P66Shc mediates increased platelet activation and aggregation in hypercholesterolemia.
OBJECTIVE
Hypercholesterolemia leads to a prothrombotic phenotype. Platelet hyperactivity associated with hypercholesterolemia has been attributed, in part, to oxidative stress. P66Shc is a well-known determinant of cellular and organismal oxidative stress. However, its role in platelet biology is not known. We hypothesized that p66Shc mediates platelet hyperactivation and hyperaggregation in hypercholesterolemia.


RESULTS
P66Shc was expressed in both human and mouse platelets, as determined by qRT-PCR and immunoblotting. Mouse platelet p66Shc expression was upregulated by hypercholesterolemia induced by high-fat diet feeding. Compared to wild-type mice, high-fat diet-induced p66Shc expression in platelets was suppressed in transgenic mice expressing a short hairpin RNA targeting p66Shc (p66ShcRNAi). High-fat diet feeding of wild-type mice amplified surface P-selectin expression on platelets stimulated by the thrombin receptor agonist protease-activated receptor-4 (PAR4), and increased aggregation of platelets induced by thrombin. These exaggerated platelet responses induced by high-fat diet feeding were significantly blunted in p66ShcRNAi mice. Finally, thrombin-stimulated platelet reactive oxygen species were suppressed in p66ShcRNAi mice.


CONCLUSIONS
Hypercholesterolemia stimulates p66Shc expression in platelets, promoting platelet oxidative stress, hyperreactivity and hyperaggregation via p66Shc.
Cardiovascular Division, Department of Internal Medicine, University of Iowa Carver College of Medicine, IA City, IA 52242, USA. Electronic address: santosh-kumar@uiowa.edu.
Santosh
S
Kumar
Cardiovascular Division, Department of Internal Medicine, University of Iowa Carver College of Medicine, IA City, IA 52242, USA.
Ajit
A
Vikram
Cardiovascular Division, Department of Internal Medicine, University of Iowa Carver College of Medicine, IA City, IA 52242, USA.
Young-Rae
YR
Kim
Cardiovascular Division, Department of Internal Medicine, University of Iowa Carver College of Medicine, IA City, IA 52242, USA.
Julia
J
S Jacobs
Cardiovascular Division, Department of Internal Medicine, University of Iowa Carver College of Medicine, IA City, IA 52242, USA. Electronic address: Kaikobad-irani@uiowa.edu.
Kaikobad
K
Irani
D000818:Animals; D059305:Diet, High-Fat; D006801:Humans; D006937:Hypercholesterolemia / Q000503:physiopathology*; D051379:Mice; D008822:Mice, Transgenic; D015539:Platelet Activation; D010974:Platelet Aggregation; D044462:Receptors, Proteinase-Activated / Q000378:metabolism; D055765:Shc Signaling Adaptor Proteins / Q000378:metabolism*; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1
D044462:Receptors, Proteinase-Activated; C528024:SHC1 protein, human; D055765:Shc Signaling Adaptor Proteins; C528034:Shc1 protein, mouse; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1
Hypercholesterolemia; Platelets; Reactive oxygen species; p66Shc