The Experts below are selected from a list of 42054 Experts worldwide ranked by ideXlab platform
Richard A Cerione - One of the best experts on this subject based on the ideXlab platform.
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Cdc42 functions as a regulatory node for tumour‐derived microvesicle biogenesis
Journal of extracellular vesicles, 2021Co-Authors: Jing Wang, Richard A Cerione, Qiyu Feng, Xiangjin Zhuang, Kai Su Greene, Marc A. Antonyak, Joseph E. Druso, Kristin F. Wilson, Hongyang WangAbstract:Tumour-derived microvesicles (MVs) serve as critical mediators of cell-to-cell communication in the tumour microenvironment. So far, the underlying mechanisms of MV biogenesis, especially how key tumorigenesis signals such as abnormal EGF signalling regulates MV release, remain unclear. Here, we set out to establish reliable readouts for MV biogenesis and then explore the molecular mechanisms that regulate MV generation. We found that Rho family small G Protein Cdc42 is a convergent node of multiple regulatory signals that occur in MV biogenesis. The binding of activated GTP-bound Cdc42 and its downstream effector, Ras GTPase-activating-like Protein 1 (IQGAP1), is required for MV shedding. Activated Cdc42 maintains sustained EGF signalling by inhibiting the internalization of cell surface receptors, including EGFR and the VEGF oligomer, VEGF90K, and then facilitates MV release. Subsequently, we further demonstrated that blocking these signalling pathways using the corresponding mutants effectively reduced MV shedding and significantly inhibited MV-promoted in vivo tumour angiogenesis. These findings reveal a complex regulation of MV shedding by tumour cells, shedding light on the regulatory mechanism of MV biogenesis, and potentially contributing to strategies that target MVs in cancer therapy.
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optimal experimental design in an epidermal growth factor receptor signalling and down regulation model
Iet Systems Biology, 2007Co-Authors: Fergal P. Casey, Richard A Cerione, Dan Baird, Qiyu Feng, Ryan N. Gutenkunst, Joshua J. Waterfall, Christopher R. Myers, Kevin S. Brown, James P. SethnaAbstract:We apply the methods of optimal experimental design to a differential equation model for epidermal growth factor receptor signalling, trafficking and down-regulation. The model incor- porates the role of a recently discovered Protein complex made up of the E3 ubiquitin ligase, Cbl, the guanine exchange factor (GEF), Cool-1 (b-Pix) and the Rho family G Protein Cdc42. The complex has been suggested to be important in disrupting receptor down-regulation. We demon- strate that the model interactions can accurately reproduce the experimental observations, that they can be used to make predictions with accompanying uncertainties, and that we can apply ideas of optimal experimental design to suggest new experiments that reduce the uncertainty on unmeasurable components of the system. The epidermal growth factor receptor (EGFR) is a transmembrane tyrosine kinase receptor which becomes activated upon binding of its ligand, epidermal growth factor (EGF) and signals via phosphorylation of various effectors (1). Besides sending signals to downstream effectors, the activated EGFR also will initialise endo- cytosis which is followed by either degradation or recycling of the receptor. These are the normal receptor down- regulation processes. Persistence of activated receptor on the cell surface can lead to aberrant signalling and transformation of cells (2). In addition, a variety of tumour cells exhibit overexpressed or hyperactivated EGF receptor (3, 4), indicative of the failure of normal receptor down-regulation. We concern ourselves with building a mathematical model of the receptor endocytosis, recycling, degradation and signalling processes that can reproduce experimental data and incorporates the effects of regulating Proteins that themselves become active after EGF stimulation. The schematic for the model is shown in Fig. 1. In particular,
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Optimal experimental design in an EGFR signaling and down-regulation model
arXiv: Molecular Networks, 2006Co-Authors: Fergal P. Casey, Richard A Cerione, Dan Baird, Qiyu Feng, Ryan N. Gutenkunst, Joshua J. Waterfall, Christopher R. Myers, Kevin S. Brown, James P. SethnaAbstract:We apply the methods of optimal experimental design to a differential equation model for epidermal growth factor receptor (EGFR) signaling, trafficking, and down-regulation. The model incorporates the role of a recently discovered Protein complex made up of the E3 ubiquitin ligase, Cbl, the guanine exchange factor (GEF), Cool-1 (Beta-Pix), and the Rho family G Protein Cdc42. The complex has been suggested to be important in disrupting receptor down-regulation. We demonstrate that the model interactions can accurately reproduce the experimental observations, that they can be used to make predictions with accompanying uncertainties, and that we can apply ideas of optimal experimental design to suggest new experiments that reduce the uncertainty on unmeasurable components of the system.
