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Zappia M, Kwon YJ, Westacott A, Liseth I, Lee H, Islam ABMMK, Kim J, Frolov M. E2F regulation of the Phosphoglycerate kinase gene is functionally important in Drosophila development. Proc Natl Acad Sci U S A 2023; 120:e2220770120. [PMID: 37011211 PMCID: PMC10104548 DOI: 10.1073/pnas.2220770120] [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: 12/06/2022] [Accepted: 03/03/2023] [Indexed: 04/05/2023] Open
Abstract
The canonical role of the transcription factor E2F is to control the expression of cell cycle genes by binding to the E2F sites in their promoters. However, the list of putative E2F target genes is extensive and includes many metabolic genes, yet the significance of E2F in controlling the expression of these genes remains largely unknown. Here, we used the CRISPR/Cas9 technology to introduce point mutations in the E2F sites upstream of five endogenous metabolic genes in Drosophila melanogaster. We found that the impact of these mutations on both the recruitment of E2F and the expression of the target genes varied, with the glycolytic gene, Phosphoglycerate kinase (Pgk), being mostly affected. The loss of E2F regulation on the Pgk gene led to a decrease in glycolytic flux, tricarboxylic acid cycle intermediates levels, adenosine triphosphate (ATP) content, and an abnormal mitochondrial morphology. Remarkably, chromatin accessibility was significantly reduced at multiple genomic regions in PgkΔE2F mutants. These regions contained hundreds of genes, including metabolic genes that were downregulated in PgkΔE2F mutants. Moreover, PgkΔE2F animals had shortened life span and exhibited defects in high-energy consuming organs, such as ovaries and muscles. Collectively, our results illustrate how the pleiotropic effects on metabolism, gene expression, and development in the PgkΔE2F animals underscore the importance of E2F regulation on a single E2F target, Pgk.
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Affiliation(s)
- Maria Paula Zappia
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL 60607
| | - Yong-Jae Kwon
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL 60607
| | - Anton Westacott
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL 60607
| | - Isabel Liseth
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL 60607
| | - Hyun Min Lee
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL 60607
| | - Abul B. M. M. K. Islam
- Department of Genetic Engineering and Biotechnology, University of Dhaka, Dhaka1000, Bangladesh
| | - Jiyeon Kim
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL 60607
| | - Maxim V. Frolov
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL 60607
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2
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Balachandra S, Sarkar S, Amodeo AA. The Nuclear-to-Cytoplasmic Ratio: Coupling DNA Content to Cell Size, Cell Cycle, and Biosynthetic Capacity. Annu Rev Genet 2022; 56:165-185. [PMID: 35977407 PMCID: PMC10165727 DOI: 10.1146/annurev-genet-080320-030537] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Though cell size varies between different cells and across species, the nuclear-to-cytoplasmic (N/C) ratio is largely maintained across species and within cell types. A cell maintains a relatively constant N/C ratio by coupling DNA content, nuclear size, and cell size. We explore how cells couple cell division and growth to DNA content. In some cases, cells use DNA as a molecular yardstick to control the availability of cell cycle regulators. In other cases, DNA sets a limit for biosynthetic capacity. Developmentally programmed variations in the N/C ratio for a given cell type suggest that a specific N/C ratio is required to respond to given physiological demands. Recent observations connecting decreased N/C ratios with cellular senescence indicate that maintaining the proper N/C ratio is essential for proper cellular functioning. Together, these findings suggest a causative, not simply correlative, role for the N/C ratio in regulating cell growth and cell cycle progression.
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Affiliation(s)
- Shruthi Balachandra
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA; ,
| | - Sharanya Sarkar
- Department of Microbiology and Immunology, Dartmouth College, Hanover, New Hampshire, USA;
| | - Amanda A Amodeo
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA; ,
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3
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Terradas G, Hermann A, James AA, McGinnis W, Bier E. High-resolution in situ analysis of Cas9 germline transcript distributions in gene-drive Anopheles mosquitoes. G3 (BETHESDA, MD.) 2022; 12:jkab369. [PMID: 34791161 PMCID: PMC8728002 DOI: 10.1093/g3journal/jkab369] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 10/14/2021] [Indexed: 11/12/2022]
Abstract
Gene drives are programmable genetic elements that can spread beneficial traits into wild populations to aid in vector-borne pathogen control. Two different drives have been developed for population modification of mosquito vectors. The Reckh drive (vasa-Cas9) in Anopheles stephensi displays efficient allelic conversion through males but generates frequent drive-resistant mutant alleles when passed through females. In contrast, the AgNosCd-1 drive (nos-Cas9) in Anopheles gambiae achieves almost complete allelic conversion through both genders. Here, we examined the subcellular localization of RNA transcripts in the mosquito germline. In both transgenic lines, Cas9 is strictly coexpressed with endogenous genes in stem and premeiotic cells of the testes, where both drives display highly efficient conversion. However, we observed distinct colocalization patterns for the two drives in female reproductive tissues. These studies suggest potential determinants underlying efficient drive through the female germline. We also evaluated expression patterns of alternative germline genes for future gene-drive designs.
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Affiliation(s)
- Gerard Terradas
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, USA
- Tata Institute for Genetics and Society, University of California, San Diego, La Jolla, CA 92093, USA
| | - Anita Hermann
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, USA
- Tata Institute for Genetics and Society, University of California, San Diego, La Jolla, CA 92093, USA
| | - Anthony A James
- Department of Microbiology and Molecular Genetics, University of California, Irvine, CA 92697, USA
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
| | - William McGinnis
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Ethan Bier
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, USA
- Tata Institute for Genetics and Society, University of California, San Diego, La Jolla, CA 92093, USA
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4
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Kim M, Delos Santos K, Moon NS. Proper CycE-Cdk2 activity in endocycling tissues requires regulation of the cyclin-dependent kinase inhibitor Dacapo by dE2F1b in Drosophila. Genetics 2021; 217:1-15. [PMID: 33683365 DOI: 10.1093/genetics/iyaa029] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Accepted: 12/06/2020] [Indexed: 01/05/2023] Open
Abstract
Polyploidy is an integral part of development and is associated with cellular stress, aging, and pathological conditions. The endocycle, comprised of successive rounds of G and S phases without mitosis, is widely employed to produce polyploid cells in plants and animals. In Drosophila, maintenance of the endocycle is dependent on E2F-governed oscillations of Cyclin E (CycE)-Cdk2 activity, which is known to be largely regulated at the level of transcription. In this study, we report an additional level of E2F-dependent control of CycE-Cdk2 activity during the endocycle. Genetic experiments revealed that an alternative isoform of Drosophila de2f1, dE2F1b, regulates the expression of the p27CIP/KIP-like Cdk inhibitor Dacapo (Dap). We provide evidence showing that dE2F1b-dependent Dap expression in endocycling tissues is necessary for setting proper CycE-Cdk2 activity. Furthermore, we demonstrate that dE2F1b is required for proliferating cell nuclear antigen expression that establishes a negative feedback loop in S phase. Overall, our study reveals previously unappreciated E2F-dependent regulatory networks that are critical for the periodic transition between G and S phases during the endocycle.
