1
|
Macabenta F, Sun HT, Stathopoulos A. BMP-gated cell-cycle progression drives anoikis during mesenchymal collective migration. Dev Cell 2022; 57:1683-1693.e3. [PMID: 35709766 PMCID: PMC9339487 DOI: 10.1016/j.devcel.2022.05.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 05/02/2022] [Accepted: 05/20/2022] [Indexed: 11/03/2022]
Abstract
Tissue homeostasis involves the elimination of abnormal cells to avoid compromised patterning and function. Although quality control through cell competition is well studied in epithelial tissues, it is unknown if and how homeostasis is regulated in mesenchymal collectives. Here, we demonstrate that collectively migrating Drosophila muscle precursors utilize both fibroblast growth factor (FGF) and bone morphogenetic protein (BMP) signaling to promote homeostasis via anoikis, a form of cell death in response to substrate de-adhesion. Cell-cycle-regulated expression of the cell death gene head involution defective is responsible for caudal visceral mesoderm (CVM) anoikis. The secreted BMP ligand drives cell-cycle progression via a visceral mesoderm-specific cdc25/string enhancer to synchronize collective proliferation, as well as apoptosis of cells that have lost access to substrate-derived FGF. Perturbation of BMP-dependent cell-cycle progression is sufficient to confer anoikis resistance to mismigrating cells and thus facilitate invasion of other tissues. This BMP-gated cell-cycle checkpoint defines a quality control mechanism during mesenchymal collective migration.
Collapse
Affiliation(s)
- Frank Macabenta
- California Institute of Technology, Division of Biology and Biological Engineering, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Hsuan-Te Sun
- California Institute of Technology, Division of Biology and Biological Engineering, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Angelike Stathopoulos
- California Institute of Technology, Division of Biology and Biological Engineering, 1200 East California Boulevard, Pasadena, CA 91125, USA.
| |
Collapse
|
2
|
Coordination between cell proliferation and apoptosis after DNA damage in Drosophila. Cell Death Differ 2022; 29:832-845. [PMID: 34824391 PMCID: PMC8989919 DOI: 10.1038/s41418-021-00898-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 11/03/2021] [Accepted: 11/08/2021] [Indexed: 12/31/2022] Open
Abstract
Exposure to genotoxic stress promotes cell cycle arrest and DNA repair or apoptosis. These "life" or "death" cell fate decisions often rely on the activity of the tumor suppressor gene p53. Therefore, the precise regulation of p53 is essential to maintain tissue homeostasis and to prevent cancer development. However, how cell cycle progression has an impact on p53 cell fate decision-making is mostly unknown. In this work, we demonstrate that Drosophila p53 proapoptotic activity can be impacted by the G2/M kinase Cdk1. We find that cell cycle arrested or endocycle-induced cells are refractory to ionizing radiation-induced apoptosis. We show that p53 binding to the regulatory elements of the proapoptotic genes and its ability to activate their expression is compromised in experimentally arrested cells. Our results indicate that p53 genetically and physically interacts with Cdk1 and that p53 proapoptotic role is regulated by the cell cycle status of the cell. We propose a model in which cell cycle progression and p53 proapoptotic activity are molecularly connected to coordinate the appropriate response after DNA damage.
Collapse
|
3
|
Identification of the Wallenda JNKKK as an Alk suppressor reveals increased competitiveness of Alk-expressing cells. Sci Rep 2020; 10:14954. [PMID: 32917927 PMCID: PMC7486895 DOI: 10.1038/s41598-020-70890-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 08/05/2020] [Indexed: 12/27/2022] Open
Abstract
Anaplastic lymphoma kinase (Alk) is a receptor tyrosine kinase of the insulin receptor super-family that functions as oncogenic driver in a range of human cancers such as neuroblastoma. In order to investigate mechanisms underlying Alk oncogenic signaling, we conducted a genetic suppressor screen in Drosophila melanogaster. Our screen identified multiple loci important for Alk signaling, including members of Ras/Raf/ERK-, Pi3K-, and STAT-pathways as well as tailless (tll) and foxo whose orthologues NR2E1/TLX and FOXO3 are transcription factors implicated in human neuroblastoma. Many of the identified suppressors were also able to modulate signaling output from activated oncogenic variants of human ALK, suggesting that our screen identified targets likely relevant in a wide range of contexts. Interestingly, two misexpression alleles of wallenda (wnd, encoding a leucine zipper bearing kinase similar to human DLK and LZK) were among the strongest suppressors. We show that Alk expression leads to a growth advantage and induces cell death in surrounding cells. Our results suggest that Alk activity conveys a competitive advantage to cells, which can be reversed by over-expression of the JNK kinase kinase Wnd.
Collapse
|
4
|
Wrapping glia regulates neuronal signaling speed and precision in the peripheral nervous system of Drosophila. Nat Commun 2020; 11:4491. [PMID: 32901033 PMCID: PMC7479103 DOI: 10.1038/s41467-020-18291-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 08/11/2020] [Indexed: 02/06/2023] Open
Abstract
The functionality of the nervous system requires transmission of information along axons with high speed and precision. Conductance velocity depends on axonal diameter whereas signaling precision requires a block of electrical crosstalk between axons, known as ephaptic coupling. Here, we use the peripheral nervous system of Drosophila larvae to determine how glia regulates axonal properties. We show that wrapping glial differentiation depends on gap junctions and FGF-signaling. Abnormal glial differentiation affects axonal diameter and conductance velocity and causes mild behavioral phenotypes that can be rescued by a sphingosine-rich diet. Ablation of wrapping glia does not further impair axonal diameter and conductance velocity but causes a prominent locomotion phenotype that cannot be rescued by sphingosine. Moreover, optogenetically evoked locomotor patterns do not depend on conductance speed but require the presence of wrapping glial processes. In conclusion, our data indicate that wrapping glia modulates both speed and precision of neuronal signaling.
