51
|
Canalis E, Zanotti S, Schilling L, Eller T, Yu J. Activation of Notch3 in osteoblasts/osteocytes causes compartment-specific changes in bone remodeling. J Biol Chem 2021; 296:100583. [PMID: 33774049 PMCID: PMC8086145 DOI: 10.1016/j.jbc.2021.100583] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 03/12/2021] [Accepted: 03/22/2021] [Indexed: 12/24/2022] Open
Abstract
Notch receptors maintain skeletal homeostasis. NOTCH1 and 2 have been studied for their effects on bone remodeling. Although NOTCH3 plays a significant role in vascular physiology, knowledge about its function in other cellular environments, including bone, is limited. The present study was conducted to establish the function of NOTCH3 in skeletal cells using models of Notch3 misexpression. Microcomputed tomography demonstrated that Notch3 null mice did not have appreciable bone phenotypes. To study the effects of the NOTCH3 activation in the osteoblast lineage, BGLAP-Cre or Dmp1-Cre transgenics were crossed with RosaNotch3 mice, where the NOTCH3 intracellular domain is expressed following the removal of a loxP-flanked STOP cassette. Microcomputed tomography demonstrated that BGLAP-Cre;RosaNotch3 and Dmp1-Cre;RosaNotch3 mice of both sexes exhibited an increase in trabecular bone and in connectivity, with a decrease in cortical bone and increased cortical porosity. Histological analysis revealed a decrease in osteoclast number and bone resorption in trabecular bone and an increase in osteoclast number and void or pore area in cortical bone of RosaNotch3 mice. Bone formation was either decreased or could not be determined in Cre;RosaNotch3 mice. NOTCH3 activation in osteoblasts inhibited Alpl (alkaline phosphatase) and Bglap (osteocalcin) and induced Tnfsf11 (RANKL) and Tnfrsf11b (osteoprotegerin) mRNA, possibly explaining the trabecular bone phenotype. However, NOTCH3 induced Tnfsf11 and suppressed Tnfrsf11b in osteocytes, possibly explaining the cortical porosity. In conclusion, basal NOTCH3 is dispensable for skeletal homeostasis, whereas activation of NOTCH3 in osteoblasts/osteocytes inhibits osteoclastogenesis and bone resorption in cancellous bone but increases intracortical remodeling and causes cortical porosity.
Collapse
Affiliation(s)
- Ernesto Canalis
- Department of Orthopaedic Surgery, UConn Health, Farmington, Connecticut, USA; Department of Medicine, UConn Health, Farmington, Connecticut, USA; UConn Musculoskeletal Institute, UConn Health, Farmington, Connecticut, USA.
| | - Stefano Zanotti
- Department of Orthopaedic Surgery, UConn Health, Farmington, Connecticut, USA; UConn Musculoskeletal Institute, UConn Health, Farmington, Connecticut, USA
| | - Lauren Schilling
- UConn Musculoskeletal Institute, UConn Health, Farmington, Connecticut, USA
| | - Tabitha Eller
- UConn Musculoskeletal Institute, UConn Health, Farmington, Connecticut, USA
| | - Jungeun Yu
- Department of Orthopaedic Surgery, UConn Health, Farmington, Connecticut, USA; UConn Musculoskeletal Institute, UConn Health, Farmington, Connecticut, USA
| |
Collapse
|
52
|
Kelly RR, Sidles SJ, LaRue AC. Effects of Neurological Disorders on Bone Health. Front Psychol 2020; 11:612366. [PMID: 33424724 PMCID: PMC7793932 DOI: 10.3389/fpsyg.2020.612366] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 11/11/2020] [Indexed: 01/10/2023] Open
Abstract
Neurological diseases, particularly in the context of aging, have serious impacts on quality of life and can negatively affect bone health. The brain-bone axis is critically important for skeletal metabolism, sensory innervation, and endocrine cross-talk between these organs. This review discusses current evidence for the cellular and molecular mechanisms by which various neurological disease categories, including autoimmune, developmental, dementia-related, movement, neuromuscular, stroke, trauma, and psychological, impart changes in bone homeostasis and mass, as well as fracture risk. Likewise, how bone may affect neurological function is discussed. Gaining a better understanding of brain-bone interactions, particularly in patients with underlying neurological disorders, may lead to development of novel therapies and discovery of shared risk factors, as well as highlight the need for broad, whole-health clinical approaches toward treatment.
