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Risbud M, Madhu V, Hernandez-Meadows M, Coleman A, Sao K, Inguito K, Haslam O, Boneski P, Sesaki H, Collins J. The loss of OPA1 accelerates intervertebral disc degeneration and osteoarthritis in aged mice. Res Sq 2024:rs.3.rs-3950044. [PMID: 38464287 PMCID: PMC10925423 DOI: 10.21203/rs.3.rs-3950044/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
NP cells of the intervertebral disc and articular chondrocytes reside in avascular and hypoxic tissue niches. As a consequence of these environmental constraints the cells are primarily glycolytic in nature and were long thought to have a minimal reliance on mitochondrial function. Recent studies have challenged this long-held view and highlighted the increasingly important role of mitochondria in the physiology of these tissues. However, the foundational understanding of mechanisms governing mitochondrial dynamics and function in these tissues is lacking. We investigated the role of mitochondrial fusion protein OPA1 in maintaining the spine and knee joint health in mice. OPA1 knockdown in NP cells altered mitochondrial size and cristae shape and increased the oxygen consumption rate without affecting ATP synthesis. OPA1 governed the morphology of multiple organelles, including peroxisomes, early endosomes and cis-Golgi and its loss resulted in the dysregulation of NP cell autophagy. Metabolic profiling and 13C-flux analyses revealed TCA cycle anaplerosis and altered metabolism in OPA1-deficient NP cells. Noteworthy, Opa1AcanCreERT2 mice with Opa1 deletion in disc and cartilage showed age-dependent disc degeneration, osteoarthritis, and vertebral osteopenia. Our findings underscore that OPA1 regulation of mitochondrial dynamics and multi-organelle interactions is critical in preserving metabolic homeostasis of disc and cartilage.
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Novais EJ, Narayanan R, Canseco JA, van de Wetering K, Kepler CK, Hilibrand AS, Vaccaro AR, Risbud MV. A new perspective on intervertebral disc calcification-from bench to bedside. Bone Res 2024; 12:3. [PMID: 38253615 PMCID: PMC10803356 DOI: 10.1038/s41413-023-00307-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Revised: 12/04/2023] [Accepted: 12/05/2023] [Indexed: 01/24/2024] Open
Abstract
Disc degeneration primarily contributes to chronic low back and neck pain. Consequently, there is an urgent need to understand the spectrum of disc degeneration phenotypes such as fibrosis, ectopic calcification, herniation, or mixed phenotypes. Amongst these phenotypes, disc calcification is the least studied. Ectopic calcification, by definition, is the pathological mineralization of soft tissues, widely studied in the context of conditions that afflict vasculature, skin, and cartilage. Clinically, disc calcification is associated with poor surgical outcomes and back pain refractory to conservative treatment. It is frequently seen as a consequence of disc aging and progressive degeneration but exhibits unique molecular and morphological characteristics: hypertrophic chondrocyte-like cell differentiation; TNAP, ENPP1, and ANK upregulation; cell death; altered Pi and PPi homeostasis; and local inflammation. Recent studies in mouse models have provided a better understanding of the mechanisms underlying this phenotype. It is essential to recognize that the presentation and nature of mineralization differ between AF, NP, and EP compartments. Moreover, the combination of anatomic location, genetics, and environmental stressors, such as aging or trauma, govern the predisposition to calcification. Lastly, the systemic regulation of calcium and Pi metabolism is less important than the local activity of PPi modulated by the ANK-ENPP1 axis, along with disc cell death and differentiation status. While there is limited understanding of this phenotype, understanding the molecular pathways governing local intervertebral disc calcification may lead to developing disease-modifying drugs and better clinical management of degeneration-related pathologies.
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Affiliation(s)
- Emanuel J Novais
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
- Unidade Local de Saúde do Litoral Alentejano, Orthopedic Department, Santiago do Cacém, Portugal
| | - Rajkishen Narayanan
- Rothman Orthopedic Institute at Thomas Jefferson University, Philadelphia, PA, USA
| | - Jose A Canseco
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
- Rothman Orthopedic Institute at Thomas Jefferson University, Philadelphia, PA, USA
| | - Koen van de Wetering
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - Christopher K Kepler
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
- Rothman Orthopedic Institute at Thomas Jefferson University, Philadelphia, PA, USA
| | - Alan S Hilibrand
- Rothman Orthopedic Institute at Thomas Jefferson University, Philadelphia, PA, USA
| | - Alexander R Vaccaro
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
- Rothman Orthopedic Institute at Thomas Jefferson University, Philadelphia, PA, USA
| | - Makarand V Risbud
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.
