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Toraason E, Adler VL, Libuda DE. Aging and sperm signals alter DNA break formation and repair in the C. elegans germline. PLoS Genet 2022; 18:e1010282. [PMID: 36342909 PMCID: PMC9671421 DOI: 10.1371/journal.pgen.1010282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 11/17/2022] [Accepted: 10/21/2022] [Indexed: 11/09/2022] Open
Abstract
Female reproductive aging is associated with decreased oocyte quality and fertility. The nematode Caenorhabditis elegans is a powerful system for understanding the biology of aging and exhibits age-related reproductive defects that are analogous to those observed in many mammals, including dysregulation of DNA repair. C. elegans germline function is influenced simultaneously by both reproductive aging and signals triggered by limited supplies of sperm, which are depleted over chronological time. To delineate the causes of DNA repair defects in aged C. elegans germlines, we assessed both DNA double strand break (DSB) induction and repair during meiotic prophase I progression in aged germlines which were depleted of self-sperm, mated, or never exposed to sperm. We find that germline DSB induction is dramatically reduced only in hermaphrodites which have exhausted their endogenous sperm, suggesting that a signal due specifically to sperm depletion downregulates DSB formation. We also find that DSB repair is delayed in aged germlines regardless of whether hermaphrodites had either a reduction in sperm supply or an inability to endogenously produce sperm. These results demonstrate that in contrast to DSB induction, DSB repair defects are a feature of C. elegans reproductive aging independent of sperm presence. Finally, we demonstrate that the E2 ubiquitin-conjugating enzyme variant UEV-2 is required for efficient DSB repair specifically in young germlines, implicating UEV-2 in the regulation of DNA repair during reproductive aging. In summary, our study demonstrates that DNA repair defects are a feature of C. elegans reproductive aging and uncovers parallel mechanisms regulating efficient DSB formation in the germline.
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Affiliation(s)
- Erik Toraason
- University of Oregon, Department of Biology, Institute of Molecular Biology, Eugene, Oregon, United States of America
| | - Victoria L. Adler
- University of Oregon, Department of Biology, Institute of Molecular Biology, Eugene, Oregon, United States of America
| | - Diana E. Libuda
- University of Oregon, Department of Biology, Institute of Molecular Biology, Eugene, Oregon, United States of America
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Maneekesorn S, Knuepfer E, Green JL, Prommana P, Uthaipibull C, Srichairatanakool S, Holder AA. Deletion of Plasmodium falciparum ubc13 increases parasite sensitivity to the mutagen, methyl methanesulfonate and dihydroartemisinin. Sci Rep 2021; 11:21791. [PMID: 34750454 PMCID: PMC8575778 DOI: 10.1038/s41598-021-01267-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 10/18/2021] [Indexed: 12/18/2022] Open
Abstract
The inducible Di-Cre system was used to delete the putative ubiquitin-conjugating enzyme 13 gene (ubc13) of Plasmodium falciparum to study its role in ubiquitylation and the functional consequence during the parasite asexual blood stage. Deletion resulted in a significant reduction of parasite growth in vitro, reduced ubiquitylation of the Lys63 residue of ubiquitin attached to protein substrates, and an increased sensitivity of the parasite to both the mutagen, methyl methanesulfonate and the antimalarial drug dihydroartemisinin (DHA), but not chloroquine. The parasite was also sensitive to the UBC13 inhibitor NSC697923. The data suggest that this gene does code for an ubiquitin conjugating enzyme responsible for K63 ubiquitylation, which is important in DNA repair pathways as was previously demonstrated in other organisms. The increased parasite sensitivity to DHA in the absence of ubc13 function indicates that DHA may act primarily through this pathway and that inhibitors of UBC13 may both enhance the efficacy of this antimalarial drug and directly inhibit parasite growth.
