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Box AM, Ramesh NA, Nandakumar S, Church SJ, Prasad D, Afrakhteh A, Taichman RS, Buttitta L. Cell cycle variants during Drosophila male accessory gland development. G3 (BETHESDA, MD.) 2024; 14:jkae089. [PMID: 38683731 PMCID: PMC11228851 DOI: 10.1093/g3journal/jkae089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 01/31/2024] [Accepted: 04/09/2024] [Indexed: 05/02/2024]
Abstract
The Drosophila melanogaster male accessory gland (AG) is a functional analog of the mammalian prostate and seminal vesicles containing two secretory epithelial cell types, termed main and secondary cells. This tissue is responsible for making and secreting seminal fluid proteins and other molecules that contribute to successful reproduction. The cells of this tissue are binucleate and polyploid, due to variant cell cycles that include endomitosis and endocycling during metamorphosis. Here, we provide evidence of additional cell cycle variants in this tissue. We show that main cells of the gland are connected by ring canals that form after the penultimate mitosis, and we describe an additional post-eclosion endocycle required for gland maturation that is dependent on juvenile hormone signaling. We present evidence that the main cells of the D. melanogaster AG undergo a unique cell cycle reprogramming throughout organ development that results in step-wise cell cycle truncations culminating in cells containing two octoploid nuclei with under-replicated heterochromatin in the mature gland. We propose this tissue as a model to study developmental and hormonal temporal control of cell cycle variants in terminally differentiating tissues.
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Affiliation(s)
- Allison M Box
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, 1105 N. University Ave. Ann Arbor, MI 48109, USA
| | - Navyashree A Ramesh
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, 1105 N. University Ave. Ann Arbor, MI 48109, USA
| | - Shyama Nandakumar
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, 1105 N. University Ave. Ann Arbor, MI 48109, USA
| | - Samuel Jaimian Church
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, 1105 N. University Ave. Ann Arbor, MI 48109, USA
| | - Dilan Prasad
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, 1105 N. University Ave. Ann Arbor, MI 48109, USA
| | - Ariana Afrakhteh
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, 1105 N. University Ave. Ann Arbor, MI 48109, USA
| | - Russell S Taichman
- Department of Periodontology, School of Dentistry, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Laura Buttitta
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, 1105 N. University Ave. Ann Arbor, MI 48109, USA
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Rodríguez A, Foronda D, Córdoba S, Felipe-Cordero D, Baonza A, Miguez DG, Estella C. Cell proliferation and Notch signaling coordinate the formation of epithelial folds in the Drosophila leg. Development 2024; 151:dev202384. [PMID: 38512712 PMCID: PMC11058088 DOI: 10.1242/dev.202384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 03/12/2024] [Indexed: 03/23/2024]
Abstract
The formation of complex three-dimensional organs during development requires precise coordination between patterning networks and mechanical forces. In particular, tissue folding is a crucial process that relies on a combination of local and tissue-wide mechanical forces. Here, we investigate the contribution of cell proliferation to epithelial morphogenesis using the Drosophila leg tarsal folds as a model. We reveal that tissue-wide compression forces generated by cell proliferation, in coordination with the Notch signaling pathway, are essential for the formation of epithelial folds in precise locations along the proximo-distal axis of the leg. As cell numbers increase, compressive stresses arise, promoting the folding of the epithelium and reinforcing the apical constriction of invaginating cells. Additionally, the Notch target dysfusion plays a key function specifying the location of the folds, through the apical accumulation of F-actin and the apico-basal shortening of invaginating cells. These findings provide new insights into the intricate mechanisms involved in epithelial morphogenesis, highlighting the crucial role of tissue-wide forces in shaping a three-dimensional organ in a reproducible manner.
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Affiliation(s)
- Alonso Rodríguez
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - David Foronda
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma de Madrid, Madrid 28049, Spain
- Departamento de Medicina, Facultad de Ciencias Biomédicas y de la Salud, Universidad Europea de Madrid, Madrid 28670, Spain
| | - Sergio Córdoba
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Daniel Felipe-Cordero
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Antonio Baonza
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - David G. Miguez
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma de Madrid, Madrid 28049, Spain
- Departmento de Física de la Materia Condensada, Instituto de Física de la Materia Condensada (IFIMAC), Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Carlos Estella
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma de Madrid, Madrid 28049, Spain
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Sekar A, Leiblich A, Wainwright SM, Mendes CC, Sarma D, Hellberg JEEU, Gandy C, Goberdhan DCI, Hamdy FC, Wilson C. Rbf/E2F1 control growth and endoreplication via steroid-independent Ecdysone Receptor signalling in Drosophila prostate-like secondary cells. PLoS Genet 2023; 19:e1010815. [PMID: 37363926 PMCID: PMC10328346 DOI: 10.1371/journal.pgen.1010815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 07/07/2023] [Accepted: 06/06/2023] [Indexed: 06/28/2023] Open
Abstract
In prostate cancer, loss of the tumour suppressor gene, Retinoblastoma (Rb), and consequent activation of transcription factor E2F1 typically occurs at a late-stage of tumour progression. It appears to regulate a switch to an androgen-independent form of cancer, castration-resistant prostate cancer (CRPC), which frequently still requires androgen receptor (AR) signalling. We have previously shown that upon mating, binucleate secondary cells (SCs) of the Drosophila melanogaster male accessory gland (AG), which share some similarities with prostate epithelial cells, switch their growth regulation from a steroid-dependent to a steroid-independent form of Ecdysone Receptor (EcR) control. This physiological change induces genome endoreplication and allows SCs to rapidly replenish their secretory compartments, even when ecdysone levels are low because the male has not previously been exposed to females. Here, we test whether the Drosophila Rb homologue, Rbf, and E2F1 regulate this switch. Surprisingly, we find that excess Rbf activity reversibly suppresses binucleation in adult SCs. We also demonstrate that Rbf, E2F1 and the cell cycle regulators, Cyclin D (CycD) and Cyclin E (CycE), are key regulators of mating-dependent SC endoreplication, as well as SC growth in both virgin and mated males. Importantly, we show that the CycD/Rbf/E2F1 axis requires the EcR, but not ecdysone, to trigger CycE-dependent endoreplication and endoreplication-associated growth in SCs, mirroring changes seen in CRPC. Furthermore, Bone Morphogenetic Protein (BMP) signalling, mediated by the BMP ligand Decapentaplegic (Dpp), intersects with CycD/Rbf/E2F1 signalling to drive endoreplication in these fly cells. Overall, our work reveals a signalling switch, which permits rapid growth of SCs and increased secretion after mating, independently of previous exposure to females. The changes observed share mechanistic parallels with the pathological switch to hormone-independent AR signalling seen in CRPC, suggesting that the latter may reflect the dysregulation of a currently unidentified physiological process.
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Affiliation(s)
- Aashika Sekar
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Aaron Leiblich
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, United Kingdom
| | - S. Mark Wainwright
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Cláudia C. Mendes
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Dhruv Sarma
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | | | - Carina Gandy
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Deborah C. I. Goberdhan
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Freddie C. Hamdy
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, United Kingdom
| | - Clive Wilson
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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4
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Dpp and Hedgehog promote the glial response to neuronal apoptosis in the developing Drosophila visual system. PLoS Biol 2021; 19:e3001367. [PMID: 34379617 PMCID: PMC8396793 DOI: 10.1371/journal.pbio.3001367] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 08/27/2021] [Accepted: 07/16/2021] [Indexed: 11/19/2022] Open
Abstract
Damage in the nervous system induces a stereotypical response that is mediated by glial cells. Here, we use the eye disc of Drosophila melanogaster as a model to explore the mechanisms involved in promoting glial cell response after neuronal cell death induction. We demonstrate that these cells rapidly respond to neuronal apoptosis by increasing in number and undergoing morphological changes, which will ultimately grant them phagocytic abilities. We found that this glial response is controlled by the activity of Decapentaplegic (Dpp) and Hedgehog (Hh) signalling pathways. These pathways are activated after cell death induction, and their functions are necessary to induce glial cell proliferation and migration to the eye discs. The latter of these 2 processes depend on the function of the c-Jun N-terminal kinase (JNK) pathway, which is activated by Dpp signalling. We also present evidence that a similar mechanism controls glial response upon apoptosis induction in the leg discs, suggesting that our results uncover a mechanism that might be involved in controlling glial cells response to neuronal cell death in different regions of the peripheral nervous system (PNS). In reaction to neuronal damage, glial cells proliferate, change their morphology and alter their behaviour; this response is associated with glial cells’ regenerative function and is necessary to preserve the structural integrity and function of the nervous system. This study identifies a role for the Decapentaplegic and Hedgehog pathways in controlling the glial response.
