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The α-chain is a specific component of FcεRI, which is essential for the cell surface expression of FcεRI and the binding of IgE. Recently, two single nucleotide polymorphisms (SNPs) in the α-chain promoter, −315C>T and −66T>C, have been shown by statistic studies to associate with allergic diseases. The effect of −66 SNP on GATA-1-mediated promoter activity has been already indicated. In the present study, to investigate roles of the −315 SNP on the α-chain promoter functions, the transcription activity was evaluated by reporter assay. The α-chain promoter carrying −315T (minor allele) possessed significantly higher transcriptional activity than that of −315C (major allele). EMSA indicated that the transcription factor Sp1, but not Myc-associated zinc finger protein (MAZ), was bound to the −315C allele probe and that a transcription factor belonging to a high mobility group-family bound to the −315T allele probe. The chromatin immunoprecipitation assay suggested that high mobility group 1, 2, and Sp1 bound around −315 of FcεRIα genomic DNA in vivo in the human basophil cell line KU812 with −315C/T and in human peripheral blood basophils with −315C/C, respectively. When cell surface expression level of FcεRI on basophils was analyzed by flow cytometry, basophils from individuals carrying −315T allele expressed significantly higher amount of FcεRI compared with those of −315C/C. The findings demonstrate that a −315 SNP significantly affects human FcεRI α-chain promoter activity and expression level of FcεRI on basophils by binding different transcription factors to the SNP site.

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The differentiation of adipose-derived stem cells (ASCs) towards epithelial lineages has yet to be demonstrated using a standardized method. This study investigated whether keratinocyte progenitor cells are present in the ASC population. ASCs isolated from subcutaneous adipose tissue were cultured and examined for the expression of the keratinocyte progenitor markers p63 and desmoglein 3 (DSG3) by immunofluorescence microscopy and flow cytometry. In addition, p63 and DSG3 expression levels were assessed before and after differentiation of ASCs into adipocytes by real-time PCR and western blot analysis, as well as in subcutaneous adipose tissue by real-time reverse transcriptase polymerase chain reaction. Both markers were expressed in ASCs, but were downregulated after the differentiation of ASCs into adipocytes; p63-positive cells were also detected in subcutaneous adipose tissue. ASCs co-cultured with human fibroblasts and incubated with all-trans retinoic acid and bone morphologic protein 4 showed an upregulation in DSG3 level, which was also increased in the presence of type IV collagen. They also showed an upregulation in cytokeratin-5 level only in the presence of type IV collagen. These results provide the demonstration that keratinocyte progenitor cells reside in subcutaneous adipose tissue.

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