NOGOB receptor deficiency increases cerebrovascular permeability and hemorrhage via impairing histone acetylation–mediated CCM1/2 expression
Zhi Fang, … , Wenquan Hu, Qing Robert Miao
Zhi Fang, … , Wenquan Hu, Qing Robert Miao
Published March 22, 2022
Citation Information: J Clin Invest. 2022;132(9):e151382. https://doi.org/10.1172/JCI151382.
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Research Article Angiogenesis Vascular biology

NOGOB receptor deficiency increases cerebrovascular permeability and hemorrhage via impairing histone acetylation–mediated CCM1/2 expression

Abstract

The loss function of cerebral cavernous malformation (CCM) genes leads to most CCM lesions characterized by enlarged leaking vascular lesions in the brain. Although we previously showed that NOGOB receptor (NGBR) knockout in endothelial cells (ECs) results in cerebrovascular lesions in the mouse embryo, the molecular mechanism by which NGBR regulates CCM1/2 expression has not been elucidated. Here, we show that genetic depletion of Ngbr in ECs at both postnatal and adult stages results in CCM1/2 expression deficiency and cerebrovascular lesions such as enlarged vessels, blood-brain-barrier hyperpermeability, and cerebral hemorrhage. To reveal the molecular mechanism, we used RNA-sequencing analysis to examine changes in the transcriptome. Surprisingly, we found that the acetyltransferase HBO1 and histone acetylation were downregulated in NGBR-deficient ECs. The mechanistic studies elucidated that NGBR is required for maintaining the expression of CCM1/2 in ECs via HBO1-mediated histone acetylation. ChIP-qPCR data further demonstrated that loss of NGBR impairs the binding of HBO1 and acetylated histone H4K5 and H4K12 on the promotor of the CCM1 and CCM2 genes. Our findings on epigenetic regulation of CCM1 and CCM2 that is modulated by NGBR and HBO1-mediated histone H4 acetylation provide a perspective on the pathogenesis of sporadic CCMs.

Authors

Zhi Fang, Xiaoran Sun, Xiang Wang, Ji Ma, Thomas Palaia, Ujala Rana, Benjamin Miao, Louis Ragolia, Wenquan Hu, Qing Robert Miao

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Figure 2

EC-specific Ngbr-knockout mice exhibit enlarged microvessels, increased phosphorylation of MLC, and disrupted AJs and TJs in the brain.

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EC-specific Ngbr-knockout mice exhibit enlarged microvessels, increased ...
(A) Immunofluorescent staining showing enlargement of microvessels in the brain of NgbrECKO mice. IB4 (red) was used to label ECs and DAPI (blue) was used to label nuclei. Scale bars: 20 μm. (B–G) Immunofluorescent staining and quantification results showing increased phos-MLC and impaired AJs (VE-cadherin, VE-cad) and TJs (claudin-5, Cldn5) coverage of ECs in the brain lesions of NgbrECKO mice. Tissue sections were stained for phos-MLC (green)/CD31 (red)/DAPI (blue), claudin-5 (green)/CD31 (red)/DAPI (blue), or VE-cadherin (green)/CD31 (red)/DAPI (blue). Scale bars: 20 μm (B, D, and F). Results were quantified using ImageJ software. Data are presented as mean ± SD, n = 6 per group . Significance was tested by 2-tailed, unpaired Student’s t test. ***P < 0.001 (C, E, and G). (H and I) Electron microscopy images of microvessels in the brain and quantification of filopodia (Fil) and caveolae (Cav) in both Ngbrfl/fl and NgbrECKO groups. Electron microscopy images show enlarged vessel lumen (Lum) and irregular endothelial shape with a rough luminal surface in the brain of NgbrECKO mice compared with that of Ngbrfl/fl mice. Caveolae, filopodia, and junction gaps (Gap) between ECs were observed in the NgbrECKO group but not in the littermate control group (Ngbrfl/fl). RBC, red blood cells; Nuc, nucleus. Scale bars: 2 μm (low-magnification images and 0.5 μm (high-magnification images). n = 10 views randomly selected from 3 mice per group. Significance was tested by 2-tailed, unpaired Student’s t test. **P < 0.01, ***P < 0.001.