scholarly journals MEK1 inactivates Myt1 to regulate Golgi membrane fragmentation and mitotic entry in mammalian cells

2012 ◽  
Vol 32 (1) ◽  
pp. 72-85 ◽  
Author(s):  
Julien Villeneuve ◽  
Margherita Scarpa ◽  
Maria Ortega-Bellido ◽  
Vivek Malhotra
Keyword(s):  
Mammalian Cells ◽  
Golgi Membrane ◽  
Mitotic Entry

scholarly journals DjA1 maintains Golgi integrity via interaction with GRASP65

2019 ◽  
Vol 30 (4) ◽  
pp. 478-490 ◽  
Author(s):  
Jie Li ◽  
Danming Tang ◽  
Stephen C. Ireland ◽  
Yanzhuang Wang
Keyword(s):  
Heat Shock ◽  
Membrane Fusion ◽  
Structure Formation ◽  
Mammalian Cells ◽  
Binding Protein ◽  
Golgi Membrane ◽  
Biochemical Methods ◽  
Golgi Fragmentation ◽  
Golgi Structure

In mammalian cells, the Golgi reassembly stacking protein of 65 kDa (GRASP65) has been implicated in both Golgi stacking and ribbon linking by forming trans-oligomers. To better understand its function and regulation, we used biochemical methods to identify the DnaJ homolog subfamily A member 1 (DjA1) as a novel GRASP65-binding protein. In cells, depletion of DjA1 resulted in Golgi fragmentation, short and improperly aligned cisternae, and delayed Golgi reassembly after nocodazole washout. In vitro, immunodepletion of DjA1 from interphase cytosol reduced its activity to enhance GRASP65 oligomerization and Golgi membrane fusion, while adding purified DjA1 enhanced GRASP65 oligomerization. DjA1 is a cochaperone of Heat shock cognate 71-kDa protein (Hsc70), but the activity of DjA1 in Golgi structure formation is independent of its cochaperone activity or Hsc70, rather, through DjA1-GRASP65 interaction to promote GRASP65 oligomerization. Thus, DjA1 interacts with GRASP65 to enhance Golgi structure formation through the promotion of GRASP65 trans-oligomerization.

The Golgi ribbon: mechanisms of maintenance and disassembly during the cell cycle

2020 ◽  
Vol 48 (1) ◽  
pp. 245-256 ◽  
Author(s):  
Inmaculada Ayala ◽  
Fabiola Mascanzoni ◽  
Antonino Colanzi
Keyword(s):  
Signaling Pathways ◽  
Mammalian Cells ◽  
Mitotic Entry ◽  
Daughter Cells ◽  
The Core ◽  
Disassembly Process ◽  
Pathological Conditions ◽  
Golgi Structure ◽  
Golgi Ribbon ◽  
Complex Structural

The Golgi complex (GC) has an essential role in the processing and sorting of proteins and lipids. The GC of mammalian cells is composed of stacks of cisternae connected by membranous tubules to create a continuous network, the Golgi ribbon, whose maintenance requires several core and accessory proteins. Despite this complex structural organization, the Golgi apparatus is highly dynamic, and this property becomes particularly evident during mitosis, when the ribbon undergoes a multistep disassembly process that allows its correct partitioning and inheritance by the daughter cells. Importantly, alterations of the Golgi structure are associated with a variety of physiological and pathological conditions. Here, we review the core mechanisms and signaling pathways involved in both the maintenance and disassembly of the Golgi ribbon, and we also report on the signaling pathways that connect the disassembly of the Golgi ribbon to mitotic entry and progression.

scholarly journals Bistability of mitotic entry and exit switches during open mitosis in mammalian cells

BioEssays ◽  
2016 ◽  
Vol 38 (7) ◽  
pp. 627-643 ◽  
Author(s):  
Nadia Hégarat ◽  
Scott Rata ◽  
Helfrid Hochegger
Keyword(s):  
Mammalian Cells ◽  
Entry And Exit ◽  
Mitotic Entry

scholarly journals Cell cycle regulation of VCIP135 deubiquitinase activity and function in p97/p47-mediated Golgi reassembly

2015 ◽  
Vol 26 (12) ◽  
pp. 2242-2251 ◽  
Author(s):  
Xiaoyan Zhang ◽  
Yanzhuang Wang
Keyword(s):  
Cell Cycle ◽  
Membrane Fusion ◽  
Mammalian Cells ◽  
Membrane Dynamics ◽  
Deubiquitinating Enzyme ◽  
Golgi Membrane ◽  
Interacting Protein ◽  
Daughter Cells ◽  
And Function ◽  
Cycle Regulation

