1
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Körner M, Meyer SR, Marincola G, Kern MJ, Grimm C, Schuelein-Voelk C, Fischer U, Hofmann K, Buchberger A. The FAM104 proteins VCF1/2 promote the nuclear localization of p97/VCP. eLife 2023; 12:e92409. [PMID: 37713320 PMCID: PMC10541173 DOI: 10.7554/elife.92409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Accepted: 09/10/2023] [Indexed: 09/17/2023] Open
Abstract
The ATPase p97 (also known as VCP, Cdc48) has crucial functions in a variety of important cellular processes such as protein quality control, organellar homeostasis, and DNA damage repair, and its de-regulation is linked to neuromuscular diseases and cancer. p97 is tightly controlled by numerous regulatory cofactors, but the full range and function of the p97-cofactor network is unknown. Here, we identify the hitherto uncharacterized FAM104 proteins as a conserved family of p97 interactors. The two human family members VCP nuclear cofactor family member 1 and 2 (VCF1/2) bind p97 directly via a novel, alpha-helical motif and associate with p97-UFD1-NPL4 and p97-UBXN2B complexes in cells. VCF1/2 localize to the nucleus and promote the nuclear import of p97. Loss of VCF1/2 results in reduced nuclear p97 levels, slow growth, and hypersensitivity to chemical inhibition of p97 in the absence and presence of DNA damage, suggesting that FAM104 proteins are critical regulators of nuclear p97 functions.
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Affiliation(s)
- Maria Körner
- University of Würzburg, Biocenter, Chair of Biochemistry IWürzburgGermany
| | - Susanne R Meyer
- University of Würzburg, Biocenter, Chair of Biochemistry IWürzburgGermany
| | | | - Maximilian J Kern
- Department of Molecular Cell Biology, Max Planck Institute of BiochemistryMartinsriedGermany
| | - Clemens Grimm
- University of Würzburg, Biocenter, Chair of Biochemistry IWürzburgGermany
| | | | - Utz Fischer
- University of Würzburg, Biocenter, Chair of Biochemistry IWürzburgGermany
| | - Kay Hofmann
- Institute of Genetics, University of CologneCologneGermany
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2
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Faienza F, Polverino F, Rajendraprasad G, Milletti G, Hu Z, Colella B, Gargano D, Strappazzon F, Rizza S, Vistesen MV, Luo Y, Antonioli M, Cianfanelli V, Ferraina C, Fimia GM, Filomeni G, De Zio D, Dengjel J, Barisic M, Guarguaglini G, Di Bartolomeo S, Cecconi F. AMBRA1 phosphorylation by CDK1 and PLK1 regulates mitotic spindle orientation. Cell Mol Life Sci 2023; 80:251. [PMID: 37584777 PMCID: PMC10432340 DOI: 10.1007/s00018-023-04878-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 06/27/2023] [Accepted: 07/17/2023] [Indexed: 08/17/2023]
Abstract
AMBRA1 is a crucial factor for nervous system development, and its function has been mainly associated with autophagy. It has been also linked to cell proliferation control, through its ability to regulate c-Myc and D-type cyclins protein levels, thus regulating G1-S transition. However, it remains still unknown whether AMBRA1 is differentially regulated during the cell cycle, and if this pro-autophagy protein exerts a direct role in controlling mitosis too. Here we show that AMBRA1 is phosphorylated during mitosis on multiple sites by CDK1 and PLK1, two mitotic kinases. Moreover, we demonstrate that AMBRA1 phosphorylation at mitosis is required for a proper spindle function and orientation, driven by NUMA1 protein. Indeed, we show that the localization and/or dynamics of NUMA1 are strictly dependent on AMBRA1 presence, phosphorylation and binding ability. Since spindle orientation is critical for tissue morphogenesis and differentiation, our findings could account for an additional role of AMBRA1 in development and cancer ontogenesis.
