Essential role of microfibrillar-associated protein 4 in human cutaneous homeostasis and in its photoprotection.

UVB-induced cutaneous photodamage/photoaging is characterized by qualitative and quantitative deterioration in dermal extracellular matrix (ECM) components such as collagen and elastic fibers. Disappearance of microfibrillar-associated protein 4 (MFAP-4), a possible limiting factor for cutaneous elasticity, was documented in photoaged dermis, but its function is poorly understood. To characterize its possible contribution to photoprotection, MFAP-4 expression was either augmented or inhibited in a human skin xenograft photodamage murine model and human fibroblasts. Xenografted skin with enhanced MFAP-4 expression was protected from UVB-induced photodamage/photoaging accompanied by the prevention of ECM degradation and aggravated elasticity. Additionally, remarkably increased or decreased fibrillin-1-based microfibril development was observed when fibroblasts were treated with recombinant MFAP-4 or with MFAP-4-specific siRNA, respectively. Immunoprecipitation analysis confirmed direct interaction between MFAP-4 and fibrillin-1. Taken together, our findings reveal the essential role of MFAP-4 in photoprotection and offer new therapeutic opportunities to prevent skin-associated pathologies.

Neprilysin is identical to skin fibroblast elastase: its role in skin aging and UV responses.

Although human skin fibroblast (HSF) elastase has been characterized as a membrane-bound metalloproteinase, little is known about its structure, amino acid sequence, and encoding gene. As there are similarities in the molecular weights and inhibitory profiles of HSF elastase and neprilysin (neutral endopeptidase 24.11 (NEP)), in this study we tested the hypothesis that they are identical using immunoprecipitation and transfection methods. An immunoprecipitation study demonstrated that HSF elastase activity co-immunoprecipitated with anti-NEP in lysates of cultured HSF. Transfection of an NEP cDNA expression vector into COS-1 cells elicited the expression of HSF elastase and NEP activities in the transfected cells. These findings strongly suggest that HSF elastase is identical to NEP, which functions mainly in neuron-associated cells to degrade neuropeptides. Analysis of the expression pattern of NEP revealed that its expression was remarkably up-regulated at the gene, protein, and enzymatic activity levels during the replicative senescence of cultured HSF. Further, the activity of NEP was markedly enhanced in a pattern similar to elastase activity during the intrinsic aging of mouse skin, in UVA-exposed HSF as well as in HSF treated with conditioned medium from UVB-exposed human keratinocytes. Analysis of the cytokine profile for the stimulation of NEP and HSF elastase activities in HSF demonstrated that among the 11 cytokines tested, IL-1α, IL-1ß, IL-6, IL-8, and GM-CSF had the potential to significantly stimulate both activities similarly, again supporting the identity of HSF elastase and NEP.

The nucleosomal binding protein NSBP1 is highly expressed in the placenta and modulates the expression of differentiation markers in placental Rcho-1 cells.

We report that NSBP1, a nucleosome binding protein that affects the structure of chromatin, is highly expressed in mouse placenta. In Rcho-1 cells, which recapitulate the differentiation of trophoblast giant cells of living placenta, NSBP1 expression is linked to differentiation. Disregulation of NSBP1 protein levels, by either siRNA treatment or by overexpression, alters the expression of several members of the prolactin gene family without affecting the levels of several transcription factors involved in placental differentiation. Our studies identify NSBP1 as a nucleosome binding protein that modulates the expression of prolactin gene family members most likely by inducing changes in chromatin structure.

