Investigating nuclear plasticity in the human placental syncytium - ABSTRACT During human pregnancy the interface between the maternal and fetal vasculature is a tissue-sized multinucleate cell termed the syncytiotrophoblast (STB). The STB is essential for transport, fetal immunoprotection, metabolic functions, and is the primary producer of placenta hormones. Surrounded by maternal blood, the STB must maintain these diverse functions while responding to extracellular stresses like hypoxia, oxidative stress, and inflammation to maintain a healthy pregnancy. In fact, systemic STB stress is a key driver of maternal pathology in preeclampsia, a leading cause of maternal and fetal mortality that affects 5-10% of pregnancies. The objective of my long-term research program is to dissect how a single giant cell supports these diverse functions while simultaneously reacting to stress. In fact, my research has revealed that individual nuclei in the STB express different sets of genes and therefore adopt distinct nuclear subtype identities. These nuclear subtypes shift in proportion throughout gestation and in response to environmental cues, suggesting the STB can adapt its distribution of nuclear subtypes to the fluctuating maternal environment. How are unique nuclear subtypes created and modified in a shared cytoplasm? Ultrastructure analyses of nuclei in the STB reveal diverse sizes, shapes, and degrees of chromatin compaction, suggesting the transcriptional diversity among STB subtypes could arise from distinct epigenetic landscapes. Further, I have identified candidate chromatin remodelers and transcription factors whose expression is specific to individual STB subtypes and could regulate their unique transcriptional identities. Therefore, I hypothesize that epigenetic regulation facilitates the formation of distinct nuclear subtypes and drives STB adaptation to stress. My research goals to test these hypotheses are 1- determine the mechanism of nuclear subtype adaptation during stress and 2- map the unique epigenetic regulation of each STB nuclear subtype. I will complete this training in Dr. Amy Gladfelter’s lab, a supportive and inspiring mentor who has ensured I have all resources necessary to achieve the proposed Aims. However, to obtain my research goals I require additional experimental and intellectual training in lineage tracing and epigenomic profiling. This will be accomplished with a world-class advisory committee at Duke University. To test how STB nuclear subtypes adapt to stress, I will work with work with Dr. Purushothama Rao Tata to master cutting-edge CRISPR lineage tracing experiments. To map the epigenetic regulation of STB nuclear subtypes, I will work with leaders in cutting-edge chromatin techniques including Dr. Anoop Patel, Dr. David MacAlpine, and Dr. Greg Wang. This training will lay the groundwork for my independent research program that dissects the epigenetic mechanisms by which a giant STB cell can support diverse cell functions while adapting to stress. Ultimately, I aim to use these molecular studies to identify therapeutic targets that mitigate STB stress during pregnancy disease. This K99/R00 award will enable me build collaborations with experts in plasticity and epigenomics and master these new fields with focused training, seminars, workshops, and conferences.
