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Tao Y, Yu X, Li X, Xu Y, Wang H, Zhang L, Lin R, Wang Y, Fan P. M6A methylation-regulated autophagy may be a new therapeutic target for intervertebral disc degeneration. Cell Biol Int 2024; 48:389-403. [PMID: 38317355 DOI: 10.1002/cbin.12135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 01/01/2024] [Indexed: 02/07/2024]
Abstract
Degeneration of intervertebral discs is considered one of the most important causes of low back pain and disability. The intervertebral disc (IVD) is characterized by its susceptibility to various stressors that accelerate the senescence and apoptosis of nucleus pulposus cells, resulting in the loss of these cells and dysfunction of the intervertebral disc. Therefore, how to reduce the loss of nucleus pulposus cells under stress environment is the main problem in treating intervertebral disc degeneration. Autophagy is a kind of programmed cell death, which can provide energy by recycling substances in cells. It is considered to be an effective method to reduce the senescence and apoptosis of nucleus pulposus cells under stress. However, further research is needed on the mechanisms by which autophagy of nucleus pulposus cells is regulated under stress environments. M6A methylation, as the most extensive RNA modification in eukaryotic cells, participates in various cellular biological functions and is believed to be related to the regulation of autophagy under stress environments, may play a significant role in nucleus pulposus responding to stress. This article first summarizes the effects of various stressors on the death and autophagy of nucleus pulposus cells. Then, it summarizes the regulatory mechanism of m6A methylation on autophagy-related genes under stress and the role of these autophagy genes in nucleus pulposus cells. Finally, it proposes that the methylation modification of autophagy-related genes regulated by m6A may become a new treatment approach for intervertebral disc degeneration, providing new insights and ideas for the clinical treatment of intervertebral disc degeneration.
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Affiliation(s)
- Yuao Tao
- Department of Spine Center, Zhongda Hospital, Medical School, Southeast University, Nanjing, China
| | - Xiaoyu Yu
- Department of Gynaecology and Obstetrics, The Affiliated Jiangning Hospital of Nanjing Medical University, Nanjing, China
| | - Xiaolong Li
- Department of Spine Center, Zhongda Hospital, Medical School, Southeast University, Nanjing, China
| | - Yuzhu Xu
- Department of Spine Center, Zhongda Hospital, Medical School, Southeast University, Nanjing, China
| | - Hui Wang
- Department of Spine Center, Zhongda Hospital, Medical School, Southeast University, Nanjing, China
| | - Lele Zhang
- Department of Spine Center, Zhongda Hospital, Medical School, Southeast University, Nanjing, China
| | - Rubing Lin
- Department of Orthopedics, Shenzhen Children's Hospital, Shenzhen, Guangdong, China
| | - Yuntao Wang
- Department of Spine Center, Zhongda Hospital, Medical School, Southeast University, Nanjing, China
| | - Pan Fan
- Department of Spine Center, Zhongda Hospital, Medical School, Southeast University, Nanjing, China
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Zhu G, Yang X, Zhou W, Lian X, Hao Y. PLAGL2 induces nucleus pulposus cell apoptosis via regulating RASSF5 expression and thus accelerates intervertebral disc degeneration. Exp Cell Res 2023:113699. [PMID: 37364764 DOI: 10.1016/j.yexcr.2023.113699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 06/21/2023] [Accepted: 06/23/2023] [Indexed: 06/28/2023]
Abstract
Excessive apoptosis of nucleus pulposus (NP) cells is the main pathological change in intervertebral disc degeneration (IVDD) progression. Pleomorphic adenoma gene like-2 (PLAGL2) plays a key role in cell apoptosis, however, the effect of PLAGL2 on IVDD has not been clarified yet. In this study, we established mouse IVDD models via the annulus fibrosis needle puncture, TUNEL and safranin O staining were used to verify the successful establishment of IVDD models, and PLAGL2 expression was detected in disc tissues. Then, NP cells isolated from disc tissues were used to construct PLAGL2 knockdown cells. PLAGL2 expression in NP cells was analyzed with qRT-PCR and Western blot. The impact of PLAGL2 on the viability, apoptosis, and mitochondria function of NP cells was evaluated by MTT assay, TUNEL, JC1 staining, and flow cytometry assay. Additionally, the regulatory mechanism of PLAGL2 was further assessed. We found that PLAGL2 was upregulated in IVDD disc tissues and serum deprivation (SD)-stimulated NP cells. PLAGL2 knockdown inhibited apoptosis and mitochondria damage in NP cells. Moreover, knockdown of PLAGL2 downregulated the expression of downstream apoptosis-related factors RASSF5, Nip3, and p73. Mechanically, PLAGL2 transcriptionally activated RASSF5 via binding to its promoter. In general, our findings indicate that PLAGL2 induces apoptosis in NP cells and aggravates IVDD progression. This study provides a promising therapeutic target for IVDD treatment.