Collapse
|
5
|
Das P, Bhadra MP. Histone deacetylase (Rpd3) regulates Drosophila early brain development via regulation of Tailless. Open Biol 2020; 10:200029. [PMID: 32873153 PMCID: PMC7536075 DOI: 10.1098/rsob.200029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 07/29/2020] [Indexed: 11/29/2022] Open
Abstract
Tailless is a committed transcriptional repressor and principal regulator of the brain and eye development in Drosophila. Rpd3, the histone deacetylase, is an established repressor that interacts with co-repressors like Sin3a, Prospero, Brakeless and Atrophin. This study aims at deciphering the role of Rpd3 in embryonic segmentation and larval brain development in Drosophila. It delineates the mechanism of Tailless regulation by Rpd3, along with its interacting partners. There was a significant reduction in Tailless in Rpd3 heteroallelic mutant embryos, substantiating that Rpd3 is indispensable for the normal Tailless expression. The expression of the primary readout, Tailless was correlative to the expression of the neural cell adhesion molecule homologue, Fascilin2 (Fas2). Rpd3 also aids in the proper development of the mushroom body. Both Tailless and Fas2 expression are reported to be antagonistic to the epidermal growth factor receptor (EGFR) expression. The decrease in Tailless and Fas2 expression highlights that EGFR is upregulated in the larval mutants, hindering brain development. This study outlines the axis comprising Rpd3, dEGFR, Tailless and Fas2, which interact to fine-tune the early segmentation and larval brain development. Therefore, Rpd3 along with Tailless has immense significance in early embryogenesis and development of the larval brain.
Collapse
Affiliation(s)
- Paromita Das
- Applied Biology Division, CSIR-Indian Institute of Chemical Technology, Uppal Road, Hyderabad 500 007, India
- Academy of Scientific and Innovative Research (AcSIR) Training and Development Complex, CSIR Campus, CSIR Road, Taramani, Chennai 600 113, India
| | - Manika Pal Bhadra
- Applied Biology Division, CSIR-Indian Institute of Chemical Technology, Uppal Road, Hyderabad 500 007, India
- Academy of Scientific and Innovative Research (AcSIR) Training and Development Complex, CSIR Campus, CSIR Road, Taramani, Chennai 600 113, India
| |
Collapse
|
6
|
Webster SH, Vella MR, Scott MJ. Development and testing of a novel killer-rescue self-limiting gene drive system in Drosophila melanogaster. Proc Biol Sci 2020; 287:20192994. [PMID: 32292114 DOI: 10.1098/rspb.2019.2994] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Here we report the development and testing of a novel self-limiting gene drive system, Killer-Rescue (K-R), in Drosophila melanogaster. This system is composed of an autoregulated Gal4 Killer (K) and a Gal4-activated Gal80 Rescue (R). Overexpression of Gal4 is lethal, but in the presence of R activation of Gal80 leads to much lower levels of Gal4 and rescue of lethality. We demonstrate that with a single 2 : 1 engineered to wild-type release, K drives R through the population and after nine generations, more than 98% of the population carry R and less than 2% of the population are wild-type flies. We discuss how this simple K-R gene drive system may be readily adapted for population replacement in a human health pest, Aedes aegypti, or for population suppression in an agricultural pest, Drosophila suzukii.
Collapse
Affiliation(s)
- Sophia H Webster
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27615, USA
| | - Michael R Vella
- Biomathematics Graduate Program, North Carolina State University, Raleigh, NC 27615, USA
| | - Maxwell J Scott
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27615, USA
| |
Collapse
|
7
|
Decoupling of Apoptosis from Activation of the ER Stress Response by the Drosophila Metallopeptidase superdeath. Genetics 2020; 214:913-925. [PMID: 32047096 DOI: 10.1534/genetics.119.303004] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 02/09/2020] [Indexed: 12/19/2022] Open
Abstract
Endoplasmic reticulum (ER) stress-induced apoptosis is a primary cause and modifier of degeneration in a number of genetic disorders. Understanding how genetic variation influences the ER stress response and subsequent activation of apoptosis could improve individualized therapies and predictions of outcomes for patients. In this study, we find that the uncharacterized, membrane-bound metallopeptidase CG14516 in Drosophila melanogaster, which we rename as SUPpressor of ER stress-induced DEATH (su per death), plays a role in modifying ER stress-induced apoptosis. We demonstrate that loss of su per death reduces apoptosis and degeneration in the Rh1G69D model of ER stress through the JNK signaling cascade. This effect on apoptosis occurs without altering the activation of the unfolded protein response (IRE1 and PERK), suggesting that the beneficial prosurvival effects of this response are intact. Furthermore, we show that su per death functions epistatically upstream of CDK5-a known JNK-activated proapoptotic factor in this model of ER stress. We demonstrate that su per death is not only a modifier of this particular model, but affects the general tolerance to ER stress, including ER stress-induced apoptosis. Finally, we present evidence of Superdeath localization to the ER membrane. While similar in sequence to a number of human metallopeptidases found in the plasma membrane and ER membrane, its localization suggests that su per death is orthologous to ERAP1/2 in humans. Together, this study provides evidence that su per death is a link between stress in the ER and activation of cytosolic apoptotic pathways.
