Abstract
MicroRNAs (miRs) and bone morphogenetic protein receptor–specific Smads are mechano-responsive molecules that play vital roles in modulating endothelial cell (EC) functions in response to blood flow. However, the roles of interplay between these molecules in modulating EC functions under flows remain unclear. We elucidated the regulatory roles of the interplay between miR-487a and Smad5 in EC proliferation in response to different flow patterns. Microarray and quantitative RT-PCR showed that disturbed flow with low and oscillatory shear stress (OS, 0.5 ± 4 dynes/cm2) upregulates EC miR-487a in comparison to static controls and pulsatile shear stress (12 ± 4 dynes/cm2). MiR-487a expression was higher in ECs in the inner curvature (OS region) than the outer curvature of the rat aortic arch and thoracic aorta and also elevated in diseased human coronary arteries. MiR-487a expression was promoted by nuclear phospho-Smad5, which bound to primary-miR-487a to facilitate miR-487a processing. Algorithm prediction and luciferase reporter and argonaute 2-immunoprecipitation assays demonstrated that miR-487a binds to 3′UTR of CREB binding protein (CBP) and p53. Knockdown and overexpression of miR-487a decreased and increased, respectively, phospho-Rb and cyclin A expressions through CBP and p53. A BrdU incorporation assay showed that miR-487a enhanced EC proliferation under OS in vitro and in disturbed flow regions of experimentally stenosed rat abdominal aorta in vivo. These results demonstrate that disturbed flow with OS induces EC expression of miR-487a through its enhanced processing by activated-Smad5. MiR-487 inhibits its direct targets CBP and p53 to induce EC cycle progression and proliferation. Our findings suggest that EC miR-487 may serve as an important molecular target for intervention against disturbed flow–associated vascular disorders resulting from atherosclerosis.
Highlights
Endothelial cell (EC) dysfunction is a critical step leading to vascular pathologies, including atherosclerosis, which develop preferentially in arterial branches and curvatures, where the local flow is disturbed with low and oscillatory shear stress (OS) (Chiu and Chien, 2011)
Detailed procedures are described in online Supplementary Documents
The results showed that nine of 380 human miRs are significantly upregulated by OS in ECs in comparison to pulsatile shear stress (PS)-stimulated and static control cells (Table 1 and online Supplementary Table 1)
Summary
Endothelial cell (EC) dysfunction is a critical step leading to vascular pathologies, including atherosclerosis, which develop preferentially in arterial branches and curvatures, where the local flow is disturbed with low and oscillatory shear stress (OS) (Chiu and Chien , 2011). The straight part of the artery, which is exposed to sustained laminar flow with pulsatile shear stress (PS) having a clear direction, is generally spared from atherosclerotic lesions (Chiu and Chien , 2011). Bone morphogenetic protein (BMP)-4 and BMP receptor (BMPR)-specific Smads (i.e., Smad1/5/8) are shown to be activated in ECs by disturbed flow with OS (Sorescu et al, 2003). BMPR-specific Smads are shown to regulate EC responses to OS, the detailed mechanisms by which BMPRspecific Smads regulate OS-induced EC cycle progression and proliferation remain unclear
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
