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Fong BC, Chakroun I, Iqbal MA, Paul S, Bastasic J, O’Neil D, Yakubovich E, Bejjani AT, Ahmadi N, Carter A, Clark A, Leone G, Park DS, Ghanem N, Vandenbosch R, Slack RS. The Rb/E2F axis is a key regulator of the molecular signatures instructing the quiescent and activated adult neural stem cell state. Cell Rep 2022; 41:111578. [DOI: 10.1016/j.celrep.2022.111578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 08/11/2022] [Accepted: 10/07/2022] [Indexed: 11/06/2022] Open
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2
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Omais S, Hilal RN, Halaby NN, Jaafar C, Ghanem N. Aging entails distinct requirements for Rb at maintaining adult neurogenesis. AGING BRAIN 2022; 2:100041. [PMID: 36908894 PMCID: PMC9997174 DOI: 10.1016/j.nbas.2022.100041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 04/13/2022] [Accepted: 04/28/2022] [Indexed: 10/18/2022] Open
Abstract
Cell cycle proteins play essential roles in regulating embryonic and adult neurogenesis in the mammalian brain. A key example is the Retinoblastoma protein (Rb) whose loss disrupts the whole neurogenic program during brain development, but only results in increased progenitor proliferation in the adult subventricular zone (SVZ) and compromised long-term neuronal survival in the adult olfactory bulb (OB). Whether this holds true of neurogenesis in the aged brain remains unknown. In this study, we find no evidence of irregular proliferation or early commitment defects in the mid-aged (12-month-old) and old-aged (20-month-old) SVZ following tamoxifen-inducible Rb knockout (Rb iKO) in mice. However, we highlight a striking defect in early maturation of Rb-deficient migrating neuroblasts along the rostral migratory stream (RMS), followed by massive decline in neuronal generation inside the aged OB. In the absence of Rb, we also show evidence of incomplete cell cycle re-entry (CCE) along with DNA damage in the young OB, while we find a similar trend towards CCE but no clear signs of DNA damage or neurodegenerative signatures (pTau or Synuclein accumulation) in the aged OB. However, such phenotype could be masked by the severe maturation defect reported above in addition to the natural decline in adult neurogenesis with age. Overall, we show that Rb is required to prevent CCE and DNA damage in adult-born OB neurons, hence maintain neuronal survival. Moreover, while loss of Rb alone is insufficient to trigger seeding of neurotoxic species, this study reveals age-dependent non-monotonic dynamics in regulating neurogenesis by Rb.
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Affiliation(s)
- Saad Omais
- Department of Biology, American University of Beirut, Lebanon
| | - Rouba N Hilal
- Department of Biology, American University of Beirut, Lebanon
| | - Nour N Halaby
- Department of Biology, American University of Beirut, Lebanon
| | - Carine Jaafar
- Department of Biology, American University of Beirut, Lebanon
| | - Noël Ghanem
- Department of Biology, American University of Beirut, Lebanon
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3
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Ho NTT, Rahane CS, Pramanik S, Kim PS, Kutzner A, Heese K. FAM72, Glioblastoma Multiforme (GBM) and Beyond. Cancers (Basel) 2021; 13:cancers13051025. [PMID: 33804473 PMCID: PMC7957592 DOI: 10.3390/cancers13051025] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/18/2021] [Accepted: 02/22/2021] [Indexed: 12/15/2022] Open
Abstract
Simple Summary Glioblastoma multiforme (GBM) is a serious and aggressive cancer disease that has not allowed scientists to rest for decades. In this review, we consider the new gene pair |-SRGAP2–FAM72-| and discuss its role in the cell cycle and the possibility of defining new therapeutic approaches for the treatment of GBM and other cancers via this gene pair |-SRGAP2–FAM72-|. Abstract Neural stem cells (NSCs) offer great potential for regenerative medicine due to their excellent ability to differentiate into various specialized cell types of the brain. In the central nervous system (CNS), NSC renewal and differentiation are under strict control by the regulation of the pivotal SLIT-ROBO Rho GTPase activating protein 2 (SRGAP2)—Family with sequence similarity 72 (FAM72) master gene (i.e., |-SRGAP2–FAM72-|) via a divergent gene transcription activation mechanism. If the gene transcription control unit (i.e., the intergenic region of the two sub-gene units, SRGAP2 and FAM72) gets out of control, NSCs may transform into cancer stem cells and generate brain tumor cells responsible for brain cancer such as glioblastoma multiforme (GBM). Here, we discuss the surveillance of this |-SRGAP2–FAM72-| master gene and its role in GBM, and also in light of FAM72 for diagnosing various types of cancers outside of the CNS.
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Affiliation(s)
- Nguyen Thi Thanh Ho
- Graduate School of Biomedical Science and Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Korea;
| | - Chinmay Satish Rahane
- Maharashtra Institute of Medical Education and Research, Talegaon Dabhade, Maharashtra 410507, India;
| | - Subrata Pramanik
- Institute of Biotechnology, RWTH Aachen University, Worringerweg 3, 52074 Aachen, Germany;
| | - Pok-Son Kim
- Department of Mathematics, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 136-702, Korea;
| | - Arne Kutzner
- Department of Information Systems, College of Computer Science, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Korea;
| | - Klaus Heese
- Graduate School of Biomedical Science and Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Korea;
- Correspondence:
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4
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Zluhan-Martínez E, Pérez-Koldenkova V, Ponce-Castañeda MV, Sánchez MDLP, García-Ponce B, Miguel-Hernández S, Álvarez-Buylla ER, Garay-Arroyo A. Beyond What Your Retina Can See: Similarities of Retinoblastoma Function between Plants and Animals, from Developmental Processes to Epigenetic Regulation. Int J Mol Sci 2020; 21:E4925. [PMID: 32664691 PMCID: PMC7404004 DOI: 10.3390/ijms21144925] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 06/29/2020] [Accepted: 07/07/2020] [Indexed: 12/15/2022] Open
Abstract
The Retinoblastoma protein (pRb) is a key cell cycle regulator conserved in a wide variety of organisms. Experimental analysis of pRb's functions in animals and plants has revealed that this protein participates in cell proliferation and differentiation processes. In addition, pRb in animals and its orthologs in plants (RBR), are part of highly conserved protein complexes which suggest the possibility that analogies exist not only between functions carried out by pRb orthologs themselves, but also in the structure and roles of the protein networks where these proteins are involved. Here, we present examples of pRb/RBR participation in cell cycle control, cell differentiation, and in the regulation of epigenetic changes and chromatin remodeling machinery, highlighting the similarities that exist between the composition of such networks in plants and animals.
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Affiliation(s)
- Estephania Zluhan-Martínez
- Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Instituto de Ecología, Universidad Nacional Autónoma de Mexico, 3er Circuito Ext. Junto a J. Botánico, Ciudad Universitaria, UNAM 04510, Mexico; (E.Z.-M.); (M.d.l.P.S.); (B.G.-P.)
