Abstract 14039: A Diet Induced Atherosclerosis in LDLR-/- Mice Is Associated With Altered HDL Proteome Dynamics
HDL promotes reverse cholesterol transport (RCT), anti-oxidant and anti-inflammatory activities that protect against CVD. Recently, the protein makeup of HDL has been identified and it was shown that CVD is associated with alterations in the HDL proteome composition. Although the static quantitation of the HDL proteome is important, it does not explain the underlying mechanism of dysfunctional HDL. Recently, we developed a novel method for studying proteome dynamics employing heavy water (2H2O)-based metabolic labeling coupled with high-resolution mass-spectrometry and specialized software. In this study, we applied this 2H-labeling approach to assess the effect of a Western type diet (WD, high fat diet containing 0.15% cholesterol) on HDL proteome dynamics in LDLR-/- mice. We hypothesized that a WD would alter composition and turnover rates of HDL proteins.
Methods: LDLR-/- mice were fed with low fat chow or a WD for 12 weeks (n=5 in each group). One week before sacrifice, mice were given 2H2O in the drinking water and serial blood samples were collected at different time points. Aortic root lesions were quantified to assess atherosclerosis. HDL was isolated and 2H-labeling of tryptic peptides were analyzed by high resolution mass spectrometry.
Results: A WD leads to atherosclerosis in LDLR-/- mice that is associated with an altered HDL composition and turnover. The kinetics of 43 previously identified HDL proteins involved in lipid metabolism (apoAI, apoAIV, apoE, apoH), thrombosis (prothrombin, kininogen), protease inhibition (SERPIN, A3K, SERPIN 2a), complement regulation (C3-C9, factors B, D, H), and acute-phase response (haptoglobin, hemopexin, CRP, and fibrinogen) were quantified. The analyzed HDL proteins exhibit wide ranges of half-lives ranging from a few hours to days. For instance, in low fat fed LDLR-/- mice, apoE, apoAI and paraxonase 1 have half-lives 5, 15 and 64 hours, respectively. A WD increased the turnover rates of proteins involved in complement activation and acute-phase response. In contrast, the production rates of proteins involved in RCT (apoAI and phospholipid transfer) were reduced by a WD.
In conclusion, 2H2O-labeling allows for the measurement of HDL proteome flux that is relevant to HDL functionality.
- © 2013 by American Heart Association, Inc.