Collapse
|
8
|
Feng Y, Li Z, Lv L, Du A, Lin Z, Ye X, Lin Y, Lin X. Tankyrase regulates apoptosis by activating JNK signaling in Drosophila. Biochem Biophys Res Commun 2018; 503:2234-2239. [PMID: 29953853 DOI: 10.1016/j.bbrc.2018.06.143] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 06/25/2018] [Indexed: 11/24/2022]
Abstract
Programmed cell death (PCD), or apoptosis, plays essential roles in various cellular and developmental processes, and dysregulation of apoptosis causes many diseases. Thus, regulation of apoptotic process is very important. Drosophila tankyrase (DTNKS) is an evolutionarily conserved protein with poly(ADP-ribose) polymerase activity. In mammalian cells, tankyrases (TNKSs) have been reported to regulate cell death. To determine whether DTNKS plays function in inducing apoptosis in in vivo development, we used Drosophila as a model system and generated transgenic flies expressing DTNKS. We show that ectopic expression of DTNKS promotes caspase-dependent apoptosis and knockdown of DTNKS by RNAi dramatically alleviates apoptotic defect caused by ectopic expression of pro-apoptotic protein hid or rpr in the adult eye. Moreover, our result shows that ectopic expression of DTNKS triggers the activation of c-Jun N-terminal kinase (JNK) signaling, which is required for DTNKS-mediated apoptosis. Taken together, our finding identifies the role of DTNKS in regulating apoptosis by activating JNK signaling in Drosophila.
Collapse
Affiliation(s)
- Ying Feng
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China; State Key Laboratory of Ophthalmology, Optometry and Visual Science, Wenzhou, Zhejiang, China
| | - Zhenzhen Li
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China; State Key Laboratory of Ophthalmology, Optometry and Visual Science, Wenzhou, Zhejiang, China
| | - Lixiu Lv
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China; State Key Laboratory of Ophthalmology, Optometry and Visual Science, Wenzhou, Zhejiang, China
| | - Anle Du
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China; State Key Laboratory of Ophthalmology, Optometry and Visual Science, Wenzhou, Zhejiang, China
| | - Zhiqing Lin
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China; State Key Laboratory of Ophthalmology, Optometry and Visual Science, Wenzhou, Zhejiang, China
| | - Xiaolei Ye
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China; State Key Laboratory of Ophthalmology, Optometry and Visual Science, Wenzhou, Zhejiang, China
| | - Yi Lin
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China; State Key Laboratory of Ophthalmology, Optometry and Visual Science, Wenzhou, Zhejiang, China
| | - Xinhua Lin
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China; State Key Laboratory of Ophthalmology, Optometry and Visual Science, Wenzhou, Zhejiang, China; Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA.
| |
Collapse
|
9
|
Xu DC, Arthurton L, Baena-Lopez LA. Learning on the Fly: The Interplay between Caspases and Cancer. BIOMED RESEARCH INTERNATIONAL 2018; 2018:5473180. [PMID: 29854765 PMCID: PMC5949197 DOI: 10.1155/2018/5473180] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 03/14/2018] [Indexed: 02/07/2023]
Abstract
The ease of genetic manipulation, as well as the evolutionary conservation of gene function, has placed Drosophila melanogaster as one of the leading model organisms used to understand the implication of many proteins with disease development, including caspases and their relation to cancer. The family of proteases referred to as caspases have been studied over the years as the major regulators of apoptosis: the most common cellular mechanism involved in eliminating unwanted or defective cells, such as cancerous cells. Indeed, the evasion of the apoptotic programme resulting from caspase downregulation is considered one of the hallmarks of cancer. Recent investigations have also shown an instrumental role for caspases in non-lethal biological processes, such as cell proliferation, cell differentiation, intercellular communication, and cell migration. Importantly, malfunction of these essential biological tasks can deeply impact the initiation and progression of cancer. Here, we provide an extensive review of the literature surrounding caspase biology and its interplay with many aspects of cancer, emphasising some of the key findings obtained from Drosophila studies. We also briefly describe the therapeutic potential of caspase modulation in relation to cancer, highlighting shortcomings and hopeful promises.
Collapse
Affiliation(s)
- Derek Cui Xu
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX13RE, UK
- Cell Biology Section, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Lewis Arthurton
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX13RE, UK
| | | |
Collapse
|
10
|
Sharma N, Khurana N, Muthuraman A. Lower vertebrate and invertebrate models of Alzheimer's disease - A review. Eur J Pharmacol 2017; 815:312-323. [PMID: 28943103 DOI: 10.1016/j.ejphar.2017.09.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 08/20/2017] [Accepted: 09/13/2017] [Indexed: 02/07/2023]
Abstract
Alzheimer's disease is a common neurodegenerative disorder which is characterized by the presence of beta- amyloid protein and neurofibrillary tangles (NFTs) in the brain. Till now, various higher vertebrate models have been in use to study the pathophysiology of this disease. But, these models possess some limitations like ethical restrictions, high cost, difficult maintenance of large quantity and lesser reproducibility. Besides, various lower chordate animals like Danio rerio, Drosophila melanogaster, Caenorhabditis elegans and Ciona intestinalis have been proved to be an important model for the in vivo determination of targets of drugs with least limitations. In this article, we reviewed different studies conducted on theses models for the better understanding of the pathophysiology of AD and their subsequent application as a potential tool in the preclinical evaluation of new drugs.
