Mechanistic insights into autocrine and paracrine roles of endothelial GABA signaling in the embryonic forebrain

Yong Kee Choi,Anju Vasudevan

doi:10.1038/s41598-019-52729-x

Abstract

The developing cerebral cortex uses a complex developmental plan involving angiogenesis, neurogenesis and neuronal migration. Our recent studies have highlighted the importance of endothelial cell secreted GABA signaling in the embryonic forebrain and established novel autonomous links between blood vessels and the origin of neuropsychiatric diseases. A GABA pathway operates in both endothelial cells and GABAergic neurons of the embryonic telencephalon; however, while the neuronal GABA pathway has been extensively studied, little is known about the endothelial GABA pathway. Our recently generated Vgat endothelial cell knockout mouse model that blocks GABA release from endothelial cells, serves as a new tool to study how endothelial GABA signaling shapes angiogenesis and neurovascular interactions during prenatal development. Quantitative gene expression profiling reveals that the endothelial GABA signaling pathway influences genes connected to specific processes like endothelial cell proliferation, differentiation, migration, tight junction formation, vascular sprouting and integrity. It also shows how components of the neuronal GABA pathway, for instance receptor mediated signaling, cell cycle related components and transcription factors are affected in the absence of endothelial GABA release. Taken together, our findings delineate the close relationship between vascular and nervous systems that begin early in embryogenesis establishing their future interactions and interdependence.

Highlights

GABA is well established as the first excitatory transmitter to become functional in the embryonic brain and exerts diverse region-specific roles at different developmental stages
VgatECKO neurons isolated at embryonic stage 15 (E15) have already undergone significant molecular changes in the absence of endothelial cell secreted GABA in vivo
Principal component analysis (PCA) showed differences in molecular signatures between endothelial cells and neurons from VgatECKO and Vgatfl/fl telencephalon based on cell segregation, that were further supported by strict clustering of independent triplicates (Fig. 1b)

Summary

Introduction

GABA is well established as the first excitatory transmitter to become functional in the embryonic brain and exerts diverse region-specific roles at different developmental stages. The VgatECKO mouse model is ideal to address such questions It is significant for identifying the mechanistic basis by which endothelial cell secreted GABA achieves its autocrine actions on angiogenesis and paracrine actions on neurons, and, it serves as new resource, to isolate hitherto unknown or novel molecular mechanisms that regulate vascular development in the embryonic forebrain. Our results show that extensive molecular changes occurred within the telencephalic endothelium and within neuronal cells due to loss of endothelial GABA release It provides valuable insights into altered expression of transcription factors, Wnt signaling and tight junction molecules as well as new GABA signaling components in VgatECKO endothelial cells. Our study explains how changes in cell-type specific gene expression are a key determinant of behavioral outcome

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Results

Conclusion