1
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Zeng Y, Guo Z, Hu Z, Liu M, Chen Y, Chen S, Peng B, Zhang P, Wu Z, Luo H, Zhong F, Jiang K, Lu Y, Yuan G, He S. FGD1 exhibits oncogenic properties in hepatocellular carcinoma through regulating cell morphology, autophagy and mitochondrial function. Biomed Pharmacother 2020; 125:110029. [PMID: 32106378 DOI: 10.1016/j.biopha.2020.110029] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Revised: 02/12/2020] [Accepted: 02/17/2020] [Indexed: 12/15/2022] Open
Abstract
Faciogenital Dysplasia 1 (FGD1) has been involved in a variety of biological processes, including cytoskeleton restructuring, cell morphology, cell cycle progression, and cell polarity. Abnormal expression of FGD1 was also identified in several types of cancers, indicating its critical role in the development of cancers. However, little is known about the role of FGD1 in hepatocellular carcinoma (HCC). In this study, the expression of FGD1 in HCC was mined with the RNA sequencing data from the cancer genome atlas. By over-expressing or knocking down of FGD1, the effects of FGD1 on the malignant behavior of HCC were evaluated both in vitro and in vivo. We find that FGD1 is up-regulated in HCC and correlated with the development and prognosis of HCC. By over-expressing or knocking down of FGD1, the effects of FGD1 on the malignant behavior of HCC were evaluated both in vitro and in vivo. Knockdown of FGD1 remarkably inhibits the malignant behaviors and causes morphological disorder of pseudopodia, autophagy inhibition and mitochondrial dyfunction in HCC cells. Further investigation shows that Cdc42, a Rho GTPase, plays a role in these processes. Overexpression of FGD1 significantly promotes the oncogenic properties of HCC cells. Collectively, these findings reveal that FGD1 exhibits oncogenic properties in HCC through regulating cell morphology, autophagy and mitochondrial function, suggesting that FGD1 may serve as a potential therapeutic target for HCC.
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Affiliation(s)
- Yonglian Zeng
- Division of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, Guangxi, China; Basic Medical School of Guangxi Medical University, Nanning, 530021, Guangxi, China
| | - Zhenya Guo
- Division of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, Guangxi, China
| | - Zhigao Hu
- Division of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, Guangxi, China
| | - Mingjiang Liu
- Division of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, Guangxi, China
| | - Yubing Chen
- Division of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, Guangxi, China
| | - Shilian Chen
- Division of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, Guangxi, China
| | - Bo Peng
- Division of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, Guangxi, China
| | - Peng Zhang
- Division of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, Guangxi, China
| | - Zhan Wu
- Division of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, Guangxi, China
| | - Hongliang Luo
- Division of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, Guangxi, China
| | - Fudi Zhong
- Division of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, Guangxi, China
| | - Keqing Jiang
- Division of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, Guangxi, China
| | - Yi Lu
- School of Medicine, Southern University of Science and Technology, 1088 Xili Xueyuan Avenue, Shenzhen, 518055, Guangdong, China.
| | - Guandou Yuan
- Division of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, Guangxi, China.
| | - Songqing He
- Division of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, Guangxi, China.
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Wu W, Jing D, Meng Z, Hu B, Zhong B, Deng X, Jin X, Shao Z. FGD1 promotes tumor progression and regulates tumor immune response in osteosarcoma via inhibiting PTEN activity. Am J Cancer Res 2020; 10:2859-2871. [PMID: 32194840 PMCID: PMC7052884 DOI: 10.7150/thno.41279] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 01/11/2020] [Indexed: 12/26/2022] Open
Abstract
Rationale: Mesenchymal cell-derived osteosarcoma is a rare malignant bone tumor affecting children and adolescents. PTEN down-regulation or function-loss mutation is associated with the aggressive of osteosarcoma. Explicating the regulatory mechanism of PTEN might highlight new targets for improving the survival rate of osteosarcoma patients. Methods: The clinical relevance of FGD1 was examined by the TCGA data set, Western blotting and immunohistochemistry of osteosarcoma microarray slides. Functional assays, such as the MTS assay, colony formation assay and xenografts, were used to determine the biological role of FGD1 in osteosarcoma. The protein-protein interaction between FGD1 and PTEN was detected via co-immunoprecipitation. The relationship between FGD1 and PD-L1 was examined by Western blot analysis, RT-qPCR and immunohistochemistry. Results: In this study, analysis of the TCGA data set of sarcomas revealed that FGD1 was over-expressed with the highest P values. Then, we demonstrated that FGD1 was also abnormally up-regulated in osteosarcoma with unfavorable prognosis. Aberrant expressed FGD1 promoted the osteosarcoma tumor cell proliferation and invasion. Moreover, we found that FGD1 was participated in activating PI3K/AKT signaling pathway by interacting with PTEN. Finally, we showed that FGD1 was capable of regulating the tumor immune response via the PTEN/PD-L1 axis in osteosarcoma. Conclusions: Our data suggested that abnormally over-expressed FGD1 functions as an oncogenic protein to promote osteosarcoma progression through inhibiting PTEN activity and activating PI3K/AKT signaling. Notably, FGD1 increased PD-L1 expression in a PTEN dependent manner and modulated the sensitivity of immune checkpoint-based immunotherapy in osteosarcoma. Thus, FGD1 might be a potential target for improving the survival rate of osteosarcomas.
