651
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The histone demethylase Jhdm1a regulates hepatic gluconeogenesis. PLoS Genet 2012; 8:e1002761. [PMID: 22719268 PMCID: PMC3375226 DOI: 10.1371/journal.pgen.1002761] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 04/30/2012] [Indexed: 11/19/2022] Open
Abstract
Hepatic gluconeogenesis is required for maintaining blood glucose homeostasis; yet, in diabetes mellitus, this process is unrestrained and is a major contributor to fasting hyperglycemia. To date, the impacts of chromatin modifying enzymes and chromatin landscape on gluconeogenesis are poorly understood. Through catalyzing the removal of methyl groups from specific lysine residues in the histone tail, histone demethylases modulate chromatin structure and, hence, gene expression. Here we perform an RNA interference screen against the known histone demethylases and identify a histone H3 lysine 36 (H3K36) demethylase, Jhdm1a, as a key negative regulator of gluconeogenic gene expression. In vivo, silencing of Jhdm1a promotes liver glucose synthesis, while its exogenous expression reduces blood glucose level. Importantly, the regulation of gluconeogenesis by Jhdm1a requires its demethylation activity. Mechanistically, we find that Jhdm1a regulates the expression of a major gluconeogenic regulator, C/EBPα. This is achieved, at least in part, by its USF1-dependent association with the C/EBPα promoter and its subsequent demethylation of dimethylated H3K36 on the C/EBPα locus. Our work provides compelling evidence that links histone demethylation to transcriptional regulation of gluconeogenesis and has important implications for the treatment of diabetes. Histones are small proteins that are essential for packaging and ordering genetic information (DNA) into high-order chromatin structures. Methylation of specific lysine residues of histones alters chromatin structure, serving as an important epigenetic mechanism for regulation of gene expression. The dynamic nature of histone methylation is controlled by a balance of methyltransferases and demethylases. We have discovered here that the demethylase Jhdm1a negatively regulates gluconeogenesis (de novo glucose synthesis) through suppressing the expression of two rate-limiting gluconeogenic enzymes. Gluconeogenesis is required for maintaining blood glucose homeostasis; yet, in diabetes mellitus, this process is unrestrained and is a major contributor to hyperglycemia. Indeed, we have found that manipulation of Jhdm1a level in liver affects glucose production in normal mice and hyperglycemia in diabetic mice. Mechanistically, Jhdm1a actively removes dimethyl groups from histone H3K36 along the locus of a key gluconeogenic regulator, C/EBPα, which in turn results in decreased C/EBPα expression. Our findings thus identify histone demethylation as a novel regulatory mechanism for gluconeogenesis and have important implications for the treatment of diabetes.
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652
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Lafontaine J, Tchakarska G, Rodier F, Mes-Masson AM. Necdin modulates proliferative cell survival of human cells in response to radiation-induced genotoxic stress. BMC Cancer 2012; 12:234. [PMID: 22691188 PMCID: PMC3495902 DOI: 10.1186/1471-2407-12-234] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 05/23/2012] [Indexed: 12/26/2022] Open
Abstract
Background The finite replicative lifespan of cells, termed cellular senescence, has been proposed as a protective mechanism against the proliferation of oncogenically damaged cells, that fuel cancer. This concept is further supported by the induction of premature senescence, a process which is activated when an oncogene is expressed in normal primary cells as well as following intense genotoxic stresses. Thus, deregulation of genes that control this process, like the tumor suppressor p53, may contribute to promoting cancer by allowing cells to bypass senescence. A better understanding of the genes that contribute to the establishment of senescence is therefore warranted. Necdin interacts with p53 and is also a p53 target gene, although the importance of Necdin in the p53 response is not clearly understood. Methods In this study, we first investigated Necdin protein expression during replicative senescence and premature senescence induced by gamma irradiation and by the overexpression of oncogenic RasV12. Gain and loss of function experiments were used to evaluate the contribution of Necdin during the senescence process. Results Necdin expression declined during replicative aging of IMR90 primary human fibroblasts or following induction of premature senescence. Decrease in Necdin expression seemed to be a consequence of the establishment of senescence since the depletion of Necdin in human cells did not induce a senescence-like growth arrest nor a flat morphology or SA-β-galactosidase activity normally associated with senescence. Similarly, overexpression of Necdin did not affect the life span of IMR90 cells. However, we demonstrate that in normal human cells, Necdin expression mimicked the effect of p53 inactivation by increasing radioresistance. Conclusion This result suggests that Necdin potentially attenuate p53 signaling in response to genotoxic stress in human cells and supports similar results describing an inhibitory function of Necdin over p53-dependent growth arrest in mice.
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Affiliation(s)
- Julie Lafontaine
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Institut du cancer de Montréal, Y-4606, 1560, rue Sherbrooke Est, Montréal, QC, H2L 4 M1, Canada
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653
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Le Page C, Marineau A, Bonza PK, Rahimi K, Cyr L, Labouba I, Madore J, Delvoye N, Mes-Masson AM, Provencher DM, Cailhier JF. BTN3A2 expression in epithelial ovarian cancer is associated with higher tumor infiltrating T cells and a better prognosis. PLoS One 2012. [PMID: 22685580 DOI: 10.1371/journal.pone.0038541] [] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BTN3A2/BT3.2 butyrophilin mRNA expression by tumoral cells was previously identified as a prognostic factor in a small cohort of high grade serous epithelial ovarian cancer (HG-EOC). Here, we evaluated the prognostic value of BT3.2 at the protein level in specimen from 199 HG-EOC patients. As the only known role of butyrophilin proteins is in immune regulation, we evaluated the association between BT3.2 expression and intratumoral infiltration of immune cells by immunohistochemistry with specific antibodies against BT3.2, CD3, CD4, CD8, CD20, CD68 and CD206. Epithelial BT3.2 expression was significantly associated with longer overall survival and lower risk of disease progression (HR=0.651, p=0.006 and HR=0.642, p=0.002, respectively) and significantly associated with a higher density of infiltrating T cells, particularly CD4+ cells (0.272, p<0.001). We also observed a strong association between the relative density of CD206+ cells, as evaluated by the ratio of intratumoral CD206+/CD68+ expression, and risk of disease progression (HR=1.355 p=0.044, respectively). In conclusion, BT3.2 protein is a potential prognostic biomarker for the identification of HG-EOC patients with better outcome. In contrast, high CD206+/CD68+ expression is associated with high risk of disease progression. While the role of BT3.2 is still unknown, our result suggest that BT3.2 expression by epithelial cells may modulates the intratumoral infiltration of immune cells.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Antigens, CD/metabolism
- Antigens, Differentiation, Myelomonocytic/metabolism
- Blotting, Western
- Butyrophilins
- Cell Line, Tumor
- Cohort Studies
- Female
- Humans
- Immunohistochemistry/statistics & numerical data
- Kaplan-Meier Estimate
- Lectins, C-Type/metabolism
- Lymphocytes, Tumor-Infiltrating/metabolism
- Lymphocytes, Tumor-Infiltrating/pathology
- Mannose Receptor
- Mannose-Binding Lectins/metabolism
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/metabolism
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Middle Aged
- Multivariate Analysis
- Neoplasms, Glandular and Epithelial/genetics
- Neoplasms, Glandular and Epithelial/metabolism
- Neoplasms, Glandular and Epithelial/pathology
- Ovarian Neoplasms/genetics
- Ovarian Neoplasms/metabolism
- Ovarian Neoplasms/pathology
- Prognosis
- Proportional Hazards Models
- Protein Isoforms/metabolism
- Receptors, Cell Surface/metabolism
- T-Lymphocytes/metabolism
- T-Lymphocytes/pathology
- Tissue Array Analysis/statistics & numerical data
- Transfection
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Affiliation(s)
- Cécile Le Page
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec, Canada
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654
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Le Page C, Marineau A, Bonza PK, Rahimi K, Cyr L, Labouba I, Madore J, Delvoye N, Mes-Masson AM, Provencher DM, Cailhier JF. BTN3A2 expression in epithelial ovarian cancer is associated with higher tumor infiltrating T cells and a better prognosis. PLoS One 2012; 7:e38541. [PMID: 22685580 PMCID: PMC3369854 DOI: 10.1371/journal.pone.0038541] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Accepted: 05/07/2012] [Indexed: 11/30/2022] Open
Abstract
BTN3A2/BT3.2 butyrophilin mRNA expression by tumoral cells was previously identified as a prognostic factor in a small cohort of high grade serous epithelial ovarian cancer (HG-EOC). Here, we evaluated the prognostic value of BT3.2 at the protein level in specimen from 199 HG-EOC patients. As the only known role of butyrophilin proteins is in immune regulation, we evaluated the association between BT3.2 expression and intratumoral infiltration of immune cells by immunohistochemistry with specific antibodies against BT3.2, CD3, CD4, CD8, CD20, CD68 and CD206. Epithelial BT3.2 expression was significantly associated with longer overall survival and lower risk of disease progression (HR = 0.651, p = 0.006 and HR = 0.642, p = 0.002, respectively) and significantly associated with a higher density of infiltrating T cells, particularly CD4+ cells (0.272, p<0.001). We also observed a strong association between the relative density of CD206+ cells, as evaluated by the ratio of intratumoral CD206+/CD68+ expression, and risk of disease progression (HR = 1.355 p = 0.044, respectively). In conclusion, BT3.2 protein is a potential prognostic biomarker for the identification of HG-EOC patients with better outcome. In contrast, high CD206+/CD68+ expression is associated with high risk of disease progression. While the role of BT3.2 is still unknown, our result suggest that BT3.2 expression by epithelial cells may modulates the intratumoral infiltration of immune cells.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Antigens, CD/metabolism
- Antigens, Differentiation, Myelomonocytic/metabolism
