Ximena Maria Muresan1, Marie-Sophie Narzt2, Brittany Woodby3, Francesca Ferrara4, Florian Gruber2, Giuseppe Valacchi5. 1. Department Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy. 2. Department of Dermatology, Medical University of Vienna, Christian Doppler Laboratory for Biotechnology of Skin Aging, Vienna, Austria. 3. Plants for Human Health Institute, Animal Sciences Dept., NC Research Campus, NC State University, NC, USA. 4. Department Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy; Department of Dermatology, Medical University of Vienna, Christian Doppler Laboratory for Biotechnology of Skin Aging, Vienna, Austria; Plants for Human Health Institute, Animal Sciences Dept., NC Research Campus, NC State University, NC, USA. 5. Department Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy; Plants for Human Health Institute, Animal Sciences Dept., NC Research Campus, NC State University, NC, USA. Electronic address: gvalacc@ncsu.edu.
Abstract
BACKGROUND: The main functions of the skin are to protect against environmental insults and prevent water loss, which are performed by the complex lipid- and protein matrix present in the outermost layers of the epithelium. The lipidome of these outer layers is mainly composed of ceramides, fatty acids, and cholesterol, which regulates keratinocyte differentiation and skin barrier function. SR-B1 is a multifunctional scavenger receptor that is best known for facilitating uptake of cholesterol from HDL particles in the liver, but it is also expressed in the skin. OBJECTIVE: To determine the role of SR-B1 in keratinocyte differentiation. METHODS: We investigated the relationship between SR-B1 and keratinocyte differentiation using a physiologically relevant model, organotypic skin equivalents (SEs), wherein SR-B1 was knocked down via siRNA transfection. To assess effects of SR-B1 knockdown on keratinocyte differentiation, we performed hematoxylin/eosin staining, RT-PCR, western blotting, and immunohistochemistry. We also examined the effect of SR-B1 knockdown on lipid production by performing Oil Red O staining and thin layer chromatography. RESULTS: SR-B1 knockdown resulted in decreased lipid levels in SEs, specifically ceramides, and in decreased transcript levels of LDLR, PPAR-α and PPAR-γ, which are factors involved in regulating ceramide synthesis. In addition, filaggrin levels increased in SR-B1 KD tissues, but neither keratin 14 nor keratin 10 were affected. CONCLUSION: We conclude that one of the main functions of SR-B1 in the skin is to regulate ceramide levels and thereby maintain the barrier function of the skin, resulting in the protection of cutaneous tissues from outdoor insults.
BACKGROUND: The main functions of the skin are to protect against environmental insults and prevent water loss, which are performed by the complex lipid- and protein matrix present in the outermost layers of the epithelium. The lipidome of these outer layers is mainly composed of ceramides, fatty acids, and cholesterol, which regulates keratinocyte differentiation and skin barrier function. SR-B1 is a multifunctional scavenger receptor that is best known for facilitating uptake of cholesterol from HDL particles in the liver, but it is also expressed in the skin. OBJECTIVE: To determine the role of SR-B1 in keratinocyte differentiation. METHODS: We investigated the relationship between SR-B1 and keratinocyte differentiation using a physiologically relevant model, organotypic skin equivalents (SEs), wherein SR-B1 was knocked down via siRNA transfection. To assess effects of SR-B1 knockdown on keratinocyte differentiation, we performed hematoxylin/eosin staining, RT-PCR, western blotting, and immunohistochemistry. We also examined the effect of SR-B1 knockdown on lipid production by performing Oil Red O staining and thin layer chromatography. RESULTS:SR-B1 knockdown resulted in decreased lipid levels in SEs, specifically ceramides, and in decreased transcript levels of LDLR, PPAR-α and PPAR-γ, which are factors involved in regulating ceramide synthesis. In addition, filaggrin levels increased in SR-B1 KD tissues, but neither keratin 14 nor keratin 10 were affected. CONCLUSION: We conclude that one of the main functions of SR-B1 in the skin is to regulate ceramide levels and thereby maintain the barrier function of the skin, resulting in the protection of cutaneous tissues from outdoor insults.
Authors: Benedetta Petracca; Barbara Rothen-Rutishauser; Giuseppe Valacchi; Marc Eeman Journal: J Expo Sci Environ Epidemiol Date: 2020-10-30 Impact factor: 5.563
Authors: Valentina Gentili; Daria Bortolotti; Mascia Benedusi; Andrea Alogna; Anna Fantinati; Anna Guiotto; Giulia Turrin; Carlo Cervellati; Claudio Trapella; Roberta Rizzo; Giuseppe Valacchi Journal: PLoS One Date: 2020-02-21 Impact factor: 3.240