title: Anti-melanogenic activity of phytosphingosine via the modulation of the microphthalmia-associated transcription factor signaling pathway.
abstract: BACKGROUND
  Microphthalmia-associated transcription factor (MITF) suppresses the expression of enzymes controlling the production of melanin. Phytosphingosine is a well-known cosmetic agent, but its anti-melanogenic activity and mechanism of action remain unclear.
  
  
  OBJECTIVE
  This study was designed to investigate the effects of phytosphingosine on melanin synthesis and elucidate the plausible mechanism of actions in vitro and ex vivo systems.
  
  
  METHODS
  Melanin content, cell viability, tyrosinase activity, p-CREB DNA binding activity, and the protein gene expression levels of the enzymes and proteins involved in melanogenesis were measured with the treatment of phytosphingosine.
  
  
  RESULTS
  Phytosphingosine inhibits melanin synthesis in cultured melan-a cells and a reconstructed human skin model. One possible mechanism of the anti-melanogenic activity of phytosphingosine appears to be associated with the modulation of MITF, which suppresses the expression of tyrosinase, tyrosinase-related protein-1 (TRP-1), and TRP-2. Further analysis revealed that phytosphingosine suppressed paired box 3 and SRY-related HMG-box 10, critical transcription factors of MITF. Phytosphingosine also effectively downregulated the protein levels of β-catenin and the phospho-cAMP response element binding protein, an upstream regulatory factor of MITF. These results are closely related to the suppression of MITF gene expression. In addition, treatment with phytosphingosine for over 12h, which is a relatively long period of time, did not directly suppress these MITF transcriptional factors. Instead, phytosphingosine induced ERK activation, which led to MITF phosphorylation, followed by its degradation. Therefore, the downregulation of MITF protein levels by phytosphingosine with a long time exposure is in part associated with MITF protein degradation through the MAPK kinase activation pathway.
  
  
  CONCLUSIONS
  The modulation of MITF by phytosphingosine is closely related with the signaling pathways, such as the suppression of the MITF gene expression and the degradation of the MITF protein, depending on the duration of treatment time. These results suggest that phytosphingosine might serve as an effective melanogenesis inhibitor in melanocytes via the regulation of the MITF signaling pathways.
authors.affiliation: College of Pharmacy, Natural Products Research Institute, Seoul National University, Seoul 151-742, Republic of Korea.
authors.forename: Eun Jeong
authors.initials: EJ
authors.lastname: Jang
authors.affiliation: College of Pharmacy, Natural Products Research Institute, Seoul National University, Seoul 151-742, Republic of Korea.
authors.forename: Yoonho
authors.initials: Y
authors.lastname: Shin
authors.affiliation: College of Pharmacy, Natural Products Research Institute, Seoul National University, Seoul 151-742, Republic of Korea.
authors.forename: Hyen Joo
authors.initials: HJ
authors.lastname: Park
authors.affiliation: College of Pharmacy, Natural Products Research Institute, Seoul National University, Seoul 151-742, Republic of Korea.
authors.forename: Donghwa
authors.initials: D
authors.lastname: Kim
authors.affiliation: College of Pharmacy, Natural Products Research Institute, Seoul National University, Seoul 151-742, Republic of Korea.
authors.forename: Cholomi
authors.initials: C
authors.lastname: Jung
authors.affiliation: College of Pharmacy, Natural Products Research Institute, Seoul National University, Seoul 151-742, Republic of Korea.
authors.forename: Ji-Young
authors.initials: JY
authors.lastname: Hong
authors.affiliation: College of Pharmacy, Natural Products Research Institute, Seoul National University, Seoul 151-742, Republic of Korea.
authors.forename: Sanghee
authors.initials: S
authors.lastname: Kim
authors.affiliation: College of Pharmacy, Natural Products Research Institute, Seoul National University, Seoul 151-742, Republic of Korea. Electronic address: sklee61@snu.ac.kr.
authors.forename: Sang Kook
authors.initials: SK
authors.lastname: Lee
mesh_terms: D000328:Adult; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D008543:Melanins / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D051739:Microphthalmia-Associated Transcription Factor / Q000235:genetics / Q000502:physiology*; D008875:Middle Aged; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors; D011401:Promoter Regions, Genetic; D015398:Signal Transduction / Q000502:physiology*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: C115163:CREB1 protein, human; D017362:Cyclic AMP Response Element-Binding Protein; D008543:Melanins; D051739:Microphthalmia-Associated Transcription Factor; D014442:Monophenol Monooxygenase; D048049:Extracellular Signal-Regulated MAP Kinases; C012491:phytosphingosine; D013110:Sphingosine
keywords: Anti-melanogenic activity; MAPK kinase; MITF; Melan-a cells; Phytosphingosine; Tyrosinase