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:Wnt5A is released from macrophages during systemic inflammation and sepsis. However, the early response targets for the paracrine action of macrophage derived Wnt5A in vascular endothelial cells still remain unclear. Here we show that Wnt5A regulates the expression of distinct molecular targets involved in inflammation, coagulation and extracellular matrix remodeling. The proteins encoded by these genes are direct targets for known drugs. Regulation of these specific targets by Wnt5A can modulate the drug response and efficiency.
Project description:We here show that the niche regulates the quality of the hematopoietic stem cells (HSCs) that are regenerated after transplantation. We find that a reduced level of Wnt5a in the niche regenerates dysfunctional HSCs, which do not successfully engraft secondary recipients. In particular, RNA sequencing shows a dysregulated Zeb1-associated gene expression of multiple genes involved in the small GTPase-dependent actin polymerization pathway. Misexpression of these genes results in reduced ability to direct polarized F-actin localization, leading to defects in adhesion, migratory behavior and homing to the bone marrow of secondary recipients. Our study further shows that the Wnt5a-haploinsufficient environment similarly affects BCR-ABLp185+ cells, which, in 42% of the studied recipients, fail to generate leukemia and, in the remaining cases, fail to transfer leukemia to secondary hosts. Thus, we show that Wnt5a in the niche is required to regenerate HSCs and leukemic cells with functional ability to rearrange the actin cytoskeleton which is required for successful engraftment.
Project description:WNTs are hydrophobic, lipid-modified proteins that control multiple functions in development and disease via short- and long-range signaling. However, it is unclear how these hydrophobic molecules reach over long distances in the mammalian brain. Here we show that WNT5A is produced by the choroid plexus (ChP) in the developing hindbrain, but not the telencephalon, in both mouse and human. Since the ChP produces and secretes the cerebrospinal fluid (CSF), we examined the presence of WNT5A in the CSF and found it is associated to lipoprotein particles rather than exosomes. Moreover, since the CSF flows along the surface of apical progenitors that do not express Wnt5a, we examined whether WNT5A up- or down-regulates their function. We found that Wnt5a down-regulates proliferation of such progenitor cells. Our study thus identifies the CSF as a route and lipoprotein particles as a vehicle for long-range transport of biologically active WNTs in the central nervous system.
Project description:Inflammatory Wnt5A signalling in human macrophages was found to be critically involved in severe systemic inflammatory response. However, the targets of Wnt5A in endothelial cells and downstream mechanisms by which Wnt5A might induce endothelial inflammation still remain unclear. We show that Wnt5A principally regulate genes involved endothelial cytoskeleton rearrangements and impairs the barrier function of cultured endothelial monolayer causing hyper permeability. We further prove that Wnt5A neither affects the expression of adhesion molecules nor induces cytokine storm in endothelial cells. These findings suggest that Wnt5A, secreted by activated macrophages during septic inflammation, paracrinically act on the endothelial wall, causing endothelial barrier breakdown and subsequent vascular leakage in sepsis.
Project description:About half of all melanomas harbor a constitutively active mutant BRAFV600E/K kinase that can be selectively inhibited by targeted BRAF inhibitors (BRAFi). While patients treated with BRAFi initially exhibit measurable clinical improvement, the majority of patients eventually develop drug resistance and relapse. We observe significant elevation of WNT5A in a subset of tumors from patients exhibiting disease progression on BRAFi therapy. WNT5A transcript and protein are also elevated in BRAFi-resistant melanoma cell lines generated by long-term in vitro treatment with BRAFi. RNAi-mediated reduction in levels of endogenous WNT5A in melanoma decreases cell growth, increases apoptosis in response to BRAFi challenge, and decreases the activity of pro-survival AKT signaling. Overexpression of WNT5A conversely promotes melanoma growth and tumorigenesis and activates AKT signaling. Similar to WNT5A knockdown, knockdown of the WNT receptors FZD7 and RYK inhibits growth, sensitizes melanoma cells to BRAFi, and reduces AKT activation. Together, these findings suggest that chronic BRAF inhibition elevates WNT5A expression, which then acts through FZD7 and RYK to promote AKT signaling, leading to increased growth and therapeutic resistance. Increased WNT5A expression in BRAFi-resistant melanomas also correlates with an associated transcriptional signature, which identifies potential therapeutic targets to reduce clinical resistance to BRAFi. Expression of WNT5A-correlated genes was compared in melanoma cell lines generated to be resistant to PLX4032 and the their associated naïve parental line Basal expression of the WNT5A-correlated genes was also measured in experiments comparing each naïve line to a mixed reference pool containing equal amounts of 47 melanoma cell lines.
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.