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Affiliation(s)
- Minhee Kim
- Department of Biology, Developmental Biology Research Initiative, McGill University, Montreal, Quebec H3A 1B1 Canada
| | - Keemo Delos Santos
- Department of Biology, Developmental Biology Research Initiative, McGill University, Montreal, Quebec H3A 1B1 Canada
| | - Nam-Sung Moon
- Department of Biology, Developmental Biology Research Initiative, McGill University, Montreal, Quebec H3A 1B1 Canada
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5
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Nandakumar S, Rozich E, Buttitta L. Cell Cycle Re-entry in the Nervous System: From Polyploidy to Neurodegeneration. Front Cell Dev Biol 2021; 9:698661. [PMID: 34249947 PMCID: PMC8264763 DOI: 10.3389/fcell.2021.698661] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 05/19/2021] [Indexed: 12/15/2022] Open
Abstract
Terminally differentiated cells of the nervous system have long been considered to be in a stable non-cycling state and are often considered to be permanently in G0. Exit from the cell cycle during development is often coincident with the differentiation of neurons, and is critical for neuronal function. But what happens in long lived postmitotic tissues that accumulate cell damage or suffer cell loss during aging? In other contexts, cells that are normally non-dividing or postmitotic can or re-enter the cell cycle and begin replicating their DNA to facilitate cellular growth in response to cell loss. This leads to a state called polyploidy, where cells contain multiple copies of the genome. A growing body of literature from several vertebrate and invertebrate model organisms has shown that polyploidy in the nervous system may be more common than previously appreciated and occurs under normal physiological conditions. Moreover, it has been found that neuronal polyploidization can play a protective role when cells are challenged with DNA damage or oxidative stress. By contrast, work over the last two and a half decades has discovered a link between cell-cycle reentry in neurons and several neurodegenerative conditions. In this context, neuronal cell cycle re-entry is widely considered to be aberrant and deleterious to neuronal health. In this review, we highlight historical and emerging reports of polyploidy in the nervous systems of various vertebrate and invertebrate organisms. We discuss the potential functions of polyploidization in the nervous system, particularly in the context of long-lived cells and age-associated polyploidization. Finally, we attempt to reconcile the seemingly disparate associations of neuronal polyploidy with both neurodegeneration and neuroprotection.
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Affiliation(s)
| | | | - Laura Buttitta
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
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6
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Ren D, Song J, Ni M, Kang L, Guo W. Regulatory Mechanisms of Cell Polyploidy in Insects. Front Cell Dev Biol 2020; 8:361. [PMID: 32548115 PMCID: PMC7272692 DOI: 10.3389/fcell.2020.00361] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 04/22/2020] [Indexed: 12/14/2022] Open
Abstract
Polyploidy cells undergo the endocycle to generate DNA amplification without cell division and have important biological functions in growth, development, reproduction, immune response, nutrient support, and conferring resistance to DNA damage in animals. In this paper, we have specially summarized current research progresses in the regulatory mechanisms of cell polyploidy in insects. First, insect hormones including juvenile hormone and 20-hydroxyecdysone regulate the endocycle of variant cells in diverse insect species. Second, cells skip mitotic division in response to developmental programming and conditional stimuli such as wound healing, regeneration, and aging. Third, the reported regulatory pathways of mitotic to endocycle switch (MES), including Notch, Hippo, and JNK signaling pathways, are summarized and constructed into genetic network. Thus, we think that the studies in crosstalk of hormones and their effects on canonical pathways will shed light on the mechanism of cell polyploidy and elucidate the evolutionary adaptions of MES through diverse insect species.
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Affiliation(s)
- Dani Ren
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Juan Song
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Ming Ni
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, Hebei University, Baoding, China
| | - Le Kang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, Hebei University, Baoding, China
| | - Wei Guo
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
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7
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Abstract
Polyploid cells contain more than two homologous sets of chromosomes. The original observations of liver polyploidy date back to the 1940s, but functional roles for polyploid cells are still unclear. Liver polyploidy may influence regeneration, stress response, and cancer, although little evidence has established direct causal links between polyploidy and these biological phenotypes. In this review, we will introduce broad concepts about polyploidy including its distribution in nature and how polyploids form in normal and pathological situations. Then we will examine recent discoveries that have begun to clarify functionality and disease relevance of liver polyploidy. Finally, we will discuss implications and future directions of research about polyploidy in the liver.
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Affiliation(s)
- Shuyuan Zhang
- a Children's Research Institute, Departments of Pediatrics and Internal Medicine, Center for Regenerative Science and Medicine , University of Texas Southwestern Medical Center , Dallas , USA
| | - Yu-Hsuan Lin
- a Children's Research Institute, Departments of Pediatrics and Internal Medicine, Center for Regenerative Science and Medicine , University of Texas Southwestern Medical Center , Dallas , USA
| | - Branden Tarlow
- b Department of Internal Medicine , University of Texas Southwestern Medical Center , Dallas , TX , USA
| | - Hao Zhu
- a Children's Research Institute, Departments of Pediatrics and Internal Medicine, Center for Regenerative Science and Medicine , University of Texas Southwestern Medical Center , Dallas , USA
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8
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Wu Z, Guo W, Yang L, He Q, Zhou S. Juvenile hormone promotes locust fat body cell polyploidization and vitellogenesis by activating the transcription of Cdk6 and E2f1. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2018; 102:1-10. [PMID: 30205150 DOI: 10.1016/j.ibmb.2018.09.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 09/07/2018] [Accepted: 09/07/2018] [Indexed: 06/08/2023]
Abstract
Juvenile hormone (JH) is known to promote cell polyploidization for insect vitellogenesis and egg production, but the underlying mechanisms remain poorly understood. Using the migratory locust Locusta migratoria as a model system, we report here that the expression of cyclin-dependent kinase 6 (Cdk6) and adenovirus E2 factor-1 (E2f1), the core mediators in cell cycle progression is regulated by JH and its receptor Methoprene-tolerant (Met). JH acts through its receptor complex comprised of Met and Taiman to directly activate the transcription of Cdk6 and E2f1. Depletion of Cdk6 or E2f1 results in significantly decreased ploidy, precocious mitotic entry and increased cell numbers in the fat body, accompanied by substantial reduction of Vitellogenin gene expression, blocked ovarian growth and arrested oocyte maturation. These findings indicate a crucial role of Cdk6 and E2f1 in JH-regulated polyploidization and vitellogenesis as well as a novel regulatory machinery for endocycling in insects.
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Affiliation(s)
- Zhongxia Wu
- Key Laboratory of Plant Stress Biology, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Wei Guo
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Libin Yang
- Key Laboratory of Plant Stress Biology, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Qiongjie He
- Key Laboratory of Plant Stress Biology, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Shutang Zhou
- Key Laboratory of Plant Stress Biology, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475004, China.
