LncRNA GAS5 as miR-26a-5p Sponge Regulates the PTEN/PI3K/Akt Axis and Affects Extracellular Matrix Synthesis in Degenerative Nucleus Pulposus Cells in vitro.

Kai Hu,Yifang Xie,Liang Tan,Ye Yuan

doi:10.3389/fneur.2021.653341

Kai Hu, Yifang Xie + Show 2 more

Open Access

https://doi.org/10.3389/fneur.2021.653341

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Abstract

The role of lncRNA growth arrest specific 5 (GAS5) in degenerative nucleus pulposus cell (NPC) apoptosis has been reported, but the mechanism of GAS5 in extracellular matrix (ECM) synthesis in intervertebral disc degeneration (IDD) remains unknown. We aimed to investigate the mechanism of GAS5 in ECM synthesis in degenerative NPCs. GAS5 expression was measured in degenerative NPCs (CP-H170) and normal NPCs (CP-H097). siRNA-mediated GAS5 knockdown was transfected to NPCs to detect cell viability and the expression of ECM-related genes (Collagen II, aggrecan, Collagen I, and MMP-3). Subcellular localization of GAS5 was analyzed. The downstream gene and pathway of GAS5 in degenerative NPCs were explored. As our results indicated, lncRNA GAS5 was upregulated in degenerative NPCs. Silencing GAS5 improved the viability of degenerative NPCs and increased ECM synthesis. GAS5 was mainly located in the cytoplasm of NPCs. LncRNA GAS5 sponged miR-26a-5p to regulate PTEN. Overexpression of miR-26a-5p promoted ECM synthesis in degenerative NPCs. Akt inhibitor LY294002 reversed the promotion of silencing GAS5 on ECM synthesis of degenerative NPCs. In conclusion, lncRNA GAS5 sponged miR-26a-5p to upregulate PTEN and inhibit the PI3K/Akt pathway, thus inhibiting ECM synthesis of degenerative NPCs.

Highlights

Intervertebral discs (IVD) are composed of nucleus pulposus (NP), annulus fibrosus, and cartilaginous endplates [1]
growth arrest specific 5 (GAS5) expression in degenerative nucleus pulposus cell (NPC) was higher than that in normal NPCs (Figure 1C, p < 0.01). These results suggest that the upregulation of GAS5 expression may be related to intervertebral disc degeneration (IDD) occurrence
This study highlighted that lncRNA GAS5 was overexpressed in IDD, and GAS5 can compete with PTEN to bind to miR-26a-5p, inhibiting extracellular matrix (ECM) the synthesis of degenerative NPCs

Summary

Introduction

Intervertebral discs (IVD) are composed of nucleus pulposus (NP), annulus fibrosus, and cartilaginous endplates [1]. The degenerative changes of IVD are related to the injury of adjacent structures, resulting in functional impairment; more vulnerability to injury; and clinical symptoms such as spinal stenosis, axial back pain, myelopathy, or radiculopathy [2]. Intervertebral disc degeneration (IDD) is the primary pathological mechanism which underlies low back pain, leading to a great burden on the global health care system [3,4,5]. Composed of collagens and proteoglycans, the ECM of the inner disc maintains IVD normal function [7]. With the increase of IDD during the process of disc degeneration, the synthesis of Collagen I and proteoglycan and ECM degradation increase [8,9,10]. It is imperative to identify the effect of ECM synthesis for IDD management

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