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Carotenuto R, Pallotta MM, Tussellino M, Fogliano C. Xenopus laevis (Daudin, 1802) as a Model Organism for Bioscience: A Historic Review and Perspective. BIOLOGY 2023; 12:890. [PMID: 37372174 DOI: 10.3390/biology12060890] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 06/15/2023] [Accepted: 06/20/2023] [Indexed: 06/29/2023]
Abstract
In vitro systems have been mainly promoted by authorities to sustain research by following the 3Rs principle, but continuously increasing amounts of evidence point out that in vivo experimentation is also of extreme relevance. Xenopus laevis, an anuran amphibian, is a significant model organism in the study of evolutionary developmental biology, toxicology, ethology, neurobiology, endocrinology, immunology and tumor biology; thanks to the recent development of genome editing, it has also acquired a relevant position in the field of genetics. For these reasons, X. laevis appears to be a powerful and alternative model to the zebrafish for environmental and biomedical studies. Its life cycle, as well as the possibility to obtain gametes from adults during the whole year and embryos by in vitro fertilization, allows experimental studies of several biological endpoints, such as gametogenesis, embryogenesis, larval growth, metamorphosis and, of course, the young and adult stages. Moreover, with respect to alternative invertebrate and even vertebrate animal models, the X. laevis genome displays a higher degree of similarity with that of mammals. Here, we have reviewed the main available literature on the use of X. laevis in the biosciences and, inspired by Feymann's revised view, "Plenty of room for biology at the bottom", suggest that X. laevis is a very useful model for all possible studies.
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Affiliation(s)
- Rosa Carotenuto
- Department of Biology, University of Naples Federico II, 80126 Naples, Italy
| | | | | | - Chiara Fogliano
- Department of Biology, University of Naples Federico II, 80126 Naples, Italy
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Ahmed T, Mythreye K, Lee NY. Strength and duration of GIPC-dependent signaling networks as determinants in cancer. Neoplasia 2021; 23:181-188. [PMID: 33360508 PMCID: PMC7773760 DOI: 10.1016/j.neo.2020.12.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 12/08/2020] [Accepted: 12/10/2020] [Indexed: 10/25/2022]
Abstract
GIPC is a PDZ-domain containing adaptor protein that regulates the cell surface expression and endocytic trafficking of numerous transmembrane receptors and signaling complexes. Interactions with over 50 proteins have been reported to date including VEGFR, insulin-like growth factor-1 receptor (IGF-1R), GPCRs, and APPL, many of which have essential roles in neuronal and cardiovascular development. In cancer, a major subset of GIPC-binding receptors and cytoplasmic effectors have been shown to promote tumorigenesis or metastatic progression, while other subsets have demonstrated strong tumor-suppressive effects. Given that these diverse pathways are widespread in normal tissues and human malignancies, precisely how these opposing signals are integrated and regulated within the same tumor setting likely depend on the strength and duration of their interactions with GIPC. This review highlights the major pathways and divergent mechanisms of GIPC signaling in various cancers and provide a rationale for emerging GIPC-targeted cancer therapies.
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Affiliation(s)
- Tasmia Ahmed
- Deparment of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, USA
| | - Karthikeyan Mythreye
- Division of Molecular and Cellular Pathology, University of Alabama Birmingham, Birmingham, AL, USA
| | - Nam Y Lee
- Deparment of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, USA; Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA; The University of Arizona Cancer Center, Tucson, AZ, USA.
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Eukaryotic initiation factor eIF6 modulates the expression of Kermit 2/XGIPC in IGF- regulated eye development. Dev Biol 2017; 427:148-154. [DOI: 10.1016/j.ydbio.2017.04.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 12/28/2016] [Accepted: 04/26/2017] [Indexed: 10/19/2022]
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Luehders K, Sasai N, Davaapil H, Kurosawa-Yoshida M, Hiura H, Brah T, Ohnuma SI. The small leucine-rich repeat secreted protein Asporin induces eyes in Xenopus embryos through the IGF signalling pathway. Development 2016; 142:3351-61. [PMID: 26443635 DOI: 10.1242/dev.124438] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Small leucine-rich repeat proteoglycan (SLRP) family proteins play important roles in a number of biological events. Here, we demonstrate that the SLRP family member Asporin (ASPN) plays a crucial role in the early stages of eye development in Xenopus embryos. During embryogenesis, ASPN is broadly expressed in the neuroectoderm of the embryo. Overexpression of ASPN causes the induction of ectopic eyes. By contrast, blocking ASPN function with a morpholino oligonucleotide (ASPN-MO) inhibits eye formation, indicating that ASPN is an essential factor for eye development. Detailed molecular analyses revealed that ASPN interacts with insulin growth factor receptor (IGFR) and is essential for activating the IGF receptor-mediated intracellular signalling pathway. Moreover, ASPN perturbed the Wnt, BMP and Activin signalling pathways, suggesting that ASPN thereby creates a favourable environment in which the IGF signal can dominate. ASPN is thus a novel secreted molecule essential for eye induction through the coordination of multiple signalling pathways.
