Browsing by Subject "Melanocytes"

Now showing 1 - 3 of 3
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    Mahogunin ring finger 1 is required for genomic stability and modulates the malignant phenotype of melanoma cells.
    (MDPI, 2020-10-01) Martínez-Vicente, Idoya; Abrisqueta, Marta; Bennett, Dorothy C.; Sirés-Campos, Julia; Castejón Griñán, María; García-Borrón Martínez, José Carlos; Herraiz Serrano, Cecilia María; Jiménez-Cervantes Frigols, Celia; Olivares Sánchez, María Concepción; Bioquímica y Biología Molecular B e Inmunología
    The mouse mahoganoid mutation abrogating Mahogunin Ring Finger‐1 (MGRN1) E3 ubiquitin ligase expression causes hyperpigmentation, congenital heart defects and neurodegeneration. To study the pathophysiology of MGRN1 loss, we compared Mgrn1‐knockout melanocytes with genetically matched controls and melan‐md1 (mahoganoid) melanocytes. MGRN1 knockout induced a more differentiated and adherent phenotype, decreased motility, increased the percentage of cells in the S phase of the cell cycle and promoted genomic instability, as shown by stronger γH2AX labelling, increased burden of DNA breaks and higher abundance of aneuploid cells. Lack of MGRN1 expression decreased the ability of melanocytes to cope with DNA breaks generated by oxidizing agents or hydroxyurea‐induced replicative stress, suggesting a contribution of genomic instability to the mahoganoid phenotype. MGRN1 knockout in B16‐F10 melanoma cells also augmented pigmentation, increased cell adhesion to collagen, impaired 2D and 3D motility and caused genomic instability. Tumors formed by Mgrn1‐KO B16‐F10 cells had lower mitotic indices, fewer Ki67‐positive cells and showed a trend towards smaller size. In short‐term lung colonization assays Mgrn1‐KO cells showed impaired colonization potential. Moreover, lower expression of MGRN1 is significantly associated with better survival of human melanoma patients. Therefore, MGRN1 might be an important phenotypic determinant of melanoma cells.
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    MGRN1 as a phenotypic determinant of human melanoma cells and a potential biomarker.
    (MDPI, 2022-07-26) Abrisqueta, Marta; Sánchez-Beltrán, José; Martínez-Vicente, Idoya; Sevilla, Arrate; Alonso, Santos; Boyano, María Dolores; Cerdido Ochoa, Sonia; García-Borrón Martínez, José Carlos; Herraiz Serrano, Cecilia María; Jiménez-Cervantes Frigols, Celia; Lambertos Escudero, Ana; Olivares Sánchez, María Concepción; Bioquímica y Biología Molecular B e Inmunología
    Mahogunin Ring Finger 1 (MGRN1), a ubiquitin ligase expressed in melanocytes, interacts with the α melanocyte-stimulating hormone receptor, a well-known melanoma susceptibility gene. Previous studies showed that MGRN1 modulates the phenotype of mouse melanocytes and melanoma cells, with effects on pigmentation, shape, and motility. Moreover, MGRN1 knockdown augmented the burden of DNA breaks in mouse cells, indicating that loss of MGRN1 promoted genomic instability. However, data concerning the roles of MGRN1 in human melanoma cells remain scarce. We analyzed MGRN1 knockdown in human melanoma cells. Transient MGRN1 depletion with siRNA or permanent knockdown in human melanoma cells by CRISPR/Cas9 caused an apparently MITF-independent switch to a more dendritic phenotype. Lack of MGRN1 also increased the fraction of human cells in the S phase of the cell cycle and the burden of DNA breaks but did not significantly impair proliferation. Moreover, in silico analysis of publicly available melanoma datasets and estimation of MGRN1 in a cohort of clinical specimens provided preliminary evidence that MGRN1 expression is higher in human melanomas than in normal skin or nevi and pointed to an inverse correlation of MGRN1 expression in human melanoma with patient survival, thus suggesting potential use of MGRN1 as a melanoma biomarker.
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    The α-melanocyte-stimulating hormone/melanocortin-1 receptor interaction: a driver of pleiotropic effects beyond pigmentation.
    (Wiley, 2021-04-21) Martínez-Vicente, Idoya; Maresca, Vittoria; Herraiz Serrano, Cecilia María; Bioquímica y Biología Molecular B e Inmunología
    Melanocortin-1 Receptor (MC1R), when stimulated by alpha-melanocyte-stimulating hormone (α-MSH), is a driver of eumelanogenesis. Brown/black eumelanin is an effective filter against ultraviolet radiation (UVR) and is a scavenger of free radicals. Several polymorphic variants of MC1R are frequent in red-head people. These polymorphisms reduce the ability of MC1R to promote eumelanogenesis after its activation and spontaneous pheomelanogenesis take place. Since pheomelanin can act as an endogenous photosensitizer, people carrying MC1R polymorphisms are more susceptible to skin cancer. Here, we summarize current knowledge on the biology of MC1R beyond its ability to drive eumelanogenesis. We analyze its capacity to cope with oxidative insult and consequent DNA damage. We describe its ability to transduce through different pathways. We start from the canonical pathway, the cAMP/protein kinase A (PKA) pathway mainly involved in promoting eumelanogenesis, and protection from oxidative damage, and we then move on to describe more recent knowledge concerning ERK pathways, phosphoinositide 3-kinase (PI3K) pathway/AKT, and α-MSH/Peroxisome proliferators activated receptor-γ (PPAR-γ) connection. We describe MC1R polymorphic variants associated with melanoma risk which represent an open window of clinical relevance.