Apelin-13/APJ system delays intervertebral disc degeneration by activating the PI3K/AKT signaling pathway

W. Liu, F. Niu, H. Sha, L.-D. Liu, Z.-S. Lv, W.-Q. Gong, M. Yan

Department of Spine Surgery, The First Hospital of Jilin University, Changchun, China. 5296827@qq.com

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• Orthopedics

OBJECTIVE: To study the effect of Apelin-13/APJ system on intervertebral disc degeneration and its mechanism.

PATIENTS AND METHODS: This study detected the expression of APJ in human intervertebral disc tissue with varying degrees of degeneration. IL-1β is used to stimulate the degeneration of nucleus pulposus cells. We used recombinant human Apelin-13 and Ala13 to activate and inhibit the APJ receptor, respectively. The inhibitor LY294002 was used to inhibit the PI3K/AKT signaling pathway. We studied the effects of Apelin-13/APJ system on nucleus pulposus cells and its mechanism by Western blot, RT-PCR, and so on.

RESULTS: APJ is lowly expressed in the nucleus pulposus of patients with a high degree of degeneration. IL-1β stimulates the nucleus pulposus cells and reduces the expression of APJ in nucleus pulposus cells. Recombinant human Apelin-13 reduces the degradation of nucleus pulposus extracellular matrix, promotes proliferation, and reduces the levels of apoptosis and inflammation. In addition, the Apelin-13/APJ system increases the expression of PI3K and AKT and activates the PI3K/AKT signaling pathway.

CONCLUSIONS: Apelin-13/APJ system activates PI3K/AKT signaling pathway activity, reduces the degradation of nucleus pulposus extracellular matrix, promotes proliferation, and reduces the level of apoptosis and inflammation, thus delaying the degeneration of the intervertebral disc.

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