Objective To investigate the role and mechanism of myotubularin-related protein 7 (Mtmr7) in proliferation and migration of mouse vascular smooth muscle cells (VSMCs). Methods The mouse aortic smooth muscle cell line (MOVAS)was cultured. 30 ng/ml of platelet-derived growth factor-BB (PDGF-BB) was used to induce proliferation and migration of VSMCs in vitro. The changes of mRNA and protein expression levels after PDGF-BB intervention in Mtmr7 was assessed by qRT-PCR and Western blotting. To explore the role of Mtmr7 in proliferation and migration of mouse VSMCs, the adenovirus carrying Mtmr7(Ad-Mtmr7) was used to infect VSMCs for overexpression of Mtmr7. MOVAS was divided into control group, Ad-Mtmr7 group,PDGF-BB group and Ad-Mtmr7+PDGF-BB group. The proliferation capacity of VSMCs was analyzed by Ki-67 immunofluorescence staining and cell counting kit-8 (CCK-8) assay. The migration capacity was assessed by scratch assay. The downstream target protein levels of mammalian rapamycin target protein complex 1 (mTORC1) were determined by Western blotting. Insulin (5 mg/L)was used to restore the activity of mTORC1. MOVAS were divided into PDGF-BB group, Ad-Mtmr7+PDGF-BB group and Ad-Mtmr7+PDGF-BB+insulin group. The proliferation, migration and protein levels were measured by methods as the same mentioned above. A model of carotid endothelial injury was established. At 28 days after operation, the protein level of Mtmr7 was determined by Western blotting. The mice were randomly divided into 4 groups (10 each): sham group, sham+Ad-Mtmr7 group,carotid endothelial injury group and carotid injury+Ad-Mtmr7 group. To overexpress Mtmr7, Ad-Mtmr7 (5×10¹⁰ pfu/ml) was injected into the carotid artery immediately after operation and then partly incubated for 30 min. At 7th, 14th and 21st day after operation, the mice were injected the adenovirus via tail vein. Twenty-eight days after modeling, the morphology of carotid artery and the degree of intimal hyperplasia were analyzed by HE staining. Results Compared with control group, the mRNA and protein levels of Mtmr7 were obviously reduced (P<0.001 and P<0.05), the rate of Ki-67 positive cells and the relative number of VSMCs increased (P<0.01 and P<0.001), the rate of wound healing and the protein expression levels of p-S6^Ser235/236 and p-4EBP1^Thr37/46 increased (P<0.001 and P<0.05) in PDGF-BB group. Compared with the PDGF-BB group, the rate of Ki-67 positive cells, the relative number of VSMCs (P<0.01 or P<0.001), the rate of wound healing (P<0.001) and the protein levels of p-S6^Ser235/236 and p-4EBP1^Thr37/46 (P<0.05) were decreased in Ad-Mtmr7+PDGF-BB group. Compared with the Ad-Mtmr7+PDGF-BB group, the protein levels of p-S6^Ser235/236 and p-4EBP1^Thr37/46 (P<0.01), the rate of Ki-67 positive cells, the relative number of VSMCs (P<0.01 or P<0.001) and the rate of wound healing (P<0.01) were increased in Ad-Mtmr7+PDGF-BB+insulin group. Compared with the sham group, the protein expression level of Mtmr7 decreased significantly (P<0.01) and the ratio of intima/media area increased (P<0.001)in carotid endothelial injury group. Compared with the carotid endothelial injury group, after overexpression of Mtmr7, the ratio of intima/media area decreased significantly (P<0.01) in carotid endothelial injury+Ad-Mtmr7 group. Conclusion Overexpression of Mtmr7 may inhibit the proliferation and migration of VSMCs induced by PDGF-BB in mice, alleviating intimal hyperplasia after vascular injury, which is closely related to the mTORC1 activity reduced by Mtmr7.