Increased gene dosage of the Ink4/Arf locus does not attenuate atherosclerosis development in hypercholesterolaemic mice.
BACKGROUND
Human genome-wide association studies have identified genetic variants in the chromosome 9p21 region that confer increased risk of coronary artery disease and other age-related diseases. These variants are located in a block of high linkage disequilibrium with the neighboring Ink4/Arf tumor-suppressor locus (also named CDKN2A/CDKN2B). Since previous studies suggest an atheroprotective role of the Ink4/Arf locus, here we assessed whether gain-of-function of the encoded genes can be exploited therapeutically to reduce atherosclerosis.


METHODS
Generation and characterization of apolipoprotein E-null mice carrying an additional transgenic copy of the entire Ink4/Arf locus (apoE-/-Super-Ink4/Arf) that reproduces the normal expression and regulation of the endogenous locus.


RESULTS
Although liver and aorta of apoE-/-Super-Ink4/Arf mice only showed a trend towards increased Ink4/Arf transcript levels compared to apoE-/- controls, cultured macrophages with increased Ink4/Arf gene dosage exhibited augmented apoptosis induced by irradiation with ultraviolet light, indicating that low level of transgene overexpression can lead to augmented Ink4/Arf function. However, increased Ink4/Arf gene dosage did not affect atherosclerosis development in different vascular regions of both male and female apoE-/- mice fed either normal or high-fat diet. Increased gene dosage of Ink4/Arf similarly had no effect on atheroma cell composition or collagen content, an index of plaque stability.


CONCLUSIONS
In contrast with previous studies demonstrating cancer resistance in Super-Ink4/Arf mice carrying an additional transgenic copy of the entire Ink4/Arf locus, our results cast doubt on the potential of Ink4/Arf activation as a strategy for the treatment of atherosclerotic disease.
Department of Epidemiology, Atherothrombosis and Imaging, Centro Nacional de Investigaciones Cardiovasculares, Melchor Fernández Almagro 3, 28029 Madrid, Spain.
José J
JJ
Fuster
Pedro
P
Molina-Sánchez
David
D
Jovaní
Ángela
Á
Vinué
Manuel
M
Serrano
Vicente
V
Andrés
D000818:Animals; D001013:Aorta, Thoracic / Q000378:metabolism / Q000473:pathology; D001018:Aortic Diseases / Q000209:etiology* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D001057:Apolipoproteins E / Q000172:deficiency / Q000235:genetics; D017209:Apoptosis; D050197:Atherosclerosis / Q000209:etiology* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D049109:Cell Proliferation; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D050762:Cyclin-Dependent Kinase Inhibitor p15 / Q000235:genetics / Q000378:metabolism*; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics / Q000378:metabolism*; D059305:Diet, High-Fat; D004195:Disease Models, Animal; D005260:Female; D018628:Gene Dosage; D006937:Hypercholesterolemia / Q000150:complications* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008099:Liver / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D014466:Ultraviolet Rays
D001057:Apolipoproteins E; C417743:Cdkn2a protein, mouse; C493968:Cdkn2b protein, mouse; D050762:Cyclin-Dependent Kinase Inhibitor p15; D019941:Cyclin-Dependent Kinase Inhibitor p16; D003094:Collagen