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Li Z, Liu Q, Cai Y, Ye N, He Z, Yao Y, Ding Y, Wang P, Qi C, Zheng L, Wang L, Zhou J, Zhang QQ. EPAC inhibitor suppresses angiogenesis and tumor growth of triple-negative breast cancer. Biochim Biophys Acta Mol Basis Dis 2024; 1870:167114. [PMID: 38447883 DOI: 10.1016/j.bbadis.2024.167114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 02/29/2024] [Accepted: 03/01/2024] [Indexed: 03/08/2024]
Abstract
AIMS Exchange protein directly activated by cAMP 1 (EPAC1), a major isoform of guanine nucleotide exchange factors, is highly expressed in vascular endothelia cells and regulates angiogenesis in the retina. High intratumor microvascular densities (MVD) resulting from angiogenesis is responsible for breast cancer development. Downregulation of EPAC1 in tumor cell reduces triple-negative breast cancer (TNBC)-induced angiogenesis. However, whether Epac1 expressed in vascular endothelial cells contributes to angiogenesis and tumor development of TNBC remains elusive. MAIN METHODS We employed NY0123, a previously identified potent EPAC inhibitor, to explore the anti-angiogenic biological role of EPAC1 in vitro and in vivo through vascular endothelial cells, rat aortic ring, Matrigel plug, and chick embryo chorioallantoic membrane (CAM) and yolk sac membrane (YSM) assays, as well as the in vivo xenograft tumor models of TNBC in both chick embryo and mice. KEY FINDINGS Inhibiting EPAC1 in vascular endothelial cells by NY0123 significantly suppresses angiogenesis and tumor growth of TNBC. In addition, NY0123 possesses a better inhibitory efficacy than ESI-09, a reported specific EPAC inhibitor tool compound. Importantly, inhibiting EPAC1 in vascular endothelia cells regulates the typical angiogenic signaling network, which is associated with not only vascular endothelial growth factor (VEGF)/vascular endothelial growth factor receptor-2 (VEGFR2) signaling, but also PI3K/AKT, MEK/ERK and Notch pathway. CONCLUSIONS Our findings support that EPAC1 may serve as an effective anti-angiogenic therapeutic target of TNBC, and EPAC inhibitor NY0123 has the therapeutic potential to be developed for the treatment of TNBC.
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Affiliation(s)
- Zishuo Li
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Qiao Liu
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Yuhao Cai
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Na Ye
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, United States
| | - Zinan He
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Yuying Yao
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Yi Ding
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Pingyuan Wang
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, United States
| | - Cuiling Qi
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Lingyun Zheng
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Lijing Wang
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Jia Zhou
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, United States.
| | - Qian-Qian Zhang
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China.
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Zhao YY, Zhang LJ, Liang XY, Zhang XC, Chang JR, Shi M, Liu H, Zhou Y, Sun Z, Zhao YF. Pyruvate Upregulates Hepatic FGF21 Expression by Activating PDE and Inhibiting cAMP–Epac–CREB Signaling Pathway. Int J Mol Sci 2022; 23:ijms23105490. [PMID: 35628302 PMCID: PMC9141208 DOI: 10.3390/ijms23105490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 05/12/2022] [Accepted: 05/13/2022] [Indexed: 02/01/2023] Open
Abstract
Fibroblast growth factor 21 (FGF21) functions as a polypeptide hormone to regulate glucose and lipid metabolism, and its expression is regulated by cellular metabolic stress. Pyruvate is an important intermediate metabolite that acts as a key hub for cellular fuel metabolism. However, the effect of pyruvate on hepatic FGF21 expression and secretion remains unknown. Herein, we examined the gene expression and protein levels of FGF21 in human hepatoma HepG2 cells and mouse AML12 hepatocytes in vitro, as well as in mice in vivo. In HepG2 and AML12 cells, pyruvate at concentrations above 0.1 mM significantly increased FGF21 expression and secretion. The increase in cellular cAMP levels by adenylyl cyclase activation, phosphodiesterase (PDE) inhibition and 8-Bromo-cAMP administration significantly restrained pyruvate-stimulated FGF21 expression. Pyruvate significantly increased PDE activities, reduced cAMP levels and decreased CREB phosphorylation. The inhibition of exchange protein directed activated by cAMP (Epac) and cAMP response element binding protein (CREB) upregulated FGF21 expression, upon which pyruvate no longer increased FGF21 expression. The increase in plasma pyruvate levels in mice induced by the intraperitoneal injection of pyruvate significantly increased FGF21 gene expression and PDE activity with a reduction in cAMP levels and CREB phosphorylation in the mouse liver compared with the control. In conclusion, pyruvate activates PDEs to reduce cAMP and then inhibits the cAMP–Epac–CREB signaling pathway to upregulate FGF21 expression in hepatocytes.
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Li X, Lu W, Zhou T, Zhao F, Yang L. Timosaponin AIII Suppresses RAP1 Signaling Pathway to Enhance the Inhibitory Effect of Paclitaxel on Nasopharyngeal Carcinoma. Comput Math Methods Med 2022; 2022:6756676. [PMID: 35586672 PMCID: PMC9110172 DOI: 10.1155/2022/6756676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 04/14/2022] [Accepted: 04/22/2022] [Indexed: 11/30/2022]
Abstract
Although PTX has been identified as an effective drug for nasopharyngeal carcinoma (NPC) therapy, it has serious side effects in the human body. Previous studies have shown that timosaponin AIII (TSAIII) can inhibit the malignant progression of NPC cells. This study investigated the active mechanism of the combination of TSAIII and paclitaxel (PTX) on NPC. Cellular viability, apoptosis, apoptotic factors, and RAP1 signaling regulators were detected in the PNC cells (CNE-1 and HNE-2) and the subcutaneous CNE-1 transplanted nude mice treated with PTX or/and TSAIII. The results showed that TSAIII notably strengthened the inhibitory effect of PTX on the proliferation of NPC cells CNE-1 and HNE-2; upregulated the expression of Bax B-cell lymphoma 2 (Bcl-2)/Bcl-xL-associated death promoter (Bad), and Ras-associated protein1 (RAP1) GTPase activating protein (Rap1GAP); inhibited the level of Bcl-2, RAP1, and Ras guanine nucleotide releasing protein (RasGRP2); and significantly enhanced the promoting effect of PTX on apoptosis in the CNE-1 and HNE-2 cells. Besides, TSAIII strengthened the inhibitory effect of PTX on xenograft tumor in nude mice without adverse reactions. In conclusion, the combination administration of TSAIII and PTX had a significantly therapeutic effect on NPC and avoided the PTX's side effects, which may have acted as a new direction for the study of therapeutic approaches for NPC clinically.
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Affiliation(s)
- Xiaofeng Li
- Department of Otorhinolarynology, Head and Neck Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Wen Lu
- Department of Otorhinolarynology, Head and Neck Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Tianjiao Zhou
- Department of Otorhinolarynology, Head and Neck Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Feng Zhao
- Department of Otorhinolarynology, Head and Neck Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Li Yang
- Department of Head and Neck Surgery, People's Hospital of Guang'an City, Guang'an 638001, China
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Li W, Qin C, Yan J, Zhao Q, You L, Yang Y. Propofol Alleviates Neuropathic Pain Induced by Chronic Contractile Injury by Regulating the Spinal glun2b-p38mapkepac1 Pathway. Comput Math Methods Med 2021; 2021:9305076. [PMID: 34804196 PMCID: PMC8601802 DOI: 10.1155/2021/9305076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Accepted: 10/15/2021] [Indexed: 11/25/2022]
Abstract
BACKGROUND Propofol acts as an intravenous anesthetic cure which is widely used as a therapy for the craniocerebral injury that comprised surgical anesthesia as well as the sedation done in the intensive care units. Propofol is one of the most commonly used and efficient anesthetics where the painful effects are followed by an injection of propofol. In many cases, patients experience pain followed by anxiety, boredom, fear, and even myocardial ischemia. OBJECTIVE This study was performed to investigate the underlying mechanism of propofol and its effect on regulating spinal glun2b-p38mapkepac1 pathways in chronic contractile injury. Material and Methods. Contractile injury was performed by ligation around the nerve of the thigh region postanesthesia. Rats were divided into three groups to analyze the changes like mechanical allodynia by the paw withdrawal threshold and histopathological analysis for assessing cellular degradation. L4-L6 from the spinal dorsal horns were isolated and harvested for studying protein expression, by the method of western blotting and immunofluorescence analysis. RESULTS The pain caused due to mechanical allodynia in the paw region was highest at 1 hour postinduction and lasted for three days postinjury. Pain was significantly less in the group receiving propofol when compared with the isoflurane group for the first two hours of injury. In the propofol group, EPAC1, GluN2B, and p38 MAP K were significantly lower. CONCLUSION In the rat model of induced chronic contractile injury, postsurgery there was a suppression of the GluN2B-p38MAPK/EPAC1 signaling pathway in the propofol group. As the p38MAPK/EPAC pathway has a significant role in the postoperative hyperalgesia, thus our experiment suggests that propofol has analgesic effects.
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Affiliation(s)
- Wen Li
- Department of Anesthesiology, Guizhou Provincial People's Hospital, Guizhou, China
| | - Chenguang Qin
- Department of Anesthesiology, Guizhou Provincial People's Hospital, Guizhou, China
| | - JianYong Yan
- Department of Anesthesiology, Guizhou Provincial People's Hospital, Guizhou, China
| | - Qian Zhao
- Department of Anesthesiology, Guizhou Provincial People's Hospital, Guizhou, China
| | - Lu You
- Department of Anesthesiology, Guizhou Provincial People's Hospital, Guizhou, China
| | - Ye Yang
- Department of Anesthesiology, Guizhou Provincial Orthopaedic Hospital, Guizhou, China
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Vélez EJ, Nasri A, Unniappan S. Nesfatin-1 and Nesfatin-1-like peptide suppress basal and TRH-Induced expression of prolactin and prolactin regulatory element-binding protein mRNAs in rat GH3 somatolactotrophs. Mol Cell Endocrinol 2021; 529:111269. [PMID: 33819522 DOI: 10.1016/j.mce.2021.111269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 03/20/2021] [Accepted: 03/29/2021] [Indexed: 11/23/2022]
Abstract
Prolactin (PRL), mainly synthesized and secreted by the lactotrophs and somatolactotrophs of the anterior pituitary, is a pleiotropic hormone that regulates lactation. In the last decade, nesfatin-1 (NESF) and NESF-like peptide (NLP), encoded in nucleobindin 1 and 2 (NUCB1 and NUCB2), respectively, were characterized as metabolic factors with a potential role in the control of pituitary hormones. We hypothesized that NUCBs and their encoded peptides (NESF and NLP) suppress PRL transcription in the pituitary. The main objective of this research was to determine whether exogenous NESF and NLP, and/or endogenous NUCB1 and NUCB2 regulate the expression of prl and preb mRNAs. Using immortalized rat somatolactotrophs (GH3 cells), dose-response studies were performed to test whether NESF and NLP affect prl and preb. Moreover, the ability of these peptides to modulate the effects of the PRL stimulator thyrotropin releasing hormone (TRH) was studied. Besides, the effects of siRNA-mediated knockdown of endogenous NUCBs on prl and preb mRNAs were determined. NESF and NLP reduced the transcription of prl and preb in GH3 cells. Both NESF and NLP also prevented the stimulatory effects of TRH prl and preb expression. The knockdown of endogenous NUCB1 attenuates both basal prl and TRH-induced expression of prl and preb, while the silencing of NUCBs did not affect the actions of exogenous NESF or NLP. Overall, this work reveals that NUCBs and encoded-peptides are novel regulators of PRL. Future research should test whether the effects observed here in GH3 cells are preserved both in vivo and at the post-transcriptional level.
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Affiliation(s)
- Emilio J Vélez
- Laboratory of Integrative Neuroendocrinology, Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada
| | - Atefeh Nasri
- Laboratory of Integrative Neuroendocrinology, Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada
| | - Suraj Unniappan
- Laboratory of Integrative Neuroendocrinology, Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada.
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Xu X, Su Y, Wu K, Pan F, Wang A. DOCK2 contributes to endotoxemia-induced acute lung injury in mice by activating proinflammatory macrophages. Biochem Pharmacol 2021; 184:114399. [PMID: 33382969 DOI: 10.1016/j.bcp.2020.114399] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 12/23/2020] [Accepted: 12/24/2020] [Indexed: 12/12/2022]
Abstract
Dedicator of cytokinesis 2 (DOCK2), an atypical Rac activator, has important anti-inflammatory properties in blepharitis, enteric bacterial infection and colitis. However, the roles of DOCK2 in macrophage activation and acute lung injury (ALI) are still poorly elucidated. In vitro studies demonstrated that DOCK2 was essential for the nucleotide-sensing Toll-like receptor (TLR) 4-mediated inflammatory response in macrophages. We also confirmed that exposure of macrophages to LPS induced Rac activation through a TLR4-independent, DOCK2-dependent mechanism. Phosphorylation of IκB kinase (IKK) β and nuclear translocation of transcription factor nuclear factor kappa B (NF-κB) were impaired in Ad-shDOCK2-expressing macrophages, resulting in a decreased inflammatory response. Similar results were obtained when EHop-016 (a Rac inhibitor) was used to treat uninfected macrophages. In summary, these data indicate that the DOCK2-Rac signaling pathway acts in parallel with TLR4 engagement to control IKKβ activation for inflammatory cytokine release. Next, we investigated whether pharmacological inhibition of DOCK2 protects against endotoxemia-induced lung injury in mice. Treatment with 4-[3'-(2″-chlorophenyl)-2'-propen-1'-ylidene]-1-phenyl-3,5-pyrazolidinedione (CPYPP), a small-molecule inhibitor of DOCK2, reduced the severity of lung injury, as indicated by decreases in the lung injury score and myeloperoxidase (MPO) activity. Moreover, CPYPP attenuated LPS-induced proinflammatory cytokine release in mice. Our studies suggest that inhibition of DOCK2 may suppress LPS-induced macrophage activation and that DOCK2 may be a novel target for treating endotoxemia-related ALI.
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Affiliation(s)
- Xiaotao Xu
- Department of Anesthesiology, Affiliated Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai 200233, China
| | - Yang Su
- Department of Anesthesiology, Kaifeng People's Hospital, Kaifeng 475000, China
| | - Kaixuan Wu
- Department of Anesthesiology, Affiliated Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai 200233, China
| | - Fan Pan
- Department of Anesthesiology, Affiliated Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai 200233, China
| | - Aizhong Wang
- Department of Anesthesiology, Affiliated Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai 200233, China.
