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Xu X, Wang J, Xia Y, Yin Y, Zhu T, Chen F, Hai C. Autophagy, a double-edged sword for oral tissue regeneration. J Adv Res 2024; 59:141-159. [PMID: 37356803 PMCID: PMC11081970 DOI: 10.1016/j.jare.2023.06.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 06/10/2023] [Accepted: 06/20/2023] [Indexed: 06/27/2023] Open
Abstract
BACKGROUND Oral health is of fundamental importance to maintain systemic health in humans. Stem cell-based oral tissue regeneration is a promising strategy to achieve the recovery of impaired oral tissue. As a highly conserved process of lysosomal degradation, autophagy induction regulates stem cell function physiologically and pathologically. Autophagy activation can serve as a cytoprotective mechanism in stressful environments, while insufficient or over-activation may also lead to cell function dysregulation and cell death. AIM OF REVIEW This review focuses on the effects of autophagy on stem cell function and oral tissue regeneration, with particular emphasis on diverse roles of autophagy in different oral tissues, including periodontal tissue, bone tissue, dentin pulp tissue, oral mucosa, salivary gland, maxillofacial muscle, temporomandibular joint, etc. Additionally, this review introduces the molecular mechanisms involved in autophagy during the regeneration of different parts of oral tissue, and how autophagy can be regulated by small molecule drugs, biomaterials, exosomes/RNAs or other specific treatments. Finally, this review discusses new perspectives for autophagy manipulation and oral tissue regeneration. KEY SCIENTIFIC CONCEPTS OF REVIEW Overall, this review emphasizes the contribution of autophagy to oral tissue regeneration and highlights the possible approaches for regulating autophagy to promote the regeneration of human oral tissue.
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Affiliation(s)
- Xinyue Xu
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases and Shaanxi Engineering Research Center for Dental Materials and Advanced Manufacture, Department of Periodontology, School of Stomatology, Fourth Military Medical University, Xi'an, PR China; Shaanxi Key Lab of Free Radical Biology and Medicine, Fourth Military Medical University, Xi'an, PR China
| | - Jia Wang
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases and Shaanxi Engineering Research Center for Dental Materials and Advanced Manufacture, Department of Periodontology, School of Stomatology, Fourth Military Medical University, Xi'an, PR China
| | - Yunlong Xia
- Shaanxi Key Lab of Free Radical Biology and Medicine, Fourth Military Medical University, Xi'an, PR China; Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi'an, PR China
| | - Yuan Yin
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases and Shaanxi Engineering Research Center for Dental Materials and Advanced Manufacture, Department of Periodontology, School of Stomatology, Fourth Military Medical University, Xi'an, PR China
| | - Tianxiao Zhu
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases and Shaanxi Engineering Research Center for Dental Materials and Advanced Manufacture, Department of Periodontology, School of Stomatology, Fourth Military Medical University, Xi'an, PR China; Shaanxi Key Lab of Free Radical Biology and Medicine, Fourth Military Medical University, Xi'an, PR China
| | - Faming Chen
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases and Shaanxi Engineering Research Center for Dental Materials and Advanced Manufacture, Department of Periodontology, School of Stomatology, Fourth Military Medical University, Xi'an, PR China
| | - Chunxu Hai
- Shaanxi Key Lab of Free Radical Biology and Medicine, Fourth Military Medical University, Xi'an, PR China.
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Resveratrol protects osteocytes against oxidative stress in ovariectomized rats through AMPK/JNK1-dependent pathway leading to promotion of autophagy and inhibition of apoptosis. Cell Death Dis 2023; 9:16. [PMID: 36681672 PMCID: PMC9867734 DOI: 10.1038/s41420-023-01331-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 01/09/2023] [Accepted: 01/11/2023] [Indexed: 01/22/2023]
Abstract
A large number of studies in recent years indicate that osteocytes are the orchestrators of bone remodeling by regulating both osteoblast and osteoclast activities. Oxidative stress-induced osteocyte apoptosis plays critical roles in the pathological processes of postmenopausal osteoporosis. Resveratrol is a natural polyphenolic compound that ameliorates postmenopausal osteoporosis. However, whether resveratrol regulates osteocyte apoptosis via autophagy remains largely unknown. The effects of resveratrol on regulating osteocyte apoptosis and autophagy were analyzed both in vivo and in vitro. In vitro, cultured MLO-Y4 cells were exposed to H2O2 with or without resveratrol. In vivo, an ovariectomy-induced osteoporosis model was constructed in rats with or without daily intraperitoneal injection of 10 mg/kg body weight resveratrol. It was found that resveratrol attenuated H2O2-induced apoptosis through activating autophagy in cultured MLO-Y4 cells, which was mediated by the dissociation of Beclin-1/Bcl-2 complex in AMPK/JNK1-dependent pathway, ultimately regulating osteocytes function. Furthermore, it was shown that resveratrol treatment reduced osteocytes oxidative stress, inhibited osteocytes apoptosis and promoted autophagy in ovariectomized rats. Our study suggests that resveratrol protects against oxidative stress by restoring osteocytes autophagy and alleviating apoptosis via AMPK/JNK1 activation, therefore dissociating Bcl-2 from Beclin-1.
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Chen D, Zhang C, Luo J, Deng H, Yang J, Chen S, Zhang P, Dong L, Chang T, Tang ZH. Activated autophagy of innate immune cells during the early stages of major trauma. Front Immunol 2023; 13:1090358. [PMID: 36713435 PMCID: PMC9879135 DOI: 10.3389/fimmu.2022.1090358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Accepted: 12/15/2022] [Indexed: 01/15/2023] Open
Abstract
Background Trauma-induced immune dysfunction has been a major barrier to achieving reduced mortality, which is poorly understood. Autophagy is a crucial catabolic mechanism of immune cells during times of stress. Few studies have investigated the immune regulatory effects induced by autophagy after trauma. Here, we use single-cell transcriptomics analysis in a major trauma cohort to demonstrate the dominant role of autophagy in innate immune cells during the early stages of major trauma. Method Single-cell transcriptional profiling of peripheral blood mononuclear cells (PBMCs) was performed, which were sampled from three control participants and five major trauma patients within 6 hours of injury. In detail, after single-cell RNA-sequence data processing, cell type annotation and cluster marker identification were performed. A genetic toolbox with 604 autophagy-related genes was used to monitor the autophagy levels in immune cells. In addition, all transcriptome RNA sequencing data obtained from PBMCs in a cohort of 167 major trauma patients were downloaded from gene expression omnibus (GEO) datasets (GSE36809). Key deregulated biological processes and important autophagic hub genes involved in immune cells were identified by weighted gene co-expression network analysis and gene ontology enrichment analysis. Results A total of 20,445 differentially expressed genes were identified and five co-expression modules were constructed. Enrichment analysis indicated that activated autophagy is the most important biological process during the early stages of major trauma, and JMY (autophagy-related genes) were identified as hub genes. The single-cell transcriptional profiling of PBMCs demonstrated that all components of adaptive immune cells were significantly decreased, whereas components of innate immune cells (monocytes and neutrophils) were significantly increased in major trauma patients compared with control participants. Activated autophagy was detected in monocytes and neutrophils by monitoring the dynamic transcriptional signature of the autophagy-related genetic toolbox. Biological process analysis shows that antigen uptake, processing presentation, and major histocompatibility complex (MHC) class II protein complex assembly pathways were up-regulated in autophagy-positive monocytes, whereas antigen processing and presentation of endogenous antigen and type I interferon signaling pathways were up-regulated in autophagy-positive neutrophils during the early stages of major trauma. Conclusion Our study demonstrated that autophagy is a biological process crucial to the development of immune disorders in the early stages of major trauma. Furthermore, the results of our study generated a comprehensive single-cell immune landscape for major trauma patients, in which we determined that autophagy profoundly affects the main functions of innate immune cells and provides insight into the cellular basis of immune dysregulation after major trauma.
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Li Z, Li D, Chen R, Gao S, Xu Z, Li N. Cell death regulation: A new way for natural products to treat osteoporosis. Pharmacol Res 2023; 187:106635. [PMID: 36581167 DOI: 10.1016/j.phrs.2022.106635] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Revised: 12/11/2022] [Accepted: 12/24/2022] [Indexed: 12/27/2022]
Abstract
Osteoporosis is a common metabolic bone disease that results from the imbalance of homeostasis within the bone. Intra-bone homeostasis is dependent on a precise dynamic balance between bone resorption by osteoclasts and bone formation by mesenchymal lineage osteoblasts, which comprises a series of complex and highly standardized steps. Programmed cell death (PCD) (e.g., apoptosis, autophagy, ferroptosis, pyroptosis, and necroptosis) is a cell death process that involves a cascade of gene expression events with tight structures. These events play a certain role in regulating bone metabolism by determining the fate of bone cells. Moreover, existing research has suggested that natural products derived from a wide variety of dietary components and medicinal plants modulate the PCDs based on different mechanisms, which show great potential for the prevention and treatment of osteoporosis, thus revealing the emergence of more acceptable complementary and alternative drugs with lower costs, fewer side effects and more long-term application. Accordingly, this review summarizes the common types of PCDs in the field of osteoporosis. Moreover, from the perspective of targeting PCDs, this review also discussed the roles of currently reported natural products in the treatment of osteoporosis and the involved mechanisms. Based on this, this review provides more insights into new molecular mechanisms of osteoporosis and provides a reference for developing more natural anti-osteoporosis drugs in the future.
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Affiliation(s)
- Zhichao Li
- First College of Clinical Medicine, Shandong University of Traditional Chinese Medicine, Jinan 250014, China
| | - Dandan Li
- College of Integrated Traditional Chinese and Western Medicine, Hebei University of Chinese Medicine, Shijiazhuang 050011, China
| | - Renchang Chen
- First College of Clinical Medicine, Shandong University of Traditional Chinese Medicine, Jinan 250014, China
| | - Shang Gao
- First College of Clinical Medicine, Shandong University of Traditional Chinese Medicine, Jinan 250014, China
| | - Zhanwang Xu
- First College of Clinical Medicine, Shandong University of Traditional Chinese Medicine, Jinan 250014, China; Department of Orthopedics, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan 250014, China
| | - Nianhu Li
- First College of Clinical Medicine, Shandong University of Traditional Chinese Medicine, Jinan 250014, China; Department of Orthopedics, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan 250014, China.
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Li Z, Li D, Su H, Xue H, Tan G, Xu Z. Autophagy: An important target for natural products in the treatment of bone metabolic diseases. Front Pharmacol 2022; 13:999017. [DOI: 10.3389/fphar.2022.999017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 11/08/2022] [Indexed: 11/19/2022] Open
Abstract
Bone homeostasis depends on a precise dynamic balance between bone resorption and bone formation, involving a series of complex and highly regulated steps. Any imbalance in this process can cause disturbances in bone metabolism and lead to the development of many associated bone diseases. Autophagy, one of the fundamental pathways for the degradation and recycling of proteins and organelles, is a fundamental process that regulates cellular and organismal homeostasis. Importantly, basic levels of autophagy are present in all types of bone-associated cells. Due to the cyclic nature of autophagy and the ongoing bone metabolism processes, autophagy is considered a new participant in bone maintenance. Novel therapeutic targets have emerged as a result of new mechanisms, and bone metabolism can be controlled by interfering with autophagy by focusing on certain regulatory molecules in autophagy. In parallel, several studies have reported that various natural products exhibit a good potential to mediate autophagy for the treatment of metabolic bone diseases. Therefore, we briefly described the process of autophagy, emphasizing its function in different cell types involved in bone development and metabolism (including bone marrow mesenchymal stem cells, osteoblasts, osteocytes, chondrocytes, and osteoclasts), and also summarized research advances in natural product-mediated autophagy for the treatment of metabolic bone disease caused by dysfunction of these cells (including osteoporosis, rheumatoid joints, osteoarthritis, fracture nonunion/delayed union). The objective of the study was to identify the function that autophagy serves in metabolic bone disease and the effects, potential, and challenges of natural products for the treatment of these diseases by targeting autophagy.
