miR-21 is upregulated, promoting fibrosis and blocking G2/M in irradiated rat cardiac fibroblasts

• Published in: PeerJ (San Francisco, CA) CA), 2020-12, Vol.8, p.e10502, Article e10502
• Main Authors: Guo, Huan, Zhao, Xinke, Su, Haixiang, Ma, Chengxu, Liu, Kai, Kong, Shanshan, Liu, Kedan, Li, Haining, Chang, Juan, Wang, Tao, Guo, Hongyun, Wei, Huiping, Fu, Zhaoyuan, Lv, Xinfang, Li, Yingdong
• Format: Article
• Language: English
• Subjects: Animal welfare; Apoptosis; Bioinformatics; Cardiology; Cardiomyocytes; Cardiovascular disease; Cell Biology; Cell cycle; Cell death; Drug dosages; Extracellular matrix; Fibroblasts; Fibrosis; Gene expression; Genes; Genomics; Health aspects; Heart; Ionizing radiation; Laboratory animals; miRNA; Morbidity; Post-irradiation; Radiation (Physics); Radiology and Medical Imaging; S phase; Structure-function relationships
• ISSN: 2167-8359; 2167-8359
• DOI: 10.7717/peerj.10502

Radiation exposure of the thorax is associated with a greatly increased risk of cardiac morbidity and mortality even after several decades of advancement in the field. Although many studies have demonstrated the damaging influence of ionizing radiation on cardiac fibroblast (CF) structure and function, myocardial fibrosis, the molecular mechanism behind this damage is not well understood. miR-21, a small microRNA, promotes the activation of CFs, leading to cardiac fibrosis. miR-21 is overexpressed after irradiation; however, the relationship between increased miR-21 and myocardial fibrosis after irradiation is unclear. This study was conducted to investigate gene expression after radiation-induced CF damage and the role of miR-21 in this process in rats. We sequenced irradiated rat CFs and performed weighted correlation network analysis (WGCNA) combined with differentially expressed gene (DEG) analysis to observe the effect on the expression profile of CF genes after radiation. DEG analysis showed that the degree of gene changes increased with the radiation dose. WGCNA revealed three module eigengenes (MEs) associated with 8.5-Gy-radiation-the Yellow, Brown, Blue modules. The three module eigengenes were related to apoptosis, G2/M phase, and cell death and S phase, respectively. By blocking with the cardiac fibrosis miRNA miR-21, we found that miR-21 was associated with G2/M blockade in the cell cycle and was mainly involved in regulating extracellular matrix-related genes, including , , , , and . Stem-loop quantitative real-time PCR was performed to verify the expression of these genes. Five genes showed higher expression after 8.5 Gy-radiation in CFs. The target genes of miR-21 predicted online were and , which showed much higher expression after treatment with antagomir-miR-21 in 8.5-Gy-irradiated CFs. Thus, miR-21 may play the role of fibrosis and G2/M blockade in regulating , , , , , and post-irradiation.