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Qi L, Zhang Y, Song F, Han Y, Ding Y. A newly identified small molecular compound acts as a protein kinase inhibitor to suppress metastasis of colorectal cancer. Bioorg Chem 2021; 107:104625. [PMID: 33454506 DOI: 10.1016/j.bioorg.2021.104625] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 12/28/2020] [Accepted: 12/31/2020] [Indexed: 01/02/2023]
Abstract
BACKGROUND Targeted therapy has demonstrated high efficacy in the treatment of advanced cancer, and protein kinase inhibitors are a major focus of that therapy; therefore, our study aimed to identify a new protein kinase inhibitor that could be used in the treatment of advanced cancers. METHODS We analyzed the expression profile of colorectal cancer (CRC), combined the driver gene and drug target databases, and identified protein kinase kalirin RhoGEF kinase (kalirin/KALRN) which is related to CRC metastasis. Based on the structure of kalirin, we screened for the small molecular compound ZINC65387069. We first compared the kinase inhibitory activities and molecular properties of ZINC65387069 and tyrosine kinase inhibitors (TKIs). We then determined the effects of ZINC65387069 on the phosphorylation of protein kinase B-Raf. Finally, we determined the effects of ZINC65387069 on migration and apoptosis of HCT116 cells as well as RKO cells. The cell cytoskeleton was also determined. RESULTS Compared with traditional TKIs, ZINC65387069 had stronger kinase inhibitory activity, a simpler structure, higher water solubility, a smaller polar surface area, and lower molecular weight and volume. In CRC cells, ZINC65387069 could significantly inhibit the phosphorylation of B-Raf as well as inhibit cell migration, destroy the cell cytoskeleton, and promote cell apoptosis. CONCLUSION ZINC65387069 is a newly identified protein kinase inhibitor that deserves additional research as a lead compound for drug development to help create targeted therapy against CRC.
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Affiliation(s)
- Lu Qi
- Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China; Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China; Guangdong Provincial Key Laboratory of Molecular Oncologic Pathology, Guangzhou 510515, China.
| | - Ying Zhang
- Department of Radiation Medicine, School of Public Health, Southern Medical University, Guangzhou 510515, China; Guangdong Provincial Key Laboratory of Tropical Disease Research, Guangzhou 510515, China
| | - Fuyao Song
- Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China; Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China; Guangdong Provincial Key Laboratory of Molecular Oncologic Pathology, Guangzhou 510515, China
| | - Yue Han
- Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China; Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China; Guangdong Provincial Key Laboratory of Molecular Oncologic Pathology, Guangzhou 510515, China
| | - Yanqing Ding
- Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China; Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China; Guangdong Provincial Key Laboratory of Molecular Oncologic Pathology, Guangzhou 510515, China.
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8
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Maziarz M, Park JC, Leyme A, Marivin A, Garcia-Lopez A, Patel PP, Garcia-Marcos M. Revealing the Activity of Trimeric G-proteins in Live Cells with a Versatile Biosensor Design. Cell 2020; 182:770-785.e16. [PMID: 32634377 DOI: 10.1016/j.cell.2020.06.020] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 04/21/2020] [Accepted: 06/08/2020] [Indexed: 12/28/2022]
Abstract
Heterotrimeric G-proteins (Gαβγ) are the main transducers of signals from GPCRs, mediating the action of countless natural stimuli and therapeutic agents. However, there are currently no robust approaches to directly measure the activity of endogenous G-proteins in cells. Here, we describe a suite of optical biosensors that detect endogenous active G-proteins with sub-second resolution in live cells. Using a modular design principle, we developed genetically encoded, unimolecular biosensors for endogenous Gα-GTP and free Gβγ: the two active species of heterotrimeric G-proteins. This design was leveraged to generate biosensors with specificity for different heterotrimeric G-proteins or for other G-proteins, such as Rho GTPases. Versatility was further validated by implementing the biosensors in multiple contexts, from characterizing cancer-associated G-protein mutants to neurotransmitter signaling in primary neurons. Overall, the versatile biosensor design introduced here enables studying the activity of endogenous G-proteins in live cells with high fidelity, temporal resolution, and convenience.
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Affiliation(s)
- Marcin Maziarz
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Jong-Chan Park
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Anthony Leyme
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Arthur Marivin
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Alberto Garcia-Lopez
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Prachi P Patel
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Mikel Garcia-Marcos
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA.
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Ahmed A, Boulton S, Shao H, Akimoto M, Natarajan A, Cheng X, Melacini G. Recent Advances in EPAC-Targeted Therapies: A Biophysical Perspective. Cells 2019; 8:cells8111462. [PMID: 31752286 PMCID: PMC6912387 DOI: 10.3390/cells8111462] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 11/12/2019] [Accepted: 11/13/2019] [Indexed: 02/07/2023] Open
Abstract
The universal second messenger cAMP regulates diverse intracellular processes by interacting with ubiquitously expressed proteins, such as Protein Kinase A (PKA) and the Exchange Protein directly Activated by cAMP (EPAC). EPAC is implicated in multiple pathologies, thus several EPAC-specific inhibitors have been identified in recent years. However, the mechanisms and molecular interactions underlying the EPAC inhibition elicited by such compounds are still poorly understood. Additionally, being hydrophobic low molecular weight species, EPAC-specific inhibitors are prone to forming colloidal aggregates, which result in non-specific aggregation-based inhibition (ABI) in aqueous systems. Here, we review from a biophysical perspective the molecular basis of the specific and non-specific interactions of two EPAC antagonists—CE3F4R, a non-competitive inhibitor, and ESI-09, a competitive inhibitor of EPAC. Additionally, we discuss the value of common ABI attenuators (e.g., TX and HSA) to reduce false positives at the expense of introducing false negatives when screening aggregation-prone compounds. We hope this review provides the EPAC community effective criteria to evaluate similar compounds, aiding in the optimization of existing drug leads, and informing the development of the next generation of EPAC-specific inhibitors.
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Affiliation(s)
- Alveena Ahmed
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada; (A.A.); (S.B.)
| | - Stephen Boulton
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada; (A.A.); (S.B.)
| | - Hongzhao Shao
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON L8S 4L8, Canada; (H.S.); (M.A.)
| | - Madoka Akimoto
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON L8S 4L8, Canada; (H.S.); (M.A.)
| | - Amarnath Natarajan
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA;
| | - Xiaodong Cheng
- Department of Integrative Biology & Pharmacology, University of Texas Health Science Center at Houston, Houston, TX 77030, USA;
- Texas Therapeutics Institute, Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Giuseppe Melacini
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada; (A.A.); (S.B.)
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON L8S 4L8, Canada; (H.S.); (M.A.)
- Correspondence:
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Wang Q, Zhao C, Jin L, Zhang H, Miao Q, Liu H, Zhang D. AWRK6, a Novel GLP-1 Receptor Agonist, Attenuates Diabetes by Stimulating Insulin Secretion. Int J Mol Sci 2018; 19:ijms19103053. [PMID: 30301245 PMCID: PMC6213269 DOI: 10.3390/ijms19103053] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 09/30/2018] [Accepted: 10/03/2018] [Indexed: 12/12/2022] Open
Abstract
Diabetes is a metabolic disorder leading to many complications. The treatment of diabetes mainly depends on hypoglycemic drugs, often with side effects, which drive us to develop novel agents. AWRK6 was a peptide developed from the antimicrobial peptide Dybowskin-2CDYa in our previous study, and the availability of AWRK6 on diabetes intervention was unknown. Here, in vivo and in vitro experiments were carried out to investigate the effects of AWRK6 against diabetes. In diabetic mice, induced by high-fat diet followed by streptozocin (STZ) administration, the daily administration of AWRK6 presented acute and sustained hypoglycemic effects. The plasma insulin was significantly elevated by AWRK6 during an oral glucose tolerance test (OGTT). The relative β cell mass in diabetic mice was increased by AWRK6 treatment. The body weight and food intake were remarkably reduced by AWRK6 administration. In the mouse pancreatic β cell line Min6 cells, the intracellular calcium concentration was found to be enhanced under the treatment with AWRK6, and protein kinase A (PKA) inhibitor H-89 and Epac2 inhibitor HJC0350 represented inhibitory effects of the insulinotropic function of AWRK6. By FITC-AWRK6 incubation and GLP-1 receptor (GLP-1R) knockdown, AWRK6 proved to be a novel GLP-1R agonist. In addition, AWRK6 showed no toxicity in cell viability and membrane integrity in Min6 cells, and no hypoglycemia risk and no lethal toxicity in mice. In summary, AWRK6 was found as a novel agonist of GLP-1R, which could stimulate insulin secretion to regulate blood glucose and energy metabolism, via cAMP-calcium signaling pathway, without significant toxicity. The peptide AWRK6 might become a novel candidate for diabetes treatment.
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Affiliation(s)
- Qiuyu Wang
- School of Life Science, Liaoning University, Shenyang 110036, China.
| | - Chunlin Zhao
- School of Life Science, Liaoning University, Shenyang 110036, China.
| | - Lili Jin
- School of Life Science, Liaoning University, Shenyang 110036, China.
| | - Hanyu Zhang
- School of Life Science, Liaoning University, Shenyang 110036, China.
| | - Qifan Miao
- School of Life Science, Liaoning University, Shenyang 110036, China.
| | - Hongsheng Liu
- Research Center for Computer Simulating and Information Processing of Bio-macromolecules of Liaoning Province, Liaoning University, Shenyang 110036, China.
| | - Dianbao Zhang
- Department of Stem Cells and Regenerative Medicine, Key Laboratory of Cell Biology, National Health Commission of China, and Key Laboratory of Medical Cell Biology, Ministry of Education of China, China Medical University, Shenyang 110122, China.
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Mishev K, Lu Q, Denoo B, Peurois F, Dejonghe W, Hullaert J, De Rycke R, Boeren S, Bretou M, De Munck S, Sharma I, Goodman K, Kalinowska K, Storme V, Nguyen LSL, Drozdzecki A, Martins S, Nerinckx W, Audenaert D, Vert G, Madder A, Otegui MS, Isono E, Savvides SN, Annaert W, De Vries S, Cherfils J, Winne J, Russinova E. Nonselective Chemical Inhibition of Sec7 Domain-Containing ARF GTPase Exchange Factors. Plant Cell 2018; 30:2573-2593. [PMID: 30018157 PMCID: PMC6241273 DOI: 10.1105/tpc.18.00145] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 06/25/2018] [Accepted: 07/17/2018] [Indexed: 05/12/2023]
Abstract
Small GTP-binding proteins from the ADP-ribosylation factor (ARF) family are important regulators of vesicle formation and cellular trafficking in all eukaryotes. ARF activation is accomplished by a protein family of guanine nucleotide exchange factors (GEFs) that contain a conserved catalytic Sec7 domain. Here, we identified and characterized Secdin, a small-molecule inhibitor of Arabidopsis thaliana ARF-GEFs. Secdin application caused aberrant retention of plasma membrane (PM) proteins in late endosomal compartments, enhanced vacuolar degradation, impaired protein recycling, and delayed secretion and endocytosis. Combined treatments with Secdin and the known ARF-GEF inhibitor Brefeldin A (BFA) prevented the BFA-induced PM stabilization of the ARF-GEF GNOM, impaired its translocation from the Golgi to the trans-Golgi network/early endosomes, and led to the formation of hybrid endomembrane compartments reminiscent of those in ARF-GEF-deficient mutants. Drug affinity-responsive target stability assays revealed that Secdin, unlike BFA, targeted all examined Arabidopsis ARF-GEFs, but that the interaction was probably not mediated by the Sec7 domain because Secdin did not interfere with the Sec7 domain-mediated ARF activation. These results show that Secdin and BFA affect their protein targets through distinct mechanisms, in turn showing the usefulness of Secdin in studies in which ARF-GEF-dependent endomembrane transport cannot be manipulated with BFA.
