Publications by authors named "Simon Saule"

31 Publications

The Phosphatase PRL-3 Is Involved in Key Steps of Cancer Metastasis.

J Mol Biol 2019 08 14;431(17):3056-3067. Epub 2019 Jun 14.

Institut Curie, PSL Research University, Centre National de La Recherche Scientifique (CNRS), Institut National de la Santé Et de la Recherche Médicale (INSERM), Unité Mixte de Recherche 3347 (UMR), Unité 1021, Orsay, France; Université Paris Sud, Université Paris-Saclay Centre National de La Recherche Scientifique, Unité Mixte de Recherche 3347, Unité 1021, Orsay, France.

PRL-3 belongs to the PRL phosphatase family. Its physiological role remains unclear, but many studies have identified that PRL-3 is a marker of cancer progression and shown it to be associated with metastasis. Evidence implicating PRL-3 in various elements of the metastatic process, such as the cell cycle, survival, angiogenesis, adhesion, cytoskeleton remodeling, EMT, motility and invasion, has been reported. Furthermore, several molecules acting as direct or indirect substrates have been identified. However, this information was obtained in many different studies, and it remains difficult to see the larger picture. We therefore systematically collected the published information together and used it to develop a comprehensive signaling network map. By analyzing this network map, we were able to retrieve the signaling pathways via which PRL-3 governs the key steps of the metastatic process in cancer. In this review, we summarize current knowledge of the role of PRL-3 in cancer and the molecular mechanisms involved. We also provide the web-based open-source PRL-3 signaling network map, for use in further studies.
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http://dx.doi.org/10.1016/j.jmb.2019.06.008DOI Listing
August 2019

Protein tyrosine phosphatase 4A3 (PTP4A3/PRL-3) promotes the aggressiveness of human uveal melanoma through dephosphorylation of CRMP2.

Sci Rep 2019 02 28;9(1):2990. Epub 2019 Feb 28.

Institut Curie, PSL Research University, CNRS, INSERM, Orsay, France.

Uveal melanoma (UM) is an aggressive tumor in which approximately 50% of patients develop metastasis. Expression of the PTP4A3 gene, encoding a phosphatase, is predictive of poor patient survival. PTP4A3 expression in UM cells increases their migration in vitro and invasiveness in vivo. Here, we show that CRMP2 is mostly dephosphorylated on T514 in PTP4A3 expressing cells. We also demonstrate that inhibition of CRMP2 expression in UM cells expressing PTP4A3 increases their migration in vitro and invasiveness in vivo. This phenotype is accompanied by modifications of the actin microfilament network, with shortened filaments, whereas cells with a inactive mutant of the phosphatase do not show the same behavior. In addition, we showed that the cell cytoplasm becomes stiffer when CRMP2 is downregulated or PTP4A3 is expressed. Our results suggest that PTP4A3 acts upstream of CRMP2 in UM cells to enhance their migration and invasiveness and that a low level of CRMP2 in tumors is predictive of poor patient survival.
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http://dx.doi.org/10.1038/s41598-019-39643-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6395723PMC
February 2019

Evaluation of Tumor Cell Invasiveness In Vivo: The Chick Chorioallantoic Membrane Assay.

Methods Mol Biol 2018 ;1749:71-77

Unité Mixte de Recherche 3347 (UMR), Unité 1021, Centre National de La Recherche Scientifique (CNRS), Institut National de la Santé Et de la Recherche Médicale (INSERM), Institut Curie, PSL Research University, Orsay, France.

Metastases is largely responsible for the mortality among cancer patients. Metastasis formation is a complex multistep process, which results from the propagation of cancer cells from the primary tumor to distant sites of the body. Research on cancer metastasis aims to understand the mechanisms involved in the spread of cancer cells through the development of in vivo assays that assess cell invasion. Here we describe the use of the chick chorioallantoic membrane to evaluate cancer cell invasiveness in vivo. The chick chorioallantoic membrane assay is based on the detection and quantification of disseminated human tumor cells in the chick embryo femurs by real-time PCR amplification of human Alu sequences.
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http://dx.doi.org/10.1007/978-1-4939-7701-7_8DOI Listing
January 2019

PRL-3/PTP4A3 phosphatase regulates integrin β1 in adhesion structures during migration of human ocular melanoma cells.

Exp Cell Res 2017 04 8;353(2):88-99. Epub 2017 Mar 8.

Institut Curie, PSL Research University, CNRS UMR3347/INSERM U1021, Orsay, France; Université Paris Diderot, Sorbonne Paris Cité, Paris, France. Electronic address:

In a previous transcriptomic analysis of 63 ocular melanomas of the uvea, we found that expression of the PRL-3/PTP4A3 gene, encoding a phosphatase that is anchored to the plasma membrane, was associated with the risk of metastasis, and a poor prognosis. We also showed that PRL-3 overexpression in OCM-1 ocular melanoma cells significantly increased cell migration in vitro and invasiveness in vivo, suggesting a direct role for PRL-3 in the metastatic spreading of uveal melanoma. Here, we aimed to identify PRL-3 substrates at the plasma membrane involved in adhesion to the extracellular matrix. We focused on integrin β1, which is the most highly expressed integrin in our cohort of uveal melanomas. We show that preventing PRL-3 anchorage to the plasma membrane i) abolishes PRL-3-induced migration in OCM-1 cells, ii) specifically enhances the spreading of OCM-1 cells overexpressing PRL-3, and iii) favors the maturation of large focal adhesions (FAs) containing integrin β1 on collagen I. Knockdown experiments confirmed integrin β1 involvement in PRL3-induced migration. We identified interactions between PRL-3 and integrin β1, as well as with FAK P-Y397, an auto-activated form of Focal Adhesion Kinase found in FAs. We also show that integrin β1 may be dephosphorylated by PRL-3 in its intracytoplasmic S/T region, an important motif for integrin-mediated cell adhesion. Finally, we observed that PRL-3 regulated the clustering of integrin β1 in FAs on collagen I but not on fibronectin. This work identifies PRL-3 as a new regulator of cell adhesion structures to the extracellular matrix, and further supports PRL-3 as a key actor of metastasis in uveal melanoma, of which molecular mechanisms are still poorly understood.
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http://dx.doi.org/10.1016/j.yexcr.2017.03.012DOI Listing
April 2017

Protein Tyrosine Phosphatase 4A3 (PTP4A3) Promotes Human Uveal Melanoma Aggressiveness Through Membrane Accumulation of Matrix Metalloproteinase 14 (MMP14).

