1
|
Long S, Cao W, Qiu Y, Deng R, Liu J, Zhang L, Dong R, Liu F, Li S, Zhao H, Li N, Li K. The appearance of cytoplasmic cytochrome C precedes apoptosis during Drosophila salivary gland degradation. INSECT SCIENCE 2024; 31:157-172. [PMID: 37370257 DOI: 10.1111/1744-7917.13240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 05/16/2023] [Accepted: 05/22/2023] [Indexed: 06/29/2023]
Abstract
Apoptosis is an important process for organism development that functions to eliminate cell damage, maintain homeostasis, and remove obsolete tissues during morphogenesis. In mammals, apoptosis is accompanied by the release of cytochrome C (Cyt-c) from mitochondria to the cytoplasm. However, whether this process is conserved in the fruit fly, Drosophila melanogaster, remains controversial. In this study, we discovered that during the degradation of Drosophila salivary gland, the transcription of mitochondria apoptosis factors (MAPFs), Cyt-c, and death-associated APAF1-related killer (Dark) encoding genes are all upregulated antecedent to initiator and effector caspases encoding genes. The proteins Cyt-c and the active caspase 3 appear gradually in the cytoplasm during salivary gland degradation. Meanwhile, the Cyt-c protein colocates with mito-GFP, the marker indicating cytoplasmic mitochondria, and the change in mitochondrial membrane potential coincides with the appearance of Cyt-c in the cytoplasm. Moreover, impeding or promoting 20E-induced transcription factor E93 suppresses or enhances the staining of Cyt-c and the active caspase 3 in the cytoplasm of salivary gland, and accordingly decreases or increases the mitochondrial membrane potential, respectively. Our research provides evidence that cytoplasmic Cyt-c appears before apoptosis during Drosophila salivary gland degradation, shedding light on partial conserved mechanism in apoptosis between insects and mammals.
Collapse
Affiliation(s)
- Shihui Long
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Wenxin Cao
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Yongyu Qiu
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Ruohan Deng
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Jiali Liu
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Lidan Zhang
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Renke Dong
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Fengxin Liu
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Sheng Li
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, China
- Guangmeiyuan R&D Center, Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, South China Normal University, Meizhou, Guangdong Province, China
| | - Haigang Zhao
- School of Food Science and Engineering, South China University of Technology, Guangzhou, China
- ChemPartner PharmaTech Co., Ltd, Jiangmen, Guangdong Province, China
| | - Na Li
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, China
- Guangmeiyuan R&D Center, Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, South China Normal University, Meizhou, Guangdong Province, China
| | - Kang Li
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, China
- Guangmeiyuan R&D Center, Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, South China Normal University, Meizhou, Guangdong Province, China
| |
Collapse
|
2
|
Yamada T, Yoshinari Y, Tobo M, Habara O, Nishimura T. Nacα protects the larval fat body from cell death by maintaining cellular proteostasis in Drosophila. Nat Commun 2023; 14:5328. [PMID: 37658058 PMCID: PMC10474126 DOI: 10.1038/s41467-023-41103-1] [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: 03/06/2023] [Accepted: 08/17/2023] [Indexed: 09/03/2023] Open
Abstract
Protein homeostasis (proteostasis) is crucial for the maintenance of cellular homeostasis. Impairment of proteostasis activates proteotoxic and unfolded protein response pathways to resolve cellular stress or induce apoptosis in damaged cells. However, the responses of individual tissues to proteotoxic stress and evoking cell death program have not been extensively explored in vivo. Here, we show that a reduction in Nascent polypeptide-associated complex protein alpha subunit (Nacα) specifically and progressively induces cell death in Drosophila fat body cells. Nacα mutants disrupt both ER integrity and the proteasomal degradation system, resulting in caspase activation through JNK and p53. Although forced activation of the JNK and p53 pathways was insufficient to induce cell death in the fat body, the reduction of Nacα sensitized fat body cells to intrinsic and environmental stresses. Reducing overall protein synthesis by mTor inhibition or Minute mutants alleviated the cell death phenotype in Nacα mutant fat body cells. Our work revealed that Nacα is crucial for protecting the fat body from cell death by maintaining cellular proteostasis, thus demonstrating the coexistence of a unique vulnerability and cell death resistance in the fat body.
