1
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Wang W, Zhu T, Lai F, Wan P, Wei Q, Fu Q. Identification and functional analysis of five genes that encode distinct isoforms of protein phosphatase 1 in Nilaparvata lugens. Sci Rep 2020; 10:10885. [PMID: 32616748 PMCID: PMC7331678 DOI: 10.1038/s41598-020-67735-7] [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: 02/14/2020] [Accepted: 06/11/2020] [Indexed: 11/09/2022] Open
Abstract
Ten distinct cDNAs encoding five different protein phosphatases 1 (PPP1) were cloned from Nilaparvata lugens. NlPPP1α and NlPPP1β are highly conserved whereas NlPPP1-Y, NlPPP1-Y1 and NlPPP1-Y2 are lowly conserved among insects. NlPPP1α and NlPPP1β exhibited a ubiquitous expression, while NlPPP1-Y, NlPPP1-Y1, and NlPPP1-Y2 were obviously detected from the 4th instar nymph to imago developmental stages in males, especially detected in internal reproductive organ and fat bodies of the male. Injection nymphs with dsRNA of NlPPP1α or NlPPP1β was able to reduce the target gene expression in a range of 71.5-91.0%, inducing a maximum mortality rate of 95.2% or 97.2% at 10th day after injection and eclosion ratio down by 65.5-100.0%. Injection with dsNlPPP1Ys targeted to NlPPP1-Y, NlPPP1-Y1and NlPPP1-Y2 was able to induce a maximum mortality rate of 95.5% at 10th day after injection, eclosion ratio down by 86.4%. Knock-down one of the male-biased NlPPP1 genes has no effect on survival and eclosion ratio. Injection of 4th instar nymph with dsNlPPP1Ys led to reduced oviposition amount and hatchability, down by 44.7% and 19.6% respectively. Knock-down of NlPPP1-Y1 or NlPPP1-Y2 gene did not significantly affect oviposition amount but significantly affected hatchability. The results indicate that the male-biased NlPPP1 genes have overlapping functions in N. lugens development, and NlPPP1-Y1 and NlPPP1-Y2 may play important roles in spermatogenesis and fertilization. The dsNlPPP1β and dsNlPPP1Ys in this study could be the preferred sequence in RNAi and low-conserved male-biased NlPPP1 genes could be potential target for N. lugens control.
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Affiliation(s)
- Weixia Wang
- State Key Lab of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, Zhejiang, China
| | - Tingheng Zhu
- College of Biotechnology and Biongineering, Zhejiang University of Technology, Chaowang Road, Hangzhou, 310014, Zhejiang, China.
| | - Fengxiang Lai
- State Key Lab of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, Zhejiang, China
| | - Pinjun Wan
- State Key Lab of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, Zhejiang, China
| | - Qi Wei
- State Key Lab of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, Zhejiang, China
| | - Qiang Fu
- State Key Lab of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, Zhejiang, China.
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2
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Dudiki T, Joudeh N, Sinha N, Goswami S, Eisa A, Kline D, Vijayaraghavan S. The protein phosphatase isoform PP1γ1 substitutes for PP1γ2 to support spermatogenesis but not normal sperm function and fertility†. Biol Reprod 2020; 100:721-736. [PMID: 30379985 DOI: 10.1093/biolre/ioy225] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 08/11/2018] [Accepted: 10/16/2018] [Indexed: 01/09/2023] Open
Abstract
Four isoforms of serine/threonine phosphatase type I, PP1α, PP1β, PP1γ1, and PP1γ2, are derived from three genes. The PP1γ1 and PP1γ2 isoforms are alternately spliced transcripts of the protein phosphatase 1 catalytic subunit gamma gene (Ppp1cc). While PP1γ1 is ubiquitous in somatic cells, PP1γ2 is expressed exclusively in testicular germ cells and sperm. Ppp1cc knockout male mice (-/-), lacking both PP1γ1 and PP1γ2, are sterile due to impaired sperm morphogenesis. Fertility and normal sperm function can be restored by transgenic expression of PP1γ2 alone in testis of Ppp1cc (-/-) mice. The purpose of this study was to determine whether the PP1γ1 isoform is functionally equivalent to PP1γ2 in supporting spermatogenesis and male fertility. Significant levels of transgenic PP1γ1 expression occurred only when the transgene lacked a 1-kb 3΄UTR region immediately following the stop codon of the PP1γ1 transcript. PP1γ1 was also incorporated into sperm at levels comparable to PP1γ2 in sperm from wild-type mice. Spermatogenesis was restored in mice expressing PP1γ1 in the absence of PP1γ2. However, males from the transgenic rescue lines were subfertile. Sperm from the PP1γ1 rescue mice were unable to fertilize eggs in vitro. Intrasperm localization of PP1γ1 and the association of the protein regulators of the phosphatase were altered in epididymal sperm in transgenic PP1γ1 compared to PP1γ2. Thus, the ubiquitous isoform PP1γ1, not normally expressed in differentiating germ cells, could replace PP1γ2 to support spermatogenesis and spermiation. However, PP1γ2, which is the PP1 isoform in mammalian sperm, has an isoform-specific role in supporting normal sperm function and fertility.
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Affiliation(s)
- Tejasvi Dudiki
- Department of Biological Sciences, Kent State University, Kent, Ohio, USA
| | - Nidaa Joudeh
- Department of Biological Sciences, Kent State University, Kent, Ohio, USA
| | - Nilam Sinha
- Department of Biological Sciences, Kent State University, Kent, Ohio, USA.,School of Veterinary Medicine, University of Pennsylvania, Philadelphia Pennsylvania, USA
| | - Suranjana Goswami
- Department of Biological Sciences, Kent State University, Kent, Ohio, USA
| | - Alaa Eisa
- Department of Biological Sciences, Kent State University, Kent, Ohio, USA
| | - Douglas Kline
- Department of Biological Sciences, Kent State University, Kent, Ohio, USA
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3
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Green N, Walker J, Bontrager A, Zych M, Geisbrecht ER. A tissue communication network coordinating innate immune response during muscle stress. J Cell Sci 2018; 131:jcs.217943. [PMID: 30478194 DOI: 10.1242/jcs.217943] [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: 03/27/2018] [Accepted: 11/15/2018] [Indexed: 12/23/2022] Open
Abstract
Complex tissue communication networks function throughout an organism's lifespan to maintain tissue homeostasis. Using the genetic model Drosophila melanogaster, we have defined a network of immune responses that are activated following the induction of muscle stresses, including hypercontraction, detachment and oxidative stress. Of these stressors, loss of the genes that cause muscle detachment produced the strongest levels of JAK-STAT activation. In one of these mutants, fondue (fon), we also observe hemocyte recruitment and the accumulation of melanin at muscle attachment sites (MASs), indicating a broad involvement of innate immune responses upon muscle detachment. Loss of fon results in pathogen-independent Toll signaling in the fat body and increased expression of the Toll-dependent antimicrobial peptide Drosomycin. Interestingly, genetic interactions between fon and various Toll pathway components enhance muscle detachment. Finally, we show that JAK-STAT and Toll signaling are capable of reciprocal activation in larval tissues. We propose a model of tissue communication for the integration of immune responses at the local and systemic level in response to altered muscle physiology.
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Affiliation(s)
- Nicole Green
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
| | - Justin Walker
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
| | - Alexandria Bontrager
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
| | - Molly Zych
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
| | - Erika R Geisbrecht
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
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4
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Zhao L, Lu Z, He X, Mughal MN, Fang R, Zhou Y, Zhao J, Gasser RB, Grevelding CG, Ye Q, Hu M. Serine/threonine protein phosphatase 1 (PP1) controls growth and reproduction in Schistosoma japonicum. FASEB J 2018; 32:fj201800725R. [PMID: 29879373 DOI: 10.1096/fj.201800725r] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Schistosomiasis is a human parasitic disease caused by flatworms of the genus Schistosoma. Adult female schistosomes produce numerous eggs that are responsible for the pathogenesis and transmission of the disease, and the maturation of female gonads depends on the permanent pairing of females and males. Signaling protein kinases have been proven to control female gonad differentiation after pairing; however, little is known about the roles of protein phosphatases in the developmental and reproductive biology of schistosomes. Here we explored 3 genes encoding catalytic subunits of serine/threonine protein phosphatase 1 (PP1c) that were structurally and evolutionarily conserved in Schistosoma japonicum. In situ hybridization showed transcripts of 3 Sj-pp1c genes mainly localized in the reproductive organs and tissues. Triple knockdown of Sj-pp1c genes by RNA interference caused stunted growth and decreased pairing stability of worm pairs, as well as a remarkable reduction in cell proliferation activity and defects in reproductive maturation and fecundity. Transcriptomic analysis post-RNA interference suggested that Sj-pp1c genes are involved in controlling worm development and maturation mainly by regulating cell proliferation, eggshell synthesis, nutritional metabolism, cytoskeleton organization, and neural process. Our study provides the first insight into the fundamental contribution of Sj-PP1c to molecular mechanisms underlying the reproductive biology of schistosomes.-Zhao, L., Lu, Z., He, X., Mughal, M. N., Fang, R., Zhou, Y., Zhao, J., Gasser, R. B., Grevelding, C. G., Ye, Q., Hu, M. Serine/threonine protein phosphatase 1 (PP1) controls growth and reproduction in Schistosoma japonicum.
