MiR-182/Sestrin2 affects the function of asthmatic airway smooth muscle cells by the AMPK/mTOR pathway.

Background and objectives: Asthma is a chronic inflammatory airway disease and brings heavy economic and spiritual burdens to patients' families and the society. Airway smooth muscle cells (ASMCs) afect the development of asthma by secreting cytokines, growth factors, and prostates. The stress-inducing protein, Sestrin2, plays a vital role in antioxidant defense. The aim of this study is to investigate the role of Sestrin2 in asthma and its corresponding molecular mechanism.

Materials and methods: Airway remodeling was induced by construction of asthma rat model. Primary ASMCs were isolated through combining tissue block adherence and enzymatic digestion and identified by immunofluorescence staining. Gene expression was measured by quantitative real-time PCR (qPCR) and western blot (WB) experiments. Cell viability, proliferation, migration, and calcium flow of ASMCs were measured by Cell Counting Kit-8 (CCK-8), 5-ethynyl-deoxyuridine (EdU), Transwell, and Fluo-3AM, respectively. The binding of miR-182 and Sestrin2 3'-untranslated region (3'-UTR) was measured by luciferase reporter system and RNA-binding protein immunoprecipitation (RIP) analysis.

Results: Sestrin2 expression was upregulated in asthma rat model and cell model. Overexpression of Sestrin2 enhanced the growth, migration, and calcium flow, and inversely, repression of Sestrin2 was reduced in ASMCs from the asthma group. MiR-182, one of the microRNAs (miRNAs) that possesses the potential to regulate Sestrin2, was downregulated in ASMCs from the asthma group. Further experiments revealed that Sestrin2 was inhibited by miR-182 and that overexpression of Sestrin2 reversed the miR-182-induced inhibition of the cellular progression of ASMCs from the asthma group. This study further investigated the downstream signaling pathway of Sestrin2 and found that increased expression of Sestrin2 activated 5'-adenosine monophosphate-activated protein kinase (AMPK), leading to the inactivation of mammalian target of rapamycin (mTOR) and thus promoting the growth, migration, and calcium flow of ASMCs from the asthma group.

Conclusion: This study investigated the role of Sestrin2 for the first time and further dissected the regulatory factor of Sestrin2, ultimately elucidating the downstream signaling pathway of Sestrin2 in asthma, providing a novel pathway, and improving the understanding of the development and progression of asthma.