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Luo Y, Gou H, Chen X, Li L, Wang X, Xu Y. Lactate inhibits osteogenic differentiation of human periodontal ligament stem cells via autophagy through the MCT1-mTOR signaling pathway. Bone 2022; 162:116444. [PMID: 35589065 DOI: 10.1016/j.bone.2022.116444] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 05/11/2022] [Accepted: 05/11/2022] [Indexed: 11/02/2022]
Abstract
BACKGROUND Periodontal ligament stem cells (PDLSCs) play a crucial role in periodontal bone regeneration. Lactate used to be considered a waste product of glucose metabolism. In recent years, a few pieces of evidence revealed its roles in regulating the osteogenic differentiation of stem cells, but the standpoints were controversial. This study aims to investigate the effects and the mechanisms of lactate on the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs). METHODS The hPDLSCs were treated with different concentrations of lactic acid and lactate to differentiate the effects of the acidic PH and ion lactate. Proliferation and cytotoxicity were measured by Cell Counting Kit-8 (CCK8) assay and Live/Dead assay. The osteogenic differentiation of hPDLSCs was analyzed by alizarin red staining, alkaline phosphatase (ALP) staining, and then osteogenic proteins and genes were measured by western blot and reverse transcription-quantitative PCR (qRT-PCR). To investigate the potential signaling pathways, MCT1 inhibitor, G-protein inhibitors, and rapamycin were used, and then autophagy-related proteins and osteogenic proteins were measured by western blot. RESULTS The inhibition of lactic acid on the osteogenic differentiation of hPDLSCs was more significant than lactate at the same concentration. Lactate inhibited the expression of ALP which can be rescued by Gα inhibitor. Alizarin red staining, the protein expression levels of osteocalcin (OCN), osteoprotegerin (OPN), osterix (OSX), and beclin1, LC3-II/LC3-I were decreased by lactate and partly rescued by MCT1 inhibitor. Rapamycin restored the protein expression levels of beclin1, LC3-II/LC3-I and OCN, OPN, OSX under the high lactate conditions. CONCLUSIONS Lactate inhibits the expression of ALP via Gα subunit signaling, and inhibits mineralized nodules formation and the expression of osteogenic-related proteins via reducing autophagy through the MCT1-mTOR signaling pathway.
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Affiliation(s)
- Ying Luo
- Jiangsu Province Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, People's Republic of China; Department of Periodontics, The Affiliated Stomatological Hospital of Nanjing Medical University, Nanjing, People's Republic of China; Jiangsu Province Engineering Research Center of Stomatological Translational Medicine, Nanjing, People's Republic of China
| | - Huiqing Gou
- Jiangsu Province Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, People's Republic of China; Department of Periodontics, The Affiliated Stomatological Hospital of Nanjing Medical University, Nanjing, People's Republic of China; Jiangsu Province Engineering Research Center of Stomatological Translational Medicine, Nanjing, People's Republic of China
| | - Xu Chen
- Jiangsu Province Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, People's Republic of China; Department of Periodontics, The Affiliated Stomatological Hospital of Nanjing Medical University, Nanjing, People's Republic of China; Jiangsu Province Engineering Research Center of Stomatological Translational Medicine, Nanjing, People's Republic of China
| | - Lu Li
- Jiangsu Province Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, People's Republic of China; Department of Periodontics, The Affiliated Stomatological Hospital of Nanjing Medical University, Nanjing, People's Republic of China; Jiangsu Province Engineering Research Center of Stomatological Translational Medicine, Nanjing, People's Republic of China
| | - Xiaoqian Wang
- Jiangsu Province Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, People's Republic of China; Department of Periodontics, The Affiliated Stomatological Hospital of Nanjing Medical University, Nanjing, People's Republic of China; Jiangsu Province Engineering Research Center of Stomatological Translational Medicine, Nanjing, People's Republic of China
| | - Yan Xu
- Jiangsu Province Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, People's Republic of China; Department of Periodontics, The Affiliated Stomatological Hospital of Nanjing Medical University, Nanjing, People's Republic of China; Jiangsu Province Engineering Research Center of Stomatological Translational Medicine, Nanjing, People's Republic of China.
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Chen P, Liu Y, Liu W, Wang Y, Liu Z, Rong M. Impact of High-Altitude Hypoxia on Bone Defect Repair: A Review of Molecular Mechanisms and Therapeutic Implications. Front Med (Lausanne) 2022; 9:842800. [PMID: 35620712 PMCID: PMC9127390 DOI: 10.3389/fmed.2022.842800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 04/15/2022] [Indexed: 11/23/2022] Open
Abstract
Reaching areas at altitudes over 2,500–3,000 m above sea level has become increasingly common due to commerce, military deployment, tourism, and entertainment. The high-altitude environment exerts systemic effects on humans that represent a series of compensatory reactions and affects the activity of bone cells. Cellular structures closely related to oxygen-sensing produce corresponding functional changes, resulting in decreased tissue vascularization, declined repair ability of bone defects, and longer healing time. This review focuses on the impact of high-altitude hypoxia on bone defect repair and discusses the possible mechanisms related to ion channels, reactive oxygen species production, mitochondrial function, autophagy, and epigenetics. Based on the key pathogenic mechanisms, potential therapeutic strategies have also been suggested. This review contributes novel insights into the mechanisms of abnormal bone defect repair in hypoxic environments, along with therapeutic applications. We aim to provide a foundation for future targeted, personalized, and precise bone regeneration therapies according to the adaptation of patients to high altitudes.
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Affiliation(s)
- Pei Chen
- Department of Periodontology and Implantology, Stomatological Hospital, Southern Medical University, Guangzhou, China
| | - Yushan Liu
- Department of Periodontology and Implantology, Stomatological Hospital, Southern Medical University, Guangzhou, China
| | - Wenjing Liu
- Department of Prosthodontics, Stomatological Hospital, Southern Medical University, Guangzhou, China
| | - Yarong Wang
- Department of Periodontology and Implantology, Stomatological Hospital, Southern Medical University, Guangzhou, China
| | - Ziyi Liu
- Department of Periodontology and Implantology, Stomatological Hospital, Southern Medical University, Guangzhou, China
| | - Mingdeng Rong
- Department of Periodontology and Implantology, Stomatological Hospital, Southern Medical University, Guangzhou, China
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Song S, Guo Y, Yang Y, Fu D. Advances in pathogenesis and therapeutic strategies for osteoporosis. Pharmacol Ther 2022; 237:108168. [PMID: 35283172 DOI: 10.1016/j.pharmthera.2022.108168] [Citation(s) in RCA: 106] [Impact Index Per Article: 53.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 02/25/2022] [Accepted: 03/07/2022] [Indexed: 02/07/2023]
Abstract
Osteoporosis, is the most common bone disorder worldwide characterized by low bone mineral density, leaving affected bones vulnerable to fracture. Bone homeostasis depends on the precise balance between bone resorption by osteoclasts and bone matrix formation by mesenchymal lineage osteoblasts, and involves a series of complex and highly regulated steps. Bone homeostasis will be disrupted when the speed of bone resorption is faster than bone formation. Based on various regulatory mechanisms of bone homeostasis, a series of drugs targeting osteoporosis have emerged in clinical practice, including bisphosphonates, selective estrogen receptor modulators, calcitonin, molecular-targeted drugs and so on. However, many drugs have major adverse effects or are unsuitable for long-term use. Therefore, it is very urgent to find more effective therapeutic drugs based on the new pathogenesis of osteoporosis. In this review, we summarize novel mechanisms involved in the pathological process of osteoporosis, including the roles of gut microbiome, autophagy, iron balance and cellular senescence. Based on the above pathological mechanism, we found promising drugs for osteoporosis treatment, such as: probiotics, alpha-ketoglutarate, senolytics and hydrogen sulfide. This new finding may provide an important basis for elucidating the complex pathological mechanisms of osteoporosis and provide promising drugs for clinical osteoporosis treatment.
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Affiliation(s)
- Shasha Song
- College of Pharmacy, Shenzhen Technology University, Shenzhen 518118, PR China
| | - Yuanyuan Guo
- Department of Pharmacy, Liyuan Hospital, Tongji Medical School, Huazhong University of Science and Technology, Wuhan, Hubei 430077, PR China
| | - Yuehua Yang
- Department of Orthopedics, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, PR China
| | - Dehao Fu
- Department of Orthopedics, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, PR China.
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Xu K, Lu C, Ren X, Wang J, Xu P, Zhang Y. Overexpression of HIF-1α enhances the protective effect of mitophagy on steroid-induced osteocytes apoptosis. ENVIRONMENTAL TOXICOLOGY 2021; 36:2123-2137. [PMID: 34310007 DOI: 10.1002/tox.23327] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Revised: 07/01/2021] [Accepted: 07/07/2021] [Indexed: 06/13/2023]
Abstract
Glucocorticoid (GC; dexamethasone, DEX) -induced osteonecrosis of the femoral head (GIOFH) is a challenging orthopedic disease, and its underlying mechanism remains not clear. This study exposed murine long bone osteocyte-Y4 (MLO-Y4) cells to DEX below normoxic or hypoxic circumstances and found that cell autophagy have been reduced. At the same time, flow cytometry analysis showed increased apoptosis, which was more pronounced in hypoxic environments. Recent research also claimed that GC induces osteoporosis after osteocyte apoptosis, and subsequent microfractures lead to ischemia and hypoxia of the femoral head, resulted in GIOFH. Presently, we found that both mitophagy-related protein hypoxia-inducible factor-1α (HIF-1α) and BNIP3 were up-regulated in the hypoxic environment, and their expression was down-regulated when exposed to DEX. Besides, we demonstrated that overexpressing HIF-1α resisted DEX-induced apoptosis in a hypoxic environment. Here, we demonstrated that overexpression of HIF-1α, through its downstream marker BNIP3, reduced the suppression of DEX on mitophagy induced by hypoxia and protected bone cells from apoptosis. Also, these findings may provide a direction of the promising application for better GIOFH treatment shortly.
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Affiliation(s)
- Ke Xu
- Department of Orthopaedics of the First Affiliated Hospital, Medical School, Xi'an Jiaotong University, Xi'an, China
| | - Chao Lu
- Department of Joint Surgery, Hong Hui Hospital, Xi'an Jiaotong University, Xi'an, China
| | - Xiaoyu Ren
- Department of Joint Surgery, Hong Hui Hospital, Xi'an Jiaotong University, Xi'an, China
| | - Jing Wang
- Department of Orthopaedics of the First Affiliated Hospital, Medical School, Xi'an Jiaotong University, Xi'an, China
| | - Peng Xu
- Department of Joint Surgery, Hong Hui Hospital, Xi'an Jiaotong University, Xi'an, China
| | - Yingang Zhang
- Department of Orthopaedics of the First Affiliated Hospital, Medical School, Xi'an Jiaotong University, Xi'an, China
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Abstract
PURPOSE OF REVIEW In this review, we provide a recent update on bioenergetic pathways in osteocytes and identify potential future areas of research interest. Studies have identified a role for regulation of bone formation and bone resorption through osteocyte mechanosensing and osteocyte secreted factors. Nevertheless, there is a paucity of studies on the bioenergetics and energy metabolism of osteocytes, which are required for the regulation of bone remodeling. RECENT FINDINGS Osteocytes are cells of the osteoblast lineage embedded in bone. The osteocyte lacunocanalicular network within the skeletal matrix is exposed to a unique hypoxic environment. Therefore, the bioenergetic requirements of these cells could differ from other bone cells due to its location in the ossified matrix and its role in bone regulation transduced by mechanical signals. Recent findings highlighted in this review provide some evidence that metabolism of these cells is dependent on their location due to the substrates present in the microenvironment and metabolic cues from stress pathways. Both glycolysis (glucose metabolism) and oxidative phosphorylation (mitochondrial dynamics, ROS generation) affect osteocyte function and viability. In this review, we provide evidence that is currently available about information regarding bioenergetics pathways in osteocytes. We discuss published studies showing a role for hypoxia-driven glucose metabolism in regulating osteocyte bioenergetics. We also provide information on various substrates that osteocytes could utilize to fuel energetic needs, namely pyruvate, amino acids, and fatty acids. This is based on some preliminary experimental evidence that is available in literature. The role of parathyroid hormone PTH and parathryoid hormone-related peptide PTHrP in bone anabolism and resorption, along with regulation of metabolic pathways in the cells of the skeletal niche, needs to be explored further. Mitochondrial metabolism has a role in osteocyte bioenergetics through substrate utilization, location of the osteocyte in the bone cortex, and mitochondrial biogenesis. While there are limitations in studying metabolic flux in traditional cell lines, there are now novel cell lines and sophisticated tools available to study osteocyte bioenergetics to help harness its potential in vivo in the future.
