bmp3 is Required for Integrity of Blood Brain Barrier by Promoting Pericyte Coverage in Zebrafish Embryos

Background: The compromise of blood brain barrier (BBB) integrity is often associated with human hemorrhage stroke and neurodegeneration diseases, including retina diseases, such as age-related macular degeneration and diabetic retinopathy. Brain pericytes play pivotal roles in regulation and maintenance of BBB integrity. However, the mechanisms underlying brain pericyte development to establish BBB integrity remain unclear. Methods: Zebrafish transgenic lines Tg(flk1:GFP; gata1:dsRed), Tg(flk1:GFP), Tg(fli1:GFP) and Tg(BRE:GFP) were used in this work. The functional studies of bmp3 were performed by mopholino oligonucleotide (MO) injection, dye-based permeability assay, RT-PCR, in vivo imaging, immunofluorescence staining and statics analysis. Results: Here we report that bmp3 regulates BBB integrity in zebrafish brain by promoting pericyte development. Knockdown of bmp3 with injection of bmp3-MO causes intracerebral hemorrhage in zebrafish embryos. Meanwhile, disruption of bmp3 function by bmp3-MO injection impairs cerebral pericyte coverage in zebrafish embryos. Mechanistically, knockdown of bmp3 disrupts the pattern and activities of BMP signaling in zebrafish brain, thus probably disrupting the balance of TGFβ/BMP signaling in zebrafish embryos. Conclusion: In summary, our data shows that bmp3 regulates BBB integrity potentially by promoting pericyte development.