Effect of germ cell depletion on levels of specific mRNA transcripts in mouse Sertoli cells and Leydig cells

Abstract

It has been shown that testicular germ cell development is critically dependent upon somatic cell activity but, conversely, the extent to which germ cells normally regulate somatic cell function is less clear. This study was designed, therefore, to examine the effect of germ cell depletion on Sertoli cell and Leydig cell transcript levels. Mice were treated with busulphan to deplete the germ cell population and levels of mRNA transcripts encoding 26 Sertoli cell-specific proteins and 6 Leydig cell proteins were measured by real-time PCR up to 50 days after treatment. Spermatogonia were lost from the testis between 5 and 10 days after treatment, while spermatocytes were depleted after 10 days and spermatids after 20 days. By 30 days after treatment, most tubules were devoid of germ cells. Circulating FSH and intratesticular testosterone were not significantly affected by treatment. Of the 26 Sertoli cell markers tested, 13 showed no change in transcript levels after busulphan treatment, 2 showed decreased levels, 9 showed increased levels and 2 showed a biphasic response. In 60% of cases, changes in transcript levels occurred after the loss of the spermatids. Levels of mRNA transcripts encoding Leydig cell-specific products related to steroidogenesis were unaffected by treatment. Results indicate (1) that germ cells play a major and widespread role in the regulation of Sertoli cell activity, (2) most changes in transcript levels are associated with the loss of spermatids and (3) Leydig cell steroidogenesis is largely unaffected by germ cell ablation.

Leydig cell re-generation and expression of cell signaling molecules in the germ cell-free testis

“…This contrasts with normal rats in which testosterone levels begin to recover between 14 and 21 days after EDS (Molenaar et al 1986, Edwards et al 1988b, Sharpe et al 1990, Ariyaratne et al 2003. It is known that germ cell depletion affects Sertoli cell function (McKinnell & Sharpe 1997, Guitton et al 2000, O'Shaughnessy et al 2008 and so the accelerated re-generation of active Leydig cells in germ cell-depleted testes may be due to altered Sertoli cell activity. Alternatively, LH is required for re-generation of Leydig cells after EDS treatment (Molenaar et al 1986, Teerds et al 1989) and levels of LH are higher in germ cell-free animals treated with EDS compared with normal EDStreated animals (Morris & Jackson 1978, Molenaar et al 1986).…”

On the role of germ cells in mammalian gonad development: quiet passengers or back-seat drivers?

“…Studies in medaka, where germ cells were depleted by a morpholino-mediated knockdown of cxcr4, a gene required for PGC migration, revealed a similar pattern, with deficiency of the germline leading to (Nekola & Nalbandov (1971) and Hubbard & Erickson (1988)) Increased progesterone and decreased oestradiol (Vanderhyden et al 1993(Vanderhyden et al , 1998 Transdifferentiation (Behringer et al (1990), Couse et al (1999) and Guigon et al (2005)) Normal development (Uhlenhaut et al (2009) Differential expression of somatic genes Maguire et al (1993), McKinnell & Sharpe (1997), Jonsson et al (1999) and (O'Shaughnessy et al (2008) Normal development (Merchant (1975) and Maatouk et al (2012)) Normal development (Handel & Eppig (1979), McCoshen (1982 and Hashimoto et al (1990)) Normal development, no evidence of differentiation in red-eared slider turtle (DiNapoli & Capel (2007)) Normal development, no evidence of differentiation in loach and goldfish (Fujimoto et al (2010) and Goto et al (2012)) Gonad degeneration (Piprek et al (2012)) Survival of intermingled somatic cells is dependanton GC signalling (Gilboa & Lehmann (2006)) Differentiation and proliferation of follicles are dependant on GC signalling (Lopez-Schier & St Johnston (2001)) Production of male-only offspring in zebrafish and medaka (Slanchev et al (2005), Houwing et al (2007), Kurokawa et al (2007), Siegfried & Nusslein-Volhard (2008 and Dranow et al (2013) Non-developed ovaries Merchant-Larios & Centeno (1981) Non-developed ovaries (McCoshen (1982)) Transdifferentiation (Taketo-Hosotani et al (1985), Vigier et al (1987) and ...…”

“…Germ cell-conditioned medium was found to regulate E 2 and androgen-binding protein secretion by immature rat Sertoli cells (Le Magueresse & Jegou 1986). Finally, busulfan treatment of adult mice resulted in increased expression of nine different genes encoding Sertoli cell markers and decreased expression of two others (O'Shaughnessy et al 2008). It is worth noting, however, that busulfan acts on all proliferative cells, hence it is possible that the observed effects on somatic cells is due to general toxicity.…”

Anti-Müllerian hormone is a gonadal cytokine with two circulating forms and cryptic actions

“…The number and state of the germ cells in the gonads is the major determinant of the level of AMH in the circulation. This is most clearly established for females (Visser et al 2012), but it may also be the case for males, as germ cells regulate Sertoli cells (O'Shaughnessy et al 2008, Cool et al 2012, Dabaja et al 2015. Consequently, AMH is uniquely and ideally placed to convey information about the current and future reproductive capacity of an individual.…”