title: Contribution of p16INK4a and p21CIP1 pathways to induction of premature senescence of human endothelial cells: permissive role of p53.
abstract: We have previously found that nonenzymatically glycated collagen I (GC), mimicking diabetic microenvironment, can induce senescent phenotype in early passage human umbilical vein endothelial cells (HUVECs). In the present study, we explored the functional involvement of cell cycle checkpoint pathways in initiating GC-induced premature endothelial cell senescence. When compared with native collagen, early passage HUVECs showed increased p53, p21(CIP1) (p21), and p16(INK4a) (p16) mRNA expression after exposure to GC. Twenty-four hours after transfection of p16, p21, and p53-enhanced green fluorescent protein (EGFP) recombinant plasmids, HUVECs entered G(1)-phase cell cycle arrest. By days 3 and 5, HUVECs transfected with p16-EGFP showed an increased proportion of senescent cells, and this increase was more prominent in the GFP-positive cell population, which exhibited 68% of senescent cells. Transfection of p21 also induced senescence but only by day 5. Cotransfection of p16 and p21 showed no additive effect. Transfection of p21 or p53 induced apoptosis in HUVECs. Next, we suppressed endogenous p53, p21, p16, or retinoblastoma (Rb) gene expression through small interference RNA strategy and investigated their influence in p16- and p21-initiated endothelial cell senescence. Analysis indicated that suppression of p53 expression can abolish senescence induced by p16 overexpression. Paradoxically, this effect was not observed when p21 was suppressed. On the other hand, suppression of Rb eliminated senescence initiated by either p16 or p21 overexpression. In summary, the p53/p21 pathway is mainly responsible for GC-induced apoptosis, but the coordinated activation of the p53/p21 and p16 pathway is responsible for GC-induced endothelial cell senescence through a Rb-dependent mechanism.
authors.affiliation: Department of Medicine, New York Medical College, Valhalla, NY 10595, USA. jun_chen@nymc.edu
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
authors.forename: Xuan
authors.initials: X
authors.lastname: Huang
authors.forename: Dorota
authors.initials: D
authors.lastname: Halicka
authors.forename: Sergey
authors.initials: S
authors.lastname: Brodsky
authors.forename: Ari
authors.initials: A
authors.lastname: Avram
authors.forename: Jonathan
authors.initials: J
authors.lastname: Eskander
authors.forename: Noah A
authors.initials: NA
authors.lastname: Bloomgarden
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Darzynkiewicz
authors.forename: Michael S
authors.initials: MS
authors.lastname: Goligorsky
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects / Q000502:physiology*; D024042:Collagen Type I / Q000494:pharmacology*; D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism*; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D051379:Mice; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D025803:Tumor Suppressor Protein p14ARF / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: C493957:Cdkn1a protein, mouse; C417743:Cdkn2a protein, mouse; D024042:Collagen Type I; D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21; D011994:Recombinant Proteins; C495901:TP53 protein, human; D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53