Protein carbonylation and cellular dysfunction at the crossroad of atherosclerosis and diabetes – CARINA

Reactive carbonyl compounds (RCCs) are formed during lipid peroxidation and carbohydrate glycoxidation and are precursors of advanced glycation end products (AGEs) and advanced lipid peroxidation end products (ALEs). AGEs and ALEs form cross-links on proteins (carbonyl stress) and are thought to contribute to tissue damages and to the progression of atherosclerosis, diabetes and related diseases. Among a broad range of cellular targets, AGEs and ALEs can modify signaling proteins such as growth factor receptors (PDGF-R and EGF-R), which could disturb cell proliferation and survival. The accumulation of RCCs in the lipid necrotic core, observed in advanced atherosclerotic lesions, could contribute to macrophage apoptosis and plaque destabilization. Likewise, AGEs formed on circulating lipoproteins (LDL and HDL), render them proatherogenic. HDL isolated from diabetic patients, are less protective and exhibit lower antioxidant properties. It can be expected that carbonyl stress should aggravate the outcome of atherosclerotic lesions, by i/ disturbing smooth muscle cells (SMC) migration and proliferation and extracellular matrix remodelling, ii/ inhibiting protective systems within the lipid core, such as the antiapoptotic chaperone proteins, and iii/ decreasing the properties of HDLs, in particular HDL3c subfractions which are the most active for cholesterol efflux and the most protective against oxidative stress and apoptosis.
Our objectives are to i/ check whether RCC-modification of growth factor receptors affects their cellular signaling, particularly the sphingosine 1-phosphate (S1P) pathway (that requires PDGFR activity and is) involved in SMC migration and proliferation, and whether carbonyl stress alters the function of protein components of the extracellular matrix, ii/ check the consequences of RCC-modification on protective ER-chaperones in the lipid core, and the consequences of an imbalance survival/apoptosis, which determine the fate of the lesions, iii/ establish a lipidomic and proteomic profile of carbonylated HDLs and check the consequences on their antiatherogenic properties, iv/ correlate the AGE- and ALE-modifications of HDL subfractions to the progression of the disease.
This project implicates two teams coming from different fields of lipoprotein metabolism and oxidation, and expert in the physiopathology of atherosclerosis and in translational research on patients affected with metabolic syndrome, diabetes and cardiovascular diseases. These teams are already collaborating together, and will share their expertise to carry out this innovative proposal. The program is divided into 3 tasks: Tasks 1 and 2 aim to identify the precise targets of RCC in intimal hyperplasia and atherosclerotic plaques, particularly the systems involved in SMC migration and proliferation, ECM remodeling, cellular and tissular protection against apoptosis. Task 3 will study the consequences of carbonyl stress on HDL subfractions, with focus on their proteomic and lipidomic modifications, correlated with the decrease in their antiatherogenic properties.
The main expected achievements are the following:
- Carbonyl stress should strongly affect SMC migration and proliferation induced by growth factor receptors, as well as ECM components. These events are suspected to affect the composition and the structure of the fibrous cap, and promote plaque fragility and rupture.
- The modification of ER chaperones should impair in situ and in vitro their protective antiapoptotic function (loss of calcium-buffering activity, enzymatic activity, folding of proteins, ER stress increase and switch towards apoptosis), thus contributing to macrophage death and to the extention of the necrotic lipid core.
- Proteomic and lipidomic studies on HDLs subfractions should allow identifying biomarkers of carbonyl stress associated to the loss of their antiatherogenic properties, in patients affected with diabetes and cardiovascular diseases.