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Zhang P, Du J, Guo X, Wu S, He J, Li X, Shen L, Chen L, Li B, Zhang J, Xie Y, Niu L, Jiang D, Li X, Zhang S, Zhu L. LncMyoD Promotes Skeletal Myogenesis and Regulates Skeletal Muscle Fiber-Type Composition by Sponging miR-370-3p. Genes (Basel) 2021; 12:genes12040589. [PMID: 33920575 PMCID: PMC8072939 DOI: 10.3390/genes12040589] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/12/2021] [Accepted: 04/15/2021] [Indexed: 02/06/2023] Open
Abstract
The development of skeletal muscle is a highly ordered and complex biological process. Increasing evidence has shown that noncoding RNAs, especially long-noncoding RNAs (lncRNAs) and microRNAs, play a vital role in the development of myogenic processes. In this study, we observed that lncMyoD regulates myogenesis and changes myofiber-type composition. miR-370-3p, which is directly targeted by lncMyoD, promoted myoblast proliferation and inhibited myoblast differentiation in the C2C12 cell line, which serves as a valuable model for studying muscle development. In addition, the inhibition of miR-370-3p promoted fast-twitch fiber transition. Further analysis indicated that acyl-Coenzyme A dehydrogenase, short/branched chain (ACADSB) is a target gene of miR-370-3p, which is also involved in myoblast differentiation and fiber-type transition. Furthermore, our data suggested that miR-370-3p was sponged by lncMyoD. In contrast with miR-370-3p, lncMyoD promoted fast-twitch fiber transition. Taken together, our results suggest that miR-370-3p regulates myoblast differentiation and muscle fiber transition and is sponged by lncMyoD.
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Affiliation(s)
- Peiwen Zhang
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (P.Z.); (J.D.); (X.G.); (S.W.); (J.H.); (X.L.); (L.S.); (L.C.); (B.L.); (J.Z.); (Y.X.); (L.N.); (D.J.); (X.L.); (S.Z.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Jingjing Du
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (P.Z.); (J.D.); (X.G.); (S.W.); (J.H.); (X.L.); (L.S.); (L.C.); (B.L.); (J.Z.); (Y.X.); (L.N.); (D.J.); (X.L.); (S.Z.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Xinyu Guo
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (P.Z.); (J.D.); (X.G.); (S.W.); (J.H.); (X.L.); (L.S.); (L.C.); (B.L.); (J.Z.); (Y.X.); (L.N.); (D.J.); (X.L.); (S.Z.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Shuang Wu
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (P.Z.); (J.D.); (X.G.); (S.W.); (J.H.); (X.L.); (L.S.); (L.C.); (B.L.); (J.Z.); (Y.X.); (L.N.); (D.J.); (X.L.); (S.Z.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Jin He
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (P.Z.); (J.D.); (X.G.); (S.W.); (J.H.); (X.L.); (L.S.); (L.C.); (B.L.); (J.Z.); (Y.X.); (L.N.); (D.J.); (X.L.); (S.Z.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Xinrong Li
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (P.Z.); (J.D.); (X.G.); (S.W.); (J.H.); (X.L.); (L.S.); (L.C.); (B.L.); (J.Z.); (Y.X.); (L.N.); (D.J.); (X.L.); (S.Z.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Linyuan Shen
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (P.Z.); (J.D.); (X.G.); (S.W.); (J.H.); (X.L.); (L.S.); (L.C.); (B.L.); (J.Z.); (Y.X.); (L.N.); (D.J.); (X.L.); (S.Z.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Lei Chen
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (P.Z.); (J.D.); (X.G.); (S.W.); (J.H.); (X.L.); (L.S.); (L.C.); (B.L.); (J.Z.); (Y.X.); (L.N.); (D.J.); (X.L.); (S.Z.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Bohong Li
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (P.Z.); (J.D.); (X.G.); (S.W.); (J.H.); (X.L.); (L.S.); (L.C.); (B.L.); (J.Z.); (Y.X.); (L.N.); (D.J.); (X.L.); (S.Z.)
| | - Jingjun Zhang
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (P.Z.); (J.D.); (X.G.); (S.W.); (J.H.); (X.L.); (L.S.); (L.C.); (B.L.); (J.Z.); (Y.X.); (L.N.); (D.J.); (X.L.); (S.Z.)
| | - Yuhao Xie
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (P.Z.); (J.D.); (X.G.); (S.W.); (J.H.); (X.L.); (L.S.); (L.C.); (B.L.); (J.Z.); (Y.X.); (L.N.); (D.J.); (X.L.); (S.Z.)
| | - Lili Niu
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (P.Z.); (J.D.); (X.G.); (S.W.); (J.H.); (X.L.); (L.S.); (L.C.); (B.L.); (J.Z.); (Y.X.); (L.N.); (D.J.); (X.L.); (S.Z.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Dongmei Jiang
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (P.Z.); (J.D.); (X.G.); (S.W.); (J.H.); (X.L.); (L.S.); (L.C.); (B.L.); (J.Z.); (Y.X.); (L.N.); (D.J.); (X.L.); (S.Z.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Xuewei Li
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (P.Z.); (J.D.); (X.G.); (S.W.); (J.H.); (X.L.); (L.S.); (L.C.); (B.L.); (J.Z.); (Y.X.); (L.N.); (D.J.); (X.L.); (S.Z.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Shunhua Zhang
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (P.Z.); (J.D.); (X.G.); (S.W.); (J.H.); (X.L.); (L.S.); (L.C.); (B.L.); (J.Z.); (Y.X.); (L.N.); (D.J.); (X.L.); (S.Z.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
| | - Li Zhu
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China; (P.Z.); (J.D.); (X.G.); (S.W.); (J.H.); (X.L.); (L.S.); (L.C.); (B.L.); (J.Z.); (Y.X.); (L.N.); (D.J.); (X.L.); (S.Z.)
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China
- Correspondence:
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Davis TL, Rebay I. Antagonistic regulation of the second mitotic wave by Eyes absent-Sine oculis and Combgap coordinates proliferation and specification in the Drosophila retina. Development 2017; 144:2640-2651. [PMID: 28619818 DOI: 10.1242/dev.147231] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 06/08/2017] [Indexed: 12/12/2022]
Abstract
The transition from proliferation to specification is fundamental to the development of appropriately patterned tissues. In the developing Drosophila eye, Eyes absent (Eya) and Sine oculis (So) orchestrate the progression of progenitor cells from asynchronous cell division to G1 arrest and neuronal specification at the morphogenetic furrow. Here, we uncover a novel role for Eya and So in promoting cell cycle exit in the second mitotic wave (SMW), a synchronized, terminal cell division that occurs several hours after passage of the furrow. We show that Combgap (Cg), a zinc-finger transcription factor, antagonizes Eya-So function in the SMW. Based on the ability of Cg to attenuate Eya-So transcriptional output in vivo and in cultured cells and on meta analysis of their chromatin occupancy profiles, we speculate that Cg limits Eya-So activation of select target genes posterior to the furrow to ensure properly timed mitotic exit. Our work supports a model in which context-specific modulation of transcriptional activity enables Eya and So to promote both entry into and exit from the cell cycle in a distinct spatiotemporal sequence.
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Affiliation(s)
- Trevor L Davis
- Committee on Development, Regeneration, and Stem Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Ilaria Rebay
- Committee on Development, Regeneration, and Stem Cell Biology, University of Chicago, Chicago, IL 60637, USA .,Ben May Department for Cancer Research, University of Chicago, Chicago, IL 60637, USA
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7
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Bradley-Gill MR, Kim M, Feingold D, Yergeau C, Houde J, Moon NS. Alternate transcripts of the Drosophila "activator" E2F are necessary for maintenance of cell cycle exit during development. Dev Biol 2016; 411:195-206. [PMID: 26859702 DOI: 10.1016/j.ydbio.2016.02.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Revised: 02/05/2016] [Accepted: 02/05/2016] [Indexed: 11/15/2022]
Abstract
The E2F family of transcription factors are evolutionarily conserved regulators of the cell cycle that can be divided into two groups based on their ability to either activate or repress transcription. In Drosophila, there is only one "activator" E2F, dE2F1, which provides all of the pro-proliferative activity of E2F during development. Interestingly, the de2f1 gene can be transcribed from multiple promoters resulting in six alternate transcripts. In this study, we sought to investigate the biological significance of the alternate transcriptional start sites. We focused on the de2f1 promoter region where tissue and cell-type specific enhancer activities were observed at the larval stage. While a genomic deletion of this region, de2f1(ΔRA), decreased the overall expression level of dE2F1, flies developed normally with no obvious proliferation defects. However, a detailed analysis of the de2f1(ΔRA) mutant eye imaginal discs revealed that dE2F1 is needed for proper cell cycle exit. We discovered that dE2F1 expression during G1 arrest prior to the differentiation process of the developing eye is important for maintaining cell cycle arrest at a later stage of the eye development. Overall, our study suggests that specific alternate transcripts of "activator" E2F, dE2F1, may have a dual function on cell cycle progression and cannot simply be viewed as a pro-proliferative transcription factor.
