Identification Of Differentially Expressed Genes In Anagen Dermal Papilla By Suppression Subtractive Hybridization

Hair has many useful biologic functions and is psychosocially important in our society, patients with hair loss (alopecia) or hypertrichosis often suffer tremendously. Progress in our understanding of the biology and pathology of hair follicles would lead to more effective therapies for disorders of hair growth.The hair follicle cyclically traverses three alternating phases of organ growth, including hair shaft formation (anagen), organ involution (catagen) and relative quiescence (telogen). Highly developed properties of the hair follicle, especially its cycling ability, have made it of great interest to biologists. The hair growth cycles reflect a tightly coordinated process characterized by apoptosis and differentiation of the proximal epithelial hair bulb, perifollicular proteolysis and matrix remodeling, as well as follicular melanogenesis. Those cyclic activeities of the hair follicle are governed by the epithetlial-mesenchymal interactions between hair follicle keratinocytes and fibroblasts of the dermal papilla. The hair follicle transition from telogen to anagen is a unique processs of organ regeneration characterized by sudden activeation of cell proliferation in the follicular epithetlium (bulge) containing HF stem cells.Although many studies have focused on cytokine production, secretion of chemical mediators and inflammatory infiltration, little of the changes are known in gene expression within anagen follicle. Because each follicle has its own inherent rhythm, and the cycles are asynchronous, the major problem when studying hair follicle cycles is the lack of model mimicking the three alternating phases, especially its telogen and anagen. Many evidences suggest that alopecia areata is an ideal model in investigation of hair growth cycles. The earliest clinical evidence of the disease is an increase in telogen shedding, which is usually focal and then spreads in a centrifugal pattern. Eckert et al concluded that alopecia areata progresses as a wave as anagen follicles are precipitated prematurely into the telogen state. Supported by the National Science Foundation of China (No 30200249) and Chongqing Scientific Foundation Committee for the major projects (No 2001-8-4)In established bald patches, most of follicles are in telogen, suggesting that there is a block in the process of follicular development beyond the stage of anagen. Therefore, we can use hair follicles in non-bald area and bald patches as models of anagen and telogen respectively to study hair follicle growth regulation. Hair dermal papilla cells located at the bottom of hair follicles play pivotal roles in hair formation, growth and cycling. Since the fundamental work of Oliver, it has been demonstrated many times that the follicular papilla is inherently able to induce follicle formation. Even if maintained in culture and transplanted onto normal skin in vivo, Hair dermal papilla cells retain their abilities to induce hair growth. Our previous work has established an efficient method for isolation of dermal papilla for the study of the progression of hair growth. A powerful approach for studying the genetic nature of many biological processes is to characterize genes that vary in expression level during this process. Several methods have been reported for detecting differentially expressed genes abnormal tissues as compared with the corresponding normal tissues, such as differential display (DD), expressed sequenced tag (EST) analysis, subtractive hybridization and serial analysis of gene expression (SAGE). More recently microarray technology attracts great interest and continues to hold promise for studies on human diseases states. However, these methods are often laborious and generally require a large amount of mRNA, which is difficult to obtain from clinical materials, especially from hair follicles. Recent studies reveal that rare mRNAs (fewer than five copies/cell) comprise the majority of total species of transcripts, and they constitute only a small portion of the total number of transcripts, whereas a small...