P3.30 Cloning, Expression and Characterization of Human URB

So-Young Cha, Young Kwan Sung, Sanguk Im, Jin Oh Kim, Jung-Chul Kim, Moon-Kyu Kim

Department of Immunology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.

Objectives: In an attempt to identify genes specifically involved in hair development or cycle, we have recently compared gene expression profiles between cultured dermal papilla cells and dermal fibroblasts using cDNA microarray analysis. This analysis led us to identify a number of gene transcripts that are differentially expressed in dermal papilla cells. In this study, we characterized a novel gene, named human URB, which shows striking homology to mouse URB (up-regulated in bombesin receptor subtype 3 deficient mice).

Methods: Northern blots, western blots, and immunohistochemical staining analyses were employed to study expression and to characterize human URB. Sequences were also analysed by various bioinformatics tools.

Results: Human URB encodes a 950 amino acid protein residue and showed high homology to chick equarin-L and rat steroid sensitive gene-1. Human URB mRNA was strongly expressed in prostate, testis, ovary and small intestine in adult tissues. Antibodies against URB showed cytoplasmic staining in cultured dermal papilla cells and detected a predicted 108 kDa protein. URB expression was higher in dermal papilla cells compared to dermal fibroblasts by Northern and Western blot analyses. Antibodies also showed robust immunoreactivity in dermal papilla of human hair follicles and in all muscle layers in mouse embryos.

Conclusions: It is unlikely that URB is specifically involved in the development and maintenance of hair growth because URB is expressed in a muscle-specific pattern in mouse tissues. Instead, we think URB may be a gene that is enriched in myofibroblastic cells. Although further investigation is needed to elucidate the biological function of URB in dermal papilla, the muscle-specific expression pattern of URB will provide an invaluable tool to researchers interested in these tissues.