- Blotting, Western
- Butyrophilins
- Cell Line, Tumor
- Cohort Studies
- Female
- Humans
- Immunohistochemistry/statistics & numerical data
- Kaplan-Meier Estimate
- Lectins, C-Type/metabolism
- Lymphocytes, Tumor-Infiltrating/metabolism
- Lymphocytes, Tumor-Infiltrating/pathology
- Mannose Receptor
- Mannose-Binding Lectins/metabolism
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/metabolism
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Middle Aged
- Multivariate Analysis
- Neoplasms, Glandular and Epithelial/genetics
- Neoplasms, Glandular and Epithelial/metabolism
- Neoplasms, Glandular and Epithelial/pathology
- Ovarian Neoplasms/genetics
- Ovarian Neoplasms/metabolism
- Ovarian Neoplasms/pathology
- Prognosis
- Proportional Hazards Models
- Protein Isoforms/metabolism
- Receptors, Cell Surface/metabolism
- T-Lymphocytes/metabolism
- T-Lymphocytes/pathology
- Tissue Array Analysis/statistics & numerical data
- Transfection
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Affiliation(s)
- Cécile Le Page
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montreal, Quebec, Canada
- Institut du Cancer de Montréal, Montreal, Quebec, Canada
| | - Alexandre Marineau
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montreal, Quebec, Canada
- Institut du Cancer de Montréal, Montreal, Quebec, Canada
| | - Patrick K. Bonza
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montreal, Quebec, Canada
- Institut du Cancer de Montréal, Montreal, Quebec, Canada
| | - Kurosh Rahimi
- Department of Pathology, Centre Hospitalier de l’Université de Montréal (CHUM), Montreal, Quebec, Canada
| | - Louis Cyr
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montreal, Quebec, Canada
- Institut du Cancer de Montréal, Montreal, Quebec, Canada
| | - Ingrid Labouba
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montreal, Quebec, Canada
- Institut du Cancer de Montréal, Montreal, Quebec, Canada
| | - Jason Madore
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montreal, Quebec, Canada
- Institut du Cancer de Montréal, Montreal, Quebec, Canada
| | - Nathalie Delvoye
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montreal, Quebec, Canada
- Institut du Cancer de Montréal, Montreal, Quebec, Canada
| | - Anne-Marie Mes-Masson
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montreal, Quebec, Canada
- Institut du Cancer de Montréal, Montreal, Quebec, Canada
- Department of Medicine, Université de Montréal, Montreal, Quebec, Canada
| | - Diane M. Provencher
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montreal, Quebec, Canada
- Institut du Cancer de Montréal, Montreal, Quebec, Canada
- Division of Gynecologic-Oncology, Centre Hospitalier de l’Université de Montréal (CHUM), Montreal, Quebec, Canada
| | - Jean-François Cailhier
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montreal, Quebec, Canada
- Institut du Cancer de Montréal, Montreal, Quebec, Canada
- Department of Medicine, Université de Montréal, Montreal, Quebec, Canada
- Division of Nephrology, Centre Hospitalier de l’Université de Montréal (CHUM), Montreal, Quebec, Canada
- * E-mail:
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655
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Freund A, Laberge RM, Demaria M, Campisi J. Lamin B1 loss is a senescence-associated biomarker. Mol Biol Cell 2012; 23:2066-75. [PMID: 22496421 PMCID: PMC3364172 DOI: 10.1091/mbc.e11-10-0884] [Citation(s) in RCA: 627] [Impact Index Per Article: 52.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Revised: 03/30/2012] [Accepted: 04/05/2012] [Indexed: 12/30/2022] Open
Abstract
Cellular senescence is a potent tumor-suppressive mechanism that arrests cell proliferation and has been linked to aging. However, studies of senescence have been impeded by the lack of simple, exclusive biomarkers of the senescent state. Senescent cells develop characteristic morphological changes, which include enlarged and often irregular nuclei and chromatin reorganization. Because alterations to the nuclear lamina can affect both nuclear morphology and gene expression, we examined the nuclear lamina of senescent cells. We show here than lamin B1 is lost from primary human and murine cell strains when they are induced to senesce by DNA damage, replicative exhaustion, or oncogene expression. Lamin B1 loss did not depend on the p38 mitogen-activated protein kinase, nuclear factor-κB, ataxia telangiectasia-mutated kinase, or reactive oxygen species signaling pathways, which are positive regulators of senescent phenotypes. However, activation of either the p53 or pRB tumor suppressor pathway was sufficient to induce lamin B1 loss. Lamin B1 declined at the mRNA level via a decrease in mRNA stability rather than by the caspase-mediated degradation seen during apoptosis. Last, lamin B1 protein and mRNA declined in mouse tissue after senescence was induced by irradiation. Our findings suggest that lamin B1 loss can serve as biomarker of senescence both in culture and in vivo.
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Affiliation(s)
- Adam Freund
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
- Buck Institute for Research on Aging, Novato, CA 94945
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | | | - Marco Demaria
- Buck Institute for Research on Aging, Novato, CA 94945
| | - Judith Campisi
- Buck Institute for Research on Aging, Novato, CA 94945
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720
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656
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Rana MK, Worthylake RA. Novel mechanism for negatively regulating Rho-kinase (ROCK) signaling through Coronin1B protein in neuregulin 1 (NRG-1)-induced tumor cell motility. J Biol Chem 2012; 287:21836-45. [PMID: 22563075 DOI: 10.1074/jbc.m112.346114] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Although many mechanisms that activate ROCK are known, corresponding negative regulatory mechanisms required for cytoskeletal plasticity are poorly understood. We have discovered that Coronin1B is a novel attenuator of ROCK signaling. We initially identified Coronin1A in a proteomics screen for ROCK2-binding proteins, and here we demonstrate that Coronin1A/B bind directly to ROCK2 through its PH (Pleckstrin Homology) domain. The consequence of the ROCK2-Coronin1B interaction was tested and revealed that increased expression of Coronin1B inhibited, whereas knockdown of Coronin1B stimulated, phosphorylation of the ROCK substrate myosin light chain phosphatase and subsequently, myosin light chain. Thus, Coronin1B is a previously unrecognized inhibitor of ROCK signaling to myosin. Furthermore, we found that the phosphatase Slingshot IL (SSH1L) was required for Coronin1B to inhibit ROCK signaling. To test the significance of this novel mechanism in tumor cell motility, we investigated its role in neuregulin 1 (NRG-1)-induced cell scattering. Importantly, we found that attenuation of the ROCK signaling by Coronin1B was required for NRG-1 stimulated scattering. Our data support a model in which Coronin1B fine-tunes ROCK signaling to modulate myosin activity, which is important for tumor cell motility.
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Affiliation(s)
- Manish K Rana
- Department of Pharmacology, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70119, USA
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657
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Guo D, Standley C, Bellve K, Fogarty K, Bao ZZ. Protein kinase Cα and integrin-linked kinase mediate the negative axon guidance effects of Sonic hedgehog. Mol Cell Neurosci 2012; 50:82-92. [PMID: 22521536 PMCID: PMC3383945 DOI: 10.1016/j.mcn.2012.03.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Revised: 03/22/2012] [Accepted: 03/26/2012] [Indexed: 01/22/2023] Open
Abstract
In addition to its role as a morphogen, Sonic hedgehog (Shh) has also been shown to function as a guidance factor that directly acts on the growth cones of various types of axons. However, the noncanonical signaling pathways that mediate the guidance effects of Shh protein remain poorly understood. We demonstrate that a novel signaling pathway consisting of protein kinase Cα (PKCα) and integrin-linked kinase (ILK) mediates the negative guidance effects of high concentration of Shh on retinal ganglion cell (RGC) axons. Shh rapidly increased Ca(2+) level and activated PKCα and ILK in the growth cones of RGC axons. By in vitro kinase assay, PKCα was found to directly phosphorylate ILK on threonine-173 and -181. Inhibition of PKCα or expression of a mutant ILK with the PKCα phosphorylation sites mutated (ILK-DM), abolished the Shh-induced macropinocytosis, growth cone collapse and repulsive axon turning. In vivo, expression of a dominant negative PKCα or ILK-DM disrupted RGC axon pathfinding at the optic chiasm but not the projection toward the optic disk, supporting that this signaling pathway plays a specific role in Shh-mediated negative guidance effects.
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Affiliation(s)
- Daorong Guo
- Department of Medicine and Cell Biology, Program in Neuroscience, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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658
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Rubinstein JD, Elagib KE, Goldfarb AN. Cyclic AMP signaling inhibits megakaryocytic differentiation by targeting transcription factor 3 (E2A) cyclin-dependent kinase inhibitor 1A (CDKN1A) transcriptional axis. J Biol Chem 2012; 287:19207-15. [PMID: 22514271 DOI: 10.1074/jbc.m112.366476] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Signaling via the intracellular second messenger cyclic AMP (cAMP) has long been implicated in the repression of megakaryocytic differentiation. However, the mechanisms by which cAMP signaling impairs megakaryopoiesis have never been elucidated. In a human CD34(+) cell culture model, we show that the adenylyl cyclase agonist forskolin inhibits megakaryocytic differentiation in a protein kinase A-dependent manner. Using this system to screen for downstream effectors, we identified the transcription factor E2A as a key target in a novel repressive signaling pathway. Specifically, forskolin acting through protein kinase A-induced E2A down-regulation and enforced expression of E2A overrode the inhibitory effects of forskolin on megakaryopoiesis. The dependence of megakaryopoiesis on critical thresholds of E2A expression was confirmed in vivo in haploinsufficient mice and ex vivo using shRNA knockdown in human progenitors. Using a variety of approaches, we further identified p21 (encoded by CDKN1A) as a functionally important megakaryopoietic regulator residing downstream of E2A. These results thus implicate the E2A-CDKN1A transcriptional axis in the control of megakaryopoiesis and reveal the lineage-selective inhibition of this axis as a likely mechanistic basis for the inhibitory effects of cAMP signaling.