Invest Ophthalmol Vis Sci 2016 Apr;57(4):1982-90

Institut Curie, PSL Research University, Centre National de La Recherche Scientifique (CNRS), Institut National de la Santé Et de la Recherche Médicale (INSERM), Unité Mixte de Recherche 3347 (UMR), Unité 1021 Orsay, France 2Université Paris Sud, Universi.

Purpose: To study PTP4A3 phosphatase and MMP14 metalloprotease synergy in uveal melanoma aggressiveness.

Methods: Cell membrane localization of matrix metalloprotease 14 (MMP14) in uveal melanoma cells expressing protein tyrosine phosphatase A3 (PTP4A3) was assessed by flow cytometry or immunohistochemistry. The vesicular trafficking of MMP14 in the presence of PTP4A3 was evaluated in OCM-1 cells expressing either the wild-type or mutated phosphatase. Finally, MMP14 localization at the cell membrane of OCM-1 cells was impaired using RNA interference, and the PTP4A3-related migration in vitro and invasiveness in vivo of the treated cells were evaluated.

Results: We found that the membrane-anchored MMP14 is enriched at the cell surface of OCM-1 cells, patient-derived xenograft cells, and human primary uveal melanoma tumors expressing PTP4A3. Moreover, we show that PTP4A3 and MMP14 colocalize and that the vesicular trafficking of MMP14 is faster in the presence of active PTP4A3. Finally, we demonstrate that inhibition of MMP14 expression in uveal melanoma cells expressing PTP4A3 impairs their migration in vitro and invasiveness in vivo.

Conclusions: Our observations indicate that PTP4A3 increases cell membrane accumulation of MMP14 as a result of increased cellular trafficking of the metalloprotease. We also show that downregulation of MMP14 expression reduced PTP4A3-induced cell migration and invasiveness. Taken together, our findings suggest that PTP4A3-related subcellular localization of MMP14 is an important event in metastasis induction.
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http://dx.doi.org/10.1167/iovs.15-18780DOI Listing
April 2016

DNA-PKcs plays role in cancer metastasis through regulation of secreted proteins involved in migration and invasion.

Cell Cycle 2015 ;14(12):1961-72

a Centre National de Recherche Scientifique (CNRS) UMR3347; Institut National de la Santé et de Recherche Médicale (INSERM) U1021; Institut Curie ; Orsay , France.

The DNA-dependent protein kinase catalytic subunit (DNA-PKcs) plays a major role in DNA damage signaling and repair and is also frequently overexpressed in tumor metastasis. We used isogenic cell lines expressing different levels of DNA-PKcs to investigate the role of DNA-PKcs in metastatic development. We found that DNA-PKcs participates in melanoma primary tumor and metastasis development by stimulating angiogenesis, migration and invasion. Comparison of conditioned medium content from DNA-PKcs-proficient and deficient cells reveals that DNA-PKcs controls secretion of at least 103 proteins (including 44 metastasis-associated with FBLN1, SERPINA3, MMP-8, HSPG2 and the inhibitors of matrix metalloproteinases, such as α-2M and TIMP-2). High throughput analysis of secretomes, proteomes and transcriptomes, indicate that DNA-PKcs regulates the secretion of 85 proteins without affecting their gene expression. Our data demonstrate that DNA-PKcs has a pro-metastatic activity via the modification of the tumor microenvironment. This study shows for the first time a direct link between DNA damage repair and cancer metastasis and highlights the importance of DNA-PKcs as a potential target for anti-metastatic treatment.
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http://dx.doi.org/10.1080/15384101.2015.1026522DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4614356PMC
April 2016

Involvement of Bcl-2-associated transcription factor 1 in the differentiation of early-born retinal cells.

J Neurosci 2014 Jan;34(4):1530-41

Institut de la Vision, INSERM UMR_S968, CNRS UMR 7210, Sorbonne Universités, UPMC Univ Paris 06, 75012 Paris, France, Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 503, 75 571 PARIS Cedex 12, France, CNRS-UMR 3347, INSERM U1021, Université Paris-sud11, Centre Universitaire, 91405 Orsay, France, and Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario M5S 1A8, Canada.

Retinal progenitor proliferation and differentiation are tightly controlled by extrinsic cues and distinctive combinations of transcription factors leading to the generation of retinal cell type diversity. In this context, we have characterized Bcl-2-associated transcription factor (Bclaf1) during rodent retinogenesis. Bclaf1 expression is restricted to early-born cell types, such as ganglion, amacrine, and horizontal cells. Analysis of developing retinas in Bclaf1-deficient mice revealed a reduction in the numbers of retinal ganglion cells, amacrine cells and horizontal cells and an increase in the numbers of cone photoreceptor precursors. Silencing of Bclaf1expression by in vitro electroporation of shRNA in embryonic retina confirmed that Bclaf1 serves to promote amacrine and horizontal cell differentiation. Misexpression of Bclaf1 in late retinal progenitors was not sufficient to directly induce the generation of amacrine and horizontal cells. Domain deletion analysis indicated that the N-terminal domain of Bclaf1 containing an arginine-serine-rich and a bZip domain is required for its effects on retinal cell differentiation. In addition, analysis revealed that Bclaf1 function occurs independently of its interaction with endogenous Bcl-2-related proteins. Altogether, our data demonstrates that Bclaf1expression in postmitotic early-born cells facilitates the differentiation of early retinal precursors into retinal ganglion cells, amacrine cells, and horizontal cells rather than into cone photoreceptors.
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http://dx.doi.org/10.1523/JNEUROSCI.3227-13.2014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6705315PMC
January 2014

Protein tyrosine phosphatase 4A3 (PTP4A3) is required for Xenopus laevis cranial neural crest migration in vivo.

PLoS One 2013 23;8(12):e84717. Epub 2013 Dec 23.

Institut Curie, Research Division, Orsay, France ; CNRS UMR3347, Orsay, France ; INSERM U1021, Orsay, France ; Université Paris Sud, Orsay, France.

