The NADPH oxidase Nox4 restricts the replicative lifespan of human endothelial cells.
The free radical theory of aging proposes that ROS (reactive oxygen species) are major driving forces of aging, and are also critically involved in cellular senescence. Besides the mitochondrial respiratory chain, alternative sources of ROS have been described that might contribute to cellular senescence. Noxs (NADPH oxidases) are well-known sources of superoxide, which contribute to the antimicrobial capabilities of macrophages, a process involving the prototypical member of the family referred to as Nox2. However, in recent years non-phagocytic homologues of Nox2 have been identified that are involved in processes other than the host defence. Superoxide anions produced by these enzymes are believed to play a major role in signalling by MAPKs (mitogen-activated protein kinases) and stress-activated kinases, but could also contribute to cellular senescence, which is known to involve oxygen radicals. In HUVECs (human umbilical vein endothelial cells), Nox4 is predominantly expressed, but its role in replicative senescence of HUVECs remains to be elucidated. Using shRNA (small-hairpin RNA)-mediated knockdown of Nox4, implicating lentiviral vectors, we addressed the question of whether lifelong depletion of Nox4 in HUVECs would influence the senescent phenotype. We found a significant extension of the replicative lifespan of HUVECs upon knockdown of Nox4. Surprisingly, mean telomere length was significantly reduced in Nox4-depleted cells. Nox4 depletion had no discernable influence on the activity of MAPKs and stress-activated kinases, but reduced the degree of oxidative DNA damage. These results suggest that Nox4 activity increases oxidative damage in HUVECs, leading to loss of replicative potential, which is at least partly independent of telomere attrition.
Lener
Barbara
B
Institute for Biomedical Aging Research, Austrian Academy of Sciences, Rennweg 10, A-6020 Innsbruck, Austria.
Kozieł
Rafał
R
Pircher
Haymo
H
Hütter
Eveline
E
Greussing
Ruth
R
Herndler-Brandstetter
Dietmar
D
Hermann
Martin
M
Unterluggauer
Hermann
H
Jansen-Dürr
Pidder
P
D002478:Cells, Cultured; D016922:Cellular Senescence; D004249:DNA Damage; D042783:Endothelial Cells / Q000201:enzymology*; D055785:Gene Knockdown Techniques; D006801:Humans; D020935:MAP Kinase Signaling System; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D000074662:NADPH Oxidase 2; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D013481:Superoxides / Q000378:metabolism; D016615:Telomere / Q000235:genetics / Q000378:metabolism*
D008562:Membrane Glycoproteins; D013481:Superoxides; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C498910:NOX4 protein, human
Nat Rev Cancer. 2008 Jul;8(7):512-22
18574463
Proc Natl Acad Sci U S A. 1994 May 10;91(10):4130-4
8183882
Biofactors. 2003;17(1-4):287-96
12897450
Jpn J Infect Dis. 2004 Oct;57(5):S28-9
15507765
Vet Immunol Immunopathol. 2007 Jan 15;115(1-2):107-25
17067684
J Hypertens. 2005 Jan;23(1):97-104
15643130
Trends Cardiovasc Med. 2008 Jan;18(1):15-9
18206804
Proc Natl Acad Sci U S A. 2001 Feb 27;98(5):2278-83
11226230
J Biol Chem. 2005 Sep 9;280(36):31859-69
15994299
Exp Gerontol. 2006 Jun;41(6):648-51
16677791
Science. 2005 Jun 24;308(5730):1909-11
15879174
Rejuvenation Res. 2008 Apr;11(2):449-53
18171112
J Cell Sci. 2004 May 1;117(Pt 11):2417-26
15126641
Ann N Y Acad Sci. 2000 Jun;908:111-25
10911952
Antioxid Redox Signal. 2008 Oct;10(10):1687-98
18593227
Mech Ageing Dev. 2005 Jun-Jul;126(6-7):813-21
15888336
J Biol Chem. 2002 May 31;277(22):19952-60
11893732
Exp Gerontol. 2003 Oct;38(10):1149-60
14580868
IUBMB Life. 2005 Apr-May;57(4-5):277-81
16036611
Exp Cell Res. 1995 Sep;220(1):186-93
7664835
Arch Gerontol Geriatr. 1991 Mar-Jun;12(2-3):99-117
15374442
PLoS Biol. 2007 May;5(5):e110
17472436
Antioxid Redox Signal. 2006 Sep-Oct;8(9-10):1473-84
16987004
Curr Opin Cell Biol. 2007 Apr;19(2):238-45
17303408
Free Radic Biol Med. 2007 Sep 15;43(6):947-58
17697939
Arch Biochem Biophys. 2004 Feb 15;422(2):197-210
14759608
Exp Cell Res. 2006 Apr 1;312(6):746-59
16388800
Antioxid Redox Signal. 2008 Mar;10(3):559-74
18092937
Arterioscler Thromb Vasc Biol. 2000 Apr;20(4):940-8
10764657
J Gerontol A Biol Sci Med Sci. 2000 Jan;55(1):B5-9
10719757
Mech Ageing Dev. 2008 Jan-Feb;129(1-2):3-10
18215413
Anal Biochem. 1998 Jan 1;255(1):20-31
9448838
Science. 1994 Feb 25;263(5150):1128-30
8108730
EMBO J. 2005 Apr 6;24(7):1311-7
15775985
Oncogene. 2006 Jun 22;25(26):3699-707
16532036
J Biol Chem. 1998 Jun 12;273(24):15022-9
9614110
Biochem J. 2004 Jun 15;380(Pt 3):919-28
15018610
Free Radic Biol Med. 2009 Jun 15;46(12):1598-606
19328228
Free Radic Biol Med. 2008 Nov 1;45(9):1340-51
18760347
Proc Natl Acad Sci U S A. 2000 Jul 5;97(14):8010-4
10869423
Biogerontology. 2007 Aug;8(4):383-97
17377850
Arterioscler Thromb Vasc Biol. 2007 Aug;27(8):1736-43
17541028
Arch Biochem Biophys. 2002 Jan 15;397(2):342-4
11795892
Mol Biol Cell. 2006 Sep;17(9):3978-88
16775014
Biochem J. 2004 Jul 1;381(Pt 1):231-9
15027896
Free Radic Biol Med. 2002 Sep 1;33(5):575-86
12208343
J Biol Chem. 2008 Jun 20;283(25):16961-5
18420576
Nucleic Acids Res. 1998 Aug 15;26(16):3651-6
9685479
Antioxid Redox Signal. 2003 Dec;5(6):803-11
14588154
Nucleic Acids Res. 2008 Oct;36(17):5678-94
18772227
Exp Gerontol. 2006 Jan;41(1):103-9
16309877
Hypertens Res. 2007 Nov;30(11):1119-28
18250561