The Experts below are selected from a list of 198 Experts worldwide ranked by ideXlab platform
Oded Meyuhas - One of the best experts on this subject based on the ideXlab platform.
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PKA-Dependent Phosphorylation of Ribosomal Protein S6 Does Not Correlate with Translation Efficiency in Striatonigral and Striatopallidal Medium-Sized Spiny Neurons
The Journal of Neuroscience, 2015Co-Authors: Anne Biever, Oded Meyuhas, Emma Puighermanal, Akinori Nishi, Alexandre David, Claire Panciatici, Sophie Longueville, Dimitris P. Xirodimas, Giuseppe Gangarossa, Denis HervéAbstract:Ribosomal protein S6 (rpS6), a component of the 40S ribosomal subunit, is phosphorylated on several residues in response to numerous stimuli. Although commonly used as a marker for neuronal activity, its upstream mechanisms of regulation are poorly studied and its role in protein synthesis remains largely debated. Here, we demonstrate that the psychostimulant d-amphetamine (d-amph) markedly increases rpS6 phosphorylation at Ser235/236 sites in both crude and synaptoneurosomal preparations of the mouse striatum. This effect occurs selectively in D1R-expressing medium-sized spiny neurons (MSNs) and requires the cAMP/PKA/DARPP-32/PP-1 cascade, whereas it is independent of mTORC1/p70S6K, PKC, and ERK signaling. By developing a novel assay to label nascent peptidic chains, we show that the rpS6 phosphorylation induced in striatonigral MSNs by d-amph, as well as in striatopallidal MSNs by the antipsychotic haloperidol or in both subtypes by papaverine, is not correlated with the translation of global or 5′ Terminal Oligopyrimidine Tract mRNAs. Together, these results provide novel mechanistic insights into the in vivo regulation of the post-translational modification of rpS6 in the striatum and point out the lack of a relationship between PKA-dependent rpS6 phosphorylation and translation efficiency.
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ribosomal protein s6 phosphorylation from protein synthesis to cell size
Trends in Biochemical Sciences, 2006Co-Authors: Igor Ruvinsky, Oded MeyuhasAbstract:Recent studies are beginning to disclose a signaling network involved in regulating cell size. Although many links and effectors are still unknown, central components of this network include the mammalian target of rapamycin (mTOR) and its downstream effectors – the ribosomal protein S6 kinase (S6K) and the translational repressor eukaryotic initiation factor 4E-binding protein. Until recently, the role of S6K and its many substrates in cell-size control remained obscure; however, a knockin mouse carrying mutations at all phosphorylation sites in the primary S6K substrate, ribosomal protein S6 (rpS6), has provided insight into the physiological role of this protein phosphorylation event. In addition to its role in glucose homeostasis in the whole mouse, phosphorylation of rpS6 is essential for regulating the size of at least some cell types, but is dispensable for translational control of mRNAs with a 5′ Terminal Oligopyrimidine Tract (TOP mRNAs) – its previously assigned targets. It therefore seems that establishing the function of the phosphorylation of other effectors of mTOR or S6K will inevitably require genetic manipulation of the respective sites within these targets.
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Lithium can relieve translational repression of TOP mRNAs elicited by various blocks along the cell cycle in a glycogen synthase kinase-3- and S6-kinase-independent manner.
Journal of Biological Chemistry, 2004Co-Authors: Miri Stolovich, Tal Lerer, Yoav Bolkier, Hannah Cohen, Oded MeyuhasAbstract:AbsTract TOP mRNAs are translationally controlled by mitogenic, growth, and nutritional stimuli through a 5′-Terminal Oligopyrimidine Tract. Here we show that LiCl can alleviate the translational repression of these mRNAs when progression through the cell cycle is blocked at G0, G1/S, or G2/M phases in different cell lines and by various physiological and chemical means. This derepressive effect of LiCl does not involve resumption of cell division. Unlike its efficient derepressive effect in mitotically arrested cells, LiCl alleviates inefficiently the repression of TOP mRNAs in amino acid-deprived cells and has no effect in lymphoblastoids whose TOP mRNAs are constitutively repressed even when they are proliferating. LiCl is widely used as a relatively selective inhibitor of glycogen synthase kinase-3. However, inhibition per se of this enzyme by more specific drugs failed to derepress the translation of TOP mRNAs, implying that relief of the translational repression of TOP mRNAs by LiCl is carried out in a glycogen synthase kinase-3-independent manner. Moreover, this effect is apparent, at least in some cell lines, in the absence of S6-kinase 1 activation and ribosomal protein S6 phosphorylation, thus further supporting the notion that translational control of TOP mRNAs does not rely on either of these variables.
