Presenilin-1 protein specifically expressed in Leydig cells with its expression level increased during rat testis development

Presenilin-1 mutations of which cause the early-onset of Alzheimer's. disea se, was shown to be abundantly expressed in the testis as well as the brain . In spite of the high expression level of this protein in the testis, no f urther analysis has been undertaken. We aimed to study the distribution and developmental changes in presenilin-1 protein, and to provide clues so as to elucidate the role of this protein in the rat testis, To evaluate the sp ecificity of the anti presenilin-1 antibody, rat presenilin-1 protein was e xpressed in COS-7 cells and the recombinant protein was used for western bl ot analysis. A positive band of approximately 20 kDa corresponding to the C -terminal fragment of proteolyzed presenilin-1 protein was observed. Using testis:and brain tissue samples, a 20 kDa band was detected in both tissues suggesting a similar proteolytic process, but the expression level in the testis was higher than that in the brain, The expression level increased si gnificantly during postnatal testis development. By an immunohistochemical analysis of the rat testis, a strong signal was observed in interstitial ce lls and further study with cultured TM3 murine Leydig cells revealed an abu ndant expression of presenilin-1 in Leydig cells. Our study suggests that p resenilin-1 expression in Leydig cells may play an important: role in Leydi g cell function and testis development. (C) 1999 Elsevier Science Ltd. All rights reserved.