Objective: To investigate the effect and mechanism of mammalian target of rapamycin complex 1（mTORC1）on the stability of microtubules in Hela cells. Methods: Hela cells was pretreated with rapamycin（50 nmol/L）for 24 hours, then treated with Nocodazole（5 μmol）for 30, 60 or 120 minutes, the stability of microtubule protein was detected by immunofluorescence. Hela cells was treated with rapamycin(50 nmol/L) for 24 hours, the expression of microtubule depolymerizing protein stathmin, KIF2A, microtubule polymerizing protein CLIP170, microtubule cutting protein Katanin and Spastin were detected by Western blotting. The stability of microtubule protein was detected by immunofluorescence after autophagy related gene 5 (ATG5) was inhibited by ATG5-shRNA. Hela cells was pretreated with rapamycin(50 nmol/L) for 24 hours, the expression of Ras homologous gene family member A (RhoA) was detected by Western blotting; the stability of microtubules was examined by immunofluorescence after transfection with GFP RhoA-Q63l or GFP RhoA-N19, P190RhoGAP-siRNA plasmids. Results: Inhibiting the activity of mTORC1 with rapamycin significantly enhanced the stability of microtubules through resisting depolymerization while the stathmin, KIF2A, CLIP170, Katanin and Spastin expression were not changed.The stability of microtubules mediated by mTORC1 was independent on the autophagy. After the activity of mTORC1 was inhibited by rapamycin, the activation of RhoA GTP was down-regulated and the stability of microtubule was attenuated along with decreased activation of P190 RhoGAP. Conclusion: mTORC1 regulated the stability of microtubules through  RhoA pathway in Hela cells.

［Key words］mTORC1; microtubules; RhoA; autophagy； Hela cells