Collapse
Affiliation(s)
- Ryan R. Kelly
- Research Services, Ralph H. Johnson VA Medical Center, Charleston, SC, United States
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC, United States
| | - Sara J. Sidles
- Research Services, Ralph H. Johnson VA Medical Center, Charleston, SC, United States
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC, United States
| | - Amanda C. LaRue
- Research Services, Ralph H. Johnson VA Medical Center, Charleston, SC, United States
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC, United States
| |
Collapse
|
53
|
Hall-Roberts H, Agarwal D, Obst J, Smith TB, Monzón-Sandoval J, Di Daniel E, Webber C, James WS, Mead E, Davis JB, Cowley SA. TREM2 Alzheimer's variant R47H causes similar transcriptional dysregulation to knockout, yet only subtle functional phenotypes in human iPSC-derived macrophages. Alzheimers Res Ther 2020; 12:151. [PMID: 33198789 PMCID: PMC7667762 DOI: 10.1186/s13195-020-00709-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 10/20/2020] [Indexed: 01/21/2023]
Abstract
BACKGROUND TREM2 is a microglial cell surface receptor, with risk mutations linked to Alzheimer's disease (AD), including R47H. TREM2 signalling via SYK aids phagocytosis, chemotaxis, survival, and changes to microglial activation state. In AD mouse models, knockout (KO) of TREM2 impairs microglial clustering around amyloid and prevents microglial activation. The R47H mutation is proposed to reduce TREM2 ligand binding. We investigated cell phenotypes of the R47H mutant and TREM2 KO in a model of human microglia, and compared their transcriptional signatures, to determine the mechanism by which R47H TREM2 disrupts function. METHODS We generated human microglia-like iPSC-macrophages (pMac) from isogenic induced pluripotent stem cell (iPSC) lines, with homozygous R47H mutation or TREM2 knockout (KO). We firstly validated the effect of the R47H mutant on TREM2 surface and subcellular localization in pMac. To assess microglial phenotypic function, we measured phagocytosis of dead neurons, cell morphology, directed migration, survival, and LPS-induced inflammation. We performed bulk RNA-seq, comparing significant differentially expressed genes (DEGs; p < 0.05) between the R47H and KO versus WT, and bioinformatically predicted potential upstream regulators of TREM2-mediated gene expression. RESULTS R47H modified surface expression and shedding of TREM2, but did not impair TREM2-mediated signalling, or gross phenotypes that were dysregulated in the TREM2 KO (phagocytosis, motility, survival). However, altered gene expression in the R47H TREM2 pMac overlapped by 90% with the TREM2 KO and was characterised by dysregulation of genes involved with immunity, proliferation, activation, chemotaxis, and adhesion. Downregulated mediators of ECM adhesion included the vitronectin receptor αVβ3, and consequently, R47H TREM2 pMac adhered weakly to vitronectin compared with WT pMac. To counteract these transcriptional defects, we investigated TGFβ1, as a candidate upstream regulator. TGFβ1 failed to rescue vitronectin adhesion of pMac, although it improved αVβ3 expression. CONCLUSIONS The R47H mutation is not sufficient to cause gross phenotypic defects of human pMac under standard culture conditions. However, overlapping transcriptional defects with TREM2 KO supports the hypothesised partial loss-of-function effects of the R47H mutation. Furthermore, transcriptomics can guide us to more subtle phenotypic defects in the R47H cells, such as reduced cell adhesion, and can be used to predict targets for therapeutic intervention.