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Affiliation(s)
- Supawadee Maneekesorn
- Department of Biochemistry, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
- Malaria Parasitology Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Ellen Knuepfer
- Malaria Parasitology Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
- Molecular and Cellular Parasitology Laboratory, Department of Pathobiology and Population Sciences, The Royal Veterinary College, Hawkshead Lane, Hatfield, AL9 7TA, UK
| | - Judith L Green
- Malaria Parasitology Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Parichat Prommana
- Medical Molecular Biotechnology Research Group, National Center for Genetic Engineering and Biotechnology (BIOTEC), 113 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, 12120, Pathum Thani, Thailand
| | - Chairat Uthaipibull
- Medical Molecular Biotechnology Research Group, National Center for Genetic Engineering and Biotechnology (BIOTEC), 113 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, 12120, Pathum Thani, Thailand
- Thailand Center of Excellence for Life Sciences (TCELS), Phayathai, 10400, Bangkok, Thailand
| | - Somdet Srichairatanakool
- Department of Biochemistry, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Anthony A Holder
- Malaria Parasitology Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.
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Novel Tsg101 Binding Partners Regulate Viral L Domain Trafficking. Viruses 2021; 13:v13061147. [PMID: 34203832 PMCID: PMC8232796 DOI: 10.3390/v13061147] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/07/2021] [Accepted: 06/09/2021] [Indexed: 02/06/2023] Open
Abstract
Two decades ago, Tsg101, a component of the Endosomal Sorting Complexes Required for Transport (ESCRT) complex 1, was identified as a cellular factor recruited by the human immunodeficiency virus type 1 (HIV-1) to facilitate budding of viral particles assembled at the cell periphery. A highly conserved Pro-(Thr/Ser)-Ala-Pro [P(T/S)AP] motif in the HIV-1 structural polyprotein, Gag, engages a P(T/S)AP-binding pocket in the Tsg101 N-terminal domain. Since the same domain in Tsg101 that houses the pocket was found to bind mono-ubiquitin (Ub) non-covalently, Ub binding was speculated to enhance P(T/S)AP interaction. Within the past five years, we found that the Ub-binding site also accommodates di-Ub, with Lys63-linked di-Ub exhibiting the highest affinity. We also identified small molecules capable of disrupting Ub binding and inhibiting budding. The structural similarity of these molecules, prazoles, to nucleosides prompted testing for nucleic acid binding and led to identification of tRNA as a Tsg101 binding partner. Here, we discuss these recently identified interactions and their contribution to the viral assembly process. These new partners may provide additional insight into the control and function of Tsg101 as well as identify opportunities for anti-viral drug design.
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DLK-1/p38 MAP Kinase Signaling Controls Cilium Length by Regulating RAB-5 Mediated Endocytosis in Caenorhabditis elegans. PLoS Genet 2015; 11:e1005733. [PMID: 26657059 PMCID: PMC4686109 DOI: 10.1371/journal.pgen.1005733] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 11/19/2015] [Indexed: 01/11/2023] Open
Abstract
Cilia are sensory organelles present on almost all vertebrate cells. Cilium length is constant, but varies between cell types, indicating that cilium length is regulated. How this is achieved is unclear, but protein transport in cilia (intraflagellar transport, IFT) plays an important role. Several studies indicate that cilium length and function can be modulated by environmental cues. As a model, we study a C. elegans mutant that carries a dominant active G protein α subunit (gpa-3QL), resulting in altered IFT and short cilia. In a screen for suppressors of the gpa-3QL short cilium phenotype, we identified uev-3, which encodes an E2 ubiquitin-conjugating enzyme variant that acts in a MAP kinase pathway. Mutation of two other components of this pathway, dual leucine zipper-bearing MAPKKK DLK-1 and p38 MAPK PMK-3, also suppress the gpa-3QL short cilium phenotype. However, this suppression seems not to be caused by changes in IFT. The DLK-1/p38 pathway regulates several processes, including microtubule stability and endocytosis. We found that reducing endocytosis by mutating rabx-5 or rme-6, RAB-5 GEFs, or the clathrin heavy chain, suppresses gpa-3QL. In addition, gpa-3QL animals showed reduced levels of two GFP-tagged proteins involved in endocytosis, RAB-5 and DPY-23, whereas pmk-3 mutant animals showed accumulation of GFP-tagged RAB-5. Together our results reveal a new role for the DLK-1/p38 MAPK pathway in control of cilium length by regulating RAB-5 mediated endocytosis. Cells detect cues in their environment using many different receptor and channel proteins, most of which localize to the plasma membrane of the cell. Some of these receptors and channels localize to a specialized sensory organelle, the primary cilium, that extends from the cell like a small antenna. Almost all cells of the human body have one or more cilia. Defects in cilium structure or function have been implicated in many diseases. Many studies have shown that the length of cilia is regulated and can be modulated by environmental signals. Several genes have been identified that function in cilium length regulation and it is clear that transport of proteins inside the cilium plays an important role. Here, we identify several genes of a MAP kinase cascade that modulate the length of cilia of the nematode Caenorhabditis elegans. Interestingly, this regulation seems not to be mediated by the transport system in the cilia, but by modulation of endocytosis. Our results suggest that regulated delivery and removal of proteins and/or lipids at the base of the cilium contributes to the regulation of cilium length.