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Transduction of Growth or Mitogenic Signals into Translational Activation of TOP mRNAs Is Fully Reliant on the Phosphatidylinositol 3-Kinase-Mediated Pathway but Requires neither S6K1 nor rpS6 Phosphorylation
Molecular and Cellular Biology, 2002Co-Authors: Miri Stolovich, Eran Hornstein, Hua Tang, Galit Levy, Ruth Cohen, Morris J. Birnbaum, Oded MeyuhasAbstract:Translation of Terminal Oligopyrimidine Tract (TOP) mRNAs, which encode multiple components of the protein synthesis machinery, is known to be controlled by mitogenic stimuli. We now show that the ability of cells to progress through the cell cycle is not a prerequisite for this mode of regulation. TOP mRNAs can be translationally activated when PC12 or embryonic stem (ES) cells are induced to grow (increase their size) by nerve growth factor and retinoic acid, respectively, while remaining mitotically arrested. However, both growth and mitogenic signals converge via the phosphatidylinositol 3-kinase (PI3-kinase)-mediated pathway and are transduced to efficiently translate TOP mRNAs. Translational activation of TOP mRNAs can be abolished by LY294002, a PI3-kinase inhibitor, or by overexpression of PTEN as well as by dominant-negative mutants of PI3-kinase or its effectors, PDK1 and protein kinase Bα (PKBα). Likewise, overexpression of constitutively active PI3-kinase or PKBα can relieve the translational repression of TOP mRNAs in quiescent cells. Both mitogenic and growth signals lead to phosphorylation of ribosomal protein S6 (rpS6), which precedes the translational activation of TOP mRNAs. Nevertheless, neither rpS6 phosphorylation nor its kinase, S6K1, is essential for the translational response of these mRNAs. Thus, TOP mRNAs can be translationally activated by growth or mitogenic stimuli of ES cells, whose rpS6 is constitutively unphosphorylated due to the disruption of both alleles of S6K1. Similarly, complete inhibition of mammalian target of rapamycin (mTOR) and its effector S6K by rapamycin in various cell lines has only a mild repressive effect on the translation of TOP mRNAs. It therefore appears that translation of TOP mRNAs is primarily regulated by growth and mitogenic cues through the PI3-kinase pathway, with a minor role, if any, for the mTOR pathway.
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s6 phosphorylation independent pathways regulate translation of 5 Terminal Oligopyrimidine Tract containing mrnas in differentiating hematopoietic cells
Nucleic Acids Research, 2002Co-Authors: Diane Barthbaus, Oded Meyuhas, Carl A Stratton, Lou Parrott, Howard Myerson, Dennis J Templeton, Gary E Landreth, Jack O HensoldAbstract:Synthesis of new ribosomes is an energy costly and thus highly regulated process. Ribosomal protein synthesis is controlled by regulating translation of the corresponding ribosomal protein (rp)mRNAs. In mammalian cells a 5′-Terminal Oligopyrimidine Tract (TOP) is a conserved feature of these mRNAs that has been demonstrated to be essential for their translational regulation. Translation of TOP mRNAs has been proposed to be regulated by phosphorylation of ribosomal protein S6, which is a common effect of mitogenic stimulation of cells. However, as demonstrated here, S6 phosphorylation is not detectable in murine erythroleukemia (MEL) or other hematopoietic cells. The absence of S6 phosphorylation appears to be due to the action of a phosphatase that acts downstream of S6 kinase, presumably on S6 itself. Despite the absence of changes in S6 phosphorylation, translation of TOP mRNAs is repressed during differentiation of MEL cells. These data demonstrate the existence of a mechanism for regulating S6 phosphorylation that is distinct from kinase activation, as well as the existence of mechanisms for regulating translation of TOP mRNAs that are independent of S6 phosphorylation.
