1
|
Das BK, Minocha T, Kunika MD, Kannan A, Gao L, Mohan S, Xing W, Varughese KI, Zhao H. Molecular and functional mapping of Plekhm1-Rab7 interaction in osteoclasts. JBMR Plus 2024; 8:ziae034. [PMID: 38586475 PMCID: PMC10994564 DOI: 10.1093/jbmrpl/ziae034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 02/21/2024] [Accepted: 03/08/2024] [Indexed: 04/09/2024] Open
Abstract
Mutations in PLEKHM1 cause osteopetrosis in humans and rats. The germline and osteoclast conditional deletions of Plekhm1 gene in mice lead to defective osteoclast bone resorption and increased trabecular bone mass without overt abnormalities in other organs. As an adaptor protein, pleckstrin homology and RUN domain containing M1 (PLEKHM1) interacts with the key lysosome regulator small GTPase RAB7 via its C-terminal RUBICON homologous (RH) domain. In this study, we have conducted a structural-functional study of the PLEKHM1 RH domain and RAB7 interaction in osteoclasts in vitro. The single mutations of the key residues in the Plekhm1 RH predicted from the crystal structure of the RUBICON RH domain and RAB7 interface failed to disrupt the Plekhm1-Rab7 binding, lysosome trafficking, and bone resorption. The compound alanine mutations at Y949-R954 and L1011-I1018 regions decreased Plekhm1 protein stability and Rab7-binding, respectively, thereby attenuated lysosome trafficking and bone resorption in osteoclasts. In contrast, the compound alanine mutations at R1060-Q1068 region were dispensable for Rab7-binding and Plekhm1 function in osteoclasts. These results indicate that the regions spanning Y949-R954 and L1011-I1018 of Plekhm1 RH domain are functionally important for Plekhm1 in osteoclasts and offer the therapeutic targets for blocking bone resorption in treatment of osteoporosis and other metabolic bone diseases.
Collapse
Affiliation(s)
- Bhaba K Das
- Southern California Institute for Research and Education, VA Long Beach Healthcare System, Long Beach, CA 90822, United States
| | - Tarun Minocha
- Southern California Institute for Research and Education, VA Long Beach Healthcare System, Long Beach, CA 90822, United States
| | - Mikaela D Kunika
- Southern California Institute for Research and Education, VA Long Beach Healthcare System, Long Beach, CA 90822, United States
| | - Aarthi Kannan
- Southern California Institute for Research and Education, VA Long Beach Healthcare System, Long Beach, CA 90822, United States
- Department of Dermatology, University of California-Irvine, Irvine, CA 92697, United States
| | - Ling Gao
- Southern California Institute for Research and Education, VA Long Beach Healthcare System, Long Beach, CA 90822, United States
- Department of Dermatology, University of California-Irvine, Irvine, CA 92697, United States
| | - Subburaman Mohan
- Musculoskeletal Disease Center, VA Loma Linda Healthcare System, Loma Linda, CA 92357, United States
| | - Weirong Xing
- Musculoskeletal Disease Center, VA Loma Linda Healthcare System, Loma Linda, CA 92357, United States
| | - Kottayil I Varughese
- Department of Physiology and Cell Biology, University of Arkansas for Medical Sciences, Little Rock 72205, AR, United States
| | - Haibo Zhao
- Southern California Institute for Research and Education, VA Long Beach Healthcare System, Long Beach, CA 90822, United States
| |
Collapse
|
2
|
Lee JW, Lee IH, Watanabe H, Liu Y, Sawada K, Maekawa M, Uehara S, Kobayashi Y, Imai Y, Kong SW, Iimura T. Centrosome clustering control in osteoclasts through CCR5-mediated signaling. Sci Rep 2023; 13:20813. [PMID: 38012303 PMCID: PMC10681980 DOI: 10.1038/s41598-023-48140-2] [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: 07/11/2023] [Accepted: 11/22/2023] [Indexed: 11/29/2023] Open
Abstract
Osteoclasts uniquely resorb calcified bone matrices. To exert their function, mature osteoclasts maintain the cellular polarity and directional vesicle trafficking to and from the resorbing bone surface. However, the regulatory mechanisms and pathophysiological relevance of these processes remain largely unexplored. Bone histomorphometric analyses in Ccr5-deficient mice showed abnormalities in the morphology and functional phenotype of their osteoclasts, compared to wild type mice. We observed disorganized clustering of nuclei, as well as centrosomes that organize the microtubule network, which was concomitant with impaired cathepsin K secretion in cultured Ccr5-deficient osteoclasts. Intriguingly, forced expression of constitutively active Rho or Rac restored these cytoskeletal phenotypes with recovery of cathepsin K secretion. Furthermore, a gene-disease enrichment analysis identified that PLEKHM1, a responsible gene for osteopetrosis, which regulates lysosomal trafficking in osteoclasts, was regulated by CCR5. These experimental results highlighted that CCR5-mediated signaling served as an intracellular organizer for centrosome clustering in osteoclasts, which was involved in the pathophysiology of bone metabolism.
Collapse
Affiliation(s)
- Ji-Won Lee
- Department of Pharmacology, Faculty and Graduate School of Dental Medicine, Hokkaido University, Sapporo, 060-8586, Japan.
- Department of Oral Molecular Microbiology, Faculty and Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan.
| | - In-Hee Lee
- Computational Health and Informatics Program, Boston Children's Hospital, Boston, MA, USA
| | - Haruhisa Watanabe
- Department of Pharmacology, Faculty and Graduate School of Dental Medicine, Hokkaido University, Sapporo, 060-8586, Japan
| | - Yunqing Liu
- Department of Pharmacology, Faculty and Graduate School of Dental Medicine, Hokkaido University, Sapporo, 060-8586, Japan
| | - Kazuaki Sawada
- NIKON SOLUTIONS CO., LTD., Oi Plant 6-3, Nishioi 1-Chome, Shinagawa-ku, Tokyo, Japan
| | - Masashi Maekawa
- Division of Physiological Chemistry and Metabolism, Graduate School of Pharmaceutical Sciences, Keio University, Tokyo, Japan
| | - Shunsuke Uehara
- Department of Biochemistry, Matsumoto Dental University, Nagano, Japan
| | - Yasuhiro Kobayashi
- Division of Hard Tissue Research, Institute for Oral Science, Matsumoto Dental University, Nagano, Japan
| | - Yuuki Imai
- Division of Integrative Pathophysiology, Proteo-Science Center, Ehime University, Ehime, Japan
- Department of Pathophysiology, Ehime University Graduate School of Medicine, Ehime, Japan
| | - Sek Won Kong
- Computational Health and Informatics Program, Boston Children's Hospital, Boston, MA, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Tadahiro Iimura
- Department of Pharmacology, Faculty and Graduate School of Dental Medicine, Hokkaido University, Sapporo, 060-8586, Japan.
| |
Collapse
|
3
|
Hao X, Shao Z, Zhang N, Jiang M, Cao X, Li S, Guan Y, Wang C. Integrative genome-wide analyses identify novel loci associated with kidney stones and provide insights into its genetic architecture. Nat Commun 2023; 14:7498. [PMID: 37980427 PMCID: PMC10657403 DOI: 10.1038/s41467-023-43400-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 11/08/2023] [Indexed: 11/20/2023] Open
Abstract
Kidney stone disease (KSD) is a complex disorder with high heritability and prevalence. We performed a large genome-wide association study (GWAS) meta-analysis for KSD to date, including 720,199 individuals with 17,969 cases in European population. We identified 44 susceptibility loci, including 28 novel loci. Cell type-specific analysis pinpointed the proximal tubule as the most relevant cells where susceptibility variants might act through a tissue-specific fashion. By integrating kidney-specific omics data, we prioritized 223 genes which strengthened the importance of ion homeostasis, including calcium and magnesium in stone formation, and suggested potential target drugs for the treatment. The genitourinary and digestive diseases showed stronger genetic correlations with KSD. In this study, we generate an atlas of candidate genes, tissue and cell types involved in the formation of KSD. In addition, we provide potential drug targets for KSD treatment and insights into shared regulation with other diseases.
Collapse
Affiliation(s)
- Xingjie Hao
- Department of Epidemiology and Biostatistics, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, China.
| | - Zhonghe Shao
- Department of Epidemiology and Biostatistics, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, China
| | - Ning Zhang
- Department of Breast and Thyroid Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430022, China
| | - Minghui Jiang
- Department of Epidemiology and Biostatistics, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, China
| | - Xi Cao
- Department of Epidemiology and Biostatistics, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, China
| | - Si Li
- Department of Epidemiology and Biostatistics, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, China
| | - Yunlong Guan
- Department of Epidemiology and Biostatistics, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, China
| | - Chaolong Wang
- Department of Epidemiology and Biostatistics, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, China.
