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Hindle A, Singh SP, Pradeepkiran JA, Bose C, Vijayan M, Kshirsagar S, Sawant NA, Reddy PH. Rlip76: An Unexplored Player in Neurodegeneration and Alzheimer’s Disease? Int J Mol Sci 2022; 23:ijms23116098. [PMID: 35682775 PMCID: PMC9181721 DOI: 10.3390/ijms23116098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 02/01/2023] Open
Abstract
Alzheimer’s disease (AD) is a progressive neurodegenerative disorder and is the most common cause of dementia in older people. AD is associated with the loss of synapses, oxidative stress, mitochondrial structural and functional abnormalities, microRNA deregulation, inflammatory responses, neuronal loss, accumulation of amyloid-beta (Aβ) and phosphorylated tau (p-tau). AD occurs in two forms: early onset, familial AD and late-onset, sporadic AD. Causal factors are still unknown for a vast majority of AD patients. Genetic polymorphisms are proposed to contribute to late-onset AD via age-dependent increases in oxidative stress and mitochondrial abnormalities. Recent research from our lab revealed that reduced levels of Rlip76 induce oxidative stress, mitochondrial dysfunction and synaptic damage, leading to molecular and behavioral phenotypes resembling late-onset AD. Rlip76 is a multifunctional 76 kDa protein encoded by the RALBP1 gene, located on chromosome 18. Rlip is a stress-protective ATPase of the mercapturic acid pathway that couples clathrin-dependent endocytosis with the efflux of glutathione–electrophile conjugates. Rlip is evolutionarily highly conserved across species and is ubiquitously expressed in all tissues, including AD-affected brain regions, the cerebral cortex and hippocampus, where highly active neuronal metabolisms render the cells highly susceptible to intracellular oxidative damage. In the current article, we summarize molecular and cellular features of Rlip and how depleted Rlip may exacerbate oxidative stress, mitochondrial dysfunction and synaptic damage in AD. We also discuss the possible role of Rlip in aspects of learning and memory via axonal growth, dendritic remodeling, and receptor regulation. We conclude with a discussion of the potential for the contribution of genetic polymorphisms in Rlip to AD progression and the potential for Rlip-based therapies.
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Affiliation(s)
- Ashly Hindle
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA; (A.H.); (S.P.S.); (J.A.P.); (C.B.); (M.V.); (S.K.); (N.A.S.)
| | - Sharda P. Singh
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA; (A.H.); (S.P.S.); (J.A.P.); (C.B.); (M.V.); (S.K.); (N.A.S.)
| | - Jangampalli Adi Pradeepkiran
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA; (A.H.); (S.P.S.); (J.A.P.); (C.B.); (M.V.); (S.K.); (N.A.S.)
| | - Chhanda Bose
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA; (A.H.); (S.P.S.); (J.A.P.); (C.B.); (M.V.); (S.K.); (N.A.S.)
| | - Murali Vijayan
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA; (A.H.); (S.P.S.); (J.A.P.); (C.B.); (M.V.); (S.K.); (N.A.S.)
| | - Sudhir Kshirsagar
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA; (A.H.); (S.P.S.); (J.A.P.); (C.B.); (M.V.); (S.K.); (N.A.S.)
| | - Neha A. Sawant
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA; (A.H.); (S.P.S.); (J.A.P.); (C.B.); (M.V.); (S.K.); (N.A.S.)
| | - P. Hemachandra Reddy
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA; (A.H.); (S.P.S.); (J.A.P.); (C.B.); (M.V.); (S.K.); (N.A.S.)
