1
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Jiang Z, Qi G, He X, Yu Y, Cao Y, Zhang C, Zou W, Yuan H. Ferroptosis in Osteocytes as a Target for Protection Against Postmenopausal Osteoporosis. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2307388. [PMID: 38233202 DOI: 10.1002/advs.202307388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 12/18/2023] [Indexed: 01/19/2024]
Abstract
Ferroptosis is a necrotic form of iron-dependent regulatory cell death. Estrogen withdrawal can interfere with iron metabolism, which is responsible for the pathogenesis of postmenopausal osteoporosis (PMOP). Here, it is demonstrated that estrogen withdrawal induces iron accumulation in the skeleton and the ferroptosis of osteocytes, leading to reduced bone mineral density. Furthermore, the facilitatory effect of ferroptosis of osteocytes is verified in the occurrence and development of postmenopausal osteoporosis is associated with over activated osteoclastogenesis using a direct osteocyte/osteoclast coculture system and glutathione peroxidase 4 (GPX4) knockout ovariectomized mice. In addition, the nuclear factor erythroid derived 2-related factor-2 (Nrf2) signaling pathway is confirmed to be a crucial factor in the ferroptosis of osteocytic cells. Nrf2 regulates the expression of nuclear factor kappa-B ligand (RANKL) by regulating the DNA methylation level of the RANKL promoter mediated by DNA methyltransferase 3a (Dnmt3a), which is as an important mechanism in osteocytic ferroptosis-mediated osteoclastogenesis. Taken together, this data suggests that osteocytic ferroptosis is involved in PMOP and can be targeted to tune bone homeostasis.
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Affiliation(s)
- Zengxin Jiang
- Department of Orthopaedics, Shanghai Jiaotong University Affiliated Sixth People's Hospital, No. 600 Yishan Road, Shanghai, 200233, China
- Institute of Microsurgery on Extremities, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China
| | - Guobin Qi
- Institute of Microsurgery on Extremities, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China
| | - Xuecheng He
- Department of Orthopaedics, Shanghai Jiaotong University Affiliated Sixth People's Hospital, No. 600 Yishan Road, Shanghai, 200233, China
- Institute of Microsurgery on Extremities, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China
| | - Yifan Yu
- Department of Orthopaedics, Shanghai Jiaotong University Affiliated Sixth People's Hospital, No. 600 Yishan Road, Shanghai, 200233, China
- Institute of Microsurgery on Extremities, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China
| | - Yuting Cao
- Department of Orthopaedics, Shanghai Jiaotong University Affiliated Sixth People's Hospital, No. 600 Yishan Road, Shanghai, 200233, China
- Institute of Microsurgery on Extremities, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China
| | - Changqing Zhang
- Department of Orthopaedics, Shanghai Jiaotong University Affiliated Sixth People's Hospital, No. 600 Yishan Road, Shanghai, 200233, China
- Institute of Microsurgery on Extremities, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China
| | - Weiguo Zou
- Institute of Microsurgery on Extremities, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Sciences, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China
| | - Hengfeng Yuan
- Department of Orthopaedics, Shanghai Jiaotong University Affiliated Sixth People's Hospital, No. 600 Yishan Road, Shanghai, 200233, China
- Institute of Microsurgery on Extremities, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China
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2
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Leser JM, Torre OM, Gould NR, Guo Q, Buck HV, Kodama J, Otsuru S, Stains JP. Osteoblast-lineage calcium/calmodulin-dependent kinase 2 delta and gamma regulates bone mass and quality. Proc Natl Acad Sci U S A 2023; 120:e2304492120. [PMID: 37976259 PMCID: PMC10666124 DOI: 10.1073/pnas.2304492120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 09/30/2023] [Indexed: 11/19/2023] Open
Abstract
Bone regulates its mass and quality in response to diverse mechanical, hormonal, and local signals. The bone anabolic or catabolic responses to these signals are often received by osteocytes, which then coordinate the activity of osteoblasts and osteoclasts on bone surfaces. We previously established that calcium/calmodulin-dependent kinase 2 (CaMKII) is required for osteocytes to respond to some bone anabolic cues in vitro. However, a role for CaMKII in bone physiology in vivo is largely undescribed. Here, we show that conditional codeletion of the most abundant isoforms of CaMKII (delta and gamma) in mature osteoblasts and osteocytes [Ocn-cre:Camk2d/Camk2g double-knockout (dCKO)] caused severe osteopenia in both cortical and trabecular compartments by 8 wk of age. In addition to having less bone mass, dCKO bones are of worse quality, with significant deficits in mechanical properties, and a propensity to fracture. This striking skeletal phenotype is multifactorial, including diminished osteoblast activity, increased osteoclast activity, and altered phosphate homeostasis both systemically and locally. These dCKO mice exhibited decreased circulating phosphate (hypophosphatemia) and increased expression of the phosphate-regulating hormone fibroblast growth factor 23. Additionally, dCKO mice expressed less bone-derived tissue nonspecific alkaline phosphatase protein than control mice. Consistent with altered phosphate homeostasis, we observed that dCKO bones were hypo-mineralized with prominent osteoid seams, analogous to the phenotypes of mice with hypophosphatemia. Altogether, these data reveal a fundamental role for osteocyte CaMKIIδ and CaMKIIγ in the maintenance of bone mass and bone quality and link osteoblast/osteocyte CaMKII to phosphate homeostasis.
