CLONING AND CHROMOSOMAL LOCATION OF THE MURINE KERATINOCYTE LIPID-BINDING PROTEIN GENE

The keratinocyte lipid-binding protein (KLBP) is a member of a large m ultigene family of intracellular fatty-acid-binding proteins. It is ex pressed in skin and tongue epithelia, adipose, lung and mammary tissue and has been found upregulated in several skin cell carcinomas and pa pillomas (Krieg et al., 1993). In order to study the regulation of KLB P expression, the murine gene has been cloned. Southern analysis using an exon 2 specific cDNA probe indicated the presence of multiple copi es of the gene in the murine genome. Based on the highly conserved str ucture of the fatty-acid-binding protein genes, the third intron of th e KLBP gene was PCR-amplified utilizing murine genomic DNA. Southern a nalysis with the intron 3 probe identified one unique gene in the muri ne genome. A full-length genomic clone of KLBP was obtained from a P1 library, and the structural gene was sequenced. Similar to the other F ABP genes, the functional KLBP gene contains four exons separated by t hree introns and maintains the conservation of size and placement of e ach exon. A functional minimal promoter was demonstrated by transient transfections of 5' upstream KLBP-luciferase reporter constructs into line 308 keratinocyte cells as well as in primary adipocytes. RT-PCR o n primary adipocyte RNA demonstrated expression of this KLBP gene by a mplification of intron 3 from the primary transcript. Fluorescence in- situ hybridization identified the murine KLBP gene as the fourth FABP gene on chromosome 3, along with myelin P2, ALBP, and intestinal FABP. These studies provide a framework for analysis of KLBP expression in normal and pathophysiological conditions. (C) 1998 Published by Elsevi er Science B.V. All rights reserved.