Different MicroRNA Expression Profiles in Murine Aorta and Carotid Arteries

Atherosclerosis, a major cause of death, affects vascular walls diffusely. Some vascular beds are, however, preferentially involved. Small noncoding RNAs, microRNAs, have emerged as key regulators of gene expression in either physiological or pathophysiological processes. Here, we investigated whether different vascular beds, commonly affected by atherosclerosis, present specific microRNA expression profiles. To this end, aorta (Ao) and carotid (Ca) arteries from two male Wistar rats (200 g) were dissected, total RNA was extracted with Trizol, and the small RNA fraction was enriched using magnetic beads. Sequencing was performed using RNA-Seq on Ion Torrent PGM platform and data were analyzed using CLC Genomics Workbench software. We identified 372 and 305 microRNAs in Ca and Ao, respectively - the arteries shared 280 microRNAs. The majority of the 20 most expressed microRNAs were similar between the arteries. Of these top 20, 90% in the Ao were also among the most expressed in Ca, and in Ca 65% were also among the most expressed in Ao. Both mechano and platelet-microRNAs were identified in both arteries. Note that overexpression of mechano-miR-21 is reported to attenuate lipid accumulation and to reduce inflammation, preventing atherosclerosis. We detected mechano-miR-21, however, only in the Ao. We also found that murine aorta and carotid arteries express differently 29 microRNAs (pu003c0.05). Among the 29 microRNAs, 8 (28%) have been related to atherosclerosis. Of these, 6 were more expressed in Ca (miR-181, miR-9a-1, miR-9a-2, miR-511, miR-146, miR-27), and 2 were more expressed in Ao (miR-144 and miR-322). Note that 3 of the 6 more expressed microRNAs in Ca are related to atherosclerosis, that is: miR-181 regulates cell stress and proliferation; miR-511 regulates cholesterol synthesis, and miR-27 is a known marker of the disease. Taken together, our results suggest that specific microRNA expression profiles may play a role in the vascular behavior during the atherosclerotic process.