Dataset Information

Normalization of non-canonical Wnt signalings does not compromise blood-brain barrier protection conferred by upregulating endothelial Wnt/β-catenin signaling following ischemic stroke.

ABSTRACT:

Background

Endothelial canonical (Wnt/β-catenin) and non-canonical Wnt signalings (Wnt/PCP and Wnt/Ca²⁺ ) promote blood-brain barrier (BBB) development and antagonize each other. However, the effects of ischemic stroke on endothelial canonical and non-canonical Wnt signalings are unclear. Further, how non-canonical Wnt signalings are influenced by upregulation of endothelial Wnt/β-catenin signaling and subsequently affect BBB function following ischemic stroke have not been studied.

Methods

First, we determined the levels of Wnt signaling markers including TCF/LEF1 transcription activity, Axin2 mRNA, phospho-JNK^{Thr183/Tyr185} , and NFAT in brain endothelial cells (ECs) with the deletion of Wnt receptor Frizzled (Fzd)4 or Fzd6, the two most abundant Fzds in brain ECs. Next, we observed the effect of ischemia/reperfusion injury on Wnt signalings in brain ECs and adult mice. Last, we assessed the changes of non-canonical Wnt signalings and BBB injury in the early stage of ischemic stroke in mice with endothelial β-catenin activation (β-cat mice).

Results

Fzd4 or Fzd6 deletion dampened both Wnt/β-catenin and Wnt/PCP signalings but enhanced Wnt/Ca²⁺ signaling in brain ECs. Both canonical and non-canonical Wnt signalings in brain ECs were downregulated after ischemia/reperfusion injury in vitro and in vivo. Upregulating endothelial Wnt/β-catenin signaling in β-cat mice normalized the downregulated non-canonical Wnt signalings, which did not compromise its protective effects on BBB integrity and endothelial tight junction following ischemic stroke.

Conclusions

The BBB protection induced by upregulation of endothelial Wnt/β-catenin signaling may be not interfered by the normalization of non-canonical Wnt signalings in the early stage of ischemic stroke.

SUBMITTER: Ji YB

PROVIDER: S-EPMC8339534 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:Wnt proteins modulate cell proliferation and differentiation and the self-renewal of stem cells by inducing ?-catenin-dependent signalling through the Wnt receptor frizzled (FZD) and the co-receptors LRP5 and LRP6 to regulate cell fate decisions and the growth and repair of several tissues. The 19 mammalian Wnt proteins are cross-reactive with the 10 FZD receptors, and this has complicated the attribution of distinct biological functions to specific FZD and Wnt subtype interactions. Furthermore, Wnt proteins are modified post-translationally by palmitoylation, which is essential for their secretion, function and interaction with FZD receptors. As a result of their acylation, Wnt proteins are very hydrophobic and require detergents for purification, which presents major obstacles to the preparation and application of recombinant Wnt proteins. This hydrophobicity has hindered the determination of the molecular mechanisms of Wnt signalling activation and the functional importance of FZD subtypes, and the use of Wnt proteins as therapeutic agents. Here we develop surrogate Wnt agonists, water-soluble FZD-LRP5/LRP6 heterodimerizers, with FZD5/FZD8-specific and broadly FZD-reactive binding domains. Similar to WNT3A, these Wnt agonists elicit a characteristic ?-catenin signalling response in a FZD-selective fashion, enhance the osteogenic lineage commitment of primary mouse and human mesenchymal stem cells, and support the growth of a broad range of primary human organoid cultures. In addition, the surrogates can be systemically expressed and exhibit Wnt activity in vivo in the mouse liver, regulating metabolic liver zonation and promoting hepatocyte proliferation, resulting in hepatomegaly. These surrogates demonstrate that canonical Wnt signalling can be activated by bi-specific ligands that induce receptor heterodimerization. Furthermore, these easily produced, non-lipidated Wnt surrogate agonists facilitate functional studies of Wnt signalling and the exploration of Wnt agonists for translational applications in regenerative medicine.