Ultraviolet B radiation modifies circadian time in epidermal skin and in subcutaneous adipose tissue

• Published in: Photodermatology, photoimmunology & photomedicine Vol. 35; no. 3; pp. 157 - 163
• Main Authors: Nikkola, Veera, Miettinen, Maija E., Karisola, Piia, Grönroos, Mari, Ylianttila, Lasse, Alenius, Harri, Snellman, Erna, Partonen, Timo
• Format: Journal Article
• Language: English
• Published: England 01.05.2019
• Subjects: circadian associated repressor of transcription (CIART); CRY1; CRY2; gene; Medicin och hälsovetenskap; mRNA; CRY1; mRNA; gene; circadian associated repressor of transcription (CIART); CRY2
• ISSN: 0905-4383; 1600-0781; 1600-0781
• DOI: 10.1111/phpp.12440

Summary Background Recent findings suggest that circadian time regulates cellular functions in the skin and may affect protection against ultraviolet radiation (UVR). It is not known, however, whether UVR through skin directly affects the expression of circadian genes. We investigated the effect of ultraviolet B (UVB) exposure on cryptochrome circadian clock 1 (CRY1), cryptochrome circadian clock 2 (CRY2), and circadian associated repressor of transcription (CIART) genes. Methods Healthy volunteers (n = 12) were exposed to narrow‐band UVB radiation of four standard erythemal dose (SED). Epidermal/dermal and subcutaneous adipose tissue samples were obtained by punch biopsies from irradiated and non‐irradiated skin 10 cm away from the irradiated site 24 hours after UVB exposure. Gene expression of CRY1, CRY2, and CIART was measured using RT‐PCR (TaqMan). Results Ultraviolet B radiation affected mRNA expression in the epidermal/dermal skin and in the subcutaneous adipose tissue. It down‐regulated expression of CRY2 gene in the epidermal/dermal skin, whereas it up‐regulated expression of CRY1 and CIART genes in the subcutaneous adipose tissue. Conclusion We showed for the first time that UVB radiation affects expression of circadian genes in the subcutaneous adipose tissue. Further studies are warranted to understand the mechanisms in detail.