Uveal melanoma is the most common intraocular malignancy in adults, representing between about 4% and 5% of all melanomas. High expression levels of Protein Tyrosine Phosphatase 4A3, a dual phosphatase, is highly predictive of metastasis development and PTP4A3 overexpression in uveal melanoma cells increases their in vitro migration and in vivo invasiveness. Melanocytes, including uveal melanocytes, are derived from the neural crest during embryonic development. We therefore suggested that PTP4A3 function in uveal melanoma metastasis may be related to an embryonic role during neural crest cell migration. We show that PTP4A3 plays a role in cephalic neural crest development in Xenopus laevis. PTP4A3 loss of function resulted in a reduction of neural crest territory, whilst gain of function experiments increased neural crest territory. Isochronic graft experiments demonstrated that PTP4A3-depleted neural crest explants are unable to migrate in host embryos. Pharmacological inhibition of PTP4A3 on dissected neural crest cells significantly reduced their migration velocity in vitro. Our results demonstrate that PTP4A3 is required for cephalic neural crest migration in vivo during embryonic development.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0084717PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3871671PMC
October 2014

Patient-derived xenografts recapitulate molecular features of human uveal melanomas.

Mol Oncol 2013 Jun 26;7(3):625-36. Epub 2013 Feb 26.

Institut Curie, Paris, France.

We have previously developed a new method for the development and maintenance of uveal melanoma (UM) xenografts in immunodeficient mice. Here, we compare the genetic profiles of the primary tumors to their corresponding xenografts that have been passaged over time. The study included sixteen primary UMs and corresponding xenografts at very early (P1), early (P4), and late (P9) in vivo passages. The tumors were analyzed for mutation status of GNAQ, GNA11, GNAS, GNA15, BAP1, and BRAF, chromosomal copy number alterations using Affymetrix GeneChip(®) Genome-Wide Human SNP6.0 arrays, gene expression profiles using GeneChip(®) Human Exon 1.0 ST arrays, BAP1 mRNA and protein expression, and MAPK pathway status using Reverse Phase Protein Arrays (RPPA). The UM xenografts accurately recapitulated the genetic features of primary human UMs and they exhibited genetic stability over the course of their in vivo maintenance. Our technique for establishing and maintaining primary UMs as xenograft tumors in immunodeficient mice exhibit a high degree of genetic conservation between the primary tumors and the xenograft tumors over multiple passages in vivo. These models therefore constitute valuable preclinical tool for drug screening in UM.
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http://dx.doi.org/10.1016/j.molonc.2013.02.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4966164PMC
June 2013

Both PAX6 and MITF are required for pigment epithelium development in vivo.

Authors:
Simon Saule

Pigment Cell Melanoma Res 2012 Sep;25(5):541-3

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http://dx.doi.org/10.1111/j.1755-148x.2012.01037.xDOI Listing
September 2012

Vimentin and the K-Ras-induced actin-binding protein control inositol-(1,4,5)-trisphosphate receptor redistribution during MDCK cell differentiation.

J Cell Sci 2012 Nov 3;125(Pt 22):5428-40. Epub 2012 Sep 3.

Laboratory of Proteomic Mass Spectrometry, Institut Curie, 75248 Paris, Cedex 05, France.

Inositol-(1,4,5)-triphosphate receptors (InsP(3)Rs) are ligand-gated Ca(2+) channels that control Ca(2+) release from intracellular stores and play a central role in a wide range of cellular responses. In most epithelial cells, InsP(3)Rs are not uniformly distributed within the endoplasmic reticulum (ER) membrane, with the consequence that agonist stimulation results in compartmentalized Ca(2+) signals. Despite these observations, little is known about the mechanisms that regulate the intracellular localization of InsP(3)Rs. Here, we report that exogenously expressed InsP(3)R1-GFP and endogenous InsP(3)R3 interact with the K-Ras-induced actin-binding protein (KRAP) in both differentiated and undifferentiated Madin-Darby canine kidney (MDCK) cells. KRAP mediates InsP(3)R clustering in confluent MDCK cells and functions as an adapter, linking InsP(3)Rs to vimentin intermediate filaments. Upon epithelial differentiation, KRAP and vimentin are both required for InsP(3)R accumulation at the periphery of MDCK cells. Finally, KRAP associates with vimentin in chicken B lymphocytes and with keratins in a breast cancer cell line devoid of vimentin. Collectively, our data suggest that intermediate filaments in conjunction with KRAP may govern the localization of InsP(3)Rs in a large number of cell types (including epithelial cells) and in various physiological or pathological contexts.
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http://dx.doi.org/10.1242/jcs.108738DOI Listing
November 2012

Genetic determinants of uveal melanoma.

Dev Ophthalmol 2012 21;49:150-165. Epub 2011 Oct 21.

Uveal melanoma (UM) arises from neural crest-derived melanocytes of the choroid and the ciliary body. About 50% of patients develop metastatic disease despite efficient control of the primary tumor. For about 15 years, cytogenetic and, recently, genome-wide analysis techniques have shown that UM can be classified into 2 genomic groups correlating with prognostic clinicopathologic features: class 1 tumors, with a low risk of metastases, typically characterized by a gain of the 6p chromosome arm, often associated with a gain of the distal part of the 8q chromosome arm, and class 2 tumors, with a high metastatic risk, presenting loss of the entire chromosome 3 and gain of the entire 8q, related to the formation of isochromosomes. Genome-wide expression profiling has proved to be a powerful tool for separating these 2 classes. However, despite advances in the genomic and prognostic characterization of UM, the knowledge of pathways deregulated in these tumors is just emerging and, in contrast to cutaneous melanoma, no major predisposing genes are known. Altered or deregulated genes are reviewed in this chapter. Inactivating mutations have recently been identified by exome sequencing in gene BAP1, mapping to 3p21.1, in class 2 tumors. Among other discriminant genes identified from genome-wide expression profiling, PTP4A3, mapping to 8q24.3, coding for a protein promoting cell migration, is highly overexpressed in class 2 tumors. The overall expression signature of class 2 tumors suggests they may originate from neuroectodermal stem cells.
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http://dx.doi.org/10.1159/000328270DOI Listing
February 2012

A SUMOylation-defective MITF germline mutation predisposes to melanoma and renal carcinoma.

