Differing effects of rapamycin and mTOR kinase inhibitors on protein synthesis

2011 ◽  
Vol 39 (2) ◽  
pp. 446-450 ◽  
Author(s):  
Yilin Huo ◽  
Valentina Iadevaia ◽  
Christopher G. Proud
Keyword(s):  
Protein Synthesis ◽  
Kinase Inhibitors ◽  
Mammalian Target Of Rapamycin ◽  
Stable Isotope Labelling ◽  
Initiation Factors ◽  
Mtor Kinase ◽  
General Protein Synthesis ◽  
Specific Proteins ◽  
Terminal Oligopyrimidine ◽  
General Protein

mTOR (mammalian target of rapamycin) forms two distinct types of complex, mTORC (mTOR complex) 1 and 2. Rapamycin inhibits some of the functions of mTORC1, whereas newly developed mTOR kinase inhibitors interfere with the actions of both types of complex. We have explored the effects of rapamycin and mTOR kinase inhibitors on general protein synthesis and, using a new stable isotope-labelling method, the synthesis of specific proteins. In HeLa cells, rapamycin only had a modest effect on total protein synthesis, whereas mTOR kinase inhibitors decreased protein synthesis by approx. 30%. This does not seem to be due to the ability of mTOR kinase inhibitors to block the binding of eIFs (eukaryotic initiation factors) eIF4G and eIF4E. Analysis of the effects of the inhibitors on the synthesis of specific proteins showed a spectrum of behaviours. As expected, synthesis of proteins encoded by mRNAs that contain a 5′-TOP (5′-terminal oligopyrimidine tract) was impaired by rapamycin, but more strongly by mTOR kinase inhibition. Several proteins not known to be encoded by 5′-TOP mRNAs also showed similar behaviour. Synthesis of proteins encoded by ‘non-TOP’ mRNAs was less inhibited by mTOR kinase inhibitors and especially by rapamycin. The implications of our findings are discussed.

Roles of the mammalian target of rapamycin, mTOR, in controlling ribosome biogenesis and protein synthesis

2012 ◽  
Vol 40 (1) ◽  
pp. 168-172 ◽  
Author(s):  
Valentina Iadevaia ◽  
Yilin Huo ◽  
Ze Zhang ◽  
Leonard J. Foster ◽  
Christopher G. Proud
Keyword(s):  
Protein Synthesis ◽  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Kinase Inhibitors ◽  
Mammalian Target Of Rapamycin ◽  
Target Of Rapamycin ◽  
Energy Status ◽  
Stable Isotope Labelling ◽  
Mtor Kinase ◽  
The Impact

mTORC1 (mammalian target of rapamycin complex 1) is controlled by diverse signals (e.g. hormones, growth factors, nutrients and cellular energy status) and regulates a range of processes including anabolic metabolism, cell growth and cell division. We have studied the impact of inhibiting mTOR on protein synthesis in human cells. Partial inhibition of mTORC1 by rapamycin has only a limited impact on protein synthesis, but inhibiting mTOR kinase activity causes much greater inhibition of protein synthesis. Using a pulsed stable-isotope-labelling technique, we show that the rapamycin and mTOR (mammalian target of rapamycin) kinase inhibitors have differential effects on the synthesis of specific proteins. In particular, the synthesis of proteins encoded by mRNAs that have a 5′-terminal pyrimidine tract is strongly inhibited by mTOR kinase inhibitors. Many of these mRNAs encode ribosomal proteins. mTORC1 also promotes the synthesis of rRNA, although the mechanisms involved remain to be clarified. We found that mTORC1 also regulates the processing of the precursors of rRNA. mTORC1 thus co-ordinates several steps in ribosome biogenesis.

A phosphorylation-regulated eIF3d translation switch mediates cellular adaptation to metabolic stress

Science ◽  
2020 ◽  
Vol 370 (6518) ◽  
pp. 853-856
Author(s):  
Adam M. Lamper ◽  
Rebecca H. Fleming ◽  
Kayla M. Ladd ◽  
Amy S. Y. Lee
Keyword(s):  
Protein Synthesis ◽  
Cellular Response ◽  
Mammalian Target Of Rapamycin ◽  
Metabolic Stress ◽  
Glucose Deprivation ◽  
Binding Pocket ◽  
Global Protein Synthesis ◽  
General Protein Synthesis ◽  
General Protein ◽  
Cellular Stresses

Shutoff of global protein synthesis is a conserved response to cellular stresses. This general phenomenon is accompanied by the induction of distinct gene programs tailored to each stress. Although the mechanisms driving repression of general protein synthesis are well characterized, how cells reprogram the translation machinery for selective gene expression remains poorly understood. Here, we found that the noncanonical 5′ cap-binding protein eIF3d was activated in response to metabolic stress in human cells. Activation required reduced CK2-mediated phosphorylation near the eIF3d cap-binding pocket. eIF3d controls a gene program enriched in factors important for glucose homeostasis, including members of the mammalian target of rapamycin (mTOR) pathway. eIF3d-directed translation adaptation was essential for cell survival during chronic glucose deprivation. Thus, this mechanism of translation reprogramming regulates the cellular response to metabolic stress.

