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Updated: Mar 24, 2026
Calcification of Vascular Smooth Muscle Cells and Imaging of Aortic Calcification and Inflammation
Published on: May 31, 2016
CalDAG-GEFI Deficiency Reduces Atherosclerotic Lesion Development in Mice
Yacine Boulaftali1, A Phillip Owens1, Ashley Beale1
1From the McAllister Heart Institute and Department of Medicine (Y.B., A.P.O., A.B., R.P., C.C., R.H.L., D.S.P., N.M., W.B.), Department of Biochemistry and Biophysics (W.B.), University of North Carolina at Chapel Hill; and Portola Pharmaceuticals, South San Francisco, CA (P.B.C.).
Objective:
Platelets are important for the development and progression of atherosclerotic lesions. However, relatively little is known about the contribution of platelet signaling to this pathological process. Our recent work identified 2 independent, yet synergistic, signaling pathways that lead to the activation of the small GTPase Rap1; one mediated by the guanine nucleotide exchange factor, CalDAG-GEFI (CDGI), the other by P2Y12, a platelet receptor for adenosine diphosphate and the target of antiplatelet drugs. In this study, we evaluated lesion formation in atherosclerosis-prone low-density lipoprotein receptor deficient (Ldlr(-/-)) mice lacking CDGI or P2Y12 in hematopoietic cells.
Approach And Results:
Lethally irradiated Ldlr(-/-) mice were reconstituted with bone marrow from wild-type (WT), Caldaggef1(-/-) (cdgI(-/-)), p2y12(-/-), or cdgI(-/-)p2y12(-/-) (double knockout [DKO]) mice and fed a high-fat diet for 12 weeks. Ldlr(-/-) chimeras deficient for CDGI or P2Y12 developed significantly smaller atherosclerotic lesions in the aortic sinus and in aortas when compared with the Ldlr(-/-)/WT controls. We also observed a significant reduction in platelet-leukocyte aggregates in blood from hypercholesterolemic Ldlr(-/-)/cdgI(-/-) and Ldlr(-/-)/p2y12(-/-) chimeras. Consistently, fewer macrophages and neutrophils were detected in the aortic sinus of Ldlr(-/-)/cdgI(-/-) and Ldlr(-/-)/ p2y12(-/-) chimeras. Compared with controls, the plaque collagen content was significantly higher in Ldlr(-/-) chimeras lacking CDGI. Interestingly, no statistically significant additive effects were seen in Ldlr(-/-)/DKO chimeras when compared with chimeras lacking only CDGI.
Conclusions:
Our findings suggest that CDGI is critical for atherosclerotic plaque development in hypercholesterolemic Ldlr(-/-) mice because of its contribution to platelet-leukocyte aggregate formation and leukocyte recruitment to the lesion area.
Insights
CalDAB-GEFI (CDGI) and P2Y12 signaling pathways are critical for atherosclerotic plaque development. Inhibiting these pathways reduces lesion formation and leukocyte recruitment in mice, highlighting their therapeutic potential.
Area of Science:
- Cardiovascular Research
- Immunology
- Molecular Biology
Background:
- Platelets play a key role in atherosclerosis development and progression.
- Platelet signaling pathways contributing to this process are not fully understood.
- Two synergistic pathways activating Rap1, mediated by CalDAG-GEFI (CDGI) and P2Y12, have been identified.
Purpose of the Study:
- To investigate the role of CDGI and P2Y12 in hematopoietic cells in the development of atherosclerotic lesions.
- To evaluate lesion formation in low-density lipoprotein receptor deficient (Ldlr(-/-)) mice lacking CDGI or P2Y12.
Main Methods:
- Ldlr(-/-) mice were lethally irradiated and reconstituted with bone marrow from wild-type, CDGI-deficient, P2Y12-deficient, or double-knockout mice.
- Chimeric mice were fed a high-fat diet for 12 weeks to induce atherosclerosis.
- Atherosclerotic lesion size, platelet-leukocyte aggregates, and immune cell infiltration in the aortic sinus were analyzed.
Main Results:
- Mice lacking CDGI or P2Y12 in hematopoietic cells showed significantly smaller atherosclerotic lesions.
- A reduction in platelet-leukocyte aggregates and leukocyte infiltration (macrophages, neutrophils) was observed.
- Plaque collagen content was higher in mice lacking CDGI, with no additive effect in double knockouts.
Conclusions:
- CDGI is crucial for atherosclerotic plaque development in hypercholesterolemic Ldlr(-/-) mice.
- CDGI's role is linked to promoting platelet-leukocyte aggregate formation and leukocyte recruitment.
- Targeting CDGI may offer a therapeutic strategy for atherosclerosis.