Collapse
Affiliation(s)
- Takayuki Yamada
- Laboratory for Growth Control Signaling, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Hyogo, 650-0047, Japan
| | - Yuto Yoshinari
- Laboratory of Metabolic Regulation and Genetics, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, 371-8512, Japan
| | - Masayuki Tobo
- Laboratory of Metabolic Regulation and Genetics, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, 371-8512, Japan
| | - Okiko Habara
- Laboratory for Growth Control Signaling, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Hyogo, 650-0047, Japan
| | - Takashi Nishimura
- Laboratory for Growth Control Signaling, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Hyogo, 650-0047, Japan.
- Laboratory of Metabolic Regulation and Genetics, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, 371-8512, Japan.
| |
Collapse
|
3
|
Zhang J, Zhang W, Wei L, Zhang L, Liu J, Huang S, Li S, Yang W, Li K. E93 promotes transcription of RHG genes to initiate apoptosis during Drosophila salivary gland metamorphosis. INSECT SCIENCE 2023; 30:588-598. [PMID: 36281570 DOI: 10.1111/1744-7917.13135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 10/03/2022] [Accepted: 10/14/2022] [Indexed: 06/15/2023]
Abstract
20-hydroxyecdysone (20E) induced transcription factor E93 is important for larval-adult transition, which functions in programmed cell death of larval obsolete tissues, and the formation of adult new tissues. However, the apoptosis-related genes directly regulated by E93 are still ambiguous. In this study, an E93 mutation fly strain was obtained by clustered regularly interspaced palindromic repeats (CRISPR) / CRISPR-associated protein 9-mediated long exon deletion to investigate whether and how E93 induces apoptosis during larval tissues metamorphosis. The transcriptional profile of E93 was consistent with 3 RHG (rpr, hid, and grim) genes and the effector caspase gene drice, and all their expressions peaked at the initiation of apoptosis during the degradation of salivary glands. The transcription expression of 3 RHG genes decreased and apoptosis was blocked in E93 mutation salivary gland during metamorphosis. In contrast, E93 overexpression promoted the transcription of 3 RHG genes, and induced advanced apoptosis in the salivary gland. Moreover, E93 not only enhance the promoter activities of the 3 RHG genes in Drosophila Kc cells in vitro, but also in the salivary gland in vivo. Our results demonstrated that 20E induced E93 promotes the transcription of RHG genes to trigger apoptosis during obsolete tissues degradation at metamorphosis in Drosophila.
Collapse
Affiliation(s)
- Jiahui Zhang
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China
- Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, 510642, China
| | - Wenhao Zhang
- College of Biological and Food Engineering, Huaihua University, Huaihua, 418000, China
| | - Lin Wei
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Lidan Zhang
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Jiali Liu
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Shumin Huang
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Sheng Li
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China
- Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, 510642, China
- Guangmeiyuan R&D Center, Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, South China Normal University, Meizhou, 514779, China
| | - Weike Yang
- The Sericultural and Apicultural Research Institute, Yunnan Academy of Agricultural Sciences, Mengzi, Yunnan, 661100, China
| | - Kang Li
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China
- Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, 510642, China
- Guangmeiyuan R&D Center, Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, South China Normal University, Meizhou, 514779, China
| |
Collapse
|
4
|
Thioredoxin-80 protects against amyloid-beta pathology through autophagic-lysosomal pathway regulation. Mol Psychiatry 2021; 26:1410-1423. [PMID: 31520067 DOI: 10.1038/s41380-019-0521-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 07/02/2019] [Accepted: 08/02/2019] [Indexed: 12/15/2022]
Abstract
Aggregation and accumulation of amyloid beta (Aβ) are believed to play a key role in the pathogenesis of Alzheimer's disease (AD). We previously reported that Thioredoxin-80 (Trx80), a truncated form of Thioredoxin-1, prevents the toxic effects of Aβ and inhibits its aggregation in vitro. Trx80 levels were found to be dramatically reduced both in the human brain and cerebrospinal fluid of AD patients. In this study, we investigated the effect of Trx80 expression using in vivo and in vitro models of Aβ pathology. We developed Drosophila melanogaster models overexpressing either human Trx80, human Aβ42, or both Aβ42/Trx80 in the central nervous system. We found that Trx80 expression prevents Aβ42 accumulation in the brain and rescues the reduction in life span and locomotor impairments seen in Aβ42 expressing flies. Also, we show that Trx80 induces autophagosome formation and reverses the inhibition of Atg4b-Atg8a/b autophagosome formation pathway caused by Aβ42. These effects were also confirmed in human neuroblastoma cells. These results give insight into Trx80 function in vivo, suggesting its role in the autophagosome biogenesis and thus in Aβ42 degradation. Our findings put Trx80 on the spotlight as an endogenous agent against Aβ42-induced toxicity in the brain suggesting that strategies to enhance Trx80 levels in neurons could potentially be beneficial against AD pathology in humans.
