Expression of the keratinocyte lipid transporter ABCA12 in developing and reconstituted human epidermis.

[harlequin ichthyosis]

Serious defects in the epidermal keratinocyte lipid transporter ABCA 12 are known to result in a deficient skin lipid barrier , leading to harlequin ichthyosis (HI ). HI is the most severe inherited keratinizing disorder and is frequently fatal in the perinatal period . To clarify the role of ABCA 12 , ABCA 12 expression was studied in developing human skin and HI lesions artificially reconstituted in immunodeficient mice . By immunofluorescent study , ABCA 12 was expressed in the periderm of the early stage two -layered human fetal epidermis . After formation of a three -layered epidermis , ABCA 12 staining was seen throughout the entire epidermis . ABCA 12 mRNA expression significantly increased during human skin development and reached 62 % of the expression in normal adult skin , whereas the expression rate of transglutaminase 1 , loricrin , and kallikrein 7 remained low . We transplanted keratinocytes from patients with HI and succeeded in reconstituting HI skin lesions in immunodeficient mice . The reconstituted lesions showed similar changes to those of patients with HI . Our findings demonstrate that ABCA 12 is highly expressed in fetal skin and suggest that ABCA 12 may play an essential role under both the wet and dry conditions , including the dramatic turning point from a wet environment of the amniotic fluid to a dry environment after birth .