The Experts below are selected from a list of 87 Experts worldwide ranked by ideXlab platform
Fuyuhiko Tamanoi - One of the best experts on this subject based on the ideXlab platform.
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Rheb Protein binds cad carbamoyl phosphate synthetase 2 aspartate transcarbamoylase and dihydroorotase Protein in a gtp and effector domain dependent manner and influences its cellular localization and carbamoyl phosphate synthetase cpsase activity
Journal of Biological Chemistry, 2015Co-Authors: Tatsuhiro Sato, Hitomi Akasu, Wataru Shimono, Chisa Matsu, Jeffrey J Heard, Yoshio Shibagaki, Yuki Fujiwara, Fuyuhiko Tamanoi, Seisuke HattoriAbstract:Abstract Rheb small GTPases, which consist of Rheb1 and Rheb2 (also known as RhebL1) in mammalian cells, are unique members of the Ras superfamily and play central roles in regulating Protein synthesis and cell growth by activating mTOR. To gain further insight into the function of Rheb, we carried out a search for Rheb-binding Proteins and found that Rheb binds to CAD Protein (carbamoyl-phosphate synthetase 2, aspartate transcarbamoylase, and dihydroorotase), a multifunctional enzyme required for the de novo synthesis of pyrimidine nucleotides. CAD binding is more pronounced with Rheb2 than with Rheb1. Rheb binds CAD in a GTP- and effector domain-dependent manner. The region of CAD where Rheb binds is located at the C-terminal region of the carbamoyl-phosphate synthetase domain and not in the dihydroorotase and aspartate transcarbamoylase domains. Rheb stimulated carbamoyl-phosphate synthetase activity of CAD in vitro. In addition, an elevated level of intracellular UTP pyrimidine nucleotide was observed in Tsc2-deficient cells, which was attenuated by knocking down of Rheb. Immunostaining analysis showed that expression of Rheb leads to increased accumulation of CAD on lysosomes. Both a farnesyltransferase inhibitor that blocks membrane association of Rheb and knockdown of Rheb mislocalized CAD. These results establish CAD as a downstream effector of Rheb and suggest a possible role of Rheb in regulating de novo pyrimidine nucleotide synthesis.
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Farnesyltransferase inhibitors reverse altered growth and distribution of actin filaments in Tsc-deficient cells via inhibition of both rapamycin-sensitive and -insensitive pathways
Molecular cancer therapeutics, 2005Co-Authors: Chia-ling Gau, Juran Kato-stankiewicz, Chen Jiang, Susie Miyamoto, Lea Guo, Fuyuhiko TamanoiAbstract:Farnesyltransferase inhibitors (FTI) have been developed as anticancer drugs and are currently being evaluated in clinical trials. In this study, we have examined the effects of FTIs on Tsc -null cells to gain insight into their effects on farnesylated Rheb GTPase. This Protein is involved in the activation of mTOR/S6K signaling and is down-regulated by the Tsc1/Tsc2 complex. Both Tsc1 −/− and Tsc2 −/− mouse embryonic fibroblasts exhibit constitutive activation of S6K and grow in the absence of serum. Two different FTI compounds, the clinical compound BMS-214662 and the newly described BMS-225975, inhibit the constitutive activation of mTOR/S6K signaling and block serum-free growth of the Tsc -null mouse embryonic fibroblasts. We have also found that Tsc -null mouse embryonic fibroblasts grow under anchorage-independent conditions and that both FTI compounds inhibit this soft agar growth. These FTI effects are similar to those observed with rapamycin. Another interesting phenotype of Tsc -null mouse embryonic fibroblasts is that they are round and contain actin filaments predominantly at the cell periphery. The addition of FTIs, but not rapamycin, led to the reappearance of intracellular actin filaments and reduction of peripheral actin filaments. The ability of FTI to rearrange actin filaments seems to be largely mediated by the inhibition of Rheb Protein, as induction of intracellular actin filaments by FTI was much less efficient in Tsc2 -null cells expressing Rheb (M184L), a geranylgeranylated mutant Rheb that can bypass farnesylation. These results reveal that FTIs inhibit Rheb, causing two different effects in Tsc -deficient cells, one on growth and the other on actin filament distribution.