Collapse
Affiliation(s)
- Hazel Hall-Roberts
- James Martin Stem Cell Facility, Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE UK
- Nuffield Department of Medicine Research Building, Alzheimer’s Research UK Oxford Drug Discovery Institute, University of Oxford, Oxford, OX3 7FZ UK
| | - Devika Agarwal
- Nuffield Department of Medicine Research Building, Alzheimer’s Research UK Oxford Drug Discovery Institute, University of Oxford, Oxford, OX3 7FZ UK
- Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS UK
| | - Juliane Obst
- Nuffield Department of Medicine Research Building, Alzheimer’s Research UK Oxford Drug Discovery Institute, University of Oxford, Oxford, OX3 7FZ UK
| | - Thomas B. Smith
- Nuffield Department of Medicine Research Building, Alzheimer’s Research UK Oxford Drug Discovery Institute, University of Oxford, Oxford, OX3 7FZ UK
| | | | - Elena Di Daniel
- Nuffield Department of Medicine Research Building, Alzheimer’s Research UK Oxford Drug Discovery Institute, University of Oxford, Oxford, OX3 7FZ UK
| | - Caleb Webber
- UK Dementia Research Institute, Cardiff University, Cardiff, CF24 4HQ UK
| | - William S. James
- James Martin Stem Cell Facility, Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE UK
| | - Emma Mead
- Nuffield Department of Medicine Research Building, Alzheimer’s Research UK Oxford Drug Discovery Institute, University of Oxford, Oxford, OX3 7FZ UK
| | - John B. Davis
- Nuffield Department of Medicine Research Building, Alzheimer’s Research UK Oxford Drug Discovery Institute, University of Oxford, Oxford, OX3 7FZ UK
| | - Sally A. Cowley
- James Martin Stem Cell Facility, Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE UK
| |
Collapse
|
54
|
Anti-Sclerostin Antibodies in Osteoporosis and Other Bone Diseases. J Clin Med 2020; 9:jcm9113439. [PMID: 33114755 PMCID: PMC7694131 DOI: 10.3390/jcm9113439] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 10/19/2020] [Accepted: 10/20/2020] [Indexed: 12/11/2022] Open
Abstract
The Wnt pathway is a key element of bone remodeling; its activation stimulates bone formation and inhibits bone resorption. The discovery of sclerostin, a natural antagonist of the Wnt pathway, promoted the development of romosozumab, a human monoclonal antibody directed against sclerostin, as well as other anti-sclerostin antibodies. Phase 3 studies have shown the efficacy of romosozumab in the prevention of fractures in postmenopausal women, against placebo but also against alendronate or teriparatide and this treatment also allows bone mineral density (BMD) increase in men. Romosozumab induces the uncoupling of bone remodeling, leading to both an increase in bone formation and a decrease in bone resorption during the first months of treatment. The effect is attenuated over time and reversible when stopped but transition with anti-resorbing agents allows the maintenance or reinforcement of BMD improvements. Some concerns were raised about cardiovascular events. Therefore, romosozumab was recently approved in several countries for the treatment of severe osteoporosis in postmenopausal women with high fracture risk and without a history of heart attack, myocardial infarction or stroke. This review aims to outline the role of sclerostin, the efficacy and safety of anti-sclerostin therapies and in particular romosozumab and their place in therapeutic strategies against osteoporosis or other bone diseases.
Collapse
|
55
|
McQuade A, Kang YJ, Hasselmann J, Jairaman A, Sotelo A, Coburn M, Shabestari SK, Chadarevian JP, Fote G, Tu CH, Danhash E, Silva J, Martinez E, Cotman C, Prieto GA, Thompson LM, Steffan JS, Smith I, Davtyan H, Cahalan M, Cho H, Blurton-Jones M. Gene expression and functional deficits underlie TREM2-knockout microglia responses in human models of Alzheimer's disease. Nat Commun 2020; 11:5370. [PMID: 33097708 PMCID: PMC7584603 DOI: 10.1038/s41467-020-19227-5] [Citation(s) in RCA: 131] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 09/30/2020] [Indexed: 12/11/2022] Open
Abstract
The discovery of TREM2 as a myeloid-specific Alzheimer's disease (AD) risk gene has accelerated research into the role of microglia in AD. While TREM2 mouse models have provided critical insight, the normal and disease-associated functions of TREM2 in human microglia remain unclear. To examine this question, we profile microglia differentiated from isogenic, CRISPR-modified TREM2-knockout induced pluripotent stem cell (iPSC) lines. By combining transcriptomic and functional analyses with a chimeric AD mouse model, we find that TREM2 deletion reduces microglial survival, impairs phagocytosis of key substrates including APOE, and inhibits SDF-1α/CXCR4-mediated chemotaxis, culminating in an impaired response to beta-amyloid plaques in vivo. Single-cell sequencing of xenotransplanted human microglia further highlights a loss of disease-associated microglial (DAM) responses in human TREM2 knockout microglia that we validate by flow cytometry and immunohistochemistry. Taken together, these studies reveal both conserved and novel aspects of human TREM2 biology that likely play critical roles in the development and progression of AD.
