Silencing of Long Noncoding RNA Growth Arrest-Specific 5 Alleviates Neuronal Cell Apoptosis and Inflammatory Responses Through Sponging microRNA-93 to Repress PTEN Expression in Spinal Cord Injury.

Yuanwu Cao,Zixian Chen,Chang Jiang,Haodong Lin

doi:10.3389/fncel.2021.646788

Abstract

A secondary injury induced by a spinal cord injury (SCI) remains the main cause of devastating neural dysfunction; therefore, it has been the subject of focused research for many years. Long noncoding RNA (lncRNA) has been found to participate in the SCI process, and this finding presents a high potential for diagnosis and treatment; however, the role of lncRNA in a secondary injury induced by SCI remains unclear. The aim of this study was to investigate the regulatory effect of lncRNA growth arrest–specific transcript 5 (GAS5) in secondary injury during SCI. The SCI mice model and hypoxic cellular model were established to research the roles of lncRNA GAS5 during SCI. Reverse transcription quantitative polymerase chain reaction (qRT-PCR) was conducted to determine the expression levels of microR-93 (miR-93) and lncRNA GAS5. Western blot analysis of the apoptosis regulator protein and terminal deoxynucleotidyl transferase dUTP nick end labeling assay was conducted to evaluate neuron cell apoptosis. Basso, Beattie, and Bresnahan (BBB) scores were calculated to assess neurological function. Flow cytometry was used to determine neuron cell apoptosis. The associations among GAS5, miR-93, and the phosphatase and tensin homolog (PTEN) were disclosed using RNA immunoprecipitation (RIP) assay, RNA pulldown assay, and dual-luciferase reporter assay. QRT-PCR demonstrated that GAS5 was significantly upregulated in both the SCI mice and hypoxic cellular models. GAS5 knockdown suppressed neuron cell apoptosis and inflammatory response in the SCI mice model. Further studies have indicated that GAS5 functions as a competing endogenous RNA (ceRNA) by sponging miR-93 in neuronal cells. In addition, PTEN was a target of miR-93, and GAS5 knockdown exhibited its anti-apoptotic and anti-inflammatory effects through the miR-93/PTEN axis. These findings suggest that the GAS5/miR-93/PTEN axis may be a promising therapeutic target for SCI.

Highlights

Spinal cord injury (SCI) is a traumatic event that can cause permanent motor and sensory deficits
We found that silencing growth arrest–specific transcript 5 (GAS5) alleviated neuron cell inflammation and apoptosis in the spinal cord injury (SCI) mice by regulating the miR-93/phosphatase and tensin homolog (PTEN) axis, which allowed us to better understand the pathologies of this disease
LncRNA GAS5 Was Upregulated in SCI Mice

Summary

Introduction

Spinal cord injury (SCI) is a traumatic event that can cause permanent motor and sensory deficits. SCI affects approximately 250,000–500,000 people worldwide each year (Singh et al, 2014). The pathophysiology of SCI is best described as primary uncontrollable mechanical injury and secondary controllable degeneration. Because of the complex nature of a secondary injury following the primary injury, considerable research efforts have focused on understanding the pathophysiology of the secondary damage. Various cellular inflammatory responses and apoptosis following SCI mediate delayed tissue degeneration and contribute to secondary damage of the spinal cord (Liu et al, 2015). Reducing secondary damage following SCI is key for preventing the propagation of additional injury

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