Développement Normal et Pathologique des Mélanocytes

Publications de l’équipe

Année de publication : 2015

Ikrame Lazar, Emily Clement, Manuelle Ducoux-Petit, Laurence Denat, Vanessa Soldan, Stéphanie Dauvillier, Stéphanie Balor, Odile Burlet-Schiltz, Lionel Larue, Catherine Muller, Laurence Nieto (2015 May 8)

Proteome characterization of melanoma exosomes reveals a specific signature for metastatic cell lines.

Pigment cell & melanoma research : 464-75 : DOI : 10.1111/pcmr.12380 En savoir plus
Résumé

Exosomes are important mediators in cell-to-cell communication and, recently, their role in melanoma progression has been brought to light. Here, we characterized exosomes secreted by seven melanoma cell lines with varying degrees of aggressivity. Extensive proteomic analysis of their exosomes confirmed the presence of characteristic exosomal markers as well as melanoma-specific antigens and oncogenic proteins. Importantly, the protein composition differed among exosomes from different lines. Exosomes from aggressive cells contained specific proteins involved in cell motility, angiogenesis, and immune response, while these proteins were less abundant or absent in exosomes from less aggressive cells. Interestingly, when exposed to exosomes from metastatic lines, less aggressive cells increased their migratory capacities, likely due to transfer of pro-migratory exosomal proteins to recipient cells. Hence, this study shows that the specific protein composition of melanoma exosomes depends on the cells’ aggressivity and suggests that exosomes influence the behavior of other tumor cells and their microenvironment.

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Leslie Yewakon Gandji, Richard Proust, Lionel Larue, Franck Gesbert (2015 Apr 16)

The tyrosine phosphatase SHP2 associates with CUB domain-containing protein-1 (CDCP1), regulating its expression at the cell surface in a phosphorylation-dependent manner.

PloS one : e0123472 : DOI : 10.1371/journal.pone.0123472 En savoir plus
Résumé

CUB domain-containing protein-1 (CDCP1) is a transmembrane glycoprotein that is phosphorylated by SRC family kinases (SFK) before recruiting and activating PKCδ. CDCP1 is overproduced in many cancers. It promotes metastasis and resistance to anoïkis. The robust production of CDCP1 would be associated with stemness and has been proposed as a novel prognosis marker. The natural transmembrane location of CDCP1 makes it an ideal therapeutic target and treatments based on the use of appropriate antibodies are currently being evaluated. However, we still know very little about the molecular fate of CDCP1 and its downstream signaling events. Improvements in our understanding of the molecular events occurring downstream of CDCP1 are required to make use of changes of CDCP1 production or functions for therapeutic purposes. By the mean of co-immunoprecipitation and affinity precipitation we show here, for the first time, that CDCP1 interacts directly, with the cytosolic tyrosine phosphatase SHP2. Point mutants of CDCP1 show that residues Y734 and Y743 are responsible for its interaction with SHP2. It may therefore compete with SFK. We also demonstrate that a shRNA-mediated down regulation of SHP2 is associated with a stronger CDCP1 phosphorylation and an impairment of antibody-mediated CDCP1 internalization.

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Roselyne Y Wagner, Flavie Luciani, Muriel Cario-André, Alain Rubod, Valérie Petit, Laila Benzekri, Khaled Ezzedine, Sébastien Lepreux, Eirikur Steingrimsson, A Taieb, Yvon Gauthier, Lionel Larue, Véronique Delmas (2015 Jan 31)

Altered E-Cadherin Levels and Distribution in Melanocytes Precede Clinical Manifestations of Vitiligo.

