scholarly journals Regulation of global translation during the cell cycle

2018 ◽  
Author(s):  
Vilte Stonyte ◽  
Erik Boye ◽  
Beáta Grallert
Keyword(s):  
Cell Cycle ◽  
Stress Responses ◽  
Mammalian Cells ◽  
Single Cells ◽  
Initiation Factor ◽  
Temperature Sensitive ◽  
Eif2α Phosphorylation ◽  
Cell Cycle Phases ◽  
General Translation ◽  
Global Translation

AbstractIt is generally accepted that global translation varies during the cell cycle and is low in mitosis. However, addressing this issue is challenging because it involves cell synchronization, which evokes stress responses which, in turn, affect translation rates. Here we have used two approaches to measure global translation rates in different cell-cycle phases. First, synchrony in different cell-cycle phases was obtained involving the same stress, by using temperature-sensitive mutants. Second, translation and DNA content were measured by flow cytometry in exponentially growing, single cells. We found no major variation in global translation rates through the cell cycle in either fission-yeast or mammalian cells. We also measured phosphorylation of eukaryotic initiation factor-2α, an event thought to downregulate global translation in mitosis. In contrast with the prevailing view, eIF2α phosphorylation correlated poorly with downregulation of general translation and ectopically induced eIF2α phosphorylation inhibited general translation only at high levels.

scholarly journals A temperature-sensitive cell-cycle mutant of mammalian cells, tsJT16, is defective in a function operating soon after growth stimulation.

1990 ◽  
Vol 15 (1) ◽  
pp. 39-45 ◽  
Author(s):  
Tsuyoshi Takasuka ◽  
Jun Ninomiya-Tsuji ◽  
Mihoko Sakayama ◽  
Sadahiko Ishibashi ◽  
Toshinori Ide
Keyword(s):  
Cell Cycle ◽  
Mammalian Cells ◽  
Growth Stimulation ◽  
Temperature Sensitive ◽  
Sensitive Cell

scholarly journals Analysis of cell cycle phases and progression in cultured mammalian cells

Methods ◽  
2007 ◽  
Vol 41 (2) ◽  
pp. 143-150 ◽  
Author(s):  
Christoph Schorl ◽  
John M. Sedivy
Keyword(s):  
Cell Cycle ◽  
Mammalian Cells ◽  
Cell Cycle Phases

scholarly journals GCN2 phosphorylation of eIF2α activates NF-κB in response to UV irradiation

2005 ◽  
Vol 385 (2) ◽  
pp. 371-380 ◽  
Author(s):  
Hao-Yuan JIANG ◽  
Ronald C. WEK
Keyword(s):  
Uv Irradiation ◽  
Mammalian Cells ◽  
Transcriptional Control ◽  
Control Cell ◽  
Nuclear Factor Κb ◽  
Initiation Factor ◽  
Α Subunit ◽  
Eif2α Phosphorylation ◽  
Eif2α Kinase ◽  
Secondary Function

In response to UV irradiation, mammalian cells elicit a gene expression programme designed to repair damage and control cell proliferation and apoptosis. Important members of this stress response include the NF-κB (nuclear factor-κB) family. However, the mechanisms by which UV irradiation activates NF-κB are not well understood. In eukaryotes, a variety of environmental stresses are recognized and remediated by a family of protein kinases that phosphorylate the α subunit of eIF2 (eukaryotic initiation factor-2). In the present study we show that NF-κB in MEF (murine embryo fibroblast) cells is activated by UV-C and UV-B irradiation through a mechanism requiring eIF2α phosphorylation. The primary eIF2α kinase in response to UV is GCN2 (general control non-derepressible-2), with PEK/PERK (pancreatic eIF2α kinase/RNA-dependent-protein-kinase-like endoplasmic-reticulum kinase) carrying out a secondary function. Our studies indicate that lowered protein synthesis accompanying eIF2α phosphorylation, combined with eIF2α kinase-independent turnover of IκBα (inhibitor of κBα), reduces the levels of IκBα in response to UV irradiation. Release of NF-κB from the inhibitory IκBα would facilitate NF-κB entry into the nucleus and targeted transcriptional control. We also find that loss of GCN2 in MEF cells significantly enhances apoptosis in response to UV exposure similar to that measured in cells deleted for the RelA/p65 subunit of NF-κB. These results demonstrate that GCN2 is central to recognition of UV stress, and that eIF2α phosphorylation provides resistance to apoptosis in response to this environmental insult.