Low-dose dioxins alter gene expression related to cholesterol biosynthesis, lipogenesis, and glucose metabolism through the aryl hydrocarbon receptor-mediated pathway in mouse liver.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a common environmental contaminant. TCDD binds and activates the transcription factor aryl hydrocarbon receptor (AHR), leading to adverse biological responses via the alteration of the expression of various AHR target genes. Although small amounts of TCDD are consumed via contaminated daily foodstuffs and environmental exposures, the effects of low-dose TCDD on gene expression in animal tissues have not been clarified, while a number of genes affected by high-dose TCDD were reported. In this study, we comprehensively analyzed gene expression profiles in livers of C57BL/6N mice that were orally administered relatively low doses of TCDD (5, 50, or 500 ng/kg body weight (bw) day(-1)) for 18 days. The hepatic TCDD concentrations, measured by gas chromatography-mass spectrometry, were 1.2, 17, and 1063 pg toxicity equivalent quantity (TEQ)/g, respectively. The mRNA level of the cytochrome P450 CYP1A1 was significantly increased by treatment with only TCDD 500 ng/kg bw day(-1). DNA microarray and quantitative RT-PCR analyses revealed changes in the expression of genes involved in the circadian rhythm, cholesterol biosynthesis, fatty acid synthesis, and glucose metabolism in the liver with at all doses of TCDD employed. However, repression of expression of genes involved in energy metabolism was not observed in the livers of Ahr-null mice that were administered the same dose of TCDD. These results indicate that changes in gene expression by TCDD are mediated by AHR and that exposure to low-dose TCDD could affect energy metabolism via alterations of gene expression.

Loss of skin elasticity precedes to rapid increase of wrinkle levels.

BACKGROUND: Decreased skin elasticity is considered as a factor that promotes wrinkle formation. However, the relationship between decreased skin elasticity and the formation of wrinkles is not fully understood. OBJECTIVE: The purpose of this study is to characterize the relationship between skin elasticity and wrinkle formation using quantitative methods. METHODS: Skin elasticity at the corner of the eye was measured using a Cutometer SEM575. Wrinkle levels at the corner of the eye were determined from three-dimensional analysis of surface replicas. Ninety healthy female volunteers living in Tokyo, Japan (aged 18-76 years) were examined in this study. RESULTS: In each scatter plot examined, women with lower U(r)/U(f) values or with higher U(v)/U(e) values showed a tendency for increased R(a) and R(max) values. However, this study determined widely scattered values for both types of parameters. These relationships were then reanalyzed in relation to age. Results were compared within a young (YNG) group of 27 women (aged 18-29), a middle-aged (MED) group of 26 women (aged 30-48) and an elderly (OLD) group of 37 women (aged 50-76). For elasticity parameters, U(r)/U(f) and U(v)/U(e) values, significant differences were found between the YNG and MED groups and also between the MED and OLD groups. For roughness parameters, a significant difference was found only between the MED and OLD groups. These results suggest that changes in R(a) or R(max) values lag about 20 years behind changes in skin elasticity values. CONCLUSIONS: Despite a strong relationship, elasticity parameters are unlikely to be an independent predictor of wrinkle levels. The amount of UV exposure to skin with decreased elasticity seems to be the variable that determines wrinkle levels. This finding represents another complexity in the mechanism of wrinkle formation.

Effect of room humidity on the formation of fine wrinkles in the facial skin of Japanese.

BACKGROUND/PURPOSE: Changes in humidity are commonly known to influence the condition of the skin. Previous studies of the skin dealt with variations in relative humidity (RH) either through statistical analysis or by maintaining room humidity at a constant level; however, the range of humidity and the length of acclimation varied in each study. This study aimed to determine whether the generally used ranges of RH are truly acceptable for studies of human skin. METHODS: Skin conductance, elasticity and fine wrinkles were assessed on the eyelids of 20 volunteers, first after acclimation for 30 min in a high-humidity room (70% RH) and again after acclimation for 30 min in a low-humidity room (40% RH). RESULTS: The study found significant decreases in skin conductance and elasticity and significant increases in fine wrinkles after acclimation to low humidity compared with high humidity. CONCLUSION: These results indicate that even a 30% difference in RH can affect skin properties in 30 min. The importance of humidity stabilization and the necessity of acclimation to the humidity, particularly when the study concerns wrinkles, were thus confirmed.