Authors:
Corine Bertolotto Fabienne Lesueur Sandy Giuliano Thomas Strub Mahaut de Lichy Karine Bille Philippe Dessen Benoit d'Hayer Hamida Mohamdi Audrey Remenieras Eve Maubec Arnaud de la Fouchardière Vincent Molinié Pierre Vabres Stéphane Dalle Nicolas Poulalhon Tanguy Martin-Denavit Luc Thomas Pascale Andry-Benzaquen Nicolas Dupin Françoise Boitier Annick Rossi Jean-Luc Perrot Bruno Labeille Caroline Robert Bernard Escudier Olivier Caron Laurence Brugières Simon Saule Betty Gardie Sophie Gad Stéphane Richard Jérôme Couturier Bin Tean Teh Paola Ghiorzo Lorenza Pastorino Susana Puig Celia Badenas Hakan Olsson Christian Ingvar Etienne Rouleau Rosette Lidereau Philippe Bahadoran Philippe Vielh Eve Corda Hélène Blanché Diana Zelenika Pilar Galan François Aubin Bertrand Bachollet Céline Becuwe Pascaline Berthet Yves Jean Bignon Valérie Bonadona Jean-Louis Bonafe Marie-Noëlle Bonnet-Dupeyron Fréderic Cambazard Jacqueline Chevrant-Breton Isabelle Coupier Sophie Dalac Liliane Demange Michel d'Incan Catherine Dugast Laurence Faivre Lynda Vincent-Fétita Marion Gauthier-Villars Brigitte Gilbert Florent Grange Jean-Jacques Grob Philippe Humbert Nicolas Janin Pascal Joly Delphine Kerob Christine Lasset Dominique Leroux Julien Levang Jean-Marc Limacher Cristina Livideanu Michel Longy Alain Lortholary Dominique Stoppa-Lyonnet Sandrine Mansard Ludovic Mansuy Karine Marrou Christine Matéus Christine Maugard Nicolas Meyer Catherine Nogues Pierre Souteyrand Laurence Venat-Bouvet Hélène Zattara Valérie Chaudru Gilbert M Lenoir Mark Lathrop Irwin Davidson Marie-Françoise Avril Florence Demenais Robert Ballotti Brigitte Bressac-de Paillerets

Nature 2011 Oct 19;480(7375):94-8. Epub 2011 Oct 19.

1] INSERM, U895 (équipe 1), Equipe labélisée Ligue Contre le Cancer, C3M, 06204 Nice, France [2] Université of Nice Sophia-Antipolis, UFR Médecine, 06204 Nice, France [3] Centre Hospitalier Universitaire de Nice, Service de Dermatologie, 06204 Nice, France [4].

So far, no common environmental and/or phenotypic factor has been associated with melanoma and renal cell carcinoma (RCC). The known risk factors for melanoma include sun exposure, pigmentation and nevus phenotypes; risk factors associated with RCC include smoking, obesity and hypertension. A recent study of coexisting melanoma and RCC in the same patients supports a genetic predisposition underlying the association between these two cancers. The microphthalmia-associated transcription factor (MITF) has been proposed to act as a melanoma oncogene; it also stimulates the transcription of hypoxia inducible factor (HIF1A), the pathway of which is targeted by kidney cancer susceptibility genes. We therefore proposed that MITF might have a role in conferring a genetic predisposition to co-occurring melanoma and RCC. Here we identify a germline missense substitution in MITF (Mi-E318K) that occurred at a significantly higher frequency in genetically enriched patients affected with melanoma, RCC or both cancers, when compared with controls. Overall, Mi-E318K carriers had a higher than fivefold increased risk of developing melanoma, RCC or both cancers. Codon 318 is located in a small-ubiquitin-like modifier (SUMO) consensus site (ΨKXE) and Mi-E318K severely impaired SUMOylation of MITF. Mi-E318K enhanced MITF protein binding to the HIF1A promoter and increased its transcriptional activity compared to wild-type MITF. Further, we observed a global increase in Mi-E318K-occupied loci. In an RCC cell line, gene expression profiling identified a Mi-E318K signature related to cell growth, proliferation and inflammation. Lastly, the mutant protein enhanced melanocytic and renal cell clonogenicity, migration and invasion, consistent with a gain-of-function role in tumorigenesis. Our data provide insights into the link between SUMOylation, transcription and cancer.
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http://dx.doi.org/10.1038/nature10539DOI Listing
October 2011

GLI2 and M-MITF transcription factors control exclusive gene expression programs and inversely regulate invasion in human melanoma cells.

Pigment Cell Melanoma Res 2011 Oct 18;24(5):932-43. Epub 2011 Aug 18.

Institut Curie, Centre de Recherche, Orsay, France.

We recently identified GLI2, the most active of GLI transcription factors, as a direct TGF-β/SMAD target, whose expression in melanoma cells is associated with increased invasiveness and metastatic capacity. In this work, we provide evidence that high GLI2 expression is inversely correlated with that of the melanocyte-specific transcription factor M-microphthalmia transcription factor (M-MITF) and associated transcriptional program. GLI2-expressing cell lines were characterized by the loss of M-MITF-dependent melanocytic differentiation markers and reduced pigmentation. The balance between M-MITF and GLI2 expression did not correlate with the presence or absence of BRAF-activating mutations, but rather was controlled by two distinct pathways: the TGF-β pathway, which favors GLI2 expression, and the protein kinase A (PKA)/cAMP pathway, which pushes the balance toward high M-MITF expression. Furthermore, overexpression and knockdown experiments demonstrated that GLI2 and M-MITF reciprocally repress each other's expression and control melanoma cell invasion in an opposite manner. These findings thus identify GLI2 as a critical transcription factor antagonizing M-MITF function to promote melanoma cell phenotypic plasticity and invasive behavior.
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http://dx.doi.org/10.1111/j.1755-148X.2011.00893.xDOI Listing
October 2011

High PTP4A3 phosphatase expression correlates with metastatic risk in uveal melanoma patients.

Cancer Res 2011 Feb 6;71(3):666-74. Epub 2010 Dec 6.