Collapse
|
5
|
Xu T, Nicolson S, Sandow JJ, Dayan S, Jiang X, Manning JA, Webb AI, Kumar S, Denton D. Cp1/cathepsin L is required for autolysosomal clearance in Drosophila. Autophagy 2020; 17:2734-2749. [PMID: 33112206 DOI: 10.1080/15548627.2020.1838105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Macroautophagy/autophagy is a highly conserved lysosomal degradative pathway important for maintaining cellular homeostasis. Much of our current knowledge of autophagy is focused on the initiation steps in this process. Recently, an understanding of later steps, particularly lysosomal fusion leading to autolysosome formation and the subsequent role of lysosomal enzymes in degradation and recycling, is becoming evident. Autophagy can function in both cell survival and cell death, however, the mechanisms that distinguish adaptive/survival autophagy from autophagy-dependent cell death remain to be established. Here, using proteomic analysis of Drosophila larval midguts during degradation, we identify a group of proteins with peptidase activity, suggesting a role in autophagy-dependent cell death. We show that Cp1/cathepsin L-deficient larval midgut cells accumulate aberrant autophagic vesicles due to a block in autophagic flux, yet later stages of midgut degradation are not compromised. The accumulation of large aberrant autolysosomes in the absence of Cp1 appears to be the consequence of decreased degradative capacity as they contain undigested cytoplasmic material, rather than a defect in autophagosome-lysosome fusion. Finally, we find that other cathepsins may also contribute to proper autolysosomal degradation in Drosophila larval midgut cells. Our findings provide evidence that cathepsins play an essential role in the autolysosome to maintain basal autophagy flux by balancing autophagosome production and turnover.
Collapse
Affiliation(s)
- Tianqi Xu
- Centre for Cancer Biology, University of South Australia and SA Pathology, Adelaide, Australia
| | - Shannon Nicolson
- Centre for Cancer Biology, University of South Australia and SA Pathology, Adelaide, Australia
| | - Jarrod J Sandow
- Advanced Technology and Biology, The Walter & Eliza Hall Institute of Medical Research, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Australia
| | - Sonia Dayan
- Centre for Cancer Biology, University of South Australia and SA Pathology, Adelaide, Australia
| | - Xin Jiang
- Centre for Cancer Biology, University of South Australia and SA Pathology, Adelaide, Australia
| | - Jantina A Manning
- Centre for Cancer Biology, University of South Australia and SA Pathology, Adelaide, Australia
| | - Andrew I Webb
- Advanced Technology and Biology, The Walter & Eliza Hall Institute of Medical Research, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Australia
| | - Sharad Kumar
- Centre for Cancer Biology, University of South Australia and SA Pathology, Adelaide, Australia
| | - Donna Denton
- Centre for Cancer Biology, University of South Australia and SA Pathology, Adelaide, Australia
| |
Collapse
|
6
|
Yalonetskaya A, Mondragon AA, Elguero J, McCall K. I Spy in the Developing Fly a Multitude of Ways to Die. J Dev Biol 2018; 6:E26. [PMID: 30360387 PMCID: PMC6316796 DOI: 10.3390/jdb6040026] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 10/18/2018] [Accepted: 10/19/2018] [Indexed: 12/11/2022] Open
Abstract
Cell proliferation and cell death are two opposing, yet complementary fundamental processes in development. Cell proliferation provides new cells, while developmental programmed cell death adjusts cell numbers and refines structures as an organism grows. Apoptosis is the best-characterized form of programmed cell death; however, there are many other non-apoptotic forms of cell death that occur throughout development. Drosophila is an excellent model for studying these varied forms of cell death given the array of cellular, molecular, and genetic techniques available. In this review, we discuss select examples of apoptotic and non-apoptotic cell death that occur in different tissues and at different stages of Drosophila development. For example, apoptosis occurs throughout the nervous system to achieve an appropriate number of neurons. Elsewhere in the fly, non-apoptotic modes of developmental cell death are employed, such as in the elimination of larval salivary glands and midgut during metamorphosis. These and other examples discussed here demonstrate the versatility of Drosophila as a model organism for elucidating the diverse modes of programmed cell death.
