<i>SENCR</i> stabilizes vascular endothelial cell adherens junctions through interaction with CKAP4.

Abstract

<i>SENCR</i> is a human-specific, vascular cell-enriched long-noncoding RNA (lncRNA) that regulates vascular smooth muscle cell and endothelial cell (EC) phenotypes. The underlying mechanisms of action of <i>SENCR</i> in these and other cell types is unknown. Here, levels of <i>SENCR</i> RNA are shown to be elevated in several differentiated human EC lineages subjected to laminar shear stress. Increases in <i>SENCR</i> RNA are also observed in the laminar shear stress region of the adult aorta of humanized <i>SENCR</i>-expressing mice, but not in disturbed shear stress regions. <i>SENCR</i> loss-of-function studies disclose perturbations in EC membrane integrity resulting in increased EC permeability. Biotinylated RNA pull-down and mass spectrometry establish an abundant <i>SENCR</i>-binding protein, cytoskeletal-associated protein 4 (CKAP4); this ribonucleoprotein complex was further confirmed in an RNA immunoprecipitation experiment using an antibody to CKAP4. Structure-function studies demonstrate a noncanonical RNA-binding domain in CKAP4 that binds <i>SENCR</i> Upon <i>SENCR</i> knockdown, increasing levels of CKAP4 protein are detected in the EC surface fraction. Furthermore, an interaction between CKAP4 and CDH5 is enhanced in <i>SENCR</i>-depleted EC. This heightened association appears to destabilize the CDH5/CTNND1 complex and augment CDH5 internalization, resulting in impaired adherens junctions. These findings support <i>SENCR</i> as a flow-responsive lncRNA that promotes EC adherens junction integrity through physical association with CKAP4, thereby stabilizing cell membrane-bound CDH5.