Vascular Bone Morphogenetic Protein (BMP) expression decreases after mouse carotid ligation

Abstract

BMPs have been previously identified in atherosclerotic lesions. The purpose of this study was to characterize the temporal changes in BMP expression following acute alterations in blood flow using a mouse model of arterial remodeling. Methods. We evaluated bmp expression in mouse carotid vessels after acute ligation of the common carotid artery at its bifurcation. Male C57/Bl6 mice weighing 19–21 g underwent left carotid ligation followed by harvest at 3 ( n = 7) and 7 ( n = 7) days. Carotid vessels from unoperated mice were harvested and used as controls ( n = 5). Vessels were snap-frozen in liquid nitrogen prior to RNA extraction and cDNA syntheses using reverse transcriptase. Expression of bmp2, bmp4, bmp7, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was then examined using quantitative real-time polymerase chain reaction (qRT-PCR). Product identities were confirmed using melt curve analysis and sequencing. Baseline subtracted cycle threshold data were analyzed using the 2 −(ΔCT) formula to quantify bmp expression relative to GAPDH for each specimen. Copy numbers relative to GAPDH were analyzed using analysis of variance (ANOVA). Results. Expression of bmp4 decreased by 71% of control at 3 days postligation (ANOVA, P = 0.04) and returned to baseline levels by 7 days. A similar trend was observed for bmp2 expression (ANOVA, P = 0.008). However, no change in bmp7 mRNA levels was identified in this series of experiments. Conclusion. Acute flow changes caused by carotid ligation produce a temporary decrease in bmp4 and bmp2 mRNA levels at 3 days with a return to baseline levels by day 7. This data suggest that BMPs may be involved in the vascular remodeling that occurs in response to changes in blood flow.