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Affiliation(s)
- GuangDuo Zhu
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, China
| | - XiaoWei Yang
- Department of Cardiovascular Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, China
| | - WeiWei Zhou
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, China
| | - Xu Lian
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, China
| | - YingJie Hao
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, China.
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Overexpression of BNIP3 in rat intervertebral disk cells triggers autophagy and apoptosis. ARCH BIOL SCI 2022. [DOI: 10.2298/abs220310013w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Excessive apoptosis of intervertebral disk cells and intervertebral disk
degeneration (IDD) is the prime cause of low back pain. B-cell lymphoma 2
(Bcl-2) and adenovirus E1B 19 kDa interacting protein 3 (BNIP3), a member of
the Bcl-2 family, are involved in cell autophagy and apoptosis. The roles
and mechanisms of BNIP3 in intervertebral disk cell autophagy and apoptosis
are unclear. In this study, primary rat intervertebral disk cells were
prepared to study the effect of BNIP3 overexpression on their autophagy and
apoptosis. The cell counting kit (CCK)-8 assay showed that BNIP3
overexpression decreased cell viability. Real-time PCR and Western blotting
showed that BNIP3 overexpression significantly upregulated the expression of
autophagy-related proteins and pro-apoptotic proteins, including
hypoxia-inducible factor-1?, apoptotic protease activating factor 1, caspase
3 and cleaved caspase 3, microtubule-associated proteins 1A/1B light chain 3
(LC3) and Beclin-1 while downregulating the expression of anti-apoptotic
protein Bcl-2. Cell staining detection of autophagy and apoptosis showed
that BNIP3 overexpression significantly increased the autophagy and
apoptosis of rat intervertebral disk cells. BNIP3 RNA interference revealed
that the effects of BNIP3 overexpression can be reversed. These findings
suggested that BNIP3 enhanced the autophagy and apoptosis in the rat
intervertebral disk cells in vitro, which might promote IDD development.
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Mitochondrial Dysfunction in Intervertebral Disc Degeneration: From Pathogenesis to Therapeutic Target. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020. [DOI: 10.1155/2020/8880320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Mitochondria are cytosolic organelles essential for cellular function and survival. The function of mitochondria is maintained by mitochondrial quality control systems including mitochondrial fission and fusion to adapt the altered environment and mitophagy for removal of damaged mitochondria. Mitochondrial dysfunction is closely involved in aging-related diseases. Intervertebral disc (IVD) degeneration, an aging-associated process, is the major contributor to low back pain. Growing evidence has suggested that the mitochondrial function in IVD cells is severely compromised during the degenerative process of IVD, and dysfunctional mitochondria along with impaired mitochondrial dynamics and mitophagy cause a series of cascade reactions that have been implicated in increased oxidative stress, senescence, matrix catabolism, and apoptosis of IVD cells, thereby contributing to the degeneration of IVD. Accordingly, therapies that target mitochondrial dysfunction and related mechanisms, such as ROS generation, mitophagy, and specific molecules and signaling, hold great promise. The present review summarizes the current state of the role of mitochondrial dysfunction in the pathophysiology of IVD degeneration and potential therapeutic strategies that could be developed.
