Aging Cell (2006) 5, pp331–344 Doi: 10.1111/j.1474-9726.2006.00223.x © 2006 The Authors 331 Journal compilation © Blackwell Publishing Ltd/Anatomical Society of Great Britain and Ireland 2006 Blackwell Publishing Ltd Age-specific hormonal decline is accompanied by transcriptional changes in human sebocytes in vitro Evgenia Makrantonaki, 1,3 James Adjaye, 2 Ralf Herwig, 2 Thore C. Brink, 2 Detlef Groth, 2 Claus Hultschig, 2 Hans Lehrach 2 and Christos C. Zouboulis 1,3 1 Laboratory for Biogerontology, Dermato-Pharmacology and Dermato-Endocrinology, Institute of Clinical Pharmacology and Toxicology, Charité Universitaetsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12200 Berlin, Germany 2 Department of Vertebrate Genomics, Max Planck Institute for Molecular Genetics, Ihnestrasse 73, 14195 Berlin, Germany 3 Departments of Dermatology and Immunology, Dessau Medical Center, Auenweg 38, 06847 Dessau, Germany Summary The importance of hormones in endogenous aging has been displayed by recent studies performed on animal models and humans. To decipher the molecular mechanisms involved in aging we maintained human sebocytes at defined hormone-substituted conditions that corresponded to average serum levels of females from 20 (f20) to 60 (f60) years of age. The corresponding hormone receptor expression was demonstrated by reverse transcription– polymerase chain reaction (RT–PCR), Western blotting and immunocytochemistry. Cells at f60 produced significantly lower lipids than at f20. Increased mRNA and protein levels of c-Myc and increased protein levels of FN1, which have been associated with aging, were detected in SZ95 sebocytes at f60 compared to those detected at f20 after 5 days of treatment. Expression profiling employing a cDNA microarray composed of 15 529 cDNAs identified 899 genes with altered expression levels at f20 vs. f60. Confirmation of gene regulation was performed by real-time RT–PCR. The functional annotation of these genes according to the Gene Ontology identified pathways related to mitochondrial function, oxidative stress, ubiquitin-mediated proteolysis, cell cycle, immune responses, steroid biosynthesis and phospholipid degradation – all hallmarks of aging. Twenty- five genes in common with those identified in aging kidneys and several genes involved in neurodegenerative diseases were also detected. This is the first report describing the transcriptome of human sebocytes and its modification by a cocktail of hormones administered in age-specific levels and provides an in vitro model system, which approximates some of the hormone-dependent changes in gene transcrip- tion that occur during aging in humans. Key words: cDNA microarray; c-Myc; FN1; growth factors; hormonal aging; neurodegenerative diseases, sebaceous cells; sebaceous lipids; signaling pathways; steroids. Introduction Some of the theories regarding the generation of endogenous aging support cellular senescence and decreased proliferative ability (Hayflick, 1965; Smith & Pereira-Smith, 1996), reduction of cellular DNA repair capacity, loss of telomeres with advancing age (Allsopp et al., 1992; Bodnar et al., 1998), point mutations of extranuclear mitochondrial DNA (Michikawa et al., 1999) which may be associated with increased oxidative stress (Miquel, 1998) and increased frequency of chromosomal abnormalities (Benn, 1976; Ly et al., 2000). Complimentary evidence of the importance of hormones and their metabolism on the aging process has come from recent studies performed on animal models (Simon et al., 2003; Tatar et al., 2003). This is not surprising as age-specific processes in humans such as puberty and menopause are also controlled hormonally. Serum levels of hormones decline with age in female and male individuals (Roshan et al., 1999). This is due to decreased functional reserve of the endocrine organs as a result of aging per se or secondarily due to concurrent disease. Skin, the largest organ of the body, usually provides the first obvious evidence of the aging process and can be used as a model for better understanding of the alterations occurring with advancing age. Furthermore, as skin is the target for a plethora of hormones and also a peripheral endocrine organ in its own right (Zouboulis, 2000), it can be affected to a large extent by the decline of hormones (Brincat, 2000). During endogenous skin aging – observed in skin areas, which are not in direct contact with environmental factors such as ultraviolet (UV) irradiation – skin gradually loses its structural and functional characteristics (Braverman & Fonferko, 1982; Moragas et al., 1993; Ghadially et al., 1995; Fisher et al., 2002; Raine-Fenning et al ., 2003; Wulf et al ., 2004). In particular, morphological changes of the sebaceous gland cells and altera- tions of their activity play a distinct role in the aging phenotype of the skin. The size of sebaceous gland cells tends to decrease with advancing age, while their number remains approximately the same throughout life (Zouboulis & Boschnakow, 2001). Further- more, sebaceous gland cells show an age-related reduced secretory Evgenia Makrantonaki, James Adjaye and Ralf Herwig contributed equally to this work. Correspondence Prof. Christos C. Zouboulis, Departments of Dermatology and Immunology, Dessau Medical Center, Auenweg 38, 06847 Dessau, Germany. Tel.: 49-340-5014000; fax: 49-340-5014025; e-mail: christos.zouboulis@klinikum-dessau.de Accepted for publication 13 May 2006