(s) in RCA: 285] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Revised: 04/09/2009] [Accepted: 04/20/2009] [Indexed: 11/17/2022]
Abstract
Embryonic stem cells (ESCs) are isolated from the inner cell mass (ICM) of blastocysts, whereas epiblast stem cells (EpiSCs) are derived from the postimplantation epiblast and display a restricted developmental potential. Here we characterize pluripotent states in the nonobese diabetic (NOD) mouse strain, which prior to this study was considered "nonpermissive" for ESC derivation. We find that NOD stem cells can be stabilized by providing constitutive expression of Klf4 or c-Myc or small molecules that can replace these factors during in vitro reprogramming. The NOD ESCs and iPSCs appear to be "metastable," as they acquire an alternative EpiSC-like identity after removal of the exogenous factors, while their reintroduction converts the cells back to ICM-like pluripotency. Our findings suggest that stem cells from different genetic backgrounds can assume distinct states of pluripotency in vitro, the stability of which is regulated by endogenous genetic determinants and can be modified by exogenous factors.
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Affiliation(s)
- Jacob Hanna
- The Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA.
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9
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Guttman M, Amit I, Garber M, French C, Lin MF, Feldser D, Huarte M, Zuk O, Carey BW, Cassady JP, Cabili MN, Jaenisch R, Mikkelsen TS, Jacks T, Hacohen N, Bernstein BE, Kellis M, Regev A, Rinn JL, Lander ES. Chromatin signature reveals over a thousand highly conserved large non-coding RNAs in mammals. Nature 2009; 458:223-7. [PMID: 19182780 DOI: 10.1038/nature07672] [Citation(s) in RCA: 3195] [Impact Index Per Article: 213.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2008] [Accepted: 11/25/2008] [Indexed: 12/19/2022]
Abstract
There is growing recognition that mammalian cells produce many thousands of large intergenic transcripts. However, the functional significance of these transcripts has been particularly controversial. Although there are some well-characterized examples, most (>95%) show little evidence of evolutionary conservation and have been suggested to represent transcriptional noise. Here we report a new approach to identifying large non-coding RNAs using chromatin-state maps to discover discrete transcriptional units intervening known protein-coding loci. Our approach identified approximately 1,600 large multi-exonic RNAs across four mouse cell types. In sharp contrast to previous collections, these large intervening non-coding RNAs (lincRNAs) show strong purifying selection in their genomic loci, exonic sequences and promoter regions, with greater than 95% showing clear evolutionary conservation. We also developed a functional genomics approach that assigns putative functions to each lincRNA, demonstrating a diverse range of roles for lincRNAs in processes from embryonic stem cell pluripotency to cell proliferation. We obtained independent functional validation for the predictions for over 100 lincRNAs, using cell-based assays. In particular, we demonstrate that specific lincRNAs are transcriptionally regulated by key transcription factors in these processes such as p53, NFkappaB, Sox2, Oct4 (also known as Pou5f1) and Nanog. Together, these results define a unique collection of functional lincRNAs that are highly conserved and implicated in diverse biological processes.
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Affiliation(s)
- Mitchell Guttman
- Broad Institute of MIT and Harvard, 7 Cambridge Center, Cambridge, Massachusetts 02142, USA
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10
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Markoulaki S, Hanna J, Beard C, Carey BW, Cheng AW, Lengner CJ, Dausman JA, Fu D, Gao Q, Wu S, Cassady JP, Jaenisch R. Transgenic mice with defined combinations of drug-inducible reprogramming factors. Nat Biotechnol 2009; 27:169-71. [PMID: 19151700 PMCID: PMC2654270 DOI: 10.1038/nbt.1520] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Accepted: 12/19/2008] [Indexed: 01/01/2023]
Abstract
Drug-inducible lentiviruses encoding Oct4, Sox2, Klf4 and c-Myc were used to derive “primary” iPS cells and segregated through germline transmission generating mice and fibroblasts carrying subsets of the reprogramming factors. Drug treatment of the cells resulted in “secondary” iPS cell derivation only when the missing factor was introduced. This creates a defined platform for studying reprogramming mechanisms and allows screening of genetically homogenous cells for compounds that replace any transcription factor required for iPS cell derivation.