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failure to farnesylate Rheb Protein contributes to the enrichment of g0 g1 phase cells in the schizosaccharomyces pombe farnesyltransferase mutant
Molecular Microbiology, 2001Co-Authors: Wenli Yang, Angel P Tabancay, Jun Urano, Fuyuhiko TamanoiAbstract:Protein farnesylation is important for a number of physiological processes, including proliferation and cell morphology. The Schizosaccharomyces pombe mutant, cpp1-, defective in farnesylation, exhibits distinct phenotypes, including morphological changes and sensitivity to the arginine analogue, canavanine. In this work, we report a novel phenotype of this mutant, enrichment of G0/G1 phase cells. This phenotype results mainly from the inability to farnesylate the Rheb G-Protein, as normal cell cycle progression can be restored to the mutant by expressing a mutant form of SpRheb (SpRheb-CVIL) that can bypass farnesylation. In contrast, a farnesylation-defective mutant of SpRheb (SpRheb-SVIA) is incapable of restoring the normal cell cycle profile to the cpp1- mutant. Inhibition of SpRheb expression leads to the accumulation of cells at the G0/G1 phase of the cell cycle. This growth arrest phenotype of the spRheb- disruption can be complemented by the introduction of wild-type spRheb+. The complementation is dependent on farnesylation, as the farnesylation-defective SpRheb-SVIA mutant is incapable of complementing the spRheb- disruption. Other mutants of SpRheb, E40K and S20N, are also incapable of complementing the spRheb- disruption. Furthermore, efficient complementation can be obtained by the expression of human Rheb but not Saccharomyces cerevisiae Rheb. Our findings suggest that Protein farnesylation is important for cell cycle progression of S. pombe cells and that farnesylated SpRheb is critical in this process.
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Failure to farnesylate Rheb Protein contributes to the enrichment of G0/G1 phase cells in the Schizosaccharomyces pombe farnesyltransferase mutant.
Molecular microbiology, 2001Co-Authors: Wenli Yang, Angel P Tabancay, Jun Urano, Fuyuhiko TamanoiAbstract:Protein farnesylation is important for a number of physiological processes, including proliferation and cell morphology. The Schizosaccharomyces pombe mutant, cpp1-, defective in farnesylation, exhibits distinct phenotypes, including morphological changes and sensitivity to the arginine analogue, canavanine. In this work, we report a novel phenotype of this mutant, enrichment of G0/G1 phase cells. This phenotype results mainly from the inability to farnesylate the Rheb G-Protein, as normal cell cycle progression can be restored to the mutant by expressing a mutant form of SpRheb (SpRheb-CVIL) that can bypass farnesylation. In contrast, a farnesylation-defective mutant of SpRheb (SpRheb-SVIA) is incapable of restoring the normal cell cycle profile to the cpp1- mutant. Inhibition of SpRheb expression leads to the accumulation of cells at the G0/G1 phase of the cell cycle. This growth arrest phenotype of the spRheb- disruption can be complemented by the introduction of wild-type spRheb+. The complementation is dependent on farnesylation, as the farnesylation-defective SpRheb-SVIA mutant is incapable of complementing the spRheb- disruption. Other mutants of SpRheb, E40K and S20N, are also incapable of complementing the spRheb- disruption. Furthermore, efficient complementation can be obtained by the expression of human Rheb but not Saccharomyces cerevisiae Rheb. Our findings suggest that Protein farnesylation is important for cell cycle progression of S. pombe cells and that farnesylated SpRheb is critical in this process.
Wenli Yang - One of the best experts on this subject based on the ideXlab platform.
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failure to farnesylate Rheb Protein contributes to the enrichment of g0 g1 phase cells in the schizosaccharomyces pombe farnesyltransferase mutant
Molecular Microbiology, 2001Co-Authors: Wenli Yang, Angel P Tabancay, Jun Urano, Fuyuhiko TamanoiAbstract:Protein farnesylation is important for a number of physiological processes, including proliferation and cell morphology. The Schizosaccharomyces pombe mutant, cpp1-, defective in farnesylation, exhibits distinct phenotypes, including morphological changes and sensitivity to the arginine analogue, canavanine. In this work, we report a novel phenotype of this mutant, enrichment of G0/G1 phase cells. This phenotype results mainly from the inability to farnesylate the Rheb G-Protein, as normal cell cycle progression can be restored to the mutant by expressing a mutant form of SpRheb (SpRheb-CVIL) that can bypass farnesylation. In contrast, a farnesylation-defective mutant of SpRheb (SpRheb-SVIA) is incapable of restoring the normal cell cycle profile to the cpp1- mutant. Inhibition of SpRheb expression leads to the accumulation of cells at the G0/G1 phase of the cell cycle. This growth arrest phenotype of the spRheb- disruption can be complemented by the introduction of wild-type spRheb+. The complementation is dependent on farnesylation, as the farnesylation-defective SpRheb-SVIA mutant is incapable of complementing the spRheb- disruption. Other mutants of SpRheb, E40K and S20N, are also incapable of complementing the spRheb- disruption. Furthermore, efficient complementation can be obtained by the expression of human Rheb but not Saccharomyces cerevisiae Rheb. Our findings suggest that Protein farnesylation is important for cell cycle progression of S. pombe cells and that farnesylated SpRheb is critical in this process.