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9
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Kim M, Tang JP, Moon NS. An alternatively spliced form affecting the Marked Box domain of Drosophila E2F1 is required for proper cell cycle regulation. PLoS Genet 2018; 14:e1007204. [PMID: 29420631 PMCID: PMC5821395 DOI: 10.1371/journal.pgen.1007204] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 02/21/2018] [Accepted: 01/16/2018] [Indexed: 12/28/2022] Open
Abstract
Across metazoans, cell cycle progression is regulated by E2F family transcription factors that can function as either transcriptional activators or repressors. For decades, the Drosophila E2F family has been viewed as a streamlined RB/E2F network, consisting of one activator (dE2F1) and one repressor (dE2F2). Here, we report that an uncharacterized isoform of dE2F1, hereon called dE2F1b, plays an important function during development and is functionally distinct from the widely-studied dE2F1 isoform, dE2F1a. dE2F1b contains an additional exon that inserts 16 amino acids to the evolutionarily conserved Marked Box domain. Analysis of de2f1b-specific mutants generated via CRISPR/Cas9 indicates that dE2F1b is a critical regulator of the cell cycle during development. This is particularly evident in endocycling salivary glands in which a tight control of dE2F1 activity is required. Interestingly, close examination of mitotic tissues such as eye and wing imaginal discs suggests that dE2F1b plays a repressive function as cells exit from the cell cycle. We also provide evidence demonstrating that dE2F1b differentially interacts with RBF1 and alters the recruitment of RBF1 and dE2F1 to promoters. Collectively, our data suggest that dE2F1b is a novel member of the E2F family, revealing a previously unappreciated complexity in the Drosophila RB/E2F network.
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Affiliation(s)
- Minhee Kim
- Department of Biology, Developmental Biology Research Initiative, McGill University, Montreal, Quebec, Canada
| | - Jack P. Tang
- Department of Biology, Developmental Biology Research Initiative, McGill University, Montreal, Quebec, Canada
| | - Nam-Sung Moon
- Department of Biology, Developmental Biology Research Initiative, McGill University, Montreal, Quebec, Canada
- * E-mail:
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10
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Hinnant TD, Alvarez AA, Ables ET. Temporal remodeling of the cell cycle accompanies differentiation in the Drosophila germline. Dev Biol 2017; 429:118-131. [PMID: 28711427 DOI: 10.1016/j.ydbio.2017.07.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Revised: 06/15/2017] [Accepted: 07/05/2017] [Indexed: 12/27/2022]
Abstract
Development of multicellular organisms relies upon the coordinated regulation of cellular differentiation and proliferation. Growing evidence suggests that some molecular regulatory pathways associated with the cell cycle machinery also dictate cell fate; however, it remains largely unclear how the cell cycle is remodeled in concert with cell differentiation. During Drosophila oogenesis, mature oocytes are created through a series of precisely controlled division and differentiation steps, originating from a single tissue-specific stem cell. Further, germline stem cells (GSCs) and their differentiating progeny remain in a predominantly linear arrangement as oogenesis proceeds. The ability to visualize the stepwise events of differentiation within the context of a single tissue make the Drosophila ovary an exceptional model for study of cell cycle remodeling. To describe how the cell cycle is remodeled in germ cells as they differentiate in situ, we used the Drosophila Fluorescence Ubiquitin-based Cell Cycle Indicator (Fly-FUCCI) system, in which degradable versions of GFP::E2f1 and RFP::CycB fluorescently label cells in each phase of the cell cycle. We found that the lengths of the G1, S, and G2 phases of the cell cycle change dramatically over the course of differentiation, and identified the 4/8-cell cyst as a key developmental transition state in which cells prepare for specialized cell cycles. Our data suggest that the transcriptional activator E2f1, which controls the transition from G1 to S phase, is a key regulator of mitotic divisions in the early germline. Our data support the model that E2f1 is necessary for proper GSC proliferation, self-renewal, and daughter cell development. In contrast, while E2f1 degradation by the Cullin 4 (Cul4)-containing ubiquitin E3 ligase (CRL4) is essential for developmental transitions in the early germline, our data do not support a role for E2f1 degradation as a mechanism to limit GSC proliferation or self-renewal. Taken together, these findings provide further insight into the regulation of cell proliferation and the acquisition of differentiated cell fate, with broad implications across developing tissues.
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Affiliation(s)
- Taylor D Hinnant
- Department of Biology, East Carolina University, Greenville, NC 27858, USA
| | - Arturo A Alvarez
- Department of Biology, East Carolina University, Greenville, NC 27858, USA
| | - Elizabeth T Ables
- Department of Biology, East Carolina University, Greenville, NC 27858, USA.
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11
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Huang F, Saraf A, Florens L, Kusch T, Swanson SK, Szerszen LT, Li G, Dutta A, Washburn MP, Abmayr SM, Workman JL. The Enok acetyltransferase complex interacts with Elg1 and negatively regulates PCNA unloading to promote the G1/S transition. Genes Dev 2016; 30:1198-210. [PMID: 27198229 PMCID: PMC4888840 DOI: 10.1101/gad.271429.115] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 04/29/2016] [Indexed: 11/24/2022]
Abstract
KAT6 histone acetyltransferases (HATs) are highly conserved in eukaryotes and are involved in cell cycle regulation. However, information regarding their roles in regulating cell cycle progression is limited. Here, we report the identification of subunits of the Drosophila Enok complex and demonstrate that all subunits are important for its HAT activity. We further report a novel interaction between the Enok complex and the Elg1 proliferating cell nuclear antigen (PCNA)-unloader complex. Depletion of Enok in S2 cells resulted in a G1/S cell cycle block, and this block can be partially relieved by depleting Elg1. Furthermore, depletion of Enok reduced the chromatin-bound levels of PCNA in both S2 cells and early embryos, suggesting that the Enok complex may interact with the Elg1 complex and down-regulate its PCNA-unloading function to promote the G1/S transition. Supporting this hypothesis, depletion of Enok also partially rescued the endoreplication defects in Elg1-depleted nurse cells. Taken together, our study provides novel insights into the roles of KAT6 HATs in cell cycle regulation through modulating PCNA levels on chromatin.
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Affiliation(s)
- Fu Huang
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA; Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Anita Saraf
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA
| | - Laurence Florens
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA
| | - Thomas Kusch
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA
| | - Selene K Swanson
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA
| | - Leanne T Szerszen
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA
| | - Ge Li
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA
| | - Arnob Dutta
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA
| | - Michael P Washburn
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA; Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
| | - Susan M Abmayr
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA; Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
| | - Jerry L Workman
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA
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12
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Huelsmann S, Brown NH. Nuclear positioning by actin cables and perinuclear actin: Special and general? Nucleus 2014; 5:219-23. [PMID: 24905988 DOI: 10.4161/nucl.29405] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Nuclear positioning is an important process during development and homeostasis. Depending on the affected tissue, mislocalized nuclei can alter cellular processes such as polarization, differentiation, or migration and lead ultimately to diseases. Many cells actively control the position of their nucleus using their cytoskeleton and motor proteins. We have recently shown that during Drosophila oogenesis, nurse cells employ cytoplasmic actin cables in association with perinuclear actin to position their nucleus. Here, we briefly summarize our work and discuss why nuclear positioning in nurse cells is specialized but the molecular mechanisms are likely to be more generally used.