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3
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Egorov M, Polishchuk R. Identification of CDC42 Effectors Operating in FGD1-Dependent Trafficking at the Golgi. Front Cell Dev Biol 2019; 7:7. [PMID: 30778386 PMCID: PMC6369352 DOI: 10.3389/fcell.2019.00007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 01/16/2019] [Indexed: 11/17/2022] Open
Abstract
Loss of function mutations in the FGD1 gene cause a rare X-linked disease, faciogenital dysplasia (FGDY, also known as Aarskog-Skott syndrome), which is associated with bone and urogenital abnormalities. The FGD1 gene encodes à CDC42-specific guanine nucleotide exchange factor. The mutations are frequently located in the DH module of FGD1 preventing its transformation to the active form. We previously reported that Golgi-associated FGD1 regulates post-Golgi transport of some conventional and bone-specific proteins in a CDC42-dependent manner. However, the downstream targets of FGD1/CDC42 signaling that operate to support transport from the Golgi remain elusive. Here, we demonstrate that Golgi-localized CDC42 effectors might be involved in FGD1-mediated post-Golgi transport, probably through coordination of Golgi membrane and cytoskeleton dynamics. Overexpression of effector-specific CDC42 mutants (exhibiting preferential affinities for PAK1, IQGAP1, N-WASP, or PAR6) only partially rescue membrane trafficking in FGD1-deficient cells, indicating that the orchestrated activities of several downstream targets of CDC42 are required to support FGD1-mediated export from the Golgi. Our findings provide new insights into understanding the molecular mechanisms behind FGD1/CDC42-dependent transport events and uncover new targets whose potential might be explored for correction of membrane trafficking in FGDY.
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Affiliation(s)
- Mikhail Egorov
- Telethon Institute of Genetics and Medicine, Naples, Italy
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4
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Genot E, Daubon T, Sorrentino V, Buccione R. FGD1 as a central regulator of extracellular matrix remodelling--lessons from faciogenital dysplasia. J Cell Sci 2012; 125:3265-70. [PMID: 22854039 DOI: 10.1242/jcs.093419] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Disabling mutations in the FGD1 gene cause faciogenital dysplasia (also known as Aarskog-Scott syndrome), a human X-linked developmental disorder that results in disproportionately short stature, facial, skeletal and urogenital anomalies, and in a number of cases, mild mental retardation. FGD1 encodes the guanine nucleotide exchange factor FGD1, which is specific for the Rho GTPase cell division cycle 42 (CDC42). CDC42 controls cytoskeleton-dependent membrane rearrangements, transcriptional activation, secretory membrane trafficking, G1 transition during the cell cycle and tumorigenic transformation. The cellular mechanisms by which FGD1 mutations lead to the hallmark skeletal deformations of faciogenital dysplasia remain unclear, but the pathology of the disease, as well as some recent discoveries, clearly show that the protein is involved in the regulation of bone development. Two recent studies unveiled new potential functions of FGD1, in particular, its involvement in the regulation of the formation and function of invadopodia and podosomes, which are cellular structures devoted to degradation of the extracellular matrix in tumour and endothelial cells. Here, we discuss the hypothesis that FGD1 might be an important regulator of events controlling extracellular matrix remodelling and possibly cell invasion in physiological and pathological settings. Additionally, we focus on how studying the cell biology of FGD1 might help us to connect the dots that link CDC42 signalling with remodelling of the extracellular matrix (ECM) in physiology and complex diseases, while, at the same time, furthering our understanding of the pathogenesis of faciogenital dysplasia.
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Affiliation(s)
- Elisabeth Genot
- Université de Bordeaux, Physiopathologie du Cancer du Foie, U1053, F-33000 Bordeaux, France
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5
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Gao L, Gorski JL, Chen CS. The Cdc42 guanine nucleotide exchange factor FGD1 regulates osteogenesis in human mesenchymal stem cells. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 178:969-74. [PMID: 21356349 DOI: 10.1016/j.ajpath.2010.11.051] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Revised: 10/22/2010] [Accepted: 11/15/2010] [Indexed: 10/18/2022]
Abstract
Loss of function mutations in FGD1 result in faciogenital dysplasia, an X-linked human developmental disorder that adversely affects the formation of multiple skeletal structures. FGD1 encodes a guanine nucleotide exchange factor that specifically activates Cdc42, a Rho family small GTPase that regulates a variety of cellular behaviors. We have found that FGD1 is expressed in human mesenchymal stem cells (hMSCs) isolated from adult bone marrow. hMSCs are multipotent cells that can differentiate into many cell types, including fibroblasts, osteoblasts, adipocytes, and chondrocytes, and are thought to play a role in maintaining musculoskeletal tissues throughout life. We demonstrate an active role of FGD1 in osteogenic differentiation of hMSCs. During osteogenic differentiation of hMSCs in culture, we observed up-regulation of both FGD1 expression and Cdc42 activity. Activating FGD1/Cdc42 signaling by overexpression of either FGD1 or constitutively active Cdc42 promoted hMSC osteogenesis, while inhibiting Cdc42 signaling by either dominant negative mutants of FGD1 or Cdc42 suppressed osteogenesis. These results demonstrate an important role for FGD1/Cdc42 signaling in hMSC osteogenesis and suggest that the defects in bone remodeling in faciogenital dysplasia may persist throughout adult life and serve as a potential pathway that may be targeted for enhancing bone regeneration.
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Affiliation(s)
- Lin Gao
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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6
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Cejudo-Martin P, Courtneidge SA. Podosomal proteins as causes of human syndromes: a role in craniofacial development? Genesis 2011; 49:209-21. [PMID: 21328520 DOI: 10.1002/dvg.20732] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 01/21/2011] [Accepted: 02/02/2011] [Indexed: 01/12/2023]
Abstract
Podosomes and invadopodia are actin-rich protrusions of the plasma membrane important for matrix degradation and cell migration. Most of the information in this field has been obtained in cancer cells, where the presence of invadopodia has been related to increased invasiveness and metastatic potential. The importance of the related podosome structure in other pathological or physiological processes that require cell invasion is relatively unexplored. Recent evidence indicates that essential components of podosomes are responsible for several human syndromes, some of which are characterized by serious developmental defects involving the craniofacial area, skeleton and heart, and very poor prognosis. Here we will review them and discuss the possible role of podosomes as a player in correct embryo development.
