RNA Interference of Myocyte Enhancer Factor 2A Accelerates Atherosclerosis in Apolipoprotein E-Deficient Mice

Abstract

ObjectiveMyocyte enhancer factor-2A (MEF 2A) has been shown to be involved in atherosclerotic lesion development, but its role in preexisting lesions is still unclear. In the present study we aim to assess the role of MEF 2A in the progression of pre-existing atherosclerosis.MethodsEighty apolipoprotein E-deficient mice (APOE KO) were randomly allocated to control, scramble and MEF 2A RNA interference (RNAi) groups, and constrictive collars were used to induce plaque formation. Six weeks after surgery, lentiviral shRNA construct was used to silence the expression of MEF 2A. Carotid plaques were harvested for analysis 4 weeks after viral vector transduction. Inflammatory gene expression in the plasma and carotid plaques was determined by using ELISAs and real-time RT-PCR.ResultsThe expression level of MEF 2A was significantly reduced in plasma and plaque in the RNAi group, compared to the control and NC groups, whereas the expression level of pro-inflammatory cytokines was markedly increased. Silencing MEF 2A using lentiviral shRNA significantly reduced the plaque collagen content and fibrous cap thickness, as well as increased plaque area. However, silencing MEF 2A had no obvious effect on plaque lipid content.ConclusionsLentivirus-mediated MEF 2A shRNA accelerates inflammation and atherosclerosis in APOE KO mice, but has no effect on lipoprotein levels in plasma.

Amelioration of atherosclerosis in apolipoprotein E-deficient mice by combined RNA interference of lipoprotein-associated phospholipase A2 and YKL-40

“…More importantly, the combined interference of Lp-PLA 2 and YKL-40 reduces local inflammation more efficiently than the selective interference of Lp-PLA 2 or YKL-40 alone. These results are in agreement with our previous studies showing that atherosclerosis is a multifactorial process intertwined with inflammation [ 1 , 2 , 5 ]. In addition, several lines of evidence have demonstrated that high circulating levels of YKL-40 are associated with increased MCP-1, IL-6, and TNF-α levels and macrophage recruitment in plaques [ 7 , 12 – 15 ].…”

“…The propensity to rupture is based on structural characteristics of lesions [ 22 ]. Evidences suggest that thicker fibrous cap, relative lower content of lipids, relative higher content of collagen are all indicators of plaque stability [ 1 , 2 , 4 , 5 ]. Finally, our data revealed that the plaque area for the combined Lp-PLA 2 and YKL-40 RNAi group was only moderately lower than that of the Lp-PLA 2 RNAi group, and this difference was not statistically significant.…”

“…Lipid- and collagen-positive areas were quantified by a computer-assisted color-gated technique. The percentage of the intimal area that stained positive for lipid and collagen was calculated as previously described [ 1 , 4 , 5 ].…”

“…Atherosclerosis and its clinical complications are the leading causes of death and disability in the western world [ 1 ]. It has been increasingly recognized that atherosclerosis is a complex, multifactorial process intertwined with inflammation [ 2 , 3 ].…”

Molecular mechanisms and genetic regulation in atherosclerosis

“…Further in vitro studies confirmed that cZNF609 acted as miR-615-5p, bonded to Ago2, the core part of RNA induced silencing complex (RISC), inhibited the expression of myocyte enhancer factor 2A(MEF2A) transcription factor and Tie2, a tyrosine-protein kinase that acts as cell-surface receptor for angiopoietins during angiogenesis, ECs survival, increased OS, ECs dysfunction and migration in HUVECs. However, researchers have shown that alteration of MEF2A and Tie2 accelerated vascular inflammation by activating proinflammatory signaling, macrophage infiltration, ECs dysfunction and AS in apoE deficiency mice [ 11 , [84] , [85] , [86] , [87] ].…”