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Skibinski GA, Boyd L. Ubiquitination is involved in secondary growth, not initial formation of polyglutamine protein aggregates in C. elegans. BMC Cell Biol 2012; 13:10. [PMID: 22494772 PMCID: PMC3368771 DOI: 10.1186/1471-2121-13-10] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Accepted: 04/11/2012] [Indexed: 11/13/2022] Open
Abstract
Background Protein misfolding and subsequent aggregation are hallmarks of several human diseases. The cell has a variety of mechanisms for coping with misfolded protein stress, including ubiquitin-mediated protein degradation. In fact, the presence of ubiquitin at protein aggregates is a common feature of protein misfolding diseases. Ubiquitin conjugating enzymes (UBCs) are part of the cascade of enzymes responsible for the regulated attachment of ubiquitin to protein substrates. The specific UBC used during ubiquitination can determine the type of polyubiquitin chain linkage, which in turn plays an important role in determining the fate of the ubiquitinated protein. Thus, UBCs may serve an important role in the cellular response to misfolded proteins and the fate of protein aggregates. Results The Q82 strain of C. elegans harbors a transgene encoding an aggregation prone tract of 82 glutamine residues fused to green fluorescent protein (Q82::GFP) that is expressed in the body wall muscle. When measured with time-lapse microscopy in young larvae, the initial formation of individual Q82::GFP aggregates occurs in approximately 58 minutes. This process is largely unaffected by a mutation in the C. elegans E1 ubiquitin activating enzyme. RNAi of ubc-22, a nematode homolog of E2-25K, resulted in higher pre-aggregation levels of Q82::GFP and a faster initial aggregation rate relative to control. Knockdown of ubc-1 (RAD6 homolog), ubc-13, and uev-1 did not affect the kinetics of initial aggregation. However, RNAi of ubc-13 decreases the rate of secondary growth of the aggregate. This result is consistent with previous findings that aggregates in young adult worms are smaller after ubc-13 RNAi. mCherry::ubiquitin becomes localized to Q82::GFP aggregates during the fourth larval (L4) stage of life, a time point long after most aggregates have formed. FLIP and FRAP analysis indicate that mCherry::ubiquitin is considerably more mobile than Q82::GFP within aggregates. Conclusions These data indicate that initial formation of Q82::GFP aggregates in C. elegans is not directly dependent on ubiquitination, but is more likely a spontaneous process driven by biophysical properties in the cytosol such as the concentration of the aggregating species. The effect of ubiquitination appears to be most significant in later, secondary aggregate growth.
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Affiliation(s)
- Gregory A Skibinski
- Department of Biological Sciences, University of Alabama in Huntsville, Huntsville AL 35899, USA.
