Liraglutide inhibits the apoptosis of human nucleus pulposus cells induced by high glucose through PI3K/Akt/caspase-3 signaling pathway.

Yao Ming-Yan,Zhou Xue,Li Zhi-Hong,Bai Xiao-Liang,Guo Shu-Qin,Zhang Jing

doi:10.1042/bsr20190109

Abstract

Diabetes mellitus (DM) is a potential etiology of disc degeneration. Glucagon-like peptide-1 (GLP-1) is currently regarded as a powerful treatment option for type 2 diabetes. Apart from the beneficial effects on glycaemic control, GLP-1 has been reported to exert functions in a variety of tissues on modulation of cell proliferation, differentiation, and apoptosis. However, little is known regarding the effects of GLP-1 on nucleus pulposus cells (NPCs). In the present study, we investigated the effects of liraglutide (LIR), a long-lasting GLP-1 analogue, on apoptosis of human NPCs and the underlying mechanisms involved. We confirmed the presence of GLP-1 receptor (GLP-1R) in NPCs. Our data demonstrated that liraglutide inhibited the apoptosis of NPCs induced by high glucose (HG), as detected by Annexin V/Propidium Iodide (PI) and ELISA assays. Moreover, liraglutide down-regulated caspase-3 activity at intermediate concentration (100 nM) for maximum effect. Further analysis suggested that liraglutide suppressed reactive oxygen species (ROS) generation and stimulated the phosphorylation of Akt under HG condition. Pretreatment of cells with the Phosphoinositide 3-kinase (PI3K) inhibitor LY294002 (LY) and small interfering RNAs (siRNAs) GLP-1R abrogated the liraglutide-induced activation of Akt and the protective effects on NPCs’ apoptosis. In conclusion, liraglutide could directly protect NPCs against HG-induced apoptosis by inhibiting oxidative stress and activate the PI3K/Akt/caspase-3 signaling pathway via GLP-1R.

Highlights

Introduction and backgroundIntervertebral disc degeneration (IDD) is a common musculoskeletal disorder
To elucidate the role of Glucagon-like peptide-1 (GLP-1) in nucleus pulposus cell (NPC) apoptosis, we demonstrated the expression of GLP-1 receptor (GLP-1R) protein in NPCs with Western blot analysis (Figure 1)
To ascertain the role of liraglutide in cell proliferation, we examined the viability of NPCs incubated with high glucose (HG) and different doses of liraglutide for 48 h with six time points using 5-ethynyl-2 -deoxyuridine (EdU) assay

Summary

Introduction

Introduction and backgroundIntervertebral disc degeneration (IDD) is a common musculoskeletal disorder. The cell vitality, apoptosis rate, reactive oxygen species (ROS) level, and the expression of GLP-1R, Akt, p-Akt, and caspase-3 of the groups were detected under the same experimental conditions after incubation for 48 h. Caspase-3 activity, a crucial mediator of cell apoptosis, was significantly increased after treating with HG compared with the control group, and it was significantly decreased after liraglutide treatment (P

Results

Conclusion