Structure and organization of the genes encoding mouse small proline-rich proteins, mSPRR1A and 1B

Two genomic clones comprising the entire coding sequence of mouse SPRR1A an d 1B genes were isolated and sequenced. Sequence analysis of the 1A and 1B genomic clones indicated that both genes contain two exons separated by an intron slightly larger than 1.1 kb in size (1147 and 1152 nt, respectively) . This type of genomic structure is identical to the counterpart of human S PRR1 gene and other genes encoding for cornified envelope proteins. Primer extension analysis using 1A and 1B gene-specific primers indicates that 1A gene is expressed in squamous tissues such as skin and esophagus, whereas 1 B gene is expressed in papilloma tumors but not in squamous tissues. The fi rst 300 nt of 5'-flanking region of the mouse SPRR 1A and 1B genes reveal a n overall similar to 50% identity to the human counterpart. However, there is a high degree of identity (>75%) at the promoter region containing a TAT A box and TRE/TRE-like motifs. Both TATA and TRE/TRE-like motifs are almost identical in sequence and positions to those found in the counterpart of h uman promoter. Using transient transfection for the analysis of promoter ac tivity, we observed that both 1A and 1B 5'-flanking regions contain the pro moter activity to direct the expression of the reporter gene, chloramphenic ol acetyltransferase, in airway epithelial cells in a fashion similar to th at observed in the human counterpart. These results indicate a conserved na ture of genetic structure and regulation of SPRR1 gene expression between h uman and mouse. (C) 1998 Elsevier Science B.V. All rights reserved.