Assessing the role of lymphatic endothelial cell niche in intestinal regeneration

项目总结

PROJECT SUMMARY Endothelial cells that line blood and lymphatic vessels are abundant in the small intestine niche. Interestingly, in the last decade, several groups have shown that endothelial cells have a role beyond “plumbing” and secrete paracrine factors supporting the stem cell maintenance and regeneration of various tissues. Although ISCs renew rapidly and continuously to sustain metabolic health, the role of lymphatic endothelial cells (LECs) in the ISC niche is not well-established. Notably, LECs are known to express high levels of Rspo3, one of the WNT signaling molecules required in the niche for ISC self-renewal. In my work, I have further made the observation that the WNT modulator Wls is also highly expressed by LECs in the small intestine. In addition to putative roles in homeostatic turnover, several lines of evidence suggest that endothelial cells become activated in response to intestinal injury to drive epithelial recovery. Despite this knowledge, whether LEC derived WNT signaling in the intestinal niche is essential for ISC regeneration after cytotoxic injury remains unknown. Based on this premise, I aim to study the role of LECs in a model of chemotherapy-induced intestinal injury, a frequent and devastating inflammatory condition that affects cancer patients. The overarching goal of my project is to understand how endothelial cells contribute to ISC regeneration and I propose that, in part, this is achieved through secretion of the WNT modulators RSPO3 and WLS by LECs. For this reason, I have generated crosses to obtain mouse models in which either Rspo3 or Wls are selectively knocked out from LECs in adult mice. My preliminary data indicate that in mice where Rspo3 has been deleted from LECs in adult mice, there is a delayed recovery of ISCs after 5FU injury. I plan to further corroborate these results in mice where Wls is deleted from LECs. Additionally, I will generate single cell RNA sequencing data to determine transcriptional changes in crypt epithelial cells after 5FU injury in mice where Rspo3 has been knocked out from LECs. Lastly, I will dissect changes in LECs as they relate to epithelial repair after 5FU injury. Together, the proposed studies will define how signals from the lymphatic niche contribute to ISC regeneration and more broadly will identify a potential novel intestinal niche component that can be therapeutically targeted to stimulate intestinal repair.