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Affiliation(s)
- Pilar Cejudo-Martin
- Tumor Microenvironment Program, Sanford-Burnham Medical Research Institute, La Jolla, California 92037, USA
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7
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Oshima T, Fujino T, Ando K, Hayakawa M. Role of FGD1, a Cdc42 Guanine Nucleotide Exchange Factor, in Epidermal Growth Factor-Stimulated c-Jun NH2-Terminal Kinase Activation and Cell Migration. Biol Pharm Bull 2011; 34:54-60. [DOI: 10.1248/bpb.34.54] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Toshiyuki Oshima
- School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
| | - Tomofumi Fujino
- School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
| | - Ken Ando
- School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
| | - Makio Hayakawa
- School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
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8
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Ayala I, Giacchetti G, Caldieri G, Attanasio F, Mariggiò S, Tetè S, Polishchuk R, Castronovo V, Buccione R. Faciogenital Dysplasia Protein Fgd1 Regulates Invadopodia Biogenesis and Extracellular Matrix Degradation and Is Up-regulated in Prostate and Breast Cancer. Cancer Res 2009; 69:747-52. [DOI: 10.1158/0008-5472.can-08-1980] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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9
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Nakanishi H, Takai Y. Frabin and other related Cdc42-specific guanine nucleotide exchange factors couple the actin cytoskeleton with the plasma membrane. J Cell Mol Med 2008; 12:1169-76. [PMID: 18410521 PMCID: PMC3865658 DOI: 10.1111/j.1582-4934.2008.00345.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Frabin, together with, at least, FGD1, FGD2, FGD3 and FGD1-related Cdc42-GEF (FRG), is a member of a family of Cdc42-specific gua-nine nucleotide exchange factors (GEFs). These proteins have multiple phosphoinositide-binding domains, including two pleckstrin homology (PH) domains and an FYVE or FERM domain. It is likely that they couple the actin cytoskeleton with the plasma membrane. Frabin associates with a specific actin structure(s) and induces the direct activation of Cdc42 in the vicinity of this structure(s), resulting in actin reorganization. Furthermore, frabin associates with a specific membrane structure(s) and induces the indirect activation of Rac in the vicinity of this structure(s), resulting in the reorganization of the actin cytoskeleton. This reorganization of the actin cytoskeleton induces cell shape changes such as the formation of filopodia and lamellipodia.
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Affiliation(s)
- Hiroyuki Nakanishi
- Department of Molecular Pharmacology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
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10
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Falasca M, Maffucci T. Emerging roles of phosphatidylinositol 3-monophosphate as a dynamic lipid second messenger. Arch Physiol Biochem 2006; 112:274-84. [PMID: 17178602 DOI: 10.1080/13813450601094664] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The lipid products of phosphoinositide 3-kinase (PI3K) are involved in many cellular responses such as proliferation, migration and survival. Disregulation of PI3K-activated pathways is implicated in different disease including diabetes and cancer. Among the different products of PI3Ks, phosphatidylinositol-3,4,5-trisphosphate (PtdIns-3,4,5-P3) has a well established role in signal transduction whereas the monophosphate phosphatidylinositol-3-phosphate (PtdIns-3-P) has been considered for a long time just a cellular component confined in endosomal structures. Only recently several evidence have indicated that PtdIns-3-P can also act as a dynamic intracellular second messenger. The role of PtdIns-3-P as mediator of crucial intracellular signals is therefore just beginning to be appreciated. Here we review some of the latest evidence showing that pools of PtdIns-3-P can be generated upon cellular stimulation in compartments different from the "classical" endosomal region. We describe several proteins that can be targets in mediating signals deriving from such stimulated PtdIns-3-P pools. In addition we describe the potential mechanism of switching on and off such signals. Taken together all this evidence suggest a novel, key role for PtdIns-3-P in signal transduction.
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Affiliation(s)
- Marco Falasca
- Centre for Cardiovascular Biology and Medicine, Division of Medicine, University College London, 5 University Street, London, WC1E 6JJ, UK.
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11
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Kutateladze TG. Phosphatidylinositol 3-phosphate recognition and membrane docking by the FYVE domain. Biochim Biophys Acta Mol Cell Biol Lipids 2006; 1761:868-77. [PMID: 16644267 PMCID: PMC2740714 DOI: 10.1016/j.bbalip.2006.03.011] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2006] [Revised: 03/07/2006] [Accepted: 03/09/2006] [Indexed: 12/17/2022]
Abstract
The FYVE domain is a small zinc binding module that recognizes phosphatidylinositol 3-phosphate [PtdIns(3)P], a phospholipid enriched in membranes of early endosomes and other endocytic vesicles. It is usually present as a single module or rarely as a tandem repeat in eukaryotic proteins involved in a variety of biological processes including endo- and exocytosis, membrane trafficking and phosphoinositide metabolism. A number of FYVE domain-containing proteins are recruited to endocytic membranes through the specific interaction of their FYVE domains with PtdIns(3)P. Structures and PtdIns(3)P binding modes of several FYVE domains have recently been characterized, shedding light on the molecular basis underlying multiple cellular functions of these proteins. Here, structural and functional aspects and the current mechanism of the multivalent membrane anchoring by monomeric or dimeric FYVE domain are reviewed. This mechanism involves stereospecific recognition of PtdIns(3)P that is facilitated by non-specific electrostatic contacts and modulated by the histidine switch, and is accompanied by hydrophobic insertion. Contributions of each component to the FYVE domain specificity and affinity for PtdIns(3)P-containing membranes are discussed.