- Posgrado en Ciencias Biomédicas, Universidad Nacional Autónoma de México, Av. Universidad 3000, Coyoacán 04510, Mexico
| | - Vadim Pérez-Koldenkova
- Laboratorio Nacional de Microscopía Avanzada, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Av. Cuauhtémoc, 330. Col. Doctores, Alc. Cuauhtémoc 06720, Mexico;
| | - Martha Verónica Ponce-Castañeda
- Unidad de Investigación Médica en Enfermedades Infecciosas, Centro Médico Nacional SXXI, Instituto Mexicano del Seguro Social, Mexico City 06720, Mexico;
| | - María de la Paz Sánchez
- Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Instituto de Ecología, Universidad Nacional Autónoma de Mexico, 3er Circuito Ext. Junto a J. Botánico, Ciudad Universitaria, UNAM 04510, Mexico; (E.Z.-M.); (M.d.l.P.S.); (B.G.-P.)
| | - Berenice García-Ponce
- Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Instituto de Ecología, Universidad Nacional Autónoma de Mexico, 3er Circuito Ext. Junto a J. Botánico, Ciudad Universitaria, UNAM 04510, Mexico; (E.Z.-M.); (M.d.l.P.S.); (B.G.-P.)
| | - Sergio Miguel-Hernández
- Laboratorio de Citopatología Ambiental, Departamento de Morfología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Campus Zacatenco, Calle Wilfrido Massieu Esquina Cda, Manuel Stampa 07738, Mexico;
| | - Elena R. Álvarez-Buylla
- Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Instituto de Ecología, Universidad Nacional Autónoma de Mexico, 3er Circuito Ext. Junto a J. Botánico, Ciudad Universitaria, UNAM 04510, Mexico; (E.Z.-M.); (M.d.l.P.S.); (B.G.-P.)
| | - Adriana Garay-Arroyo
- Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Instituto de Ecología, Universidad Nacional Autónoma de Mexico, 3er Circuito Ext. Junto a J. Botánico, Ciudad Universitaria, UNAM 04510, Mexico; (E.Z.-M.); (M.d.l.P.S.); (B.G.-P.)
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5
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Naert T, Dimitrakopoulou D, Tulkens D, Demuynck S, Carron M, Noelanders R, Eeckhout L, Van Isterdael G, Deforce D, Vanhove C, Van Dorpe J, Creytens D, Vleminckx K. RBL1 (p107) functions as tumor suppressor in glioblastoma and small-cell pancreatic neuroendocrine carcinoma in Xenopus tropicalis. Oncogene 2020; 39:2692-2706. [PMID: 32001819 DOI: 10.1038/s41388-020-1173-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 01/13/2020] [Accepted: 01/20/2020] [Indexed: 11/09/2022]
Abstract
Alterations of the retinoblastoma and/or the p53 signaling network are associated with specific cancers such as high-grade astrocytoma/glioblastoma, small-cell lung cancer (SCLC), choroid plexus tumors, and small-cell pancreatic neuroendocrine carcinoma (SC-PaNEC). However, the intricate functional redundancy between RB1 and the related pocket proteins RBL1/p107 and RBL2/p130 in suppressing tumorigenesis remains poorly understood. Here we performed lineage-restricted parallel inactivation of rb1 and rbl1 by multiplex CRISPR/Cas9 genome editing in the true diploid Xenopus tropicalis to gain insight into this in vivo redundancy. We show that while rb1 inactivation is sufficient to induce choroid plexus papilloma, combined rb1 and rbl1 inactivation is required and sufficient to drive SC-PaNEC, retinoblastoma and astrocytoma. Further, using a novel Li-Fraumeni syndrome-mimicking tp53 mutant X. tropicalis line, we demonstrate increased malignancy of rb1/rbl1-mutant glioma towards glioblastoma upon concomitant inactivation of tp53. Interestingly, although clinical SC-PaNEC samples are characterized by abnormal p53 expression or localization, in the current experimental models, the tp53 status had little effect on the establishment and growth of SC-PaNEC, but may rather be essential for maintaining chromosomal stability. SCLC was only rarely observed in our experimental setup, indicating requirement of additional or alternative oncogenic insults. In conclusion, we used CRISPR/Cas9 to delineate the tumor suppressor properties of Rbl1, generating new insights in the functional redundancy within the retinoblastoma protein family in suppressing neuroendocrine pancreatic cancer and glioma/glioblastoma.
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Affiliation(s)
- Thomas Naert
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
- Cancer Research Institute Ghent, Ghent, Belgium
| | - Dionysia Dimitrakopoulou
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
- Cancer Research Institute Ghent, Ghent, Belgium
| | - Dieter Tulkens
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
- Cancer Research Institute Ghent, Ghent, Belgium
| | - Suzan Demuynck
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Marjolein Carron
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
- Center for Medical Genetics, Ghent University, Ghent, Belgium
| | - Rivka Noelanders
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Liza Eeckhout
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | | | - Dieter Deforce
- Laboratory for Pharmaceutical Biotechnology, Ghent University, Ghent, Belgium
| | - Christian Vanhove
- Cancer Research Institute Ghent, Ghent, Belgium
- Infinity lab, Ghent University Hospital, Ghent, Belgium
| | - Jo Van Dorpe
- Cancer Research Institute Ghent, Ghent, Belgium
- Department of Pathology, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - David Creytens
- Cancer Research Institute Ghent, Ghent, Belgium
- Department of Pathology, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Kris Vleminckx
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium.
- Cancer Research Institute Ghent, Ghent, Belgium.
- Center for Medical Genetics, Ghent University, Ghent, Belgium.
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6
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D'Angelo B, Astarita C, Boffo S, Massaro-Giordano M, Antonella Ianuzzi C, Caporaso A, Macaluso M, Giordano A. LPS-induced inflammatory response triggers cell cycle reactivation in murine neuronal cells through retinoblastoma proteins induction. Cell Cycle 2019; 16:2330-2336. [PMID: 28820328 DOI: 10.1080/15384101.2017.1363943] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Cell cycle reactivation in adult neurons is an early hallmark of neurodegeneration. The lipopolysaccharide (LPS) is a well-known pro-inflammatory factor that provokes neuronal cell death via glial cells activation. The retinoblastoma (RB) family includes RB1/p105, retinoblastoma-like 1 (RBL1/p107), and retinoblastoma-like 2 (Rb2/p130). Several studies have indicated that RB proteins exhibit tumor suppressor activities, and play a central role in cell cycle regulation. In this study, we assessed LPS-mediated inflammatory effect on cell cycle reactivation and apoptosis of neuronally differentiated cells. Also, we investigated whether the LPS-mediated inflammatory response can influence the function and expression of RB proteins. Our results showed that LPS challenges triggered cell cycle reactivation of differentiated neuronal cells, indicated by an accumulation of cells in S and G2/M phase. Furthermore, we found that LPS treatment also induced apoptotic death of neurons. Interestingly, we observed that LPS-mediated inflammatory effect on cell cycle re-entry and apoptosis was concomitant with the aberrant expression of RBL1/p107 and RB1/p105. To the best of our knowledge, our study is the first to indicate a role of LPS in inducing cell cycle re-entry and/or apoptosis of differentiated neuronal cells, perhaps through mechanisms altering the expression of specific members of RB family proteins. This study provides novel information on the biology of post-mitotic neurons and could help in identifying novel therapeutic targets to prevent de novo cell cycle reactivation and/or apoptosis of neurons undergoing neurodegenerative processes.