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Abstract
Mitochondrial dysfunction is involved in aging and multiple degenerative diseases, including intervertebral disc degeneration (IVDD) and osteoarthritis (OA). Thus, the maintenance of mitochondria homeostasis and function is important. Mitophagy, a process that selectively clears damaged or dysfunctional mitochondria through autophagic machinery, functions to maintain mitochondrial quality control and homeostasis. IVDD and OA are similar joint diseases involving the degradation of cartilaginous tissues that are mainly caused by oxidative stress, cell apoptosis and extracellular matrix (ECM) degradation. Over the past decade, accumulating evidence indicates the essential role of mitophagy in the pathogenesis of IVDD and OA. Importantly, strategies by the regulation of mitophagy exert beneficial effects in the pre-clinical experiments. Given the importance and novelty of mitophagy, we provide an overview of mitophagy pathways and discuss the roles of mitophagy in IVDD and OA. We also highlight the potential of targeting mitophagy for the treatment of degenerative joint diseases. Abbreviations: AD: Alzheimer disease; AF: annulus fibrosus; ADORA2A/A2AR: adenosine A2a receptor; AMBRA1: autophagy and beclin 1 regulator 1; BMSCs: bone marrow mesenchymal stem cells; BNIP3: BCL2 interacting protein 3; BNIP3L/NIX: BCL2/adenovirus E1B interacting protein 3-like; CDH6: cadherin 6; CEP: cartilaginous endplates; circRNA: circular RNA; DNM1L/DRP1: dynamin 1-like; ECM: extracellular matrix; HIF1A: hypoxia inducible factor 1: alpha subunit; IL1B: interleukin 1 beta; IMM: inner mitochondrial membranes; IVDD: intervertebral disc degeneration; MAPK8/JNK: mitogen-activated protein kinase 8; MFN1: mitofusin 1; MFN2: mitofusin 2; MIA: monosodium iodoacetate; RHOT/MIRO: ras homolog family member T; MMP: mitochondrial transmembrane potential; CALCOCO2/NDP52: calcium binding and coiled-coil domain 2; NFE2L2: nuclear factor: erythroid 2 like 2; NP: nucleus pulposus; OA: osteoarthritis; OPA1: OPA1: mitochondrial dynamin like GTPase; OPTN: optineurin; PRKN: parkin RBR E3 ubiquitin protein ligase; PD: Parkinson disease; PGAM5: PGAM family member 5; PPARGC1A/PGC-1A: peroxisome proliferator activated receptor: gamma: coactivator 1 alpha; PHF23: PHD finger protein 23; PINK1: PTEN induced putative kinase 1; ROS: reactive oxygen species; SfMSCs: synovial fluid MSCs; SIRT1: sirtuin 1; SIRT2: sirtuin 2; SIRT3: sirtuin 3; SQSTM1/p62: sequestosome 1; TNF: tumor necrosis factor; Ub: ubiquitin; UBL: ubiquitin-like; VDAC: voltage-dependent anion channel.
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Affiliation(s)
- Kai Sun
- Department of Orthopedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Xingzhi Jing
- Department of Spine Surgery, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
| | - Jiachao Guo
- Department of Orthopedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Xudong Yao
- Department of Orthopedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Fengjing Guo
- Department of Orthopedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
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Antiaging Factor Klotho Retards the Progress of Intervertebral Disc Degeneration through the Toll-Like Receptor 4-NF- κB Pathway. Int J Cell Biol 2020; 2020:8319516. [PMID: 32256598 PMCID: PMC7106913 DOI: 10.1155/2020/8319516] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 01/09/2020] [Accepted: 01/31/2020] [Indexed: 12/18/2022] Open
Abstract
Antiaging protein Klotho exhibits impressive properties of anti-inflammation, however is declined early after intervertebral disc injury, making Klotho restoration an attractive strategy of treating intervertebral disc inflammatory disorders. Here, we have found that Klotho is enriched in nucleus pulposus (NP) cells and Klotho overexpression attenuates H2O2-induced acute inflammation essentially via suppressing Toll-like receptor 4 (TLR4). The proinflammatory NF-κB signaling and cytokine expressions paralleled with Klotho repression and TLR4 elevation in both NP cells (H2O2 treatment) and rat intervertebral disc (needle puncture treatment). Overexpression of TLR4 downregulated expression of Klotho, whereas interfering TLR4 expression diminished the inhibitory effects of H2O2 on Klotho in NP cells. Consistently, Klotho knockdown by RNA interferences largely diminished the anti-inflammatory and intervertebral disc protective effects in an Intervertebral Disc Degeneration (IDD) model. Thus, our study indicates that TLR4-NF-κB signaling and Klotho form a negative-feedback loop in NP cells. Also, we demonstrate that the expression of Klotho is regulated by the balance between upregulation and downregulation of TLR4-NF-κB signaling.
