Enhanced Megakaryopoiesis and Platelet Activity in Hypercholesterolemic, B6-Ldlr-/-, Cdkn2a-Deficient Mice.
BACKGROUND
Genome-wide association studies for coronary artery disease/myocardial infarction revealed a 58 kb risk locus on 9p21.3. Refined genetic analyses revealed unique haplotype blocks conferring susceptibility to atherosclerosis per se versus risk for acute complications in the presence of underlying coronary artery disease. The cell proliferation inhibitor locus, CDKN2A, maps just upstream of the myocardial infarction risk block, is at least partly regulated by the noncoding RNA, ANRIL, overlapping the risk block, and has been associated with platelet counts in humans. Thus, we tested the hypothesis that CDKN2A deficiency predisposes to increased platelet production, leading to increased platelet activation in the setting of hypercholesterolemia.


RESULTS
Platelet production and activation were measured in B6-Ldlr(-/-)Cdkn2a(+/-) mice and a congenic strain carrying the region of homology with the human 9p21.3/CDKN2A locus. The strains exhibit decreased expression of CDKN2A (both p16(INK4a) and p19(ARF)) but not CDKN2B (p15(INK4b)). Compared with B6-Ldlr(-/-) controls, both Cdkn2a-deficient strains exhibited increased platelet counts and bone marrow megakaryopoiesis. The platelet overproduction phenotype was reversed by treatment with cyclin-dependent kinase 4/6 inhibitor, PD0332991/palbociclib, that mimics the endogenous effect of p16(INK4a). Western diet feeding resulted in increased platelet activation, increased thrombin/antithrombin complex, and decreased bleeding times in Cdkn2a-deficient mice compared with controls.


CONCLUSIONS
Together, the data suggest that one or more Cdkn2a transcripts modulate platelet production and activity in the setting of hypercholesterolemia, amenable to pharmaceutical intervention. Enhanced platelet production and activation may predispose to arterial thrombosis, suggesting an explanation, at least in part, for the association of 9p21.3 and myocardial infarction.
From the Department of Medicine, Division of Molecular Medicine, Columbia University, New York, NY.
Wei
W
Wang
From the Department of Medicine, Division of Molecular Medicine, Columbia University, New York, NY.
Seon
S
Oh
From the Department of Medicine, Division of Molecular Medicine, Columbia University, New York, NY.
Mark
M
Koester
From the Department of Medicine, Division of Molecular Medicine, Columbia University, New York, NY.
Sandra
S
Abramowicz
From the Department of Medicine, Division of Molecular Medicine, Columbia University, New York, NY.
Nan
N
Wang
From the Department of Medicine, Division of Molecular Medicine, Columbia University, New York, NY.
Alan R
AR
Tall
From the Department of Medicine, Division of Molecular Medicine, Columbia University, New York, NY. cbw13@cumc.columbia.edu.
Carrie L
CL
Welch
D000818:Animals; D000990:Antithrombin III / Q000378:metabolism; D050197:Atherosclerosis / Q000097:blood / Q000201:enzymology* / Q000235:genetics; D001792:Blood Platelets / Q000187:drug effects / Q000201:enzymology*; D051358:Cyclin-Dependent Kinase 4 / Q000037:antagonists & inhibitors / Q000378:metabolism; D051361:Cyclin-Dependent Kinase 6 / Q000037:antagonists & inhibitors / Q000378:metabolism; D050762:Cyclin-Dependent Kinase Inhibitor p15 / Q000378:metabolism; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000172:deficiency* / Q000235:genetics; D050763:Cyclin-Dependent Kinase Inhibitor p18 / Q000235:genetics; D004195:Disease Models, Animal; D020022:Genetic Predisposition to Disease; D006937:Hypercholesterolemia / Q000097:blood / Q000201:enzymology* / Q000235:genetics; D008533:Megakaryocytes / Q000187:drug effects / Q000201:enzymology*; D020297:Mice, Congenic; D018345:Mice, Knockout; D010447:Peptide Hydrolases / Q000378:metabolism; D010641:Phenotype; D015539:Platelet Activation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011973:Receptors, LDL / Q000172:deficiency* / Q000235:genetics; D013921:Thrombocytopenia / Q000097:blood / Q000201:enzymology* / Q000235:genetics / Q000517:prevention & control; D034061:Thrombopoiesis / Q000187:drug effects
C000614131:CDKN2A protein, human; C417743:Cdkn2a protein, mouse; C493968:Cdkn2b protein, mouse; D050762:Cyclin-Dependent Kinase Inhibitor p15; D019941:Cyclin-Dependent Kinase Inhibitor p16; D050763:Cyclin-Dependent Kinase Inhibitor p18; D047428:Protein Kinase Inhibitors; D011973:Receptors, LDL; C046193:antithrombin III-protease complex; D000990:Antithrombin III; C495902:Cdk4 protein, mouse; C495912:Cdk6 protein, mouse; D051358:Cyclin-Dependent Kinase 4; D051361:Cyclin-Dependent Kinase 6; D010447:Peptide Hydrolases
arterial thrombosis; atherosclerosis; genetics; mouse; platelet