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Affiliation(s)
- Mary-Rose Bradley-Gill
- Department of Biology, Developmental Biology Research Initiative, McGill University, Montreal, Quebec, Canada H3A 1B1
| | - Minhee Kim
- Department of Biology, Developmental Biology Research Initiative, McGill University, Montreal, Quebec, Canada H3A 1B1
| | - Daniel Feingold
- Department of Biology, Developmental Biology Research Initiative, McGill University, Montreal, Quebec, Canada H3A 1B1
| | - Christine Yergeau
- Department of Biology, Developmental Biology Research Initiative, McGill University, Montreal, Quebec, Canada H3A 1B1
| | - Josée Houde
- Department of Biology, Developmental Biology Research Initiative, McGill University, Montreal, Quebec, Canada H3A 1B1
| | - Nam-Sung Moon
- Department of Biology, Developmental Biology Research Initiative, McGill University, Montreal, Quebec, Canada H3A 1B1.
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8
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The homeodomain of Eyeless regulates cell growth and antagonizes the paired domain-dependent retinal differentiation function. Protein Cell 2014; 6:68-78. [PMID: 25234589 PMCID: PMC4286722 DOI: 10.1007/s13238-014-0101-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 08/12/2014] [Indexed: 12/23/2022] Open
Abstract
Pax6 and its Drosophila homolog Eyeless (Ey) play essential roles during eye development. Ey/Pax6 contains two distinct DNA binding domains, a Paired domain (PD) and a Homeodomain (HD). While Ey/Pax6 PD is required for the expression of key regulators of retinal development, relatively little is known about the HD-dependent Ey function. In this study, we used the UAS/GAL4 system to determine the functions of different Ey domains on cell growth and on retinal development. We showed that Ey can promote cell growth, which requires the HD but not the PD. In contrast, the ability of Ey to activate Ato expression and induce ectopic eye formation requires the PD but not the HD. Interestingly, deletion of the HD enhanced Ey-dependent ectopic eye induction while overexpression of the HD only Ey forms antagonizes ectopic eye induction. These studies revealed a novel function of Ey HD on cell growth and a novel antagonistic effect of Ey HD on Ey PD-dependent eye induction. We further show the third helix of the Ey HD can directly interact with the RED subdomain in Ey PD and that deletion of the HD increased the binding of Ey PD to its target. These results suggest that the direct interaction between the HD and the PD potentially mediates their antagonistic effects. Since different Ey splicing forms are expressed in overlapping regions during normal development, we speculate that the expression ratios of the different Ey splice forms potentially contribute to the regulation of growth and differentiation of these tissues.
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9
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Zhang L, Wei Y, Pushel I, Heinze K, Elenbaas J, Henry RW, Arnosti DN. Integrated stability and activity control of the Drosophila Rbf1 retinoblastoma protein. J Biol Chem 2014; 289:24863-73. [PMID: 25049232 DOI: 10.1074/jbc.m114.586818] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The retinoblastoma (RB) family transcriptional corepressors regulate diverse cellular events including cell cycle, senescence, and differentiation. The activity and stability of these proteins are mediated by post-translational modifications; however, we lack a general understanding of how distinct modifications coordinately impact both of these properties. Previously, we showed that protein turnover and activity are tightly linked through an evolutionarily conserved C-terminal instability element (IE) in the Drosophila RB-related protein Rbf1; surprisingly, mutant proteins with enhanced stability were less, not more active. To better understand how activity and turnover are controlled in this model RB protein, we assessed the impact of Cyclin-Cdk kinase regulation on Rbf1. An evolutionarily conserved N-terminal threonine residue is required for Cyclin-Cdk response and showed a dominant impact on turnover and activity; however, specific residues in the C-terminal IE differentially impacted Rbf1 activity and turnover, indicating an additional level of regulation. Strikingly, specific IE mutations that impaired turnover but not activity induced dramatic developmental phenotypes in the Drosophila eye. Mutation of the highly conserved Lys-774 residue induced hypermorphic phenotypes that mimicked the loss of phosphorylation control; mutation of the corresponding codon of the human RBL2 gene has been reported in lung tumors. Our data support a model in which closely intermingled residues within the conserved IE govern protein turnover, presumably through interactions with E3 ligases, and protein activity via contacts with E2F transcription partners. Such functional relationships are likely to similarly impact mammalian RB family proteins, with important implications for development and disease.
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Affiliation(s)
- Liang Zhang
- From the Cell and Molecular Biology Program and
| | - Yiliang Wei
- the Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319 and
| | - Irina Pushel
- the Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319 and
| | - Karolin Heinze
- the Biochemistry and Molecular Biology Program, Friedrich-Schiller University Jena, D-07743 Jena, Germany
| | - Jared Elenbaas
- the Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319 and
| | - R William Henry
- From the Cell and Molecular Biology Program and the Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319 and
| | - David N Arnosti
- From the Cell and Molecular Biology Program and the Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319 and
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10
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Nicolay BN, Dyson NJ. The multiple connections between pRB and cell metabolism. Curr Opin Cell Biol 2013; 25:735-40. [PMID: 23916769 DOI: 10.1016/j.ceb.2013.07.012] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 07/12/2013] [Accepted: 07/15/2013] [Indexed: 02/03/2023]
Abstract
The pRB tumor suppressor is traditionally seen as an important regulator of the cell cycle. pRB represses the transcriptional activation of a diverse set of genes by the E2F transcription factors and prevents inappropriate S-phase entry. Advances in our understanding of pRB have documented roles that extend beyond the cell cycle and this review summarizes recent studies that link pRB to the control of cell metabolism. pRB has been shown to regulate glucose tolerance, mitogenesis, glutathione synthesis, and the expression of genes involved in central carbon metabolism. Several studies have demonstrated that pRB directly targets a set of genes that are crucial for nucleotide metabolism, and this seems likely to represent one of the ways by which pRB influences the G1/S-phase transition and S-phase progression.
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Affiliation(s)
- Brandon N Nicolay
- Laboratory of Molecular Oncology, Massachusetts General Hospital Cancer Center, Building 149, 13th Street, Charlestown, MA 02129, USA.
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11
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A targeted genetic modifier screen links the SWI2/SNF2 protein domino to growth and autophagy genes in Drosophila melanogaster. G3-GENES GENOMES GENETICS 2013; 3:815-25. [PMID: 23550128 PMCID: PMC3656729 DOI: 10.1534/g3.112.005496] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Targeted genetic studies can facilitate phenotypic analyses and provide important insights into development and other complex processes. The SWI2/SNF2 DNA-dependent ATPase Domino (Dom) of Drosophila melanogaster, a component of the Tip60 acetyltransferase complex, has been associated with a wide spectrum of cellular processes at multiple developmental stages. These include hematopoiesis, cell proliferation, homeotic gene regulation, histone exchange during DNA repair, and Notch signaling. To explore the wider gene network associated with Dom action, we used RNAi directed against domino (dom) to mediate loss-of-function at the wing margin, a tissue that is readily scored for phenotypic changes. Dom RNAi driven through GAL4-UAS elicited dominant wing nicking that responded phenotypically to the dose of dom and other loci known to function with dom. We screened for phenotypic modifiers of this wing phenotype among 2500 transpositions of the EP P element and found both enhancers and suppressors. Several classes of modifier were obtained, including those encoding transcription factors, RNA regulatory proteins, and factors that regulate cell growth, proliferation and autophagy, a lysosomal degradation pathway that affects cell growth under conditions of starvation and stress. Our analysis is consistent with prior studies, suggesting that Dom acts pleiotropically as a positive effector of Notch signaling and a repressor of proliferation. This genetic system should facilitate screens for additional loci associated with Dom function, and complement biochemical approaches to their regulatory activity.