Collapse
Affiliation(s)
- Neha Sharma
- Department of Pharmaceutical Sciences, Lovely Professional University, Phagwara, Punjab, India
| | - Navneet Khurana
- Department of Pharmaceutical Sciences, Lovely Professional University, Phagwara, Punjab, India
| | - Arunachalam Muthuraman
- Department of Pharmacology, Akal College of Pharmacy and Technical Education, Mastuana Sahib, Sangrur, Punjab, India; Department of Pharmacology, JSS College of Pharmacy, Jagadguru Sri Shivarathreeshwara University, Mysuru 570015, Karnataka, India.
| |
Collapse
|
11
|
Drosophila melanogaster “a potential model organism” for identification of pharmacological properties of plants/plant-derived components. Biomed Pharmacother 2017; 89:1331-1345. [DOI: 10.1016/j.biopha.2017.03.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 02/09/2017] [Accepted: 03/01/2017] [Indexed: 12/18/2022] Open
|
12
|
Cloning and functional characterizations of an apoptogenic Hid gene in the Scuttle Fly, Megaselia scalaris (Diptera; Phoridae). Gene 2016; 604:9-21. [PMID: 27940109 DOI: 10.1016/j.gene.2016.11.043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 11/24/2016] [Accepted: 11/30/2016] [Indexed: 12/19/2022]
Abstract
Although the mechanisms of apoptotic cell death have been well studied in the fruit fly, Drosophila melanogaster, it is unclear whether such mechanisms are conserved in other distantly related species. Using degenerate primers and PCR, we cloned a proapoptotic gene homologous to Head involution defective (Hid) from the Scuttle fly, Megaselia scalaris (MsHid). MsHid cDNA encodes a 197-amino acid-long polypeptide, which so far is the smallest HID protein. PCR analyses revealed that the MsHid gene consists of four exons and three introns. Ectopic expression of MsHid in various peptidergic neurons and non-neuronal tissues in Drosophila effectively induced apoptosis of these cells. However, deletion of either conserved domain, N-terminal IBM or C-terminal MTS, abolished the apoptogenic activity of MsHID, indicating that these two domains are indispensable. Expression of MsHid was found in all life stages, but more prominently in embryos and pupae. MsHid is actively expressed in the central nervous system (CNS), indicating its important role in CNS development. Together MsHID is likely to be an important cell death inducer during embryonic and post-embryonic development in this species. In addition, we found 2-fold induction of MsHid expression in UV-irradiated embryos, indicating a possible role for MsHid in UV-induced apoptosis.
Collapse
|
13
|
Drosophila Wnt and STAT Define Apoptosis-Resistant Epithelial Cells for Tissue Regeneration after Irradiation. PLoS Biol 2016; 14:e1002536. [PMID: 27584613 PMCID: PMC5008734 DOI: 10.1371/journal.pbio.1002536] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 07/27/2016] [Indexed: 01/05/2023] Open
Abstract
Drosophila melanogaster larvae irradiated with doses of ionizing radiation (IR) that kill about half of the cells in larval imaginal discs still develop into viable adults. How surviving cells compensate for IR-induced cell death to produce organs of normal size and appearance remains an active area of investigation. We have identified a subpopulation of cells within the continuous epithelium of Drosophila larval wing discs that shows intrinsic resistance to IR- and drug-induced apoptosis. These cells reside in domains of high Wingless (Wg, Drosophila Wnt-1) and STAT92E (sole Drosophila signal transducer and activator of transcription [STAT] homolog) activity and would normally form the hinge in the adult fly. Resistance to IR-induced apoptosis requires STAT and Wg and is mediated by transcriptional repression of the pro-apoptotic gene reaper. Lineage tracing experiments show that, following irradiation, apoptosis-resistant cells lose their identity and translocate to areas of the wing disc that suffered abundant cell death. Our findings provide a new paradigm for regeneration in which it is unnecessary to invoke special damage-resistant cell types such as stem cells. Instead, differences in gene expression within a population of genetically identical epithelial cells can create a subpopulation with greater resistance, which, following damage, survive, alter their fate, and help regenerate the tissue. After widespread radiation damage in the developing fruit fly, organs are formed by regeneration from an apoptosis-resistant subpopulation of cells marked by high levels of Wingless and STAT. Like other insects, Drosophila larvae have epithelial structures called imaginal discs that will give rise to most of the external adult structures, such as wings, limbs, or antennae; these organ precursors are formed by a single layer of epithelial cells that folds into a sac. Imaginal discs manage to regenerate efficiently if they are damaged. Previous studies have shown that dying cells produce signals that activate cell proliferation of some of their neighbors, allowing them to regenerate the disc and thereby enabling the flies to develop into normal adults. But a dedicated stem cell population that contributes to regeneration, if any, remained to be identified. Here, we report the identification of a subpopulation of cells in wing imaginal discs that is more resistant to the cytotoxic effects of radiation and drugs. We show that the protection of these cells depends on two signaling pathways—Wingless and STAT—that are conserved in humans. Following tissue damage by radiation, we observe that protected cells change their location and their identity, allowing them to fill in for dead cells in other parts of the same organ precursor. In sum, this work identified ways in which a subset of cells in Drosophila imaginal wing discs is preserved through radiation exposure so that they could participate in regeneration of the organ after radiation damage. We also discuss how this situation may resemble human cancers.
Collapse
|
14
|
Novel genes on rat chromosome 10 are linked to body fat mass, preadipocyte number and adipocyte size. Int J Obes (Lond) 2016; 40:1832-1840. [PMID: 27460604 DOI: 10.1038/ijo.2016.127] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 05/10/2016] [Accepted: 06/12/2016] [Indexed: 01/23/2023]
Abstract
BACKGROUND The genetic architecture of obesity is multifactorial. We have previously identified a quantitative trait locus (QTL) on rat chromosome 10 in a F2 cross of Wistar Ottawa Karlsburg (WOKW) and Dark Agouti (DA) rats responsible for obesity-related traits. The QTL was confirmed in congenic DA.WOKW10 rats. To pinpoint the region carrying causal genes, we established two new subcongenic lines, L1 and L2, with smaller refined segments of chromosome 10 to identify novel candidate genes. METHODS All lines were extensively characterized under different diet conditions. We employed transcriptome analysis in visceral adipose tissue (VAT) by RNA-Seq technology to identify potential underlying genes in the segregating regions. Three candidate genes were measured in human paired samples of VAT and subcutaneous (SC) AT (SAT) (N=304) individuals with a wide range of body weight and glucose homeostasis parameters. RESULTS DA.WOKW and L1 subcongenic lines were protected against body fat gain under high-fat diet (HFD), whereas L2 and DA had significantly more body fat after high-fat feeding. Interestingly, adipocyte size distribution in SAT and epigonadal AT of L1 subcongenic rats did not undergo typical ballooning under HFD and the number of preadipocytes in AT was significantly elevated in L2 compared with L1 and parental rats. Transcriptome analysis identified three candidate genes in VAT on rat chromosome 10. In humans, these candidate genes were differentially expressed between SAT and VAT. Moreover, HID1 mRNA significantly correlates with parameters of obesity and glucose metabolism. CONCLUSIONS Our data suggest novel candidate genes for obesity that map on rat chromosome 10 in an interval 102.2-104.7 Mb and are strongly associated with body fat mass regulation, preadipocyte number and adipocyte size in rats. Among those genes, AT head involution defective (HID1) mRNA expression may be relevant for human fat distribution and glucose homeostasis.