R B Gartenhaus - One of the best experts on this subject based on the ideXlab platform.
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Ribosomal protein S6 is highly expressed in non-Hodgkin lymphoma and associates with mRNA containing a 5′ Terminal Oligopyrimidine Tract
Oncogene, 2011Co-Authors: P R Hagner, K Mazan-mamczarz, E M Balzer, S Corl, S S Martin, X F Zhao, R B GartenhausAbstract:The molecular mechanism(s) linking tumorigenesis and morphological alterations in the nucleolus are presently coming into focus. The nucleolus is the cellular organelle in which the formation of ribosomal subunits occurs. Ribosomal biogenesis occurs through the transcription of ribosomal RNA (rRNA), rRNA processing and production of ribosomal proteins. An error in any of these processes may lead to deregulated cellular translation, evident in multiple cancers and ‘ribosomopathies’. Deregulated protein synthesis may be achieved through the overexpression of ribosomal proteins as seen in primary leukemic blasts with elevated levels of ribosomal proteins S11 and S14. In this study, we demonstrate that ribosomal protein S6 (RPS6) is highly expressed in primary diffuse large B-cell lymphoma (DLBCL) samples. Genetic modulation of RPS6 protein levels with specifically targeted short hairpin RNA (shRNA) lentiviruses led to a decrease in the actively proliferating population of cells compared with control shRNA. Low-dose rapamycin treatments have been shown to affect the translation of 5′ Terminal Oligopyrimidine (5′ TOP) Tract mRNA, which encodes the translational machinery, implicating RPS6 in 5′ TOP translation. Recently, it was shown that disruption of 40S ribosomal biogenesis through specific small inhibitory RNA knockdown of RPS6 defined RPS6 as a critical regulator of 5′ TOP translation. For the first time, we show that RPS6 associates with multiple mRNAs containing a 5′ TOP Tract. These findings expand our understanding of the mechanism(s) involved in ribosomal biogenesis and deregulated protein synthesis in DLBCL.
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ribosomal protein s6 is highly expressed in non hodgkin lymphoma and associates with mrna containing a 5 Terminal Oligopyrimidine Tract
Oncogene, 2011Co-Authors: P R Hagner, E M Balzer, S Corl, S S Martin, X F Zhao, R B Gartenhaus, Krystyna MazanmamczarzAbstract:The molecular mechanism(s) linking tumorigenesis and morphological alterations in the nucleolus are presently coming into focus. The nucleolus is the cellular organelle in which the formation of ribosomal subunits occurs. Ribosomal biogenesis occurs through the transcription of ribosomal RNA (rRNA), rRNA processing and production of ribosomal proteins. An error in any of these processes may lead to deregulated cellular translation, evident in multiple cancers and ‘ribosomopathies’. Deregulated protein synthesis may be achieved through the overexpression of ribosomal proteins as seen in primary leukemic blasts with elevated levels of ribosomal proteins S11 and S14. In this study, we demonstrate that ribosomal protein S6 (RPS6) is highly expressed in primary diffuse large B-cell lymphoma (DLBCL) samples. Genetic modulation of RPS6 protein levels with specifically targeted short hairpin RNA (shRNA) lentiviruses led to a decrease in the actively proliferating population of cells compared with control shRNA. Low-dose rapamycin treatments have been shown to affect the translation of 5′ Terminal Oligopyrimidine (5′ TOP) Tract mRNA, which encodes the translational machinery, implicating RPS6 in 5′ TOP translation. Recently, it was shown that disruption of 40S ribosomal biogenesis through specific small inhibitory RNA knockdown of RPS6 defined RPS6 as a critical regulator of 5′ TOP translation. For the first time, we show that RPS6 associates with multiple mRNAs containing a 5′ TOP Tract. These findings expand our understanding of the mechanism(s) involved in ribosomal biogenesis and deregulated protein synthesis in DLBCL.