| |
Collapse
|
4
|
Bergen DJM, Maurizi A, Formosa MM, McDonald GLK, El-Gazzar A, Hassan N, Brandi ML, Riancho JA, Rivadeneira F, Ntzani E, Duncan EL, Gregson CL, Kiel DP, Zillikens MC, Sangiorgi L, Högler W, Duran I, Mäkitie O, Van Hul W, Hendrickx G. High Bone Mass Disorders: New Insights From Connecting the Clinic and the Bench. J Bone Miner Res 2023; 38:229-247. [PMID: 36161343 PMCID: PMC10092806 DOI: 10.1002/jbmr.4715] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 09/05/2022] [Accepted: 09/22/2022] [Indexed: 02/04/2023]
Abstract
Monogenic high bone mass (HBM) disorders are characterized by an increased amount of bone in general, or at specific sites in the skeleton. Here, we describe 59 HBM disorders with 50 known disease-causing genes from the literature, and we provide an overview of the signaling pathways and mechanisms involved in the pathogenesis of these disorders. Based on this, we classify the known HBM genes into HBM (sub)groups according to uniform Gene Ontology (GO) terminology. This classification system may aid in hypothesis generation, for both wet lab experimental design and clinical genetic screening strategies. We discuss how functional genomics can shape discovery of novel HBM genes and/or mechanisms in the future, through implementation of omics assessments in existing and future model systems. Finally, we address strategies to improve gene identification in unsolved HBM cases and highlight the importance for cross-laboratory collaborations encompassing multidisciplinary efforts to transfer knowledge generated at the bench to the clinic. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
Collapse
Affiliation(s)
- Dylan J M Bergen
- School of Physiology, Pharmacology, and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, UK.,Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical School, Faculty of Health Sciences, University of Bristol, Bristol, UK
| | - Antonio Maurizi
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Melissa M Formosa
- Department of Applied Biomedical Science, Faculty of Health Sciences, University of Malta, Msida, Malta.,Center for Molecular Medicine and Biobanking, University of Malta, Msida, Malta
| | - Georgina L K McDonald
- School of Physiology, Pharmacology, and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, UK
| | - Ahmed El-Gazzar
- Department of Paediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria
| | - Neelam Hassan
- Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical School, Faculty of Health Sciences, University of Bristol, Bristol, UK
| | | | - José A Riancho
- Department of Internal Medicine, Hospital U M Valdecilla, University of Cantabria, IDIVAL, Santander, Spain
| | - Fernando Rivadeneira
- Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Evangelia Ntzani
- Department of Hygiene and Epidemiology, Medical School, University of Ioannina, Ioannina, Greece.,Center for Evidence Synthesis in Health, Policy and Practice, Center for Research Synthesis in Health, School of Public Health, Brown University, Providence, RI, USA.,Institute of Biosciences, University Research Center of loannina, University of Ioannina, Ioannina, Greece
| | - Emma L Duncan
- Department of Twin Research & Genetic Epidemiology, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK.,Department of Endocrinology, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Celia L Gregson
- Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical School, Faculty of Health Sciences, University of Bristol, Bristol, UK
| | - Douglas P Kiel
- Marcus Institute for Aging Research, Hebrew SeniorLife and Department of Medicine Beth Israel Deaconess Medical Center and Harvard Medical School, Broad Institute of MIT & Harvard, Cambridge, MA, USA
| | - M Carola Zillikens
- Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Luca Sangiorgi
- Department of Rare Skeletal Diseases, IRCCS Rizzoli Orthopaedic Institute, Bologna, Italy
| | - Wolfgang Högler
- Department of Paediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria.,Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK
| | | | - Outi Mäkitie
- Children's Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.,Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Folkhälsan Research Centre, Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Wim Van Hul
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium
| | | |
Collapse
|
5
|
Huybrechts Y, Van Hul W. Osteopetrosis associated with PLEKHM1 and SNX10 genes, both involved in osteoclast vesicular trafficking. Bone 2022; 164:116520. [PMID: 35981699 DOI: 10.1016/j.bone.2022.116520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 08/09/2022] [Accepted: 08/11/2022] [Indexed: 11/24/2022]
Abstract
The clinical and radiological variability seen in different forms of osteopetrosis, all due to impaired osteoclastic bone resorption, reflect many causal genes. Both defective differentiation of osteoclasts from hematopoietic stem cells as well as disturbed functioning of osteoclasts can be the underlying pathogenic mechanism. Pathogenic variants in PLEKHM1 and SNX10 can be classified among the latter as they impair vesicular transport within the osteoclast and therefore result in the absence of a ruffled border. Some of the typical radiological hallmarks of osteopetrosis can be seen, and most cases present as a relatively mild form segregating in an autosomal recessive mode of inheritance.
Collapse
Affiliation(s)
- Yentl Huybrechts
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium
| | - Wim Van Hul
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
| |
Collapse
|
6
|
Delaisse JM, Andersen TL, Kristensen HB, Jensen PR, Andreasen CM, Søe K. Re-thinking the bone remodeling cycle mechanism and the origin of bone loss. Bone 2020; 141:115628. [PMID: 32919109 DOI: 10.1016/j.bone.2020.115628] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 09/04/2020] [Accepted: 09/04/2020] [Indexed: 02/06/2023]
Abstract
Proper bone remodeling necessarily requires that osteoblasts reconstruct the bone that osteoclasts have resorbed. However, the cellular events connecting resorption to reconstruction have remained poorly known. The consequence is a fragmentary understanding of the remodeling cycle where only the resorption and formation steps are taken into account. New tools have recently made possible to elucidate how resorption shifts to formation, thereby allowing to comprehend the remodeling cycle as a whole. This new knowledge is reviewed herein. It shows how teams of osteoclasts and osteoblast lineage cells are progressively established and how they are subjected therein to reciprocal interactions. Contrary to the common view, osteoclasts and osteoprogenitors are intermingled on the eroded surfaces. The analysis of the resorption and cell population dynamics shows that osteoprogenitor cell expansion and resorption proceed as an integrated mechanism; that a threshold cell density of osteoprogenitors on the eroded surface is mandatory for onset of bone formation; that the cell initiating osteoprogenitor cell expansion is the osteoclast; and that the osteoclast therefore triggers putative osteoprogenitor reservoirs positioned at proximity of the eroded bone surface (bone lining cells, canopy cells, pericytes). The interplay between magnitude of resorption and rate of cell expansion governs how soon bone reconstruction is initiated and may determine uncoupling and permanent bone loss if a threshold cell density is not reached. The clinical perspectives opened by these findings are discussed.
Collapse
Affiliation(s)
- Jean-Marie Delaisse
- Clinical Cell Biology, Department of Pathology, Odense University Hospital, Department of Clinical Research, Department of Molecular Medicine, University of Southern Denmark, Odense, Denmark.
| | - Thomas Levin Andersen
- Clinical Cell Biology, Department of Pathology, Odense University Hospital, Department of Clinical Research, Department of Molecular Medicine, University of Southern Denmark, Odense, Denmark; Department of Forensic Medicine, Aarhus University, Aarhus, Denmark.
| | - Helene Bjoerg Kristensen
- Clinical Cell Biology, Lillebælt Hospital, Department of Regional Health Research, University of Southern Denmark, Vejle, Denmark.
| | - Pia Rosgaard Jensen
- Clinical Cell Biology, Lillebælt Hospital, Department of Regional Health Research, University of Southern Denmark, Vejle, Denmark.
| | - Christina Møller Andreasen
- Clinical Cell Biology, Department of Pathology, Odense University Hospital, Department of Clinical Research, Department of Molecular Medicine, University of Southern Denmark, Odense, Denmark.
| | - Kent Søe
- Clinical Cell Biology, Department of Pathology, Odense University Hospital, Department of Clinical Research, Department of Molecular Medicine, University of Southern Denmark, Odense, Denmark.
| |
Collapse
|
7
|
Abstract
The phenotypic trait of high bone mass (HBM) is an excellent example of the nexus between common and rare disease genetics. HBM may arise from carriage of many 'high bone mineral density [BMD]'-associated alleles, and certainly the genetic architecture of individuals with HBM is enriched with high BMD variants identified through genome-wide association studies of BMD. HBM may also arise as a monogenic skeletal disorder, due to abnormalities in bone formation, bone resorption, and/or bone turnover. Individuals with monogenic disorders of HBM usually, though not invariably, have other skeletal abnormalities (such as mandible enlargement) and thus are best regarded as having a skeletal dysplasia rather than just isolated high BMD. A binary etiological division of HBM into polygenic vs. monogenic, however, would be excessively simplistic: the phenotype of individuals carrying rare variants of large effect can still be modified by their common variant polygenic background, and by the environment. HBM disorders-whether predominantly polygenic or monogenic in origin-are not only interesting clinically and genetically: they provide insights into bone processes that can be exploited therapeutically, with benefits both for individuals with these rare bone disorders and importantly for the many people affected by the commonest bone disease worldwide-i.e., osteoporosis. In this review we detail the genetic architecture of HBM; we provide a conceptual framework for considering HBM in the clinical context; and we discuss monogenic and polygenic causes of HBM with particular emphasis on anabolic causes of HBM.
Collapse
Affiliation(s)
- Celia L. Gregson
- Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Emma L. Duncan
- Department of Twin Research & Genetic Epidemiology, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King’s College London, London, United Kingdom
| |
Collapse
|
8
|
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: 39] [Impact Index Per Article: 9.8] [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.
Collapse
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.)
| |
Collapse
|
9
|
Tamura T, Yoshioka Y, Sakamoto S, Ichikawa T, Ochiya T. Extracellular Vesicles in Bone Metastasis: Key Players in the Tumor Microenvironment and Promising Therapeutic Targets. Int J Mol Sci 2020; 21:E6680. [PMID: 32932657 PMCID: PMC7555648 DOI: 10.3390/ijms21186680] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 09/10/2020] [Accepted: 09/10/2020] [Indexed: 12/11/2022] Open
Abstract
Extracellular vesicles (EVs) are lipid membranous vesicles that are released from every type of cell. It has become clear that EVs are involved in a variety of biological phenomena, including cancer progression, and play critical roles in intracellular communication through the horizontal transfer of cellular cargoes such as proteins, DNA fragments, RNAs including mRNA and non-coding RNAs (microRNA, piRNA, and long non-coding RNA) and lipids. The most common cause of death associated with cancer is metastasis. Recent investigations have revealed that EVs are deeply associated with metastasis. Bone is a preferred site of metastasis, and bone metastasis is generally incurable and dramatically affects patient quality of life. Bone metastasis can cause devastating complications, including hypercalcemia, pathological fractures, spinal compression, and bone pain, which result in a poor prognosis. Although the mechanisms underlying bone metastasis have yet to be fully elucidated, increasing evidence suggests that EVs in the bone microenvironment significantly contribute to cancer progression and cancer bone tropism. Emerging evidence on EV functions in bone metastasis will facilitate the discovery of novel treatments. In this review, we will discuss the remarkable effects of EVs, especially on the tumor microenvironment in bone.
Collapse
Affiliation(s)
- Takaaki Tamura
- Department of Molecular and Cellular Medicine, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan; (T.T.); (Y.Y.)