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Affiliation(s)
- Jeremy D Rubinstein
- Department of Pathology, University of Virginia School of Medicine, Charlottesville, Virginia 22903, USA
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659
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A genome wide shRNA screen identifies α/β hydrolase domain containing 4 (ABHD4) as a novel regulator of anoikis resistance. Apoptosis 2012; 17:666-78. [DOI: 10.1007/s10495-012-0723-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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660
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Singh A, Sweeney MF, Yu M, Burger A, Greninger P, Benes C, Haber DA, Settleman J. TAK1 inhibition promotes apoptosis in KRAS-dependent colon cancers. Cell 2012; 148:639-50. [PMID: 22341439 DOI: 10.1016/j.cell.2011.12.033] [Citation(s) in RCA: 224] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 10/28/2011] [Accepted: 12/29/2011] [Indexed: 10/28/2022]
Abstract
Colon cancers frequently harbor KRAS mutations, yet only a subset of KRAS mutant colon cancer cell lines are dependent upon KRAS signaling for survival. In a screen for kinases that promote survival of KRAS-dependent colon cancer cells, we found that the TAK1 kinase (MAP3K7) is required for tumor cell viability. The induction of apoptosis by RNAi-mediated depletion or pharmacologic inhibition of TAK1 is linked to its suppression of hyperactivated Wnt signaling, evident in both endogenous and genetically reconstituted cells. In APC mutant/KRAS-dependent cells, KRAS stimulates BMP-7 secretion and BMP signaling, leading to TAK1 activation and enhancement of Wnt-dependent transcription. An in vitro-derived "TAK1 dependency signature" is enriched in primary human colon cancers with mutations in both APC and KRAS, suggesting potential clinical utility in stratifying patient populations. Together, these findings identify TAK1 inhibition as a potential therapeutic strategy for a treatment-refractory subset of colon cancers exhibiting aberrant KRAS and Wnt pathway activation.
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Affiliation(s)
- Anurag Singh
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Charlestown, MA 02129, USA
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661
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White RE, Rämer PC, Naresh KN, Meixlsperger S, Pinaud L, Rooney C, Savoldo B, Coutinho R, Bödör C, Gribben J, Ibrahim HA, Bower M, Nourse JP, Gandhi MK, Middeldorp J, Cader FZ, Murray P, Münz C, Allday MJ. EBNA3B-deficient EBV promotes B cell lymphomagenesis in humanized mice and is found in human tumors. J Clin Invest 2012; 122:1487-502. [PMID: 22406538 DOI: 10.1172/jci58092] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Accepted: 01/25/2012] [Indexed: 11/17/2022] Open
Abstract
Epstein-Barr virus (EBV) persistently infects more than 90% of the human population and is etiologically linked to several B cell malignancies, including Burkitt lymphoma (BL), Hodgkin lymphoma (HL), and diffuse large B cell lymphoma (DLBCL). Despite its growth transforming properties, most immune-competent individuals control EBV infection throughout their lives. EBV encodes various oncogenes, and of the 6 latency-associated EBV-encoded nuclear antigens, only EBNA3B is completely dispensable for B cell transformation in vitro. Here, we report that infection with EBV lacking EBNA3B leads to aggressive, immune-evading monomorphic DLBCL-like tumors in NOD/SCID/γc-/- mice with reconstituted human immune system components. Infection with EBNA3B-knockout EBV (EBNA3BKO) induced expansion of EBV-specific T cells that failed to infiltrate the tumors. EBNA3BKO-infected B cells expanded more rapidly and secreted less T cell-chemoattractant CXCL10, reducing T cell recruitment in vitro and T cell-mediated killing in vivo. B cell lines from 2 EBV-positive human lymphomas encoding truncated EBNA3B exhibited gene expression profiles and phenotypic characteristics similar to those of tumor-derived lines from the humanized mice, including reduced CXCL10 secretion. Screening EBV-positive DLBCL, HL, and BL human samples identified additional EBNA3B mutations. Thus, EBNA3B is a virus-encoded tumor suppressor whose inactivation promotes immune evasion and virus-driven lymphomagenesis.
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Affiliation(s)
- Robert E White
- Section of Virology, Faculty of Medicine, Imperial College London, London, United Kingdom
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662
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Bazarov AV, Lee WJ, Bazarov I, Bosire M, Hines WC, Stankovich B, Chicas A, Lowe SW, Yaswen P. The specific role of pRb in p16 (INK4A) -mediated arrest of normal and malignant human breast cells. Cell Cycle 2012; 11:1008-13. [PMID: 22333593 DOI: 10.4161/cc.11.5.19492] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
RB family proteins pRb, p107 and p130 have similar structures and overlapping functions, enabling cell cycle arrest and cellular senescence. pRb, but not p107 or p130, is frequently mutated in human malignancies. In human fibroblasts acutely exposed to oncogenic ras, pRb has a specific role in suppressing DNA replication, and p107 or p130 cannot compensate for the loss of this function; however, a second p53/p21-dependent checkpoint prevents escape from growth arrest. This model of oncogene-induced senescence requires the additional loss of p53/p21 to explain selection for preferential loss of pRb function in human malignancies. We asked whether similar rules apply to the role of pRb in growth arrest of human epithelial cells, the source of most cancers. In two malignant human breast cancer cell lines, we found that individual RB family proteins were sufficient for the establishment of p16-initiated senescence, and that growth arrest in G 1 was not dependent on the presence of functional pRb or p53. However, senescence induction by endogenous p16 was delayed in primary normal human mammary epithelial cells with reduced pRb but not with reduced p107 or p130. Thus, under these circumstances, despite the presence of functional p53, p107 and p130 were unable to completely compensate for pRb in mediating senescence induction. We propose that early inactivation of pRb in pre-malignant breast cells can, by itself, extend proliferative lifespan, allowing acquisition of additional changes necessary for malignant transformation.
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Affiliation(s)
- Alexey V Bazarov
- Department of Medicine, University of California at San Francisco, San Francisco, CA, USA
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663
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Deuse T, Seifert M, Phillips N, Fire A, Tyan D, Kay M, Tsao PS, Hua X, Velden J, Eiermann T, Volk HD, Reichenspurner H, Robbins RC, Schrepfer S. Immunobiology of naïve and genetically modified HLA-class-I-knockdown human embryonic stem cells. J Cell Sci 2012; 124:3029-37. [PMID: 21878509 DOI: 10.1242/jcs.087718] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Human embryonic stem cells (hESCs) can serve as a universal cell source for emerging cell or tissue replacement strategies, but immune rejection of hESC derivatives remains an unsolved problem. Here, we sought to describe the mechanisms of rejection for naïve hESCs and upon HLA class I (HLA I) knockdown (hESC(KD)). hESCs were HLA I-positive but negative for HLA II and co-stimulatory molecules. Transplantation of naïve hESC into immunocompetent Balb/c mice induced substantial T helper cell 1 and 2 (Th1 and Th2) responses with rapid cell death, but hESCs survived in immunodeficient SCID-beige recipients. Histology revealed mainly macrophages and T cells, but only scattered natural killer (NK) cells. A surge of hESC-specific antibodies against hESC class I, but not class II antigens, was observed. Using HLA I RNA interference and intrabody technology, HLA I surface expression of hESC(KD) was 88%-99% reduced. T cell activation after hESC(KD) transplantation into Balb/c was significantly diminished, antibody production was substantially alleviated, the levels of graft-infiltrating immune cells were reduced and the survival of hESC(KD) was prolonged. Because of their very low expression of stimulatory NK ligands, NK-susceptibility of naïve hESCs and hESC(KD) was negligible. Thus, HLA I recognition by T cells seems to be the primary mechanism of hESC recognition, and T cells, macrophages and hESC-specific antibodies participate in hESC killing.
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Affiliation(s)
- Tobias Deuse
- Cardiothoracic Surgery Department, Stanford University, Stanford, CA 94305, USA
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664
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Chernikova SB, Razorenova OV, Higgins JP, Sishc BJ, Nicolau M, Dorth JA, Chernikova DA, Kwok S, Brooks JD, Bailey SM, Game JC, Brown JM. Deficiency in mammalian histone H2B ubiquitin ligase Bre1 (Rnf20/Rnf40) leads to replication stress and chromosomal instability. Cancer Res 2012; 72:2111-9. [PMID: 22354749 DOI: 10.1158/0008-5472.can-11-2209] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Mammalian Bre1 complexes (BRE1A/B (RNF20/40) in humans and Bre1a/b (Rnf20/40) in mice) function similarly to their yeast homolog Bre1 as ubiquitin ligases in monoubiquitination of histone H2B. This ubiquitination facilitates methylation of histone H3 at K4 and K79, and accounts for the roles of Bre1 and its homologs in transcriptional regulation. Recent studies by others suggested that Bre1 acts as a tumor suppressor, augmenting expression of select tumor suppressor genes and suppressing select oncogenes. In this study, we present an additional mechanism of tumor suppression by Bre1 through maintenance of genomic stability. We track the evolution of genomic instability in Bre1-deficient cells from replication-associated double-strand breaks (DSB) to specific genomic rearrangements that explain a rapid increase in DNA content and trigger breakage-fusion-bridge cycles. We show that aberrant RNA-DNA structures (R-loops) constitute a significant source of DSBs in Bre1-deficient cells. Combined with a previously reported defect in homologous recombination, generation of R-loops is a likely initiator of replication stress and genomic instability in Bre1-deficient cells. We propose that genomic instability triggered by Bre1 deficiency may be an important early step that precedes acquisition of an invasive phenotype, as we find decreased levels of BRE1A/B and dimethylated H3K79 in testicular seminoma and in the premalignant lesion in situ carcinoma.