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Failure to farnesylate Rheb Protein contributes to the enrichment of G0/G1 phase cells in the Schizosaccharomyces pombe farnesyltransferase mutant.
Molecular microbiology, 2001Co-Authors: Wenli Yang, Angel P Tabancay, Jun Urano, Fuyuhiko TamanoiAbstract:Protein farnesylation is important for a number of physiological processes, including proliferation and cell morphology. The Schizosaccharomyces pombe mutant, cpp1-, defective in farnesylation, exhibits distinct phenotypes, including morphological changes and sensitivity to the arginine analogue, canavanine. In this work, we report a novel phenotype of this mutant, enrichment of G0/G1 phase cells. This phenotype results mainly from the inability to farnesylate the Rheb G-Protein, as normal cell cycle progression can be restored to the mutant by expressing a mutant form of SpRheb (SpRheb-CVIL) that can bypass farnesylation. In contrast, a farnesylation-defective mutant of SpRheb (SpRheb-SVIA) is incapable of restoring the normal cell cycle profile to the cpp1- mutant. Inhibition of SpRheb expression leads to the accumulation of cells at the G0/G1 phase of the cell cycle. This growth arrest phenotype of the spRheb- disruption can be complemented by the introduction of wild-type spRheb+. The complementation is dependent on farnesylation, as the farnesylation-defective SpRheb-SVIA mutant is incapable of complementing the spRheb- disruption. Other mutants of SpRheb, E40K and S20N, are also incapable of complementing the spRheb- disruption. Furthermore, efficient complementation can be obtained by the expression of human Rheb but not Saccharomyces cerevisiae Rheb. Our findings suggest that Protein farnesylation is important for cell cycle progression of S. pombe cells and that farnesylated SpRheb is critical in this process.
Seisuke Hattori - One of the best experts on this subject based on the ideXlab platform.
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Rheb Protein binds cad carbamoyl phosphate synthetase 2 aspartate transcarbamoylase and dihydroorotase Protein in a gtp and effector domain dependent manner and influences its cellular localization and carbamoyl phosphate synthetase cpsase activity
Journal of Biological Chemistry, 2015Co-Authors: Tatsuhiro Sato, Hitomi Akasu, Wataru Shimono, Chisa Matsu, Jeffrey J Heard, Yoshio Shibagaki, Yuki Fujiwara, Fuyuhiko Tamanoi, Seisuke HattoriAbstract:Abstract Rheb small GTPases, which consist of Rheb1 and Rheb2 (also known as RhebL1) in mammalian cells, are unique members of the Ras superfamily and play central roles in regulating Protein synthesis and cell growth by activating mTOR. To gain further insight into the function of Rheb, we carried out a search for Rheb-binding Proteins and found that Rheb binds to CAD Protein (carbamoyl-phosphate synthetase 2, aspartate transcarbamoylase, and dihydroorotase), a multifunctional enzyme required for the de novo synthesis of pyrimidine nucleotides. CAD binding is more pronounced with Rheb2 than with Rheb1. Rheb binds CAD in a GTP- and effector domain-dependent manner. The region of CAD where Rheb binds is located at the C-terminal region of the carbamoyl-phosphate synthetase domain and not in the dihydroorotase and aspartate transcarbamoylase domains. Rheb stimulated carbamoyl-phosphate synthetase activity of CAD in vitro. In addition, an elevated level of intracellular UTP pyrimidine nucleotide was observed in Tsc2-deficient cells, which was attenuated by knocking down of Rheb. Immunostaining analysis showed that expression of Rheb leads to increased accumulation of CAD on lysosomes. Both a farnesyltransferase inhibitor that blocks membrane association of Rheb and knockdown of Rheb mislocalized CAD. These results establish CAD as a downstream effector of Rheb and suggest a possible role of Rheb in regulating de novo pyrimidine nucleotide synthesis.
Paul D. Adams - One of the best experts on this subject based on the ideXlab platform.