- Department of Urology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan; (S.S.); (T.I.)
| | - Yusuke Yoshioka
- Department of Molecular and Cellular Medicine, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan; (T.T.); (Y.Y.)
| | - Shinichi Sakamoto
- Department of Urology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan; (S.S.); (T.I.)
| | - Tomohiko Ichikawa
- Department of Urology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan; (S.S.); (T.I.)
| | - Takahiro Ochiya
- Department of Molecular and Cellular Medicine, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan; (T.T.); (Y.Y.)
| |
Collapse
|
10
|
Ali A, Bin Arif T, Khan S, Bakhtawar Fatima F, Abbasi RS. A Rare Case of Malignant Infantile Osteopetrosis Presenting as Frontal Lobe Hemorrhage. Cureus 2020; 12:e9234. [PMID: 32821582 PMCID: PMC7430660 DOI: 10.7759/cureus.9234] [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] [Indexed: 12/02/2022] Open
Abstract
Osteopetrosis comprises a group of rare inherited disorders of the bones characterized by a common radiographic finding of increased bone thickness. The disorders vary genetically as well as clinically, and range in severity from mild manifestations to fatal complications based on the type of the disorder. Malignant infantile osteopetrosis (MIOP) is a less common, more severe form of the disease with most affected individuals surviving up to only the first few years of life if left untreated. We present a previously diagnosed case of the malignant infantile type who was brought to our attention for convulsions. Antiepileptic medications were started along with supportive therapy. CT scan revealed a large frontal lobe hemorrhage, which was suspected as a possible cause of the seizures, other than the progressively worsening hypocalcemia. Laboratory investigations also revealed pancytopenia and blood cultures positive for staphylococci, which were treated accordingly. Genetic testing and hematopoietic stem cell transplantation could not be performed due to financial constraints and the rapidly deteriorating condition of the patient. Unfortunately, the baby expired two weeks from the day of admission. This case highlights a rare and grave clinical manifestation of MIOP and brings to attention the significance of bone marrow transplantation as the only curative therapy of the disease.
Collapse
Affiliation(s)
- Aiman Ali
- Internal Medicine, Dow University of Health Sciences, Karachi, PAK
| | - Taha Bin Arif
- Internal Medicine, Dow University of Health Sciences, Karachi, PAK
| | - Sulhera Khan
- Medical Education and Simulation, Dow University of Health Sciences, Karachi, PAK
| | | | - Rabia Sehar Abbasi
- General Surgery, Liaquat University of Medical and Health Sciences, Hyderabad, PAK
| |
Collapse
|
11
|
Membrane trafficking in osteoclasts and implications for osteoporosis. Biochem Soc Trans 2019; 47:639-650. [PMID: 30837319 PMCID: PMC6490703 DOI: 10.1042/bst20180445] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 02/03/2019] [Accepted: 02/05/2019] [Indexed: 12/20/2022]
Abstract
Osteoclasts are large multinucleated cells exquisitely adapted to resorb bone matrix. Like other eukaryotes, osteoclasts possess an elaborate ensemble of intracellular organelles through which solutes, proteins and other macromolecules are trafficked to their target destinations via membrane-bound intermediaries. During bone resorption, membrane trafficking must be tightly regulated to sustain the structural and functional polarity of the osteoclasts’ membrane domains. Of these, the ruffled border (RB) is most characteristic, functioning as the osteoclasts' secretory apparatus. This highly convoluted organelle is classically considered to be formed by the targeted fusion of acidic vesicles with the bone-facing plasma membrane. Emerging findings disclose new evidence that the RB is far more complex than previously envisaged, possessing discrete subdomains that are serviced by several intersecting endocytic, secretory, transcytotic and autophagic pathways. Bone-resorbing osteoclasts therefore serve as a unique model system for studying polarized membrane trafficking. Recent advances in high-resolution microscopy together with the convergence of genetic and cell biological studies in humans and in mice have helped illuminate the major membrane trafficking pathways in osteoclasts and unmask the core molecular machinery that governs these distinct vesicle transport routes. Among these, small Rab GTPases, their binding partners and members of the endocytic sorting nexin family have emerged as critical regulators. This mini review summarizes our current understanding of membrane trafficking in osteoclasts, the key molecular participants, and discusses how these transport machinery may be exploited for the development of new therapies for metabolic disorders of bone-like osteoporosis.
Collapse
|
12
|
Rossi M, Battafarano G, D'Agostini M, Del Fattore A. The Role of Extracellular Vesicles in Bone Metastasis. Int J Mol Sci 2018; 19:ijms19041136. [PMID: 29642618 PMCID: PMC5979436 DOI: 10.3390/ijms19041136] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/05/2018] [Accepted: 04/05/2018] [Indexed: 12/15/2022] Open
Abstract
Multiple types of cancer have the specific ability to home to the bone microenvironment and cause metastatic lesions. Despite being the focus of intense investigation, the molecular and cellular mechanisms that regulate the metastasis of disseminated tumor cells still remain largely unknown. Bone metastases severely impact quality of life since they are associated with pain, fractures, and bone marrow aplasia. In this review, we will summarize the recent discoveries on the role of extracellular vesicles (EV) in the regulation of bone remodeling activity and bone metastasis occurrence. Indeed, it was shown that extracellular vesicles, including exosomes and microvesicles, released from tumor cells can modify the bone microenvironment, allowing the formation of osteolytic, osteosclerotic, and mixed mestastases. In turn, bone-derived EV can stimulate the proliferation of tumor cells. The inhibition of EV-mediated crosstalk between cancer and bone cells could represent a new therapeutic target for bone metastasis.
Collapse
Affiliation(s)
- Michela Rossi
- Bone Physiopathology Group, Multifactorial Disease and Complex Phenotype Research Area, Bambino Gesù Children's Hospital, 00165 Rome, Italy.
| | - Giulia Battafarano
- Bone Physiopathology Group, Multifactorial Disease and Complex Phenotype Research Area, Bambino Gesù Children's Hospital, 00165 Rome, Italy.
| | - Matteo D'Agostini
- Clinical Laboratory, Bambino Gesù Children's Hospital, 00165 Rome, Italy.
| | - Andrea Del Fattore
- Bone Physiopathology Group, Multifactorial Disease and Complex Phenotype Research Area, Bambino Gesù Children's Hospital, 00165 Rome, Italy.
| |
Collapse
|
13
|
Abstract
PURPOSE OF REVIEW The term osteopetrosis refers to a group of rare skeletal diseases sharing the hallmark of a generalized increase in bone density owing to a defect in bone resorption. Osteopetrosis is clinically and genetically heterogeneous, and a precise molecular classification is relevant for prognosis and treatment. Here, we review recent data on the pathogenesis of this disorder. RECENT FINDINGS Novel mutations in known genes as well as defects in new genes have been recently reported, further expanding the spectrum of molecular defects leading to osteopetrosis. Exploitation of next-generation sequencing tools is ever spreading, facilitating differential diagnosis. Some complex phenotypes in which osteopetrosis is accompanied by additional clinical features have received a molecular classification, also involving new genes. Moreover, novel types of mutations have been recognized, which for their nature or genomic location are at high risk being neglected. Yet, the causative mutation is unknown in some patients, indicating that the genetics of osteopetrosis still deserves intense research efforts.
Collapse
Affiliation(s)
- Eleonora Palagano
- Humanitas Clinical and Research Institute, via Manzoni 113, 20089, Rozzano, MI, Italy
- Department of Medical Biotechnologies and Translational Medicine, University of Milan, Milan, Italy
| | - Ciro Menale
- Humanitas Clinical and Research Institute, via Manzoni 113, 20089, Rozzano, MI, Italy
- Milan Unit, CNR-IRGB, Milan, Italy
| | - Cristina Sobacchi
- Humanitas Clinical and Research Institute, via Manzoni 113, 20089, Rozzano, MI, Italy.
- Milan Unit, CNR-IRGB, Milan, Italy.
| | - Anna Villa
- Humanitas Clinical and Research Institute, via Manzoni 113, 20089, Rozzano, MI, Italy
- Milan Unit, CNR-IRGB, Milan, Italy
| |
Collapse
|
14
|
Zhang X, Wei Z, He J, Wang C, Zhang Z. Novel mutations of CLCN7 cause autosomal dominant osteopetrosis type II (ADOII) and intermediate autosomal recessive osteopetrosis (ARO) in seven Chinese families. Postgrad Med 2017; 129:934-942. [PMID: 28975865 DOI: 10.1080/00325481.2017.1386529] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Xiaoya Zhang
- Metabolic Bone Disease and Genetic Research Unit, Department of Osteoporosis and Bone Disease, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, China
| | - Zhanying Wei
- Metabolic Bone Disease and Genetic Research Unit, Department of Osteoporosis and Bone Disease, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, China
| | - Jinwei He
- Metabolic Bone Disease and Genetic Research Unit, Department of Osteoporosis and Bone Disease, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, China
| | - Chun Wang
- Metabolic Bone Disease and Genetic Research Unit, Department of Osteoporosis and Bone Disease, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, China
| | - Zhenlin Zhang
- Metabolic Bone Disease and Genetic Research Unit, Department of Osteoporosis and Bone Disease, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, China
| |
Collapse
|
15
|
Abstract
Macroautophagy/autophagy is a catabolic process that is widely found in nature. Over the past few decades, mounting evidence has indicated that noncoding RNAs, ranging from small noncoding RNAs to long noncoding RNAs (lncRNAs) and even circular RNAs (circRNAs), mediate the transcriptional and post-transcriptional regulation of autophagy-related genes by participating in autophagy regulatory networks. The differential expression of noncoding RNAs affects autophagy levels at different physiological and pathological stages, including embryonic proliferation and differentiation, cellular senescence, and even diseases such as cancer. We summarize the current knowledge regarding noncoding RNA dysregulation in autophagy and investigate the molecular regulatory mechanisms underlying noncoding RNA involvement in autophagy regulatory networks. Then, we integrate public resources to predict autophagy-related noncoding RNAs across species and discuss strategies for and the challenges of identifying autophagy-related noncoding RNAs. This article will deepen our understanding of the relationship between noncoding RNAs and autophagy, and provide new insights to specifically target noncoding RNAs in autophagy-associated therapeutic strategies.
