1
|
Maniates KA, Zuo Y, Flanagan K, Halim SG, Kane A, Singson A. Identification and sequencing of temperature sensitive alleles of the Anaphase Promoting Complex component mat-3 in C. elegans. MICROPUBLICATION BIOLOGY 2023; 2023:10.17912/micropub.biology.000889. [PMID: 37614776 PMCID: PMC10442702 DOI: 10.17912/micropub.biology.000889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 07/06/2023] [Accepted: 08/04/2023] [Indexed: 08/25/2023]
Abstract
The Anaphase Promoting Complex (APC) regulates the transition from metaphase to anaphase during cell division and is important to prevent defects in chromosome segregation. In a recent temperature sensitive genetic screen looking for further genes involved in fertilization, we isolated a new temperature sensitive allele of mat-3 (as49) . We also sequenced a previously identified mat-3 ( or344 ) allele that did not previously have an annotated sequence. We determined that the as49 allele was an Alanine to Threonine (A451T) mutation in the sixth exon and the or344 mutation was a Leucine to Phenylalanine (L474F) mutation in the seventh exon. These locations of the mutant alleles are consistent with other previously annotated alleles that displayed the same metaphase to anaphase transition defect phenotype and further reinforce the importance of the tetratricopeptide repeats to mediate protein interactions.
Collapse
Affiliation(s)
- Katherine A. Maniates
- Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States
- Department of Genetics, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States
| | - Yamei Zuo
- Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States
- Department of Genetics, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States
| | - Kendall Flanagan
- Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States
- Department of Genetics, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States
| | - Shania G. Halim
- Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States
- Department of Genetics, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States
| | - Alexander Kane
- Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States
- Department of Genetics, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States
| | - Andrew Singson
- Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States
- Department of Genetics, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States
| |
Collapse
|
2
|
Hu Y, Hu X, Li D, Du Z, Shi K, He C, Zhang Y, Zhang D. The APC/C FZY-1/Cdc20 Complex Coordinates With OMA-1 to Regulate the Oocyte-to-Embryo Transition in Caenorhabditis elegans. Front Cell Dev Biol 2021; 9:749654. [PMID: 34722532 PMCID: PMC8554129 DOI: 10.3389/fcell.2021.749654] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 09/27/2021] [Indexed: 11/13/2022] Open
Abstract
During oocyte maturation and the oocyte-to-embryo transition, key developmental regulators such as RNA-binding proteins coordinate translation of particular messenger RNA (mRNAs) and related developmental processes by binding to their cognate maternal mRNAs. In the nematode Caenorhabditis elegans, these processes are regulated by a set of CCCH zinc finger proteins. Oocyte maturation defective-1 (OMA-1) and OMA-2 are two functionally redundant CCCH zinc finger proteins that turnover rapidly during the first embryonic cell division. These turnovers are required for proper transition from oogenesis to embryogenesis. A gain-of-function mutant of OMA-1, oma-1(zu405), stabilizes and delays degradation of OMA-1, resulting in delayed turnover and mis-segregation of other cell fate determinants, which eventually causes embryonic lethality. We performed a large-scale forward genetic screen to identify suppressors of the oma-1(zu405) mutant. We show here that multiple alleles affecting functions of various anaphase promoting complex/cyclosome (APC/C) subunits, including MAT-1, MAT-2, MAT-3, EMB-30, and FZY-1, suppress the gain-of-function mutant of OMA-1. Transcriptome analysis suggested that overall transcription in early embryos occurred after introducing mutations in APC/C genes into the oma-1(zu405) mutant. Mutations in APC/C genes prevent OMA-1 enrichment in P granules and correct delayed degradation of downstream cell fate determinants including pharynx and intestine in excess-1 (PIE-1), posterior segregation-1 (POS-1), muscle excess-3 (MEX-3), and maternal effect germ-cell defective-1 (MEG-1). We demonstrated that only the activator FZY-1, but not FZR-1, is incorporated in the APC/C complex to regulate the oocyte-to-embryo transition. Our findings suggested a genetic relationship linking the APC/C complex and OMA-1, and support a model in which the APC/C complex promotes P granule accumulation and modifies RNA binding of OMA-1 to regulate the oocyte-to-embryo transition process.
Collapse
Affiliation(s)
- Yabing Hu
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xuewen Hu
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Dongchen Li
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhenzhen Du
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Kun Shi
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chenxia He
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ying Zhang
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Donglei Zhang
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| |
Collapse
|
3
|
Developmental Control of the Cell Cycle: Insights from Caenorhabditis elegans. Genetics 2019; 211:797-829. [PMID: 30846544 PMCID: PMC6404260 DOI: 10.1534/genetics.118.301643] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Accepted: 10/10/2018] [Indexed: 12/11/2022] Open
Abstract
During animal development, a single fertilized egg forms a complete organism with tens to trillions of cells that encompass a large variety of cell types. Cell cycle regulation is therefore at the center of development and needs to be carried out in close coordination with cell differentiation, migration, and death, as well as tissue formation, morphogenesis, and homeostasis. The timing and frequency of cell divisions are controlled by complex combinations of external and cell-intrinsic signals that vary throughout development. Insight into how such controls determine in vivo cell division patterns has come from studies in various genetic model systems. The nematode Caenorhabditis elegans has only about 1000 somatic cells and approximately twice as many germ cells in the adult hermaphrodite. Despite the relatively small number of cells, C. elegans has diverse tissues, including intestine, nerves, striated and smooth muscle, and skin. C. elegans is unique as a model organism for studies of the cell cycle because the somatic cell lineage is invariant. Somatic cells divide at set times during development to produce daughter cells that adopt reproducible developmental fates. Studies in C. elegans have allowed the identification of conserved cell cycle regulators and provided insights into how cell cycle regulation varies between tissues. In this review, we focus on the regulation of the cell cycle in the context of C. elegans development, with reference to other systems, with the goal of better understanding how cell cycle regulation is linked to animal development in general.
Collapse
|
4
|
Abstract
In all animals, oocytes are surrounded by an extracellular matrix upon fertilization. This matrix serves similar purposes in each animal. It functions to mediate sperm binding, to prevent polyspermy, to control the chemical environment of the embryo, and to provide physical protection to the embryo as it developes. The synthesis of the C. elegans matrix, or eggshell, begins when the oocyte enters the spermatheca and is fertilized by a single sperm. The process of eggshell synthesis is thought to take place during the completion of the maternal meiotic divisions such that the multi-layered eggshell is completed by anaphase II. The synthesis of the eggshell occurs in a hierarchical pattern in which the outermost layers are synthesized first in order to capture and retain the innermost layers as they form. Recent studies have revealed that the lipid-rich permeability barrier is distinct from the outer trilaminar eggshell. These new findings alter our previous understanding of the eggshell. This chapter aims to define each of the eggshell layers and the molecules that are known to play significant roles in their formation.
Collapse
Affiliation(s)
- Kathryn K Stein
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Andy Golden
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| |
Collapse
|
5
|
Davis-Roca AC, Muscat CC, Wignall SM. Caenorhabditis elegans oocytes detect meiotic errors in the absence of canonical end-on kinetochore attachments. J Cell Biol 2017; 216:1243-1253. [PMID: 28356326 PMCID: PMC5412562 DOI: 10.1083/jcb.201608042] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 12/13/2016] [Accepted: 02/14/2017] [Indexed: 01/13/2023] Open
Abstract
During mitosis, cells monitor kinetochore–microtubule attachments as a means of detecting errors. Although end-on attachments have not been observed in Caenorhabditis elegans oocytes, Davis-Roca et al. now report that these cells alter key aspects of anaphase progression in the presence of meiotic defects, revealing a new strategy for error detection during cell division. Mitotically dividing cells use a surveillance mechanism, the spindle assembly checkpoint, that monitors the attachment of spindle microtubules to kinetochores as a means of detecting errors. However, end-on kinetochore attachments have not been observed in Caenorhabditis elegans oocytes and chromosomes instead associate with lateral microtubule bundles; whether errors can be sensed in this context is not known. Here, we show that C. elegans oocytes delay key events in anaphase, including AIR-2/Aurora B relocalization to the microtubules, in response to a variety of meiotic defects, demonstrating that errors can be detected in these cells and revealing a mechanism that regulates anaphase progression. This mechanism does not appear to rely on several components of the spindle assembly checkpoint but does require the kinetochore, as depleting kinetochore components prevents the error-induced anaphase delays. These findings therefore suggest that in this system, kinetochores could be involved in sensing meiotic errors using an unconventional mechanism that does not use canonical end-on attachments.
