The Cupp laboratory utilizes animal models to understand mechanisms involved in female and male fertility. Our goal is to better understand infertility disorders and maintain longer reproductive lifespans in several different projects.
Female Infertility due to Androgen Excess
1) We have identified a population of females in the herd (15%) to have irregular reproductive cycles, anovulation, naturally occurring excess androgen in follicular fluid of dominant follicles (High A4 cows), and a 17% reduction in calving rate compared to controls. Many aspects of their phenotype is similar to women with Polycystic Ovary Syndrome (PCOS). In addition to reproductive problems, our High A4 cows also appear to have alterations in metabolites in blood plasma. While High A4 cows respond to FSH by developing similar numbers and diameter of follicles, they have 50% reduction in number of granulosa cells/follicle and granulosa cell gene expression indicates that excess androgen causes prematurely luteinization or loss of granulosa cell identity. Furthermore, ovarian cortex from these High A4 cows secretes excess A4 with increased production of other steroid hormones and metabolites. There is also increased oxidative stress and fibrosis in the ovarian cortex suggesting increased inflammation which can be resolved by in vivo FSH or in vitro treatment with angiogenic VEGFA165. (Collaborators- John Davis and DJ Murry UNMC, Jennifer Wood)
2) Heifer pubertal classifications may identify female reproductive longevityFemale Infertility due to Androgen Excess
Since earlier age at puberty indicates longer reproductive lifespan, we wanted to determine genetic and environmental factors that may affect puberty. We started determining how heifers in our herd attained puberty and identified 4 different pubertal groups: Typical, Early, Start-Stop and Non-Cycling. We have genotyped the whole herd and conducted whole genome sequencing on 35 individuals, determined heritability related to pubertal classifications and conducted GWAS. We have several Small Nucleotide Polymorphisms (SNP’s) that may describe some genetic variation and pubertal classification that we are investigating. Ultimately, we would like to use our beef population to develop high-throughput methods to identify heifers that genetically may develop delayed or precocious puberty and select against them or determine ways to increase their reproductive efficiency to aid beef producers in profitability of their cow/calf operations. (Collaborators- Jessica Petersen, Melanie Hess, Matt Spangler and Jennifer Wood UNL and John Davis UNMC, Bob Cushman USMARC).
3) Vascular Endothelial Growth Factor (VEGFA) isoforms in Gonadal Morphogenesis and Function
Increasing numbers of couples have infertility problems. In the last 15-20 years, there has been an increase in the number of boys with ambiguous genitalia, and testicular cancer with 40% of the men in industrialized countries having subnormal sperm counts. In addition, infertility problems in women are on the rise with major problems associated with anovulation or ovulation at appropriate times during the reproductive cycle. Many scientists have associated adult reproductive infertility with abnormal differentiation of cells within the ovary and testis during development. Thus, one major focus of my laboratory is to determine the basic science behind what genes or cells may be alternatively regulated to result in male or female infertility. We are presently determining the role of Vascular Endothelial Growth Factor A (VEGFA) isoforms (pro-angiogenic and anti-angiogenic) and their receptors (KDR and FLT1) and co-receptor (NRP1) in the testis and ovarian development through the use of gonadal organ cultures, recombination experiments, overexpression assays, transgenic and conditional knockout mice (using cell-specific gene knockouts) or overexpressing mice lines. We have developed over 8 different lines of mice to knockout a member of the VEGFA family or overexpress it. These unique mouse models have allowed us to determine that the VEGFA family has novel roles in the maintenance of the spermatogonial stem cell niche in males. In females the VEGFA family also is critical in stimulating follicle progression, proliferation and survival of somatic cells which is necessary for fertility, reproductive lifespan, and bone density.
4) Differentiation of Granulosa and Theca Cells to form luteal cells and a Corpus Luteum (CL)
We have determined gene expression profiles for theca and granulosa cells during the process of differentiation to luteinization which also includes lipid production and immune function. We have been determining how these cells differente, how they interact with the immune system, and how lipids are produced and involved in this process. We also have evaluated how the CL regresses and what signal transduction pathways are involved. (Collaborators- John Davis and Jennifer Wood)