Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8321912 | The International Journal of Biochemistry & Cell Biology | 2018 | 31 Pages |
Abstract
Accumulation of senescent endothelial cells can contribute to endothelium dysfunction. Suppression of MTOR signaling has been shown to delay senescence but the mechanism that underpins this effect, particularly one that involves miRNAs, remains to be further defined. This study sought to identify miRNAs involved in MTORC1-mediated inhibition of replicative senescence in endothelial cells. Pre-senescent HUVECs were prolonged treated with low dose rapamycin (1â¯nM), an MTOR inhibitor. Rapamycin treatment down-regulated the phosphorylated MTOR, RPS6 and 4EBP1 expressions, which confirmed MTORC1 suppression. Prolonged low dose rapamycin treatment has significantly reduced the percentage of senescence-associated beta galactosidase (SA-β gal) positively stained senescent cells and P16INK4A expression in these cells. On the contrary, the percentage of BrdU-labelled proliferating cells has significantly increased. RPTOR, a positive regulator of MTORC1 was knockdown using RPTOR siRNA to inhibit MTORC1 activation. RPTOR knockdown was evidenced by significant suppressions of RPTOR mRNA and protein expression levels. In these cells, the expression of miR-107 was down-regulated whereas miR-145-5p and miR-217 were up-regulated. Target gene prediction revealed PTEN as the target of miR-107 and this was confirmed by biotin pull-down assay. Over-expression of miR-107 has decreased PTEN expression, increased MTORC1 activity, induced cell cycle arrest at G0/G1 phase and up-regulated P16INK4A expression but mitigated tube formation. Collectively, our findings revealed that delayed endothelial replicative senescence caused by the inhibition of MTORC1 activation could be modulated by miR-107 via its influence on PTEN.
Keywords
ECMeIF4E binding protein 1cyclin dependent kinase 6RPS64EBP1S6K1S6 kinase 1HUVECUTRmTORSDSBSACdk6bovine serum albuminRISCRapamycinsodium dodecyl sulfateHuman endothelial cellHuman umbilical vein endothelial cellphosphatase and tensin homologRNA-Induced Silencing Complexendothelial cell mediumUn-translated regionMicroRNAMiRNAmammalian target of rapamycinRibosomal protein S6Cellular senescencePten
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Authors
Eng-Soon Khor, Pooi-Fong Wong,