- Neuroscience & Pharmacology, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
- Neurology, Departments of School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
- Public Health Department of Graduate School of Biomedical Sciences, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
- Department of Speech, Language and Hearing Sciences, School Health Professions, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
- Correspondence:
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A potential function of RLIP76 in the ovarian corpus luteum. J Ovarian Res 2019; 12:34. [PMID: 30999946 PMCID: PMC6474048 DOI: 10.1186/s13048-019-0510-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 04/08/2019] [Indexed: 11/24/2022] Open
Abstract
Ral interacting protein of 76 kDa (RLIP76) is multifunctional protein localized and distributed in the plasma membrane, cytosol, and nucleus of the cell. In tumorigenesis, RLIP76 emerges as a common feature for the solid tumor growth. RLIP76 is ubiquitously expressed in various tissues including the ovary. Interestingly, the similar physiological events in obtaining an adequate supply of nutrient by gaining access to the host vascular system are required either for corpus luteum formation or tumor development. In addition, the identical angiogenesis modulators were found in neoplastic and normal ovaries. Our previous study involving RLIP76−/− mice implanted with melanoma or carcinoma cell conclusively demonstrated that RLIP76 is necessary for angiogenesis and neovascularization of primary solid tumors. RLIP76 plays an essential role in tumor angiogenesis through the regulation of pro-angiogenic factors such as vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1 (HIF-1). In certain previous studies, those pro-angiogenic factors were found significantly to be upregulated during the corpus luteum formation. To that, the following review will discuss the likelihood of RLIP76 role in ovarian corpus luteum.
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Lee S, Wurtzel JGT, Goldfinger LE. The RLIP76 N-terminus binds ARNO to regulate PI 3-kinase, Arf6 and Rac signaling, cell spreading and migration. Biochem Biophys Res Commun 2014; 454:560-5. [PMID: 25450693 DOI: 10.1016/j.bbrc.2014.10.114] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 10/24/2014] [Indexed: 11/29/2022]
Abstract
RLIP76 is a multifunctional protein involved in tumor growth and angiogenesis, and a promising therapeutic target in many cancers. RLIP76 harbors docking sites for many proteins, and we have found that it interacts with ARNO, a guanine nucleotide exchange factor for Arf6, and that RLIP76 regulates activation of Rac1 via Arf6, and regulates cell spreading and migration in an ARNO and Arf6-dependent manner. Here we show that ARNO interacts with the RLIP76 N-terminal domain, and this domain was required for RLIP76-dependent cell spreading and migration. We identified two sites in the RLIP76 N-terminus with differential effects on ARNO binding and downstream signaling: Ser29/Ser30 and Ser62. Ser29/30 mutation to Alanine inhibited ARNO interaction and was sufficient to block RLIP76-dependent cell spreading and migration, as well as RLIP76-dependent Arf6 activation. In contrast, RLIP76(S62A) interacted with ARNO and supported Arf6 activation. However, both sets of mutations blocked Rac1 activation. RLIP76-mediated Rac and Arf6 activation required PI3K activity. S29/30A mutations inhibited RLIP76-dependent PI3K activation, but S62A mutation did not. Together these results show that ARNO interaction with the RLIP76 N-terminus regulates cell spreading and motility via PI3K and Arf6, independent of RLIP76 control of Rac.
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Affiliation(s)
- Seunghyung Lee
- Department of Anatomy & Cell Biology and The Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Jeremy G T Wurtzel
- Department of Anatomy & Cell Biology and The Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Lawrence E Goldfinger
- Department of Anatomy & Cell Biology and The Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA; Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
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Sahu M, Sharma R, Yadav S, Wakamiya M, Chaudhary P, Awasthi S, Awasthi YC. Lens specific RLIP76 transgenic mice show a phenotype similar to microphthalmia. Exp Eye Res 2013; 118:125-34. [PMID: 24188744 DOI: 10.1016/j.exer.2013.10.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 10/18/2013] [Accepted: 10/24/2013] [Indexed: 10/26/2022]
Abstract
RALBP1/RLIP76 is a ubiquitously expressed protein, involved in promotion and regulation of functions initiated by Ral and R-Ras small GTPases. Presence of multiple domains in its structure enables RLIP76 to be involved in a number of physiological processes such as endocytosis, exocytosis, mitochondrial fission, actin cytoskeleton remodeling, and transport of exogenous and endogenous toxicants. Previously, we have established that RLIP76 provides protection to ocular tissues against oxidative stress by transporting the glutathione-conjugates of the toxic, electrophilic products of lipid peroxidation generated during oxidative stress. Therefore, we developed lens specific RLIP76 transgenic mice (lensRLIP76 Tg) to elucidate the role of RLIP76 in protection against oxidative stress, but these transgenic mice showed impaired lens development and a phenotype with small eyes similar to that observed in microphthalmia. These findings prompted us to investigate the mechanisms via which RLIP76 affects lens and eye development. In the present study, we report engineering of lensRLIP76 Tg mice, characterization of the associated phenotype, and the possible molecular mechanisms that lead to the impaired development of eye and lens in these mice. The results of microarray array analysis indicate that the genes involved in pathways for G-Protein signaling, actin cytoskeleton reorganization, endocytosis, and apoptosis are affected in these transgenic mice. The expression of transcription factors, Pax6, Hsf1, and Hsf4b known to be involved in lens development is down regulated in the lens of these Tg mice. However, the expression of heat shock proteins (Hsps), the downstream targets of Hsfs, is differentially affected in the lens showing down regulation of Hsp27, Hsp40, up regulation of Hsp60, and no effect on Hsp70 and Hsp90 expression. The disruption in the organization of actin cytoskeleton of these Tg mice was associated with the inhibition of the activation of Cdc42 and down regulation of cofilin phosphorylation. These mice may provide useful animal model for elucidating the mechanisms of lens development, and etiology of microphthalmia.