The Journal of investigative dermatology : 1810-9 : DOI : 10.1038/jid.2015.25 En savoir plus
Résumé

Vitiligo is the most common depigmenting disorder resulting from the loss of melanocytes from the basal epidermal layer. The pathogenesis of the disease is likely multifactorial and involves autoimmune causes, as well as oxidative and mechanical stress. It is important to identify early events in vitiligo to clarify pathogenesis, improve diagnosis, and inform therapy. Here, we show that E-cadherin (Ecad), which mediates the adhesion between melanocytes and keratinocytes in the epidermis, is absent from or discontinuously distributed across melanocyte membranes of vitiligo patients long before clinical lesions appear. This abnormality is associated with the detachment of the melanocytes from the basal to the suprabasal layers in the epidermis. Using human epidermal reconstructed skin and mouse models with normal or defective Ecad expression in melanocytes, we demonstrated that Ecad is required for melanocyte adhesiveness to the basal layer under oxidative and mechanical stress, establishing a link between silent/preclinical, cell-autonomous defects in vitiligo melanocytes and known environmental stressors accelerating disease expression. Our results implicate a primary predisposing skin defect affecting melanocyte adhesiveness that, under stress conditions, leads to disappearance of melanocytes and clinical vitiligo. Melanocyte adhesiveness is thus a potential target for therapy aiming at disease stabilization.

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Année de publication : 2014

Matthieu Bertrand, Valérie Petit, Ashish Jain, Raymonde Amsellem, Terje Johansen, Lionel Larue, Patrice Codogno, Isabelle Beau (2014 Dec 16)

SQSTM1/p62 regulates the expression of junctional proteins through epithelial-mesenchymal transition factors.

Cell cycle (Georgetown, Tex.) : 364-74 : DOI : 10.4161/15384101.2014.987619 En savoir plus
Résumé

The epithelial to mesenchymal transition (EMT) is an essential process during development and during tumor progression. Here, we observed the accumulation of the selective autophagy receptor and signaling adaptor sequestosome-1 (SQSTM1/p62) during growth factor-induced EMT in immortalized and tumor-derived epithelial cell lines. Modulation of the p62 level regulated the expression of junctional proteins. This effect was dependent on the ubiquitin-associated domain of p62, which stabilized the TGFβ/Smad signaling co-activator Smad4 and the EMT transcription factor Twist. This study highlights a novel function of p62 in a major epithelial phenotypic alteration.

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Cheng-Feng Zhang, Florian Gruber, Chunya Ni, Michael Mildner, Ulrich Koenig, Susanne Karner, Caterina Barresi, Heidemarie Rossiter, Marie-Sophie Narzt, Ionela M Nagelreiter, Lionel Larue, Desmond J Tobin, Leopold Eckhart, Erwin Tschachler (2014 Oct 8)

Suppression of autophagy dysregulates the antioxidant response and causes premature senescence of melanocytes.

The Journal of investigative dermatology : 1348-57 : DOI : 10.1038/jid.2014.439 En savoir plus
Résumé

Autophagy is the central cellular mechanism for delivering organelles and cytoplasm to lysosomes for degradation and recycling of their molecular components. To determine the contribution of autophagy to melanocyte (MC) biology, we inactivated the essential autophagy gene Atg7 specifically in MCs using the Cre-loxP system. This gene deletion efficiently suppressed a key step in autophagy, lipidation of microtubule-associated protein 1 light chain 3 beta (LC3), in MCs and induced slight hypopigmentation of the epidermis in mice. The melanin content of hair was decreased by 10-15% in mice with autophagy-deficient MC as compared with control animals. When cultured in vitro, MCs from mutant and control mice produced equal amounts of melanin per cell. However, Atg7-deficient MCs entered into premature growth arrest and accumulated reactive oxygen species (ROS) damage, ubiquitinated proteins, and the multi-functional adapter protein SQSTM1/p62. Moreover, nuclear factor erythroid 2-related factor 2 (Nrf2)-dependent expression of NAD(P)H dehydrogenase, quinone 1, and glutathione S-transferase Mu 1 was increased, indicating a contribution of autophagy to redox homeostasis in MCs. In summary, the results of our study suggest that Atg7-dependent autophagy is dispensable for melanogenesis but necessary for achieving the full proliferative capacity of MCs.

