• Journal of the Society of Cosmetic Scientists of Korea
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• v.41 no.3
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• pp.243-252
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• 2015

Melanosome, the pigment granule in melanocyte, determines the color of skin when it moves into the keratinocyte. Inhibition of melanosome transfer from melanocyte to keratinocyte results in skin depigmentation. Protease activated receptor-2 (PAR-2) is involved in signal transduction systems via cell membrane and increases the melasome transfer when it is activated by cleavage of their extracellular amino acid sequence by trypsin or by a peptide such as SLIGKV. Here, we showed that lobaric acid inhibited PAR-2 activation and affected the mobilization of $Ca2^+$. The uptake of fluorescent microspheres and isolated melanosomes from melan-a melanocytes to keratinocytes induced by SLIGKV were inhibited by lobaric acid. Also, confocal microscopy studies illustrated a decreased melanosome transfer to keratinocytes in melanocyte-keratinocyte co-culture system by lobaric acid. In addition, lobaric acid induced visible skin lightening effect in human skin tissue culture model, melanoderm$^{(R)}$. Our data suggest that lobaric acid could be an effective skin lightening agent that works via regulation of phagocytic activity of keratinocytes.

• Journal of Life Science
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• v.19 no.7
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• pp.892-898
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• 2009

MIF is a progesterone analogue and is known as a potent progesterone antagonist. Although MIF has been known to inhibit prostate cancer cell growth, its molecular mechanisms are not yet clear. In the present study, when the cells were treated for 2-4 days with 5-40 $\mu$M of MIF, the growth and viability of LNCaP cells were significantly decreased in a dose- and time-dependent manner. When the cells, cultivated in a normal 2 mM calcium concentration medium, were treated with 15 $\mu$M MIF for 1 day, the intracellular calcium level increased by 26% compared to the control. Similar results were also found in cells located in the calcium-free reaction buffer, indicating that MIF induced the increase of intracellular Ca$^{2+}$ levels, regardless of the presence of calcium in the surrounding medium. In the cells treated with various concentrations of MIF, the intracellular calcium levels increased in a dose dependent manner. Cells treated with MIF revealed typical early apoptotic signs, i.e., chromosome condensation and nuclei fragmentation. In cells treated with 40 11M MIF, Bcl-2 decreased to 19% of the control. The expression of Bax increased to almost 2 fold of the control. These results demonstrated very clearly that MIF treatment blocks the expression of Bcl-2 but stimulates the expression of Bax. According to the results of the present investigation, the apoptotic mechanism of MIF is triggered by intracellular modulation.

• Journal of Ginseng Research
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• v.43 no.4
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• pp.527-538
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• 2019

Background: Ginsenoside Rg1 was shown to exert ligand-independent activation of estrogen receptor (ER) via mitogen-activated protein kinase-mediated pathway. Our study aimed to delineate the mechanisms by which Rg1 activates the rapid ER signaling pathways. Methods: ER-positive human breast cancer MCF-7 cells and ER-negative human embryonic kidney HEK293 cells were treated with Rg1 ($10^{-12}M$, $10^{-8}M$), $17{\beta}$-estradiol ($10^{-8}M$), or vehicle. Immunoprecipitation was conducted to investigate the interactions between signaling protein and ER in MCF-7 cells. To determine the roles of these signaling proteins in the actions of Rg1, small interfering RNA or their inhibitors were applied. Results: Rg1 rapidly induced $ER{\alpha}$ translocation to plasma membrane via caveolin-1 and the formation of signaling complex involving linker protein (Shc), insulin-like growth factor-I receptor, modulator of nongenomic activity of ER (MNAR), $ER{\alpha}$, and cellular nonreceptor tyrosine kinase (c-Src) in MCF-7 cells. The induction of extracellular signal-regulated protein kinase and mitogen-activated protein kinase kinase (MEK) phosphorylation in MCF-7 cells by Rg1 was suppressed by cotreatment with small interfering RNA against these signaling proteins. The stimulatory effects of Rg1 on MEK phosphorylation in these cells were suppressed by both PP2 (Src kinase inhibitor) and AG1478 [epidermal growth factor receptor (EGFR) inhibitor]. In addition, Rg1-induced estrogenic activities, EGFR and MEK phosphorylation in MCF-7 cells were abolished by cotreatment with G15 (G protein-coupled estrogen receptor-1 antagonist). The increase in intracellular cyclic AMP accumulation, but not Ca mobilization, in MCF-7 cells by Rg1 could be abolished by G15. Conclusion: Ginsenoside Rg1 exerted estrogenic actions by rapidly inducing the formation of ER containing signalosome in MCF-7 cells. Additionally, Rg1 could activate EGFR and c-Src ER-independently and exert estrogenic effects via rapid activation of membrane-associated ER and G protein-coupled estrogen receptor.

• Journal of Ginseng Research
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• v.46 no.3
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• pp.348-356
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• 2022

Background: Gintonin is a ginseng-derived exogenous G-protein-coupled lysophosphatidic acid (LPA) receptor ligand. Gintonin exerts its neuronal and non-neuronal in vitro and in vivo effects through LPA receptor subtypes. However, it is unknown whether gintonin can bind to the plasma membrane of cells and can transactivate the epidermal growth factor (EGF) receptor. In the present study, we examined whether gintonin-biotin conjugates directly bound to LPA receptors and transactivated the EGF receptor. Methods: We designed gintonin-biotin conjugates through gintonin biotinylation and examined whether gintonin-biotin conjugate binding sites co-localized with the LPA receptor subtype binding sites. We further examined whether gintonin-biotin transactivated the EGF receptor via LPA receptor regulation via phosphor-EGF and cell migration assays. Results: Gintonin-biotin conjugates elicit [Ca²⁺]_i transient similar to that observed with unbiotinylated gintonin in cultured PC3 cells, suggesting that biotinylation does not affect physiological activity of gintonin. We proved that gintonin-biotin conjugate binding sites co-localized with the LPA1/6 receptor binding sites. Gintonin-biotin binding to the LPA1 receptor transactivates the epidermal growth factor (EGF) receptor through phosphorylation, while the LPA1/3 receptor antagonist, Ki16425, blocked phosphorylation of the EGF receptor. Additionally, an EGF receptor inhibitor AG1478 blocked gintonin-biotin conjugate-mediated cell migration. Conclusions: We observed the binding between ginseng-derived gintonin and the plasma membrane target proteins corresponding to the LPA1/6 receptor subtypes. Moreover, gintonin transactivated EGF receptors via LPA receptor regulation. Our results suggest that gintonin directly binds to the LPA receptor subtypes and transactivates the EGF receptor. It may explain the molecular basis of ginseng physiology/pharmacology in biological systems.