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12
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Evidence for autoregulation and cell signaling pathway regulation from genome-wide binding of the Drosophila retinoblastoma protein. G3-GENES GENOMES GENETICS 2012; 2:1459-72. [PMID: 23173097 PMCID: PMC3484676 DOI: 10.1534/g3.112.004424] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Accepted: 09/20/2012] [Indexed: 12/24/2022]
Abstract
The retinoblastoma (RB) tumor suppressor protein is a transcriptional cofactor with essential roles in cell cycle and development. Physical and functional targets of RB and its paralogs p107/p130 have been studied largely in cultured cells, but the full biological context of this family of proteins' activities will likely be revealed only in whole organismal studies. To identify direct targets of the major Drosophila RB counterpart in a developmental context, we carried out ChIP-Seq analysis of Rbf1 in the embryo. The association of the protein with promoters is developmentally controlled; early promoter access is globally inhibited, whereas later in development Rbf1 is found to associate with promoter-proximal regions of approximately 2000 genes. In addition to conserved cell-cycle-related genes, a wholly unexpected finding was that Rbf1 targets many components of the insulin, Hippo, JAK/STAT, Notch, and other conserved signaling pathways. Rbf1 may thus directly affect output of these essential growth-control and differentiation pathways by regulation of expression of receptors, kinases and downstream effectors. Rbf1 was also found to target multiple levels of its own regulatory hierarchy. Bioinformatic analysis indicates that different classes of genes exhibit distinct constellations of motifs associated with the Rbf1-bound regions, suggesting that the context of Rbf1 recruitment may vary within the Rbf1 regulon. Many of these targeted genes are bound by Rbf1 homologs in human cells, indicating that a conserved role of RB proteins may be to adjust the set point of interlinked signaling networks essential for growth and development.
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13
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A dual role for the dREAM/MMB complex in the regulation of differentiation-specific E2F/RB target genes. Mol Cell Biol 2012; 32:2110-20. [PMID: 22451490 DOI: 10.1128/mcb.06314-11] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
E2F and RB proteins regulate the expression of genes involved in cell cycle progression, apoptosis, differentiation, and development. Recent studies indicate that they function as part of an evolutionarily conserved multiprotein complex termed dREAM/DREAM/LINC. Here we characterize the role of the Drosophila complex, dREAM, in the regulation of differentiation-specific E2F target genes in actively proliferating cells. These genes are regulated differently from cell cycle-related E2F targets, they do not depend on E2F activation, and E2F/RB repression is maintained throughout the cell cycle. In proliferating cells, their repression is dependent on dREAM. We find that dREAM plays a dual role in their regulation. First, it is required for the stability of the repressive dE2F2/RBF complexes at their promoters during S phase. Second, we find that dREAM is indispensable for both transcriptional repression mechanisms employed at these genes.
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14
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Abstract
The compound eye of the fruit fly, Drosophila melanogaster, has for decades been used extensively to study a number of critical developmental processes including tissue development, pattern formation, cell fate specification, and planar cell polarity. To a lesser degree it has been used to examine the cell cycle and tissue proliferation. Discovering the mechanisms that balance tissue growth and cell death in developing epithelia has traditionally been the realm of those using the wing disc. However, over the last decade a series of observations has demonstrated that the eye is a suitable and maybe even preferable tissue for studying tissue growth. This review will focus on how growth of the retina is controlled by the genes and pathways that govern the specification of tissue fate, the division of the epithelium into dorsal-ventral compartments, the initiation, and progression of the morphogenetic furrow and the second mitotic wave.
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Affiliation(s)
- Justin P Kumar
- Department of Biology, Indiana University, Bloomington, USA.
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15
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Lin JI, Mitchell NC, Kalcina M, Tchoubrieva E, Stewart MJ, Marygold SJ, Walker CD, Thomas G, Leevers SJ, Pearson RB, Quinn LM, Hannan RD. Drosophila ribosomal protein mutants control tissue growth non-autonomously via effects on the prothoracic gland and ecdysone. PLoS Genet 2011; 7:e1002408. [PMID: 22194697 PMCID: PMC3240600 DOI: 10.1371/journal.pgen.1002408] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 10/20/2011] [Indexed: 11/30/2022] Open
Abstract
The ribosome is critical for all aspects of cell growth due to its essential role in protein synthesis. Paradoxically, many Ribosomal proteins (Rps) act as tumour suppressors in Drosophila and vertebrates. To examine how reductions in Rps could lead to tissue overgrowth, we took advantage of the observation that an RpS6 mutant dominantly suppresses the small rough eye phenotype in a cyclin E hypomorphic mutant (cycEJP). We demonstrated that the suppression of cycEJP by the RpS6 mutant is not a consequence of restoring CycE protein levels or activity in the eye imaginal tissue. Rather, the use of UAS-RpS6 RNAi transgenics revealed that the suppression of cycEJP is exerted via a mechanism extrinsic to the eye, whereby reduced Rp levels in the prothoracic gland decreases the activity of ecdysone, the steroid hormone, delaying developmental timing and hence allowing time for tissue and organ overgrowth. These data provide for the first time a rationale to explain the counter-intuitive organ overgrowth phenotypes observed for certain members of the Minute class of Drosophila Rp mutants. They also demonstrate how Rp mutants can affect growth and development cell non-autonomously. Ribosomes are required for protein synthesis, which is essential for cell growth and division, thus mutations that reduce Rp expression would be expected to limit cell growth. Paradoxically, heterozygous deletion or mutation of certain Rps can actually promote growth and proliferation and in some cases bestow predisposition to cancer. The underlying mechanism(s) behind these unexpected overgrowth phenotypes despite impairment of ribosome biogenesis has remained obscure. We have addressed this question using the power of Drosophila genetics, taking advantage of our observation that four different Rp mutants, or Minutes, are able to suppress a small rough eye phenotype associated with a mutation of the essential controller of cell proliferation cyclin E (cycEJP). Our findings demonstrate that suppression of cycEJP by the RpS6 mutant is exerted via a tissue non-autonomous mechanism whereby reduced Rp in the prothoracic gland decreases activity of the steroid hormone ecdysone, delaying development and hence allowing time for compensatory growth. These data provide for the first time a rationale to explain the counter-intuitive organ overgrowth phenotypes observed for certain Drosophila Minutes. Our findings also have implications for the effect of Rp mutants on endocrine related control of tissue growth in higher organisms.
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Affiliation(s)
- Jane I. Lin
- Peter MacCallum Cancer Centre, East Melbourne, Australia
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Australia
| | - Naomi C. Mitchell
- Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Australia
| | - Marina Kalcina
- Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Australia
| | | | - Mary J. Stewart
- Department of Biological Sciences, North Dakota State University, Fargo, North Dakota, United States of America
| | - Steven J. Marygold
- Growth Regulation Laboratory, Cancer Research UK London Research Institute, London, United Kingdom
| | - Cherryl D. Walker
- Growth Regulation Laboratory, Cancer Research UK London Research Institute, London, United Kingdom
| | - George Thomas
- University of Cincinnati Medical Center, Cincinnati, Ohio, United States of America
| | - Sally J. Leevers
- Growth Regulation Laboratory, Cancer Research UK London Research Institute, London, United Kingdom
| | - Richard B. Pearson
- Peter MacCallum Cancer Centre, East Melbourne, Australia
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Australia
- Department of Biochemistry and Cell Biology, Monash University, Clayton, Australia
| | - Leonie M. Quinn
- Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Australia
- * E-mail: (LMQ); (RDH)
| | - Ross D. Hannan
- Peter MacCallum Cancer Centre, East Melbourne, Australia
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Australia
- Department of Biochemistry and Cell Biology, Monash University, Clayton, Australia
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
- * E-mail: (LMQ); (RDH)
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16
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Zielke N, Kim KJ, Tran V, Shibutani ST, Bravo MJ, Nagarajan S, van Straaten M, Woods B, von Dassow G, Rottig C, Lehner CF, Grewal SS, Duronio RJ, Edgar BA. Control of Drosophila endocycles by E2F and CRL4(CDT2). Nature 2011; 480:123-7. [PMID: 22037307 PMCID: PMC3330263 DOI: 10.1038/nature10579] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Accepted: 09/21/2011] [Indexed: 12/20/2022]
Abstract
Endocycles are variant cell cycles comprised of DNA Synthesis (S)- and Gap (G)- phases but lacking mitosis1,2. Such cycles facilitate post-mitotic growth in many invertebrate and plant cells, and are so ubiquitous that they may account for up to half the world’s biomass3,4. DNA replication in endocycling Drosophila cells is triggered by Cyclin E/Cyclin Dependent Kinase 2 (CycE/Cdk2), but this kinase must be inactivated during each G-phase to allow the assembly of pre-Replication Complexes (preRCs) for the next S-phase5,6. How CycE/Cdk2 is periodically silenced to allow re-replication has not been established. Here, using genetic tests in parallel with computational modeling, we show that Drosophila’s endocycles are driven by a molecular oscillator in which the E2F1 transcription factor promotes CycE expression and S-phase initiation, S-phase then activates the CRL4Cdt2 ubiquitin ligase, and this in turn mediates the destruction of E2F17. We propose that it is the transient loss of E2F1 during S-phases that creates the window of low Cdk activity required for preRC formation. In support of this model over-expressed E2F1 accelerated endocycling, whereas a stabilized variant of E2F1 blocked endocycling by de-regulating target genes including CycE, as well as Cdk1 and mitotic Cyclins. Moreover, we find that altering cell growth by changing nutrition or TOR signaling impacts E2F1 translation, thereby making endocycle progression growth-dependent. Many of the regulatory interactions essential to this novel cell cycle oscillator are conserved in animals and plants1,2,8, suggesting that elements of this mechanism act in most growth-dependent cell cycles.