Collapse
Affiliation(s)
- Alla Yalonetskaya
- Cell and Molecular Biology Program, Department of Biology, 5 Cummington Mall, Boston University, Boston, MA 02215, USA.
| | - Albert A Mondragon
- Molecular Biology, Cell Biology, and Biochemistry Program, 5 Cummington Mall, Boston University, Boston, MA 02215, USA.
| | - Johnny Elguero
- Cell and Molecular Biology Program, Department of Biology, 5 Cummington Mall, Boston University, Boston, MA 02215, USA.
| | - Kimberly McCall
- Cell and Molecular Biology Program, Department of Biology, 5 Cummington Mall, Boston University, Boston, MA 02215, USA.
- Molecular Biology, Cell Biology, and Biochemistry Program, 5 Cummington Mall, Boston University, Boston, MA 02215, USA.
| |
Collapse
|
7
|
Abstract
Autophagy influences cell survival through maintenance of cell bioenergetics and clearance of protein aggregates and damaged organelles. Several lines of evidence indicate that autophagy is a multifaceted regulator of cell death, but controversy exists over whether autophagy alone can drive cell death under physiologically relevant circumstances. Here, we review the role of autophagy in cell death and examine how autophagy interfaces with other forms of cell death including apoptosis and necrosis.
Collapse
|
8
|
Midgut morphological changes and autophagy during metamorphosis in sand flies. Cell Tissue Res 2017; 368:513-529. [DOI: 10.1007/s00441-017-2586-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 02/06/2017] [Indexed: 10/20/2022]
|
9
|
Mutants for Drosophila Isocitrate Dehydrogenase 3b Are Defective in Mitochondrial Function and Larval Cell Death. G3-GENES GENOMES GENETICS 2017; 7:789-799. [PMID: 28104670 PMCID: PMC5345709 DOI: 10.1534/g3.116.037366] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The death of larval salivary gland cells during metamorphosis in Drosophila melanogaster has been a key system for studying steroid controlled programmed cell death. This death is induced by a pulse of the steroid hormone ecdysone that takes place at the end of the prepupal period. For many years, it has been thought that the ecdysone direct response gene Eip93F (E93) plays a critical role in initiating salivary gland cell death. This conclusion was based largely on the finding that the three “type” alleles of E93 cause a near-complete block in salivary gland cell death. Here, we show that these three mutations are in fact allelic to Idh3b, a nearby gene that encodes the β subunit of isocitrate dehydrogenase 3, a mitochondrial enzyme of the tricarboxylic acid (TCA) cycle. The strongest of the Idh3b alleles appears to cause a near-complete block in oxidative phosphorylation, as mitochondria are depolarized in mutant larvae, and development arrests early during cleavage in embryos from homozygous-mutant germline mothers. Idh3b-mutant larval salivary gland cells fail to undergo mitochondrial fragmentation, which normally precedes the death of these cells, and do not initiate autophagy, an early step in the cell death program. These observations suggest a close relationship between the TCA cycle and the initiation of larval cell death. In normal development, tagged Idh3b is released from salivary gland mitochondria during their fragmentation, suggesting that Idh3b may be an apoptogenic factor that functions much like released cytochrome c in mammalian cells.
Collapse
|
10
|
Brandão ADS, do Amaral JB, Rezende-Teixeira P, Hartfelder K, Siviero F, Machado-Santelli GM. Cell death and tissue reorganization in Rhynchosciara americana (Sciaridae: Diptera) metamorphosis and their relation to molting hormone titers. ARTHROPOD STRUCTURE & DEVELOPMENT 2014; 43:511-522. [PMID: 24943875 DOI: 10.1016/j.asd.2014.05.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 05/02/2014] [Accepted: 05/12/2014] [Indexed: 06/03/2023]
Abstract
Programmed cell death (PCD) is a focal topic for understanding processes underlying metamorphosis in insects, especially so in holometabolous orders. During adult morphogenesis it allows for the elimination of larva-specific tissues and the reorganization of others for their functionalities in adult life. In Rhynchosciara, this PCD process could be classified as autophagic cell death, yet the expression of apoptosis-related genes and certain morphological aspects suggest that processes, autophagy and apoptosis may be involved. Aiming to reveal the morphological changes that salivary gland and fat body cells undergo during metamorphosis we conducted microscopy analyses to detect chromatin condensation and fragmentation, as well as alterations in the cytoplasm of late pupal tissues of Rhynchosciara americana. Transmission electron microscopy and confocal microscopy revealed cells in variable stages of death. By analyzing the morphological structure of the salivary gland we observed the presence of cells with autophagic vacuoles and apoptotic bodies and DNA fragmentation was confirmed with the TUNEL assay in salivary gland. The reorganization of fat body occurs with discrete detection of cell death by TUNEL assay. However, both salivary gland histolysis and fat body reorganization occur under control of the hormone ecdysone.