Collapse
Affiliation(s)
- Amanda C Davis-Roca
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208
| | - Christina C Muscat
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208
| | - Sarah M Wignall
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208
| |
Collapse
|
6
|
Kumar R. Separase: Function Beyond Cohesion Cleavage and an Emerging Oncogene. J Cell Biochem 2017; 118:1283-1299. [PMID: 27966791 DOI: 10.1002/jcb.25835] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Accepted: 12/12/2016] [Indexed: 12/22/2022]
Abstract
Proper and timely segregation of genetic endowment is necessary for survival and perpetuation of every species. Mis-segregation of chromosomes and resulting aneuploidy leads to genetic instability, which can jeopardize the survival of an individual or population as a whole. Abnormality with segregation of genetic contents has been associated with several medical consequences including cancer, sterility, mental retardation, spontaneous abortion, miscarriages, and other birth related defects. Separase, by irreversible cleavage of cohesin complex subunit, paves the way for metaphase/anaphase transition during the cell cycle. Both over or reduced expression and altered level of separase have been associated with several medical consequences including cancer, as a result separase now emerges as an important oncogene and potential molecular target for medical intervenes. Recently, separase is also found to be essential in separation and duplication of centrioles. Here, I review the role of separase in mitosis, meiosis, non-canonical roles of separase, separase regulation, as a regulator of centriole disengagement, nonproteolytic roles, diverse substrates, structural insights, and association of separase with cancer. At the ends, I proposed a model which showed that separase is active throughout the cell cycle and there is a mere increase in separase activity during metaphase contrary to the common believes that separase is inactive throughout cell cycle except for metaphase. J. Cell. Biochem. 118: 1283-1299, 2017. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Ravinder Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400 076, Maharashtra, India
| |
Collapse
|
7
|
Regulation of the MEI-1/MEI-2 Microtubule-Severing Katanin Complex in Early Caenorhabditis elegans Development. G3-GENES GENOMES GENETICS 2016; 6:3257-3268. [PMID: 27527792 PMCID: PMC5068946 DOI: 10.1534/g3.116.031666] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
After fertilization, rapid changes of the Caenorhabditis elegans cytoskeleton occur in the transition from meiosis to mitosis, requiring precise regulation. The MEI-1/MEI-2 katanin microtubule-severing complex is essential for meiotic spindle formation but must be quickly inactivated to allow for proper formation of the mitotic spindle. MEI-1/MEI-2 inactivation is dependent on multiple redundant pathways. The primary pathway employs the MEL-26 substrate adaptor for the CUL-3/cullin-based E3 ubiquitin ligase, which targets MEI-1 for proteosomal degradation. Here, we used quantitative antibody staining to measure MEI-1 levels to determine how other genes implicated in MEI-1 regulation act relative to CUL-3/MEL-26. The anaphase-promoting complex/cyclosome, APC/C, the DYRK (Dual-specificity tyrosine-regulated kinase), MBK-2, and the CUL-2-based E3 ubiquitin ligase act together to degrade MEI-1, in parallel to MEL-26/CUL-3. CUL-2 is known to keep MEL-26 low during meiosis, so CUL-2 apparently changes its target from MEL-26 in meiosis to MEI-1 in mitosis. RFL-1, an activator of cullin E3 ubiquitin ligases, activates CUL-2 but not CUL-3 for MEI-1 elimination. HECD-1 (HECT/Homologous to the E6AP carboxyl terminus domain) E3 ligase acts as a MEI-1 activator in meiosis but functions as an inhibitor during mitosis, without affecting levels of MEI-1 or MEI-2. Our results highlight the multiple layers of MEI-1 regulation that are required during the switch from the meiotic to mitotic modes of cell division.
Collapse
|
8
|
Wang J, Jennings AK, Kowalski JR. The Anaphase-Promoting Complex (APC) ubiquitin ligase affects chemosensory behavior in C. elegans. PeerJ 2016; 4:e2013. [PMID: 27190716 PMCID: PMC4867703 DOI: 10.7717/peerj.2013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Accepted: 04/14/2016] [Indexed: 01/09/2023] Open
Abstract
The regulation of fundamental aspects of neurobiological function has been linked to the ubiquitin signaling system (USS), which regulates the degradation and activity of proteins and is catalyzed by E1, E2, and E3 enzymes. The Anaphase-Promoting Complex (APC) is a multi-subunit E3 ubiquitin ligase that controls diverse developmental and signaling processes in post-mitotic neurons; however, potential roles for the APC in sensory function have yet to be explored. In this study, we examined the effect of the APC ubiquitin ligase on chemosensation in Caenorhabditis elegans by testing chemotaxis to the volatile odorants, diacetyl, pyrazine, and isoamyl alcohol, to which wild-type worms are attracted. Animals with loss of function mutations in either of two alleles (g48 and ye143) of the gene encoding the APC subunit EMB-27 APC6 showed increased chemotaxis towards diacetyl and pyrazine, odorants sensed by AWA neurons, but exhibited normal chemotaxis to isoamyl alcohol, which is sensed by AWC neurons. The statistically significant increase in chemotaxis in the emb-27 APC6 mutants suggests that the APC inhibits AWA-mediated chemosensation in C. elegans. Increased chemotaxis to pyrazine was also seen with mutants lacking another essential APC subunit, MAT-2 APC1; however, mat-2 APC1 mutants exhibited wild type responses to diacetyl. The difference in responsiveness of these two APC subunit mutants may be due to differential strength of these hypomorphic alleles or may indicate the presence of functional sub-complexes of the APC at work in this process. These findings are the first evidence for APC-mediated regulation of chemosensation and lay the groundwork for further studies aimed at identifying the expression levels, function, and targets of the APC in specific sensory neurons. Because of the similarity between human and C. elegans nervous systems, the role of the APC in sensory neurons may also advance our understanding of human sensory function and disease.
Collapse
Affiliation(s)
- Julia Wang
- Department of Biological Sciences, Butler University , Indianapolis, IN , United States
| | - Alexandra K Jennings
- Department of Biological Sciences, Butler University , Indianapolis, IN , United States
| | - Jennifer R Kowalski
- Department of Biological Sciences, Butler University , Indianapolis, IN , United States
| |
Collapse
|
9
|
Abstract
Screening for suppressor mutations is a powerful method to isolate genes that function in a common pathway or process. Because suppressor mutations often do not have phenotypes on their own, cloning of suppressor loci can be challenging. A method combining whole-genome sequencing (WGS) and single nucleotide polymorphism (SNP) mapping (WGS/SNP mapping) was developed to identify mutations with visible phenotypes in C. elegans. We show here that WGS/SNP mapping is an efficient method to map suppressor mutations without the need for previous phenotypic characterization. Using RNA-mediated interference to test candidate loci identified by WGS/SNP mapping, we identified 10 extragenic and six intragenic suppressors of mbk-2, a DYRK family kinase required for the transition from oocyte to zygote. Remarkably, seven suppressors are mutations in cell-cycle regulators that extend the timing of the oocyte-to-zygote transition.
Collapse
|
10
|
McNally K, Berg E, Cortes DB, Hernandez V, Mains PE, McNally FJ. Katanin maintains meiotic metaphase chromosome alignment and spindle structure in vivo and has multiple effects on microtubules in vitro. Mol Biol Cell 2014; 25:1037-49. [PMID: 24501424 PMCID: PMC3967969 DOI: 10.1091/mbc.e13-12-0764] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Caenorhabditis elegans bivalents are positioned between dense bundles of microtubules within female meiotic spindles. Rapid inactivation of katanin after meiotic spindle assembly causes loss of organized microtubule bundles and displacement of bivalents from the metaphase plate. Purified katanin can preferentially sever at intersections between microtubules. Assembly of Caenorhabditis elegans female meiotic spindles requires both MEI-1 and MEI-2 subunits of the microtubule-severing ATPase katanin. Strong loss-of-function mutants assemble apolar intersecting microtubule arrays, whereas weaker mutants assemble bipolar meiotic spindles that are longer than wild type. To determine whether katanin is also required for spindle maintenance, we monitored metaphase I spindles after a fast-acting mei-1(ts) mutant was shifted to a nonpermissive temperature. Within 4 min of temperature shift, bivalents moved off the metaphase plate, and microtubule bundles within the spindle lengthened and developed a high degree of curvature. Spindles eventually lost bipolar structure. Immunofluorescence of embryos fixed at increasing temperature indicated that MEI-1 was lost from spindle microtubules before loss of ASPM-1, indicating that MEI-1 and ASPM-1 act independently at spindle poles. We quantified the microtubule-severing activity of purified MEI-1/MEI-2 complexes corresponding to six different point mutations and found a linear relationship between microtubule disassembly rate and meiotic spindle length. Previous work showed that katanin is required for severing at points where two microtubules intersect in vivo. We show that purified MEI-1/MEI-2 complexes preferentially sever at intersections between two microtubules and directly bundle microtubules in vitro. These activities could promote parallel/antiparallel microtubule organization in meiotic spindles.
