The 3D structure of the myoendothelial projections: intracellular organelles, protein trafficking and biological function (677.12)

Abstract

The 3‐D structure of the myoendothelial projections: intracellular organelles, protein trafficking and biological Function Nadia Maarouf and Donald G. Welsh Department of physiology and pharmacology, University of Calgary, Calgary, AB, Canada Endothelial and smooth muscle cells communicate with one another in order to regulate vessel diameter. A key element of heterocellular communication is the myoendothelial projection, a thin endothelial extension that crosses the internal elastic lamina to make contact with the smooth muscle. The aim of this study was to ascertain the structural composition of the myoendothelial projection using electron tomography, a technique that enables the generation of 3‐D models. Anatomical models from mesenteric arteries reveal that myoendothelial projections are generally devoid of membranous structures, contrary to current thought. Intriguingly, key organelles such as endoplasmic reticulum with ribosomes, caveolae and vesicles were found in abundance at the base of the projection. The presence and positioning of the ribosomal endoplasmic reticulum suggests that in addition to governing Ca2+ regulation, this organelle contributes to protein packaging and trafficking to the plasma membrane which may include ion channels. In summary, the electron tomography approach provides valuable structural insight into the detailed composition of myoendothelial projections and their potential role in arterial tone regulation.Grant Funding Source: CIHR