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Affiliation(s)
- Styliani Markoulaki
- The Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, Massachusetts 02142, USA
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11
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Carey BW, Markoulaki S, Hanna J, Saha K, Gao Q, Mitalipova M, Jaenisch R. Reprogramming of murine and human somatic cells using a single polycistronic vector. Proc Natl Acad Sci U S A 2009; 106:157-62. [PMID: 19109433 PMCID: PMC2629226 DOI: 10.1073/pnas.0811426106] [Citation(s) in RCA: 397] [Impact Index Per Article: 26.5] [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: 10/18/2008] [Indexed: 01/26/2023] Open
Abstract
Directed reprogramming of somatic cells by defined factors provides a novel method for the generation of patient-specific stem cells with the potential to bypass both the practical and ethical concerns associated with somatic cell nuclear transfer (SCNT) and human embryonic stem (hES) cells. Although the generation of induced pluripotent stem (iPS) cells has proven a robust technology in mouse and human, a major impediment to the use of iPS cells for therapeutic purposes has been the viral-based delivery of the reprogramming factors because multiple proviral integrations pose the danger of insertional mutagenesis. Here we report a novel approach to reduce the number of viruses necessary to reprogram somatic cells by delivering reprogramming factors in a single virus using 2A "self-cleaving" peptides, which support efficient polycistronic expression from a single promoter. We find that up to four reprogramming factors (Oct4, Sox2, Klf4, and c-Myc) can be expressed from a single virus to generate iPS cells in both embryonic and adult somatic mouse cells and we show that a single proviral copy is sufficient to generate iPS cells from mouse embryonic fibroblasts. In addition we have generated human induced pluripotent stem (hiPS) cell lines from human keratinocytes, demonstrating that a single polycistronic virus can reprogram human somatic cells.
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Affiliation(s)
- Bryce W. Carey
- Whitehead Institute for Biomedical Research and
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
| | | | - Jacob Hanna
- Whitehead Institute for Biomedical Research and
| | - Kris Saha
- Whitehead Institute for Biomedical Research and
| | - Qing Gao
- Whitehead Institute for Biomedical Research and
| | | | - Rudolf Jaenisch
- Whitehead Institute for Biomedical Research and
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
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Abstract
All mammalian somatic cells originate from a single fertilized cell, the zygote, and share identical genetic information despite the dramatic changes in cell structure and function that accompany organismal development. The genome is subjected to a wide array of epigenetic modifications during lineage specification, a process that contributes to the implementation and maintenance of specific gene expression programs in somatic cells. Nuclear transfer and cell-fusion experiments demonstrate that the epigenetic signature directing a cell identity can be erased and modified into that of another cell type. Furthermore, in the case of cloning, differentiated cells can be reprogrammed back to pluripotency to support the reexpression of all developmental programs. Recent breakthroughs highlight the importance of transcription factors as well as epigenetic modifiers in the establishment, maintenance, and rewiring of cell identity. By focusing on reprogramming of terminally differentiated lymphocytes, we review and highlight recent insights into the molecular mechanisms and cellular events potentially underlying programming and reprogramming of somatic cell identity in mammals.
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Affiliation(s)
- J Hanna
- The Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA
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13
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Hanna J, Markoulaki S, Schorderet P, Carey BW, Beard C, Wernig M, Creyghton MP, Steine EJ, Cassady JP, Foreman R, Lengner CJ, Dausman JA, Jaenisch R. Direct Reprogramming of Terminally Differentiated Mature B Lymphocytes to Pluripotency. Cell 2008. [DOI: 10.1016/j.cell.2008.07.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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14
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Hanna J, Markoulaki S, Schorderet P, Carey BW, Beard C, Wernig M, Creyghton MP, Steine EJ, Cassady JP, Foreman R, Lengner CJ, Dausman JA, Jaenisch R. Direct reprogramming of terminally differentiated mature B lymphocytes to pluripotency. Cell 2008; 133:250-64. [PMID: 18423197 DOI: 10.1016/j.cell.2008.03.028] [Citation(s) in RCA: 535] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2008] [Revised: 03/19/2008] [Accepted: 03/26/2008] [Indexed: 12/22/2022]
Abstract
Pluripotent cells can be derived from fibroblasts by ectopic expression of defined transcription factors. A fundamental unresolved question is whether terminally differentiated cells can be reprogrammed to pluripotency. We utilized transgenic and inducible expression of four transcription factors (Oct4, Sox2, Klf4, and c-Myc) to reprogram mouse B lymphocytes. These factors were sufficient to convert nonterminally differentiated B cells to a pluripotent state. However, reprogramming of mature B cells required additional interruption with the transcriptional state maintaining B cell identity by either ectopic expression of the myeloid transcription factor CCAAT/enhancer-binding-protein-alpha (C/EBPalpha) or specific knockdown of the B cell transcription factor Pax5. Multiple iPS lines were clonally derived from both nonfully and fully differentiated B lymphocytes, which gave rise to adult chimeras with germline contribution, and to late-term embryos when injected into tetraploid blastocysts. Our study provides definite proof for the direct nuclear reprogramming of terminally differentiated adult cells to pluripotency.