Collapse
Affiliation(s)
- Karen McNally
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616 Genes and Development Research Group, Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB T2N 4N1, Canada
| | | | | | | | | | | |
Collapse
|
11
|
Kowalski JR, Dube H, Touroutine D, Rush KM, Goodwin PR, Carozza M, Didier Z, Francis MM, Juo P. The Anaphase-Promoting Complex (APC) ubiquitin ligase regulates GABA transmission at the C. elegans neuromuscular junction. Mol Cell Neurosci 2014; 58:62-75. [PMID: 24321454 PMCID: PMC4036811 DOI: 10.1016/j.mcn.2013.12.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 11/23/2013] [Accepted: 12/02/2013] [Indexed: 01/05/2023] Open
Abstract
Regulation of both excitatory and inhibitory synaptic transmission is critical for proper nervous system function. Aberrant synaptic signaling, including altered excitatory to inhibitory balance, is observed in numerous neurological diseases. The ubiquitin enzyme system controls the abundance of many synaptic proteins and thus plays a key role in regulating synaptic transmission. The Anaphase-Promoting Complex (APC) is a multi-subunit ubiquitin ligase that was originally discovered as a key regulator of protein turnover during the cell cycle. More recently, the APC has been shown to function in postmitotic neurons, where it regulates diverse processes such as synapse development and synaptic transmission at glutamatergic synapses. Here we report that the APC regulates synaptic GABA signaling by acting in motor neurons to control the balance of excitatory (acetylcholine) to inhibitory (GABA) transmission at the Caenorhabditis elegans neuromuscular junction (NMJ). Loss-of-function mutants in multiple APC subunits have increased muscle excitation at the NMJ; this phenotype is rescued by expression of the missing subunit in GABA neurons. Quantitative imaging and electrophysiological analyses indicate that APC mutants have decreased GABA release but normal cholinergic transmission. Consistent with this, APC mutants exhibit convulsions in a seizure assay sensitive to reductions in GABA signaling. Previous studies in other systems showed that the APC can negatively regulate the levels of the active zone protein SYD-2 Liprin-α. Similarly, we found that SYD-2 accumulates in APC mutants at GABAergic presynaptic sites. Finally, we found that the APC subunit EMB-27 CDC16 can localize to presynapses in GABA neurons. Together, our data suggest a model in which the APC acts at GABAergic presynapses to promote GABA release and inhibit muscle excitation. These findings are the first evidence that the APC regulates transmission at inhibitory synapses and have implications for understanding nervous system pathologies, such as epilepsy, that are characterized by misregulated GABA signaling.
Collapse
Affiliation(s)
- Jennifer R Kowalski
- Department of Biological Sciences, Butler University, Indianapolis, IN 46208 USA.
| | - Hitesh Dube
- Department of Biological Sciences, Butler University, Indianapolis, IN 46208 USA.
| | - Denis Touroutine
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
| | - Kristen M Rush
- Department of Biological Sciences, Butler University, Indianapolis, IN 46208 USA.
| | - Patricia R Goodwin
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA 02111, USA.
| | - Marc Carozza
- Department of Biological Sciences, Butler University, Indianapolis, IN 46208 USA.
| | - Zachary Didier
- Department of Biological Sciences, Butler University, Indianapolis, IN 46208 USA.
| | - Michael M Francis
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
| | - Peter Juo
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA 02111, USA.
| |
Collapse
|
12
|
Abstract
Egg activation is the series of events that transition a mature oocyte to an egg capable of supporting embryogenesis. Increasing evidence points toward phosphorylation as a critical regulator of these events. We used Drosophila melanogaster to investigate the relationship between known egg activation genes and phosphorylation changes that occur upon egg activation. Using the phosphorylation states of four proteins-Giant Nuclei, Young Arrest, Spindly, and Vap-33-1-as molecular markers, we showed that the egg activation genes sarah, CanB2, and cortex are required for the phospho-regulation of multiple proteins. We show that an additional egg activation gene, prage, regulates the phosphorylation state of a subset of these proteins. Finally, we show that Sarah and calcineurin are required for the Anaphase Promoting Complex/Cyclosome (APC/C)-dependent degradation of Cortex following egg activation. From these data, we present a model in which Sarah, through the activation of calcineurin, positively regulates the APC/C at the time of egg activation, which leads to a change in phosphorylation state of numerous downstream proteins.
Collapse
|
13
|
Wang R, Kaul Z, Ambardekar C, Yamamoto TG, Kavdia K, Kodali K, High AA, Kitagawa R. HECT-E3 ligase ETC-1 regulates securin and cyclin B1 cytoplasmic abundance to promote timely anaphase during meiosis in C. elegans. Development 2013; 140:2149-59. [PMID: 23578927 DOI: 10.1242/dev.090688] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The anaphase inhibitor securin plays a crucial role in regulating the timing of sister chromatid separation during mitosis. When sister chromatid pairs become bioriented, the E3 ligase anaphase promoting complex/cyclosome (APC/C) ubiquitylates securin for proteolysis, triggering sister chromatid separation. Securin is also implicated in regulating meiotic progression. Securin protein levels change sharply during cell cycle progression, enabling its timely action. To understand the mechanism underlying the tightly regulated dynamics of securin, we analyzed the subcellular localization of the securin IFY-1 during C. elegans development. IFY-1 was highly expressed in the cytoplasm of germ cells. The cytoplasmic level of IFY-1 declined immediately following meiosis I division and remained low during meiosis II and following mitoses. We identified a C. elegans homolog of another type of E3 ligase, UBE3C, designated ETC-1, as a regulator of the cytoplasmic IFY-1 level. RNAi-mediated depletion of ETC-1 stabilized IFY-1 and CYB-1 (cyclin B1) in post-meiosis I embryos. ETC-1 knockdown in a reduced APC function background caused an embryonic lethal phenotype. In vitro, ETC-1 ubiquitylates IFY-1 and CYB-1 in the presence of the E2 enzyme UBC-18, which functions in pharyngeal development. Genetic analysis revealed that UBC-18 plays a distinct role together with ETC-1 in regulating the cytoplasmic level of IFY-1 during meiosis. Our study reports a novel mechanism, mediated by ETC-1, that co-operates with APC/C to maintain the meiotic arrest required for proper cell cycle timing during reproduction.
Collapse
Affiliation(s)
- Ruishan Wang
- Department of Molecular Pharmacology, St Jude Children's Research Hospital, Memphis, TN 38105, USA
| | | | | | | | | | | | | | | |
Collapse
|
14
|
Control of oocyte growth and meiotic maturation in Caenorhabditis elegans. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 757:277-320. [PMID: 22872481 DOI: 10.1007/978-1-4614-4015-4_10] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
In sexually reproducing animals, oocytes arrest at diplotene or diakinesis and resume meiosis (meiotic maturation) in response to hormones. Chromosome segregation errors in female meiosis I are the leading cause of human birth defects, and age-related changes in the hormonal environment of the ovary are a suggested cause. Caenorhabditis elegans is emerging as a genetic paradigm for studying hormonal control of meiotic maturation. The meiotic maturation processes in C. elegans and mammals share a number of biological and molecular similarities. Major sperm protein (MSP) and luteinizing hormone (LH), though unrelated in sequence, both trigger meiotic resumption using somatic Gα(s)-adenylate cyclase pathways and soma-germline gap-junctional communication. At a molecular level, the oocyte responses apparently involve the control of conserved protein kinase pathways and post-transcriptional gene regulation in the oocyte. At a cellular level, the responses include cortical cytoskeletal rearrangement, nuclear envelope breakdown, assembly of the acentriolar meiotic spindle, chromosome segregation, and likely changes important for fertilization and the oocyte-to-embryo transition. This chapter focuses on signaling mechanisms required for oocyte growth and meiotic maturation in C. elegans and discusses how these mechanisms coordinate the completion of meiosis and the oocyte-to-embryo transition.
Collapse
|
15
|
|
16
|
Cell-Cycle Control in Oocytes and During Early Embryonic Cleavage Cycles in Ascidians. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 297:235-64. [DOI: 10.1016/b978-0-12-394308-8.00006-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
|
17
|
Abstract
In the nematode Caenorhabditis elegans, temperature-sensitive mutants of emb-1 arrest as one-cell embryos in metaphase of meiosis I in a manner that is indistinguishable from embryos that have been depleted of known subunits of the anaphase-promoting complex or cyclosome (APC/C). Here we show that the emb-1 phenotype is enhanced in double mutant combinations with known APC/C subunits and suppressed in double mutant combinations with known APC/C suppressors. In addition to its meiotic function, emb-1 is required for mitotic proliferation of the germline. These studies reveal that emb-1 encodes K10D2.4, a homolog of the small, recently discovered APC/C subunit, APC16.
Collapse
|
18
|
Green RA, Kao HL, Audhya A, Arur S, Mayers JR, Fridolfsson HN, Schulman M, Schloissnig S, Niessen S, Laband K, Wang S, Starr DA, Hyman AA, Schedl T, Desai A, Piano F, Gunsalus KC, Oegema K. A high-resolution C. elegans essential gene network based on phenotypic profiling of a complex tissue. Cell 2011; 145:470-82. [PMID: 21529718 DOI: 10.1016/j.cell.2011.03.037] [Citation(s) in RCA: 158] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2010] [Revised: 12/21/2010] [Accepted: 03/24/2011] [Indexed: 10/18/2022]
Abstract
High-content screening for gene profiling has generally been limited to single cells. Here, we explore an alternative approach-profiling gene function by analyzing effects of gene knockdowns on the architecture of a complex tissue in a multicellular organism. We profile 554 essential C. elegans genes by imaging gonad architecture and scoring 94 phenotypic features. To generate a reference for evaluating methods for network construction, genes were manually partitioned into 102 phenotypic classes, predicting functions for uncharacterized genes across diverse cellular processes. Using this classification as a benchmark, we developed a robust computational method for constructing gene networks from high-content profiles based on a network context-dependent measure that ranks the significance of links between genes. Our analysis reveals that multi-parametric profiling in a complex tissue yields functional maps with a resolution similar to genetic interaction-based profiling in unicellular eukaryotes-pinpointing subunits of macromolecular complexes and components functioning in common cellular processes.
