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Kim AJ, Miller SI, Greiner EC, Kettenbach AN, Griffin EE. PLK-1 regulates MEX-1 polarization in the C. elegans zygote. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.26.605193. [PMID: 39091813 PMCID: PMC11291152 DOI: 10.1101/2024.07.26.605193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
The one-cell C. elegans embryo undergoes an asymmetric cell division during which germline factors such as the RNA-binding proteins POS-1 and MEX-1 segregate to the posterior cytoplasm, leading to their asymmetric inheritance to the posterior germline daughter cell. Previous studies found that the RNA-binding protein MEX-5 recruits polo-like kinase PLK-1 to the anterior cytoplasm where PLK-1 inhibits the retention of its substrate POS-1, leading to POS-1 segregation to the posterior. In this study, we tested whether PLK-1 similarly regulates MEX-1 polarization. We find that both the retention of MEX-1 in the anterior and the segregation of MEX-1 to the posterior depend on PLK kinase activity and on the interaction between MEX-5 and PLK-1. Human PLK1 directly phosphorylates recombinant MEX-1 on 9 predicted PLK-1 sites in vitro, four of which were identified in previous phosphoproteomic analysis of C. elegans embryos. The introduction of alanine substitutions at these four PLK-1 phosphorylation sites (MEX-1(4A)) significantly weakened the inhibition of MEX-1 retention in the anterior, thereby weakening MEX-1 segregation to the posterior. In contrast, mutation of a predicted CDK1 phosphorylation site had no effect on MEX-1 retention or on MEX-1 segregation. MEX-1(4A) mutants are viable and fertile but display significant sterility and fecundity defects at elevated temperatures. Taken together with our previous findings, these findings suggest PLK-1 phosphorylation drives both MEX-1 and POS-1 polarization during the asymmetric division of the zygote.
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Naef V, De Sarlo M, Testa G, Corsinovi D, Azzarelli R, Borello U, Ori M. The Stemness Gene Mex3A Is a Key Regulator of Neuroblast Proliferation During Neurogenesis. Front Cell Dev Biol 2020; 8:549533. [PMID: 33072742 PMCID: PMC7536324 DOI: 10.3389/fcell.2020.549533] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 08/31/2020] [Indexed: 01/31/2023] Open
Abstract
Mex3A is an RNA binding protein that can also act as an E3 ubiquitin ligase to control gene expression at the post-transcriptional level. In intestinal adult stem cells, MEX3A is required for cell self-renewal and when overexpressed, MEX3A can contribute to support the proliferation of different cancer cell types. In a completely different context, we found mex3A among the genes expressed in neurogenic niches of the embryonic and adult fish brain and, notably, its expression was downregulated during brain aging. The role of mex3A during embryonic and adult neurogenesis in tetrapods is still unknown. Here, we showed that mex3A is expressed in the proliferative region of the developing brain in both Xenopus and mouse embryos. Using gain and loss of gene function approaches, we showed that, in Xenopus embryos, mex3A is required for neuroblast proliferation and its depletion reduced the neuroblast pool, leading to microcephaly. The tissue-specific overexpression of mex3A in the developing neural plate enhanced the expression of sox2 and msi-1 keeping neuroblasts into a proliferative state. It is now clear that the stemness property of mex3A, already demonstrated in adult intestinal stem cells and cancer cells, is a key feature of mex3a also in developing brain, opening new lines of investigation to better understand its role during brain aging and brain cancer development.
