Data Availability StatementAll data generated or analyzed during this study are included in this published article. growth, reduced the number of invasive cells and decreased the percentage cells in the G1 phase. Autophagy of HASMCs was inhibited following Rab7 knockdown. Inhibition of autophagy with 3-methyladenine or Rab7 knockdown suppressed the phenotypic conversion of contractile to synthetic HASMCs. TUG-891 The action of Rab7 may be mediated by inhibiting the Ras/Raf/mitogen-activated protein kinase (MAPK) kinase (MEK)/extracellular signal related kinase (ERK) signaling pathway. In conclusion, the results revealed that Rab7-mediated autophagy regulated the behavior of SMCs and the phenotypic transformations in AD via activation of the Ras/Raf/MEK/ERK signaling pathway. The findings of the present study may improve understanding of the role Rab7 in the molecular etiology of AD and suggests the application of Rab7 as a novel therapeutic target in the treatment of human AD. strong class=”kwd-title” Keywords: Rab7, phenotypic transformation, smooth muscle cells, autophagy, extracellular signal-regulated kinase Introduction Acute aortic dissection (AAD) is a common and critical clinical disease with a high rate of mortality; however, its pathogenetic mechanism requires further investigation. Recent studies suggested that AAD arises from problems with vascular function. It is well established that TUG-891 vascular smooth muscle cells (VSMCs) are essential regulators of vascular function (1). VSMCs are located in the middle vascular layer of healthy arteries (2C4), where they secrete vasoconstrictor proteins that help regulate blood vessel tension and blood flow (5). VSMCs are TUG-891 the most important component of the vascular middle layer and may contribute to AAD. VSMCs are divided into two cell phenotypes: Contractile and synthetic (6,7). Fusiform contractile VSMCs demonstrate difficulty in secreting extracellular matrix proteins, and exhibit poor proliferation and migration (8). The proliferative and migration abilities of synthetic VSMCs are enhanced compared with the systolic VSMCs (9C11). Synthetic VSMCs secrete a variety of extracellular matrix components, including collagen, elastin and proteoglycans (12,13). Upon atherosclerosis and arterial restenosis, VSMCs undergo a transformation from the contractile to the synthetic phenotype (14). This transformation promotes the migration of SMCs into the intima, enhances proliferation and promotes the secretion of extracellular proteins (15). These phenotypic transformations may underlie the basis of regulating the composition and stability of blood vessels, which may eventually lead to the formation of vascular lesions (16). Recent studies revealed that extracellular factors and downstream signaling pathways participate in transformation of VSMCs (17,18), such as autophagy. It was demonstrated that Rab7 participates in the regulation of VSMC proliferation and migration (2). Autophagy, induced by platelet-derived growth factor, serves an important role in the process of transforming the phenotype of VSMCs from a contractile to a synthetic form by preventing oxidative stress-induced cell death (19). Rab proteins are Ras-related small GTPases, which regulate exo- and endocytic membrane trafficking by vesicle docking and fusion (20). As an important member of the Rab GTPase superfamily, Rab7 promotes lysosomal biosynthesis and maintains lysosomal function (21,22). Furthermore, Rab7 serves a pivotal role in the fusion of vesicles and lysosomes, and exhibit an important effect on autophagosome maturation (23). Abnormal expression or alterations in the activity of Rab7 may be associated with cardiovascular diseases, lipid storage disorders and neurodegenerative diseases (24C27). Therefore, the present study hypothesized that phenotypic transformation regulated by Rab7-mediated autophagy may be associated with VSMC proliferation and invasion. In the present study, DFNB53 AD VSMCs were treated with small interfering (si)RNA or Rab7 overexpression plasmid to assess phenotypic transformations and cellular behavior, including proliferation, invasion, cell cycle and autophagy. The present study aimed to identify the effects of Rab7 on autophagy in VSMCs and determine whether -Rab7-regulated autophagy results in the alteration of VSMC phenotype and cell behavior. Materials and methods Tissue sampling A total of 51 AAD tissues were obtained from patients with type A AD, who underwent aortic replacement operations at The First Affiliated Hospital of Nanjing Medical University (Nanjing, China) between October 2015 and October 2017 (Ethics no. 2016-SR-144). The main clinicopathological characteristics of the patients are shown in Table I. All experimental protocols.