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Affiliation(s)
- Norman Zielke
- German Cancer Research Center (DKFZ)-Zentrum für Molekulare Biologie der Universität Heidelberg Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
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17
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Acharya P, Raj N, Buckley MS, Zhang L, Duperon S, Williams G, Henry RW, Arnosti DN. Paradoxical instability-activity relationship defines a novel regulatory pathway for retinoblastoma proteins. Mol Biol Cell 2010; 21:3890-901. [PMID: 20861300 PMCID: PMC2982090 DOI: 10.1091/mbc.e10-06-0520] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Functional overlap of retinoblastoma protein stability and activity reveals a novel conserved regulatory pathway during Drosophila development. The Retinoblastoma (RB) transcriptional corepressor and related family of pocket proteins play central roles in cell cycle control and development, and the regulatory networks governed by these factors are frequently inactivated during tumorigenesis. During normal growth, these proteins are subject to tight control through at least two mechanisms. First, during cell cycle progression, repressor potential is down-regulated by Cdk-dependent phosphorylation, resulting in repressor dissociation from E2F family transcription factors. Second, RB proteins are subject to proteasome-mediated destruction during development. To better understand the mechanism for RB family protein instability, we characterized Rbf1 turnover in Drosophila and the protein motifs required for its destabilization. We show that specific point mutations in a conserved C-terminal instability element strongly stabilize Rbf1, but strikingly, these mutations also cripple repression activity. Rbf1 is destabilized specifically in actively proliferating tissues of the larva, indicating that controlled degradation of Rbf1 is linked to developmental signals. The positive linkage between Rbf1 activity and its destruction indicates that repressor function is governed in a manner similar to that described by the degron theory of transcriptional activation. Analogous mutations in the mammalian RB family member p107 similarly induce abnormal accumulation, indicating substantial conservation of this regulatory pathway.
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Affiliation(s)
- Pankaj Acharya
- Department of Microbiology and Molecular Genetics, Program in Genetics, Michigan State University, East Lansing, MI 48824-1319, USA
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18
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Gou D, Rubalcava M, Sauer S, Mora-Bermúdez F, Erdjument-Bromage H, Tempst P, Kremmer E, Sauer F. SETDB1 is involved in postembryonic DNA methylation and gene silencing in Drosophila. PLoS One 2010; 5:e10581. [PMID: 20498723 PMCID: PMC2871795 DOI: 10.1371/journal.pone.0010581] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Accepted: 03/29/2010] [Indexed: 11/19/2022] Open
Abstract
DNA methylation is fundamental for the stability and activity of genomes. Drosophila melanogaster and vertebrates establish a global DNA methylation pattern of their genome during early embryogenesis. Large-scale analyses of DNA methylation patterns have uncovered revealed that DNA methylation patterns are dynamic rather than static and change in a gene-specific fashion during development and in diseased cells. However, the factors and mechanisms involved in dynamic, postembryonic DNA methylation remain unclear. Methylation of lysine 9 in histone H3 (H3-K9) by members of the Su(var)3-9 family of histone methyltransferases (HMTs) triggers embryonic DNA methylation in Arthropods and Chordates. Here, we demonstrate that Drosophila SETDB1 (dSETDB1) can mediate DNA methylation and silencing of genes and retrotransposons. We found that dSETDB1 tri-methylates H3-K9 and binds methylated CpA motifs. Tri-methylation of H3-K9 by dSETDB1 mediates recruitment of DNA methyltransferase 2 (Dnmt2) and Su(var)205, the Drosophila ortholog of mammalian "Heterochromatin Protein 1", to target genes for dSETDB1. By enlisting Dnmt2 and Su(var)205, dSETDB1 triggers DNA methylation and silencing of genes and retrotransposons in Drosophila cells. DSETDB1 is involved in postembryonic DNA methylation and silencing of Rt1b{} retrotransposons and the tumor suppressor gene retinoblastoma family protein 1 (Rb) in imaginal discs. Collectively, our findings implicate dSETDB1 in postembryonic DNA methylation, provide a model for silencing of the tumor suppressor Rb, and uncover a role for cell type-specific DNA methylation in Drosophila development.
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Affiliation(s)
- Dawei Gou
- Department of Biochemistry, University of California Riverside, Riverside, California, United States of America
| | - Monica Rubalcava
- Department of Biochemistry, University of California Riverside, Riverside, California, United States of America
| | - Silvia Sauer
- Department of Biochemistry, University of California Riverside, Riverside, California, United States of America
| | - Felipe Mora-Bermúdez
- Zentrum für Molekulare Biologie der Universität Heidelberg, Universität Heidelberg, Heidelberg, Germany
| | - Hediye Erdjument-Bromage
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Paul Tempst
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Elisabeth Kremmer
- Institute of Molecular Immunology, Helmholtz Zentrum München, German Research Center for Environmental Health, München, Germany
| | - Frank Sauer
- Department of Biochemistry, University of California Riverside, Riverside, California, United States of America
- Zentrum für Molekulare Biologie der Universität Heidelberg, Universität Heidelberg, Heidelberg, Germany
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19
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Shibutani ST, de la Cruz AFA, Tran V, Turbyfill WJ, Reis T, Edgar BA, Duronio RJ. Intrinsic negative cell cycle regulation provided by PIP box- and Cul4Cdt2-mediated destruction of E2f1 during S phase. Dev Cell 2009; 15:890-900. [PMID: 19081076 DOI: 10.1016/j.devcel.2008.10.003] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Revised: 09/09/2008] [Accepted: 10/06/2008] [Indexed: 12/22/2022]
Abstract
E2F transcription factors are key regulators of cell proliferation that are inhibited by pRb family tumor suppressors. pRb-independent modes of E2F inhibition have also been described, but their contribution to animal development and tumor suppression is unclear. Here, we show that S phase-specific destruction of Drosophila E2f1 provides a novel mechanism for cell cycle regulation. E2f1 destruction is mediated by a PCNA-interacting-protein (PIP) motif in E2f1 and the Cul4(Cdt2) E3 ubiquitin ligase and requires the Dp dimerization partner but not direct Cdk phosphorylation or Rbf1 binding. E2f1 lacking a functional PIP motif accumulates inappropriately during S phase and is more potent than wild-type E2f1 at accelerating cell cycle progression and inducing apoptosis. Thus, S phase-coupled destruction is a key negative regulator of E2f1 activity. We propose that pRb-independent inhibition of E2F during S phase is an evolutionarily conserved feature of the metazoan cell cycle that is necessary for development.
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Affiliation(s)
- Shusaku T Shibutani
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
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20
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The N-terminal domain of the Drosophila retinoblastoma protein Rbf1 interacts with ORC and associates with chromatin in an E2F independent manner. PLoS One 2008; 3:e2831. [PMID: 18665226 PMCID: PMC2475671 DOI: 10.1371/journal.pone.0002831] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Accepted: 07/03/2008] [Indexed: 12/21/2022] Open
Abstract
Background The retinoblastoma (Rb) tumor suppressor protein can function as a DNA replication inhibitor as well as a transcription factor. Regulation of DNA replication may occur through interaction of Rb with the origin recognition complex (ORC). Principal Findings We characterized the interaction of Drosophila Rb, Rbf1, with ORC. Using expression of proteins in Drosophila S2 cells, we found that an N-terminal Rbf1 fragment (amino acids 1–345) is sufficient for Rbf1 association with ORC but does not bind to dE2F1. We also found that the C-terminal half of Rbf1 (amino acids 345–845) interacts with ORC. We observed that the amino-terminal domain of Rbf1 localizes to chromatin in vivo and associates with chromosomal regions implicated in replication initiation, including colocalization with Orc2 and acetylated histone H4. Conclusions/Significance Our results suggest that Rbf1 can associate with ORC and chromatin through domains independent of the E2F binding site. We infer that Rbf1 may play a role in regulating replication directly through its association with ORC and/or chromatin factors other than E2F. Our data suggest an important role for retinoblastoma family proteins in cell proliferation and tumor suppression through interaction with the replication initiation machinery.