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absTract 3159 rps6 controls the translation of 5 Terminal Oligopyrimidine Tract containing mrnas through a physical interaction that regulates the loading of these messages on the polysome
Cancer Research, 2010Co-Authors: P R Hagner, Krystyna Mazanmamczarz, R B GartenhausAbstract:The prevailing paradigm for mTOR signaling implicates RPS6 activation in translational control of mRNAs characterized by the presence of an Oligopyrimidine Tract (5’ Terminal Oligopyrimidine) within the 5’ untranslated region. These messages containing an Oligopyrimidine Tract are important for ribosomal biogenesis as they encode most of the translational apparatus. However, mechanistic details of how RPS6 is involved in the regulation of these Oligopyrimidine Tract-containing messages are still poorly understood. We demonstrated that through small inhibitory RNA (siRNA) knockdown of RPS6, 5’ TOP mRNA were selectively upregulated in heavy polysomal fractions. The ability of RPS6 to interact with endogenous mRNA containing 5’ TOP sequences was tested by immunoprecipitation (IP) analysis using lysates from Diffuse Large B-cell Lymphoma (DLBCL) cell lines (Farage and OCI-LY10) and a specific RPS6 antibody. The association of RPS6 with 5’ TOP mRNA was interrogated using RT-qPCR to examine mRNAs isolated from the IP material using primer sets specific for multiple 5’ TOP mRNAs. We found that 5’ TOP containing mRNA were highly enriched in IP material obtained with anti-RPS6 antibody compared with the background level of amplification seen in control immunoglobulin G (IgG) IP. We constructed a heterologous green fluorescent protein (GFP) mRNA containing the 5’ TOP sequence from the RPS6 gene in the 5’ UTR. Using mRNP-IP assays, RPS6 was found to interact with the heterologous construct containing the 5’ TOP sequence when compared to the normal GFP mRNA control. A number of previous publications indicated that aberrant control of protein translation contributes to lymphomagenesis. RPS6 has been shown to control the formation of nascent ribosomal subunits and to participate in ribosomal biogenesis. An overabundance of RPS6 has been postulated to lead to an increase in the total number of ribosomes and change the profile of translated mRNAs, including messages with a low affinity for the translation machinery i.e., oncogenic mRNAs. To investigate the possibility that RPS6 is overexpressed in lymphoma, we screened a panel of DLBCL samples for RPS6 protein levels. Utilizing immunohistochemistry, we observed that RPS6 protein levels were significantly increased in DLBCL compared to B cells found in the germinal center of matched normal reactive lymph nodes. Finally, using short hairpin RNA (shRNA) targeting RPS6 we demonstrated significantly increased apoptosis in DLBCL cell lines when compared to control shRNA. Our work sheds light on how RPS6 may regulate the translation of mRNA containing a 5’ TOP sequence through a direct protein-mRNA interaction and has potential therapeutic implications for targeting RPS6 in lymphoid malignancies. Note: This absTract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {AbsTract title} [absTract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):AbsTract nr 3159.
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AbsTract 3159: RPS6 controls the translation of 5’ Terminal Oligopyrimidine Tract-containing mRNAs through a physical interaction that regulates the loading of these messages on the polysome
Cancer Research, 2010Co-Authors: P R Hagner, Krystyna Mazan-mamczarz, R B GartenhausAbstract:The prevailing paradigm for mTOR signaling implicates RPS6 activation in translational control of mRNAs characterized by the presence of an Oligopyrimidine Tract (5’ Terminal Oligopyrimidine) within the 5’ untranslated region. These messages containing an Oligopyrimidine Tract are important for ribosomal biogenesis as they encode most of the translational apparatus. However, mechanistic details of how RPS6 is involved in the regulation of these Oligopyrimidine Tract-containing messages are still poorly understood. We demonstrated that through small inhibitory RNA (siRNA) knockdown of RPS6, 5’ TOP mRNA were selectively upregulated in heavy polysomal fractions. The ability of