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Affiliation(s)
- Kiril Mishev
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
- Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium
- Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Qing Lu
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
- Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium
| | - Bram Denoo
- Department of Organic and Macromolecular Chemistry, Ghent University, 9000 Ghent, Belgium
| | - François Peurois
- Laboratoire de Biologie et Pharmacologie Appliquée, Centre National de la Recherche Scientifique, Ecole Normale Supérieure Paris-Saclay, 94235 Cachan, France
| | - Wim Dejonghe
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
- Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium
| | - Jan Hullaert
- Department of Organic and Macromolecular Chemistry, Ghent University, 9000 Ghent, Belgium
| | - Riet De Rycke
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
- Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium
- VIB BioImaging Core, 9052 Ghent, Belgium
| | - Sjef Boeren
- Laboratory of Biochemistry, Wageningen University, 6708 Wageningen, The Netherlands
| | - Marine Bretou
- Laboratory for Membrane Trafficking, VIB Center for Brain and Disease Research, KU Leuven, Department of Neurosciences, 3000 Leuven, Belgium
| | - Steven De Munck
- Laboratory for Protein Biochemistry and Biomolecular Engineering, Department of Biochemistry and Microbiology, Ghent University, 9000 Ghent, Belgium
- Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Isha Sharma
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
- Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium
| | - Kaija Goodman
- Laboratory of Cell and Molecular Biology and Departments of Botany and Genetics, University of Wisconsin-Madison, Wisconsin 53706
| | - Kamila Kalinowska
- School of Life Sciences Weihenstephan, Technical University of Munich, 85354 Freising, Germany
| | - Veronique Storme
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
- Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium
| | - Le Son Long Nguyen
- VIB Screening Core, 9052 Ghent, Belgium
- Expertise Centre for Bioassay Development and Screening (C-BIOS), Ghent University, 9052 Ghent, Belgium
| | - Andrzej Drozdzecki
- VIB Screening Core, 9052 Ghent, Belgium
- Expertise Centre for Bioassay Development and Screening (C-BIOS), Ghent University, 9052 Ghent, Belgium
| | - Sara Martins
- Institute for Integrative Biology of the Cell (I2BC), CNRS/CEA/Université Paris Sud, Université Paris-Saclay, Gif-sur-Yvette 91198, France
| | - Wim Nerinckx
- Laboratory for Protein Biochemistry and Biomolecular Engineering, Department of Biochemistry and Microbiology, Ghent University, 9000 Ghent, Belgium
- Center for Medical Biotechnology, VIB, 9052 Ghent, Belgium
| | - Dominique Audenaert
- VIB Screening Core, 9052 Ghent, Belgium
- Expertise Centre for Bioassay Development and Screening (C-BIOS), Ghent University, 9052 Ghent, Belgium
| | - Grégory Vert
- Institute for Integrative Biology of the Cell (I2BC), CNRS/CEA/Université Paris Sud, Université Paris-Saclay, Gif-sur-Yvette 91198, France
| | - Annemieke Madder
- Department of Organic and Macromolecular Chemistry, Ghent University, 9000 Ghent, Belgium
| | - Marisa S Otegui
- Laboratory of Cell and Molecular Biology and Departments of Botany and Genetics, University of Wisconsin-Madison, Wisconsin 53706
| | - Erika Isono
- School of Life Sciences Weihenstephan, Technical University of Munich, 85354 Freising, Germany
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Savvas N Savvides
- Laboratory for Protein Biochemistry and Biomolecular Engineering, Department of Biochemistry and Microbiology, Ghent University, 9000 Ghent, Belgium
- Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Wim Annaert
- Laboratory for Membrane Trafficking, VIB Center for Brain and Disease Research, KU Leuven, Department of Neurosciences, 3000 Leuven, Belgium
| | - Sacco De Vries
- Laboratory of Biochemistry, Wageningen University, 6708 Wageningen, The Netherlands
| | - Jacqueline Cherfils
- Laboratoire de Biologie et Pharmacologie Appliquée, Centre National de la Recherche Scientifique, Ecole Normale Supérieure Paris-Saclay, 94235 Cachan, France
| | - Johan Winne
- Department of Organic and Macromolecular Chemistry, Ghent University, 9000 Ghent, Belgium
| | - Eugenia Russinova
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
- Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium
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12
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Hamilton A, Zhang Q, Salehi A, Willems M, Knudsen JG, Ringgaard AK, Chapman CE, Gonzalez-Alvarez A, Surdo NC, Zaccolo M, Basco D, Johnson PRV, Ramracheya R, Rutter GA, Galione A, Rorsman P, Tarasov AI. Adrenaline Stimulates Glucagon Secretion by Tpc2-Dependent Ca 2+ Mobilization From Acidic Stores in Pancreatic α-Cells. Diabetes 2018; 67:1128-1139. [PMID: 29563152 PMCID: PMC6258900 DOI: 10.2337/db17-1102] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 03/14/2018] [Indexed: 12/25/2022]
Abstract
Adrenaline is a powerful stimulus of glucagon secretion. It acts by activation of β-adrenergic receptors, but the downstream mechanisms have only been partially elucidated. Here, we have examined the effects of adrenaline in mouse and human α-cells by a combination of electrophysiology, imaging of Ca2+ and PKA activity, and hormone release measurements. We found that stimulation of glucagon secretion correlated with a PKA- and EPAC2-dependent (inhibited by PKI and ESI-05, respectively) elevation of [Ca2+]i in α-cells, which occurred without stimulation of electrical activity and persisted in the absence of extracellular Ca2+ but was sensitive to ryanodine, bafilomycin, and thapsigargin. Adrenaline also increased [Ca2+]i in α-cells in human islets. Genetic or pharmacological inhibition of the Tpc2 channel (that mediates Ca2+ release from acidic intracellular stores) abolished the stimulatory effect of adrenaline on glucagon secretion and reduced the elevation of [Ca2+]i Furthermore, in Tpc2-deficient islets, ryanodine exerted no additive inhibitory effect. These data suggest that β-adrenergic stimulation of glucagon secretion is controlled by a hierarchy of [Ca2+]i signaling in the α-cell that is initiated by cAMP-induced Tpc2-dependent Ca2+ release from the acidic stores and further amplified by Ca2+-induced Ca2+ release from the sarco/endoplasmic reticulum.
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Affiliation(s)
- Alexander Hamilton
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Headington, U.K
| | - Quan Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Headington, U.K
| | - Albert Salehi
- Institute of Neuroscience of Physiology, Department of Physiology, Metabolic Research Unit, University of Göteborg, Göteborg, Sweden
| | - Mara Willems
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Headington, U.K
| | - Jakob G Knudsen
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Headington, U.K
| | - Anna K Ringgaard
- Diabetes Research, Department of Stem Cell Biology, Novo Nordisk A/S, Måløv, Denmark
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Caroline E Chapman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Headington, U.K
| | - Alejandro Gonzalez-Alvarez
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Headington, U.K
| | - Nicoletta C Surdo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - Davide Basco
- Center for Integrative Genomics, Université de Lausanne, Lausanne, Switzerland
| | - Paul R V Johnson
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Headington, U.K
- Oxford National Institute for Health Research, Biomedical Research Centre, Oxford, U.K
| | - Reshma Ramracheya
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Headington, U.K
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Department of Medicine, Imperial College London, London, U.K
| | - Antony Galione
- Department of Pharmacology, University of Oxford, Oxford, U.K
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Headington, U.K.
- Institute of Neuroscience of Physiology, Department of Physiology, Metabolic Research Unit, University of Göteborg, Göteborg, Sweden
- Oxford National Institute for Health Research, Biomedical Research Centre, Oxford, U.K
| | - Andrei I Tarasov
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Headington, U.K.
- Oxford National Institute for Health Research, Biomedical Research Centre, Oxford, U.K
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13
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Iwatake M, Nishishita K, Okamoto K, Tsukuba T. The Rho-specific guanine nucleotide exchange factor Plekhg5 modulates cell polarity, adhesion, migration, and podosome organization in macrophages and osteoclasts. Exp Cell Res 2017; 359:415-430. [PMID: 28847484 DOI: 10.1016/j.yexcr.2017.08.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 08/06/2017] [Accepted: 08/17/2017] [Indexed: 12/28/2022]
Abstract
Osteoclasts are multinucleated bone-resorbing cells that are formed by fusion of monocyte/macrophage lineage. Osteoclasts and macrophages generate podosomes that are actin-based dynamic organelles implicated in cell adhesion, spreading, migration, and degradation. However, the detailed mechanisms of podosome organization remain unknown. Here, we identified the Rho-specific guanine-nucleotide exchange factor (Rho-GEF) Plekhg5 as an up-regulated gene during differentiation of osteoclasts from macrophages. Knockdown of Plekhg5 with small interfering RNA in both macrophages and osteoclasts induced larger cell formation with impaired cell polarity and resulted in an elongated and flattened shape. In macrophages, Plekhg5 depletion enhanced random migration, but impaired directional migration, adhesion, and matrix degradation. Plekhg5 in osteoclasts affected random migration, podosome organization, and bone resorption. Plekhg5 depletion affected signaling and localization of several Rho downstream effectors. In fact, end-binding protein 1 (EB1), cofilin and vinculin were abnormally localized in Plekhg5-depleted cells, and mDia1 and LIM kinase (LIMK)1 were upregulated in Plekhg5-depleted cells compared with control cells. However, overexpression of Plekhg5 in macrophages induced an increase in its mRNA level, but failed to increase the protein level, indicating that overexpressed Plekhg5 was degraded in macrophages but not HEK293T cells. Thus, Plekhg5 affects cell polarity, migration, adhesion, degradation, and podosome organization in macrophages and osteoclasts.
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Affiliation(s)
- Mayumi Iwatake
- Department of Dental Pharmacology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8588, Japan
| | - Kazuhisa Nishishita
- Department of Dental Pharmacology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8588, Japan
| | - Kuniaki Okamoto
- Department of Dental Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8558, Japan
| | - Takayuki Tsukuba
- Department of Dental Pharmacology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8588, Japan.
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14
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Wang X, Luo C, Cheng X, Lu M. Lithium and an EPAC-specific inhibitor ESI-09 synergistically suppress pancreatic cancer cell proliferation and survival. Acta Biochim Biophys Sin (Shanghai) 2017; 49:573-580. [PMID: 28475672 DOI: 10.1093/abbs/gmx045] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Indexed: 01/03/2023] Open
Abstract
Our previous studies showed that while lithium suppresses proliferation and induces apoptosis in pancreatic cancer cells, the inhibition of exchange proteins directly activated by cyclic adenosine monophosphate (cAMP) (EPAC)1 blocks pancreatic cancer cell migration and invasion. In this study, we further investigated the combinatory effects of lithium and EPAC-specific inhibitor (ESI)-09, an EPAC-specific inhibitor, on pancreatic cancer cell proliferation and viability, and explored whether lithium synergistically cooperates with EPAC inhibition in suppressing pancreatic cancer cell tumorigenicity. The cell viability of pancreatic cancer cell lines PANC-1 and MiaPaCa-2 was measured after 48 h of incubation with different dose combination of lithium and ESI-09. Flow cytometric analysis was carried out to further verify the impact of lithium and ESI-09 upon PANC-1 cell proliferation and apoptosis. To investigate the mechanism that the effects generated by lithium and ESI-09 on PANC-1 cells, the intracellular cAMP level was measured by an ELISA-based cAMP immunoassay. Our data showed that lithium and ESI-09 synergistically inhibit pancreatic cancer cell growth and survival. Furthermore, our results revealed a novel mechanism in which the synergism between lithium and ESI-09 is not mediated by the inhibitory effect of lithium toward GSK3β, but by lithium's ability to suppress cAMP/protein kinase A signaling.
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Affiliation(s)
- Xinshuo Wang
- State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing 210009, China
| | - Cheng Luo
- State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing 210009, China
| | - Xiaodong Cheng
- Department of Integrative Biology and Pharmacology, Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, TX, USA
| | - Meiling Lu
- State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing 210009, China
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15
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Wang P, Liu Z, Chen H, Ye N, Cheng X, Zhou J. Exchange proteins directly activated by cAMP (EPACs): Emerging therapeutic targets. Bioorg Med Chem Lett 2017; 27:1633-1639. [PMID: 28283242 PMCID: PMC5397994 DOI: 10.1016/j.bmcl.2017.02.065] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 02/07/2017] [Accepted: 02/26/2017] [Indexed: 11/22/2022]
Abstract
Exchange proteins directly activated by cAMP (EPACs) are critical cAMP-dependent signaling pathway mediators. The discovery of EPAC proteins has significantly facilitated understanding on cAMP-dependent signaling pathway and efforts along this line open new avenues for developing novel therapeutics for cancer, diabetes, heart failure, inflammation, infections, neurological disorders and other human diseases. Over the past decade, important progress has been made in the identification of EPAC agonists, antagonists and their biological and pharmacological applications. In this review, we briefly summarize recently reported novel functions of EPACs and the discovery of their small molecule modulators. The challenges and future perspectives are also discussed.
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Affiliation(s)
- Pingyuan Wang
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, United States
| | - Zhiqing Liu
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, United States
| | - Haiying Chen
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, United States
| | - Na Ye
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, United States
| | - Xiaodong Cheng
- Department of Integrative Biology and Pharmacology, Texas Therapeutics Institute, University of Texas Health Science Center, Houston, TX 77030, United States
| | - Jia Zhou
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, United States.
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16
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Yu X, Zhang Q, Zhao Y, Schwarz BJ, Stallone JN, Heaps CL, Han G. Activation of G protein-coupled estrogen receptor 1 induces coronary artery relaxation via Epac/Rap1-mediated inhibition of RhoA/Rho kinase pathway in parallel with PKA. PLoS One 2017; 12:e0173085. [PMID: 28278256 PMCID: PMC5344336 DOI: 10.1371/journal.pone.0173085] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 02/15/2017] [Indexed: 12/24/2022] Open
Abstract
Previously, we reported that cAMP/PKA signaling is involved in GPER-mediated coronary relaxation by activating MLCP via inhibition of RhoA pathway. In the current study, we tested the hypothesis that activation of GPER induces coronary artery relaxation via inhibition of RhoA/Rho kinase pathway by cAMP downstream targets, exchange proteins directly activated by cAMP (Epac) as well as PKA. Our results show that Epac inhibitors, brefeldin A (BFA, 50 μM), or ESI-09 (20 μM), or CE3F4 (100 μM), all partially inhibited porcine coronary artery relaxation response to the selective GPER agonist, G-1 (0.3–3 μM); while concurrent administration of BFA and PKI (5 μM), a PKA inhibitor, almost completely blocked the relaxation effect of G-1. The Epac specific agonist, 8-CPT-2Me-cAMP (007, 1–100 μM), induced a concentration-dependent relaxation response. Furthermore, the activity of Ras-related protein 1 (Rap1) was up regulated by G-1 (1 μM) treatment of porcine coronary artery smooth muscle cells (CASMCs). Phosphorylation of vasodilator-stimulated phosphoprotein (p-VASP) was elevated by G-1 (1 μM) treatment, but not by 007 (50 μM); and the effect of G-1 on p-VASP was blocked by PKI, but not by ESI-09, an Epac antagonist. RhoA activity was similarly down regulated by G-1 and 007, whereas ESI-09 restored most of the reduced RhoA activity by G-1 treatment. Furthermore, G-1 decreased PGF2α-induced p-MYPT1, which was partially reversed with either ESI-09 or PKI; whereas, concurrent administration of ESI-09 and PKI totally prevented the inhibitory effect of G-1. The inhibitory effects of G-1 on p- MLC levels in CASMCs were mostly restored by either ESI-09 or PKI. These results demonstrate that activation of GPER induces coronary artery relaxation via concurrent inhibition of RhoA/Rho kinase by Epac/Rap1 and PKA. GPER could be a potential drug target for preventing and treating cardiovascular diseases.
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Affiliation(s)
- Xuan Yu
- Department of Physiology and Pharmacology, Texas A&M University, College Station, TX, United States of America
| | - Qiao Zhang
- Department of Physiology and Pharmacology, Texas A&M University, College Station, TX, United States of America
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yan Zhao
- Department of Physiology and Pharmacology, Texas A&M University, College Station, TX, United States of America
- Department of Cardiovascular Medicine, First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China
| | - Benjamin J. Schwarz
- Department of Physiology and Pharmacology, Texas A&M University, College Station, TX, United States of America
| | - John N. Stallone
- Department of Physiology and Pharmacology, Texas A&M University, College Station, TX, United States of America
- Women's Health Division, Michael E. DeBakey Institute, Texas A&M University, College Station, TX, United States of America
| | - Cristine L. Heaps
- Department of Physiology and Pharmacology, Texas A&M University, College Station, TX, United States of America
| | - Guichun Han
- Department of Physiology and Pharmacology, Texas A&M University, College Station, TX, United States of America
- Women's Health Division, Michael E. DeBakey Institute, Texas A&M University, College Station, TX, United States of America
- * E-mail:
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17
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Takenaka N, Nihata Y, Satoh T. Rac1 Activation Caused by Membrane Translocation of a Guanine Nucleotide Exchange Factor in Akt2-Mediated Insulin Signaling in Mouse Skeletal Muscle. PLoS One 2016; 11:e0155292. [PMID: 27163697 PMCID: PMC4862641 DOI: 10.1371/journal.pone.0155292] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 04/27/2016] [Indexed: 11/25/2022] Open
Abstract
Insulin-stimulated glucose uptake in skeletal muscle is mediated by the glucose transporter GLUT4, which is translocated to the plasma membrane following insulin stimulation. Several lines of evidence suggested that the protein kinase Akt2 plays a key role in this insulin action. The small GTPase Rac1 has also been implicated as a regulator of insulin-stimulated GLUT4 translocation, acting downstream of Akt2. However, the mechanisms whereby Akt2 regulates Rac1 activity remain obscure. The guanine nucleotide exchange factor FLJ00068 has been identified as a direct regulator of Rac1 in Akt2-mediated signaling, but its characterization was performed mostly in cultured myoblasts. Here, we provide in vivo evidence that FLJ00068 indeed acts downstream of Akt2 as a Rac1 regulator by using mouse skeletal muscle. Small interfering RNA knockdown of FLJ00068 markedly diminished GLUT4 translocation to the sarcolemma following insulin administration or ectopic expression of a constitutively activated mutant of either phosphoinositide 3-kinase or Akt2. Additionally, insulin and these constitutively activated mutants caused the activation of Rac1 as shown by immunofluorescent microscopy using a polypeptide probe specific to activated Rac1 in isolated gastrocnemius muscle fibers and frozen sections of gastrocnemius muscle. This Rac1 activation was also abrogated by FLJ00068 knockdown. Furthermore, we observed translocation of FLJ00068 to the cell periphery following insulin stimulation in cultured myoblasts. Localization of FLJ00068 in the plasma membrane in insulin-stimulated, but not unstimulated, myoblasts and mouse gastrocnemius muscle was further affirmed by subcellular fractionation and subsequent immunoblotting. Collectively, these results strongly support a critical role of FLJ00068 in Akt2-mediated Rac1 activation in mouse skeletal muscle insulin signaling.