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Affiliation(s)
- Jenna M. Leser
- Department of Othopaedics, University of Maryland School of Medicine, Baltimore, MD21201
| | - Olivia M. Torre
- Department of Othopaedics, University of Maryland School of Medicine, Baltimore, MD21201
| | - Nicole R. Gould
- Department of Othopaedics, University of Maryland School of Medicine, Baltimore, MD21201
| | - Qiaoyue Guo
- Department of Othopaedics, University of Maryland School of Medicine, Baltimore, MD21201
| | - Heather V. Buck
- Department of Othopaedics, University of Maryland School of Medicine, Baltimore, MD21201
| | - Joe Kodama
- Department of Othopaedics, University of Maryland School of Medicine, Baltimore, MD21201
| | - Satoru Otsuru
- Department of Othopaedics, University of Maryland School of Medicine, Baltimore, MD21201
| | - Joseph P. Stains
- Department of Othopaedics, University of Maryland School of Medicine, Baltimore, MD21201
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Akyer SP, Karagur ER, Ata MT, Toprak EK, Donmez AC, Donmez BO. Verbascoside Inhibits/Repairs the Damage of LPS-Induced Inflammation by Regulating Apoptosis, Oxidative Stress, and Bone Remodeling. Curr Issues Mol Biol 2023; 45:8755-8766. [PMID: 37998727 PMCID: PMC10670241 DOI: 10.3390/cimb45110550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 10/24/2023] [Accepted: 10/27/2023] [Indexed: 11/25/2023] Open
Abstract
Osteocytes play an important role as regulators of both osteoclasts and osteoblasts, and some proteins that are secreted from them play a role in bone remodeling and modeling. LPS affects bone structure because it is an inflammatory factor, despite verbascoside's potential for bone preservation and healing. Osteocytes may also be involved in the control of the bone's response to immunological changes in inflammatory situations. MLO-Y4 cells were cultured in either supplemented -MEM alone with a low serum to inhibit cell growth or media with LPS (10 ng/mL) and/or verbascoside (50 g/mL) to show the LPS effect. In our research, LPS treatment increased RANKL levels while decreasing OPG and RUNX2 expression. Treatment with verbascoside reduced RANKL expression. In our work, verbascoside increased the expression of OPG and RUNX2. In MLO-Y4 cells exposed to verbascoside, SOD, CAT, and GSH activities as well as the expression levels of bone mineralization proteins like PHEX, RUNX2, and OPG were all elevated.
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Affiliation(s)
- Sahika Pinar Akyer
- Department of Anatomy, School of Medicine, Pamukkale University, Kinikli, Str. No. 11, 20160 Denizli, Turkey;
| | - Ege Rıza Karagur
- Department of Medical Genetics, School of Medicine, Pamukkale University, Kinikli, Str. No. 11, 20160 Denizli, Turkey;
| | - Melek Tunc Ata
- Department of Physiology, School of Medicine, Pamukkale University, Kinikli, Str. No. 11, 20160 Denizli, Turkey; (M.T.A.); (E.K.T.)
| | - Emine Kilic Toprak
- Department of Physiology, School of Medicine, Pamukkale University, Kinikli, Str. No. 11, 20160 Denizli, Turkey; (M.T.A.); (E.K.T.)
| | - Aysegul Cort Donmez
- Department of Medical Biochemistry, School of Medicine, Pamukkale University, Kinikli, Str. No. 11, 20160 Denizli, Turkey;
| | - Baris Ozgur Donmez
- Department of Anatomy, School of Medicine, Pamukkale University, Kinikli, Str. No. 11, 20160 Denizli, Turkey;
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Atria PJ, Castillo AB. Skeletal adaptation to mechanical cues during homeostasis and repair: the niche, cells, and molecular signaling. Front Physiol 2023; 14:1233920. [PMID: 37916223 PMCID: PMC10616261 DOI: 10.3389/fphys.2023.1233920] [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: 06/03/2023] [Accepted: 10/02/2023] [Indexed: 11/03/2023] Open
Abstract
Bones constantly change and adapt to physical stress throughout a person's life. Mechanical signals are important regulators of bone remodeling and repair by activating skeletal stem and progenitor cells (SSPCs) to proliferate and differentiate into bone-forming osteoblasts using molecular signaling mechanisms not yet fully understood. SSPCs reside in a dynamic specialized microenvironment called the niche, where external signals integrate to influence cell maintenance, behavior and fate determination. The nature of the niche in bone, including its cellular and extracellular makeup and regulatory molecular signals, is not completely understood. The mechanisms by which the niche, with all of its components and complexity, is modulated by mechanical signals during homeostasis and repair are virtually unknown. This review summarizes the current view of the cells and signals involved in mechanical adaptation of bone during homeostasis and repair, with an emphasis on identifying novel targets for the prevention and treatment of age-related bone loss and hard-to-heal fractures.