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Affiliation(s)
- Barbara D'Angelo
- a Sbarro Institute for Cancer Research and Molecular Medicine, Department of Biology, Center for Biotechnology, College of Science and Technology , Temple University , Philadelphia , PA , USA
| | - Carlo Astarita
- a Sbarro Institute for Cancer Research and Molecular Medicine, Department of Biology, Center for Biotechnology, College of Science and Technology , Temple University , Philadelphia , PA , USA.,b Department of Medicine, Surgery, and Neuroscience , University of Siena , Siena , Italy
| | - Silvia Boffo
- a Sbarro Institute for Cancer Research and Molecular Medicine, Department of Biology, Center for Biotechnology, College of Science and Technology , Temple University , Philadelphia , PA , USA
| | - Mina Massaro-Giordano
- c Department of Ophthalmology, Perelman School of Medicine , University of Pennsylvania , Philadelphia , PA
| | | | - Antonella Caporaso
- d Oncology Research Center of Mercogliano (CROM) , Istituto Nazionale Tumori-IRCCS-Fondazione G. Pascale , Naples , Italy
| | - Marcella Macaluso
- a Sbarro Institute for Cancer Research and Molecular Medicine, Department of Biology, Center for Biotechnology, College of Science and Technology , Temple University , Philadelphia , PA , USA
| | - Antonio Giordano
- a Sbarro Institute for Cancer Research and Molecular Medicine, Department of Biology, Center for Biotechnology, College of Science and Technology , Temple University , Philadelphia , PA , USA.,b Department of Medicine, Surgery, and Neuroscience , University of Siena , Siena , Italy
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7
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Urbach A, Witte OW. Divide or Commit - Revisiting the Role of Cell Cycle Regulators in Adult Hippocampal Neurogenesis. Front Cell Dev Biol 2019; 7:55. [PMID: 31069222 PMCID: PMC6491688 DOI: 10.3389/fcell.2019.00055] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Accepted: 03/28/2019] [Indexed: 12/21/2022] Open
Abstract
The adult dentate gyrus continuously generates new neurons that endow the brain with increased plasticity, helping to cope with changing environmental and cognitive demands. The process leading to the birth of new neurons spans several precursor stages and is the result of a coordinated series of fate decisions, which are tightly controlled by extrinsic signals. Many of these signals act through modulation of cell cycle (CC) components, not only to drive proliferation, but also for linage commitment and differentiation. In this review, we provide a comprehensive overview on key CC components and regulators, with emphasis on G1 phase, and analyze their specific functions in precursor cells of the adult hippocampus. We explore their role for balancing quiescence versus self-renewal, which is essential to maintain a lifelong pool of neural stem cells while producing new neurons “on demand.” Finally, we discuss available evidence and controversies on the impact of CC/G1 length on proliferation versus differentiation decisions.
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Affiliation(s)
- Anja Urbach
- Hans Berger Department of Neurology, Jena University Hospital, Jena, Germany
| | - Otto W Witte
- Hans Berger Department of Neurology, Jena University Hospital, Jena, Germany
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8
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Omais S, Jaafar C, Ghanem N. "Till Death Do Us Part": A Potential Irreversible Link Between Aberrant Cell Cycle Control and Neurodegeneration in the Adult Olfactory Bulb. Front Neurosci 2018; 12:144. [PMID: 29593485 PMCID: PMC5854681 DOI: 10.3389/fnins.2018.00144] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 02/22/2018] [Indexed: 12/13/2022] Open
Abstract
Adult neurogenesis (AN) is an ongoing developmental process that generates newborn neurons in the olfactory bulb (OB) and the hippocampus (Hi) throughout life and significantly contributes to brain plasticity. Adult neural stem and progenitor cells (aNSPCs) are relatively limited in number and fate and are spatially restricted to the subventricular zone (SVZ) and the subgranular zone (SGZ). During AN, the distinct roles played by cell cycle proteins extend beyond cell cycle control and constitute key regulatory mechanisms involved in neuronal maturation and survival. Importantly, aberrant cell cycle re-entry (CCE) in post-mitotic neurons has been strongly linked to the abnormal pathophysiology in rodent models of neurodegenerative diseases with potential implications on the etiology and progression of such diseases in humans. Here, we present an overview of AN in the SVZ-OB and olfactory epithelium (OE) in mice and humans followed by a comprehensive update of the distinct roles played by cell cycle proteins including major tumors suppressor genes in various steps during neurogenesis. We also discuss accumulating evidence underlining a strong link between abnormal cell cycle control, olfactory dysfunction and neurodegeneration in the adult and aging brain. We emphasize that: (1) CCE in post-mitotic neurons due to loss of cell cycle suppression and/or age-related insults as well as DNA damage can anticipate the development of neurodegenerative lesions and protein aggregates, (2) the age-related decline in SVZ and OE neurogenesis is associated with compensatory pro-survival mechanisms in the aging OB which are interestingly similar to those detected in Alzheimer's disease and Parkinson's disease in humans, and (3) the OB represents a well suitable model to study the early manifestation of age-related defects that may eventually progress into the formation of neurodegenerative lesions and, possibly, spread to the rest of the brain. Such findings may provide a novel approach to the modeling of neurodegenerative diseases in humans from early detection to progression and treatment as well.
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Affiliation(s)
- Saad Omais
- Department of Biology, American University of Beirut, Beirut, Lebanon
| | - Carine Jaafar
- Department of Biology, American University of Beirut, Beirut, Lebanon
| | - Noël Ghanem
- Department of Biology, American University of Beirut, Beirut, Lebanon
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9
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C-terminal deletion of NOTCH1 intracellular domain (N1 ICD) increases its stability but does not amplify and recapitulate N1 ICD-dependent signalling. Sci Rep 2017; 7:5034. [PMID: 28698562 PMCID: PMC5506007 DOI: 10.1038/s41598-017-05119-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 05/24/2017] [Indexed: 12/16/2022] Open
Abstract
Since the generation of a mouse strain conditionally expressing the active intracellular domain of Notch1 (N1ICD), many laboratories have exploited this model (RosaN1-ICD) to assess the impact of constitutive Notch1 signalling activation in normal and pathological processes. It should be underscored that Cre-recombination leads to the expression of a C-terminally truncated form of N1ICD (N1ICDdC) in the RosaN1-ICD mutant mice. Given that no studies were undertaken to delineate whether deletion of this region leaves intact N1ICD function, stable cell lines with single targeted integration of inducible N1ICD and N1ICDdC were generated. We found that C-terminal deletion of N1ICD stabilized the protein but did not promote the activity of Notch responsive promoters. Furthermore, despite higher expression levels, N1ICDdC failed to phenocopy N1ICD in the promotion of anchorage-independent growth. Our results thus suggest that the C-terminal region of N1ICD plays a role in shaping the Notch response. Therefore, it should be taken into consideration that N1ICD is truncated when interpreting phenotypes of RosaN1-ICD mutant mice.
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10
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Fong BC, Slack RS. RB: An essential player in adult neurogenesis. NEUROGENESIS 2017; 4:e1270382. [PMID: 28229086 DOI: 10.1080/23262133.2016.1270382] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 11/30/2016] [Accepted: 12/04/2016] [Indexed: 12/16/2022]
Abstract
The fundamental mechanisms underlying adult neurogenesis remain to be fully clarified. Members of the cell cycle machinery have demonstrated key roles in regulating adult neural stem cell (NSC) quiescence and the size of the adult-born neuronal population. The retinoblastoma protein, Rb, is known to possess CNS-specific requirements that are independent from its classical role as a tumor suppressor. The recent study by Vandenbosch et al. has clarified distinct requirements for Rb during adult neurogenesis, in the restriction of proliferation, as well as long-term adult-born neuronal survival. However, Rb is no longer believed to be the main cell cycle regulator maintaining the quiescence of adult NSCs. Future studies must consider Rb as part of a larger network of regulatory effectors, including the other members of the Rb family, p107 and p130. This will help elucidate the contribution of Rb and other pocket proteins in the context of adult neurogenesis, and define its crucial role in regulating the size and fate of the neurogenic niche.