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21
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Swanhart LM, Sanders AN, Duronio RJ. Normal regulation of Rbf1/E2f1 target genes in Drosophila type 1 protein phosphatase mutants. Dev Dyn 2007; 236:2567-77. [PMID: 17676643 DOI: 10.1002/dvdy.21265] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
G1 Cyclin/Cdk complexes phosphorylate and inactivate the pRb tumor suppressor by preventing its ability to bind and repress E2F transcription factors. Current molecular and biochemical evidence suggests that type 1 protein phosphatases (PP1) dephosphorylate and thereby activate pRb, but the functional significance of this has not been addressed in the context of animal development. Here, we use genetic analyses to determine the role of PP1 in the regulation of Rbf1 activity during Drosophila development. While Rbf1 is required for E2f1 inhibition and G1 arrest in the embryonic epidermis and for the periodic expression of E2f1 target genes during endocycle S phase in the embryonic midgut and larval salivary gland, PP1 is not. PP1 regulates periodic cyclin E protein accumulation in ovarian nurse cells independently of Rbf1, which is dispensable for endocycle regulation in this tissue. We conclude that PP1 is not a major regulator of the Rbf1/E2F1 pathway in Drosophila.
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Affiliation(s)
- Lisa M Swanhart
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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22
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Role of NAD binding and catalytic residues in the C-terminal binding protein corepressor. FEBS Lett 2007; 581:5241-6. [PMID: 17964573 DOI: 10.1016/j.febslet.2007.10.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Revised: 08/20/2007] [Accepted: 10/05/2007] [Indexed: 11/22/2022]
Abstract
CtBP corepressor proteins potentiate the activity of many metazoan transcriptional repressors. These proteins are homologous to prokaryotic D-2-hydroxyacid dehydrogenases, possessing an NAD/NADH binding fold and conserved active site residues. When expressed in Drosophila, a catalytic site mutant retains biological activity, however, we find that an NAD binding mutant lacks biological activity. The NAD mutant, similar to a dimerization mutant, is expressed at low levels, indicating that binding of NAD/NADH may affect CtBP stability. These data support the idea that the ancestral dehydrogenase activity is not required for CtBP function, and NAD binding may play a regulatory, rather than catalytic, role.
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23
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Tsai YC, Yao JG, Chen PH, Posakony JW, Barolo S, Kim J, Sun YH. Upd/Jak/STAT signaling represses wg transcription to allow initiation of morphogenetic furrow in Drosophila eye development. Dev Biol 2007; 306:760-71. [PMID: 17498684 DOI: 10.1016/j.ydbio.2007.04.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2007] [Revised: 04/08/2007] [Accepted: 04/11/2007] [Indexed: 12/23/2022]
Abstract
The initiation of retinal development in Drosophila begins at the posterior center (PC) of the eye disc margin. The front of the differentiation wave, recognized as a morphogenetic furrow (MF), moves from posterior to anterior. What determines MF initiates from the specific PC site is still unclear. The unpaired (upd) gene is expressed at PC at early third instar, just before the time of MF initiation. Therefore, upd is expressed at the appropriate time and location for a specific role in defining the site of MF initiation. upd encodes a ligand for the Jak/STAT signaling pathway. In this report, we showed that the Upd/Jak/STAT signaling is required and sufficient to determine MF initiation. This is primarily achieved by repressing the transcription of wingless (wg), which is known to block MF initiation.
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Affiliation(s)
- Yu-Chen Tsai
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan, Republic of China
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24
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Zacharek SJ, Xiong Y, Shumway SD. Negative regulation of TSC1-TSC2 by mammalian D-type cyclins. Cancer Res 2006; 65:11354-60. [PMID: 16357142 DOI: 10.1158/0008-5472.can-05-2236] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The metazoan cell cycle is driven by the timely and composite activities of cyclin-dependent kinases (CDKs). Among these, cyclin D- and cyclin E-dependent kinases phosphorylate the pRb family proteins during G(1) phase of the cell cycle and thereby advance cells beyond the restriction point. Increasing evidence suggests that cyclin D-dependent kinases might affect events other than Rb pathway-mediated entry into S phase, such as accumulation of cell mass. However, little is known about cyclin D activity toward Rb-independent pathway(s) or non-pRb substrates. In this article, we show that the tumor suppressor TSC2 is a cyclin D binding protein. Coexpression of cyclin D1-CDK4/6 in cultured cells leads to increased phosphorylation and decreased detection of both TSC2 and TSC1, and promotes the phosphorylation of the mTOR substrates, 4E-BP1 and S6K1, two key effectors of cell growth that are negatively regulated by the TSC1-TSC2 complex. At the cellular level, ectopic expression of cyclin D1 restores the cell size decrease caused by TSC1-TSC2 expression. Intriguingly, down-regulation of TSC proteins was also observed by the expression of a mutant cyclin D1 that is unable to bind to CDK4/6, or by the coexpression of cyclin D1 with either an INK4 inhibitor or with catalytically inactive CDK6, indicating that cyclin D may regulate TSC1-TSC2 independently of CDK4/6. Together, these observations suggest that mammalian D-type cyclins participate in cell growth control through negative regulation of TSC1-TSC2 function.
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Affiliation(s)
- Sima J Zacharek
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, 27599, USA
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25
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Abstract
The development of human cancer is a multistep process, involving the cooperation of mutations in signalling, cell-cycle and cell-death pathways, as well as interactions between the tumour and the tumour microenvironment. To dissect the steps of tumorigenesis, simple animal models are needed. This article discusses the use of the genetically amenable, multicellular organism, the vinegar fly Drosophila melanogaster. In particular, recent studies have highlighted the power of D. melanogaster for examining cooperative interactions between tumour suppressors and oncogenes and for generating in vivo models of tumour development and metastasis.
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Affiliation(s)
- Anthony M Brumby
- Cell Cycle and Development Group, Research Division, Peter MacCallum Cancer Centre, 7 St Andrew's Place, 3002, East Melbourne, Victoria, Australia.
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26
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Abstract
During metazoan development, the organization of the cell cycle is often modified in response to developmental signals. The endocycle provides a dramatic example of this phenomenon. In the endocycle, also referred to as the endoreplicative cycle, cells undergo successive rounds of DNA replication without an intervening mitosis. Often the endocycle is used to expand the genome of a group of specialized cells that are highly biosynthetically active. In these circumstances, large polyploid cells are produced in organisms that are primarily comprised of diploid cells. However, many organisms achieve growth by increasing cell size, rather than cell number. This strategy is more generally exploited in insects and plants. For instance, in the insect Drosophila melanogaster, the majority of the larval tissues, as well as many adult tissues, enter the endocycle and become polyploid. Therefore, Drosophila has been a rich source for studies on endocycle regulation. Recent work from Drosophila is beginning to reveal how developmental signals promote the transition from the mitotic cycle to the endocycle, as well as what drives endocycle progression. In addition, studies on the endocycle have provided insight into the regulatory principles underlying the once per cell cycle replication of the genome, as well as the relationship between S phase and mitosis.
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Affiliation(s)
- Mary A Lilly
- Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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27
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Brumby A, Secombe J, Horsfield J, Coombe M, Amin N, Coates D, Saint R, Richardson H. A genetic screen for dominant modifiers of a cyclin E hypomorphic mutation identifies novel regulators of S-phase entry in Drosophila. Genetics 2005; 168:227-51. [PMID: 15454540 PMCID: PMC1448096 DOI: 10.1534/genetics.104.026617] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Cyclin E together with its kinase partner Cdk2 is a critical regulator of entry into S phase. To identify novel genes that regulate the G1- to S-phase transition within a whole animal we made use of a hypomorphic cyclin E mutation, DmcycEJP, which results in a rough eye phenotype. We screened the X and third chromosome deficiencies, tested candidate genes, and carried out a genetic screen of 55,000 EMS or X-ray-mutagenized flies for second or third chromosome mutations that dominantly modified the DmcycEJP rough eye phenotype. We have focused on the DmcycEJP suppressors, S(DmcycEJP), to identify novel negative regulators of S-phase entry. There are 18 suppressor gene groups with more than one allele and several genes that are represented by only a single allele. All S(DmcycEJP) tested suppress the DmcycEJP rough eye phenotype by increasing the number of S phases in the postmorphogenetic furrow S-phase band. By testing candidates we have identified several modifier genes from the mutagenic screen as well as from the deficiency screen. DmcycEJP suppressor genes fall into the classes of: (1) chromatin remodeling or transcription factors; (2) signaling pathways; and (3) cytoskeletal, (4) cell adhesion, and (5) cytoarchitectural tumor suppressors. The cytoarchitectural tumor suppressors include scribble, lethal-2-giant-larvae (lgl), and discs-large (dlg), loss of function of which leads to neoplastic tumors and disruption of apical-basal cell polarity. We further explored the genetic interactions of scribble with S(DmcycEJP) genes and show that hypomorphic scribble mutants exhibit genetic interactions with lgl, scab (alphaPS3-integrin--cell adhesion), phyllopod (signaling), dEB1 (microtubule-binding protein--cytoskeletal), and moira (chromatin remodeling). These interactions of the cytoarchitectural suppressor gene, scribble, with cell adhesion, signaling, cytoskeletal, and chromatin remodeling genes, suggest that these genes may act in a common pathway to negatively regulate cyclin E or S-phase entry.