Collapse
Affiliation(s)
- Amanda McQuade
- grid.266093.80000 0001 0668 7243Department of Neurobiology & Behavior, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA
| | - You Jung Kang
- grid.266859.60000 0000 8598 2218Department of Mechanical Engineering and Engineering Science, University of North Carolina Charlotte, Charlotte, NC 28223 USA ,grid.266859.60000 0000 8598 2218Department of Biological Sciences, University of North Carolina Charlotte, Charlotte, NC 28223 USA ,grid.266859.60000 0000 8598 2218Nanoscale Science Program, University of North Carolina Charlotte, Charlotte, NC 28223 USA ,grid.266859.60000 0000 8598 2218Center for Biomedical Engineering and Science, University of North Carolina Charlotte, Charlotte, NC 28223 USA
| | - Jonathan Hasselmann
- grid.266093.80000 0001 0668 7243Department of Neurobiology & Behavior, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA
| | - Amit Jairaman
- grid.266093.80000 0001 0668 7243Department of Physiology and Biophysics, University of California Irvine, Irvine, CA 92697 USA
| | - Alexandra Sotelo
- grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA
| | - Morgan Coburn
- grid.266093.80000 0001 0668 7243Department of Neurobiology & Behavior, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA
| | - Sepideh Kiani Shabestari
- grid.266093.80000 0001 0668 7243Department of Neurobiology & Behavior, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA
| | - Jean Paul Chadarevian
- grid.266093.80000 0001 0668 7243Department of Neurobiology & Behavior, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA
| | - Gianna Fote
- grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA
| | - Christina H. Tu
- grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA
| | - Emma Danhash
- grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA
| | - Jorge Silva
- grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA
| | - Eric Martinez
- grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA
| | - Carl Cotman
- grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA
| | - G. Aleph Prieto
- grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA ,grid.9486.30000 0001 2159 0001Institute of Neurobiology, National Autonomous University of Mexico, Queretaro, Mexico
| | - Leslie M. Thompson
- grid.266093.80000 0001 0668 7243Department of Neurobiology & Behavior, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA ,grid.266859.60000 0000 8598 2218Department of Biological Sciences, University of North Carolina Charlotte, Charlotte, NC 28223 USA
| | - Joan S. Steffan
- grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Department of Psychology and Human Behavior, University of California Irvine, Irvine, CA 92697 USA
| | - Ian Smith
- grid.266093.80000 0001 0668 7243Department of Neurobiology & Behavior, University of California Irvine, Irvine, CA 92697 USA
| | - Hayk Davtyan
- grid.266093.80000 0001 0668 7243Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA 92697 USA ,grid.266093.80000 0001 0668 7243Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697 USA
| | - Michael Cahalan
- grid.266093.80000 0001 0668 7243Department of Physiology and Biophysics, University of California Irvine, Irvine, CA 92697 USA
| | - Hansang Cho
- grid.266859.60000 0000 8598 2218Department of Mechanical Engineering and Engineering Science, University of North Carolina Charlotte, Charlotte, NC 28223 USA ,grid.266859.60000 0000 8598 2218Department of Biological Sciences, University of North Carolina Charlotte, Charlotte, NC 28223 USA ,grid.266859.60000 0000 8598 2218Nanoscale Science Program, University of North Carolina Charlotte, Charlotte, NC 28223 USA ,grid.266859.60000 0000 8598 2218Center for Biomedical Engineering and Science, University of North Carolina Charlotte, Charlotte, NC 28223 USA ,grid.264381.a0000 0001 2181 989XDepartment of Biophysics, Sungkyunkwan University, Suwon, 16419 Korea
| | - Mathew Blurton-Jones
- Department of Neurobiology & Behavior, University of California Irvine, Irvine, CA, 92697, USA. .,Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA, 92697, USA. .,Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA, 92697, USA.
