Endothelial cells isolated from caveolin-2 knockout mice display higher proliferation rate and cell cycle progression relative to their wild-type counterparts.
The goal of this study was to determine whether caveolin-2 (Cav-2) is capable of controlling endothelial cell (EC) proliferation in vitro. To realize this goal, we have directly compared proliferation rates and cell cycle-associated signaling proteins between lung ECs isolated from wild-type (WT) and Cav-2 knockout (KO) mice. Using three independent proliferation assays, we have determined that Cav-2 KO ECs proliferate by ca. 2-fold faster than their WT counterparts. Cell cycle analysis by flow cytometry of propidium iodide-stained cells showed a relatively higher percentage of Cav-2 KO ECs in S and G(2)/M and lower percentage in G(o)/G(1) phases of cell cycle relative to their WT counterparts. Furthermore, an over 2-fold increase in the percentage of S phase-associated Cav-2 KO relative to WT ECs was independently determined with bromodeoxyuridine incorporation assay. Mechanistically, the increase in proliferation/cell cycle progression of Cav-2 KO ECs correlated well with elevated expression levels of predominantly S phase- and G(2)/M phase-associated cyclin A and B1, respectively. Further mechanistic analysis of molecular events controlling cell cycle progression revealed increased level of hyperphosphorylated (inactive) form of G(1) to S phase transition inhibitor, the retinoblastoma protein in hyperproliferating Cav-2 KO ECs. Conversely, the expression level of the two cyclin-dependent kinase inhibitors p16(INK4) and p27(Kip1) was reduced in Cav-2 KO ECs. Finally, increased phosphorylation (activation) of proproliferative extracellular signal-regulated kinase 1/2 was observed in hyperproliferating Cav-2 KO ECs. Overall, our data suggest that Cav-2 negatively regulates lung EC proliferation and cell cycle progression.
Xie
Leike
L
Dept. of Medical Pharmacology and Physiology, Univ. of Missouri, 1 Hospital Drive, Rm. MA 415, Columbia, MO 65212, USA.
Frank
Philippe G
PG
Lisanti
Michael P
MP
Sowa
Grzegorz
G
D000818:Animals; D051243:Caveolin 2 / Q000172:deficiency* / Q000235:genetics; D002453:Cell Cycle; D049109:Cell Proliferation; D002478:Cells, Cultured; D019925:Cyclin A / Q000378:metabolism; D056744:Cyclin B1 / Q000378:metabolism; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism; D050760:Cyclin-Dependent Kinase Inhibitor p27; D042783:Endothelial Cells / Q000378:metabolism*; D005434:Flow Cytometry; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008168:Lung / Q000098:blood supply; D051379:Mice; D018345:Mice, Knockout; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010766:Phosphorylation; D016160:Retinoblastoma Protein / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors
C436291:CDKN1B protein, human; C495545:Cav2 protein, mouse; D051243:Caveolin 2; C534700:Ccnb1 protein, mouse; C417743:Cdkn2a protein, mouse; D019925:Cyclin A; D056744:Cyclin B1; D019941:Cyclin-Dependent Kinase Inhibitor p16; D047908:Intracellular Signaling Peptides and Proteins; D016160:Retinoblastoma Protein; D050760:Cyclin-Dependent Kinase Inhibitor p27; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3