Institut Curie, Paris, France.

A high percentage of uveal melanoma patients develop metastatic tumors predominantly in the liver. We studied the molecular profiles derived from gene expression microarrays and comparative genomic hybridization microarrays, to identify genes associated with metastasis in this aggressive cancer. We compared 28 uveal melanomas from patients who developed liver metastases within three years of enucleation with 35 tumors from patients without metastases or who developed metastases more than 3 years after enucleation. Protein tyrosine phosphatase type IV A member 3 (PTP4A3/PRL3), was identified as a strong predictor of metastasis occurrence. We demonstrated that the differential expression of this gene, which maps to 8q24.3, was not merely a consequence of 8q chromosome overrepresentation. PTP4A3 overexpression in uveal melanoma cell lines significantly increased cell migration and invasiveness in vivo, suggesting a direct role for this protein in metastasis. Our findings suggest that PTP4A3 or its cellular substrates could constitute attractive therapeutic targets to treat metastatic uveal melanomas.
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http://dx.doi.org/10.1158/0008-5472.CAN-10-0605DOI Listing
February 2011

GLI2-mediated melanoma invasion and metastasis.

J Natl Cancer Inst 2010 Aug 21;102(15):1148-59. Epub 2010 Jul 21.

Curie Institute, INSERM U1021/CNRS UMR3347, University Center, Orsay Cedex, France.

Background: The transforming growth factor-beta (TGF-beta) pathway, which has both tumor suppressor and pro-oncogenic activities, is often constitutively active in melanoma and is a marker of poor prognosis. Recently, we identified GLI2, a mediator of the hedgehog pathway, as a transcriptional target of TGF-beta signaling.

Methods: We used real-time reverse transcription-polymerase chain reaction (RT-PCR) and western blotting to determine GLI2 expression in human melanoma cell lines and subsequently classified them as GLI2high or as GLI2low according to their relative GLI2 mRNA and protein expression levels. GLI2 expression was reduced in a GLI2high cell line with lentiviral expression of short hairpin RNA targeting GLI2. We assessed the role of GLI2 in melanoma cell invasiveness in Matrigel assays. We measured secretion of matrix metalloproteinase (MMP)-2 and MMP-9 by gelatin zymography and expression of E-cadherin by western blotting and RT-PCR. The role of GLI2 in development of bone metastases was determined following intracardiac injection of melanoma cells in immunocompromised mice (n = 5-13). Human melanoma samples (n = 79) at various stages of disease progression were analyzed for GLI2 and E-cadherin expression by immunohistochemistry, in situ hybridization, or RT-PCR. All statistical tests were two-sided.

Results: Among melanoma cell lines, increased GLI2 expression was associated with loss of E-cadherin expression and with increased capacity to invade Matrigel and to form bone metastases in mice (mean osteolytic tumor area: GLI2high vs GLI2low, 2.81 vs 0.93 mm(2), difference = 1.88 mm(2), 95% confidence interval [CI] = 1.16 to 2.60, P < .001). Reduction of GLI2 expression in melanoma cells that had expressed high levels of GLI2 substantially inhibited both basal and TGF-beta-induced cell migration, invasion (mean number of Matrigel invading cells: shGLI2 vs shCtrl (control), 52.6 vs 100, difference = 47.4, 95% CI = 37.0 to 57.8, P = .024; for shGLI2 + TGF-beta vs shCtrl + TGF-beta, 31.0 vs 161.9, difference = -130.9, 95% CI = -96.2 to -165.5, P = .002), and MMP secretion in vitro and the development of experimental bone metastases in mice. Within human melanoma lesions, GLI2 expression was heterogeneous, associated with tumor regions in which E-cadherin was lost and increased in the most aggressive tumors.

Conclusion: GLI2 was directly involved in driving melanoma invasion and metastasis in this preclinical study.
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http://dx.doi.org/10.1093/jnci/djq257DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2914763PMC
August 2010

Down regulation of pRb in cultures of avian neuroretina cells promotes proliferation of reactive Müller-like cells and emergence of retinal stem/progenitors.

Exp Eye Res 2010 Jun 7;90(6):791-801. Epub 2010 Apr 7.

Institut Curie, Centre National de Recherche Scientifique (CNRS) UMR3347, Institut National de la Santé et de Recherche Médicale (INSERM) U1021, Université Paris-Sud 11, Centre Universitaire Orsay, Orsay, France.

The aim of this work was to define the role of pRb depletion in the proliferation and differentiation of avian retinoblasts in vitro. For this purpose vectors expressing pRb short hairpin RNA were used to deplete pRb in cultures of avian neuroretinal cells. Down regulation of pRb was observed by Western blot and quantification of nuclear pRb. Cell proliferation and differentiation were studied following BrdU labeling and immunostaining. Transfection significantly down-regulated pRb in neuroretinal cells. Long-term effect of pRb depletion mainly induced proliferation of epithelial-like cells that expressed markers of reactive Müller glial cells. A minority of these cells that survived passaging could be maintained as neurosphere-like aggregates with low pRb, not observed in control cultures. BrdU labeling followed by a two week chase showed the presence of cells still remained labelled, indicating low cell cycling. Under appropriate conditions, these aggregates differentiate in precursors of amacrine interneurons shown by the expression of AP2, in absence of the photoreceptors marker visinin and the late neuronal marker MAP2. Taken together these data show that decrease pRb level in cultures of avian neuroretinal cells promotes the emergence and proliferation of stem cell/progenitors from reactive-like Muller cells.
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http://dx.doi.org/10.1016/j.exer.2010.03.015DOI Listing
June 2010

Establishment and characterization of a panel of human uveal melanoma xenografts derived from primary and/or metastatic tumors.

Clin Cancer Res 2010 Apr 6;16(8):2352-62. Epub 2010 Apr 6.

Laboratory of Preclinical Investigation, Translational Research Department, Institut Curie, Paris, France.

Purpose: Uveal melanoma is the most common primary intraocular malignant tumor in adults and is defined by a poor natural outcome, as 50% of patients die from metastases. The aim of this study was to develop and characterize a panel of human uveal melanoma xenografts transplanted into immunodeficient mice.