RPS6 to interact with endogenous mRNA containing 5’ TOP sequences was tested by immunoprecipitation (IP) analysis using lysates from Diffuse Large B-cell Lymphoma (DLBCL) cell lines (Farage and OCI-LY10) and a specific RPS6 antibody. The association of RPS6 with 5’ TOP mRNA was interrogated using RT-qPCR to examine mRNAs isolated from the IP material using primer sets specific for multiple 5’ TOP mRNAs. We found that 5’ TOP containing mRNA were highly enriched in IP material obtained with anti-RPS6 antibody compared with the background level of amplification seen in control immunoglobulin G (IgG) IP. We constructed a heterologous green fluorescent protein (GFP) mRNA containing the 5’ TOP sequence from the RPS6 gene in the 5’ UTR. Using mRNP-IP assays, RPS6 was found to interact with the heterologous construct containing the 5’ TOP sequence when compared to the normal GFP mRNA control. A number of previous publications indicated that aberrant control of protein translation contributes to lymphomagenesis. RPS6 has been shown to control the formation of nascent ribosomal subunits and to participate in ribosomal biogenesis. An overabundance of RPS6 has been postulated to lead to an increase in the total number of ribosomes and change the profile of translated mRNAs, including messages with a low affinity for the translation machinery i.e., oncogenic mRNAs. To investigate the possibility that RPS6 is overexpressed in lymphoma, we screened a panel of DLBCL samples for RPS6 protein levels. Utilizing immunohistochemistry, we observed that RPS6 protein levels were significantly increased in DLBCL compared to B cells found in the germinal center of matched normal reactive lymph nodes. Finally, using short hairpin RNA (shRNA) targeting RPS6 we demonstrated significantly increased apoptosis in DLBCL cell lines when compared to control shRNA. Our work sheds light on how RPS6 may regulate the translation of mRNA containing a 5’ TOP sequence through a direct protein-mRNA interaction and has potential therapeutic implications for targeting RPS6 in lymphoid malignancies. Note: This absTract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {AbsTract title} [absTract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):AbsTract nr 3159.
P R Hagner - One of the best experts on this subject based on the ideXlab platform.
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Ribosomal protein S6 is highly expressed in non-Hodgkin lymphoma and associates with mRNA containing a 5′ Terminal Oligopyrimidine Tract
Oncogene, 2011Co-Authors: P R Hagner, K Mazan-mamczarz, E M Balzer, S Corl, S S Martin, X F Zhao, R B GartenhausAbstract:The molecular mechanism(s) linking tumorigenesis and morphological alterations in the nucleolus are presently coming into focus. The nucleolus is the cellular organelle in which the formation of ribosomal subunits occurs. Ribosomal biogenesis occurs through the transcription of ribosomal RNA (rRNA), rRNA processing and production of ribosomal proteins. An error in any of these processes may lead to deregulated cellular translation, evident in multiple cancers and ‘ribosomopathies’. Deregulated protein synthesis may be achieved through the overexpression of ribosomal proteins as seen in primary leukemic blasts with elevated levels of ribosomal proteins S11 and S14. In this study, we demonstrate that ribosomal protein S6 (RPS6) is highly expressed in primary diffuse large B-cell lymphoma (DLBCL) samples. Genetic modulation of RPS6 protein levels with specifically targeted short hairpin RNA (shRNA) lentiviruses led to a decrease in the actively proliferating population of cells compared with control shRNA. Low-dose rapamycin treatments have been shown to affect the translation of 5′ Terminal Oligopyrimidine (5′ TOP) Tract mRNA, which encodes the translational machinery, implicating RPS6 in 5′ TOP translation. Recently, it was shown that disruption of 40S ribosomal biogenesis through specific small inhibitory RNA knockdown of RPS6 defined RPS6 as a critical regulator of 5′ TOP translation. For the first time, we show that RPS6 associates with multiple mRNAs containing a 5′ TOP Tract. These findings expand our understanding of the mechanism(s) involved in ribosomal biogenesis and deregulated protein synthesis in DLBCL.
