Oxygen sensing by primary cardiac fibroblasts: a key role of p21(Waf1/Cip1/Sdi1).
In mammalian organs under normoxic conditions, O2 concentration ranges from 12% to <0.5%, with O2 approximately 14% in arterial blood and <10% in the myocardium. During mild hypoxia, myocardial O2 drops to approximately 1% to 3% or lower. In response to chronic moderate hypoxia, cells adjust their normoxia set point such that reoxygenation-dependent relative elevation of PO2 results in perceived hyperoxia. We hypothesized that O2, even in marginal relative excess of the PO2 to which cardiac cells are adjusted, results in activation of specific signal transduction pathways that alter the phenotype and function of these cells. To test this hypothesis, cardiac fibroblasts (CFs) isolated from adult murine ventricle were cultured in 10% or 21% O2 (hyperoxia relative to the PO2 to which cells are adjusted in vivo) and were compared with those cultured in 3% O2 (mild hypoxia). Compared with cells cultured in 3% O2, cells that were cultured in 10% or 21% O2 demonstrated remarkable reversible G2/M arrest and a phenotype indicative of differentiation to myofibroblasts. These effects were independent of NADPH oxidase function. CFs exposed to high O2 exhibited higher levels of reactive oxygen species production. The molecular signature response to perceived hyperoxia included (1) induction of p21, cyclin D1, cyclin D2, cyclin G1, Fos-related antigen-2, and transforming growth factor-beta1, (2) lowered telomerase activity, and (3) activation of transforming growth factor-beta1 and p38 mitogen-activated protein kinase. CFs deficient in p21 were resistant to such O2 sensitivity. This study raises the vital broad-based issue of controlling ambient O2 during the culture of primary cells isolated from organs.
Roy
Sashwati
S
Laboratory of Molecular Medicine, Department of Surgery, Davis Heart and Lung Research Institute, The Ohio State University Medical Center, Columbus 43210, USA.
Khanna
Savita
S
Bickerstaff
Alice A
AA
Subramanian
Sukanya V
SV
Atalay
Mustafa
M
Bierl
Michael
M
Pendyala
Srikanth
S
Levy
Dana
D
Sharma
Nidhi
N
Venojarvi
Mika
M
Strauch
Arthur
A
Orosz
Charles G
CG
Sen
Chandan K
CK
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D015687:Cell Hypoxia / Q000502:physiology*; D002469:Cell Separation; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000172:deficiency / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006352:Heart Ventricles / Q000166:cytology; D018496:Hyperoxia / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000502:physiology; D010100:Oxygen / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D019098:Telomerase / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D053773:Transforming Growth Factor beta1; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases
C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D017382:Reactive Oxygen Species; C508961:Tgfb1 protein, mouse; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D016159:Tumor Suppressor Protein p53; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D019098:Telomerase; D010100:Oxygen