Self-Improvement of Keratinocyte Differentiation Defects During Skin Maturation in ABCA12-Deficient Harlequin Ichthyosis Model Mice
Authors
Yanagi T, Akiyama M, Nishihara H, Ishikawa J, Sakai K, Miyamura Y, Naoe A, Kitahara T, Tanaka S, Shimizu H.
Institution
Department of Dermatology, Laboratory of Translational Pathology, Laboratory of Cancer Research, Department of Pathology, Hokkaido University Graduate School of Medicine, Sapporo; and Tochigi Research Laboratories, Kao Corporation, Ichikai, Haga, Tochigi
Country
Japan
Year
2010
Journal
The American Journal of Pathology
Abstract
Harlequin ichthyosis (HI) is caused by loss-of-function mutations in the keratinocyte lipid transporter ABCA12. The patients often die in the first 1 or 2 weeks of life, although HI survivors' phenotypes improve within several weeks after birth. In order to clarify the mechanisms of phenotypic recovery, we studied grafted skin and keratinocytes from Abca12-disrupted (Abca12(-/-)) mice showing abnormal lipid transport. Abca12(-/-) neonatal epidermis showed significantly reduced total ceramide amounts and aberrant ceramide composition. Immunofluorescence and immunoblotting of Abca12(-/-) neonatal epidermis revealed defective profilaggrin/filaggrin conversion and reduced protein expression of the differentiation-specific molecules, loricrin, kallikrein 5, and transglutaminase 1, although their mRNA expression was up-regulated. In contrast, Abca12(-/-) skin grafts kept in a dry environment exhibited dramatic improvements in all these abnormalities. Increased transepidermal water loss, a parameter representing barrier defect, was remarkably decreased in grafted Abca12(-/-) skin. Ten-passage sub-cultured Abca12(-/-) keratinocytes showed restoration of intact ceramide distribution, differentiation-specific protein expression and profilaggrin/filaggrin conversion, which were defective in primary-cultures. Using cDNA microarray analysis, lipid transporters including four ATP-binding cassette transporters were up-regulated after sub-culture of Abca12(-/-) keratinocytes compared with primary-culture. These results indicate that disrupted keratinocyte differentiation during the fetal development is involved in the pathomechanism of HI and, during maturation, Abca12(-/-) epidermal keratinocytes regain normal differentiation processes. This restoration may account for the skin phenotype improvement observed in HI survivors.
Product use
Isolation and cultivation of primary keratiocytes; differentiation; total RNA extraction and RT-PCR; and protein extractions, radioimmunoprecipitation assay for western blotting; immunofluorescence; DNA microarray analysis for the gene expression profile;