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Perez-Tejeiro JM, Csukasi F. DEPTOR in Skeletal Development and Diseases. Front Genet 2021; 12:667283. [PMID: 34122519 PMCID: PMC8191632 DOI: 10.3389/fgene.2021.667283] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 04/12/2021] [Indexed: 12/02/2022] Open
Abstract
Discovered in 2009, the DEP-domain containing mTOR-interacting protein, DEPTOR, is a known regulator of the mechanistic target of rapamycin (mTOR), an evolutionarily conserved kinase that regulates diverse cellular processes in response to environmental stimuli. DEPTOR was originally identified as a negative regulator of mTOR complexes 1 (mTORC1) and 2 (mTORC2). However, recent discoveries have started to unravel the roles of DEPTOR in mTOR-independent responses. In the past few years, mTOR emerged as an important regulator of skeletal development, growth, and homeostasis; the dysregulation of its activity contributes to the development of several skeletal diseases, both chronic and genetic. Even more recently, several groups have reported on the relevance of DEPTOR in skeletal biology through its action on mTOR-dependent and mTOR-independent pathways. In this review, we summarize the current understanding of DEPTOR in skeletal development and disease.
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Affiliation(s)
- Jose Miguel Perez-Tejeiro
- Department of Cell Biology, Genetics and Physiology, Faculty of Sciences, IBIMA, University of Málaga, Málaga, Spain.,Biomaterials and Nanomedicine (CIBER-BBN), Andalusian Centre for Nanomedicine and Biotechnology-BIONAND, Networking Biomedical Research Center in Bioengineering, Málaga, Spain
| | - Fabiana Csukasi
- Department of Cell Biology, Genetics and Physiology, Faculty of Sciences, IBIMA, University of Málaga, Málaga, Spain.,Biomaterials and Nanomedicine (CIBER-BBN), Andalusian Centre for Nanomedicine and Biotechnology-BIONAND, Networking Biomedical Research Center in Bioengineering, Málaga, Spain
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Li K, Yang P, Zhang Y, Zhang Y, Cao H, Liu P, Huang B, Xu S, Lai P, Lei G, Liu J, Tang Y, Bai X, Zou Z. DEPTOR Prevents Osteoarthritis Development Via Interplay With TRC8 to Reduce Endoplasmic Reticulum Stress in Chondrocytes. J Bone Miner Res 2021; 36:400-411. [PMID: 32916025 DOI: 10.1002/jbmr.4176] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 08/23/2020] [Accepted: 09/03/2020] [Indexed: 12/22/2022]
Abstract
Endoplasmic reticulum (ER) stress has been shown to promote chondrocyte apoptosis and osteoarthritis (OA) progression, but the precise mechanisms via which ER stress is modulated in OA remain unclear. Here we report that DEP domain-containing mTOR-interacting protein (DEPTOR) negatively regulated ER stress and OA development independent of mTOR signaling. DEPTOR is ubiquitinated in articular chondrocytes and its expression is markedly reduced along with OA progression. Deletion of DEPTOR in chondrocytes significantly promoted destabilized medial meniscus (DMM) surgery-induced OA development, whereas intra-articular injection of lentivirus-expressing DEPTOR delayed OA progression in mice. Proteomics analysis revealed that DEPTOR interplayed with TRC8, which promoted TRC8 auto-ubiquitination and degraded by the ubiquitin-proteasome system (UPS) in chondrocytes. Loss of DEPTOR led to TRC8 accumulation and excessive ER stress, with subsequent chondrocyte apoptosis and OA progression. Importantly, an inhibitor of ER stress eliminated chondrocyte DEPTOR deletion-exacerbated OA in mice. Together, these findings establish a novel mechanism essential for OA pathogenesis, where decreasing DEPTOR in chondrocytes during OA progression relieves the auto-ubiquitination of TRC8, resulting in TRC8 accumulation, excessive ER stress, and OA progression. Targeting this pathway has promising therapeutic potential for OA treatment. © 2020 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Kai Li
- Academy of Orthopedics, Guangdong Province, Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diseases, The Third Affiliated Hospital of Southern Medical University, Guangzhou, China.,State Key Laboratory of Organ Failure Research, Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China.,Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China
| | - Panpan Yang
