Primary cilia are present on endothelial cells of the hyaloid vasculature but are not required for the development of the blood-retinal barrier

• Published in: PloS one 2020-07, Vol.15 (7), p.e0225351
• Main Authors: Pollock, Lana M, Perkins, Brian, Anand-Apte, Bela
• Format: Article
• Language: English
• Subjects: Adaptor Proteins, Signal Transducing - genetics; Adaptor Proteins, Signal Transducing - metabolism; Animals; Animals, Genetically Modified; Biology and Life Sciences; Blood; Blood plasma; Blood-Retinal Barrier - drug effects; Blood-Retinal Barrier - metabolism; Blood-Retinal Barrier - physiology; Brain research; Breakdown; Cell development (Biology); Cilia; Cilia - metabolism; Danio rerio; Embryos; Endothelial cells; Endothelial Cells - cytology; Endothelial Cells - metabolism; Endothelium; Fatty acid-binding protein; Fish diseases; Fluorescence; Green fluorescent protein; Hedgehog protein; Hedgehog Proteins - antagonists & inhibitors; Hedgehog Proteins - genetics; Hedgehog Proteins - metabolism; Hemorrhage; Integrity; Larva - metabolism; Larvae; Medicine and Health Sciences; Microscopy; Microvasculature; Mutagenesis; Mutants; Mutation; Observations; Physiological research; Properties; Proteins; Research and Analysis Methods; Retina; Retinal Vessels - cytology; Signal Transduction; Veratrum Alkaloids - pharmacology; Vitamin D; Vitamin D-binding protein; Zebrafish; Zebrafish - growth & development; Zebrafish - metabolism; Zebrafish Proteins - genetics; Zebrafish Proteins - metabolism
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0225351

Endothelial cilia are found in a variety of tissues including the cranial vasculature of zebrafish embryos. Recently, endothelial cells in the developing mouse retina were reported to also possess primary cilia that are potentially involved in vascular remodeling. Fish carrying mutations in intraflagellar transport (ift) genes have disrupted cilia and have been reported to have an increased rate of spontaneous intracranial hemorrhage (ICH), potentially due to disruption of the sonic hedgehog (shh) signaling pathway. However, it remains unknown whether the endothelial cells forming the retinal microvasculature in zebrafish also possess cilia, and whether endothelial cilia are necessary for development and maintenance of the blood-retinal barrier (BRB). In the present study, we found that the endothelial cells lining the zebrafish hyaloid vasculature possess primary cilia during development. To determine whether endothelial cilia are necessary for BRB integrity, ift57, ift88, and ift172 mutants, which lack cilia, were crossed with the double-transgenic zebrafish strain Tg(l-fabp:DBP-EGFP;flk1:mCherry). This strain expresses a vitamin D-binding protein (DBP) fused to enhanced green fluorescent protein (EGFP) as a tracer in the blood plasma, while the endothelial cells forming the vasculature are tagged by mCherry. The Ift mutant fish develop a functional BRB, indicating that endothelial cilia are not necessary for early BRB integrity. Additionally, although treatment of zebrafish larvae with Shh inhibitor cyclopamine results in BRB breakdown, the Ift mutant fish were not sensitized to cyclopamine-induced BRB breakdown.