Collapse
Affiliation(s)
- Rebecca A Green
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, 92093, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Ellefson ML, McNally FJ. CDK-1 inhibits meiotic spindle shortening and dynein-dependent spindle rotation in C. elegans. ACTA ACUST UNITED AC 2011; 193:1229-44. [PMID: 21690306 PMCID: PMC3216336 DOI: 10.1083/jcb.201104008] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Before chromosome expulsion into polar bodies during female meiosis, the APC inhibits CDK-1 to allow dynein-driven spindle rotation. In animals, the female meiotic spindle is positioned at the egg cortex in a perpendicular orientation to facilitate the disposal of half of the chromosomes into a polar body. In Caenorhabditis elegans, the metaphase spindle lies parallel to the cortex, dynein is dispersed on the spindle, and the dynein activators ASPM-1 and LIN-5 are concentrated at spindle poles. Anaphase-promoting complex (APC) activation results in dynein accumulation at spindle poles and dynein-dependent rotation of one spindle pole to the cortex, resulting in perpendicular orientation. To test whether the APC initiates spindle rotation through cyclin B–CDK-1 inactivation, separase activation, or degradation of an unknown dynein inhibitor, CDK-1 was inhibited with purvalanol A in metaphase-I–arrested, APC-depleted embryos. CDK-1 inhibition resulted in the accumulation of dynein at spindle poles and dynein-dependent spindle rotation without chromosome separation. These results suggest that CDK-1 blocks rotation by inhibiting dynein association with microtubules and with LIN-5–ASPM-1 at meiotic spindle poles and that the APC promotes spindle rotation by inhibiting CDK-1.
Collapse
Affiliation(s)
- Marina L Ellefson
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA
| | | |
Collapse
|
20
|
Abstract
Although the general events surrounding fertilization in many species are well described, the molecular underpinnings of fertilization are still poorly understood. Caenorhabditis elegans has emerged as a powerful model system for addressing the molecular and cell biological mechanism of fertilization. A primary advantage is the ability to isolate and propagate mutants that effect gametes and no other cells. This chapter provides conceptual guidelines for the identification, maintenance, and experimental approaches for the study fertility mutants.
Collapse
Affiliation(s)
- Brian D. Geldziler
- Waksman Institute, Rutgers University, Dept. of Microbiology and Molecular Genetics
| | - Matthew R. Marcello
- Waksman Institute, Rutgers University, Dept. of Microbiology and Molecular Genetics
| | | | - Andrew Singson
- Waksman Institute, Rutgers University, Dept. of Microbiology and Molecular Genetics
| |
Collapse
|
21
|
Functional redundancy of paralogs of an anaphase promoting complex/cyclosome subunit in Caenorhabditis elegans meiosis. Genetics 2010; 186:1285-93. [PMID: 20944012 DOI: 10.1534/genetics.110.123463] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The anaphase promoting complex/cyclosome (APC/C) mediates the metaphase-to-anaphase transition by instructing the ubiquitination and turnover of key proteins at this stage of the cell cycle. We have recovered a gain-of-function allele in an APC5 subunit of the anaphase promoting complex/cyclosome. This finding led us to investigate further the role of APC5 in Caenorhabditis elegans, which contains two APC5 paralogs. We have shown that these two paralogs, such-1 and gfi-3, are coexpressed in the germline but have nonoverlapping expression patterns in other tissues. Depletion of such-1 or gfi-3 alone does not have a notable effect on the meiotic divisions; however, codepletion of these two factors results in meiotic arrest. In sum, the two C. elegans APC5 paralogs have a redundant function during the meiotic divisions.
Collapse
|
22
|
Mutual antagonism between the anaphase promoting complex and the spindle assembly checkpoint contributes to mitotic timing in Caenorhabditis elegans. Genetics 2010; 186:1271-83. [PMID: 20944014 DOI: 10.1534/genetics.110.123133] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The anaphase promoting complex/cyclosome (APC/C) triggers the separation of sister chromatids and exit from mitosis across eukaryotic evolution. The APC/C is inhibited by the spindle assembly checkpoint (SAC) until all chromosomes have achieved bipolar attachment, but whether the APC/C reciprocally regulates the SAC is less understood. Here, we report the characterization of a novel allele of the APC5 component SUCH-1 in Caenorhabditis elegans. We find that some such-1(t1668) embryos lack paternally contributed DNA and centrioles and assemble a monopolar spindle in the one-cell stage. Importantly, we show that mitosis is drastically prolonged in these embryos, as well as in embryos that are otherwise compromised for APC/C function and assemble a monopolar spindle. This increased duration of mitosis is dependent on the SAC, since inactivation of the SAC components MDF-1/MAD1 or MDF-2/MAD2 rescues proper timing in these embryos. Moreover, partial depletion of the E1 enzyme uba-1 significantly increases mitosis duration upon monopolar spindle assembly. Taken together, our findings raise the possibility that the APC/C negatively regulates the SAC and, therefore, that the SAC and the APC/C have a mutual antagonistic relationship in C. elegans embryos.
Collapse
|
23
|
Kops GJPL, van der Voet M, van der Voet M, Manak MS, van Osch MHJ, Naini SM, Brear A, McLeod IX, Hentschel DM, Yates JR, van den Heuvel S, Shah JV. APC16 is a conserved subunit of the anaphase-promoting complex/cyclosome. J Cell Sci 2010; 123:1623-33. [PMID: 20392738 DOI: 10.1242/jcs.061549] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Error-free chromosome segregation depends on timely activation of the multi-subunit E3 ubiquitin ligase APC/C. Activation of the APC/C initiates chromosome segregation and mitotic exit by targeting critical cell-cycle regulators for destruction. The APC/C is the principle target of the mitotic checkpoint, which prevents segregation while chromosomes are unattached to spindle microtubules. We now report the identification and characterization of APC16, a conserved subunit of the APC/C. APC16 was found in association with tandem-affinity-purified mitotic checkpoint complex protein complexes. APC16 is a bona fide subunit of human APC/C: it is present in APC/C complexes throughout the cell cycle, the phenotype of APC16-depleted cells copies depletion of other APC/C subunits, and APC16 is important for APC/C activity towards mitotic substrates. APC16 sequence homologues can be identified in metazoans, but not fungi, by four conserved primary sequence stretches. We provide evidence that the C. elegans gene K10D2.4 and the D. rerio gene zgc:110659 are functional equivalents of human APC16. Our findings show that APC/C is composed of previously undescribed subunits, and raise the question of why metazoan APC/C is molecularly different from unicellular APC/C.
Collapse
Affiliation(s)
- Geert J P L Kops
- Department of Physiological Chemistry and Cancer Genomics Centre, UMC Utrecht, Utrecht, The Netherlands.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Abstract
The anaphase-promoting complex/cyclosome (APC/C) is a multisubunit E3 ubiquitin ligase that triggers the degradation of multiple substrates during mitosis. Cdc20/Fizzy and Cdh1/Fizzy-related activate the APC/C and confer substrate specificity through complex interactions with both the core APC/C and substrate proteins. The regulation of Cdc20 and Cdh1 is critical for proper APC/C activity and occurs in multiple ways: targeted protein degradation, phosphorylation, and direct binding of inhibitory proteins. During the specialized divisions of meiosis, the activity of the APC/C must be modified to achieve proper chromosome segregation. Recent studies show that one way in which APC/C activity is modified is through the use of meiosis-specific APC/C activators. Furthermore, regulation of the APC/C during meiosis is carried out by both mitotic regulators of the APC/C as well as meiosis-specific regulators. Here, we review the regulation of APC/C activators during mitosis and the role and regulation of the APC/C during female meiosis.
Collapse
Affiliation(s)
- Jillian A Pesin
- Whitehead Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | | |
Collapse
|
25
|
Kulkarni M, Smith HE. E1 ubiquitin-activating enzyme UBA-1 plays multiple roles throughout C. elegans development. PLoS Genet 2008; 4:e1000131. [PMID: 18636104 PMCID: PMC2443343 DOI: 10.1371/journal.pgen.1000131] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Accepted: 06/18/2008] [Indexed: 11/18/2022] Open
Abstract
Poly-ubiquitination of target proteins typically marks them for destruction via the proteasome and provides an essential mechanism for the dynamic control of protein levels. The E1 ubiquitin-activating enzyme lies at the apex of the ubiquitination cascade, and its activity is necessary for all subsequent steps in the reaction. We have isolated a temperature-sensitive mutation in the Caenorhabditis elegans uba-1 gene, which encodes the sole E1 enzyme in this organism. Manipulation of UBA-1 activity at different developmental stages reveals a variety of functions for ubiquitination, including novel roles in sperm fertility, control of body size, and sex-specific development. Levels of ubiquitin conjugates are substantially reduced in the mutant, consistent with reduced E1 activity. The uba-1 mutation causes delays in meiotic progression in the early embryo, a process that is known to be regulated by ubiquitin-mediated proteolysis. The uba-1 mutation also demonstrates synthetic lethal interactions with alleles of the anaphase-promoting complex, an E3 ubiquitin ligase. The uba-1 mutation provides a sensitized genetic background for identifying new in vivo functions for downstream components of the ubiquitin enzyme cascade, and it is one of the first conditional mutations reported for the essential E1 enzyme in a metazoan animal model.