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Affiliation(s)
- Nobuyuki Takenaka
- Laboratory of Cell Biology, Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka, Japan
| | - Yuma Nihata
- Laboratory of Cell Biology, Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka, Japan
| | - Takaya Satoh
- Laboratory of Cell Biology, Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka, Japan
- * E-mail:
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18
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Jia Z, Johnson AC, Wang X, Guo Z, Dreisbach AW, Lewin JR, Kyle PB, Garrett MR. Allelic Variants in Arhgef11 via the Rho-Rock Pathway Are Linked to Epithelial-Mesenchymal Transition and Contributes to Kidney Injury in the Dahl Salt-Sensitive Rat. PLoS One 2015; 10:e0132553. [PMID: 26172442 PMCID: PMC4501567 DOI: 10.1371/journal.pone.0132553] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 06/17/2015] [Indexed: 12/21/2022] Open
Abstract
Previously, genetic analyses identified that variants in Arhgef11 may influence kidney injury in the Dahl salt-sensitive (S) rat, a model of hypertensive chronic kidney disease. To understand the potential mechanism by which altered expression and/or protein differences in Arhgef11 could play a role in kidney injury, stably transduced Arhgef11 knockdown cell lines as well as primary cultures of proximal tubule cells were studied. Genetic knockdown of Arhgef11 in HEK293 and NRK resulted in reduced RhoA activity, decreased activation of Rho-ROCK pathway, and less stress fiber formation versus control, similar to what was observed by pharmacological inhibition (fasudil). Primary proximal tubule cells (PTC) cultured from the S exhibited increased expression of Arhgef11, increased RhoA activity, and up regulation of Rho-ROCK signaling compared to control (small congenic). The cells were also more prone (versus control) to TGFβ-1 induced epithelial-mesenchymal transition (EMT), a hallmark feature of the development of renal interstitial fibrosis, and characterized by development of spindle shape morphology, gene expression changes in EMT markers (Col1a3, Mmp9, Bmp7, and Ocln) and increased expression of N-Cadherin and Vimentin. S derived PTC demonstrated a decreased ability to uptake FITC-albumin compared to the small congenic in vitro, which was confirmed by assessment of albumin re-uptake in vivo by infusion of FITC-albumin and immunofluorescence imaging. In summary, these studies suggest that genetic variants in the S form of Arhgef11 via increased expression and/or protein activity play a role in promoting kidney injury in the S rat through changes in cell morphology (Rho-Rock and/or EMT) that impact the function of tubule cells.
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Affiliation(s)
- Zhen Jia
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS, United States of America
| | - Ashley C. Johnson
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS, United States of America
| | - Xuexiang Wang
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS, United States of America
| | - Zibiao Guo
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS, United States of America
- Molecular and Genomics Core Facility, University of Mississippi Medical Center, Jackson, MS, United States of America
| | - Albert W. Dreisbach
- Department of Medicine (Nephrology), University of Mississippi Medical Center, Jackson, MS, United States of America
| | - Jack R. Lewin
- Department of Pathology, University of Mississippi Medical Center, Jackson, MS, United States of America
| | - Patrick B. Kyle
- Department of Pathology, University of Mississippi Medical Center, Jackson, MS, United States of America
| | - Michael R. Garrett
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS, United States of America
- Department of Medicine (Nephrology), University of Mississippi Medical Center, Jackson, MS, United States of America
- * E-mail:
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Vives V, Cres G, Richard C, Busson M, Ferrandez Y, Planson AG, Zeghouf M, Cherfils J, Malaval L, Blangy A. Pharmacological inhibition of Dock5 prevents osteolysis by affecting osteoclast podosome organization while preserving bone formation. Nat Commun 2015; 6:6218. [PMID: 25645278 DOI: 10.1038/ncomms7218] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 01/07/2015] [Indexed: 12/13/2022] Open
Abstract
Osteoporosis is caused by excessive activity of bone-degrading osteoclasts over bone-forming osteoblast. Standard antiosteolytic treatments inhibit bone resorption by inducing osteoclast loss, with the adverse effect of hindering also bone formation. Formation of the osteoclast sealing zone requires Dock5, a guanine nucleotide exchange factor for the small GTPase Rac, and C21, a chemical inhibitor of Dock5, decreases bone resorption by cultured osteoclasts. Here we show that C21 directly inhibits the exchange activity of Dock5 and disrupts osteoclast podosome organization. Remarkably, C21 administration protects mice against bone degradation in models recapitulating major osteolytic diseases: menopause, rheumatoid arthritis and bone metastasis. Furthermore, C21 administration does not affect bone formation and is not toxic. Our results validate the pharmacological inhibition of Dock5 as a novel therapeutic route for fighting osteolytic diseases while preserving bone formation.
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Affiliation(s)
- Virginie Vives
- 1] Centre de Recherche de Biochimie Macromoléculaire, CNRS UMR 5237, 34293, Montpellier cedex 5, France [2] Montpellier University, 34095 Montpellier cedex 5, France
| | - Gaëlle Cres
- 1] Centre de Recherche de Biochimie Macromoléculaire, CNRS UMR 5237, 34293, Montpellier cedex 5, France [2] Montpellier University, 34095 Montpellier cedex 5, France
| | - Christian Richard
- 1] Centre de Recherche de Biochimie Macromoléculaire, CNRS UMR 5237, 34293, Montpellier cedex 5, France [2] Montpellier University, 34095 Montpellier cedex 5, France
| | - Muriel Busson
- Institut de Recherche en Cancérologie de Montpellier, U896 INSERM, 34298 Montpellier cedex 5, France
| | - Yann Ferrandez
- Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, Centre de Recherche de Gif, 91198 Gif-sur-Yvette, France
| | - Anne-Gaelle Planson
- Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, Centre de Recherche de Gif, 91198 Gif-sur-Yvette, France
| | - Mahel Zeghouf
- Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, Centre de Recherche de Gif, 91198 Gif-sur-Yvette, France
| | - Jacqueline Cherfils
- Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, Centre de Recherche de Gif, 91198 Gif-sur-Yvette, France
| | - Luc Malaval
- INSERM U1059, Université Jean Monnet, 42023 Saint-Etienne cedex 02, France
| | - Anne Blangy
- 1] Centre de Recherche de Biochimie Macromoléculaire, CNRS UMR 5237, 34293, Montpellier cedex 5, France [2] Montpellier University, 34095 Montpellier cedex 5, France
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20
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Liao CY, Lee CL, Wang HC, Liang SS, Kung PH, Wu YC, Chang FR, Wu CC. CLL2-1, a chemical derivative of orchid 1,4-phenanthrenequinones, inhibits human platelet aggregation through thiol modification of calcium-diacylglycerol guanine nucleotide exchange factor-I (CalDAG-GEFI). Free Radic Biol Med 2015; 78:101-10. [PMID: 25451646 DOI: 10.1016/j.freeradbiomed.2014.10.512] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Revised: 10/14/2014] [Accepted: 10/14/2014] [Indexed: 11/29/2022]
Abstract
CalDAG-GEFI is a guanine nucleotide exchange factor, which actives small GTPase Rap1 and plays an important role in platelet aggregation. Our previous study has shown that CalDAG-GEFI contains redox-sensitive thiols, and its function can be inhibited by thiol modification. In the present study, the effect of CLL2-1, a 1,4-phenanthrenequinone, on CalDAG-GEFI and platelet functions was investigated. In human platelets, CLL2-1 prevented platelet aggregation caused by various stimulators. Flow cytometric analysis revealed that CLL2-1 inhibited GPIIb/IIIa activation and P-selectin secretion. Moreover, CLL2-1 prevented Rap1 activation caused by thrombin, the Ca(2+) ionophore A23187, and the diacylglycerol mimetic phorbol 12-myristate 13-acetate, while only slightly inhibited thrombin-induced increases in [Ca(2+)]i and did not inhibit protein kinase C activation. Western blots after reducing SDS-PAGE showed that treatment of either platelets or platelet lysates with CLL2-1 led to a decrease of monomeric CalDAG-GEFI and appearance of cross-linked oligomers of CalDAG-GEFI, and these effects were inhibited by pretreatment of platelets or lysates with thiol reducing agents prior to the addition of CLL2-1, indicating thiol modification of CalDAG-GEFI by CLL2-1. Furthermore, the thiol reducing agents also prevented the inhibitory effect of CLL2-1 on Rap1 activation, GPIIb/IIIa activation, and platelet aggregation. In CalDAG-GEFI-overexpressing human embryonic kidney 293T cells, CLL2-1 also inhibited CalDAG-GEFI-mediated Rap1 activation. Taken together, our results suggest that the antiplatelet effect of CLL2-1 is due to, at least in part, inhibition of CalDAG-GEFI-mediated Rap1 activation, and provide the basis for development of novel antiplatelet drugs.
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Affiliation(s)
- Chieh-Yu Liao
- Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Chia-Lin Lee
- School of Pharmacy, College of Pharmacy, China Medical University, Taichung, Taiwan
| | - Hui-Chun Wang
- Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Shih-Shin Liang
- Department of Biotechnology, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Po-Hsiung Kung
- Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Yang-Chang Wu
- School of Pharmacy, College of Pharmacy, China Medical University, Taichung, Taiwan
| | - Fang-Rong Chang
- Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Chin-Chung Wu
- Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung, Taiwan; Department of Marine Biotechnology and Resources, National Sun Yat-Sen University, Kaohsiung, Taiwan.
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21
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Ohtsu Y, Nakagawa Y, Nagasawa M, Takeda S, Arakawa H, Kojima I. Diverse signaling systems activated by the sweet taste receptor in human GLP-1-secreting cells. Mol Cell Endocrinol 2014; 394:70-9. [PMID: 25017733 DOI: 10.1016/j.mce.2014.07.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 06/30/2014] [Accepted: 07/04/2014] [Indexed: 01/08/2023]
Abstract
Sweet taste receptor regulates GLP-1 secretion in enteroendocrine L-cells. We investigated the signaling system activated by this receptor using Hutu-80 cells. We stimulated them with sucralose, saccharin, acesulfame K and glycyrrhizin. These sweeteners stimulated GLP-1 secretion, which was attenuated by lactisole. All these sweeteners elevated cytoplasmic cyclic AMP ([cAMP]c) whereas only sucralose and saccharin induced a monophasic increase in cytoplasmic Ca(2+) ([Ca(2+)]c). Removal of extracellular calcium or sodium and addition of a Gq/11 inhibitor greatly reduced the [Ca(2+)]c responses to two sweeteners. In contrast, acesulfame K induced rapid and sustained reduction of [Ca(2+)]c. In addition, glycyrrhizin first reduced [Ca(2+)]c which was followed by an elevation of [Ca(2+)]c. Reductions of [Ca(2+)]c induced by acesulfame K and glycyrrhizin were attenuated by a calmodulin inhibitor or by knockdown of the plasma membrane calcium pump. These results indicate that various sweet molecules act as biased agonists and evoke strikingly different patterns of intracellular signals.
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Affiliation(s)
- Yoshiaki Ohtsu
- Institute for Molecular & Cellular Regulation, Gunma University, Maebashi 371-8512, Japan; Department of Pediatrics, Gunma University Graduate School of Medicine, Maebashi 371-8511, Japan
| | - Yuko Nakagawa
- Institute for Molecular & Cellular Regulation, Gunma University, Maebashi 371-8512, Japan
| | - Masahiro Nagasawa
- Institute for Molecular & Cellular Regulation, Gunma University, Maebashi 371-8512, Japan
| | - Shigeki Takeda
- Gunma University Graduate School of Technology, Kiryu 376-8515, Japan
| | - Hirokazu Arakawa
- Department of Pediatrics, Gunma University Graduate School of Medicine, Maebashi 371-8511, Japan
| | - Itaru Kojima
- Institute for Molecular & Cellular Regulation, Gunma University, Maebashi 371-8512, Japan.
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22
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Um K, Niu S, Duman JG, Cheng JX, Tu YK, Schwechter B, Liu F, Hiles L, Narayanan AS, Ash RT, Mulherkar S, Alpadi K, Smirnakis SM, Tolias KF. Dynamic control of excitatory synapse development by a Rac1 GEF/GAP regulatory complex. Dev Cell 2014; 29:701-15. [PMID: 24960694 DOI: 10.1016/j.devcel.2014.05.011] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Revised: 04/23/2014] [Accepted: 05/14/2014] [Indexed: 11/18/2022]
Abstract
The small GTPase Rac1 orchestrates actin-dependent remodeling essential for numerous cellular processes including synapse development. While precise spatiotemporal regulation of Rac1 is necessary for its function, little is known about the mechanisms that enable Rac1 activators (GEFs) and inhibitors (GAPs) to act in concert to regulate Rac1 signaling. Here, we identify a regulatory complex composed of a Rac-GEF (Tiam1) and a Rac-GAP (Bcr) that cooperate to control excitatory synapse development. Disruption of Bcr function within this complex increases Rac1 activity and dendritic spine remodeling, resulting in excessive synaptic growth that is rescued by Tiam1 inhibition. Notably, EphB receptors utilize the Tiam1-Bcr complex to control synaptogenesis. Following EphB activation, Tiam1 induces Rac1-dependent spine formation, whereas Bcr prevents Rac1-mediated receptor internalization, promoting spine growth over retraction. The finding that a Rac-specific GEF/GAP complex is required to maintain optimal levels of Rac1 signaling provides an important insight into the regulation of small GTPases.
