Jae Sung Hwang

The dermal stem cell factor and c-kit are overexpressed in melasma.

Background  The pathogenesis of melasma has not yet been clearly demonstrated. We tried to determine whether the stem cell factor (SCF) and its receptor c‐kit are involved in the mechanism of hyperpigmentation of melasma because this factor is highly implicated in the stimulation of melanocyte function in vitro and in vivo.

Loss of elastic fibers causes skin wrinkles in sun-damaged human skin

BACKGROUND Although wrinkling is the most obvious sign of aged skin, the detailed pathomechanism of wrinkle development has not been elucidated. OBJECTIVES In this study, we investigated the role of elastic fibers in the formation of skin wrinkles. METHODS Loss of elastic fibers was measured quantitatively in the facial skins of subjects representing seven decades, and then compared with wrinkle severities. We also investigated whether topical retinoic acid treatment to photoaged human skin can restore destroyed elastic fiber, and the correlation between wrinkle improvement with increase in elastic fibers in RA-treated facial skin. RESULTS We found a significant correlation between decreases in the length, width, number and total area of oxytalan fibers and wrinkle severity. Furthermore, we found that topical application of retinoic acid (0.025%) to chronically photodamaged skin regenerated and restored elastic fibers, and that there was a significant positive correlation between the amount of newly regenerated elastic fiber and the wrinkle improvement caused by retinoic acid. CONCLUSIONS Our results provide an objective insight into the role of elastic fibers in skin wrinkle formation by providing a quantitative correlation between changes in oxytalan fibers and the severity of skin wrinkling.

Dissection of SNARE-driven membrane fusion and neuroexocytosis by wedging small hydrophobic molecules into the SNARE zipper

Neuronal SNARE proteins mediate neurotransmitter release at the synapse by facilitating the fusion of vesicles to the presynaptic plasma membrane. Cognate v-SNAREs and t-SNAREs from the vesicle and the plasma membrane, respectively, zip up and bring about the apposition of two membranes attached at the C-terminal ends. Here, we demonstrate that SNARE zippering can be modulated in the midways by wedging with small hydrophobic molecules. Myricetin, which intercalated into the hydrophobic inner core near the middle of the SNARE complex, stopped SNARE zippering in motion and accumulated the trans-complex, where the N-terminal region of v-SNARE VAMP2 is in the coiled coil with the frayed C-terminal region. Delphinidin and cyanidin inhibited N-terminal nucleation of SNARE zippering. Neuronal SNARE complex in PC12 cells showed the same pattern of vulnerability to small hydrophobic molecules. We propose that the half-zipped trans-SNARE complex is a crucial intermediate waiting for a calcium trigger that leads to fusion pore opening.

A new moisturizer containing physiologic lipid granules alleviates atopic dermatitis

Background: Patients with atopic dermatitis show a defective barrier function. In atopic skin, ceramide is significantly decreased and the secretion of lamellar bodies is also impaired. To mimic lamellar bodies, we prepared lipid granules composed of ceramide, fatty acids and cholesterol. Because these lipid granules contain multiple lamellar structures, it is expected that they will have superior affinity to skin; hence, they should have a good moisturizing effect. This study was performed to evaluate the effects of moisturizer containing lipid granules on atopic dermatitis. Methods: Patients with mild atopic dermatitis (n = 30, aged 5–19 years) were recruited and instructed to apply a moisturizer containing physiologic lipid granules for 4 weeks. The SCORing Atopic Dermatitis (SCORAD) score and general symptoms were evaluated. In addition, transepidermal water loss (TEWL) and stratum corneum (SC) hydration were also measured. Results: Twenty-nine patients completed the study. The SCORAD value decreased dramatically after 4 weeks of moisturizer application (p = 0.000). The general symptoms of atopic dermatitis were also greatly improved. At baseline, most patients reported their symptoms as mild and moderate, but after 4 weeks 20 of the patients (69%) had no symptoms. The TEWL was not changed, but the SC hydration increased significantly (p = 0.000). No significant adverse effects were observed. Conclusions: Moisturizer containing lipid granules effectively controlled atopic dermatitis.

Influence of N-glycan processing disruption on tyrosinase and melanin synthesis in HM3KO melanoma cells.

Abstract:  Tyrosinase, a type I membrane glycoprotein, is synthesized and glycosylated in the endoplasmic reticulum (ER) and Golgi. The enzyme is subsequently transported to melanosomes where it participates in melanogenesis. Previous studies showed that the disruption of early ER N‐glycan processing by deoxynojirimycin (DNJ), an inhibitor of α‐glucosidase, suppresses tyrosinase enzymatic activity and melanogenesis. However, the disruption of late glycan processing, mainly performed by ER and Golgi α‐1,2‐mannosidases, on tyrosinase enzymatic activity and melanogenesis remains to be investigated. Following treatment of HM3KO human melanoma cells with deoxymannojirimycin (DMJ), an inhibitor of α‐1,2‐mannosidase, transport of tyrosinase to the melanosome, enzymatic activity, and melanogenesis were reduced in a dose‐dependent manner. However, DMJ did not directly inhibit tyrosinase enzymatic activity and expression. Interestingly, an extract of Streptomyces subrutilus culture medium (ESSCM) containing DMJ and DNJ as the main components inhibited glycosylation and transport of tyrosinase to the melanosome as well as melanin synthesis, but with no negative effects on cell viability. These inhibitory effects of ESSCM were stronger than those of DMJ or DNJ alone. Tyrosinase glycosylation and melanogenesis in HM3KO melanoma cells were more effectively inhibited by DMJ and DNJ combined than DMJ or DNJ alone. Accordingly, we propose that ESSCM is a potential candidate for treating undesirable hyperpigmentation conditions, such as melasma, postinflammatory melanoderma, and solar lentigo.