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Affiliation(s)
- Vivin Karthik
- Center for Molecular Medicine, Maine Medical Center Research Institute, 81 Research Drive, Scarborough, ME, 04074, USA
- Graduate School of Biomedical Sciences and Engineering, University of Maine, Orono, ME, USA
| | - Anyonya R Guntur
- Center for Molecular Medicine, Maine Medical Center Research Institute, 81 Research Drive, Scarborough, ME, 04074, USA.
- Graduate School of Biomedical Sciences and Engineering, University of Maine, Orono, ME, USA.
- Tufts University School of Medicine, Tufts University, Boston, MA, USA.
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Zhao X, Huang B, Wang H, Ni N, He F, Liu Q, Shi D, Chen C, Zhao P, Wang X, Wagstaff W, Pakvasa M, Tucker AB, Lee MJ, Wolf JM, Reid RR, Hynes K, Strelzow J, Ho SH, Yu T, Yang J, Shen L, He TC, Zhang Y. A functional autophagy pathway is essential for BMP9-induced osteogenic differentiation of mesenchymal stem cells (MSCs). Am J Transl Res 2021; 13:4233-4250. [PMID: 34150011 PMCID: PMC8205769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Accepted: 03/15/2021] [Indexed: 06/12/2023]
Abstract
Mesenchymal stem cells (MSCs) are capable of differentiating into bone, cartilage and adipose tissues. We identified BMP9 as the most potent osteoinductive BMP although detailed mechanism underlying BMP9-regulated osteogenesis of MSCs is indeterminate. Emerging evidence indicates that autophagy plays a critical role in regulating bone homeostasis. We investigated the possible role of autophagy in osteogenic differentiation induced by BMP9. We showed that BMP9 upregulated the expression of multiple autophagy-related genes in MSCs. Autophagy inhibitor chloroquine (CQ) inhibited the osteogenic activity induced by BMP9 in MSCs. While overexpression of ATG5 or ATG7 did not enhance osteogenic activity induced by BMP9, silencing Atg5 expression in MSCs effectively diminished BMP9 osteogenic signaling activity and blocked the expression of the osteogenic regulator Runx2 and the late marker osteopontin induced by BMP9. Stem cell implantation study revealed that silencing Atg5 in MSCs profoundly inhibited ectopic bone regeneration and bone matrix mineralization induced by BMP9. Collectively, our results strongly suggest a functional autophagy pathway may play an essential role in regulating osteogenic differentiation induced by BMP9 in MSCs. Thus, restoration of dysregulated autophagic activity in MSCs may be exploited to treat fracture healing, bone defects or osteoporosis.
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Affiliation(s)
- Xia Zhao
- Department of Orthopaedic Surgery, The Affiliated Hospital of Qingdao UniversityQingdao 266061, China
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
| | - Bo Huang
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
- Department of Clinical Laboratory Medicine, The Second Affiliated Hospital of Nanchang UniversityNanchang 330031, China
| | - Hao Wang
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
- Ministry of Education Key Laboratory of Diagnostic Medicine, and School of Laboratory and Diagnostic Medicine, Chongqing Medical UniversityChongqing 400016, China
| | - Na Ni
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
- Ministry of Education Key Laboratory of Diagnostic Medicine, and School of Laboratory and Diagnostic Medicine, Chongqing Medical UniversityChongqing 400016, China
| | - Fang He
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
- Departments of Medicine/Gastroenterology, Orthopaedic Surgery, The First Affiliated Hospital of Chongqing Medical UniversityChongqing 400016, China
| | - Qing Liu
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
- Departments of Orthopaedic Surgery and Spine Surgery, Second Xiangya Hospital, Central South UniversityChangsha, China
| | - Deyao Shi
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
- Department of Orthopaedics, Union Hospital of Tongji Medical College, Huazhong University of Science and TechnologyWuhan, China
| | - Connie Chen
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
| | - Piao Zhao
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
- Departments of Medicine/Gastroenterology, Orthopaedic Surgery, The First Affiliated Hospital of Chongqing Medical UniversityChongqing 400016, China
| | - Xi Wang
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
- Ministry of Education Key Laboratory of Diagnostic Medicine, and School of Laboratory and Diagnostic Medicine, Chongqing Medical UniversityChongqing 400016, China
| | - William Wagstaff
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
| | - Mikhail Pakvasa
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
| | - Andrew Blake Tucker
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
| | - Michael J Lee
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
| | - Jennifer Moriatis Wolf
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
| | - Russell R Reid
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
- Section of Plastic Surgery and Laboratory of Craniofacial Biology and Development, and Section of Surgical Research, Department of Surgery, The University of Chicago Medical CenterChicago, IL 60637, USA
| | - Kelly Hynes
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
| | - Jason Strelzow
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
| | - Sherwin H Ho
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
| | - Tengbo Yu
- Department of Orthopaedic Surgery, The Affiliated Hospital of Qingdao UniversityQingdao 266061, China
| | - Jian Yang
- Department of Biomedical Engineering, Materials Research Institute, The Huck Institutes of The Life Sciences, The Pennsylvania State UniversityUniversity Park, PA 16802, USA
| | - Le Shen
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
- Section of Surgical Research, Department of Surgery, The University of Chicago Medical CenterChicago, IL 60637, USA
| | - Tong-Chuan He
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
- Section of Surgical Research, Department of Surgery, The University of Chicago Medical CenterChicago, IL 60637, USA
| | - Yongtao Zhang
- Department of Orthopaedic Surgery, The Affiliated Hospital of Qingdao UniversityQingdao 266061, China
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical CenterChicago, IL 60637, USA
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12
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Guo YF, Su T, Yang M, Li CJ, Guo Q, Xiao Y, Huang Y, Liu Y, Luo XH. The role of autophagy in bone homeostasis. J Cell Physiol 2021; 236:4152-4173. [PMID: 33452680 DOI: 10.1002/jcp.30111] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 09/24/2020] [Accepted: 10/05/2020] [Indexed: 12/15/2022]
Abstract
Autophagy is an evolutionarily conserved intracellular process and is considered one of the main catabolism pathways. In the process of autophagy, cells are digested nonselectively or selectively to recover nutrients and energy, so it is regarded as an antiaging process. In addition to the essential role of autophagy in cellular homeostasis, autophagy is a stress response mechanism for cell survival. Here, we review recent literature describing the pathway of autophagy and its role in different bone cell types, including osteoblasts, osteoclasts, and osteocytes. Also discussed is the mechanism of autophagy in bone diseases associated with bone homeostasis, including osteoporosis and Paget's disease. Finally, we discuss the application of autophagy regulators in bone diseases. This review aims to introduce autophagy, summarize the understanding of its relevance in bone physiology, and discuss its role and therapeutic potential in the pathogenesis of bone diseases such as osteoporosis.
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Affiliation(s)
- Yi-Fan Guo
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Tian Su
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Mi Yang
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Chang-Jun Li
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Qi Guo
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Ye Xiao
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Yan Huang
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Ya Liu
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Xiang-Hang Luo
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, Hunan, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital of Central South University, Changsha, Hunan, China
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13
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Yang Y, Huang Y, Li W. Autophagy and its significance in periodontal disease. J Periodontal Res 2020; 56:18-26. [PMID: 33247437 DOI: 10.1111/jre.12810] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 09/24/2020] [Accepted: 10/10/2020] [Indexed: 12/14/2022]
Abstract
Autophagy is an evolutionarily conserved process essential for cellular homeostasis and human health. As a lysosome-dependent degradation pathway, autophagy acts as a modulator of the pathogenesis of diverse diseases. The relationship between autophagy and oral diseases has been explored in recent years, and there is increasing interest in the role of autophagy in periodontal disease. Periodontal disease is a prevalent chronic inflammatory disorder characterized by the destruction of periodontal tissues. It is initiated through pathogenic bacterial infection and interacts with the host immune defense, leading to inflammation and alveolar bone resorption. In this review, we outline the machinery of autophagy and present an overview of work on the significance of autophagy in regulating pathogen invasion, the immune response, inflammation, and alveolar bone homeostasis of periodontal disease. Existing data provide support for the importance of autophagy as a multi-dimensional regulator in the pathogenesis of periodontal disease and demonstrate the importance of future research on the potential roles of autophagy in periodontal disease.
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Affiliation(s)
- Yuhui Yang
- Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, China
| | - Yiping Huang
- Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, China
| | - Weiran Li
- Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, China
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14
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Yang Y, Lin Z, Chen J, Ding S, Mao W, Shi S, Liang B. Autophagy in spinal ligament fibroblasts: evidence and possible implications for ossification of the posterior longitudinal ligament. J Orthop Surg Res 2020; 15:490. [PMID: 33092625 PMCID: PMC7579890 DOI: 10.1186/s13018-020-02017-6] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 10/14/2020] [Indexed: 12/18/2022] Open
Abstract
Background The molecular mechanisms of ossification of the posterior longitudinal ligament (OPLL) remain to be elucidated. The aim of the present study was to investigate the autophagy of spinal ligament fibroblasts derived from patients with OPLL and to examine whether autophagy-associated gene expression was correlated with the expression of osteogenic differentiation genes. Methods Expression of autophagy-associated genes was detected in 37 samples from 21 OPLL patients and 16 non-OPLL patients. The correlation of autophagy-associated gene expression and the expression of osteogenic differentiation genes was analyzed by Pearson’s correlation. The expression of autophagy-associated genes of ligament fibroblasts was assessed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), western blotting, and immunofluorescence. The incidence of autophagy was assessed by flow cytometry. After knockdown using small interfering RNA targeting Beclin1, the expression of osteogenic differentiation genes were compared in spinal ligament fibroblasts. Results In clinical specimens, mRNA expression levels of microtubule-associated protein 1 light chain 3 and Beclin1 were higher in the OPLL group compared with the non-OPLL group. Pearson correlation analysis demonstrated that Beclin1 expression was positively correlated with expression of osteocalcin (OCN) (r = 0.8233, P < 0.001), alkaline phosphatase, biomineralization associated (ALP) (r = 0.7821, P < 0.001), and collagen type 1 (COL 1) (r = 0.6078, P = 0.001). Consistently, the upregulation of autophagy-associated genes in ligament fibroblasts from patients with OPLL were further confirmed by western blotting and immunofluorescence. The incidence of autophagy was also increased in ligament fibroblasts from patients with OPLL. Furthermore, knockdown of Beclin1 led to a decrease in the expression of OCN, ALP, and COL 1 by 63.2% (P < 0.01), 52% (P < 0.01), and 53.2% (P < 0.01) in ligament fibroblasts from patients with OPLL, respectively. Conclusions Beclin1-mediated autophagy was involved in the osteogenic differentiation of ligament fibroblasts and promoted the development of OPLL.