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Affiliation(s)
- Kyongmi Um
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Sanyong Niu
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Joseph G Duman
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Jinxuan X Cheng
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Yen-Kuei Tu
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Integrative Molecular and Biomedical Sciences Program, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Brandon Schwechter
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Feng Liu
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Laura Hiles
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Anjana S Narayanan
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Ryan T Ash
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Shalaka Mulherkar
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Kannan Alpadi
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Stelios M Smirnakis
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Kimberley F Tolias
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Integrative Molecular and Biomedical Sciences Program, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
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23
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Naramoto S, Otegui MS, Kutsuna N, de Rycke R, Dainobu T, Karampelias M, Fujimoto M, Feraru E, Miki D, Fukuda H, Nakano A, Friml J. Insights into the localization and function of the membrane trafficking regulator GNOM ARF-GEF at the Golgi apparatus in Arabidopsis. Plant Cell 2014; 26:3062-76. [PMID: 25012191 PMCID: PMC4145132 DOI: 10.1105/tpc.114.125880] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 05/28/2014] [Accepted: 06/04/2014] [Indexed: 05/19/2023]
Abstract
GNOM is one of the most characterized membrane trafficking regulators in plants, with crucial roles in development. GNOM encodes an ARF-guanine nucleotide exchange factor (ARF-GEF) that activates small GTPases of the ARF (ADP ribosylation factor) class to mediate vesicle budding at endomembranes. The crucial role of GNOM in recycling of PIN auxin transporters and other proteins to the plasma membrane was identified in studies using the ARF-GEF inhibitor brefeldin A (BFA). GNOM, the most prominent regulator of recycling in plants, has been proposed to act and localize at so far elusive recycling endosomes. Here, we report the GNOM localization in context of its cellular function in Arabidopsis thaliana. State-of-the-art imaging, pharmacological interference, and ultrastructure analysis show that GNOM predominantly localizes to Golgi apparatus. Super-resolution confocal live imaging microscopy identified GNOM and its closest homolog GNOM-like 1 at distinct subdomains on Golgi cisternae. Short-term BFA treatment stabilizes GNOM at the Golgi apparatus, whereas prolonged exposures results in GNOM translocation to trans-Golgi network (TGN)/early endosomes (EEs). Malformed TGN/EE in gnom mutants suggests a role for GNOM in maintaining TGN/EE function. Our results redefine the subcellular action of GNOM and reevaluate the identity and function of recycling endosomes in plants.
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Affiliation(s)
- Satoshi Naramoto
- Department of Plant Systems Biology, VIB, and Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium Molecular Membrane Biology laboratory, RIKEN Advanced Science Institute, Wako, Saitama 351-0198, Japan Department of Life Science, International Christian University, Mitaka-shi, Tokyo 181-8585, Japan
| | - Marisa S Otegui
- Department of Botany and Genetics, University of Wisconsin, Madison, Wisconsin 53706
| | - Natsumaro Kutsuna
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba 277-8562, Japan
| | - Riet de Rycke
- Department of Plant Systems Biology, VIB, and Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
| | - Tomoko Dainobu
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Michael Karampelias
- Department of Plant Systems Biology, VIB, and Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
| | - Masaru Fujimoto
- Laboratory of Plant Molecular Genetics, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Elena Feraru
- Department of Plant Systems Biology, VIB, and Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
| | - Daisuke Miki
- Department of Plant Systems Biology, VIB, and Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
| | - Hiroo Fukuda
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Akihiko Nakano
- Molecular Membrane Biology laboratory, RIKEN Advanced Science Institute, Wako, Saitama 351-0198, Japan Department of Biological Sciences, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan Live Cell Molecular Imaging Research Team, Extreme Photonics Research Group, RIKEN Center for Advanced Photonics, Wako, Saitama 351-0198, Japan
| | - Jiří Friml
- Department of Plant Systems Biology, VIB, and Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
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24
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Hofbauer SW, Krenn PW, Ganghammer S, Asslaber D, Pichler U, Oberascher K, Henschler R, Wallner M, Kerschbaum H, Greil R, Hartmann TN. Tiam1/Rac1 signals contribute to the proliferation and chemoresistance, but not motility, of chronic lymphocytic leukemia cells. Blood 2014; 123:2181-8. [PMID: 24501217 DOI: 10.1182/blood-2013-08-523563] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Signals from the tumor microenvironment promote the migration, survival, and proliferation of chronic lymphocytic leukemia (CLL) cells. Rho GTPases control various signaling pathways downstream of microenvironmental cues. Here, we analyze the function of Rac1 in the motility and proliferation of CLL cells. We found decreased transcription of the Rac guanine nucleotide exchange factors Tiam1 and Vav1 in unstimulated peripheral blood CLL cells with almost complete loss of Tiam1 but increased transcription of the potential Rac antagonist RhoH. Consistently, stimulation of CLL cells with the chemokine CXCL12 induced RhoA but not Rac1 activation, whereas chemokine-induced CLL cell motility was Rac1-independent. Coculture of CLL cells with activated T cells induced their activation and subsequent proliferation. Here, Tiam1 expression was induced in the malignant cells in line with increased Ki-67 and c-Myc expression. Rac1 or Tiam1 knockdown using siRNA or treatment with the Tiam1/Rac inhibitor NSC-23766 attenuated c-Myc transcription. Furthermore, treatment of CLL cells with NSC-23766 reduced their proliferation. Rac inhibition also antagonized the chemoresistance of activated CLL cells toward fludarabine. Collectively, our data suggest a dynamic regulation of Rac1 function in the CLL microenvironment. Rac inhibition could be of clinical use by selectively interfering with CLL cell proliferation and chemoresistance.
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MESH Headings
- Aminoquinolines/pharmacology
- Animals
- Antineoplastic Agents/pharmacology
- Cell Movement/genetics
- Cell Proliferation
- Cells, Cultured
- Drug Resistance, Neoplasm/genetics
- Gene Expression Regulation, Leukemic/drug effects
- Guanine Nucleotide Exchange Factors/antagonists & inhibitors
- Guanine Nucleotide Exchange Factors/physiology
- Humans
- Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy
- Leukemia, Lymphocytic, Chronic, B-Cell/genetics
- Leukemia, Lymphocytic, Chronic, B-Cell/pathology
- Mice
- NIH 3T3 Cells
- Pyrimidines/pharmacology
- RNA, Small Interfering/genetics
- Signal Transduction/physiology
- T-Lymphoma Invasion and Metastasis-inducing Protein 1
- rac1 GTP-Binding Protein/antagonists & inhibitors
- rac1 GTP-Binding Protein/physiology
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Affiliation(s)
- Sebastian W Hofbauer
- Laboratory for Immunological and Molecular Cancer Research, Third Medical Department with Hematology, Oncology, Hemostaseology, Infectiology, and Rheumatology, Oncologic Center, Paracelsus Medical University, Salzburg, Austria
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25
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Liu Y, Ding Y, Huang J, Wang S, Ni W, Guan J, Li Q, Zhang Y, Ding Y, Chen B, Chen L. MiR-141 suppresses the migration and invasion of HCC cells by targeting Tiam1. PLoS One 2014; 9:e88393. [PMID: 24551096 PMCID: PMC3923786 DOI: 10.1371/journal.pone.0088393] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 01/06/2014] [Indexed: 12/15/2022] Open
Abstract
Background We have demonstrated that T lymphoma invasion and metastasis 1 (Tiam1) gene is associated with the poor prognosis of patients with hepatocellular carcinoma (HCC), and we used a computational approach to identify miR-141 as a Tiam1-targeting microRNA (miRNA). Here, we explored the function of miR-141 and the relationship between miR-141 and Tiam1 gene in HCC. Methods The miR-141 expression in HCC tissues and cell lines was detected and its roles in regulation of HCC cell proliferation, migration and invasion and target gene expression was investigated. Tiam1 was identified as a novel target of miR-141. Ethics statement: our study was approved by the Nanfang Hospital Medical Ethics Committee Ethics statement. Written informed consent was obtained before collection. Results Based on in situ hybridization (ISH) analysis, miR-141 was down-regulated in the same HCC samples. Kaplan-Meier analysis demonstrated that patients with low miR-141 expression had poorer overall survival rate than that of the patients with high miR-141 expression. Furthermore, multivariate Cox regression analysis indicated that miR-141 could serve as an independent prognostic factor in HCC. MiR-141 significantly inhibited in vitro cell proliferation, migration and invasion as proved by gain- and loss- of function studies, while the mRNA and protein levels of Tiam1 were reduced in cells over-expressing miR-141. Moreover, Tiam1 treatment antagonized this effect, while knockdown of Tiam1 by Tiam1 short hairpin RNA (shTiam1) induced inhibitory effects. Conclusions These findings indicated that miR-141 functions as a tumor suppressor and inhibits the migration and invasion of HCC cells by targeting Tiam1, which may provide novel prognostic and treatment strategies for HCC patients.
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Affiliation(s)
- Ying Liu
- Department of Radiation Oncology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, PR China
| | - Yi Ding
- Department of Radiation Oncology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, PR China
| | - Jing Huang
- Department of Radiation Oncology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, PR China
- Department of Cancer Center of Affiliated Hospital, Guangdong Medical College, Zhanjiang, China
| | - Shuang Wang
- Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong Province, People’s Republic of China
| | - Wen Ni
- Department of Radiation Oncology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, PR China
| | - Jian Guan
- Department of Radiation Oncology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, PR China
| | - Qisheng Li
- Department of Radiation Oncology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, PR China
| | - Yuqin Zhang
- Department of Radiation Oncology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, PR China
| | - Yanqing Ding
- Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong Province, People’s Republic of China
| | - Bin Chen
- General Hospital of Guangzhou Military Command of PLA, Southern Medical University, Guangzhou, Guangdong Province, People’s Republic of China
- * E-mail: (BC); (LC)
| | - Longhua Chen
- Department of Radiation Oncology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, PR China
- * E-mail: (BC); (LC)
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Hu Z, Xu R, Liu J, Zhang Y, Du J, Li W, Zhang W, Li Y, Zhu Y, Gu L. GEP100 regulates epidermal growth factor-induced MDA-MB-231 breast cancer cell invasion through the activation of Arf6/ERK/uPAR signaling pathway. Exp Cell Res 2013; 319:1932-1941. [PMID: 23747719 DOI: 10.1016/j.yexcr.2013.05.028] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 05/10/2013] [Accepted: 05/29/2013] [Indexed: 02/07/2023]
Abstract
GEP100, a guanine nucleotide exchanging factor (GEF) for Arf6, plays a pivotal role in promoting breast cancer cell invasion both in vitro and in vivo. However, the precise mechanism for GEP100-mediated cell invasion is still poorly understood. In this study, we found that down-regulation of endogenous GEP100 in MDA-MB-231 cells significantly inhibited EGF-induced cell invasion, which was rescued by over-expression of ectopic GEP100. EGF increased Arf6 activity, ERK phosphorylation, and uPAR expression in a time dependent manner. Additionally, blocking Arf6 with Arf6 siRNA largely abolished EGF-induced cell invasion. GEP100 siRNA or Arf6 siRNA suppressed EGF-induced ERK activity and uPAR expression. Furthermore, blocking ERK signaling with U0126, a specific inhibitor for MEK, markedly inhibited EGF-induced uPAR expression and consequently cell invasion. Inhibition of uPAR expression by uPAR siRNA also significantly abolished EGF-induced cell invasion. Taken together, this study illustrates that GEP100 regulates an Arf6/ERK/uPAR signaling cascade in EGF-induced breast cancer cell invasion. These findings could provide a rationale for designing new therapies based on inhibition of breast cancer metastasis.
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Affiliation(s)
- Zhenzhen Hu
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, Jiangsu 210029, PR China
| | - Rui Xu
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu 210029, PR China
| | - Jiaojing Liu
- Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 210029, PR China
| | - Yujie Zhang
- Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 210029, PR China
| | - Jun Du
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, Jiangsu 210029, PR China; Cancer Center, Nanjing Medical University, Nanjing, Jiangsu 210029, PR China
| | - Weixing Li
- Medicine Technique School, Taizhou Polytechnic College, Taizhou, Jiangsu 225300, PR China
| | - Wanqiu Zhang
- Medicine Technique School, Taizhou Polytechnic College, Taizhou, Jiangsu 225300, PR China
| | - Yueying Li
- School of Medical Sciences and Laboratory Medicine, Jiangsu University, Zhenjiang, Jiangsu 212013, PR China
| | - Yichao Zhu
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, Jiangsu 210029, PR China; Cancer Center, Nanjing Medical University, Nanjing, Jiangsu 210029, PR China.
| | - Luo Gu
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, Jiangsu 210029, PR China; Cancer Center, Nanjing Medical University, Nanjing, Jiangsu 210029, PR China.
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27
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Abstract
We have shown that resistance to inhibitors of cholinesterase 8 (Ric-8) proteins regulate an early step of heterotrimeric G protein α (Gα) subunit biosynthesis. Here, mammalian and plant cell-free translation systems were used to study Ric-8A action during Gα subunit translation and protein folding. Gα translation rates and overall produced protein amounts were equivalent in mock and Ric-8A-immunodepleted rabbit reticulocyte lysate (RRL). GDP-AlF4(-)-bound Gαi, Gαq, Gα13, and Gαs produced in mock-depleted RRL had characteristic resistance to limited trypsinolysis, showing that these G proteins were folded properly. Gαi, Gαq, and Gα13, but not Gαs produced from Ric-8A-depleted RRL were not protected from trypsinization and therefore not folded correctly. Addition of recombinant Ric-8A to the Ric-8A-depleted RRL enhanced GDP-AlF4(-)-bound Gα subunit trypsin protection. Dramatic results were obtained in wheat germ extract (WGE) that has no endogenous Ric-8 component. WGE-translated Gαq was gel filtered and found to be an aggregate. Ric-8A supplementation of WGE allowed production of Gαq that gel filtered as a ∼100 kDa Ric-8A:Gαq heterodimer. Addition of GTPγS to Ric-8A-supplemented WGE Gαq translation resulted in dissociation of the Ric-8A:Gαq heterodimer and production of functional Gαq-GTPγS monomer. Excess Gβγ supplementation of WGE did not support functional Gαq production. The molecular chaperoning function of Ric-8 is to participate in the folding of nascent G protein α subunits.