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Affiliation(s)
- Sven Huelsmann
- The Gurdon Institute and Department of Physiology, Development, and Neuroscience; University of Cambridge; Cambridge, UK; Department of Biological and Environmental Science; University of Jyväskylä; Jyväskylä, Finland
| | - Nicholas H Brown
- The Gurdon Institute and Department of Physiology, Development, and Neuroscience; University of Cambridge; Cambridge, UK
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13
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Clough E, Tedeschi T, Hazelrigg T. Epigenetic regulation of oogenesis and germ stem cell maintenance by the Drosophila histone methyltransferase Eggless/dSetDB1. Dev Biol 2014; 388:181-91. [PMID: 24485852 DOI: 10.1016/j.ydbio.2014.01.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Revised: 01/10/2014] [Accepted: 01/17/2014] [Indexed: 11/16/2022]
Abstract
The Drosophila melanogaster histone lysine methyltransferase (HKMT) Eggless (Egg/dSETDB1) catalyzes methylation of Histone H3 lysine 9 (H3K9), a signature of repressive heterochromatin. Our previous studies showed that H3K9 methylation by Egg is required for oogenesis. Here we analyze a set of EMS-induced mutations in the egg gene, identify the molecular lesions of these mutations, and compare the effects on oogenesis of both strong loss-of-function and weak hypomorphic alleles. These studies show that H3K9 methylation by Egg is required for multiple stages of oogenesis. Mosaic expression experiments show that the egg gene is not required intrinsically in the germ cells for their early differentiation, but is required in the germ cells for their survival past stage 5 of oogenesis. egg is also required in germ stem cells for their maintenance, since egg- germ stem cells initially survive but are not maintained as females age. Mosaic analysis also reveals that the early egg chamber budding defects in egg- ovaries are due to an intrinsic requirement for egg in follicle stem cells and their descendents, and that egg plays a non-autonomous role in somatic cells in the germarium to influence the differentiation of early germ cells.
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Affiliation(s)
- Emily Clough
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Thomas Tedeschi
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Tulle Hazelrigg
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
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14
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Bauer CR, Hartl TA, Bosco G. Condensin II promotes the formation of chromosome territories by inducing axial compaction of polyploid interphase chromosomes. PLoS Genet 2012; 8:e1002873. [PMID: 22956908 PMCID: PMC3431300 DOI: 10.1371/journal.pgen.1002873] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 06/23/2012] [Indexed: 12/02/2022] Open
Abstract
The eukaryotic nucleus is both spatially and functionally partitioned. This organization contributes to the maintenance, expression, and transmission of genetic information. Though our ability to probe the physical structure of the genome within the nucleus has improved substantially in recent years, relatively little is known about the factors that regulate its organization or the mechanisms through which specific organizational states are achieved. Here, we show that Drosophila melanogaster Condensin II induces axial compaction of interphase chromosomes, globally disrupts interchromosomal interactions, and promotes the dispersal of peri-centric heterochromatin. These Condensin II activities compartmentalize the nucleus into discrete chromosome territories and indicate commonalities in the mechanisms that regulate the spatial structure of the genome during mitosis and interphase. A number of recent studies have debunked the idea that chromosomes exist as a tangled mass of chromatin fibers within the nucleus. In many organisms, including mammals, each chromosome occupies a specific region of the nucleus known as a chromosome territory. This organization has implications for many biological processes such as chromosomal rearrangements that are common in cancer and the interactions between sub-nuclear structures that control how genes are expressed. Despite this, little is known about the genes or mechanisms that are responsible for creating or maintaining chromosome territories. Here, we show that the Condensin II complex can induce the formation of chromosome territories in fruit flies. We propose that this activity stems from the ability of Condensin II to reduce the length of chromosomes.
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Affiliation(s)
- Christopher R. Bauer
- Department of Molecular and Cellular Biology, The University of Arizona, Tucson, Arizona, United States of America
| | - Tom A. Hartl
- Department of Molecular and Cellular Biology, The University of Arizona, Tucson, Arizona, United States of America
| | - Giovanni Bosco
- Department of Molecular and Cellular Biology, The University of Arizona, Tucson, Arizona, United States of America
- Department of Genetics, The Geisel School of Medicine at Dartmouth, Dartmouth College, Hanover, New Hampshire, United States of America
- * E-mail:
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15
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Truscott M, Islam ABMMK, López-Bigas N, Frolov MV. mir-11 limits the proapoptotic function of its host gene, dE2f1. Genes Dev 2011; 25:1820-34. [PMID: 21856777 DOI: 10.1101/gad.16947411] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The E2F family of transcription factors regulates the expression of both genes associated with cell proliferation and genes that regulate cell death. The net outcome is dependent on cellular context and tissue environment. The mir-11 gene is located in the last intron of the Drosophila E2F1 homolog gene dE2f1, and its expression parallels that of dE2f1. Here, we investigated the role of miR-11 and found that miR-11 specifically modulated the proapoptotic function of its host gene, dE2f1. A mir-11 mutant was highly sensitive to dE2F1-dependent, DNA damage-induced apoptosis. Consistently, coexpression of miR-11 in transgenic animals suppressed dE2F1-induced apoptosis in multiple tissues, while exerting no effect on dE2F1-driven cell proliferation. Importantly, miR-11 repressed the expression of the proapoptotic genes reaper (rpr) and head involution defective (hid), which are directly regulated by dE2F1 upon DNA damage. In addition to rpr and hid, we identified a novel set of cell death genes that was also directly regulated by dE2F1 and miR-11. Thus, our data support a model in which the coexpression of miR-11 limits the proapoptotic function of its host gene, dE2f1, upon DNA damage by directly modulating a dE2F1-dependent apoptotic transcriptional program.
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Affiliation(s)
- Mary Truscott
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, Illinois 60607, USA
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16
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Baxley RM, Soshnev AA, Koryakov DE, Zhimulev IF, Geyer PK. The role of the Suppressor of Hairy-wing insulator protein in Drosophila oogenesis. Dev Biol 2011; 356:398-410. [PMID: 21651900 DOI: 10.1016/j.ydbio.2011.05.666] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 05/16/2011] [Accepted: 05/22/2011] [Indexed: 12/21/2022]
Abstract
The Drosophila Suppressor of Hairy wing [Su(Hw)] insulator protein has an essential role in the development of the female germline. Here we investigate the function of Su(Hw) in the ovary. We show that Su(Hw) is universally expressed in somatic cells, while germ cell expression is dynamic. Robust levels accumulate in post-mitotic germ cells, where Su(Hw) localization is limited to chromosomes within nurse cells, the specialized cells that support oocyte growth. Although loss of Su(Hw) causes global defects in nurse cell chromosome structure, we demonstrate that these architectural changes are not responsible for the block in oogenesis. Connections between the fertility and insulator functions of Su(Hw) were investigated through studies of the two gypsy insulator proteins, Modifier of (mdg4)67.2 (Mod67.2) and Centrosomal Protein of 190kDa (CP190). Accumulation of these proteins is distinct from Su(Hw), with Mod67.2 and CP190 showing uniform expression in all cells during early stages of oogenesis that diminishes in later stages. Although Mod67.2 and CP190 extensively co-localize with Su(Hw) on nurse cell chromosomes, neither protein is required for nurse cell chromosome development or oocyte production. These data indicate that while the gypsy insulator function requires both Mod67.2 and CP190, these proteins are not essential for oogenesis. These studies represent the first molecular investigations of Su(Hw) function in the germline, which uncover distinct requirements for Su(Hw) insulator and ovary functions.
