scholarly journals Molecular Cross-talk between MEK1/2 and mTOR Signaling during Recovery of 293 Cells from Hypertonic Stress

2004 ◽  
Vol 279 (44) ◽  
pp. 46023-46034 ◽  
Author(s):  
Susanne Naegele ◽  
Simon J. Morley
Keyword(s):  
Protein Synthesis ◽  
Ribosomal Protein ◽  
Signaling Pathways ◽  
De Novo ◽  
Human Kidney ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Hypertonic Stress ◽  
Salt Shock ◽  
Ribosomal Protein S6

To investigate the role for initiation factor phosphorylation inde novotranslation, we have studied the recovery of human kidney cells from hypertonic stress. Previously, we have demonstrated that hypertonic shock causes a rapid inhibition of protein synthesis, the disaggregation of polysomes, the dephosphorylation of eukaryotic translation initiation factor (eIF)4E, 4E-BP1, and ribosomal protein S6, and increased association of 4E-BP1 with eIF4E. The return of cells to isotonic medium promotes a transient activation of Erk1/2 and the phosphorylation of initiation factors, promoting an increase in protein synthesis that is independent of a requirement for eIF4E phosphorylation. Asde novotranslation is associated with the phosphorylation of 4E-BP1, we have investigated the role of the signaling pathways required for this event by the use of cell-permeable inhibitors. Surprisingly, although rapamycin, RAD001, wortmannin, and LY294002 inhibited the phosphorylation of 4E-BP1 and its release from eIF4E, they did not prevent the recovery of translation rates. These data suggest that only a small proportion of the available eIF4F complex is required for maximal translation rates under these conditions. Similarly, prevention of Erk1/2 activity alone with low concentrations of PD184352 did not impinge uponde novotranslation until later times of recovery from salt shock. However, U0126, which prevented the phosphorylation of Erk1/2, ribosomal protein S6, TSC2, and 4E-BP1, attenuatedde novoprotein synthesis in recovering cells. These results indicate that the phosphorylation of 4E-BP1 is mediated by both phosphatidylinositol 3-kinase-dependent rapamycin-sensitive and Erk1/2-dependent signaling pathways and that activation of either pathway in isolation is sufficient to promotede novotranslation.

scholarly journals Molecular mechanisms relating to amino acid regulation of protein synthesis

2019 ◽  
Vol 32 (2) ◽  
pp. 183-191 ◽  
Author(s):  
Yangchun Cao ◽  
Shimin Liu ◽  
Kai Liu ◽  
Imtiaz Hussain Raja Abbasi ◽  
Chuanjiang Cai ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Ribosomal Protein ◽  
Translation Initiation ◽  
Molecular Mechanisms ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Signalling Pathways ◽  
Control Of Gene Expression ◽  
Ribosomal Protein S6 ◽  
New Findings

AbstractSome amino acids (AA) act through several signalling pathways and mechanisms to mediate the control of gene expression at the translation level, and the regulation occurs, specifically, on the initiation and the signalling pathways for translation. The translation of mRNA to protein synthesis proceeds through the steps of initiation and elongation, and AA act as important feed-forward activators that are involved in many pathways, such as the sensing and the transportation of AA by cells, in these steps in many tissues of mammals. For the translation, phosphorylation of eukaryotic translation initiation factor 2α (eIF2α) is a critical molecule that controls the translation initiation and its functions can be regulated by some AA. Another control point in the mRNA binding step in the translation initiation is at the regulation by mammalian target of rapamycin, which requires a change of phosphorylation status of ribosomal protein S6. In fact, the change of phosphorylation status of ribosomal protein S6 might be involved in global protein synthesis. The present review summarises recent work on the molecular mechanisms of the regulation of protein synthesis by AA and highlights new findings.

scholarly journals Amino acid availability and age affect the leucine stimulation of protein synthesis and eIF4F formation in muscle

2007 ◽  
Vol 293 (6) ◽  
pp. E1615-E1621 ◽  
Author(s):  
Jeffery Escobar ◽  
Jason W. Frank ◽  
Agus Suryawan ◽  
Hanh V. Nguyen ◽  
Teresa A. Davis
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Ribosomal Protein ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
S6 Kinase ◽  
Ribosomal Protein S6 ◽  
Ribosomal Protein S6 Kinase

We have previously shown that a physiological increase in plasma leucine for 60 and 120 min increases translation initiation factor activation in muscle of neonatal pigs. Although muscle protein synthesis is increased by leucine at 60 min, it is not maintained at 120 min, perhaps because of the decrease in plasma amino acids (AA). In the present study, 7- and 26-day-old pigs were fasted overnight and infused with leucine (0 or 400 μmol·kg−1·h−1) for 120 min to raise leucine within the postprandial range. The leucine was infused in the presence or absence of a replacement AA mixture (without leucine) to maintain baseline plasma AA levels. AA administration prevented the leucine-induced reduction in plasma AA in both age groups. At 7 days, leucine infusion alone increased eukaryotic initiation factor (eIF) 4E binding protein-1 (4E-BP1) phosphorylation, decreased inactive 4E-BP1·eIF4E complex abundance, and increased active eIF4G·eIF4E complex formation in skeletal muscle; leucine infusion with replacement AA also stimulated these, as well as 70-kDa ribosomal protein S6 kinase, ribosomal protein S6, and eIF4G phosphorylation. At 26 days, leucine infusion alone increased 4E-BP1 phosphorylation and decreased the inactive 4E-BP1·eIF4E complex only; leucine with AA also stimulated these, as well as 70-kDa ribosomal protein S6 kinase and ribosomal protein S6 phosphorylation. Muscle protein synthesis was increased in 7-day-old (+60%) and 26-day-old (+40%) pigs infused with leucine and replacement AA but not with leucine alone. Thus the ability of leucine to stimulate eIF4F formation and protein synthesis in skeletal muscle is dependent on AA availability and age.