In mammalian cells, the inheritance of the Golgi apparatus into the daughter cells during each cycle of cell division is mediated by a disassembly and reassembly process, and this process is precisely controlled by phosphorylation and ubiquitination. VCIP135 (valosin-containing protein p97/p47 complex–interacting protein, p135), a deubiquitinating enzyme required for p97/p47-mediated postmitotic Golgi membrane fusion, is phosphorylated at multiple sites during mitosis. However, whether phosphorylation directly regulates VCIP135 deubiquitinase activity and Golgi membrane fusion in the cell cycle remains unknown. We show that, in early mitosis, phosphorylation of VCIP135 by Cdk1 at a single residue, S130, is sufficient to inactivate the enzyme and inhibit p97/p47-mediated Golgi membrane fusion. At the end of mitosis, VCIP135 S130 is dephosphorylated, which is accompanied by the recovery of its deubiquitinase activity and Golgi reassembly. Our results demonstrate that phosphorylation and ubiquitination are coordinated via VCIP135 to control Golgi membrane dynamics in the cell cycle.

scholarly journals SLK-dependent activation of ERMs controls LGN–NuMA localization and spindle orientation

2014 ◽  
Vol 205 (6) ◽  
pp. 791-799 ◽  
Author(s):  
Mickael Machicoane ◽  
Cristina A. de Frutos ◽  
Jenny Fink ◽  
Murielle Rocancourt ◽  
Yannis Lombardi ◽  
...  
Keyword(s):  
Mitotic Spindle ◽  
Mammalian Cells ◽  
Molecular Level ◽  
Spindle Orientation ◽  
Cell Cortex ◽  
Mitotic Apparatus ◽  
Mitotic Entry ◽  
Spindle Microtubules ◽  
Force Generator

Mitotic spindle orientation relies on a complex dialog between the spindle microtubules and the cell cortex, in which F-actin has been recently implicated. Here, we report that the membrane–actin linkers ezrin/radixin/moesin (ERMs) are strongly and directly activated by the Ste20-like kinase at mitotic entry in mammalian cells. Using microfabricated adhesive substrates to control the axis of cell division, we found that the activation of ERMs plays a key role in guiding the orientation of the mitotic spindle. Accordingly, impairing ERM activation in apical progenitors of the mouse embryonic neocortex severely disturbed spindle orientation in vivo. At the molecular level, ERM activation promotes the polarized association at the mitotic cortex of leucine-glycine-asparagine repeat protein (LGN) and nuclear mitotic apparatus (NuMA) protein, two essential factors for spindle orientation. We propose that activated ERMs, together with Gαi, are critical for the correct localization of LGN–NuMA force generator complexes and hence for proper spindle orientation.

scholarly journals Roles of aurora-A kinase in mitotic entry and G2 checkpoint in mammalian cells

2002 ◽  
Vol 7 (11) ◽  
pp. 1173-1182 ◽  
Author(s):  
Tomotoshi Marumoto ◽  
Toru Hirota ◽  
Tetsuro Morisaki ◽  
Naoko Kunitoku ◽  
Dongwei Zhang ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Aurora A Kinase ◽  
Aurora A ◽  
Mitotic Entry ◽  
G2 Checkpoint

scholarly journals USP7 couples DNA replication termination to mitotic entry

2018 ◽  
Author(s):  
Antonio Galarreta ◽  
Emilio Lecona ◽  
Pablo Valledor ◽  
Patricia Ubieto ◽  
Vanesa Lafarga ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Chromosome Segregation ◽  
Mechanism Of Action ◽  
Mammalian Cells ◽  
Essential Role ◽  
Premature Termination ◽  
Mitotic Entry ◽  
Entire Cell ◽  
Segregation Of Chromosomes

SUMMARYTo ensure a faithful segregation of chromosomes, DNA must be fully replicated before mitotic entry. However, how cells sense the completion of DNA replication and to what extent this is linked to the activation of the mitotic machinery remains poorly understood. We previously showed that USP7 is a replisome-associated deubiquitinase with an essential role in DNA replication. Here, we reveal that USP7 inhibition leads to the ubiquitination of MCM7, a hallmark of DNA replication termination. In addition, USP7 inhibition leads to the ubiquitination of additional replisome components such as POLD1, which are displaced from replisomes. Surprisingly, this premature termination of DNA replication occurs concomitant to a generalized activation of CDK1 throughout the entire cell cycle, which impairs chromosome segregation and is toxic for mammalian cells. Accordingly, the toxicity of USP7 inhibitors is alleviated by CDK1 inhibition. Our work sheds light into the mechanism of action of USP7 inhibitors and provides evidence to the concept that DNA replication termination is coupled to the activation of the mitotic program.