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Affiliation(s)
- Ryan M Baxley
- Molecular Biology Program, University of Iowa, College of Medicine, Iowa City, IA 52242, USA
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17
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Intra J, Perotti ME, Pasini ME. Cloning, sequence identification and expression profile analysis of α-L-fucosidase gene from the Mediterranean fruit fly Ceratitis capitata. JOURNAL OF INSECT PHYSIOLOGY 2011; 57:452-461. [PMID: 21272587 DOI: 10.1016/j.jinsphys.2011.01.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2010] [Revised: 01/14/2011] [Accepted: 01/14/2011] [Indexed: 05/30/2023]
Abstract
The Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritidae) is one of the most destructive agricultural pests, a polyphagus insect of relevant economic importance and is widespread in many regions around the world. It is the best-studied fruit fly pest at genetic and molecular level and much has been learned on its ecology and behaviour. An α-L-fucosidase has been recently hypothesized to be involved in sperm-egg interactions in Drosophila melanogaster and in other Drosophila species. Here, a complete cDNA encoding a putative α-L-fucosidase of the medfly was amplified using the reverse polymerase chain reaction (RT-PCR) with degenerate based on the conserved coding sequence information of several insect α-L-fucosidases, cloned and sequenced (GenBank accession no. FJ177429). The coding region consisted of 1482 bp which encoded a 485-residues protein (named CcFUCA) with a predicted molecular mass of 56.1 kDa. The deduced protein sequence showed 75% amino acid identity to D. melanogaster α-L-fucosidase, and in fact the phylogenetic tree analysis revealed that CcFUCA had closer relationships with the α-L-fucosidases of drosophilid species. The tissue expression analysis indicated that CcFuca was expressed in a single transcript in all tissues, suggesting a ubiquitous localization pattern of the encoded protein. Our findings provide novel insights on a gene encoding a protein potentially involved in primary gamete interactions in C. capitata.
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Affiliation(s)
- Jari Intra
- Department of Biomolecular Sciences and Biotechnology, University of Milano, via Celoria 26, 20133 Milano, Italy
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18
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Klusza S, Deng WM. poly is required for nurse-cell chromosome dispersal and oocyte polarity in Drosophila. Fly (Austin) 2010; 4:128-36. [PMID: 20473032 DOI: 10.4161/fly.4.2.11954] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
During Drosophila oogenesis, nurse cells undergo changes in chromosomal morphology, first from the polytenic form to a transient condensed phase known as the five-blob configuration, then into a diffuse polytenic-polyploid state for the remainder of oogenesis. The mechanism by which nurse-cell chromosome dispersal is regulated remains elusive. Mutations in several genes, including the heterogeneous ribonucleoprotein genes squid (sqd) and hrb27C, the alternative splicing factor gene poly U binding factor 68 kDa (pUf68, also known as half-pint), and the germ-line-specific gene ovarian tumor (otu), that produce defects in nurse-cell chromosome dispersal also produce defects in oocyte polarity, suggesting a link between these two processes. Here, we characterize a novel gene named poly, which, when mutated in the germ line, disrupts nurse-cell chromosome dispersal, as well as localization of anteroposterior and dorsoventral determinants in the oocyte. We also show that poly interacts genetically with hrb27C and otu. We conclude that poly is required for nurse-cell chromosome dispersal and oocyte polarization in the Drosophila germ-line. In addition, our interaction data suggest that poly is probably a member of the characterized mRNP complex that mediates both processes.
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Affiliation(s)
- Stephen Klusza
- Department of Biological Science, Florida State University, Tallahassee, USA
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19
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Maric C, Prioleau MN. Interplay between DNA replication and gene expression: a harmonious coexistence. Curr Opin Cell Biol 2010; 22:277-83. [PMID: 20363609 DOI: 10.1016/j.ceb.2010.03.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Revised: 03/11/2010] [Accepted: 03/12/2010] [Indexed: 01/01/2023]
Abstract
Multicellular organisms have evolved highly sophisticated machinery to that their genomes are accurately duplicated and that the various gene expression programs are established correctly. Recent large-scale studies have shed light on how these fundamental processes interact. Although the machinery mediating these processes share similar cis-regulatory elements, they are not strictly coregulated. Furthermore, studies of the replisome show that highly transcribed genes present a major obstacle to its operation. Further studies will be needed to identify key regulators of the spatio-temporal program of DNA replication, for the elucidation of the complex interplay between replication and transcription.
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Affiliation(s)
- Chrystelle Maric
- Institut Jacques Monod, Centre National de la Recherche Scientifique, Université Paris 7, Paris, France
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20
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Abstract
A great many cell types are necessary for the myriad capabilities of complex, multicellular organisms. One interesting aspect of this diversity of cell type is that many cells in diploid organisms are polyploid. This is called endopolyploidy and arises from cell cycles that are often characterized as "variant," but in fact are widespread throughout nature. Endopolyploidy is essential for normal development and physiology in many different organisms. Here we review how both plants and animals use variations of the cell cycle, termed collectively as endoreplication, resulting in polyploid cells that support specific aspects of development. In addition, we discuss briefly how endoreplication occurs in response to certain physiological stresses, and how it may contribute to the development of cancer. Finally, we describe the molecular mechanisms that support the onset and progression of endoreplication.
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21
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Abstract
The Drosophila melanogaster ovary is a powerful yet simple system with only a few cell types. Cell death in the ovary can be induced in response to multiple developmental and environmental signals. These cell deaths occur at distinct stages of oogenesis and involve unique mechanisms utilizing apoptotic, autophagic and perhaps necrotic processes. In this review, we summarize recent progress characterizing cell death mechanisms in the fly ovary.
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22
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Rutkowski RJ, Warren WD. Phenotypic analysis of deflated/Ints7 function in Drosophila development. Dev Dyn 2009; 238:1131-9. [PMID: 19326441 DOI: 10.1002/dvdy.21922] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The Drosophila gene deflated (CG18176; renamed after the pupal lethal abdominal phenotype of mutant individuals) is a member of a conserved gene family found in all multicellular organisms. The human orthologue of deflated (Ints7) encodes a subunit of the Integrator complex that associates with RNA polymerase II and has been implicated in snRNA processing. Since loss-of-function analyses of deflated have not yet been reported, we undertook to investigate deflated expression patterns and mutant phenotypes. deflated mRNA was detected at low levels in proliferating cells in postblastoderm embryos and GFP tagged protein is predominately nuclear. Generation and analysis of four mutant alleles revealed deflated is essential for normal development, as mutant individuals displayed pleiotropic defects affecting many stages of development, consistent with perturbation of cell signalling or cell proliferation. Our data demonstrate multiple roles in development for an Ints7 homologue and to demonstrate its requirement for normal cell signalling and proliferation.
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Affiliation(s)
- Rachael J Rutkowski
- Comparative Genomics Centre, James Cook University, Townsville, Queensland, Australia
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23
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Abstract
Proteins that are related to the retinoblastoma tumour suppressor pRB and the E2F transcription factor are conserved in many species of plants and animals. The mammalian orthologues of pRB and E2F are best known for their roles in cell proliferation, but it has become clear that they affect many biological processes. Here we describe the functions of pRB-related proteins and E2F proteins that have emerged from genetic and biochemical experiments in Caenorhabditis elegans and Drosophila melanogaster. The similarities that have been observed between worms, flies and mammals provide insight into the core activities of pRB and E2F proteins and show how a common regulatory module can control various biological functions in different organisms.