Collapse
Affiliation(s)
- Jian Zhang
- Department of Breast Surgery, Harbin Medical University Cancer Hospital, Harbin, China
| | - Peiyuan Wang
- Department of Breast Surgery, Harbin Medical University Cancer Hospital, Harbin, China
| | - Lin Wan
- Department of Breast Surgery, Harbin Medical University Cancer Hospital, Harbin, China
| | - Shouping Xu
- Department of Breast Surgery, Harbin Medical University Cancer Hospital, Harbin, China,CONTACT Da Pang ; Shouping Xu Department of Breast Surgery, Harbin Medical University Cancer Hospital, Harbin, No. 150 Haping Road, Harbin, China 150040
| | - Da Pang
- Department of Breast Surgery, Harbin Medical University Cancer Hospital, Harbin, China,Heilongjiang Academy of Medical Sciences, Harbin, China,CONTACT Da Pang ; Shouping Xu Department of Breast Surgery, Harbin Medical University Cancer Hospital, Harbin, No. 150 Haping Road, Harbin, China 150040
| |
Collapse
|
16
|
Bo T, Yan F, Guo J, Lin X, Zhang H, Guan Q, Wang H, Fang L, Gao L, Zhao J, Xu C. Characterization of a Relatively Malignant Form of Osteopetrosis Caused by a Novel Mutation in the PLEKHM1 Gene. J Bone Miner Res 2016; 31:1979-1987. [PMID: 27291868 DOI: 10.1002/jbmr.2885] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Revised: 05/25/2016] [Accepted: 06/10/2016] [Indexed: 12/11/2022]
Abstract
Osteopetrosis (OMIM: 611497), literally "stone bone," is a group of inherited bone disorders characterized by increased skeletal mass due to defective osteoclast function. A patient who reported a history of frequent fractures, weakness and fatigue was admitted to our hospital in 2011. The patient presented with the typical features of osteopetrosis: fractures after minor trauma, early tooth loss, anemia, hepatosplenomegaly, and a generalized increase in bone mineral density (BMD). Aside from his father's complaint of excessive tooth loss, his mother, two sisters, son, and daughter were healthy. Blood samples of the family members were drawn for genetic analyses. The entire coding region and adjacent splice sites of the pleckstrin homology domain-containing family M (with RUN domain) member 1 (PLEKHM1) gene were sequenced. One mutation, a heterozygous deletion mutation in exon 11 (c.3051_3052delCA), was identified in the patient but not in his relatives. The mutation leads to a translation product with a highly impaired Rubicon homology domain. Co-immunoprecipitation and immunofluorescence analyses using HEK293 cells showed that overexpression of a PLEKHM1 CA-deletion mutant resulted in a dramatic decrease in the interaction between PLEKHM1 and the small GTPase Rab7 compared to wild-type PLEKHM1. The normal processes of endocytosis and autophagy were disturbed in cells expressing the mutant (transfected HEK293 and U937 cells), as indicated by epidermal growth factor receptor (EGFR) degradation and an altered LC3-I/II ratio, respectively, which may lead to a defect in osteoclast function. A four-year follow-up study of the patient showed that the PLEKHM1-dependent osteopetrosis was relatively malignant, with significant symptoms of pancytopenia and hepatosplenomegaly. © 2016 American Society for Bone and Mineral Research.
Collapse
Affiliation(s)
- Tao Bo
- Scientific Center, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong, China.,Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan, Shandong, China
| | - Fang Yan
- Department of Pain Management, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong, China
| | - Jun Guo
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan, Shandong, China.,Department of Endocrinology and Metabolism, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong, China
| | - Xiaoyan Lin
- Pathology Department, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong, China
| | - Haiqing Zhang
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan, Shandong, China.,Department of Endocrinology and Metabolism, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong, China
| | - Qingbo Guan
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan, Shandong, China.,Department of Endocrinology and Metabolism, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong, China
| | - Hai Wang
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan, Shandong, China.,Department of Endocrinology and Metabolism, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong, China
| | - Li Fang
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan, Shandong, China.,Department of Endocrinology and Metabolism, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong, China
| | - Ling Gao
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan, Shandong, China.,Department of Endocrinology and Metabolism, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong, China
| | - Jiajun Zhao
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan, Shandong, China.,Department of Endocrinology and Metabolism, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong, China
| | - Chao Xu
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan, Shandong, China.,Department of Endocrinology and Metabolism, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong, China
| |
Collapse
|
17
|
Fujiwara T, Ye S, Castro-Gomes T, Winchell CG, Andrews NW, Voth DE, Varughese KI, Mackintosh SG, Feng Y, Pavlos N, Nakamura T, Manolagas SC, Zhao H. PLEKHM1/DEF8/RAB7 complex regulates lysosome positioning and bone homeostasis. JCI Insight 2016; 1:e86330. [PMID: 27777970 DOI: 10.1172/jci.insight.86330] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Mutations of the Plekhm1 gene in humans and rats cause osteopetrosis, an inherited bone disease characterized by diminished bone resorption by osteoclasts. PLEKHM1 binds to RAB7 and is critical for lysosome trafficking. However, the molecular mechanisms by which PLEKHM1 regulates lysosomal pathways remain unknown. Here, we generated germline and conditional Plekhm1-deficient mice. These mice displayed no overt abnormalities in major organs, except for an increase in trabecular bone mass. Furthermore, loss of PLEKHM1 abrogated the peripheral distribution of lysosomes and bone resorption in osteoclasts. Mechanistically, we indicated that DEF8 interacts with PLEKHM1 and promotes its binding to RAB7, whereas the binding of FAM98A and NDEL1 with PLEKHM1 connects lysosomes to microtubules. Importantly, suppression of these proteins results in lysosome positioning and bone resorption defects similar to those of Plekhm1-null osteoclasts. Thus, PLHKEM1, DEF8, FAM98A, and NDEL1 constitute a molecular complex that regulates lysosome positioning and secretion through RAB7.
Collapse
Affiliation(s)
- Toshifumi Fujiwara
- Center for Osteoporosis and Metabolic Bone Diseases, Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Shiqiao Ye
- Center for Osteoporosis and Metabolic Bone Diseases, Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Thiago Castro-Gomes
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA
| | | | - Norma W Andrews
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA
| | | | | | - Samuel G Mackintosh
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Yunfeng Feng
- Department of Pathology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, USA
| | - Nathan Pavlos
- Center for Orthopedic Research, Dentistry and Health Sciences, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Takashi Nakamura
- Department of Biochemistry & Integrative Medical Biology, School of Medicine, Keio University, Tokyo, Japan
| | - Stavros C Manolagas
- Center for Osteoporosis and Metabolic Bone Diseases, Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Haibo Zhao
- Center for Osteoporosis and Metabolic Bone Diseases, Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.,Department of Physiology and Biophysics, and
| |
Collapse
|
18
|
Pang Q, Qi X, Jiang Y, Wang O, Li M, Xing X, Dong J, Xia W. Two novel CAII mutations causing carbonic anhydrase II deficiency syndrome in two unrelated Chinese families. Metab Brain Dis 2015; 30:989-97. [PMID: 25720518 DOI: 10.1007/s11011-015-9660-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 02/17/2015] [Indexed: 01/28/2023]
Abstract
The carbonic anhydrase II (CAII) deficiency syndrome is a rare autosomal recessive osteopetrosis with renal tubular acidosis (RTA) and cerebral calcifications (MIM259730). CAII deficiency syndrome is caused by mutations in the gene CAII, which encodes the enzyme carbonic anhydrase II. CAII mutations are rarely reported in the Asian population. Here, we described two unrelated CAII deficiency families of Chinese Han origin with clinical and genetic analysis. Altogether, 106 subjects, including 2 probands, 4 unaffected family members from two non-consanguineous Chinese families, and 100 healthy controls were recruited. All seven exons and the exon-intron boundaries of the CAII gene were amplified and directly sequenced. Reverse transcription PCR (RT-PCR) was used to study the effect of splice site mutation. All clinical and biochemical parameters of the probands were collected. Two novel mutations of CAII gene were identified by mutational analysis: A nonsense mutation in exon 4 (c.T381C p.Y127X) in both families; a splice mutation at the splice donor site of intron 3 (c.350+2T>C, IVS3+2T>C) in one family. The splice-site mutation causes exon 3 skipping in patient's mRNA resulting in an in-frame deletion and a novel premature stop codon. These mutations were predicted to result in a loss of function of CAII. This is the first report of CAII deficiency syndrome in Chinese population. Our findings extent the spectrum of CAII mutations observed in patients with CAII deficiency syndrome.
Collapse
Affiliation(s)
- Qianqian Pang
- Department of Endocrinology, Key Laboratory of Endocrinology, The Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, China
| | | | | | | | | | | | | | | |
Collapse
|
19
|
Witwicka H, Jia H, Kutikov A, Reyes-Gutierrez P, Li X, Odgren PR. TRAFD1 (FLN29) Interacts with Plekhm1 and Regulates Osteoclast Acidification and Resorption. PLoS One 2015; 10:e0127537. [PMID: 25992615 PMCID: PMC4438057 DOI: 10.1371/journal.pone.0127537] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 04/16/2015] [Indexed: 02/07/2023] Open
Abstract
Plekhm1 is a large, multi-modular, adapter protein implicated in osteoclast vesicle trafficking and bone resorption. In patients, inactivating mutations cause osteopetrosis, and gain-of-function mutations cause osteopenia. Investigations of potential Plekhm1 interaction partners by mass spectrometry identified TRAFD1 (FLN29), a protein previously shown to suppress toll-like receptor signaling in monocytes/macrophages, thereby dampening inflammatory responses to innate immunity. We mapped the binding domains to the TRAFD1 zinc finger (aa 37-60), and to the region of Plekhm1 between its second pleckstrin homology domain and its C1 domain (aa 784-986). RANKL slightly increased TRAFD1 levels, particularly in primary osteoclasts, and the co-localization of TRAFD1 with Plekhm1 also increased with RANKL treatment. Stable knockdown of TRAFD1 in RAW 264.7 cells inhibited resorption activity proportionally to the degree of knockdown, and inhibited acidification. The lack of acidification occurred despite the presence of osteoclast acidification factors including carbonic anhydrase II, a3-V-ATPase, and the ClC7 chloride channel. Secretion of TRAP and cathepsin K were also markedly inhibited in knockdown cells. Truncated Plekhm1 in ia/ia osteopetrotic rat cells prevented vesicle localization of Plekhm1 and TRAFD1. We conclude that TRAFD1, in association with Plekhm1/Rab7-positive late endosomes-early lysosomes, has a previously unknown role in vesicle trafficking, acidification, and resorption in osteoclasts.
Collapse
Affiliation(s)
- Hanna Witwicka
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts, 01655 United States of America
| | - Hong Jia
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts, 01655 United States of America
| | - Artem Kutikov
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts, 01655 United States of America
| | - Pablo Reyes-Gutierrez
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts, 01655 United States of America
| | - Xiangdong Li
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts, 01655 United States of America
| | - Paul R. Odgren
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts, 01655 United States of America
- * E-mail:
| |
Collapse
|
20
|
Coudert AE, de Vernejoul MC, Muraca M, Del Fattore A. Osteopetrosis and its relevance for the discovery of new functions associated with the skeleton. Int J Endocrinol 2015; 2015:372156. [PMID: 25873953 PMCID: PMC4385565 DOI: 10.1155/2015/372156] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 10/16/2014] [Accepted: 10/30/2014] [Indexed: 01/29/2023] Open
Abstract
Osteopetrosis is a rare genetic disorder characterized by an increase of bone mass due to defective osteoclast function. Patients typically displayed spontaneous fractures, anemia, and in the most severe forms hepatosplenomegaly and compression of cranial facial nerves leading to deafness and blindness. Osteopetrosis comprises a heterogeneous group of diseases as several forms are known with different models of inheritance and severity from asymptomatic to lethal. This review summarizes the genetic and clinical features of osteopetrosis, emphasizing how recent studies of this disease have contributed to understanding the central role of the skeleton in the whole body physiology. In particular, the interplay of bone with the stomach, insulin metabolism, male fertility, the immune system, bone marrow, and fat is described.