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Measurement of epidermal growth factor receptor turnover and effects of Cdc42.
Methods in enzymology, 2006Co-Authors: Qiong Lin, Wannian Yang, Richard A CerioneAbstract:Ligand‐induced degradation represents an essential component of the overall regulation of EGF receptor (EGFR)–coupled signal transduction. Following activation, EGFRs are monoubiquitinated, subsequently sorted by ubiquitin‐interaction–based sorting machinery, and transported to multivesicular bodies (MVBs) and lysosomes for degradation. The Rho‐family small G‐Protein, Cdc42, has been implicated in the regulation of EGFR degradation. Here we describe routine methods for assaying EGFR endocytosis and degradation. In addition, we have introduced procedures for determining the effects of Cdc42 and its downstream targets, in particular, ACK (Activated Cdc42‐associated Kinase) and p85Cool‐1 (Cloned out of library)/Pix (for Pak‐interactive exchange factor), on EGFR degradation.
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Insulin-like growth factor-I diminishes the activation status and expression of the small GTPase Cdc42 in articular chondrocytes.
Journal of orthopaedic research : official publication of the Orthopaedic Research Society, 2004Co-Authors: Lisa A. Fortier, Molly M Deak, Stacy A. Semevolos, Richard A CerioneAbstract:Insulin-like growth factor-I (IGF-I) is an important anabolic growth factor in the maintenance of articular cartilage phenotypic expression. Chondrocyte morphology is also tightly linked to phenotype. The small G-Protein Cdc42 plays a key role in regulation of cell morphology and phenotypic expression in several cell types and, we show here, in articular chondrocytes. The purpose of these studies was to investigate possible links between the intracellular signaling pathways of IGF-I and Cdc42 in articular chondrocytes. Treatment of chondrocytes with IGF-I resulted in a rapid and sustained decrease in the activation state (decreased GTP-bound) of Cdc42. Nucleotide exchange and hydrolysis experiments suggest that the decreased activation occurs through increased hydrolysis. Transient expression of dominant-negative Cdc42(T17N) allowed for enhanced expression of normal chondrocyte phenotype as determined by increased mRNA expression of collagen type II (Coll II) with decreased matrix metalloProteinase-3 (MMP-3) expression. The results of these studies suggest a novel link between IGF-I and Cdc42 signaling pathways. Further, an additional mechanism for the regulation of chondrocyte phenotype is defined through the IGF-I induced down-regulation of Cdc42 activation.
Buhyun Youn - One of the best experts on this subject based on the ideXlab platform.
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TFAP2C-mediated upregulation of TGFBR1 promotes lung tumorigenesis and epithelial–mesenchymal transition
Experimental & molecular medicine, 2016Co-Authors: Wanyeon Kim, Eungi Kim, Sungmin Lee, Daehoon Kim, Jahyun Chun, Kang Hyun Park, Hyesook Youn, Buhyun YounAbstract:TFAP2C (transcription factor-activating enhancer-binding Protein 2C) expression has been positively correlated with poor prognosis in patients with certain types of cancer, but the mechanisms underlying TFAP2C-mediated tumorigenesis in non-small-cell lung cancer (NSCLC) are still unknown. We previously performed a microarray analysis to identify TFAP2C regulation genes, and TGFBR1 (transforming growth factor-β receptor type 1) was found to be upregulated by TFAP2C. We observed that TFAP2C or TGFBR1 overexpression led to oncogenic properties, such as cell viability, proliferation and cell cycle progression. TGFBR1 upregulation induced by TFAP2C also promoted cell motility and migration, leading to malignant development. We also found that PAK1 (p21 Protein (Cdc42/Rac)-activated kinase 1) signaling was involved in TFAP2C/TGFBR1-induced tumorigenesis. These results were confirmed by an in vivo xenograft model and patient tissue samples. This study shows that TFAP2C promoted tumor progression by upregulation of TGFBR1 and consequent activation of PAK1 signaling.