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Preliminary Characterization of the Protein Interaction of the Ras-Related Protein Rheb and Tuberous Sclerosis 2 (TSC2)
Biophysical Journal, 2015Co-Authors: Kyla M. Morris, Paul D. AdamsAbstract:The Tuberous sclerosis complex (1 and 2) has been implicated in benign tumorigenesis in humans. TSC2 is the GTPase activating Protein toward the Rheb, and a number of mutations that are localized to the GTPase-binding domain of TSC2 have been found in patients with tuberous sclerosis. This suggests that altered interactions involving TSC2 with Rheb may signal activity leading to the disease-state. As such, understanding the details of TSC2's interaction with Rheb is extremely important for future therapeutic approaches to be developed targeted at inhibiting abnormal Rheb signaling activity. Moreover, a major challenge still facing the biomedical community is the limited availability of therapeutic strategies to tackle this disease. As such, understanding the details of TSC2's interaction with Rheb is critical for future therapeutic approaches to be developed targeted at inhibiting over-active Rheb signaling activity. Our central hypothesis is that there are unique molecular features of the Rheb-TSC2 Protein interaction that can be exploited, once known, to underscore these Proteins’ roles in abnormal biochemical cell signaling leading to tuberous sclerosis. To this end, we have characterized the Ras-related Rheb complexed to a truncated Tuberous sclerosis complex 2 (TSC2) wild type construct, TSC2-218, and a single-point mutant of TSC2-218 using various biophysical and biochemical techniques. The characterization studies presented highlight the potential importance of subsequent efforts to provide a detailed characterization of the molecular features of the TSC2-218-Rheb Protein-Protein interface.
Jun Urano - One of the best experts on this subject based on the ideXlab platform.
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failure to farnesylate Rheb Protein contributes to the enrichment of g0 g1 phase cells in the schizosaccharomyces pombe farnesyltransferase mutant
Molecular Microbiology, 2001Co-Authors: Wenli Yang, Angel P Tabancay, Jun Urano, Fuyuhiko TamanoiAbstract:Protein farnesylation is important for a number of physiological processes, including proliferation and cell morphology. The Schizosaccharomyces pombe mutant, cpp1-, defective in farnesylation, exhibits distinct phenotypes, including morphological changes and sensitivity to the arginine analogue, canavanine. In this work, we report a novel phenotype of this mutant, enrichment of G0/G1 phase cells. This phenotype results mainly from the inability to farnesylate the Rheb G-Protein, as normal cell cycle progression can be restored to the mutant by expressing a mutant form of SpRheb (SpRheb-CVIL) that can bypass farnesylation. In contrast, a farnesylation-defective mutant of SpRheb (SpRheb-SVIA) is incapable of restoring the normal cell cycle profile to the cpp1- mutant. Inhibition of SpRheb expression leads to the accumulation of cells at the G0/G1 phase of the cell cycle. This growth arrest phenotype of the spRheb- disruption can be complemented by the introduction of wild-type spRheb+. The complementation is dependent on farnesylation, as the farnesylation-defective SpRheb-SVIA mutant is incapable of complementing the spRheb- disruption. Other mutants of SpRheb, E40K and S20N, are also incapable of complementing the spRheb- disruption. Furthermore, efficient complementation can be obtained by the expression of human Rheb but not Saccharomyces cerevisiae Rheb. Our findings suggest that Protein farnesylation is important for cell cycle progression of S. pombe cells and that farnesylated SpRheb is critical in this process.
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Failure to farnesylate Rheb Protein contributes to the enrichment of G0/G1 phase cells in the Schizosaccharomyces pombe farnesyltransferase mutant.
Molecular microbiology, 2001Co-Authors: Wenli Yang, Angel P Tabancay, Jun Urano, Fuyuhiko TamanoiAbstract:Protein farnesylation is important for a number of physiological processes, including proliferation and cell morphology. The Schizosaccharomyces pombe mutant, cpp1-, defective in farnesylation, exhibits distinct phenotypes, including morphological changes and sensitivity to the arginine analogue, canavanine. In this work, we report a novel phenotype of this mutant, enrichment of G0/G1 phase cells. This phenotype results mainly from the inability to farnesylate the Rheb G-Protein, as normal cell cycle progression can be restored to the mutant by expressing a mutant form of SpRheb (SpRheb-CVIL) that can bypass farnesylation. In contrast, a farnesylation-defective mutant of SpRheb (SpRheb-SVIA) is incapable of restoring the normal cell cycle profile to the cpp1- mutant. Inhibition of SpRheb expression leads to the accumulation of cells at the G0/G1 phase of the cell cycle. This growth arrest phenotype of the spRheb- disruption can be complemented by the introduction of wild-type spRheb+. The complementation is dependent on farnesylation, as the farnesylation-defective SpRheb-SVIA mutant is incapable of complementing the spRheb- disruption. Other mutants of SpRheb, E40K and S20N, are also incapable of complementing the spRheb- disruption. Furthermore, efficient complementation can be obtained by the expression of human Rheb but not Saccharomyces cerevisiae Rheb. Our findings suggest that Protein farnesylation is important for cell cycle progression of S. pombe cells and that farnesylated SpRheb is critical in this process.