Linking aMSH with PPARc in B16-F10 melanoma Vittoria Maresca 1, *, Enrica Flori 1, *, Emanuela Camera 1 , Barbara Bellei 1 , Nicaela Aspite 1 , Matteo Ludovici 1 , Caterina Catricala ` 2 , Giorgia Cardinali 1 and Mauro Picardo 1 1 Laboratory of Cutaneous Physiopathology and Integrated Centre of Metabolomics Research, San Gallicano Dermatological Institute (IRCCS), Rome, Italy 2 Department of Dermatological Oncology San Gallicano Dermatological Institute (IRCCS), Rome, Italy CORRESPONDENCE M. Picardo, e-mail: picardo@ifo.it *These authors contributed equally to this work. KEYWORDS B16-F10 ⁄ a-melanocyte stimulating hor- mone ⁄ peroxisome proliferator activated receptor-c ⁄ PI(4,5)P 2 ⁄ PLC b pathway ⁄ calcium fluxes PUBLICATION DATA Received 27 January 2012, revised and accepted for publication 20 July 2012, published online 2 August 2012 doi: 10.1111/j.1755-148X.2012.01042.x Summary We have discovered a new a-melanocyte stimulating hormone (a-MSH) ⁄ peroxisome proliferator activated receptor-c (PPAR-c) connection in B16-F10 cells. Both PPAR-c up-regulation and its induction as an active transcription factor were observed in response to a-MSH. The a-MSH ⁄ PPAR-c connection influenced both pigmentation and proliferation. The forskolin-stimulated cAMP ⁄ PKA pathway was not able to induce either PPAR-c translocation into the nucleus or PPAR-c transcriptional activity. As the melanocortin-1 receptor, the specific receptor for the a-MSH, is a G-protein coupled receptor, we wondered whether the phosphatidylinosi- tol [PI(4,5)P 2 ⁄ PLC b ] signal pathway was involved in mediating the a-MSH-dependent PPAR-c activation. Employing inhibitors of PI(4,5)P 2 ⁄ PLC b pathway, the results of our experiments suggested that this pathway was promoted by a-MSH and that a-MSH played a role in mediating PPAR-c activation. We have demon- strated, for the first time, that a-MSH induces the PI(4,5)P 2 ⁄ PLC b pathway, through analysis of the basic steps of the pathway. The a-MSH effect on PPAR-c was independent of animal species and was not correlated with the physio-pathological status. Introduction Lipids or lipid-derived products, generated by phospho- lipases, modulate many cellular functions, such as the control of differentiation and inflammation (Yuri et al., 2007). Lipid compounds also promote cellular response through the induction of a class of transcription factors known as peroxisome proliferator activated receptors (PPARs). PPARs belong to the nuclear hormone recep- tor super-family and regulate the expression of target genes containing PPAR-responsive elements in their promoter (Palmer et al., 1995; Willson et al., 2000). Three PPARs iso-forms have been identified in cell types from different lineages and are designated as a, b ⁄ d and c (Barish et al., 2006; Issemann and Green, 1990; Tontonoz et al., 1993). Initially known for their important role in fat metabolism and adipocyte differen- tiation (Tontonoz et al., 1993), other regulatory roles of PPARs have been demonstrated. PPAR-c has been shown to have a crucial role in the control of differentia- Significance Most of the studies in cancer therapy employ pharmacological agents for direct activation of PPARs. This study highlights a new aspect of PPAR-c, placing this transcription factor inside a signal transduction pathway triggered by a hormone-receptor stimulus. We describe the existence of a new connection between a-MSH and PPAR-c. In B16-F10 cells we have observed that this link exerts an influence on melanogenesis and proliferation and that the pathway which drives this connection is the PI(4,5)P 2 ⁄ PLC b pathway. ª 2012 John Wiley & Sons A/S 1 Pigment Cell Melanoma Res. ORIGINAL ARTICLE