Downregulation of circular RNA HECTD1 induces neuroprotection against ischemic stroke through the microRNA-133b/TRAF3 pathway.

AIMS: Circular RNAs (circRNAs) have been shown to play crucial roles in various biological processes and human diseases. However, their exact functions in ischemic stroke remain largely unknown. In this study, we explored the functional role of circRNA HECTD1 (circ-HECTD1) and its underlying mechanism in cerebral ischemia/reperfusion injury. METHODS: Mouse middle cerebral artery occlusion (MCAO) model and oxygen-glucose deprivation (OGD) model in HT22 cells were used to mimic the cerebral ischemia/reperfusion injury. Brain infarct volume, flow cytometry, caspase 3 activity, NF-κB activity, and TUNEL staining were performed to evaluate the function of circ-HECTD1. Luciferase report assay was used to explore the regulatory mechanism. FINDINGS: The results showed that the expression of circ-HECTD1 and tumor necrosis factor receptor-associated factor 3 (TRAF3) was remarkably up-regulated, while miR-133b was down-regulated in oxygen-glucose deprivation (OGD)-induced HT22 cells and mouse middle cerebral artery occlusion (MCAO) model. circ-HECTD1 knockdown relieved OGD-caused neuronal cell death in vitro. Simultaneously, circ-HECTD1 knockdown improved cerebral infarction volume and neuronal apoptosis in MCAO mice. circ-HECTD1 was able to negatively regulate the expression of miR-133b, and TRAF3 is one of the targets of miR-133b. Upregulation of miR-133b inhibited the expression of TRAF3 in OGD-stimulated cells, whereas circ-HECTD1 upregulation reversed this effect. Furthermore, upregulation of miR-133 was able to inhibit OGD-caused cell apoptosis and NF-κB activation, whereas upregulation of circ-HECTD1 attenuated these effects of miR-133b mimics. SIGNIFICANCE: Taken together, circ-HECTD1 knockdown inhibited the expression of TRAF3 by targeting miR-133b, thereby attenuating neuronal injury caused by cerebral ischemia.

Knockdown of long non-coding RNA AL049437 mitigates MPP+ -induced neuronal injury in SH-SY5Y cells via the microRNA-205-5p/MAPK1 axis.

BACKGROUND: Long noncoding RNAs (lncRNAs) have been defined as critical regulators of various human diseases. However, the functions of lncRNAs in Parkinson's disease (PD) have not yet been elucidated. In this study, we investigated the role of lncRNA AL049437 in PD and its underlying mechanism. METHODS: An in vivo model of PD was established using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), while an in vitro model was created using N-methyl-4-phenylpyridinium (MPP+). Gene expression was evaluated using quantitative reverse transcriptase polymerase chain reaction and western blotting. The effects and mechanism of AL049437 in PD were explored using Cell Counting Kit-8 assay, flow cytometry, enzyme-linked immunosorbent assay, and 2',7'-dichlorodihydrofluorescein diacetate fluorescence assay. The interaction between AL049437, miR-205-5p, and mitogen-activated protein kinase 1 (MAPK1) was evaluated using luciferase reporter and RNA pull-down assays. RESULTS: The expression of AL049437 was upregulated, while that of miR-205-5p was downregulated in MPTP-induced PD mouse model and MPP+-treated SH-SY5Y cells. Silencing of AL049437 mitigated MPP+-induced neurotoxicity in SH-SY5Y cells, as demonstrated by increased cell viability and reduced cell apoptosis. Furthermore, silencing of AL049437 alleviated MPP+-induced neuroinflammation and oxidative stress, as indicated by the reduction in tumor necrosis factor-α and interleukin-6 levels and reactive oxygen species production. In addition, AL049437 was predominantly localized in the cytoplasm of SH-SY5Y cells and functioned as an miR-205-5p sponge. Moreover, MAPK1 was identified as a downstream target of miR-205-5p. Remarkably, the impact of AL049437 silencing on MPP+-induced neuronal damage could be blocked by miR-205-5p inhibition or MAPK1 overexpression. CONCLUSION: Knockdown of lncRNA AL049437 mitigates MPP+ -induced neuronal injury in SH-SY5Y cells by regulating the miR-205-5p/MAPK1 axis. Our research reveals a novel regulatory mechanism of AL049437 in PD progression.