The interaction between follicle-stimulating hormone (FSH) and the FSH receptor (FSHR) is essential for normal oogenesis and spermatogenesis. Recently, single-nucleotide polymorphisms (SNPs) have been assigned to the gene. These give rise to different haplotypes that modify the action of FSH. In women, FSH sensitivities during the menstrual cycle and different cycle lengths are observed, depending on the haplotype. Thus, SNPs of the determine the ovarian response and should, therefore, be considered in controlled ovarian hyperstimulation during assisted-reproduction techniques in women with normal ovarian function. In men, the impact of the SNPs is unclear. The genetic complexity of should be considered when studying FSH action. These SNPs are one of the first examples in which genetic changes contribute to fine-tuning the endocrine regulation of reproduction. A rational pharmacogenetic approach that combines FSH dose according to the haplotype is envisaged.
Abstract STUDY QUESTION Does the sperm DNA fragmentation index (DFI) improve depending on the FSH receptor (FSHR) genotype as assessed by the nonsynonymous polymorphisms rs6166 (p.N680S) after 3 months of recombinant FSH treatment in men with idiopathic infertility? SUMMARY ANSWER FSH treatment significantly improves sperm DFI only in idiopathic infertile men with the p.N680S homozygous N FSHR. WHAT IS KNOWN ALREADY FSH, fundamental for spermatogenesis, is empirically used to treat male idiopathic infertility and several studies suggest that DFI could be a candidate predictor of response to FSH treatment, in terms of probability to conceive. Furthermore, it is known that the FSHR single nucleotide polymorphism (SNP) rs6166 (p.N680S) influences ovarian response in women and testicular volume in men. STUDY DESIGN, SIZE AND DURATION A multicenter, longitudinal, prospective, open-label, two-arm clinical trial was performed. Subjects enrolled were idiopathic infertile men who received 150 IU recombinant human FSH s.c. every other day for 12 weeks and were followed-up for a further 12 weeks after FSH withdrawal. Patients were evaluated at baseline, at the end of treatment and at the end of follow-up. PARTICIPANTS/MATERIALS, SETTING, METHODS Eighty-nine men with idiopathic infertility carrier of the FSHR p.N680S homozygous N or S genotype, FSH ≤ 8 IU/l and DFI >15%, were enrolled. A total of 66 patients had DFI analysis completed on at least two visits. DFI was evaluated in one laboratory by TUNEL/PI (propidium iodide) assay coupled to flow cytometry, resolving two different fractions of sperm, namely the ‘brighter’ and ‘dimmer’ sperm DFI fractions. MAIN RESULTS AND THE ROLE OF CHANCE Thirty-eight men (57.6%) were carriers of the p.N680S homozygous N and 28 (42.4%) of the homozygous S FSHR. Sperm concentration/number was highly heterogeneous and both groups included men ranging from severe oligozoospermia to normozoospermia. Total DFI was significantly lower at the end of the study in homozygous carriers of the p.N680S N versus p.N680S S allele (P = 0.008). Total DFI decreased significantly from baseline to the end of the study (P = 0.021) only in carriers of the p.N680S homozygous N polymorphism, and this decrease involved the sperm population containing vital sperm (i.e. brighter sperm) (P = 0.008). The dimmer sperm DFI fraction, including only nonvital sperm, was significantly larger in p.N680S S homozygous patients than in homozygous N men (P = 0.018). Total DFI was inversely related to total sperm number (P = 0.020) and progressive sperm motility (P = 0.014). When patients were further stratified according to sperm concentration (normoozospermic versus oligozoospermic) or -211G>T polymorphism in the FSHB gene (rs10835638) (homozygous G versus others), the significant improvement of sperm DFI in FSHR p.N680S homozygous N men was independent of sperm concentration and associated with the homozygous FSHB -211G>T homozygous G genotype. LIMITATIONS, REASONS FOR CAUTION The statistical power of the study is 86.9% with alpha error 0.05. This is the first pharmacogenetic study suggesting that FSH treatment induces a significant improvement of total DFI in men carriers of the p.N680S homozygous N FSHR; however, the results need to be confirmed in larger studies using a personalized FSH dosage and treatment duration. WIDER IMPLICATIONS OF THE FINDINGS The evaluation of sperm DFI as a surrogate marker of sperm quality, and of the FSHR SNP rs6166 (p.N680S), might be useful to predict the response to FSH treatment in men with idiopathic infertility. STUDY FUNDING/COMPETING INTEREST(S) The study was supported by an unrestricted grant to M.S. and H.M.B. from Merck Serono that provided the drug used in the study. MS received additional grants from Merck Serono and IBSA as well as honoraria from Merck Serono. The remaining authors declare that no conflicts of interest are present. TRIAL REGISTRATION NUMBER EudraCT number 2010-020240-35.
