Richard Finnell Lab

Genetically modified mice represent outstanding tools for developing and directly testing hypotheses about environmental factors that cause birth defects. Our laboratory makes use of a variety of such mice to understand the mechanism by which nutrients such as folic acid prevents common birth defects, including neural tube (Spina bifida) and heart defects (conotruncal defects). We have applied both conventional and conditional knockout mouse models of genes specifically involved in folate metabolism and transport (e.g., Folr1, Folr2, Folr4, Rfc1, Slc25a32, Mthfr and Pcft) to these birth defect studies. We have also created novel mouse NTD models by knocking in gene variants identified in our human NTD cohorts, such as the MED12 mouse.  

These mouse tools are an invaluable resource as we try to learn how nutritional factors prevent certain birth defects and promote the development of healthy babies. In a knockout mouse, we eliminate one gene-usually a gene that brings a vitamin into a cell-and then determine its impact on embryogenesis. For example, when we inactivate (knock out) the folate receptor (Forl1) gene-its protein product which is a receptor molecule that brings vitamin B9 (folic acid) into cells is eliminated, and the newborn pups present with neural, cardiac and craniofacial defects. We can then investigate cellular events that are occurring in order to elucidate other potential interventions for non-folate responsive birth defects in our ongoing efforts to prevent preventable birth defects. We have come to appreciate that in human spina bifida patients there are often single copies of more than one gene that has been mutated. Therefore, we have begun to utilize a haploid androgenic stem cell line obtained from the Chinese Academy of Science to rapidly create novel mice with 3-4 human gene variants associated with NTDs.

These unique models help us better understand the complex genetic architecture underlying NTDs.  We make these mice and related reagents available to researchers around the world so that they can apply their particular skills to learn more about the causes of environmentally-related birth defects. Interestingly, while not all cells have folate receptors, essentially all cancer cells do. So many new drugs to fight cancer are being developed in such a way that a cytotoxic molecule is linked to folic acid. When they are administered to the person (or animal), the folic acid is bound by the folate receptor, which is on the cancer cells more often than on healthy cells, and so the toxic drugs are more effectively targeted directly to the cancer cells. This is especially true for ovarian cancer, so we are working with collaborators to help them develop such highly efficacious drugs and our mice which lack these folate receptors are the perfect tool for them to test the effectiveness of candidate compounds.

The ultimate goals short of total prevention of all birth defects would be to develop effective treatments for those children born with structural malformations. We have set forth on a program of highly translational research using mice and sheep models of spina bifida to utilize information gained from genomic studies to activate select developmental pathways using stem cells or neurotrophic or growth factors to treat neurogenic bladder and bowel issues secondary to spina bifida.

We have been using what we have learned from our model organism studies to develop new prenatal diagnostic tests to identify and help manage high risk pregnancies. We discovered that there were high titers of antibodies to the folate receptor alpha protein among mothers who were pregnant with spina bifida affected infants. These blocking antibodies were thought to restrict folate transport to the placenta and developing embryo at critical periods during neural tube closure, increasing the risk for spina bifida and perhaps other birth defects. We have expanded this to see if autoantibodies to folate receptor alpha is a good prenatal test for other neurodevelopmental anomalies and adverse reproductive outcomes including: autism, cerebral folate deficiency syndrome, congenital heart defects, preeclampsia and low birth weight infants.

We are involved in all of the largest genomic studies of neural tube defects in order to better define the genetic architecture of these complex birth defects in an effort to identify novel pathways that might be better suited for intervention strategies than those that are currently known and appreciated. We have long established global collaborations with investigators on every continent in our efforts to prevent, preventable birth defects.