scholarly journals Phosphorylation and membrane dissociation of the ARF exchange factor GBF1 in mitosis

2010 ◽  
Vol 427 (3) ◽  
pp. 401-412 ◽  
Author(s):  
Yuichi Morohashi ◽  
Zita Balklava ◽  
Matthew Ball ◽  
Helen Hughes ◽  
Martin Lowe
Keyword(s):  
Golgi Apparatus ◽  
Protein Trafficking ◽  
Mammalian Cells ◽  
Cell Cycle Progression ◽  
Brefeldin A ◽  
Secretory Protein ◽  
Golgi Membrane ◽  
Nucleotide Exchange ◽  
Exchange Factor ◽  
Mitotic Cells

Secretory protein trafficking is arrested and the Golgi apparatus fragmented when mammalian cells enter mitosis. These changes are thought to facilitate cell-cycle progression and Golgi inheritance, and are brought about through the actions of mitotically active protein kinases. To better understand how the Golgi apparatus undergoes mitotic fragmentation we have sought to identify novel Golgi targets for mitotic kinases. We report in the present paper the identification of the ARF (ADP-ribosylation factor) exchange factor GBF1 (Golgi-specific brefeldin A-resistant guanine nucleotide-exchange factor 1) as a Golgi phosphoprotein. GBF1 is phosphorylated by CDK1 (cyclin-dependent kinase 1)–cyclin B in mitosis, which results in its dissociation from Golgi membranes. Consistent with a reduced level of GBF1 activity at the Golgi membrane there is a reduction in levels of membrane-associated GTP-bound ARF in mitotic cells. Despite the reduced levels of membrane-bound GBF1 and ARF, COPI (coat protein I) binding to the Golgi membrane appears unaffected in mitotic cells. Surprisingly, this pool of COPI is dependent upon GBF1 for its recruitment to the membrane, suggesting that a low level of GBF1 activity persists in mitosis. We propose that the phosphorylation and membrane dissociation of GBF1 and the consequent reduction in ARF-GTP levels in mitosis are important for changes in Golgi dynamics and possibly other mitotic events mediated through effectors other than the COPI vesicle coat.

scholarly journals The Auto-ubiquitylation of E3 Ubiquitin-protein Ligase Chfr at G2Phase Is Required for Accumulation of Polo-like Kinase 1 and Mitotic Entry in Mammalian Cells

2011 ◽  
Vol 286 (35) ◽  
pp. 30615-30623 ◽  
Author(s):  
Jo-Sun Kim ◽  
Yong-Yea Park ◽  
Sun-Yi Park ◽  
Hyeseon Cho ◽  
Dongmin Kang ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Mitotic Entry ◽  
Ubiquitin Protein Ligase

scholarly journals Myt1 protein kinase is essential for Golgi and ER assembly during mitotic exit

2008 ◽  
Vol 181 (1) ◽  
pp. 89-103 ◽  
Author(s):  
Hiroyuki Nakajima ◽  
Shigenobu Yonemura ◽  
Masayuki Murata ◽  
Nobuhiro Nakamura ◽  
Helen Piwnica-Worms ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Mammalian Cells ◽  
Cyclin B1 ◽  
Membrane Dynamics ◽  
Mitotic Exit ◽  
Negative Regulator ◽  
Unexpected Finding ◽  
Intracellular Membrane ◽  
Mitotic Entry ◽  
Cdc2 Activity

Myt1 was originally identified as an inhibitory kinase for Cdc2 (Cdk1), the master engine of mitosis, and has been thought to function, together with Wee1, as a negative regulator of mitotic entry. In this study, we report an unexpected finding that Myt1 is essential for Golgi and endoplasmic reticulum (ER) assembly during telophase in mammalian cells. Our analyses reveal that both cyclin B1 and cyclin B2 serve as targets of Myt1 for proper Golgi and ER assembly to occur. Thus, our results show that Myt1-mediated suppression of Cdc2 activity is not indispensable for the regulation of a broad range of mitotic events but is specifically required for the control of intracellular membrane dynamics during mitosis.

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