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Affiliation(s)
- Pablo J. Atria
- Department of Orthopedic Surgery, New York University Grossman School of Medicine, New York, NY, United States
| | - Alesha B. Castillo
- Department of Orthopedic Surgery, New York University Grossman School of Medicine, New York, NY, United States
- Department of Biomedical Engineering, New York University Tandon School of Engineering, New York, NY, United States
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Noguchi S, Yamasaki R, Nagai-Yoshioka Y, Sato T, Kuroishi K, Gunjigake K, Ariyoshi W, Kawamoto T. The Mechanism of Interleukin 33-Induced Stimulation of Interleukin 6 in MLO-Y4 Cells. Int J Mol Sci 2023; 24:14842. [PMID: 37834290 PMCID: PMC10573633 DOI: 10.3390/ijms241914842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 09/22/2023] [Accepted: 09/29/2023] [Indexed: 10/15/2023] Open
Abstract
The differentiation and function of osteocytes are controlled by surrounding cells and mechanical stress; however, the detailed mechanisms are unknown. Recent findings suggest that IL-33 is highly expressed in periodontal tissues in orthodontic tooth movement. The present study aimed to elucidate the effect of IL-33 on the expression of regulatory factors for bone remodeling and their molecular mechanisms in the osteocyte-like cell line MLO-Y4. MLO-Y4 cells were treated with IL-33, and the activation of intracellular signaling molecules and transcriptional factors was determined using Western blot analysis and chromatin immunoprecipitation assay. IL-33 treatment enhanced the expression of IL-6 in MLO-Y4 cells, which was suppressed by the knockdown of the IL-33 receptor ST2L. Additionally, IL-33 treatment induced activation of NF-κB, JNK/AP-1, and p38 MAPK signaling pathways in MLO-Y4 cells. Moreover, pretreatment with specific inhibitors of NF-κB, p38 MAPK, and JNK/AP-1 attenuated the IL-33-induced expression of IL-6. Furthermore, chromatin immunoprecipitation indicated that IL-33 increased c-Jun recruitment to the IL-6 promoter. Overall, these results suggest that IL-33 induces IL-6 expression and regulates osteocyte function via activation of the NF-κB, JNK/AP-1, and p38 MAPK pathways through interaction with ST2L receptors on the plasma membrane.
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Affiliation(s)
- Sae Noguchi
- Division of Orofacial Functions and Orthodontics, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580, Japan; (S.N.); (K.K.); (K.G.); (T.K.)
- Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580, Japan; (R.Y.); (Y.N.-Y.)
| | - Ryota Yamasaki
- Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580, Japan; (R.Y.); (Y.N.-Y.)
| | - Yoshie Nagai-Yoshioka
- Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580, Japan; (R.Y.); (Y.N.-Y.)
| | - Tsuyoshi Sato
- Department of Oral and Maxillofacial Surgery, Saitama Medical University, 38 Moro-hongou, Moroyama-machi, Iruma-gun, Saitama 350-0495, Japan;
| | - Kayoko Kuroishi
- Division of Orofacial Functions and Orthodontics, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580, Japan; (S.N.); (K.K.); (K.G.); (T.K.)
| | - Kaori Gunjigake
- Division of Orofacial Functions and Orthodontics, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580, Japan; (S.N.); (K.K.); (K.G.); (T.K.)
| | - Wataru Ariyoshi
- Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580, Japan; (R.Y.); (Y.N.-Y.)
| | - Tatsuo Kawamoto
- Division of Orofacial Functions and Orthodontics, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580, Japan; (S.N.); (K.K.); (K.G.); (T.K.)
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6
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Anesi A, Ferretti M, Salvatori R, Bellucci D, Cavani F, Di Bartolomeo M, Palumbo C, Cannillo V. In-vivo evaluations of bone regenerative potential of two novel bioactive glasses. J Biomed Mater Res A 2023; 111:1264-1278. [PMID: 36876550 DOI: 10.1002/jbm.a.37526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 02/13/2023] [Accepted: 02/23/2023] [Indexed: 03/07/2023]
Abstract
Due to the aging of population, materials able to repair damaged tissues are needed. Among others, bioactive glasses (BGs) have attracted a lot of interest due to their outstanding properties both for hard and soft tissues. Here, for the first time, two new BGs, which gave very promising results in preliminary in vitro-tests, were implanted in animals in order to evaluate their regenerative potential. The new BGs, named BGMS10 and Bio_MS and containing specific therapeutic ions, were produced in granules and implanted in rabbits' femurs for up to 60 days, to test their biocompatibility and osteoconduction. Additionally, granules of 45S5 Bioglass® were employed and used as a standard reference for comparison. The results showed that, after 30 days, the two novel BGs and 45S5 displayed a similar behavior, in terms of bone amount, thickness of new bone trabeculae and affinity index. On the contrary, after 60 days, 45S5 granules were mainly surrounded by wide and scattered bone trabeculae, separated by large amounts of soft tissue, while in BGMS10 and Bio_MS the trabeculae were thin and uniformly distributed around the BG granules. This latter scenario could be considered as more advantageous, since the features of the two novel BG granules allowed for the neo-formation of a uniformly distributed bony trabeculae, predictive of more favorable mechanical behavior, compared to the less uniform coarse trabeculae, separated by large areas of soft tissue in 45S5 granules. Thus, BGMS10 and Bio_MS could be considered suitable products for tissue regeneration in the orthopedic and dental fields.