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Affiliation(s)
- Mukesh Sahu
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX 76107, USA
| | - Rajendra Sharma
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX 76107, USA
| | - Sushma Yadav
- Division of Diabetes, Endocrinology & Metabolism, Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute, City of Hope, National Medical Center, Duarte, CA 91010, USA
| | - Maki Wakamiya
- Department of Neurology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Pankaj Chaudhary
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX 76107, USA
| | - Sanjay Awasthi
- Division of Diabetes, Endocrinology & Metabolism, Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute, City of Hope, National Medical Center, Duarte, CA 91010, USA
| | - Yogesh C Awasthi
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX 76107, USA.
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Liggi S, Drakakis G, Hendry AE, Hanson KM, Brewerton SC, Wheeler GN, Bodkin MJ, Evans DA, Bender A. Extensions to In Silico Bioactivity Predictions Using Pathway Annotations and Differential Pharmacology Analysis: Application toXenopus laevisPhenotypic Readouts. Mol Inform 2013; 32:1009-24. [DOI: 10.1002/minf.201300102] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 08/06/2013] [Indexed: 12/20/2022]
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Goldfinger LE, Lee S. Emerging treatments in lung cancer - targeting the RLIP76 molecular transporter. LUNG CANCER-TARGETS AND THERAPY 2013; 2013:61-69. [PMID: 25419163 PMCID: PMC4240306 DOI: 10.2147/lctt.s53672] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Multidrug resistance in lung cancer cells is a significant obstacle in the treatment of lung cancer. Resistance to chemotherapeutic agents is often the result of efflux of the drugs from cancer cells, mediated by adenosine triphosphate (ATP)-dependent drug transport across the plasma membrane. Thus, identifying molecular targets in the cancer cell transport machinery could be a key factor in successful combinatorial therapy, along with chemotherapeutic drugs. The transport protein Ral-interacting protein of 76 kDa (RLIP76), also known as Ral-binding protein 1 (RalBP1), is a highly promising target for lung cancer treatment. RLIP76 is an ATP-dependent non-ATP-binding cassette (ABC) transporter, responsible for the major transport function in many cells, including many cancer cell lines, causing efflux of glutathione-electrophile conjugates of both endogenous metabolites and environmental toxins. RLIP76 is expressed in most human tissues, and is overexpressed in non-small-cell lung cancer cell lines and in many tumor types. The blockade of RLIP76 by various approaches has been shown to increase the sensitivity to radiation and chemotherapeutic drugs, and leads to apoptosis in cells. In xenograft tumor models in mice, RLIP76 blockade or depletion results in complete and sustained regression across many cancer cell types, including lung cancer cells. In addition to its transport function, RLIP76 has many other cellular and physiological functions based on its domain structure, which includes a unique Ral-binding domain and a Rho GTPase activating protein (RhoGAP)-catalytic domain as well as docking sites for multiple signaling proteins. As a Ral effector, RhoGAP, and adapter protein, RLIP76 has been shown to play important roles in endocytosis, mitochondrial fission, cell spreading and migration, actin dynamics during gastrulation, and Ras-induced tumorigenesis. Additionally, RLIP76 is also important for stromal cell function in tumors, as it was recently shown to be required for efficient endothelial cell function and angiogenesis in solid tumors. However, RLIP76 knockout mice are viable, and blockade effects appear to be selective for implanted tumors in mice, suggesting the possibility that RLIP76-targeting drugs may be successful in clinical trials. In this review, we outline the many cellular and physiological functions of RLIP76 in normal and cancer cells, and discuss the potential for RLIP76-based therapeutics in lung cancer treatment.
