Background Abnormal regulation of vascular smooth muscle cells is regarded as the iconic pathological change of aortic dissection (AD). Herein, we aim to identify as a crucial regulator in AD. Methods and Results Microarray analysis of circular RNAs, messenger RNAs, and micro RNAs in patients with AD was performed, and we identified that was significantly downregulated in these patients. The Pearson correlation analysis uncovered the negative correlation between and or TGFβR1 (transforming growth factor beta receptor 1). Angiotensin II was used to treat human aortic vascular smooth muscle cells (HASMCs) and mice as models for AD. Hematoxylin and eosin and Masson's trichrome staining were used to analyze AD histopathology. Cell proliferation was analyzed with Cell Counting Kit-8 assay and EdU incorporation. Cell migration was assessed with transwell and wound healing assays. Enhanced expression dramatically inhibited HASMC proliferation and migration and maintained contractile marker expression induced by angiotensin II, whereas exerted opposite effects. was a target of . targeted IRF1 (interferon regulatory factor 1) and thus negatively regulated TGFβR1 expression to promote HASMC proliferation and migration and inhibit contractile marker expression. suppressed the progression of AD in vivo. Conclusions modulates the contractile phenotype of HASMCs via regulating the -IRF1-TGFβR1 axis in angiotensin II-induced models for AD, which provides potential therapeutic targets for AD.