碩士 / 國立暨南國際大學 / 生物醫學科技研究所 / 96 / An increased level of melanin is one of the characteristics of several skin diseases, including acquired hyperpigmentation such as melasma, postinflammatory melanoderma, and solar lentigo. 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 regulates the activation of protein kinase A, which phosphoylates the transcription protein, CREB. Phosphoryed CREB further facilitates 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 involves a series of redox reactions. Antioxidants such as ascorbic acid, retard melanogenesis through reduction of oxidized intermediates. C-phycocyanin (CPC), a component of blue green algae, has been studied to have anti-oxidative capacity and free radical scavenging activity. In the present study, the results showed that B16F10 melanin content and tyrosinase expression were reduced by the addition of CPC. In addition, CPC increased cAMP level and protein kinase A (PKA) activity. CPC were uptaken and trapped in cell nuclei to inhibit melanogenesis possibly the through suppression of the PKA pathway.
| Identifer | oai:union.ndltd.org:TW/096NCNU0114010 |
| Date | January 2008 |
| Creators | Yu-Ting Weng, 翁于婷 |
| 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 | 63 |
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