Collapse
Affiliation(s)
- Madhura Kulkarni
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America
| | - Harold E. Smith
- Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland, United States of America
- * E-mail:
| |
Collapse
|
26
|
Pesin JA, Orr-Weaver TL. Developmental role and regulation of cortex, a meiosis-specific anaphase-promoting complex/cyclosome activator. PLoS Genet 2008; 3:e202. [PMID: 18020708 PMCID: PMC2077894 DOI: 10.1371/journal.pgen.0030202] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2007] [Accepted: 09/28/2007] [Indexed: 11/18/2022] Open
Abstract
During oogenesis in metazoans, the meiotic divisions must be coordinated with development of the oocyte to ensure successful fertilization and subsequent embryogenesis. The ways in which the mitotic machinery is specialized for meiosis are not fully understood. cortex, which encodes a putative female meiosis-specific anaphase-promoting complex/cyclosome (APC/C) activator, is required for proper meiosis in Drosophila. We demonstrate that CORT physically associates with core subunits of the APC/C in ovaries. APC/C(CORT) targets Cyclin A for degradation prior to the metaphase I arrest, while Cyclins B and B3 are not targeted until after egg activation. We investigate the regulation of CORT and find that CORT protein is specifically expressed during the meiotic divisions in the oocyte. Polyadenylation of cort mRNA is correlated with appearance of CORT protein at oocyte maturation, while deadenylation of cort mRNA occurs in the early embryo. CORT protein is targeted for degradation by the APC/C following egg activation, and this degradation is dependent on an intact D-box in the C terminus of CORT. Our studies reveal the mechanism for developmental regulation of an APC/C activator and suggest it is one strategy for control of the female meiotic cell cycle in a multicellular organism.
Collapse
Affiliation(s)
- Jillian A Pesin
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Whitehead Institute, Cambridge, Massachusetts, United States of America
| | - Terry L Orr-Weaver
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Whitehead Institute, Cambridge, Massachusetts, United States of America
- * To whom correspondence should be addressed. E-mail:
| |
Collapse
|
27
|
Narbonne-Reveau K, Senger S, Pal M, Herr A, Richardson HE, Asano M, Deak P, Lilly MA. APC/CFzr/Cdh1 promotes cell cycle progression during the Drosophila endocycle. Development 2008; 135:1451-61. [PMID: 18321983 DOI: 10.1242/dev.016295] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The endocycle is a commonly observed variant cell cycle in which cells undergo repeated rounds of DNA replication with no intervening mitosis. How the cell cycle machinery is modified to transform a mitotic cycle into endocycle has long been a matter of interest. In both plants and animals, the transition from the mitotic cycle to the endocycle requires Fzr/Cdh1, a positive regulator of the Anaphase-Promoting Complex/Cyclosome (APC/C). However, because many of its targets are transcriptionally downregulated upon entry into the endocycle, it remains unclear whether the APC/C functions beyond the mitotic/endocycle boundary. Here, we report that APC/C Fzr/Cdh1 activity is required to promote the G/S oscillation of the Drosophila endocycle. We demonstrate that compromising APC/C activity, after cells have entered the endocycle, inhibits DNA replication and results in the accumulation of multiple APC/C targets, including the mitotic cyclins and Geminin. Notably, our data suggest that the activity of APC/C Fzr/Cdh1 during the endocycle is not continuous but is cyclic, as demonstrated by the APC/C-dependent oscillation of the pre-replication complex component Orc1. Taken together, our data suggest a model in which the cyclic activity of APC/C Fzr/Cdh1 during the Drosophila endocycle is driven by the periodic inhibition of Fzr/Cdh1 by Cyclin E/Cdk2. We propose that, as is observed in mitotic cycles, during endocycles, APC/C Fzr/Cdh1 functions to reduce the levels of the mitotic cyclins and Geminin in order to facilitate the relicensing of DNA replication origins and cell cycle progression.
Collapse
Affiliation(s)
- Karine Narbonne-Reveau
- Cell Biology and Metabolism Program, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | | | | | | | | | | | | | | |
Collapse
|
28
|
Identification of the C. elegans anaphase promoting complex subunit Cdc26 by phenotypic profiling and functional rescue in yeast. BMC DEVELOPMENTAL BIOLOGY 2007; 7:19. [PMID: 17374146 PMCID: PMC1847674 DOI: 10.1186/1471-213x-7-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Accepted: 03/20/2007] [Indexed: 11/10/2022]
Abstract
Background RNA interference coupled with videorecording of C. elegans embryos is a powerful method for identifying genes involved in cell division processes. Here we present a functional analysis of the gene B0511.9, previously identified as a candidate cell polarity gene in an RNAi videorecording screen of chromosome I embryonic lethal genes. Results Whereas weak RNAi inhibition of B0511.9 causes embryonic cell polarity defects, strong inhibition causes embryos to arrest in metaphase of meiosis I. The range of defects induced by RNAi of B0511.9 is strikingly similar to those displayed by mutants of anaphase-promoting complex/cyclosome (APC/C) components. Although similarity searches did not reveal any obvious homologue of B0511.9 in the non-redundant protein database, we found that the N-terminus shares a conserved sequence pattern with the N-terminus of the small budding yeast APC/C subunit Cdc26 and its orthologues from a variety of other organisms. Furthermore, we show that B0511.9 robustly complements the temperature-sensitive growth defect of a yeast cdc26Δ mutant. Conclusion These data demonstrate that B0511.9 encodes the C. elegans APC/C subunit CDC-26.
Collapse
|
29
|
Tarailo M, Kitagawa R, Rose AM. Suppressors of spindle checkpoint defect (such) mutants identify new mdf-1/MAD1 interactors in Caenorhabditis elegans. Genetics 2007; 175:1665-79. [PMID: 17237515 PMCID: PMC1855113 DOI: 10.1534/genetics.106.067918] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The spindle assembly checkpoint (SAC) governs the timing of metaphase-to-anaphase transition and is essential for genome stability. The Caenorhabditis elegans mutant strain gk2 carries a deletion within the mdf-1/MAD1 gene that results in death of the homozygous strain after two or three generations. Here we describe 11 suppressors of the mdf-1(gk2) lethality, 10 identified in an ethyl methanesulfonate (EMS) mutagenesis screen and 1 isolated using the dog-1(gk10) (deletions of guanine-rich DNA) mutator strain. Using time-lapse imaging of early embryonic cells and germline mitotic division, we demonstrate that there are two classes of suppressors. Eight suppressors compensate for the loss of the checkpoint by delaying mitotic progression, which coincides with securin (IFY-1/Pds1) accumulation; three suppressors have normal IFY-1/Pds1 levels and normal anaphase onset. Furthermore, in the class of suppressors with delayed mitotic progression, we have identified four alleles of known suppressors emb-30/APC4 and fzy-1/CDC20, which are components of the anaphase-promoting complex/cyclosome (APC/C). In addition, we have identified another APC/C component capable of bypassing the checkpoint requirement that has not previously been described in C. elegans. The such-1/APC5-like mutation, h1960, significantly delays anaphase onset both in germline and in early embryonic cells.
Collapse
Affiliation(s)
- Maja Tarailo
- Department of Medical Genetics, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | | | | |
Collapse
|
30
|
Wehman AM, Staub W, Baier H. The anaphase-promoting complex is required in both dividing and quiescent cells during zebrafish development. Dev Biol 2006; 303:144-56. [PMID: 17141209 DOI: 10.1016/j.ydbio.2006.10.043] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2006] [Revised: 10/21/2006] [Accepted: 10/27/2006] [Indexed: 01/04/2023]
Abstract
The anaphase-promoting complex/cyclosome (APC/C) regulates multiple stages of the cell cycle, most prominently mitosis. We describe zebrafish with mutations in two APC/C subunits, Cdc16 and Cdc26, whose phenotypes reveal a multifaceted set of defects resulting from the gradual depletion of the APC/C. First, loss of the APC/C in dividing cells results in mitotic arrest, followed by apoptosis. This defect becomes detectable in different organs at different larval ages, because the subunits of the APC/C are maternally deposited, are unusually stable, and are depleted at uneven rates in different tissues. Second, loss of the APC/C in quiescent or differentiated cells results in improper re-entry into the cell cycle, again in an apparently tissue-specific manner. This study is the first demonstration of both functions of the APC/C in a vertebrate organism and also provides an illustration of the surprisingly complex effects that essential, maternally supplied factors can have on the growing animal over a period of 10 days or longer.