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Affiliation(s)
- Yuehua Yang
- Department of Orthopaedics, The Fifth Affiliated Hospital, Southern Medical University, No. 566 Congcheng Avenue, Conghua District, Guangzhou, 510900, People's Republic of China.
| | - Zunwen Lin
- Department of Orthopedic Surgery, The First Affiliated Hospital, Nanchang University, No. 17, Yongwaizheng Street, Nanchang, 330006, Jiangxi, People's Republic of China
| | - Jiangwei Chen
- Department of Orthopedic Surgery, The First Affiliated Hospital, Nanchang University, No. 17, Yongwaizheng Street, Nanchang, 330006, Jiangxi, People's Republic of China
| | - Sheng Ding
- Department of Stomatology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, 1665, Kongjiang Road, Shanghai, 200092, People's Republic of China
| | - Weiwei Mao
- Department of Pediatric Neurosurgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, 1665, Kongjiang Road, Shanghai, 200092, People's Republic of China
| | - Sheng Shi
- Department of Orthopedics, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, 301 Middle Yanchang Road, Shanghai, 200072, People's Republic of China
| | - Biru Liang
- Department of Orthopaedics, The Fifth Affiliated Hospital, Southern Medical University, No. 566 Congcheng Avenue, Conghua District, Guangzhou, 510900, People's Republic of China
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15
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Osteocyte apoptosis: the roles and key molecular mechanisms in resorption-related bone diseases. Cell Death Dis 2020; 11:846. [PMID: 33046704 PMCID: PMC7552426 DOI: 10.1038/s41419-020-03059-8] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 09/23/2020] [Accepted: 09/24/2020] [Indexed: 01/18/2023]
Abstract
Vital osteocytes have been well known to function as an important orchestrator in the preservation of robustness and fidelity of the bone remodeling process. Nevertheless, some key pathological factors, such as sex steroid deficiency and excess glucocorticoids, and so on, are implicated in inducing a bulk of apoptotic osteocytes, subsequently resulting in resorption-related bone loss. As much, osteocyte apoptosis, under homeostatic conditions, is in an optimal state of balance tightly controlled by pro- and anti-apoptotic mechanism pathways. Importantly, there exist many essential signaling proteins in the process of osteocyte apoptosis, which has a crucial role in maintaining a homeostatic environment. While increasing in vitro and in vivo studies have established, in part, key signaling pathways and cross-talk mechanism on osteocyte apoptosis, intrinsic and complex mechanism underlying osteocyte apoptosis occurs in various states of pathologies remains ill-defined. In this review, we discuss not only essential pro- and anti-apoptotic signaling pathways and key biomarkers involved in these key mechanisms under different pathological agents, but also the pivotal role of apoptotic osteocytes in osteoclastogenesis-triggered bone loss, hopefully shedding new light on the attractive and proper actions of pharmacotherapeutics of targeting apoptosis and ensuing resorption-related bone diseases such as osteoporosis and fragility fractures.
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16
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Montaseri A, Giampietri C, Rossi M, Riccioli A, Fattore AD, Filippini A. The Role of Autophagy in Osteoclast Differentiation and Bone Resorption Function. Biomolecules 2020; 10:E1398. [PMID: 33008140 PMCID: PMC7601508 DOI: 10.3390/biom10101398] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 09/28/2020] [Accepted: 09/29/2020] [Indexed: 12/11/2022] Open
Abstract
Autophagy is an evolutionary conserved and highly regulated recycling process of cellular wastes. Having a housekeeping role, autophagy through the digestion of domestic cytosolic organelles, proteins, macromolecules, and pathogens, eliminates unnecessary materials and provides nutrients and energy for cell survival and maintenance. The critical role of autophagy and autophagy-related proteins in osteoclast differentiation, bone resorption, and maintenance of bone homeostasis has previously been reported. Increasing evidence reveals that autophagy dysregulation leads to alteration of osteoclast function and enhanced bone loss, which is associated with the onset and progression of osteoporosis. In this review, we briefly consolidate the current state-of-the-art technology regarding the role of autophagy in osteoclast function in both physiologic and pathologic conditions to have a more general view on this issue.
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Affiliation(s)
- Azadeh Montaseri
- Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, Unit of Histology and Medical Embryology, Sapienza University of Rome, 00161 Rome, Italy; (A.M.); (A.R.); (A.F.)
| | - Claudia Giampietri
- Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, Unit of Human Anatomy, Sapienza University of Rome, 00161 Rome, Italy;
| | - Michela Rossi
- Bone Physiopathology Research Unit, Genetics and Rare Diseases Research Division, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy;
| | - Anna Riccioli
- Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, Unit of Histology and Medical Embryology, Sapienza University of Rome, 00161 Rome, Italy; (A.M.); (A.R.); (A.F.)
| | - Andrea Del Fattore
- Bone Physiopathology Research Unit, Genetics and Rare Diseases Research Division, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy;
| | - Antonio Filippini
- Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, Unit of Histology and Medical Embryology, Sapienza University of Rome, 00161 Rome, Italy; (A.M.); (A.R.); (A.F.)
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17
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Moss JJ, Hammond CL, Lane JD. Zebrafish as a model to study autophagy and its role in skeletal development and disease. Histochem Cell Biol 2020; 154:549-564. [PMID: 32915267 PMCID: PMC7609422 DOI: 10.1007/s00418-020-01917-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/31/2020] [Indexed: 12/13/2022]
Abstract
In the last twenty years, research using zebrafish as a model organism has increased immensely. With the many advantages that zebrafish offer such as high fecundity, optical transparency, ex vivo development, and genetic tractability, they are well suited to studying developmental processes and the effect of genetic mutations. More recently, zebrafish models have been used to study autophagy. This important protein degradation pathway is needed for cell and tissue homeostasis in a variety of contexts. Correspondingly, its dysregulation has been implicated in multiple diseases including skeletal disorders. In this review, we explore how zebrafish are being used to study autophagy in the context of skeletal development and disease, and the ways these areas are intersecting to help identify potential therapeutic targets for skeletal disorders.
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Affiliation(s)
- Joanna J Moss
- School of Biochemistry, Biomedical Sciences Building, University of Bristol, Bristol, UK.,School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, Bristol, UK
| | - Chrissy L Hammond
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, Bristol, UK.
| | - Jon D Lane
- School of Biochemistry, Biomedical Sciences Building, University of Bristol, Bristol, UK.
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18
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The Function and Mechanisms of Autophagy in Trauma of Other Parts of the Body. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020. [PMID: 32671783 DOI: 10.1007/978-981-15-4272-5_48] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register]
Abstract
Trauma is common in modern society. Besides TBI and SCI, trauma can lead to severe cardiopulmonary injury and even to death. Fracture and skin injury are also very likely to occur in our daily life. Limited studies have reported the levels of autophagy after heart and trauma, fracture, and skin injury. In this chapter, we update the current state of knowledge and recent advances in the study of autophagy after trauma including heart and lung trauma, fracture, and skin injury which we try to clarify how autophagy levels are affected by injury or trauma and how their manipulation may represent potential novel protective targets for treatments.
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19
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Li X, Xu J, Dai B, Wang X, Guo Q, Qin L. Targeting autophagy in osteoporosis: From pathophysiology to potential therapy. Ageing Res Rev 2020; 62:101098. [PMID: 32535273 DOI: 10.1016/j.arr.2020.101098] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/26/2020] [Accepted: 06/03/2020] [Indexed: 12/19/2022]
Abstract
Osteoporosis is a highly prevalent disorder characterized by the loss of bone mass and microarchitecture deterioration of bone tissue, attributed to various factors, including menopause (primary), aging (primary) and adverse effects of relevant medications (secondary). In recent decades, knowledge regarding the etiological mechanisms underpinning osteoporosis emphasizes that bone cellular homeostasis, including the maintenance of cell functions, differentiation, and the response to stress, is tightly regulated by autophagy, which is a cell survival mechanism for eliminating and recycling damaged proteins and organelles. With the important roles in the maintenance of cellular homeostasis and organ function, autophagy has emerged as a potential target for the prevention and treatment of osteoporosis. In this review, we update and discuss the pathophysiology of autophagy in normal bone cell life cycle and metabolism. Then, the alternations of autophagy in primary and secondary osteoporosis, and the accompanied pathological process are discussed. Finally, we discuss current strategies, limitations, and challenges involved in targeting relevant pathways and propose strategies by which such hurdles may be circumvented in the future for their translation into clinical validations and applications for the prevention and treatment of osteoporosis.
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20
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Yang Y, Lin Z, Cheng J, Ding S, Mao WW, Shi S, Liang B, Jiang L. The roles of autophagy in osteogenic differentiation in rat ligamentum fibroblasts: Evidence and possible implications. FASEB J 2020; 34:8876-8886. [PMID: 32510740 DOI: 10.1096/fj.201903216rr] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 05/12/2020] [Accepted: 05/15/2020] [Indexed: 12/27/2022]
Abstract
Autophagy, a macromolecular degradation process, plays a pivotal role in cell differentiation and survival. This study was designed to investigate the role of autophagy in the osteogenic differentiation in ligamentum fibroblasts. Rat ligamentum fibroblasts were isolated from the posterior longitudinal ligament and cultured in osteogenic induction medium. Ultrastructural analysis, immunofluorescence assay, western blot, flow cytometry, and lysosomal activity assessment were performed to determine the presence and activity of autophagy in the cells. The mineralization deposit and osteogenic gene expressions were evaluated to classify the association between autophagy activity and the bone formation ability of the spinal ligament cells. The influence of leptin and endothelin-1 on the autophagy activity was also evaluated. Our study demonstrated that autophagy was present and increased in the ligament cells under osteogenic induction. Inhibition of autophagy with either pharmacologic inhibitors (Bafilomycin A and 3-methyladenine) or Belcin1 (BECN1) knocking down weakened the mineralization capacity, decreased the gene expressions of COL1A1, osteocalcin (Ocn), and runt-related transcription factor 2 (Runx2) in the ligamentum fibroblasts and increased cell apoptosis. The Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK)-BECN1 autophagic pathway was activated in the osteogenic differentiating ligamentum fibroblasts. Leptin significantly increased the autophagy activity in the ligament cells under osteogenic induction. These discoveries might improve our understanding for the mechanism of ossification of the posterior longitudinal ligament (OPLL) and provide new approaches on the prevention and treatment of this not uncommon disease.
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Affiliation(s)
- Yuehua Yang
- Spine Center, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.,Department of Orthopaedics, Fifth Affiliated Hospital, Southern Medical University, Guangzhou, P.R. China
| | - Zunwen Lin
- Department of Orthopedic Surgery, First Affiliated Hospital, Nanchang University, Jiangxi, P.R. China
| | - Jiangwei Cheng
- Department of Orthopedic Surgery, First Affiliated Hospital, Nanchang University, Jiangxi, P.R. China
| | - Sheng Ding
- Department of Stomatology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
| | - Wei-Wei Mao
- Department of Pediatric Neurosurgery, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
| | - Sheng Shi
- Department of Orthopedics, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, P.R. China
| | - Biru Liang
- Department of Orthopaedics, Fifth Affiliated Hospital, Southern Medical University, Guangzhou, P.R. China
| | - Leisheng Jiang
- Spine Center, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
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21
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Wang T, He H, Liu S, Jia C, Fan Z, Zhong C, Yu J, Liu H, He C. Autophagy: A Promising Target for Age-related Osteoporosis. Curr Drug Targets 2020; 20:354-365. [PMID: 29943700 DOI: 10.2174/1389450119666180626120852] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 06/07/2018] [Accepted: 06/18/2018] [Indexed: 02/08/2023]
Abstract
Autophagy is a process the primary role of which is to clear up damaged cellular components such as long-lived proteins and organelles, thus participating in the conservation of different cells. Osteoporosis associated with aging is characterized by consistent changes in bone metabolism with suppression of bone formation as well as increased bone resorption. In advanced age, not only bone mass but also bone strength decrease in both sexes, resulting in an increased incidence of fractures. Clinical and animal experiments reveal that age-related bone loss is associated with many factors such as accumulation of autophagy, increased levels of reactive oxygen species, sex hormone deficiency, and high levels of endogenous glucocorticoids. Available basic and clinical studies indicate that age-associated factors can regulate autophagy. Those factors play important roles in bone remodeling and contribute to decreased bone mass and bone strength with aging. In this review, we summarize the mechanisms involved in bone metabolism related to aging and autophagy, supplying a theory for therapeutic targets to rescue bone mass and bone strength in older people.
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Affiliation(s)
- Tiantian Wang
- Department of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Hongchen He
- Department of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Shaxin Liu
- Department of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Chengsen Jia
- Department of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Ziyan Fan
- Department of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Can Zhong
- Department of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Jiadan Yu
- Department of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Honghong Liu
- Department of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Chengqi He
- Department of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Rehabilitation Medicine, West China Hospital, Sichuan University, Chengdu, China
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22
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Autophagy in bone homeostasis and the onset of osteoporosis. Bone Res 2019; 7:28. [PMID: 31666998 PMCID: PMC6804951 DOI: 10.1038/s41413-019-0058-7] [Citation(s) in RCA: 100] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 05/28/2019] [Accepted: 06/02/2019] [Indexed: 02/06/2023] Open
Abstract
Autophagy is an evolutionarily conserved intracellular process, in which domestic cellular components are selectively digested for the recycling of nutrients and energy. This process is indispensable for cell homeostasis maintenance and stress responses. Both genetic and functional studies have demonstrated that multiple proteins involved in autophagic activities are critical to the survival, differentiation, and functioning of bone cells, including osteoblasts, osteocytes, and osteoclasts. Dysregulation at the level of autophagic activity consequently disturbs the balance between bone formation and bone resorption and mediates the onset and progression of multiple bone diseases, including osteoporosis. This review aims to introduce the topic of autophagy, summarize the understanding of its relevance in bone physiology, and discuss its role in the onset of osteoporosis and therapeutic potential.