| |
Collapse
|
56
|
Yu J, Canalis E. Notch and the regulation of osteoclast differentiation and function. Bone 2020; 138:115474. [PMID: 32526405 PMCID: PMC7423683 DOI: 10.1016/j.bone.2020.115474] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 06/05/2020] [Accepted: 06/05/2020] [Indexed: 12/30/2022]
Abstract
Notch 1 through 4 are transmembrane receptors that play a pivotal role in cell differentiation and function; this review addresses the role of Notch signaling in osteoclastogenesis and bone resorption. Notch receptors are activated following interactions with their ligands of the Jagged and Delta-like families. In the skeleton, Notch signaling controls osteoclast differentiation and bone-resorbing activity either directly acting on osteoclast precursors, or indirectly acting on cells of the osteoblast lineage and cells of the immune system. NOTCH1 inhibits osteoclastogenesis, whereas NOTCH2 enhances osteoclast differentiation and function by direct and indirect mechanisms. NOTCH3 induces the expression of RANKL in osteoblasts and osteocytes and as a result induces osteoclast differentiation. There is limited expression of NOTCH4 in skeletal cells. Selected congenital disorders and skeletal malignancies are associated with dysregulated Notch signaling and enhanced bone resorption. In conclusion, Notch signaling is a critical pathway that controls osteoblast and osteoclast differentiation and function and regulates skeletal homeostasis in health and disease.
Collapse
Affiliation(s)
- Jungeun Yu
- Departments of Orthopaedic Surgery, UConn Musculoskeletal Institute, Farmington, CT 06030, USA; UConn Musculoskeletal Institute, UConn Health, Farmington, CT 06030, USA
| | - Ernesto Canalis
- Departments of Orthopaedic Surgery, UConn Musculoskeletal Institute, Farmington, CT 06030, USA; Medicine, UConn Musculoskeletal Institute, Farmington, CT 06030, USA; UConn Musculoskeletal Institute, UConn Health, Farmington, CT 06030, USA.
| |
Collapse
|
57
|
Price BR, Sudduth TL, Weekman EM, Johnson S, Hawthorne D, Woolums A, Wilcock DM. Therapeutic Trem2 activation ameliorates amyloid-beta deposition and improves cognition in the 5XFAD model of amyloid deposition. J Neuroinflammation 2020; 17:238. [PMID: 32795308 PMCID: PMC7427742 DOI: 10.1186/s12974-020-01915-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 07/30/2020] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Triggering receptor expressed on myeloid cell-2 (TREM2) is a lipid and lipoprotein binding receptor expressed by cells of myeloid origin. Homozygous TREM2 mutations cause early onset progressive presenile dementia while heterozygous, point mutations triple the risk of Alzheimer's disease (AD). Although human genetic findings support the notion that loss of TREM2 function exacerbates neurodegeneration, it is not clear whether activation of TREM2 in a disease state would result in therapeutic benefits. To determine the viability of TREM2 activation as a therapeutic strategy, we sought to characterize an agonistic Trem2 antibody (AL002a) and test its efficacy and mechanism of action in an aggressive mouse model of amyloid deposition. METHODS To determine whether agonism of Trem2 results in therapeutic benefits, we designed both intracranial and systemic administration studies. 5XFAD mice in the intracranial administration study were assigned to one of two injection groups: AL002a, a Trem2-agonizing antibody, or MOPC, an isotype-matched control antibody. Mice were then subject to a single bilateral intracranial injection into the frontal cortex and hippocampus and euthanized 72 h later. The tissue from the left hemisphere was histologically examined for amyloid-beta and microglia activation, whereas the tissue from the right hemisphere was used for biochemical analyses. Similarly, mice in the systemic administration study were randomized to one of the aforementioned injection groups and the assigned antibody was administered intraperitoneally once a week for 14 weeks. Mice underwent behavioral assessment between the 12- and 14-week timepoints and were euthanized 24 h after their final injection. The tissue from the left hemisphere was used for histological analyses whereas the tissue from the right hemisphere was used for biochemical analyses. RESULTS Here, we show that chronic activation of Trem2, in the 5XFAD mouse model of amyloid deposition, leads to reversal of the amyloid-associated gene expression signature, recruitment of microglia to plaques, decreased amyloid deposition, and improvement in spatial learning and novel object recognition memory. CONCLUSIONS These findings indicate that Trem2 activators may be effective for the treatment of AD and possibly other neurodegenerative disorders.