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Affiliation(s)
- Lu Zhao
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Zhigang Lu
- Institute of Parasitology, Biomedical Research Center Seltersberg (BFS), Justus Liebig University, Giessen, Germany
| | - Xin He
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Mudassar N Mughal
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Rui Fang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Yanqin Zhou
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Junlong Zhao
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Robin B Gasser
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Melbourne, Australia
| | - Christoph G Grevelding
- Institute of Parasitology, Biomedical Research Center Seltersberg (BFS), Justus Liebig University, Giessen, Germany
| | - Qing Ye
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Min Hu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
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5
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Valencia-Expósito A, Grosheva I, Míguez DG, González-Reyes A, Martín-Bermudo MD. Myosin light-chain phosphatase regulates basal actomyosin oscillations during morphogenesis. Nat Commun 2016; 7:10746. [PMID: 26888436 PMCID: PMC4759631 DOI: 10.1038/ncomms10746] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 01/18/2016] [Indexed: 01/09/2023] Open
Abstract
Contractile actomyosin networks generate forces that drive tissue morphogenesis. Actomyosin contractility is controlled primarily by reversible phosphorylation of the myosin-II regulatory light chain through the action of myosin kinases and phosphatases. While the role of myosin light-chain kinase in regulating contractility during morphogenesis has been largely characterized, there is surprisingly little information on myosin light-chain phosphatase (MLCP) function in this context. Here, we use live imaging of Drosophila follicle cells combined with mathematical modelling to demonstrate that the MLCP subunit flapwing (flw) is a key regulator of basal myosin oscillations and cell contractions underlying egg chamber elongation. Flw expression decreases specifically on the basal side of follicle cells at the onset of contraction and flw controls the initiation and periodicity of basal actomyosin oscillations. Contrary to previous reports, basal F-actin pulsates similarly to myosin. Finally, we propose a quantitative model in which periodic basal actomyosin oscillations arise in a cell-autonomous fashion from intrinsic properties of motor assemblies. Actomyosin contractility is regulated by phosphorylation of myosin regulatory light chain; much of the work in this area has focused on the kinase. Here the authors use Drosophila follicle cells and modelling to show that the phosphatase subunit Flapwing controls the initiation and dynamics of actomyosin oscillations.
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Affiliation(s)
- Andrea Valencia-Expósito
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide/CSIC/JA, Carretera de Utrera km 1, Sevilla 41013, Spain
| | - Inna Grosheva
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide/CSIC/JA, Carretera de Utrera km 1, Sevilla 41013, Spain
| | - David G Míguez
- Departamento de Física de la Materia Condensada, Instituto de Ciencias de Materiales Nicolás Cabrera, Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Acaimo González-Reyes
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide/CSIC/JA, Carretera de Utrera km 1, Sevilla 41013, Spain
| | - María D Martín-Bermudo
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide/CSIC/JA, Carretera de Utrera km 1, Sevilla 41013, Spain
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6
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Weber S, Meyer-Roxlau S, Wagner M, Dobrev D, El-Armouche A. Counteracting Protein Kinase Activity in the Heart: The Multiple Roles of Protein Phosphatases. Front Pharmacol 2015; 6:270. [PMID: 26617522 PMCID: PMC4643138 DOI: 10.3389/fphar.2015.00270] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 10/28/2015] [Indexed: 12/19/2022] Open
Abstract
Decades of cardiovascular research have shown that variable and flexible levels of protein phosphorylation are necessary to maintain cardiac function. A delicate balance between phosphorylated and dephosphorylated states of proteins is guaranteed by a complex interplay of protein kinases (PKs) and phosphatases. Serine/threonine phosphatases, in particular members of the protein phosphatase (PP) family govern dephosphorylation of the majority of these cardiac proteins. Recent findings have however shown that PPs do not only dephosphorylate previously phosphorylated proteins as a passive control mechanism but are capable to actively control PK activity via different direct and indirect signaling pathways. These control mechanisms can take place on (epi-)genetic, (post-)transcriptional, and (post-)translational levels. In addition PPs themselves are targets of a plethora of proteinaceous interaction partner regulating their endogenous activity, thus adding another level of complexity and feedback control toward this system. Finally, novel approaches are underway to achieve spatiotemporal pharmacologic control of PPs which in turn can be used to fine-tune misleaded PK activity in heart disease. Taken together, this review comprehensively summarizes the major aspects of PP-mediated PK regulation and discusses the subsequent consequences of deregulated PP activity for cardiovascular diseases in depth.
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Affiliation(s)
- Silvio Weber
- Department of Pharmacology and Toxicology, Dresden University of Technology , Dresden, Germany
| | - Stefanie Meyer-Roxlau
- Department of Pharmacology and Toxicology, Dresden University of Technology , Dresden, Germany
| | - Michael Wagner
- Department of Pharmacology and Toxicology, Dresden University of Technology , Dresden, Germany
| | - Dobromir Dobrev
- Institute of Pharmacology, Faculty of Medicine, West German Heart and Vascular Center , Essen, Germany
| | - Ali El-Armouche
- Department of Pharmacology and Toxicology, Dresden University of Technology , Dresden, Germany
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7
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Flores-Benitez D, Knust E. Crumbs is an essential regulator of cytoskeletal dynamics and cell-cell adhesion during dorsal closure in Drosophila. eLife 2015; 4. [PMID: 26544546 PMCID: PMC4718732 DOI: 10.7554/elife.07398] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 11/06/2015] [Indexed: 12/12/2022] Open
Abstract
The evolutionarily conserved Crumbs protein is required for epithelial polarity and morphogenesis. Here we identify a novel role of Crumbs as a negative regulator of actomyosin dynamics during dorsal closure in the Drosophila embryo. Embryos carrying a mutation in the FERM (protein 4.1/ezrin/radixin/moesin) domain-binding motif of Crumbs die due to an overactive actomyosin network associated with disrupted adherens junctions. This phenotype is restricted to the amnioserosa and does not affect other embryonic epithelia. This function of Crumbs requires DMoesin, the Rho1-GTPase, class-I p21-activated kinases and the Arp2/3 complex. Data presented here point to a critical role of Crumbs in regulating actomyosin dynamics, cell junctions and morphogenesis. DOI:http://dx.doi.org/10.7554/eLife.07398.001 A layer of epithelial cells covers the body surface of animals. Epithelial cells have a property known as polarity; this means that they have two different poles, one of which is in contact with the environment. Midway through embryonic development, the Drosophila embryo is covered by two kinds of epithelial sheets; the epidermis on the front, the belly and the sides of the embryo, and the amnioserosa on the back. In the second half of embryonic development, the amnioserosa is brought into the embryo in a process called dorsal closure, while the epidermis expands around the back of the embryo to encompass it. One of the major activities driving dorsal closure is the contraction of amnioserosa cells. This contraction depends on the highly dynamic activity of the protein network that helps give cells their shape, known as the actomyosin cytoskeleton. One major question in the field is how changes in the actomyosin cytoskeleton are controlled as tissues take shape (a process known as “morphogenesis”) and how the integrity of epithelial tissues is maintained during these processes. A key regulator of epidermal and amnioserosa polarity is an evolutionarily conserved protein called Crumbs. The epithelial tissues of mutant embryos that do not produce Crumbs lose polarity and integrity, and the embryos fail to develop properly. Flores-Benitez and Knust have now studied the role of Crumbs in the morphogenesis of the amnioserosa during dorsal closure. This revealed that fly embryos that produce a mutant Crumbs protein that cannot interact with a protein called Moesin (which links the cell membrane and the actomyosin cytoskeleton) are unable to complete dorsal closure. Detailed analyses showed that this failure of dorsal closure is due to the over-activity of the actomyosin cytoskeleton in the amnioserosa. This results in increased and uncoordinated contractions of the cells, and is accompanied by defects in cell-cell adhesion that ultimately cause the amnioserosa to lose integrity. Flores-Benitez and Knust’s genetic analyses further showed that several different signalling systems participate in this process. Flores-Benitez and Knust’s results reveal an unexpected role of Crumbs in coordinating polarity, actomyosin activity and cell-cell adhesion. Further work is now needed to understand the molecular mechanisms and interactions that enable Crumbs to coordinate these processes; in particular, to unravel how Crumbs influences the periodic contractions that drive changes in cell shape. It will also be important to investigate whether Crumbs is involved in similar mechanisms that operate in other developmental events in which actomyosin oscillations have been linked to tissue morphogenesis. DOI:http://dx.doi.org/10.7554/eLife.07398.002
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Affiliation(s)
| | - Elisabeth Knust
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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8
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A cis-regulatory mutation in troponin-I of Drosophila reveals the importance of proper stoichiometry of structural proteins during muscle assembly. Genetics 2015; 200:149-65. [PMID: 25747460 DOI: 10.1534/genetics.115.175604] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 03/01/2015] [Indexed: 02/02/2023] Open
Abstract
Rapid and high wing-beat frequencies achieved during insect flight are powered by the indirect flight muscles, the largest group of muscles present in the thorax. Any anomaly during the assembly and/or structural impairment of the indirect flight muscles gives rise to a flightless phenotype. Multiple mutagenesis screens in Drosophila melanogaster for defective flight behavior have led to the isolation and characterization of mutations that have been instrumental in the identification of many proteins and residues that are important for muscle assembly, function, and disease. In this article, we present a molecular-genetic characterization of a flightless mutation, flightless-H (fliH), originally designated as heldup-a (hdp-a). We show that fliH is a cis-regulatory mutation of the wings up A (wupA) gene, which codes for the troponin-I protein, one of the troponin complex proteins, involved in regulation of muscle contraction. The mutation leads to reduced levels of troponin-I transcript and protein. In addition to this, there is also coordinated reduction in transcript and protein levels of other structural protein isoforms that are part of the troponin complex. The altered transcript and protein stoichiometry ultimately culminates in unregulated acto-myosin interactions and a hypercontraction muscle phenotype. Our results shed new insights into the importance of maintaining the stoichiometry of structural proteins during muscle assembly for proper function with implications for the identification of mutations and disease phenotypes in other species, including humans.