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Affiliation(s)
- Tatiana G Kutateladze
- Department of Pharmacology, University of Colorado Health Sciences Center, 12801 East 17th Avenue, Aurora, CO 80045, USA.
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12
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Daly RJ. Cortactin signalling and dynamic actin networks. Biochem J 2005; 382:13-25. [PMID: 15186216 PMCID: PMC1133910 DOI: 10.1042/bj20040737] [Citation(s) in RCA: 239] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2004] [Revised: 06/08/2004] [Accepted: 06/09/2004] [Indexed: 12/29/2022]
Abstract
Cortactin was first identified over a decade ago, and its initial characterization as both an F-actin binding protein and v-Src substrate suggested that it was likely to be a key regulator of actin rearrangements in response to tyrosine kinase signalling. The recent discovery that cortactin binds and activates the actin related protein (Arp)2/3 complex, and thus regulates the formation of branched actin networks, together with the identification of multiple protein targets of the cortactin SH3 domain, have revealed diverse cellular roles for this protein. This article reviews current knowledge regarding the role of cortactin in signalling to the actin cytoskeleton in the context of these developments.
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Affiliation(s)
- Roger J Daly
- Cancer Research Program, Garvan Institute of Medical Research, 384 Victoria St, Sydney, NSW 2010, Australia.
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13
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Pendaries C, Tronchère H, Racaud-Sultan C, Gaits-Iacovoni F, Coronas S, Manenti S, Gratacap MP, Plantavid M, Payrastre B. Emerging roles of phosphatidylinositol monophosphates in cellular signaling and trafficking. ACTA ACUST UNITED AC 2005; 45:201-14. [PMID: 16023705 DOI: 10.1016/j.advenzreg.2005.02.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The phosphoinositide metabolism that is highly controlled by a set of kinases, phosphatases and phospholipases leads to the production of several second messengers playing critical roles in intracellular signal transduction mechanisms. Recent discoveries have unraveled unexpected roles for the three phosphatidylinositol monophosphates, PtdIns(3)P, PtdIns(4)P and PtdIns(5)P, that appear now as important lipid messengers able to specifically interact with proteins. The formation of functionally distinct and independently regulated pools of phosphatidylinositol monophosphates probably contributes to the specificity of the interactions with their targets. The relative enrichment of organelles in a particular species of phosphoinositides (i.e. PtdIns(3)P in endosomes, PtdIns(4)P in Golgi and PtdIns(4,5)P2 in plasma membrane) suggests the notion of lipid-defined organelle identity. PtdIns(3)P is now clearly involved in vesicular trafficking by interaction with a set of FYVE domain-containing proteins both in yeast and in mammals. PtdIns(4)P, which until now was only considered as a precursor for PtdIns(4,5)P2, appears as a regulator on its own, by recruiting a set of proteins to the trans-Golgi network. PtdIns(5)P, the most recently discovered inositol lipid, is also emerging as a potentially important signaling molecule.
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Affiliation(s)
- Caroline Pendaries
- Inserm U563-CPTP, IFR 30, Department of Oncogenesis and signaling in haematopoïetic cells, CHU Purpan, 31024 Toulouse, France
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14
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van Galen EJM, Ramakers GJA. Rho proteins, mental retardation and the neurobiological basis of intelligence. PROGRESS IN BRAIN RESEARCH 2005; 147:295-317. [PMID: 15581714 DOI: 10.1016/s0079-6123(04)47022-8] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
For several decades it has been known that mental retardation is associated with abnormalities in dendrites and dendritic spines. The recent cloning of eight genes which cause nonspecific mental retardation when mutated, provides an important insight into the cellular mechanisms that result in the dendritic abnormalities underlying mental retardation. Three of the encoded proteins, oligophrenin1, PAK3 and alphaPix, interact directly with Rho GTPases. Rho GTPases are key signaling proteins which integrate extracellular and intracellular signals to orchestrate coordinated changes in the actin cytoskeleton, essential for directed neurite outgrowth and the generation/rearrangement of synaptic connectivity. Although many details of the cell biology of Rho signaling in the CNS are as yet unclear, a picture is unfolding showing how mutations that cause abnormal Rho signaling result in abnormal neuronal connectivity which gives rise to deficient cognitive functioning in humans.
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Affiliation(s)
- Elly J M van Galen
- Neurons and Networks Research Group, Netherlands Institute for Brain Research, Graduate School Neurosciences Amsterdam, Meibergdreef 33, 1105 AZ Amsterdam ZO, The Netherlands
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15
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Palmby TR, Abe K, Karnoub AE, Der CJ. Vav Transformation Requires Activation of Multiple GTPases and Regulation of Gene Expression. Mol Cancer Res 2004. [DOI: 10.1158/1541-7786.702.2.12] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Although Vav can act as a guanine nucleotide exchange factor for RhoA, Rac1, and Cdc42, its transforming activity has been ascribed primarily to its ability to activate Rac1. However, because activated Vav, but not Rac-specific guanine nucleotide exchange factors, exhibits very potent focus-forming transforming activity when assayed in NIH 3T3 cells, Vav transforming activity must also involve activation of Rac-independent pathways. In this study, we determined the involvement of other Rho family proteins and their signaling pathways in Vav transformation. We found that RhoA, Rac1, and Cdc42 functions are all required for Vav transforming activity. Furthermore, we determined that Vav activation of nuclear factor-κB and the Jun NH2-terminal kinase mitogen-activated protein kinase (MAPK) is necessary for full transformation by Vav, whereas p38 MAPK does not seem to play an important role. We also determined that Vav is a weak activator of Elk-1 via a Ras- and MAPK/extracellular signal-regulated kinase kinase–dependent pathway, and this activity was essential for Vav transformation. Thus, we conclude that full Vav transforming activation is mediated by the activation of multiple small GTPases and their subsequent activation of signaling pathways that regulate changes in gene expression. Because Vav is activated by the epidermal growth factor receptor and other tyrosine kinases involved in cancer development, defining the role of aberrant Vav signaling may identify activities of receptor tyrosine kinases important for human oncogenesis.