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Affiliation(s)
- Valentina Naef
- Unità di Biologia Cellulare e dello Sviluppo, Dipartimento di Biologia, Università di Pisa, Pisa, Italy.,Molecular Medicine, IRCCS Fondazione Stella Maris, Pisa, Italy
| | - Miriam De Sarlo
- Unità di Biologia Cellulare e dello Sviluppo, Dipartimento di Biologia, Università di Pisa, Pisa, Italy
| | - Giovanna Testa
- Unità di Biologia Cellulare e dello Sviluppo, Dipartimento di Biologia, Università di Pisa, Pisa, Italy.,Scuola Normale Superiore di Pisa, Pisa, Italy
| | - Debora Corsinovi
- Unità di Biologia Cellulare e dello Sviluppo, Dipartimento di Biologia, Università di Pisa, Pisa, Italy
| | - Roberta Azzarelli
- Unità di Biologia Cellulare e dello Sviluppo, Dipartimento di Biologia, Università di Pisa, Pisa, Italy
| | - Ugo Borello
- Unità di Biologia Cellulare e dello Sviluppo, Dipartimento di Biologia, Università di Pisa, Pisa, Italy
| | - Michela Ori
- Unità di Biologia Cellulare e dello Sviluppo, Dipartimento di Biologia, Università di Pisa, Pisa, Italy
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Tavella D, Ertekin A, Schaal H, Ryder SP, Massi F. A Disorder-to-Order Transition Mediates RNA Binding of the Caenorhabditis elegans Protein MEX-5. Biophys J 2020; 118:2001-2014. [PMID: 32294479 PMCID: PMC7175634 DOI: 10.1016/j.bpj.2020.02.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 01/31/2020] [Accepted: 02/12/2020] [Indexed: 11/17/2022] Open
Abstract
CCCH-type tandem zinc finger (TZF) domains are found in many RNA-binding proteins (RBPs) that regulate the essential processes of post-transcriptional gene expression and splicing through direct protein-RNA interactions. In Caenorhabditis elegans, RBPs control the translation, stability, or localization of maternal messenger RNAs required for patterning decisions before zygotic gene activation. MEX-5 (Muscle EXcess) is a C. elegans protein that leads a cascade of RBP localization events that is essential for axis polarization and germline differentiation after fertilization. Here, we report that at room temperature, the CCCH-type TZF domain of MEX-5 contains an unstructured zinc finger that folds upon binding of its RNA target. We have characterized the structure and dynamics of the TZF domain of MEX-5 and designed a variant MEX-5 in which both fingers are fully folded in the absence of RNA. Within the thermal range experienced by C. elegans, the population of the unfolded state of the TZF domain of MEX-5 varies. We observe that the TZF domain becomes less disordered at lower temperatures and more disordered at higher temperatures. However, in the temperature range in which C. elegans is fertile, when MEX-5 needs to be functional, only one of the two zinc fingers is folded.
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Affiliation(s)
- Davide Tavella
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Asli Ertekin
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Hila Schaal
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Sean P Ryder
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Francesca Massi
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts.
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Huang C, Liu T, Wang Q, Hou W, Zhou C, Song Z, Shi YS, Gao X, Chen G, Yin Z, Hu Y. Loss of PP2A Disrupts the Retention of Radial Glial Progenitors in the Telencephalic Niche to Impair the Generation for Late-Born Neurons During Cortical Development†. Cereb Cortex 2020; 30:4183-4196. [PMID: 32186707 DOI: 10.1093/cercor/bhaa042] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Telencephalic radial glial progenitors (RGPs) are retained in the ventricular zone (VZ), the niche for neural stem cells during cortical development. However, the underlying mechanism is not well understood. To study whether protein phosphatase 2A (PP2A) may regulate the above process, we generate Ppp2cα conditional knockout (cKO) mice, in which PP2A catalytic subunit α (PP2Acα) is inactivated in neural progenitor cells in the dorsal telencephalon. We show that RGPs are ectopically distributed in cortical areas outside of the VZ in Ppp2cα cKO embryos. Whereas deletion of PP2Acα does not affect the proliferation of RGPs, it significantly impairs the generation of late-born neurons. We find complete loss of apical adherens junctions (AJs) in the ventricular membrane in Ppp2cα cKO cortices. We observe abundant colocalization for N-cadherin and PP2Acα in control AJs. Moreover, in vitro analysis reveals direct interactions of N-cadherin to PP2Acα and to β-catenin. Overall, this study not only uncovers a novel function of PP2Acα in retaining RGPs into the VZ but also demonstrates the impact of PP2A-dependent retention of RGPs on the generation for late-born neurons.