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Affiliation(s)
- Bensun C Fong
- University of Ottawa Brain and Mind Research Institute, Department of Cellular & Molecular Medicine, University of Ottawa , Ottawa, ON, Canada
| | - Ruth S Slack
- University of Ottawa Brain and Mind Research Institute, Department of Cellular & Molecular Medicine, University of Ottawa , Ottawa, ON, Canada
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11
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Kyrousi C, Lygerou Z, Taraviras S. How a radial glial cell decides to become a multiciliated ependymal cell. Glia 2017; 65:1032-1042. [DOI: 10.1002/glia.23118] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 12/15/2016] [Accepted: 12/15/2016] [Indexed: 12/28/2022]
Affiliation(s)
- Christina Kyrousi
- Department of Physiology; School of Medicine, University of Patras; Patras 26504 Greece
| | - Zoi Lygerou
- Department of General Biology; School of Medicine, University of Patras; Patras 26504 Greece
| | - Stavros Taraviras
- Department of Physiology; School of Medicine, University of Patras; Patras 26504 Greece
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12
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Naser R, Vandenbosch R, Omais S, Hayek D, Jaafar C, Al Lafi S, Saliba A, Baghdadi M, Skaf L, Ghanem N. Role of the Retinoblastoma protein, Rb, during adult neurogenesis in the olfactory bulb. Sci Rep 2016; 6:20230. [PMID: 26847607 PMCID: PMC4742828 DOI: 10.1038/srep20230] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 12/23/2015] [Indexed: 12/15/2022] Open
Abstract
Adult neural stem cells (aNSCs) are relatively quiescent populations that give rise to distinct neuronal subtypes throughout life, yet, at a very low rate and restricted differentiation potential. Thus, identifying the molecular mechanisms that control their cellular expansion is critical for regeneration after brain injury. Loss of the Retinoblastoma protein, Rb, leads to several defects in cell cycle as well as neuronal differentiation and migration during brain development. Here, we investigated the role of Rb during adult neurogenesis in the olfactory bulb (OB) by inducing its temporal deletion in aNSCs and progenitors. Loss of Rb was associated with increased proliferation of adult progenitors in the subventricular zone (SVZ) and the rostral migratory stream (RMS) but did not alter self-renewal of aNSCs or neuroblasts subsequent migration and terminal differentiation. Hence, one month after their birth, Rb-null neuroblasts were able to differentiate into distinct subtypes of GABAergic OB interneurons but were gradually lost after 3 months. Similarly, Rb controlled aNSCs/progenitors proliferation in vitro without affecting their differentiation capacity. This enhanced SVZ/OB neurogenesis associated with loss of Rb was only transient and negatively affected by increased apoptosis indicating a critical requirement for Rb in the long-term survival of adult-born OB interneurons.
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Affiliation(s)
- Rayan Naser
- Department of Biology, American University of Beirut, Lebanon
| | - Renaud Vandenbosch
- Department of Cellular and Molecular Medicine, University of Ottawa, Canada
| | - Saad Omais
- Department of Biology, American University of Beirut, Lebanon
| | - Dayana Hayek
- Department of Biology, American University of Beirut, Lebanon
| | - Carine Jaafar
- Department of Biology, American University of Beirut, Lebanon
| | - Sawsan Al Lafi
- Department of Biology, American University of Beirut, Lebanon
| | - Afaf Saliba
- Department of Biology, American University of Beirut, Lebanon
| | | | - Larissa Skaf
- Department of Biology, American University of Beirut, Lebanon
| | - Noël Ghanem
- Department of Biology, American University of Beirut, Lebanon
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13
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Julian LM, Blais A. Transcriptional control of stem cell fate by E2Fs and pocket proteins. Front Genet 2015; 6:161. [PMID: 25972892 PMCID: PMC4412126 DOI: 10.3389/fgene.2015.00161] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2014] [Accepted: 04/08/2015] [Indexed: 01/04/2023] Open
Abstract
E2F transcription factors and their regulatory partners, the pocket proteins (PPs), have emerged as essential regulators of stem cell fate control in a number of lineages. In mammals, this role extends from both pluripotent stem cells to those encompassing all embryonic germ layers, as well as extra-embryonic lineages. E2F/PP-mediated regulation of stem cell decisions is highly evolutionarily conserved, and is likely a pivotal biological mechanism underlying stem cell homeostasis. This has immense implications for organismal development, tissue maintenance, and regeneration. In this article, we discuss the roles of E2F factors and PPs in stem cell populations, focusing on mammalian systems. We discuss emerging findings that position the E2F and PP families as widespread and dynamic epigenetic regulators of cell fate decisions. Additionally, we focus on the ever expanding landscape of E2F/PP target genes, and explore the possibility that E2Fs are not simply regulators of general ‘multi-purpose’ cell fate genes but can execute tissue- and cell type-specific gene regulatory programs.
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Affiliation(s)
- Lisa M Julian
- Sprott Centre for Stem Cell Research, Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON Canada
| | - Alexandre Blais
- Ottawa Institute of Systems Biology, Ottawa, ON Canada ; Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON Canada
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14
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Tissue-specific targeting of cell fate regulatory genes by E2f factors. Cell Death Differ 2015; 23:565-75. [PMID: 25909886 DOI: 10.1038/cdd.2015.36] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 02/03/2015] [Accepted: 03/04/2015] [Indexed: 12/30/2022] Open
Abstract
Cell cycle proteins are important regulators of diverse cell fate decisions, and in this capacity have pivotal roles in neurogenesis and brain development. The mechanisms by which cell cycle regulation is integrated with cell fate control in the brain and other tissues are poorly understood, and an outstanding question is whether the cell cycle machinery regulates fate decisions directly or instead as a secondary consequence of proliferative control. Identification of the genes targeted by E2 promoter binding factor (E2f) transcription factors, effectors of the pRb/E2f cell cycle pathway, will provide essential insights into these mechanisms. We identified the promoter regions bound by three neurogenic E2f factors in neural precursor cells in a genome-wide manner. Through bioinformatic analyses and integration of published genomic data sets we uncovered hundreds of transcriptionally active E2f-bound promoters corresponding to genes that control cell fate processes, including key transcriptional regulators and members of the Notch, fibroblast growth factor, Wnt and Tgf-β signaling pathways. We also demonstrate a striking enrichment of the CCCTC binding factor transcription factor (Ctcf) at E2f3-bound nervous system-related genes, suggesting a potential regulatory co-factor for E2f3 in controlling differentiation. Finally, we provide the first demonstration of extensive tissue specificity among E2f target genes in mammalian cells, whereby E2f3 promoter binding is well conserved between neural and muscle precursors at genes associated with cell cycle processes, but is tissue-specific at differentiation-associated genes. Our findings implicate the cell cycle pathway as a widespread regulator of cell fate genes, and suggest that E2f3 proteins control cell type-specific differentiation programs by regulating unique sets of target genes. This work significantly enhances our understanding of how the cell cycle machinery impacts cell fate and differentiation, and will importantly drive further discovery regarding the mechanisms of cell fate control and transcriptional regulation in the brain, as well as in other tissues.