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Affiliation(s)
- Todd R. Palmby
- Department of Pharmacology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Karon Abe
- Department of Pharmacology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Antoine E. Karnoub
- Department of Pharmacology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Channing J. Der
- Department of Pharmacology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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16
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Subtil A, Wyplosz B, Balañá ME, Dautry-Varsat A. Analysis of Chlamydia caviae entry sites and involvement of Cdc42 and Rac activity. J Cell Sci 2004; 117:3923-33. [PMID: 15265988 DOI: 10.1242/jcs.01247] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
In epithelial cells, endocytic activity is mostly dedicated to nutrient and macromolecule uptake. To invade these cells, Chlamydiaceae, like other pathogens, have evolved strategies that utilise the existing endocytic machineries and signalling pathways, but little is known about the host cell molecules involved. In this report, we show that within five minutes of infection of HeLa cells by Chlamydia caviae GPIC strain several events take place in the immediate vicinity of invasive bacteria: GM1-containing microdomains cluster, tyrosine-phosphorylated proteins accumulate, and intense actin polymerization occurs. We show that actin polymerization is controlled by the small GTPases Cdc42 and Rac, which become activated upon infection. Expression of dominant negative forms of these GTPases inhibits C. caviae entry and leads to abnormal actin polymerization. In contrast, the small GTPase Rho does not seem essential for bacterial entry. Finally, phosphatidylinositol 3-kinase activity is also required for internalization of C. caviae, probably downstream of the other molecular events reported here. We present the first scheme of the events occurring at the sites of invasion of epithelial cells by a member of the Chlamydiaceae family.
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Affiliation(s)
- Agathe Subtil
- Unité de Biologie des Interactions Cellulaires, Institut Pasteur, CNRS URA 2582, 25 rue du Docteur Roux, 75015 Paris, France
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17
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Kim K, Hou P, Gorski JL, Cooper JA. Effect of Fgd1 on cortactin in Arp2/3 complex-mediated actin assembly. Biochemistry 2004; 43:2422-7. [PMID: 14992579 PMCID: PMC2366894 DOI: 10.1021/bi036173t] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mutations in faciogenital dysplasia protein (Fgd1) result in the human disease faciogenital dysplasia (FGDY). Fgd1 contains a RhoGEF domain specific for Cdc42. Fgd1 also contains a Src homology (SH3) binding domain (SH3-BD) that binds directly to the SH3 domain of cortactin, which promotes actin assembly by actin-related protein (Arp)2/3 complex. Here, we report the effect of ligation of cortactin's SH3 domain by the Fgd1 SH3-BD on actin polymerization in vitro. Glutathione S-transferase (GST)-fused Fgd1 SH3-BD enhanced the ability of cortactin to stimulate Arp2/3-mediated actin polymerization. However, a synthetic peptide containing only the SH3-BD sequence had no effect. The SH3-BD peptide bound to cortactin and inhibited the effect of GST-Fgd1 SH3-BD, suggesting that GST dimerization was responsible for the stimulating effect of GST-Fgd1 SH3-BD. When GST-Fgd1 SH3-BD was prepared as a heterodimer with a control GST fusion protein (GST-Pac1), no stimulatory effect on actin polymerization was observed. In addition, when cortactin was dimerized via its N-terminus, away from the C-terminal SH3 domain, actin polymerization with Arp2/3 complex increased markedly, compared to free cortactin. Thus, cortactin ligated by Fgd1 is fully active, indicating that the cell can use Fgd1 to target actin assembly. Moreover, if Fgd1 is multimerized, then cortactin's activity should be enhanced. Fgd1 and cortactin may participate as scaffolds and signal transducers in a positive feedback cycle to promote actin assembly at the cell cortex.
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Affiliation(s)
| | | | | | - John A. Cooper
- Corresponding author: John A Cooper, Campus Box 8228, 660 S. Euclid Ave., St Louis, MO 63110. Phone (314) 362-3964. Fax (314) 362-0098. E-mail:
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18
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Shapiro P. Ras-MAP kinase signaling pathways and control of cell proliferation: relevance to cancer therapy. Crit Rev Clin Lab Sci 2002; 39:285-330. [PMID: 12385501 DOI: 10.1080/10408360290795538] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The mitogen-activated protein (MAP) kinase pathways represent several families of signal transduction cascades that mediate information provided by extracellular stimuli. MAP kinase pathways regulate a wide range of physiological responses, including cell proliferation, apoptosis, cell differentiation, and tissue development. Constitutive activation of MAP kinase proteins in experimental models has been shown to cause cell transformation and is implicated in tumorigenesis. Of clinical importance, MAP kinase pathways are regulated by Ras G-proteins, which are found to be mutated and constitutively active in approximately 30% of all human cancers. Thus, a major goal in the treatment of cancer is the development of specific compounds that target Ras and critical downstream signaling proteins responsible for uncontrolled cell growth. A variety of biochemical, molecular, and structural approaches have been used to develop drug compounds that target signaling proteins important for MAP kinase pathway activation. These compounds have been useful tools for identifying the mechanisms of MAP kinase pathway signaling and hold promise for clinical use. This review will present an overview of the major proteins involved in Ras and MAP kinase signaling pathways and their function in regulating cell cycle events and proliferation. In addition, some of the relevant compounds that have been developed to inhibit the activities of these proteins and MAP kinase signaling are discussed.