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Affiliation(s)
- A Anesi
- Laboratorio Biomateriali, Dipartimento di Scienze Mediche e Chirurgiche Materno-Infantili e dell'Adulto, Università degli Studi di Modena e Reggio Emilia, Modena, Italy
| | - M Ferretti
- Dipartimento di Scienze Biomediche, Metaboliche e Neuroscienze - Sezione di Morfologia umana (c/o Policlinico), Università degli Studi di Modena e Reggio Emilia, Modena, Italy
| | - R Salvatori
- Laboratorio Biomateriali, Dipartimento di Scienze Mediche e Chirurgiche Materno-Infantili e dell'Adulto, Università degli Studi di Modena e Reggio Emilia, Modena, Italy
| | - D Bellucci
- Dipartimento di Ingegneria "Enzo Ferrari", Università degli Studi di Modena e Reggio Emilia, Modena, Italy
| | - F Cavani
- Dipartimento di Scienze Biomediche, Metaboliche e Neuroscienze - Sezione di Morfologia umana (c/o Policlinico), Università degli Studi di Modena e Reggio Emilia, Modena, Italy
| | - M Di Bartolomeo
- Chirurgia Maxillo Facciale e Odontostomatologia, Dipartimento di Scienze Chirurgiche Odontostomatologiche e Materno-Infantili, Università degli Studi di Verona, Verona, Italy
| | - C Palumbo
- Dipartimento di Scienze Biomediche, Metaboliche e Neuroscienze - Sezione di Morfologia umana (c/o Policlinico), Università degli Studi di Modena e Reggio Emilia, Modena, Italy
| | - V Cannillo
- Dipartimento di Ingegneria "Enzo Ferrari", Università degli Studi di Modena e Reggio Emilia, Modena, Italy
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Palumbo C, Ferretti M. Morphology and cell biology - two sides of the same coin: Importance of morphology in choosing Cre experimental models for targeting osteoblasts vs osteocytes. Bone 2023; 173:116790. [PMID: 37182755 DOI: 10.1016/j.bone.2023.116790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 05/06/2023] [Indexed: 05/16/2023]
Abstract
The present letter to editor comments the manuscript entitled "Targeting osteocytes vs osteoblasts" by Y. Kitase and M. Prideaux, where we underlie the importance morphology in choosing Cre experimental models for targeting osteoblasts vs osteocytes.
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Affiliation(s)
- Carla Palumbo
- Section of Human Morphology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Anatomical Institutes, Via del Pozzo 71, 41124 Modena, Italy.
| | - Marzia Ferretti
- Section of Human Morphology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Anatomical Institutes, Via del Pozzo 71, 41124 Modena, Italy
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8
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Heng BC, Bai Y, Li X, Meng Y, Lu Y, Zhang X, Deng X. The bioelectrical properties of bone tissue. Animal Model Exp Med 2023; 6:120-130. [PMID: 36856186 PMCID: PMC10158952 DOI: 10.1002/ame2.12300] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 11/18/2022] [Indexed: 03/02/2023] Open
Abstract
Understanding the bioelectrical properties of bone tissue is key to developing new treatment strategies for bone diseases and injuries, as well as improving the design and fabrication of scaffold implants for bone tissue engineering. The bioelectrical properties of bone tissue can be attributed to the interaction of its various cell lineages (osteocyte, osteoblast and osteoclast) with the surrounding extracellular matrix, in the presence of various biomechanical stimuli arising from routine physical activities; and is best described as a combination and overlap of dielectric, piezoelectric, pyroelectric and ferroelectric properties, together with streaming potential and electro-osmosis. There is close interdependence and interaction of the various electroactive and electrosensitive components of bone tissue, including cell membrane potential, voltage-gated ion channels, intracellular signaling pathways, and cell surface receptors, together with various matrix components such as collagen, hydroxyapatite, proteoglycans and glycosaminoglycans. It is the remarkably complex web of interactive cross-talk between the organic and non-organic components of bone that define its electrophysiological properties, which in turn exerts a profound influence on its metabolism, homeostasis and regeneration in health and disease. This has spurred increasing interest in application of electroactive scaffolds in bone tissue engineering, to recapitulate the natural electrophysiological microenvironment of healthy bone tissue to facilitate bone defect repair.
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Affiliation(s)
- Boon Chin Heng
- Department of Dental Materials & Dental Medical Devices Testing Center, Peking University School and Hospital of Stomatology, Beijing, PR China.,Central Laboratory, Peking University School and Hospital of Stomatology, Beijing, PR China.,School of Medical and Life Sciences, Sunway University, Subang Jaya, Malaysia
| | - Yunyang Bai
- Department of Geriatric Dentistry, Peking University School and Hospital of Stomatology, Beijing, PR China
| | - Xiaochan Li
- Department of Geriatric Dentistry, Peking University School and Hospital of Stomatology, Beijing, PR China
| | - Yanze Meng
- Department of Dental Materials & Dental Medical Devices Testing Center, Peking University School and Hospital of Stomatology, Beijing, PR China
| | - Yanhui Lu
- Department of Dental Materials & Dental Medical Devices Testing Center, Peking University School and Hospital of Stomatology, Beijing, PR China
| | - Xuehui Zhang
- Department of Dental Materials & Dental Medical Devices Testing Center, Peking University School and Hospital of Stomatology, Beijing, PR China.,National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, NMPA Key Laboratory for Dental Materials, Beijing Laboratory of Biomedical Materials & Beijing Key Laboratory of Digital Stomatology, Peking University School and Hospital of Stomatology, Beijing, People's Republic of China
| | - Xuliang Deng
- Department of Geriatric Dentistry, Peking University School and Hospital of Stomatology, Beijing, PR China.,National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, NMPA Key Laboratory for Dental Materials, Beijing Laboratory of Biomedical Materials & Beijing Key Laboratory of Digital Stomatology, Peking University School and Hospital of Stomatology, Beijing, People's Republic of China
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9
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Zappalà A, Romano IR, D’Angeli F, Musumeci G, Lo Furno D, Giuffrida R, Mannino G. Functional Roles of Connexins and Gap Junctions in Osteo-Chondral Cellular Components. Int J Mol Sci 2023; 24:ijms24044156. [PMID: 36835567 PMCID: PMC9967557 DOI: 10.3390/ijms24044156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 02/14/2023] [Accepted: 02/17/2023] [Indexed: 02/22/2023] Open
Abstract
Gap junctions (GJs) formed by connexins (Cxs) play an important role in the intercellular communication within most body tissues. In this paper, we focus on GJs and Cxs present in skeletal tissues. Cx43 is the most expressed connexin, participating in the formation of both GJs for intercellular communication and hemichannels (HCs) for communication with the external environment. Through GJs in long dendritic-like cytoplasmic processes, osteocytes embedded in deep lacunae are able to form a functional syncytium not only with neighboring osteocytes but also with bone cells located at the bone surface, despite the surrounding mineralized matrix. The functional syncytium allows a coordinated cell activity through the wide propagation of calcium waves, nutrients and anabolic and/or catabolic factors. Acting as mechanosensors, osteocytes are able to transduce mechanical stimuli into biological signals that spread through the syncytium to orchestrate bone remodeling. The fundamental role of Cxs and GJs is confirmed by a plethora of investigations that have highlighted how up- and downregulation of Cxs and GJs critically influence skeletal development and cartilage functions. A better knowledge of GJ and Cx mechanisms in physiological and pathological conditions might help in developing therapeutic approaches aimed at the treatment of human skeletal system disorders.