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9
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Ferreira T, Prudêncio P, Martinho RG. Drosophila protein kinase N (Pkn) is a negative regulator of actin-myosin activity during oogenesis. Dev Biol 2014; 394:277-91. [PMID: 25131196 DOI: 10.1016/j.ydbio.2014.08.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 08/08/2014] [Accepted: 08/09/2014] [Indexed: 02/05/2023]
Abstract
Nurse cell dumping is an actin-myosin based process, where 15 nurse cells of a given egg chamber contract and transfer their cytoplasmic content through the ring canals into the growing oocyte. We isolated two mutant alleles of protein kinase N (pkn) and showed that Pkn negatively-regulates activation of the actin-myosin cytoskeleton during the onset of dumping. Using live-cell imaging analysis we observed that nurse cell dumping rates sharply increase during the onset of fast dumping. Such rate increase was severely impaired in pkn mutant nurse cells due to excessive nurse cell actin-myosin activity and/or loss of tissue integrity. Our work demonstrates that the transition between slow and fast dumping is a discrete event, with at least a five to six-fold dumping rate increase. We show that Pkn negatively regulates nurse cell actin-myosin activity. This is likely to be important for directional cytoplasmic flow. We propose Pkn provides a negative feedback loop to help avoid excessive contractility after local activation of Rho GTPase.
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Affiliation(s)
- Tânia Ferreira
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras 2781-901, Portugal
| | - Pedro Prudêncio
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras 2781-901, Portugal; Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; IBB-Institute for Biotechnology and Bioengineering, Centro de Biomedicina Molecular e Estrutural, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Rui Gonçalo Martinho
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras 2781-901, Portugal; Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; IBB-Institute for Biotechnology and Bioengineering, Centro de Biomedicina Molecular e Estrutural, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
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10
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Williams BC, Filter JJ, Blake-Hodek KA, Wadzinski BE, Fuda NJ, Shalloway D, Goldberg ML. Greatwall-phosphorylated Endosulfine is both an inhibitor and a substrate of PP2A-B55 heterotrimers. eLife 2014; 3:e01695. [PMID: 24618897 PMCID: PMC3949306 DOI: 10.7554/elife.01695] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 01/30/2014] [Indexed: 11/13/2022] Open
Abstract
During M phase, Endosulfine (Endos) family proteins are phosphorylated by Greatwall kinase (Gwl), and the resultant pEndos inhibits the phosphatase PP2A-B55, which would otherwise prematurely reverse many CDK-driven phosphorylations. We show here that PP2A-B55 is the enzyme responsible for dephosphorylating pEndos during M phase exit. The kinetic parameters for PP2A-B55's action on pEndos are orders of magnitude lower than those for CDK-phosphorylated substrates, suggesting a simple model for PP2A-B55 regulation that we call inhibition by unfair competition. As the name suggests, during M phase PP2A-B55's attention is diverted to pEndos, which binds much more avidly and is dephosphorylated more slowly than other substrates. When Gwl is inactivated during the M phase-to-interphase transition, the dynamic balance changes: pEndos dephosphorylated by PP2A-B55 cannot be replaced, so the phosphatase can refocus its attention on CDK-phosphorylated substrates. This mechanism explains simultaneously how PP2A-B55 and Gwl together regulate pEndos, and how pEndos controls PP2A-B55. DOI: http://dx.doi.org/10.7554/eLife.01695.001.
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Affiliation(s)
- Byron C Williams
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - Joshua J Filter
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | | | - Brian E Wadzinski
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, United States
| | - Nicholas J Fuda
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - David Shalloway
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - Michael L Goldberg
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
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11
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Yamamoto S, Bayat V, Bellen HJ, Tan C. Protein phosphatase 1ß limits ring canal constriction during Drosophila germline cyst formation. PLoS One 2013; 8:e70502. [PMID: 23936219 PMCID: PMC3723691 DOI: 10.1371/journal.pone.0070502] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 06/20/2013] [Indexed: 12/15/2022] Open
Abstract
Germline cyst formation is essential for the propagation of many organisms including humans and flies. The cytoplasm of germline cyst cells communicate with each other directly via large intercellular bridges called ring canals. Ring canals are often derived from arrested contractile rings during incomplete cytokinesis. However how ring canal formation, maintenance and growth are regulated remains unclear. To better understand this process, we carried out an unbiased genetic screen in Drosophila melanogaster germ cells and identified multiple alleles of flapwing (flw), a conserved serine/threonine-specific protein phosphatase. Flw had previously been reported to be unnecessary for early D. melanogaster oogenesis using a hypomorphic allele. We found that loss of Flw leads to over-constricted nascent ring canals and subsequently tiny mature ring canals, through which cytoplasmic transfer from nurse cells to the oocyte is impaired, resulting in small, non-functional eggs. Flw is expressed in germ cells undergoing incomplete cytokinesis, completely colocalized with the Drosophila myosin binding subunit of myosin phosphatase (DMYPT). This colocalization, together with genetic interaction studies, suggests that Flw functions together with DMYPT to negatively regulate myosin activity during ring canal formation. The identification of two subunits of the tripartite myosin phosphatase as the first two main players required for ring canal constriction indicates that tight regulation of myosin activity is essential for germline cyst formation and reproduction in D. melanogaster and probably other species as well.
