MicroRNAs in flow-dependent vascular remodelling.

Changes in haemodynamic forces in the vascular system result in an altered expression of miRs, which play important gene-regulatory roles by pairing to the mRNAs of protein-coding genes to fine-tune post-transcriptional repression. The development and structure of blood vessels are highly adapted to haemodynamic forces, such as shear stress, cyclic stretch, and circumferential wall stress, generated by the conductance of blood. Thus, fluctuations in shear stress contribute to miR-regulated differential gene expression in endothelial cells (ECs), which is essential for maintenance of vascular physiology. Several microRNAs have been identified that are induced by high shear stress mediating an atheroprotective role, such as miR-10a, miR-19a, miR-23b, miR-101, and miR-143/145. While changes in the expression profile of miR-21 and miR-92a by high shear stress are associated with an atheroprotective function, low shear stress-induced expression of miR-21, miR-92a, and miR-663 results in a pathological EC phenotype. MiR-155 fulfils pleiotropic functions in different regions of vasculature, when exposed to different modes of shear stress. Thus, changes in shear stress result in differential expression of numerous miRs, triggering the balance between susceptibility and resistance to cardiovascular diseases. Further elucidating the regulation of miRs by flow may allow future clinical applications of miRs as diagnostic and therapeutic tools.