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Affiliation(s)
- Kristin Luehders
- Ocular Biology and Therapeutic unit (ORBIT), Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
| | - Noriaki Sasai
- Ocular Biology and Therapeutic unit (ORBIT), Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK Developmental Biomedical Science, Graduate School of Biological Sciences, Nara Institute of Science and Technology (NAIST), 8916-5, Takayama-cho, Ikoma 630-0192, Japan
| | - Hongorzul Davaapil
- Ocular Biology and Therapeutic unit (ORBIT), Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
| | - Maiko Kurosawa-Yoshida
- Department of Oncology, The Hutchison/MRC Research Centre, University of Cambridge, Hills Road, Cambridge CB2 2XZ, UK
| | - Hitoshi Hiura
- Ocular Biology and Therapeutic unit (ORBIT), Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
| | - Tara Brah
- Ocular Biology and Therapeutic unit (ORBIT), Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
| | - Shin-ichi Ohnuma
- Ocular Biology and Therapeutic unit (ORBIT), Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK Department of Oncology, The Hutchison/MRC Research Centre, University of Cambridge, Hills Road, Cambridge CB2 2XZ, UK
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Insulin-like factor regulates neural induction through an IGF1 receptor-independent mechanism. Sci Rep 2015; 5:11603. [PMID: 26112133 PMCID: PMC4481404 DOI: 10.1038/srep11603] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 05/29/2015] [Indexed: 01/15/2023] Open
Abstract
Insulin receptor (IR) and insulin-like growth factor-1 receptor (IGF1R) signalling is required for normal embryonic growth and development. Previous reports indicated that the IGF/IGF1R/MAPK pathway contributes to neural induction and the IGF/IGF1R/PI3K/Akt pathway to eye development. Here, we report the isolation of insulin3 encoding a novel insulin-like ligand involved in neural induction. Insulin3 has a similar structure to pro-insulin and mature IGF ligands, but cannot activate the IGF1 receptor. However, similar to IGFs, Insulin3 induced the gene expression of an anterior neural marker, otx2, and enlarged anterior head structures by inhibiting Wnt signalling. Insulin3 are predominantly localised to the endoplasmic reticulum when otx2 is induced by insulin3. Insulin3 reduced extracellular Wnts and cell surface localised Lrp6. These results suggest that Insulin3 is a novel cell-autonomous inhibitor of Wnt signalling. This study provides the first evidence that an insulin-like factor regulates neural induction through an IGF1R-independent mechanism.
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La Torre A, Hoshino A, Cavanaugh C, Ware CB, Reh TA. The GIPC1-Akt1 Pathway Is Required for the Specification of the Eye Field in Mouse Embryonic Stem Cells. Stem Cells 2015; 33:2674-85. [PMID: 26013465 DOI: 10.1002/stem.2062] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 04/22/2015] [Indexed: 12/20/2022]
Abstract
During early patterning of the neural plate, a single region of the embryonic forebrain, the eye field, becomes competent for eye development. The hallmark of eye field specification is the expression of the eye field transcription factors (EFTFs). Experiments in fish, amphibians, birds, and mammals have demonstrated largely conserved roles for the EFTFs. Although some of the key signaling events that direct the synchronized expression of these factors to the eye field have been elucidated in fish and frogs, it has been more difficult to study these mechanisms in mammalian embryos. In this study, we have used two different methods for directed differentiation of mouse embryonic stem cells (mESCs) to generate eye field cells and retina in vitro to test for a role of the PDZ domain-containing protein GIPC1 in the specification of the mammalian eye primordia. We find that the overexpression of a dominant-negative form of GIPC1 (dnGIPC1), as well as the downregulation of endogenous GIPC1, is sufficient to inhibit the development of eye field cells from mESCs. GIPC1 interacts directly with IGFR and participates in Akt1 activation, and pharmacological inhibition of Akt1 phosphorylation mimics the dnGIPC1 phenotype. Our data, together with previous studies in Xenopus, support the hypothesis that the GIPC1-PI3K-Akt1 pathway plays a key role in eye field specification in vertebrates.