Collapse
Affiliation(s)
- Amélie E. Coudert
- Institut National de la Santé et de la Recherche Médicale U1138, Centre de Recherche des Cordeliers, Paris, France
| | | | - Maurizio Muraca
- Regenerative Medicine Unit, Bambino Gesù Children's Hospital, IRCCS, Piazza Sant'Onofrio 4, 00165 Rome, Italy
| | - Andrea Del Fattore
- Regenerative Medicine Unit, Bambino Gesù Children's Hospital, IRCCS, Piazza Sant'Onofrio 4, 00165 Rome, Italy
- *Andrea Del Fattore:
| |
Collapse
|
21
|
Itzstein C, Coxon FP, Rogers MJ. The regulation of osteoclast function and bone resorption by small GTPases. Small GTPases 2014; 2:117-130. [PMID: 21776413 DOI: 10.4161/sgtp.2.3.16453] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 04/22/2011] [Accepted: 05/10/2011] [Indexed: 01/11/2023] Open
Abstract
Osteoclasts are multinucleated cells that are responsible for resorption of bone, and increased activity of these cells is associated with several common bone diseases, including postmenopausal osteoporosis. Upon adhesion to bone, osteoclasts become polarized and reorganise their cytoskeleton and membrane to form unique domains including the sealing zone (SZ), which is a dense ring of F-actin-rich podosomes delimiting the ruffled border (RB), where protons and proteases are secreted to demineralise and degrade the bone matrix, respectively. These processes are dependent on the activity of small GTPases. Rho GTPases are well known to control the organization of F-actin and adhesion structures of different cell types, affecting subsequently their migration. In osteoclasts, RhoA, Rac, Cdc42, RhoU and also Arf6 regulate podosome assembly and their organization into the SZ. By contrast, the formation of the RB involves vesicular trafficking pathways that are regulated by the Rab family of GTPases, in particular lysosomal Rab7. Finally, osteoclast survival is dependent on the activity of Ras GTPases. The correct function of almost all these GTPases is absolutely dependent on post-translational prenylation, which enables them to localize to specific target membranes. Bisphosphonate drugs, which are widely used in the treatment of bone diseases such as osteoporosis, act by preventing the prenylation of small GTPases, resulting in the loss of the SZ and RB and therefore inhibition of osteoclast activity, as well as inducing osteoclast apoptosis. In this review we summarize current understanding of the role of specific prenylated small GTPases in osteoclast polarization, function and survival.
Collapse
Affiliation(s)
- Cecile Itzstein
- Musculoskeletal Research Programme; Institute of Medical Sciences; University of Aberdeen; Aberdeen, Scotland UK
| | | | | |
Collapse
|
22
|
Cappariello A, Maurizi A, Veeriah V, Teti A. Reprint of: The Great Beauty of the osteoclast. Arch Biochem Biophys 2014; 561:13-21. [DOI: 10.1016/j.abb.2014.08.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 06/02/2014] [Accepted: 06/05/2014] [Indexed: 12/17/2022]
|
23
|
Brommage R, Liu J, Hansen GM, Kirkpatrick LL, Potter DG, Sands AT, Zambrowicz B, Powell DR, Vogel P. High-throughput screening of mouse gene knockouts identifies established and novel skeletal phenotypes. Bone Res 2014; 2:14034. [PMID: 26273529 PMCID: PMC4472125 DOI: 10.1038/boneres.2014.34] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 07/29/2014] [Accepted: 07/31/2014] [Indexed: 12/13/2022] Open
Abstract
Screening gene function in vivo is a powerful approach to discover novel drug targets. We present high-throughput screening (HTS) data for 3 762 distinct global gene knockout (KO) mouse lines with viable adult homozygous mice generated using either gene-trap or homologous recombination technologies. Bone mass was determined from DEXA scans of male and female mice at 14 weeks of age and by microCT analyses of bones from male mice at 16 weeks of age. Wild-type (WT) cagemates/littermates were examined for each gene KO. Lethality was observed in an additional 850 KO lines. Since primary HTS are susceptible to false positive findings, additional cohorts of mice from KO lines with intriguing HTS bone data were examined. Aging, ovariectomy, histomorphometry and bone strength studies were performed and possible non-skeletal phenotypes were explored. Together, these screens identified multiple genes affecting bone mass: 23 previously reported genes (Calcr, Cebpb, Crtap, Dcstamp, Dkk1, Duoxa2, Enpp1, Fgf23, Kiss1/Kiss1r, Kl (Klotho), Lrp5, Mstn, Neo1, Npr2, Ostm1, Postn, Sfrp4, Slc30a5, Slc39a13, Sost, Sumf1, Src, Wnt10b), five novel genes extensively characterized (Cldn18, Fam20c, Lrrk1, Sgpl1, Wnt16), five novel genes with preliminary characterization (Agpat2, Rassf5, Slc10a7, Slc26a7, Slc30a10) and three novel undisclosed genes coding for potential osteoporosis drug targets.
Collapse
Affiliation(s)
| | - Jeff Liu
- Lexicon Pharmaceuticals , The Woodlands, TX, USA
| | | | | | | | | | | | | | - Peter Vogel
- Lexicon Pharmaceuticals , The Woodlands, TX, USA
| |
Collapse
|
24
|
Cappariello A, Maurizi A, Veeriah V, Teti A. The Great Beauty of the osteoclast. Arch Biochem Biophys 2014; 558:70-8. [DOI: 10.1016/j.abb.2014.06.017] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 06/02/2014] [Accepted: 06/05/2014] [Indexed: 12/12/2022]
|
25
|
Charles JF, Aliprantis AO. Osteoclasts: more than 'bone eaters'. Trends Mol Med 2014; 20:449-59. [PMID: 25008556 PMCID: PMC4119859 DOI: 10.1016/j.molmed.2014.06.001] [Citation(s) in RCA: 253] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 05/28/2014] [Accepted: 06/02/2014] [Indexed: 02/08/2023]
Abstract
As the only cells definitively shown to degrade bone, osteoclasts are key mediators of skeletal diseases including osteoporosis. Bone-forming osteoblasts, and hematopoietic and immune system cells, each influence osteoclast formation and function, but the reciprocal impact of osteoclasts on these cells is less well appreciated. We highlight here the functions that osteoclasts perform beyond bone resorption. First, we consider how osteoclast signals may contribute to bone formation by osteoblasts and to the pathology of bone lesions such as fibrous dysplasia and giant cell tumors. Second, we review the interaction of osteoclasts with the hematopoietic system, including the stem cell niche and adaptive immune cells. Connections between osteoclasts and other cells in the bone microenvironment are discussed within a clinically relevant framework.
Collapse
Affiliation(s)
- Julia F Charles
- Department of Medicine, Division of Rheumatology, Allergy, and Immunology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Antonios O Aliprantis
- Department of Medicine, Division of Rheumatology, Allergy, and Immunology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.
| |
Collapse
|
26
|
Caveolae-mediated endocytosis of the glucosaminoglycan-interacting adipokine tartrate resistant acid phosphatase 5a in adipocyte progenitor lineage cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:495-507. [PMID: 24316135 DOI: 10.1016/j.bbamcr.2013.11.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 11/22/2013] [Accepted: 11/25/2013] [Indexed: 11/23/2022]
Abstract
Adipogenesis depends on growth factors controlling proliferation/differentiation of mesenchymal stem cells (MSCs). Membrane binding and endocytosis of growth factors are often coupled to receptor activation and downstream signaling leading to specific cellular responses. The novel adipokine tartrate-resistant acid phosphatase (TRAP) 5a exhibits a growth factor-like effect on MSCs and pre-adipocytes and induces hyperplastic obesity in vivo. However its molecular interaction with pre-adipocytes remains unknown. Therefore, this study aimed to investigate membrane interaction of TRAP and its endocytosis routes in pre-adipocytes. Confocal and/or electron microscopy were used to detect TRAP in untreated or TRAP 5a/b treated pre-adipocytes under conditions that allow or inhibit endocytosis in combination with co-staining of endocytotic vesicles. TRAP interaction with heparin/heparan sulfate was verified by gel filtration. It could be shown that TRAP 5a, but not 5b, binds to the membrane of pre-adipocytes where it co-localizes with heparin-sulfate proteoglycan glypican-4. Also in vitro, TRAP 5a exhibited affinity for both heparin and heparan sulfate with heparin inhibiting its enzyme activity. Upon caveolae-mediated endocytosis of saturating levels of TRAP 5a, TRAP 5a co-localized intracellularly with glypican-4 and late endosomal marker Rab-7 positive vesicles. The protein was also located in multivesicular bodies (MVBs) but did not co-localize with lysosomal marker LAMP-1. TRAP 5a endocytosis was also detectable in pre-osteoblasts, but not fibroblasts, embryonic MSCs or mature adipocytes. These results indicate that TRAP 5a exhibits binding to cell surface, endocytosis and affinity to glucosaminoglycans (GAGs) in pre-adipocyte and pre-osteoblast lineage cells in a manner similar to other heparin-binding growth factors.
Collapse
|
27
|
Henriksen K, Karsdal MA, Martin TJ. Osteoclast-derived coupling factors in bone remodeling. Calcif Tissue Int 2014; 94:88-97. [PMID: 23700149 DOI: 10.1007/s00223-013-9741-7] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 04/28/2013] [Indexed: 12/15/2022]
Abstract
In the bone remodeling process that takes place throughout the skeleton at bone multicellular units, intercellular communication processes are crucial. The osteoblast lineage has long been known to program osteoclast formation and hence resorption, but the preservation of bone mass and integrity requires tight control of remodeling. This needs local controls that ensure availability of mesenchymal precursors and the provision of local signals that promote differentiation through the osteoblast lineage. Some signals can come from growth factors released from resorbed bone matrix, and there is increasing evidence that the osteoclast lineage itself produces factors that can either enhance or inhibit osteoblast differentiation and hence bone formation. A number of such factors have been identified from predominantly in vitro experiments. The coupling of bone formation to resorption is increasingly recognized as a complex, dynamic process that results from the input of many local factors of cell and matrix origin that can either promote or inhibit bone formation.