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15
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De Sousa M, Porras DP, Perry CGR, Seale P, Scimè A. p107 is a crucial regulator for determining the adipocyte lineage fate choices of stem cells. Stem Cells 2014; 32:1323-36. [PMID: 24449206 DOI: 10.1002/stem.1637] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 11/20/2013] [Indexed: 12/11/2022]
Abstract
Thermogenic (beige and brown) adipocytes protect animals against obesity and metabolic disease. However, little is known about the mechanisms that commit stem cells toward different adipocyte lineages. We show here that p107 is a master regulator of adipocyte lineage fates, its suppression required for commitment of stem cells to the brown-type fate. p107 is strictly expressed in the stem cell compartment of white adipose tissue depots and completely absent in brown adipose tissue. Remarkably, p107-deficient stem cells uniformly give rise to brown-type adipocytes in vitro and in vivo. Furthermore, brown fat programming of mesenchymal stem cells by PRDM-BF1-RIZ1 homologous domain containing 16 (Prdm16) was associated with a dramatic reduction of p107 levels. Indeed, Prdm16 directly suppressed p107 transcription via promoter binding. Notably, the sustained expression of p107 blocked the ability of Prdm16 to induce brown fat genes. These findings demonstrate that p107 expression in stem cells commits cells to the white versus brown adipose lineage.
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Affiliation(s)
- Martina De Sousa
- Stem Cell Research Group, Faculty of Health, York University, Toronto, Ontario, Canada
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16
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Cheffer A, Tárnok A, Ulrich H. Cell Cycle Regulation During Neurogenesis in the Embryonic and Adult Brain. Stem Cell Rev Rep 2013; 9:794-805. [DOI: 10.1007/s12015-013-9460-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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17
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Conditional disruption of calpain in the CNS alters dendrite morphology, impairs LTP, and promotes neuronal survival following injury. J Neurosci 2013; 33:5773-84. [PMID: 23536090 DOI: 10.1523/jneurosci.4247-12.2013] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Ubiquitous classical (typical) calpains, calpain-1 and calpain-2, are Ca(+2)-dependent cysteine proteases, which have been associated with numerous physiological and pathological cellular functions. However, a clear understanding of the role of calpains in the CNS has been hampered by the lack of appropriate deletion paradigms in the brain. In this study, we describe a unique model of conditional deletion of both calpain-1 and calpain-2 activities in mouse brain, which more definitively assesses the role of these ubiquitous proteases in brain development/function and pathology. Surprisingly, we show that these calpains are not critical for gross CNS development. However, calpain-1/calpain-2 loss leads to reduced dendritic branching complexity and spine density deficits associated with major deterioration in hippocampal long-term potentiation and spatial memory. Moreover, calpain-1/calpain-2-deficient neurons were significantly resistant to injury induced by excitotoxic stress or mitochondrial toxicity. Examination of downstream target showed that the conversion of the Cdk5 activator, p35, to pathogenic p25 form, occurred only in the presence of calpain and that it played a major role in calpain-mediated neuronal death. These findings unequivocally establish two central roles of calpain-1/calpain-2 in CNS function in plasticity and neuronal death.
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18
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Bartesaghi S, Salomoni P. Tumor suppressive pathways in the control of neurogenesis. Cell Mol Life Sci 2013; 70:581-97. [PMID: 22802124 PMCID: PMC11113109 DOI: 10.1007/s00018-012-1063-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 06/16/2012] [Accepted: 06/18/2012] [Indexed: 12/16/2022]
Abstract
The generation of specialized neural cells in the developing and postnatal central nervous system is a highly regulated process, whereby neural stem cells divide to generate committed neuronal progenitors, which then withdraw from the cell cycle and start to differentiate. Cell cycle checkpoints play a major role in regulating the balance between neural stem cell expansion and differentiation. Loss of tumor suppressors involved in checkpoint control can lead to dramatic alterations of neurogenesis, thus contributing to neoplastic transformation. Here we summarize and critically discuss the existing literature on the role of tumor suppressive pathways and their regulatory networks in the control of neurogenesis and transformation.
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Affiliation(s)
- Stefano Bartesaghi
- Samantha Dickson Brain Cancer Unit, UCL Cancer Institute, 72 Huntley Street, London, WC1E 6DD UK
| | - Paolo Salomoni
- Samantha Dickson Brain Cancer Unit, UCL Cancer Institute, 72 Huntley Street, London, WC1E 6DD UK
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19
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The Retinoblastoma pathway regulates stem cell proliferation in freshwater planarians. Dev Biol 2012; 373:442-52. [PMID: 23123964 DOI: 10.1016/j.ydbio.2012.10.025] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 10/16/2012] [Accepted: 10/22/2012] [Indexed: 02/01/2023]
Abstract
Freshwater planarians are flatworms of the Lophotrochozoan superphylum and are well known for their regenerative abilities, which rely on a large population of pluripotent adult stem cells. However, the mechanisms by which planarians maintain a precise population of adult stem cells while balancing proliferation and cell death, remain to be elucidated. Here we have identified, characterized, and functionally tested the core Retinoblastoma (Rb) pathway components in planarian adult stem cell biology. The Rb pathway is an ancient and conserved mechanism of proliferation control from plants to animals and is composed of three core components: an Rb protein, and a transcription factor heterodimer of E2F and DP proteins. Although the planarian genome contains all components of the Rb pathway, we found that they have undergone gene loss from the ancestral state, similar to other species in their phylum. The single Rb homolog (Smed-Rb) was highly expressed in planarian stem cells and was required for stem cell maintenance, similar to the Rb-homologs p107 and p130 in vertebrates. We show that planarians and their phylum have undergone the most severe reduction in E2F genes observed thus far, and the single remaining E2F was predicted to be a repressive-type E2F (Smed-E2F4-1). Knockdown of either Smed-E2F4-1 or its dimerization partner Dp (Smed-Dp) by RNAi resulted in temporary hyper-proliferation. Finally, we showed that known Rb-interacting genes in other systems, histone deacetylase 1 and cyclinD (Smed-HDAC1; Smed-cycD), were similar to Rb in expression and phenotypes when knocked down by RNAi, suggesting that these established interactions with Rb may also be conserved in planarians. Together, these results showed that planarians use the conserved components of the Rb tumor suppressor pathway to control proliferation and cell survival.
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Abstract
Stem cells play a critical role during embryonic development and in the maintenance of homeostasis in adult individuals. A better understanding of stem cell biology, including embryonic and adult stem cells, will allow the scientific community to better comprehend a number of pathologies and possibly design novel approaches to treat patients with a variety of diseases. The retinoblastoma tumor suppressor RB controls the proliferation, differentiation, and survival of cells, and accumulating evidence points to a central role for RB activity in the biology of stem and progenitor cells. In some contexts, loss of RB function in stem or progenitor cells is a key event in the initiation of cancer and determines the subtype of cancer arising from these pluripotent cells by altering their fate. In other cases, RB inactivation is often not sufficient to initiate cancer but may still lead to some stem cell expansion, raising the possibility that strategies aimed at transiently inactivating RB might provide a novel way to expand functional stem cell populations. Future experiments dedicated to better understanding how RB and the RB pathway control a stem cell's decisions to divide, self-renew, or give rise to differentiated progeny may eventually increase our capacity to control these decisions to enhance regeneration or help prevent cancer development.