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24
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Pasini ME, Intra J, Pavesi G. Expression study of an α-l-fucosidase gene in the Drosophilidae family. Gene 2008; 420:23-33. [DOI: 10.1016/j.gene.2008.04.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Revised: 04/22/2008] [Accepted: 04/30/2008] [Indexed: 01/29/2023]
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25
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Analysis of Drosophila species genome size and satellite DNA content reveals significant differences among strains as well as between species. Genetics 2008; 177:1277-90. [PMID: 18039867 DOI: 10.1534/genetics.107.075069] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The size of eukaryotic genomes can vary by several orders of magnitude, yet genome size does not correlate with the number of genes nor with the size or complexity of the organism. Although "whole"-genome sequences, such as those now available for 12 Drosophila species, provide information about euchromatic DNA content, they cannot give an accurate estimate of genome sizes that include heterochromatin or repetitive DNA content. Moreover, genome sequences typically represent only one strain or isolate of a single species that does not reflect intraspecies variation. To more accurately estimate whole-genome DNA content and compare these estimates to newly assembled genomes, we used flow cytometry to measure the 2C genome values, relative to Drosophila melanogaster. We estimated genome sizes for the 12 sequenced Drosophila species as well as 91 different strains of 38 species of Drosophilidae. Significant differences in intra- and interspecific 2C genome values exist within the Drosophilidae. Furthermore, by measuring polyploid 16C ovarian follicle cell underreplication we estimated the amount of satellite DNA in each of these species. We found a strong correlation between genome size and amount of satellite underreplication. Addition and loss of heterochromatin satellite repeat elements appear to have made major contributions to the large differences in genome size observed in the Drosophilidae.
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26
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Drosophila sticky/citron kinase is a regulator of cell-cycle progression, genetically interacts with Argonaute 1 and modulates epigenetic gene silencing. Genetics 2008; 178:1311-25. [PMID: 18245345 DOI: 10.1534/genetics.107.082511] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The sticky/citron kinase protein is a conserved regulator of cell-cycle progression from invertebrates to humans. While this kinase is essential for completion of cytokinesis, sticky/citron kinase phenotypes disrupting neurogenesis and cell differentiation suggest additional non-cell-cycle functions. However, it is not known whether these phenotypes are an indirect consequence of sticky mutant cell-cycle defects or whether they define a novel function for this kinase. We have isolated a temperature-sensitive allele of the Drosophila sticky gene and we show that sticky/citron kinase is required for histone H3-K9 methylation, HP1 localization, and heterochromatin-mediated gene silencing. sticky genetically interacts with Argonaute 1 and sticky mutants exhibit context-dependent Su(var) and E(var) activity. These observations indicate that sticky/citron kinase functions to regulate both actin-myosin-mediated cytokinesis and epigenetic gene silencing, possibly linking cell-cycle progression to heterochromatin assembly and inheritance of gene expression states.
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27
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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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28
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Riparbelli MG, Gigliotti S, Callaini G. The Drosophila nucleoporin gene nup154 is required for correct microfilament dynamics and cell death during oogenesis. ACTA ACUST UNITED AC 2007; 64:590-604. [PMID: 17410542 DOI: 10.1002/cm.20206] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The Drosophila nucleoporin gene nup154 is required in both male and female germline for successful gametogenesis. Mutant flies lack differentiated sperm and lay abnormal eggs. We demonstrated that the egg phenotype was associated with specific alterations of the actin cytoskeleton at different stages of oogenesis. Actually, mutant egg chambers displayed an abnormal organization of both subcortical microfilaments and cytoplasmic actin bundles, that led to defective nurse cell dumping. TUNEL analysis also showed that the dumpless phenotype was associated with delayed apoptosis. The nup154 gene product was localized by conventional immunofluorescence microscopy to the nuclear envelope in a distinct punctuate pattern, characteristic of nuclear pore complex components. TEM analysis revealed that the protein was mainly distributed along filamentous structures that extended radially on the nuclear side of the pore, suggesting that Nup154 could be an integral component of the basket filaments associated with the nuclear pore complexes. We propose that Nup154 is necessary for correct nuclear pore complex functions and that the proper regulation of the actin cytoskeleton dynamics strongly relies upon nuclear pore integrity.
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29
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Sasaki T, Gilbert DM. The many faces of the origin recognition complex. Curr Opin Cell Biol 2007; 19:337-43. [PMID: 17466500 DOI: 10.1016/j.ceb.2007.04.007] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Accepted: 04/13/2007] [Indexed: 12/12/2022]
Abstract
The hetero-hexameric origin recognition complex (ORC) is well known for its separable roles in DNA replication and heterochromatin assembly. However, ORC and its individual subunits have been implicated in diverse cellular activities in both the nucleus and the cytoplasm. Some of ORC's implied functions, such as cell cycle checkpoint control and mitotic chromosome assembly, may be indirectly related to its roles in replication control and/or heterochromatin assembly. Other suggested roles in ribosomal biogenesis and in centrosome and kinetochore function are based on localization/interaction data and are as yet inconclusive. However, recent findings directly link ORC to sister chromatin cohesion, cytokinesis and neural dendritic branching.
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Affiliation(s)
- Takayo Sasaki
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
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30
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Hartl T, Boswell C, Orr-Weaver TL, Bosco G. Developmentally regulated histone modifications in Drosophila follicle cells: initiation of gene amplification is associated with histone H3 and H4 hyperacetylation and H1 phosphorylation. Chromosoma 2007; 116:197-214. [PMID: 17219175 DOI: 10.1007/s00412-006-0092-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2006] [Accepted: 11/22/2006] [Indexed: 12/18/2022]
Abstract
We have used gene amplification in Drosophila follicle cells as a model of metazoan DNA replication to address whether changes in histone modifications are associated with replication origin activation. We observe that replication initiation is associated with distinct histone modifications. Acetylated lysines K5, K8, and K12 on histone H4 and K14 on histone H3 are specifically enriched during replication initiation at the amplification origins. Strikingly, H4 acetylation persists at an amplification origin well after replication forks have progressed significantly outward from the origin, indicating that H4 acetylation is associated with origin regulation and not histone deposition at the replication forks. Origin recognition complex subunit 2 (orc2) mutants with severe amplification defects do not abolish H4 acetylation, whereas the dup/cdt1 mutant delays the appearance of acetylation foci, and mutants in rbf result in temporal persistence. These data indicate that core histone acetylation is associated with origin activity. Furthermore, follicle cells undergoing gene amplification exhibit high levels of histone H1 phosphorylation. The patterns of H1 phosphorylation provide insights into cell cycle states during amplification, as H1 kinase activity in follicle cells is responsive to high Cyclin E activity, and it can be abolished by overexpressing the retinoblastoma homolog, Rbf, that represses Cyclin E. These data suggest that amplification origins are able to initiate when the cells are in a late S-phase, when the genome is normally not licensed for replication.
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Affiliation(s)
- Tom Hartl
- Department of Molecular and Cellular Biology, Arizona Cancer Center, University of Arizona, Tucson, AZ 85724, USA
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31
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Stanelle J, Pützer BM. E2F1-induced apoptosis: turning killers into therapeutics. Trends Mol Med 2006; 12:177-85. [PMID: 16530485 DOI: 10.1016/j.molmed.2006.02.002] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Revised: 01/30/2006] [Accepted: 02/17/2006] [Indexed: 01/04/2023]
Abstract
The cellular transcription factor E2F1 is part of an anti-tumor safeguard mechanism: it engages cell-death pathways either alone or in cooperation with p53 to protect organisms from the development of tumors. E2F1 activates downstream factors, which in turn produce secondary changes in gene expression that trigger apoptosis. Although the mechanisms are incompletely understood, several studies have demonstrated that E2F1 is involved in many different aspects of programmed cell death depending on the cellular background. Here, these findings are highlighted in the context of the most recent follow-up studies that have used apoptotic E2F1 genes as new therapeutics or drug targets, thereby providing insight into the basic mechanisms of E2F1-induced apoptosis and its possible clinical implications.
