Investigating the relationship between embryonic glucose homeostasis and neural tube closure

PROJECT SUMMARY Neural tube defects (NTDs) occur in ~1-2 in 1000 pregnancies globally every year and constitute one of the top three most common congenital developmental differences in the world. An embryo with an NTD develops with an area of partially enclosed or completely exposed central nervous tissue, which can lead to complications both during pregnancy and after birth. Some NTDs are so severe they lead to lethality, and even milder forms of NTDs lead to a decreased quality of life. NTDs can have many negative consequences for the people they affect, and improving identification of pregnancies that are at risk for an NTD would benefit many people around the world. One known NTD risk factor is maternal diabetes, which exposes the embryo to elevated levels of glucose. The relevance of glucose to NTDs is one of the factors that makes Insulin Receptor Substrate 1 (IRS-1) an attractive candidate for investigation as a potential player in NTD risk. In addition to the role of IRS-1 in mediating glucose uptake, glucose utilization, and cell growth, multiple patients with NTDs have mutations in IRS1 (collaboration with the Gleeson Lab, UCSD). These pieces of evidence focus my proposed project on IRS-1 and its intersections with maternal diabetes and embryonic glucose response. Much work has been done on glucose from the maternal perspective, but little is known about glucose homeostasis or the role of IRS-1 in the embryo. This study aims to use IRS-1 to clarify the relationship between NTD risk and the embryonic response to environmental glucose. By understanding how perturbing IRS-1 levels can dysregulate glucose homeostasis and lead to NTDs, we can improve identification of pregnancies at risk for NTDs. To achieve these goals, the proposed study has two aims. Specific Aim 1 will investigate the role of IRS-1 in cellular glucose consumption dynamics using mouse neural progenitor cell lines and primary cells with a genetic knock-out of the Irs1 gene. Specific Aim 2 will examine IRS-1 loss using an established Irs1 knockout mouse line. Embryos from this model will be cultured and live-imaged ex utero to dynamically assess the effects of IRS-1 loss on the morphology of the neural tube as it closes. To understand potential interactions between maternal diabetes and Irs1 loss, female mice from this line will also be treated with streptozotocin to induce diabetes, and NTD incidence in their offspring will be measured. All experiments will be conducted in the Niswander lab, which is part of the Molecular, Cellular, and Developmental Biology Department at the University of Colorado Boulder. Both the lab and department provide excellent resources including a supportive environment, quality equipment, and a wealth of knowledge from experienced scientists. These resources will support my journey towards my career goal of becoming an independent research scientist in academia, as well as my intermediary training goals of accumulating technical skills in developmental biology, improving my science communication skills, and mentoring future scientists.