Caspase-14, a cysteine endoproteinase belonging to the conserved family of aspartate-specific proteinases, was shown to play an important role in the terminal differentiation of keratinocytes and barrier function of the skin. In the present study, we developed a biofunctional compound that we described as a modulator of caspase-14 expression. Using normal human keratinocytes (NHK) in culture and human skin biopsies, this compound was shown to increase caspase-14 expression and partially reverse the effect of caspase-14-specific siRNA on NHK. Moreover, the increase in filaggrin expression visualized on skin biopsies and the recovery of the barrier structure after tape-stripping indicated that this compound could exhibit a beneficial effect on the skin barrier function. Considering the possible link between caspase-14 and the barrier function, a UVB irradiation on NHK and skin biopsies previously treated with the caspase-14 inducer, was performed. Results indicated that pretreated skin biopsies exhibited less signs of UV damage such as active caspase-3 and cyclobutane pyrimidine dimers (CPDs). Likewise, pretreated NHK were protected from UV-induced genomic DNA damage, as revealed by the Comet Assay. Finally, a clinical test showed a reduction of transepidermal water loss (TEWL) on the treated skin compared with placebo, under UV stress condition, confirming a protecting effect. Taken together, these results strongly suggest that, by increasing caspase-14 expression, the biofunctional compound could exhibit a protective effect on the skin barrier function, especially in case of barrier damage and UV irradiation.
One of the main functions of the skin is to protect the organism against environmental threats, such as thermal stress. Aquaporin-3 (AQP3) facilitates water and glycerol transport across cell membranes and therefore regulates osmotic balance in different situations of stress. This mechanism seems to be particularly important for the resistance of different organisms to cold stress. Consequently, we were interested in investigating the effect of cold and osmotic stress on AQP3 expression in normal human keratinocytes. We developed a new active ingredient to stimulate aquaporins in skin and demonstrated the partial restoration of AQP3 expression in keratinocytes transfected with AQP3 siRNA. Moreover, we examined the effect of cold stress on cell morphology and the impact of a pre-treatment with the active ingredient. Our results indicated that induction of AQP3 helped maintain a correct organization of the actin cytoskeleton, preserving cell morphology and preventing cells from rounding. Immunofluorescent staining revealed cytoplasmic localization of AQP3 and its translocation to the cell membrane following osmotic stress. Histological ex vivo studies of skin under different conditions, such as cold environment and tape-stripping, indicated that increase in AQP3 expression appears to be involved in skin protection and showed that the pattern of AQP3 expression was more enhanced in the active ingredient-treated samples. In vivo confocal microscopy by Vivascope showed a generally healthier appearance of the skin in the treated areas. These results attest to the potential value of the active ingredient in optimizing environmental stress resistance and protecting the skin from stratum corneum damage.
The stem cell factor (SCF) and its protein-tyrosine kinase receptor KIT are together implicated in the regulation of diverse biological processes and particularly in melanogenesis. Indeed, this signalling pathway controls melanoblast migration from the neural crest during embryogenesis and allows the communication between keratinocytes and melanocytes in the adult. In melanocytes, the binding of SCF to its transmembrane receptor leads to the activation of signalling pathways implicating protein kinases which finally control the expression of pigmentation-related genes. We have developed a biological compound called IV09.007, which we previously described as a modulator of the SCF/KIT signalling pathway with a pro-pigmenting effect. In the present work, we have studied the expression and localization of both SCF and KIT mRNAs and proteins in the skin or skin-derived cell lines. Then, we explored with a microarray approach the ability of IV09.007 to modulate the expression of genes in human keratinocytes and melanocytes in culture. Thereby, we observed the regulation of genes implicated in DNA repair, mainly related to base/nucleotides excision pathways. A modulated transcriptional response was also observed for some genes implicated in the response against oxidative stress, in apoptosis inhibition and in lowering inflammatory immune response. These microarray results predicted a conferred protective effect of IV09.007 and we verified this hypothesis by performing comet assays on UVB-irradiated keratinocytes or melanocytes, to demonstrate the efficacy of IV09.007 on preventing DNA damage.
In conclusion, this assay could be of interest for subacute cytotoxicity and genotoxic assessment of daily and topically applied products and suggests that PQ is a choice worthy positive control.
Abstract:The significance of Coenzyme Q10 (CoQ10) as an anti-oxidant barrier of the skin, as well as a key component in anti-aging strategies for skin care products, has been firmly established. Biosynthesis of CoQ10 in the mitochondria is well known, but there is only limited information on the non-mitochondrial synthesis of CoQ10 in the skin. Recent findings in zebrafish identified that a tumor suppressor, Ubiad1, is also a key enzyme in the non-mitochondrial synthesis of CoQ10. The purpose of this study was to investigate expression of Ubiad1 in human skin, and its implication in the skin's cutaneous response to oxidative stress. We observed Ubiad1 localization in the epidermis, particularly a subcellular localization in the Golgi apparatus. Ubiad1 modulation by a pentapeptide was associated with an observed reduction in ROS/RNS stresses (−44%/−19% respectively), lipid peroxidation (−25%) and preservation of membrane fluidity under stress conditions. Electron microscopy of keratinocytes revealed a significant degree of stimulation of the Golgi complex, as well as significantly improved mitochondrial morphology. Given the importance of CoQ10 in mitigating the visible signs of skin aging, our findings identify Ubiad1 as an essential component of the defensive barriers of the epidermis.
Mitochondria, long considered to have the primary role in cellular energetic, have been the center of much research interest in the recent past. Technological advances in microscopy and development of new and specific fluorescent dyes for visualization of mitochondrial dynamics in living cells have facilitated the newfound interest in these fascinating organelles, which are now implicated in diverse cellular functions crucial in health and disease. Mitochondria play crucial roles in several age-related diseases, and in the physiology of normal aging. In this review, we discuss the structural and functional aspects of mitochondria and their implications to the aging process, as well as its significance to skin aging. Available information on active molecules that can impact the mitochondrial functions, and their potential use in skin care products is also discussed, highlighting these organelles as a new focus for anti-aging strategies in personal care.
Basal keratinocytes may divide frequently during skin lifespan, and signs of deterioration could appear such as loss of protein factors required for correct mitosis. Our findings suggest that mitotic abnormalities can be prevented by the modulation of CRM1 and survivin. We demonstrated the ability of compound 'IV08.009' to efficiently protect cultured keratinocytes from mitotic abnormalities.
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