Collapse
Affiliation(s)
- Brittani R Price
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA
- Department of Physiology, University of Kentucky, Lexington, KY, 40536, USA
| | - Tiffany L Sudduth
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA
| | - Erica M Weekman
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA
- Department of Physiology, University of Kentucky, Lexington, KY, 40536, USA
| | - Sherika Johnson
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA
| | - Danielle Hawthorne
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA
| | - Abigail Woolums
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA
- Department of Physiology, University of Kentucky, Lexington, KY, 40536, USA
| | - Donna M Wilcock
- Sanders-Brown Center on Aging, College of Medicine, University of Kentucky, 800 S Limestone St, Lexington, KY, 40536, USA.
- Department of Physiology, University of Kentucky, Lexington, KY, 40536, USA.
| |
Collapse
|
58
|
Schwabe T, Srinivasan K, Rhinn H. Shifting paradigms: The central role of microglia in Alzheimer's disease. Neurobiol Dis 2020; 143:104962. [PMID: 32535152 DOI: 10.1016/j.nbd.2020.104962] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Revised: 05/01/2020] [Accepted: 06/10/2020] [Indexed: 12/31/2022] Open
Abstract
Recent human genetic studies have challenged long standing hypotheses about the chain of events in Alzheimer's disease (AD), as the identification of genetic risk factors in microglial genes supports a causative role for microglia in the disease. Parallel transcriptome and histology studies at the single-cell level revealed a rich palette of microglial states affected by disease status and genetic risk factors. Taken together, those findings support microglia dysfunction as a central mechanism in AD etiology and thus the therapeutic potential of modulating microglial activity for AD treatment. Here we review how human genetic studies discovered microglial AD risk genes, such as TREM2, CD33, MS4A and APOE, and how experimental studies are beginning to decipher the cellular functions of some of these genes. Our review also focuses on recent transcriptomic studies of human microglia from postmortem tissue to critically assess areas of similarity and dissimilarity between human and mouse models currently in use in order to better understand the biology of innate immunity in AD.
Collapse
|
59
|
Deczkowska A, Weiner A, Amit I. The Physiology, Pathology, and Potential Therapeutic Applications of the TREM2 Signaling Pathway. Cell 2020; 181:1207-1217. [DOI: 10.1016/j.cell.2020.05.003] [Citation(s) in RCA: 143] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 04/15/2020] [Accepted: 04/30/2020] [Indexed: 12/20/2022]
|
60
|
Abstract
The adaptor protein 3BP2 (SH3-domain binding protein 2), which is encoded by the SH3BP2 locus, nucleates a signaling complex comprising ABL, SRC, VAV, and SYK, and facilitates an open active configuration of these proteins, leading to their kinase activation. Gain-of-function missense mutations in the SH3BP2 gene cause cherubism, an autosomal dominant disorder associated with severe craniofacial developmental defects in children. Previous studies have demonstrated that 3BP2 and its degradation pathway regulate bone metabolism, energy metabolism, and inflammation and that dysregulation of the 3BP2 degradation pathway is associated with human disorders. Herein, we discussed lessons from cherubism indicating that 3BP2 studies could elucidate the pathogenesis of bone loss caused by inflammation and identify suitable therapeutic targets.