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ribosomal protein s6 is highly expressed in non hodgkin lymphoma and associates with mrna containing a 5 Terminal Oligopyrimidine Tract
Oncogene, 2011Co-Authors: P R Hagner, E M Balzer, S Corl, S S Martin, X F Zhao, R B Gartenhaus, Krystyna MazanmamczarzAbstract:The molecular mechanism(s) linking tumorigenesis and morphological alterations in the nucleolus are presently coming into focus. The nucleolus is the cellular organelle in which the formation of ribosomal subunits occurs. Ribosomal biogenesis occurs through the transcription of ribosomal RNA (rRNA), rRNA processing and production of ribosomal proteins. An error in any of these processes may lead to deregulated cellular translation, evident in multiple cancers and ‘ribosomopathies’. Deregulated protein synthesis may be achieved through the overexpression of ribosomal proteins as seen in primary leukemic blasts with elevated levels of ribosomal proteins S11 and S14. In this study, we demonstrate that ribosomal protein S6 (RPS6) is highly expressed in primary diffuse large B-cell lymphoma (DLBCL) samples. Genetic modulation of RPS6 protein levels with specifically targeted short hairpin RNA (shRNA) lentiviruses led to a decrease in the actively proliferating population of cells compared with control shRNA. Low-dose rapamycin treatments have been shown to affect the translation of 5′ Terminal Oligopyrimidine (5′ TOP) Tract mRNA, which encodes the translational machinery, implicating RPS6 in 5′ TOP translation. Recently, it was shown that disruption of 40S ribosomal biogenesis through specific small inhibitory RNA knockdown of RPS6 defined RPS6 as a critical regulator of 5′ TOP translation. For the first time, we show that RPS6 associates with multiple mRNAs containing a 5′ TOP Tract. These findings expand our understanding of the mechanism(s) involved in ribosomal biogenesis and deregulated protein synthesis in DLBCL.
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absTract 3159 rps6 controls the translation of 5 Terminal Oligopyrimidine Tract containing mrnas through a physical interaction that regulates the loading of these messages on the polysome
Cancer Research, 2010Co-Authors: P R Hagner, Krystyna Mazanmamczarz, R B GartenhausAbstract:The prevailing paradigm for mTOR signaling implicates RPS6 activation in translational control of mRNAs characterized by the presence of an Oligopyrimidine Tract (5’ Terminal Oligopyrimidine) within the 5’ untranslated region. These messages containing an Oligopyrimidine Tract are important for ribosomal biogenesis as they encode most of the translational apparatus. However, mechanistic details of how RPS6 is involved in the regulation of these Oligopyrimidine Tract-containing messages are still poorly understood. We demonstrated that through small inhibitory RNA (siRNA) knockdown of RPS6, 5’ TOP mRNA were selectively upregulated in heavy polysomal fractions. The ability of RPS6 to interact with endogenous mRNA containing 5’ TOP sequences was tested by immunoprecipitation (IP) analysis using lysates from Diffuse Large B-cell Lymphoma (DLBCL) cell lines (Farage and OCI-LY10) and a specific RPS6 antibody. The association of RPS6 with 5’ TOP mRNA was interrogated using RT-qPCR to examine mRNAs isolated from the IP material using primer sets specific for multiple 5’ TOP mRNAs. We found that 5’ TOP containing mRNA were highly enriched in IP material obtained with anti-RPS6 antibody compared with the background level of amplification seen in control immunoglobulin G (IgG) IP. We constructed a heterologous green fluorescent protein (GFP) mRNA containing the 5’ TOP sequence from the RPS6 gene in the 5’ UTR. Using mRNP-IP assays, RPS6 was found to interact with the heterologous construct containing the 5’ TOP sequence when compared to the normal GFP mRNA control. A number of previous publications indicated that aberrant control of protein translation contributes to lymphomagenesis. RPS6 has been shown to control the formation of nascent ribosomal subunits and to participate in ribosomal biogenesis. An overabundance of RPS6 has been postulated to lead to an increase in the total number of ribosomes and change the profile of translated mRNAs, including messages with a low affinity for the translation machinery i.e., oncogenic mRNAs. To investigate the possibility that RPS6 is overexpressed in lymphoma, we screened a panel of DLBCL samples for RPS6 protein levels. Utilizing immunohistochemistry, we observed that RPS6 protein levels were significantly increased in DLBCL compared to B cells found in the germinal center of matched normal reactive lymph nodes. Finally, using short hairpin RNA (shRNA) targeting RPS6 we demonstrated significantly increased apoptosis in DLBCL cell lines when compared to control shRNA. Our work sheds light on how RPS6 may regulate the translation of mRNA containing a 5’ TOP sequence through a direct protein-mRNA interaction and has potential therapeutic implications for targeting RPS6 in lymphoid malignancies. Note: This absTract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {AbsTract title} [absTract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):AbsTract nr 3159.