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Affiliation(s)
- Sophia B Chernikova
- Department of Radiation Oncology, Stanford University, Stanford, California 94305, USA
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665
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Lafontaine J, Rodier F, Ouellet V, Mes-Masson AM. Necdin, a p53-target gene, is an inhibitor of p53-mediated growth arrest. PLoS One 2012; 7:e31916. [PMID: 22355404 PMCID: PMC3280226 DOI: 10.1371/journal.pone.0031916] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Accepted: 01/20/2012] [Indexed: 01/09/2023] Open
Abstract
In vitro, cellular immortalization and transformation define a model for multistep carcinogenesis and current ongoing challenges include the identification of specific molecular events associated with steps along this oncogenic pathway. Here, using NIH3T3 cells, we identified transcriptionally related events associated with the expression of Polyomavirus Large-T antigen (PyLT), a potent viral oncogene. We propose that a subset of these alterations in gene expression may be related to the early events that contribute to carcinogenesis. The proposed tumor suppressor Necdin, known to be regulated by p53, was within a group of genes that was consistently upregulated in the presence of PyLT. While Necdin is induced following p53 activation with different genotoxic stresses, Necdin induction by PyLT did not involve p53 activation or the Rb-binding site of PyLT. Necdin depletion by shRNA conferred a proliferative advantage to NIH3T3 and PyLT-expressing NIH3T3 (NIHLT) cells. In contrast, our results demonstrate that although overexpression of Necdin induced a growth arrest in NIH3T3 and NIHLT cells, a growing population rapidly emerged from these arrested cells. This population no longer showed significant proliferation defects despite high Necdin expression. Moreover, we established that Necdin is a negative regulator of p53-mediated growth arrest induced by nutlin-3, suggesting that Necdin upregulation could contribute to the bypass of a p53-response in p53 wild type tumors. To support this, we characterized Necdin expression in low malignant potential ovarian cancer (LMP) where p53 mutations rarely occur. Elevated levels of Necdin expression were observed in LMP when compared to aggressive serous ovarian cancers. We propose that in some contexts, the constitutive expression of Necdin could contribute to cancer promotion by delaying appropriate p53 responses and potentially promote genomic instability.
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Affiliation(s)
- Julie Lafontaine
- Centre de recherche du Centre hospitalier de l'Université de Montréal and Institut du cancer de Montréal, Montréal, Québec, Canada
| | - Francis Rodier
- Centre de recherche du Centre hospitalier de l'Université de Montréal and Institut du cancer de Montréal, Montréal, Québec, Canada
- Département de radiologie, radio-oncologie et médecine nucléaire, Université de Montréal, Montréal, Québec, Canada
| | - Véronique Ouellet
- Centre de recherche du Centre hospitalier de l'Université de Montréal and Institut du cancer de Montréal, Montréal, Québec, Canada
| | - Anne-Marie Mes-Masson
- Centre de recherche du Centre hospitalier de l'Université de Montréal and Institut du cancer de Montréal, Montréal, Québec, Canada
- Département de médecine, Université de Montréal, Montréal, Québec, Canada
- * E-mail:
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666
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Liang R, Khanna A, Muthusamy S, Li N, Sarojini H, Kopchick JJ, Masternak MM, Bartke A, Wang E. Post-transcriptional regulation of IGF1R by key microRNAs in long-lived mutant mice. Aging Cell 2011; 10:1080-8. [PMID: 21967153 PMCID: PMC3587961 DOI: 10.1111/j.1474-9726.2011.00751.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Long-lived mutant mice, both Ames dwarf and growth hormone receptor gene-disrupted or knockout strains, exhibit heightened cognitive robustness and altered IGF1 signaling in the brain. Here, we report, in both these long-lived mice, that three up-regulated lead microRNAs, miR-470, miR-669b, and miR-681, are involved in posttranscriptional regulation of genes pertinent to growth hormone/IGF1 signaling. All three are most prominently localized in the hippocampus and correspond to reduced expression of key IGF1 signaling genes: IGF1, IGF1R, and PI3 kinase. The decline in these genes' expression translates into decreased phosphorylation of downstream molecules AKT and FoxO3a. Cultures transfected with either miR-470, miR-669b, or miR-681 show repressed endogenous expression of all three genes of the IGF1 signaling axis, most significantly IGF1R, while other similarly up-regulated microRNAs, including let-7g and miR-509, do not induce the same levels of repression. Transduction study in IGF1-responsive cell cultures shows significantly reduced IGF1R expression, and AKT to some extent, most notably by miR-681. This is accompanied by decreased levels of downstream phosphorylated forms of AKT and FoxO3a upon IGF1 stimulation. Suppression of IGF1R by the three microRNAs is further validated by IGF1R 3'UTR reporter assays. Taken together, our results suggest that miR-470, miR-669b, and miR-681 are all functionally able to suppress IGF1R and AKT, two upstream genes controlling FoxO3a phosphorylation status. Their up-regulation in growth hormone signaling-deficient mutant mouse brain suggests reduced IGF1 signaling at the posttranscriptional level, for numerous gains of neuronal function in these long-lived mice.
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Affiliation(s)
- Ruqiang Liang
- Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, Kentucky
- Gheens Center on Aging, University of Louisville School of Medicine, Louisville, Kentucky
| | - Amit Khanna
- Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, Kentucky
- Gheens Center on Aging, University of Louisville School of Medicine, Louisville, Kentucky
| | - Senthilkumar Muthusamy
- Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, Kentucky
- Gheens Center on Aging, University of Louisville School of Medicine, Louisville, Kentucky
| | - Na Li
- Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, Kentucky
- Gheens Center on Aging, University of Louisville School of Medicine, Louisville, Kentucky
| | - Harshini Sarojini
- Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, Kentucky
- Gheens Center on Aging, University of Louisville School of Medicine, Louisville, Kentucky
| | | | - Michal M. Masternak
- Department of Medicine, Southern Illinois University, Springfield, Illinois
- Burnet School of Biomedical Sciences, University of Central Florida, Orlando, Florida
- Institute of Human Genetics, Polish Academy of Sciences, Strzeszynska St., No 32, 60-479 Poznan, Poland
| | - Andrzej Bartke
- Department of Medicine, Southern Illinois University, Springfield, Illinois
| | - Eugenia Wang
- Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, Kentucky
- Gheens Center on Aging, University of Louisville School of Medicine, Louisville, Kentucky
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667
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Wang J, Geesman GJ, Hostikka SL, Atallah M, Blackwell B, Lee E, Cook PJ, Pasaniuc B, Shariat G, Halperin E, Dobke M, Rosenfeld MG, Jordan IK, Lunyak VV. Inhibition of activated pericentromeric SINE/Alu repeat transcription in senescent human adult stem cells reinstates self-renewal. Cell Cycle 2011; 10:3016-30. [PMID: 21862875 PMCID: PMC3218602 DOI: 10.4161/cc.10.17.17543] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 07/28/2011] [Indexed: 01/01/2023] Open
Abstract
Cellular aging is linked to deficiencies in efficient repair of DNA double strand breaks and authentic genome maintenance at the chromatin level. Aging poses a significant threat to adult stem cell function by triggering persistent DNA damage and ultimately cellular senescence. Senescence is often considered to be an irreversible process. Moreover, critical genomic regions engaged in persistent DNA damage accumulation are unknown. Here we report that 65% of naturally occurring repairable DNA damage in self-renewing adult stem cells occurs within transposable elements. Upregulation of Alu retrotransposon transcription upon ex vivo aging causes nuclear cytotoxicity associated with the formation of persistent DNA damage foci and loss of efficient DNA repair in pericentric chromatin. This occurs due to a failure to recruit of condensin I and cohesin complexes. Our results demonstrate that the cytotoxicity of induced Alu repeats is functionally relevant for the human adult stem cell aging. Stable suppression of Alu transcription can reverse the senescent phenotype, reinstating the cells' self-renewing properties and increasing their plasticity by altering so-called "master" pluripotency regulators.
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Affiliation(s)
- Jianrong Wang
- School of Biology, Georgia Institute of Technology, Atlanta, GA, USA
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668
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Coppé JP, Rodier F, Patil CK, Freund A, Desprez PY, Campisi J. Tumor suppressor and aging biomarker p16(INK4a) induces cellular senescence without the associated inflammatory secretory phenotype. J Biol Chem 2011; 286:36396-403. [PMID: 21880712 DOI: 10.1074/jbc.m111.257071] [Citation(s) in RCA: 341] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Cellular senescence suppresses cancer by preventing the proliferation of cells that experience potentially oncogenic stimuli. Senescent cells often express p16(INK4a), a cyclin-dependent kinase inhibitor, tumor suppressor, and biomarker of aging, which renders the senescence growth arrest irreversible. Senescent cells also acquire a complex phenotype that includes the secretion of many cytokines, growth factors, and proteases, termed a senescence-associated secretory phenotype (SASP). The SASP is proposed to underlie age-related pathologies, including, ironically, late life cancer. Here, we show that ectopic expression of p16(INK4a) and another cyclin-dependent kinase inhibitor, p21(CIP1/WAF1), induces senescence without a SASP, even though they induced other features of senescence, including a stable growth arrest. Additionally, human fibroblasts induced to senesce by ionizing radiation or oncogenic RAS developed a SASP regardless of whether they expressed p16(INK4a). Cells induced to senesce by ectopic p16(INK4a) expression lacked paracrine activity on epithelial cells, consistent with the absence of a functional SASP. Nonetheless, expression of p16(INK4a) by cells undergoing replicative senescence limited the accumulation of DNA damage and premature cytokine secretion, suggesting an indirect role for p16(INK4a) in suppressing the SASP. These findings suggest that p16(INK4a)-positive cells may not always harbor a SASP in vivo and, furthermore, that the SASP is not a consequence of p16(INK4a) activation or senescence per se, but rather is a damage response that is separable from the growth arrest.
