title: Atheroma development in apolipoprotein E-null mice is not regulated by phosphorylation of p27(Kip1) on threonine 187.
abstract: Excessive cellular proliferation is thought to contribute to neointimal lesion development during atherosclerosis and restenosis after angioplasty. Inhibition of cyclin-dependent kinase (CDK) activity by p27 inhibits mammalian cell growth. Mounting evidence indicates that p27 negatively regulates neointimal thickening in animal models of restenosis and atherosclerosis, and its expression in human neointimal lesions is consistent with such a protective role. Cell cycle progression is facilitated by cyclinE/CDK2-dependent phosphorylation of p27 on threonine 187 (T187) during late G1. The purpose of this study was to assess whether this phosphorylation event plays a role during atherosclerosis. To this end, we generated apolipoprotein E-null mice with both p27 alleles replaced by a mutated form non-phosphorylatable at T187 (apoE-/-p27T187A mice) and investigated the kinetics of atheroma development in these animals compared to apoE-/- controls with an intact p27 gene. Fat feeding resulted in comparable level of hypercholesterolemia in both groups of mice. Surprisingly, aortic p27 expression was not increased in fat-fed apoE-/-p27T187A mice compared with apoE-/- controls. Moreover, atheroma size, lesion cellularity, proliferation, and apoptotic rates were undistinguishable in both groups of fat-fed mice. Thus, in contrast to previous studies that highlight the importance of p27 phosphorylation at T187 on the control of p27 expression and function in different tissues and pathophysiological scenarios, our findings demonstrate that this phosphorylation event is not implicated in the control of aortic p27 expression and atheroma progression in hypercholesterolemic mice.
authors.affiliation: Laboratory of Vascular Biology, Department of Molecular and Cellular Pathology and Therapy, Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas, Valencia, Spain.
authors.forename: Silvia M
authors.initials: SM
authors.lastname: Sanz-González
authors.forename: Raquel
authors.initials: R
authors.lastname: Melero-Fernández de Mera
authors.forename: Nisar P
authors.initials: NP
authors.lastname: Malek
authors.forename: Vicente
authors.initials: V
authors.lastname: Andrés
mesh_terms: D000818:Animals; D001011:Aorta / Q000378:metabolism* / Q000473:pathology; D001057:Apolipoproteins E / Q000235:genetics*; D017209:Apoptosis / Q000187:drug effects; D050197:Atherosclerosis / Q000378:metabolism* / Q000473:pathology; D001768:Blister / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002784:Cholesterol / Q000097:blood; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics* / Q000378:metabolism; D004033:Diet Fads; D005260:Female; D006937:Hypercholesterolemia / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010766:Phosphorylation; D013912:Threonine / Q000737:chemistry
chemical_list: D001057:Apolipoproteins E; D050760:Cyclin-Dependent Kinase Inhibitor p27; D013912:Threonine; D002784:Cholesterol