Abstract：
OBJECTIVE: Myotubularin-related protein 7 (MTMR7) suppresses proliferation in various cell types and is associated with cardiovascular and cerebrovascular diseases. However, whether MTMR7 regulates vascular smooth muscle cell (VSMC) and vascular intimal hyperplasia remains unclear. We explored the role of MTMR7 in phenotypic switching of VSMC and vascular intimal hyperplasia after injury.
RESULTS: MTMR7 expression was significantly downregulated in injured arteries. Compared to wild type (WT) mice, Mtmr7-transgenic (Mtmr7-Tg) mice showed reduced intima/media ratio, decreased percentage of Ki-67-positive cells within neointima, and increased Calponin expression in injured artery. In vitro, upregulating MTMR7 by Len-Mtmr7 transfection inhibited platelet derived growth factor (PDGF)-BB-induced proliferation, migration of VSMC and reversed PDGF-BB-induced decrease in expression of Calponin and SM-MHC. Microarray, single cell sequence, and other bioinformatics analysis revealed that MTMR7 is highly related to glucose metabolism and mammalian target of rapamycin complex 1 (mTORC1). Further experiments confirmed that MTMR7 markedly repressed glycolysis and mTORC1 activity in PDGF-BB-challenged VSMC in vitro. Restoring mTORC1 activity abolished MTMR7-mediated suppression of glycolysis, phenotypic shift in VSMC in vitro and protection against vascular intimal hyperplasia in vivo. Furthermore, upregulating MTMR7 in vitro led to dephosphorylation and dissociation of p62 from mTORC1 in VSMC. External expression of p62 in vitro also abrogated the inhibitory effects of MTMR7 on glycolysis and phenotypic switching in PDGF-BB-stimulated VSMC.
CONCLUSIONS: Our study demonstrates that MTMR7 inhibits injury-induced vascular intimal hyperplasia and phenotypic switching of VSMC. Mechanistically, the beneficial effects of MTMR7 are conducted via suppressing p62/mTORC1-mediated glycolysis.
RESULTS: MTMR7 expression was significantly downregulated in injured arteries. Compared to wild type (WT) mice, Mtmr7-transgenic (Mtmr7-Tg) mice showed reduced intima/media ratio, decreased percentage of Ki-67-positive cells within neointima, and increased Calponin expression in injured artery. In vitro, upregulating MTMR7 by Len-Mtmr7 transfection inhibited platelet derived growth factor (PDGF)-BB-induced proliferation, migration of VSMC and reversed PDGF-BB-induced decrease in expression of Calponin and SM-MHC. Microarray, single cell sequence, and other bioinformatics analysis revealed that MTMR7 is highly related to glucose metabolism and mammalian target of rapamycin complex 1 (mTORC1). Further experiments confirmed that MTMR7 markedly repressed glycolysis and mTORC1 activity in PDGF-BB-challenged VSMC in vitro. Restoring mTORC1 activity abolished MTMR7-mediated suppression of glycolysis, phenotypic shift in VSMC in vitro and protection against vascular intimal hyperplasia in vivo. Furthermore, upregulating MTMR7 in vitro led to dephosphorylation and dissociation of p62 from mTORC1 in VSMC. External expression of p62 in vitro also abrogated the inhibitory effects of MTMR7 on glycolysis and phenotypic switching in PDGF-BB-stimulated VSMC.
CONCLUSIONS: Our study demonstrates that MTMR7 inhibits injury-induced vascular intimal hyperplasia and phenotypic switching of VSMC. Mechanistically, the beneficial effects of MTMR7 are conducted via suppressing p62/mTORC1-mediated glycolysis.
摘要：
目的：肌管蛋白相关蛋白7（MTMR7）抑制各种细胞类型的增殖，并与心脑血管疾病有关。然而,MTMR7是否调节血管平滑肌细胞(VSMC)和血管内膜增生尚不清楚.我们探讨了MTMR7在损伤后VSMC表型转换和血管内膜增生中的作用。
结果：MTMR7表达在损伤的动脉中显著下调。与野生型（WT）小鼠相比，Mtmr7转基因（Mtmr7-Tg）小鼠显示内膜/中膜比例降低，新内膜内Ki-67阳性细胞的百分比降低，并且在损伤的动脉中增加了Calponin的表达。体外，通过Len-Mtmr7转染上调MTMR7抑制血小板源性生长因子（PDGF）-BB诱导的增殖，VSMC的迁移和逆转的PDGF-BB诱导的Calponin和SM-MHC表达降低。微阵列,单细胞序列，等生物信息学分析显示,MTMR7与葡萄糖代谢和哺乳动物雷帕霉素靶蛋白复合物1(mTORC1)高度相关。进一步的实验证实,MTMR7在体外显著抑制PDGF-BB攻击的VSMC中的糖酵解和mTORC1活性。恢复mTORC1活性消除了MTMR7介导的糖酵解抑制，体外VSMC的表型转变和体内对血管内膜增生的保护。此外，在体外上调MTMR7导致p62从VSMC中的mTORC1去磷酸化和解离。体外p62的外部表达也消除了MTMR7对PDGF-BB刺激的VSMC中糖酵解和表型转换的抑制作用。
结论：我们的研究表明，MTMR7抑制损伤诱导的血管内膜增生和VSMC的表型转换。机械上,MTMR7的有益作用是通过抑制p62/mTORC1介导的糖酵解来进行的。
结果：MTMR7表达在损伤的动脉中显著下调。与野生型（WT）小鼠相比，Mtmr7转基因（Mtmr7-Tg）小鼠显示内膜/中膜比例降低，新内膜内Ki-67阳性细胞的百分比降低，并且在损伤的动脉中增加了Calponin的表达。体外，通过Len-Mtmr7转染上调MTMR7抑制血小板源性生长因子（PDGF）-BB诱导的增殖，VSMC的迁移和逆转的PDGF-BB诱导的Calponin和SM-MHC表达降低。微阵列,单细胞序列，等生物信息学分析显示,MTMR7与葡萄糖代谢和哺乳动物雷帕霉素靶蛋白复合物1(mTORC1)高度相关。进一步的实验证实,MTMR7在体外显著抑制PDGF-BB攻击的VSMC中的糖酵解和mTORC1活性。恢复mTORC1活性消除了MTMR7介导的糖酵解抑制，体外VSMC的表型转变和体内对血管内膜增生的保护。此外，在体外上调MTMR7导致p62从VSMC中的mTORC1去磷酸化和解离。体外p62的外部表达也消除了MTMR7对PDGF-BB刺激的VSMC中糖酵解和表型转换的抑制作用。
结论：我们的研究表明，MTMR7抑制损伤诱导的血管内膜增生和VSMC的表型转换。机械上,MTMR7的有益作用是通过抑制p62/mTORC1介导的糖酵解来进行的。