scholarly journals Protein synthesis persists during necrotic cell death

2005 ◽  
Vol 168 (4) ◽  
pp. 545-551 ◽  
Author(s):  
Xavier Saelens ◽  
Nele Festjens ◽  
Eef Parthoens ◽  
Isabel Vanoverberghe ◽  
Michael Kalai ◽  
...  
Keyword(s):  
Cell Death ◽  
Protein Synthesis ◽  
De Novo ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Necrotic Cell Death ◽  
Necrotic Cell ◽  
Proteolytic Activation ◽  
Double Stranded Rna ◽  
Molecular Events

Cell death is an intrinsic part of metazoan development and mammalian immune regulation. Whereas the molecular events orchestrating apoptosis have been characterized extensively, little is known about the biochemistry of necrotic cell death. Here, we show that, in contrast to apoptosis, the induction of necrosis does not lead to the shut down of protein synthesis. The rapid drop in protein synthesis observed in apoptosis correlates with caspase-dependent breakdown of eukaryotic translation initiation factor (eIF) 4G, activation of the double-stranded RNA-activated protein kinase PKR, and phosphorylation of its substrate eIF2-α. In necrosis induced by tumor necrosis factor, double-stranded RNA, or viral infection, de novo protein synthesis persists and 28S ribosomal RNA fragmentation, eIF2-α phosphorylation, and proteolytic activation of PKR are absent. Collectively, these results show that, in contrast to apoptotic cells, necrotic dying cells retain the opportunity to synthesize proteins.

scholarly journals Experimental Selection of Paromomycin Resistance in Leishmania donovani Amastigotes Induces Variable Genomic Polymorphisms

2021 ◽  
Vol 9 (8) ◽  
pp. 1546
Author(s):  
Sarah Hendrickx ◽  
João Luís Reis-Cunha ◽  
Sarah Forrester ◽  
Daniel C. Jeffares ◽  
Guy Caljon
Keyword(s):  
Ribosomal Protein ◽  
Protein Tyrosine Phosphatase ◽  
Copy Number ◽  
Leishmania Donovani ◽  
Rna Binding ◽  
Tyrosine Phosphatase ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Gene Copy ◽  
Protein Tyrosine

The relatively high post-treatment relapse rates of paromomycin (PMM) in visceral leishmaniasis treatment and the swift emergence of experimental drug resistance challenge its broad application and urge for rational use and monitoring of resistance. However, no causal molecular mechanisms to Leishmania PMM resistance have been identified so far. To gain insights into potential resistance mechanisms, twelve experimentally selected Leishmania donovani clonal lines and the non-cloned preselection population, with variable degrees of PMM resistance, were subjected to whole genome sequencing. To identify genomic variations potentially associated with resistance, SNPs, Indels, chromosomal somy and gene copy number variations were compared between the different parasite lines. A total of 11 short nucleotide variations and the copy number alterations in 39 genes were correlated to PMM resistance. Some of the identified genes are involved in transcription, translation and protein turn-over (transcription elongation factor-like protein, RNA-binding protein, ribosomal protein L1a, 60S ribosomal protein L6, eukaryotic translation initiation factor 4E-1, proteasome regulatory non-ATP-ase subunit 3), virulence (major surface protease gp63, protein-tyrosine phosphatase 1-like protein), mitochondrial function (ADP/ATP mitochondrial carrier-like protein), signaling (phosphatidylinositol 3-related kinase, protein kinase putative and protein-tyrosine phosphatase 1-like protein) and vesicular trafficking (ras-related protein RAB1). These results indicate that, in Leishmania, the aminoglycoside PMM affects protein translational processes and underlines the complex and probably multifactorial origin of resistance.

scholarly journals Correction of eIF2-dependent defects in brain protein synthesis, synaptic plasticity, and memory in mouse models of Alzheimer’s disease

2021 ◽  
Vol 14 (668) ◽  
pp. eabc5429
Author(s):  
Mauricio M. Oliveira ◽  
Mychael V. Lourenco ◽  
Francesco Longo ◽  
Nicole P. Kasica ◽  
Wenzhong Yang ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Protein Synthesis ◽  
Synaptic Plasticity ◽  
Translation Initiation ◽  
Mrna Translation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Postmortem Brain Tissue ◽  
Phosphorylated Eif2α