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Affiliation(s)
- Jacob Hanna
- The Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
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15
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Abstract
The endemic index is a time saver for busy health officials. It permits the delegating of enormous routine work to a clerical staff. By the devices a serious condition is automatically brought to the attention of the staff, who notify the chief.
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Kim DY, Carey BW, Wang H, Ingano LAM, Binshtok AM, Wertz MH, Pettingell WH, He P, Lee VMY, Woolf CJ, Kovacs DM. BACE1 regulates voltage-gated sodium channels and neuronal activity. Nat Cell Biol 2007; 9:755-64. [PMID: 17576410 PMCID: PMC2747787 DOI: 10.1038/ncb1602] [Citation(s) in RCA: 244] [Impact Index Per Article: 14.4] [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: 04/16/2007] [Accepted: 05/30/2007] [Indexed: 02/08/2023]
Abstract
BACE1 activity is significantly increased in the brains of Alzheimer's disease patients, potentially contributing to neurodegeneration. The voltage-gated sodium channel (Na(v)1) beta2-subunit (beta2), a type I membrane protein that covalently binds to Na(v)1 alpha-subunits, is a substrate for BACE1 and gamma-secretase. Here, we find that BACE1-gamma-secretase cleavages release the intracellular domain of beta2, which increases mRNA and protein levels of the pore-forming Na(v)1.1 alpha-subunit in neuroblastoma cells. Similarly, endogenous beta2 processing and Na(v)1.1 protein levels are elevated in brains of BACE1-transgenic mice and Alzheimer's disease patients with high BACE1 levels. However, Na(v)1.1 is retained inside the cells and cell surface expression of the Na(v)1 alpha-subunits and sodium current densities are markedly reduced in both neuroblastoma cells and adult hippocampal neurons from BACE1-transgenic mice. BACE1, by cleaving beta2, thus regulates Na(v)1 alpha-subunit levels and controls cell-surface sodium current densities. BACE1 inhibitors may normalize membrane excitability in Alzheimer's disease patients with elevated BACE1 activity.
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Affiliation(s)
- Doo Yeon Kim
- Neurobiology of Disease Laboratory, Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
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Haapasalo A, Kim DY, Carey BW, Turunen MK, Pettingell WH, Kovacs DM. Presenilin/gamma-secretase-mediated cleavage regulates association of leukocyte-common antigen-related (LAR) receptor tyrosine phosphatase with beta-catenin. J Biol Chem 2007; 282:9063-72. [PMID: 17259169 DOI: 10.1074/jbc.m611324200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Leukocyte-common antigen-related (LAR) receptor tyrosine phosphatase regulates cell adhesion and formation of functional synapses and neuronal networks. Here we report that LAR is sequentially cleaved by alpha- and presenilin (PS)/gamma-secretases, which also affect signaling and/or degradation of type-I membrane proteins including the Alzheimer disease-related beta-amyloid precursor protein. Similar to the previously characterized PS/gamma-secretase substrates, inhibition of gamma-secretase activity resulted in elevated LAR C-terminal fragment (LAR-CTF) levels in stably LAR-overexpressing Chinese hamster ovary (CHO) cells, human neuroglioma cells, and mouse cortical neurons endogenously expressing LAR. Furthermore, LAR-CTF levels increased in cells lacking functional PS, indicating that gamma-secretase-mediated cleavage of LAR was PS-dependent. Inhibition of alpha-secretase activity by TAPI-1 treatment blocked LAR-CTF accumulation, demonstrating that prior ectodomain shedding was prerequisite for PS/gamma-secretase-mediated cleavage of LAR. Moreover, we identified the product of PS/gamma-secretase cleavage, LAR intracellular domain (LICD), both in vitro and in cells overexpressing full-length (FL) LAR or LAR-CTFs. LAR localizes to cadherin-beta-catenin-based cellular junctions. Assembly and disassembly of these junctions are regulated by tyrosine phosphorylation. We found that endogenous tyrosine-phosphorylated beta-catenin coimmunoprecipitated with LAR in CHO cells. However, when PS/gamma-secretase activity was inhibited, the association between LAR and beta-catenin significantly diminished. In addition to cell adhesion, beta-catenin is involved in transcriptional regulation. We observed that LICD significantly decreased transcription of cyclin D1, one of the beta-catenin target genes. Thus, our results show that PS/gamma-secretase-mediated cleavage of LAR controls LAR-beta-catenin interaction, suggesting an essential role for PS/gamma-secretase in the regulation of LAR signaling.
