Versican is crucial for the initiation of cardiovascular lumen development in medaka (Oryzias latipes)

Nishant Mittal,Misato Fujita,Hideto Watanabe,Hirokazu Enomoto,Atsushi Kawakami,Shinji Makino,Atsushi Shimizu,Miyama Hiroshi,Sung Han Yoon,Keiichi Fukuda

doi:10.1038/s41598-019-45851-3

Abstract

Versican is an evolutionary conserved extracellular matrix proteoglycan, and versican expression loss in mice results in embryonic lethality owing to cardiovascular defects. However, the in utero development of mammals limits our understanding of the precise role of versican during cardiovascular development. Therefore, the use of evolutionarily distant species that develop ex utero is more suitable for studying the mechanistic basis of versican activity. We performed ENU mutagenesis screening to identify medaka mutants with defects in embryonic cardiovascular development. In this study, we described a recessive point mutation in the versican 3′UTR resulting in reduced versican protein expression. The fully penetrant homozygous mutant showed termination of cardiac development at the linear heart tube stage and exhibited absence of cardiac looping, a constricted outflow tract, and no cardiac jelly. Additionally, progenitor cells did not migrate from the secondary source towards the arterial pole of the linear heart tube, resulting in a constricted outflow tract. Furthermore, mutants lacked blood flow and vascular lumen despite continuous peristaltic heartbeats. These results enhance our understanding of the mechanistic basis of versican in cardiac development, and this mutant represents a novel genetic model to investigate the mechanisms of vascular tubulogenesis.

Highlights

The development of the cardiovascular system is a complex and dynamic process regulated by multiple cell-cell and cell-extracellular matrix (ECM) interactions[1], and changes in these molecular interactions can result in congenital heart diseases (CHDs) that occur in approximately 1% human live births[2]
Using three independent experiments with control MO and antisense MO oligonucleotides directed against zebrafish versican-a, we demonstrated that 83.5% (91/109) of the morphants showed an absence of cardiac looping; depicting a linear heart tube, 78% (85/109) of the morphants showed constricted outflow tracts, and 87.1% (95/109) of the morphants lacked blood circulation
ECM is enriched in hyaluronan and proteoglycans, including versican

Summary

Introduction

The development of the cardiovascular system is a complex and dynamic process regulated by multiple cell-cell and cell-extracellular matrix (ECM) interactions[1], and changes in these molecular interactions can result in congenital heart diseases (CHDs) that occur in approximately 1% human live births[2]. In the heart defect (hdf) mouse mutant, transgene insertion disrupted versican expression, resulting in embryonic lethality owing to an abnormal right ventricle, the absence of an outflow tract, and no cardiac jelly[7,8]. In another murine model, after deletion of the hyaluronan binding domain (A-subdomain of the G1-domain in versican; VcanΔ3/Δ3) in a congenic C57BL/6 background, the embryos died at E10.5, to the hdf phenotype[9]. Our studies showed the great potential of lht mutants as a novel model system to understand the mechanistic basis of vascular lumen formation

Methods

Results

Conclusion