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Affiliation(s)
- Chaoli Huang
- State Key Laboratory of Pharmaceutical Biotechnology, MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Institute for Brain Sciences, Nanjing University, Nanjing 210061, China
| | - Tingting Liu
- State Key Laboratory of Pharmaceutical Biotechnology, MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Institute for Brain Sciences, Nanjing University, Nanjing 210061, China
| | - Qihui Wang
- State Key Laboratory of Pharmaceutical Biotechnology, MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Institute for Brain Sciences, Nanjing University, Nanjing 210061, China
| | - Weikang Hou
- State Key Laboratory of Pharmaceutical Biotechnology, MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Institute for Brain Sciences, Nanjing University, Nanjing 210061, China
| | - Cuihua Zhou
- Department of Anesthesiology, The Second Affiliated Changzhou People's Hospital of Nanjing Medical University, Changzhou 213000, China
| | - Zeyuan Song
- Department of Anesthesiology, The Second Affiliated Changzhou People's Hospital of Nanjing Medical University, Changzhou 213000, China
| | - Yun Stone Shi
- State Key Laboratory of Pharmaceutical Biotechnology, MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Institute for Brain Sciences, Nanjing University, Nanjing 210061, China
| | - Xiang Gao
- State Key Laboratory of Pharmaceutical Biotechnology, MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Institute for Brain Sciences, Nanjing University, Nanjing 210061, China
| | - Guiquan Chen
- State Key Laboratory of Pharmaceutical Biotechnology, MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Institute for Brain Sciences, Nanjing University, Nanjing 210061, China
| | - Zhenyu Yin
- Department of Geriatric, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing 210008, China
| | - Yimin Hu
- Department of Anesthesiology, The Second Affiliated Changzhou People's Hospital of Nanjing Medical University, Changzhou 213000, China
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Elewa A, Shirayama M, Kaymak E, Harrison PF, Powell DR, Du Z, Chute CD, Woolf H, Yi D, Ishidate T, Srinivasan J, Bao Z, Beilharz TH, Ryder SP, Mello CC. POS-1 Promotes Endo-mesoderm Development by Inhibiting the Cytoplasmic Polyadenylation of neg-1 mRNA. Dev Cell 2015; 34:108-18. [PMID: 26096734 DOI: 10.1016/j.devcel.2015.05.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 04/17/2015] [Accepted: 05/27/2015] [Indexed: 12/01/2022]
Abstract
The regulation of mRNA translation is of fundamental importance in biological mechanisms ranging from embryonic axis specification to the formation of long-term memory. POS-1 is one of several CCCH zinc-finger RNA-binding proteins that regulate cell fate specification during C. elegans embryogenesis. Paradoxically, pos-1 mutants exhibit striking defects in endo-mesoderm development but have wild-type distributions of SKN-1, a key determinant of endo-mesoderm fates. RNAi screens for pos-1 suppressors identified genes encoding the cytoplasmic poly(A)-polymerase homolog GLD-2, the Bicaudal-C homolog GLD-3, and the protein NEG-1. We show that NEG-1 localizes in anterior nuclei, where it negatively regulates endo-mesoderm fates. In posterior cells, POS-1 binds the neg-1 3' UTR to oppose GLD-2 and GLD-3 activities that promote NEG-1 expression and cytoplasmic lengthening of the neg-1 mRNA poly(A) tail. Our findings uncover an intricate series of post-transcriptional regulatory interactions that, together, achieve precise spatial expression of endo-mesoderm fates in C. elegans embryos.
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Affiliation(s)
- Ahmed Elewa
- Program in Molecular Medicine, RNA Therapeutics Institute and Howard Hughes Medical Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA
| | - Masaki Shirayama
- Program in Molecular Medicine, RNA Therapeutics Institute and Howard Hughes Medical Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA
| | - Ebru Kaymak
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Paul F Harrison
- Victorian Bioinformatics Consortium, Monash University, Clayton, Victoria 3800, Australia; Life Sciences Computation Centre, Victorian Life Sciences Computation Initiative, Carlton, Victoria 3053, Australia
| | - David R Powell
- Victorian Bioinformatics Consortium, Monash University, Clayton, Victoria 3800, Australia; Life Sciences Computation Centre, Victorian Life Sciences Computation Initiative, Carlton, Victoria 3053, Australia
| | - Zhuo Du
- Developmental Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Christopher D Chute
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Life Science and Bioengineering Center, Gateway Park, 60 Prescott Street, Worcester, MA 01605, USA
| | - Hannah Woolf
- Program in Molecular Medicine, RNA Therapeutics Institute and Howard Hughes Medical Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA
| | - Dongni Yi
- Program in Molecular Medicine, RNA Therapeutics Institute and Howard Hughes Medical Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA
| | - Takao Ishidate
- Program in Molecular Medicine, RNA Therapeutics Institute and Howard Hughes Medical Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA
| | - Jagan Srinivasan
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Life Science and Bioengineering Center, Gateway Park, 60 Prescott Street, Worcester, MA 01605, USA
| | - Zhirong Bao
- Developmental Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Traude H Beilharz
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Sean P Ryder
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Craig C Mello
- Program in Molecular Medicine, RNA Therapeutics Institute and Howard Hughes Medical Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA.
