The overall goal of this mentored research program is to provide the P.I. with the opportunity to develop further the cognitive, technical and interpretive skills required to pursue her career goal of combining clinical practice with basic research. The specific goal of the experiments proposed is to elucidate androgens' role in controlling the development and differentiation of the sebaceous gland (SG). Androgens are thought to modulate sebum production by the SG and, thereby, to contribute to the development of acne vulgaris, a prevalent disease associated with significant physical and psychological morbidity. Understanding the mechanisms regulating SG growth and lipogenesis by androgens is essential for developing rationale strategies to control sebum production and acne. In order to characterize these mechanisms we have established an organotypic culture (histoculture) system for propagating intact human SG in the presence and absence of their native dermal fibroblasts. Manipulating this system, using androgens, inhibitors of androgen metabolizing enzymes and growth factors, and tissue specific ribozyme constructs to prevent selectively the translation of individual transcripts, will enable us to test the following hypotheses: i) Conversion of testosterone to dihydrotestosterone by type 1 5a-reductase in fibroblasts and sebocytes is an obligatory step in the modulation of SG growth and lipid production and; ii) Growth and lipid production of SG is regulated by paracrine interactions between growth factors and androgens. We will determine if androgens act on the SG only directly, or also indirectly via dermal fibroblasts. Should fibroblasts prove to be involved in mediating some actions of androgens on SG growth and lipid production, we will determine if growth factors generated by fibroblasts, specifically epidermal growth factor, insulin-like growth factor-I and keratinocyte growth factor, are involved in this process. Endpoints for assessing sebaceous gland growth will include, incorporation of 3H thymidine, Ki-67 immunocytochemistry and histology. Lipogenesis will be determined using incorporation of 14C-acetate into lipids. Pharmacological inhibitors of each of the enzymes involved in the metabolism of androgens, and which are known to be expressed in human SG, will be used to identify the role of individual C-19 steroids in modulating specific aspects of growth and lipid production by SG. Results on the role of 1 5alpha-reductase, androgen receptor and growth factor of interest will be confirmed by transfecting sebocytes and dermal fibroblasts with a construct containing a novel triple ribozyme, driven by tissue-specific promoters, which will selectively cleave transcript for the enzyme, receptor or peptide.
| Thiboutot, Diane; Jabara, Sami; McAllister, Jan M et al. (2003) Human skin is a steroidogenic tissue: steroidogenic enzymes and cofactors are expressed in epidermis, normal sebocytes, and an immortalized sebocyte cell line (SEB-1). J Invest Dermatol 120:905-14 |
| Thiboutot, D; Sivarajah, A; Gilliland, K et al. (2000) The melanocortin 5 receptor is expressed in human sebaceous glands and rat preputial cells. J Invest Dermatol 115:614-9 |
| Thiboutot, D; Bayne, E; Thorne, J et al. (2000) Immunolocalization of 5alpha-reductase isozymes in acne lesions and normal skin. Arch Dermatol 136:1125-9 |
| Thiboutot, D; Gilliland, K; Light, J et al. (1999) Androgen metabolism in sebaceous glands from subjects with and without acne. Arch Dermatol 135:1041-5 |
| Thiboutot, D; Martin, P; Volikos, L et al. (1998) Oxidative activity of the type 2 isozyme of 17beta-hydroxysteroid dehydrogenase (17beta-HSD) predominates in human sebaceous glands. J Invest Dermatol 111:390-5 |
