Gene expression ontogeny of spermatogenesis in the marmoset uncovers primate characteristics during testicular development

Abstract

Mammalian spermatogenesis has been investigated extensively in rodents and a strictly controlled developmental process has been defined at cellular and molecular levels. In comparison, primate spermatogenesis has been far less well characterized. However, important differences between primate and rodent spermatogenesis are emerging so it is not always accurate to extrapolate findings in rodents to primate systems. Here, we performed an extensive immunofluorescence study of spermatogenesis in neonatal, juvenile, and adult testes in the common marmoset (Callithrix jacchus) to determine primate-specific patterns of gene expression that underpin primate germ cell development. Initially we characterized adult spermatogonia into two main classes; mitotically active C-KIT(+)Ki67(+) cells and mitotically quiescent SALL4(+)PLZF(+)LIN28(+)DPPA4(+) cells. We then explored the expression of a set of markers, including PIWIL1/MARWI, VASA, DAZL, CLGN, RanBPM, SYCP1 and HAPRIN, during germ cell differentiation from early spermatocytes through round and elongating spermatids, and a clear program of gene expression changes was determined as development proceeded. We then examined the juvenile marmoset testis. Markers of gonocytes demonstrated two populations; one that migrates to the basal membrane where they form the SALL4(+) or C-KIT(+) spermatogonia, and another that remains in the lumen of the seminiferous tubule. This later population, historically identified as pre-spermatogonia, expressed meiotic and apoptotic markers and were eliminated because they appear to have failed to correctly migrate. Our findings provide the first platform of gene expression dynamics in adult and developing germ cells of the common marmoset. Although we have characterized a limited number of genes, these results will facilitate primate spermatogenesis research and understanding of human reproduction.

Spermatogonial stem cells and spermatogenesis in mice, monkeys and men

“…Some A pale have a transition phenotype similar to larger chain A al spermatogonia in rodents (e.g., GFRa1+/SOHLH1+/NGN3+/cKIT+) (Hermann et al, 2009; Ramaswamy et al, 2014). Markers of undifferentiated spermatogonia that are conserved from rodents to nonhuman primates to humans include GFRa1, UTF1, PLZF, SALL4 and LIN28 (van Bragt et al, 2008; Meng et al, 2000; Costoya et al, 2004; Buaas et al, 2004; Hobbs et al, 2012; Eildermann et al, 2012a; Gassei & Orwig, 2013; Zheng et al, 2009; Hermann et al, 2009; Ramaswamy et al, 2014; Aeckerle et al, 2012; Lin et al, 2015; Di Persio et al, 2017; Valli et al, 2014; Zheng et al, 2014; Sachs et al, 2014) (See UTF1 staining of monkey and human testis cross sections in Fig. 4C and D).…”

Cell signalling pathway regulation by RanBPM: molecular insights and disease implications

“…[116] further noted that both male and female RanBPM KO mice were sterile, and closer examination showed that RanBPM is essential for spermatogenesis and oogenesis. Both genders were found to have a meiotic defect occurring around the late pachytene/diplotene stages, therefore suggesting the presence of a common mechanism requiring RanBPM function occurring in both genders at the end of prophase I. RanBPM was also shown to play a role in spermatogenesis in the new world common marmoset [118]. RanBPM was previously suggested to function in spermatogenesis, as it is able to associate with mouse vasa homologue (MVH), a vasa protein, which plays an essential role in the development of the male germ cell [20,55,116].…”

Male germline stem cells in non-human primates

“…Assuming that A dark and A pale spermatogonia can be distinguished based on their mitotic activity Simorangkir et al, 2009), a co-localization study was performed evaluating the expression of spermatogonial markers with the proliferation marker Ki67 (Lin et al, 2015). Two populations of spermatogonia were identified in adult marmoset monkeys with the molecular phenotype of SALL4+/PLZF+/LIN28+/DPPA4+ (developmental pluripotency-associated 4)/DAZL+ (deleted in azoospermia-like) and DAZL+/c-kit+/KI67+ (Lin et al, 2015).…”

“…Two populations of spermatogonia were identified in adult marmoset monkeys with the molecular phenotype of SALL4+/PLZF+/LIN28+/DPPA4+ (developmental pluripotency-associated 4)/DAZL+ (deleted in azoospermia-like) and DAZL+/c-kit+/KI67+ (Lin et al, 2015). While the former population may represent A dark spermatogonia, the latter population may comprise the A pale population.…”

“…While the former population may represent A dark spermatogonia, the latter population may comprise the A pale population. However, Lin et al (2015) questioned the possibility to differentiate these two populations based on this one criterion.…”