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Madhu V, Hernandaz-Meadows M, Coleman A, Sao K, Inguito K, Haslam O, Boneski PK, Sesaki H, Collins JA, Risbud MV. OPA1 protects intervertebral disc and knee joint health in aged mice by maintaining the structure and metabolic functions of mitochondria. bioRxiv 2024:2024.01.17.576115. [PMID: 38293153 PMCID: PMC10827164 DOI: 10.1101/2024.01.17.576115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Due to their glycolytic nature and limited vascularity, nucleus pulposus (NP) cells of the intervertebral disc and articular chondrocytes were long thought to have minimal reliance on mitochondrial function. Recent studies have challenged this long-held view and highlighted the increasingly important role of mitochondria in the physiology of these tissues. We investigated the role of mitochondrial fusion protein OPA1 in maintaining the spine and knee joint health in aging mice. OPA1 knockdown in NP cells altered mitochondrial size and cristae shape and increased the oxygen consumption rate without affecting ATP synthesis. OPA1 governed the morphology of multiple organelles, and its loss resulted in the dysregulation of NP cell autophagy. Metabolic profiling and 13 C-flux analyses revealed TCA cycle anaplerosis and altered metabolism in OPA1-deficient NP cells. Noteworthy, Opa1 AcanCreERT2 mice showed age- dependent disc, and cartilage degeneration and vertebral osteopenia. Our findings suggest that OPA1 regulation of mitochondrial dynamics and multi-organelle interactions is critical in preserving metabolic homeostasis of disc and cartilage. Teaser OPA1 is necessary for the maintenance of intervertebral disc and knee joint health in aging mice.
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Chen N, Wu RW, Lam Y, Chan WC, Chan D. Hypertrophic chondrocytes at the junction of musculoskeletal structures. Bone Rep 2023; 19:101698. [PMID: 37485234 PMCID: PMC10359737 DOI: 10.1016/j.bonr.2023.101698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 06/12/2023] [Accepted: 07/01/2023] [Indexed: 07/25/2023] Open
Abstract
Hypertrophic chondrocytes are found at unique locations at the junction of skeletal tissues, cartilage growth plate, articular cartilage, enthesis and intervertebral discs. Their role in the skeleton is best understood in the process of endochondral ossification in development and bone fracture healing. Chondrocyte hypertrophy occurs in degenerative conditions such as osteoarthritis. Thus, the role of hypertrophic chondrocytes in skeletal biology and pathology is context dependent. This review will focus on hypertrophic chondrocytes in endochondral ossification, in which they exist in a transient state, but acting as a central regulator of differentiation, mineralization, vascularization and conversion to bone. The amazing journey of a chondrocyte from being entrapped in the extracellular matrix environment to becoming proliferative then hypertrophic will be discussed. Recent studies on the dynamic changes and plasticity of hypertrophic chondrocytes have provided new insights into how we view these cells, not as terminally differentiated but as cells that can dedifferentiate to more progenitor-like cells in a transition to osteoblasts and adipocytes, as well as a source of skeletal stem and progenitor cells residing in the bone marrow. This will provide a foundation for studies of hypertrophic chondrocytes at other skeletal sites in development, tissue maintenance, pathology and therapy.
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Affiliation(s)
- Ning Chen
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Robin W.H. Wu
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Yan Lam
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Wilson C.W. Chan
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
- Department of Orthopaedics Surgery and Traumatology, The University of Hong Kong-Shenzhen Hospital (HKU-SZH), Shenzhen 518053, China
| | - Danny Chan
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
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Wynsberghe JV, Vanakker OM. Significance of Premature Vertebral Mineralization in Zebrafish Models in Mechanistic and Pharmaceutical Research on Hereditary Multisystem Diseases. Biomolecules 2023; 13:1621. [PMID: 38002303 PMCID: PMC10669475 DOI: 10.3390/biom13111621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 10/25/2023] [Accepted: 10/27/2023] [Indexed: 11/26/2023] Open
Abstract
Zebrafish are increasingly becoming an important model organism for studying the pathophysiological mechanisms of human diseases and investigating how these mechanisms can be effectively targeted using compounds that may open avenues to novel treatments for patients. The zebrafish skeleton has been particularly instrumental in modeling bone diseases as-contrary to other model organisms-the lower load on the skeleton of an aquatic animal enables mutants to survive to early adulthood. In this respect, the axial skeletons of zebrafish have been a good read-out for congenital spinal deformities such as scoliosis and degenerative disorders such as osteoporosis and osteoarthritis, in which aberrant mineralization in humans is reflected in the respective zebrafish models. Interestingly, there have been several reports of hereditary multisystemic diseases that do not affect the vertebral column in human patients, while the corresponding zebrafish models systematically show anomalies in mineralization and morphology of the spine as their leading or, in some cases, only phenotype. In this review, we describe such examples, highlighting the underlying mechanisms, the already-used or potential power of these models to help us understand and amend the mineralization process, and the outstanding questions on how and why this specific axial type of aberrant mineralization occurs in these disease models.