scholarly journals Heat production of mammalian cells at different cell-cycle phases

1982 ◽  
Vol 7 (4) ◽  
pp. 209-213 ◽  
Author(s):  
C. Loesberg ◽  
J.C. van Miltenburg ◽  
R. van Wuk
Keyword(s):  
Cell Cycle ◽  
Heat Production ◽  
Mammalian Cells ◽  
Cell Cycle Phases

scholarly journals Reovirus Induces and Benefits from an Integrated Cellular Stress Response

2006 ◽  
Vol 80 (4) ◽  
pp. 2019-2033 ◽  
Author(s):  
Jennifer A. Smith ◽  
Stephen C. Schmechel ◽  
Arvind Raghavan ◽  
Michelle Abelson ◽  
Cavan Reilly ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Stress Response ◽  
Stress Responses ◽  
Cellular Stress Response ◽  
Initiation Factor ◽  
Viral Protein Synthesis ◽  
Protein Levels ◽  
Eif2α Phosphorylation ◽  
Infected Cells ◽  
Reovirus Replication

ABSTRACT Following infection with most reovirus strains, viral protein synthesis is robust, even when cellular translation is inhibited. To gain further insight into pathways that regulate translation in reovirus-infected cells, we performed a comparative microarray analysis of cellular gene expression following infection with two strains of reovirus that inhibit host translation (clone 8 and clone 87) and one strain that does not (Dearing). Infection with clone 8 and clone 87 significantly increased the expression of cellular genes characteristic of stress responses, including the integrated stress response. Infection with these same strains decreased transcript and protein levels of P58IPK, the cellular inhibitor of the eukaryotic initiation factor 2α (eIF2α) kinases PKR and PERK. Since infection with host shutoff-inducing strains of reovirus impacted cellular pathways that control eIF2α phosphorylation and unphosphorylated eIF2α is required for translation initiation, we examined reovirus replication in a variety of cell lines with mutations that impact eIF2α phosphorylation. Our results revealed that reovirus replication is more efficient in the presence of eIF2α kinases and phosphorylatable eIF2α. When eIF2α is phosphorylated, it promotes the synthesis of ATF4, a transcription factor that controls cellular recovery from stress. We found that the presence of this transcription factor increased reovirus yields 10- to 100-fold. eIF2α phosphorylation also led to the formation of stress granules in reovirus-infected cells. Based on these results, we hypothesize that eIF2α phosphorylation facilitates reovirus replication in two ways—first, by inducing ATF4 synthesis, and second, by creating an environment that places abundant reovirus transcripts at a competitive advantage for limited translational components.

scholarly journals Substrate recognition determinants of human eIF2α phosphatases

2021 ◽  
Author(s):  
George Hodgson ◽  
Antonina Andreeva ◽  
Anne Bertolotti
Keyword(s):  
Mammalian Cells ◽  
Biological Significance ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Wild Type ◽  
Binding Region ◽  
Antagonistic Action ◽  
Catalytic Subunits ◽  
Eif2α Phosphorylation ◽  
Cellular Defence

Phosphorylation of the translation initiation factor eIF2α is a rapid and vital cellular defence against many forms of stress. In mammals, the levels of eIF2α phosphorylation are set through the antagonistic action of four protein kinases and two heterodimeric protein phosphatases. The phosphatases are composed of the catalytic subunit PP1 and one of two related non-catalytic subunits, PPP1R15A or PPP1R15B (R15A or R15B). Attempts at reconstituting recombinant holophosphatases have generated two models, one proposing that substrate recruitment requires the addition of actin, whilst the second proposes that this function is encoded by R15s. The biological relevance of actin in substrate recruitment has not been evaluated. Here we generated a series of truncation mutants and tested their properties in mammalian cells. We show that substrate recruitment is encoded by an evolutionary conserved region in R15s, R15A325-554 and R15B340-639. Actin does not bind these regions establishing that it is not required for substrate recruitment. Activity assays in cells showed that R15A325-674 and R15B340-713, encompassing the substrate-binding region and the PP1 binding-region, exhibit wild-type activity. This study identifies essential regions of R15s and demonstrates they function as substrate receptors. This work will guide the design of future structural studies with biological significance.