Collapse
|
15
|
Shklover J, Levy-Adam F, Kurant E. The role of Drosophila TNF Eiger in developmental and damage-induced neuronal apoptosis. FEBS Lett 2015; 589:871-9. [PMID: 25754009 DOI: 10.1016/j.febslet.2015.02.032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 02/17/2015] [Accepted: 02/27/2015] [Indexed: 10/23/2022]
Abstract
Eiger, the sole Drosophila TNF-alpha homolog, causes ectopic apoptosis through JNK pathway activation. Yet, its role in developmental apoptosis remains unclear. eiger mutant flies are viable and fertile but display compromised elimination of oncogenic cells and extracellular bacteria. Here we show that Eiger, specifically expressed in embryonic neurons and glia, is not involved in developmental neuronal apoptosis or in apoptotic cell clearance. Instead, we provide evidence that Eiger is required for damage-induced apoptosis in the embryonic CNS through regulation of the pro-apoptotic gene hid independently of the JNK pathway. Our study thus reveals a new requirement for Eiger in eliminating damaged cells during development.
Collapse
Affiliation(s)
- Jeny Shklover
- Department of Genetics and Developmental Biology, The Rappaport Family Institute for Research in the Medical Sciences, Faculty of Medicine, Technion - Israel Institute of Technology, Haifa 31096, Israel
| | - Flonia Levy-Adam
- Department of Genetics and Developmental Biology, The Rappaport Family Institute for Research in the Medical Sciences, Faculty of Medicine, Technion - Israel Institute of Technology, Haifa 31096, Israel
| | - Estee Kurant
- Department of Genetics and Developmental Biology, The Rappaport Family Institute for Research in the Medical Sciences, Faculty of Medicine, Technion - Israel Institute of Technology, Haifa 31096, Israel.
| |
Collapse
|
16
|
Edman RM, Linger RJ, Belikoff EJ, Li F, Sze SH, Tarone AM, Scott MJ. Functional characterization of calliphorid cell death genes and cellularization gene promoters for controlling gene expression and cell viability in early embryos. INSECT MOLECULAR BIOLOGY 2015; 24:58-70. [PMID: 25225046 DOI: 10.1111/imb.12135] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The New World screwworm fly, Cochliomyia hominivorax, and the Australian sheep blow fly, Lucilia cuprina, are major pests of livestock. The sterile insect technique was used to eradicate C. hominivorax from North and Central America. This involved area-wide releases of male and female flies that had been sterilized by radiation. Genetic systems have been developed for making 'male-only' strains that would improve the efficiency of genetic control of insect pests. One system involves induction of female lethality in embryos through activation of a pro-apoptotic gene by the tetracycline-dependent transactivator. Sex-specific expression is achieved using an intron from the transformer gene, which we previously isolated from several calliphorids. In the present study, we report the isolation of the promoters from the C. hominivorax slam and Lucilia sericata bnk cellularization genes and show that these promoters can drive expression of a GFP reporter gene in early embryos of transgenic L. cuprina. Additionally, we report the isolation of the L. sericata pro-apoptotic hid and rpr genes, identify conserved motifs in the encoded proteins and determine the relative expression of these genes at different stages of development. We show that widespread expression of the L. sericata pro-apoptotic genes was lethal in Drosophila melanogaster. The isolated gene promoters and pro-apoptotic genes could potentially be used to build transgenic embryonic sexing strains of calliphorid livestock pests.