Collapse
Affiliation(s)
- Ann M Wehman
- Programs in Genetics and Developmental Biology, University of California-San Francisco, 1550 4th Street, San Francisco, CA 94158-2722, USA
| | | | | |
Collapse
|
31
|
Stein KK, Davis ES, Hays T, Golden A. Components of the spindle assembly checkpoint regulate the anaphase-promoting complex during meiosis in Caenorhabditis elegans. Genetics 2006; 175:107-23. [PMID: 17057243 PMCID: PMC1774991 DOI: 10.1534/genetics.106.059105] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Temperature-sensitive mutations in subunits of the Caenorhabditis elegans anaphase-promoting complex (APC) arrest at metaphase of meiosis I at the restrictive temperature. Embryos depleted of the APC co-activator FZY-1 by RNAi also arrest at this stage. To identify regulators and potential substrates of the APC, we performed a genetic suppressor screen with a weak allele of the APC subunit MAT-3/CDC23/APC8, whose defects are specific to meiosis. Twenty-seven suppressors that resulted in embryonic viability and larval development at the restrictive temperature were isolated. We have identified the molecular lesions in 18 of these suppressors, which correspond to five genes. In addition to a single intragenic suppressor, we found mutations in the APC co-activator fzy-1 and in three spindle assembly checkpoint genes, mdf-1, mdf-2, and mdf-3/san-1, orthologs of Mad1, Mad2, and Mad3, respectively. Reduction-of-function alleles of mdf-2 and mdf-3 suppress APC mutants and exhibit pleiotropic phenotypes in an otherwise wild-type background. Analysis of a single separation-of-function allele of mdf-1 suggests that MDF-1 has a dual role during development. These studies provide evidence that components of the spindle assembly checkpoint may regulate the metaphase-to-anaphase transition in the absence of spindle damage during C. elegans meiosis.
Collapse
Affiliation(s)
- Kathryn K Stein
- Laboratory of Biochemistry and Genetics, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA
| | | | | | | |
Collapse
|
32
|
Abstract
Cell division is an inherent part of organismal development, and defects in this process can lead to developmental abnormalities as well as cancerous growth. In past decades, much of the basic cell-cycle machinery has been identified, and a major challenge in coming years will be to understand the complex interplay between cell division and multicellular development. Inevitably, this requires the use of more complex multicellular model systems. The small nematode Caenorhabditis elegans is an excellent model system to study the regulation of cell division in a multicellular organism, and is poised to make important contributions to this field. The past decade has already seen a surge in cell-cycle research in C. elegans, yielding information on the function of many basic cell-cycle regulators, and making inroads into the developmental control of cell division. This review focuses on the in vivo roles of cyclin-dependent kinases in C. elegans, and highlights novel findings implicating CDKs in coupling development to cell-cycle progression.
Collapse
Affiliation(s)
- Mike Boxem
- Massachusetts General Hospital Cancer Center, Building 149, 13th Street, Charlestown, MA 02129, USA.
| |
Collapse
|
33
|
Yamamoto I, Kosinski ME, Greenstein D. Start me up: Cell signaling and the journey from oocyte to embryo inC. elegans. Dev Dyn 2006; 235:571-85. [PMID: 16372336 DOI: 10.1002/dvdy.20662] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Intercellular communication plays a pivotal role in regulating and coordinating oocyte meiosis and fertilization, key triggers for embryonic development. The nematode Caenorhabaditis elegans has emerged as an important experimental paradigm for exploring these fundamental reproductive processes and their regulation. The oocytes of most animal species arrest during meiotic prophase and complete meiosis in response to intercellular signaling in the process of meiotic maturation. Oocyte meiotic maturation is defined by the transition between diakinesis and metaphase of meiosis I and is accompanied by nuclear envelope breakdown and meiotic spindle assembly. As such, the meiotic maturation process is essential for completing meiosis and a prerequisite for successful fertilization. In C. elegans, the processes of meiotic maturation, ovulation, and fertilization are temporally coupled: sperm utilize the major sperm protein as a hormone to trigger oocyte meiotic maturation, and, in turn, the maturing oocyte signals its own ovulation, leading to fertilization. The powerful genetic screens possible in C. elegans have led to the identification of several sperm cell surface proteins that are required for the interaction and fusion of gametes at fertilization. The study of these proteins provides fundamental insights into fertilization mechanisms, their role in speciation, and their potential conservation across phyla. Signaling processes sparked by fertilization are required for meiotic chromosome segregation and initiating the embryonic program. Here we review recent advances in understanding how signaling mechanisms contribute to the oocyte-to-embryo transition in C. elegans.
Collapse
Affiliation(s)
- Ikuko Yamamoto
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-8240, USA
| | | | | |
Collapse
|
34
|
Bowerman B, Kurz T. Degrade to create: developmental requirements for ubiquitin-mediated proteolysis during earlyC. elegansembryogenesis. Development 2006; 133:773-84. [PMID: 16469970 DOI: 10.1242/dev.02276] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The ubiquitin protein conjugation system tags proteins with the small polypeptide ubiquitin. Most poly-ubiquitinated proteins are recognized and degraded by the proteasome, a large multi-subunit protease. Ubiquitin-dependent protein degradation is used as a regulatory tool for many essential processes, the best studied of which is eukaryotic cell cycle progression. More recently, genetic studies in C. elegans have identified multiple roles for the ubiquitin system in early development, where ubiquitin-dependent protein degradation governs such diverse events as passage through meiosis, cytoskeletal regulation and cell fate determination.
Collapse
Affiliation(s)
- Bruce Bowerman
- Institute of Molecular Biology, University of Oregon, Eugene, 97403, USA
| | | |
Collapse
|
35
|
Burrows AE, Sceurman BK, Kosinski ME, Richie CT, Sadler PL, Schumacher JM, Golden A. The C. elegans Myt1 ortholog is required for the proper timing of oocyte maturation. Development 2006; 133:697-709. [PMID: 16421191 PMCID: PMC1794222 DOI: 10.1242/dev.02241] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Maturation promoting factor (MPF), a complex of cyclin-dependent kinase 1 and cyclin B, drives oocyte maturation in all animals. Mechanisms to block MPF activation in developing oocytes must exist to prevent precocious cell cycle progression prior to oocyte maturation and fertilization. This study sought to determine the developmental consequences of precociously activating MPF in oocytes prior to fertilization. Whereas depletion of Myt1 in Xenopus oocytes causes nuclear envelope breakdown in vitro, we found that depletion of the Myt1 ortholog WEE-1.3 in C. elegans hermaphrodites causes precocious oocyte maturation in vivo. Although such oocytes are ovulated, they are fertilization incompetent. We have also observed novel phenotypes in these precociously maturing oocytes, such as chromosome coalescence, aberrant meiotic spindle organization, and the expression of a meiosis II post-fertilization marker. Furthermore, co-depletion studies of CDK-1 and WEE-1.3 demonstrate that WEE-1.3 is dispensable in the absence of CDK-1, suggesting that CDK-1 is a major target of WEE-1.3 in C. elegans oocytes.
Collapse
Affiliation(s)
- Anna E Burrows
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 8 Center Drive, Building 8, Room 323, Bethesda, MD 20892, USA
| | | | | | | | | | | | | |
Collapse
|
36
|
Abstract
Ubiquitin-mediated proteolysis is one of the key mechanisms underlying cell cycle control. The removal of barriers posed by accumulation of negative regulators, as well as the clearance of proteins when they are no longer needed or deleterious, are carried out via the ubiquitin-proteasome system. Ubiquitin conjugating enzymes and protein-ubiquitin ligases collaborate to mark proteins destined for degradation by the proteasome by covalent attachment of multi-ubiquitin chains. Most regulated proteolysis during the cell cycle can be attributed to two families of protein-ubiquitin ligases. The anaphase promoting complex/cyclosome (APC/C) is activated during mitosis and G1 where it is responsible for eliminating proteins that impede mitotic progression and that would have deleterious consequences if allowed to accumulate during G1. SCF (Skp1/Culin/F-box protein) protein-ubiquitin ligases ubiquitylate proteins that are marked by phosphorylation at specific sequences known as phosphodegrons. Targeting of proteins for destruction by phosphorylation provides a mechanism for linking cell cycle regulation to internal and external signaling pathways via regulated protein kinase activities.
Collapse
Affiliation(s)
- Steven I Reed
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
| |
Collapse
|
37
|
McNally KL, McNally FJ. Fertilization initiates the transition from anaphase I to metaphase II during female meiosis in C. elegans. Dev Biol 2005; 282:218-30. [PMID: 15936342 DOI: 10.1016/j.ydbio.2005.03.009] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2004] [Revised: 03/02/2005] [Accepted: 03/15/2005] [Indexed: 11/15/2022]
Abstract
Oocytes from most animals arrest twice during the meiotic cell cycle. The universally conserved prophase I arrest is released by a maturation hormone that allows progression to a second arrest point, typically metaphase I or II. This second arrest allows for short-term storage of fertilization-competent eggs and is released by signaling that occurs during fertilization. Nematodes are unique in that the maturation hormone is secreted by sperm rather than by the mother's somatic tissues. We have investigated the nature of the second arrest in matured but unfertilized Caenorhabditis elegans embryos using time-lapse imaging of GFP-tubulin or GFP-histone. Unfertilized embryos completed anaphase I but did not form polar bodies or assemble meiosis II spindles. Nevertheless, unfertilized embryos assembled female pronuclei at the same time as fertilized embryos. Analysis of embryos fertilized by sperm lacking the SPE-11 protein indicated that fertilization promotes meiotic cytokinesis through the SPE-11 protein but assembly of the meiosis II spindle is initiated through an SPE-11-independent pathway.