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Affiliation(s)
- Anna La Torre
- Department of Biological Structure, Institute for Stem Cells and Regenerative Medicine, University of Washington, Seattle, Washington, USA.,Department of Cell Biology and Human Anatomy, School of Medicine, University of California, Davis, California, USA
| | - Akina Hoshino
- Department of Biological Structure, Institute for Stem Cells and Regenerative Medicine, University of Washington, Seattle, Washington, USA
| | - Christopher Cavanaugh
- Department of Comparative Medicine, University of Washington, Seattle, Washington, USA
| | - Carol B Ware
- Department of Comparative Medicine, University of Washington, Seattle, Washington, USA
| | - Thomas A Reh
- Department of Biological Structure, Institute for Stem Cells and Regenerative Medicine, University of Washington, Seattle, Washington, USA
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Guo L, Du X, Lu C, Zhang WH. Association between Insulin-Like Growth Factor 1 Gene rs12423791 or rs6214 Polymorphisms and High Myopia: A Meta-Analysis. PLoS One 2015; 10:e0129707. [PMID: 26076017 PMCID: PMC4468052 DOI: 10.1371/journal.pone.0129707] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Accepted: 05/12/2015] [Indexed: 11/19/2022] Open
Abstract
Objective To evaluate the association of insulin-like growth factor 1 gene rs12423791 and rs6214 polymorphisms with high myopia. Methods An electronic search was conducted on PubMed, Embase, the Cochrane Library and the Chinese Biological Abstract Database for articles published prior to May 6, 2014. A meta-analysis was performed using Revman 5.1 and Stata 12.0, and the odds ratios with 95% confidence intervals were calculated in fixed or random effects models based on the results of the Q test. The subgroup analysis was conducted on the basis of the various regions, the sensitivity analysis was also performed to evaluate the stability of the results, and the publication bias was evaluated by a funnel plot and Egger’s linear regression analysis. Results This comprehensive meta-analysis included 2808 high myopia patients and 2778 controls from five unrelated studies. The results demonstrated that the significant association was not present in any genetic models between IGF-1 rs12423791 or rs6214 and high myopia. However, subgroup analysis indicated that rs12423791 polymorphism was associated with high myopia in the Chinese populations in the allelic contrast model (C vs. G: OR=1.24, 95% CI=1.04-1.48 in the fixed-effects model), the dominant model (CC+CG vs. GG: OR=1.40, 95% CI=1.16-1.69 in the fixed-effects model), and the codominant model (CG vs. GG: OR=1.37, 95% CI= 1.12-1.68 in the fixed-effects model). Additionally, none of the individual studies significantly affected the association between IGF-1 rs12423791 and high myopia, according to sensitivity analysis. Conclusion This meta-analysis shows that IGF-1 rs12423791 or rs6214 gene polymorphism is not associated with high myopia.
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Affiliation(s)
- Lan Guo
- Department of Medical statistics and Epidemiology, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, People’s Republic of China
| | - Xueying Du
- Department of laboratory, Center for the primary and secondary school health promotion, Guangzhou, 510080, People’s Republic of China
| | - Ciyong Lu
- Department of Medical statistics and Epidemiology, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, People’s Republic of China
- * E-mail:
| | - Wei-Hong Zhang
- Epidemiology, Biostatistics and Clinical Research Centre, School of Public Health, Université Libre de Bruxelles (ULB), Belgium
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Chau TL, Göktuna SI, Rammal A, Casanova T, Duong HQ, Gatot JS, Close P, Dejardin E, Desmecht D, Shostak K, Chariot A. A role for APPL1 in TLR3/4-dependent TBK1 and IKKε activation in macrophages. THE JOURNAL OF IMMUNOLOGY 2015; 194:3970-83. [PMID: 25780039 DOI: 10.4049/jimmunol.1401614] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 02/03/2015] [Indexed: 01/07/2023]
Abstract
Endosomes have important roles in intracellular signal transduction as a sorting platform. Signaling cascades from TLR engagement to IRF3-dependent gene transcription rely on endosomes, yet the proteins that specifically recruit IRF3-activating molecules to them are poorly defined. We show that adaptor protein containing a pleckstrin-homology domain, a phosphotyrosine-binding domain, and a leucine zipper motif (APPL)1, an early endosomal protein, is required for both TRIF- and retinoic acid-inducible gene 1-dependent signaling cascades to induce IRF3 activation. APPL1, but not early endosome Ag 1, deficiency impairs IRF3 target gene expression upon engagement of both TLR3 and TLR4 pathways, as well as in H1N1-infected macrophages. The IRF3-phosphorylating kinases TBK1 and IKKε are recruited to APPL1 endosomes in LPS-stimulated macrophages. Interestingly, APPL1 undergoes proteasome-mediated degradation through ERK1/2 to turn off signaling. APPL1 degradation is blocked when signaling through the endosome is inhibited by chloroquine or dynasore. Therefore, APPL1 endosomes are critical for IRF3-dependent gene expression in response to some viral and bacterial infections in macrophages. Those signaling pathways involve the signal-induced degradation of APPL1 to prevent aberrant IRF3-dependent gene expression linked to immune diseases.