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Tian D, Liu J, Chen L, Zhu B, Jing J. The protective effects of PI3K/Akt pathway on human nucleus pulposus mesenchymal stem cells against hypoxia and nutrition deficiency. J Orthop Surg Res 2020; 15:29. [PMID: 31992313 PMCID: PMC6988348 DOI: 10.1186/s13018-020-1551-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 01/09/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND To study the effects of hypoxia and nutrition deficiency mimicking degenerated intervertebral disc on the biological behavior of human nucleus-derived pulposus mesenchymal stem cells (hNP-MSCs) and the role of PI3K/Akt pathway in the process in vitro. METHODS hP-MSCs were isolated from lumbar disc and were further identified by their immunophenotypes and multilineage differentiation. Then, cells were divided into the control group, hypoxia and nutrition deficiency group, the LY294002 group, and insulin-like growth factor 1 (IGF-1) group. Then cell apoptosis, the cell viability, the caspase 3 activity, and the expression of PI3K, Akt, and functional genes (aggrecan, collagen I, and collagen II) were evaluated. RESULT Our work showed that isolated cells met the criteria of International Society for cellular Therapy. Therefore, cells obtained from degenerated nucleus pulposus were definitely hNP-MSCs. Our results showed that hypoxia and nutrition deficiency could significantly increase cell apoptosis, the caspase 3 activity, and inhibit cell viability. Gene expression results demonstrated that hypoxia and nutrition deficiency could increase the relative expression of PI3K and Akt gene and inhibit the expression of functional genes. However, when the PI3K/Akt pathway was inhibited by LY294002, the cell apoptosis and caspase 3 activity significantly increased while the cell viability was obviously inhibited. Quantitative real-time PCR results showed that the expression of functional genes was more significantly inhibited. Our study further verified that the above-mentioned biological activities of hNP-MSCs could be significantly improved by IGF1. CONCLUSIONS PI3K/Akt signal pathway may have protective effects on human nucleus pulposus-derived mesenchymal stem cells against hypoxia and nutrition deficiency.
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Affiliation(s)
- DaSheng Tian
- Department of Orthopaedics, The Second Affiliated Hospital of Anhui Medical University, 678#Fu Rong Road, Hefei, Anhui, 230601, People's Republic of China
| | - Jianjun Liu
- Department of Orthopaedics, The Second Affiliated Hospital of Anhui Medical University, 678#Fu Rong Road, Hefei, Anhui, 230601, People's Republic of China
| | - Lei Chen
- Department of Orthopaedics, The Second Affiliated Hospital of Anhui Medical University, 678#Fu Rong Road, Hefei, Anhui, 230601, People's Republic of China
| | - Bin Zhu
- Department of Orthopaedics, The Second Affiliated Hospital of Anhui Medical University, 678#Fu Rong Road, Hefei, Anhui, 230601, People's Republic of China
| | - Juehua Jing
- Department of Orthopaedics, The Second Affiliated Hospital of Anhui Medical University, 678#Fu Rong Road, Hefei, Anhui, 230601, People's Republic of China.
