Human 27-kDa heat shock protein (hsp27) gene family: chromosomal band assignments and possible involvement in Williams syndrome deletion

Abstract

The 27-kDa human heat shock protein (hsp27) is expressed in a wide variety of tissues in the absence of stress and is thought to regulate actin filament dynamics. Three related human hsp27 sequences had been previously mapped to chromosomes 3, 9, and X (McGuire et al., 1989). We have used fluorescent in situ hybridization (FISH) to correct and refine the map position of the transcribed hsp27 gene to chromosome 7, band 7q11.23 and its two pseudogenes to chromosome bands 9q21 and Xp11.2. Band 7q11.23 is the site of a deletion associated with Williams syndrome (WS), a congenital developmental disorder involving the vascular, connective tissue, and central nervous systems. We performed FISH mapping of hsp27 DNA to the chromosomes of four WS patients and found that in the majority of cells (77%), a bright signal was found on only one chromosome 7 at band 7q11.23. These results may indicate that the WS deletion includes the gene for the 27-kDa heat shock protein. However, in a small proportion of cells, a second, less intense signal was found on the other chromosome 7. We have interpreted these second weak signals as cross-hybridization due to the repeated DNA sequences (Alu sequences) known to reside within the introns and the flanking regions of this gene. Southern hybridization analysis is currently being performed to substantiate these findings in WS patient DNAs.REFERENCE: McGuire SE, Fuqua SA, Naylor SL, Helin-Davis DA, McGuire WL (1989): Chromosomal assignments of human 27-kDa heat shock protein gene family Somat Cell Mol Genet 15:167-71.