| Gene name: | CD9 |
| Aging type: | Accelerate |
| Aging characteristic: |
| Tissue type: | -- |
| Cell name: | HUVEC |
| Experiment: | Cell transfection//SA-β-gal activity assay//Flow cytometry//Western blot |
| Description: | To examine the roles of CD9 in endothelial cell senescence, we measured the effects of CD9 knockdown in senescent HUVECs (PD>50). Knockdown of CD9 in senescent cells with siRNA reduced the p53 and p21 levels, representative senescence markers, and the pAKT and pS6K levels, decreased SAβG staining, and caused morphological changes similar to those observed in young cells. CD9 downregulation increased cell proliferation, BrdU incorporation, and Ki67 immunoreactivity, which are all well-known cell proliferation markers. CD9 knockdown decreased the G0/G1 cell population and increased the S and G2/M cell population, suggesting a release of G1 arrest, which is a typical phenotype in cellular senescence Young cells transduced with CD9 adenovirus were enlarged and flattened. Moreover, CD9 upregulation increased SAβG staining, but decreased BrdU incorporation, Ki67 immunoreactivity, the proportion of cells in the S phase, and endothelial tube formation. |
| Regulatory pathway: | PI3K-AKT-MTOR-P53 |
| R-AG-Pathway: | Activation |
| Pathway experiment: | Cell transfection//SA-β-gal activity assay//Flow cytometry//Western blot |
| Pathway description: | Therefore, we tested whether the PI3K/AKT-mTOR pathway plays a role in CD9-induced senescence. Pretreatment with LY294002, a specific inhibitor of PI3K, or rapamycin, an inhibitor of mTOR, reduced the levels of p53 and p21 and SA-β-gal staining induced by CD9 overexpression. We next tested whether PIK3CA 110β or PIK3CB 110β, two PI3K catalytic subunits, plays a role in CD9-induced senescence. Knockdown of PIK3CA, but not that of PIK3CB, significantly decreased the levels of pAKT, p53, p-p53, pS6K, and p21 proteins, as well as SA-β-gal staining, suggesting that PIK3CA might be involved in CD9-induced cellular senescence. These results indicate that the PI3K-AKT-mTOR-p53 pathway might regulate CD9-mediated cellular senescence. |
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