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Affiliation(s)
- Tieu-Lan Chau
- Interdisciplinary Cluster of Applied Genoproteomics, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Laboratory of Medical Chemistry, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Unit of Signal Transduction, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium
| | - Serkan Ismail Göktuna
- Interdisciplinary Cluster of Applied Genoproteomics, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Laboratory of Medical Chemistry, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Unit of Signal Transduction, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium
| | - Ayman Rammal
- Interdisciplinary Cluster of Applied Genoproteomics, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Laboratory of Medical Chemistry, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Unit of Signal Transduction, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium
| | - Tomás Casanova
- Department of Veterinary Pathology, Fundamental and Applied Research for Animals and Health, University of Liege, 4000 Liege, Belgium
| | - Hong-Quan Duong
- Interdisciplinary Cluster of Applied Genoproteomics, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Laboratory of Medical Chemistry, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Unit of Signal Transduction, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium
| | - Jean-Stéphane Gatot
- Interdisciplinary Cluster of Applied Genoproteomics, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Laboratory of Medical Chemistry, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Unit of Signal Transduction, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium
| | - Pierre Close
- Interdisciplinary Cluster of Applied Genoproteomics, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Laboratory of Medical Chemistry, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Unit of Signal Transduction, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium
| | - Emmanuel Dejardin
- Interdisciplinary Cluster of Applied Genoproteomics, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Unit of Signal Transduction, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Laboratory of Molecular Immunology and Signal Transduction, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; and
| | - Daniel Desmecht
- Department of Veterinary Pathology, Fundamental and Applied Research for Animals and Health, University of Liege, 4000 Liege, Belgium
| | - Kateryna Shostak
- Interdisciplinary Cluster of Applied Genoproteomics, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Laboratory of Medical Chemistry, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Unit of Signal Transduction, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium
| | - Alain Chariot
- Interdisciplinary Cluster of Applied Genoproteomics, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Laboratory of Medical Chemistry, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Unit of Signal Transduction, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Walloon Excellence in Life Sciences and Biotechnology, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium
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Yoshida M, Meguro A, Yoshino A, Nomura N, Okada E, Mizuki N. Association study of IGF1 polymorphisms with susceptibility to high myopia in a Japanese population. Clin Ophthalmol 2013; 7:2057-62. [PMID: 24204106 PMCID: PMC3804590 DOI: 10.2147/opth.s52726] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
PURPOSE Polymorphisms in the insulin-like growth factor 1 (IGF1) gene were previously associated with high or extreme myopia in Caucasian and Chinese populations. In the present study, we investigated whether IGF1 polymorphisms are associated with high myopia in a Japanese population. METHODS A total of 446 Japanese patients with high myopia (≤-9.00 diopters) and 481 Japanese healthy controls (+1.50 diopters to -1.50 diopters) were recruited. We genotyped seven tagging single-nucleotide polymorphisms (SNPs) in IGF1 and assessed allelic and haplotypic diversity in cases and controls. RESULTS There were no statistically significant differences in the allele frequencies of IGF1 SNPs and genotypes between cases and controls (P>0.05). However, the A allele of rs5742629 and the G allele of rs12423791 were associated with a moderately increased risk of high myopia (odds ratio [OR] =1.20 and OR =1.21, respectively) with borderline statistical significance (P=0.0502, corrected P (Pc) =0.21 and P=0.064, Pc=0.29, respectively). The haplotype consisting of the A allele of rs5742629 and the G allele of rs12423791 was marginally associated with the risk of high myopia (P=0.041; OR =1.21); this association was not significant after correction (Pc=0.19). CONCLUSION We found that the IGF1 SNPs are not significantly associated with high myopia in our Japanese population. Our results are in contrast to a previous study in which extreme myopia cases had significantly higher frequencies of the G allele of rs5742629 and the C allele of rs12423791 than controls. Therefore, the IGF1 SNPs may not be important factors for susceptibility to high myopia in all populations. Further genetic studies are needed to elucidate the possible contributions of the IGF1 region to the development of high myopia.
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Affiliation(s)
- Masao Yoshida
- Department of Public Health, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
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Reynolds J, Lamba DA. Human embryonic stem cell applications for retinal degenerations. Exp Eye Res 2013; 123:151-60. [PMID: 23880530 DOI: 10.1016/j.exer.2013.07.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 06/27/2013] [Accepted: 07/08/2013] [Indexed: 12/12/2022]
Abstract
Loss of vision in severe retinal degenerations often is a result of photoreceptor cell or retinal pigment epithelial cell death or dysfunction. Cell replacement therapy has the potential to restore useful vision for these individuals especially after they have lost most or all of their light-sensing cells in the eye. A reliable, well-characterized source of retinal cells will be needed for replacement purposes. Human embryonic stem cells (ES cells) can provide an unlimited source of replacement retinal cells to take over the function of lost cells in the eye. The author's intent for this review is to provide an historical overview of the field of embryonic stem cells with relation to the retina. The review will provide a quick primer on key pathways involved in the development of the neural retina and RPE followed by a discussion of the various protocols out in the literature for generating these cells from non-human and human embryonic stem cells and end with in vivo application of ES cell-derived photoreceptors and RPE cells.
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Affiliation(s)
- Joseph Reynolds
- Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, USA
| | - Deepak A Lamba
- Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, USA.
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Katoh M. Functional proteomics, human genetics and cancer biology of GIPC family members. Exp Mol Med 2013; 45:e26. [PMID: 23743496 PMCID: PMC3701287 DOI: 10.1038/emm.2013.49] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Accepted: 04/04/2013] [Indexed: 12/24/2022] Open
Abstract
GIPC1, GIPC2 and GIPC3 consist of GIPC homology 1 (GH1) domain, PDZ domain and GH2 domain. The regions around the GH1 and GH2 domains of GIPC1 are involved in dimerization and interaction with myosin VI (MYO6), respectively. The PDZ domain of GIPC1 is involved in interactions with transmembrane proteins [IGF1R, NTRK1, ADRB1, DRD2, TGFβR3 (transforming growth factorβ receptor type III), SDC4, SEMA4C, LRP1, NRP1, GLUT1, integrin α5 and VANGL2], cytosolic signaling regulators (APPL1 and RGS19) and viral proteins (HBc and HPV-18 E6). GIPC1 is an adaptor protein with dimerizing ability that loads PDZ ligands as cargoes for MYO6-dependent endosomal trafficking. GIPC1 is required for cell-surface expression of IGF1R and TGFβR3. GIPC1 is also required for integrin recycling during cell migration, angiogenesis and cytokinesis. On early endosomes, GIPC1 assembles receptor tyrosine kinases (RTKs) and APPL1 for activation of PI3K-AKT signaling, and G protein-coupled receptors (GPCRs) and RGS19 for attenuation of inhibitory Gα signaling. GIPC1 upregulation in breast, ovarian and pancreatic cancers promotes tumor proliferation and invasion, whereas GIPC1 downregulation in cervical cancer with human papillomavirus type 18 infection leads to resistance to cytostatic transforming growth factorβ signaling. GIPC2 is downregulated in acute lymphocytic leukemia owing to epigenetic silencing, while Gipc2 is upregulated in estrogen-induced mammary tumors. Somatic mutations of GIPC2 occur in malignant melanoma, and colorectal and ovarian cancers. Germ-line mutations of the GIPC3 or MYO6 gene cause nonsyndromic hearing loss. As GIPC proteins are involved in trafficking, signaling and recycling of RTKs, GPCRs, integrins and other transmembrane proteins, dysregulation of GIPCs results in human pathologies, such as cancer and hereditary deafness.