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Wang Z, Ishihara Y, Ishikawa T, Hoshijima M, Odagaki N, Ei Hsu Hlaing E, Kamioka H. Screening of key candidate genes and pathways for osteocytes involved in the differential response to different types of mechanical stimulation using a bioinformatics analysis. J Bone Miner Metab 2019; 37:614-626. [PMID: 30413886 DOI: 10.1007/s00774-018-0963-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 09/25/2018] [Indexed: 12/16/2022]
Abstract
This study aimed to predict the key genes and pathways that are activated when different types of mechanical loading are applied to osteocytes. mRNA expression datasets (series number of GSE62128 and GSE42874) were obtained from Gene Expression Omnibus database (GEO). High gravity-treated osteocytic MLO-Y4 cell-line samples from GSE62128 (Set1), and fluid flow-treated MLO-Y4 samples from GSE42874 (Set2) were employed. After identifying the differentially expressed genes (DEGs), functional enrichment was performed. The common DEGs between Set1 and Set2 were considered as key DEGs, then a protein-protein interaction (PPI) network was constructed using the minimal nodes from all of the DEGs in Set1 and Set2, which linked most of the key DEGs. Several open source software programs were employed to process and analyze the original data. The bioinformatic results and the biological meaning were validated by in vitro experiments. High gravity and fluid flow induced opposite expression trends in the key DEGs. The hypoxia-related biological process and signaling pathway were the common functional enrichment terms among the DEGs from Set1, Set2 and the PPI network. The expression of almost all the key DEGs (Pdk1, Ccng2, Eno2, Egln1, Higd1a, Slc5a3 and Mxi1) were mechano-sensitive. Eno2 was identified as the hub gene in the PPI network. Eno2 knockdown results in expression changes of some other key DEGs (Pdk1, Mxi1 and Higd1a). Our findings indicated that the hypoxia response might have an important role in the differential responses of osteocytes to the different types of mechanical force.
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Affiliation(s)
- Ziyi Wang
- Department of Orthodontics, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata, Kita-ku, Okayama, 700-8525, Japan
| | | | - Takanori Ishikawa
- Department of Orthodontics, Okayama University Hospital, Okayama, Japan
| | - Mitsuhiro Hoshijima
- Department of Orthodontics, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata, Kita-ku, Okayama, 700-8525, Japan
| | - Naoya Odagaki
- Department of Orthodontics, Okayama University Hospital, Okayama, Japan
| | - Ei Ei Hsu Hlaing
- Department of Orthodontics, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata, Kita-ku, Okayama, 700-8525, Japan
| | - Hiroshi Kamioka
- Department of Orthodontics, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata, Kita-ku, Okayama, 700-8525, Japan.
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Sun H, Qi L, Wang S, Li X, Li C. Hydrogen sulfide is expressed in the human and the rat cultured nucleus pulposus cells and suppresses apoptosis induced by hypoxia. PLoS One 2018; 13:e0192556. [PMID: 29466396 PMCID: PMC5821346 DOI: 10.1371/journal.pone.0192556] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 01/25/2018] [Indexed: 12/22/2022] Open
Abstract
Apoptosis plays pivotal role in the pathogenesis of degenerative disc diseases, which is the primary contributor to low back pain. Although the role of hydrogen sulfide (H2S) in cell apoptosis is well appreciated, the effects and mechanism that H2S regulates the program death of intervertebral disc cell are not yet elucidated. In this study, we utilized the nucleus pulposus (NP) from patients with lumbar disc herniation to investigate the relationship between endogenous H2S and NP cells apoptosis in human. Furthermore, we analyzed primary rat NP cells to study the effects of exogenous H2S on hypoxia induced cell apoptosis. Human NP samples were obtained from patients with lumbar disc herniation and were divided into uncontained and contained herniation groups. Using immunohistochemistry staining and sulphur-sensitive electrode, we detected the expression of cystathionine-β-synthase (CBS) and cystathionine γ-lyase (CSE), as well as the production of endogenous H2S in human NP. Tunel staining showed increased apoptosis in NP from herniated disc; and there was significant correlation between H2S generation and apoptosis in human NP. CoCl2 was then used to induce hypoxia in cultured primary rat NP cells. Annexin V staining indicated that exogenous NaHS attenuated hypoxia induced apoptosis in rat NP cells. Furthermore, hypoxia significantly increased the levels of multiple apoptosis associated proteins (Fas, Cytochromes C, Caspase 9 and cleaved-Caspase-3) in cells, which were eliminated by NaHS. Our study demonstrates the presence of endogenous H2S in human intervertebral disc; and the endogenous H2S generation rate is associated with NP apoptosis in herniated disc. In vitro study showes exogenous H2S donor attenuates hypoxia induced apoptosis in primary rat NP cells. Thus, our work provides insights that H2S may have beneficial effects in treating degenerative disc diseases.