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Affiliation(s)
- Agata Zappalà
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
| | - Ivana Roberta Romano
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
| | - Floriana D’Angeli
- Department of Human Sciences and Quality of Life Promotion, San Raffaele Roma Open University, 00166 Rome, Italy
| | - Giuseppe Musumeci
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
| | - Debora Lo Furno
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
- Correspondence: (D.L.F.); (R.G.)
| | - Rosario Giuffrida
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
- Correspondence: (D.L.F.); (R.G.)
| | - Giuliana Mannino
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98122 Messina, Italy
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10
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Liu X, Yan Z, Cai J, Wang D, Yang Y, Ding Y, Shao X, Hao X, Luo E, Guo XE, Luo P, Shen L, Jing D. Glucose- and glutamine-dependent bioenergetics sensitize bone mechanoresponse after unloading by modulating osteocyte calcium dynamics. J Clin Invest 2023; 133:164508. [PMID: 36512405 PMCID: PMC9888392 DOI: 10.1172/jci164508] [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: 08/15/2022] [Accepted: 12/08/2022] [Indexed: 12/15/2022] Open
Abstract
Disuse osteoporosis is a metabolic bone disease resulting from skeletal unloading (e.g., during extended bed rest, limb immobilization, and spaceflight), and the slow and insufficient bone recovery during reambulation remains an unresolved medical challenge. Here, we demonstrated that loading-induced increase in bone architecture/strength was suppressed in skeletons previously exposed to unloading. This reduction in bone mechanosensitivity was directly associated with attenuated osteocytic Ca2+ oscillatory dynamics. The unloading-induced compromised osteocytic Ca2+ response to reloading resulted from the HIF-1α/PDK1 axis-mediated increase in glycolysis, and a subsequent reduction in ATP synthesis. HIF-1α also transcriptionally induced substantial glutaminase 2 expression and thereby glutamine addiction in osteocytes. Inhibition of glycolysis by blockade of PDK1 or glutamine supplementation restored the mechanosensitivity in those skeletons with previous unloading by fueling the tricarboxylic acid cycle and rescuing subsequent Ca2+ oscillations in osteocytes. Thus, we provide mechanistic insight into disuse-induced deterioration of bone mechanosensitivity and a promising therapeutic approach to accelerate bone recovery after long-duration disuse.
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Affiliation(s)
- Xiyu Liu
- Department of Biomedical Engineering, Fourth Military Medical University, Xi’an, China
| | - Zedong Yan
- Department of Biomedical Engineering, Fourth Military Medical University, Xi’an, China
| | - Jing Cai
- College of Basic Medicine, Shaanxi University of Chinese Medicine, Xianyang, China
| | - Dan Wang
- Department of Biomedical Engineering, Fourth Military Medical University, Xi’an, China
| | - Yongqing Yang
- Department of Biomedical Engineering, Fourth Military Medical University, Xi’an, China
| | - Yuanjun Ding
- Department of Biomedical Engineering, Fourth Military Medical University, Xi’an, China
| | - Xi Shao
- Department of Biomedical Engineering, Fourth Military Medical University, Xi’an, China
| | - Xiaoxia Hao
- Department of Biomedical Engineering, Fourth Military Medical University, Xi’an, China
| | - Erping Luo
- Department of Biomedical Engineering, Fourth Military Medical University, Xi’an, China
| | - X. Edward Guo
- Bone Bioengineering Laboratory, Department of Biomedical Engineering, Columbia University, New York, New York, USA
| | - Peng Luo
- Department of Neurosurgery, Xijing Hospital
| | - Liangliang Shen
- State Key Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology
| | - Da Jing
- Department of Biomedical Engineering, Fourth Military Medical University, Xi’an, China.,Ministry of Education Key Lab of Hazard Assessment and Control in Special Operational Environment, and,Shaanxi Provincial Key Laboratory of Bioelectromagnetic Detection and Intelligent Perception, Fourth Military Medical University, Xi’an, China
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11
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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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12
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Chen W, Wu P, Yu F, Luo G, Qing L, Tang J. HIF-1α Regulates Bone Homeostasis and Angiogenesis, Participating in the Occurrence of Bone Metabolic Diseases. Cells 2022; 11:cells11223552. [PMID: 36428981 PMCID: PMC9688488 DOI: 10.3390/cells11223552] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 10/16/2022] [Accepted: 11/07/2022] [Indexed: 11/12/2022] Open
Abstract
In the physiological condition, the skeletal system's bone resorption and formation are in dynamic balance, called bone homeostasis. However, bone homeostasis is destroyed under pathological conditions, leading to the occurrence of bone metabolism diseases. The expression of hypoxia-inducible factor-1α (HIF-1α) is regulated by oxygen concentration. It affects energy metabolism, which plays a vital role in preventing bone metabolic diseases. This review focuses on the HIF-1α pathway and describes in detail the possible mechanism of its involvement in the regulation of bone homeostasis and angiogenesis, as well as the current experimental studies on the use of HIF-1α in the prevention of bone metabolic diseases. HIF-1α/RANKL/Notch1 pathway bidirectionally regulates the differentiation of macrophages into osteoclasts under different conditions. In addition, HIF-1α is also regulated by many factors, including hypoxia, cofactor activity, non-coding RNA, trace elements, etc. As a pivotal pathway for coupling angiogenesis and osteogenesis, HIF-1α has been widely studied in bone metabolic diseases such as bone defect, osteoporosis, osteonecrosis of the femoral head, fracture, and nonunion. The wide application of biomaterials in bone metabolism also provides a reasonable basis for the experimental study of HIF-1α in preventing bone metabolic diseases.
