ARS Component B: structural characterization, tissue expression and regulation of the gene and protein (SLURP-1) associated with Mal de Meleda

The ARS Component B gene (EMBL ID: HSARS81S, AC: X99977) encodes a 9 kD non-glycosylated polypeptide (also known as SLURP-1, SwissProt/TrEMBL: P55000), a soluble member of the human Ly6/uPAR superfamily. ARS Component B gene mutations have been implicated in Mal de Meleda. In this study we show by immunohistochemistry that SLURP-1 (secreted Ly-6/uPAR related protein, the protein product of the ARS Component B gene) is localized to human skin, exocervix, gums, stomach and esophagus. In the epidermis, keratinocytes underlying the stratum corneum are highly positive for SLURP1 immunostaining and cultured keratinocytes secrete the expected 9 kD protein. Circulating SLURP1 is detected in human plasma and urine. In the mouse, expression is evident in skin, eye, whole lung, trachea, esophagus and stomach. Human ARS Component B mRNA expression is regulated by retinoic acid, epidermal growth factor and interferon-gamma. The tissue localization and the association with Mal de Meleda suggest that ARS Component B and its protein product SLURP1 are implicated in maintaining the physiological and structural integrity of the keratinocyte layers of the skin.