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Affiliation(s)
- Haolin Sun
- Department of Orthopedic, Peking University First Hospital, Beijing, China
| | - Longtao Qi
- Department of Orthopedic, Peking University First Hospital, Beijing, China
| | - Shijun Wang
- Department of Orthopedic, Peking University First Hospital, Beijing, China
| | - Xuwen Li
- Department of Orthopedic, Peking University First Hospital, Beijing, China
| | - Chunde Li
- Department of Orthopedic, Peking University First Hospital, Beijing, China
- * E-mail:
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Liu J, Yuan C, Pu L, Wang J. Nutrient deprivation induces apoptosis of nucleus pulposus cells via activation of the BNIP3/AIF signalling pathway. Mol Med Rep 2017; 16:7253-7260. [PMID: 28944876 PMCID: PMC5865853 DOI: 10.3892/mmr.2017.7550] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 06/29/2017] [Indexed: 01/03/2023] Open
Abstract
Nutrient deprivation (ND)-induced nucleus pulposus (NP) cell death serves an important role in intervertebral disc degeneration disease. However, the underlying mechanisms have yet to be thoroughly elucidated. The present study created a cell culture model under ND conditions to investigate the roles of the nutrient-sensitive protein B-cell lymphoma 2/adenovirus E1B 19 kDa-interacting protein (BNIP3) and the mitochondrial pro-death protein apoptosis-inducing factor (AIF) in the death pathway of NP cells. The present study demonstrated that cells subjected to ND for up to 72 h exhibited a time-dependent increase in cell death and decrease in mitochondrial membrane potential (Δψm), as compared with cells cultured under normal conditions. The results of western blotting demonstrated that BNIP3 expression was significantly upregulated in NP cells subjected to ND for 24 h, which coincided with AIF translocation to the cell nucleus and alterations in cell viability and Δψm. Furthermore, BNIP3 overexpression increased ND-induced NP cell death, whereas knockdown of BNIP3 or AIF abolished ND-induced NP cell death. In addition, BNIP3 overexpression increased AIF expression and BNIP3 knockdown decreased AIF expression in NP cells subjected to ND. In conclusion, ND induced NP cell death partially via activation of the BNIP3/AIF signalling pathway. These findings provide novel insights into the potential mechanisms underlying ND-induced death of NP cells during disc degeneration.
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Affiliation(s)
- Jie Liu
- Department of Orthopaedics, The First People's Hospital of Yunnan, Kunming, Yunnan 650032, P.R. China
| | - Chao Yuan
- Department of Orthopaedics, Xinqiao Hospital, The Third Military Medical University, Chongqing 400038, P.R. China
| | - Luqiao Pu
- Department of Orthopaedics, Xinqiao Hospital, The Third Military Medical University, Chongqing 400038, P.R. China
| | - Jian Wang
- Department of Orthopaedics, Xinqiao Hospital, The Third Military Medical University, Chongqing 400038, P.R. China
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11
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He Z, Pu L, Yuan C, Jia M, Wang J. Nutrition deficiency promotes apoptosis of cartilage endplate stem cells in a caspase-independent manner partially through upregulating BNIP3. Acta Biochim Biophys Sin (Shanghai) 2017; 49:25-32. [PMID: 27864279 DOI: 10.1093/abbs/gmw111] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 10/09/2016] [Indexed: 01/07/2023] Open
Abstract
Nutrition deficiency is reported to induce apoptosis of chondrocytes and degeneration of cartilage endplate (CEP) in rabbit. Cartilage endplate stem cells (CESCs) are important for the integrity of structure and function of CEP. Bcl-2/adenovirus E1B 19-kDa-interacting protein 3 (BNIP3) has been reported to regulate apoptosis, autophagy, and cytoprotection. In this study, we aimed to determine whether nutrition deficiency induces apoptosis of CESCs, and whether or not the BNIP3-related pathway is activated in CESCs during nutrition deficiency. CESCs isolated from degenerated human CEP were cultured under normal or nutrition-deficient condition. Then, apoptosis was analyzed by flow cytometry. The expression and intracellular localization of BNIP3 were detected by quantitative real-time polymerase chain reaction, western blot analysis, and immunofluorescence assay, respectively. Mitochondrial membrane potential (MMP) and caspase-3 activity were measured by JC-1 staining and caspase-3 activity assay. Our results showed that nutrition deficiency promotes apoptosis and BNIP3 expression in CESCs. Notably, knockdown of BNIP3 could partially decrease nutrition deficiency-induced apoptosis of CESCs. In addition, nutrition deficiency could also induce upregulation of BNIP3, resulting in mitochondrial translocation of BNIP3 and loss of MMP in CESCs in a time-dependent manner. However, nutrition deficiency showed no effects on caspase-3 activity in CESCs. In summary, nutrition deficiency may promote CESC apoptosis partially through upregulating BNIP3, which might lead to activation of the BNIP3-related pathway and apoptosis of CESCs in a caspase-independent manner.
