Klf4, Klf2, and Zfp148 activate autophagy‐related genes in smooth muscle cells during aortic aneurysm formation

• Published in: Physiological reports 2019-04, Vol.7 (8), p.e14058-n/a
• Main Authors: Salmon, Morgan, Spinosa, Michael, Zehner, Zendra E., Upchurch, Gilbert R., Ailawadi, Gorav
• Format: Article
• Language: English
• Subjects: Aneurysms; Animals; Aorta; Aortic Aneurysm; Aortic Aneurysm - metabolism; Aortic aneurysms; Apoptosis; Atherosclerosis; Autophagy; Beclin-1 - genetics; Beclin-1 - metabolism; Cardiovascular Conditions, Disorders and Treatments; Cell death; Cells, Cultured; Cellular Physiology; Chromatin; Collagen; Cytokines; Disease control; Disease prevention; DNA-Binding Proteins - metabolism; Elastase; Homeostasis; Humans; Immunology; Immunoprecipitation; Inflammation; Injury prevention; Investigations; Klf2; Klf4; KLF4 protein; Krueppel-like factor; Kruppel protein; Kruppel-Like Factor 4; Kruppel-Like Transcription Factors - metabolism; Laboratory animals; Male; Mice; Microtubule-Associated Proteins - genetics; Microtubule-Associated Proteins - metabolism; Myocytes, Smooth Muscle - metabolism; Organelles; Original Research; Pancreas; Pancreatic elastase; Phagocytosis; Phenotypes; Physiology; Protein Binding; Proteins; Ramadan; Roles; siRNA; Smooth Muscle; smooth muscle cells; Transcription activation; Transcription factors; Transcription Factors - metabolism; Zfp148; Zinc finger proteins
• ISSN: 2051-817X
• DOI: 10.14814/phy2.14058

Abdominal aortic aneurysms (AAAs) are a progressive dilation of the aorta that is characterized by an initial influx of inflammatory cells followed by a pro‐inflammatory, migratory, proliferative, and eventually apoptotic smooth muscle cell phenotype. In recent years, the mechanisms related to the initial influx of inflammatory cells have become well‐studied; the mechanisms related to chronic aneurysm formation, smooth muscle cell apoptosis and death are less well‐characterized. Autophagy is a generally believed to be a protective cellular mechanism that functions to recycle defective proteins and cellular organelles to maintain cellular homeostasis. Our goal with the present study was to investigate the role of autophagy in smooth muscle cells during AAA formation. Levels of the autophagy factors, Beclin, and LC3 were elevated in human and mouse AAA tissue via both qPCR and immunohistochemical analysis. Confocal staining in human and mouse AAA tissue demonstrated Beclin and LC3 were present in smooth muscle cells during AAA formation. Treatment of smooth muscle cells with porcine pancreatic elastase or interleukin (IL)‐1β activated autophagy‐related genes in vitro while treatment with a siRNA to Kruppel‐like transcription factor 4 (Klf4), Kruppel‐like transcription factor 2 (Klf2) or Zinc‐finger protein 148 (Zfp148) separately inhibited activation of autophagy genes. Chromatin immunoprecipitation assays demonstrated that Klf4, Klf2, and Zfp148 separately bind autophagy genes in smooth muscle cells following elastase treatment. These results demonstrate that autophagy is an important mechanism related to Klfs in smooth muscle cells during AAA formation. These studies represent one mechanism for activation of autophagy during aortic aneurysm formation and suggest that KLF4 and ZNF148 may play a role. These studies suggest that part of the inflammatory process of aneurysm formation may be the activation of the autophagy process and support the importance of KLF4 and ZNF148 to inflammatory vascular diseases.