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23
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Mo LY, Jia XY, Liu CC, Zhou XD, Xu X. [Role of autophagy in the pathogenesis of periodontitis]. HUA XI KOU QIANG YI XUE ZA ZHI = HUAXI KOUQIANG YIXUE ZAZHI = WEST CHINA JOURNAL OF STOMATOLOGY 2019; 37:422-427. [PMID: 31512838 DOI: 10.7518/hxkq.2019.04.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Periodontitis is a chronic inflammatory disease of periodontal tissues initiated by oral biofilm. Cellular autophagy is an effective weapon against bacterial infection. Recent studies have shown that autophagy not only promotes the removal of bacteria and toxins from infected cells, but also helps to suppress the inflammatory response to maintain the homeostasis of intracellular environment, which is closely related to the development of periodontitis. Here, we reviewed the relationship between autophagy and periodontitis from three aspects: the interactions between autophagy and periodontal pathogen infection, the regulation of autophagy and immune inflammatory responses, and the relationship between autophagy and alveolar bone metabolism. We aim to provide ideas for further study on the mechanisms of autophagy and periodontitis, and ultimately contribute to a better prevention and treatment of periodontitis.
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Affiliation(s)
- Long-Yi Mo
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Xiao-Yue Jia
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Dept. of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Cheng-Cheng Liu
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Dept. of Periodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Xue-Dong Zhou
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Dept. of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Xin Xu
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Dept. of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
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24
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Jaber FA, Khan NM, Ansari MY, Al-Adlaan AA, Hussein NJ, Safadi FF. Autophagy plays an essential role in bone homeostasis. J Cell Physiol 2019; 234:12105-12115. [PMID: 30820954 DOI: 10.1002/jcp.27071] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 06/29/2018] [Indexed: 12/20/2022]
Abstract
Autophagy is very critical for multiple cellular processes. Autophagy plays a critical role in bone cell differentiation and function.
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Affiliation(s)
- Fatima A Jaber
- Department of Biology, King Abdulaziz University, Jeddah, Saudi Arabia.,Department of Anatomy and Neurobiology, Northeast Ohio Medical University (NEOMED) School of Medicine, Rootstown, Ohio.,School of Biomedical Sciences, Kent State University, Kent, Ohio
| | - Nazir M Khan
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University (NEOMED) School of Medicine, Rootstown, Ohio
| | - Mohammad Y Ansari
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University (NEOMED) School of Medicine, Rootstown, Ohio
| | - Asaad A Al-Adlaan
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University (NEOMED) School of Medicine, Rootstown, Ohio.,School of Biomedical Sciences, Kent State University, Kent, Ohio
| | - Nazar J Hussein
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University (NEOMED) School of Medicine, Rootstown, Ohio.,School of Biomedical Sciences, Kent State University, Kent, Ohio
| | - Fayez F Safadi
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University (NEOMED) School of Medicine, Rootstown, Ohio.,School of Biomedical Sciences, Kent State University, Kent, Ohio.,Department of Pharmaceutical Sciences, College of Pharmacy, Northeast Ohio Medical University, Rootstown, Ohio.,Department of Orthopedic Surgery, SUMMA Health System, Akron, Ohio.,Rebecca D. Considine Research Institute Akron Children's Hospital, Akron, Ohio
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25
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Xiao L, Xiao Y. The Autophagy in Osteoimmonology: Self-Eating, Maintenance, and Beyond. Front Endocrinol (Lausanne) 2019; 10:490. [PMID: 31428045 PMCID: PMC6689986 DOI: 10.3389/fendo.2019.00490] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 07/08/2019] [Indexed: 12/12/2022] Open
Abstract
It has been long realized that the immune and skeletal systems are closely linked. This crosstalk, also known as osteoimmunology, is a primary process required for bone health. For example, the immune system acts as a key regulator in osteoclasts-osteoblasts coupling to maintain the balanced bone remodeling. Osteoimmunology is achieved through many cellular and molecular processes, among which autophagy has recently been found to play an indispensable role. Autophagy is a highly conserved process in eukaryotic cells, by which the cytoplasm components such as dysfunctional organelles are degraded through lysosomes and then returned to the cytosol for reuse. Autophagy is present in all cells at basal levels to maintain homeostasis and to promote cell survival in response to cellular stress conditions such as nutrition deprivation and hypoxia. Autophagy is a required process in immune cell activation/polarization and osteoclast differentiation, which protecting cells from oxidative stress. The essential of autophagy in osteogenesis is its involvement in osteoblast differentiation and mineralization, especially the role of autophagosome in extracellular calcium transportation. The modulatory feature of autophagy in both immune and skeleton systems suggests its crucial roles in osteoimmunology. Furthermore, autophagy also participates in the maintenance of bone marrow hematopoietic stem cell niche. The focus of this review is to highlight the role of autophagy in the immune-skeleton interactions and the effects on bone physiology, as well as the future application in translational research.
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Affiliation(s)
- Lan Xiao
- Key Laboratory of Oral Medicine, Guangzhou Institute of Oral Disease, Stomatology Hospital of Guangzhou Medical University, Guangzhou, China
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
- The Australia-China Centre for Tissue Engineering and Regenerative Medicine (ACCTERM), Queensland University of Technology, Brisbane, QLD, Australia
| | - Yin Xiao
- Key Laboratory of Oral Medicine, Guangzhou Institute of Oral Disease, Stomatology Hospital of Guangzhou Medical University, Guangzhou, China
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
- The Australia-China Centre for Tissue Engineering and Regenerative Medicine (ACCTERM), Queensland University of Technology, Brisbane, QLD, Australia
- *Correspondence: Yin Xiao
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Li H, Li D, Ma Z, Qian Z, Kang X, Jin X, Li F, Wang X, Chen Q, Sun H, Wu S. Defective autophagy in osteoblasts induces endoplasmic reticulum stress and causes remarkable bone loss. Autophagy 2018; 14:1726-1741. [PMID: 29962255 PMCID: PMC6135623 DOI: 10.1080/15548627.2018.1483807] [Citation(s) in RCA: 126] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 05/15/2018] [Accepted: 05/24/2018] [Indexed: 12/13/2022] Open
Abstract
Macroautophagy/autophagy is a highly regulated process involved in the turnover of cytosolic components, however its pivotal role in maintenance of bone homeostasis remains elusive. In the present study, we investigated the direct role of ATG7 (autophagy related 7) during developmental and remodeling stages in vivo using osteoblast-specific Atg7 conditional knockout (cKO) mice. Atg7 cKO mice exhibited a reduced bone mass at both developmental and adult age. The trabecular bone volume of Atg7 cKO mice was significantly lower than that of controls at 5 months of age. This phenotype was attributed to decreased osteoblast formation and matrix mineralization, accompanied with an increased osteoclast number and the extent of the bone surface covered by osteoclasts as well as an elevated secretion of TNFSF11/RANKL (tumor necrosis factor [ligand] superfamily, member 11), and a decrease in TNFRSF11B/OPG (tumor necrosis factor receptor superfamily, member 11b [osteoprotegerin]). Remarkably, Atg7 deficiency in osteoblasts triggered endoplasmic reticulum (ER) stress, whereas attenuation of ER stress by administration of phenylbutyric acid in vivo abrogated Atg7 ablation-mediated effects on osteoblast differentiation, mineralization capacity and bone formation. Consistently, Atg7 deficiency impeded osteoblast mineralization and promoted apoptosis partially in DDIT3/CHOP (DNA-damage-inducible transcript 3)- and MAPK8/JNK1 (mitogen-activated protein kinase 8)-SMAD1/5/8-dependent manner in vitro, while reconstitution of Atg7 could improve ER stress and restore skeletal balance. In conclusion, our findings provide direct evidences that autophagy plays crucial roles in regulation of bone homeostasis and suggest an innovative therapeutic strategy against skeletal diseases.
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Affiliation(s)
- Huixia Li
- The First Affiliated Hospital of Xi’an Jiaotong University; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Danhui Li
- The First Affiliated Hospital of Xi’an Jiaotong University; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Zhengmin Ma
- The First Affiliated Hospital of Xi’an Jiaotong University; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Zhuang Qian
- Center for Translational Medicine, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
| | - Xiaomin Kang
- Center for Translational Medicine, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
| | - Xinxin Jin
- Center for Translational Medicine, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
| | - Fang Li
- The First Affiliated Hospital of Xi’an Jiaotong University; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Xinluan Wang
- Translational Medicine R&D Center, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Qian Chen
- Department of Orthopaedics, Alpert Medical School of Brown University, Rhode Island Hospital, Providence, RI, USA
- Bone and Joint Research Center, the First Affiliated Hospital of Medical School, Frontier Institute of Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi, China
| | - Hongzhi Sun
- The First Affiliated Hospital of Xi’an Jiaotong University; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Shufang Wu
- The First Affiliated Hospital of Xi’an Jiaotong University; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
- Center for Translational Medicine, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
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Abstract
PURPOSE OF REVIEW Bone marrow fat expresses mixed characteristics, which could correspond to white, brown, and beige types of fat. Marrow fat could act as either energy storing and adipokine secreting white fat or as a source of energy for hematopoiesis and bone metabolism, thus acting as brown fat. However, there is also a negative interaction between marrow fat and other elements of the bone marrow milieu, which is known as lipotoxicity. In this review, we will describe the good and bad roles of marrow fat in the bone, while focusing on the specific components of the negative effect of marrow fat on bone metabolism. RECENT FINDINGS Lipotoxicity in the bone is exerted by bone marrow fat through the secretion of adipokines and free fatty acids (FFA) (predominantly palmitate). High levels of FFA found in the bone marrow of aged and osteoporotic bone are associated with decreased osteoblastogenesis and bone formation, decreased hematopoiesis, and increased osteoclastogenesis. In addition, FFA such as palmitate and stearate induce apoptosis and dysfunctional autophagy in the osteoblasts, thus affecting their differentiation and function. Regulation of marrow fat could become a therapeutic target for osteoporosis. Inhibition of the synthesis of FFA by marrow fat could facilitate osteoblastogenesis and bone formation while affecting osteoclastogenesis. However, further studies testing this hypothesis are still required.
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Affiliation(s)
- Lakshman Singh
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, Level 3 WCHRE, 176 Furlong Road, St. Albans, VIC, 3021, Australia
- Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St. Albans, VIC, Australia
| | - Sonia Tyagi
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, Level 3 WCHRE, 176 Furlong Road, St. Albans, VIC, 3021, Australia
- Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St. Albans, VIC, Australia
| | - Damian Myers
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, Level 3 WCHRE, 176 Furlong Road, St. Albans, VIC, 3021, Australia
- Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St. Albans, VIC, Australia
| | - Gustavo Duque
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, Level 3 WCHRE, 176 Furlong Road, St. Albans, VIC, 3021, Australia.
- Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St. Albans, VIC, Australia.