Experimental Design: Ninety tumor specimens were grafted into severe combined immunodeficient mice, and 25 transplantable xenografts were then established (28%). Relationship between tumor graft and clinical, biological, and therapeutic features of the patients included were investigated. Characterization of 16 xenografts included histology, molecular analyses by immunohistochemistry, genetic alteration analysis (single-nucleotide polymorphism), and specific tumor antigen expression by quantitative reverse transcription-PCR. Pharmacologic characterization (chemosensitivity) was also done in four models using two drugs, temozolomide and fotemustine, currently used in the clinical management of uveal melanoma.

Results: Take rate of human uveal melanoma was 28% (25 of 90). Tumor take was independent of size, histologic parameters, or chromosome 3 monosomy but was significantly higher in metastatic tumors. Interestingly, in vivo tumor growth was prognostic for a lower metastasis-free survival in patients with primary tumors. A high concordance between the patients' tumors and their corresponding xenografts was found for all parameters tested (histology, genetic profile, and tumor antigen expression). Finally, the four xenografts studied displayed different response profiles to chemotherapeutic agents.

Conclusions: Based on these results, this panel of 16 uveal melanoma xenografts represents a useful preclinical tool for both pharmacologic and biological assessments.
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http://dx.doi.org/10.1158/1078-0432.CCR-09-3066DOI Listing
April 2010

Genomic profiling and identification of high-risk uveal melanoma by array CGH analysis of primary tumors and liver metastases.

Invest Ophthalmol Vis Sci 2009 Jun 17;50(6):2572-80. Epub 2009 Jan 17.

Department of Bioinformatics, Institut Curie, Paris, France.

Purpose: Incurable metastases develop in approximately 50% of patients with uveal melanoma (UM). The purpose of this study was to analyze genomic profiles in a large series of ocular tumors and liver metastases and design a genome-based classifier for metastatic risk assessment.

Methods: A series of 86 UM tumors and 66 liver metastases were analyzed by using a BAC CGH (comparative genomic hybridization) microarray. A clustering was performed, and correlation with the metastatic status was sought among a subset of 71 patients with a minimum follow-up of 24 months. The status of chromosome 3 was further examined in the tumors, and metastases with disomy 3 were checked with an SNP microarray. A prognostic classifier was constructed using a log-linear model on minimal regions and leave-one-out cross-validation.

Results: The clustering divides the groups of tumors with disomy 3 and monosomy 3 into two and three subgroups, respectively. Same subgroups are found in primary tumors and in metastases, but with different frequencies. Isolated monosomy 3 was present in 0% of metastatic ocular tumors and in 3% of metastases. The highest metastatic rate in ocular tumors was observed in a subgroup defined by the gain of 8q with a proximal breakpoint, and losses of 3, 8p, and 16q, also most represented in metastases. A prognostic classifier that included the status of these markers led to an 85.9% classification accuracy.

Conclusions: The analysis of the status of these specific chromosome regions by genome profiling on SNP microarrays should be a reliable tool for identifying high-risk patients in future adjuvant therapy protocols.
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http://dx.doi.org/10.1167/iovs.08-2296DOI Listing
June 2009

Relationship of Pax6 activity levels to the extent of eye development in the mouse, Mus musculus.

Genetics 2008 Jul 18;179(3):1345-55. Epub 2008 Jun 18.

Institute of Human Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, D-85764 Neuherberg, Germany.

In this study we extend the mouse Pax6 mutant allelic series to include a homozygous and hemizygous viable hypomorph allele. The Pax6(132-14Neu) allele is a Phe272Ile missense mutation within the third helix of the homeodomain. The mutant Pax6 homeodomain shows greatly reduced binding activity to the P3 DNA binding target. Glucagon-promoter activation by the entire mutant Pax6 product of a reporter gene driven by the G1 paired and homeodomain DNA binding target was slightly increased. We constructed mutant Pax6 genotypes such that Pax6 activity ranged between 100 and 0% and show that the extent of eye development is progressively reduced as Pax6 activity decreased. Two apparent thresholds identify three groups in which the extent of eye development abruptly shifted from complete eye at the highest levels of Pax6 to a rudimentary eye at intermediate levels of Pax6 to very early termination of eye development at the lowest levels of Pax6. Of the two Pax6-positive regions that participate in eye development, the surface ectoderm, which develops into the lens vesicle and the cornea, is more sensitive to reduced levels of Pax6 activity than the optic vesicle, which develops into the inner and outer retinal layers.
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http://dx.doi.org/10.1534/genetics.108.088591DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2475738PMC
July 2008

Pax6p46 binds chromosomes in the pericentromeric region and induces a mitosis defect when overexpressed.

Invest Ophthalmol Vis Sci 2007 Dec;48(12):5408-19

Institut Curie, Centre National de la Recherche Scientifique (CNRS) UMR 146, Centre Universitaire Orsay, Orsay, France.

Purpose: Haploinsufficiency and overexpression of the Pax6 gene are responsible for defective central nervous system development. The purpose of the current work was to identify and characterize a new potential role for the Pax6 transcription factor in cellular proliferation in addition to its role at the level of gene expression.

Methods: Expression vectors encoding tagged Pax6p46 protein were used to observe directly protein localization during the cell cycle in cells lines. Three dimensional (3-D) fluorescence microscopy imaging was used to observe in vivo mitotic progression and chromosome dynamics to define the mitotic step affected by p46DsRed as well as to validate endogenous p46 localization on chromosomes in quail retinal cells. Video imaging was used to identify the precise moment of onset of effects related to p46 overexpression in living cells. A pulldown assay in HEK cells was used to identify a specific partner of p46.

Results: Pax6p46 protein in transfected cells is localized on the chromosomes, predominantly in a pericentromeric area, and its localization changes as mitosis progresses. Overexpression of p46 protein induces incomplete chromatid separation, resulting in defective mitosis at the onset of the anaphase. A physical interaction between p46 and ESPL1 was identified.

Conclusions: The results suggest that Pax6 exerts an effect on mitosis through protein-protein interactions with proteins localized on chromosomes. Supported by the observation that p46 interacts with separase, an enzyme required for chromatid separation, the authors propose that this interaction is responsible for the mitosis defect observed in cells overexpressing Pax6.
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http://dx.doi.org/10.1167/iovs.07-0413DOI Listing
December 2007

Nuclear addressing provides a clue for the transforming activity of amino-truncated CCN3 proteins.

