Identification of a novel gene that regulates proliferation and lipid metabolism in lymphatic endothelial cells

Abstract

Developmental lymphatic vascular defects are a major cause of fetal nuchal edema, which is characterized by a subcutaneous accumulation of extracellular fluid in the fetal neck. Fetal nuchal edema is visualized as increased nuchal translucency by ultrasonography. It is found to be associated with chromosomal anomalies in about ten percent of clinical cases, whereas causative genes have not been elucidated in many clinical cases. In this study, we aimed to identify novel causative genes of fetal nuchal edema and lymphatic vascular defects through N-Ethyl-N-nitrosourea-induced mutagenesis screening in mice. This screening detected mouse embryos exhibiting both fetal nuchal edema and lymphatic vascular defect. Exome sequencing of the genomic DNA from these embryos revealed the candidate causative genes for fetal nuchal edema. Knockout of a candidate causative gene by CRISPR/Cas9 system in mice induced fetal nuchal edema and lymphatic vascular defects. Gene silencing by small interfering RNA in culture inhibited proliferation of lymphatic endothelial cells  and also reduced mRNA expression of HMGCR and FASN encoding 3-hydroxy-3-methylglutaryl-coA reductase and fatty acid synthase, respectively. In conclusion, we identified a novel gene that regulates both proliferation and lipid metabolism in lymphatic endothelial cells.