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Affiliation(s)
- Masaru Katoh
- Division of Integrative Omics and Bioinformatics, National Cancer Centre, Tokyo, Japan.
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Preston JC, Hileman LC. Functional Evolution in the Plant SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) Gene Family. FRONTIERS IN PLANT SCIENCE 2013; 4:80. [PMID: 23577017 PMCID: PMC3617394 DOI: 10.3389/fpls.2013.00080] [Citation(s) in RCA: 147] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 03/19/2013] [Indexed: 05/18/2023]
Abstract
The SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) family of transcription factors is functionally diverse, controlling a number of fundamental aspects of plant growth and development, including vegetative phase change, flowering time, branching, and leaf initiation rate. In natural plant populations, variation in flowering time and shoot architecture have major consequences for fitness. Likewise, in crop species, variation in branching and developmental rate impact biomass and yield. Thus, studies aimed at dissecting how the various functions are partitioned among different SPL genes in diverse plant lineages are key to providing insight into the genetic basis of local adaptation and have already garnered attention by crop breeders. Here we use phylogenetic reconstruction to reveal nine major SPL gene lineages, each of which is described in terms of function and diversification. To assess evidence for ancestral and derived functions within each SPL gene lineage, we use ancestral character state reconstructions. Our analyses suggest an emerging pattern of sub-functionalization, neo-functionalization, and possible convergent evolution following both ancient and recent gene duplication. Based on these analyses we suggest future avenues of research that may prove fruitful for elucidating the importance of SPL gene evolution in plant growth and development.
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Affiliation(s)
| | - Lena C. Hileman
- Ecology and Evolutionary Biology, The University of KansasLawrence, KS, USA
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Abstract
Vascular endothelial growth factors (VEGF) and their receptors play a central role in the development of cardiovascular system and in vasculature-related processes in the adult organism. Given the critical role of this signaling cascade, intricate control systems have evolved to regulate its function. A new layer of added complexity has been the demonstration of the importance of endocytosis and intracellular trafficking of VEGF receptors in the regulation of VEGF signaling. In this review, we consider an evolving link between VEGF receptor endocytosis, trafficking, and signaling and their biological function.
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Affiliation(s)
- Michael Simons
- Department of Internal Medicine, Section of Cardiovascular Medicine, Yale Cardiovascular Research Center, New Haven, Connecticut, USA.
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Mu Y, Huang H, Liu S, Cai P, Gao Y. Molecular characterization and ligand binding specificity of the PDZ domain-containing protein GIPC3 from Schistosoma japonicum. Parasit Vectors 2012; 5:227. [PMID: 23050840 PMCID: PMC3504512 DOI: 10.1186/1756-3305-5-227] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 10/05/2012] [Indexed: 01/09/2023] Open
Abstract
Background Schistosomiasis is a serious global health problem that afflicts more than 230 million people in 77 countries. Long-term mass treatments with the only available drug, praziquantel, have caused growing concerns about drug resistance. PSD-95/Dlg/ZO-1 (PDZ) domain-containing proteins are recognized as potential targets for the next generation of drug development. However, the PDZ domain-containing protein family in parasites has largely been unexplored. Methods We present the molecular characteristics of a PDZ domain-containing protein, GIPC3, from Schistosoma japonicum (SjGIPC3) according to bioinformatics analysis and experimental approaches. The ligand binding specificity of the PDZ domain of SjGIPC3 was confirmed by screening an arbitrary peptide library in yeast two-hybrid (Y2H) assays. The native ligand candidates were predicted by Tailfit software based on the C-terminal binding specificity, and further validated by Y2H assays. Results SjGIPC3 is a single PDZ domain-containing protein comprised of 328 amino acid residues. Structural prediction revealed that a conserved PDZ domain was presented in the middle region of the protein. Phylogenetic analysis revealed that SjGIPC3 and other trematode orthologues clustered into a well-defined cluster but were distinguishable from those of other phyla. Transcriptional analysis by quantitative RT-PCR revealed that the SjGIPC3 gene was relatively highly expressed in the stages within the host, especially in male adult worms. By using Y2H assays to screen an arbitrary peptide library, we confirmed the C-terminal binding specificity of the SjGIPC3-PDZ domain, which could be deduced as a consensus sequence, -[SDEC]-[STIL]-[HSNQDE]-[VIL]*. Furthermore, six proteins were predicted to be native ligand candidates of SjGIPC3 based on the C-terminal binding properties and other biological information; four of these were confirmed to be potential ligands using the Y2H system. Conclusions In this study, we first characterized a PDZ domain-containing protein GIPC3 in S. japonicum. The SjGIPC3-PDZ domain is able to bind both type I and II ligand C-terminal motifs. The identification of native ligand will help reveal the potential biological function of SjGIPC3. These data will facilitate the identification of novel drug targets against S. japonicum infections.