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Affiliation(s)
- Jean-Philippe Coppé
- Division of Life Sciences, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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669
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Lake RJ, Basheer A, Fan HY. Reciprocally regulated chromatin association of Cockayne syndrome protein B and p53 protein. J Biol Chem 2011; 286:34951-8. [PMID: 21852235 DOI: 10.1074/jbc.m111.252643] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The Cockayne syndrome complementation group B (CSB) protein is an ATP-dependent chromatin remodeler with an essential function in transcription-coupled DNA repair, and mutations in the CSB gene are associated with Cockayne syndrome. The p53 tumor suppressor has been known to interact with CSB, and both proteins have been implicated in overlapping biological processes, such as DNA repair and aging. The significance of the interaction between CSB and p53 has remained unclear, however. Here, we show that the chromatin association of CSB and p53 is inversely related. Using in vitro binding and chromatin immunoprecipitation approaches, we demonstrate that CSB facilitates the sequence-independent association of p53 with chromatin when p53 concentrations are low and that this is achieved by the interaction of CSB with the C-terminal region of p53. Remarkably, p53 prevents CSB from binding to nucleosomes when p53 concentrations are elevated. Examining the enzymatic properties of CSB revealed that p53 excludes CSB from nucleosomes by occluding a nucleosome interaction surface on CSB. Together, our results suggest that the reciprocal regulation of chromatin access by CSB and p53 could be part of a mechanism by which these two proteins coordinate their activities to regulate DNA repair, cell survival, and aging.
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Affiliation(s)
- Robert J Lake
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6145, USA
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670
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Birket MJ, Orr AL, Gerencser AA, Madden DT, Vitelli C, Swistowski A, Brand MD, Zeng X. A reduction in ATP demand and mitochondrial activity with neural differentiation of human embryonic stem cells. J Cell Sci 2011; 124:348-58. [PMID: 21242311 DOI: 10.1242/jcs.072272] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Here, we have investigated mitochondrial biology and energy metabolism in human embryonic stem cells (hESCs) and hESC-derived neural stem cells (NSCs). Although stem cells collectively in vivo might be expected to rely primarily on anaerobic glycolysis for ATP supply, to minimise production of reactive oxygen species, we show that in vitro this is not so: hESCs generate an estimated 77% of their ATP through oxidative phosphorylation. Upon differentiation of hESCs into NSCs, oxidative phosphorylation declines both in absolute rate and in importance relative to glycolysis. A bias towards ATP supply from oxidative phosphorylation in hESCs is consistent with the expression levels of the mitochondrial gene regulators peroxisome-proliferator-activated receptor γ coactivator (PGC)-1α, PGC-1β and receptor-interacting protein 140 (RIP140) in hESCs when compared with a panel of differentiated cell types. Analysis of the ATP demand showed that the slower ATP turnover in NSCs was associated with a slower rate of most energy-demanding processes but occurred without a reduction in the cellular growth rate. This mismatch is probably explained by a higher rate of macromolecule secretion in hESCs, on the basis of evidence from electron microscopy and an analysis of conditioned media. Taken together, our developmental model provides an understanding of the metabolic transition from hESCs to more quiescent somatic cell types, and supports important roles for mitochondria and secretion in hESC biology.
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Affiliation(s)
- Matthew J Birket
- Buck Institute for Age Research, 8001 Redwood Blvd, Novato, CA 94945, USA
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671
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Baxley SE, Jiang W, Serra R. Misexpression of wingless-related MMTV integration site 5A in mouse mammary gland inhibits the milk ejection response and regulates connexin43 phosphorylation. Biol Reprod 2011; 85:907-15. [PMID: 21753195 DOI: 10.1095/biolreprod.111.091645] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Wingless-related MMTV integration site 5A (Wnt5a) is a noncanonical signaling WNT that is expressed in every stage of mouse mammary gland development except lactation. Using slow release pellets containing WNT5A as well as Wnt5a-null tissue, we previously showed that WNT5A acts to limit mammary development. Here, we generated transgenic mice that overexpress WNT5A in the mammary epithelium using the mouse mammary tumor virus promoter (M5a mice). Lactation was impaired in two high WNT5A-expressing lines. Lactation defects could not be explained by differences in apoptosis, lineage differentiation, milk synthesis, or secretion. Instead, misexpression of WNT5A led to a failure in oxytocin response and milk ejection. Noting the similarity between the M5a phenotype and that of mice with a mutation in connexin43 (Cx43; official gene symbol Gja1), we examined Cx43 phosphorylation and localization in M5a mice. In wild-type mice, Cx43 switched from a phosphorylated to a more hypophosphorylated form after parturition. In contrast, the phosphorylated form of Cx43 was maintained after parturition in M5a mice. Using a nontumorigenic breast cell line, MCF10A, we showed that, in addition to increasing the levels of phosphorylation of Cx43 on serine-368, ectopic expression of WNT5A reduced or blocked the amount of dye transferred between cells. In summary, we propose that WNT5A inhibits the response to oxytocin and prevents milk ejection through regulation of Cx43 function.
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Affiliation(s)
- Sarah E Baxley
- Department of Cell Biology, University of Alabama at Birmingham, Birmingham, Alabama, USA
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672
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Improvement of lentiviral transfer vectors using cis-acting regulatory elements for increased gene expression. Appl Microbiol Biotechnol 2011; 91:1581-91. [PMID: 21674167 DOI: 10.1007/s00253-011-3392-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 05/16/2011] [Accepted: 05/16/2011] [Indexed: 10/18/2022]
Abstract
Lentiviral vectors are an important tool for gene delivery in vivo and in vitro. The success of gene transfer approaches relies on high and stable levels of gene expression. To this end, several molecular strategies have been employed to manipulate these vectors towards improving gene expression in the targeted animal cells. Low gene expression can be accepted due to the weak transcription from the majority of available mammalian promoters; however, this obstacle can be in part overcome by the insertion of cis-acting elements that enhance gene expression in various expression contexts. In this work, we created different lentiviral vectors in which several posttranscriptional regulatory elements, namely the Woodchuck hepatitis posttranscriptional regulatory element (WPRE) and different specialized poly(A) termination sequences (BGH and SV40) were used to develop vectors leading to improved transgene expression. These vectors combine the advantages of restriction enzyme/ligation-independent cloning eliminating the instability and recombinogenic problems occurring from traditional cloning methods in lentiviral expression vectors and were tested by expressing GFP and the firefly Luciferase reporter gene from different cellular promoters in different cell lines. We show that the promoter activity varies between cell lines and is affected by the lentiviral genomic context. Moreover, we show that the combination of the WPRE element with the BGH poly(A) signal significantly enhances transgene expression. The vectors herein created can be easily modified and adapted without the need for extensive recloning making them a valuable tool for viral vector development.
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673
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Leblanc E, Trensz F, Haroun S, Drouin G, Bergeron E, Penton CM, Montanaro F, Roux S, Faucheux N, Grenier G. BMP-9-induced muscle heterotopic ossification requires changes to the skeletal muscle microenvironment. J Bone Miner Res 2011; 26:1166-77. [PMID: 21611960 DOI: 10.1002/jbmr.311] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Heterotopic ossification (HO) is defined as the formation of bone inside soft tissue. Symptoms include joint stiffness, swelling, and pain. Apart from the inherited form, the common traumatic form generally occurs at sites of injury in damaged muscles and is often associated with brain injury. We investigated bone morphogenetic protein 9 (BMP-9), which possesses a strong osteoinductive capacity, for its involvement in muscle HO physiopathology. We found that BMP-9 had an osteoinductive influence on mouse muscle resident stromal cells by increasing their alkaline phosphatase activity and bone-specific marker expression. Interestingly, BMP-9 induced HO only in damaged muscle, whereas BMP-2 promoted HO in skeletal muscle regardless of its state. The addition of the soluble form of the ALK1 protein (the BMP-9 receptor) significantly inhibited the osteoinductive potential of BMP-9 in cells and HO in damaged muscles. BMP-9 thus should be considered a candidate for involvement in HO physiopathology, with its activity depending on the skeletal muscle microenvironment.
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674
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Škalamera D, Ranall MV, Wilson BM, Leo P, Purdon AS, Hyde C, Nourbakhsh E, Grimmond SM, Barry SC, Gabrielli B, Gonda TJ. A high-throughput platform for lentiviral overexpression screening of the human ORFeome. PLoS One 2011; 6:e20057. [PMID: 21629697 PMCID: PMC3101218 DOI: 10.1371/journal.pone.0020057] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Accepted: 04/24/2011] [Indexed: 11/22/2022] Open
Abstract
In response to the growing need for functional analysis of the human genome, we have developed a platform for high-throughput functional screening of genes overexpressed from lentiviral vectors. Protein-coding human open reading frames (ORFs) from the Mammalian Gene Collection were transferred into lentiviral expression vector using the highly efficient Gateway recombination cloning. Target ORFs were inserted into the vector downstream of a constitutive promoter and upstream of an IRES controlled GFP reporter, so that their transfection, transduction and expression could be monitored by fluorescence. The expression plasmids and viral packaging plasmids were combined and transfected into 293T cells to produce virus, which was then used to transduce the screening cell line. We have optimised the transfection and transduction procedures so that they can be performed using robotic liquid handling systems in arrayed 96-well microplate, one-gene-per-well format, without the need to concentrate the viral supernatant. Since lentiviruses can infect both dividing and non-dividing cells, this system can be used to overexpress human ORFs in a broad spectrum of experimental contexts. We tested the platform in a 1990 gene pilot screen for genes that can increase proliferation of the non-tumorigenic mammary epithelial cell line MCF-10A after removal of growth factors. Transduced cells were labelled with the nucleoside analogue 5-ethynyl-2′-deoxyuridine (EdU) to detect cells progressing through S phase. Hits were identified using high-content imaging and statistical analysis and confirmed with vectors using two different promoters (CMV and EF1α). The screen demonstrates the reliability, versatility and utility of our screening platform, and identifies novel cell cycle/proliferative activities for a number of genes.