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TFAP2C-mediated upregulation of TGFBR1 promotes lung tumorigenesis and epithelial–mesenchymal transition
Experimental & Molecular Medicine, 2016Co-Authors: Wanyeon Kim, Eungi Kim, Sungmin Lee, Daehoon Kim, Jahyun Chun, Kang Hyun Park, Hyesook Youn, Buhyun YounAbstract:The gene regulatory Protein TFAP2C contributes to non-small cell lung cancer (NSCLC) by stimulating cell proliferation and motility. Although TFAP2C expression has previously been associated with cancer, little was known about how it contributes to tumor formation. BuHyun Youn at Pusan National University, Busan, and colleagues found that in NSCLC cell lines TFAP2C increases the levels of the cell surface receptor TGFBR1 and promotes cell survival and proliferation. They also showed that overexpression of this receptor leads to an increase in cell motility by activating the enzyme p21-activated kinase 1. High levels of TFACP2C and TGFBR1 are found in lung tissue of NSCLC patients and depletion of either in a mouse model of NSCLC reduces tumor size. Together, these findings highlight potential new drug targets for halting lung cancer progression. TFAP2C (transcription factor-activating enhancer-binding Protein 2C) expression has been positively correlated with poor prognosis in patients with certain types of cancer, but the mechanisms underlying TFAP2C-mediated tumorigenesis in non-small-cell lung cancer (NSCLC) are still unknown. We previously performed a microarray analysis to identify TFAP2C regulation genes, and TGFBR1 (transforming growth factor-β receptor type 1) was found to be upregulated by TFAP2C. We observed that TFAP2C or TGFBR1 overexpression led to oncogenic properties, such as cell viability, proliferation and cell cycle progression. TGFBR1 upregulation induced by TFAP2C also promoted cell motility and migration, leading to malignant development. We also found that PAK1 (p21 Protein (Cdc42/Rac)-activated kinase 1) signaling was involved in TFAP2C/TGFBR1-induced tumorigenesis. These results were confirmed by an in vivo xenograft model and patient tissue samples. This study shows that TFAP2C promoted tumor progression by upregulation of TGFBR1 and consequent activation of PAK1 signaling.
Wanyeon Kim - One of the best experts on this subject based on the ideXlab platform.
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TFAP2C-mediated upregulation of TGFBR1 promotes lung tumorigenesis and epithelial–mesenchymal transition
Experimental & molecular medicine, 2016Co-Authors: Wanyeon Kim, Eungi Kim, Sungmin Lee, Daehoon Kim, Jahyun Chun, Kang Hyun Park, Hyesook Youn, Buhyun YounAbstract:TFAP2C (transcription factor-activating enhancer-binding Protein 2C) expression has been positively correlated with poor prognosis in patients with certain types of cancer, but the mechanisms underlying TFAP2C-mediated tumorigenesis in non-small-cell lung cancer (NSCLC) are still unknown. We previously performed a microarray analysis to identify TFAP2C regulation genes, and TGFBR1 (transforming growth factor-β receptor type 1) was found to be upregulated by TFAP2C. We observed that TFAP2C or TGFBR1 overexpression led to oncogenic properties, such as cell viability, proliferation and cell cycle progression. TGFBR1 upregulation induced by TFAP2C also promoted cell motility and migration, leading to malignant development. We also found that PAK1 (p21 Protein (Cdc42/Rac)-activated kinase 1) signaling was involved in TFAP2C/TGFBR1-induced tumorigenesis. These results were confirmed by an in vivo xenograft model and patient tissue samples. This study shows that TFAP2C promoted tumor progression by upregulation of TGFBR1 and consequent activation of PAK1 signaling.