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Affiliation(s)
- Yi Mu
- National Key Laboratory of Medical Molecular Biology, Dept, of Physiology and Pathophysiology, School of Basic Medicine, Peking Union Medical College, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, Beijing 100005, P,R, China
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15
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Qin L, Wang Y, Tao L, Wang Z. AKT down-regulates insulin-like growth factor-1 receptor as a negative feedback. J Biochem 2011; 150:151-6. [PMID: 21616916 DOI: 10.1093/jb/mvr066] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
As a member of receptor tyrosine kinase (RTK) family, insulin-like growth factor-1 (IGF1) receptor (IGF1R) activates several downstream pathways to transmit proliferative signals from extracellular stimulation. AKT as a major effector plays a pivotal role in integrating various survival signalling cascades. Our data here show that hyperactive AKT leads to the decrease of IGF1R at the transcriptional level, which could be partly restored by phosphatidylinositol-3 kinase (PI3K) inhibitors including wortmannin and LY294002. Moreover, the decrease of IGF1R impairs the sensitivity of IRS1 to the stimulation by IGF1. mTOR as a main downstream target of AKT is not involved in the AKT-mediated down-regulation of IGF1R.
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Affiliation(s)
- Liang Qin
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA.
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16
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De Marco N, Tussellino M, Vitale A, Campanella C. Eukaryotic initiation factor 6 (eif6) overexpression affects eye development in Xenopus laevis. Differentiation 2011; 82:108-15. [PMID: 21601348 DOI: 10.1016/j.diff.2011.05.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 04/27/2011] [Accepted: 05/02/2011] [Indexed: 01/13/2023]
Abstract
The translation initiation factor eif6 has been implicated as a regulator of ribosome assembly, selective mRNA translation and apoptosis. Many of these activities depend upon the phosphorylation of eif6 serine 235 by PKC. Previous data showed that eif6 binds to the 60S ribosomal subunit when unphosphorylated, inhibiting assembly with the 40S subunit. Phosphorylation of Ser235 releases eif6 from the 60S subunit and allows assembly. eif6 acts as an anti-apoptotic factor via regulation of the bcl2/bax balance and acts selectively upstream of bcl2. This activity also depends upon phosphorylation of eif6 Ser235. One of the consequences of eif6 overexpression in Xenopus embryos is aberrant eye development. Here we evaluate the eye phenotype and show that it is transient. We show that the whole eye, particularly the retina layers, of the embryos injected with eif6-encoding mRNA recover by stage 42. Embryos over-expressing eif6 have normal expression of anterior- and brain-specific markers, indicating that outside the eye field, other neural regions appear unaffected by the eif6 injection. No eye defect was detected when morpholinos were used to reduce eif6 protein synthesis. We tested how two known pathways of eif6 function with respect to alteration of eye development. We found that injection of bcl2 did not produce the eye phenotype and eif6-bax co-injection did not rescue the eye defect, suggesting that the eye phenotype is not bearing on the anti-apoptotic role played by eif6 is not linked to its role as an anti-apoptotic factor. We also determined that PKC-dependant phosphorylation of Ser235 in eif6 is not required to produce defective eye development. These results indicate that the aberrant eye phenotype, produced by eif6 overexpression, is not directly linked to the PKC-regulated effects of eif6 on translation and ribosomal subunit interaction or on eif6 anti-apoptotic properties.
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Affiliation(s)
- N De Marco
- Department of Structural and Functional Biology, University of Naples Federico II, Naples, Italy.
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Bugner V, Aurhammer T, Kühl M. Xenopus laevis insulin receptor substrate IRS-1 is important for eye development. Dev Dyn 2011; 240:1705-15. [DOI: 10.1002/dvdy.22659] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/22/2011] [Indexed: 12/30/2022] Open
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Romanelli RJ, Wood TL. Directing traffic in neural cells: determinants of receptor tyrosine kinase localization and cellular responses. J Neurochem 2010; 105:2055-68. [PMID: 18248622 DOI: 10.1111/j.1471-4159.2008.05263.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The trafficking of receptor tyrosine kinases (RTKs) to distinct subcellular locations is essential for the specificity and fidelity of signal transduction and biological responses. This is particularly important in the PNS and CNS in which RTKs mediate key events in the development and maintenance of neurons and glia through a wide range of neural processes, including survival, proliferation, differentiation, neurite outgrowth, and synaptogenesis. The mechanisms that regulate the targeting of RTKs to their subcellular destinations for appropriate signal transduction, however, are still elusive. In this review, we discuss evidence for the spatial organization of signaling machinery into distinct subcellular compartments, as well as the role for ligand specificity, receptor sorting signals, and lipid raft microdomains in RTK targeting and the resultant cellular responses in neural cells.