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Affiliation(s)
- Jens Stanelle
- Department of Vectorology and Experimental Gene Therapy, University of Rostock, Schillingallee 70, 18057 Rostock, Germany
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32
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Moon NS, Frolov MV, Kwon EJ, Di Stefano L, Dimova DK, Morris EJ, Taylor-Harding B, White K, Dyson NJ. Drosophila E2F1 has context-specific pro- and antiapoptotic properties during development. Dev Cell 2005; 9:463-75. [PMID: 16198289 DOI: 10.1016/j.devcel.2005.08.015] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2005] [Revised: 07/19/2005] [Accepted: 08/25/2005] [Indexed: 01/28/2023]
Abstract
E2F transcription factors are generally believed to be positive regulators of apoptosis. In this study, we show that dE2F1 and dDP are important for the normal pattern of DNA damage-induced apoptosis in Drosophila wing discs. Unexpectedly, the role that E2F plays varies depending on the position of the cells within the disc. In irradiated wild-type discs, intervein cells show a high level of DNA damage-induced apoptosis, while cells within the D/V boundary are protected. In irradiated discs lacking E2F regulation, intervein cells are largely protected, but apoptotic cells are found at the D/V boundary. The protective effect of E2F at the D/V boundary is due to a spatially restricted role in the repression of hid. These loss-of-function experiments demonstrate that E2F cannot be classified simply as a pro- or antiapoptotic factor. Instead, the overall role of E2F in the damage response varies greatly and depends on the cellular context.
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Affiliation(s)
- Nam-Sung Moon
- Massachusetts General Hospital Cancer Research Center, Charlestown, Massachusetts 02129, USA
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33
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Wallace JA, Orr-Weaver TL. Replication of heterochromatin: insights into mechanisms of epigenetic inheritance. Chromosoma 2005; 114:389-402. [PMID: 16220346 DOI: 10.1007/s00412-005-0024-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2005] [Revised: 08/13/2005] [Accepted: 08/15/2005] [Indexed: 12/20/2022]
Abstract
Heterochromatin is composed of tightly condensed chromatin in which the histones are deacetylated and methylated, and specific nonhistone proteins are bound. Additionally, in vertebrates and plants, the DNA within heterochromatin is methylated. As the heterochromatic state is stably inherited, replication of heterochromatin requires not only duplication of the DNA but also a reinstallment of the appropriate protein and DNA modifications. Thus replication of heterochromatin provides a framework for understanding mechanisms of epigenetic inheritance. In recent studies, roles have been identified for replication factors in reinstating heterochromatin, particularly functions for origin recognition complex, proliferating cell nuclear antigen, and chromatin-assembly factor 1 in recruiting the heterochromatin binding protein HP1, a histone methyltransferase, a DNA methyltransferase, and a chromatin remodeling complex. Potential mechanistic links between these factors are discussed. In some cells, replication of the heterochromatin is blocked, and in Drosophila this inhibition is mediated by a chromatin binding protein SuUR.
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34
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Muzzopappa M, Wappner P. Multiple roles of the F-box protein Slimb inDrosophilaegg chamber development. Development 2005; 132:2561-71. [PMID: 15857915 DOI: 10.1242/dev.01839] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Substrate-specific degradation of proteins by the ubiquitin-proteasome pathway is a precise mechanism that controls the abundance of key cell regulators. SCF complexes are a family of E3 ubiquitin ligases that target specific proteins for destruction at the 26S-proteasome. These complexes are composed of three constant polypeptides – Skp1, Cullin1/3 and Roc1/Rbx1– and a fourth variable adapter, the F-box protein. Slimb (Slmb) is a Drosophila F-Box protein that fulfills several roles in development and cell physiology. We analyzed its participation in egg chamber development and found that slmb is required in both the follicle cells and the germline at different stages of oogenesis. We observed that in slmbsomatic clones, morphogenesis of the germarium and encapsulation of the cyst were altered, giving rise to egg chambers with extra germline cells and two oocytes. Furthermore, in slmb somatic clones, we observed ectopic Fasciclin 3 expression, suggesting a delay in follicle cell differentiation,which correlated with the occurrence of ectopic polar cells, lack of interfollicular stalks and mislocalization of the oocyte. Later in oogenesis,Slmb was required in somatic cells to specify the position, size and morphology of dorsal appendages. Mild overactivation of the Dpp pathway caused similar phenotypes that could be antagonized by simultaneous overexpression of Slmb, suggesting that Slmb might normally downregulate the Dpp pathway in follicle cells. Indeed, ectopic expression of a dad-LacZ enhancer trap revealed that the Dpp pathway was upregulated in slmb somatic clones and, consistent with this, ectopic accumulation of the co-Smad protein,Medea, was recorded. By analyzing slmb germline clones, we found that loss of Slmb provoked a reduction in E2f2 and Dp levels, which correlated with misregulation of mitotic cycles during cyst formation, abnormal nurse cell endoreplication and impairment of dumping of the nurse cell content into the oocyte.
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Affiliation(s)
- Mariana Muzzopappa
- Instituto Leloir and IIB, FCEyN-Universidad de Buenos Aires, Patricias Argentinas 435, Buenos Aires, 1405, Argentina
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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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36
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Abstract
In many organisms, programmed cell death of germ cells is required for normal development. This often occurs through highly conserved events including the transfer of vital cellular material to the growing gametes following death of neighboring cells. Germline cell death also plays a role in such diverse processes as removal of abnormal or superfluous cells at certain checkpoints, establishment of caste differentiation, and individualization of gametes. This review focuses on the cell death events that occur during gametogenesis in both vertebrates and invertebrates. It also examines the signals and machinery that initiate and carry out these germ cell deaths.
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Affiliation(s)
- J S Baum
- Department of Biology, Boston University, 5 Cummington St., Boston, MA 02215, USA
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37
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McCall K. Eggs over easy: cell death in the Drosophila ovary. Dev Biol 2004; 274:3-14. [PMID: 15355784 DOI: 10.1016/j.ydbio.2004.07.017] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2004] [Revised: 07/07/2004] [Accepted: 07/21/2004] [Indexed: 11/22/2022]
Abstract
Programmed cell death is the most common fate of female germ cells in Drosophila and many animals. In Drosophila, oocytes form in individual egg chambers that are supported by germline nurse cells and surrounded by somatic follicle cells. As oogenesis proceeds, 15 nurse cells die for every oocyte that is produced. In addition to this developmentally regulated cell death, groups of germ cells or entire egg chambers may be induced to undergo apoptosis in response to starvation or other insults. Recent findings suggest that these different types of cell death involve distinct genetic pathways. This review focuses on progress towards elucidating the molecular mechanisms acting during programmed cell death in Drosophila oogenesis.
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Affiliation(s)
- Kimberly McCall
- Department of Biology, Boston University, Boston, MA 02215, USA.
