Upregulation of miR-20b Protects Against Cerebral Ischemic Stroke by Targeting Thioredoxin Interacting Protein (TXNIP)

Abstract

Dysregulation of microRNAs (miRNAs) is involved in abnormal development and pathophysiology in the brain. Although miR-20b plays essential roles in various human diseases, its function in cerebral ischemic stroke remains unclear. A cell model of oxygen glucose deprivation/reoxygenation (OGD/R) and A rat model of middle cerebral artery occlusion/reperfusion (MCAO/R) were constructed. qRT-PCR and western blot were used to evaluate the expression of miR-20b and TXNIP. Cell viability was detected by MTT assay, and cell apoptosis was evaluated by flow cytometry. Targetscan and Starbase were used to predict the potential targets of miR-20b. Luciferase reporter assay was applied to determine the interaction between miR-20b and TXNIP. Rescue experiments were conducted to confirm the functions of miR-20b/TXNIP axis in cerebral ischemic stroke. MiR-20b was significantly downregulated after I/R both in vitro and in vivo. Upregulation of miR-20b inhibited OGD/R-induced neurons apoptosis and attenuated ischemic brain injury in rat model. Bioinformatic prediction suggested that TXNIP might be a target of miR-20b, and luciferase reporter assay revealed that miR-20b negatively regulated TXNIP expression by directly binding to the 3'-UTR of TXNIP. Downregulation of TXNIP inhibited OGD/R-induced neurons apoptosis in vitro and ischemic brain injury in vivo. Rescue experiments indicated that downregulation of TXNIP effectively reversed the effect of miR-20b inhibitor in neurons apoptosis after OGD/R-treatment and ischemic brain injury in a mouse model after MCAO/R-treatment. Our study demonstrated that upregulation of miR-20b protected the brain from ischemic brain injury by targeting TXNIP, extending our understanding of miRNAs in cerebral ischemic stroke.

TXNIP: A Double-Edged Sword in Disease and Therapeutic Outlook

“…Bak reduces blood-brain barrier (BBB) damage, oxidative stress, and apoptosis by regulating TRX1/TXNIP expression and AMPK phosphorylation to weaken EBI after SAH [ 144 ]. Micro-RNAs like miR-17-5P [ 145 ], miR-106b-5p [ 146 ], and miR-20b [ 147 ], inhibits TXNIP expression, protecting brain cells. Thus, upregulation of mir-RNA appears to be a therapeutic target such as GW0742 [ 145 ] and estradiol [ 146 ], to protect brain cells from apoptosis and inflammation damage.…”

Thioredoxin interacting protein, a key molecular switch between oxidative stress and sterile inflammation in cellular response

“…Recent literature shows growing number of newly-identified miRNA that regulate TXNIP expression in various models. One of the examples include miR-20b-3p that has been demonstrated to negatively regulate TXNIP expression in models of diabetic retinopathy and cerebral ischemia[ 24 , 25 ]. Another example is miR-146a-5p, that has been shown to regulate TXNIP expression and subsequently the inflammatory and apoptotic response in human chondrocytes cell line[ 26 ].…”