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Affiliation(s)
- Shinya Yamamoto
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Baylor College of Medicine and Texas Children’s Hospital, Houston, Texas, United States of America
| | - Vafa Bayat
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Medical Scientist Training Program, Baylor College of Medicine, Houston, Texas, United States of America
| | - Hugo J. Bellen
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Baylor College of Medicine and Texas Children’s Hospital, Houston, Texas, United States of America
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas, United States of America
| | - Change Tan
- Division of Biological Sciences, Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
- * E-mail:
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12
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Pronovost SM, Beckerle MC, Kadrmas JL. Elevated expression of the integrin-associated protein PINCH suppresses the defects of Drosophila melanogaster muscle hypercontraction mutants. PLoS Genet 2013; 9:e1003406. [PMID: 23555310 PMCID: PMC3610608 DOI: 10.1371/journal.pgen.1003406] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 02/07/2013] [Indexed: 01/05/2023] Open
Abstract
A variety of human diseases arise from mutations that alter muscle contraction. Evolutionary conservation allows genetic studies in Drosophila melanogaster to be used to better understand these myopathies and suggest novel therapeutic strategies. Integrin-mediated adhesion is required to support muscle structure and function, and expression of Integrin adhesive complex (IAC) proteins is modulated to adapt to varying levels of mechanical stress within muscle. Mutations in flapwing (flw), a catalytic subunit of myosin phosphatase, result in non-muscle myosin hyperphosphorylation, as well as muscle hypercontraction, defects in size, motility, muscle attachment, and subsequent larval and pupal lethality. We find that moderately elevated expression of the IAC protein PINCH significantly rescues flw phenotypes. Rescue requires PINCH be bound to its partners, Integrin-linked kinase and Ras suppressor 1. Rescue is not achieved through dephosphorylation of non-muscle myosin, suggesting a mechanism in which elevated PINCH expression strengthens integrin adhesion. In support of this, elevated expression of PINCH rescues an independent muscle hypercontraction mutant in muscle myosin heavy chain, MhcSamba1. By testing a panel of IAC proteins, we show specificity for PINCH expression in the rescue of hypercontraction mutants. These data are consistent with a model in which PINCH is present in limiting quantities within IACs, with increasing PINCH expression reinforcing existing adhesions or allowing for the de novo assembly of new adhesion complexes. Moreover, in myopathies that exhibit hypercontraction, strategic PINCH expression may have therapeutic potential in preserving muscle structure and function. A wide variety of diseases of the muscle are caused by mutations that alter either the actin and myosin contractile machinery or its regulation. One class of mutations of interest results in hypercontraction of the muscle—actin and myosin fibers contract, but cannot efficiently relax. We have used the fruit fly as a model to study these mutations because of the striking similarity of fly and human muscle and because of the many genetic techniques that are available in the fly. Using a genetic approach we identified a protein, PINCH, whose increased expression can rescue the defects observed in hypercontraction mutants. PINCH is a component of integrin adhesion complexes, responsible for anchoring cells in their environment. This suggests that strengthening the anchorage of muscles via PINCH may be an effective strategy to prevent or reduce the muscle damage that occurs in diseases of muscle hypercontraction.
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Affiliation(s)
- Stephen M. Pronovost
- Huntsman Cancer Institute, Departments of Biology and Oncological Sciences, University of Utah, Salt Lake City, Utah, United States of America
| | - Mary C. Beckerle
- Huntsman Cancer Institute, Departments of Biology and Oncological Sciences, University of Utah, Salt Lake City, Utah, United States of America
| | - Julie L. Kadrmas
- Huntsman Cancer Institute, Departments of Biology and Oncological Sciences, University of Utah, Salt Lake City, Utah, United States of America
- * E-mail:
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13
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Horn T, Boutros M. Design of RNAi reagents for invertebrate model organisms and human disease vectors. Methods Mol Biol 2013; 942:315-346. [PMID: 23027059 DOI: 10.1007/978-1-62703-119-6_17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
RNAi has become a very versatile tool to silence gene expression in a variety of organisms, in particular when classical genetic methods are missing. However, the application of this method in functional studies has raised new challenges in order to design RNAi reagents that minimize false positives and false negatives. Because the performance of reagents cannot be validated on a genome-wide scale, improved computational methods are required that consider experimentally derived quality measures. In this chapter, we describe computational methods for the design of RNAi reagents for invertebrate model organisms and human disease vectors, such as Anopheles. We describe procedures for designing short and long double-stranded RNAs for single genes, and evaluate their predicted specificity and efficiency. Using a bioinformatics pipeline we also describe how to design a genome-wide RNAi library for Anopheles gambiae.
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Affiliation(s)
- Thomas Horn
- Department of Cell and Molecular Biology, Heidelberg University, Heidelberg, Germany
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14
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Miskei M, Ádám C, Kovács L, Karányi Z, Dombrádi V. Molecular evolution of phosphoprotein phosphatases in Drosophila. PLoS One 2011; 6:e22218. [PMID: 21789237 PMCID: PMC3137614 DOI: 10.1371/journal.pone.0022218] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Accepted: 06/20/2011] [Indexed: 12/25/2022] Open
Abstract
Phosphoprotein phosphatases (PPP), these ancient and important regulatory enzymes are present in all eukaryotic organisms. Based on the genome sequences of 12 Drosophila species we traced the evolution of the PPP catalytic subunits and noted a substantial expansion of the gene family. We concluded that the 18–22 PPP genes of Drosophilidae were generated from a core set of 8 indispensable phosphatases that are present in most of the insects. Retropositons followed by tandem gene duplications extended the phosphatase repertoire, and sporadic gene losses contributed to the species specific variations in the PPP complement. During the course of these studies we identified 5, up till now uncharacterized phosphatase retrogenes: PpY+, PpD5+, PpD6+, Pp4+, and Pp6+ which are found only in some ancient Drosophila. We demonstrated that all of these new PPP genes exhibit a distinct male specific expression. In addition to the changes in gene numbers, the intron-exon structure and the chromosomal localization of several PPP genes was also altered during evolution. The G−C content of the coding regions decreased when a gene moved into the heterochromatic region of chromosome Y. Thus the PPP enzymes exemplify the various types of dynamic rearrangements that accompany the molecular evolution of a gene family in Drosophilidae.
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Affiliation(s)
- Márton Miskei
- Centre for Agricultural and Applied Economic Sciences, Institute of Horticultural Sciences, Department of Plant Biotechnology, University of Debrecen, Debrecen, Hungary
| | - Csaba Ádám
- Department of Medical Chemistry, Research Center for Molecular Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
| | - László Kovács
- Department of Medical Chemistry, Research Center for Molecular Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
| | - Zsolt Karányi
- First Department of Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Viktor Dombrádi
- Department of Medical Chemistry, Research Center for Molecular Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
- * E-mail:
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15
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Sun Y, Yan Y, Denef N, Schüpbach T. Regulation of somatic myosin activity by protein phosphatase 1β controls Drosophila oocyte polarization. Development 2011; 138:1991-2001. [PMID: 21490061 DOI: 10.1242/dev.062190] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Drosophila body axes are established in the oocyte during oogenesis. Oocyte polarization is initiated by Gurken, which signals from the germline through the epidermal growth factor receptor (Egfr) to the posterior follicle cells (PFCs). In response the PFCs generate an unidentified polarizing signal that regulates oocyte polarity. We have identified a loss-of-function mutation of flapwing, which encodes the catalytic subunit of protein phosphatase 1β (PP1β) that disrupts oocyte polarization. We show that PP1β, by regulating myosin activity, controls the generation of the polarizing signal. Excessive myosin activity in the PFCs causes oocyte mispolarization and defective Notch signaling and endocytosis in the PFCs. The integrated activation of JAK/STAT and Egfr signaling results in the sensitivity of PFCs to defective Notch. Interestingly, our results also demonstrate a role of PP1β in generating the polarizing signal independently of Notch, indicating a direct involvement of somatic myosin activity in axis formation.
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Affiliation(s)
- Yi Sun
- Howard Hughes Medical Institute, Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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16
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Fu G, Lees RS, Nimmo D, Aw D, Jin L, Gray P, Berendonk TU, White-Cooper H, Scaife S, Kim Phuc H, Marinotti O, Jasinskiene N, James AA, Alphey L. Female-specific flightless phenotype for mosquito control. Proc Natl Acad Sci U S A 2010; 107:4550-4. [PMID: 20176967 PMCID: PMC2826341 DOI: 10.1073/pnas.1000251107] [Citation(s) in RCA: 215] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Dengue and dengue hemorrhagic fever are increasing public health problems with an estimated 50-100 million new infections each year. Aedes aegypti is the major vector of dengue viruses in its range and control of this mosquito would reduce significantly human morbidity and mortality. Present mosquito control methods are not sufficiently effective and new approaches are needed urgently. A "sterile-male-release" strategy based on the release of mosquitoes carrying a conditional dominant lethal gene is an attractive new control methodology. Transgenic strains of Aedes aegypti were engineered to have a repressible female-specific flightless phenotype using either two separate transgenes or a single transgene, based on the use of a female-specific indirect flight muscle promoter from the Aedes aegypti Actin-4 gene. These strains eliminate the need for sterilization by irradiation, permit male-only release ("genetic sexing"), and enable the release of eggs instead of adults. Furthermore, these strains are expected to facilitate area-wide control or elimination of dengue if adopted as part of an integrated pest management strategy.