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Claycomb JM, Benasutti M, Bosco G, Fenger DD, Orr-Weaver TL. Gene amplification as a developmental strategy: isolation of two developmental amplicons in Drosophila. Dev Cell 2004; 6:145-55. [PMID: 14723854 DOI: 10.1016/s1534-5807(03)00398-8] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Gene amplification is known to be critical for upregulating gene expression in a few cases, but the extent to which amplification is utilized in the development of diverse organisms remains unknown. By quantifying genomic DNA hybridization to microarrays to assay gene copy number, we identified two additional developmental amplicons in the follicle cells of the Drosophila ovary. Both amplicons contain genes which, following their amplification, are expressed in the follicle cells, and the expression of three of these genes becomes restricted to specialized follicle cells late in differentiation. Genetic analysis establishes that at least one of these genes, yellow-g, is critical for follicle cell function, because mutations in yellow-g disrupt eggshell integrity. Thus, during follicle cell differentiation the entire genome is overreplicated as the cells become polyploid, and subsequently specific genomic intervals are overreplicated to facilitate gene expression.
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Affiliation(s)
- Julie M Claycomb
- Whitehead Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
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Zhimulev IF, Belyaeva ES, Semeshin VF, Koryakov DE, Demakov SA, Demakova OV, Pokholkova GV, Andreyeva EN. Polytene Chromosomes: 70 Years of Genetic Research. INTERNATIONAL REVIEW OF CYTOLOGY 2004; 241:203-75. [PMID: 15548421 DOI: 10.1016/s0074-7696(04)41004-3] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Polytene chromosomes were described in 1881 and since 1934 they have served as an outstanding model for a variety of genetic experiments. Using the polytene chromosomes, numerous biological phenomena were discovered. First the polytene chromosomes served as a model of the interphase chromosomes in general. In polytene chromosomes, condensed (bands), decondensed (interbands), genetically active (puffs), and silent (pericentric and intercalary heterochromatin as well as regions subject to position effect variegation) regions were found and their features were described in detail. Analysis of the general organization of replication and transcription at the cytological level has become possible using polytene chromosomes. In studies of sequential puff formation it was found for the first time that the steroid hormone (ecdysone) exerts its action through gene activation, and that the process of gene activation upon ecdysone proceeds as a cascade. Namely on the polytene chromosomes a new phenomenon of cellular stress response (heat shock) was discovered. Subsequently chromatin boundaries (insulators) were discovered to flank the heat shock puffs. Major progress in solving the problems of dosage compensation and position effect variegation phenomena was mainly related to studies on polytene chromosomes. This review summarizes the current status of studies of polytene chromosomes and of various phenomena described using this successful model.
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Affiliation(s)
- I F Zhimulev
- Institute of Cytology and Genetics, Russian Academy of Sciences, Novosibirsk, 630090, Russia
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40
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Nezis IP, Stravopodis DJ, Papassideri IS, Stergiopoulos C, Margaritis LH. Morphological irregularities and features of resistance to apoptosis in thedcp-1/pita double mutated egg chambers duringDrosophila oogenesis. ACTA ACUST UNITED AC 2004; 60:14-23. [PMID: 15547953 DOI: 10.1002/cm.20043] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In the present study, we demonstrate the most novel characteristic morphological features of Drosophila egg chambers lacking both dcp-1 and pita functions in the germline cells. Dcp-1 is an effector caspase and it has been previously shown to play an important role during Drosophila oogenesis [McCall and Steller, 1998 : Science 279 : 230-234; Laundrie et al., 2003 : Genetics 165 : 1881-1888; Peterson et al., 2003 : Dev Biol 260 : 113-123]. The completion of sequencing and annotation of the Drosophila genome has revealed that the dcp-1 gene is nested within an intron of another distinct gene, called pita, a member of the C2H2 zinc finger protein family that regulates transcriptional initiation. The dcp-1(-/-)/pita(-/-) nurse cells exhibit euchromatic nuclei (delay of apoptosis) during the late stages of oogenesis, as revealed by conventional light and electron microscopy. The phalloidin-FITC staining discloses significant defects in actin cytoskeleton arrangement. The actin bundles fail to organize properly and the distribution of actin filaments in the ring canals is changed compared to the wild type. The oocyte and the chorion structures have been also modified. The oocyte nucleus is out of position and the chorion appears to contain irregular foldings, while the respiratory filaments obtain an altered morphology. The dcp-1(-/-)/pita(-/-) egg chambers do not exhibit the rare events of spontaneously induced apoptosis, observed for the wild type flies, during mid-oogenesis. Interestingly, the mutated egg chambers are protected by staurosporine-induced apoptosis in a percentage of 40%, strongly suggesting the essential role of dcp-1 and/or pita during mid-oogenesis.
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Affiliation(s)
- Ioannis P Nezis
- Faculty of Biology, Department of Cell Biology and Biophysics, University of Athens, Athens, Greece
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41
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Abstract
An intriguing aspect of cell cycle regulation is how cell growth and division are coordinated with developmental signals to produce properly patterned organisms of the appropriate size. Using the foundation laid by a detailed understanding of the regulators that intrinsically control progression through the cell cycle, links between developmental signals and the cell cycle are being elucidated. Considerable progress has been made using Drosophila melanogaster, both in identifying new cell cycle regulators that respond to developmental cues and in defining the impact of extrinsic signals on homologs of mammalian oncogenes and tumor suppressors. In this review, we discuss each cell cycle phase, highlighting differences between archetypal and variant cell cycles employed for specific developmental strategies. We emphasize the interplay between developmental signals and cell cycle transitions. Developmental control of checkpoints, cell cycle exit, and cell growth are also addressed.
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Affiliation(s)
- Laura A Lee
- Whitehead Institute and Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA.
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Laundrie B, Peterson JS, Baum JS, Chang JC, Fileppo D, Thompson SR, McCall K. Germline Cell Death Is Inhibited byP-Element Insertions Disrupting thedcp-1/pitaNested Gene Pair in Drosophila. Genetics 2003; 165:1881-8. [PMID: 14704173 PMCID: PMC1462893 DOI: 10.1093/genetics/165.4.1881] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AbstractGermline cell death in Drosophila oogenesis is controlled by distinct signals. The death of nurse cells in late oogenesis is developmentally regulated, whereas the death of egg chambers during mid-oogenesis is induced by environmental stress or developmental abnormalities. P-element insertions in the caspase gene dcp-1 disrupt both dcp-1 and the outlying gene, pita, leading to lethality and defective nurse cell death in late oogenesis. By isolating single mutations in the two genes, we have found that the loss of both genes contributes to this ovary phenotype. Mutants of pita, which encodes a C2H2 zinc-finger protein, are homozygous lethal and show dumpless egg chambers and premature nurse cell death in germline clones. Early nurse cell death is not observed in the dcp-1/pita double mutants, suggesting that dcp-1+ activity is required for the mid-oogenesis cell death seen in pita mutants. dcp-1 mutants are viable and nurse cell death in late oogenesis occurs normally. However, starvation-induced germline cell death during mid-oogenesis is blocked, leading to a reduction and inappropriate nuclear localization of the active caspase Drice. These findings suggest that the combinatorial loss of pita and dcp-1 leads to the increased survival of abnormal egg chambers in mutants bearing the P-element alleles and that dcp-1 is essential for cell death during mid-oogenesis.
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Affiliation(s)
- Bonni Laundrie
- Department of Biology, Boston University, Boston, Massachusetts 02215, USA
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