Impact of NAD(P)H:Quinone Oxidoreductase-1 on Pigmentation

We obtained metastasized melanoma tissue from a primary acral lentiginous melanoma (ALM) patient and established a melanoma cell line named primary culture of melanoma cell derived from lymph node (PML)-1. PML-1 cells had a light brown color and decreased the expression of melanogenesis markers, including tyrosinase (TYR), microphthalmia-associated transcription factor, and tyrosinase-related protein-1. To identify genes differentially regulated in PML-1 melanoma cells, we performed DNA microarray and two-dimensional matrix-assisted laser desorption ionization-time of flight mass spectrometry analyses. Among the candidate genes identified, we chose NAD(P)H:quinone oxidoreductase-1 (NQO1) for further study. Reverse transcription-PCR and western blot analyses showed that NQO1 was markedly decreased in PML-1 cells and in several amelanotic melanoma cell lines. To investigate whether NQO1 affects the melanogenesis, we treated the cultured normal human melanocytes (NHMC) and zebrafish with NQO1 inhibitors, ES936 and dicoumarol. Interestingly, melanogenesis was significantly decreased by the addition of NQO1 inhibitors in both NHMC and zebrafish models. In contrast, overexpression of NQO1 using a recombinant adenovirus clearly induced melanogenesis, concomitantly with an increase of TYR protein level. These results suggest that NQO1 is a positive regulator of the pigmentation process.

Transcriptional profiling in human HaCaT keratinocytes in response to kaempferol and identification of potential transcription factors for regulating differential gene expression

Kaempferol is the major flavonol in green tea and exhibits many biomedically useful properties such as antioxidative, cytoprotective and anti-apoptotic activities. To elucidate its effects on the skin, we investigated the transcriptional profiles of kaempferol-treated HaCaT cells using cDNA microarray analysis and identified 147 transcripts that exhibited significant changes in expression. Of these, 18 were up-regulated and 129 were down-regulated. These transcripts were then classified into 12 categories according to their functional roles: cell adhesion/cytoskeleton, cell cycle, redox homeostasis, immune/defense responses, metabolism, protein biosynthesis/modification, intracellular transport, RNA processing, DNA modification/ replication, regulation of transcription, signal transduction and transport. We then analyzed the promoter sequences of differentially-regulated genes and identified over-represented regulatory sites and candidate transcription factors (TFs) for gene regulation by kaempferol. These included c-REL, SAP-1, Ahr-ARNT, Nrf-2, Elk-1, SPI-B, NF-κB and p65. In addition, we validated the microarray results and promoter analyses using conventional methods such as real-time PCR and ELISA-based transcription factor assay. Our microarray analysis has provided useful information for determining the genetic regulatory network affected by kaempferol, and this approach will be useful for elucidating gene-phytochemical interactions.

Pigment-lightening effect of N,N′-dilinoleylcystamine on human melanoma cells

Background  Cystamine and linoleic acid have been reported to reduce melanin synthesis in vitro and in vivo. N,N′‐dilinoleylcystamine (DLC) is a compound of cystamine and linoleic acid connected by an ester bond.

N-(3,5-Dimethylphenyl)-3-Methoxybenzamide (A3B5) Targets TRP-2 and Inhibits Melanogenesis and Melanoma Growth

Melanin protects the skin from harmful environmental factors such as UV light. However, excessive melanin production induces hyperpigmentation. Previously, N-(3,5-dimethylphenyl)-3-methoxybenzamide (A(3)B(5)), a biaryl amide derivative, was identified for its ability to inhibit melanin production. However, its detailed mechanism of action has not been investigated. We elucidated the inhibitory mechanisms of A(3)B(5) in melanin production. Our results showed that A(3)B(5) had no effect on the production and activity of tyrosinase, an enzyme involved in melanogenesis. However, A(3)B(5) markedly decreased both constitutively expressed and UVB-induced tyrosinase-related protein 2 (TRP-2), which plays an important role along with tyrosinase in melanogenesis. The TRP-2 downregulation caused by A(3)B(5) may occur through proteasomal degradation because the A(3)B(5)-induced TRP-2 downregulation was inhibited by the ubiquitination inhibitor, MG-132. In addition, A(3)B(5) inhibited the proliferation of melanocytes and melanoma cells by arresting cells in the G1 stage of the cell cycle and moderately suppressed tumor growth in vivo. Taken together, our results indicate that A(3)B(5) downregulates melanin production and melanoma cell growth via proteosomal degradation of TRP-2 and suggest that A(3)B(5) can be a possible therapeutic agent that effectively regulates both hyperpigmentation and melanoma growth in the skin.

A New Antioxidant, Clitocybin A, from the Culture Broth of Clitocybe aurantiaca

Clitocybin A (1), a new antioxidant, was isolated from the culture broth of Clitocybe aurantiaca. This compound was purified by solvent extraction, silica gel column chromatography, Sephadex LH-20 column chromatography and preparative HPLC. Its structure was determined as 4,6-dihydroxy-2-ρ-hydroxyphenyl-isoindol-1-one on the basis of the UV, NMR, and MS spectroscopic analysis. The compound 1 showed potent free radical scavenging activity against superoxide, ABTS, and DPPH radicals, and protective effect against cellular DNA damage induced by oxidative stress.