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13
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Hasegawa T, Hongo H, Yamamoto T, Abe M, Yoshino H, Haraguchi-Kitakamae M, Ishizu H, Shimizu T, Iwasaki N, Amizuka N. Matrix Vesicle-Mediated Mineralization and Osteocytic Regulation of Bone Mineralization. Int J Mol Sci 2022; 23:ijms23179941. [PMID: 36077336 PMCID: PMC9456179 DOI: 10.3390/ijms23179941] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 08/23/2022] [Accepted: 08/29/2022] [Indexed: 11/16/2022] Open
Abstract
Bone mineralization entails two mineralization phases: primary and secondary mineralization. Primary mineralization is achieved when matrix vesicles are secreted by osteoblasts, and thereafter, bone mineral density gradually increases during secondary mineralization. Nearby extracellular phosphate ions (PO43−) flow into the vesicles via membrane transporters and enzymes located on the vesicles’ membranes, while calcium ions (Ca2+), abundant in the tissue fluid, are also transported into the vesicles. The accumulation of Ca2+ and PO43− in the matrix vesicles induces crystal nucleation and growth. The calcium phosphate crystals grow radially within the vesicle, penetrate the vesicle’s membrane, and continue to grow outside the vesicle, ultimately forming mineralized nodules. The mineralized nodules then attach to collagen fibrils, mineralizing them from the contact sites (i.e., collagen mineralization). Afterward, the bone mineral density gradually increases during the secondary mineralization process. The mechanisms of this phenomenon remain unclear, but osteocytes may play a key role; it is assumed that osteocytes enable the transport of Ca2+ and PO43− through the canaliculi of the osteocyte network, as well as regulate the mineralization of the surrounding bone matrix via the Phex/SIBLINGs axis. Thus, bone mineralization is biologically regulated by osteoblasts and osteocytes.
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Affiliation(s)
- Tomoka Hasegawa
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, Faculty of Dental Medicine, Hokkaido University, Sapporo 060-8586, Japan
- Correspondence: (T.H.); (N.A.); Tel.: +81-11-706-4226 (T.H.); +81-11-706-4223 (N.A.)
| | - Hiromi Hongo
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, Faculty of Dental Medicine, Hokkaido University, Sapporo 060-8586, Japan
| | - Tomomaya Yamamoto
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, Faculty of Dental Medicine, Hokkaido University, Sapporo 060-8586, Japan
- Northern Army Medical Unit, Camp Makomanai, Japan Ground Self-Defense Forces, Sapporo 005-8543, Japan
| | - Miki Abe
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, Faculty of Dental Medicine, Hokkaido University, Sapporo 060-8586, Japan
| | - Hirona Yoshino
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, Faculty of Dental Medicine, Hokkaido University, Sapporo 060-8586, Japan
| | - Mai Haraguchi-Kitakamae
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, Faculty of Dental Medicine, Hokkaido University, Sapporo 060-8586, Japan
- Division of Craniofacial Development and Tissue Biology, Graduate School of Dentistry, Tohoku University, Sendai 980-8577, Japan
| | - Hotaka Ishizu
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, Faculty of Dental Medicine, Hokkaido University, Sapporo 060-8586, Japan
- Orthopedic Surgery, Faculty of Medicine, Hokkaido University, Sapporo 060-8638, Japan
| | - Tomohiro Shimizu
- Orthopedic Surgery, Faculty of Medicine, Hokkaido University, Sapporo 060-8638, Japan
| | - Norimasa Iwasaki
- Orthopedic Surgery, Faculty of Medicine, Hokkaido University, Sapporo 060-8638, Japan
| | - Norio Amizuka
- Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, Faculty of Dental Medicine, Hokkaido University, Sapporo 060-8586, Japan
- Correspondence: (T.H.); (N.A.); Tel.: +81-11-706-4226 (T.H.); +81-11-706-4223 (N.A.)
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14
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Bolamperti S, Villa I, Rubinacci A. Bone remodeling: an operational process ensuring survival and bone mechanical competence. Bone Res 2022; 10:48. [PMID: 35851054 PMCID: PMC9293977 DOI: 10.1038/s41413-022-00219-8] [Citation(s) in RCA: 91] [Impact Index Per Article: 45.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 05/02/2022] [Accepted: 05/15/2022] [Indexed: 12/12/2022] Open
Abstract
Bone remodeling replaces old and damaged bone with new bone through a sequence of cellular events occurring on the same surface without any change in bone shape. It was initially thought that the basic multicellular unit (BMU) responsible for bone remodeling consists of osteoclasts and osteoblasts functioning through a hierarchical sequence of events organized into distinct stages. However, recent discoveries have indicated that all bone cells participate in BMU formation by interacting both simultaneously and at different differentiation stages with their progenitors, other cells, and bone matrix constituents. Therefore, bone remodeling is currently considered a physiological outcome of continuous cellular operational processes optimized to confer a survival advantage. Bone remodeling defines the primary activities that BMUs need to perform to renew successfully bone structural units. Hence, this review summarizes the current understanding of bone remodeling and future research directions with the aim of providing a clinically relevant biological background with which to identify targets for therapeutic strategies in osteoporosis.