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Affiliation(s)
- Paul Shapiro
- Department of Pharmaceutical Sciences, University of Maryland-School of Pharmacy, Baltimore 21201, USA
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19
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Schmidt A, Hall A. Guanine nucleotide exchange factors for Rho GTPases: turning on the switch. Genes Dev 2002; 16:1587-609. [PMID: 12101119 DOI: 10.1101/gad.1003302] [Citation(s) in RCA: 917] [Impact Index Per Article: 41.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Anja Schmidt
- MRC Laboratory for Molecular Cell Biology, Cancer Research UK Oncogene and Signal Transduction Group, University College London, London WC1E 6BT, UK.
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20
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Abstract
The functionality and efficacy of Rho GTPase signaling is pivotal for a plethora of biological processes. Due to the integral nature of these molecules, the dysregulation of their activities can result in diverse aberrant phenotypes. Dysregulation can, as will be described below, be based on an altered signaling strength on the level of a specific regulator or that of the respective GTPase itself. Alternatively, effector pathways emanating from a specific Rho GTPase may be under- or overactivated. In this review, we address the role of the Rho-type GTPases as a subfamily of the Ras-superfamily of small GTP-binding proteins in the development of various disease phenotypes. The steadily growing list of genetic alterations that specifically impinge on proper Rho GTPase function corresponds to pathological categories such as cancer progression, mental disabilities and a group of quite diverse and unrelated disorders. We will provide an overview of disease-rendering mutations in genes that have been positively correlated with Rho GTPase signaling and will discuss the cellular and molecular mechanisms that may be affected by them.
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Affiliation(s)
- Benjamin Boettner
- Cold Spring Harbor Laboratories, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA
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21
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Abstract
The FYVE zinc finger domain is conserved from yeast (five proteins) to man (27 proteins). It functions in the membrane recruitment of cytosolic proteins by binding to phosphatidylinositol 3-phosphate (PI3P), which is found mainly on endosomes. Here we review recent work that sheds light on the targeting of FYVE finger proteins to PI3P-containing membranes, and how these proteins serve to regulate multiple cellular functions.
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Affiliation(s)
- Harald Stenmark
- Department of Biochemistry, The Norwegian Radium Hospital, Oslo, Norway.
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22
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Abstract
The Dbl family of guanine nucleotide exchange factors are multifunctional molecules that transduce diverse intracellular signals leading to the activation of Rho GTPases. The tandem Dbl-homology and pleckstrin-homology domains shared by all members of this family represent the structural module responsible for catalyzing the GDP-GTP exchange reaction of Rho proteins. Recent progress in genomic, genetic, structural and biochemical studies has implicated Dbl family members in diverse biological processes, including growth and development, skeletal muscle formation, neuronal axon guidance and tissue organization. The detailed pictures of their autoregulation, agonist-controlled activation and mechanism of interaction with Rho GTPase substrates, have begun to emerge.
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Affiliation(s)
- Y Zheng
- Dept of Molecular Sciences, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
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23
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Krugmann S, Jordens I, Gevaert K, Driessens M, Vandekerckhove J, Hall A. Cdc42 induces filopodia by promoting the formation of an IRSp53:Mena complex. Curr Biol 2001; 11:1645-55. [PMID: 11696321 DOI: 10.1016/s0960-9822(01)00506-1] [Citation(s) in RCA: 302] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND The Rho GTPases Rho, Rac, and Cdc42 regulate the organization of the actin cytoskeleton by interacting with multiple, distinct downstream effector proteins. Cdc42 controls the formation of actin bundle-containing filopodia at the cellular periphery. The molecular mechanism for this remains as yet unclear. RESULTS We report here that Cdc42 interacts with IRSp53/BAP2 alpha, an SH3 domain-containing scaffold protein, at a partial CRIB motif and that an N-terminal fragment of IRSp53 binds, via an intramolecular interaction, to the CRIB motif-containing central region. Overexpression of IRSp53 in fibroblasts leads to the formation of filopodia, and both this and Cdc42-induced filopodia are inhibited by expression of the N-terminal IRSp53 fragment. Using affinity chromatography, we have identified Mena, an Ena/VASP family member, as interacting with the SH3 domain of IRSp53. Mena and IRSp53 act synergistically to promote filopodia formation. CONCLUSION We conclude that the interaction of Cdc42 with the partial CRIB motif of IRSp53 relieves an intramolecular, autoinhibitory interaction with the N terminus, allowing the recruitment of Mena to the IRSp53 SH3 domain. This IRSp53:Mena complex initiates actin filament assembly into filopodia.
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Affiliation(s)
- S Krugmann
- MRC Laboratory for Molecular Cell Biology and Cell Biology Unit, CRC Oncogene and Signal Transduction Group, University College London, Gower Street, London WC1E 6BT, United Kingdom
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24
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Suzuki N, Buechner M, Nishiwaki K, Hall DH, Nakanishi H, Takai Y, Hisamoto N, Matsumoto K. A putative GDP-GTP exchange factor is required for development of the excretory cell in Caenorhabditis elegans. EMBO Rep 2001; 2:530-5. [PMID: 11415987 PMCID: PMC1083904 DOI: 10.1093/embo-reports/kve110] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The Caenorhabditis elegans excretory cell extends tubular processes, called canals, along the basolateral surface of the epidermis. Mutations in the exc-5 gene cause tubulocystic defects in this canal. Ultrastructural analysis suggests that exc-5 is required for the proper placement of cytoskeletal elements at the apical epithelial surface. exc-5 encodes a protein homologous to guanine nucleotide exchange factors and contains motif architecture similar to that of FGD1, which is responsible for faciogenital dysplasia. exc-5 interacts genetically with mig-2, which encodes Rho GTPase. These results suggest that EXC-5 controls the structural organization of the excretory canal by regulating Rho family GTPase activities.