J Cell Biochem 2006 Sep;99(1):105-16

Université Paris7-D. Diderot, UFR de Biochimie, Laboratoire d'Oncologie Virale et Moléculaire, 2 Place Jussieu, 75005 Paris, France.

CCN3 is a founding member of the CCN (Cyr61, Ctgf, Nov) family of cell growth and differentiation regulators. These secreted proteins are key regulators in embryonic development, and are associated with severe pathologies including fibrotic diseases and cancers. CCN3 was discovered as a MAV integration site in an avian nephroblastoma. Previous work established that the amino-truncated protein expressed in this tumor was inducing morphological transformation of chicken embryo fibroblasts, whereas the full-length secreted CCN3 protein was inhibiting cell growth. Amino-truncated variants were identified in cancer cell lines. Since the lack of signal peptide was expected to alter the fate of the truncated proteins, we hypothesized that modifications of CCN3 subcellular addressing could be responsible for the oncogenic activities of CCN3. The CCN proteins are composed of four structural modules (IGFBP, TSP1, VWC, and CT). We report that amino-truncated variants of CCN3 are addressed to the nucleus and that the carboxyterminal (CT) module of CCN3 is responsible for the nuclear addressing. Furthermore, our data identify nuclear CCN3 variants as potential transcriptional regulators. In this context, the CT module confers on nuclear CCN3 proteins a negative regulatory effect on transcription. We propose that the nuclear localization of amino-truncated CCN3 proteins be correlated to oncogenicity.
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http://dx.doi.org/10.1002/jcb.20887DOI Listing
September 2006

Protein interaction mapping: a Drosophila case study.

Genome Res 2005 Mar 14;15(3):376-84. Epub 2005 Feb 14.

Hybrigenics, 75014 Paris, France.

The Drosophila (fruit fly) model system has been instrumental in our current understanding of human biology, development, and diseases. Here, we used a high-throughput yeast two-hybrid (Y2H)-based technology to screen 102 bait proteins from Drosophila melanogaster, most of them orthologous to human cancer-related and/or signaling proteins, against high-complexity fly cDNA libraries. More than 2300 protein-protein interactions (PPI) were identified, of which 710 are of high confidence. The computation of a reliability score for each protein-protein interaction and the systematic identification of the interacting domain combined with a prediction of structural/functional motifs allow the elaboration of known complexes and the identification of new ones. The full data set can be visualized using a graphical Web interface, the PIMRider (http://pim.hybrigenics.com), and is also accessible in the PSI standard Molecular Interaction data format. Our fly Protein Interaction Map (PIM) is surprisingly different from the one recently proposed by Giot et al. with little overlap between the two data sets. Analysis of the differences in data sets and methods suggests alternative strategies to enhance the accuracy and comprehensiveness of the post-genomic generation of broad-scale protein interaction maps.
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http://dx.doi.org/10.1101/gr.2659105DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC551564PMC
March 2005

Pax6 interacts with cVax and Tbx5 to establish the dorsoventral boundary of the developing eye.

J Biol Chem 2004 Nov 18;279(45):47272-7. Epub 2004 Aug 18.

CNRS UMR 146, Institut Curie Section de Recherche, Bātiment 110, Centre Universitaire, 91405 Orsay Cedex, France.

Dorsoventral pattern formation of the optic cup is essential for vertebrate eye morphogenesis and retinotectal topographic mapping. Dorsal and ventral aspects of the eye are distinct at early stages of development; cVax homeodomain protein expression is confined to the ventral optic cup, whereas Tbx5 (T-box transcription factor) expression domain becomes restricted to the dorsal region. Misexpression of cVax or Tbx5 induces profound defects in eye morphology and abnormal visual projections. In the Pax6-/- mutant Tbx5 fails to be expressed, and Vax1 and -2 are abnormally present in the entire optic vesicle. During eye development Pax6 becomes expressed in a gradient at the optic cup stage due to the specific activation of a highly conserved intronic alpha enhancer in the Pax6 locus. We observed that the highest level of Pax6 in the optic cup corresponds to the boundary between non-overlapping cVax and Tbx5 territories. To further investigate how these transcription factors control the patterning of the eye, we overexpressed Pax6 in the chick optic cup (E2) using in ovo electroporation. We observed that overexpression of Pax6 extends the Tbx5 and Bmp4 domains but reduces the cVax expression domains in the E3 chick eye. This results in an abnormal eye phenotype at E4. In addition, we showed that cVax and Tbx5 interact with Pax6 and modulate in an opposite manner the activity of the Pax6 alpha enhancer. Moreover, the Pax6/cVax interaction inhibits the transactivation properties of Pax6. These results demonstrate that Pax6 together with cVax and Tbx5 mediate dorsoventral patterning of the eye.
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http://dx.doi.org/10.1074/jbc.M406624200DOI Listing
November 2004

Microphthalmia transcription factor induces both retinal pigmented epithelium and neural crest melanocytes from neuroretina cells.

J Biol Chem 2004 Oct 23;279(40):41911-7. Epub 2004 Jul 23.

UMR 146, Institut Curie Section de Recherche, Bātiment 110, Centre Universitaire, 91405 Orsay Cedex, France.

Mitf encodes a basic helix-loop-helix transcription factor that plays an essential role in the differentiation of the retinal pigmented epithelium (RPE) and neural crest-derived melanocytes. As cells containing melanogenic enzymes (TRP2) are found in Mitf mouse mutants, it is not clear whether Mitf is a downstream factor or a master regulator of melanocyte differentiation. To further study the role of Mitf in committing cells to the melanocyte lineage, we express Mitf in the cultured quail neuroretina cells. This leads to the induction of two types of pigmented cells: neural crest-derived melanocytes, according to their dendritic morphology, physiology, and gene expression pattern are observed together with pigmented epithelial RPE-like cells. The expression of Mitf is lower in pigmented epithelial RPE-like cells than in neural crest-derived melanocytes. Accordingly, overexpression of Mitf in cultured quail RPE causes cells to develop into neural crest-like pigmented cells. Thus, Mitf is sufficient for the proper differentiation of crest-like pigmented cells from retinal cells and its expression level may determine the type of pigment cell induced.
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http://dx.doi.org/10.1074/jbc.M404964200DOI Listing
October 2004

Microphthalmia transcription factor analysis in posterior uveal melanomas.