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Franck Gesbert, Lionel Larue (2014 Jul 2)

Non-thermal plasmas: novel preventive and curative therapy against melanomas?

Experimental dermatology : 716-7 : DOI : 10.1111/exd.12481 En savoir plus
Résumé

Malignant melanoma is a very aggressive cancer with a very poor short-term prognosis once metastatic. For years, there was no efficient adjuvant therapy after surgery. Chemotherapy and immunotherapy provided hope, but not victory. Further efforts are therefore required, to find new ways to cure this disease. Physics has, once again, opened up new possibilities for treatment, through the use of non-equilibrium atmospheric pressure plasma (NEAPP). The curative potential of this technique was initially assessed on cancer cells, among which melanoma. In a recent issue, Yajima et al. use NEAPP on benign nevi, as a preventive treatment.

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Florian Rambow, Audrey Bechadergue, Gaelle Saintigny, Frédérique Morizot, Christian Mahé, Lionel Larue (2014 May 28)

miR-330-5p targets tyrosinase and induces depigmentation.

The Journal of investigative dermatology : 2846-9 : DOI : 10.1038/jid.2014.231 En savoir plus
Résumé

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Daniel J Coleman, Gloria Garcia, Stephen Hyter, Hyo Sang Jang, Sharmeen Chagani, Xiaobo Liang, Lionel Larue, Gitali Ganguli-Indra, Arup K Indra (2014 May 10)

Retinoid-X-receptors (α/β) in melanocytes modulate innate immune responses and differentially regulate cell survival following UV irradiation.

PLoS genetics : e1004321 : DOI : 10.1371/journal.pgen.1004321 En savoir plus
Résumé

Understanding the molecular mechanisms of ultraviolet (UV) induced melanoma formation is becoming crucial with more reported cases each year. Expression of type II nuclear receptor Retinoid-X-Receptor α (RXRα) is lost during melanoma progression in humans. Here, we observed that in mice with melanocyte-specific ablation of RXRα and RXRβ, melanocytes attract fewer IFN-γ secreting immune cells than in wild-type mice following acute UVR exposure, via altered expression of several chemoattractive and chemorepulsive chemokines/cytokines. Reduced IFN-γ in the microenvironment alters UVR-induced apoptosis, and due to this, the survival of surrounding dermal fibroblasts is significantly decreased in mice lacking RXRα/β. Interestingly, post-UVR survival of the melanocytes themselves is enhanced in the absence of RXRα/β. Loss of RXRs α/β specifically in the melanocytes results in an endogenous shift in homeostasis of pro- and anti-apoptotic genes in these cells and enhances their survival compared to the wild type melanocytes. Therefore, RXRs modulate post-UVR survival of dermal fibroblasts in a « non-cell autonomous » manner, underscoring their role in immune surveillance, while independently mediating post-UVR melanocyte survival in a « cell autonomous » manner. Our results emphasize a novel immunomodulatory role of melanocytes in controlling survival of neighboring cell types besides controlling their own, and identifies RXRs as potential targets for therapy against UV induced melanoma.

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G Denecker, N Vandamme, O Akay, D Koludrovic, J Taminau, K Lemeire, A Gheldof, B De Craene, M Van Gele, L Brochez, G M Udupi, M Rafferty, B Balint, W M Gallagher, G Ghanem, D Huylebroeck, J Haigh, J van den Oord, L Larue, I Davidson, J-C Marine, G Berx (2014 Apr 29)

Identification of a ZEB2-MITF-ZEB1 transcriptional network that controls melanogenesis and melanoma progression.

