- Epithelial stem cells are responsible for the continual regeneration and homeostasis of all self-renewing tissues such as the epidermis, hair follicle, corneal epithelium, and seminiferous epithelium. The applicant originally identified groups of epithelial stem cells in the limbal epithelium of the cornea, and in the bulge region of the outer root sheath of the hair follicle. The long-term goals of this project are to advance our understanding of these epithelial stem cells by identifying genes that are preferentially expressed or unique to stem cell-rich areas such as the bulge. It is hypothesized in this proposal that molecules unique or upregulated in stem cell-rich tissue are responsible for maintaining their stem cell attributes (e.g., slow-cycling and high proliferative potential). Using a PCR-based subtraction hybridization technique, the principal investigator has isolated four partial cDNA clones which appear to be differentially expressed in cultured outer root sheath cells from the bulge. In addition, he created a cell line and a cDNA library from these cells. Screening this library with a candidate clone, he obtained a nearly full-length sequence of a previously undescribed cDNA (B10) that appears to be preferentially expressed in outer root sheath cells. This clone has also been found in testis. The research objective of the proposal is to characterize the expression of this gene and its protein product in epithelial tissues with known populations of stem cells to evaluate its potential as a stem cell marker. Because the hair follicle serves as a model for mesenchymal-epithelial interactions, any insight into the specific molecules elaborated by epithelial stem cells could have broad implications on our understanding of epithelial differentiation and proliferation. Additionally, patients with disorders of proliferating tissues such as alopecia, basal cell carcinoma, chronic wounds, or oligospermia may ultimately benefit from this research.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29AR044038-03
Application #
2683341
Study Section
General Medicine A Subcommittee 2 (GMA)
Project Start
1996-04-01
Project End
2001-03-31
Budget Start
1998-04-01
Budget End
1999-03-31
Support Year
3
Fiscal Year
1998
Total Cost
Indirect Cost
Name
University of Pennsylvania
Department
Dermatology
Type
Schools of Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Liu, Yaping; Lyle, Stephen; Yang, Zaixin et al. (2003) Keratin 15 promoter targets putative epithelial stem cells in the hair follicle bulge. J Invest Dermatol 121:963-8
Xu, Xiaowei; Lyle, Stephen; Liu, Yaping et al. (2003) Differential expression of cyclin D1 in the human hair follicle. Am J Pathol 163:969-78
Lyle, S; Christofidou-Solomidou, M; Liu, Y et al. (1999) Human hair follicle bulge cells are biochemically distinct and possess an epithelial stem cell phenotype. J Investig Dermatol Symp Proc 4:296-301
Jih, D M; Lyle, S; Elenitsas, R et al. (1999) Cytokeratin 15 expression in trichoepitheliomas and a subset of basal cell carcinomas suggests they originate from hair follicle stem cells. J Cutan Pathol 26:113-8