Exp Eye Res 2003 Jun;76(6):653-61

Service d'ophtalmologie, Centre Hopitalier de Lens, Route de La Bassée, Lens 62307, France.

Purpose: The protein encoded by the Microphthalmia gene (MITF) is a transcription factor essential for the development and survival of melanocytes. It serves as a master regulator in modulating extracellular signals. Because of its central role in melanocytes survival and to assess its potential use as a histopathological marker for melanoma, MITF expression was examined in human choroidal melanomas.

Methods: Fifty-seven paraffin-embedded sections of choroidal melanoma specimens and 1 choroidal melanoma cell line were analyzed using immunochemistry and RT-PCR. Normal choroids and normal choroidal melanocyte cells were used as control.

Results: Sixty-five percent of the tumoral specimens stained positively for MITF with a predominant nuclear pattern of reactivity. MITF-M and MITF-A isoforms were detected by RT-PCR in all specimens examined. Using a chimeric protein resulting from the fusion of each Mitf protein with the GFP, Mitf-M exhibited an exclusive nuclear staining whereas Mitf-A exhibited a mixed nuclear and cytoplasmic staining. No correlation between MITF-positivity and parameters such as cell type, largest tumor diameter, sclera invasion, mitotic figures was observed. In contrast, a significant negative association was found between MITF staining and the pigmentation (p=0.02) and a positive correlation between MITF staining and the proliferative marker Ki67 was found (p=0.02).

Conclusion: MITF may be implicated in choroidal melanoma pigmentation and proliferation. Further analysis should provide new insights into the mechanisms underlying the molecular and cellular changes of choroidal melanomas.
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http://dx.doi.org/10.1016/s0014-4835(03)00082-4DOI Listing
June 2003

Expression of the c-kit receptor in choroidal melanomas.

Melanoma Res 2003 Apr;13(2):161-6

Department of Ophthalmology, Lens Hospital, 62307 Lens, France.

The KIT gene encodes c-kit, a transmembrane receptor that has tyrosine kinase activity and plays a role in haematopoiesis, gametogenesis and melanogenesis. The c-kit protein is found in normal cutaneous and choroidal melanocytes, and there is evidence that expression is lost in melanoma. Expression of c-kit was analysed in 57 paraffin-embedded sections of choroidal melanoma specimens and three choroidal melanoma cell lines using immunochemistry and Western blotting. Of the tumour specimens, 75% stained positively for c-kit with a membrane pattern of reactivity. Of the six patients who underwent proton beam therapy before enucleation, five tumours exhibited no c-kit immunoreactivity and the other tumour demonstrated weak staining. Of the three melanoma cell lines used, c-kit expression was observed in only one. No correlations between c-kit positivity and parameters such as cell type, largest macroscopic tumour dimension, scleral invasion or pigmentation were observed. In contrast, a significant positive association was found between c-kit staining and mitotic activity (P = 0.02). However, c-kit expression did not significantly influence survival when evaluated by univariate analysis. In conclusion, c-kit is expressed in most choroidal melanoma tumours. Further analysis should provide new insights into the mechanisms underlying the molecular and cellular changes in choroidal melanomas.
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http://dx.doi.org/10.1097/00008390-200304000-00008DOI Listing
April 2003

OTX2 activates the molecular network underlying retina pigment epithelium differentiation.

J Biol Chem 2003 Jun 27;278(24):21721-31. Epub 2003 Mar 27.

Instituto Cajal, Consejo Superior de Investigaciones Científicas, Dr. Arce 37, Madrid 28002, Spain.

The retina pigment epithelium (RPE) is fundamental for the development and function of the vertebrate eye. Molecularly, the presumptive RPE can be identified by the early expression of two transcription factors, Mitf and Otx. In mice deficient for either gene, RPE development is impaired with loss of melanogenic gene expression, raising the possibility that in the eye OTX proteins operate either in a feedback loop or in cooperation with MITF for the control of RPE-specific gene expression. Here we show that Otx2 induces a pigmented phenotype when overexpressed in avian neural retina cells. In addition, OTX2 binds specifically to a bicoid motif present in the promoter regions of three Mitf target genes, QNR71, TRP-1, and tyrosinase, leading to their transactivation. OTX2 and MITF co-localize in the nuclei of RPE cells and physically interact, and their co-expression results in a cooperative activation of QNR71 and tyrosinase promoters. Collectively, these data suggest that both transcription factors operate at the same hierarchical level to establish the identity of the RPE.
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http://dx.doi.org/10.1074/jbc.M301708200DOI Listing
June 2003

Activated MAPK/ERK kinase (MEK-1) induces transdifferentiation of pigmented epithelium into neural retina.

Dev Biol 2002 Aug;248(2):251-64

CNRS UMR 146, Institut Curie, Centre Universitaire, Laboratoire 110, 91405 Orsay Cedex, France.

During vertebrate eye development, the optic vesicle originating from the neuroectoderm is partitioned into a domain that will give rise to the neural retina (NR) and another that will give rise to the retinal pigmented epithelium (RPE). Previous studies have shown that ectopic expression of FGFs in the RPE induces RPE-to-NR transdifferentiation. Similarly, a naturally occurring mutation of the transcription factor Mitf in mouse resulted in the formation of a second neural retina in place of the dorsal RPE, but the putative signaling pathway linking FGF to Mitf regulation is presently unknown. In cultures of neural crest-derived melanocytes, the MAPK pathway was recently shown to target the Mitf transcription factor for ubiquitin-dependent proteolysis, resulting in a rapid degradation and downregulation. In the present study, we show that ectopic expression of a constitutively activated allele of MEK-1, the immediate upstream activator of the MAPK ERK, in chicken embryonic retina in ovo, induces transdifferentiation of the RPE into a neural-like epithelium that is correlated with a downregulation of Mitf expression in the presumptive RPE.
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http://dx.doi.org/10.1006/dbio.2002.0736DOI Listing
August 2002