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Affiliation(s)
- PuiYee Chan
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642; and
| | - Celestine J. Thomas
- Center for Biomolecular Structure and Dynamics and the Division of Biological Science, University of Montana, Missoula, MT 59812
| | - Stephen R. Sprang
- Center for Biomolecular Structure and Dynamics and the Division of Biological Science, University of Montana, Missoula, MT 59812
| | - Gregory G. Tall
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642; and
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Eckler AM, Wilder C, Castanon A, Ferris VM, Lamere RA, Perrin BA, Pearlman R, White B, Byrd C, Ludvik N, Nichols N, Poole-Sumrall K, Sztul E, Styers ML. Haploinsufficiency of the Sec7 guanine nucleotide exchange factor gea1 impairs septation in fission yeast. PLoS One 2013; 8:e56807. [PMID: 23457617 PMCID: PMC3574105 DOI: 10.1371/journal.pone.0056807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Accepted: 01/15/2013] [Indexed: 11/19/2022] Open
Abstract
Membrane trafficking is essential to eukaryotic life and is controlled by a complex network of proteins that regulate movement of proteins and lipids between organelles. The GBF1/GEA family of Guanine nucleotide Exchange Factors (GEFs) regulates trafficking between the endoplasmic reticulum and Golgi by catalyzing the exchange of GDP for GTP on ADP Ribosylation Factors (Arfs). Activated Arfs recruit coat protein complex 1 (COP-I) to form vesicles that ferry cargo between these organelles. To further explore the function of the GBF1/GEA family, we have characterized a fission yeast mutant lacking one copy of the essential gene gea1 (gea1+/-), the Schizosaccharomyces pombe ortholog of GBF1. The haploinsufficient gea1+/- strain was shown to be sensitive to the GBF1 inhibitor brefeldin A (BFA) and was rescued from BFA sensitivity by gea1p overexpression. No overt defects in localization of arf1p or arf6p were observed in gea1+/- cells, but the fission yeast homolog of the COP-I cargo sac1 was mislocalized, consistent with impaired COP-I trafficking. Although Golgi morphology appeared normal, a slight increase in vacuolar size was observed in the gea1+/- mutant strain. Importantly, gea1+/- cells exhibited dramatic cytokinesis-related defects, including disorganized contractile rings, an increased septation index, and alterations in septum morphology. Septation defects appear to result from altered secretion of enzymes required for septum dynamics, as decreased secretion of eng1p, a β-glucanase required for septum breakdown, was observed in gea1+/- cells, and overexpression of eng1p suppressed the increased septation phenotype. These observations implicate gea1 in regulation of septum breakdown and establish S. pombe as a model system to explore GBF1/GEA function in cytokinesis.
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Affiliation(s)
- Alan M. Eckler
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Caroline Wilder
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Antonio Castanon
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Veronica M. Ferris
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Rachael A. Lamere
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Benjamin A. Perrin
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Ross Pearlman
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Blaise White
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Clifton Byrd
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Nicholas Ludvik
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Nona Nichols
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Kristen Poole-Sumrall
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Elizabeth Sztul
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Melanie L. Styers
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
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Li LC, Jayarama S, Pilli T, Qian L, Pacini F, Prabhakar BS. Down-modulation of expression, or dephosphorylation, of IG20/MADD in tumor necrosis factor-related apoptosis-inducing ligand-resistant thyroid cancer cells makes them susceptible to treatment with this ligand. Thyroid 2013; 23:70-8. [PMID: 22998497 PMCID: PMC3539253 DOI: 10.1089/thy.2012.0155] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND The IG20/MADD gene is overexpressed in thyroid cancer tissues and cell lines, and can contribute to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) resistance. The ability of the MADD protein to resist TRAIL-induced apoptosis is dependent upon its phosphorylation by Akt. Interestingly, while TRAIL induces a significant reduction in the levels of phospho-Akt (pAkt) and phospho-MADD (pMADD) in TRAIL-sensitive cells, it fails to do so in TRAIL-resistant cells. In this study, we investigated if MADD phosphorylation by Akt was contributing to TRAIL resistance in thyroid cancer cells. METHODS We determined the susceptibility of different thyroid cancer cell lines to TRAIL-induced apoptosis by fluorescence-activated cell sorting (FACS) analysis. We tested for various TRAIL resistance factors by FACS analyses or for IG20/MADD expression by quantitative reverse transcription-polymerase chain reaction. We determined the levels of pAkt and pMADD upon TRAIL treatment in thyroid cancer cells by Western blotting. We tested if down-modulation of IG20/MADD gene expression using shRNA or phosphorylation using a dominant negative Akt (DN-Akt) or pretreatment with LY294002, a PI3 kinase inhibitor, could help overcome TRAIL resistance. RESULT BCPAP and TPC1 cells were susceptible, while KTC1 and FTC133 cells were resistant, to TRAIL-induced apoptosis. The differential susceptibility to TRAIL was not related to the levels of expression of death receptors, decoy receptors, or TRAIL. KTC1 and FTC133 cells showed higher levels of IG20/MADD expression relative to BCPAP and TPC1, and were rendered susceptible to TRAIL treatment upon IG20/MADD knockdown. Interestingly, upon TRAIL treatment, the pAkt and pMADD levels were reduced in TRAIL-sensitive BCPAP and TPC1 cells, while they remained unchanged in the resistant KTC1 and FTC133 cells. While expression of a constitutively active Akt in BCPAP and TPC1 cells rendered them resistant to TRAIL, pretreating KTC1 and FTC133 cells with LY294002 rendered them TRAIL-sensitive. Moreover, expression of a DN-Akt in KTC1 and FTC133 cells reduced the levels of pAkt and pMADD and sensitized them to TRAIL-induced apoptosis. CONCLUSION Our results show that pMADD is an important TRAIL resistance factor in certain thyroid cancer cells and suggest that down-modulation of either IG20/MADD expression or phosphorylation can render TRAIL-resistant thyroid cancer cells sensitive to TRAIL.
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Affiliation(s)
- Liang-Cheng Li
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Shankara Jayarama
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Tania Pilli
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois
- Section of Endocrinology & Metabolism, Department of Internal Medicine, Endocrinology & Metabolism and Biochemistry, University of Siena, Siena, Italy
| | - Lixia Qian
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Furio Pacini
- Section of Endocrinology & Metabolism, Department of Internal Medicine, Endocrinology & Metabolism and Biochemistry, University of Siena, Siena, Italy
| | - Bellur S. Prabhakar
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois
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Bill A, Schmitz A, König K, Heukamp LC, Hannam JS, Famulok M. Anti-proliferative effect of cytohesin inhibition in gefitinib-resistant lung cancer cells. PLoS One 2012; 7:e41179. [PMID: 22815959 PMCID: PMC3399819 DOI: 10.1371/journal.pone.0041179] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 06/18/2012] [Indexed: 11/18/2022] Open
Abstract
Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI), such as gefitinib, have been proven to efficiently inhibit the proliferation of a subset of non small-cell lung cancers (NSCLC). Unfortunately, the majority of NSCLC expressing wild type EGFR is primarily resistant to EGFR-TKI treatment. Here, we show that the proliferation of the gefitinib-resistant NSCLC cell lines H460 and A549 is reduced by the small molecule SecinH3 which indirectly attenuates EGFR activation by inhibition of cytohesins, a class of recently discovered cytoplasmic EGFR activators. SecinH3 and gefitinib showed a synergistic antiproliferative effect, which correlated with a profound inhibition of Akt activation and survivin expression. Treating mice bearing H460 xenografts with SecinH3 showed the antiproliferative and pro-apoptotic effect of SecinH3 in vivo. Our data suggest that targeting the EGFR indirectly by inhibiting its cytoplasmic activators, the cytohesins, has the potential to improve the treatment of primarily EGFR-TKI resistant lung cancers.
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Affiliation(s)
- Anke Bill
- Chemical Biology and Medicinal Chemistry Unit, Life and Medical Sciences (LIMES) Institute, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Anton Schmitz
- Chemical Biology and Medicinal Chemistry Unit, Life and Medical Sciences (LIMES) Institute, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Katharina König
- Institute of Pathology, University of Cologne, Köln, Germany
| | | | - Jeffrey S. Hannam
- Chemical Biology and Medicinal Chemistry Unit, Life and Medical Sciences (LIMES) Institute, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Michael Famulok
- Chemical Biology and Medicinal Chemistry Unit, Life and Medical Sciences (LIMES) Institute, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
- * E-mail:
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31
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Meiri D, Marshall CB, Greeve MA, Kim B, Balan M, Suarez F, Bakal C, Wu C, Larose J, Fine N, Ikura M, Rottapel R. Mechanistic insight into the microtubule and actin cytoskeleton coupling through dynein-dependent RhoGEF inhibition. Mol Cell 2012; 45:642-55. [PMID: 22405273 DOI: 10.1016/j.molcel.2012.01.027] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2011] [Revised: 09/01/2011] [Accepted: 01/20/2012] [Indexed: 11/16/2022]
Abstract
Actin-based stress fiber formation is coupled to microtubule depolymerization through the local activation of RhoA. While the RhoGEF Lfc has been implicated in this cytoskeleton coupling process, it has remained elusive how Lfc is recruited to microtubules and how microtubule recruitment moderates Lfc activity. Here, we demonstrate that the dynein light chain protein Tctex-1 is required for localization of Lfc to microtubules. Lfc residues 139-161 interact with Tctex-1 at a site distinct from the cleft that binds dynein intermediate chain. An NMR-based GEF assay revealed that interaction with Tctex-1 represses Lfc nucleotide exchange activity in an indirect manner that requires both polymerized microtubules and phosphorylation of S885 by PKA. We show that inhibition of Lfc by Tctex-1 is dynein dependent. These studies demonstrate a pivotal role of Tctex-1 as a negative regulator of actin filament organization through its control of Lfc in the crosstalk between microtubule and actin cytoskeletons.
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Affiliation(s)
- David Meiri
- Ontario Cancer Institute and the Campbell Family Cancer Research Institute, 101 College Street, Room 8-703 Toronto Medical Discovery Tower, University of Toronto, Toronto, ON M5G 1L7, Canada
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32
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van Rijssel J, Hoogenboezem M, Wester L, Hordijk PL, Van Buul JD. The N-terminal DH-PH domain of Trio induces cell spreading and migration by regulating lamellipodia dynamics in a Rac1-dependent fashion. PLoS One 2012; 7:e29912. [PMID: 22238672 PMCID: PMC3253119 DOI: 10.1371/journal.pone.0029912] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 12/06/2011] [Indexed: 11/19/2022] Open
Abstract
The guanine-nucleotide exchange factor Trio encodes two DH-PH domains that catalyze nucleotide exchange on Rac1, RhoG and RhoA. The N-terminal DH-PH domain is known to activate Rac1 and RhoG, whereas the C-terminal DH-PH domain can activate RhoA. The current study shows that the N-terminal DH-PH domain, upon expression in HeLa cells, activates Rac1 and RhoG independently from each other. In addition, we show that the flanking SH3 domain binds to the proline-rich region of the C-terminus of Rac1, but not of RhoG. However, this SH3 domain is not required for Rac1 or RhoG GDP-GTP exchange. Rescue experiments in Trio-shRNA-expressing cells showed that the N-terminal DH-PH domain of Trio, but not the C-terminal DH-PH domain, restored fibronectin-mediated cell spreading and migration defects that are observed in Trio-silenced cells. Kymograph analysis revealed that the N-terminal DH-PH domain, independent of its SH3 domain, controls the dynamics of lamellipodia. Using siRNA against Rac1 or RhoG, we found that Trio-D1-induced lamellipodia formation required Rac1 but not RhoG expression. Together, we conclude that the GEF Trio is responsible for lamellipodia formation through its N-terminal DH-PH domain in a Rac1-dependent manner during fibronectin-mediated spreading and migration.
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Affiliation(s)
- Jos van Rijssel
- Department of Molecular Cell Biology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Mark Hoogenboezem
- Department of Molecular Cell Biology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Lynn Wester
- Department of Molecular Cell Biology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Peter L. Hordijk
- Department of Molecular Cell Biology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Jaap D. Van Buul
- Department of Molecular Cell Biology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
- * E-mail:
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33
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Srougi MC, Burridge K. The nuclear guanine nucleotide exchange factors Ect2 and Net1 regulate RhoB-mediated cell death after DNA damage. PLoS One 2011; 6:e17108. [PMID: 21373644 PMCID: PMC3044157 DOI: 10.1371/journal.pone.0017108] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Accepted: 01/20/2011] [Indexed: 12/19/2022] Open
Abstract
Commonly used antitumor treatments, including radiation and chemotherapy, function by damaging the DNA of rapidly proliferating cells. However, resistance to these agents is a predominant clinical problem. A member of the Rho family of small GTPases, RhoB has been shown to be integral in mediating cell death after ionizing radiation (IR) or other DNA damaging agents in Ras-transformed cell lines. In addition, RhoB protein expression increases after genotoxic stress, and loss of RhoB expression causes radio- and chemotherapeutic resistance. However, the signaling pathways that govern RhoB-induced cell death after DNA damage remain enigmatic. Here, we show that RhoB activity increases in human breast and cervical cancer cell lines after treatment with DNA damaging agents. Furthermore, RhoB activity is necessary for DNA damage-induced cell death, as the stable loss of RhoB protein expression using shRNA partially protects cells and prevents the phosphorylation of c-Jun N-terminal kinases (JNKs) and the induction of the pro-apoptotic protein Bim after IR. The increase in RhoB activity after genotoxic stress is associated with increased activity of the nuclear guanine nucleotide exchange factors (GEFs), Ect2 and Net1, but not the cytoplasmic GEFs p115 RhoGEF or Vav2. Importantly, loss of Ect2 and Net1 via siRNA-mediated protein knock-down inhibited IR-induced increases in RhoB activity, reduced apoptotic signaling events, and protected cells from IR-induced cell death. Collectively, these data suggest a mechanism involving the nuclear GEFs Ect2 and Net1 for activating RhoB after genotoxic stress, thereby facilitating cell death after treatment with DNA damaging agents.
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Affiliation(s)
- Melissa C Srougi
- Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America.
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34
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Chen Z, Guo L, Sprang SR, Sternweis PC. Modulation of a GEF switch: autoinhibition of the intrinsic guanine nucleotide exchange activity of p115-RhoGEF. Protein Sci 2011; 20:107-17. [PMID: 21064165 PMCID: PMC3047067 DOI: 10.1002/pro.542] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 10/28/2010] [Accepted: 10/29/2010] [Indexed: 12/13/2022]
Abstract
p115-RhoGEF (p115) belongs to the family of RGS-containing guanine nucleotide exchange factors for Rho GTPases (RGS-RhoGEFs) that are activated by G12 class heterotrimeric G protein α subunits. All RGS-RhoGEFs possess tandemly linked Dbl-homology (DH) and plekstrin-homology (PH) domains, which bind and catalyze the exchange of GDP for GTP on RhoA. We have identified that the linker region connecting the N-terminal RGS-homology (RH) domain and the DH domain inhibits the intrinsic guanine nucleotide exchange (GEF) activity of p115, and determined the crystal structures of the DH/PH domains in the presence or absence of the inhibitory linker region. An N-terminal extension of the canonical DH domain (the GEF switch), which is critical to GEF activity, is well folded in the crystal structure of DH/PH alone, but becomes disordered in the presence of the linker region. The linker region is completely disordered in the crystal structure and partially disordered in the molecular envelope calculated from measurements of small angle x-ray scattering (SAXS). It is possible that Gα subunits activate p115 in part by relieving autoinhibition imposed by the linker region.
