scholarly journals Diphthamide promotes TOR signaling by increasing the translation of proteins in the TORC1 pathway

2021 ◽  
Vol 118 (37) ◽  
pp. e2104577118
Author(s):  
Yugang Zhang ◽  
Zhewang Lin ◽  
Julia Zhu ◽  
Miao Wang ◽  
Hening Lin
Keyword(s):  
Feedback Loop ◽  
Elongation Factor ◽  
Translation Elongation Factor ◽  
Tor Signaling ◽  
Translation Elongation ◽  
Developmental Defects ◽  
Elongation Factor 2 ◽  
Genome Wide ◽  
Mtorc1 Signaling ◽  
Evolutionarily Conserved

Diphthamide, a modification found only on translation elongation factor 2 (EF2), was proposed to suppress −1 frameshifting in translation. Although diphthamide is conserved among all eukaryotes, exactly what proteins are affected by diphthamide deletion is not clear in cells. Through genome-wide profiling for a potential −1 frameshifting site, we identified that the target of rapamycin complex 1 (TORC1)/mammalian TORC1 (mTORC1) signaling pathway is affected by deletion of diphthamide. Diphthamide deficiency in yeast suppresses the translation of TORC1-activating proteins Vam6 and Rtc1. Interestingly, TORC1 signaling also promotes diphthamide biosynthesis, suggesting that diphthamide forms a positive feedback loop to promote translation under nutrient-rich conditions. Our results provide an explanation for why diphthamide is evolutionarily conserved and why diphthamide deletion can cause severe developmental defects.

scholarly journals Translation elongation factor 2 depletion by siRNA in mouse liver leads to mTOR-independent translational upregulation of ribosomal protein genes

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Maxim V. Gerashchenko ◽  
Mikhail V. Nesterchuk ◽  
Elena M. Smekalova ◽  
Joao A. Paulo ◽  
Piotr S. Kowalski ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Mammalian Cells ◽  
Ribosomal Proteins ◽  
Mouse Liver ◽  
Negative Impact ◽  
Elongation Factor ◽  
Ribosome Profiling ◽  
Translation Elongation Factor ◽  
Translation Elongation ◽  
Elongation Factor 2

Abstract Due to breakthroughs in RNAi and genome editing methods in the past decade, it is now easier than ever to study fine details of protein synthesis in animal models. However, most of our understanding of translation comes from unicellular organisms and cultured mammalian cells. In this study, we demonstrate the feasibility of perturbing protein synthesis in a mouse liver by targeting translation elongation factor 2 (eEF2) with RNAi. We were able to achieve over 90% knockdown efficacy and maintain it for 2 weeks effectively slowing down the rate of translation elongation. As the total protein yield declined, both proteomics and ribosome profiling assays showed robust translational upregulation of ribosomal proteins relative to other proteins. Although all these genes bear the TOP regulatory motif, the branch of the mTOR pathway responsible for translation regulation was not activated. Paradoxically, coordinated translational upregulation of ribosomal proteins only occurred in the liver but not in murine cell culture. Thus, the upregulation of ribosomal transcripts likely occurred via passive mTOR-independent mechanisms. Impaired elongation sequesters ribosomes on mRNA and creates a shortage of free ribosomes. This leads to preferential translation of transcripts with high initiation rates such as ribosomal proteins. Furthermore, severe eEF2 shortage reduces the negative impact of positively charged amino acids frequent in ribosomal proteins on ribosome progression.

scholarly journals A Chemical Genomic Screen in Saccharomyces cerevisiae Reveals a Role for Diphthamidation of Translation Elongation Factor 2 in Inhibition of Protein Synthesis by Sordarin

2008 ◽  
Vol 52 (5) ◽  
pp. 1623-1629 ◽  
Author(s):  
Javier Botet ◽  
María Rodríguez-Mateos ◽  
Juan P. G. Ballesta ◽  
José Luis Revuelta ◽  
Miguel Remacha
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Synthesis ◽  
Elongation Factor ◽  
Translation Elongation Factor ◽  
Cellular Mechanisms ◽  
Translation Elongation ◽  
Chemical Genomic ◽  
Elongation Factor 2 ◽  
Fungal Organisms ◽  
Inhibitor Of Protein Synthesis

ABSTRACT Sordarin and its derivatives are antifungal compounds of potential clinical interest. Despite the highly conserved nature of the fungal and mammalian protein synthesis machineries, sordarin is a selective inhibitor of protein synthesis in fungal organisms. In cells sensitive to sordarin, its mode of action is through preventing the release of translation elongation factor 2 (eEF2) during the translocation step, thus blocking protein synthesis. To further investigate the cellular components required for the effects of sordarin in fungal cells, we have used the haploid deletion collection of Saccharomyces cerevisiae to systematically identify genes whose deletion confers sensitivity or resistance to the compound. Our results indicate that genes in a number of cellular pathways previously unknown to play a role in sordarin response are involved in its growth effects on fungal cells and reveal a specific requirement for the diphthamidation pathway of cells in causing eEF2 to be sensitive to the effects of sordarin on protein synthesis. Our results underscore the importance of the powerful genomic tools developed in yeast (Saccharomyces cerevisiae) to more comprehensively understanding the cellular mechanisms involved in the response to therapeutic agents.

scholarly journals Proteome of actin stress fibers

2021 ◽  
Author(s):  
Shiyou Liu ◽  
Tsubasa S. Matsui ◽  
Na Kang ◽  
Shinji Deguchi
Keyword(s):  
Molecular Basis ◽  
Replicative Senescence ◽  
Human Fibroblasts ◽  
Elongation Factor ◽  
Stress Fibers ◽  
Translation Elongation Factor ◽  
Translation Elongation ◽  
Eukaryotic Translation ◽  
Elongation Factor 2 ◽  
Protein Components

Stress fibers (SFs), which are actomyosin structures, reorganize in response to various cues to maintain cellular homeostasis. Currently, the protein components of SFs are only partially identified, limiting our understanding of their responses. Here we isolate SFs from human fibroblasts HFF-1 to determine with proteomic analysis the whole protein components and how they change with replicative senescence (RS), a state where cells decline in ability to replicate after repeated divisions. We found that at least 263 proteins are associated with SFs, and 101 of them are upregulated with RS, by which SFs become larger in size. Among them, we focused on eEF2 (eukaryotic translation elongation factor 2) as it exhibited upon RS the most significant increase in abundance. We show that eEF2 is critical to the reorganization and stabilization of SFs in senescent fibroblasts. Our findings provide a novel molecular basis for SFs to be reinforced to resist cellular senescence.

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