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Spiró Z, Gönczy P. Polarity-dependent asymmetric distribution and MEX-5/6-mediated translational activation of the Era-1 mRNA in C. elegans embryos. PLoS One 2015; 10:e0120984. [PMID: 25821955 PMCID: PMC4378847 DOI: 10.1371/journal.pone.0120984] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 02/09/2015] [Indexed: 11/18/2022] Open
Abstract
The early C. elegans embryo is an attractive model system to investigate fundamental developmental processes. With the exception of mex-3 mRNA, maternally contributed mRNAs are thought to be distributed uniformly in the one-cell embryo. Here, we report and characterize the striking distribution of the mRNA encoding the novel protein ERA-1. We found that era-1 mRNA is enriched in the anterior of the one-cell embryo and present solely in anterior blastomeres thereafter. Although era-1 is not an essential gene, we uncovered that era-1 null mutant embryos are sensitive to slight impairment of embryonic polarity. We found that the asymmetric distribution of era-1 mRNA depends on anterior-posterior polarity cues and on the era-1 3’UTR. Similarly to the era-1 mRNA, the YFP-ERA-1 protein is enriched in anterior blastomeres. Interestingly, we found that the RNA-binding protein MEX-5 is required for era-1 mRNA asymmetry. Furthermore, we show that MEX-5, together with its partially redundant partner MEX-6, are needed to activate era-1 mRNA translation in anterior blastomeres. These findings lead us to propose that MEX-5/6–mediated regulation of era-1 mRNA contributes to robust embryonic development.
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Affiliation(s)
- Zoltán Spiró
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL) Lausanne, Lausanne, Switzerland
| | - Pierre Gönczy
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL) Lausanne, Lausanne, Switzerland
- * E-mail:
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Aburatani S. Network inference of pal-1 lineage-specific regulation in the C. elegans embryo by structural equation modeling. Bioinformation 2012; 8:652-7. [PMID: 23055605 PMCID: PMC3449367 DOI: 10.6026/97320630008652] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 07/07/2012] [Indexed: 01/06/2023] Open
Abstract
The elucidation of spatial and temporal control during developmental stages is one of the central tasks for systems biology, and a variety of intracellular factors are known as regulators for specific gene expression. The activity information of those various factors is not directly reflected in their gene expression profiles. Hence, a method based on Structural Equation Modeling (SEM) is described. SEM can include the latent variables within the constructed model and infer the relationships among latent and observed variables, as a network model. An improved SEM approach for the construction of an optimal model is applied to infer the regulatory network for the determination of C lineage fate in C. elegans development. The inferred network model shows that the 13 analysed transcription factor genes were regulated by several other factors in addition to pal-1 expression. The other regulatory factors are those involved in protein accumulation and localization as important regulatory factors for normal development. Those regulatory factors were regulated sequentially in the network model. The regulation of the known pal-1 regulated genes was dependent on this sequential control of the regulatory factors. The interpretation of the network model shows insights to the complex regulation occurring during the C lineage determination by pal-1.
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Affiliation(s)
- Sachiyo Aburatani
- Computational Biology Research Center, National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koto-ku, Tokyo, Japan
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Kronja I, Orr-Weaver TL. Translational regulation of the cell cycle: when, where, how and why? Philos Trans R Soc Lond B Biol Sci 2012; 366:3638-52. [PMID: 22084390 DOI: 10.1098/rstb.2011.0084] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Translational regulation contributes to the control of archetypal and specialized cell cycles, such as the meiotic and early embryonic cycles. Late meiosis and early embryogenesis unfold in the absence of transcription, so they particularly rely on translational repression and activation of stored maternal mRNAs. Here, we present examples of cell cycle regulators that are translationally controlled during different cell cycle and developmental transitions in model organisms ranging from yeast to mouse. Our focus also is on the RNA-binding proteins that affect cell cycle progression by recognizing special features in untranslated regions of mRNAs. Recent research highlights the significance of the cytoplasmic polyadenylation element-binding protein (CPEB). CPEB determines polyadenylation status, and consequently translational efficiency, of its target mRNAs in both transcriptionally active somatic cells as well as in transcriptionally silent mature Xenopus oocytes and early embryos. We discuss the role of CPEB in mediating the translational timing and in some cases spindle-localized translation of critical regulators of Xenopus oogenesis and early embryogenesis. We conclude by outlining potential directions and approaches that may provide further insights into the translational control of the cell cycle.
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Affiliation(s)
- Iva Kronja
- Whitehead Institute and Department of Biology, Massachusetts Institute of Technology, Nine Cambridge Center, Cambridge, MA 02142, USA
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Abstract
Cell polarity is essential for cells to divide asymmetrically, form spatially restricted subcellular structures and participate in three-dimensional multicellular organization. PAR proteins are conserved polarity regulators that function by generating cortical landmarks that establish dynamic asymmetries in the distribution of effector proteins. Here, we review recent findings on the role of PAR proteins in cell polarity in C. elegans and Drosophila, and emphasize the links that exist between PAR networks and cytoskeletal proteins that both regulate PAR protein localization and act as downstream effectors to elaborate polarity within the cell.
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Affiliation(s)
- Jeremy Nance
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute for Biomolecular Medicine, NYU School of Medicine, 540 First Avenue, New York, NY 10016, USA.
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