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Florencio-Silva R, Sasso GRS, Sasso-Cerri E, Simões MJ, Cerri PS. Effects of estrogen status in osteocyte autophagy and its relation to osteocyte viability in alveolar process of ovariectomized rats. Biomed Pharmacother 2017; 98:406-415. [PMID: 29276969 DOI: 10.1016/j.biopha.2017.12.089] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 12/05/2017] [Accepted: 12/18/2017] [Indexed: 12/13/2022] Open
Abstract
Estrogen maintains osteocyte viability, whereas its deficiency induces osteocyte apoptosis. As autophagy is important for osteocyte viability, we hypothesized whether the anti-apoptotic effect of estrogen is related to autophagy in osteocytes. Thirty adult female rats were sham-operated (SHAM) or ovariectomized (OVX). After three weeks, twelve rats of SHAM and OVX groups were killed before treatment (basal period), whereas the remaining rats received estrogen (OVXE) or vehicle (OVX) for 45 days. Fragments of maxilla containing alveolar process of the first molars were embedded in paraffin or Araldite. Paraffin-sections were stained with hematoxylin/eosin for histomorphometry, or subjected to the silver impregnation method for morphological analysis of osteocyte cytoplasmic processes. Autophagy was analyzed by immunohistochemical detections of beclin-1, MAP-LC3α and p62, whereas apoptosis was evaluated by immunohistochemical detections of cleaved caspase-3 and BAX, TUNEL (Terminal deoxynucleotidyl transferase dUTP nick end labeling) method and by ultrastructural analysis. Araldite-semithin sections were subjected to the Sudan-black method for detection of lipids. OVX-basal group showed high frequency of caspase-3-, TUNEL- and p62-positive osteocytes accompanied with low frequency of beclin-1- and MAP-LC3α-positive osteocytes. At 45 days, OVXE group exhibited higher number of osteocytes, higher frequency of beclin-1- and MAP-LC3α-positive osteocytes, and lower frequency of caspase-3, BAX-, TUNEL- and p62-positive osteocytes than OVX group. Significant reduction in bone area was observed in the OVX compared to OVXE and SHAM groups. The highest frequency of Sudan-Black-positive osteocytes and osteocytes with scarce cytoplasmic processes, or showing apoptotic features were mainly observed in OVX groups. Our results indicate that estrogen deficiency decreases autophagy and increases apoptosis, whereas estrogen replacement enhances osteocyte viability by inhibiting apoptosis and maintaining autophagy in alveolar process osteocytes. These results suggest that the anti-apoptotic effect of estrogen may be, at least in part, related to autophagy regulation in osteocytes.
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Affiliation(s)
- Rinaldo Florencio-Silva
- Universidade Federal de São Paulo - UNIFESP, Escola Paulista de Medicina - EPM, Departamento de Morfologia e Genética, Disciplina de Histologia e Biologia Estrutural, São Paulo, SP, Brazil
| | - Gisela R S Sasso
- Universidade Federal de São Paulo - UNIFESP, Escola Paulista de Medicina - EPM, Departmento de Ginecologia, São Paulo, SP, Brazil
| | - Estela Sasso-Cerri
- São Paulo State University (UNESP), School of Dentistry, Araraquara - Laboratory of Histology and Embryology, Araraquara, SP, Brazil
| | - Manuel J Simões
- Universidade Federal de São Paulo - UNIFESP, Escola Paulista de Medicina - EPM, Departamento de Morfologia e Genética, Disciplina de Histologia e Biologia Estrutural, São Paulo, SP, Brazil
| | - Paulo S Cerri
- São Paulo State University (UNESP), School of Dentistry, Araraquara - Laboratory of Histology and Embryology, Araraquara, SP, Brazil.
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Zhang B, Hou R, Zou Z, Luo T, Zhang Y, Wang L, Wang B. Mechanically induced autophagy is associated with ATP metabolism and cellular viability in osteocytes in vitro. Redox Biol 2017; 14:492-498. [PMID: 29096322 PMCID: PMC5680519 DOI: 10.1016/j.redox.2017.10.021] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 10/17/2017] [Accepted: 10/25/2017] [Indexed: 12/16/2022] Open
Abstract
Both mechanical loading and intracellular autophagy play important roles in bone homeostasis; however, their relationship remains largely unexplored. The objectives of this study were to determine whether osteocytes undergo autophagy upon fluid shear stress (FSS) loading and to determine the correlation between mechanically induced autophagy and ATP metabolism. Autophagic vacuoles were observed by transmission electron microscopy (TEM) in osteocyte-like MLO-Y4 cells subjected to FSS. Increased autophagic flux was further confirmed by the increased amount of the LC3-II isoform and the degradation of p62. Fluorescent puncta distributed in the cytoplasm were observed in the GFP-LC3 transformed cells subjected to FSS. Furthermore, FSS-induced ATP release and synthesis in osteocytes were attenuated by inhibiting autophagy with 3-MA. After FSS exposure, a high ratio of cell death was observed in cultures pretreated with 3-MA, an autophagy inhibitor, with no significantly different Caspase 3/7 activity. Our results indicated that FSS induces protective autophagy in osteocytes and that mechanically induced autophagy is associated with ATP metabolism and osteocyte survival. From the clinical perspective, it may be possible to enhance skeletal cell survival with drugs that modulate the autophagic state, and the autophagy-related pathway could be a potential target for the prevention of ageing-related bone disorders. Fluid flow shear stress (FSS) induces activation of autophagic flux in MLO-Y4 osteocytes. FSS-induced autophagy promoted ATP metabolism in MLO-Y4 osteocytes. Inhibited autophagy decreased FSS-induced ATP release. FSS-induced autophagy was beneficial to the osteocyte survival after FSS exposure.
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Affiliation(s)
- Bingbing Zhang
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, China
| | - Rutao Hou
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, China
| | - Zhen Zou
- Department of Medical Laboratory Technology, Institute of Life Sciences, Chongqing Medical University, Chongqing 400016, China
| | - Tiantian Luo
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, China
| | - Yang Zhang
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, China
| | - Liyun Wang
- Department of Mechanical Engineering, University of Delaware, Newark, DE 19716, USA
| | - Bin Wang
- Department of Medical Laboratory Technology, Institute of Life Sciences, Chongqing Medical University, Chongqing 400016, China.
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Florencio-Silva R, Sasso GRDS, Simões MDJ, Simões RS, Baracat MCP, Sasso-Cerri E, Cerri PS. Osteoporosis and autophagy: What is the relationship? Rev Assoc Med Bras (1992) 2017; 63:173-179. [PMID: 28355379 DOI: 10.1590/1806-9282.63.02.173] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 05/31/2016] [Indexed: 01/19/2023] Open
Abstract
Autophagy is a survival pathway wherein non-functional proteins and organelles are degraded in lysosomes for recycling and energy production. Therefore, autophagy is fundamental for the maintenance of cell viability, acting as a quality control process that prevents the accumulation of unnecessary structures and oxidative stress. Increasing evidence has shown that autophagy dysfunction is related to several pathologies including neurodegenerative diseases and cancer. Moreover, recent studies have shown that autophagy plays an important role for the maintenance of bone homeostasis. For instance, in vitro and animal and human studies indicate that autophagy dysfunction in bone cells is associated with the onset of bone diseases such as osteoporosis. This review had the purpose of discussing the issue to confirm whether a relationship between autophagy dysfunction and osteoporosis exits.
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Affiliation(s)
- Rinaldo Florencio-Silva
- PhD, Postdoctoral Student, Department of Morphology and Genetics, Division of Histology and Structural Biology, Universidade Federal de São Paulo (Unifesp), São Paulo, SP, Brazil
| | | | - Manuel de Jesus Simões
- Full Professor of the Department of Morphology and Genetics, Division of Histology and Structural Biology, Unifesp, São Paulo, SP, Brazil
| | - Ricardo Santos Simões
- PhD, MD, Department of Obstetrics and Gynecology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), São Paulo, SP, Brazil
| | | | - Estela Sasso-Cerri
- PhD, Adjunct Professor (Habilitation: BR. Livre-docente) of the Department of Morphology, Laboratory of Histology and Embryology, Faculty of Dentistry of Araraquara, Universidade Estadual Paulista (Unesp), Araraquara, SP, Brazil
| | - Paulo Sérgio Cerri
- PhD, Adjunct Professor (Habilitation: BR. Livre-docente) of the Department of Morphology, Laboratory of Histology and Embryology, Faculty of Dentistry of Araraquara, Universidade Estadual Paulista (Unesp), Araraquara, SP, Brazil
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Fu J, Hao L, Tian Y, Liu Y, Gu Y, Wu J. miR-199a-3p is involved in estrogen-mediated autophagy through the IGF-1/mTOR pathway in osteocyte-like MLO-Y4 cells. J Cell Physiol 2017; 233:2292-2303. [PMID: 28708244 DOI: 10.1002/jcp.26101] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 07/13/2017] [Indexed: 12/24/2022]
Affiliation(s)
- Jiayao Fu
- Department of Prosthodontics, School and Hospital of Stomatology, Tongji University; Shanghai Engineering Research Center of Tooth Restoration and Regeneration; Shanghai China
| | - Lingyu Hao
- Department of Prosthodontics, School and Hospital of Stomatology, Tongji University; Shanghai Engineering Research Center of Tooth Restoration and Regeneration; Shanghai China
| | - Yawen Tian
- Department of Prosthodontics, School and Hospital of Stomatology, Tongji University; Shanghai Engineering Research Center of Tooth Restoration and Regeneration; Shanghai China
| | - Yang Liu
- Department of Prosthodontics, School and Hospital of Stomatology, Tongji University; Shanghai Engineering Research Center of Tooth Restoration and Regeneration; Shanghai China
| | - Yijing Gu
- Department of Prosthodontics, School and Hospital of Stomatology, Tongji University; Shanghai Engineering Research Center of Tooth Restoration and Regeneration; Shanghai China
| | - Junhua Wu
- Department of Prosthodontics, School and Hospital of Stomatology, Tongji University; Shanghai Engineering Research Center of Tooth Restoration and Regeneration; Shanghai China
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Acidic pH environment induces autophagy in osteoblasts. Sci Rep 2017; 7:46161. [PMID: 28382973 PMCID: PMC5382697 DOI: 10.1038/srep46161] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 03/09/2017] [Indexed: 12/22/2022] Open
Abstract
Osteoblasts (OBs) play an important role in bone fracture healing, yet the extreme adverse microenvironment in fracture sites has a negative impact on the survival of OBs. Therefore, it is important to study how OBs behave in the complex fracture microenvironment. Studies have shown that autophagy plays a pivotal role in maintaining cellular homeostasis and defending the cell against adverse microenvironments. In this study we found the induction of autophagy in OBs at femoral bone fracture sites, which may be a result of ischemia, oxidative stress and hypoxia within the local area. At fracture sites a low pH environment also developed. Until now it has been unclear whether the induction of autophagy in osteoblasts is triggered by the acidic pH environment. Therefore, we cultured OBs in vitro in media of different pH values, and found both autophagy and apoptosis increased in OBs in acidic conditions. However, when autophagy inhibitor chloroquine (CQ) was used, apoptosis increased significantly compared with that without CQ. Thus indicating that inhibition of autophagy may promote apoptosis in OBs in an acidic environment, which may provide a new therapeutic strategy to decrease cell apoptosis in OBs through the use of drugs that modulate the autophagic state.
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Pierrefite-Carle V, Santucci-Darmanin S, Breuil V, Camuzard O, Carle GF. Autophagy in bone: Self-eating to stay in balance. Ageing Res Rev 2015; 24:206-17. [PMID: 26318060 DOI: 10.1016/j.arr.2015.08.004] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 08/18/2015] [Accepted: 08/20/2015] [Indexed: 12/14/2022]
Abstract
Autophagy, a major catabolic pathway responsible of the elimination of damaged proteins and organelles, is now recognized as an anti-aging process. In addition to its basal role in cell homeostasis, autophagy is also a stress-responsive mechanism for survival purposes. Here, we review recent literature to highlight the autophagy role in the different bone cell types, i.e., osteoblasts, osteoclasts and osteocytes. We also discuss the effects of autophagy modulators in bone physiology and of bone anabolic compounds in autophagy. Finally, we analyzed studies regarding bone cell autophagy-deficient mouse models to obtain a more general view on how autophagy modulates bone physiology and pathophysiology, particularly during aging.