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Affiliation(s)
- Lawrence E Goldfinger
- Department of Anatomy and Cell Biology, The Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA, USA ; Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Seunghyung Lee
- Department of Anatomy and Cell Biology, The Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA, USA
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Lee S, Wurtzel JGT, Singhal SS, Awasthi S, Goldfinger LE. RALBP1/RLIP76 depletion in mice suppresses tumor growth by inhibiting tumor neovascularization. Cancer Res 2012; 72:5165-73. [PMID: 22902412 DOI: 10.1158/0008-5472.can-12-0468] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RalBP1/RLIP76 is a widely expressed multifunctional protein that binds the Ral and R-Ras small GTPases. In the mouse, RLIP76 is nonessential but its depletion or blockade promotes tumorigenesis and heightens the sensitivity of normal and tumor cells to radiation and cytotoxic drugs. However, its pathobiologic functions, which support tumorigenesis, are not well understood. Here, we show that RLIP76 is required for angiogenesis and for efficient neovascularization of primary solid tumors. Tumor growth from implanted melanoma or carcinoma cells was blunted in RLIP76(-/-) mice. An X-ray microcomputed tomography-based method to model tumor vascular structures revealed defects in both the extent and form of tumor angiogenesis in RLIP76(-/-) mice. Specifically, tumor vascular volumes were diminished and vessels were fewer in number, shorter, and narrower in RLIP76(-/-) mice than in wild-type mice. Moreover, we found that angiogenesis was blunted in mutant mice in the absence of tumor cells, with endothelial cells isolated from these animals exhibiting defects in migration, proliferation, and cord formation in vitro. Taken together, our results establish that RLIP76 is required for efficient endothelial cell function and angiogenesis in solid tumors.
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Affiliation(s)
- Seunghyung Lee
- Authors' Affiliations: Department of Anatomy & Cell Biology and The Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
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Identification and characterization of the RLIP/RALBP1 interacting protein Xreps1 in Xenopus laevis early development. PLoS One 2012; 7:e33193. [PMID: 22413001 PMCID: PMC3297634 DOI: 10.1371/journal.pone.0033193] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Accepted: 02/06/2012] [Indexed: 11/19/2022] Open
Abstract
Background The FGF/Ras/Ral/RLIP pathway is required for the gastrulation process during the early development of vertebrates. The Ral Interacting Protein (RLIP also known as RalBP1) interacts with GTP-bound Ral proteins. RLIP/RalBP1 is a modular protein capable of participating in many cellular functions. Methodology/Principal Findings To investigate the role of RLIP in early development, a two-hybrid screening using a library of maternal cDNAs of the amphibian Xenopus laevis was performed. Xreps1 was isolated as a partner of RLIP/RalBP1 and its function was studied. The mutual interacting domains of Xreps1 and Xenopus RLIP (XRLIP) were identified. Xreps1 expressed in vivo, or synthesized in vitro, interacts with in vitro expressed XRLIP. Interestingly, targeting of Xreps1 or the Xreps1-binding domain of XRLIP (XRLIP(469–636)) to the plasma membrane through their fusion to the CAAX sequence induces a hyperpigmentation phenotype of the embryo. This hyperpigmented phenotype induced by XRLIP(469–636)-CAAX can be rescued by co-expression of a deletion mutant of Xreps1 restricted to the RLIP-binding domain (Xreps1(RLIP-BD)) but not by co-expression of a cDNA coding for a longer form of Xreps1. Conclusion/Significance We demonstrate here that RLIP/RalBP1, an effector of Ral involved in receptor-mediated endocytosis and in the regulation of actin dynamics during embryonic development, also interacts with Reps1. Although these two proteins are present early during embryonic development, they are active only at the end of gastrulation. Our results suggest that the interaction between RLIP and Reps1 is negatively controlled during the cleavage stage of development, which is characterized by rapid mitosis. Later in development, Reps1 is required for the normal function of the ectodermic cell, and its targeting into the plasma membrane affects the stability of the ectoderm.