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Affiliation(s)
- Fiorella Faienza
- Cell Stress and Survival Group, Center for Autophagy, Recycling and Disease (CARD), Danish Cancer Institute, Copenhagen, Denmark
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | - Federica Polverino
- Institute of Molecular Biology and Pathology, CNR National Research Council, Rome, Italy
| | | | - Giacomo Milletti
- Department of Pediatric Hemato-Oncology and Cell and Gene Therapy, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
- DNA Replication and Cancer Group, Danish Cancer Institute, 2100, Copenhagen, Denmark
| | - Zehan Hu
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Barbara Colella
- Department of Biosciences and Territory, University of Molise, Pesche, Italy
| | - Deborah Gargano
- Department of Biosciences and Territory, University of Molise, Pesche, Italy
| | - Flavie Strappazzon
- IRCCS Fondazione Santa Lucia, Rome, Italy
- Physiopathologie et Génétique du Neurone et du Muscle, UMR5261, U1315, Institut NeuroMyogène, Univ Lyon, Univ Lyon 1, CNRS, INSERM, 69008, Lyon, France
| | - Salvatore Rizza
- Redox Biology Group, Danish Cancer Institute, Copenhagen, Denmark
| | - Mette Vixø Vistesen
- Cell Stress and Survival Group, Center for Autophagy, Recycling and Disease (CARD), Danish Cancer Institute, Copenhagen, Denmark
| | - Yonglun Luo
- Lars Bolund Institute of Regenerative Medicine and Qingdao-Europe Advanced Institute for Life Sciences, BGI Research, Shenzhen, China
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Manuela Antonioli
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
- National Institute for Infectious Diseases, IRCSS "L. Spallanzani", Rome, Italy
| | - Valentina Cianfanelli
- Department of Pediatric Hemato-Oncology and Cell and Gene Therapy, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
- Department of Science, University "ROMA TRE", 00146, Rome, Italy
- Department of Woman and Child Health and Public Health, Gynecologic Oncology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy
| | - Caterina Ferraina
- Department of Pediatric Hemato-Oncology and Cell and Gene Therapy, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Gian Maria Fimia
- National Institute for Infectious Diseases, IRCSS "L. Spallanzani", Rome, Italy
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
| | - Giuseppe Filomeni
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
- Redox Biology Group, Danish Cancer Institute, Copenhagen, Denmark
- Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark
| | - Daniela De Zio
- Melanoma Research Team, Danish Cancer Institute, Copenhagen, Denmark
- Department of Drug Design and Pharmacology, University Of Copenhagen, Copenhagen, Denmark
| | - Joern Dengjel
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Marin Barisic
- Cell Division and Cytoskeleton, Danish Cancer Institute, Copenhagen, Denmark
- Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Giulia Guarguaglini
- Institute of Molecular Biology and Pathology, CNR National Research Council, Rome, Italy
| | | | - Francesco Cecconi
- Cell Stress and Survival Group, Center for Autophagy, Recycling and Disease (CARD), Danish Cancer Institute, Copenhagen, Denmark.
- Università Cattolica del Sacro Cuore and Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy.