Cell death and differentiation : 1250-61 : DOI : 10.1038/cdd.2014.44 En savoir plus
Résumé

Deregulation of signaling pathways that control differentiation, expansion and migration of neural crest-derived melanoblasts during normal development contributes also to melanoma progression and metastasis. Although several epithelial-to-mesenchymal (EMT) transcription factors, such as zinc finger E-box binding protein 1 (ZEB1) and ZEB2, have been implicated in neural crest cell biology, little is known about their role in melanocyte homeostasis and melanoma. Here we show that mice lacking Zeb2 in the melanocyte lineage exhibit a melanoblast migration defect and, unexpectedly, a severe melanocyte differentiation defect. Loss of Zeb2 in the melanocyte lineage results in a downregulation of the Microphthalmia-associated transcription factor (Mitf) and melanocyte differentiation markers concomitant with an upregulation of Zeb1. We identify a transcriptional signaling network in which the EMT transcription factor ZEB2 regulates MITF levels to control melanocyte differentiation. Moreover, our data are also relevant for human melanomagenesis as loss of ZEB2 expression is associated with reduced patient survival.

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Madeleine Le Coz, Alexandre Benmerah, Lionel Larue (2014 Apr 25)

Quiescent melanocytes form primary cilia.

Experimental dermatology : 426-7 : DOI : 10.1111/exd.12426 En savoir plus
Résumé

We show, for the first time, that melanocytes can form a primary cilium in vitro, corresponding to an immotile or sensory cilium. Such cilia are observed when melanocytes reach confluence or when medium nutrient levels are insufficient. This observation should greatly improve our understanding of the signal transduction processes potentially occurring in these cells during embryonic development, homeostasis in adulthood and melanomagenesis.

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Mélanie J Domingues, Florian Rambow, Bastien Job, Laura Papon, Wanguo Liu, Lionel Larue, Jacky Bonaventure (2014 Feb 10)

β-catenin inhibitor ICAT modulates the invasive motility of melanoma cells.

Cancer research : 1983-95 : DOI : 10.1158/0008-5472.CAN-13-0920 En savoir plus
Résumé

Inhibitor of β-catenin and TCF (ICAT) inhibits β-catenin transcriptional activity by competing with T-cell factor/lymphoid enhancer factor. We documented high ICAT levels in human melanoma cells, in which β-catenin signaling is frequently deregulated, finding a correlation with the capacity to form metastases in nude mice. Ectopic expression of ICAT in melanoma cells did not affect their proliferation but increased cell motility and Matrigel invasion of metastatic cells in a manner relying upon stable ICAT-β-catenin interaction. This effect was associated with conversion of an elongated/mesenchymal phenotype to a round/amoeboid phenotype in the absence of similar effects on elongated morphology of nonmetastatic melanoma cells. Transition from mesenchymal to amoeboid movement was associated with decreased levels of NEDD9 and activated Rac1, a positive regulator of mesenchymal movement. Ectopic ICAT promoted colonization of melanoma cells in the lungs of nude mice, suggesting an increase in metastatic potential. Together, our results showed that by downregulating Rac signaling in metastatic melanoma cells, ICAT increased their invasive motility by promoting a morphologic variation that facilitates a favorable adaptation to their microenvironment.

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Année de publication : 2013

Alejandro Conde-Perez, Lionel Larue (2013 Dec 18)

Human relevance of NRAS/BRAF mouse melanoma models.

European journal of cell biology : 82-6 : DOI : 10.1016/j.ejcb.2013.10.010 En savoir plus
Résumé

Melanoma is a major problem for many individuals worldwide. Although no effective treatment is available, promising new strategies are being developed. A better understanding of the inner workings of the disease would undoubtedly lead to improved treatments. Mouse melanoma models have been used to elucidate many key regulatory pathways involved in melanoma initiation and progression, and models with mutations in the oncogenes RAF and RAS have been particularly informative. Here, we summarize and evaluate the human relevance of various RAF and RAS mouse melanoma models and their contribution to our understanding of melanoma.

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Fabrice P Cordelières, Valérie Petit, Mayuko Kumasaka, Olivier Debeir, Véronique Letort, Stuart J Gallagher, Lionel Larue (2013 Dec 7)

Automated cell tracking and analysis in phase-contrast videos (iTrack4U): development of Java software based on combined mean-shift processes.

