Ovarian Folliculogenesis

Child Health And Human Development

Investigators

Linked publications & trials

Abstract

This project seeks to improve the clinical care available to patients with disorders of ovarian follicle function and ovulation through research using animal models as well as clinical protocols. In pursuing this goal, we expect to expand basic science understanding of the ovarian follicle in health and disease. We have focused on premature ovarian failure, a condition that prematurely terminates ovarian function and fertility in 1% of women. We have particular interest in autoimmunity as a cause of ovarian failure. In a mouse model, we found that autoantibodies from mice with experimental autoimmune oophoritis bind to MATER, a novel 120 kd protein that is specific to the oocyte cytoplasm. Mater is a novel oocyte-specific maternal effect gene whose product is essential for embryonic development beyond the two-cell stage. MATER provides a new determinant with which to investigate the mechanisms of autoimmune premature ovarian failure as well as mechanisms of early embryonic developmental failure. During the past year we have moved forward to sequence human MATER and are working to develop an assay that will detect anti-MATER antibodies in women. Genetic mapping indicated that Mater is located in the proximal end of mouse chromosome 7, a syntenic region of human Chromosome 19q13. To isolate the human homolog of mouse Mater, we blasted the human genome database using mouse MATER cDNA and protein sequences. We designed oligonucleotides as primers to amplify cDNAs from a human ovarian cDNA library. The primers were based on sequences found on human Chromosome 19 that were homologous with mouse MATER cDNA. As in the mouse, oocyte-specific expression of human MATER transcripts was detected in human oocytes by in situ hybridization. The human oocytes also contained the MATER protein as demonstrated by immunohistochemistry and immunoblotting. Over all, human MATER cDNA shares ~ 67% identity with the mouse MATER cDNA while their deduced proteins have 54% identity of amino acids. In the clinic, we have found that premature ovarian failure is more complex than merely a premature menopause. One half of these young women have ovarian follicles remaining that function intermittently. We are investigating the mechanisms of this ovarian follicle dysfunction. In some cases the dysfunction is caused by autoimmune oophoritis; in other cases it is due to low follicle number. We are also investigating other adverse health consequences of premature ovarian failure. We found that these young women have deficient circulating free testosterone levels, and, surprisingly, two thirds of our patients have a reduced bone density that may place them at increased risk of hip fracture. We have clinical studies underway to develop hormone replacement methods appropriate specifically to these young women, and we are working to develop a clinically useful test that will detect ovarian insufficiency earlier in its course. Approximately 3% of women with premature ovarian failure will also develop autoimmune adrenal insufficiency, and we are working to develop an efficient screening method to detect this earlier in its course. We also have preliminary evidence to suggest that young women with premature ovarian failure have an increased incidence of dry eye syndrome, and we are conducting a controlled study to test this hypothesis. Premature ovarian failure is clearly a more complex condition than has been previously recognized.