Differential regulation of melanosomal proteins after hinokitiol treatment.
BACKGROUND
Melanogenesis is regulated by a series of enzymes under the control of microphthalmia-associated transcription factor (MITF).


OBJECTIVE
The aim of this study was to examine melanosome-associated protein levels in Mel-Ab cells after hinokitiol treatment.


METHODS
We measured melanin contents and analyzed melanosome-associated protein levels using Western blot and RT-PCR analysis.


RESULTS
Hinokitiol markedly inhibited melanin synthesis and also reduced the protein levels of tyrosinase (TYR), tyrosinase-related protein 1 (TYRP-1), tyrosinase-related protein 2 (TYRP-2) and MITF in Mel-Ab cells. In addition, hinokitiol significantly increased the phosphorylations of extracellular signal-regulated kinases 1 and 2 (ERK1/2). Furthermore, reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed that TYR and MITF mRNA levels were significantly decreased but that levels of TYRP-1 and TYRP-2 mRNA were unaffected by hinokitiol treatment. These results suggest that hinokitiol-induced ERK phosphorylation reduces MITF and TYR transcription, and mediates the action of hinokitiol on melanogenesis. Interestingly, the mRNAs of TYRP-1 and TYRP-2 were unaffected, although the protein levels of TYRP-1 and TYRP-2 were down-regulated. Thus, the effects of hinokitiol on the transcription of TYR may differ from its effects on TYRP-1 and TYRP-2.


CONCLUSIONS
Therefore, we suggest that TYRP-1 and TYRP-2 may be regulated by post-translational degradation after hinokitiol treatment.
Choi
Yeong-Gon
YG
Department of Dermatology, Seoul National University College of Medicine, Republic of Korea.
Bae
Eun-Jin
EJ
Kim
Dong-Seok
DS
Park
Seo-Hyoung
SH
Kwon
Sun-Bang
SB
Na
Jung-Im
JI
Park
Kyoung-Chan
KC
D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D015536:Down-Regulation; D005419:Flavonoids / Q000494:pharmacology; D017496:Hypopigmentation / Q000139:chemically induced / Q000378:metabolism; D019746:Intramolecular Oxidoreductases / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D008543:Melanins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D020460:Melanosomes / Q000187:drug effects* / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D051379:Mice; D051739:Microphthalmia-Associated Transcription Factor / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D014442:Monophenol Monooxygenase / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D039821:Monoterpenes / Q000494:pharmacology*; D010088:Oxidoreductases / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D014176:Protein Biosynthesis / Q000187:drug effects* / Q000235:genetics; D011506:Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000187:drug effects*; D014334:Tropolone / Q000031:analogs & derivatives* / Q000494:pharmacology
D005419:Flavonoids; D008543:Melanins; D008562:Membrane Glycoproteins; D051739:Microphthalmia-Associated Transcription Factor; C497235:Mitf protein, mouse; D039821:Monoterpenes; D011506:Proteins; D012333:RNA, Messenger; D014334:Tropolone; D010088:Oxidoreductases; C079621:Tyrp1 protein, mouse; D014442:Monophenol Monooxygenase; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D019746:Intramolecular Oxidoreductases; C042501:dopachrome isomerase; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; C009479:beta-thujaplicin