scholarly journals Induction of carnitine acetyltransferase by clofibrate in rat liver

1981 ◽  
Vol 194 (1) ◽  
pp. 249-255 ◽  
Author(s):  
B Mittal ◽  
C K R Kurup
Keyword(s):  
Protein Synthesis ◽  
Enzyme Activity ◽  
Rat Liver ◽  
Time Lag ◽  
Mitochondrial Protein ◽  
Carnitine Acetyltransferase ◽  
Enzyme Protein ◽  
General Protein Synthesis ◽  
Liver And Kidney ◽  
General Protein

Administration of the anti-hypercholesterolaemic drug clofibrate to the rat increases the activity of carnitine acetyltransferase (acetyl-CoA-carnitine O-acetyltransferase, EC 2.3.1.7) in liver and kidney. The drug-mediated increase in enzyme activity in hepatic mitochondria shows a time lag during which the activity increases in the microsomal and peroxisomal fractions. The enzyme induced in the particulate fractions is identical with one normally present in mitochondria. The increase in enzyme activity is prevented by inhibitors of RNA and general protein synthesis. Mitochondrial protein-synthetic machinery does not appear to be involved in the process. Immunoprecipitation shows increased concentration of the enzyme protein in hepatic mitochondria isolated from drug-treated animals. In these animals, the rate of synthesis of the enzyme is increased 7-fold.

scholarly journals Bmp Induces Osteoblast Differentiation through both Smad4 and mTORC1 Signaling

2016 ◽  
Vol 37 (4) ◽  
Author(s):  
Courtney M. Karner ◽  
Seung-Yon Lee ◽  
Fanxin Long
Keyword(s):  
Protein Synthesis ◽  
Intracellular Signaling ◽  
Osteoblast Differentiation ◽  
De Novo ◽  
Bmp Signaling ◽  
Endoplasmic Reticulum Stress Response ◽  
Versus Protein ◽  
Mtorc1 Signaling ◽  
General Protein Synthesis ◽  
General Protein

ABSTRACT The bone morphogenetic protein (Bmp) family of secreted molecules has been extensively studied in the context of osteoblast differentiation. However, the intracellular signaling cascades that mediate the osteoblastogenic function of Bmp have not been fully elucidated. By profiling mRNA expression in the bone marrow mesenchymal progenitor cell line ST2, we discover that BMP2 induces not only genes commonly associated with ossification and mineralization but also genes important for general protein synthesis. We define the two groups of genes as mineralization related versus protein anabolism signatures of osteoblasts. Although it induces the expression of several Wnt genes, BMP2 activates the osteogenic program largely independently of de novo Wnt secretion. Remarkably, although Smad4 is necessary for the activation of the mineralization-related genes, it is dispensable for BMP2 to induce the protein anabolism signature, which instead critically depends on the transcription factor Atf4. Upstream of Atf4, BMP2 activates mTORC1 to stimulate protein synthesis, resulting in an endoplasmic reticulum stress response mediated by Perk. Thus, Bmp signaling induces osteoblast differentiation through both Smad4- and mTORC1-dependent mechanisms.

Stage-specific changes in cytoplasmic protein synthesis in Entomophaga aulicae protoplasts

1989 ◽  
Vol 35 (3) ◽  
pp. 373-378
Author(s):  
Richard A. Nolan
Keyword(s):  
Protein Synthesis ◽  
Developmental Stages ◽  
Late Fusion ◽  
One Dimensional ◽  
Early Fusion ◽  
Specific Proteins ◽  
Fungal Protoplasts ◽  
General Protein ◽  
The Individual ◽  
Synthesis Stage

The patterns of protein synthesis associated with three sequential stages in protoplast morphogenesis (spindle-shaped, early fusion sphere, and late fusion sphere protoplasts) of the fungus Entomophaga aulicae were studied using both one-dimensional gels with general protein staining and two-dimensional gels with [35S]methionine protein labelling and fluorography. A total of 332 proteins were observed with 63.5% (211) common to all three developmental stages. Of the individual totals, 3.3% (8 out of 245), 7.3% (22 out of 301), and 4.5% (13 out of 286) of the proteins were unique to the spindle-shaped, early fusion sphere, and late fusion sphere protoplasts, respectively. The molecular mass and pI distribution profiles for early fusion sphere protoplast proteins are discussed.Key words: protein synthesis, stage-specific proteins, fungal protoplasts, Entomophaga aulicae.

