Mechanisms of BMP signaling driving tissue pattern in the intestine - Project Abstract Diseases of the gastrointestinal system are complex and, as a result, poorly understood on a genetic and molecular level. Understanding how certain factors establish and maintain the homeostatic balance of proliferative stem cells and differentiated, functional villus cells in the intestine is important to uncovering why these diseases arise. Recently, the Bone Morphogenetic Protein (BMP) pathway has been implicated in driving a gradient of functional cell types for intestinal villus enterocytes, the absorptive cells in the intestine. Improper differentiation of these enterocytes can lead to metabolic dysfunction, malabsorption, and compromised barrier integrity. Additionally, stem cells in the crypts are suppressed by BMP signaling. Loss of stem cell suppression can lead to uncontrolled proliferation and cancer. Despite the demonstrated importance of BMP signaling in maintaining appropriate differentiation and suppressing unwanted proliferation, the specific molecular mechanisms by which this tissue patterning occurs are not understood. Mothers against decapentaplegic homolog (SMAD) family proteins are transcription factors involved in the canonical transduction of signaling cascades for the BMP pathway to regulate and promote development of most tissues in the body. SMAD1 and SMAD5, the BMP pathway-specific receptor-regulated SMADs (R-SMADs), have not yet been extensively studied in the mammalian intestine with regards to transcriptional mechanisms or genetic requirements. I hypothesize that SMAD1 and SMAD5 control key aspects of intestinal cell functionality and stem cell suppression downstream of BMP signaling. I will evaluate intestinal function after epithelium-specific knockout of Smad1 and Smad5. Specifically, I will determine the role of SMAD1 and SMAD5 in metabolism and tissue patterning of the intestine by performing RNA-seq, histology, and organoid assays on murine intestinal tissues (Aim 1). To define the targets of these transcription factors more accurately and identify interacting partners, I will perform molecular profiling of SMAD1 and SMAD5 using CUT&RUN and RIME (Aim 2). My project will clarify the roles of SMAD1 and SMAD5 in the establishment and maintenance of intestinal cell functionality and homeostasis and may reveal opportunities to target BMP pathway components in intestinal dysfunction. Importantly, this project will provide critical training opportunities in the application of mouse models, organoid technologies, epigenomic profiling techniques, and bioinformatic data analysis toward understanding and manipulating signaling pathways. As well as strengthening my research skillset through the proposal goals, I will improve my scientific presentation, writing, and collaboration skills. The proposed research project, training plan, and mentorship team will support my development into an independent research scientist poised to employ mouse models and organoid technologies toward my research career in regenerative medicine and development of cell therapies.