Collapse
Affiliation(s)
- Yoshinori Matsumoto
- Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Robert Rottapel
- Princess Margaret Cancer Center, University Health Network, University of Toronto, Toronto, Canada
| |
Collapse
|
61
|
Frame G, Bretland KA, Dengler-Crish CM. Mechanistic complexities of bone loss in Alzheimer's disease: a review. Connect Tissue Res 2020; 61:4-18. [PMID: 31184223 DOI: 10.1080/03008207.2019.1624734] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Purpose/Aim: Alzheimer's disease (AD), the primary cause of dementia in the elderly, is one of the leading age-related neurodegenerative diseases worldwide. While AD is notorious for destroying memory and cognition, dementia patients also experience greater incidence of bone loss and skeletal fracture than age-matched neurotypical individuals, greatly impacting their quality of life. Despite the significance of this comorbidity, there is no solid understanding of the mechanisms driving early bone loss in AD. Here, we review studies that have evaluated many of the obvious risk factors shared by dementia and osteoporosis, and illuminate emerging work investigating covert pathophysiological mechanisms shared between the disorders that may have potential as new risk biomarkers or therapeutic targets in AD.Conclusions: Skeletal deficits emerge very early in clinical Alzheimer's progression, and cannot be explained by coincident factors such as aging, female sex, mobility status, falls, or genetics. While research in this area is still in its infancy, studies implicate several potential mechanisms in disrupting skeletal homeostasis that include direct effects of amyloid-beta pathology on bone cells, neurofibrillary tau-induced damage to neural centers regulating skeletal remodeling, and/or systemic Wnt/Beta-catenin signaling deficits. Data from an increasing number of studies substantiate a role for the newly discovered "exercise hormone" irisin and its protein precursor FNDC5 in bone loss and AD-associated neurodegeneration. We conclude that the current status of research on bone loss in AD is insufficient and merits critical attention because this work could uncover novel diagnostic and therapeutic opportunities desperately needed to address AD.
Collapse
Affiliation(s)
- Gabrielle Frame
- Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA.,Biomedical Sciences Program, Kent State University, Kent, OH, USA
| | - Katie A Bretland
- Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA.,Integrated Pharmaceutical Medicine Program, Northeast Ohio Medical University, Rootstown, OH, USA
| | | |
Collapse
|
62
|
Golde TE. Harnessing Immunoproteostasis to Treat Neurodegenerative Disorders. Neuron 2019; 101:1003-1015. [PMID: 30897353 DOI: 10.1016/j.neuron.2019.02.027] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 02/05/2019] [Accepted: 02/15/2019] [Indexed: 12/12/2022]
Abstract
Immunoproteostasis is a term used to reflect interactions between the immune system and the proteinopathies that are presumptive "triggers" of many neurodegenerative disorders. The study of immunoproteostasis is bolstered by several observations. Mutations or rare variants in genes expressed in microglial cells, known to regulate immune functions, or both can cause, or alter risk for, various neurodegenerative disorders. Additionally, genetic association studies identify numerous loci harboring genes that encode proteins of known immune function that alter risk of developing Alzheimer's disease (AD) and other neurodegenerative proteinopathies. Further, preclinical studies reveal beneficial effects and liabilities of manipulating immune pathways in various neurodegenerative disease models. Although there are concerns that manipulation of the immune system may cause more harm than good, there is considerable interest in developing immune modulatory therapies for neurodegenerative disorders. Herein, I highlight the promise and challenges of harnessing immunoproteostasis to treat neurodegenerative proteinopathies.
Collapse
Affiliation(s)
- Todd E Golde
- McKnight Brain Institute, Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience and Neurology, University of Florida, Gainesville, FL 32607, USA.
