Abstract
BackgroundSertoli cells are the most important somatic cells contributing to the microenvironment (named niche) for spermatogonial stem cells (SSCs). They produce amounts of crucial growth factors and structure proteins that play essential roles in the complex processes of male SSCs survival, proliferation, and differentiation. It has been suggested that Sertoli cell abnormalities could result in spermatogenesis failure, eventually causing azoospermia in humans. However, to the end, the gene expression characteristics and protein functions of human Sertoli cells remained unknown. In this study, we aimed to evaluate the effect of fibroblast growth factor-5 (FGF5), a novel growth factor downregulated in Sertoli cells from Sertoli cell-only syndrome (SCOS) patients compared to Sertoli cells from obstructive azoospermia (OA) patients, on SSCs.MethodsWe compared the transcriptome between Sertoli cell from SCOS and OA patients. Then, we evaluated the expression of FGF5, a growth factor which is downregulated in SCOS Sertoli cells, in human primary cultured Sertoli cells and testicular tissue. Also, the proliferation effect of FGF5 in mice SSCs was detected using EDU assay and CCK-8 assay. To investigate the mechanism of FGF5, Phospho Explorer Array was performed. And the results were verified using Western blot assay.ResultsUsing RNA-Seq, we found 308 differentially expressed genes (DEGs) between Sertoli cells from SCOS and OA patients. We noted and verified that the expression of fibroblast growth factor-5 (FGF5) was higher in Sertoli cells of OA patients than that of SCOS patients at both transcriptional and translational levels. Proliferation assays showed that rFGF5 enhanced the proliferation of mouse SSCs line C18-4 in a time- and dose-dependent manner. Moreover, we demonstrated that ERK and AKT were activated and the expression of Cyclin A2 and Cyclin E1 was enhanced by rFGF5.ConclusionThe distinct RNA profiles between Sertoli cells from SCOS and OA patients were identified using RNA-Seq. Also, FGF5, a growth factor that downregulated in SCOS Sertoli cells, could promote SSCs proliferation via ERK and AKT activation.
Highlights
Male infertility is a common reproductive disorder which contributes to about 10–15% of infertile couples in the world [1, 2]
We have for the first time reported that 308 genes were distinctly expressed in human Sertoli cells between Sertoli cell-only syndrome (SCOS) and obstructive azoospermia (OA) patients. In these differentially expressed genes (DEGs), we found that fibroblast growth factor-5 (FGF5) was downregulated in human Sertoli cells of SCOS patients compared to that of OA patients
Patients with non-obstructive azoospermia (NOA) were confirmed by histological analysis, and patients with reproductive congenital disease such as Klinefelter syndrome and genomic AZF deletions, or other diseases including cancer were excluded in this study
Summary
Male infertility is a common reproductive disorder which contributes to about 10–15% of infertile couples in the world [1, 2]. Sertoli cell-only syndrome (SCOS) is a type of NOA with the most severe impairment of spermatogenesis, diagnosed by the testicular biopsy displaying that seminiferous tubules are lined with only Sertoli cells, with complete depletion of male germ cells. Azoospermia is usually determined by the pathological diagnosis which is mainly dependent on the fine-needle aspiration biopsy. Sertoli cells are the most important somatic cells contributing to the microenvironment (named niche) for spermatogonial stem cells (SSCs). They produce amounts of crucial growth factors and structure proteins that play essential roles in the complex processes of male SSCs survival, proliferation, and differentiation. It has been suggested that Sertoli cell abnormalities could result in spermatogenesis failure, eventually causing azoospermia in humans. We aimed to evaluate the effect of fibroblast growth factor-5 (FGF5), a novel growth factor downregulated in Sertoli cells from Sertoli cell-only syndrome (SCOS) patients compared to Sertoli cells from obstructive azoospermia (OA) patients, on SSCs
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