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Kramer LB, Shim J, Previtera ML, Isack NR, Lee MC, Firestein BL, Rongo C. UEV-1 is an ubiquitin-conjugating enzyme variant that regulates glutamate receptor trafficking in C. elegans neurons. PLoS One 2010; 5:e14291. [PMID: 21179194 PMCID: PMC3001443 DOI: 10.1371/journal.pone.0014291] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Accepted: 11/18/2010] [Indexed: 11/18/2022] Open
Abstract
The regulation of AMPA-type glutamate receptor (AMPAR) membrane trafficking is a key mechanism by which neurons regulate synaptic strength and plasticity. AMPAR trafficking is modulated through a combination of receptor phosphorylation, ubiquitination, endocytosis, and recycling, yet the factors that mediate these processes are just beginning to be uncovered. Here we identify the ubiquitin-conjugating enzyme variant UEV-1 as a regulator of AMPAR trafficking in vivo. We identified mutations in uev-1 in a genetic screen for mutants with altered trafficking of the AMPAR subunit GLR-1 in C. elegans interneurons. Loss of uev-1 activity results in the accumulation of GLR-1 in elongated accretions in neuron cell bodies and along the ventral cord neurites. Mutants also have a corresponding behavioral defect--a decrease in spontaneous reversals in locomotion--consistent with diminished GLR-1 function. The localization of other synaptic proteins in uev-1-mutant interneurons appears normal, indicating that the GLR-1 trafficking defects are not due to gross deficiencies in synapse formation or overall protein trafficking. We provide evidence that GLR-1 accumulates at RAB-10-containing endosomes in uev-1 mutants, and that receptors arrive at these endosomes independent of clathrin-mediated endocytosis. UEV-1 homologs in other species bind to the ubiquitin-conjugating enzyme Ubc13 to create K63-linked polyubiquitin chains on substrate proteins. We find that whereas UEV-1 can interact with C. elegans UBC-13, global levels of K63-linked ubiquitination throughout nematodes appear to be unaffected in uev-1 mutants, even though UEV-1 is broadly expressed in most tissues. Nevertheless, ubc-13 mutants are similar in phenotype to uev-1 mutants, suggesting that the two proteins do work together to regulate GLR-1 trafficking. Our results suggest that UEV-1 could regulate a small subset of K63-linked ubiquitination events in nematodes, at least one of which is critical in regulating GLR-1 trafficking.
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Affiliation(s)
- Lawrence B Kramer
- The Waksman Institute, Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey, United States of America
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Trujillo G, Nakata K, Yan D, Maruyama IN, Jin Y. A ubiquitin E2 variant protein acts in axon termination and synaptogenesis in Caenorhabditis elegans. Genetics 2010; 186:135-45. [PMID: 20592265 PMCID: PMC2940282 DOI: 10.1534/genetics.110.117341] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Accepted: 06/19/2010] [Indexed: 11/18/2022] Open
Abstract
In the developing nervous system, cohorts of events regulate the precise patterning of axons and formation of synapses between presynaptic neurons and their targets. The conserved PHR proteins play important roles in many aspects of axon and synapse development from C. elegans to mammals. The PHR proteins act as E3 ubiquitin ligases for the dual-leucine-zipper-bearing MAP kinase kinase kinase (DLK MAPKKK) to regulate the signal transduction cascade. In C. elegans, loss-of-function of the PHR protein RPM-1 (Regulator of Presynaptic Morphology-1) results in fewer synapses, disorganized presynaptic architecture, and axon overextension. Inactivation of the DLK-1 pathway suppresses these defects. By characterizing additional genetic suppressors of rpm-1, we present here a new member of the DLK-1 pathway, UEV-3, an E2 ubiquitin-conjugating enzyme variant. We show that uev-3 acts cell autonomously in neurons, despite its ubiquitous expression. Our genetic epistasis analysis supports a conclusion that uev-3 acts downstream of the MAPKK mkk-4 and upstream of the MAPKAPK mak-2. UEV-3 can interact with the p38 MAPK PMK-3. We postulate that UEV-3 may provide additional specificity in the DLK-1 pathway by contributing to activation of PMK-3 or limiting the substrates accessible to PMK-3.