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Affiliation(s)
- Anthony Brumby
- Peter MacCallum Cancer Centre, East Melbourne, Victoria, 3002, Australia
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28
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Baonza A, Freeman M. Control of Cell Proliferation in the Drosophila Eye by Notch Signaling. Dev Cell 2005; 8:529-39. [PMID: 15809035 DOI: 10.1016/j.devcel.2005.01.019] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2004] [Revised: 11/17/2004] [Accepted: 01/10/2005] [Indexed: 11/24/2022]
Abstract
Cell proliferation in animals must be precisely controlled, but the signaling mechanisms that regulate the cell cycle are not well characterized. A regulated terminal mitosis, called the second mitotic wave (SMW), occurs during Drosophila eye development, providing a model for the genetic analysis of proliferation control. We report a cell cycle checkpoint at the G1-S transition that initiates the SMW, and we demonstrate that Notch signaling is required for cells to overcome this checkpoint. Notch triggers the onset of proliferation by multiple pathways, including the activation of dE2F1, a member of the E2F transcription factor family. Delta to Notch signaling derepresses the inhibition of dE2F1 by RBF, and Delta expression depends on the secreted proteins Hedgehog and Dpp. Notch is also required for the expression of Cyclin A in the SMW.
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Affiliation(s)
- Antonio Baonza
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, United Kingdom
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29
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Emmerich J, Meyer CA, de la Cruz AFA, Edgar BA, Lehner CF. Cyclin D does not provide essential Cdk4-independent functions in Drosophila. Genetics 2005; 168:867-75. [PMID: 15514060 PMCID: PMC1448836 DOI: 10.1534/genetics.104.027417] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The three mammalian D-type cyclins are thought to promote progression through the G1 phase of the cell cycle as regulatory subunits of cyclin-dependent kinase 4 and 6. In addition, they have been proposed to control the activity of various transcription factors without a partner kinase. Here we describe phenotypic consequences of null mutations in Cyclin D, the single D-type cyclin gene in Drosophila. As previously observed with null mutations in the single Drosophila Cdk4 gene, these mutations do not primarily affect progression through the G1 phase. Moreover, the apparently indistinguishable phenotypes of double (CycD and Cdk4) and single mutants (CycD or Cdk4) argue against major independent functions of Cyclin D and Cdk4. The reduced cellular and organismal growth rates observed in both mutants indicate that Cyclin D-Cdk4 acts as a growth driver.
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Affiliation(s)
- Jan Emmerich
- Bayreuther Zentrum für Molekulare Biowissenschaften, Department of Genetics, University of Bayreuth, 95440 Bayreuth, Germany
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30
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Edgar KA, Belvin M, Parks AL, Whittaker K, Mahoney MB, Nicoll M, Park CC, Winter CG, Chen F, Lickteig K, Ahmad F, Esengil H, Lorenzi MV, Norton A, Rupnow BA, Shayesteh L, Tabios M, Young LM, Carroll PM, Kopczynski C, Plowman GD, Friedman LS, Francis-Lang HL. Synthetic lethality of retinoblastoma mutant cells in the Drosophila eye by mutation of a novel peptidyl prolyl isomerase gene. Genetics 2005; 170:161-71. [PMID: 15744054 PMCID: PMC1449713 DOI: 10.1534/genetics.104.036343] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mutations that inactivate the retinoblastoma (Rb) pathway are common in human tumors. Such mutations promote tumor growth by deregulating the G1 cell cycle checkpoint. However, uncontrolled cell cycle progression can also produce new liabilities for cell survival. To uncover such liabilities in Rb mutant cells, we performed a clonal screen in the Drosophila eye to identify second-site mutations that eliminate Rbf(-) cells, but allow Rbf(+) cells to survive. Here we report the identification of a mutation in a novel highly conserved peptidyl prolyl isomerase (PPIase) that selectively eliminates Rbf(-) cells from the Drosophila eye.
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Affiliation(s)
- Kyle A Edgar
- Exelixis, South San Francisco, California 94083, USA
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31
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Frei C, Galloni M, Hafen E, Edgar BA. The Drosophila mitochondrial ribosomal protein mRpL12 is required for Cyclin D/Cdk4-driven growth. EMBO J 2005; 24:623-34. [PMID: 15692573 PMCID: PMC548645 DOI: 10.1038/sj.emboj.7600523] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2004] [Accepted: 11/25/2004] [Indexed: 11/08/2022] Open
Abstract
The Drosophila melanogaster cyclin-dependent protein kinase complex CycD/Cdk4 stimulates both cell cycle progression and cell growth (accumulation of mass). CycD/Cdk4 promotes cell cycle progression via the well-characterized RBF/E2F pathway, but our understanding of how growth is stimulated is still limited. To identify growth regulatory targets of CycD/Cdk4, we performed a loss-of-function screen for modifiers of CycD/Cdk4-induced overgrowth of the Drosophila eye. One mutation that suppressed CycD/Cdk4 was in a gene encoding the mitochondrial ribosomal protein, mRpL12. We show here that mRpL12 is required for CycD/Cdk4-induced cell growth. Cells homozygous mutant for mRpL12 have reduced mitochondrial activity, and exhibit growth defects that are very similar to those of cdk4 null cells. CycD/Cdk4 stimulates mitochondrial activity, and this is mRpL12 dependent. Hif-1 prolyl hydroxylase (Hph), another effector of CycD/Cdk4, regulates growth and is required for inhibition of the hypoxia-inducible transcription factor 1 (Hif-1). Both functions depend on mRpL12 dosage, suggesting that CycD/Cdk4, mRpL12 and Hph function together in a common pathway that controls cell growth via affecting mitochondrial activity.
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Affiliation(s)
- Christian Frei
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Zoologisches Institut, Universität Zürich, Zürich, Switzerland
- Institute of Cell Biology, HPM F39, ETH Hönggerberg, 8093 Zürich, Switzerland. Tel.: +41 1 633 3447; Fax: +41 1 633 1286; E-mail:
| | - Mireille Galloni
- INSERM-UM2 E343, Université de Montpellier 2, Montpellier, France
| | - Ernst Hafen
- Zoologisches Institut, Universität Zürich, Zürich, Switzerland
| | - Bruce A Edgar
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA. Tel.: +1 206 667 4185; Fax: +1 206 3308; E-mail:
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32
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Keller SA, Ullah Z, Buckley MS, Henry RW, Arnosti DN. Distinct developmental expression of Drosophila retinoblastoma factors. Gene Expr Patterns 2005; 5:411-21. [PMID: 15661648 DOI: 10.1016/j.modgep.2004.09.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2003] [Revised: 09/07/2004] [Accepted: 09/08/2004] [Indexed: 11/20/2022]
Abstract
Retinoblastoma (RB) tumor suppressor proteins are important regulators of the cell cycle and are implicated in a wide variety of human tumors. Genetic analysis of RB mutations in humans and in model systems indicates that individual RB proteins also have distinct functions in development. Specific target genes or mechanisms of action of individual RB proteins in developmental contexts are not well understood, however. To better understand the developmental activities of the two RB family members in Drosophila, we have characterized endogenous expression patterns of Rbf1 and Rbf2 proteins and transcripts in embryos and imaginal discs. These gene products are coexpressed at several stages of development, however, spatial and temporal differences are evident, including partly complementary patterns of expression in the embryonic central nervous system.
