p21<sup>WAF1</sup> and hypoxia/reoxygenation-induced premature senescence of H9c2 cardiomyocytes
We have previously reported on hypoxia/reoxygenation-induced premature senescence in neonatal rat cardiomyocytes. In this research, we investigated the effects of p21<sup>WAF1</sup> (p21) in hypoxia/reoxygenation-induced senescence, using H9c2 cells. A plasmid overexpress...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Via Medica
2011-10-01
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| Series: | Folia Histochemica et Cytobiologica |
| Subjects: | |
| Online Access: | http://czasopisma.viamedica.pl/fhc/article/view/9439 |
| Summary: | We have previously reported on hypoxia/reoxygenation-induced premature senescence in neonatal rat cardiomyocytes. In this research, we investigated the effects of p21<sup>WAF1</sup> (p21) in hypoxia/reoxygenation-induced senescence, using H9c2 cells. A plasmid overexpressing wild type p21<sup>WAF1</sup> and a plasmid expressing small hairpin RNA (shRNA) targeting p21<sup>WAF1</sup> were constructed, and transfected into H9c2 cells to control the p21 expression. Hypoxia/reoxygenation conditions were 1% O2 and 5% CO<sub>2</sub>, balancing the incubator chamber with N<sub>2</sub> for 6 h (hypoxia 6 h), then 21% oxygen for 8 h (reoxygenation 8 h). Cell cycle was examined using flow cytometry. Senescence was assessed using <i>&#946;</i>-galactosidase staining. The expression of p53, p21, p16<sup>INK4a</sup>, and cyclin D1 was assayed using Western blotting. At hypoxia 6 h, cells overexpressing p21 had a larger G1 distribution, stronger <i>&#946;</i>-galactosidase activity, and lower cyclin D1 expression compared to control cells, while the opposite results and higher p53 expression were obtained in p21-knockdown cells. At reoxygenation 8 h, p21-silenced cells had a smaller percentage of G1 cells, weaker <i>&#946;</i>-galactosidase activity and lower 16<sup>INK4a</sup> expression, and higher cyclin D1 expression, but the overexpression group showed no difference. Taken together, this data implies that p21<sup>WAF1</sup> is important for the hypoxia phase, but not the reoxygenation phase, in the H9c2 senescence process. (<i>Folia Histochemica et Cytobiologica 2011, Vol. 49, No. 3, 445&#8211;451</i>) |
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| ISSN: | 0239-8508 1897-5631 |