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Affiliation(s)
- Zhe Chen
- Department of Pharmacology, The University of Texas Southwestern Medical CenterDallas, Texas 75390
| | - Liang Guo
- BioCAT, Advanced Photon Source, Argonne National Laboratory9700 South Cass Avenue, Argonne, Illinois 60439
| | - Stephen R Sprang
- Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of MontanaMissoula, Montana 59812
| | - Paul C Sternweis
- Department of Pharmacology, The University of Texas Southwestern Medical CenterDallas, Texas 75390
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35
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Abstract
There is now considerable and increasing evidence for a causal role for aberrant activity of the Ras superfamily of small GTPases in human cancers. These GTPases function as GDP-GTP-regulated binary switches that control many fundamental cellular processes. A common mechanism of GTPase deregulation in cancer is the deregulated expression and/or activity of their regulatory proteins, guanine nucleotide exchange factors (GEFs) that promote formation of the active GTP-bound state and GTPase-activating proteins (GAPs) that return the GTPase to its GDP-bound inactive state. In this Review, we assess the association of GEFs and GAPs with cancer and their druggability for cancer therapeutics.
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Affiliation(s)
- Dominico Vigil
- University of North Carolina at Chapel Hill, Lineberger Comprehensive Cancer Center, Department of Pharmacology, Chapel Hill, North Carolina 27599, USA
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36
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Woodcock SA, Rushton HJ, Castañeda-Saucedo E, Myant K, White GR, Blyth K, Sansom OJ, Malliri A. Tiam1-Rac signaling counteracts Eg5 during bipolar spindle assembly to facilitate chromosome congression. Curr Biol 2010; 20:669-75. [PMID: 20346677 PMCID: PMC2989435 DOI: 10.1016/j.cub.2010.02.033] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 01/29/2010] [Accepted: 02/05/2010] [Indexed: 12/01/2022]
Abstract
Centrosome separation, critical for bipolar spindle formation and subsequent chromosome segregation during mitosis, occurs via distinct prophase and prometaphase pathways. Kinesin-5 (Eg5), a microtubule (MT) motor, pushes centrosomes apart during bipolar spindle assembly; its suppression results in monopolar spindles and mitotic arrest. Forces that antagonize Eg5 in prophase are unknown. Here we identify a new force generating mechanism mediated by the guanine nucleotide exchange factor (GEF) Tiam1, dependent on its ability to activate the GTPase Rac. We reveal that Tiam1 and Rac localize to centrosomes during prophase and prometaphase, and Tiam1, acting through Rac, ordinarily retards centrosome separation. Importantly, both Tiam1-depleted cells in culture and Rac1-deficient epithelial cells in vivo escape the mitotic arrest induced by Eg5 suppression. Moreover, Tiam1-depleted cells transit more slowly through prometaphase and display increased chromosome congression errors. Significantly, Eg5 suppression in Tiam1-depleted cells rectifies not only their increased centrosome separation but also their chromosome congression errors and mitotic delay. These findings identify Tiam1-Rac signaling as the first antagonist of centrosome separation during prophase, demonstrate its requirement in balancing Eg5-induced forces during bipolar spindle assembly in vitro and in vivo, and show that proper centrosome separation in prophase facilitates subsequent chromosome congression.
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Affiliation(s)
- Simon A. Woodcock
- Cell Signalling Group, Cancer Research UK Paterson Institute for Cancer Research, The University of Manchester, Manchester M20 4BX, UK
| | - Helen J. Rushton
- Cell Signalling Group, Cancer Research UK Paterson Institute for Cancer Research, The University of Manchester, Manchester M20 4BX, UK
| | - Eduardo Castañeda-Saucedo
- Cell Signalling Group, Cancer Research UK Paterson Institute for Cancer Research, The University of Manchester, Manchester M20 4BX, UK
| | - Kevin Myant
- Colorectal Cancer and Wnt Signalling Group, Cancer Research UK Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Gavin R.M. White
- Cell Signalling Group, Cancer Research UK Paterson Institute for Cancer Research, The University of Manchester, Manchester M20 4BX, UK
| | - Karen Blyth
- Colorectal Cancer and Wnt Signalling Group, Cancer Research UK Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Owen J. Sansom
- Colorectal Cancer and Wnt Signalling Group, Cancer Research UK Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Angeliki Malliri
- Cell Signalling Group, Cancer Research UK Paterson Institute for Cancer Research, The University of Manchester, Manchester M20 4BX, UK
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37
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Marat AL, McPherson PS. The connecdenn family, Rab35 guanine nucleotide exchange factors interfacing with the clathrin machinery. J Biol Chem 2010; 285:10627-37. [PMID: 20154091 PMCID: PMC2856271 DOI: 10.1074/jbc.m109.050930] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Revised: 12/15/2009] [Indexed: 11/06/2022] Open
Abstract
Rabs constitute the largest family of monomeric GTPases, yet for the majority of Rabs relatively little is known about their activation and recruitment to vesicle-trafficking pathways. We recently identified connecdenn (DENND1A), which contains an N-terminal DENN (differentially expressed in neoplastic versus normal cells) domain, a common and evolutionarily ancient protein module. Through its DENN domain, connecdenn functions enzymatically as a guanine-nucleotide exchange factor (GEF) for Rab35. Here we identify two additional connecdenn family members and demonstrate that all connecdenns function as Rab35 GEFs, albeit with different levels of activity. The DENN domain of connecdenn 1 and 2 binds Rab35, whereas connecdenn 3 does not, indicating that Rab35 binding and activation are separable functions. Through their highly divergent C termini, each of the connecdenns binds to clathrin and to the clathrin adaptor AP-2. Interestingly, all three connecdenns use different mechanisms to bind AP-2. Characterization of connecdenn 2 reveals binding to the beta2-ear of AP-2 on a site that overlaps with that used by the autosomal recessive hypercholesterolemia protein and betaarrestin, although the sequence used by connecdenn 2 is unique. Loss of connecdenn 2 function through small interference RNA knockdown results in an enlargement of early endosomes, similar to what is observed upon loss of Rab35 activity. Our studies reveal connecdenn DENN domains as generalized GEFs for Rab35 and identify a new AP-2-binding motif, demonstrating a complex link between the clathrin machinery and Rab35 activation.
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Affiliation(s)
- Andrea L. Marat
- From the Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Peter S. McPherson
- From the Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada
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38
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Bouquier N, Vignal E, Charrasse S, Weill M, Schmidt S, Léonetti JP, Blangy A, Fort P. A cell active chemical GEF inhibitor selectively targets the Trio/RhoG/Rac1 signaling pathway. ACTA ACUST UNITED AC 2009; 16:657-66. [PMID: 19549603 DOI: 10.1016/j.chembiol.2009.04.012] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Revised: 04/13/2009] [Accepted: 04/29/2009] [Indexed: 11/18/2022]
Abstract
RhoGEFs (guanine nucleotide exchange factors of the Rho GTPase family) are upstream regulators of cell adhesion and migration pathways, thus representing attractive yet relatively unexplored targets for the development of anti-invasive drugs. We screened for chemical inhibitors of TrioN, the N-terminal GEF domain of the multidomain Trio protein, and identified ITX3 as a nontoxic inhibitor. In transfected mammalian cells, ITX3 blocked TrioN-mediated dorsal membrane ruffling and Rac1 activation while having no effect on GEF337-, Tiam1-, or Vav2-mediated RhoA or Rac1 activation. ITX3 specifically inhibited endogenous TrioN activity, as evidenced by its ability to inhibit neurite outgrowth in nerve growth factor (NGF)-stimulated PC12 cells or C2C12 differentiation into myotubes. This study introduces a selective cell active inhibitor of the Trio/RhoG/Rac1 pathway and validates RhoGEFs as druggable targets.
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Affiliation(s)
- Nathalie Bouquier
- Centre de Recherche de Biochimie Macromoléculaire, Universités Montpellier I et II, CNRS, 34293 Montpellier, France
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Hampson L, He XT, Oliver AW, Hadfield JA, Kemp T, Butler J, McGown A, Kitchener HC, Hampson IN. Analogues of Y27632 increase gap junction communication and suppress the formation of transformed NIH3T3 colonies. Br J Cancer 2009; 101:829-39. [PMID: 19707205 PMCID: PMC2736836 DOI: 10.1038/sj.bjc.6605208] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 05/29/2009] [Accepted: 06/30/2009] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Constitutive activation of RhoA-dependent RhoA kinase (ROCK) signalling is known to promote cellular transformation and the ROCK inhibitor Y-27632 has the ability to suppress focus formation of RhoA transformed NIH3T3 cells. METHODS Sixty-four novel structural analogues of Y27632 were synthesised and tested for their ability to persistently inhibit the transformation of NIH3T3 cells by Rho guanidine exchange factor 16 (ARHGEF16) or Ras. In vitro kinase inhibitor profiling, co-culture of transformed cells with non-transformed cells and a novel Lucifer yellow/PKH67 dye transfer method were used to investigate their mode of action. RESULTS Four Y27632 analogues inhibited transformed focus formation that persisted when the compound was withdrawn. No toxicity was observed against either transformed or non-transformed cells and the effect was dependent on co-culture of these two cell types. In vitro kinase inhibitor profiling indicated that these compounds had reduced activity against ROCK compared with Y27632, targeting instead Aurora A (AURKA), p38 (MAPK14) and Hgk (MAP4K4). Dye transfer analysis showed they increased gap junction intercellular communication (GJIC) between transformed and non-transformed cells. CONCLUSIONS These data are the first to suggest that transient blockade of specific kinases can induce a persistent inhibition of non-contact inhibited transformed colony formation and can also remove pre-formed colonies. These effects could potentially be mediated by the observed increase in GJIC between transformed and non-transformed cells. Selection of kinase inhibitors with this property may thus provide a novel strategy for cancer chemoprevention.
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Affiliation(s)
- L Hampson
- University of Manchester School of Cancer Studies and Imaging Science, Gynaecological Oncology Laboratories, St Mary's Hospital, Hathersage Road, Manchester M13 OJH, UK
| | - X T He
- University of Manchester School of Cancer Studies and Imaging Science, Gynaecological Oncology Laboratories, St Mary's Hospital, Hathersage Road, Manchester M13 OJH, UK
| | - A W Oliver
- University of Manchester School of Cancer Studies and Imaging Science, Gynaecological Oncology Laboratories, St Mary's Hospital, Hathersage Road, Manchester M13 OJH, UK
| | - J A Hadfield
- Centre for Molecular Drug Design, Kidscan Laboratories, Cockcroft Building, University of Salford, Manchester M5 4WT, UK
| | - T Kemp
- Centre for Molecular Drug Design, Kidscan Laboratories, Cockcroft Building, University of Salford, Manchester M5 4WT, UK
| | - J Butler
- Centre for Molecular Drug Design, Kidscan Laboratories, Cockcroft Building, University of Salford, Manchester M5 4WT, UK
| | - A McGown
- Centre for Molecular Drug Design, Kidscan Laboratories, Cockcroft Building, University of Salford, Manchester M5 4WT, UK
| | - H C Kitchener
- University of Manchester School of Cancer Studies and Imaging Science, Gynaecological Oncology Laboratories, St Mary's Hospital, Hathersage Road, Manchester M13 OJH, UK
| | - I N Hampson
- University of Manchester School of Cancer Studies and Imaging Science, Gynaecological Oncology Laboratories, St Mary's Hospital, Hathersage Road, Manchester M13 OJH, UK
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Borland G, Bird RJ, Palmer TM, Yarwood SJ. Activation of protein kinase Calpha by EPAC1 is required for the ERK- and CCAAT/enhancer-binding protein beta-dependent induction of the SOCS-3 gene by cyclic AMP in COS1 cells. J Biol Chem 2009; 284:17391-403. [PMID: 19423709 PMCID: PMC2719379 DOI: 10.1074/jbc.m109.015370] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 04/30/2009] [Indexed: 01/09/2023] Open
Abstract
We recently found that induction of the anti-inflammatory SOCS-3 gene by cyclic AMP occurs through novel cyclic AMP-dependent protein kinase-independent mechanisms involving activation of CCAAT/enhancer-binding protein (C/EBP) transcription factors, notably C/EBPbeta, by the cyclic AMP GEF EPAC1 and the Rap1 GTPase. In this study we show that down-regulation of phospholipase (PL) Cepsilon with small interfering RNA or blockade of PLC activity with chemical inhibitors ablates exchange protein directly activated by cyclic AMP (EPAC)-dependent induction of SOCS-3 in COS1 cells. Consistent with this, stimulation of cells with 1-oleoyl-2-acetyl-sn-glycerol and phorbol 12-myristate 13-acetate, both cell-permeable analogues of the PLC product diacylglycerol, are sufficient to induce SOCS-3 expression in a Ca2+-dependent manner. Moreover, the diacylglycerol- and Ca2+-dependent protein kinase C (PKC) isoform PKCalpha becomes activated following cyclic AMP elevation or EPAC stimulation. Conversely, down-regulation of PKC activity with chemical inhibitors or small interfering RNA-mediated depletion of PKCalpha or -delta blocks EPAC-dependent SOCS-3 induction. Using the MEK inhibitor U0126, we found that activation of ERK MAPKs is essential for SOCS-3 induction by either cyclic AMP or PKC. C/EBPbeta is known to be phosphorylated and activated by ERK. Accordingly, we found ERK activation to be essential for cyclic AMP-dependent C/EBP activation and C/EBPbeta-dependent SOCS-3 induction by cyclic AMP and PKC. Moreover, overexpression of a mutant form of C/EBPbeta (T235A), which lacks the ERK phosphorylation site, blocks SOCS-3 induction by cyclic AMP and PKC in a dominant-negative manner. Together, these results indicate that EPAC mediates novel regulatory cross-talk between the cyclic AMP and PKC signaling pathways leading to ERK- and C/EBPbeta-dependent induction of the SOCS-3 gene.
