Journal Article

High cholesterol induces apoptosis and autophagy through the ROS-activated AKT/FOXO1 pathway in tendon-derived stem cells

Deng, Ye, Deng, Ganming, Chen, Pengyu, Li, Kaiqun, Wang, Yutian, Yu, Bin, Zhang, Kairui, Wu, Hangtian, Zhang, Xianrong, Yao, Zilong, Ji, Zhiguo

2020

Overview

Background Hypercholesterolemia increases the risk of tendon pain and tendon rupture. Tendon-derived stem cells (TDSCs) play a vital role in the development of tendinopathy. Our previous research found that high cholesterol inhibits tendon-related gene expression in TDSCs. Whether high cholesterol has other biological effects on TDSCs remains unknown. Methods TDSCs isolated from female SD rats were exposed to 10 mg/dL cholesterol for 24 h. Then, cell apoptosis was assessed using flow cytometry and fluorescence microscope. RFP-GFP-LC3 adenovirus transfection was used for measuring autophagy. Signaling transduction was measured by immunofluorescence and immunoblotting. In addition, Achilles tendons from ApoE −/− mice fed with a high-fat diet were histologically assessed using HE staining and immunohistochemistry. Results In this work, we verified that 10 mg/dL cholesterol suppressed cell proliferation and migration and induced G0/G1 phase arrest. Additionally, cholesterol induced apoptosis and autophagy simultaneously in TDSCs. Apoptosis induction was related to increased expression of cleaved caspase-3 and BAX and decreased expression of Bcl-xL. The occurrence of autophagic flux and accumulation of LC3-II demonstrated the induction of autophagy by cholesterol. Compared with the effects of cholesterol treatment alone, the autophagy inhibitor 3-methyladenine (3-MA) enhanced apoptosis, while the apoptosis inhibitor Z-VAD-FMK diminished cholesterol-induced autophagy. Moreover, cholesterol triggered reactive oxygen species (ROS) generation and activated the AKT/FOXO1 pathway, while the ROS scavenger NAC blocked cholesterol-induced activation of the AKT/FOXO1 pathway. NAC and the FOXO1 inhibitor AS1842856 rescued the apoptosis and autophagy induced by cholesterol. Finally, high cholesterol elevated the expression of cleaved caspase-3, Bax, LC3-II, and FOXO1 in vivo. Conclusion The present study indicated that high cholesterol induced apoptosis and autophagy through ROS-activated AKT/FOXO1 signaling in TDSCs, providing new insights into the mechanism of hypercholesterolemia-induced tendinopathy. Graphical abstract High cholesterol induces apoptosis and autophagy through the ROS-activated AKT/FOXO1 pathway in tendon-derived stem cells.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Adenoviruses / AKT protein / Apolipoprotein E / Apolipoproteins / Apoptosis / Autophagy / Bcl-x protein / Biomedical and Life Sciences / Biomedical Engineering and Bioengineering / Caspase-3 / Cell adhesion & migration / Cell Biology / Cell cycle / Cell growth / Cell migration / Cell proliferation / Cellular signal transduction / Cholesterol / Experiments / Flow cytometry / Fluorescence / Fluorescence microscopy / Fluorescent antibody technique / FOXO1 protein / G1 phase / Gene expression / Genes / Genetic research / High fat diet / Homeostasis / Hypercholesterolemia / Immunoblotting / Immunofluorescence / Immunohistochemistry / Infection / Life Sciences / Phagocytosis / Reactive oxygen species / Regenerative Medicine/Tissue Engineering / ROS / Signal transduction / Stem cell transplantation / Stem Cells / Tendinopathy / Tendon-derived stem cells / Tendons / Wound healing