Project description:Radiation therapy for abdominal tumors is challenging because the small intestine is exquisitely radiosensitive. Unfortunately, there are no FDA-approved therapies to prevent or mitigate GI radiotoxicity. The EGLN protein family are oxygen sensors that regulate cell survival and metabolism through the degradation of hypoxia-inducible factors (HIFs). Our group has previously shown that stabilization of HIF2 through genetic deletion or pharmacologic inhibition of the EGLNs mitigates and protects against GI radiotoxicity in mice by improving intestinal crypt stem cell survival. Here we aimed to elucidate the molecular mechanisms by which HIF2 confers GI radioprotection. We developed duodenal organoids from mice, transiently overexpressed non-degradable HIF2, and performed bulk RNA sequencing. Interestingly, HIF2 upregulated known radiation modulators and genes involved in GI homeostasis, including Wnt5a. Non-canonical Wnt5a signaling has been shown by other groups to improve intestinal crypt regeneration in response to injury. Here we show that HIF2 drives Wnt5a expression in multiple duodenal organoid models. Luciferase reporter assays performed in human cells showed that HIF2 directly activates the WNT5A promoter via a hypoxia response element. We then evaluated crypt regeneration using spheroid formation assays. Duodenal organoids that were pre-treated with recombinant Wnt5a had a higher cryptogenic capacity after irradiation, compared to vehicle-treated organoids. Conversely, we found that Wnt5a knockout decreased the cryptogenic potential of intestinal stem cells following irradiation. Treatment with recombinant Wnt5a prior to irradiation rescued the cryptogenic capacity of Wnt5a knockout organoids, indicating that Wnt5a is necessary and sufficient for duodenal radioprotection. Taken together, our results.txt suggest that HIF2 radioprotects the GI tract by inducing Wnt5a expression.
Project description:Transcriptional profiling of E18.5 livers derived from Wnt5a-deficient (KO) mice compared to those from littermate wild-type (WT) mice. RNA samples were extracted from whole livers derived from E18.5 fetuses. Two-condition experiment: Wnt5a KO vs. WT whole livers. Total RNA samples were extracted from E18.5 whole livers. KO and WT samples were a mixture of RNA solutions derived from two Wnt5a KO livers and two WT livers, respectively.
Project description:Non-canonical Wnt signaling activated by Wnt5a and Wnt11 is required for the development of second heart field cardiac progenitor cells in mice. However, the pathophysiological role of non-canonical Wnt signaling in the adult heart has not been fully elucidated. Here we show that cardiomyocyte-specific Wnt5a knockout mice exhibit improved systolic function and reduced expression of mechanosensitive genes including Nppb compared to control mice when subjected to pressure overload. In cultured cardiac myocytes, Wnt5a knockdown reduces the upregulation of Nppb gene expression and YAP nuclear translocation induced by cyclic cell stretch. Wnt5a knockdown-induced Nppb downregulation in response to cell stretch is rescued by inhibition of Hippo pathway, and the rescue effect of Hippo inhibition is canceled by YAP knockdown. These results collectively suggest that Wnt5a-YAP signaling axis mediates mechanotransduction in cardiac myocytes and contributes to the transition to heart failure.
