REGULATORS FOR THE RAT CLUSTERIN GENE - DNA METHYLATION AND CIS-ACTING REGULATORY ELEMENTS

Clusterin, also known as sulphated glycoprotein-2 or testosterone-repr essed prostate message-2, is a ubiquitous protein found in a variety o f tissues and species. In the reproductive tract of the male rat, clus terin is regulated in a complex age-dependent and cell-specific manner . It is expressed at high levels in the epididymis and testis and at v ery low levels in the prostate under basal conditions. The expression of this gene in the prostate and seminal vesicles is associated with a ndrogen withdrawal, while in the testis clusterin mRNA is repressed by cyclic AMP (cAMP). To understand the mechanisms that control the expr ession of the clusterin gene better, we isolated and characterized the gene encoding rat clusterin, and analysed its cytosine methylation pa ttern in various tissues. Several putative regulatory DNA elements wer e identified, including a consensus AP-1 site in the 5' flanking regio n. Two AP-1 sites and two transforming growth factor-beta inhibitory e lements, one AP-2 site and eight half-sites for glucocorticoid/androge n response elements were found within the first intron, and one cAMP r esponse element was found in the first exon. The cytosine methylation pattern indicated that testicular or epididymal DNA in the rat is hypo methylated in the region between positions -534 and -99 of the cluster in gene, when compared with tissues with lower levels of expression su ch as prostate as well as liver, lung, kidney and spleen.