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Affiliation(s)
- Gloriana Trujillo
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, CA 92093 Information Processing Biology Unit, Okinawa Institute of Science and Technology, Onna-Son, Okinawa 904-0412, Japan and Howard Hughes Medical Institute, La Jolla, CA 92093
| | - Katsunori Nakata
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, CA 92093 Information Processing Biology Unit, Okinawa Institute of Science and Technology, Onna-Son, Okinawa 904-0412, Japan and Howard Hughes Medical Institute, La Jolla, CA 92093
| | - Dong Yan
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, CA 92093 Information Processing Biology Unit, Okinawa Institute of Science and Technology, Onna-Son, Okinawa 904-0412, Japan and Howard Hughes Medical Institute, La Jolla, CA 92093
| | - Ichi N. Maruyama
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, CA 92093 Information Processing Biology Unit, Okinawa Institute of Science and Technology, Onna-Son, Okinawa 904-0412, Japan and Howard Hughes Medical Institute, La Jolla, CA 92093
| | - Yishi Jin
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, CA 92093 Information Processing Biology Unit, Okinawa Institute of Science and Technology, Onna-Son, Okinawa 904-0412, Japan and Howard Hughes Medical Institute, La Jolla, CA 92093
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Hwang SY, Rose LS. Control of asymmetric cell division in early C. elegans embryogenesis: teaming-up translational repression and protein degradation. BMB Rep 2010; 43:69-78. [PMID: 20193124 DOI: 10.5483/bmbrep.2010.43.2.069] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Asymmetric cell division is a fundamental mechanism for the generation of body axes and cell diversity during early embryogenesis in many organisms. During intrinsically asymmetric divisions, an axis of polarity is established within the cell and the division plane is oriented to ensure the differential segregation of developmental determinants to the daughter cells. Studies in the nematode Caenorhabditis elegans have contributed greatly to our understanding of the regulatory mechanisms underlying cell polarity and asymmetric division. However, much remains to be elucidated about the molecular machinery controlling the spatiotemporal distribution of key components. In this review we discuss recent findings that reveal intricate interactions between translational control and targeted proteolysis. These two mechanisms of regulation serve to carefully modulate protein levels and reinforce asymmetries, or to eliminate proteins from certain cells.
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Affiliation(s)
- Sue-Yun Hwang
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
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Characterization of a Moniezia expansa ubiquitin-conjugating enzyme E2 cDNA. Mol Biol Rep 2009; 37:1585-90. [PMID: 19468864 DOI: 10.1007/s11033-009-9564-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Accepted: 05/01/2009] [Indexed: 10/20/2022]
Abstract
Ubiquitin and other ubiquitin-like proteins play important roles in post-translational modification. They are phylogenetically well-conserved in eukaryotes. Here we report a new ubiquitin-conjugating enzyme E2 cDNA, which containing a ubiquitin-conjugating enzyme UBCc-domain named UBE2AM. Its cDNA is 899 base pairs in length and contains an open reading frame from nucleotide 171 to 632 encoding 153 amino acids. The result of real time RT-PCR showed that UBEA2 M is expressed in most of M. expansa proglottides and over-expressed in the mature proglottides. Comparison of predicted UBE2AM with UBCc (protein) homologues/orthologous from other species revealed identities between species varying from 97.5 to 99.4% at the amino acid level. Phylogenetic analysis showed the UBE2AM is a member of the eukaryotic UBCc superfamily, which have diverged from a common ancestor and the gene is clustered in the same group with the ubiquitin-conjugating enzyme E2A-like protein from Taenia asiatica.
