Effects of follicle-stimulating hormone on intermediate filaments and cell division of Sertoli cells of fetal rat testis in culture

Common markers of testicular Sertoli cells

INTRODUCTION

Sertoli cells play central roles in the development of testis formation in fetuses and the initiation and maintenance of spermatogenesis in puberty and adulthood, and disorders of Sertoli cell proliferation and/or functional maturation can cause male reproductive disorders at various life stages. It's well documented that various genes are either overexpressed or absent in Sertoli cells during the conversion of an immature, proliferating Sertoli cell to a mature, non-proliferating Sertoli cell, which are considered as Sertoli cell stage-specific markers. Thus, it is paramount to choose an appropriate Sertoli cell marker that will be used not only to identify the developmental, proliferative, and maturation of Sertoli cell status in the testis during the fetal period, prepuberty, puberty, or in the adult, but also to diagnose the mechanisms underlying spermatogenic dysfunction.

AREAS COVERED

In this review, we principally enumerated 5 categories of testicular Sertoli cell markers - including immature Sertoli cell markers, mature Sertoli cell markers, immature/mature Sertoli cell markers, Sertoli cell functional markers, and others.

EXPERT OPINION

By delineating the characteristics and applications of more than 20 Sertoli cell markers, this review provided novel Sertoli cell markers for the more accurate diagnosis and mechanistic evaluation of male reproductive disorders.

Effects of secretome on cisplatin-induced testicular dysfunction in rats

Background

Testicular dysfunction is a degenerative disorder characterized by failure in the synthesis of reproductive hormones and spermatogenesis. Secretome derived from the human umbilical mesenchymal stem cell (MSC) has been reported to repair some degenerative disorders.

Aim

This study aimed to investigate the effect of secretome derived from the human umbilical MSCs on cisplatin-induced testicular dysfunction in rats.

Materials and Methods

Thirty-six male Wistar rats were divided into the control and secretome-treated groups. In the secretome-treated group, testicular dysfunction was induced by 3 mg/kg BW of cisplatin intraperitoneally 3 times with 3-day intervals. The secretome-treated group was divided according to dose: Low-dose (0.2 mL/kg BW) and high-dose (0.5 mL/kg BW) groups. Secretomes were injected intraperitoneally once a week for 3 weeks. 1 week after the injection of secretome, the cauda epididymis of the rats was removed for spermatozoa evaluation and histological examination.

Result

After the injection of secretome, the sperm motility of the high-dose group showed thin wave-like, rare, and slow movements. No abnormal sperm morphology was observed in all the treated groups. The number of spermatozoa increased gradually in the high-dose group after the injection of secretome. The developmental stages of the spermatogenic cells were complete in both spermatozoa groups after the injection of secretome. However, the spermatozoa in the seminiferous tubules of the high-dose group were denser. Vimentin and cytokeratin immunoreactivities were very strong in the high-dose group 1 week after the second secretome injection.

Conclusion

High-dose secretome derived from the human fetal umbilical cord could increase the number and motility of sperms in rats with cisplatin-induced testicular dysfunction. The administration of high-dose secretome was effective 1 week after the second dose, as indicated by very strong immunoreactivity for vimentin and cytokeratin. Moreover, secretome could promote the regeneration of the seminiferous tubules of both the groups.

Involvement of calcium-dependent mechanisms in T3-induced phosphorylation of vimentin of immature rat testis

Thyroid hormones have been shown to act at extra nuclear sites, inducing target cell responses by several mechanisms, frequently involving intracellular calcium concentration. It has also been reported that cytoskeletal proteins are a target for thyroid and steroid hormones and cytoskeletal rearrangements are observed during hormone-induced differentiation and development of rat testes. However, little is known about the effect of 3,5,3'-triiodo-L-thyronine (T3) on the intermediate filament (IF) vimentin in rat testes. In this study we investigated the immunocontent and in vitro phosphorylation of vimentin in the cytoskeletal fraction of immature rat testes after a short-term in vitro treatment with T3. Gonads were incubated with or without T3 and 32P orthophosphate for 30 min and the intermediate filament-enriched cytoskeletal fraction was extracted in a high salt Triton-containing buffer. Vimentin immunoreactivity was analyzed by immunoblotting and the in vitro 32P incorporation into this protein was measured. Results showed that 1 microM T3 was able to increase the vimentin immunoreactivity and in vitro phosphorylation in the cytoskeletal fraction without altering total vimentin immunocontent in immature rat testes. Besides, these effects were independent of active protein synthesis. The involvement of Ca2+-mediated mechanisms in vimentin phosphorylation was evident when specific channel blockers (verapamil and nifedipine) or chelating agents (EGTA and BAPTA) were added during pre-incubation and incubation of the testes with T3. The effect of T3 was prevented when Ca2+ influx was blocked or intracellular Ca2+ was chelated. These results demonstrate a rapid nongenomic Ca2+-dependent action of T3 in phosphorylating vimentin in immature rat testes.

Subcellular and molecular mechanisms regulating anti-Müllerian hormone gene expression in mammalian and nonmammalian species

Anti-Müllerian hormone (AMH) is best known for its role as an inhibitor of the development of female internal genitalia primordia during fetal life. In the testis, AMH is highly expressed by Sertoli cells of the testis from early fetal life to puberty, when it is downregulated by the action of testosterone, acting through the androgen receptor, and meiotic spermatocytes, probably acting through TNFalpha. Basal expression of AMH is induced by SOX9; GATA4, SF1, and WT1 enhance SOX9-activated expression. When the hypothalamic-pituitary axis is active and the negative effect of androgens and germ cells is absent, for example, in the fetal and neonatal periods or in disorders like androgen insensitivity, FSH upregulates AMH expression through a nonclassical cAMP-PKA pathway involving transcription factors AP2 and NFkappaB. The maintenance and hormonal regulation of AMH expression in late fetal and postnatal life requires distal AMH promoter sequences. In the ovary, granulosa cells express AMH from late fetal life at low levels; DAX1 and FOG2 seem to be responsible for negatively modulating AMH expression. Particular features are observed in AMH expression in nonmammalian species. In birds, AMH is expressed both in the male and female fetal gonads, and, like in reptiles, its expression is not preceded by that of SOX9.