碩士 / 國立暨南國際大學 / 生物醫學科技研究所 / 94 / Tyrosinase catalyzes the rate-limiting reaction of melanogenesis. The formation of melanin is regulated by the activity or the expression of the enzyme. Although the whole picture of the signal transduction involved in melanogenesis remains unclear, it is
suggested that cAMP plays an important role in the biosynthesis. cAMP modulates melanogenesis in three aspects. Firstly, cAMP activates the expression of microphthalmia associated transcription factor (MITF), which is the transcription factor of tyrosinase.
Secondly, cAMP induces MITF degradation through the activation of ERK, and therefore, down-regulates the expression of tyrosinase. Thirdly, cAMP inhibits the activation of phosphatidylinositol 3-kinase (PI3K), which results in the repression of protein kinase B
(Akt) expression, yet up-regulates MITF.
Melanogenesis is involved in a series of redox reactions. Some antioxidants such as ascorbic acid, retard melanogenesis through reverse the process by reduction of oxidized intermediates. C-phycocyanin (CPC), a component of blue green algae, has been studied to have anti-oxidative capacity. In this study, we investigate the inhibitory effect of CPC on melanogenesis. Results showed that CPC attenuated melanogenesis via reduced tyrosinase activity and expression. The reduced level of tyorsinase expression was due to the
activation of ERK, which phosphorylated MITF and consequently leaded to MITF degradation. Besides, the decreased level of MITF was also observed at transcriptionallevel. In conclusion, CPC reduced melanin biosynthesis by activation of ERK and decreased level of MITF transcription; therefore, resulted in subsequent down-regulation of tyrosinase.
| Identifer | oai:union.ndltd.org:TW/094NCNU0114004 |
| Date | January 2006 |
| Creators | Yu-Yun Lin, 林育筠 |
| Contributors | Li-Chen Wu, 吳立真 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 72 |
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