Developmental expression of the S35‐S45/SGP‐2/TRPM‐2 gene in rat testis and epididymis

Abstract

Testosterone-repressed prostate message-2 (TRPM-2) was originally isolated and cloned from the regressing ventral prostate of the rat. In this tissue, and in other hormone-dependent tissues such as the mammary gland, this gene is induced in the absence of the appropriate trophic hormone. Sequence analysis of the cDNA and genomic clones of TRPM-2 have demonstrated that the coding sequence of this gene is identical to S35-S45 (also known as SGP-2 and clusterin), which is constitutively expressed by the Sertoli cells of the adult testis. Using Northern, slot blot, S1-nuclease analysis, and in situ hybridization, we have investigated the regulation of TRPM-2 expression in the testis and epididymis during development. Slot blot analysis of RNA extracted from the testis and epididymis of 7-, 14-, 28-, 35-, and 91-day-old rats demonstrates that the gene is induced to detectable levels between days 7 and 14 and that the relative level of expression does not change significantly after day 14. In situ hybridization using frozen sections of testis from day 2-, 7-, 14-, 28-, 35-, and 91-day-old rats confirms that there is little expression of TPRM-2 in the seminiferous epithelium of 7-day-old rats, but this increases considerably after 14 days, primarily in Sertoli cells but also in association with meiotic developing spermatogenic cells. However, TRPM-2 mRNA is expressed in the rete testis at 2 days of age, reaches a peak at 35 days of age, and continues to be expressed in the adult. Slot blot analysis demonstrates that TRPM-2 is also induced in the epididymis between 7 and 14 days of age, although, as has been demonstrated by in situ hybridization, TRPM-2 mRNA is detectable in the epithelial cells in the head of the epididymis but is barely detectable in the midportion or tail regions. Northern analysis suggests that the size of the TRPM-2 transcript in the testis also changes during development. In the early stages of testicular development, the TRPM-2 transcript appears to be a broad band of approximately 1.5 kb, while the transcript in the adult appears to be approximately 1.8 kb in length. S1-nuclease protection assays suggest that this increase in size is not due to differential splicing of the first exon of TRPM-2/SGP-2 and most probably reflects a difference in the polyadenylation of the mRNA in the testis at different times during development.

Relationship of a Mouse Sertoli Cell Line (MSC-1) to Normal Sertoli Cells1

“…Although there is evidence that germ cells may produce ABP and SGP-2 [34,35], it seems unlikely that MSC-1 cells contain a contaminating germ cell line, since the cDNA probe for transferrin used on mRNA from MSC-1 cells did not detect a band in the region of hemiferrin, which is present in germ cells [36]. In addition, these cells do not express protamine associated with round and elongated spermatids [16].…”

Caspase-independent cell death?

“…In mammalian spermatogenesis, apoptosis is common, and genetic disruptions of the Bax-Bcl-2 and other regulatory pathways distort spermatogenesis in usually predictable ways. However, fertility is often not completely disrupted, and spermatogenesis occasionally continues in the face of presumptive catastrophic interference with apoptosis, indicating that the decision-making regulation still functions and that alternative pathways can be found Zakeri et al, 1992;Knudson et al, 1995;Miller et al, 1997;Print and Loveland, 2000;Kierszenbaum, 2001;Sinha Hikim et al, 2003).…”

Apoptosis, tumour invasion and prostate cancer

“…It has subsequently been shown that clusterin is expressed in a wide variety of tissues undergoing apoptosis [74]. Although the expression of the gene is not confined exclusively to dying cells in other CATHE PSI NS COLLAGENASES b c systems (particularly the testis and liver [75][76][77]), it clearly plays an integral part in the death of prostatic secretory epithelial cells. While the role of clusterin in cell death is still not established firmly, the Protein appears to be involved in controlling cholesterol efflux from the membranes of the dying cells and facilitating the transfer of cholesterol to ApoA-I/HDL, and in protecting the membrane from complement fixation [ 7 8 ] .…”