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Affiliation(s)
- Dubravka Škalamera
- University of Queensland Diamantina Institute, Princess Alexandra Hospital, Brisbane, Queensland, Australia.
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675
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Yuan Z, Qiao C, Hu P, Li J, Xiao X. A versatile adeno-associated virus vector producer cell line method for scalable vector production of different serotypes. Hum Gene Ther 2011; 22:613-24. [PMID: 21186998 PMCID: PMC3081441 DOI: 10.1089/hum.2010.241] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2010] [Accepted: 12/25/2010] [Indexed: 02/04/2023] Open
Abstract
Application of adeno-associated virus (AAV) vector in large animal studies and clinical trials often requires high-titer and high-potency vectors. A number of currently used vector production methods, based on either transient transfection or helper virus infection of cell lines, have their advantages and limitations. We previously developed a 293-cell-based producer cell line method for high-titer and high-potency AAV2 vectors. Similar to several other methods, however, it requires multiple cloning steps for the vector and packaging plasmids and a two-step transfection and selection for stable cell lines. Here we report a simplified method with several key improvements and advantages: (1) a one-step cloning of AAV vector cassette into the serotype-specific packaging plasmid; (2) a single plasmid transfection and selection for stable AAV vector producer cell lines; (3) high vector yields of different serotypes, e.g., AAV2, 8, and 9, upon infection with an E1A/E1B-deleted helper adenovirus; (4) efficient packaging of both single-stranded and double-stranded (self-complementary) AAV vectors; and (5) efficient packaging of large AAV cassettes such as a mini-dystrophin vector (5.0 kb). All cell lines were stable with growth rates identical to the parental 293 cells. The vector yields were consistent among serotypes, with 5 × 10(13) to 8 × 10(13) vector genome particles per Nunc cell factory (equivalent to 40 15-cm plates). The vectors showed high potency for in vitro and in vivo transduction. In conclusion, the simple and versatile AAV producer cell line method can be useful for large scale AAV vector production in preclinical and clinical studies.
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Affiliation(s)
- Zhenhua Yuan
- Division of Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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676
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Mohapatra S, Kawahara M, Khan IS, Yannone SM, Povirk LF. Restoration of G1 chemo/radioresistance and double-strand-break repair proficiency by wild-type but not endonuclease-deficient Artemis. Nucleic Acids Res 2011; 39:6500-10. [PMID: 21531702 PMCID: PMC3159448 DOI: 10.1093/nar/gkr257] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Deficiency in Artemis is associated with lack of V(D)J recombination, sensitivity to radiation and radiomimetic drugs, and failure to repair a subset of DNA double-strand breaks (DSBs). Artemis harbors an endonuclease activity that trims both 5′- and 3′-ends of DSBs. To examine whether endonucleolytic trimming of terminally blocked DSBs by Artemis is a biologically relevant function, Artemis-deficient fibroblasts were stably complemented with either wild-type Artemis or an endonuclease-deficient D165N mutant. Wild-type Artemis completely restored resistance to γ-rays, bleomycin and neocarzinostatin, and also restored DSB-repair proficiency in G0/G1 phase as measured by pulsed-field gel electrophoresis and repair focus resolution. In contrast, cells expressing the D165N mutant, even at very high levels, remained as chemo/radiosensitive and repair deficient as the parental cells, as evidenced by persistent γ-H2AX, 53BP1 and Mre11 foci that slowly increased in size and ultimately became juxtaposed with promyelocytic leukemia protein nuclear bodies. In normal fibroblasts, overexpression of wild-type Artemis increased radioresistance, while D165N overexpression conferred partial repair deficiency following high-dose radiation. Restoration of chemo/radioresistance by wild-type, but not D165N Artemis suggests that the lack of endonucleolytic trimming of DNA ends is the principal cause of sensitivity to double-strand cleaving agents in Artemis-deficient cells.
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Affiliation(s)
- Susovan Mohapatra
- Department of Pharmacology and Toxicology, Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
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677
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Radulovich N, Leung L, Tsao MS. Modified gateway system for double shRNA expression and Cre/lox based gene expression. BMC Biotechnol 2011; 11:24. [PMID: 21418658 PMCID: PMC3070635 DOI: 10.1186/1472-6750-11-24] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Accepted: 03/22/2011] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND The growing need for functional studies of genes has set the stage for the development of versatile tools for genetic manipulations. RESULTS Aiming to provide tools for high throughput analysis of gene functions, we have developed a modified short hairpin RNA (shRNA) and gene expression system based on Gateway Technology. The system contains a series of entry and destination vectors that enables easy transfer of shRNA or cDNA into lentiviral expression systems with a variety of selection or marker genes (i.e. puromycin, hygromycin, green fluorescent protein-EGFP, yellow fluorescent protein-YFP and red fluorescent protein-dsRed2). Our shRNA entry vector pENTR.hU6.hH1 containing two tandem human shRNA expression promoters, H1 and U6, was capable of co-expressing two shRNA sequences simultaneously. The entry vector for gene overexpression, pENTR.CMV.ON was constructed to contain CMV promoter with a multiple cloning site flanked by loxP sites allowing for subsequent Cre/lox recombination. Both shRNA and cDNA expression vectors also contained attL sites necessary for recombination with attR sites in our destination expression vectors. As proof of principle we demonstrate the functionality and efficiency of this system by testing expression of several cDNA and shRNA sequences in a number of cell lines. CONCLUSION Our system is a valuable addition to already existing library of Gateway based vectors and can be an essential tool for many aspects of gene functional studies.
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Affiliation(s)
- Nikolina Radulovich
- University Health Network, Ontario Cancer Institute/Princess Margaret Hospital Site, 610 University Ave., Toronto, Ontario, M5G 2M9, Canada
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Medical Sciences Buildings, 1 King's College Circle, Toronto, Ontario, M5 S 1A8, Canada
| | - Lisa Leung
- University Health Network, Ontario Cancer Institute/Princess Margaret Hospital Site, 610 University Ave., Toronto, Ontario, M5G 2M9, Canada
- Department of Medical Biophysics, University Health Network, Ontario Cancer Institute/Princess Margaret Hospital Site, 610 University Ave., Toronto, Ontario, M5G 2M9, Canada
| | - Ming-Sound Tsao
- University Health Network, Ontario Cancer Institute/Princess Margaret Hospital Site, 610 University Ave., Toronto, Ontario, M5G 2M9, Canada
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Medical Sciences Buildings, 1 King's College Circle, Toronto, Ontario, M5 S 1A8, Canada
- Department of Medical Biophysics, University Health Network, Ontario Cancer Institute/Princess Margaret Hospital Site, 610 University Ave., Toronto, Ontario, M5G 2M9, Canada
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678
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p38MAPK is a novel DNA damage response-independent regulator of the senescence-associated secretory phenotype. EMBO J 2011; 30:1536-48. [PMID: 21399611 PMCID: PMC3102277 DOI: 10.1038/emboj.2011.69] [Citation(s) in RCA: 681] [Impact Index Per Article: 52.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Accepted: 02/18/2011] [Indexed: 12/11/2022] Open
Abstract
Cellular senescence suppresses cancer by forcing potentially oncogenic cells into a permanent cell cycle arrest. Senescent cells also secrete growth factors, proteases, and inflammatory cytokines, termed the senescence-associated secretory phenotype (SASP). Much is known about pathways that regulate the senescence growth arrest, but far less is known about pathways that regulate the SASP. We previously showed that DNA damage response (DDR) signalling is essential, but not sufficient, for the SASP, which is restrained by p53. Here, we delineate another crucial SASP regulatory pathway and its relationship to the DDR and p53. We show that diverse senescence-inducing stimuli activate the stress-inducible kinase p38MAPK in normal human fibroblasts. p38MAPK inhibition markedly reduced the secretion of most SASP factors, constitutive p38MAPK activation was sufficient to induce an SASP, and p53 restrained p38MAPK activation. Further, p38MAPK regulated the SASP independently of the canonical DDR. Mechanistically, p38MAPK induced the SASP largely by increasing NF-κB transcriptional activity. These findings assign p38MAPK a novel role in SASP regulation--one that is necessary, sufficient, and independent of previously described pathways.