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Affiliation(s)
- Guoliang Fu
- Oxitec Limited, 71 Milton Park, Oxford OX14 4RX, United Kingdom
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom
| | - Rosemary S. Lees
- Oxitec Limited, 71 Milton Park, Oxford OX14 4RX, United Kingdom
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom
| | - Derric Nimmo
- Oxitec Limited, 71 Milton Park, Oxford OX14 4RX, United Kingdom
| | - Diane Aw
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697-3900; and
| | - Li Jin
- Oxitec Limited, 71 Milton Park, Oxford OX14 4RX, United Kingdom
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom
| | - Pam Gray
- Oxitec Limited, 71 Milton Park, Oxford OX14 4RX, United Kingdom
| | - Thomas U. Berendonk
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom
| | - Helen White-Cooper
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom
| | - Sarah Scaife
- Oxitec Limited, 71 Milton Park, Oxford OX14 4RX, United Kingdom
| | - Hoang Kim Phuc
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom
| | - Osvaldo Marinotti
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697-3900; and
| | - Nijole Jasinskiene
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697-3900; and
| | - Anthony A. James
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697-3900; and
- Department of Microbiology and Molecular Genetics, University of California, Irvine, CA 92697-3900
| | - Luke Alphey
- Oxitec Limited, 71 Milton Park, Oxford OX14 4RX, United Kingdom
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom
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17
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Kirchner J, Vissi E, Gross S, Szoor B, Rudenko A, Alphey L, White-Cooper H. Drosophila Uri, a PP1alpha binding protein, is essential for viability, maintenance of DNA integrity and normal transcriptional activity. BMC Mol Biol 2008; 9:36. [PMID: 18412953 PMCID: PMC2346476 DOI: 10.1186/1471-2199-9-36] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2007] [Accepted: 04/15/2008] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Protein phosphatase 1 (PP1) is involved in diverse cellular processes, and is targeted to substrates via interaction with many different protein binding partners. PP1 catalytic subunits (PP1c) fall into PP1alpha and PP1beta subfamilies based on sequence analysis, however very few PP1c binding proteins have been demonstrated to discriminate between PP1alpha and PP1beta. RESULTS URI (unconventional prefoldin RPB5 interactor) is a conserved molecular chaperone implicated in a variety of cellular processes, including the transcriptional response to nutrient signalling and maintenance of DNA integrity. We show that Drosophila Uri binds PP1alpha with much higher affinity than PP1beta, and that this ability to discriminate between PP1c forms is conserved to humans. Most Uri is cytoplasmic, however we found some protein associated with active RNAPII on chromatin. We generated a uri loss of function allele, and show that uri is essential for viability in Drosophila. uri mutants have transcriptional defects, reduced cell viability and differentiation in the germline, and accumulate DNA damage in their nuclei. CONCLUSION Uri is the first PP1alpha specific binding protein to be described in Drosophila. Uri protein plays a role in transcriptional regulation. Activity of uri is required to maintain DNA integrity and cell survival in normal development.
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Affiliation(s)
- Jasmin Kirchner
- Department of Zoology, University of Oxford, South Parks Rd, Oxford, OX1 3PS. UK
| | - Emese Vissi
- Department of Zoology, University of Oxford, South Parks Rd, Oxford, OX1 3PS. UK
| | - Sascha Gross
- Abbott Laboratories, Global Pharmaceutical Regulatory Affairs, Abbott Park, IL 60064-6157, USA
- Department of Zoology, University of Oxford, South Parks Rd, Oxford, OX1 3PS. UK
| | - Balazs Szoor
- Institute of Immunology and Infection Research, University of Edinburgh, EH9 3JT, UK
- Department of Zoology, University of Oxford, South Parks Rd, Oxford, OX1 3PS. UK
| | - Andrey Rudenko
- Harvard University, FAS Molecular & Cell Biology, Sherman Fairchild Biochemistry Bldg, 7 Divinity Ave, Cambridge MA, 02138, USA
- Department of Zoology, University of Oxford, South Parks Rd, Oxford, OX1 3PS. UK
| | - Luke Alphey
- Department of Zoology, University of Oxford, South Parks Rd, Oxford, OX1 3PS. UK
| | - Helen White-Cooper
- Department of Zoology, University of Oxford, South Parks Rd, Oxford, OX1 3PS. UK
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18
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Kirchner J, Gross S, Bennett D, Alphey L. Essential, overlapping and redundant roles of the Drosophila protein phosphatase 1 alpha and 1 beta genes. Genetics 2007; 176:273-81. [PMID: 17513890 PMCID: PMC1893066 DOI: 10.1534/genetics.106.069914] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Protein serine/threonine phosphatase type 1 (PP1) has been found in all eukaryotes examined to date and is involved in the regulation of many cellular functions, including glycogen metabolism, muscle contraction, and mitosis. In Drosophila, four genes code for the catalytic subunit of PP1 (PP1c), three of which belong to the PP1 alpha subtype. PP1 beta 9C (flapwing) encodes the fourth PP1c gene and has a specific and nonredundant function as a nonmuscle myosin phosphatase. PP1 alpha 87B is the major form and contributes approximately 80% of the total PP1 activity. We describe the first mutant alleles of PP1 alpha 96A and show that PP1 alpha 96A is not an essential gene, but seems to have a function in the regulation of nonmuscle myosin. We show that overexpression of the PP1 alpha isozymes does not rescue semilethal PP1 beta 9C mutants, whereas overexpression of either PP1 alpha 96A or PP1 beta 9C does rescue a lethal PP1 alpha 87B mutant combination, showing that the lethality is due to a quantitative reduction in the level of PP1c. Overexpression of PP1 beta 9C does not rescue a PP1 alpha 87B, PP1 alpha 96A double mutant, suggesting an essential PP1 alpha-specific function in Drosophila.
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Affiliation(s)
- Jasmin Kirchner
- Department of Zoology, University of Oxford, Oxford, United Kingdom
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19
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Fang Y, Sathyanarayanan S, Sehgal A. Post-translational regulation of the Drosophila circadian clock requires protein phosphatase 1 (PP1). Genes Dev 2007; 21:1506-18. [PMID: 17575052 PMCID: PMC1891428 DOI: 10.1101/gad.1541607] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Phosphorylation is an important timekeeping mechanism in the circadian clock that has been closely studied at the level of the kinases involved but may also be tightly controlled by phosphatase action. Here we demonstrate a role for protein phosphatase 1 (PP1) in the regulation of the major timekeeping molecules in the Drosophila clock, TIMELESS (TIM) and PERIOD (PER). Flies with reduced PP1 activity exhibit a lengthened circadian period, reduced amplitude of behavioral rhythms, and an altered response to light that suggests a defect in the rising phase of clock protein expression. On a molecular level, PP1 directly dephosphorylates TIM and stabilizes it in both S2R(+) cells and clock neurons. However, PP1 does not act in a simple antagonistic manner to SHAGGY (SGG), the kinase that phosphorylates TIM, because the behavioral phenotypes produced by inhibiting PP1 in flies are different from those achieved by overexpressing SGG. PP1 also acts on PER, and TIM regulates the control of PER by PP1, although it does not affect PP2A action on PER. We propose a modified model for post-translational regulation of the Drosophila clock, in which PP1 is critical for the rhythmic abundance of TIM/PER while PP2A also regulates the nuclear translocation of TIM/PER.
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Affiliation(s)
- Yanshan Fang
- Howard Hughes Medical Institute, Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | - Sriram Sathyanarayanan
- Howard Hughes Medical Institute, Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | - Amita Sehgal
- Howard Hughes Medical Institute, Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
- Corresponding author.E-MAIL ; FAX (215) 746-0232
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20
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Kirchner J, Gross S, Bennett D, Alphey L. The nonmuscle myosin phosphatase PP1beta (flapwing) negatively regulates Jun N-terminal kinase in wing imaginal discs of Drosophila. Genetics 2007; 175:1741-9. [PMID: 17277363 PMCID: PMC1855117 DOI: 10.1534/genetics.106.067488] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Drosophila flapwing (flw) codes for serine/threonine protein phosphatase type 1beta (PP1beta). Regulation of nonmuscle myosin activity is the single essential flw function that is nonredundant with the three closely related PP1alpha genes. Flw is thought to dephosphorylate the nonmuscle myosin regulatory light chain, Spaghetti Squash (Sqh); this inactivates the nonmuscle myosin heavy chain, Zipper (Zip). Thus, strong flw mutants lead to hyperphosphorylation of Sqh and hyperactivation of nonmuscle myosin activity. Here, we show genetically that a Jun N-terminal kinase (JNK) mutant suppresses the semilethality of a strong flw allele. Alleles of the JNK phosphatase puckered (puc) genetically enhance the weak allele flw1, leading to severe wing defects. Introducing a mutant of the nonmuscle myosin-binding subunit (Mbs) further enhances this genetic interaction to lethality. We show that puc expression is upregulated in wing imaginal discs mutant for flw1 and pucA251 and that this upregulation is modified by JNK and Zip. The level of phosphorylated (active) JNK is elevated in flw1 enhanced by puc. Together, we show that disruption of nonmuscle myosin activates JNK and puc expression in wing imaginal discs.