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Affiliation(s)
- Judith Van Wynsberghe
- Center for Medical Genetics, Ghent University Hospital, 9000 Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, 9000 Ghent, Belgium
- Ectopic Mineralization Research Group, 9000 Ghent, Belgium
| | - Olivier M Vanakker
- Center for Medical Genetics, Ghent University Hospital, 9000 Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, 9000 Ghent, Belgium
- Ectopic Mineralization Research Group, 9000 Ghent, Belgium
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Kauffenstein G, Chappard D, Leftheriotis G, Martin L. ABCC6 deficiency and bone loss: A double benefit of etidronate for patient presenting with pseudoxanthoma elasticum? Exp Dermatol 2022; 31:1635-1637. [PMID: 35771123 PMCID: PMC9796561 DOI: 10.1111/exd.14636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 06/12/2022] [Accepted: 06/26/2022] [Indexed: 01/01/2023]
Affiliation(s)
| | | | | | - Ludovic Martin
- PXE National Reference Center (MAGEC Nord)Angers University HospitalAngersFrance,MITOVASC – UMR CNRS 6015 INSERM 1083Angers UniversityAngersFrance
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Ottone OK, Kim C, Collins JA, Risbud MV. The cGAS-STING Pathway Affects Vertebral Bone but Does Not Promote Intervertebral Disc Cell Senescence or Degeneration. Front Immunol 2022; 13:882407. [PMID: 35769461 PMCID: PMC9235924 DOI: 10.3389/fimmu.2022.882407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 05/06/2022] [Indexed: 11/25/2022] Open
Abstract
The DNA-sensing cGAS-STING pathway promotes the senescence-associated secretory phenotype (SASP) and mediates type-I interferon inflammatory responses to foreign viral and bacterial DNA as well as self-DNA. Studies of the intervertebral disc in humans and mice demonstrate associations between aging, increased cell senescence, and disc degeneration. Herein we assessed the role of STING in SASP promotion in STING gain- (N153S) and loss-of-function mouse models. N153S mice evidenced elevated circulating levels of proinflammatory markers including IL-1β, IL-6, and TNF-α, showed elevated monocyte and macrophage abundance in the vertebral marrow, and exhibited a mild trabecular and cortical bone phenotype in caudal vertebrae. Interestingly, despite systemic inflammation, the structural integrity of the disc and knee articular joint remained intact, and cells did not show a loss of their phenotype or elevated SASP. Transcriptomic analysis of N153S tissues demonstrated an upregulated immune response by disc cells, which did not closely resemble inflammatory changes in human tissues. Interestingly, STING-/- mice also showed a mild vertebral bone phenotype, but the absence of STING did not reduce the abundance of SASP markers or improve the age-associated disc phenotype. Overall, the analyses of N153S and STING-/- mice suggest that the cGAS-STING pathway is not a major contributor to SASP induction and consequent disc aging and degeneration but may play a minor role in the maintenance of trabecular bone in the vertebrae. This work contributes to a growing body of work demonstrating that systemic inflammation is not a key driver of disc degeneration.
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Affiliation(s)
- Olivia K. Ottone
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, United States
- Graduate Program in Cell Biology and Regenerative Medicine, Jefferson College of Life Sciences, Thomas Jefferson University, Philadelphia, PA, United States
| | - Cheeho Kim
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, United States
| | - John A. Collins
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, United States
| | - Makarand V. Risbud
- Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, United States
- Graduate Program in Cell Biology and Regenerative Medicine, Jefferson College of Life Sciences, Thomas Jefferson University, Philadelphia, PA, United States
- *Correspondence: Makarand V. Risbud,
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