PloS one : e81266 : DOI : 10.1371/journal.pone.0081266 En savoir plus
Résumé

Cell migration is a key biological process with a role in both physiological and pathological conditions. Locomotion of cells during embryonic development is essential for their correct positioning in the organism; immune cells have to migrate and circulate in response to injury. Failure of cells to migrate or an inappropriate acquisition of migratory capacities can result in severe defects such as altered pigmentation, skull and limb abnormalities during development, and defective wound repair, immunosuppression or tumor dissemination. The ability to accurately analyze and quantify cell migration is important for our understanding of development, homeostasis and disease. In vitro cell tracking experiments, using primary or established cell cultures, are often used to study migration as cells can quickly and easily be genetically or chemically manipulated. Images of the cells are acquired at regular time intervals over several hours using microscopes equipped with CCD camera. The locations (x,y,t) of each cell on the recorded sequence of frames then need to be tracked. Manual computer-assisted tracking is the traditional method for analyzing the migratory behavior of cells. However, this processing is extremely tedious and time-consuming. Most existing tracking algorithms require experience in programming languages that are unfamiliar to most biologists. We therefore developed an automated cell tracking program, written in Java, which uses a mean-shift algorithm and ImageJ as a library. iTrack4U is a user-friendly software. Compared to manual tracking, it saves considerable amount of time to generate and analyze the variables characterizing cell migration, since they are automatically computed with iTrack4U. Another major interest of iTrack4U is the standardization and the lack of inter-experimenter differences. Finally, iTrack4U is adapted for phase contrast and fluorescent cells.

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S J Gallagher, F Rambow, M Kumasaka, D Champeval, A Bellacosa, V Delmas, L Larue (2013 Apr 25)

Beta-catenin inhibits melanocyte migration but induces melanoma metastasis.

Oncogene : 2230-8 : DOI : 10.1038/onc.2012.229 En savoir plus
Résumé

The canonical Wnt signalling pathway induces the β-catenin/lymphoid enhancer factor transcription factors. It is activated in various cancers, most characteristically carcinomas, in which it promotes metastatic spread by increasing migration and/or invasion. The Wnt/β-catenin signalling pathway is frequently activated in melanoma, but the presence of β-catenin in the nucleus does not seem to be a sign of aggressiveness in these tumours. We found that, unlike its positive role in stimulating migration and invasion of carcinoma cells, β-catenin signalling decreased the migration of melanocytes and melanoma cell lines. In vivo, β-catenin signalling in melanoblasts reduced the migration of these cells, causing a white belly-spot phenotype. The inhibition by β-catenin of migration was dependent on MITF-M, a key transcription factor of the melanocyte lineage, and CSK, an Src-inhibitor. Despite reducing migration, β-catenin signalling promoted lung metastasis in the NRAS-driven melanoma murine model. Thus, β-catenin may have conflicting roles in the metastatic spread of melanoma, repressing migration while promoting metastasis. These results highlight that metastasis formation requires a series of successful cellular processes, any one of which may not be optimally efficient.

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Mélanie J Domingues, Lionel Larue, Jacky Bonaventure (2013 Apr 3)

[Migration of melanocytic lineage-derived cells].

Médecine sciences : M/S : 287-92 : DOI : 10.1051/medsci/2013293015 En savoir plus
Résumé

During development, neural crest cells-derived melanoblasts migrate along the dorso-lateral axis into the dermis, then cross the basal layer to reach the epidermis and differentiate into melanocytes. They finally colonize the hair follicles to become resident pigmented cells. Neoplastic transformation converts melanocytes into highly invasive melanoma cells, which can adopt two modes of interconvertible migration (mesenchymal and amoeboid). Through analysis of the coat color phenotype of natural mouse mutants and genetically modified animals, many of the genes regulating migration were identified. Deciphering of cell membrane protrusions and signaling molecules involved in melanoma cell motility was further achieved through 2D and 3D culture systems. Here, we summarize how these data allow a better understanding of the complex mechanisms controlling migration of normal and pathological cells of the melanocytic lineage.

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