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Affiliation(s)
- Jasmin Kirchner
- Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom
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21
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Bennett D, Lyulcheva E, Alphey L, Hawcroft G. Towards a comprehensive analysis of the protein phosphatase 1 interactome in Drosophila. J Mol Biol 2006; 364:196-212. [PMID: 17007873 DOI: 10.1016/j.jmb.2006.08.094] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Revised: 08/22/2006] [Accepted: 08/31/2006] [Indexed: 11/25/2022]
Abstract
Protein phosphatase type 1 (PP1) is one of the major classes of serine/threonine protein phosphatases, and has been found in all eukaryotic cells examined to date. Metazoans from Drosophila to humans have multiple genes encoding catalytic subunits of PP1 (PP1c), which are involved in a wide range of biological processes. Different PP1c isoforms have pleiotropic and overlapping functions; this has complicated the analysis of their biological roles and the identification of specific in vivo substrates. PP1c isoforms are associated in vivo with regulatory subunits that target them to specific locations and modify their substrate specificity and activity. The PP1c-binding proteins are therefore the key to understanding the role of PP1 in particular biological processes. The existence of isoform specific PP1c-binding subunits may also help to explain the unique roles of different PP1c isoforms. Here we report the identification of 24 genes encoding Drosophila PP1c-binding proteins in the yeast two-hybrid system. Sequence analysis identified a minimal interacting fragment and putative PP1c-binding motif for each protein, delimiting the region involved in binding to PP1c. Further two-hybrid analysis showed that virtually all of the interactors were capable of binding all Drosophila PP1c isoforms. One of the novel interactors, CG1553, was examined further and shown to interact with multiple isoforms by co-immunoprecipitation from Drosophila extracts and functional interaction with PP1c isoforms in vivo. Bioinformatic analyses implicate the putative PP1c-associated subunits in a diverse array of intracellular processes. Our identification of a large number of PP1c-binding proteins with the potential for directing PP1c's specific functions in Drosophila represents a significant step towards a full understanding of the range of PP1 complexes and function in animals.
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Affiliation(s)
- Daimark Bennett
- Department of Zoology, Oxford University, South Parks Road, Oxford, OX1 3PS, UK.
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22
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Oguri T, Inoko A, Shima H, Izawa I, Arimura N, Yamaguchi T, Inagaki N, Kaibuchi K, Kikuchi K, Inagaki M. Vimentin-Ser82 as a memory phosphorylation site in astrocytes. Genes Cells 2006; 11:531-40. [PMID: 16629905 DOI: 10.1111/j.1365-2443.2006.00961.x] [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: 11/30/2022]
Abstract
In astrocytes, the PGF(2alpha) or ionomycin treatment induces the phosphorylation at Ser38 and Ser82 of vimentin, a type III intermediate filament, by Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). We found here that vimentin phospho-Ser82 was dephosphorylated much slower than phospho-Ser38. Vimentin phospho-Ser38 was dephosphorylated quickly by purified PP1 catalytic subunit (PP1c) in vitro, whereas phospho-Ser82 was insensitive to PP1c. Because PP1c directly bound to vimentin through a VxF motif (Val83-Asp84-Phe85), the PP1c active site appeared to be unable to approach phospho-Ser82, leading to the prolongation of the phosphorylation at Ser-82. In astrocytes, PP1calpha was in vivo associated with vimentin filaments. The repetitive treatment by ionomycin at a short interval resulted in the sustained elevation of Ser82 phosphorylation, leading to the marked disassembly of vimentin filaments. Taken together, these results suggest that vimentin is a novel member of binding partner of PP1c in astrocytes, and vimentin-Ser82 may act as a memory phosphorylation site.
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Affiliation(s)
- Takashi Oguri
- Division of Biochemistry, Aichi Cancer Center Research Institute, Nagoya 464-8681, Japan
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23
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Montana ES, Littleton JT. Expression profiling of a hypercontraction-induced myopathy in Drosophila suggests a compensatory cytoskeletal remodeling response. J Biol Chem 2006; 281:8100-9. [PMID: 16415344 DOI: 10.1074/jbc.m512468200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mutations that alter muscle contraction lead to a large array of diseases, including muscular dystrophies and cardiomyopathies. Although the molecular lesions underlying many hereditary muscle diseases are known, the downstream pathways that contribute to disease pathogenesis and compensatory muscle remodeling are poorly defined. We have recently identified and characterized mutations in Myosin Heavy Chain (Mhc) that lead to hypercontraction and subsequent degeneration of flight muscles in Drosophila. To characterize the genomic response to hypercontraction-induced myopathy, we performed expression analysis using Affymetrix high density oligonucleotide microarrays in Drosophila Mhc hypercontraction alleles. The altered transcriptional profile of dystrophic Mhc muscles suggests an actin-dependent remodeling of the muscle cytoskeleton. Specifically, a subset of the highly up-regulated transcripts is involved in actin regulation and structural support for the contractile machinery. In addition, we identified previously uncharacterized proteins with putative actin-interaction domains that are up-regulated in Mhc mutants and differentially expressed in muscles. Several of the up-regulated proteins, including the dystrophin-related protein, MSP-300, and the homolog of the neuronal activity-regulated protein, ARC, localize to specific subcellular muscle structures that may provide key structural sites for cytoskeletal remodeling in dystrophic muscles. Defining the genome-wide transcriptional response to muscle hypercontraction in Drosophila has revealed candidate loci that may participate in the pathogenesis of muscular dystrophy and in compensatory muscle repair pathways through modulation of the actin cytoskeleton.
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Affiliation(s)
- Enrico S Montana
- Department of Biology, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge 02139, USA
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24
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Babu K, Bahri S, Alphey L, Chia W. Bifocal and PP1 interaction regulates targeting of the R-cell growth cone in Drosophila. Dev Biol 2005; 288:372-86. [PMID: 16280124 DOI: 10.1016/j.ydbio.2005.09.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2005] [Revised: 09/07/2005] [Accepted: 09/10/2005] [Indexed: 11/24/2022]
Abstract
Bifocal is a putative cytoskeletal regulator and a Protein phosphatase-1 (PP1) interacting protein that mediates normal photoreceptor morphology in Drosophila. We show here that Bif and PP1-87B as well as their ability to interact with each other are required for photoreceptor growth cone targeting in the larval visual system. Single mutants for bif or PP1-87B show defects in axonal projections in which the axons of the outer photoreceptors bypass the lamina, where they normally terminate. The data show that the functions of bif and PP1-87B in either stabilizing R-cell morphology (for Bif) or regulating the cell cycle (for PP1-87B) can be uncoupled from their function in visual axon targeting. Interestingly, the axon targeting phenotypes are observed in both PP1-87B mutants and PP1-87B overexpression studies, suggesting that an optimal PP1 activity may be required for normal axon targeting. bif mutants also display strong genetic interactions with receptor tyrosine phosphatases, dptp10d and dptp69d, and biochemical studies demonstrate that Bif interacts directly with F-actin in vitro. We propose that, as a downstream component of axon signaling pathways, Bif regulates PP1 activity, and both proteins influence cytoskeleton dynamics in the growth cone of R cells to allow proper axon targeting.
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Affiliation(s)
- Kavita Babu
- Temasek Life Science Laboratory and Department of Biological Sciences, 1 Research Link, National University of Singapore, 117604, Singapore.
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Rudenko A, Bennett D, Alphey L. PP1beta9C interacts with Trithorax in Drosophila wing development. Dev Dyn 2005; 231:336-41. [PMID: 15366010 DOI: 10.1002/dvdy.20146] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Type 1 Ser/Thr protein phosphatase (PP1) has many roles in Drosophila: regulating diverse processes from chromatin condensation to transforming growth factor-beta signaling. The presence of four PP1 genes, PP1alpha87B, PP1beta9C, PP1alpha96A, and PP1alpha13C, encoding very similar proteins complicates analysis of their particular functions. Here, we report that the minor PP1 isoform PP1beta9C binds in vitro and in vivo and genetically interacts with Trithorax (TRX), the archetypal member of the Trx-G family of epigenetic regulators in Drosophila. Direct binding was demonstrated by GST pull-down experiments and PP1beta9C/TRX interaction in vivo was confirmed by coimmune precipitation from Drosophila embryonic extracts. PP1beta9C was found to be present at all TRX sites on the polytene chromosomes. Flies homo- and hemizygous for loss-of-function alleles of PP1beta9C exhibited specific wing defects when combined with various trx mutants, which indicates that PP1beta9C and TRX cooperate in Drosophila wing development.
