Cycloastragenol and Astragaloside IV activate telomerase and protect nucleus pulposus cells against high glucose‑induced senescence and apoptosis

Abstract

In diabetes-induced intervertebral disc degeneration (Db-IVDD), senescence and apoptosis of nucleus pulposus cells (NPCs) are major contributing factors. Telomere attrition and telomerase downregulation are some of the main reasons for senescence and eventual apoptosis. The derivatives of the Chinese herb Astragalus membranaceus , Cycloastragenol (CAG) and Astragaloside IV (AG-IV), are reportedly effective telomerase activators against telomere shortening; however, their effect in Db-IVDD have not been explored. The present study simultaneously investigated the regulation of these derivatives on senescence, apoptosis, telomeres and telomerase a model of high-glucose (HG)-induced stress using rat primary NPCs. The NPCs were stimulated with HG (50 mM) to evoke HG-induced stress, and the effects of CAG and AG-IV were observed on: i) The expression level of senescence marker p16; ii) β-Gal staining; iii) the expression levels of apoptosis markers cleaved-caspase 3 (c-C3), BAX and Bcl-2; iv) telomerase activation with telomerase reverse transcriptase (TERT) mRNA and protein expression, while telomere length was measured with reverse transcription-quantitative PCR. Cell proliferation was determined using the Cell Counting Kit-8 assay. Results demonstrated an upregulation in the expression levels of p16, c-C3 and BAX, and increased β-Gal staining; while the expression level of Bcl-2 was downregulated in a concentration-dependent manner. Pre-treatment of the NPCs with CAG and AG-IV downregulated the protein expression levels of p16, c-C3 and BAX, and decreased the percentage of β-Gal and FITC staining; while upregulating the Bcl-2 expression. These effects protected the cells from HG stress-induced senescence and apoptosis. HG also downregulated the expression profile of TERT and shortened the telomere length in a glucose concentration-dependent manner. While pretreatment with CAG and AG-IV upregulated TERT expression and ameliorated the telomere attrition. CAG and AG-IV also increased cell proliferation and improved cell morphology in HG conditions. Overall, these findings indicated that CAG and AG-IV suppressed HG stress-induced senescence and apoptosis, in addition to enhancing telomerase activation and lengthening of the Telomere. Therefore, CAG and AG-IV prolonged the replicative capability and longevity of the NPCs and they have the potential to be therapeutic agents in Db-IVDD.

Astragaloside IV relieves IL-1β-induced human nucleus pulposus cells degeneration through modulating PI3K/Akt signaling pathway

“…At the same time, studies have found that AS IV effectively alleviated IDD in vivo and in vitro. [ 10 , 31 ] In addition, AS IV ability to stimulate the PI3K/AKT pathway has been pointed out many times and is related to antiapoptosis, antioxidative stress and the protective effect of ischemia-reperfusion. [ 32 , 33 ] However, it is not clear whether AS IV can alleviate disc degeneration by interfering with PI3K/Akt pathway.…”

The therapeutic effects of cycloastragenol in ulcerative colitis by modulating SphK/MIP‐1α/miR‐143 signalling

“…However, cycloastragenol treatment significantly increased BCL2 expression and decreased that of BAX and caspase‐3 in UC rats. Cycloastragenol can modulate BCL2/BAX/caspase‐3 in high glucose‐induced senescence 44 and brain ischaemia‐induced neuroinflammation 37 . However, no previous study has reported the effects of cycloastragenol on apoptosis in UC.…”

From hyperglycemia to intervertebral disc damage: exploring diabetic-induced disc degeneration

“…High glucose concentration is known to have adverse effects on telomerase reverse transcriptase (TERT) expression and telomere length in NPs. After treatment with CAG and AG-IV, the cell morphology and vitality significantly improve, the TERT expression of NPC and telomere length increased, and apoptosis and senescence an inhibited ( 121 ). At present, the exploration of novel pharmacotherapeutic strategies for treating IDD, particularly in the presence of concurrent diabetes, represents a highly promising avenue.…”