Jiang Min

Bio: Jiang Min is an academic researcher from University of Turku. The author has contributed to research in topics: Male infertility & Azoospermia. The author has an hindex of 1, co-authored 1 publications receiving 501 citations.

Men Homozygous for an Inactivating Mutation of the Follicle-Stimulating Hormone (FSH) Receptor Gene Present Variable Suppression of Spermatogenesis and Fertility

Abstract: Gonadal function is controlled by the two pituitary gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH). While LH mainly regulates gonadal steroidogenesis, FSH is considered essential for folliculogenesis in the female and spermatogenesis in the male. We recently discovered that an inactivating point mutation in the FSH receptor (R) gene causes a recessively inherited form of hypergonadotropic ovarian failure in homozygous females. This 566C-->T mutation, predicting an alanine to valine substitution, is located in exon 7 of the FSHR gene, in the region encoding the extracellular domain of the receptor molecule. Functional testing showed a clear-cut reduction in ligand binding and signal transduction by the mutated receptor. Hence, lack of FSH function is incompatible with ovarian follicular maturation and female fertility. In the male, FSH is generally considered essential for the pubertal initiation of spermatogenesis and maintenance of quantitatively normal sperm production in adults. We report here the first characterization of males homozygous for an inactivating FSHR mutation. They have variable degrees of spermatogenic failure, but, surprisingly, do not show azoospermia or absolute infertility. These results question the essential role of FSH for the initiation of spermatogenesis, and demonstrate that FSH is more important for female than for male fertility.

Follicle stimulating hormone is required for ovarian follicle maturation but not male fertility.

Abstract: Follicle stimulating hormone (FSH) is a member of the glycoprotein hormone family that includes luteinzing hormone (LH), thyroid stimulating hormone, and chorionic gonadotropin. These heterodimeric hormones share a common alpha subunit and differ in their hormone-specific beta subunit. The biological activity is conferred only by the heterodimers. FSH and LH are synthesized in the same cells of the pituitary, the gonadotrophs. FSH receptors are localized to Sertoli cells of the testes and granulosa cells of the ovary. Minimal data has been accumulated so far involving human mutations in the FSH beta, LH beta, or the gonadotropin receptor genes. There are no known mouse strains with mutations in the FSH beta gene. To generate animal models for human diseases involving the gonadotropin signal transduction pathway, we produced mice deficient in the FSH beta subunit and therefore in FSH using ES cell technology. FSH-deficient females are infertile due to a block in folliculogenesis prior to antral follicle formation. Although FSH was predicted to be necessary for spermatogenesis and Sertoli cell growth in males, FSH-deficient males are fertile despite having small testes. Our findings have important implications for male contraceptive development in humans.

Advances in male contraception.

Abstract: Despite significant advances in contraceptive options for women over the last 50 yr, world population continues to grow rapidly. Scientists and activists alike point to the devastating environmental impacts that population pressures have caused, including global warming from the developed world and hunger and disease in less developed areas. Moreover, almost half of all pregnancies are still unwanted or unplanned. Clearly, there is a need for expanded, reversible, contraceptive options. Multicultural surveys demonstrate the willingness of men to participate in contraception and their female partners to trust them to do so. Notwithstanding their paucity of options, male methods including vasectomy and condoms account for almost one third of contraceptive use in the United States and other countries. Recent international clinical research efforts have demonstrated high efficacy rates (90-95%) for hormonally based male contraceptives. Current barriers to expanded use include limited delivery methods and perceived regulatory obstacles, which stymie introduction to the marketplace. However, advances in oral and injectable androgen delivery are cause for optimism that these hurdles may be overcome. Nonhormonal methods, such as compounds that target sperm motility, are attractive in their theoretical promise of specificity for the reproductive tract. Gene and protein array technologies continue to identify potential targets for this approach. Such nonhormonal agents will likely reach clinical trials in the near future. Great strides have been made in understanding male reproductive physiology; the combined efforts of scientists, clinicians, industry and governmental funding agencies could make an effective, reversible, male contraceptive an option for family planning over the next decade.

The follicle-stimulating hormone receptor: biochemistry, molecular biology, physiology, and pathophysiology.

Abstract: I. Introduction II. Biochemical Properties of the FSH Receptor: A Historical Prelude III. Molecular Structure of the FSH Receptor A. Cloning of the FSH receptor B. Predicted primary structure of the FSH receptor C. Molecular mass of the FSH receptor IV. The FSH Receptor Gene A. Chromosomal localization B. Structure and organization of the FSH receptor gene C. The promoter of the FSH receptor gene V. Expression of the FSH Receptor and Its Regulation A. FSH receptor gene expression B. Expression of the FSH receptor in the testis C. Expression of the FSH receptor in the ovary VI. Expression of the FSH Receptor in Cell Lines A. Cell lines expressing the recombinant FSH receptor B. Measurement of FSH by means of “recombinant” in vitro bioassays C. FSH receptor function in cell lines VII. Structure-Function Relationships and Models of FSH-FSH Receptor Interaction A. General features B. Structure-function relationships C. Models of FSH-FSH receptor interaction VIII. Signal Transduction and Postreceptor Events A....

Impairing follicle-stimulating hormone (FSH) signaling in vivo: Targeted disruption of the FSH receptor leads to aberrant gametogenesis and hormonal imbalance

Abstract: Pituitary gonadotropins follicle-stimulating hormone (FSH) and luteinizing hormone stimulate the gonads by regulating germ cell proliferation and differentiation. FSH receptors (FSH-Rs) are localized to testicular Sertoli cells and ovarian granulosa cells and are coupled to activation of the adenylyl cyclase and other signaling pathways. Activation of FSH-Rs is considered essential for folliculogenesis in the female and spermatogenesis in the male. We have generated mice lacking FSH-R by homologous recombination. FSH-R-deficient males are fertile but display small testes and partial spermatogenic failure. Thus, although FSH signaling is not essential for initiating spermatogenesis, it appears to be required for adequate viability and motility of the sperms. FSH-R-deficient females display thin uteri and small ovaries and are sterile because of a block in folliculogenesis before antral follicle formation. Although the expression of marker genes is only moderately altered in FSH-R −/− mice, drastic sex-specific changes are observed in the levels of various hormones. The anterior lobe of the pituitary gland in females is enlarged and reveals a larger number of FSH- and thyroid-stimulating hormone (TSH)-positive cells. The phenotype of FSH-R −/− mice is reminiscent of human hypergonadotropic ovarian dysgenesis and infertility.