MiR-21 promotes ECM degradation through inhibiting autophagy via the PTEN/akt/mTOR signaling pathway in human degenerated NP cells.

Schematic presentation of ECM degradation induced by miR-21 in human degenerated NP cells. The binding of miR-21 to PTEN mRNA 3'-UTR can significantly downregulate PTEN expression, which leads to the sequential Akt and mTOR phosphorylation. Activated Akt/mTOR pathway strongly reduces autophagy levels in human degenerative NP cells, which in turn increases the expression of MMP-3 and MMP-9 and facilitates the degradation of Col II and aggrecan. P: phosphorylation.