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Hyenne V, Desrosiers M, Labbé JC. C. elegans Brat homologs regulate PAR protein-dependent polarity and asymmetric cell division. Dev Biol 2008; 321:368-78. [PMID: 18652816 DOI: 10.1016/j.ydbio.2008.06.037] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2008] [Revised: 06/25/2008] [Accepted: 06/25/2008] [Indexed: 12/18/2022]
Abstract
The evolutionary conserved PAR proteins control polarization and asymmetric division in many organisms. Recent work in Caenorhabditis elegans demonstrated that nos-3 and fbf-1/2 can suppress par-2(it5ts) lethality, suggesting that they participate in cell polarity by regulating the function of the anterior PAR-3/PAR-6/PKC-3 proteins. In Drosophila embryos, Nanos and Pumilio are homologous to NOS-3 and FBF-1/2 respectively and control cell polarity by forming a complex with the tumor suppressor Brat to inhibit Hunchback mRNA translation. In this study, we investigated the possibility that Brat could control cell polarity and asymmetric cell division in C. elegans. We found that disrupting four of the five C. elegans Brat homologs (Cebrats) individually results in suppression of par-2(it5ts) lethality, indicating that these genes are involved in embryonic polarity. Two of the Cebrats, ncl-1 and nhl-2, partially restore the localization of PAR proteins at the cortex. While mutations in the four Cebrat genes do not severely impair polarity, they display polarity-associated defects. Surprisingly, these defects are absent from nos-3 mutants. Similarly, while nos-3 controls PAR-6 protein levels, this is not the case for any of the Cebrats. Our results, together with results from Drosophila, indicate that Brat family members function in generating cellular asymmetries and suggest that, in contrast to Drosophila embryos, the C. elegans homologs of Brat and Nanos could participate in embryonic polarity via distinct mechanisms.
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Affiliation(s)
- Vincent Hyenne
- Cell Division and Differentiation Laboratory, Institute of Research in Immunology and Cancer, Université de Montréal, C.P. 6128, Succ Centre-ville Montréal, QC Canada H3C 3J7.
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11
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O'Farrell F, Esfahani SS, Engström Y, Kylsten P. Regulation of the Drosophila lin-41 homologue dappled by let-7 reveals conservation of a regulatory mechanism within the LIN-41 subclade. Dev Dyn 2008; 237:196-208. [PMID: 18069688 DOI: 10.1002/dvdy.21396] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Drosophila Dappled (DPLD) is a member of the RBCC/TRIM superfamily, a protein family involved in numerous diverse processes such as developmental timing and asymmetric cell divisions. DPLD belongs to the LIN-41 subclade, several members of which are micro RNA (miRNA) regulated. We re-examined the LIN-41 subclade members and their relation to other RBCC/TRIMs and dpld paralogs, and identified a new Drosophila muscle specific RBCC/TRIM: Another B-Box Affiliate, ABBA. In silico predictions of candidate miRNA regulators of dpld identified let-7 as the strongest candidate. Overexpression of dpld led to abnormal eye development, indicating that strict regulation of dpld mRNA levels is crucial for normal eye development. This phenotype was sensitive to let-7 dosage, suggesting let-7 regulation of dpld in the eye disc. A cell-based assay verified let-7 miRNA down-regulation of dpld expression by means of its 3'-untranslated region. Thus, dpld seems also to be miRNA regulated, suggesting that miRNAs represent an ancient mechanism of LIN-41 regulation.
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Affiliation(s)
- Fergal O'Farrell
- Department of Natural Sciences, Södertörns Högskola, Huddinge, Sweden.