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Affiliation(s)
- Julien Sage
- Department of Pediatrics, Department of Genetics, Stanford Institute for Stem Cell Biology and Regenerative Medicine, Stanford Cancer Institute, Stanford, California 94305, USA.
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21
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Beukelaers P, Vandenbosch R, Caron N, Nguyen L, Moonen G, Malgrange B. Cycling or not cycling: cell cycle regulatory molecules and adult neurogenesis. Cell Mol Life Sci 2012; 69:1493-503. [PMID: 22068613 PMCID: PMC11114951 DOI: 10.1007/s00018-011-0880-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 10/10/2011] [Accepted: 10/27/2011] [Indexed: 12/11/2022]
Abstract
The adult brain most probably reaches its highest degree of plasticity with the lifelong generation and integration of new neurons in the hippocampus and olfactory system. Neural precursor cells (NPCs) residing both in the subgranular zone of the dentate gyrus and in the subventricular zone of the lateral ventricles continuously generate neurons that populate the dentate gyrus and the olfactory bulb, respectively. The regulation of NPC proliferation in the adult brain has been widely investigated in the past few years. Yet, the intrinsic cell cycle machinery underlying NPC proliferation remains largely unexplored. In this review, we discuss the cell cycle components that are involved in the regulation of NPC proliferation in both neurogenic areas of the adult brain.
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Affiliation(s)
- Pierre Beukelaers
- GIGA- Neurosciences, University of Liège, Avenue de l’Hôpital, 1 Bâtiment C.H.U B36, +1, 4000 Liège, Belgium
| | - Renaud Vandenbosch
- GIGA- Neurosciences, University of Liège, Avenue de l’Hôpital, 1 Bâtiment C.H.U B36, +1, 4000 Liège, Belgium
- Present Address: Department of Cellular and Molecular Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5 Canada
| | - Nicolas Caron
- GIGA- Neurosciences, University of Liège, Avenue de l’Hôpital, 1 Bâtiment C.H.U B36, +1, 4000 Liège, Belgium
| | - Laurent Nguyen
- GIGA- Neurosciences, University of Liège, Avenue de l’Hôpital, 1 Bâtiment C.H.U B36, +1, 4000 Liège, Belgium
| | - Gustave Moonen
- GIGA- Neurosciences, University of Liège, Avenue de l’Hôpital, 1 Bâtiment C.H.U B36, +1, 4000 Liège, Belgium
- Department of Neurology, C.H.U. Sart Tilman, B35, 4000 Liège, Belgium
| | - Brigitte Malgrange
- GIGA- Neurosciences, University of Liège, Avenue de l’Hôpital, 1 Bâtiment C.H.U B36, +1, 4000 Liège, Belgium
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22
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Ouyang Y, Song Y, Lu B. dp53 Restrains ectopic neural stem cell formation in the Drosophila brain in a non-apoptotic mechanism involving Archipelago and cyclin E. PLoS One 2011; 6:e28098. [PMID: 22140513 PMCID: PMC3225381 DOI: 10.1371/journal.pone.0028098] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 11/01/2011] [Indexed: 02/06/2023] Open
Abstract
Accumulating evidence suggests that tumor-initiating stem cells or cancer stem cells (CSCs) possibly originating from normal stem cells may be the root cause of certain malignancies. How stem cell homeostasis is impaired in tumor tissues is not well understood, although certain tumor suppressors have been implicated. In this study, we use the Drosophila neural stem cells (NSCs) called neuroblasts as a model to study this process. Loss-of-function of Numb, a key cell fate determinant with well-conserved mammalian counterparts, leads to the formation of ectopic neuroblasts and a tumor phenotype in the larval brain. Overexpression of the Drosophila tumor suppressor p53 (dp53) was able to suppress ectopic neuroblast formation caused by numb loss-of-function. This occurred in a non-apoptotic manner and was independent of Dacapo, the fly counterpart of the well-characterized mammalian p53 target p21 involved in cellular senescence. The observation that dp53 affected Edu incorporation into neuroblasts led us to test the hypothesis that dp53 acts through regulation of factors involved in cell cycle progression. Our results show that the inhibitory effect of dp53 on ectopic neuroblast formation was mediated largely through its regulation of Cyclin E (Cyc E). Overexpression of Cyc E was able to abrogate dp53's ability to rescue numb loss-of-function phenotypes. Increasing Cyc E levels by attenuating Archipelago (Ago), a recently identified transcriptional target of dp53 and a negative regulator of Cyc E, had similar effects. Conversely, reducing Cyc E activity by overexpressing Ago blocked ectopic neuroblast formation in numb mutant. Our results reveal an intimate connection between cell cycle progression and NSC self-renewal vs. differentiation control, and indicate that p53-mediated regulation of ectopic NSC self-renewal through the Ago/Cyc E axis becomes particularly important when NSC homeostasis is perturbed as in numb loss-of-function condition. This has important clinical implications.
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Affiliation(s)
- Yingshi Ouyang
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Yan Song
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Bingwei Lu
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States of America
- * E-mail:
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23
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Beukelaers P, Vandenbosch R, Caron N, Nguyen L, Belachew S, Moonen G, Kiyokawa H, Barbacid M, Santamaria D, Malgrange B. Cdk6-dependent regulation of G(1) length controls adult neurogenesis. Stem Cells 2011; 29:713-24. [PMID: 21319271 DOI: 10.1002/stem.616] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The presence of neurogenic precursors in the adult mammalian brain is now widely accepted, but the mechanisms coupling their proliferation with the onset of neuronal differentiation remain unknown. Here, we unravel the major contribution of the G(1) regulator cyclin-dependent kinase 6 (Cdk6) to adult neurogenesis. We found that Cdk6 was essential for cell proliferation within the dentate gyrus of the hippocampus and the subventricular zone of the lateral ventricles. Specifically, Cdk6 deficiency prevents the expansion of neuronally committed precursors by lengthening G(1) phase duration, reducing concomitantly the production of newborn neurons. Altogether, our data support G(1) length as an essential regulator of the switch between proliferation and neuronal differentiation in the adult brain and Cdk6 as one intrinsic key molecular regulator of this process.
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24
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Viatour P, Ehmer U, Saddic LA, Dorrell C, Andersen JB, Lin C, Zmoos AF, Mazur PK, Schaffer BE, Ostermeier A, Vogel H, Sylvester KG, Thorgeirsson SS, Grompe M, Sage J. Notch signaling inhibits hepatocellular carcinoma following inactivation of the RB pathway. ACTA ACUST UNITED AC 2011; 208:1963-76. [PMID: 21875955 PMCID: PMC3182062 DOI: 10.1084/jem.20110198] [Citation(s) in RCA: 160] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Mice lacking all three Rb genes in the liver develop tumors resembling specific subgroups of human hepatocellular carcinomas, and Notch activity appears to suppress the growth and progression of these tumors. Hepatocellular carcinoma (HCC) is the third cancer killer worldwide with >600,000 deaths every year. Although the major risk factors are known, therapeutic options in patients remain limited in part because of our incomplete understanding of the cellular and molecular mechanisms influencing HCC development. Evidence indicates that the retinoblastoma (RB) pathway is functionally inactivated in most cases of HCC by genetic, epigenetic, and/or viral mechanisms. To investigate the functional relevance of this observation, we inactivated the RB pathway in the liver of adult mice by deleting the three members of the Rb (Rb1) gene family: Rb, p107, and p130. Rb family triple knockout mice develop liver tumors with histopathological features and gene expression profiles similar to human HCC. In this mouse model, cancer initiation is associated with the specific expansion of populations of liver stem/progenitor cells, indicating that the RB pathway may prevent HCC development by maintaining the quiescence of adult liver progenitor cells. In addition, we show that during tumor progression, activation of the Notch pathway via E2F transcription factors serves as a negative feedback mechanism to slow HCC growth. The level of Notch activity is also able to predict survival of HCC patients, suggesting novel means to diagnose and treat HCC.
