MiR-3571 Modulates Traumatic Brain Injury by Regulating the PI3K/AKT Signaling Pathway Via Fbxo31

To investigate the effect of miR-3571 on traumatic brain injury (TBI) via the regulation of neuronal apoptosis through F-box-only protein 31/phosphoinositide 3-kinase/protein kinase B (Fbxo31/PI3K/AKT). We established TBI rat and cell models. Hematoxylin‒eosin (HE) and Nissl staining were used to observe brain injury and the number of Nissl bodies, respectively. Cell proliferation and apoptosis were assessed by 5-ethynyl-2'-deoxyuridine (EdU), terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL), and flow cytometry. Gene and protein expression was measured via reverse transcription quantitative polymerase chain reaction (RT‒qPCR), Western blotting, and enzyme-linked immunosorbent assay (ELISA). In this study, miR-3571 was highly expressed in TBI models. Inhibition of miR-3571 expression can suppress autophagy, reduce the expression of proinflammatory cytokines, and reduce neuronal apoptosis, thus alleviating the pathological conditions of tissue congestion, edema and structural damage after TBI. These experiments demonstrated that miR-3571 could target and regulate the level of Fbxo31. Knockdown of Fbxo31 weakened the remission effect of the miR-3571 inhibitor on TBI and promoted neurological damage; moreover, overexpression of Fbxo31 enhanced the protective effect on neural function, whereas the PI3K/AKT pathway inhibitor LY294002 increased the damage caused by miR-3571 on neural function and weakened the protective effect of Fbxo31. In conclusion, miR-3571 regulates the PI3K/AKT signaling pathway by reducing Fbxo31 expression, promotes neuronal apoptosis and exacerbates TBI.