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3
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Lechler T, Mapelli M. Spindle positioning and its impact on vertebrate tissue architecture and cell fate. Nat Rev Mol Cell Biol 2021; 22:691-708. [PMID: 34158639 PMCID: PMC10544824 DOI: 10.1038/s41580-021-00384-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/11/2021] [Indexed: 12/18/2022]
Abstract
In multicellular systems, oriented cell divisions are essential for morphogenesis and homeostasis as they determine the position of daughter cells within the tissue and also, in many cases, their fate. Early studies in invertebrates led to the identification of conserved core mechanisms of mitotic spindle positioning centred on the Gαi-LGN-NuMA-dynein complex. In recent years, much has been learnt about the way this complex functions in vertebrate cells. In particular, studies addressed how the Gαi-LGN-NuMA-dynein complex dynamically crosstalks with astral microtubules and the actin cytoskeleton, and how it is regulated to orient the spindle according to cellular and tissue-wide cues. We have also begun to understand how dynein motors and actin regulators interact with mechanosensitive adhesion molecules sensing extracellular mechanical stimuli, such as cadherins and integrins, and with signalling pathways so as to respond to extracellular cues instructing the orientation of the division axis in vivo. In this Review, with the focus on epithelial tissues, we discuss the molecular mechanisms of mitotic spindle orientation in vertebrate cells, and how this machinery is regulated by epithelial cues and extracellular signals to maintain tissue cohesiveness during mitosis. We also outline recent knowledge of how spindle orientation impacts tissue architecture in epithelia and its emerging links to the regulation of cell fate decisions. Finally, we describe how defective spindle orientation can be corrected or its effects eliminated in tissues under physiological conditions, and the pathological implications associated with spindle misorientation.
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Affiliation(s)
- Terry Lechler
- Department of Dermatology, Duke University Medical Center, Durham, NC, USA.
- Department of Cell Biology, Duke University Medical Center, Durham, NC, USA.
| | - Marina Mapelli
- Department of Experimental Oncology, European Institute of Oncology IRCCS, Milan, Italy.
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4
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Ong JY, Bradley MC, Torres JZ. Phospho-regulation of mitotic spindle assembly. Cytoskeleton (Hoboken) 2020; 77:558-578. [PMID: 33280275 PMCID: PMC7898546 DOI: 10.1002/cm.21649] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 10/08/2020] [Accepted: 12/02/2020] [Indexed: 12/23/2022]
Abstract
The assembly of the bipolar mitotic spindle requires the careful orchestration of a myriad of enzyme activities like protein posttranslational modifications. Among these, phosphorylation has arisen as the principle mode for spatially and temporally activating the proteins involved in early mitotic spindle assembly processes. Here, we review key kinases, phosphatases, and phosphorylation events that regulate critical aspects of these processes. We highlight key phosphorylation substrates that are important for ensuring the fidelity of centriole duplication, centrosome maturation, and the establishment of the bipolar spindle. We also highlight techniques used to understand kinase-substrate relationships and to study phosphorylation events. We conclude with perspectives on the field of posttranslational modifications in early mitotic spindle assembly.
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Affiliation(s)
- Joseph Y Ong
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California, USA
| | - Michelle C Bradley
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California, USA
| | - Jorge Z Torres
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California, USA.,Molecular Biology Institute, University of California, Los Angeles, California, USA.,Jonsson Comprehensive Cancer Center, University of California, Los Angeles, California, USA
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5
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Hoffmann I. Centrosomes in mitotic spindle assembly and orientation. Curr Opin Struct Biol 2020; 66:193-198. [PMID: 33296732 DOI: 10.1016/j.sbi.2020.11.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 10/30/2020] [Accepted: 11/02/2020] [Indexed: 12/24/2022]
Abstract
The centrosome is present in most animal cells and functions as the major microtubule-organizing center to ensure faithful chromosome segregation during cell division. As cells transition from interphase to mitosis, the duplicated centrosomes separate and move to opposite sides of the cell where the spindle assembles. Centrosomes not only nucleate but also organize microtubules of the mitotic spindle. The mitotic spindle is anchored to the cell cortex by the astral microtubules emanating from the centrosomes. Proper orientation of the mitotic spindle is essential for correct cell division. Centrosome-localized polo-like kinase Plk1 has been linked to regulation of proper spindle orientation. A number of proteins including MISP and NuMA have been implicated in the Plk1-mediated spindle orientation pathway.
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Affiliation(s)
- Ingrid Hoffmann
- Cell Cycle Control and Carcinogenesis, German Cancer Research Center, F045, Im Neuenheimer Feld 242, 69120 Heidelberg, Germany.