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Affiliation(s)
- Valérie Pierrefite-Carle
- UMR E-4320 TIRO-MATOs CEA/iBEB, Université Nice Sophia Antipolis, Faculté de Médecine Nice, France.
| | - Sabine Santucci-Darmanin
- UMR E-4320 TIRO-MATOs CEA/iBEB, Université Nice Sophia Antipolis, Faculté de Médecine Nice, France
| | - Véronique Breuil
- UMR E-4320 TIRO-MATOs CEA/iBEB, Université Nice Sophia Antipolis, Faculté de Médecine Nice, France; Service de Rhumatologie, CHU de Nice, Nice, France
| | - Olivier Camuzard
- UMR E-4320 TIRO-MATOs CEA/iBEB, Université Nice Sophia Antipolis, Faculté de Médecine Nice, France; Service de Chirurgie Réparatrice et de la main, CHU de Nice, Nice, France
| | - Georges F Carle
- UMR E-4320 TIRO-MATOs CEA/iBEB, Université Nice Sophia Antipolis, Faculté de Médecine Nice, France
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Owen HC, Vanhees I, Gunst J, Van Cromphaut S, Van den Berghe G. Critical illness-induced bone loss is related to deficient autophagy and histone hypomethylation. Intensive Care Med Exp 2015. [PMID: 26215816 PMCID: PMC4480347 DOI: 10.1186/s40635-015-0052-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Survivors of critical illness are at increased risk of fractures. This may be due to increased osteoclast formation during critical illness, leading to trabecular bone loss. Such bone loss has also been observed in Paget's disease, and has been related to deficient autophagy. Deficient autophagy has also been documented in vital organs and skeletal muscle of critically ill patients. The objective of this study was to investigate whether deficient autophagy can be linked to critical illness-induced bone loss. METHODS Osteoclasts grown in vitro and their precursor cells isolated from peripheral blood of critically ill patients and from matched healthy volunteers were analysed for the expression of autophagy genes (SQSTM1, Atg3 and Atg7), and proteins (p62, Atg-5, and microtubule-associated protein light chain 3-II (LC3-II)) and for autophagy and epigenetic signalling factors via PCR arrays and were treated with the autophagy inducer rapamycin. The effect of rapamycin was also investigated at the tissue level in an in vivo rabbit model of critical illness. RESULTS Many more osteoclasts formed in vitro from the blood precursor cells isolated from critically ill patients, which accumulated p62, and displayed reduced expression of Atg5, Atg7, and LC3-II compared to healthy controls, suggesting deficient autophagy, whilst addition of rapamycin reduced osteoclast formation. PCR arrays revealed a down-regulation of histone methyltransferases coupled with an up-regulation of negative regulators of autophagy. Critically ill rabbits displayed a reduction in trabecular and cortical bone, which was rescued with rapamycin. CONCLUSIONS Deficient autophagy in osteoclasts and their blood precursor cells at least partially explained aberrant osteoclast formation during critical illness and was linked to global histone hypomethylation. Treatment with the autophagy activator Rapamycin reduced patient osteoclast formation in vitro and reduced the amount of bone loss in critically ill rabbits in vivo. These findings may help to develop novel therapeutic targets to prevent critical illness-induced bone loss.
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Affiliation(s)
- Helen C Owen
- Research Group of Intensive Care Medicine, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium,
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35
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Yang Y, Zheng X, Li B, Jiang S, Jiang L. Increased activity of osteocyte autophagy in ovariectomized rats and its correlation with oxidative stress status and bone loss. Biochem Biophys Res Commun 2014; 451:86-92. [PMID: 25063028 DOI: 10.1016/j.bbrc.2014.07.069] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 07/15/2014] [Indexed: 12/22/2022]
Abstract
OBJECTIVES The objectives of the present study were to investigate ovariectomy on autophagy level in the bone and to examine whether autophagy level is associated with bone loss and oxidative stress status. METHODS 36 female Sprague-Dawley rats were randomly divided into sham-operated (Sham), and ovariectomized (OVX) rats treated either with vehicle or 17-β-estradiol. At the end of the six-week treatment, bone mineral density (BMD) and bone micro-architecture in proximal tibias were assessed by micro-CT. Serum 17β-estradiol (E2) level were measured. Total antioxidant capacity (T-AOC), superoxide dismutase (SOD) activity, catalase (CAT) activity in proximal tibia was also determined. The osteocyte autophagy in proximal tibias was detected respectively by Transmission Electron Microscopy (TEM), immunofluorescent histochemistry (IH), realtime-PCR and Western blot. In addition, the spearman correlation between bone mass, oxidative stress status, serum E2 and autophagy were analyzed. RESULTS Ovariectomy increased Atg5, LC3, and Beclin1 mRNA and proteins expressions while decreased p62 expression. Ovariectomy also declined the activities of T-AOC, CAT, and SOD. Treatment with E2 prevented the reduction in bone mass as well as restored the autophagy level. Furthermore, LC3-II expression was inversely correlated with T-AOC, CAT, and SOD activities. A significant inverse correlation between LC3-II expression and BV/TV, Tb.N, BMD in proximal tibias was found. CONCLUSIONS Ovariectomy induced oxidative stress, autophagy and bone loss. Autophagy of osteocyte was inversely correlated with oxidative stress status and bone loss.
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Affiliation(s)
- Yuehua Yang
- Department of Orthopaedic Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, 1665 Kongjiang Road, Shanghai 200092, China.
| | - Xinfeng Zheng
- Department of Orthopaedic Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, 1665 Kongjiang Road, Shanghai 200092, China.
| | - Bo Li
- Department of Orthopaedic Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, 1665 Kongjiang Road, Shanghai 200092, China.
| | - Shengdan Jiang
- Department of Orthopaedic Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, 1665 Kongjiang Road, Shanghai 200092, China.
| | - Leisheng Jiang
- Department of Orthopaedic Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, 1665 Kongjiang Road, Shanghai 200092, China.
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36
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Decreased activity of osteocyte autophagy with aging may contribute to the bone loss in senile population. Histochem Cell Biol 2014; 142:285-95. [PMID: 24553790 DOI: 10.1007/s00418-014-1194-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/27/2014] [Indexed: 12/30/2022]
Abstract
Age-related bone loss is a major cause of osteoporosis and osteoporotic fractures in the elderly. However, the underlying molecular mechanism of age-related bone loss is still poorly understood. The aim of this study was to clarify whether autophagy in osteocytes was involved in age-related bone loss. Male Sprague-Dawley (SD) rats in 3, 9, and 24 month old were used to mimic the age-related bone loss in men. Micro-CT evaluation, histomorphometric analysis, and measurement of bone turnover rate verified age-related bone loss in the male SD rats. Immunofluorescent histochemistry, RT-PCR, and Western blot assessment demonstrated that the expression of LC3-II, LC3-II/I, Beclin-1, and Ulk-1 in the osteocytes decreased with age, while SQSTM1/p62 and apoptosis in the osteocytes increased. A significant correlation between the markers of osteocyte autophagy and bone mineral density in the proximal tibia was revealed. However, osteocyte autophagy was not correlated with osteocyte apoptosis in the process of aging. These results suggested that osteocyte autophagy was possibly involved in the age-related bone loss. Decreased activity of osteocyte autophagy independent of apoptosis might contribute to the age-related bone loss in senile osteoporosis.
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37
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Autophagy impairment aggravates the inhibitory effects of high glucose on osteoblast viability and function. Biochem J 2014; 455:329-37. [PMID: 23981124 DOI: 10.1042/bj20130562] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Autophagy is a highly regulated homoeostatic process involved in the lysosomal degradation of damaged cell organelles and proteins. This process is considered an important pro-survival mechanism under diverse stress conditions. A diabetic milieu is known to hamper osteoblast viability and function. In the present study, we explored the putative protective role of autophagy in osteoblastic cells exposed to an HG (high glucose) medium. HG was found to increase protein oxidation and triggered autophagy by a mechanism dependent on reactive oxygen species overproduction in osteoblastic MC3T3-E1 cells. MC3T3-E1 cell survival was impaired by HG and worsened by chemical or genetic inhibition of autophagy. These findings were mimicked by H2O2-induced oxidative stress in these cells. Autophagy impairment led to both defective mitochondrial morphology and decreased bioenergetic machinery and inhibited further osteoblast differentiation in MC3T3-E1 cells upon exposure to HG. These novel findings indicate that autophagy is an essential mechanism to maintain osteoblast viability and function in an HG environment.
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38
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Nollet M, Santucci-Darmanin S, Breuil V, Al-Sahlanee R, Cros C, Topi M, Momier D, Samson M, Pagnotta S, Cailleteau L, Battaglia S, Farlay D, Dacquin R, Barois N, Jurdic P, Boivin G, Heymann D, Lafont F, Lu SS, Dempster DW, Carle GF, Pierrefite-Carle V. Autophagy in osteoblasts is involved in mineralization and bone homeostasis. Autophagy 2014; 10:1965-77. [PMID: 25484092 PMCID: PMC4502694 DOI: 10.4161/auto.36182] [Citation(s) in RCA: 281] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Bone remodeling is a tightly controlled mechanism in which osteoblasts (OB), the cells responsible for bone formation, osteoclasts (OC), the cells specialized for bone resorption, and osteocytes, the multifunctional mechanosensing cells embedded in the bone matrix, are the main actors. Increased oxidative stress in OB, the cells producing and mineralizing bone matrix, has been associated with osteoporosis development but the role of autophagy in OB has not yet been addressed. This is the goal of the present study. We first show that the autophagic process is induced in OB during mineralization. Then, using knockdown of autophagy-essential genes and OB-specific autophagy-deficient mice, we demonstrate that autophagy deficiency reduces mineralization capacity. Moreover, our data suggest that autophagic vacuoles could be used as vehicles in OB to secrete apatite crystals. In addition, autophagy-deficient OB exhibit increased oxidative stress and secretion of the receptor activator of NFKB1 (TNFSF11/RANKL), favoring generation of OC, the cells specialized in bone resorption. In vivo, we observed a 50% reduction in trabecular bone mass in OB-specific autophagy-deficient mice. Taken together, our results show for the first time that autophagy in OB is involved both in the mineralization process and in bone homeostasis. These findings are of importance for mineralized tissues which extend from corals to vertebrates and uncover new therapeutic targets for calcified tissue-related metabolic pathologies.
