BACKGROUND/AIMS: Autophagy is an evolutionarily conserved mechanism that affects the survival and functions of vascular smooth muscle cells (VSMCs). We explored the role of microRNAs (miRNAs) in regulating autophagy in VSMCs exposed to high phosphorus (Pi) levels. METHODS: VSMCs were isolated from the thoracic aorta of rats and were cultured primarily. Real-time PCR was used to measure the mRNA expression of indicated genes. Western blotting was performed to detect the protein expression of autophagy-related markers. RESULTS: We found that treatment with high Pi levels (1 and 3 mM) activated LC3II expression and promoted autophagic flux in VSMCs. Conversely, treatment with an autophagy inhibitor decreased LC3II expression. Pi stimulation dysregulated the expression of several miRNAs such as miR-18a, miR-21, miR-23a, miR-30b, and miR-31a. However, miR-30b overexpression decreased Pi-induced expression of autophagy-related marker genes such as BECN1, ATG5, and LC3b, whereas miR-30b downregulation increased Pi-induced expression of these genes. In addition, we found that miR-30b directly targeted BECN1. CONCLUSIONS: These data suggest that miR-30b plays an important role in the regulation of high Pi level-induced autophagy in VSMCs by targeting BECN1.
BACKGROUND/AIMS: Autophagy is an evolutionarily conserved mechanism that affects the survival and functions of vascular smooth muscle cells (VSMCs). We explored the role of microRNAs (miRNAs) in regulating autophagy in VSMCs exposed to high phosphorus (Pi) levels. METHODS: VSMCs were isolated from the thoracic aorta of rats and were cultured primarily. Real-time PCR was used to measure the mRNA expression of indicated genes. Western blotting was performed to detect the protein expression of autophagy-related markers. RESULTS: We found that treatment with high Pi levels (1 and 3 mM) activated LC3II expression and promoted autophagic flux in VSMCs. Conversely, treatment with an autophagy inhibitor decreased LC3II expression. Pi stimulation dysregulated the expression of several miRNAs such as miR-18a, miR-21, miR-23a, miR-30b, and miR-31a. However, miR-30b overexpression decreased Pi-induced expression of autophagy-related marker genes such as BECN1, ATG5, and LC3b, whereas miR-30b downregulation increased Pi-induced expression of these genes. In addition, we found that miR-30b directly targeted BECN1. CONCLUSIONS: These data suggest that miR-30b plays an important role in the regulation of high Pi level-induced autophagy in VSMCs by targeting BECN1.