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Affiliation(s)
- Patrick Viatour
- Department of Genetics, Department of Pediatrics, Stanford University, Stanford, CA, USA; Department of Medical Chemistry, University of Liège, B-4000 Liège, Belgium
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25
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Burkhart DL, Wirt SE, Zmoos AF, Kareta MS, Sage J. Tandem E2F binding sites in the promoter of the p107 cell cycle regulator control p107 expression and its cellular functions. PLoS Genet 2010; 6:e1001003. [PMID: 20585628 PMCID: PMC2891812 DOI: 10.1371/journal.pgen.1001003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Accepted: 05/26/2010] [Indexed: 11/19/2022] Open
Abstract
The retinoblastoma tumor suppressor (Rb) is a potent and ubiquitously expressed cell cycle regulator, but patients with a germline Rb mutation develop a very specific tumor spectrum. This surprising observation raises the possibility that mechanisms that compensate for loss of Rb function are present or activated in many cell types. In particular, p107, a protein related to Rb, has been shown to functionally overlap for loss of Rb in several cellular contexts. To investigate the mechanisms underlying this functional redundancy between Rb and p107 in vivo, we used gene targeting in embryonic stem cells to engineer point mutations in two consensus E2F binding sites in the endogenous p107 promoter. Analysis of normal and mutant cells by gene expression and chromatin immunoprecipitation assays showed that members of the Rb and E2F families directly bound these two sites. Furthermore, we found that these two E2F sites controlled both the repression of p107 in quiescent cells and also its activation in cycling cells, as well as in Rb mutant cells. Cell cycle assays further indicated that activation of p107 transcription during S phase through the two E2F binding sites was critical for controlled cell cycle progression, uncovering a specific role for p107 to slow proliferation in mammalian cells. Direct transcriptional repression of p107 by Rb and E2F family members provides a molecular mechanism for a critical negative feedback loop during cell cycle progression and tumorigenesis. These experiments also suggest novel therapeutic strategies to increase the p107 levels in tumor cells. The retinoblastoma tumor suppressor Rb belongs to a family of cell cycle inhibitors along with the related proteins p107 and p130. Strong evidence indicates that the three family members have both specific and overlapping functions and expression patterns in mammalian cells, including in cancer cells. However, the molecular mechanisms underlying the functional differences and similarities among Rb, p107, and p130 are still poorly understood. One proposed mechanism of compensation is a negative feedback loop involving increased p107 transcription in Rb-deficient cells. To dissect the mechanisms controlling p107 expression in both wild-type and Rb-deficient cells, we have engineered inactivating point mutations into the E2F binding sites in the endogenous p107 promoter using gene targeting in mouse embryonic stem cells. Gene expression and DNA binding assays revealed that these two sites are essential for the control of p107 transcription in wild-type and Rb mutant cells, and cell cycle assays showed their importance for normal functions of p107. These experiments identify a key node in cell cycle regulatory networks.
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Affiliation(s)
- Deborah L. Burkhart
- Departments of Pediatrics and Genetics, Stanford Medical School, Stanford, California, United States of America
- Cancer Biology Program, Stanford Medical School, Stanford, California, United States of America
| | - Stacey E. Wirt
- Departments of Pediatrics and Genetics, Stanford Medical School, Stanford, California, United States of America
- Cancer Biology Program, Stanford Medical School, Stanford, California, United States of America
| | - Anne-Flore Zmoos
- Departments of Pediatrics and Genetics, Stanford Medical School, Stanford, California, United States of America
| | - Michael S. Kareta
- Departments of Pediatrics and Genetics, Stanford Medical School, Stanford, California, United States of America
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford Medical School, Stanford, California, United States of America
| | - Julien Sage
- Departments of Pediatrics and Genetics, Stanford Medical School, Stanford, California, United States of America
- Cancer Biology Program, Stanford Medical School, Stanford, California, United States of America
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford Medical School, Stanford, California, United States of America
- * E-mail:
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26
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Wirt SE, Sage J. p107 in the public eye: an Rb understudy and more. Cell Div 2010; 5:9. [PMID: 20359370 PMCID: PMC2861648 DOI: 10.1186/1747-1028-5-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Accepted: 04/02/2010] [Indexed: 11/25/2022] Open
Abstract
p107 and its related family members Rb and p130 are critical regulators of cellular proliferation and tumorigenesis. Due to the extent of functional overlap within the Rb family, it has been difficult to assess which functions are exclusive to individual members and which are shared. Like its family members, p107 can bind a variety of cellular proteins to affect the expression of many target genes during cell cycle progression. Unlike Rb and p130, p107 is most highly expressed during the G1 to S phase transition of the cell cycle in actively dividing cells and accumulating evidence suggests a role for p107 during DNA replication. The specific roles for p107 during differentiation and development are less clear, although emerging studies suggest that it can cooperate with other Rb family members to control differentiation in multiple cell lineages. As a tumor suppressor, p107 is not as potent as Rb, yet studies in knockout mice have revealed some tumor suppressor functions in mice, depending on the context. In this review, we identify the unique and overlapping functions of p107 during the cell cycle, differentiation, and tumorigenesis.
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Affiliation(s)
- Stacey E Wirt
- Departments of Pediatrics and Genetics, Stanford Medical School, Stanford, CA 94305, USA.
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27
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Xing Y, Li C, Li A, Sridurongrit S, Tiozzo C, Bellusci S, Borok Z, Kaartinen V, Minoo P. Signaling via Alk5 controls the ontogeny of lung Clara cells. Development 2010; 137:825-33. [PMID: 20147383 DOI: 10.1242/dev.040535] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Clara cells, together with ciliated and pulmonary neuroendocrine cells, make up the epithelium of the bronchioles along the conducting airways. Clara cells are also known as progenitor or stem cells during lung regeneration after injury. The mechanisms of Clara cell differentiation are largely unknown. Transforming growth factor beta (TGFbeta)is a multifunctional molecule with roles in normal development and disease pathogenesis. In this study, we deleted the TGFbeta type I receptor Alk5 in the embryonic lung epithelium using Gata5-Cre mice. Absence of Alk5 blocked Clara cell differentiation but had no effect on ciliated or pulmonary neuroendocrine cells. Hairy/Enhancer of Split-1, which is expressed in Clara cell putative ;progenitors' was found to be a downstream target of Alk5 in vivo and in vitro. Loss of Alk5-mediated signaling also stimulated Pten gene expression and inhibited ERK phosphorylation in vivo. Using lung epithelial cells, we show that Alk5-regulated Hes1 expression is stimulated through Pten and the MEK/ERK and PI3K/AKT pathways. Thus, the signaling pathway by which TGFbeta/ALK5 regulates Clara cell differentiation may entail inhibition of Pten expression, which in turn activates ERK and AKT phosphorylation.