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Affiliation(s)
- Zhiliang He
- Department of Orthopedics, Xinqiao Hospital, Third Military Medical University, Chongqing 400038, China
| | - Luqiao Pu
- Department of Orthopedics, Xinqiao Hospital, Third Military Medical University, Chongqing 400038, China
| | - Chao Yuan
- Department of Orthopedics, Xinqiao Hospital, Third Military Medical University, Chongqing 400038, China
| | - Min Jia
- Department of Orthopedics, Xinqiao Hospital, Third Military Medical University, Chongqing 400038, China
| | - Jian Wang
- Department of Orthopedics, Xinqiao Hospital, Third Military Medical University, Chongqing 400038, China
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Kliminski V, Uziel O, Kessler-Icekson G. Popdc1/Bves Functions in the Preservation of Cardiomyocyte Viability While Affecting Rac1 Activity and Bnip3 Expression. J Cell Biochem 2016; 118:1505-1517. [PMID: 27886395 DOI: 10.1002/jcb.25810] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 11/23/2016] [Indexed: 01/15/2023]
Abstract
The Popeye domain containing1, also called Bves (Popdc1/Bves), is a transmembrane protein that functions in muscle regeneration, heart rate regulation, hypoxia tolerance, and ischemia preconditioning. The expression of Popdc1/Bves is elevated in cardiomyocytes maintained in serum free defined medium. We hypothesized that Popdc1/Bves is important for cardiomyocyte survival under the stress of serum deprivation and investigated the mechanisms involved. A deficit in Popdc1/Bves, achieved by siRNA-mediated gene silencing, results in cardiomyocyte injury and death, upregulation of the pro-apoptotic protein Bcl-2/adenovirus E1B 19-kDa interacting protein3 (Bnip3), as well as reduction in Rac1-GTPase activity and in Akt phosphorylation. Combined Popdc1/Bves and Bnip3 silencing attenuated cell injury and prevented Bnip3 upregulation induced by the silencing of Popdc1/Bves alone. Chromatin immunoprecipitation indicated an increased binding of the transcription factor FoxO3 to the Bnip3 promoter although augmentation of FoxO3 in the nuclei was not detected. By contrast, the transcription factor NFκB was excluded from the nuclei of Popdc1/Bves deficient cardiomyocytes and exhibited decreased binding to the Bnip3 promoter. The data indicates that Popdc1/Bves plays a role in the preservation of cardiomyocyte viability under serum deficiency through the alteration of Rac1 activity and the regulation of Bnip3 expression by FoxO3 and NFκB transcription factors pointing to Popdc1/Bves as a potential target to enhance heart protection. J. Cell. Biochem. 118: 1505-1517, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Vitaly Kliminski
- The Felsenstein Medical Research Center, Sackler Faculty of Medicine and Rabin Medical Center, Tel-Aviv University, Tel-Aviv, Israel
| | - Orit Uziel
- The Felsenstein Medical Research Center, Sackler Faculty of Medicine and Rabin Medical Center, Tel-Aviv University, Tel-Aviv, Israel
| | - Gania Kessler-Icekson
- The Felsenstein Medical Research Center, Sackler Faculty of Medicine and Rabin Medical Center, Tel-Aviv University, Tel-Aviv, Israel
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Liu KE, Frazier WA. Phosphorylation of the BNIP3 C-Terminus Inhibits Mitochondrial Damage and Cell Death without Blocking Autophagy. PLoS One 2015; 10:e0129667. [PMID: 26102349 PMCID: PMC4477977 DOI: 10.1371/journal.pone.0129667] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 05/11/2015] [Indexed: 11/24/2022] Open
Abstract