scholarly journals Proline responding1 Plays a Critical Role in Regulating General Protein Synthesis and the Cell Cycle in Maize

2014 ◽  
Vol 26 (6) ◽  
pp. 2582-2600 ◽  
Author(s):  
Gang Wang ◽  
Jushan Zhang ◽  
Guifeng Wang ◽  
Xiangyu Fan ◽  
Xin Sun ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Protein Synthesis ◽  
Critical Role ◽  
General Protein Synthesis ◽  
General Protein

Stable isotope-labelling analysis of the impact of inhibition of the mammalian target of rapamycin on protein synthesis

2012 ◽  
Vol 444 (1) ◽  
pp. 141-151 ◽  
Author(s):  
Yilin Huo ◽  
Valentina Iadevaia ◽  
Zhong Yao ◽  
Isabelle Kelly ◽  
Sabina Cosulich ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Stable Isotope ◽  
Mammalian Target Of Rapamycin ◽  
Mrna Translation ◽  
Target Of Rapamycin ◽  
Stable Isotope Labelling ◽  
Isotope Labelling ◽  
Cell Functions ◽  
Specific Mrnas ◽  
The Impact

mTORC1 [mTOR (mammalian target of rapamycin) complex 1] regulates diverse cell functions. mTORC1 controls the phosphorylation of several proteins involved in mRNA translation and the translation of specific mRNAs, including those containing a 5′-TOP (5′-terminal oligopyrimidine). To date, most of the proteins encoded by known 5′-TOP mRNAs are proteins involved in mRNA translation, such as ribosomal proteins and elongation factors. Rapamycin inhibits some mTORC1 functions, whereas mTOR-KIs (mTOR kinase inhibitors) interfere with all of them. mTOR-KIs inhibit overall protein synthesis more strongly than rapamycin. To study the effects of rapamycin or mTOR-KIs on synthesis of specific proteins, we applied pSILAC [pulsed SILAC (stable isotope-labelling with amino acids in cell culture)]. Our results reveal, first, that mTOR-KIs and rapamycin differentially affect the synthesis of many proteins. Secondly, mTOR-KIs inhibit the synthesis of proteins encoded by 5′-TOP mRNAs much more strongly than rapamycin does, revealing that these mRNAs are controlled by rapamycin-insensitive outputs from mTOR. Thirdly, the synthesis of certain other proteins shows a similar pattern of inhibition. Some of them appear to be encoded by ‘novel’ 5′-TOP mRNAs; they include proteins which, like known 5′-TOP mRNA-encoded proteins, are involved in protein synthesis, whereas others are enzymes involved in intermediary or anabolic metabolism. These results indicate that mTOR signalling may promote diverse biosynthetic processes through the translational up-regulation of specific mRNAs. Lastly, a SILAC-based approach revealed that, although rapamycin and mTOR-KIs have little effect on general protein stability, they stabilize proteins encoded by 5′-TOP mRNAs.

scholarly journals Multiple components of eIF4F are required for protein synthesis-dependent hippocampal long-term potentiation

2013 ◽  
Vol 109 (1) ◽  
pp. 68-76 ◽  
Author(s):  
Charles A. Hoeffer ◽  
Emanuela Santini ◽  
Tao Ma ◽  
Elizabeth C. Arnold ◽  
Ashley M. Whelan ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Synaptic Plasticity ◽  
Translation Initiation ◽  
Translational Control ◽  
Late Phase ◽  
Long Term Potentiation ◽  
Term Potentiation ◽  
General Protein Synthesis ◽  
General Protein

Persistent forms of synaptic plasticity are widely thought to require the synthesis of new proteins. This feature of long-lasting forms of plasticity largely has been demonstrated using inhibitors of general protein synthesis, such as either anisomycin or emetine. However, these drugs, which inhibit elongation, cannot address detailed questions about the regulation of translation initiation, where the majority of translational control occurs. Moreover, general protein synthesis inhibitors cannot distinguish between cap-dependent and cap-independent modes of translation initiation. In the present study, we took advantage of two novel compounds, 4EGI-1 and hippuristanol, each of which targets a different component of the eukaryotic initiation factor (eIF)4F initiation complex, and investigated their effects on long-term potentiation (LTP) at CA3-CA1 synapses in the hippocampus. We found that 4EGI-1 and hippuristanol both attenuated long-lasting late-phase LTP induced by two different stimulation paradigms. We also found that 4EGI-1 and hippuristanol each were capable of blocking the expression of newly synthesized proteins immediately after the induction of late-phase LTP. These new pharmacological tools allow for a more precise dissection of the role played by translational control pathways in synaptic plasticity and demonstrate the importance of multiple aspects of eIF4F in processes underlying hippocampal LTP, laying the foundation for future studies investigating the role of eIF4F in hippocampus-dependent memory processes.

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