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Fillatre J, Delacour D, Van Hove L, Bagarre T, Houssin N, Soulika M, Veitia RA, Moreau J. Dynamics of the subcellular localization of RalBP1/RLIP through the cell cycle: the role of targeting signals and of protein-protein interactions. FASEB J 2012; 26:2164-74. [PMID: 22319010 DOI: 10.1096/fj.11-196451] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The small G protein Ras regulates many cell processes, such as gene expression, proliferation, apoptosis, and cell differentiation. Its mutations are associated with one-third of all cancers. Ras functions are mediated, at least in part, by Ral proteins and their downstream effector the Ral-binding protein 1 (RalBP1). RalBP1 is involved in endocytosis and in regulating the dynamics of the actin cytoskeleton. It also regulates early development since it is required for the completion of gastrulation in Xenopus laevis. RalBP1 has also been reported to be the main transporter of glutathione electrophiles, and it is involved in multidrug resistance. Such a variety of functions could be explained by a differential regulation of RalBP1 localization. In this study, we have detected endogenous RalBP1 in the nucleus of interphasic cells. This nuclear targeting is mediated by nuclear localization sequences that map to the N-terminal third of the protein. Moreover, in X. laevis embryos, a C-terminal coiled-coil sequence mediates RalBP1 retention in the nucleus. We have also observed RalBP1 at the level of the actin cytoskeleton, a localization that depends on interaction of the protein with active Ral. During mitosis RalBP1 also associates with the mitotic spindle and the centrosome, a localization that could be negatively regulated by active Ral. Finally, we demonstrate the presence of post-transcriptional and post-translational isoforms of RalBP1 lacking the Ral-binding domain, which opens new possibilities for the existence of Ral-independent functions.
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Affiliation(s)
- Jonathan Fillatre
- Mécanismes Moléculaires du Développement, Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité. 15, rue Hélène Brion. 75205 Paris, France
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Novokhatska O, Dergai M, Houssin N, Tsyba L, Moreau J, Rynditch A. Intersectin 2 nucleotide exchange factor regulates Cdc42 activity during Xenopus early development. Biochem Biophys Res Commun 2011; 408:663-8. [PMID: 21530493 DOI: 10.1016/j.bbrc.2011.04.081] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Accepted: 04/18/2011] [Indexed: 11/28/2022]
Abstract
Intersectin 2 (ITSN2) is an evolutionarily conserved scaffold protein involved in endocytic internalization, regulation of actin cytoskeleton and epithelial morphogenesis. Recent studies of different Itsn-deficient organisms revealed that this gene is essential for the functioning of the nervous system and for organism viability. Here we report investigations on a possible role of the ITSN2 long isoform in the early embryonic development of Xenopus laevis. In vertebrates, alternative splicing generates several alternatively spliced isoforms of ITSN2. To date the long splice variant of ITSN2 (ITSN2-L) has been reported only for mammals. We show that transcripts of ITSN2-L can be detected in Xenopus embryos from the first cleavage onwards. Overexpression of functional domains of ITSN2-L in embryos resulted in aberrant phenotypes. The strongest phenotype was produced by the C-terminal extension of ITSN2-L. Embryos displayed hyperpigmentation and gastrulation failure that were incompatible with survival. The C-terminus of ITSN2-L includes the DH-PH tandem, a nucleotide exchange factor for the small GTPase Cdc42 and the C2 domain. Further investigations revealed that the DH-PH tandem was responsible for the development of the phenotype affecting the actin cytoskeleton in embryos. Observed developmental defects depended on Cdc42. The effect of expression of the constitutively active GTPase strongly resembled that of the DH-PH tandem. The dominant negative Cdc42 partially rescued developmental defects induced by the expression of the DH-PH tandem. Thus, our data indicate that the ITSN2 exchange factor regulates the activity of Cdc42 during embryo development affecting actin cytoskeleton in Xenopus embryos.
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Affiliation(s)
- Olga Novokhatska
- Department of Functional Genomics, Institute of Molecular Biology and Genetics, National Academy of Sciences-Ukraine, 150 Zabolotnogo Street, Kyiv, Ukraine.