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Affiliation(s)
- Gillian Borland
- From the Division of Molecular and Cellular Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Rebecca J. Bird
- From the Division of Molecular and Cellular Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Timothy M. Palmer
- From the Division of Molecular and Cellular Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Stephen J. Yarwood
- From the Division of Molecular and Cellular Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
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Pan H, Yu J, Zhang L, Carpenter A, Zhu H, Li L, Ma D, Yuan J. A novel small molecule regulator of guanine nucleotide exchange activity of the ADP-ribosylation factor and golgi membrane trafficking. J Biol Chem 2008; 283:31087-96. [PMID: 18799457 PMCID: PMC2576541 DOI: 10.1074/jbc.m806592200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Revised: 09/15/2008] [Indexed: 11/06/2022] Open
Abstract
An image-based phenotypic screen was developed to identify small molecule regulators of intracellular traffic. Using this screen we found that AG1478, a previously known inhibitor of epidermal growth factor receptor, had epidermal growth factor receptor-independent activity in inducing the disassembly of the Golgi in human cells. Similar to brefeldin A (BFA), a known disrupter of the Golgi, AG1478 inhibits the activity of small GTPase ADP-ribosylation factor. Unlike BFA, AG1478 exhibits low cytotoxicity and selectively targets the cis-Golgi without affecting endosomal compartment. We show that AG1478 inhibits GBF1, a large nucleotide exchange factor for the ADP-ribosylation factor, in a Sec7 domain-dependent manner and mimics the phenotype of a GBF1 mutant that has an inactive mutation. The treatment with AG1478 leads to the recruitment of GBF1 to the vesicular-tubular clusters adjacent to the endoplasmic reticulum exit sites, a step only transiently observed previously in the presence of BFA. We propose that the treatment with AG1478 delineates a membrane trafficking intermediate step that depends upon the Sec7 domain.
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Affiliation(s)
- Heling Pan
- State Key Laboratory of Bio-organic & Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
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42
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Sukhanova IF, Solomonova VG, Avdotin PV. [Activators of protein kinase A and Epac proteins enhance the contractile response of the isolated snail (Helix pomatia) heart to serotonin]. Izv Akad Nauk Ser Biol 2008:730-735. [PMID: 19198079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The mechanisms of cAMP action on the contractility of the isolated heart were studied in the snail Helix pomatia. Serotonin is a powerful activator of heart contractility in this animal. Preincubation of the isolated heart ventricle with the activator of protein kinase A (PKA) Sp-8-bromoadenosine-3',5'-cyclic monophosphothioate (200 microM) or the activator of Epac proteins 8-(4-chlorophenylthio)-2'-O-methyladenosine-3',5'-cyclic monophosphate (100 microM) proved to enhance the amplitude of contractions induced by serotonin. Two types of changes in the contractile response were observed: each agent caused either a uniform increase in the amplitude of heart contractions at all concentrations of serotonin or an abrupt increase in the response to the first minimum dose of serotonin. These results indicate that Epac proteins along with PKA are involved in the transmission of cAMP effect on heart contractility.
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Misra UK, Kaczowka S, Pizzo SV. The cAMP-activated GTP exchange factor, Epac1 upregulates plasma membrane and nuclear Akt kinase activities in 8-CPT-2-O-Me-cAMP-stimulated macrophages: Gene silencing of the cAMP-activated GTP exchange Epac1 prevents 8-CPT-2-O-Me-cAMP activation of Akt activity in macrophages. Cell Signal 2008; 20:1459-70. [PMID: 18495429 PMCID: PMC2519236 DOI: 10.1016/j.cellsig.2008.04.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2007] [Revised: 03/11/2008] [Accepted: 04/01/2008] [Indexed: 11/16/2022]
Abstract
cAMP regulates a wide range of processes through its downstream effectors including PKA, and the family of guanine nucleotide exchange factors. Depending on the cell type, cAMP inhibits or stimulates growth and proliferation in a PKA-dependent or independent manner. PKA-independent effects are mediated by PI 3-kinases-Akt signaling and EPAC1 (exchange protein directly activated by cAMP) activation. Recently, we reported PKA-independent activation of the protein kinase Akt as well co-immunoprecipitation of Epac1 with Rap1, p-Akt(Thr-308), and p-Akt(Ser-473) in forskolin-stimulated macrophages. To further probe the role of Epac1 in Akt protein kinase activation and cellular proliferation, we employed the cAMP analog 8-CPT-2-O-Me-cAMP, which selectively binds to Epac1 and triggers Epac1 signaling. We show the association of Epac1 with activated Akt kinases by co-immunoprecipitation and GST-pulldown assays. Silencing Epac1 gene expression by RNA interference significantly reduced levels of Epac1 mRNA, Epac protein, Rap1 GTP, p-ERK1/2, p-B-Raf, p110alpha catalytic subunit of PI 3-kinase, p-PDK, and p-p(70s6k). Silencing Epac1 gene expression by RNA interference also suppressed 8-CPT-2-O-Me-cAMP-upregulated protein and DNA synthesis. Concomitantly, 8-CPT-2-O-Me-cAMP-mediated upregulation of Akt(Thr-308) protein kinase activity and p-Akt(Thr-308) levels was prevented in plasma membranes and nuclei of the cells. In contrast, silencing Epac1 gene expression reduced Akt(Ser-473) kinase activity and p-Akt(Ser-473) levels in plasma membranes, but showed negligible effects on nuclear activity. In conclusion, we show that cAMP-induced Akt kinase activation and cellular proliferation is mediated by Epac1 which appears to function as an accessory protein for Akt activation.
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Affiliation(s)
- Uma K. Misra
- Department of Pathology, Duke University Medical Center, Durham, North Carolina 27710
| | - Steven Kaczowka
- Department of Pathology, Duke University Medical Center, Durham, North Carolina 27710
| | - Salvatore V. Pizzo
- Department of Pathology, Duke University Medical Center, Durham, North Carolina 27710
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Wang L, Liao FL, Zhu L, Peng XB, Sun MX. NtGNL1 is involved in embryonic cell division patterning, root elongation, and pollen tube growth in tobacco. New Phytol 2008; 179:81-93. [PMID: 18399932 DOI: 10.1111/j.1469-8137.2008.02444.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The function of the ARF-GEF family has drawn great attention recently, especially GNOM and GNL1, owing to their important role in plant development. A homolog of GBF was identified in Nicotiana tabacum, named NtGNL1, which is ubiquitously expressed throughout the tobacco life cycle. In NtGNL1 RNAi plants, irregular orientation of cell division and asynchronous cell development during early embryogenesis disrupted the symmetry of the developing embryo. In addition, root growth in transgenic lines was significantly slower than that in wild-type plants, although the structure of the root tip was largely intact. Pollen germination and pollen tube growth were also inhibited in the transgenic lines, and the tip of the pollen tube presented various aberrant morphologies in one of the transgenic lines. The phenotypes of different NtGNL1 RNAi transgenic lines suggest that the NtGNL1 is likely to be involved not only in embryogenesis and postembryonic development, but also in sexual reproduction; thus, NtGNL1 may play multiple and critical roles in plant development.
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Affiliation(s)
| | | | - Li Zhu
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Xiong-Bo Peng
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Meng-Xiang Sun
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan 430072, China
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Abstract
In the present study, we demonstrate that AC5 (type V adenylate cyclase) interacts with Ric8a through directly interacting at its N-terminus. Ric8a was shown to be a GEF (guanine nucleotide exchange factor) for several alpha subunits of heterotrimeric GTP binding proteins (Galpha proteins) in vitro. Selective Galpha targets of Ric8a have not yet been revealed in vivo. An interaction between AC5 and Ric8a was verified by pull-down assays, co-immunoprecipitation analyses, and co-localization in the brain. Expression of Ric8a selectively suppressed AC5 activity. Treating cells with pertussis toxin or expressing a dominant negative Galphai mutant abolished the suppressive effect of Ric8a, suggesting that interaction between the N-terminus of AC5 and a GEF (Ric8a) provides a novel pathway to fine-tune AC5 activity via a Galphai-mediated pathway.
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Affiliation(s)
- Shyi-Chyi Wang
- *Institute of Life Sciences, National Defence Medical Center, Taipei 104, Taiwan
- †Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
| | - Hsing-Lin Lai
- †Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
| | - Yi-Ting Chiu
- †Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
- ‡Institute of Neuroscience, National Yang-Ming University, Taipei 112, Taiwan
| | - Ren Ou
- †Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
- ‡Institute of Neuroscience, National Yang-Ming University, Taipei 112, Taiwan
| | - Chuen-Lin Huang
- §Cardinal Tien Hospital, Hsintien Taipei Hsien 23137, Taiwan
| | - Yijuang Chern
- *Institute of Life Sciences, National Defence Medical Center, Taipei 104, Taiwan
- †Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
- ‡Institute of Neuroscience, National Yang-Ming University, Taipei 112, Taiwan
- To whom correspondence should be addressed (email )
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Mitin N, Betts L, Yohe ME, Der CJ, Sondek J, Rossman KL. Release of autoinhibition of ASEF by APC leads to CDC42 activation and tumor suppression. Nat Struct Mol Biol 2007; 14:814-23. [PMID: 17704816 PMCID: PMC2716141 DOI: 10.1038/nsmb1290] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Accepted: 07/13/2007] [Indexed: 12/19/2022]
Abstract
Autoinhibition of the Rho guanine nucleotide exchange factor ASEF is relieved by interaction with the APC tumor suppressor. Here we show that binding of the armadillo repeats of APC to a 'core APC-binding' (CAB) motif within ASEF, or truncation of the SH3 domain of ASEF, relieves autoinhibition, allowing the specific activation of CDC42. Structural determination of autoinhibited ASEF reveals that the SH3 domain forms an extensive interface with the catalytic DH and PH domains to obstruct binding and activation of CDC42, and the CAB motif is positioned adjacent to the SH3 domain to facilitate activation by APC. In colorectal cancer cell lines, full-length, but not truncated, APC activates CDC42 in an ASEF-dependent manner to suppress anchorage-independent growth. We therefore propose a model in which ASEF acts as a tumor suppressor when activated by APC and inactivation of ASEF by mutation or APC truncation promotes tumorigenesis.
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Affiliation(s)
- Natalia Mitin
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, USA
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Pontow S, Harmon B, Campbell N, Ratner L. Antiviral activity of a Rac GEF inhibitor characterized with a sensitive HIV/SIV fusion assay. Virology 2007; 368:1-6. [PMID: 17640696 PMCID: PMC2174213 DOI: 10.1016/j.virol.2007.06.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2007] [Revised: 02/15/2007] [Accepted: 06/13/2007] [Indexed: 01/14/2023]
Abstract
A virus-dependent fusion assay was utilized to examine the activity of a panel of HIV-1, -2, and SIV isolates of distinct coreceptor phenotypes. This assay allowed identification of entry inhibitors, and characterization of an antagonist of a Rac guanine nucleotide exchange factor, as an inhibitor of HIV-mediated fusion.
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Affiliation(s)
- Suzanne Pontow
- Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, Box 8069, 660 S Euclid Ave, St. Louis, MO 63110, USA
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48
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Abstract
Guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs) regulate the activity of small guanine nucleotide-binding (G) proteins to control cellular functions. In general, GEFs turn on signaling by catalyzing the exchange from G-protein-bound GDP to GTP, whereas GAPs terminate signaling by inducing GTP hydrolysis. GEFs and GAPs are multidomain proteins that are regulated by extracellular signals and localized cues that control cellular events in time and space. Recent evidence suggests that these proteins may be potential therapeutic targets for developing drugs to treat various diseases, including cancer.
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Affiliation(s)
- Johannes L Bos
- Department of Physiological Chemistry and Centre of Biomedical Genetics, UMC Utrecht Universiteitsweg 100, 3584 CG Utrecht, The Netherlands.
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Pechlivanis M, Ringel R, Popkirova B, Kuhlmann J. Prenylation of Ras facilitates hSOS1-promoted nucleotide exchange, upon Ras binding to the regulatory site. Biochemistry 2007; 46:5341-8. [PMID: 17437339 DOI: 10.1021/bi602353k] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The oncoprotein Ras is anchored in lipid membranes due to its C-terminal lipid modification. The ubiquitously expressed Ras nucleotide exchange-factor hSOS1 promotes nucleotide exchange and thus Ras activation. This reaction is enhanced by a positive feedback loop whereby activated Ras binds to an allosteric site of SOS to enhance GEF activity. Here we present biochemical data showing that prenylation of both active site bound and allosterically bound N-Ras is required for efficient hSOS1-promoted nucleotide exchange. Our results indicate that prenyl sensitivity of the allosteric feedback-activation is mediated by the PH domain of hSOS1. Farnesylation of Ras thereby allows hSOS1 to bind even GDP-loaded allosteric regulator to maintain basal hSOS1-activity.
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Affiliation(s)
- Markos Pechlivanis
- Department of Structural Biology, Max-Planck-Institut für molekulare Physiologie, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
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Birukova AA, Alekseeva E, Mikaelyan A, Birukov KG. HGF attenuates thrombin-induced endothelial permeability by Tiam1-mediated activation of the Rac pathway and by Tiam1/Rac-dependent inhibition of the Rho pathway. FASEB J 2007; 21:2776-86. [PMID: 17428964 DOI: 10.1096/fj.06-7660com] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Reorganization of the endothelial cell (EC) cytoskeleton and cell adhesive complexes provides a structural basis for increased vascular permeability implicated in the pathogenesis of many diseases, including asthma, sepsis, and acute respiratory distress syndrome (ARDS). We have recently described the barrier-protective effects of hepatocyte growth factor (HGF) on the human pulmonary EC. In the present study, we explored the involvement of Rac-GTPase and Rac-specific nucleotide exchange factor Tiam1 in the mechanisms of EC barrier protection by HGF. HGF protected EC monolayers from thrombin-induced hyperpermeability, disruption of intercellular junctions, and formation of stress fibers and paracellular gaps by inhibiting thrombin-induced activation of Rho GTPase, Rho association with nucleotide exchange factor p115-RhoGEF, and myosin light chain phosphorylation, which was opposed by stimulation of Rac-dependent signaling. The pharmacological Rac inhibitor or silencing RNA (siRNA) based depletion of either Rac or Tiam1 significantly attenuated HGF-induced peripheral translocation of Rac effector cortactin, cortical actin ring formation, and EC barrier enhancement. Moreover, Tiam1 knockdown using the siRNA approach, attenuated the protective effect of HGF against thrombin-induced activation of Rho signaling, monolayer disruption, and EC hyperpermeability. This study demonstrates the Tiam1/Rac-dependent mechanism of HGF-induced EC barrier protection and provides novel mechanistic insights into regulation of EC permeability via dynamic interactions between Rho- and Tiam1/Rac-mediated pathways.
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Affiliation(s)
- Anna A Birukova
- Section of Pulmonary and Critical Medicine, Department of Medicine, University of Chicago, 929 East 57th St., CIS Bldg., W410, Chicago, IL 60637, USA.
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