Collapse
Affiliation(s)
- Kim Henriksen
- Nordic Bioscience Biomarkers and Research, 2730, Herlev, Denmark
| | | | | |
Collapse
|
28
|
Mechanisms of osteoclast-dependent bone formation. BONEKEY REPORTS 2013; 2:449. [PMID: 24422142 DOI: 10.1038/bonekey.2013.183] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 10/08/2013] [Indexed: 01/14/2023]
Abstract
Should we believe that osteoclasts are only involved in bone resorption? What about their contribution to bone formation? In this article I will review evidence that bone formation can be regulated by osteoclasts. Why is this? Likely because in the physiologic condition of bone remodeling, bone resorption and formation are balanced, and there is no better way to control this equilibrium than through a concerted action between the two cell types. Although the influence of osteoblasts on osteoclastic bone resorption is well documented and consolidated over time, what osteoclasts do to regulate osteoblast activity is still matter of intense investigation. The original hypothesis that all is in the osteoblast-seeking factors stored in the bone matrix, released and activated during bone resorption, is now being challenged by several studies, suggesting that osteoclasts are also capable of producing 'clastokines' that regulate osteoblast performance. Indeed, several of them have been demonstrated to orchestrate osteoclast-osteoblast activities. However, we are probably still at the dawn of a new era, and future work will tell us whether any of these clastokines can be exploited to stimulate bone formation and rebalance bone remodeling in skeletal diseases.
Collapse
|
29
|
Ochotny N, Voronov I, Owen C, Aubin JE, Manolson MF. The R740S mutation in the V-ATPase a3 subunit results in osteoclast apoptosis and defective early-stage autophagy. J Cell Biochem 2013; 114:2823-33. [DOI: 10.1002/jcb.24630] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 07/22/2013] [Indexed: 11/06/2022]
Affiliation(s)
- Noelle Ochotny
- Faculty of Dentistry; Dental Research Institute; University of Toronto; Toronto; Ontario; Canada
| | - Irina Voronov
- Faculty of Dentistry; Dental Research Institute; University of Toronto; Toronto; Ontario; Canada
| | - Celeste Owen
- Centre for Modeling Human Disease; Samuel Lunenfeld Research Institute; Mt. Sinai Hospital; Toronto; Ontario; Canada
| | | | - Morris F. Manolson
- Faculty of Dentistry; Dental Research Institute; University of Toronto; Toronto; Ontario; Canada
| |
Collapse
|
30
|
Lacombe J, Karsenty G, Ferron M. Regulation of lysosome biogenesis and functions in osteoclasts. Cell Cycle 2013; 12:2744-52. [PMID: 23966172 DOI: 10.4161/cc.25825] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
In order to resorb the mineralized bone extracellular matrix, the osteoclast relies on the generation of a resorption lacuna characterized by the presence of specific proteases and a low pH. Hence, bone resorption by osteoclasts is highly dependent on lysosomes, the organelles specialized in intra- and extracellular material degradation. This is best illustrated by the fact that multiple forms of human osteopetrosis are caused by mutations in genes encoding for lysosomal proteins. Yet, until recently, the molecular mechanisms regulating lysosomal biogenesis and function in osteoclasts were poorly understood. Here we review the latest developments in the study of lysosomal biogenesis and function in osteoclasts with an emphasis on the transcriptional control of these processes.
Collapse
Affiliation(s)
- Julie Lacombe
- Institut de Recherches Cliniques de Montréal; Montréal, Québec, Canada
| | | | | |
Collapse
|
31
|
Gregson CL, Hardcastle SA, Cooper C, Tobias JH. Friend or foe: high bone mineral density on routine bone density scanning, a review of causes and management. Rheumatology (Oxford) 2013; 52:968-85. [PMID: 23445662 DOI: 10.1093/rheumatology/ket007] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
A finding of high BMD on routine DXA scanning is not infrequent and most commonly reflects degenerative disease. However, BMD increases may also arise secondary to a range of underlying disorders affecting the skeleton. Although low BMD increases fracture risk, the converse may not hold for high BMD, since elevated BMD may occur in conditions where fracture risk is increased, unaffected or reduced. Here we outline a classification for the causes of raised BMD, based on identification of focal or generalized BMD changes, and discuss an approach to guide appropriate investigation by clinicians after careful interpretation of DXA scan findings within the context of the clinical history. We will also review the mild skeletal dysplasia associated with the currently unexplained high bone mass phenotype and discuss recent advances in osteoporosis therapies arising from improved understanding of rare inherited high BMD disorders.
Collapse
Affiliation(s)
- Celia L Gregson
- Musculoskeletal Research Unit, School of Clinical Sciences, University of Bristol, Bristol, UK.
| | | | | | | |
Collapse
|
32
|
Bone cell communication factors and Semaphorins. BONEKEY REPORTS 2012; 1:183. [PMID: 24171101 DOI: 10.1038/bonekey.2012.183] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 08/26/2012] [Indexed: 01/06/2023]
Abstract
Bone tissue is continuously renewed throughout adult life by a process called 'remodeling', which involves a dynamic interplay among bone cells including osteoclasts, osteoblasts and osteocytes. For example, a tight coupling between bone resorption and formation is essential for the homeostasis of the skeletal system. Studies on the coupling mechanism in physiological and pathological settings have revealed that osteoclasts or osteoclastic bone resorption promote bone formation through the production of diverse coupling factors. The classical coupling factors are the molecules that promote bone formation after resorption, but there may be distinct mechanisms at work in various phases of bone remodeling. A recent study revealed that the Semaphorin 4D expressed by osteoclasts inhibits bone formation, which represents a mechanism by which coupling is dissociated. Furthermore, it has been demonstrated that osteoblastic expression of Semaphorin 3A exerts an osteoprotective effect by both suppressing bone resorption and increasing bone formation. Thus, recent advances have made it increasingly clear that bone remodeling is regulated by not only classical coupling factors, but also molecules that mediate cell-cell communication among bone cells. We propose that such factors be called bone cell communication factors, which control the delicate balance of the interaction of bone cells so as to maintain bone homeostasis.
Collapse
|
33
|
de Jong S, Chepelev I, Janson E, Strengman E, van den Berg LH, Veldink JH, Ophoff RA. Common inversion polymorphism at 17q21.31 affects expression of multiple genes in tissue-specific manner. BMC Genomics 2012; 13:458. [PMID: 22950410 PMCID: PMC3582489 DOI: 10.1186/1471-2164-13-458] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Accepted: 08/27/2012] [Indexed: 11/12/2022] Open
Abstract
Background Chromosome 17q21.31 contains a common inversion polymorphism of approximately 900 kb in populations with European ancestry. Two divergent MAPT haplotypes, H1 and H2 are described with distinct linkage disequilibrium patterns across the region reflecting the inversion status at this locus. The MAPT H1 haplotype has been associated with progressive supranuclear palsy, corticobasal degeneration, Parkinson’s disease and Alzheimer’s disease, while the H2 is linked to recurrent deletion events associated with the 17q21.31 microdeletion syndrome, a disease characterized by developmental delay and learning disability. Results In this study, we investigate the effect of the inversion on the expression of genes in the 17q21.31 region. We find the expression of several genes in and at the borders of the inversion to be affected; specific either to whole blood or different regions of the human brain. The H1 haplotype was found to be associated with an increased expression of LRRC37A4, PLEKH1M and MAPT. In contrast, a decreased expression of MGC57346, LRRC37A and CRHR1 was associated with H1. Conclusions Studies thus far have focused on the expression of MAPT in the inversion region. However, our results show that the inversion status affects expression of other genes in the 17q21.31 region as well. Given the link between the inversion status and different neurological diseases, these genes may also be involved in disease pathology, possibly in a tissue-specific manner.
Collapse
Affiliation(s)
- Simone de Jong
- Department of Medical Genetics, University Medical Center Utrecht, Utrecht3584 CG, The Netherlands
| | | | | | | | | | | | | |
Collapse
|
34
|
Henriksen K, Andreassen KV, Thudium CS, Gudmann KNS, Moscatelli I, Crüger-Hansen CE, Schulz AS, Dziegiel MH, Richter J, Karsdal MA, Neutzsky-Wulff AV. A specific subtype of osteoclasts secretes factors inducing nodule formation by osteoblasts. Bone 2012; 51:353-61. [PMID: 22722081 DOI: 10.1016/j.bone.2012.06.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 06/07/2012] [Accepted: 06/09/2012] [Indexed: 12/19/2022]
Abstract
Osteoclasts are known to be important for the coupling process between bone resorption and formation. The aim of this study was to address when osteoclasts are anabolically active. Human monocytes were differentiated into mature osteoclasts by treatment with M-CSF and RANKL. Conditioned medium was collected from macrophages, pre-osteoclasts, and mature functional or non-resorbing osteopetrotic osteoclasts on either bone, plastic, decalcified bone or dentine with or without diphyllin, E64 or GM6001. Osteoclasts numbers were measured by TRACP activity. Bone resorption was evaluated by CTX-I and calcium release. The osteoblastic cell line 2T3 was treated with 50% of CM or non-CM for 12days. Bone formation was assessed by Alizarin Red extraction. CM from mature osteoclasts induced bone formation, while CM from macrophages did not. Non-resorbing osteoclasts generated from osteopetrosis patients showed little resorption, but still an induction of bone formation by osteoblasts. Mimicking the reduction in bone resorption using the V-ATPase inhibitor Diphyllin, the cysteine proteinase inhibitor E64 and the MMP-inhibitor GM6001 showed that CM from diphyllin and E64 treated osteoclasts showed reduced ability to induce bone formation compared to CM from vehicle treated osteoclasts, while CM from GM6001 treated osteoclasts equaled vehicle CM. Osteoclasts on either dentine or decalcified bone showed strongly attenuated anabolic capacities. In conclusion, we present evidence that osteoclasts, both dependent and independent of their resorptive activity, secrete factors stimulating osteoblastic bone formation.