Collapse
Affiliation(s)
- R M Edman
- Department of Genetics, North Carolina State University, Raleigh, NC, USA
| | | | | | | | | | | | | |
Collapse
|
17
|
Drosophila Small Heat Shock Proteins: An Update on Their Features and Functions. HEAT SHOCK PROTEINS 2015. [DOI: 10.1007/978-3-319-16077-1_25] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
|
18
|
Sagri E, Reczko M, Tsoumani KT, Gregoriou ME, Harokopos V, Mavridou AM, Tastsoglou S, Athanasiadis K, Ragoussis J, Mathiopoulos KD. The molecular biology of the olive fly comes of age. BMC Genet 2014; 15 Suppl 2:S8. [PMID: 25472866 PMCID: PMC4255830 DOI: 10.1186/1471-2156-15-s2-s8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Background Olive cultivation blends with the history of the Mediterranean countries since ancient times. Even today, activities around the olive tree constitute major engagements of several people in the countryside of both sides of the Mediterranean basin. The olive fly is, beyond doubt, the most destructive pest of cultivated olives. The female fly leaves its eggs in the olive fruit. Upon emergence, the larvae feed on the olive sap, thus destroying the fruit. If untreated, practically all olives get infected. The use of chemical insecticides constitutes the principal olive fly control approach. The Sterile Insect Technique (SIT), an environmentally friendly alternative control method, had been tried in pilot field applications in the 1970's, albeit with no practical success. This was mainly attributed to the low, non-antagonistic quality of the mixed-sex released insects. Many years of experience from successful SIT applications in related species, primarily the Mediterranean fruit fly, Ceratitis capitata, demonstrated that efficient SIT protocols require the availability of fundamental genetic and molecular information. Results Among the primary systems whose understanding can contribute towards novel SIT approaches (or its recently developed alternative RIDL: Release of Insects carrying a Dominant Lethal) is the reproductive, since the ability to manipulate the reproductive system would directly affect the insect's fertility. In addition, the analysis of early embryonic promoters and apoptotic genes would provide tools that confer dominant early-embryonic lethality during mass-rearing. Here we report the identification of several genes involved in these systems through whole transcriptome analysis of female accessory glands (FAGs) and spermathecae, as well as male testes. Indeed, analysis of differentially expressed genes in these tissues revealed higher metabolic activity in testes than in FAGs/spermathecae. Furthermore, at least five olfactory-related genes were shown to be differentially expressed in the female and male reproductive systems analyzed. Finally, the expression profile of the embryonic serendipity-α locus and the pre-apoptotic head involution defective gene were analyzed during embryonic developmental stages. Conclusions Several years of molecular studies on the olive fly can now be combined with new information from whole transcriptome analyses and lead to a deep understanding of the biology of this notorious insect pest. This is a prerequisite for the development of novel embryonic lethality female sexing strains for successful SIT efforts which, combined with improved mass-reared conditions, give new hope for efficient SIT applications for the olive fly.
Collapse
|
19
|
A mutation in Drosophila methuselah resists paraquat induced Parkinson-like phenotypes. Neurobiol Aging 2014; 35:2419.e1-2419.e16. [DOI: 10.1016/j.neurobiolaging.2014.04.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 03/14/2014] [Accepted: 04/13/2014] [Indexed: 11/23/2022]
|
20
|
Zhang T, Liao Y, Hsu FN, Zhang R, Searle JS, Pei X, Li X, Ryoo HD, Ji JY, Du W. Hyperactivated Wnt signaling induces synthetic lethal interaction with Rb inactivation by elevating TORC1 activities. PLoS Genet 2014; 10:e1004357. [PMID: 24809668 PMCID: PMC4014429 DOI: 10.1371/journal.pgen.1004357] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 03/24/2014] [Indexed: 12/31/2022] Open
Abstract
Inactivation of the Rb tumor suppressor can lead to increased cell proliferation or cell death depending on specific cellular context. Therefore, identification of the interacting pathways that modulate the effect of Rb loss will provide novel insights into the roles of Rb in cancer development and promote new therapeutic strategies. Here, we identify a novel synthetic lethal interaction between Rb inactivation and deregulated Wg/Wnt signaling through unbiased genetic screens. We show that a weak allele of axin, which deregulates Wg signaling and increases cell proliferation without obvious effects on cell fate specification, significantly alters metabolic gene expression, causes hypersensitivity to metabolic stress induced by fasting, and induces synergistic apoptosis with mutation of fly Rb ortholog, rbf. Furthermore, hyperactivation of Wg signaling by other components of the Wg pathway also induces synergistic apoptosis with rbf. We show that hyperactivated Wg signaling significantly increases TORC1 activity and induces excessive energy stress with rbf mutation. Inhibition of TORC1 activity significantly suppressed synergistic cell death induced by hyperactivated Wg signaling and rbf inactivation, which is correlated with decreased energy stress and decreased induction of apoptotic regulator expression. Finally the synthetic lethality between Rb and deregulated Wnt signaling is conserved in mammalian cells and that inactivation of Rb and APC induces synergistic cell death through a similar mechanism. These results suggest that elevated TORC1 activity and metabolic stress underpin the evolutionarily conserved synthetic lethal interaction between hyperactivated Wnt signaling and inactivated Rb tumor suppressor. Inactivation of Rb tumor suppressor is common in cancers. Therefore, identification of genes and pathways that are synthetic lethal with Rb will provide new insights into the role of Rb in cancer development and promote the development of novel therapeutic approaches. Here we identified a novel synthetic lethal interaction between Rb inactivation and hyperactivated Wnt signaling and showed that this synthetic lethal interaction is conserved in mammalian systems. We demonstrate that hyperactivated Wnt signaling activate TORC1 activity and induce excessive energy stress with inactivated Rb tumor suppressor, which underpins the evolutionarily conserved synthetic lethal interaction. This study provides novel insights into the interactions between the Rb, Wnt, and mTOR pathways in regulating cellular energy balance, cell growth, and survival.
