EXPRESSION OF CLUSTERIN IN CELL-DIFFERENTIATION AND CELL-DEATH

Clusterin, originally isolated as testosterone-repressed prostate mess age-2 from regressing rat ventral prostate, has been identified with t he process of active cell death (ACD). The clusterin gene product is a glycosylated dimer consisting of alpha and beta subunits, resulting f rom the 70-kilodalton preprotein. To determine its relationship with A CD, we have examined clusterin expression via in situ hybridization an d immunohistochemistry. Clusterin message is detected in the supportin g cells in both testes and ovaries and the protein surrounds the matur e germ cells. The highest level of expression was found in the head re gion of the epididymis. Clusterin message is also detected in selected cells of uterine glands and ducts both in the normal and pregnant ute rus. The expression of clusterin in the developing embryo is most abun dant in the choroid plexus, inner ear, and epithelium of the eye. None of the cells in the testes, epididymis, or embryo that express cluste rin are undergoing ACD. The expression of clusterin appears to correla te with cell remodelling or differentiation that occurs during these p eriods of development. However, in the female reproductive system, we found clusterin to be expressed in both differentiating as well as dyi ng cells. These results suggest that clusterin may provide support for cells undergoing specific biochemical and (or) physical changes. Our results are consistent with the hypothesis that clusterin is an antiin flammatory agent.