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12
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Ubiquitin conjugating enzymes participate in polyglutamine protein aggregation. BMC Cell Biol 2007; 8:32. [PMID: 17663792 PMCID: PMC1952058 DOI: 10.1186/1471-2121-8-32] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2006] [Accepted: 07/30/2007] [Indexed: 12/17/2022] Open
Abstract
Background Protein aggregation is a hallmark of several neurodegenerative diseases including Huntington's disease and Parkinson's disease. Proteins containing long, homopolymeric stretches of glutamine are especially prone to form aggregates. It has long been known that the small protein modifier, ubiquitin, localizes to these aggregates. In this report, nematode and cell culture models for polyglutamine aggregation are used to investigate the role of the ubiquitin pathway in protein aggregation. Results Ubiquitin conjugating enzymes (Ubc's) were identified that affect polyglutamine aggregates in C. elegans. Specifically, RNAi knockdown of ubc-2 or ubc-22 causes a significant increase in the size of aggregates as well as a reduction in aggregate number. In contrast, RNAi of ubc-1, ubc-13, or uev-1 leads to a reduction of aggregate size and eliminates ubiquitin and proteasome localization to aggregates. In cultured human cells, shRNA knockdown of human homologs of these Ubc's (Ube2A, UbcH5b, and E2-25K) causes similar effects indicating a conserved role for ubiquitination in polyglutamine protein aggregation. Conclusion Results of knockdown of different Ubc enzymes indicate that at least two different and opposing ubiquitination events occur during polyglutamine aggregation. The loss of ubiquitin localization after ubc-1, ubc-13, or uev-1 knockdown suggests that these enzymes might be directly involved in ubiquitination of aggregating proteins.
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13
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Hao Y, Boyd L, Seydoux G. Stabilization of cell polarity by the C. elegans RING protein PAR-2. Dev Cell 2006; 10:199-208. [PMID: 16459299 PMCID: PMC1712613 DOI: 10.1016/j.devcel.2005.12.015] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2005] [Revised: 11/11/2005] [Accepted: 12/21/2005] [Indexed: 12/25/2022]
Abstract
Asymmetric localization of PAR proteins is a hallmark of polarized cells, but the mechanisms that create PAR asymmetry are not well understood. In the C. elegans zygote, PAR asymmetry is initiated by a transient actomyosin contraction, which sweeps the PAR-3/PAR-6/PKC-3 complex toward the anterior pole of the egg. The RING finger protein PAR-2 accumulates in a complementary pattern in the posterior cortex. Here we present evidence that PAR-2 participates in a feedback loop to stabilize polarity. PAR-2 is a target of the PKC-3 kinase and is excluded from the anterior cortex by PKC-3-dependent phosphorylation. The RING domain of PAR-2 is required to overcome inhibition by PKC-3 and stabilize PAR-2 on the posterior cortex. Cortical PAR-2 in turn prevents PAR-3/PAR-6/PKC-3 from returning to the posterior, in a PAR-1- and PAR-5-dependent manner. Our findings suggest that reciprocal inhibitory interactions among PAR proteins stabilize polarity by reinforcing an initial asymmetry in PKC-3.
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Affiliation(s)
- Yingsong Hao
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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Cottee PA, Abs EL-Osta YG, Nisbet AJ, Gasser RB. Ubiquitin-conjugating enzyme genes in Oesophagostomum dentatum. Parasitol Res 2006; 99:119-25. [PMID: 16518612 DOI: 10.1007/s00436-005-0111-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2005] [Accepted: 12/08/2005] [Indexed: 02/03/2023]
Abstract
Full-length genes representing different isoforms of the ubiquitin-conjugating enzyme UBC-2 were isolated from Oesophagostomum dentatum, cloned and sequenced. The alignment of their sequences (designated Od-ubc-2.1 to Od-ubc-2.3) revealed nucleotide variation at three positions within the predicted open reading frame of 444 bp. Substitutions were at positions 141 (A<-->G), 142 (A<-->G) and 296 (T<-->C). Both former substitutions resulted in amino acid changes from a glycine residue to an arginine residue, whereas the latter resulted in a change from isoleucine to threonine. Comparison of predicted OD-UBC-2 with UBC-2 (protein) homologues/orthologues from 12 other species representing nematodes, Drosophila melanogaster, Saccharomyces cerevisiae, mice and humans revealed identities between species varying from 77 to 100% at the amino acid level, and motifs associated with protein conformation and function were identified. While the function of a representative ubc-2 gene from O. dentatum could not be established in C. elegans, it is likely to play a key role in the catabolism of proteins and in the development of O. dentatum.
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Affiliation(s)
- Pauline A Cottee
- Department of Veterinary Science, The University of Melbourne, 250 Princes Highway, Werribee, Victoria 3030, Australia
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