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Affiliation(s)
- Simona Bolamperti
- Osteoporosis and Bone and Mineral Metabolism Unit, IRCCS San Raffaele Hospital, Via Olgettina 60, 20132, Milano, Italy
| | - Isabella Villa
- Osteoporosis and Bone and Mineral Metabolism Unit, IRCCS San Raffaele Hospital, Via Olgettina 60, 20132, Milano, Italy
| | - Alessandro Rubinacci
- Osteoporosis and Bone and Mineral Metabolism Unit, IRCCS San Raffaele Hospital, Via Olgettina 60, 20132, Milano, Italy.
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15
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Effects of BMSC-Derived EVs on Bone Metabolism. Pharmaceutics 2022; 14:pharmaceutics14051012. [PMID: 35631601 PMCID: PMC9146387 DOI: 10.3390/pharmaceutics14051012] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 05/03/2022] [Accepted: 05/06/2022] [Indexed: 01/27/2023] Open
Abstract
Extracellular vesicles (EVs) are small membrane vesicles that can be secreted by most cells. EVs can be released into the extracellular environment through exocytosis, transporting endogenous cargo (proteins, lipids, RNAs, etc.) to target cells and thereby triggering the release of these biomolecules and participating in various physiological and pathological processes. Among them, EVs derived from bone marrow mesenchymal stem cells (BMSC-EVs) have similar therapeutic effects to BMSCs, including repairing damaged tissues, inhibiting macrophage polarization and promoting angiogenesis. In addition, BMSC-EVs, as efficient and feasible natural nanocarriers for drug delivery, have the advantages of low immunogenicity, no ethical controversy, good stability and easy storage, thus providing a promising therapeutic strategy for many diseases. In particular, BMSC-EVs show great potential in the treatment of bone metabolic diseases. This article reviews the mechanism of BMSC-EVs in bone formation and bone resorption, which provides new insights for future research on therapeutic strategies for bone metabolic diseases.
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16
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Oton-Gonzalez L, Mazziotta C, Iaquinta MR, Mazzoni E, Nocini R, Trevisiol L, D’Agostino A, Tognon M, Rotondo JC, Martini F. Genetics and Epigenetics of Bone Remodeling and Metabolic Bone Diseases. Int J Mol Sci 2022; 23:ijms23031500. [PMID: 35163424 PMCID: PMC8836080 DOI: 10.3390/ijms23031500] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Revised: 01/24/2022] [Accepted: 01/26/2022] [Indexed: 02/06/2023] Open
Abstract
Bone metabolism consists of a balance between bone formation and bone resorption, which is mediated by osteoblast and osteoclast activity, respectively. In order to ensure bone plasticity, the bone remodeling process needs to function properly. Mesenchymal stem cells differentiate into the osteoblast lineage by activating different signaling pathways, including transforming growth factor β (TGF-β)/bone morphogenic protein (BMP) and the Wingless/Int-1 (Wnt)/β-catenin pathways. Recent data indicate that bone remodeling processes are also epigenetically regulated by DNA methylation, histone post-translational modifications, and non-coding RNA expressions, such as micro-RNAs, long non-coding RNAs, and circular RNAs. Mutations and dysfunctions in pathways regulating the osteoblast differentiation might influence the bone remodeling process, ultimately leading to a large variety of metabolic bone diseases. In this review, we aim to summarize and describe the genetics and epigenetics of the bone remodeling process. Moreover, the current findings behind the genetics of metabolic bone diseases are also reported.
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Affiliation(s)
- Lucia Oton-Gonzalez
- Department of Medical Sciences, University of Ferrara, 64/b, Fossato di Mortara Street, 44121 Ferrara, Italy; (L.O.-G.); (C.M.); (M.R.I.); (M.T.)
| | - Chiara Mazziotta
- Department of Medical Sciences, University of Ferrara, 64/b, Fossato di Mortara Street, 44121 Ferrara, Italy; (L.O.-G.); (C.M.); (M.R.I.); (M.T.)
- Center for Studies on Gender Medicine, Department of Medical Sciences, University of Ferrara, 44121 Ferrara, Italy
| | - Maria Rosa Iaquinta
- Department of Medical Sciences, University of Ferrara, 64/b, Fossato di Mortara Street, 44121 Ferrara, Italy; (L.O.-G.); (C.M.); (M.R.I.); (M.T.)
- Center for Studies on Gender Medicine, Department of Medical Sciences, University of Ferrara, 44121 Ferrara, Italy
| | - Elisa Mazzoni
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, 44121 Ferrara, Italy;
| | - Riccardo Nocini
- Unit of Otolaryngology, University of Verona, 37134 Verona, Italy;
| | - Lorenzo Trevisiol
- Unit of Maxillo-Facial Surgery and Dentistry, University of Verona, 37134 Verona, Italy; (L.T.); (A.D.)
| | - Antonio D’Agostino
- Unit of Maxillo-Facial Surgery and Dentistry, University of Verona, 37134 Verona, Italy; (L.T.); (A.D.)
| | - Mauro Tognon
- Department of Medical Sciences, University of Ferrara, 64/b, Fossato di Mortara Street, 44121 Ferrara, Italy; (L.O.-G.); (C.M.); (M.R.I.); (M.T.)
| | - John Charles Rotondo
- Department of Medical Sciences, University of Ferrara, 64/b, Fossato di Mortara Street, 44121 Ferrara, Italy; (L.O.-G.); (C.M.); (M.R.I.); (M.T.)