Collapse
Affiliation(s)
- Karen L McNally
- Section of Molecular and Cellular Biology, 149 Briggs Hall, University of California, Davis, CA 95616, USA
| | | |
Collapse
|
38
|
Garbe D, Doto JB, Sundaram MV. Caenorhabditis elegans lin-35/Rb, efl-1/E2F and other synthetic multivulva genes negatively regulate the anaphase-promoting complex gene mat-3/APC8. Genetics 2005; 167:663-72. [PMID: 15238519 PMCID: PMC1470888 DOI: 10.1534/genetics.103.026021] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Retinoblastoma (Rb)/E2F complexes repress expression of many genes important for G(1)-to-S transition, but also appear to regulate gene expression at other stages of the cell cycle. In C. elegans, lin-35/Rb and other synthetic Multivulva (SynMuv) group B genes function redundantly with other sets of genes to regulate G(1)/S progression, vulval and pharyngeal differentiation, and other unknown processes required for viability. Here we show that lin-35/Rb, efl-1/E2F, and other SynMuv B genes negatively regulate a component of the anaphase-promoting complex or cyclosome (APC/C). The APC/C is a multisubunit complex that promotes metaphase-to-anaphase progression and G(1) arrest by targeting different substrates for ubiquitination and proteasome-mediated destruction. The C. elegans APC/C gene mat-3/APC8 has been defined by temperature-sensitive embryonic lethal alleles that strongly affect germline meiosis and mitosis but only weakly affect somatic development. We describe severe nonconditional mat-3 alleles and a hypomorphic viable allele (ku233), all of which affect postembryonic cell divisions including those of the vulval lineage. The ku233 lesion is located outside of the mat-3 coding region and reduces mat-3 mRNA expression. Loss-of-function alleles of lin-35/Rb and other SynMuv B genes suppress mat-3(ku233) defects by restoring mat-3 mRNA to wild-type levels. Therefore, Rb/E2F complexes appear to repress mat-3 expression.
Collapse
Affiliation(s)
- David Garbe
- Department of Genetics, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6100, USA
| | | | | |
Collapse
|
39
|
Penkner AM, Prinz S, Ferscha S, Klein F. Mnd2, an essential antagonist of the anaphase-promoting complex during meiotic prophase. Cell 2005; 120:789-801. [PMID: 15797380 DOI: 10.1016/j.cell.2005.01.017] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2004] [Revised: 11/19/2004] [Accepted: 01/18/2005] [Indexed: 11/30/2022]
Abstract
Meiotic cohesin serves in sister chromatid linkage and DNA repair until its subunit Rec8 is cleaved by separase. Separase is activated when its inhibitor, securin, is polyubiquitinated by the Cdc20 regulated anaphase-promoting complex (APC(Cdc20)) and consequently degraded. Differently regulated APCs (APC(Cdh1), APC(Ama1)) have not been implicated in securin degradation at meiosis I. We show that Mnd2, a factor known to associate with APC components, prevents premature securin degradation in meiosis by APC(Ama1). mnd2Delta cells lack linear chromosome axes and exhibit precocious sister chromatid separation, but deletion of AMA1 suppresses these defects. Besides securin, Sgo1, a protein essential for protection of centromeric cohesion during anaphase I, is also destabilized in mnd2delta cells. Mnd2's disappearance prior to anaphase II may activate APC(Ama1). Human oocytes may spend many years in meiotic prophase before maturation. Inhibitors of meiotic APC variants could prevent loss of chiasmata also in these cells, thereby guarding against aberrant chromosome segregation.
Collapse
Affiliation(s)
- Alexandra M Penkner
- Vienna Biocenter II, Max Perutz Laboratories, Department of Chromosome Biology, Vienna, Austria
| | | | | | | |
Collapse
|
40
|
Juo P, Kaplan JM. The anaphase-promoting complex regulates the abundance of GLR-1 glutamate receptors in the ventral nerve cord of C. elegans. Curr Biol 2005; 14:2057-62. [PMID: 15556870 DOI: 10.1016/j.cub.2004.11.010] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2004] [Revised: 09/27/2004] [Accepted: 09/29/2004] [Indexed: 10/26/2022]
Abstract
The anaphase-promoting complex (APC) is a multisubunit E3 ubiquitin ligase that targets key cell cycle regulatory proteins for degradation. Blockade of APC activity causes mitotic arrest. Recent evidence suggests that the APC may have roles outside the cell cycle. Several studies indicate that ubiquitin plays an important role in regulating synaptic strength. We previously showed that ubiquitin is directly conjugated to GLR-1, a C. elegans non-NMDA (N-methyl-D-aspartate) class glutamate receptor (GluR), resulting in its removal from synapses. By contrast, endocytosis of rodent AMPA GluRs is apparently regulated by ubiquitination of associated scaffolding proteins. Relatively little is known about the E3 ligases that mediate these effects. We examined the effects of perturbing APC function on postmitotic neurons in the nematode C. elegans. Temperature-sensitive mutations in APC subunits increased the abundance of GLR-1 in the ventral nerve cord. Mutations that block clathrin-mediated endocytosis blocked the effects of the APC mutations, suggesting that the APC regulates some aspect of GLR-1 recycling. Overexpression of ubiquitin decreased the density of GLR-1-containing synapses, and APC mutations blunted this effect. APC mutants had locomotion defects consistent with increased synaptic strength. This study defines a novel function for the APC in postmitotic neurons.
Collapse
Affiliation(s)
- Peter Juo
- Department of Molecular Biology, Massachusetts General Hospital, Department of Genetics, Harvard Medical School, Boston, MA 02114, USA
| | | |
Collapse
|
41
|
Arnason TG, Pisclevich MG, Dash MD, Davies GF, Harkness TAA. Novel interaction between Apc5p and Rsp5p in an intracellular signaling pathway in Saccharomyces cerevisiae. EUKARYOTIC CELL 2005; 4:134-46. [PMID: 15643069 PMCID: PMC544157 DOI: 10.1128/ec.4.1.134-146.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2004] [Accepted: 11/02/2004] [Indexed: 11/20/2022]
Abstract
The ubiquitin-targeting pathway is evolutionarily conserved and critical for many cellular functions. Recently, we discovered a role for two ubiquitin-protein ligases (E3s), Rsp5p and the Apc5p subunit of the anaphase-promoting complex (APC), in mitotic chromatin assembly in Saccharomyces cerevisiae. In the present study, we investigated whether Rsp5p and Apc5p interact in an intracellular pathway regulating chromatin remodeling. Our genetic studies strongly suggest that Rsp5p and Apc5p do interact and that Rsp5p acts upstream of Apc5p. Since E3 enzymes typically require the action of a ubiquitin-conjugating enzyme (E2), we screened E2 mutants for chromatin assembly defects, which resulted in the identification of Cdc34p and Ubc7p. Cdc34p is the E2 component of the SCF (Skp1p/Cdc53p/F-box protein). Therefore, we analyzed additional SCF mutants for chromatin assembly defects. Defective chromatin assembly extracts generated from strains harboring a mutation in the Cdc53p SCF subunit or a nondegradable SCF target, Sic1(Deltaphos), confirmed that the SCF was involved in mitotic chromatin assembly. Furthermore, we demonstrated that Ubc7p physically and genetically interacts with Rsp5p, suggesting that Ubc7p acts as an E2 for Rsp5p. However, rsp5CA and Deltaubc7 mutations had opposite genetic effects on apc5CA and cdc34-2 phenotypes. Therefore, the antagonistic interplay between Deltaubc7 and rsp5CA, with respect to cdc34-2 and apc5CA, indicates that the outcome of Rsp5p's interaction with Cdc34p and Apc5p may depend on the E2 interacting with Rsp5p.
Collapse
Affiliation(s)
- Terra G Arnason
- Department of Medicine, Royal University Hospital, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | | | | | | | | |
Collapse
|
42
|
Abstract
Meiosis is the type of cell division that gives rise to eggs and sperm. Errors in the execution of this process can result in the generation of aneuploid gametes, which are associated with birth defects and infertility in humans. Here, we review recent findings on how cell-cycle controls ensure the coordination of meiotic events, with a particular focus on the segregation of chromosomes.
Collapse
Affiliation(s)
- Adèle L Marston
- Center for Cancer Research, Howard Hughes Medical Institute, Massachusetts Institute of Technology, E17-233, 40 Ames Street, Cambridge, Massachusetts 02139, USA
| | | |
Collapse
|
43
|
Humbert PO, Brumby AM, Quinn LM, Richardson HE. New tricks for old dogs: unexpected roles for cell cycle regulators revealed using animal models. Curr Opin Cell Biol 2004; 16:614-22. [PMID: 15530771 DOI: 10.1016/j.ceb.2004.09.001] [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] [Indexed: 12/24/2022]
Abstract
Studies in animal models have revealed many surprises regarding the importance of key cell cycle regulators during animal development and homeostasis, underscoring the plasticity and redundancy of cell cycle circuitry within a whole-animal context. Moreover, checkpoint regulators, which are not essential for viability in yeast and cultured cells, play important roles in cell cycle control during development.