- Academy of Orthopedics, Guangdong Province, Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diseases, The Third Affiliated Hospital of Southern Medical University, Guangzhou, China
| | - Yuwei Zhang
- State Key Laboratory of Organ Failure Research, Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Yue Zhang
- State Key Laboratory of Organ Failure Research, Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - He Cao
- Academy of Orthopedics, Guangdong Province, Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diseases, The Third Affiliated Hospital of Southern Medical University, Guangzhou, China
| | - Peilin Liu
- Academy of Orthopedics, Guangdong Province, Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diseases, The Third Affiliated Hospital of Southern Medical University, Guangzhou, China
| | - Bin Huang
- Academy of Orthopedics, Guangdong Province, Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diseases, The Third Affiliated Hospital of Southern Medical University, Guangzhou, China
| | - Song Xu
- Department of Orthopedics and Arthroplasty, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Pinglin Lai
- Academy of Orthopedics, Guangdong Province, Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diseases, The Third Affiliated Hospital of Southern Medical University, Guangzhou, China
| | - Guanghua Lei
- Department of Orthopaedics, Xiangya Hospital, Central South University, Changsha, China
| | - Jia Liu
- Department of Orthopedics, Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, China
| | - Yujin Tang
- Department of Orthopedics, Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, China
| | - Xiaochun Bai
- Academy of Orthopedics, Guangdong Province, Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diseases, The Third Affiliated Hospital of Southern Medical University, Guangzhou, China.,State Key Laboratory of Organ Failure Research, Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China.,Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China
| | - Zhipeng Zou
- State Key Laboratory of Organ Failure Research, Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
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Xin L, Fan W, Tingting D, Zuoming S, Qiang Z. 4-phenylbutyric acid attenuates endoplasmic reticulum stress-mediated apoptosis and protects the hepatocytes from intermittent hypoxia-induced injury. Sleep Breath 2018; 23:711-717. [PMID: 30324548 DOI: 10.1007/s11325-018-1739-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Revised: 09/27/2018] [Accepted: 10/08/2018] [Indexed: 12/15/2022]
Abstract
PURPOSE To investigate the effect of 4-phenylbutyric acid (4-PBA) on intermittent hypoxia (IH)-induced liver cell injury and to clarify the underlying mechanisms. METHODS L02 cells (normal human liver cells) were cultured in normoxic condition or subjected to intermittent hypoxia for 4, 8, and 12 h. A part of hypoxia-treated L02 cells was applied with 4-PBA 1 h before exposure to hypoxia. The effect of 4-PBA on liver injury, hepatocyte apoptosis, endoplasmic reticulum stress (ERS), and PERK-eIFa2-ATF4-CHOP apoptotic pathway was investigated. RESULTS (1) IH caused apoptosis in hepatocyte; (2) IH caused ERS in hepatocyte; (3) IH caused hepatic injury; (4) 4-PBA attenuated IH-induced liver cell injury; (5) 4-PBA protected liver cell from IH-induced apoptosis; (6) 4-PBA suppressed ERS-related apoptotic pathway (PERK-eIFa2-ATF4-CHOP), but did not suppress IH-induced unfold protein reaction (UPR). CONCLUSIONS 4-PBA could protect liver cells by suppressing IH-induced apoptosis mediated by ERS, but not by reducing the UPR.
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Affiliation(s)
- Liu Xin
- Geriatrics, Institute of Gerontology of Tianjin, Tianjin Medical University General Hospital, No.154, Anshan Road, Heping District, Tianjin, China
| | - Wu Fan
- Geriatrics, Institute of Gerontology of Tianjin, Tianjin Medical University General Hospital, No.154, Anshan Road, Heping District, Tianjin, China
| | - Du Tingting
- Geriatrics, Institute of Gerontology of Tianjin, Tianjin Medical University General Hospital, No.154, Anshan Road, Heping District, Tianjin, China
| | - Sun Zuoming
- Beckman Research Institute of the City of Hope, Duarte, CA, USA
| | - Zhang Qiang
- Geriatrics, Institute of Gerontology of Tianjin, Tianjin Medical University General Hospital, No.154, Anshan Road, Heping District, Tianjin, China.
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