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6
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Abstract
p97 belongs to the functional diverse superfamily of AAA+ (ATPases Associated with diverse cellular Activities) ATPases and is characterized by an N-terminal regulatory domain and two stacked hexameric ATPase domains forming a central protein conducting channel. p97 is highly versatile and has key functions in maintaining protein homeostasis including protein quality control mechanisms like the ubiquitin proteasome system (UPS) and autophagy to disassemble polyubiquitylated proteins from chromatin, membranes, macromolecular protein complexes and aggregates which are either degraded by the proteasome or recycled. p97 can use energy derived from ATP hydrolysis to catalyze substrate unfolding and threading through its central channel. The function of p97 in a large variety of different cellular contexts is reflected by its simultaneous association with different cofactors, which are involved in substrate recognition and processing, thus leading to the formation of transient multi-protein complexes. Dysregulation in protein homeostasis and proteotoxic stress are often involved in the development of cancer and neurological diseases and targeting the UPS including p97 in cancer is a well-established pharmacological strategy. In this chapter we will describe structural and functional aspects of the p97 interactome in regulating diverse cellular processes and will discuss the role of p97 in targeted cancer therapy.
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7
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Figuerola-Conchas A, Saarbach J, Daguer JP, Cieren A, Barluenga S, Winssinger N, Gotta M. Small-Molecule Modulators of the ATPase VCP/p97 Affect Specific p97 Cellular Functions. ACS Chem Biol 2020; 15:243-253. [PMID: 31790201 DOI: 10.1021/acschembio.9b00832] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
VCP/p97 belongs to the AAA+ ATPase family and has an essential role in several cellular processes ranging from cell division to protein homeostasis. Compounds targeting p97 inhibit the main ATPase domain and cause cell death. Here, using PNA-encoded chemical libraries, we have identified two small molecules that target the regulatory domain of p97, comprising the N-terminal and the D1 ATPase domains, and do not cause cell death. One molecule, NW1028, inhibits the degradation of a p97-dependent reporter, whereas the other, NW1030, increases it. ATPase assays show that NW1028 and NW1030 do not affect the main catalytic domain of p97. Mapping of the binding site using a photoaffinity conjugate points to a cleft at the interface of the N-terminal and the D1 ATPase domains. We have therefore discovered two new compounds that bind to the regulatory domain of p97 and modulate specific p97 cellular functions. Using these compounds, we have revealed a role for p97 in the regulation of mitotic spindle orientation in HeLa cells.
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Affiliation(s)
- Ainoa Figuerola-Conchas
- Department of Cell Physiology and Metabolism, University of Geneva, 1211 Geneva 4, Switzerland
- National Centre of Competence in Research (NCCR) in Chemical Biology, University of Geneva, Geneva, Switzerland
| | - Jacques Saarbach
- Department of Cell Physiology and Metabolism, University of Geneva, 1211 Geneva 4, Switzerland
- National Centre of Competence in Research (NCCR) in Chemical Biology, University of Geneva, Geneva, Switzerland
| | - Jean-Pierre Daguer
- National Centre of Competence in Research (NCCR) in Chemical Biology, University of Geneva, Geneva, Switzerland
- Department of Organic Chemistry, University of Geneva, 1211 Geneva 4, Switzerland
| | - Adeline Cieren
- Department of Cell Physiology and Metabolism, University of Geneva, 1211 Geneva 4, Switzerland
- National Centre of Competence in Research (NCCR) in Chemical Biology, University of Geneva, Geneva, Switzerland
| | - Sofia Barluenga
- National Centre of Competence in Research (NCCR) in Chemical Biology, University of Geneva, Geneva, Switzerland
- Department of Organic Chemistry, University of Geneva, 1211 Geneva 4, Switzerland
| | - Nicolas Winssinger
- National Centre of Competence in Research (NCCR) in Chemical Biology, University of Geneva, Geneva, Switzerland
- Department of Organic Chemistry, University of Geneva, 1211 Geneva 4, Switzerland
| | - Monica Gotta
- Department of Cell Physiology and Metabolism, University of Geneva, 1211 Geneva 4, Switzerland
- National Centre of Competence in Research (NCCR) in Chemical Biology, University of Geneva, Geneva, Switzerland
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8
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Bondaz A, Cirillo L, Meraldi P, Gotta M. Cell polarity-dependent centrosome separation in the C. elegans embryo. J Cell Biol 2019; 218:4112-4126. [PMID: 31645459 PMCID: PMC6891102 DOI: 10.1083/jcb.201902109] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 07/10/2019] [Accepted: 09/06/2019] [Indexed: 12/30/2022] Open
Abstract