- Center for Studies on Gender Medicine, Department of Medical Sciences, University of Ferrara, 44121 Ferrara, Italy
- Correspondence: (J.C.R.); (F.M.); Tel.: +39-0532-455536 (J.C.R.); +39-0532-455540 (F.M.)
| | - Fernanda Martini
- Department of Medical Sciences, University of Ferrara, 64/b, Fossato di Mortara Street, 44121 Ferrara, Italy; (L.O.-G.); (C.M.); (M.R.I.); (M.T.)
- Center for Studies on Gender Medicine, Department of Medical Sciences, University of Ferrara, 44121 Ferrara, Italy
- Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, 44121 Ferrara, Italy
- Correspondence: (J.C.R.); (F.M.); Tel.: +39-0532-455536 (J.C.R.); +39-0532-455540 (F.M.)
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17
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Leser JM, Harriot A, Buck HV, Ward CW, Stains JP. Aging, Osteo-Sarcopenia, and Musculoskeletal Mechano-Transduction. FRONTIERS IN REHABILITATION SCIENCES 2021; 2:782848. [PMID: 36004321 PMCID: PMC9396756 DOI: 10.3389/fresc.2021.782848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 11/10/2021] [Indexed: 11/13/2022]
Abstract
The decline in the mass and function of bone and muscle is an inevitable consequence of healthy aging with early onset and accelerated decline in those with chronic disease. Termed osteo-sarcopenia, this condition predisposes the decreased activity, falls, low-energy fractures, and increased risk of co-morbid disease that leads to musculoskeletal frailty. The biology of osteo-sarcopenia is most understood in the context of systemic neuro-endocrine and immune/inflammatory alterations that drive inflammation, oxidative stress, reduced autophagy, and cellular senescence in the bone and muscle. Here we integrate these concepts to our growing understanding of how bone and muscle senses, responds and adapts to mechanical load. We propose that age-related alterations in cytoskeletal mechanics alter load-sensing and mechano-transduction in bone osteocytes and muscle fibers which underscores osteo-sarcopenia. Lastly, we examine the evidence for exercise as an effective countermeasure to osteo-sarcopenia.
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Affiliation(s)
| | | | | | | | - Joseph P. Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, United States
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18
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Abstract
MicroRNAs, identified in the early 1990s, are believed to regulate approximately 30% of the human genome. The role of microRNA in bone cells was first reported in 2007 in a manuscript showing that microRNA-223 is essential for osteoclast differentiation in vitro, and a few studies reported a role of microRNAs in osteoblasts the same year. The first report of microRNA actions in osteocytes was published in 2010, in which it was demonstrated that the microRNA cluster 23a~27a~24-2 regulates osteocyte differentiation. Since then, few studies have described the role of these 18-25-nucleotide non-coding RNAs on osteocyte biology, reporting osteocytes both as producers and as targets of the actions of microRNAs. We review here the current knowledge on the effects of microRNAs on osteocyte biology.
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Affiliation(s)
- Lilian I Plotkin
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, USA; Indiana Center for Musculoskeletal Health, USA.
| | - Joseph M Wallace
- Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202, USA
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19
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Osteocyte Dysfunction in Joint Homeostasis and Osteoarthritis. Int J Mol Sci 2021; 22:ijms22126522. [PMID: 34204587 PMCID: PMC8233862 DOI: 10.3390/ijms22126522] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 06/13/2021] [Accepted: 06/16/2021] [Indexed: 01/29/2023] Open
Abstract
Structural disturbances of the subchondral bone are a hallmark of osteoarthritis (OA), including sclerotic changes, cystic lesions, and osteophyte formation. Osteocytes act as mechanosensory units for the micro-cracks in response to mechanical loading. Once stimulated, osteocytes initiate the reparative process by recruiting bone-resorbing cells and bone-forming cells to maintain bone homeostasis. Osteocyte-expressed sclerostin is known as a negative regulator of bone formation through Wnt signaling and the RANKL pathway. In this review, we will summarize current understandings of osteocytes at the crossroad of allometry and mechanobiology to exploit the relationship between osteocyte morphology and function in the context of joint aging and osteoarthritis. We also aimed to summarize the osteocyte dysfunction and its link with structural and functional disturbances of the osteoarthritic subchondral bone at the molecular level. Compared with normal bones, the osteoarthritic subchondral bone is characterized by a higher bone volume fraction, a larger trabecular bone number in the load-bearing region, and an increase in thickness of pre-existing trabeculae. This may relate to the aberrant expressions of sclerostin, periostin, dentin matrix protein 1, matrix extracellular phosphoglycoprotein, insulin-like growth factor 1, and transforming growth factor-beta, among others. The number of osteocyte lacunae embedded in OA bone is also significantly higher, yet the volume of individual lacuna is relatively smaller, which could suggest abnormal metabolism in association with allometry. The remarkably lower percentage of sclerostin-positive osteocytes, together with clustering of Runx-2 positive pre-osteoblasts, may suggest altered regulation of osteoblast differentiation and osteoblast-osteocyte transformation affected by both signaling molecules and the extracellular matrix. Aberrant osteocyte morphology and function, along with anomalies in molecular signaling mechanisms, might explain in part, if not all, the pre-osteoblast clustering and the uncoupled bone remodeling in OA subchondral bone.
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