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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Neurosci. | doi: 10.3389/fnins.2019.01225

High-Frequency Repetitive Transcranial Magnetic Stimulation Mediates Autophagy Flux in Human Bone Mesenchymal Stromal Cells via NMDAR–Ca2+–ERK–mTOR Signaling

  • 1First Affiliated Hospital of Soochow University, China
  • 2Department of Physical Medicine & Rehabilitation, the First Affiliated Hospital of Soochow University, China
  • 3Department of Children’s Health Care Center, Wuxi Children’s Hospital, China
  • 4Sport Rehabilitation Center of Physical and Education School, Soochow University, China
  • 5Department of Neurology, the First Affiliated Hospital of Soochow University, China
  • 6Department of Medical Rehabilitation Community Health Service Centre, China
  • 7Department of cardiopulmonary rehabilitation, Wuxi Tongren International Rehabilitation Hospital, China
  • 8Department of Geriatric Rehabilitation, Jiangsu Rongjun Hospital, China
  • 9Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Soochow University, China

Repetitive transcranial magnetic stimulation (rTSM) is a non-invasive and safe technique for treatment of central and peripheral nerve injury. In recent years, this technique has been widely used in the clinic and an increasing number of studies have reported its mechanisms. In this study, we investigated the mechanisms of rTMS mediated autophagy flux in human bone mesenchymal stromal cells (BMSCs). Methods: A frequency of 50 Hz was employed. Cells were divided into five groups: (1) normal; (2) sham; (3) 0.5 T; (4) 1.0 T; and (5) 1.5 T. Cells were stimulated for 20 minutes per day. The levels of p62, LC3-II/I, p-ERK, ERK, p-AKT, AKT, p-mTOR, mTOR, p-PKA, PKA, p-EGFR, EGFR, Nanog, Oct4, Sox2 and NMDAR1 were investigated by western blotting. Intracellular calcium (Ca2+) levels were quantified by flow cytometry. p62 and LC3 expression were also assessed by immunofluorescent analysis. Results: In the 0.5 T group, rTSM increased the expression of LC3-II/I, p-ERK/ERK, NMDAR1, and decreased the levels of p62 and p-mTOR/mTOR compared to the normal group. The ratio of p-AKT/AKT, p-PKA/PKA and p-EGFR/EGFR and the expression of Nanog, Oct4 and Sox2 remained unchanged. Immunofluorescence analysis revealed colocalization of p62 with LC3 puncta and flow cytometry analysis displayed Ca2+ levels were elevated. However, in the 1.0 T and 1.5 T groups, no changes in the expression of these autophagy markers were observed. Conclusions: In the 0.5 T group, high-frequency rTSM can induce autophagy through NMDAR–Ca2+–ERK–mTOR signaling in BMSCs. In the 1.0 T and 1.5 T groups, autophagy is not activated.

Keywords: repetitive transcranial magnetic stimulation, Autophagy, Bone mesenchymal stromal cells, ERK-mTOR signaling, NMDAR

Received: 17 Jul 2019; Accepted: 29 Oct 2019.

Copyright: © 2019 Long, xing, jie, guo, zhao, yang, jing, qi, Liu and min. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Mx. Fang qi, Department of Neurology, the First Affiliated Hospital of Soochow University, Suzhou, China, fangqi_008@126.com
Mx. Su min, Department of Physical Medicine & Rehabilitation, the First Affiliated Hospital of Soochow University, Suzhou, China, sumin@suda.edu.cn