Collapse
Affiliation(s)
- Tianyi Zhang
- Ben May Department for Cancer Research, The University of Chicago, Chicago, Illinois, United States of America
| | - Yang Liao
- Ben May Department for Cancer Research, The University of Chicago, Chicago, Illinois, United States of America
| | - Fu-Ning Hsu
- Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M Health Science Center, College Station, Texas, United States of America
| | - Robin Zhang
- Ben May Department for Cancer Research, The University of Chicago, Chicago, Illinois, United States of America
| | - Jennifer S Searle
- Ben May Department for Cancer Research, The University of Chicago, Chicago, Illinois, United States of America
| | - Xun Pei
- Ben May Department for Cancer Research, The University of Chicago, Chicago, Illinois, United States of America
| | - Xuan Li
- Ben May Department for Cancer Research, The University of Chicago, Chicago, Illinois, United States of America
| | - Hyung Don Ryoo
- Department of Cell Biology, New York University School of Medicine, New York, New York, United States of America
| | - Jun-Yuan Ji
- Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M Health Science Center, College Station, Texas, United States of America
| | - Wei Du
- Ben May Department for Cancer Research, The University of Chicago, Chicago, Illinois, United States of America
| |
Collapse
|
21
|
James A, Cindass R, Mayer D, Terhoeve S, Mumphrey C, DiMario P. Nucleolar stress in Drosophila melanogaster: RNAi-mediated depletion of Nopp140. Nucleus 2013; 4:123-33. [PMID: 23412656 DOI: 10.4161/nucl.23944] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Nucleolar stress results when ribosome biogenesis is disrupted. An excellent example is the human Treacher Collins syndrome in which the loss of the nucleolar chaperone, Treacle, leads to p53-dependent apoptosis in embryonic neural crest cells and ultimately to craniofacial birth defects. Here, we show that depletion of the related nucleolar phosphoprotein, Nopp140, in Drosophila melanogaster led to nucleolar stress and eventual lethality when multiple tissues were depleted of Nopp140. We used TEM, immuno-blot analysis and metabolic protein labeling to show the loss of ribosomes. Targeted loss of Nopp140 in larval wing discs caused Caspase-dependent apoptosis which eventually led to defects in the adult wings. These defects were not rescued by a p53 gene deletion, as the craniofacial defects were in the murine model of TCS, thus suggesting that apoptosis caused by nucleolar stress in Drosophila is induced by a p53-independent mechanism. Loss of Nopp140 in larval polyploid midgut cells induced premature autophagy as marked by the accumulation of mCherry-ATG8a into autophagic vesicles. We also found elevated phenoloxidase A3 levels in whole larval lysates and within the hemolymph of Nopp140-depleted larvae vs. hemolymph from parental genotype larvae. Phenoloxidase A3 enrichment was coincident with the appearance of melanotic tumors in the Nopp140-depleted larvae. The occurrence of apoptosis, autophagy and phenoloxidase A3 release to the hemolymph upon nucleolar stress correlated well with the demonstrated activation of Jun N-terminal kinase (JNK) in Nopp140-depleted larvae. We propose that JNK is a central stress response effector that is activated by nucleolar stress in Drosophila larvae.
Collapse
Affiliation(s)
- Allison James
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA
| | | | | | | | | | | |
Collapse
|
22
|
Large neurological component to genetic differences underlying biased sperm use in Drosophila. Genetics 2012; 193:177-85. [PMID: 23105014 DOI: 10.1534/genetics.112.146357] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Sperm competition arises as a result of complex interactions among male and female factors. While the roles of some male factors are known, little is known of the molecules or mechanisms that underlie the female contribution to sperm competition. The genetic tools available for Drosophila allow us to identify, in an unbiased manner, candidate female genes that are critical for mediating sperm competition outcomes. We first screened for differences in female sperm storage and use patterns by characterizing the natural variation in sperm competition in a set of 39 lines from the sequenced Drosophila Genetic Reference Panel (DGRP) of wild-derived inbred lines. We found extensive female variation in sperm competition outcomes. To generate a list of candidate female genes for functional studies, we performed a genome-wide association mapping, utilizing the common single-nucleotide polymorphisms (SNPs) segregating in the DGRP lines. Surprisingly, SNPs within ion channel genes and other genes with roles in the nervous system were among the top associated SNPs. Knockdown studies of three candidate genes (para, Rab2, and Rim) in sensory neurons innervating the female reproductive tract indicate that some of these candidate female genes may affect sperm competition by modulating the neural input of these sensory neurons to the female reproductive tract. More extensive functional studies are needed to elucidate the exact role of all these candidate female genes in sperm competition. Nevertheless, the female nervous system appears to have a previously unappreciated role in sperm competition. Our results indicate that the study of female control of sperm competition should not be limited to female reproductive tract-specific genes, but should focus also on diverse biological pathways.
Collapse
|
23
|
Davidson JM, Duronio RJ. S phase-coupled E2f1 destruction ensures homeostasis in proliferating tissues. PLoS Genet 2012; 8:e1002831. [PMID: 22916021 PMCID: PMC3420931 DOI: 10.1371/journal.pgen.1002831] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 05/29/2012] [Indexed: 12/23/2022] Open
Abstract
Precise control of cell cycle regulators is critical for normal development and tissue homeostasis. E2F transcription factors are activated during G1 to drive the G1-S transition and are then inhibited during S phase by a variety of mechanisms. Here, we genetically manipulate the single Drosophila activator E2F (E2f1) to explore the developmental requirement for S phase–coupled E2F down-regulation. Expression of an E2f1 mutant that is not destroyed during S phase drives cell cycle progression and causes apoptosis. Interestingly, this apoptosis is not exclusively the result of inappropriate cell cycle progression, because a stable E2f1 mutant that cannot function as a transcription factor or drive cell cycle progression also triggers apoptosis. This observation suggests that the inappropriate presence of E2f1 protein during S phase can trigger apoptosis by mechanisms that are independent of E2F acting directly at target genes. The ability of S phase-stabilized E2f1 to trigger apoptosis requires an interaction between E2f1 and the Drosophila pRb homolog, Rbf1, and involves induction of the pro-apoptotic gene, hid. Simultaneously blocking E2f1 destruction during S phase and inhibiting the induction of apoptosis results in tissue overgrowth and lethality. We propose that inappropriate accumulation of E2f1 protein during S phase triggers the elimination of potentially hyperplastic cells via apoptosis in order to ensure normal development of rapidly proliferating tissues. Rapidly growing tissues provide an excellent opportunity to study the careful balance between cell proliferation and apoptosis needed for normal organ structure and function in developing organisms. We present evidence that a transcription factor critical for regulating progression of the Drosophila melanogaster cell cycle, E2f1, serves also as an indicator of normal tissue development. E2f1 activation during G1 phase of the cell cycle triggers entry into S phase. E2f1 activity is then rapidly inhibited during S phase by a mechanism that couples E2f1 proteolysis directly to DNA synthesis. Expression during larval development of an S phase-stabilized form of E2f1 results in apoptosis in rapidly proliferating adult wing precursor cells, even when this stabilized E2f1 protein is mutated such that it cannot induce transcription or cell cycle progression. Preventing the ability of S phase-stabilized E2f1 to induce apoptosis results in massive tissue overgrowth. We propose that aberrant E2f1 accumulation during S phase triggers apoptosis in order to remove potentially hyper-proliferative cells and to maintain homeostasis during tissue growth.