scholarly journals Inhibition of a constitutive translation initiation factor 2α phosphatase, CReP, promotes survival of stressed cells

2003 ◽  
Vol 163 (4) ◽  
pp. 767-775 ◽  
Author(s):  
Céline Jousse ◽  
Seiichi Oyadomari ◽  
Isabel Novoa ◽  
Phoebe Lu ◽  
Yuhong Zhang ◽  
...  
Keyword(s):  
Phosphatase Activity ◽  
Translation Initiation ◽  
Mammalian Cells ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Regulatory Subunit ◽  
Gene Encoding ◽  
Eukaryotic Translation ◽  
Eif2α Phosphorylation ◽  
Stressed Cells

Phosphorylation of eukaryotic translation initiation factor 2α (eIF2α) on serine 51 is effected by specific stress-activated protein kinases. eIF2α phosphorylation inhibits translation initiation promoting a cytoprotective gene expression program known as the integrated stress response (ISR). Stress-induced activation of GADD34 feeds back negatively on this pathway by promoting eIF2α dephosphorylation, however, GADD34 mutant cells retain significant eIF2α-directed phosphatase activity. We used a somatic cell genetic approach to identify a gene encoding a novel regulatory subunit of a constitutively active holophosphatase complex that dephosphorylates eIF2α. RNAi of this gene, which we named constitutive repressor of eIF2α phosphorylation (CReP, or PPP1R15B), repressed the constitutive eIF2α-directed phosphatase activity and activated the ISR. CReP RNAi strongly protected mammalian cells against oxidative stress, peroxynitrite stress, and more modestly against accumulation of malfolded proteins in the endoplasmic reticulum. These findings suggest that therapeutic inhibition of eIF2α dephosphorylation by targeting the CReP-protein–phosphatase-1 complex may be used to access the salubrious qualities of the ISR.

scholarly journals CellMAPtracer: A User-Friendly Tracking Tool for Long-Term Migratory and Proliferating Cells Associated with FUCCI Systems

Cells ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 469
Author(s):  
Salim Ghannoum ◽  
Kamil Antos ◽  
Waldir Leoncio Netto ◽  
Cecil Gomes ◽  
Alvaro Köhn-Luque ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Biology ◽  
Imaging Techniques ◽  
Tracking System ◽  
Single Cells ◽  
Automated Tracking ◽  
Dividing Cells ◽  
Cell Cycle Phases ◽  
User Friendly

Cell migration is a fundamental biological process of key importance in health and disease. Advances in imaging techniques have paved the way to monitor cell motility. An ever-growing collection of computational tools to track cells has improved our ability to analyze moving cells. One renowned goal in the field is to provide tools that track cell movement as comprehensively and automatically as possible. However, fully automated tracking over long intervals of time is challenged by dividing cells, thus calling for a combination of automated and supervised tracking. Furthermore, after the emergence of various experimental tools to monitor cell-cycle phases, it is of relevance to integrate the monitoring of cell-cycle phases and motility. We developed CellMAPtracer, a multiplatform tracking system that achieves that goal. It can be operated as a conventional, automated tracking tool of single cells in numerous imaging applications. However, CellMAPtracer also allows adjusting tracked cells in a semiautomated supervised fashion, thereby improving the accuracy and facilitating the long-term tracking of migratory and dividing cells. CellMAPtracer is available with a user-friendly graphical interface and does not require any coding or programming skills. CellMAPtracer is compatible with two- and three-color fluorescent ubiquitination-based cell-cycle indicator (FUCCI) systems and allows the user to accurately monitor various migration parameters throughout the cell cycle, thus having great potential to facilitate new discoveries in cell biology.

Sign in / Sign up

Export Citation Format

Share Document