Collapse
Affiliation(s)
- Kim Henriksen
- Nordic Bioscience A/S, Bone Biology and Biomarkers, Herlev, Denmark.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Gradin P, Hollberg K, Cassady AI, Lång P, Andersson G. Transgenic overexpression of tartrate-resistant acid phosphatase is associated with induction of osteoblast gene expression and increased cortical bone mineral content and density. Cells Tissues Organs 2012; 196:68-81. [PMID: 22248481 DOI: 10.1159/000330806] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/12/2011] [Indexed: 11/19/2022] Open
Abstract
Bone remodeling is a central event in the maintenance of skeletal tissue, and involves cycles of resorption followed by the formation of bone tissue. The activity of osteoclasts and osteoblasts during these cycles is tightly regulated by systemic and local factors coupling the action of these cells. Tartrate-resistant acid phosphatase (TRAP) is predominantly expressed in bone by osteoclasts but has also been detected in osteoblasts and osteocytes. Moreover, TRAP can stimulate the differentiation of mesenchymal lineage cells, i.e. progenitors of osteoblasts and adipocytes. In order to further explore the effects of TRAP on bone turnover, the structural and molecular phenotypes of osteoclasts and osteoblasts were assessed in TRAP-overexpressing transgenic mice. Transgenic mice of both sexes display increased cortical bone mineral content and density, which cannot be accounted for by decreased bone resorption since osteoclast numbers and resorptive activity do not differ from wild-type mice. Examination of the osteoblast phenotype revealed that markers of bone formation, i.e. procollagen type I N-terminal propeptides, and osteoblast lineage markers as well as the TRAP 1B mRNA transcript are increased in TRAP-overexpressing mice. Expression of the osteoclast-selective TRAP 1C mRNA is not increased in TRAP transgenic mice. Elevated expression of TRAP mRNA and protein were detected in osteoblasts, osteocytes and in the bone matrix of TRAP transgenic mice, suggesting that TRAP overexpression in osteoblast lineage cells is associated with increased cortical bone mineral content and density. The data presented here support the hypothesis that TRAP overexpression in the osteoblastic cell lineage stimulates the differentiation and/or activation of these cells.
Collapse
Affiliation(s)
- Per Gradin
- Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | | | | | | | | |
Collapse
|
36
|
Abstract
Vertebrates evolved elaborating a structure made up of more than 200 bones and cartilages articulated with one another to form the skeleton, through which locomotion, organ protection, lodging of hematopoiesis, and mineral homeostasis are allowed. Skeletogenesis starts at the fetal stage, along with marrow hematopoiesis, and evolves postnatally through modeling and remodeling processes that permit skeletal mass buildup. Preservation of skeletal mass is then implemented by balanced remodeling, which ensures continuous renovation of the tissue to allow its mechanical, structural, and metabolic properties to remain unaltered until ageing or diseases disrupt this equilibrium. Skeletal homeostasis is fulfilled by specialized bone cells in association with systemic and local regulators. Herein I review landmark discoveries that shed light on the intricate mesh connecting bone cells among themselves and with other systems, thus representing the cellular basis of normal and abnormal bone development and homeostasis.
Collapse
Affiliation(s)
- Anna Teti
- Department of Experimental Medicine, University of L'Aquila, Via Vetoio-Coppito 2, 67100, L'Aquila, Italy.
| |
Collapse
|
37
|
Ye S, Fowler TW, Pavlos NJ, Ng PY, Liang K, Feng Y, Zheng M, Kurten R, Manolagas SC, Zhao H. LIS1 regulates osteoclast formation and function through its interactions with dynein/dynactin and Plekhm1. PLoS One 2011; 6:e27285. [PMID: 22073305 PMCID: PMC3207863 DOI: 10.1371/journal.pone.0027285] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Accepted: 10/13/2011] [Indexed: 11/19/2022] Open
Abstract
Microtubule organization and lysosomal secretion are both critical for the activation and function of osteoclasts, highly specialized polykaryons that are responsible for bone resorption and skeletal homeostasis. Here, we have identified a novel interaction between microtubule regulator LIS1 and Plekhm1, a lysosome-associated protein implicated in osteoclast secretion. Decreasing LIS1 expression by shRNA dramatically attenuated osteoclast formation and function, as shown by a decreased number of mature osteoclasts differentiated from bone marrow macrophages, diminished resorption pits formation, and reduced level of CTx-I, a bone resorption marker. The ablated osteoclast formation in LIS1-depleted macrophages was associated with a significant decrease in macrophage proliferation, osteoclast survival and differentiation, which were caused by reduced activation of ERK and AKT by M-CSF, prolonged RANKL-induced JNK activation and declined expression of NFAT-c1, a master transcription factor of osteoclast differentiation. Consistent with its critical role in microtubule organization and dynein function in other cell types, we found that LIS1 binds to and colocalizes with dynein in osteoclasts. Loss of LIS1 led to disorganized microtubules and aberrant dynein function. More importantly, the depletion of LIS1 in osteoclasts inhibited the secretion of Cathepsin K, a crucial lysosomal hydrolase for bone degradation, and reduced the motility of osteoclast precursors. These results indicate that LIS1 is a previously unrecognized regulator of osteoclast formation, microtubule organization, and lysosomal secretion by virtue of its ability to modulate dynein function and Plekhm1.
Collapse
Affiliation(s)
- Shiqiao Ye
- Center for Osteoporosis and Metabolic Bone Diseases, Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Arkansas for Medical Sciences and the Central Arkansas Veterans Healthcare System, Little Rock, Arkansas, United States of America
| | | | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Cenni E, Scioscia L, Baldini N. Orthopaedic research in italy: state of the art. Int J Immunopathol Pharmacol 2011; 24:157-78. [PMID: 21669157 DOI: 10.1177/03946320110241s230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The most significant results in experimental and clinical orthopaedic research in Italy within the last three years have been primarily in major congenital diseases, bone tumors, regenerative medicine, joint replacements, spine, tendons and ligaments. The data presented in the following discussion is comparable with leading international results, highlighting Italian orthopaedic research excellemce as well as its shortcomings.
Collapse
Affiliation(s)
- E Cenni
- Istituto Ortopedico Rizzoli, Bologna, Italy
| | | | | |
Collapse
|
39
|
Leung P, Pickarski M, Zhuo Y, Masarachia PJ, Duong LT. The effects of the cathepsin K inhibitor odanacatib on osteoclastic bone resorption and vesicular trafficking. Bone 2011; 49:623-35. [PMID: 21718816 DOI: 10.1016/j.bone.2011.06.014] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 06/10/2011] [Accepted: 06/14/2011] [Indexed: 11/28/2022]
Abstract
Odanacatib (ODN) is a selective, potent and reversible inhibitor of cathepsin K (CatK) that inhibits bone loss in postmenopausal osteoporosis. Evidence from osteoclast (OC) formation from bone marrow of CatK(-/-) mice or human OC progenitors treated with ODN, demonstrated that CatK inhibition has no effect on osteoclastogenesis or survival of OCs. Although having no impact on OC activation, ODN reduces resorption activity as measured by CTx release (IC(50)=9.4 nM) or resorption area (IC(50)=6.5 nM). While untreated cells generate deep trail-like resorption lacunae, treated OCs form small discrete shallow pits. ODN leads to significant accumulation of intracellular vesicles intensely stained for CatK and TRAP. CatK (+) vesicles localize toward the basolateral and functional secretory membranes of the polarized OC and TRAP(+) vesicles evenly distribute in the cytoplasm, suggesting that ODN disrupts multiple vesicular trafficking pathways. Intracellular levels of both precursor and mature TRAP were increased by 2-fold and the pre-pro and mature CatK by 6- and 2-fold in ODN-treated OCs compared to untreated controls. ODN treated OC accumulates labeled degraded bone matrix proteins in CatK containing vesicles. In summary, ODN treatment inhibits bone resorption by blocking degradation of demineralized collagen in the resorption lacunae, and retarding transcytosis for further processing of degraded proteins.
Collapse
Affiliation(s)
- P Leung
- Merck Sharp, & Dohme Corp., P.O. Box 100, Whitehouse Station, NJ 08889, USA
| | | | | | | | | |
Collapse
|
40
|
Almarzooqi S, Reed S, Fung B, Boué DR, Prasad V, Pietryga D. Infantile osteopetrosis and juvenile xanthogranuloma presenting together in a newborn: a case report and literature review. Pediatr Dev Pathol 2011; 14:307-12. [PMID: 21054159 DOI: 10.2350/10-09-0909-cr.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Osteopetrosis (OP) is a clinically and genetically heterogeneous disorder characterized by increased bone density. Associations between OP and other clinical entities are rare but include muscular degeneration, Dandy-Walker syndrome, craniosynostosis, and poikiloderma. Infantile OP has also been diagnosed in a group of infants with neuronal storage disease. An association between OP and juvenile xanthogranuloma (JXG) has never been previously reported. Herein we present a case of an intermediate form of OP in a newborn who presented with hepatosplenomegaly and pancytopenia. Histologic evaluation of a bone marrow biopsy demonstrated abnormally thickened bony trabeculae. A liver biopsy demonstrated prominent expansion of portal areas by a histiocytic infiltrate expressing CD45, CD14, CD68, CD163, factor XIIIa, and fascin, while the biopsy was negative for S100 and CD1a. These findings were those associated with JXG. Genetic testing demonstrated a mutation involving the Pleckstrin homology domain-containing family M member 1 ( PLEKHM1 ) gene. A different mutation in this gene has been previously reported in one other patient with OP. Our case is the 2nd reported case with PLEKHM1 mutation in a patient with a mild form of OP. It also demonstrates the 1st reported occurrence of OP concomitantly with JXG.