Bondaz et al. show that in C. elegans embryos, the microtubule depolymerase KLP-7/MCAK is required for efficient centrosome separation in the somatic AB cell, but not the germline P1 cell. This difference in spindle assembly depends on cell polarity via the mitotic kinase PLK1. In animal cells, faithful chromosome segregation depends on the assembly of a bipolar spindle driven by the timely separation of the two centrosomes. Here we took advantage of the highly stereotypical cell divisions in Caenorhabditis elegans embryos to identify new regulators of centrosome separation. We find that at the two-cell stage, the somatic AB cell initiates centrosome separation later than the germline P1 cell. This difference is strongly exacerbated by the depletion of the kinesin-13 KLP-7/MCAK, resulting in incomplete centrosome separation at NEBD in AB but not P1. Our genetic and cell biology data indicate that this phenotype depends on cell polarity via the enrichment in AB of the mitotic kinase PLK-1, which itself limits the cortical localization of the dynein-binding NuMA orthologue LIN-5. We postulate that the timely separation of centrosomes is regulated in a cell type–dependent manner.
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Affiliation(s)
- Alexandra Bondaz
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Translational Research Centre in Onco-hematology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Luca Cirillo
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Translational Research Centre in Onco-hematology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Patrick Meraldi
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland .,Translational Research Centre in Onco-hematology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Monica Gotta
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland .,Translational Research Centre in Onco-hematology, Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Swiss National Centre for Competence in Research in Chemical Biology, University of Geneva, Geneva, Switzerland
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9
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Franco M, Carmena A. Eph signaling in mitotic spindle orientation: what´s your angle here? Cell Cycle 2019; 18:2590-2597. [PMID: 31475621 DOI: 10.1080/15384101.2019.1658479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
The orientation of the mitotic spindle is a crucial process during development and adult tissue homeostasis and multiple mechanisms have been shown to intrinsically regulate this process. However, much less is known about the extrinsic cues involved in modulating spindle orientation. We have recently uncovered a novel function of Eph intercellular signaling in regulating spindle alignment by ultimately ensuring the correct cortical distribution of central components within the intrinsic spindle orientation machinery. Here, we comment on these results, novel questions that they open and potential additional research to address in the future.
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Affiliation(s)
- Maribel Franco
- Developmental Neurobiology Unit, Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas/Universidad Miguel Hernández , Alicante , Spain
| | - Ana Carmena
- Developmental Neurobiology Unit, Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas/Universidad Miguel Hernández , Alicante , Spain
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10
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Kotak S. Mechanisms of Spindle Positioning: Lessons from Worms and Mammalian Cells. Biomolecules 2019; 9:E80. [PMID: 30823600 PMCID: PMC6406873 DOI: 10.3390/biom9020080] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 02/13/2019] [Accepted: 02/18/2019] [Indexed: 02/06/2023] Open
Abstract
Proper positioning of the mitotic spindle is fundamental for specifying the site for cleavage furrow, and thus regulates the appropriate sizes and accurate distribution of the cell fate determinants in the resulting daughter cells during development and in the stem cells. The past couple of years have witnessed tremendous work accomplished in the area of spindle positioning, and this has led to the emergence of a working model unravelling in-depth mechanistic insight of the underlying process orchestrating spindle positioning. It is evident now that the correct positioning of the mitotic spindle is not only guided by the chemical cues (protein⁻protein interactions) but also influenced by the physical nature of the cellular environment. In metazoans, the key players that regulate proper spindle positioning are the actin-rich cell cortex and associated proteins, the ternary complex (Gα/GPR-1/2/LIN-5 in Caenorhabditis elegans, Gαi/Pins/Mud in Drosophila and Gαi1-3/LGN/NuMA in humans), minus-end-directed motor protein dynein and the cortical machinery containing myosin. In this review, I will mainly discuss how the abovementioned components precisely and spatiotemporally regulate spindle positioning by sensing the physicochemical environment for execution of flawless mitosis.