Collapse
Affiliation(s)
- Jean M. Davidson
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Robert J. Duronio
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Program in Molecular Biology and Biotechnology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail:
| |
Collapse
|
24
|
Gafuik C, Steller H. A gain-of-function germline mutation in Drosophila ras1 affects apoptosis and cell fate during development. PLoS One 2011; 6:e23535. [PMID: 21858158 PMCID: PMC3155559 DOI: 10.1371/journal.pone.0023535] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 07/19/2011] [Indexed: 12/30/2022] Open
Abstract
The RAS/MAPK signal transduction pathway is an intracellular signaling cascade that transmits environmental signals from activated receptor tyrosine kinases (RTKs) on the cell surface and other endomembranes to transcription factors in the nucleus, thereby linking extracellular stimuli to changes in gene expression. Largely as a consequence of its role in oncogenesis, RAS signaling has been the subject of intense research efforts for many years. More recently, it has been shown that milder perturbations in Ras signaling during embryogenesis also contribute to the etiology of a group of human diseases. Here we report the identification and characterization of the first gain-of-function germline mutation in Drosophila ras1 (ras85D), the Drosophila homolog of human K-ras, N-ras and H-ras. A single amino acid substitution (R68Q) in the highly conserved switch II region of Ras causes a defective protein with reduced intrinsic GTPase activity, but with normal sensitivity to GAP stimulation. The ras1R68Q mutant is homozygous viable but causes various developmental defects associated with elevated Ras signaling, including cell fate changes and ectopic survival of cells in the nervous system. These biochemical and functional properties are reminiscent of germline Ras mutants found in patients afflicted with Noonan, Costello or cardio-facio-cutaneous syndromes. Finally, we used ras1R68Q to identify novel genes that interact with Ras and suppress cell death.
Collapse
Affiliation(s)
- Christopher Gafuik
- Howard Hughes Medical Institute, The Rockefeller University, New York, New York, United States of America
| | - Hermann Steller
- Howard Hughes Medical Institute, The Rockefeller University, New York, New York, United States of America
- * E-mail:
| |
Collapse
|
25
|
Physiological apoptosis of polar cells during Drosophila oogenesis is mediated by Hid-dependent regulation of Diap1. Cell Death Differ 2010; 18:793-805. [PMID: 21113144 DOI: 10.1038/cdd.2010.141] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Although much has been learned in recent years about the apoptotic machinery, the mechanisms underlying survival and death choices during development of metazoans remain less clearly understood. During early oogenesis in Drosophila, a small excess in the number of specialized somatic cells, called polar cells (PCs), produced at follicle extremities is reduced to exactly two cells through apoptosis by mid-oogenesis. We have found that PCs destined to die first lose their apical contacts and then round up and shrink progressively until they disappear. Caspases are activated only once the cells have begun to shrink, suggesting that they are implicated in this part of the process, but not in the initial loss of cell polarity. Loss-of-function analyses based on mutant, clonal and RNAi approaches show that among the RHG family of pro-apoptotic factors, Hid is specifically necessary for PC apoptosis, as well as the initiator caspase Dronc and its adaptor Dark/Apaf-1, and likely several effector caspases, in particular Drice. In addition, we show that Hid protein and transcripts accumulate specifically in PCs destined to die, while the anti-apoptotic factor Diap1 is downregulated in these cells in a hid-dependent manner. Therefore, our results implicate the Hid-Diap1 module as an important regulatory point in a developmental case of apoptosis.
Collapse
|
26
|
Abstract
Mitogen-activated protein kinase kinase kinase kinase-3 (MAP4K3) is a Ste20 kinase family member that modulates multiple signal transduction pathways. We recently identified MAP4K3 as proapoptotic kinase using an RNA interference screening approach. In mammalian cells, MAP4K3 enhances the mitochondrial apoptosis pathway through the post-transcriptional modulation of selected proapoptotic Bcl-2 homology domain 3-only proteins. Recent data suggest that MAP4K3 mutations contribute to pancreatic cancer, which highlights the importance of studying the in vivo function of this kinase. To determine whether the cell death function is conserved in vivo and which downstream signalling pathways are involved, we generated transgenic flies expressing happyhour (hppy), the Drosophila MAP4K3 orthologue. Here, we show that the overexpression of hppy promotes caspase-dependent apoptosis and that the hypothetical kinase domain is essential for inducing cell death. In addition, we show that hppy expression triggers the activation of both the c-Jun N-terminal kinase (JNK) and target of rapamycin (TOR) signalling pathways; however, only JNK signalling is required for apoptosis. Together, our results show that hppy has a JNK-dependent proapoptotic function in Drosophila, which reinforces the hypothesis that MAP4K3 might act as tumour suppressor by regulating apoptosis in higher eukaryotes.
Collapse
|
27
|
|
28
|
Mollereau B. Cell death: what can we learn from flies? Editorial for the special review issue on Drosophila apoptosis. Apoptosis 2009; 14:929-34. [PMID: 19629695 DOI: 10.1007/s10495-009-0383-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
|