BNIP3 is a dual function protein, able to activate autophagy and induce cell death. Upon expression of BNIP3, which is upregulated by hypoxia, the protein induces mitochondrial dysfunction, often leading to cell death. However, some highly respiring cells and cancer cells tolerate BNIP3 expression, suggesting that a yet unknown mechanism exists to restrain the lethal effects of BNIP3 on mitochondria. Here we present evidence that BNIP3 undergoes several phosphorylation events at its C-terminus, adjacent to the transmembrane domain. Phosphorylation at these residues inhibits BNIP3-induced mitochondrial damage, preventing a loss of mitochondrial mass and mitochondrial membrane potential, as well as preventing an increase in reactive oxygen species. This decrease in mitochondrial damage, as well as the reduction of cell death upon C-terminal BNIP3 phosphorylation, can be explained by a diminished interaction between BNIP3 and OPA1, a key regulator of mitochondrial fusion and mitochondrial inner membrane structure. Importantly, phosphorylation of these C-terminal BNIP3 residues blocks cell death without preventing autophagy, providing evidence that the two functional roles of BNIP3 can be regulated independently. These findings establish phosphorylation as a switch to determine the pro-survival and pro-death effects of the protein. Our findings also suggest a novel target for the regulation of these activities in transformed cells where BNIP3 is often highly expressed.
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Affiliation(s)
- Katherine E. Liu
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - William A. Frazier
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
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Ding L, Wu JP, Xu G, Zhu B, Zeng QM, Li DF, Lu W. Lentiviral-mediated RNAi targeting caspase-3 inhibits apoptosis induced by serum deprivation in rat endplate chondrocytes in vitro. ACTA ACUST UNITED AC 2014; 47:445-51. [PMID: 24878605 PMCID: PMC4086170 DOI: 10.1590/1414-431x20143198] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2013] [Accepted: 02/20/2014] [Indexed: 01/27/2023]
Abstract
Current studies find that degenerated cartilage endplates (CEP) of vertebrae, with
fewer diffusion areas, decrease nutrient supply and accelerate intervertebral disc
degeneration. Many more apoptotic cells have been identified in degenerated than in
normal endplates, and may be responsible for the degenerated grade. Previous findings
suggest that inhibition of apoptosis is one possible approach to improve disc
regeneration. It is postulated that inhibition of CEP cell apoptosis may be
responsible for the regeneration of endplates. Caspase-3, involved in the execution
phase of apoptosis, is a candidate for regulating the apoptotic process. In the
present study, CEP cells were incubated in 1% fetal bovine serum. Activated caspases
were detected to identify the apoptotic pathway, and apoptosis was quantified by flow
cytometry. Lentiviral caspase-3 short hairpin RNA (shRNA) was employed to study its
protective effects against serum deprivation. Silencing of caspase-3 expression was
quantified by reverse transcription-polymerase chain reaction and Western blots, and
inhibition of apoptosis was quantified by flow cytometry. Serum deprivation increased
apoptosis of rat CEP cells through activation of a caspase cascade. Lentiviral
caspase-3 shRNA was successfully transduced into CEP cells, and specifically silenced
endogenous caspase-3 expression. Surviving cells were protected by the downregulation
of caspase-3 expression and activation. Thus, lentiviral caspase-3 shRNA-mediated
RNAi successfully silenced endogenous caspase-3 expression, preventing inappropriate
or premature apoptosis.
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Affiliation(s)
- L Ding
- Department of Orthopaedics, Jinshan Hospital, Fudan University, China
| | - J P Wu
- Department of Orthopaedics, Jinshan Hospital, Fudan University, China
| | - G Xu
- Center Laboratory, Jinshan Hospital, Fudan University, China
| | - B Zhu
- Department of Orthopaedics, Jinshan Hospital, Fudan University, China
| | - Q M Zeng
- Department of Orthopaedics, Jinshan Hospital, Fudan University, China
| | - D F Li
- Department of Orthopaedics, Jinshan Hospital, Fudan University, China
| | - W Lu
- Department of Orthopaedics, Jinshan Hospital, Fudan University, China
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15
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