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Affiliation(s)
- N Suzuki
- Department of Molecular Biology, Graduate school of Science, Nagoya University and CREST, Japan
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25
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Abstract
A milestone in Huntington's disease (HD) research is represented by the identification of the causative gene. With the genetics at hand, a series of transgenic cellular and animal models has been developed, which has greatly contributed to understanding of HD. All these models are described in this review, and are compared to each other, along with the information they have generated. Although the mechanism by which progressive loss of striatal neurons occurs in HD remains uncertain, hypotheses on mutant huntingtin toxicity involve impaired vescicular trafficking, transcriptional dysregulation, and/or activation of apoptotic pathways. The development of inducible HD mice has shown that neurodegeneration in HD may be at least partially blocked. Although traditionally considered a "gain-of-function" disease, the recent finding that normal huntingtin has an important role in neuronal survival suggests that loss of function of the normal protein might contribute to HD as well, also discloseing new perspectives on the therapeutical approach to the pathology.
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Affiliation(s)
- S Sipione
- Department of Pharmacological Sciences, University of Milano, Center of Excellence on Neurodegenerative Diseases, Italy
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26
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Abstract
E-cadherin is a transmembrane protein that mediates Ca(2+)-dependent cell-cell adhesion. Cdc42, a member of the Rho family of small GTPases, participates in cytoskeletal rearrangement and cell cycle progression. Recent evidence reveals that members of the Rho family modulate E-cadherin function. To further examine the role of Cdc42 in E-cadherin-mediated cell-cell adhesion, we developed an assay for active Cdc42 using the GTPase-binding domain of the Wiskott-Aldrich syndrome protein. Initiation of E-cadherin-mediated cell-cell attachment significantly increased in a time-dependent manner the amount of active Cdc42 in MCF-7 epithelial cell lysates. By contrast, Cdc42 activity was not increased under identical conditions in MCF-7 cells incubated with anti-E-cadherin antibodies nor in MDA-MB-231 (E-cadherin negative) epithelial cells. By fusing the Wiskott-Aldrich syndrome protein/GTPase-binding domain to a green fluorescent protein, activation of endogenous Cdc42 by E-cadherin was demonstrated in live cells. These data indicate that E-cadherin activates Cdc42, demonstrating bi-directional interactions between the Rho- and E-cadherin signaling pathways.
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Affiliation(s)
- S H Kim
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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27
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Ono Y, Nakanishi H, Nishimura M, Kakizaki M, Takahashi K, Miyahara M, Satoh-Horikawa K, Mandai K, Takai Y. Two actions of frabin: direct activation of Cdc42 and indirect activation of Rac. Oncogene 2000; 19:3050-8. [PMID: 10871857 DOI: 10.1038/sj.onc.1203631] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Frabin is an actin filament-binding protein which shows GDP/GTP exchange activity specific for Cdc42 small G protein and induces filopodium-like microspike formation and c-Jun N-terminal kinase (JNK) activation presumably through the activation of Cdc42. Frabin has one actin filament-binding (FAB) domain, one Dbl homology (DH) domain, first pleckstrin homology (PH) domain adjacent to the DH domain, one cysteine-rich FYVE domain, and second PH domain from the N-terminus to the C-terminus in this order. Different domains of frabin are involved in the microspike formation and the JNK activation, and the association of frabin with the actin cytoskeleton through the FAB domain is necessary for the microspike formation, but not for the JNK activation. We have found here that frabin induces the formation of not only filopodium-like microspikes but also lamellipodium-like structures in NIH3T3 and L fibroblasts. We have analysed the mechanism of frabin in these two actions and found that frabin induces filopodium-like microspike formation through the direct activation of Cdc42 and lamellipodium-like structure formation through the Cdc42-independent indirect activation of Rac small G protein. The FAB domain of frabin in addition to the DH domain and the first PH domain is necessary for the filopodium-like microspike formation, but not for the lamellipodium-like structure formation. The FYVE domain and the second PH domain in addition to the DH domain and the first PH domain are necessary for the lamellipodium-like structure formation. We show here these two actions of frabin in the regulation of cell morphology.
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Affiliation(s)
- Y Ono
- Takai Biotimer Project, ERATO, Japan Science and Technology Corporation, c/o JCR Pharmaceuticals Co. Ltd., 2-2-10 Murotani, Nishi-ku, Kobe 651-2241, Japan
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28
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Umikawa M, Obaishi H, Nakanishi H, Satoh-Horikawa K, Takahashi K, Hotta I, Matsuura Y, Takai Y. Association of frabin with the actin cytoskeleton is essential for microspike formation through activation of Cdc42 small G protein. J Biol Chem 1999; 274:25197-200. [PMID: 10464238 DOI: 10.1074/jbc.274.36.25197] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have recently isolated a novel actin filament-binding protein, named frabin. Frabin has one actin filament-binding domain (ABD), one Dbl homology domain (DHD), first pleckstrin homology domains (PHD) adjacent to DHD, one cysteine rich-domain (CRD), and second PHD from the N terminus to the C terminus in this order. Full-length frabin induces microspike formation and c-Jun N-terminal kinase (JNK) activation. We found here that the fragment of frabin containing DHD and first PHD stimulated guanine nucleotide exchange of Cdc42Hs small G protein, but not that of RhoA or Rac1 small G protein. However, this fragment of frabin did not induce microspike formation, and ABD was additionally necessary for microspike formation. Frabin having ABD was associated with the actin cytoskeleton, whereas frabin lacking ABD was diffusely distributed in the cytoplasm. In contrast, ABD was not necessary for JNK activation but CRD and second PHD were additionally necessary for this activation. These results indicate that the association of frabin with the actin cytoskeleton is essential for microspike formation but not for JNK activation and that different domains of frabin are involved in microspike formation and JNK activation through Cdc42 activation.