Collapse
|
41
|
|
42
|
Crockett JC, Mellis DJ, Scott DI, Helfrich MH. New knowledge on critical osteoclast formation and activation pathways from study of rare genetic diseases of osteoclasts: focus on the RANK/RANKL axis. Osteoporos Int 2011; 22:1-20. [PMID: 20458572 DOI: 10.1007/s00198-010-1272-8] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Accepted: 03/30/2010] [Indexed: 12/14/2022]
Abstract
Functional, biochemical and genetic studies have over the past decade identified many causative genes in the osteoclast diseases osteopetrosis and Paget's disease of bone. Here, we outline all osteoclast diseases and their genetic associations and then focus specifically on those diseases caused by mutations in the critical osteoclast molecule Receptor Activator of Nuclear factor Kappa B (RANK). Both loss and gain-of-function mutations have been found in humans leading to osteopetrosis and high bone turnover phenotypes, respectively. Osteopetrosis-associated RANK mutations are widely distributed over the RANK molecule. It is likely that some negatively affect ligand binding, whereas others preclude appropriate association of RANK with downstream signalling molecules. In the Paget-like disorders, familial expansile osteolysis, early onset Paget's disease and expansile skeletal hyperphosphatasia, heterozygous insertion mutations are found in the RANK signal peptide. These prevent signal peptide cleavage, trapping the protein translated from the mutated allele in the endoplasmic reticulum. Whole animal studies replicate the hyperactive osteoclast phenotype associated with these disorders and present only with heterozygous expression of the mutation, suggesting an as yet unexplained effect of the mutant allele on normal RANK function. We discuss the cell biological studies and animal models that help us to understand the nature of these different RANK defects and describe how careful dissection of these conditions can help understand critical pathways in osteoclast development and function. We highlight areas that require further study, particularly in light of the pharmacological interest in targeting the RANK signalling pathway to treat diseases caused by excessive bone resorption.
Collapse
Affiliation(s)
- J C Crockett
- Bone and Musculoskeletal Research Programme, Division of Applied Medicine, School of Medicine and Dentistry, University of Aberdeen, AB25 2ZD, Aberdeen, UK.
| | | | | | | |
Collapse
|
43
|
Committed osteoclast precursors colonize the bone and improve the phenotype of a mouse model of autosomal recessive osteopetrosis. J Bone Miner Res 2010; 25:106-13. [PMID: 20091929 DOI: 10.1359/jbmr.090715] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Osteopetrosis is a genetic disease characterized by defective osteoclasts. Autosomal recessive osteopetrosis is fatal within the first years of life. Hematopoietic stem cell transplantation (HSCT) cures fewer than 50% of cases but often leaves severe neurologic damages and other dysfunctions. Osteoclast appearance after HSCT is a slow process, during which disease progression continues. We hypothesize that a support osteoclast precursor therapy may contribute to improve the osteopetrotic phenotype. To this end, we established a procedure to obtain the best yield of osteoclast precursors from human peripheral blood or mouse bone marrow mononuclear cells. These cells were injected in vivo in animal models, testing different cell injection protocols, as well as in association with CD117+ stem cells. Injected cells showed the ability to form multinucleated osteoclasts and to improve the phenotype of oc/oc osteopetrotic mice. In the best working protocol, animals presented with longer survival, improved weight and longitudinal growth, increased tibial length, tooth eruption, decreased bone volume, reduced bone marrow fibrosis, and improved hematopoiesis compared with sham-treated mice. These results provide first-hand information on the feasibility of a support osteoclast precursor therapy in osteopetrosis.
Collapse
|
44
|
Gogakos AI, Cheung MS, Bassett JD, Williams GR. Bone signaling pathways and treatment of osteoporosis. Expert Rev Endocrinol Metab 2009; 4:639-650. [PMID: 30780784 DOI: 10.1586/eem.09.38] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Osteoporotic fractures are a major healthcare burden costing over US$50 billion/per year. Bone turnover is a continuous process regulated by the coupled activities of osteocytes, osteoclasts and osteoblasts that maintain bone mass and strength. Osteoclastic bone resorption is regulated by the RANKL/osteoprotegerin/RANK pathway, while osteoblastic bone formation is controlled by canonical Wnt signaling. Antiresorptive bisphosphonates remain the mainstay of treatment but recombinant parathyroid hormone is increasingly being used as an anabolic agent. Nevertheless, these drugs are limited by patient compliance, efficacy and cost. Cathepsin K inhibitors and RANKL antibodies have been developed as new antiresorptive drugs, while short-acting calcilytics and antibodies to Dickkopf-1 and sclerostin are promising anabolics. The recent identification of adipocytes and duodenal enterochromaffin cells as novel regulators of bone mass represent exciting opportunities for future drug development.
Collapse
Affiliation(s)
- Apostolos I Gogakos
- a Molecular Endocrinology Group, Imperial College London, MRC Clinical Sciences Centre, Room 7N2, 7th Floor Commonwealth Building, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK.
| | - Moira S Cheung
- b Molecular Endocrinology Group, Imperial College London, MRC Clinical Sciences Centre, Room 7N2, 7th Floor Commonwealth Building, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK.
| | - Jh Duncan Bassett
- c Molecular Endocrinology Group, Imperial College London, MRC Clinical Sciences Centre, Room 7N2b, 7th Floor Commonwealth Building, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK.
| | - Graham R Williams
- d Molecular Endocrinology Group, Imperial College London, MRC Clinical Sciences Centre, Room 7N2a, 7th Floor Commonwealth Building, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK.
| |
Collapse
|
45
|
Henriksen K, Neutzsky-Wulff AV, Bonewald LF, Karsdal MA. Local communication on and within bone controls bone remodeling. Bone 2009; 44:1026-33. [PMID: 19345750 DOI: 10.1016/j.bone.2009.03.671] [Citation(s) in RCA: 172] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2008] [Revised: 03/16/2009] [Accepted: 03/18/2009] [Indexed: 02/04/2023]
Abstract
Bone remodeling is required for healthy calcium homeostasis and for repair of damage occurring with stress and age. Osteoclasts resorb bone and osteoblasts form bone. These processes normally occur in a tightly regulated sequence of events, where the amount of formed bone equals the amount of resorbed bone, thereby restoring the removed bone completely. Osteocytes are the third cell type playing an essential role in bone turnover. They appear to regulate activation of bone remodeling, and they exert both positive and negative regulation on both osteoclasts and osteoblasts. In this review, we consider the intricate communication between these bone cells in relation to bone remodeling, reviewing novel data from patients with mutations rendering different cell populations inactive, which have shown that these interactions are more complex than originally thought. We highlight the high probability that a detailed understanding of these processes will aid in the development of novel treatments for bone metabolic disorders, i.e. we discuss the possibility that bone resorption can be attenuated pharmacologically without a secondary reduction in bone formation.
Collapse
Affiliation(s)
- Kim Henriksen
- Nordic Bioscience A/S, Herlev Hovedgade 207, DK-2730 Herlev, Denmark.
| | | | | | | |
Collapse
|
46
|
Villa A, Guerrini MM, Cassani B, Pangrazio A, Sobacchi C. Infantile malignant, autosomal recessive osteopetrosis: the rich and the poor. Calcif Tissue Int 2009; 84:1-12. [PMID: 19082854 DOI: 10.1007/s00223-008-9196-4] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Accepted: 11/07/2008] [Indexed: 02/06/2023]
Abstract
Human recessive osteopetrosis (ARO) represents a group of diseases in which, due to a defect in osteoclasts, bone resorption is prevented. The deficit could arise either from failure in osteoclast differentiation or from inability to perform resorption by mature, multinucleated, but nonfunctional cells. Historically, osteopetrosis due to both these mechanisms was found in spontaneous and artificially created mouse mutants, but the first five genes identified in human ARO (CA-II, TCIRG1, ClCN7, OSTM1, and PLEKHM1) were all involved in the effector function of mature osteoclasts, being linked to acidification of the cell/bone interface or to intracellular processing of the resorbed material. Differentiation defects in human ARO have only recently been described, following the identification of mutations in both RANKL and RANK, which define a new form of osteoclast-poor ARO, as expected from biochemical, cellular, and animal studies. The molecular dissection of ARO has prognostic and therapeutic implications. RANKL-dependent patients, in particular, represent an interesting subset which could benefit from mesenchymal cell transplant and/or administration of soluble RANKL cytokine.
Collapse
Affiliation(s)
- Anna Villa
- Istituto di Tecnologie Biomediche, CNR, via Cervi 93, Segrate, Italy.
| | | | | | | | | |
Collapse
|
47
|
|
48
|
Kaunitz JD, Yamaguchi DT. TNAP, TrAP, ecto-purinergic signaling, and bone remodeling. J Cell Biochem 2008; 105:655-62. [PMID: 18773425 DOI: 10.1002/jcb.21885] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Bone remodeling is a process of continuous resorption and formation/mineralization carried out by osteoclasts and osteoblasts, which, along with osteocytes, comprise the bone multicellular unit (BMU). A key component of the BMU is the bone remodeling compartment (BRC), isolated from the marrow by a canopy of osteoblast-like lining cells. Although much progress has been made regarding the cytokine-dependent and hormonal regulation of bone remodeling, less attention has been placed on the role of extracellular pH (pH(e)). Osteoclastic bone resorption occurs at acidic pH(e). Furthermore, osteoclasts can be regarded as epithelial-like cells, due to their polarized structure and ability to form a seal against bone, isolating the lacunar space. The major ecto-phosphatases of osteoclasts and osteoblasts, acid and alkaline phosphatases, both have ATPase activity with pH optima several units different from neutrality. Furthermore, osteoclasts and osteoblasts express plasma membrane purinergic P2 receptors that, upon activation by ATP, accelerate bone osteoclast resorption and impair osteoblast mineralization. We hypothesize that these ecto-phosphatases help regulate [ATP](e) and localized pH(e) at the sites of bone resorption and mineralization by pH-dependent ATP hydrolysis coupled with P2Y-dependent regulation of osteoclast and osteoblast function. Furthermore, osteoclast cellular HCO3(-), formed as a product of lacunar V-ATPase H(+) secretion, is secreted into the BRC, which could elevate BRC pH(e), in turn affecting osteoblast function. We will review the existing data addressing regulation of BRC pH(e), present a hypothesis regarding its regulation, and discuss the hypothesis in the context of the function of proteins that regulate pH(e).
Collapse
Affiliation(s)
- Jonathan D Kaunitz
- Department of Medicine, Division of Gastroenterology, UCLA School of Medicine, Los Angeles, California 90073, USA.
| | | |
Collapse
|
49
|
Advances in osteoclast biology resulting from the study of osteopetrotic mutations. Hum Genet 2008; 124:561-77. [DOI: 10.1007/s00439-008-0583-8] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Accepted: 10/28/2008] [Indexed: 02/05/2023]
|
50
|
Coxon FP, Taylor A. Vesicular trafficking in osteoclasts. Semin Cell Dev Biol 2008; 19:424-33. [DOI: 10.1016/j.semcdb.2008.08.004] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2008] [Revised: 08/04/2008] [Accepted: 08/08/2008] [Indexed: 11/24/2022]
|