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679
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Peter CJ, Evans M, Thayanithy V, Taniguchi-Ishigaki N, Bach I, Kolpak A, Bassell GJ, Rossoll W, Lorson CL, Bao ZZ, Androphy EJ. The COPI vesicle complex binds and moves with survival motor neuron within axons. Hum Mol Genet 2011; 20:1701-11. [PMID: 21300694 DOI: 10.1093/hmg/ddr046] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Spinal muscular atrophy (SMA), an inherited disease of motor neuron dysfunction, results from insufficient levels of the survival motor neuron (SMN) protein. Movement of the SMN protein as granules within cultured axons suggests that the pathogenesis of SMA may involve defects in neuronal transport, yet the nature of axon transport vesicles remains enigmatic. Here we show that SMN directly binds to the α-subunit of the coat protein I (COPI) vesicle coat protein. The α-COP protein co-immunoprecipitates with SMN, small nuclear ribonucleoprotein-associated assembly factors and β-actin mRNA. Although typically Golgi associated, in neuronal cells α-COP localizes to lamellipodia and growth cones and moves within the axon, with a subset of these granules traveling together with SMN. Depletion of α-COP resulted in mislocalization of SMN and actin at the leading edge at the lamellipodia. We propose that neurons utilize the Golgi-associated COPI vesicle to deliver cargoes necessary for motor neuron integrity and function.
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Affiliation(s)
- Cyril Jayakumar Peter
- Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
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680
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Rodier F, Muñoz DP, Teachenor R, Chu V, Le O, Bhaumik D, Coppé JP, Campeau E, Beauséjour CM, Kim SH, Davalos AR, Campisi J. DNA-SCARS: distinct nuclear structures that sustain damage-induced senescence growth arrest and inflammatory cytokine secretion. J Cell Sci 2011; 124:68-81. [PMID: 21118958 PMCID: PMC3001408 DOI: 10.1242/jcs.071340] [Citation(s) in RCA: 372] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/23/2010] [Indexed: 12/19/2022] Open
Abstract
DNA damage can induce a tumor suppressive response termed cellular senescence. Damaged senescent cells permanently arrest growth, secrete inflammatory cytokines and other proteins and harbor persistent nuclear foci that contain DNA damage response (DDR) proteins. To understand how persistent damage foci differ from transient foci that mark repairable DNA lesions, we identify sequential events that differentiate transient foci from persistent foci, which we term 'DNA segments with chromatin alterations reinforcing senescence' (DNA-SCARS). Unlike transient foci, DNA-SCARS associate with PML nuclear bodies, lack the DNA repair proteins RPA and RAD51, lack single-stranded DNA and DNA synthesis and accumulate activated forms of the DDR mediators CHK2 and p53. DNA-SCARS form independently of p53, pRB and several other checkpoint and repair proteins but require p53 and pRb to trigger the senescence growth arrest. Importantly, depletion of the DNA-SCARS-stabilizing component histone H2AX did not deplete 53BP1 from DNA-SCARS but diminished the presence of MDC1 and activated CHK2. Furthermore, depletion of H2AX reduced both the p53-dependent senescence growth arrest and p53-independent cytokine secretion. DNA-SCARS were also observed following severe damage to multiple human cell types and mouse tissues, suggesting that they can be used in combination with other markers to identify senescent cells. Thus, DNA-SCARS are dynamically formed distinct structures that functionally regulate multiple aspects of the senescent phenotype.
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Affiliation(s)
- Francis Rodier
- Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA
- The Buck Institute for Age Research, 8001 Redwood Boulevard, Novato, CA 94945, USA
| | - Denise P. Muñoz
- Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA
- The Buck Institute for Age Research, 8001 Redwood Boulevard, Novato, CA 94945, USA
| | - Robert Teachenor
- Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA
| | - Victoria Chu
- Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA
| | - Oanh Le
- CHU Ste-Justine, Département de Pharmacologie, Université de Montréal, 3175 Cote Ste-Catherine, Montreal, QC H3T 1C5, Canada
| | - Dipa Bhaumik
- The Buck Institute for Age Research, 8001 Redwood Boulevard, Novato, CA 94945, USA
| | - Jean-Philippe Coppé
- Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA
- The Buck Institute for Age Research, 8001 Redwood Boulevard, Novato, CA 94945, USA
| | - Eric Campeau
- Program in Gene Function and Expression, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - Christian M. Beauséjour
- CHU Ste-Justine, Département de Pharmacologie, Université de Montréal, 3175 Cote Ste-Catherine, Montreal, QC H3T 1C5, Canada
| | - Sahn-Ho Kim
- Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA
| | - Albert R. Davalos
- Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA
- The Buck Institute for Age Research, 8001 Redwood Boulevard, Novato, CA 94945, USA
| | - Judith Campisi
- Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA
- The Buck Institute for Age Research, 8001 Redwood Boulevard, Novato, CA 94945, USA
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681
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Banerjee D, Mandal SM, Das A, Hegde ML, Das S, Bhakat KK, Boldogh I, Sarkar PS, Mitra S, Hazra TK. Preferential repair of oxidized base damage in the transcribed genes of mammalian cells. J Biol Chem 2010; 286:6006-16. [PMID: 21169365 DOI: 10.1074/jbc.m110.198796] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Preferential repair of bulky DNA adducts from the transcribed genes via nucleotide excision repair is well characterized in mammalian cells. However, definitive evidence is lacking for similar repair of oxidized bases, the major endogenous DNA lesions. Here we show that the oxidized base-specific human DNA glycosylase NEIL2 associates with RNA polymerase II and the transcriptional regulator heterogeneous nuclear ribonucleoprotein-U (hnRNP-U), both in vitro and in cells. NEIL2 immunocomplexes from cell extracts preferentially repaired the mutagenic cytosine oxidation product 5-hydroxyuracil in the transcribed strand. In a reconstituted system, we also observed NEIL2-initiated transcription-dependent base excision repair of 5-hydroxyuracil in the transcribed strand, with hnRNP-U playing a critical role. Chromatin immunoprecipitation/reimmunoprecipitation studies showed association of NEIL2, RNA polymerase II, and hnRNP-U on transcribed but not on transcriptionally silent genes. Furthermore, NEIL2-depleted cells accumulated more DNA damage in active than in silent genes. These results strongly support the preferential role of NEIL2 in repairing oxidized bases in the transcribed genes of mammalian cells.
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Affiliation(s)
- Dibyendu Banerjee
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas 77555, USA
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682
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Barrès V, Ouellet V, Lafontaine J, Tonin PN, Provencher DM, Mes-Masson AM. An essential role for Ran GTPase in epithelial ovarian cancer cell survival. Mol Cancer 2010; 9:272. [PMID: 20942967 PMCID: PMC2964620 DOI: 10.1186/1476-4598-9-272] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Accepted: 10/13/2010] [Indexed: 12/03/2022] Open
Abstract
Background We previously identified that Ran protein, a member of the Ras GTPase family, is highly expressed in high grade and high stage serous epithelial ovarian cancers, and that its overexpression is associated with a poor prognosis. Ran is known to contribute to both nucleocytoplasmic transport and cell cycle progression, but its role in ovarian cancer is not well defined. Results Using a lentivirus-based tetracycline-inducible shRNA approach, we show that downregulation of Ran expression in aggressive ovarian cancer cell lines affects cellular proliferation by inducing a caspase-3 associated apoptosis. Using a xenograft tumor assay, we demonstrate that depletion of Ran results in decreased tumorigenesis, and eventual tumor formation is associated with tumor cells that express Ran protein. Conclusion Our results suggest a role for Ran in ovarian cancer cell survival and tumorigenicity and suggest that this critical GTPase may be suitable as a therapeutic target.
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Affiliation(s)
- Véronique Barrès
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal/Institut du cancer de Montréal,1560 Sherbrooke Est, Montreal H2L 4M1, Canada
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683
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Bazarov AV, van Sluis M, Hines C, Bassett E, Beliveau A, Campeau E, Mukhopadhyay R, Lee WJ, Melodyev S, Zaslavsky Y, Lee L, Rodier F, Chicas A, Lowe SW, Benhattar J, Ren B, Campisi J, Yaswen P. p16(INK4a) -mediated suppression of telomerase in normal and malignant human breast cells. Aging Cell 2010; 9:736-46. [PMID: 20569236 PMCID: PMC2941554 DOI: 10.1111/j.1474-9726.2010.00599.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The cyclin-dependent kinase inhibitor p16(INK4a) (CDKN2A) is an important tumor suppressor gene frequently inactivated in human tumors. p16 suppresses the development of cancer by triggering an irreversible arrest of cell proliferation termed cellular senescence. Here, we describe another anti-oncogenic function of p16 in addition to its ability to halt cell cycle progression. We show that transient expression of p16 stably represses the hTERT gene, encoding the catalytic subunit of telomerase, in both normal and malignant breast epithelial cells. Short-term p16 expression increases the amount of histone H3 trimethylated on lysine 27 (H3K27) bound to the hTERT promoter, resulting in transcriptional silencing, likely mediated by polycomb complexes. Our results indicate that transient p16 exposure may prevent malignant progression in dividing cells by irreversible repression of genes, such as hTERT, whose activity is necessary for extensive self-renewal.