Collapse
Affiliation(s)
- Amanda Dos Santos Brandão
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1524, Ed Biomédicas 1, CEP 05508-000 São Paulo, SP, Brazil; Post-Graduate Interunits Program in Biotechnology, Av. Prof. Lineu Prestes, 2415 Edifício ICB - III - Cidade Universitária, CEP 05508-900 São Paulo, SP, Brazil.
| | - Jônatas Bussador do Amaral
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1524, Ed Biomédicas 1, CEP 05508-000 São Paulo, SP, Brazil.
| | - Paula Rezende-Teixeira
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1524, Ed Biomédicas 1, CEP 05508-000 São Paulo, SP, Brazil.
| | - Klaus Hartfelder
- Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Av. Bandeirantes 3900, CEP 14049-900 Ribeirão Preto, SP, Brazil.
| | - Fábio Siviero
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1524, Ed Biomédicas 1, CEP 05508-000 São Paulo, SP, Brazil.
| | - Gláucia Maria Machado-Santelli
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1524, Ed Biomédicas 1, CEP 05508-000 São Paulo, SP, Brazil.
| |
Collapse
|
11
|
Lőw P, Varga Á, Pircs K, Nagy P, Szatmári Z, Sass M, Juhász G. Impaired proteasomal degradation enhances autophagy via hypoxia signaling in Drosophila. BMC Cell Biol 2013; 14:29. [PMID: 23800266 PMCID: PMC3700814 DOI: 10.1186/1471-2121-14-29] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Accepted: 06/21/2013] [Indexed: 01/04/2023] Open
Abstract
Background Two pathways are responsible for the majority of regulated protein catabolism in eukaryotic cells: the ubiquitin-proteasome system (UPS) and lysosomal self-degradation through autophagy. Both processes are necessary for cellular homeostasis by ensuring continuous turnover and quality control of most intracellular proteins. Recent studies established that both UPS and autophagy are capable of selectively eliminating ubiquitinated proteins and that autophagy may partially compensate for the lack of proteasomal degradation, but the molecular links between these pathways are poorly characterized. Results Here we show that autophagy is enhanced by the silencing of genes encoding various proteasome subunits (α, β or regulatory) in larval fat body cells. Proteasome inactivation induces canonical autophagy, as it depends on core autophagy genes Atg1, Vps34, Atg9, Atg4 and Atg12. Large-scale accumulation of aggregates containing p62 and ubiquitinated proteins is observed in proteasome RNAi cells. Importantly, overexpressed Atg8a reporters are captured into the cytoplasmic aggregates, but these do not represent autophagosomes. Loss of p62 does not block autophagy upregulation upon proteasome impairment, suggesting that compensatory autophagy is not simply due to the buildup of excess cargo. One of the best characterized substrates of UPS is the α subunit of hypoxia-inducible transcription factor 1 (HIF-1α), which is continuously degraded by the proteasome during normoxic conditions. Hypoxia is a known trigger of autophagy in mammalian cells, and we show that genetic activation of hypoxia signaling also induces autophagy in Drosophila. Moreover, we find that proteasome inactivation-induced autophagy requires sima, the Drosophila ortholog of HIF-1α. Conclusions We have characterized proteasome inactivation- and hypoxia signaling-induced autophagy in the commonly used larval Drosophila fat body model. Activation of both autophagy and hypoxia signaling was implicated in various cancers, and mutations affecting genes encoding UPS enzymes have recently been suggested to cause renal cancer. Our studies identify a novel genetic link that may play an important role in that context, as HIF-1α/sima may contribute to upregulation of autophagy by impaired proteasomal activity.
Collapse
Affiliation(s)
- Péter Lőw
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pázmány P. s. 1/C, H-1117, Budapest, Hungary
| | | | | | | | | | | | | |
Collapse
|