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Affiliation(s)
- Robert J Romanelli
- Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, Oregon, USA
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Wu D, Haruta A, Wei Q. GIPC1 interacts with MyoGEF and promotes MDA-MB-231 breast cancer cell invasion. J Biol Chem 2010; 285:28643-50. [PMID: 20634288 DOI: 10.1074/jbc.m110.107649] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
GIPC1/synectin, a single PDZ domain-containing protein, binds to numerous proteins and is involved in multiple biological processes, including cell migration. We reported previously that MyoGEF, a guanine nucleotide exchange factor, plays a role in regulating breast cancer cell polarization and invasion. Here, we identify GIPC1 as an interacting partner of MyoGEF. Both in vitro and in vivo binding assays show that the GIPC1 PDZ domain binds to the PDZ-binding motif at the C terminus of MyoGEF. Immunofluorescence analysis shows that GIPC1 and MyoGEF colocalize to the cell leading edge. Depletion of GIPC1 by RNAi in MDA-MB-231 cells causes cells to shift from a polarized to a rounded morphology. Matrigel invasion assays show that RNAi-mediated depletion of GIPC1 dramatically decreases MDA-MB-231 cell invasion. Notably, an anti-MyoGEF peptide antibody, whose epitope is located at the C terminus of MyoGEF, interferes with GIPC1-MyoGEF complex formation. Treatment of MDA-MB-231 cells with the anti-MyoGEF peptide antibody disrupts cell polarization and invasion. Thus, our results suggest that GIPC1-MyoGEF complex formation plays an important role in regulating MDA-MB-231 breast cancer cell polarization and invasion.
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Affiliation(s)
- Di Wu
- Department of Biochemistry, Kansas State University, Manhattan, Kansas 66506, USA
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Djiane A, Mlodzik M. The Drosophila GIPC homologue can modulate myosin based processes and planar cell polarity but is not essential for development. PLoS One 2010; 5:e11228. [PMID: 20574526 PMCID: PMC2888583 DOI: 10.1371/journal.pone.0011228] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Accepted: 06/01/2010] [Indexed: 01/20/2023] Open
Abstract
Epithelia often show, in addition to the ubiquitous apico-basal (A/B) axis, a polarization within the plane of the epithelium, perpendicular to the A/B axis. Such planar cell polarity (PCP) is for example evident in the regular arrangement of the stereocilia in the cochlea of the mammalian inner ear or in (almost) all Drosophila adult external structures. GIPCs (GAIP interacting protein, C terminus) were first identified in mammals and bind to the Gαi GTPase activating protein RGS-GAIP. They have been proposed to act in a G-protein coupled complex controlling vesicular trafficking. Although GIPCs have been found to bind to numerous proteins including Frizzled receptors, which participate in PCP establishment, there is little in vivo evidence for the functional role(s) of GIPCs. We show here that overexpressed Drosophila dGIPC alters PCP generation in the wing. We were however unable to find any binding between dGIPC and the Drosophila receptors Fz1 and Fz2. The effect of overexpressed dGIPC is likely due to an effect on the actin cytoskeleton via myosins, since it is almost entirely suppressed by removing a genomic copy of the Myosin VI/jaguar gene. Surprisingly, although dGIPC can interfere with PCP generation and myosin based processes, the complete loss-of-function of dGIPC gives viable adults with no PCP or other detectable defects arguing for a non-essential role of dGIPC in viability and normal Drosophila development.
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Affiliation(s)
- Alexandre Djiane
- Department of Physiology Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Marek Mlodzik
- Department of Developmental and Regenerative Biology, Mount Sinai School of Medicine, New York, New York, United States of America
- * E-mail:
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Spicer E, Suckert C, Al-Attar H, Marsden M. Integrin alpha5beta1 function is regulated by XGIPC/kermit2 mediated endocytosis during Xenopus laevis gastrulation. PLoS One 2010; 5:e10665. [PMID: 20498857 PMCID: PMC2871791 DOI: 10.1371/journal.pone.0010665] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 04/19/2010] [Indexed: 12/17/2022] Open
Abstract
During Xenopus gastrulation α5β1 integrin function is modulated in a temporally and spatially restricted manner, however, the regulatory mechanisms behind this regulation remain uncharacterized. Here we report that XGIPC/kermit2 binds to the cytoplasmic domain of the α5 subunit and regulates the activity of α5β1 integrin. The interaction of kermit2 with α5β1 is essential for fibronectin (FN) matrix assembly during the early stages of gastrulation. We further demonstrate that kermit2 regulates α5β1 integrin endocytosis downstream of activin signaling. Inhibition of kermit2 function impairs cell migration but not adhesion to FN substrates indicating that integrin recycling is essential for mesoderm cell migration. Furthermore, we find that the α5β1 integrin is colocalized with kermit2 and Rab 21 in embryonic and XTC cells. These data support a model where region specific mesoderm induction acts through kermit2 to regulate the temporally and spatially restricted changes in adhesive properties of the α5β1 integrin through receptor endocytosis.