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Key Words
- ACP5/TRAP, acid phosphatase 5, tartrate resistant
- BECN1, Beclin 1, autophagy-related
- BV, bone volume
- Baf, bafilomycin A1
- Col1A, collagen, type I, α 1
- HRTEM, high resolution transmission electron microscopy
- MAP1LC3 (LC3), microtubule-associated protein 1 light chain 3
- OB, osteoblast
- OC, osteoclast
- PBS, phosphate-buffered saline
- RNA, ribonucleic acid
- RUNX2, runt-related transcription factor 2
- SAED, selected area electron diffraction
- SPP1/OPN, secreted phosphoprotein 1
- TNFSF11/RANKL, tumor necrosis factor (ligand) superfamily, member 11
- TUBB, tubulin, beta
- TV, total volume
- autophagy
- bone remodeling
- mineralization
- osteoblast
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Affiliation(s)
- Marie Nollet
- UMR E-4320 MATOs CEA/iBEB/SBTN-CAL; Université Nice Sophia Antipolis; Faculté de Médecine; Nice, France
| | - Sabine Santucci-Darmanin
- UMR E-4320 MATOs CEA/iBEB/SBTN-CAL; Université Nice Sophia Antipolis; Faculté de Médecine; Nice, France
| | - Véronique Breuil
- UMR E-4320 MATOs CEA/iBEB/SBTN-CAL; Université Nice Sophia Antipolis; Faculté de Médecine; Nice, France
- Service de Rhumatologie; CHU de Nice; Nice, France
| | - Rasha Al-Sahlanee
- UMR E-4320 MATOs CEA/iBEB/SBTN-CAL; Université Nice Sophia Antipolis; Faculté de Médecine; Nice, France
| | - Chantal Cros
- UMR E-4320 MATOs CEA/iBEB/SBTN-CAL; Université Nice Sophia Antipolis; Faculté de Médecine; Nice, France
| | - Majlinda Topi
- UMR E-4320 MATOs CEA/iBEB/SBTN-CAL; Université Nice Sophia Antipolis; Faculté de Médecine; Nice, France
| | - David Momier
- UMR E-4320 MATOs CEA/iBEB/SBTN-CAL; Université Nice Sophia Antipolis; Faculté de Médecine; Nice, France
| | - Michel Samson
- UMR E-4320 MATOs CEA/iBEB/SBTN-CAL; Université Nice Sophia Antipolis; Faculté de Médecine; Nice, France
| | - Sophie Pagnotta
- Centre Commun de Microscopie Appliquee; Université Nice Sophia Antipolis; Nice, France
| | - Laurence Cailleteau
- Plateforme Imagerie IRCAN; Faculté de Médecine; Université Nice Sophia Antipolis; Nice, France
| | - Séverine Battaglia
- INSERM UMR 957; Université de Nantes; Equipe labellisée Ligue Nationale Contre le Cancer 2012; Nantes, France
| | | | - Romain Dacquin
- Institut de Génomique Fonctionnelle de Lyon; Université de Lyon; CNRS; Ecole Normale Supérieure de Lyon; Lyon, France
| | - Nicolas Barois
- Plate-forme BICeL-IFR142; Institut Pasteur de Lille; Lille, France
| | - Pierre Jurdic
- Institut de Génomique Fonctionnelle de Lyon; Université de Lyon; CNRS; Ecole Normale Supérieure de Lyon; Lyon, France
| | | | - Dominique Heymann
- INSERM UMR 957; Université de Nantes; Equipe labellisée Ligue Nationale Contre le Cancer 2012; Nantes, France
| | - Frank Lafont
- Plate-forme BICeL-IFR142; Institut Pasteur de Lille; Lille, France
- INSERM U1019 - CNRS UMR 8204; Institut Pasteur de Lille - Univ Lille Nord de France; Lille, France
| | - Shi Shou Lu
- Regional Bone Center; Helen Hayes Hospital; West Havertsraw, NY USA
| | - David W Dempster
- Regional Bone Center; Helen Hayes Hospital; West Havertsraw, NY USA
| | - Georges F Carle
- UMR E-4320 MATOs CEA/iBEB/SBTN-CAL; Université Nice Sophia Antipolis; Faculté de Médecine; Nice, France
| | - Valérie Pierrefite-Carle
- UMR E-4320 MATOs CEA/iBEB/SBTN-CAL; Université Nice Sophia Antipolis; Faculté de Médecine; Nice, France
- Correspondence to: Valérie Pierrefite-Carle;
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39
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Shapiro IM, Layfield R, Lotz M, Settembre C, Whitehouse C. Boning up on autophagy: the role of autophagy in skeletal biology. Autophagy 2013; 10:7-19. [PMID: 24225636 DOI: 10.4161/auto.26679] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
From an evolutionary perspective, the major function of bone is to provide stable sites for muscle attachment and affording protection of vital organs, especially the heart and lungs (ribs) and spinal cord (vertebrae and intervertebral discs). However, bone has a considerable number of other functions: serving as a store for mineral ions, providing a site for blood cell synthesis and participating in a complex system-wide endocrine system. Not surprisingly, bone and cartilage cell homeostasis is tightly controlled, as is the maintenance of tissue structure and mass. While a great deal of new information is accruing concerning skeletal cell homeostasis, one relatively new observation is that the cells of bone (osteoclasts osteoblasts and osteocytes) and cartilage (chondrocytes) exhibit autophagy. The focus of this review is to examine the significance of this process in terms of the functional demands of the skeleton in health and during growth and to provide evidence that dysregulation of the autophagic response is involved in the pathogenesis of diseases of bone (Paget disease of bone) and cartilage (osteoarthritis and the mucopolysaccharidoses). Delineation of molecular changes in the autophagic process is uncovering new approaches for the treatment of diseases that affect the axial and appendicular skeleton.
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Affiliation(s)
- Irving M Shapiro
- Jefferson Medical College; Thomas Jefferson University; Philadelphia, PA USA
| | - Robert Layfield
- School of Life Sciences; University of Nottingham Medical School; Nottingham UK
| | - Martin Lotz
- Arthritis Research; The Scripps Research Institute; La Jolla, CA USA
| | - Carmine Settembre
- Telethon Institute of Genetics and Medicine (TIGEM); Naples, Italy; Department of Molecular and Human Genetics; Baylor College of Medicine, Houston, TXUSA and Jan and Dan Duncan Neurological Research Institute; Texas Children's Hospital; Houston, TX USA; Medical Genetics; Department of Translational and Medical Science; Federico II University; Naples, Italy
| | - Caroline Whitehouse
- Department of Medical and Molecular Genetics; Kings College London; London UK
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40
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Liu F, Fang F, Yuan H, Yang D, Chen Y, Williams L, Goldstein SA, Krebsbach PH, Guan JL. Suppression of autophagy by FIP200 deletion leads to osteopenia in mice through the inhibition of osteoblast terminal differentiation. J Bone Miner Res 2013; 28:2414-30. [PMID: 23633228 PMCID: PMC3805719 DOI: 10.1002/jbmr.1971] [Citation(s) in RCA: 168] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 03/21/2013] [Accepted: 04/15/2013] [Indexed: 12/22/2022]
Abstract
Autophagy is a conserved lysosomal degradation process that has important roles in both normal human physiology and disease. However, the function of autophagy in bone homeostasis is not well understood. Here, we report that autophagy is activated during osteoblast differentiation. Ablation of focal adhesion kinase family interacting protein of 200 kD (FIP200), an essential component of mammalian autophagy, led to multiple autophagic defects in osteoblasts including aberrantly increased p62 expression, deficient LC3-II conversion, defective autophagy flux, absence of GFP-LC3 puncta in FIP200-null osteoblasts expressing transgenic GFP-LC3, and absence of autophagosome-like structures by electron microscope examination. Osteoblast-specific deletion of FIP200 led to osteopenia in mice. Histomorphometric analysis revealed that the osteopenia was the result of cell-autonomous effects of FIP200 deletion on osteoblasts. FIP200 deletion led to defective osteoblast terminal differentiation in both primary bone marrow and calvarial osteoblasts in vitro. Interestingly, both proliferation and differentiation were not adversely affected by FIP200 deletion in early cultures. However, FIP200 deletion led to defective osteoblast nodule formation after initial proliferation and differentiation. Furthermore, treatment with autophagy inhibitors recapitulated the effects of FIP200 deletion on osteoblast differentiation. Taken together, these data identify FIP200 as an important regulator of bone development and reveal a novel role of autophagy in osteoblast function through its positive role in supporting osteoblast nodule formation and differentiation.
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Affiliation(s)
- Fei Liu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA
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41
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Rochefort GY, Benhamou CL. Osteocytes are not only mechanoreceptive cells. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2013; 29:1082-1088. [PMID: 23776074 DOI: 10.1002/cnm.2561] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 03/25/2013] [Accepted: 04/23/2013] [Indexed: 06/02/2023]
Abstract
Osteocytes represent 95% of all bone cells. These cells are old osteoblasts occupying the lacunar space surrounded by the bone matrix. They possess cytoplasmic dendrites that form a canalicular network for communication between osteocytes and the bone surface. They have a mechanosensing role that is dependent upon the frequency, the intensity, and the duration of strain. The mechanical information transmitted into the cytoplasm also triggers a biological cascade, starting with nitric oxide and prostaglandin E 2 and followed by Wnt/ β-catenin signaling. This information is transmitted to the bone surface through the canalicular network, particularly to the lining cells, and is able to trigger bone remodeling by directing the osteoblast activity and the osteoclastic resorption. Furthermore, the osteocyte death seems to play an important role. The outcome of microcracks in the vicinity of osteocytes may interrupt the canalicular network and trigger cell apoptosis in the immediate surrounding environment thus transmitting a message to the bone surface and activate remodeling. This network also plays a recognized endocrine role, particularly concerning phosphate regulation and vitamin D metabolism.
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42
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Engedal N, Torgersen ML, Guldvik IJ, Barfeld SJ, Bakula D, Sætre F, Hagen LK, Patterson JB, Proikas-Cezanne T, Seglen PO, Simonsen A, Mills IG. Modulation of intracellular calcium homeostasis blocks autophagosome formation. Autophagy 2013; 9:1475-90. [PMID: 23970164 DOI: 10.4161/auto.25900] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Cellular stress responses often involve elevation of cytosolic calcium levels, and this has been suggested to stimulate autophagy. Here, however, we demonstrated that agents that alter intracellular calcium ion homeostasis and induce ER stress-the calcium ionophore A23187 and the sarco/endoplasmic reticulum Ca (2+)-ATPase inhibitor thapsigargin (TG)-potently inhibit autophagy. This anti-autophagic effect occurred under both nutrient-rich and amino acid starvation conditions, and was reflected by a strong reduction in autophagic degradation of long-lived proteins. Furthermore, we found that the calcium-modulating agents inhibited autophagosome biogenesis at a step after the acquisition of WIPI1, but prior to the closure of the autophagosome. The latter was evident from the virtually complete inability of A23187- or TG-treated cells to sequester cytosolic lactate dehydrogenase. Moreover, we observed a decrease in both the number and size of starvation-induced EGFP-LC3 puncta as well as reduced numbers of mRFP-LC3 puncta in a tandem fluorescent mRFP-EGFP-LC3 cell line. The anti-autophagic effect of A23187 and TG was independent of ER stress, as chemical or siRNA-mediated inhibition of the unfolded protein response did not alter the ability of the calcium modulators to block autophagy. Finally, and remarkably, we found that the anti-autophagic activity of the calcium modulators did not require sustained or bulk changes in cytosolic calcium levels. In conclusion, we propose that local perturbations in intracellular calcium levels can exert inhibitory effects on autophagy at the stage of autophagosome expansion and closure.
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Affiliation(s)
- Nikolai Engedal
- Centre for Molecular Medicine Norway (NCMM); Nordic EMBL Partnership; University of Oslo, Norway
| | - Maria L Torgersen
- Department of Biochemistry; Institute of Basic Medical Sciences; Faculty of Medicine; University of Oslo, Norway
| | - Ingrid J Guldvik
- Centre for Molecular Medicine Norway (NCMM); Nordic EMBL Partnership; University of Oslo, Norway
| | - Stefan J Barfeld
- Centre for Molecular Medicine Norway (NCMM); Nordic EMBL Partnership; University of Oslo, Norway
| | - Daniela Bakula
- Autophagy Laboratory; Department of Molecular Biology; Interfaculty Institute for Cell Biology; Faculty of Science; Eberhard Karls University; Tuebingen, Germany
| | - Frank Sætre
- Department of Cell Biology; Institute for Cancer Research; Norwegian Radium Hospital; Oslo University Hospital; Nydalen, Oslo Norway
| | - Linda K Hagen
- Department of Cell Biology; Institute for Cancer Research; Norwegian Radium Hospital; Oslo University Hospital; Nydalen, Oslo Norway
| | | | - Tassula Proikas-Cezanne
- Autophagy Laboratory; Department of Molecular Biology; Interfaculty Institute for Cell Biology; Faculty of Science; Eberhard Karls University; Tuebingen, Germany
| | - Per O Seglen
- Department of Cell Biology; Institute for Cancer Research; Norwegian Radium Hospital; Oslo University Hospital; Nydalen, Oslo Norway
| | - Anne Simonsen
- Department of Biochemistry; Institute of Basic Medical Sciences; Faculty of Medicine; University of Oslo, Norway
| | - Ian G Mills
- Centre for Molecular Medicine Norway (NCMM); Nordic EMBL Partnership; University of Oslo, Norway; Department of Cancer Prevention and Department of Urology; Oslo University Hospitals; Oslo, Norway
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43
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Abstract
Imbalances between bone resorption and formation lie at the root of disorders such as osteoporosis, Paget's disease of bone (PDB), and osteopetrosis. Recently, genetic and functional studies have implicated proteins involved in autophagic protein degradation as important mediators of bone cell function in normal physiology and in pathology. Autophagy is the conserved process whereby aggregated proteins, intracellular pathogens, and damaged organelles are degraded and recycled. This process is important both for normal cellular quality control and in response to environmental or internal stressors, particularly in terminally-differentiated cells. Autophagic structures can also act as hubs for the spatial organization of recycling and synthetic process in secretory cells. Alterations to autophagy (reduction, hyperactivation, or impairment) are associated with a number of disorders, including neurodegenerative diseases and cancers, and are now being implicated in maintenance of skeletal homoeostasis. Here, we introduce the topic of autophagy, describe the new findings that are starting to emerge from the bone field, and consider the therapeutic potential of modifying this pathway for the treatment of age-related bone disorders.
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Affiliation(s)
- Lynne J Hocking
- Musculoskeletal Research Programme, Division of Applied Medicine, University of Aberdeen, Aberdeen, UK.
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