Neuronal protein synthesis is essential for long-term memory consolidation, and its dysregulation is implicated in various neurodegenerative disorders, including Alzheimer’s disease (AD). Cellular stress triggers the activation of protein kinases that converge on the phosphorylation of eukaryotic translation initiation factor 2α (eIF2α), which attenuates mRNA translation. This translational inhibition is one aspect of the integrated stress response (ISR). We found that postmortem brain tissue from AD patients showed increased phosphorylation of eIF2α and reduced abundance of eIF2B, another key component of the translation initiation complex. Systemic administration of the small-molecule compound ISRIB (which blocks the ISR downstream of phosphorylated eIF2α) rescued protein synthesis in the hippocampus, measures of synaptic plasticity, and performance on memory-associated behavior tests in wild-type mice cotreated with salubrinal (which inhibits translation by inducing eIF2α phosphorylation) and in both β-amyloid-treated and transgenic AD model mice. Thus, attenuating the ISR downstream of phosphorylated eIF2α may restore hippocampal protein synthesis and delay cognitive decline in AD patients.

scholarly journals Dual modulation of Ras-Mnk and PI3K-AKT-mTOR pathways: A Novel c-FLIP inhibitory mechanism of 3-AWA mediated translational attenuation through dephosphorylation of eIF4E

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Reyaz ur Rasool ◽  
Bilal Rah ◽  
Hina Amin ◽  
Debasis Nayak ◽  
Souneek Chakraborty ◽  
...  
Keyword(s):  
Translation Initiation ◽  
Cell Cycle Progression ◽  
De Novo ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Apoptosis Resistance ◽  
Nih3t3 Cells ◽  
Eukaryotic Translation ◽  
Underlying Mechanisms

Abstract The eukaryotic translation initiation factor 4E (eIF4E) is considered as a key survival protein involved in cell cycle progression, transformation and apoptosis resistance. Herein, we demonstrate that medicinal plant derivative 3-AWA (from Withaferin A) suppressed the proliferation and metastasis of CaP cells through abrogation of eIF4E activation and expression via c-FLIP dependent mechanism. This translational attenuation prevents the de novo synthesis of major players of metastatic cascades viz. c-FLIP, c-Myc and cyclin D1. Moreover, the suppression of c-FLIP due to inhibition of translation initiation complex by 3-AWA enhanced FAS trafficking, BID and caspase 8 cleavage. Further ectopically restored c-Myc and GFP-HRas mediated activation of eIF4E was reduced by 3-AWA in transformed NIH3T3 cells. Detailed underlying mechanisms revealed that 3-AWA inhibited Ras-Mnk and PI3-AKT-mTOR, two major pathways through which eIF4E converges upon eIF4F hub. In addition to in vitro studies, we confirmed that 3-AWA efficiently suppressed tumor growth and metastasis in different mouse models. Given that 3-AWA inhibits c-FLIP through abrogation of translation initiation by co-targeting mTOR and Mnk-eIF4E, it (3-AWA) can be exploited as a lead pharmacophore for promising anti-cancer therapeutic development.

Identification of spatial specifically expressed genes in rice (Oryza sativa) seedlings using cDNA microarray

2004 ◽  
Vol 1 (2) ◽  
pp. 133-139
Author(s):  
Sun Liang-Xian ◽  
Dong Hai-Tao ◽  
Zhuang Xiao-Feng ◽  
Zhang Feng ◽  
Li De-Bao
Keyword(s):  
Ribosomal Protein ◽  
Lipid Transfer Protein ◽  
Protein Biosynthesis ◽  
Critical Role ◽  
Phosphoglycerate Kinase ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Metabolic Reaction ◽  
Lipid Transfer ◽  
Molecular Physiology

AbstractMembranous cDNA microarrays containing 2200 unique rice transcripts were designed for screening the characteristics of spatially expressed genes in post-germination rice seedlings. By comparing the profiles obtained, 31 genes were identified as expressed specifically in the plumule, 36 in the mesocotyl and 73 in the radicle. Several genes, such as polyubiquitin, UDP-glucose pyrophosphorylase, sucrose synthase and phosphoglycerate kinase, which encode components of the carbohydrate or protein metabolic reaction cascades, were expressed specifically in the mesocotyl, indicating that degradation reactions of the endospermous reserve starch and proteins occur mainly in the mesocotyl during the post-germination stage. A number of genes involved in defence mechanisms or in the processes of replication, transcription and translation were identified as expressed specifically in the plumule or radicle. Among plumule specifically expressed genes, translation initiation factor 5a, 40s ribosomal protein s28 and ribosomal protein 136 are considered to have a critical role in protein biosynthesis; while allergenic protein, β-D-glucan exohydrolase and actin 11 are genes with defending functions. Among the catalogue of radicle specifically expressed genes, EF-1a, Tat binding protein, replication protein A2, histone h3.2, ribosomal protein s29a and 40s ribosomal protein s19 are genes that function in the process of replication, transcription or translation; whereas glycine-rich protein, wound-induced basic protein, Bowman-Birk proteinase inhibitor and lipid transfer protein-2 are genes involved in defence responses. Results of this experiment have provided insight into post-germination molecular physiology at the genomic level of gene expression.

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