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Affiliation(s)
- M Umikawa
- Department of Molecular Biology and Biochemistry, Osaka University Medical School, Suita 565-0871, Japan
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29
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Gaullier JM, Simonsen A, D'Arrigo A, Bremnes B, Stenmark H. FYVE finger proteins as effectors of phosphatidylinositol 3-phosphate. Chem Phys Lipids 1999; 98:87-94. [PMID: 10358931 DOI: 10.1016/s0009-3084(99)00021-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Phosphatidylinositol 3-phosphate (PtdIns(3)P), generated via the phosphorylation of phosphatidylinositol by phosphatidylinositol 3-kinase (PI 3-kinase), plays an essential role in intracellular membrane traffic. The underlying mechanism is still not understood in detail, but the recent identification of the FYVE finger as a protein domain that binds specifically to PtdIns(3)P provides a number of potential effectors for PtdIns(3)P. The FYVE finger (named after the first letter of the four proteins containing it; Fab1p, YOTB, Vac1p and EEA1) is a double-zinc binding domain that is conserved in more than 30 proteins from yeast to mammals. It is found in several proteins involved in intracellular traffic, and FYVE finger mutations that affect zinc binding are associated with the loss of function of several of these proteins. The interaction of FYVE fingers with PtdIns(3)P may serve three alternative functions: First, to recruit cytosolic FYVE finger proteins to PtdIns(3)P-containing membranes (in concert with accessory molecules); second, to enrich for membrane bound FYVE finger proteins into PtdIns(3)P containing microdomains within the membrane; and third, to modulate the activity of membrane bound FYVE finger proteins.
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Affiliation(s)
- J M Gaullier
- Department of Biochemistry, Norwegian Radium Hospital, Oslo, Norway
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30
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Abstract
Cdc42p is an essential GTPase that belongs to the Rho/Rac subfamily of Ras-like GTPases. These proteins act as molecular switches by responding to exogenous and/or endogenous signals and relaying those signals to activate downstream components of a biological pathway. The 11 current members of the Cdc42p family display between 75 and 100% amino acid identity and are functional as well as structural homologs. Cdc42p transduces signals to the actin cytoskeleton to initiate and maintain polarized gorwth and to mitogen-activated protein morphogenesis. In the budding yeast Saccharomyces cerevisiae, Cdc42p plays an important role in multiple actin-dependent morphogenetic events such as bud emergence, mating-projection formation, and pseudohyphal growth. In mammalian cells, Cdc42p regulates a variety of actin-dependent events and induces the JNK/SAPK protein kinase cascade, which leads to the activation of transcription factors within the nucleus. Cdc42p mediates these processes through interactions with a myriad of downstream effectors, whose number and regulation we are just starting to understand. In addition, Cdc42p has been implicated in a number of human diseases through interactions with its regulators and downstream effectors. While much is known about Cdc42p structure and functional interactions, little is known about the mechanism(s) by which it transduces signals within the cell. Future research should focus on this question as well as on the detailed analysis of the interactions of Cdc42p with its regulators and downstream effectors.
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Affiliation(s)
- D I Johnson
- Department of Microbiology & Molecular Genetics and the Markey Center for Molecular Genetics, University of Vermont, Burlington, Vermont 05405,
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31
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Abstract
The importance for the Rho GTPases Rho, Rac, and Cdc42 for the heterogeneity of the actin cytoskeleton is well documented. However, there is now an emerging view that they also have important roles in signaling pathways that control gene transcription, cell cycle regulation, apoptosis, and tumor progression. Furthermore, not only has the number of pathways which involve Rho GTPases increased, the number of Rho family members and their regulating proteins has increased considerably. This raises important questions regarding how specificity is achieved in cell signaling employing Rho GTPases.
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Affiliation(s)
- P Aspenström
- Ludwig Institute for Cancer Research, Uppsala, S-751 24, Sweden.
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32
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Caron E, Hall A. Identification of two distinct mechanisms of phagocytosis controlled by different Rho GTPases. Science 1998; 282:1717-21. [PMID: 9831565 DOI: 10.1126/science.282.5394.1717] [Citation(s) in RCA: 730] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The complement and immunoglobulin receptors are the major phagocytic receptors involved during infection. However, only immunoglobulin-dependent uptake results in a respiratory burst and an inflammatory response in macrophages. Rho guanosine triphosphatases (molecular switches that control the organization of the actin cytoskeleton) were found to be essential for both types of phagocytosis. Two distinct mechanisms of phagocytosis were identified: Type I, used by the immunoglobulin receptor, is mediated by Cdc42 and Rac, and type II, used by the complement receptor, is mediated by Rho. These results suggest a molecular basis for the different biological consequences that are associated with phagocytosis.
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Affiliation(s)
- E Caron
- Medical Research Council Laboratory for Molecular Cell Biology, Cancer Research Campaign Oncogene and Signal Transduction Group, and Department of Biochemistry, University College London, Gower Street, London WC1E 6BT, UK
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