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Affiliation(s)
- Sachin Kotak
- Department of Microbiology and Cell Biology (MCB), Indian Institute of Science (IISc), Bangalore 560012, India.
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11
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Moura M, Conde C. Phosphatases in Mitosis: Roles and Regulation. Biomolecules 2019; 9:E55. [PMID: 30736436 PMCID: PMC6406801 DOI: 10.3390/biom9020055] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 01/31/2019] [Accepted: 02/01/2019] [Indexed: 02/07/2023] Open
Abstract
Mitosis requires extensive rearrangement of cellular architecture and of subcellular structures so that replicated chromosomes can bind correctly to spindle microtubules and segregate towards opposite poles. This process originates two new daughter nuclei with equal genetic content and relies on highly-dynamic and tightly regulated phosphorylation of numerous cell cycle proteins. A burst in protein phosphorylation orchestrated by several conserved kinases occurs as cells go into and progress through mitosis. The opposing dephosphorylation events are catalyzed by a small set of protein phosphatases, whose importance for the accuracy of mitosis is becoming increasingly appreciated. This review will focus on the established and emerging roles of mitotic phosphatases, describe their structural and biochemical properties, and discuss recent advances in understanding the regulation of phosphatase activity and function.
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Affiliation(s)
- Margarida Moura
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
- i3S-Instituto de Investigação e Inovação em Saúde da Universidade do Porto, 4200-135, Porto, Portugal.
- Programa Doutoral em Biologia Molecular e Celular (MCbiology), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, 4050-313 Porto, Portugal.
| | - Carlos Conde
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
- i3S-Instituto de Investigação e Inovação em Saúde da Universidade do Porto, 4200-135, Porto, Portugal.
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12
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Ubiquitin-Independent Disassembly by a p97 AAA-ATPase Complex Drives PP1 Holoenzyme Formation. Mol Cell 2018; 72:766-777.e6. [PMID: 30344098 DOI: 10.1016/j.molcel.2018.09.020] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 08/15/2018] [Accepted: 09/13/2018] [Indexed: 12/12/2022]
Abstract
The functional diversity of protein phosphatase-1 (PP1), with its countless substrates, relies on the ordered assembly of alternative PP1 holoenzymes. Here, we show that newly synthesized PP1 is first held by its partners SDS22 and inhibitor-3 (I3) in an inactive complex, which needs to be disassembled by the p97 AAA-ATPase to promote exchange to substrate specifiers. Unlike p97-mediated degradative processes that require the Ufd1-Npl4 ubiquitin adapters, p97 is targeted to PP1 by p37 and related adapter proteins. Reconstitution with purified components revealed direct interaction of the p37 SEP domain with I3 without the need for ubiquitination, and ATP-driven pulling of I3 into the central channel of the p97 hexamer, which triggers dissociation of I3 and SDS22. Thus, we establish regulatory ubiquitin-independent protein complex disassembly as part of the functional arsenal of p97 and define an unanticipated essential step in PP1 biogenesis that illustrates the molecular challenges of ordered subunit exchange.
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