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Affiliation(s)
- Scott A Keller
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824-1319, USA
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33
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Frei C, Edgar BA. Drosophila Cyclin D/Cdk4 Requires Hif-1 Prolyl Hydroxylase to Drive Cell Growth. Dev Cell 2004; 6:241-51. [PMID: 14960278 DOI: 10.1016/s1534-5807(03)00409-x] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2003] [Revised: 12/16/2003] [Accepted: 12/19/2003] [Indexed: 01/06/2023]
Abstract
The Drosophila cyclin-dependent protein kinase complex Cyclin D/Cdk4 induces cell growth (accumulation of mass) as well as proliferation (cell cycle progression). To understand how CycD/Cdk4 promotes growth, we performed a screen for modifiers of CycD/Cdk4-driven overgrowth in the eye. Loss-of-function mutations in Hif-1 prolyl hydroxylase (Hph), an enzyme involved in the cellular response to hypoxic stress, dominantly suppress the growth but not the proliferation function of CycD/Cdk4. hph mutant cells are defective for growth, and, remarkably, ectopic expression of Hph is sufficient to increase cellular growth. Epistasis analysis places Hph downstream of CycD/Cdk4. Overexpressed CycD/Cdk4 causes an increase in Hph protein in tissues where Hph induces growth, suggesting a mechanism whereby Hph levels are regulated posttranscriptionally in response to CycD/Cdk4. Our data suggest that Hph, in addition to its function in hypoxic response, is a regulator of cellular growth and that it is a key mediator for CycD/Cdk4.
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Affiliation(s)
- Christian Frei
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, P.O. Box 19024, Seattle, WA 98109, USA.
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34
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Raisin S, Pantalacci S, Breittmayer JP, Léopold P. A new genetic locus controlling growth and proliferation in Drosophila melanogaster. Genetics 2003; 164:1015-25. [PMID: 12871911 PMCID: PMC1462610 DOI: 10.1093/genetics/164.3.1015] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Multicellular organisms grow through both proliferation and growth of their individual cells. We have conducted a P-element-based misexpression screen for genes whose upregulation alters wing disc growth during development. One particular group of four P elements, all inserted at cytological location 61C7-8, exhibited specific overgrowth upon misexpression in proliferating imaginal tissues. Clonal analysis revealed that upon misexpression, cell number was increased but cell size was not affected, indicating that cell growth and proliferation were induced in a coordinate manner. Loss of function at the locus produced small flies with reduced cell number, consistent with the presence of a gene encoding a positive growth regulator. We characterized a new transcription unit initiating in a region adjacent to the P insertions, which generated a complex series of polyadenylated transcripts. Although these RNAs were induced in response to misexpression, none was sufficient by itself to recapitulate overgrowth when overexpressed. This suggested either that a particular combination of these transcripts was necessary or that other sequences are involved.
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Affiliation(s)
- Sophie Raisin
- Institute for Signaling, Developmental Biology and Cancer Research, UMR6543 CNRS, Parc Valrose, 06108 Nice Cedex 2, France
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35
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Ma D, Zhou P, Harbour JW. Distinct mechanisms for regulating the tumor suppressor and antiapoptotic functions of Rb. J Biol Chem 2003; 278:19358-66. [PMID: 12646568 DOI: 10.1074/jbc.m301761200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The retinoblastoma protein, Rb, suppresses tumorigenesis by inhibiting cell proliferation and promoting senescence and differentiation. Paradoxically, Rb also inhibits apoptosis, which would seem to oppose its tumor suppressor function. Further, most human cancer cells inactivate Rb by hyperphosphorylation and demonstrate increased proliferative capacity but not high levels of apoptosis. As a potential explanation for these findings, we show here that the tumor suppressor and antiapoptotic functions of Rb are regulated by distinct phosphorylation events. Phosphorylation of sites in the C terminus occurs efficiently every cell cycle and regulates proliferation. Phosphorylation of Ser567 is inefficient and does not occur during the normal cell cycle. However, high cyclin-dependent kinase activity promotes phosphorylation of Ser567 by inducing an intramolecular interaction that leads to release of E2F, degradation of Rb, and susceptibility to apoptosis. Thus, phosphorylation of Ser567 may limit excessive proliferation by triggering cell death under hyperproliferative conditions. These findings suggest that the antiproliferative and antiapoptotic activities of Rb may represent complementary functions that work in concert to maintain the proliferation rate of cells within certain limits. As a survival strategy, some cancer cells may exploit this dual role of Rb by phosphorylating sites that regulate tumor suppression but avoiding phosphorylation of Ser567 and consequent apoptotic stimulus.
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Affiliation(s)
- Duanduan Ma
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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36
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Li FX, Zhu JW, Hogan CJ, DeGregori J. Defective gene expression, S phase progression, and maturation during hematopoiesis in E2F1/E2F2 mutant mice. Mol Cell Biol 2003; 23:3607-22. [PMID: 12724419 PMCID: PMC164755 DOI: 10.1128/mcb.23.10.3607-3622.2003] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
E2F plays critical roles in cell cycle progression by regulating the expression of genes involved in nucleotide synthesis, DNA replication, and cell cycle control. We show that the combined loss of E2F1 and E2F2 in mice leads to profound cell-autonomous defects in the hematopoietic development of multiple cell lineages. E2F2 mutant mice show erythroid maturation defects that are comparable with those observed in patients with megaloblastic anemia. Importantly, hematopoietic defects observed in E2F1/E2F2 double-knockout (DKO) mice appear to result from impeded S phase progression in hematopoietic progenitor cells. During DKO B-cell maturation, differentiation beyond the large pre-BII-cell stage is defective, presumably due to failed cell cycle exit, and the cells undergo apoptosis. However, apoptosis appears to be the consequence of failed maturation, not the cause. Despite the accumulation of hematopoietic progenitor cells in S phase, the combined loss of E2F1 and E2F2 results in significantly decreased expression and activities of several E2F target genes including cyclin A2. Our results indicate specific roles for E2F1 and E2F2 in the induction of E2F target genes, which contribute to efficient expansion and maturation of hematopoietic progenitor cells. Thus, E2F1 and E2F2 play essential and redundant roles in the proper coordination of cell cycle progression with differentiation which is necessary for efficient hematopoiesis.
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Affiliation(s)
- Feng X Li
- Department of Biochemistry and Molecular Genetics, Division of Medical Oncology, University of Colorado Health Sciences Center, 4200 East Ninth Avenue, Denver, CO 80262, USA
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37
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Thacker SA, Bonnette PC, Duronio RJ. The contribution of E2F-regulated transcription to Drosophila PCNA gene function. Curr Biol 2003; 13:53-8. [PMID: 12526745 DOI: 10.1016/s0960-9822(02)01400-8] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
E2F proteins control cell cycle progression by predominantly acting as either activators or repressors of transcription. How the antagonizing activities of different E2Fs are integrated by cis-acting control regions into a final transcriptional output in an intact animal is not well understood. E2F function is required for normal development in many species, but it is not completely clear for which genes E2F-regulated transcription provides an essential biological function. To address these questions, we have characterized the control region of the Drosophila PCNA gene. A single E2F binding site within a 100-bp enhancer is necessary and sufficient to direct the correct spatiotemporal program of G1-S-regulated PCNA expression during development. This dynamic program requires both E2F-mediated transcriptional activation and repression, which, in Drosophila, are thought to be carried out by two distinct E2F proteins. Our data suggest that functional antagonism between these different E2F proteins can occur in vivo by competition for the same binding site. An engineered PCNA gene with mutated E2F binding sites supports a low level of expression that can partially rescue the lethality of PCNA null mutants. Thus, E2F regulation of PCNA is dispensable for viability, but is nonetheless important for normal Drosophila development.
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Affiliation(s)
- Stephen A Thacker
- Program in Molecular Biology, University of North Carolina, 27599, Chapel Hill, NC, USA
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38
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Duman-Scheel M, Weng L, Xin S, Du W. Hedgehog regulates cell growth and proliferation by inducing Cyclin D and Cyclin E. Nature 2002; 417:299-304. [PMID: 12015606 DOI: 10.1038/417299a] [Citation(s) in RCA: 330] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Although mutations that activate the Hedgehog (Hh) signalling pathway have been linked to several types of cancer, the molecular and cellular basis of Hh's ability to induce tumour formation is not well understood. We identified a mutation in patched (ptc), an inhibitor of Hh signalling, in a genetic screen for regulators of the Retinoblastoma (Rb) pathway in Drosophila. Here we show that Hh signalling promotes transcription of Cyclin E and Cyclin D, two inhibitors of Rb, and principal regulators of the cell cycle during development in Drosophila. Upregulation of Cyclin E expression, accomplished through binding of Cubitus interruptus (Ci) to the Cyclin E promoter, mediates the ability of Hh to induce DNA replication. Upregulation of Cyclin D expression by Hh mediates the distinct ability of Hh to promote cellular growth. The discovery of a direct connection between Hh signalling and principal cell-cycle regulators provides insight into the mechanism by which deregulated Hh signalling promotes tumour formation.
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Affiliation(s)
- Molly Duman-Scheel
- Ben May Institute for Cancer Research and Center for Molecular Oncology, The University of Chicago, 924 E. 57th Street, Chicago, Illinois 60637, USA
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