Understanding intestinal intercellular communication using Light Induced Synchronized Protein Secretion

Intercellular communication between epithelial intestinal stem cells (ISCs) and their niche Paneth cells is essential for intestinal homeostasis. It deteriorates with age promoting disease onset such as inflammation and cancer. Thus, understanding age-associated alterations in stem-niche cell communication is crucial for developing interventions to optimize tissue function in later years.To communicate, Paneth cells secrete ligands instructing proliferation and differentiation of ISCs. ISCs receive these ligands via the respective receptors on their plasma membrane. While the signaling pathways of their communication are comprehensively described, the secretory membrane transport from the inside of the cell towards the cell surface of the ligands and receptors are only poorly understood.This project will identify how ISCs and their niche cells direct the secretory transport of receptor and ligand proteins for efficient intercellular communication at the cell surface and how directed secretion functions as an intestinal homeostasis regulator. First, I will establish a novel optogenetic tool in intestinal organoids enabling spatiotemporal resolved tracing of synchronized signal secretion in ISCs and niche Paneth cells using live imaging. Second, I will reroute directed secretory transport by addition of GPI-anchors, targeted signaling motif and gene removal. In combination with transcriptomics, I will study the effects of disturbed secretion on intestinal homeostasis. Third, I will unveil alterations in directed secretory transport with age and age-related dysfunctions.The proposed project will elucidate how directed secretory transport between ISCs and their neighboring niche cells determines stem cell function for tissue homeostasis. Overall, it holds the potential to uncover age-related changes in directed signal secretion, opening new avenues for treatments improving age-associated intestinal dysfunction.