The synergistic actions of Testosterone (T) and FSH via testicular Sertoli cells (Sc) regulate male fertility. We have previously reported that the actions of these hormones (T and FSH) in infant monkey testes are restricted only to the expansion of Sc and spermatogonial cells. The robust differentiation of male Germ cells (Gc) occurs after pubertal maturation of testis. The present study was aimed to investigate the molecular basis of the synergy between T and FSH action in pubertal primate ( ) Sc. Using primary Sc culture, we here have demonstrated that T (but not FSH) downregulated and ( ) mRNAs in pubertal Sc. We also found that, prolonged stimulation of T in pubertal Sc significantly elevated the expression of genes involved in FSH signaling pathway like , and , and this was associated with a rise in cAMP production. T also augmented FSH induced expression of genes like and ( ) in pubertal Sc. We therefore conclude that T acts in synergy with FSH signaling in pubertal Sc. Such a coordinated network of hormonal signaling in Sc may facilitate the timely onset of the first spermatogenic wave in pubertal primates and is responsible for quantitatively and qualitatively normal spermatogenesis.
Cells of the monocyte series respond to follicle stimulating hormone (FSH) by poorly characterized mechanisms. We studied FSH-receptors (FSH-R) and FSH response in nontransformed human monocytes and in osteoclasts differentiated from these cells. Western blot and PCR confirmed FSH-R expression on monocytes or osteoclasts, although at low levels relative to ovarian controls. Monocyte and osteoclast FSH-Rs differed from FSH-R from ovarian cells, reflecting variable splicing in exons 8–10. Monocytes produced no cAMP, the major signal in ovarian cells, in response to FSH. However, monocytes and osteoclasts transcribed TNFα in response to the FSH. No relation of expression of osteoclast FSH-R to the sex of cell donors or to exposure to sex hormones was apparent. Controls for FSH purity and endotoxin contamination were negative. Unamplified cRNA screening in adherent CD14 cells after 2 h in 25 ng/ml FSH showed increased transcription of RANKL signalling proteins. Transcription of key proteins that stimulate bone turnover, TNFα and TSG-6, increased 2- to 3-fold after FSH treatment. Smaller but significant changes occurred in transcripts of selected signalling, adhesion, and cytoskeletal proteins. We conclude that monocyte and osteoclast FSH response diverges from that of ovarian cells, reflecting, at least in part, varying FSH-R isoforms.
FSH brings about its physiological actions by activating a specific receptor located on target cells. Normal functioning of the FSH receptor (FSHR) is crucial for follicular development and estradiol production in females and for the regulation of Sertoli cell function and spermatogenesis in males. In the last two decades, the number of inactivating and activating mutations, single nucleotide polymorphisms, and spliced variants of FSHR gene has been identified in selected infertile cases. Information on genotype-phenotype correlation and in vitro functional characterization of the mutants has helped in understanding the possible genetic cause for female infertility in affected individuals. The information is also being used to dissect various extracellular and intracellular events involved in hormone-receptor interaction by studying the differences in the properties of the mutant receptor when compared with WT receptor. Studies on polymorphisms in the FSHR gene have shown variability in clinical outcome among women treated with FSH. These observations are being explored to develop molecular markers to predict the optimum dose of FSH required for controlled ovarian hyperstimulation. Pharmacogenetics is an emerging field in this area that aims at designing individual treatment protocols for reproductive abnormalities based on FSHR gene polymorphisms. The present review discusses the current knowledge of various genetic alterations in FSHR and their impact on receptor function in the female reproductive system.