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AbsTract 3159: RPS6 controls the translation of 5’ Terminal Oligopyrimidine Tract-containing mRNAs through a physical interaction that regulates the loading of these messages on the polysome
Cancer Research, 2010Co-Authors: P R Hagner, Krystyna Mazan-mamczarz, R B GartenhausAbstract:The prevailing paradigm for mTOR signaling implicates RPS6 activation in translational control of mRNAs characterized by the presence of an Oligopyrimidine Tract (5’ Terminal Oligopyrimidine) within the 5’ untranslated region. These messages containing an Oligopyrimidine Tract are important for ribosomal biogenesis as they encode most of the translational apparatus. However, mechanistic details of how RPS6 is involved in the regulation of these Oligopyrimidine Tract-containing messages are still poorly understood. We demonstrated that through small inhibitory RNA (siRNA) knockdown of RPS6, 5’ TOP mRNA were selectively upregulated in heavy polysomal fractions. The ability of RPS6 to interact with endogenous mRNA containing 5’ TOP sequences was tested by immunoprecipitation (IP) analysis using lysates from Diffuse Large B-cell Lymphoma (DLBCL) cell lines (Farage and OCI-LY10) and a specific RPS6 antibody. The association of RPS6 with 5’ TOP mRNA was interrogated using RT-qPCR to examine mRNAs isolated from the IP material using primer sets specific for multiple 5’ TOP mRNAs. We found that 5’ TOP containing mRNA were highly enriched in IP material obtained with anti-RPS6 antibody compared with the background level of amplification seen in control immunoglobulin G (IgG) IP. We constructed a heterologous green fluorescent protein (GFP) mRNA containing the 5’ TOP sequence from the RPS6 gene in the 5’ UTR. Using mRNP-IP assays, RPS6 was found to interact with the heterologous construct containing the 5’ TOP sequence when compared to the normal GFP mRNA control. A number of previous publications indicated that aberrant control of protein translation contributes to lymphomagenesis. RPS6 has been shown to control the formation of nascent ribosomal subunits and to participate in ribosomal biogenesis. An overabundance of RPS6 has been postulated to lead to an increase in the total number of ribosomes and change the profile of translated mRNAs, including messages with a low affinity for the translation machinery i.e., oncogenic mRNAs. To investigate the possibility that RPS6 is overexpressed in lymphoma, we screened a panel of DLBCL samples for RPS6 protein levels. Utilizing immunohistochemistry, we observed that RPS6 protein levels were significantly increased in DLBCL compared to B cells found in the germinal center of matched normal reactive lymph nodes. Finally, using short hairpin RNA (shRNA) targeting RPS6 we demonstrated significantly increased apoptosis in DLBCL cell lines when compared to control shRNA. Our work sheds light on how RPS6 may regulate the translation of mRNA containing a 5’ TOP sequence through a direct protein-mRNA interaction and has potential therapeutic implications for targeting RPS6 in lymphoid malignancies. Note: This absTract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {AbsTract title} [absTract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):AbsTract nr 3159.
Jack O Hensold - One of the best experts on this subject based on the ideXlab platform.
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s6 phosphorylation independent pathways regulate translation of 5 Terminal Oligopyrimidine Tract containing mrnas in differentiating hematopoietic cells
Nucleic Acids Research, 2002Co-Authors: Diane Barthbaus, Oded Meyuhas, Carl A Stratton, Lou Parrott, Howard Myerson, Dennis J Templeton, Gary E Landreth, Jack O HensoldAbstract:Synthesis of new ribosomes is an energy costly and thus highly regulated process. Ribosomal protein synthesis is controlled by regulating translation of the corresponding ribosomal protein (rp)mRNAs. In mammalian cells a 5′-Terminal Oligopyrimidine Tract (TOP) is a conserved feature of these mRNAs that has been demonstrated to be essential for their translational regulation. Translation of TOP mRNAs has been proposed to be regulated by phosphorylation of ribosomal protein S6, which is a common effect of mitogenic stimulation of cells. However, as demonstrated here, S6 phosphorylation is not detectable in murine erythroleukemia (MEL) or other hematopoietic cells. The absence of S6 phosphorylation appears to be due to the action of a phosphatase that acts downstream of S6 kinase, presumably on S6 itself. Despite the absence of changes in S6 phosphorylation, translation of TOP mRNAs is repressed during differentiation of MEL cells. These data demonstrate the existence of a mechanism for regulating S6 phosphorylation that is distinct from kinase activation, as well as the existence of mechanisms for regulating translation of TOP mRNAs that are independent of S6 phosphorylation.
