Katja Reuschlein

Natural Arctium lappa fruit extract improves the clinical signs of aging skin

Background  Subclinical, chronic tissue inflammation involving the generation of cytokines (e.g., interleukin‐6 and tumor necrosis factor‐alpha) might contribute to the cutaneous aging process.

A novel treatment option for photoaged skin

Background  DNA damage as a result of ultraviolet (UV) exposure plays an important role in the progression of cutaneous aging. Both folic acid and creatine have been linked to the process of DNA protection and repair.

Damage at the root of cell renewal—UV sensitivity of human epidermal stem cells

BACKGROUND The epidermis harbors adult stem cells that reside in the basal layer and ensure the continuous maintenance of tissue homeostasis. Various studies imply that stem cells generally possess specific defense mechanisms against several forms of exogenous stress factors. As sun exposition is the most prevalent impact on human skin, this feature would be of particular importance in terms of sensitivity to UV-induced DNA damage. OBJECTIVE To investigate whether human epidermal stem cells are susceptible to UV-induced DNA damage and subsequent functional impairment. METHODS A method to isolate human epidermal stem cells from suction blister epidermis was established and validated. Volunteers were treated with solar-simulated irradiation on test areas of the forearm and stem cells were isolated from suction blister material of this region. DNA damage was analyzed by staining for cyclobutane thymidine dimers. The functional consequences of UV-induced damages were assessed by colony forming efficiency assays and gene expression analyses. RESULTS Compared to an unirradiated control, stem cells isolated from areas that were exposed to solar-simulated radiation showed significantly more DNA lesions. Although the number of stem cells was not reduced by this treatment, a functional impairment of stem cells could be shown by reduced colony forming efficiency and altered gene expression of stem cell markers. CONCLUSIONS Despite their essential role in skin maintenance, epidermal stem cells are sensitive to physiological doses of UV irradiation in vivo.

Poly(A) tail shortening correlates with mRNA repression in tropoelastin regulation

BACKGROUND It has been shown for various organisms that expression of tropoelastin (TE) is high during fetal and neonatal growth and that it is reduced in adulthood by an unknown mechanism. OBJECTIVE To highlight the process of TE mRNA repression in vivo, total RNA from human skin biopsies was analyzed and TE mRNA expression was compared in fetal and adult donors. METHODS TaqMan Real-Time PCR, Poly(A) tail length assay, immunoblot. RESULTS In this study a more than 30-fold reduction of mature TE mRNA was detected whereas the decline on pre-mRNA level was not pronounced. This finding supports the hypothesis that the repression of mature TE mRNA is for the most part due to posttranscriptional mechanisms. Since deadenylation-dependent mRNA destabilization is the major decay pathway for most mRNAs, poly(A) tail length of mature TE mRNA was analyzed in fetal and adult human skin, lung and uterus, showing a profound reduction of poly(A) tail length in the adult samples. While TE mRNA is repressed in adult tissues in vivo, TGF-ß(1) has been shown to induce expression of TE mRNA in vitro on the posttranscriptional level. To analyze the underlying mechanism, TE mRNA poly(A) tail length was analyzed in human dermal fibroblasts after treatment with TGF-ß(1)in vitro. Besides the expected increase in TE expression, TGF-ß(1) treatment resulted in a significant stabilization of TE mRNA poly(A) tail length. CONCLUSION Our findings correlate for the first time TE expression level with poly(A) tail length and suggest that maintenance of poly(A) tail and deadenylation of TE mRNA might be general mechanisms involved in the regulation of TE expression.