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Coon BG, Burgner J, Camonis JH, Aguilar RC. The epsin family of endocytic adaptors promotes fibrosarcoma migration and invasion. J Biol Chem 2010; 285:33073-33081. [PMID: 20709745 DOI: 10.1074/jbc.m110.124123] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Abnormalities in the process of endocytosis are classically linked to malignant transformation through the deficient down-regulation of signaling receptors. The present study describes a non-classical mechanism that does not require internalization by which endocytic proteins affect cell migration and basement membrane invasion. Specifically, we found that the endocytic adaptor epsin binds and regulates the biological properties of the signaling molecule RalBP1 (Ral-binding protein 1). Epsin interacted with the N terminus of RalBP1 via its characteristic epsin N-terminal homology (ENTH) domain. A combination of siRNA-mediated knock-down and transfection of siRNA-resistant constructs in fibrosarcoma cells demonstrated that impairment of the epsin-RalBP1 interaction led to cell migration and basement membrane invasion defects. We found the ENTH domain was necessary and sufficient to sustain normal cell migration and invasion. Because all the epsin endocytic motifs reside in the C-terminal part of the molecule, these results suggest that this novel regulatory circuit does not require endocytosis. In addition, cells depleted of epsin-RalBP1 complex displayed deficient activation of Rac1 and Arf6 suggesting a signaling function for this novel interaction. Further, overexpression of either epsin or RalBP1 enhanced migration and invasion of fibrosarcoma cells. Collectively, our results indicate that epsin regulates RalBP1 function in Rac1- and Arf6-dependent pathways to ultimately affect cell migration and invasion. We propose that the observed up-regulation of both epsin and RalBP1 in certain cancers contributes to their invasive characteristics.
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Affiliation(s)
- Brian G Coon
- From the Department of Biological Sciences, Purdue Center for Cancer Research, West Lafayette, Indiana 47907
| | - John Burgner
- Bindley Biosciences Center, Purdue University, West Lafayette, Indiana 47907
| | - Jacques H Camonis
- Institut Curie, 75248 Paris Cedex 05, France; Inserm U830, 75248 Paris Cedex 05, France
| | - R Claudio Aguilar
- From the Department of Biological Sciences, Purdue Center for Cancer Research, West Lafayette, Indiana 47907.
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Abstract
The migration of single cells and epithelial sheets is of great importance for gastrulation and organ formation in developing embryos and, if misregulated, can have dire consequences e.g. during cancer metastasis. A keystone of cell migration is the regulation of adhesive contacts, which are dynamically assembled and disassembled via endocytosis. Here, we discuss some of the basic concepts about the function of endocytic trafficking during cell migration: transport of integrins from the cell rear to the leading edge in fibroblasts; confinement of signalling to the front of single cells by endocytic transport of growth factors; regulation of movement coherence in multicellular sheets by cadherin turnover; and shaping of extracellular chemokine gradients. Taken together, endocytosis enables migrating cells and tissues to dynamically modulate their adhesion and signalling, allowing them to efficiently migrate through their extracellular environment.
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Affiliation(s)
- Florian Ulrich
- Skirball Institute of Biomolecular Medicine, New York, USA
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13
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Boissel L, Houssin N, Chikh A, Rynditch A, Van Hove L, Moreau J. Recruitment of Cdc42 through the GAP domain of RLIP participates in remodeling of the actin cytoskeleton and is involved in Xenopus gastrulation. Dev Biol 2007; 312:331-43. [DOI: 10.1016/j.ydbio.2007.09.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2007] [Revised: 09/07/2007] [Accepted: 09/17/2007] [Indexed: 12/23/2022]
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Oxford G, Smith SC, Hampton G, Theodorescu D. Expression profiling of Ral-depleted bladder cancer cells identifies RREB-1 as a novel transcriptional Ral effector. Oncogene 2007; 26:7143-52. [PMID: 17496927 DOI: 10.1038/sj.onc.1210521] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Although the monomeric GTPases RalA and RalB have been shown to regulate a variety of transcription factors, little is known regarding the differences or similarities in transcriptional programs regulated by RalA compared to RalB. Further, the association of these transcriptional pathways to human carcinogenesis and progression remains unclear. Here, we studied the role of RalA and/or RalB in transcriptional regulation by combining short interfering RNA depletion of Ral with gene expression profiling via microarray in the human bladder cancer cell line, UMUC-3. A large number of genes were found to be similarly modulated in cells with RalA and RalB depletion, suggesting that RalA and RalB impinge on overlapping transcriptional signaling pathways. However, smaller sets of genes were modulated by depletion of RalA or RalB, indicating that these closely related proteins also regulate nonoverlapping transcriptional pathways. Computational analysis of upstream sequences of genes modulated by Ral depletion identified Ras-responsive element-binding protein (RREB)-1, as a putative Ral transcriptional target, which we verified experimentally. Importantly, as a group, Ral-regulated probe sets identified here were disproportionally represented among those differentially expressed as a function of human bladder transformation. Taken together, these data strongly suggest that Ral family members mediate both common and specific transcriptional programs that are associated with human cancer and identify RREB-1 as a novel transcriptional effector of Ral.
