C-KIT signaling depends on microphthalmia-associated transcription factor for effects on cell proliferation

• Published in: PloS one 2011-08, Vol.6 (8), p.e24064-e24064
• Main Authors: Phung, Bengt, Sun, Jianmin, Schepsky, Alexander, Steingrimsson, Eirikur, Rönnstrand, Lars
• Format: Article
• Language: English
• Subjects: 1-Phosphatidylinositol 3-kinase; Activation; AKT protein; B cells; Basic Medicine; Binding sites; Biochemistry; Biology; c-Kit protein; Cell cycle; Cell growth; Cell Line; Cell Proliferation; DNA binding proteins; Extracellular signal-regulated kinase; Helix-loop-helix proteins; Helix-loop-helix proteins (basic); Humans; Integrated approach; Kinases; Laboratories; Leucine; Leucine zipper proteins; Ligands; Läkemedelskemi; Medical and Health Sciences; Medicin och hälsovetenskap; Medicinal Chemistry; Medicine; Medicinska och farmaceutiska grundvetenskaper; Melanocytes; Melanocytes - cytology; Melanocytes - metabolism; Melanocytes - pathology; Melanoma; Metastasis; Microphthalmia-associated transcription factor; Microphthalmia-Associated Transcription Factor - metabolism; Mitogen-Activated Protein Kinase Kinases - metabolism; Molecular biology; Mutants; Mutation; Mutation, Missense; Phosphorylation; Phosphotransferases; Protein-tyrosine kinase receptors; Proteins; Proto-Oncogene Proteins c-kit - genetics; Proto-Oncogene Proteins c-kit - metabolism; Regulators; Regulatory mechanisms (biology); Signal Transduction; Signaling; Stem cells; Transcription factors; Tyrosine
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0024064

The development of melanocytes is regulated by the tyrosine kinase receptor c-KIT and the basic-helix-loop-helix-leucine zipper transcription factor Mitf. These essential melanocyte survival regulators are also well known oncogenic factors in malignant melanoma. Despite their importance, not much is known about the regulatory mechanisms and signaling pathways involved. In this study, we therefore sought to identify the signaling pathways and mechanisms involved in c-KIT mediated regulation of Mitf. We report that c-KIT stimulation leads to the activation of Mitf specifically through the c-KIT phosphorylation sites Y721 (PI3 kinase binding site), Y568 and Y570 (Src binding site). Our study not only confirms the involvement of Ras-Erk signaling pathway in the activation of Mitf, but also establishes that Src kinase binding to Y568 and Y570 of c-KIT is required. Using specific inhibitors we observe and verify that c-KIT induced activation of Mitf is dependent on PI3-, Akt-, Src-, p38- or Mek kinases. Moreover, the proliferative effect of c-KIT is dependent on Mitf in HEK293T cells. In contrast, c-KIT Y568F and Y721F mutants are less effective in driving cell proliferation, compared to wild type c-KIT. Our results reveal novel mechanisms by which c-KIT signaling regulates Mitf, with implications for understanding both melanocyte development and melanoma.