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Affiliation(s)
- Annakaisa Haapasalo
- Neurobiology of Disease Laboratory, Genetics and Aging Research Unit, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129, USA
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Haapasalo A, Kim DY, Carey BW, Pettingell WH, Kovacs DM. P3–394: Proteolytic cleavage of LAR receptor tyrosine phosphatase by gamma–secretase regulates association with beta–catenin. Alzheimers Dement 2006. [DOI: 10.1016/j.jalz.2006.05.1664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
| | - Doo Y. Kim
- Massachusetts General Hospital/Harvard Medical SchoolCharlestownMAUSA
| | - Bryce W. Carey
- Massachusetts General Hospital/Harvard Medical SchoolCharlestownMAUSA
| | | | - Dora M. Kovacs
- Massachusetts General Hospital/Harvard Medical SchoolCharlestownMAUSA
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Kim DY, Ingano LAM, Carey BW, Pettingell WH, Kovacs DM. Presenilin/gamma-secretase-mediated cleavage of the voltage-gated sodium channel beta2-subunit regulates cell adhesion and migration. J Biol Chem 2005; 280:23251-61. [PMID: 15833746 DOI: 10.1074/jbc.m412938200] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The voltage-gated sodium channel beta2-subunit (beta2) is a member of the IgCAM superfamily and serves as both an adhesion molecule and an auxiliary subunit of the voltage-gated sodium channel. Here we found that beta2 undergoes ectodomain shedding followed by presenilin (PS)-dependent gamma-secretase-mediated cleavage. 12-O-Tetradecanoylphorbol-13-acetate treatment or expression of an alpha-secretase enzyme, ADAM10, resulted in ectodomain cleavage of beta2 in Chinese hamster ovary cells. Subsequent cleavage of the remaining 15-kDa C-terminal fragment (beta2-CTF) was independently inhibited by three specific gamma-secretase inhibitors, expression of the dominant negative form of PS1, and in PS1/PS2 knock-out cells. gamma-Secretase inhibitor treatment also increased endogenous beta2-CTF levels in neuroblastoma cells and mouse primary neuronal cultures. In a cell-free gamma-secretase assay, we detected gamma-secretase activity-dependent generation of a 12 kDa beta2 intracellular domain (ICD), which was loosely associated with the membrane fraction. To assess the functional role of beta2 processing by gamma-secretase, we tested whether N-[N-(3,5-difluorophenylacetyl-l-alanyl)]-S-phenylglycine t-butylester (DAPT), a specific gamma-secretase inhibitor, would alter beta2-mediated cell adhesion and migration. We found that DAPT inhibited cell-cell aggregation and migration in a wound healing assay carried out with Chinese hamster ovary cells expressing beta2. DAPT also reduced migration of neuroblastoma cells in a modified Boyden chamber assay. Since DAPT treatment resulted in increased beta2-CTF levels, we also tested whether beta2-CTFs or beta2-ICDs would directly affect cell migration by overexpressing recombinant proteins. Interestingly, elevated levels of beta2-CTFs, but not ICDs, also blocked cell migration by 81 to 93%. Together, our findings show for the first time that beta2 is a PS/gamma-secretase substrate and gamma-secretase mediated cleavage of beta2-CTF is required for cell-cell adhesion and migration of beta2-expressing cells.
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Affiliation(s)
- Doo Yeon Kim
- Neurobiology of Disease Laboratory, Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, 02129, USA
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Kim DY, MacKenzie Ingano LA, Carey BW, Pettingell W, Kovacs DM. P4-290 Voltage-gated sodium channel beta2 subunit is processed by alpha-, beta- and gamma-secretases, generating fragments elevated in AD brains. Neurobiol Aging 2004. [DOI: 10.1016/s0197-4580(04)81848-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Carey BW. Photodynamic Reaction to Demethylchlortetracycline (Declomycin). Can Med Assoc J 1960; 82:334. [PMID: 20326136 PMCID: PMC1937757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Subscribe] [Scholar Register] [Indexed: 04/19/2023]
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