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Affiliation(s)
- Andrey Rudenko
- Department of Zoology, Oxford University, South Parks Road, Oxford, United Kingdom
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26
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Hormi-Carver KK, Shi W, Liu CWY, Berndt N. Protein phosphatase 1alpha is required for murine lung growth and morphogenesis. Dev Dyn 2004; 229:791-801. [PMID: 15042703 DOI: 10.1002/dvdy.10497] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein phosphatase 1 (PP1) plays important roles in cell cycle control and apoptosis, two processes that impinge on morphogenesis and differentiation. Following the precedent set by other molecules regulating the cell cycle and apoptosis, we hypothesized that PP1 may have context-specific roles in development. Therefore, we have studied the spatial and temporal expression of PP1alpha during murine lung development and determined the consequences of loss of PP1alpha function on branching morphogenesis. By using an immunohistochemical approach, we show here that PP1alpha was expressed throughout the epithelium and mesenchyme upon the emergence of the lung primordium on embryonic day 10, with immunostaining exclusively extranuclear. During the late pseudoglandular stage, PP1alpha was predominantly expressed in the distal lung epithelium, whereas the mesenchyme contained very little or no PP1alpha protein. Peri- and postnatally, PP1alpha immunostaining was mostly nuclear in apparently differentiated cells, as judged by colocalization with well-known markers for lung differentiation. Exposure of fetal lung explants to antisense oligodeoxynucleotides against PP1alpha, resulted in decreased overall size of the cultured lung, a defect in forming new airways, lack of expression of surfactant protein C, and histologic signs of poor differentiation. These data suggest that PP1alpha is required for branching morphogenesis and differentiation.
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Affiliation(s)
- Kadija-Kathy Hormi-Carver
- Division of Hematology/Oncology, Department of Pediatrics, Childrens Hospital Los Angeles, University of Southern California School of Medicine, Los Angeles, California, USA
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27
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Soustelle L, Jacques C, Altenhein B, Technau GM, Volk T, Giangrande A. Terminal tendon cell differentiation requires the glide/gcm complex. Development 2004; 131:4521-32. [PMID: 15342477 DOI: 10.1242/dev.01290] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Locomotion relies on stable attachment of muscle fibres to their target sites, a process that allows for muscle contraction to generate movement. Here, we show that glide/gcm and glide2/gcm2, the fly glial cell determinants, are expressed in a subpopulation of embryonic tendon cells and required for their terminal differentiation. By using loss-of-function approaches, we show that in the absence of both genes, muscle attachment to tendon cells is altered, even though the molecular cascade induced by stripe, the tendon cell determinant, is normal. Moreover, we show that glide/gcm activates a new tendon cell gene independently of stripe. Finally, we show that segment polarity genes control the epidermal expression of glide/gcm and determine, within the segment,whether it induces glial or tendon cell-specific markers. Thus, under the control of positional cues, glide/gcm triggers a new molecular pathway involved in terminal tendon cell differentiation, which allows the establishment of functional muscle attachment sites and locomotion.
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Affiliation(s)
- Laurent Soustelle
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, BP 10142, 67404 Illkirch Cedex, C.U. de Strasbourg, France
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28
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Vereshchagina N, Bennett D, Szöor B, Kirchner J, Gross S, Vissi E, White-Cooper H, Alphey L. The essential role of PP1beta in Drosophila is to regulate nonmuscle myosin. Mol Biol Cell 2004; 15:4395-405. [PMID: 15269282 PMCID: PMC519135 DOI: 10.1091/mbc.e04-02-0139] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Reversible phosphorylation of myosin regulatory light chain (MRLC) is a key regulatory mechanism controlling myosin activity and thus regulating the actin/myosin cytoskeleton. We show that Drosophila PP1beta, a specific isoform of serine/threonine protein phosphatase 1 (PP1), regulates nonmuscle myosin and that this is the essential role of PP1beta. Loss of PP1beta leads to increased levels of phosphorylated nonmuscle MRLC (Sqh) and actin disorganisation; these phenotypes can be suppressed by reducing the amount of active myosin. Drosophila has two nonmuscle myosin targeting subunits, one of which (MYPT-75D) resembles MYPT3, binds specifically to PP1beta, and activates PP1beta's Sqh phosphatase activity. Expression of a mutant form of MYPT-75D that is unable to bind PP1 results in elevation of Sqh phosphorylation in vivo and leads to phenotypes that can also be suppressed by reducing the amount of active myosin. The similarity between fly and human PP1beta and MYPT genes suggests this role may be conserved.
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29
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Anholt RRH, Dilda CL, Chang S, Fanara JJ, Kulkarni NH, Ganguly I, Rollmann SM, Kamdar KP, Mackay TFC. The genetic architecture of odor-guided behavior in Drosophila: epistasis and the transcriptome. Nat Genet 2003; 35:180-4. [PMID: 12958599 DOI: 10.1038/ng1240] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2003] [Accepted: 08/25/2003] [Indexed: 11/09/2022]
Abstract
We combined transcriptional profiling and quantitative genetic analysis to elucidate the genetic architecture of olfactory behavior in Drosophila melanogaster. We applied whole-genome expression analysis to five coisogenic smell-impaired (smi) mutant lines and their control. We used analysis of variance to partition variation in transcript abundance between males and females and between smi genotypes and to determine the genotype-by-sex interaction. A total of 666 genes showed sexual dimorphism in transcript abundance, and 530 genes were coregulated in response to one or more smi mutations, showing considerable epistasis at the level of the transcriptome in response to single mutations. Quantitative complementation tests of mutations at these coregulated genes with the smi mutations showed that in most cases (67%) epistatic interactions for olfactory behavior mirrored epistasis at the level of transcription, thus identifying new candidate genes regulating olfactory behavior.
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Affiliation(s)
- Robert R H Anholt
- The Department of Zoology, North Carolina State University, Raleigh, North Carolina 27695, USA.
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30
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Andrioli LPM, Zaini PA, Viviani W, Da Silva AM. Dictyostelium discoideum protein phosphatase-1 catalytic subunit exhibits distinct biochemical properties. Biochem J 2003; 373:703-11. [PMID: 12737629 PMCID: PMC1223547 DOI: 10.1042/bj20021964] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2002] [Revised: 04/29/2003] [Accepted: 05/09/2003] [Indexed: 01/04/2023]
Abstract
Protein phosphatase-1 (PP1) is expressed ubiquitously and is involved in many eukaryotic cellular functions, although PP1 enzyme activity could not be detected in the social amoeba Dictyostelium discoideum cell extracts. In the present paper, we show that D. discoideum has a single copy gene that codes for the catalytic subunit of PP1 (DdPP1c). DdPP1c is expressed throughout the D. discoideum life cycle with constant levels of mRNA, and its protein and amino acid sequence show a mean identity of 80% with other PP1c enzymes. However, it has a distinctive difference: the substitution of a phenylalanine residue (Phe(269) in the DdPP1c) for a highly conserved cysteine residue (Cys(273) in rabbit PP1c) in a region that was shown to have a critical role in the interaction of rabbit PP1c with toxin inhibitors. Wild-type DdPP1c and an engineered mutant form in which Phe(269) was replaced by a cysteine residue were expressed in Escherichia coli. Both recombinant activities were similarly inhibited by okadaic acid, tautomycin and microcystin. However, the Phe(269)-->Cys mutation resulted in a large increase in enzyme activity towards phosphorylase a and a higher sensitivity to calyculin A. These results, together with the molecular modelling of DdPP1c structure, indicate that the Phe(269) residue, which occurs naturally in D. discoideum, confers distinct biochemical properties on this enzyme.
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Affiliation(s)
- Luiz P M Andrioli
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Avenida Professor Lineu Prestes 748, 05508-900, São Paulo, SP, Brazil
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31
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Bennett D, Szöor B, Gross S, Vereshchagina N, Alphey L. Ectopic expression of inhibitors of protein phosphatase type 1 (PP1) can be used to analyze roles of PP1 in Drosophila development. Genetics 2003; 164:235-45. [PMID: 12750335 PMCID: PMC1462544 DOI: 10.1093/genetics/164.1.235] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We have identified two proteins that bind with high specificity to type 1 serine/threonine protein phosphatase (PP1) and have exploited their inhibitory properties to develop an efficient and flexible strategy for conditional inactivation of PP1 in vivo. We show that modest overexpression of Drosophila homologs of I-2 and NIPP1 (I-2Dm and NIPP1Dm) reduces the level of PP1 activity and phenotypically resembles known PP1 mutants. These phenotypes, which include lethality, abnormal mitotic figures, and defects in muscle development, are suppressed by coexpression of PP1, indicating that the effect is due specifically to loss of PP1 activity. Reactivation of I-2Dm:PP1c complexes suggests that inhibition of PP1 activity in vivo does not result in a compensating increase in synthesis of active PP1. PP1 mutants enhance the wing overgrowth phenotype caused by ectopic expression of the type II TGF beta superfamily signaling receptor Punt. Using I-2Dm, which has a less severe effect than NIPP1Dm, we show that lowering the level of PP1 activity specifically in cells overexpressing Punt is sufficient for wing overgrowth and that the interaction between PP1 and Punt requires the type I receptor Thick-veins (Tkv) but is not strongly sensitive to the level of the ligand, Decapentaplegic (Dpp), nor to that of the other type I receptors. This is consistent with a role for PP1 in antagonizing Punt by preventing phosphorylation of Tkv. These studies demonstrate that inhibitors of PP1 can be used in a tissue- and developmental-specific manner to examine the developmental roles of PP1.