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Affiliation(s)
- G Oxford
- Department of Molecular Physiology and Biological Physics, Health Sciences Center, University of Virginia, Charlottesville, VA 22908, USA
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Goldfinger LE, Ptak C, Jeffery ED, Shabanowitz J, Hunt DF, Ginsberg MH. RLIP76 (RalBP1) is an R-Ras effector that mediates adhesion-dependent Rac activation and cell migration. ACTA ACUST UNITED AC 2006; 174:877-88. [PMID: 16966426 PMCID: PMC2064341 DOI: 10.1083/jcb.200603111] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The Ras family of small GTPases regulates cell proliferation, spreading, migration and apoptosis, and malignant transformation by binding to several protein effectors. One such GTPase, R-Ras, plays distinct roles in each of these processes, but to date, identified R-Ras effectors were shared with other Ras family members (e.g., H-Ras). We utilized a new database of Ras-interacting proteins to identify RLIP76 (RalBP1) as a novel R-Ras effector. RLIP76 binds directly to R-Ras in a GTP-dependent manner, but does not physically associate with the closely related paralogues H-Ras and Rap1A. RLIP76 is required for adhesion-induced Rac activation and the resulting cell spreading and migration, as well as for the ability of R-Ras to enhance these functions. RLIP76 regulates Rac activity through the adhesion-induced activation of Arf6 GTPase and activation of Arf6 bypasses the requirement for RLIP76 in Rac activation and cell spreading. Thus, we identify a novel R-Ras effector, RLIP76, which links R-Ras to adhesion-induced Rac activation through a GTPase cascade that mediates cell spreading and migration.
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Affiliation(s)
- Lawrence E Goldfinger
- Division of Rheumatology, Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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Gaffré M, Dupré A, Valuckaite R, Suziedelis K, Jessus C, Haccard O. Deciphering the H-Ras pathway in Xenopus oocyte. Oncogene 2006; 25:5155-62. [PMID: 16607282 DOI: 10.1038/sj.onc.1209523] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Xenopus oocytes are arrested in prophase of the first meiotic division. In response to progesterone, they re-enter meiosis and arrest again in metaphase of the second meiotic division. This process, called meiotic maturation, is under the control of the Cyclin B-Cdc2 complex, M phase promoting factor (MPF). Injection of a constitutively active Xenopus H-Ras protein activates MPF, suggesting that Ras proteins could be implicated in the progesterone transduction pathway. The aim of this study was (1) to elucidate the pathway triggered by H-Ras leading to MPF activation in Xenopus oocytes and (2) to investigate whether endogenous H-Ras is involved in the physiological process of meiotic maturation. We generated three constitutively active double mutants, each of them recruiting a single effector in mammalian cells, mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K) or RalGDS. Our results show that the activation of a PI3K-related enzyme is crucial for H-Ras-induced MPF activation, whereas the recruitment of either MAPK or RalGDS is not. However, although the H-Ras/PI3K pathway is functional in Xenopus oocytes, it is not the physiological transducer of progesterone responsible for meiotic resumption.
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Affiliation(s)
- M Gaffré
- Laboratoire de Biologie du Développement, UMR-CNRS 7622, Université Pierre et Marie Curie, Paris, France
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