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S6 phosphorylation-independent pathways regulate translation of 5′-Terminal Oligopyrimidine Tract-containing mRNAs in differentiating hematopoietic cells
Nucleic Acids Research, 2002Co-Authors: Diane Barth-baus, Oded Meyuhas, Carl A Stratton, Lou Parrott, Howard Myerson, Dennis J Templeton, Gary E Landreth, Jack O HensoldAbstract:Synthesis of new ribosomes is an energy costly and thus highly regulated process. Ribosomal protein synthesis is controlled by regulating translation of the corresponding ribosomal protein (rp)mRNAs. In mammalian cells a 5′-Terminal Oligopyrimidine Tract (TOP) is a conserved feature of these mRNAs that has been demonstrated to be essential for their translational regulation. Translation of TOP mRNAs has been proposed to be regulated by phosphorylation of ribosomal protein S6, which is a common effect of mitogenic stimulation of cells. However, as demonstrated here, S6 phosphorylation is not detectable in murine erythroleukemia (MEL) or other hematopoietic cells. The absence of S6 phosphorylation appears to be due to the action of a phosphatase that acts downstream of S6 kinase, presumably on S6 itself. Despite the absence of changes in S6 phosphorylation, translation of TOP mRNAs is repressed during differentiation of MEL cells. These data demonstrate the existence of a mechanism for regulating S6 phosphorylation that is distinct from kinase activation, as well as the existence of mechanisms for regulating translation of TOP mRNAs that are independent of S6 phosphorylation.
Wayne S Sossin - One of the best experts on this subject based on the ideXlab platform.
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translation of 5 Terminal Oligopyrimidine Tract 5 top mrnas in aplysia californica is regulated by the target of rapamycin tor
Biochemical and Biophysical Research Communications, 2011Co-Authors: Margaret Labban, Wayne S SossinAbstract:Aplysia californica is a model organism for determining the molecular basis of memory. In this system identified synaptic changes have been closely linked to behavioral memories. Long-term sensitization and long-term synaptic changes between sensory neurons and motor neurons require both gene expression followed by translational control of the newly expressed mRNAs. One important mechanism for translational control is mediated through the target of rapamycin (TOR) and one mechanism downstream of TOR is the translational control of mRNAs containing a 5′ Terminal Oligopyrimidine Tract (5′TOP) sequence in their mRNA transcript. These include all ribosomal proteins, elongation factors and a few other translational regulators. TOR regulation of 5′TOP mRNAs in vertebrates is thought to be due to TOR dependent removal of the translational repression mediated by the 5′TOP sequence. Here, we show that this mechanism is similar in Aplysia, whereby Aplysia 5′TOP mRNAs are repressed under basal conditions and this repression is removed by serotonin in a rapamycin-sensitive manner.
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Translation of 5′ Terminal Oligopyrimidine Tract (5′TOP) mRNAs in Aplysia Californica is regulated by the target of rapamycin (TOR)
Biochemical and Biophysical Research Communications, 2010Co-Authors: Margaret Labban, Wayne S SossinAbstract:Aplysia californica is a model organism for determining the molecular basis of memory. In this system identified synaptic changes have been closely linked to behavioral memories. Long-term sensitization and long-term synaptic changes between sensory neurons and motor neurons require both gene expression followed by translational control of the newly expressed mRNAs. One important mechanism for translational control is mediated through the target of rapamycin (TOR) and one mechanism downstream of TOR is the translational control of mRNAs containing a 5′ Terminal Oligopyrimidine Tract (5′TOP) sequence in their mRNA transcript. These include all ribosomal proteins, elongation factors and a few other translational regulators. TOR regulation of 5′TOP mRNAs in vertebrates is thought to be due to TOR dependent removal of the translational repression mediated by the 5′TOP sequence. Here, we show that this mechanism is similar in Aplysia, whereby Aplysia 5′TOP mRNAs are repressed under basal conditions and this repression is removed by serotonin in a rapamycin-sensitive manner.