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Affiliation(s)
- Yiming Xing
- Department of Pediatrics, Division of Neonatology, University of Southern California, Keck School of Medicine, Los Angeles, CA 90033, USA
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28
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Swiss VA, Casaccia P. Cell-context specific role of the E2F/Rb pathway in development and disease. Glia 2010; 58:377-90. [PMID: 19795505 DOI: 10.1002/glia.20933] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Development of the central nervous system (CNS) requires the generation of neuronal and glial cell subtypes in appropriate numbers, and this demands the careful coordination of cell-cycle exit, survival, and differentiation. The E2F/Rb pathway is critical for cell-cycle regulation and also modulates survival and differentiation of distinct cell types in the developing and adult CNS. In this review, we first present the specific temporal patterns of expression of the E2F and Rb family members during CNS development and then discuss the genetic ablation of single or multiple members of these two families. Overall, the available data suggest a time-dependent and cell-context specific role of E2F and Rb family members in the developing and adult CNS.
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Affiliation(s)
- Victoria A Swiss
- Department of Neuroscience and Genetics and Genomics, Mount Sinai School of Medicine, New York, New York 10029, USA
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29
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Salomoni P, Calegari F. Cell cycle control of mammalian neural stem cells: putting a speed limit on G1. Trends Cell Biol 2010; 20:233-43. [PMID: 20153966 DOI: 10.1016/j.tcb.2010.01.006] [Citation(s) in RCA: 204] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 01/13/2010] [Accepted: 01/13/2010] [Indexed: 01/06/2023]
Abstract
The potential to increase unlimitedly in number and to generate differentiated cell types is a key feature of somatic stem cells. Within the nervous system, cellular and environmental determinants tightly control the expansion and differentiation of neural stem cells. Importantly, a number of studies have indicated that changes in cell cycle length can influence development and physiopathology of the nervous system, and might have played a role during evolution of the mammalian brain. Specifically, it has been suggested that the length of G1 can directly influence the differentiation of neural precursors. This has prompted the proposal of a model to explain how manipulation of G1 length can be used to expand neural stem cells. If validated in non-neural systems, this model might provide the means to control the proliferation vs. differentiation of somatic stem cells, which will represent a significant advance in the field.
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Affiliation(s)
- Paolo Salomoni
- Samantha Dickson Brain Cancer Unit, UCL Cancer Institute, 72 Huntley Street, London WC1E 6BT, UK.
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Román-Trufero M, Méndez-Gómez HR, Pérez C, Hijikata A, Fujimura YI, Endo T, Koseki H, Vicario-Abejón C, Vidal M. Maintenance of Undifferentiated State and Self-Renewal of Embryonic Neural Stem Cells by Polycomb Protein Ring1B. Stem Cells 2009; 27:1559-70. [DOI: 10.1002/stem.82] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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The p107/E2F pathway regulates fibroblast growth factor 2 responsiveness in neural precursor cells. Mol Cell Biol 2009; 29:4701-13. [PMID: 19564414 DOI: 10.1128/mcb.01767-08] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
We have previously shown that p107, a member of the retinoblastoma (Rb) cell cycle regulatory family, has a unique function in regulating the pool of neural precursor cells. As the pool of progenitors is regulated by a limiting supply of trophic factors, we asked if the Rb/E2F pathway may control the size of the progenitor population by regulating the levels of growth factors or their receptors. Here, we demonstrate that fibroblast growth factor 2 (FGF2) is aberrantly upregulated in the brains of animals lacking Rb family proteins and that the gene encoding the FGF2 ligand is directly regulated by p107 and E2F3. Chromatin immunoprecipitation assays demonstrated that E2F3 and p107 occupy E2F consensus sites on the FGF2 promoter in the context of native chromatin. To evaluate the physiological consequence of FGF2 deregulation in both p107 and E2F3 mutants, we measured neural progenitor responsiveness to growth factors. Our results demonstrate that E2F3 and p107 are each mediators of FGF2 growth factor responsiveness in neural progenitor cells. These results support a model whereby p107 regulates the pool of FGF-responsive progenitors by directly regulating FGF2 gene expression in vivo. By identifying novel roles for p107/E2F in regulating genes outside of the classical cell cycle machinery targets, we uncover a new mechanism whereby Rb/E2F mediates proliferation through regulating growth factor responsiveness.
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Zhu YH, Zhang CW, Lu L, Demidov ON, Sun L, Yang L, Bulavin DV, Xiao ZC. Wip1 Regulates the Generation of New Neural Cells in the Adult Olfactory Bulb through p53-Dependent Cell Cycle Control. Stem Cells 2009; 27:1433-42. [PMID: 19489034 DOI: 10.1002/stem.65] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Yun-Hua Zhu
- Department of Clinical Research, Singapore General Hospital, Singapore
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Burkhart DL, Viatour P, Ho VM, Sage J. GFP reporter mice for the retinoblastoma-related cell cycle regulator p107. Cell Cycle 2008; 7:2544-52. [PMID: 18719374 DOI: 10.4161/cc.7.16.6441] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The RB tumor suppressor gene is mutated in a broad range of human cancers, including pediatric retinoblastoma. Strikingly, however, Rb mutant mice develop tumors of the pituitary and thyroid glands, but not retinoblastoma. Mouse genetics experiments have demonstrated that p107, a protein related to pRB, is capable of preventing retinoblastoma, but not pituitary tumors, in Rb-deficient mice. Evidence suggests that the basis for this compensatory function of p107 is increased transcription of the p107 gene in response to Rb inactivation. To begin to address the context-dependency of this compensatory role of p107 and to follow p107 expression in vivo, we have generated transgenic mice carrying an enhanced GFP (eGFP) reporter inserted into a bacterial artificial chromosome (BAC) containing the mouse p107 gene. Expression of the eGFP transgene parallels that of p107 in these transgenic mice and identifies cells with a broad range of expression level for p107, even within particular organs or tissues. We also show that loss of Rb results in the upregulation of p107 transcription in specific cell populations in vivo, including subpopulations of hematopoietic cells. Thus, p107 BAC-eGFP transgenic mice serve as a useful tool to identify distinct cell types in which p107 is expressed and may have key functions in vivo, and to characterize changes in cellular networks accompanying Rb deficiency.
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Affiliation(s)
- Deborah L Burkhart
- Department of Pediatrics and Genetics, Cancer Biology Program, Stanford Medical School, Stanford, California, USA
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Abstract
Stem cells are captivating because they have the potential to make multiple cell types yet maintain their undifferentiated state. Recent studies of Drosophila and mammalian neural stem cells have shed light on how stem cells regulate self-renewal versus differentiation and have revealed the proteins, processes and pathways that all converge to regulate neural progenitor self-renewal. If we can better understand how stem cells balance self-renewal versus differentiation, we will significantly advance our knowledge of embryogenesis, cancer biology and brain evolution, as well as the use of stem cells for therapeutic purposes.
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Affiliation(s)
- Chris Q Doe
- Howard Hughes Medical Institute, Institute of Neuroscience, Institute of Molecular Biology, University of Oregon, Eugene, OR, USA.
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