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TFAP2C-mediated upregulation of TGFBR1 promotes lung tumorigenesis and epithelial–mesenchymal transition
Experimental & Molecular Medicine, 2016Co-Authors: Wanyeon Kim, Eungi Kim, Sungmin Lee, Daehoon Kim, Jahyun Chun, Kang Hyun Park, Hyesook Youn, Buhyun YounAbstract:The gene regulatory Protein TFAP2C contributes to non-small cell lung cancer (NSCLC) by stimulating cell proliferation and motility. Although TFAP2C expression has previously been associated with cancer, little was known about how it contributes to tumor formation. BuHyun Youn at Pusan National University, Busan, and colleagues found that in NSCLC cell lines TFAP2C increases the levels of the cell surface receptor TGFBR1 and promotes cell survival and proliferation. They also showed that overexpression of this receptor leads to an increase in cell motility by activating the enzyme p21-activated kinase 1. High levels of TFACP2C and TGFBR1 are found in lung tissue of NSCLC patients and depletion of either in a mouse model of NSCLC reduces tumor size. Together, these findings highlight potential new drug targets for halting lung cancer progression. TFAP2C (transcription factor-activating enhancer-binding Protein 2C) expression has been positively correlated with poor prognosis in patients with certain types of cancer, but the mechanisms underlying TFAP2C-mediated tumorigenesis in non-small-cell lung cancer (NSCLC) are still unknown. We previously performed a microarray analysis to identify TFAP2C regulation genes, and TGFBR1 (transforming growth factor-β receptor type 1) was found to be upregulated by TFAP2C. We observed that TFAP2C or TGFBR1 overexpression led to oncogenic properties, such as cell viability, proliferation and cell cycle progression. TGFBR1 upregulation induced by TFAP2C also promoted cell motility and migration, leading to malignant development. We also found that PAK1 (p21 Protein (Cdc42/Rac)-activated kinase 1) signaling was involved in TFAP2C/TGFBR1-induced tumorigenesis. These results were confirmed by an in vivo xenograft model and patient tissue samples. This study shows that TFAP2C promoted tumor progression by upregulation of TGFBR1 and consequent activation of PAK1 signaling.
Marc W Kirschner - One of the best experts on this subject based on the ideXlab platform.
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the arp2 3 complex mediates actin polymerization induced by the small gtp binding Protein Cdc42
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Rajat Rohatgi, Marc W KirschnerAbstract:The small GTP-binding Protein Cdc42 is thought to induce filopodium formation by regulating actin polymerization at the cell cortex. Although several Cdc42-binding Proteins have been identified and some of them have been implicated in filopodium formation, the precise role of Cdc42 in modulating actin polymerization has not been defined. To understand the biochemical pathways that link Cdc42 to the actin cytoskeleton, we have reconstituted Cdc42-induced actin polymerization in Xenopus egg extracts. Using this cell-free system, we have developed a rapid and specific assay that has allowed us to fractionate the extract and isolate factors involved in this activity. We report here that at least two biochemically distinct components are required, based on their chromatographic behavior and affinity for Cdc42. One component is purified to homogeneity and is identified as the Arp2/3 complex, a Protein complex that has been shown to nucleate actin polymerization. However, the purified complex alone is not sufficient to mediate the activity; a second component that binds Cdc42 directly and mediates the interaction between Cdc42 and the complex also is required. These results establish an important link between a signaling molecule, Cdc42, and a complex that can directly modulate actin networks in vitro. We propose that activation of the Arp2/3 complex by Cdc42 and other signaling molecules plays a central role in stimulating actin polymerization at the cell surface.
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The Arp2/3 complex mediates actin polymerization induced by the small GTP-binding Protein Cdc42
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Rajat Rohatgi, Marc W KirschnerAbstract:The small GTP-binding Protein Cdc42 is thought to induce filopodium formation by regulating actin polymerization at the cell cortex. Although several Cdc42-binding Proteins have been identified and some of them have been implicated in filopodium formation, the precise role of Cdc42 in modulating actin polymerization has not been defined. To understand the biochemical pathways that link Cdc42 to the actin cytoskeleton, we have reconstituted Cdc42-induced actin polymerization in Xenopus egg extracts. Using this cell-free system, we have developed a rapid and specific assay that has allowed us to fractionate the extract and isolate factors involved in this activity. We report here that at least two biochemically distinct components are required, based on their chromatographic behavior and affinity for Cdc42. One component is purified to homogeneity and is identified as the Arp2/3 complex, a Protein complex that has been shown to nucleate actin polymerization. However, the purified complex alone is not sufficient to mediate the activity; a second component that binds Cdc42 directly and mediates the interaction between Cdc42 and the complex also is required. These results establish an important link between a signaling molecule, Cdc42, and a complex that can directly modulate actin networks in vitro. We propose that activation of the Arp2/3 complex by Cdc42 and other signaling molecules plays a central role in stimulating actin polymerization at the cell surface.