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Affiliation(s)
- Erin Spicer
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Catherine Suckert
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Hyder Al-Attar
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Mungo Marsden
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
- * E-mail:
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22
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Muders MH, Vohra PK, Dutta SK, Wang E, Ikeda Y, Wang L, Udugamasooriya DG, Memic A, Rupasinghe CN, Rupashinghe CN, Baretton GB, Aust DE, Langer S, Datta K, Simons M, Spaller MR, Mukhopadhyay D. Targeting GIPC/synectin in pancreatic cancer inhibits tumor growth. Clin Cancer Res 2009; 15:4095-103. [PMID: 19509165 DOI: 10.1158/1078-0432.ccr-08-2837] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
PURPOSE Various studies have shown the importance of the GAIP interacting protein, COOH-terminus (GIPC, also known as Synectin) as a central adaptor molecule in different signaling pathways and as an important mediator of receptor stability. GIPC/Synectin is associated with different growth-promoting receptors such as insulin-like growth factor receptor I (IGF-IR) and integrins. These interactions were mediated through its PDZ domain. GIPC/Synectin has been shown to be overexpressed in pancreatic and breast cancer. The goal of this study was to show the importance of GIPC/Synectin in pancreatic cancer growth and to evaluate a possible therapeutic strategy by using a GIPC-PDZ domain inhibitor. Furthermore, the effect of targeting GIPC on the IGF-I receptor as one of its associated receptors was tested. EXPERIMENTAL DESIGN The in vivo effects of GIPC/Synectin knockdown were studied after lentiviral transduction of luciferase-expressing pancreatic cancer cells with short hairpin RNA against GIPC/Synectin. Additionally, a GIPC-PDZ--targeting peptide was designed. This peptide was tested for its influence on pancreatic cancer growth in vitro and in vivo. RESULTS Knockdown of GIPC/Synectin led to a significant inhibition of pancreatic adenocarcinoma growth in an orthotopic mouse model. Additionally, a cell-permeable GIPC-PDZ inhibitor was able to block tumor growth significantly without showing toxicity in a mouse model. Targeting GIPC was accompanied by a significant reduction in IGF-IR expression in pancreatic cancer cells. CONCLUSIONS Our findings show that targeting GIPC/Synectin and its PDZ domain inhibits pancreatic carcinoma growth and is a potential strategy for therapeutic intervention of pancreatic cancer.
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Affiliation(s)
- Michael H Muders
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota 55905, USA
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Zoncu R, Perera RM, Balkin DM, Pirruccello M, Toomre D, De Camilli P. A phosphoinositide switch controls the maturation and signaling properties of APPL endosomes. Cell 2009; 136:1110-21. [PMID: 19303853 DOI: 10.1016/j.cell.2009.01.032] [Citation(s) in RCA: 271] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Revised: 11/12/2008] [Accepted: 01/06/2009] [Indexed: 01/11/2023]
Abstract
The recent identification of several novel endocytic compartments has challenged our current understanding of the topological and functional organization of the endocytic pathway. Using quantitative single vesicle imaging and acute manipulation of phosphoinositides we show that APPL endosomes, which participate in growth factor receptor trafficking and signaling, represent an early endocytic intermediate common to a subset of clathrin derived endocytic vesicles and macropinosomes. Most APPL endosomes are precursors of classical PI3P positive endosomes, and PI3P plays a critical role in promoting this conversion. Depletion of PI3P causes a striking reversion of Rab5 positive endosomes to the APPL stage, and results in enhanced growth factor signaling. These findings reveal a surprising plasticity of the early endocytic pathway. Importantly, PI3P functions as a switch to dynamically regulate maturation and signaling of APPL endosomes.
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Affiliation(s)
- Roberto Zoncu
- Department of Cell Biology, Kavli Institute for Neuroscience and Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06510, USA
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Rorick AM, Mei W, Liette NL, Phiel C, El-Hodiri HM, Yang J. PP2A:B56ε is required for eye induction and eye field separation. Dev Biol 2007; 302:477-93. [PMID: 17074314 DOI: 10.1016/j.ydbio.2006.10.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2006] [Revised: 09/29/2006] [Accepted: 10/05/2006] [Indexed: 12/18/2022]
Abstract
Eye induction and eye field separation are the earliest events during vertebrate eye development. Both of these processes occur much earlier than the formation of optic vesicles. The insulin-like growth factor (IGF) pathway appears to be essential for eye induction, yet it remains unclear how IGF downstream pathways are involved in eye induction. As a consequence of eye induction, a single eye anlage is specified in the anterior neural plate. Subsequently, this single eye anlage is divided into two symmetric eye fields in response to Sonic Hedgehog (Shh) secreted from the prechordal mesoderm. Here, we report that B56epsilon regulatory subunit of protein phosphatase 2A (PP2A) is involved in Xenopus eye induction and subsequent eye field separation. We provide evidence that B56epsilon is required for the IGF/PI3K/Akt pathway and that interfering with the PI3K/Akt pathway inhibits eye induction. In addition, we show that B56epsilon regulates the Hedgehog (Hh) pathway during eye field separation. Thus, B56epsilon is involved in multiple signaling pathways and plays critical roles during early development.
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Affiliation(s)
- Anna M Rorick
- Columbus Children's Research Institute, Department of Pediatrics, The Ohio State University, Columbus, OH 43205, USA
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