Collapse
Affiliation(s)
- Patrick O Humbert
- Cell cycle and cancer genetics laboratory, Research Division, Peter MacCallum Cancer Centre, East Melbourne, Australia
| | | | | | | |
Collapse
|
44
|
Frazier T, Shakes D, Hota U, Boyd L. Caenorhabditis elegans UBC-2 functions with the anaphase-promoting complex but also has other activities. J Cell Sci 2004; 117:5427-35. [PMID: 15466891 DOI: 10.1242/jcs.01417] [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: 01/11/2023] Open
Abstract
The anaphase-promoting complex or cyclosome (APC/C) is a multi-subunit ubiquitin ligase that regulates the eukaryotic cell cycle. APC/C belongs to the RING finger class of ubiquitin ligases that function by interacting with a ubiquitin-conjugating enzyme (Ubc), thus inciting the Ubc to transfer ubiquitin onto a target protein. Extensive studies with APC/C in other organisms have identified several possible Ubcs that might function as partners for APC/C. This report presents phenotypic and biochemical evidence showing that, in Caenorhabditis elegans, UBC-2 interacts specifically with the APC/C. This conclusion is based on three lines of evidence: first, the RNAi phenotype of ubc-2 is indistinguishable from RNAi phenotypes of APC/C subunits; second, RNAi of ubc-2 but not other Ubcs enhances the phenotype of hypomorphic APC/C mutants; third, purified UBC-2 and APC-11, the RING finger subunit of the APC/C, show robust ubiquitination activity in in vitro assays. APC-11 interaction is specific for UBC-2 as ubiquitination is not seen when APC-11 is combined other C. elegans Ubcs. As expected from the Ubc that functions with the APC/C, ubc-2(RNAi) produces metaphase blocks in both mitotic germ cells and in meiotic divisions of post-fertilization oocytes. In addition, ubc-2(RNAi) results in two germline phenotypes that appear to be unrelated to the APC/C: an expanded transition zone indicative of a pre-pachytene meiotic arrest and endo-reduplicated oocytes indicative of a problem in ovulation or oocyte-soma interactions.
Collapse
Affiliation(s)
- Tyralynn Frazier
- Department of Biological Sciences, University of Alabama in Huntsville, Huntsville, AL 35899, USA
| | | | | | | |
Collapse
|
45
|
Abstract
The RING finger motif exists in E3 ligases of the ubiquitination pathway. These ubiquitin ligases bind to target proteins, leading to their modification by covalent addition of ubiquitin peptides. Current databases contain hundreds of proteins with RING finger motifs. This study investigates the role of RING finger genes in embryogenesis of the nematode, Caenorhabditis elegans. We expand the previous list of RING finger-containing genes and show that there are 103 RING finger-containing genes in the C. elegans genome. DNA microarrays of these 103 genes were probed with various RNA samples to identify 16 RING finger genes whose expression is enriched in the germline. RNA interference (RNAi) analysis was then used to determine the developmental role of these genes. One RING finger gene, C32D5.10, showed a dramatic larval arrest upon RNAi. Three RING finger genes exhibited embryonic lethality after RNAi. These three genes include par-2, and two small RING finger proteins: F35G12.9 (an ortholog of APC11) and ZK287.5 (an ortholog of rbx1). Embryos from RNAi of the APC11 and rbx1 orthologs were arrested in the cell cycle, confirming the role of these particular RING finger proteins in regulation of the cell cycle. genesis 38:1-12, 2004.
Collapse
Affiliation(s)
- Rhonda Moore
- Department of Biological Sciences, University of Alabama in Huntsville, Huntsville, Alabama, USA
| | | |
Collapse
|
46
|
Sasagawa Y, Urano T, Kohara Y, Takahashi H, Higashitani A. Caenorhabditis elegans RBX1 is essential for meiosis, mitotic chromosomal condensation and segregation, and cytokinesis. Genes Cells 2004; 8:857-72. [PMID: 14622138 DOI: 10.1046/j.1365-2443.2003.00682.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND The RING-H2 finger protein RBX1 (ROC1/HRT1) is a common subunit of SKP1-CDC53/CUL1-F-box (SCF), other cullins and von Hippel-Lindau (VHL) tumour suppressor E3 ubiquitin ligase complexes. RBX1 protein sequences are highly conserved in various species, including yeasts, Drosophila melanogaster, mice and humans. In Saccharomyces cerevisiae, RBX1 is essential for the G1/S transition. RESULTS Caenorhabditis elegans RBX1 is strongly expressed in early embryos and in the gonad, including meiotic cells. Depletion of RBX1 by RNA-mediated interference (RNAi) caused pronounced defects in the first meiotic division. Several irregular phenotypes were identified in embryos that escaped from meiotic arrest: defects in mitotic chromosomal condensation and segregation, abnormal chromosome bridges, giant nuclei, abnormal cortical protrusion, multinucleate cells and defects in germ cell proliferation. Moreover, histone H3 phosphorylation at Ser10 and Ser28 was significantly reduced in these embryos. The histone H3 phosphorylation defect of embryos was rescued by the additional depletion of protein phosphatase 1 (GLC7alpha/beta) by RNAi. CONCLUSION These results indicate that the RBX1 protein participates in diverse functions relevant to chromosome metabolism and cell cycle control.
Collapse
Affiliation(s)
- Yohei Sasagawa
- Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | | | | | | | | |
Collapse
|
47
|
Liu J, Vasudevan S, Kipreos ET. CUL-2 and ZYG-11 promote meiotic anaphase II and the proper placement of the anterior-posterior axis in C. elegans. Development 2004; 131:3513-25. [PMID: 15215209 DOI: 10.1242/dev.01245] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The faithful segregation of chromosomes during meiosis is vital for sexual reproduction. Currently, little is known about the molecular mechanisms regulating the initiation and completion of meiotic anaphase. We show that inactivation of CUL-2, a member of the cullin family of ubiquitin ligases, delays or abolishes meiotic anaphase II with no effect on anaphase I, indicating differential regulation during the two meiotic stages. In cul-2 mutants, the cohesin REC-8 is removed from chromosomes normally during meiosis II and sister chromatids separate, suggesting that the failure to complete anaphase results from a defect in chromosome movement rather than from a failure to sever chromosome attachments. CUL-2 is required for the degradation of cyclin B1 in meiosis and inactivation of cyclin B1 partially rescued the meiotic delay in cul-2 mutants. In cul-2 mutants, the failure to degrade cyclin B1 precedes the metaphase II arrest. CUL-2 is also required for at least two aspects of embryonic polarity. The extended meiosis II in cul-2 mutants induces polarity reversals that include reversed orientation of polarity proteins, P granules, pronuclei migration and asymmetric cell division. Independently of its role in meiotic progression, CUL-2 is required to limit the initiation/spread of the polarity protein PAR-2 in regions distant from microtubule organizing centers. Finally, we show that inactivation of the leucine-rich repeat protein ZYG-11 produces meiotic and polarity reversal defects similar to those observed in cul-2 mutants, suggesting that the two proteins function in the same pathways.
Collapse
Affiliation(s)
- Ji Liu
- Department of Cellular Biology, University of Georgia, Athens, GA 30602-2607, USA
| | | | | |
Collapse
|
48
|
Affiliation(s)
- Foong May Yeong
- Department of Biochemistry, Faculty of Medicine, National University of Singapore, Singapore 117597, Singapore.
| |
Collapse
|
49
|
Kwee HS, Sundaresan V. The NOMEGA gene required for female gametophyte development encodes the putative APC6/CDC16 component of the Anaphase Promoting Complex in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2003; 36:853-66. [PMID: 14675450 DOI: 10.1046/j.1365-313x.2003.01925.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Development of the female gametophyte involves several rounds of nuclear divisions during which nuclei are rearranged and finally cellularized to form a mature seven-celled embryo sac. During these nuclear divisions, key proteins involved in the cell cycle need to be degraded quickly in order to facilitate both the metaphase-anaphase transition stage and late anaphase. Here, we report the characterization of an Arabidopsis mutant nomega, which results in arrest of the embryo sac development at the two-nucleate stage. The NOMEGA gene product shows high homology to the APC6/cell division cycle (CDC)16 subunit of the Anaphase Promoting Complex/Cyclosome (APC/C). The phenotype of the nomega mutant is quite different from that of the hobbit mutant, which had suggested a role for the plant APC/C in auxin signalling. We show that nomega mutant embryo sacs are unable to degrade Cyclin B, an important APC/C substrate, providing further evidence of a role for the NOMEGA gene product and the plant APC/C in cell cycle progression during gametophyte development.
Collapse
Affiliation(s)
- Hong-Sien Kwee
- Institute of Molecular and Cell Biology, 1 Research Link, National University of Singapore, Singapore 117604, Singapore
| | | |
Collapse
|
50
|
Abstract
The anterior-posterior axis of the Caenorhabditis elegans zygote forms shortly after fertilization when the sperm pronucleus and its associated centrosomal asters provide a cue that establishes the anterior-posterior (AP) body axis. In response to this cue, the microfilament cytoskeleton polarizes the distribution of a group of widely conserved, cortically localized regulators called the PAR proteins, which are required for the first mitotic division to be asymmetric. These asymmetries include a posterior displacement of the first mitotic spindle and the differential segregation of cell-fate determinants to the anterior and posterior daughters produced by the first cleavage of the zygote. Here we review recent advances in our understanding of the mechanisms that polarize the one-cell zygote to generate an AP axis of asymmetry.
Collapse
Affiliation(s)
- Stephan Q Schneider
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, USA.
| | | |
Collapse
|