<130907 김준섭>▶Objective : To know relation bew-teen HMG-CoA reductase and melanogensis

INHA University - Bioengineer-ingABSTRACT

cholesterol regulation of melanogenesis

artemisinic acid melanogenesis in human epidermal melanocyte

MITFtyrosinaseTRP-1TRP-2

•c-KIT, stem cell factor•macrophage migration inhibition factor(MIF)

•cAMP•protein kinase activ-ity

artemisinic acid inhibition of C/EBP α inhibition of HMG CoA reductase

INHA University - Bioengineer-ingINTRODUCTION

Cholesterol is an essential mammalian membrane protein

•cell integrity•cell signaling•cell metabo-lism

•membrane fluidity•steroid hormone synthe-sis

Cellular changes in endogenous synthesis and exogenous supply of cholesterol occur through feedback regulation of HMG CoA reduc-tase and the low-density lipoprotein receptor(LPLR).

•sterol-response element (SRE)•Sp1•NF-Y•a cyclic AMP-response element (CRE)•C/EBP family binding element

Several important elements of HMG CoAreductase promoter

INHA University - Bioengineer-ingMATERIALS AND METHODS

• Cell culture : human epidermal melanocyte

• Melanin content assay

• Histochemistry of reconstructed epidermis

• Cyclic AMP immunoassay

• Cell viability assay : MTT

• Real-time RT-PCR analysis

• HMG CoA reductase assay

• Western blot analysis

• Protein kinase A (PKA) activity assay

• Cholesterol content assay

INHA University - Bioengineer-ingRESULTS

Fig. 1. Artemisinic acid inhibits melanogenesis in human epidermal melanocytes.

3.1. Artemisinic acid inhibits melanogenesis in human epidermal melanocytes

Inhibitory effects of artemisinic acid on melanin formation were found.

Cytotoxic effects were not observed (data not shown)

Reduction of melanogenic protein mRNA

INHA University - Bioengineer-ingRESULTS

3.2. Cyclic AMP-PKA signaling was inhibited by artemisinic acid

Levels of cAMP decreased significantly by treatment with artemisinic acid.

A significant decrease in PKA activity was observed.

Fig. 2. Artemisinic acid reduces cAMP production and PKA activity.

INHA University - Bioengineer-ingRESULTS

Fig. 3. Artemisinic acid inhibits cholesterol synthesis by downregulating the hydrox-ymethylglutaryl CoA (HMG CoA) reductase gene.

3.3. Artemisinic acid inhibited cholesterol synthesis by downregulating the hydroxymethylglutaryl CoA (HMG CoA) reductase gene

Cholesterol content decreased signifi-cantly by artemisinic acid treatment.

Expression of HMG CoA reductase, a critical factor in cholesterol synthe-sis, decreased fol-lowing artemisinic acid treatment

INHA University - Bioengineer-ingRESULTS

3.4. Reduced expression of the HMG CoA reductase gene by artemisinic acid is mediated through C/EBP α gene downregulation

Fig. 4. Reduced expression of the HMG CoA reductase gene by artemisinic acid is medi-ated by downregulation of the C/EBP a gene.

artemisinic acid treatment C/EBP a gene downregula-tion

INHA University - Bioengineer-ingDISCUSSION

Artemisinic acid downregulated HMG CoA reductase gene expression by inhibiting C/EBP a gene expression, after which it reduced choles-terol synthesis, consequently inhibiting melanogenesis

Fig. 5. Mechanisms of artemisinic acid-induced attenuation of melanogenesis.