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Affiliation(s)
- Alexey V. Bazarov
- Department of Laboratory Medicine, University of California, San Francisco, CA, USA
| | - Marjolein van Sluis
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Curtis Hines
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Ekaterina Bassett
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Alain Beliveau
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Eric Campeau
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | | | - Won Jae Lee
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Sonya Melodyev
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Yuri Zaslavsky
- Department of Laboratory Medicine, University of California, San Francisco, CA, USA
| | - Leonard Lee
- Ludwig Institute For Cancer Research, University of California, San Diego, CA, USA
| | - Francis Rodier
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Buck Institute for Age Research, Novato, CA, USA
| | - Agustin Chicas
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, USA
| | - Scott W. Lowe
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, USA
| | - Jean Benhattar
- Institute of Pathology, University of Lausanne, 1011 Lausanne, Switzerland
| | - Bing Ren
- Ludwig Institute For Cancer Research, University of California, San Diego, CA, USA
| | - Judith Campisi
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Buck Institute for Age Research, Novato, CA, USA
| | - Paul Yaswen
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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684
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Chernikova SB, Dorth JA, Razorenova OV, Game JC, Brown JM. Deficiency in Bre1 impairs homologous recombination repair and cell cycle checkpoint response to radiation damage in mammalian cells. Radiat Res 2010; 174:558-65. [PMID: 20738173 DOI: 10.1667/rr2184.1] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The pathway involving Bre1-dependent monoubiquitination of histone H2B lysine 123, which leads to Dot1-dependent methylation of histone H3 lysine 79 (H3K79me2), has been implicated in survival after exposure to ionizing radiation in Saccharomyces cerevisiae. We found that depletion of mammalian homologs of Bre1 compromises the response to ionizing radiation, leading to increased radiosensitivity and a G(2)/M checkpoint defect. The deficiency in Bre1a/b function was also associated with increased sensitivity to crosslinking drugs and defective formation of Rad51 foci in mouse cells, suggesting a defect in homologous recombinational repair analogous to that seen in Saccharomyces. In budding yeast, H3K79me2 is important for the recruitment of the checkpoint signaling protein Rad9 to sites of double-strand breaks (DSBs). However, in mammalian cells, 53BP1 (the Rad9 ortholog) in addition to H3K79me2 recognizes a different residue, H4K20me2, and some studies argue that it is H4K20me2 and not H3K79me2 that is the preferred target for 53BP1. We show here that depletion of Bre1b specifically reduced dimethylation of H3K79 without affecting dimethylation of H4K20. Thus our data suggest that the observed defects in the radiation response of Bre1a/b-deficient cells are associated with reduced H3K79me2 and not with H4K20me2.
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Affiliation(s)
- Sophia B Chernikova
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305-5152, USA
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685
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Cohet N, Stewart KM, Mudhasani R, Asirvatham AJ, Mallappa C, Imbalzano KM, Weaver VM, Imbalzano AN, Nickerson JA. SWI/SNF chromatin remodeling enzyme ATPases promote cell proliferation in normal mammary epithelial cells. J Cell Physiol 2010; 223:667-78. [PMID: 20333683 DOI: 10.1002/jcp.22072] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The ATPase subunits of the SWI/SNF chromatin remodeling enzymes, Brahma (BRM) and Brahma-related gene 1 (BRG1), can induce cell cycle arrest in BRM and BRG1 deficient tumor cell lines, and mice heterozygous for Brg1 are pre-disposed to breast tumors, implicating loss of BRG1 as a mechanism for unregulated cell proliferation. To test the hypothesis that loss of BRG1 can contribute to breast cancer, we utilized RNA interference to reduce the amounts of BRM or BRG1 protein in the nonmalignant mammary epithelial cell line, MCF-10A. When grown in reconstituted basement membrane (rBM), these cells develop into acini that resemble the lobes of normal breast tissue. Contrary to expectations, knockdown of either BRM or BRG1 resulted in an inhibition of cell proliferation in monolayer cultures. This inhibition was strikingly enhanced in three-dimensional rBM culture, although some BRM-depleted cells were later able to resume proliferation. Cells did not arrest in any specific stage of the cell cycle; instead, the cell cycle length increased by approximately 50%. Thus, SWI/SNF ATPases promote cell cycle progression in nonmalignant mammary epithelial cells.
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Affiliation(s)
- Nathalie Cohet
- Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
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686
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Ghosh R, Lipson KL, Sargent KE, Mercurio AM, Hunt JS, Ron D, Urano F. Transcriptional regulation of VEGF-A by the unfolded protein response pathway. PLoS One 2010; 5:e9575. [PMID: 20221394 PMCID: PMC2833197 DOI: 10.1371/journal.pone.0009575] [Citation(s) in RCA: 189] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Accepted: 02/15/2010] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Angiogenesis is crucial to many physiological and pathological processes including development and cancer cell survival. Vascular endothelial growth factor-A (VEGFA) is the predominant mediator of angiogenesis in the VEGF family. During development, adverse environmental conditions like nutrient deprivation, hypoxia and increased protein secretion occur. IRE1alpha, PERK, and ATF6alpha, master regulators of the unfolded protein response (UPR), are activated under these conditions and are proposed to have a role in mediating angiogenesis. PRINCIPAL FINDINGS Here we show that IRE1alpha, PERK, and ATF6alpha powerfully regulate VEGFA mRNA expression under various stress conditions. In Ire1alpha(-/-) and Perk(-/-) mouse embryonic fibroblasts and ATF6alpha-knockdown HepG2 cells, induction of VEGFA mRNA by endoplasmic reticulum stress is attenuated as compared to control cells. Embryonic lethality of Ire1alpha-/- mice is due to the lack of VEGFA induction in labyrinthine trophoblast cells of the developing placenta. Rescue of IRE1alpha and PERK in Ire1alpha(-/-) and Perk(-/-) cells respectively, prevents VEGFA mRNA attenuation. We further report that the induction of VEGFA by IRE1alpha, PERK and ATF6 involves activation of transcription factors, spliced-XBP-1, ATF4 and cleaved ATF6 respectively. CONCLUSIONS/SIGNIFICANCE Our results reveal that the IRE1alpha-XBP-1, PERK-ATF4, and ATF6alpha pathways constitute novel upstream regulatory pathways of angiogenesis by modulating VEGF transcription. Activation of these pathways helps the rapidly growing cells to obtain sufficient nutrients and growth factors for their survival under the prevailing hostile environmental conditions. These results establish an important role of the UPR in angiogenesis.
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Affiliation(s)
- Rajarshi Ghosh
- Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Kathryn L. Lipson
- Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Department of Physical and Biological Sciences, Western New England College, Springfield, Massachusetts, United States of America
| | - Karen E. Sargent
- Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Arthur M. Mercurio
- Department of Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Joan S. Hunt
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - David Ron
- Skirball Institute, New York University School of Medicine, New York, New York, United States of America
- Institute of Metabolic Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Fumihiko Urano
- Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
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687
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Fonseca SG, Ishigaki S, Oslowski CM, Lu S, Lipson KL, Ghosh R, Hayashi E, Ishihara H, Oka Y, Permutt MA, Urano F. Wolfram syndrome 1 gene negatively regulates ER stress signaling in rodent and human cells. J Clin Invest 2010; 120:744-55. [PMID: 20160352 DOI: 10.1172/jci39678] [Citation(s) in RCA: 292] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Accepted: 01/06/2010] [Indexed: 12/15/2022] Open
Abstract
Wolfram syndrome is an autosomal-recessive disorder characterized by insulin-dependent diabetes mellitus, caused by nonautoimmune loss of beta cells, and neurological dysfunctions. We have previously shown that mutations in the Wolfram syndrome 1 (WFS1) gene cause Wolfram syndrome and that WFS1 has a protective function against ER stress. However, it remained to be determined how WFS1 mitigates ER stress. Here we have shown in rodent and human cell lines that WFS1 negatively regulates a key transcription factor involved in ER stress signaling, activating transcription factor 6alpha (ATF6alpha), through the ubiquitin-proteasome pathway. WFS1 suppressed expression of ATF6alpha target genes and repressed ATF6alpha-mediated activation of the ER stress response element (ERSE) promoter. Moreover, WFS1 stabilized the E3 ubiquitin ligase HRD1, brought ATF6alpha to the proteasome, and enhanced its ubiquitination and proteasome-mediated degradation, leading to suppression of ER stress signaling. Consistent with these data, beta cells from WFS1-deficient mice and lymphocytes from patients with Wolfram syndrome exhibited dysregulated ER stress signaling through upregulation of ATF6alpha and downregulation of HRD1. These results reveal a role for WFS1 in the negative regulation of ER stress signaling and in the pathogenesis of diseases involving chronic, unresolvable ER stress, such as pancreatic beta cell death in diabetes.
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Affiliation(s)
- Sonya G Fonseca
- Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, MA 01605-2324, USA
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688
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Ishigaki S, Fonseca SG, Oslowski CM, Jurczyk A, Shearstone JR, Zhu LJ, Permutt MA, Greiner DL, Bortell R, Urano F. AATF mediates an antiapoptotic effect of the unfolded protein response through transcriptional regulation of AKT1. Cell Death Differ 2009; 17:774-86. [PMID: 19911006 PMCID: PMC2854298 DOI: 10.1038/cdd.2009.175] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Endoplasmic reticulum (ER) stress-mediated cell death plays an important
role in the pathogenesis of chronic diseases including diabetes and
neurodegeneration. Although pro-apoptotic programs activated by ER stress have
been extensively studied, identification and characterization of anti-apoptotic
programs that counteract ER stress is currently incomplete. Through the gene
expression profiling of β-cells lacking WFS1, a causative gene for
Wolfram syndrome, we have discovered a novel anti-apoptotic gene of the unfolded
protein response (UPR), apoptosis antagonizing transcription factor (AATF). Here
we study the regulation of AATF, identify its target genes, and determine the
basis for its anti-apoptotic activities in response to ER stress. We show that
AATF is induced by ER stress through the PERK-eIF2α pathway and
transcriptionally activates the Akt1 gene through Stat3, which sustains Akt1
activation and promotes cell survival. Ectopic expression of AATF or a
constitutively active form of AKT1 confers on cells resistance to ER
stress-mediated cell death, whereas RNAi-mediated knockdown of AATF or AKT1
renders cells sensitive to ER stress. We also discovered positive crosstalk
between the AATF and WFS1 signaling pathways. Thus, WFS1-deficiency or
AATF-deficiency mediates a self-perpetuating cycle of cell death. Our results
reveal a novel anti-apoptotic program relevant to treatment for diseases caused
by ER stress-mediated cell death.
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Affiliation(s)
- S Ishigaki
- University of Massachusetts Medical School, Worcester, 01605-2324, USA.
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