ABSTRACT
BACKGROUND: Intrinsic and extrinsic factors, including ultraviolet irradiation, lead to visible signs of skin aging. OBJECTIVE: We evaluated molecular changes occurring in photoexposed and photoprotected skin of white women 20 to 74 years of age, some of whom appeared substantially younger than their chronologic age. METHODS: Histologic and transcriptomics profiling were conducted on skin biopsy samples of photoexposed (face and dorsal forearm) or photoprotected (buttocks) body sites from 158 women. 23andMe genotyping determined genetic ancestry. RESULTS: Gene expression and ontologic analysis revealed progressive changes from the 20s to the 70s in pathways related to oxidative stress, energy metabolism, senescence, and epidermal barrier; these changes were accelerated in the 60s and 70s. The gene expression patterns from the subset of women who were younger-appearing were similar to those in women who were actually younger. LIMITATIONS: Broader application of these findings (eg, across races and Fitzpatrick skin types) will require further studies. CONCLUSIONS: This study demonstrates a wide range of molecular processes in skin affected by aging, providing relevant targets for improving the condition of aging skin at different life stages and defining a molecular pattern of epidermal gene expression in women who appear younger than their chronologic age.
Subject(s)
Genetic Predisposition to Disease , Skin Aging/genetics , Skin Aging/physiology , Ultraviolet Rays/adverse effects , Adult , Aged , Aged, 80 and over , Biopsy, Needle , Facial Dermatoses/genetics , Facial Dermatoses/pathology , Female , Humans , Immunohistochemistry , Middle Aged , Prognosis , Risk Factors , Skin Aging/pathology , White People , Young AdultABSTRACT
Many laboratories identify proteins by searching tandem mass spectrometry data against genomic or protein sequence databases. These database searches typically use the measured peptide masses or the derived peptide sequence and, in this paper, we focus on the latter. We study the minimum peptide sequence data requirements for definitive protein identification from protein sequence databases. Accurate mass measurements are not needed for definitive protein identification, even when a limited amount of sequence data is available for searching. This information has implications for the mass spectrometry performance (and cost), data base search strategies and proteomics research.