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Corequirement of Specific Phosphoinositides and Small GTP-binding Protein Cdc42 in Inducing Actin Assembly in Xenopus Egg Extracts
The Journal of cell biology, 1998Co-Authors: Lewis C. Cantley, Paul A. Janmey, Marc W KirschnerAbstract:Both phosphoinositides and small GTP-binding Proteins of the Rho family have been postulated to regulate actin assembly in cells. We have reconstituted actin assembly in response to these signals in Xenopus extracts and examined the relationship of these pathways. We have found that GTPγS stimulates actin assembly in the presence of endogenous membrane vesicles in low speed extracts. These membrane vesicles are required, but can be replaced by lipid vesicles prepared from purified phospholipids containing phosphoinositides. Vesicles containing phosphatidylinositol (4,5) bisphosphate or phosphatidylinositol (3,4,5) trisphosphate can induce actin assembly even in the absence of GTPγS. RhoGDI, a guanine-nucleotide dissociation inhibitor for the Rho family, inhibits phosphoinositide-induced actin assembly, suggesting the involvement of the Rho family small G Proteins. Using various dominant mutants of these G Proteins, we demonstrate the requirement of Cdc42 for phosphoinositide-induced actin assembly. Our results suggest that phosphoinositides may act to facilitate GTP exchange on Cdc42, as well as to anchor Cdc42 and actin nucleation activities. Hence, both phosphoinositides and Cdc42 are required to induce actin assembly in this cell-free system.
Kenneth D. Greis - One of the best experts on this subject based on the ideXlab platform.
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Ubiquitination of hnRNPA1 by TRAF6 links chronic innate immune signaling with myelodysplasia
Nature Immunology, 2017Co-Authors: Jing Fang, Kwangmin Choi, Xiaona Liu, Susanne Christie, Shailaja Akunuru, Rupali Kumar, Dehua Wang, Xiaoting Chen, Lyndsey C Bolanos, Kenneth D. GreisAbstract:Toll-like receptor (TLR) activation contributes to premalignant hematologic conditions, such as myelodysplastic syndromes (MDS). TRAF6, a TLR effector with ubiquitin (Ub) ligase activity, is overexpressed in MDS hematopoietic stem/progenitor cells (HSPCs). We found that TRAF6 overexpression in mouse HSPC results in impaired hematopoiesis and bone marrow failure. Using a global Ub screen, we identified hnRNPA1, an RNA-binding Protein and auxiliary splicing factor, as a substrate of TRAF6. TRAF6 ubiquitination of hnRNPA1 regulated alternative splicing of Arhgap1 , which resulted in activation of the GTP-binding Rho family Protein Cdc42 and accounted for hematopoietic defects in TRAF6-expressing HSPCs. These results implicate Ub signaling in coordinating RNA processing by TLR pathways during an immune response and in premalignant hematologic diseases, such as MDS. Starczynowski and colleagues show that overexpression of TRAF6 in HSCs induces ubiquitination of the RNA-binding Protein hnRNPA1 and alternative splicing of Arhgap1, which accounts for the hematopoietic defects in myelodysplastic syndromes.
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Ubiquitination of hnRNPA1 by TRAF6 links chronic innate immune signaling with myelodysplasia
Nature immunology, 2016Co-Authors: Jing Fang, Lyndsey Bolanos, Kwangmin Choi, Xiaona Liu, Susanne Christie, Shailaja Akunuru, Rupali Kumar, Dehua Wang, Xiaoting Chen, Kenneth D. GreisAbstract:Toll-like receptor (TLR) activation contributes to premalignant hematologic conditions, such as myelodysplastic syndromes (MDS). TRAF6, a TLR effector with ubiquitin (Ub) ligase activity, is overexpressed in MDS hematopoietic stem/progenitor cells (HSPCs). We found that TRAF6 overexpression in mouse HSPC results in impaired hematopoiesis and bone marrow failure. Using a global Ub screen, we identified hnRNPA1, an RNA-binding Protein and auxiliary splicing factor, as a substrate of TRAF6. TRAF6 ubiquitination of hnRNPA1 regulated alternative splicing of Arhgap1, which resulted in activation of the GTP-binding Rho family Protein Cdc42 and accounted for hematopoietic defects in TRAF6-expressing HSPCs. These results implicate Ub signaling in coordinating RNA processing by TLR pathways during an immune response and in premalignant hematologic diseases, such as MDS.
