2. Academic Validation
  3. Cholesterol inhibits autophagy in RANKL-induced osteoclast differentiation through activating the PI3K/AKT/mTOR signaling pathway

Cholesterol inhibits autophagy in RANKL-induced osteoclast differentiation through activating the PI3K/AKT/mTOR signaling pathway

  • Mol Biol Rep. 2022 Oct;49(10):9217-9229. doi: 10.1007/s11033-022-07747-w.
Chunyan Jiang 1 2 3 4 5,  Yan Wang 1 2 3 4,  Mengqi Zhang 1 2 3 4,  Jin Xu 6 7 8 9
Affiliations

Affiliations

  • 1 Department of Endocrinology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China.
  • 2 Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China.
  • 3 Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan, Shandong, China.
  • 4 Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Jinan, 250021, Shandong, China.
  • 5 Department of Endocrinology, People's Hospital of Linyi, Linyi, Shandong, China.
  • 6 Department of Endocrinology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China. slyyxujin@163.com.
  • 7 Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China. slyyxujin@163.com.
  • 8 Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan, Shandong, China. slyyxujin@163.com.
  • 9 Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Jinan, 250021, Shandong, China. slyyxujin@163.com.
PMID: 35881223 DOI: 10.1007/s11033-022-07747-w
Abstract

Background: A dysregulated balance between bone formation and bone resorption controlled by osteoblast and osteoclast will lead to osteoporosis. Cholesterol (CHO) is a crucial factor leading to osteoporosis, and Autophagy appears to involve it. Therefore, we aimed to study the molecular mechanism of Autophagy in CHO-induced osteoclasts differentiation.

Methods: Nuclear factor-κ B ligand as a receptor activator was used to induce osteoclasts differentiation of murine macrophage RAW264.7 treated with CHO, PI3-kinase inhibitor (LY294002), and Rapamycin (RAPA), respectively. Western blot assay was used to detect the expression of TRAP/ACP5 and the proteins involved in Autophagy and the PI3K/Akt/mTOR signaling pathway. In addition, TRAP staining, bone resorption assay, and F-actin immunofluorescence were performed to evaluate the ability of osteoclast formation. Transmission electron microscopy and immunofluorescence were also executed to observed the expression of LC3B, and autophagosome.

Results: When RAW264.7 was treated with 20 μg/mL CHO for 5 consecutive days, It exhibited the optimal osteoclast activity. In addition, CHO could inhibit Autophagy and activate the PI3K/Akt/mTOR signaling pathway. Moreover, the effects of CHO on osteoclast differentiation and Autophagy could partially be reversed by LY294002 and RAPA.

Conclusion: Therefore, our results demonstrated that CHO could inhibit Autophagy during osteoclast differentiation by activating the PI3K/Akt/mTOR signaling pathway. These findings provided important theoretical basis for CHO in bone resorption and formation.

Keywords

Autophagy; Cholesterol; Osteoclast differentiation; PI3K/AKT/mTOR signaling pathway.

Figures
Products