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Affiliation(s)
- Daimark Bennett
- Department of Zoology, Oxford University, Oxford OX1 3PS, United Kingdom
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Bennett D, Alphey L. PP1 binds Sara and negatively regulates Dpp signaling in Drosophila melanogaster. Nat Genet 2002; 31:419-23. [PMID: 12134149 DOI: 10.1038/ng938] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In signaling involving the transforming growth factor-beta (TGF-beta) superfamily of proteins, ligand binding brings the constitutively active type II receptor kinase into close proximity to its substrate, the type I receptor kinase, which it then activates by phosphorylation. The type I receptor kinase in turn phosphorylates one of the Smad family of transcription factors, which translocates to the nucleus and regulates gene expression. Smads are recruited to the receptor complex by an anchor protein, SARA (Smad anchor for receptor activation). Although several protein kinases in this pathway were known, including the receptors themselves, the relevant phosphatases had not previously been identified. Here we report the isolation of a Drosophila melanogaster homolog of SARA (Sara) in a screen for proteins that bind the catalytic subunit of type 1 serine/threonine protein phosphatase (PP1c). We identified a PP1c-binding motif in Sara, disruption of which reduced the ability of Sara to bind PP1c. Expression of this non-PP1c-binding mutant resulted in hyperphosphorylation of the type I receptor and stimulated expression of a target of TGF-beta signaling. Reducing PP1c activity enhanced the increase in the basal level of expression of genes responsive to Dpp (Decapentaplegic) caused by ectopic expression of the type II receptor Punt. Together these data suggest that PP1c is targeted to Dpp receptor complexes by Sara, where it acts as a negative regulator of Dpp signaling by affecting the phosphorylation state of the type I receptor.
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Affiliation(s)
- Daimark Bennett
- Department of Zoology, Oxford University, South Parks Road, Oxford OX1 3PS, UK
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33
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Ceulemans H, Stalmans W, Bollen M. Regulator-driven functional diversification of protein phosphatase-1 in eukaryotic evolution. Bioessays 2002; 24:371-81. [PMID: 11948623 DOI: 10.1002/bies.10069] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We have used the (nearly) completed eukaryotic genome sequences to trace the evolution of thirteen families of established vertebrate regulators of type-1 protein phosphatases (PP1). Two of these families are present in all lineages of the eukaryotic crown and therefore qualify as candidate primordial regulators that determined the surface of PP1. The set of regulators of PP1 has continued to expand ever since, often in response to functional innovations in different eukaryotic lineages. In particular, the development of metazoan multicellularity was accompanied by an explosive increase in the number of regulators of PP1. The further increase in the functional diversity of PP1 in the vertebrate lineage was mainly achieved by the duplication of genes for regulatory subunits and by the conversion of already existing proteins into regulators of PP1. Unexpectedly, our analysis has also enabled us to classify nine poorly characterized proteins as likely regulators of PP1.
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Affiliation(s)
- Hugo Ceulemans
- Afdeling Biochemie, Katholieke Universiteit Leuven, Belgium.
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34
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Abstract
Protein phosphatase 1 (PP1) is a major eukaryotic protein serine/threonine phosphatase that regulates an enormous variety of cellular functions through the interaction of its catalytic subunit (PP1c) with over fifty different established or putative regulatory subunits. Most of these target PP1c to specific subcellular locations and interact with a small hydrophobic groove on the surface of PP1c through a short conserved binding motif – the RVxF motif – which is often preceded by further basic residues. Weaker interactions may subsequently enhance binding and modulate PP1 activity/specificity in a variety of ways. Several putative targeting subunits do not possess an RVxF motif but nevertheless interact with the same region of PP1c. In addition, several ‘modulator’ proteins bind to PP1c but do not possess a domain targeting them to a specific location. Most are potent inhibitors of PP1c and possess at least two sites for interaction with PP1c, one of which is identical or similar to the RVxF motif.Regulation of PP1c in response to extracellular and intracellular signals occurs mostly through changes in the levels, conformation or phosphorylation status of targeting subunits. Understanding of the mode of action of PP1c complexes may facilitate development of drugs that target particular PP1c complexes and thereby modulate the phosphorylation state of a very limited subset of proteins.
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Affiliation(s)
- Patricia T W Cohen
- Medical Research Council Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee DD15EH, Scotland, UK.
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35
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Szöor B, Gross S, Alphey L. Biochemical characterization of recombinant Drosophila type 1 serine/threonine protein phosphatase (PP1c) produced in Pichia pastoris. Arch Biochem Biophys 2001; 396:213-8. [PMID: 11747299 DOI: 10.1006/abbi.2001.2602] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The methylotrophic yeast Pichia pastoris was used to express Drosophila melanogaster type 1beta serine/threonine phosphoprotein phosphatase catalytic subunit (PP1beta9C). A construct encoding PP1beta9C with a short NH(2)-terminal fusion including six histidine residues was introduced into the X-33 and KM71H strains of P. pastoris by homologous recombination. Recombinant protein was purified from cell free extracts 24 h after methanol induction. PP1beta9C was purified to a specific activity of 12,077 mU/mg by a three-step purification method comprising (NH(4))(2)SO(4)-ethanol precipitation followed by Ni(2+)-agarose affinity chromatography and Mono Q anion-exchange chromatography. This purification scheme yielded approximately 80 microg of active, soluble PP1beta9C per 1 L of culture. In contrast to recombinant PP1beta9C overexpressed in bacteria, which differs from native PP1c in several biochemical criteria including the requirement for divalent cations, sensitivity to vanadate, and p-nitrophenyl phosphate (pNPP) phosphatase activity, recombinant PP1beta9C produced in P. pastoris has native-like properties. P. pastoris thus provides a reliable and convenient system for the production of active, native-like recombinant PP1beta9C.
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Affiliation(s)
- B Szöor
- Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, United Kingdom
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36
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Abstract
The catalytic subunit of the type 1 Ser/Thr protein phosphatases (PP1) can interact with many different regulatory (R) subunits. These R subunits function as activity-modulators, targeting subunits and/or substrates. The specificity of the R subunits can be accounted for by their interaction with specific subsets of binding pockets on the catalytic subunit and by the presence of subcellular targeting sequences. Hormones, growth factors and metabolites control the function of PP1 holoenzymes mainly by modulating the interaction of the subunits.
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Affiliation(s)
- M Bollen
- Afdeling Biochemie, Faculteit Geneeskunde, Katholieke Universiteit Leuven, B-3000, Leuven, Belgium.
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37
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Helps NR, Cohen PT, Bahri SM, Chia W, Babu K. Interaction with protein phosphatase 1 Is essential for bifocal function during the morphogenesis of the Drosophila compound eye. Mol Cell Biol 2001; 21:2154-64. [PMID: 11238949 PMCID: PMC86841 DOI: 10.1128/mcb.21.6.2154-2164.2001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The gene bifocal (bif), required for photoreceptor morphogenesis in the Drosophila compound eye, encodes a protein that is shown to interact with protein phosphatase 1 (PP1) using the yeast two-hybrid system. Complex formation between Bif and PP1 is supported by coprecipitation of the two proteins. Residues 992 to 995 (RVQF) in the carboxy-terminal region of Bif, which conform to the consensus PP1-binding motif, are shown to be essential for the interaction of Bif with PP1. The interaction of PP1 with bacterially expressed and endogenous Bif can be disrupted by a synthetic peptide known to block interaction of other regulatory subunits with PP1. Null bif mutants exhibit a rough eye phenotype, disorganized rhabdomeres (light-gathering rhodopsin-rich microvillar membrane structures in the photoreceptor cells) and alterations in the actin cytoskeleton. Expression of wild-type bif transgenes resulted in significant rescue of these abnormalities. In contrast, expression of transgenes encoding the Bif F995A mutant, which disrupts binding to PP1, was unable to rescue any aspect of the bif phenotype. The results indicate that the PP1-Bif interaction is critical for the rescue and that a major function of Bif is to target PP1c to a specific subcellular location. The role of the PP1-Bif complex in modulating the organization of the actin cytoskeleton underlying the rhabdomeres is discussed.
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Affiliation(s)
- N R Helps
- Medical Research Council Protein Phosphorylation Unit, Department of Biochemistry, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
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