| |
Collapse
|
63
|
Jay TR, von Saucken VE, Muñoz B, Codocedo JF, Atwood BK, Lamb BT, Landreth GE. TREM2 is required for microglial instruction of astrocytic synaptic engulfment in neurodevelopment. Glia 2019; 67:1873-1892. [PMID: 31265185 DOI: 10.1002/glia.23664] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 05/03/2019] [Accepted: 06/05/2019] [Indexed: 01/08/2023]
Abstract
Variants in the microglial receptor TREM2 confer risk for multiple neurodegenerative diseases. However, it remains unknown how this receptor functions on microglia to modulate these diverse neuropathologies. To understand the role of TREM2 on microglia more generally, we investigated changes in microglial function in Trem2-/- mice. We found that loss of TREM2 impairs normal neurodevelopment, resulting in reduced synapse number across the cortex and hippocampus in 1-month-old mice. This reduction in synapse number was not due directly to alterations in interactions between microglia and synapses. Rather, TREM2 was required for microglia to limit synaptic engulfment by astrocytes during development. While these changes were largely normalized later in adulthood, high fat diet administration was sufficient to reinitiate TREM2-dependent modulation of synapse loss. Together, this identifies a novel role for microglia in instructing synaptic pruning by astrocytes to broadly regulate appropriate synaptic refinement, and suggests novel candidate mechanisms for how TREM2 and microglia could influence synaptic loss in brain injury and disease.
Collapse
Affiliation(s)
- Taylor R Jay
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio
| | - Victoria E von Saucken
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana
| | - Braulio Muñoz
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, Indiana
| | - Juan F Codocedo
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana
| | - Brady K Atwood
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Bruce T Lamb
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana
| | - Gary E Landreth
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana
| |
Collapse
|
64
|
|
65
|
Ponzetti M, Rucci N. Updates on Osteoimmunology: What's New on the Cross-Talk Between Bone and Immune System. Front Endocrinol (Lausanne) 2019; 10:236. [PMID: 31057482 PMCID: PMC6482259 DOI: 10.3389/fendo.2019.00236] [Citation(s) in RCA: 110] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 03/25/2019] [Indexed: 12/11/2022] Open
Abstract
The term osteoimmunology was coined many years ago to describe the research field that deals with the cross-regulation between bone cells and the immune system. As a matter of fact, many factors that are classically considered immune-related, such as InterLeukins (i.e., IL-6, -11, -17, and -23), Tumor Necrosis Factor (TNF)-α, Receptor-Activator of Nuclear factor Kappa B (RANK), and its Ligand (RANKL), Nuclear Factor of Activated T-cell, cytoplasmatic-1 (NFATc1), and others have all been found to be crucial in osteoclast and osteoblast biology. Conversely, bone cells, which we used to think would only regulate each other and take care of remodeling bone, actually regulate immune cells, by creating the so-called "endosteal niche." Both osteoblasts and osteoclasts participate to this niche, either by favoring engraftment, or mobilization of Hematopoietic Stem Cells (HSCs). In this review, we will describe the main milestones at the base of the osteoimmunology and present the key cellular players of the bone-immune system cross-talk, including HSCs, osteoblasts, osteoclasts, bone marrow macrophages, osteomacs, T- and B-lymphocytes, dendritic cells, and neutrophils. We will also briefly describe some pathological conditions in which the bone-immune system cross-talk plays a crucial role, with the final aim to portray the state of the art in the mechanisms regulating the bone-immune system interplay, and some of the latest molecular players in the field. This is important to encourage investigation in this field, to identify new targets in the treatment of bone and immune diseases.
Collapse
|
66
|
Linnartz-Gerlach B, Bodea LG, Klaus C, Ginolhac A, Halder R, Sinkkonen L, Walter J, Colonna M, Neumann H. TREM2 triggers microglial density and age-related neuronal loss. Glia 2018; 67:539-550. [PMID: 30548312 PMCID: PMC6590266 DOI: 10.1002/glia.23563] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 10/19/2018] [Accepted: 10/19/2018] [Indexed: 12/22/2022]
Abstract
The microglial triggering receptor expressed on myeloid cells 2 (TREM2) signals via the activatory membrane adaptor molecule TYROBP. Genetic variants or mutations of TREM2 or TYROBP have been linked to inflammatory neurodegenerative diseases associated with aging. The typical aging process goes along with microglial changes and mild neuronal loss, but the exact contribution of TREM2 is still unclear. Aged TREM2 knock‐out mice showed decreased age‐related neuronal loss in the substantia nigra and the hippocampus. Transcriptomic analysis of the brains of 24 months old TREM2 knock‐out mice revealed 211 differentially expressed genes mostly downregulated and associated with complement activation and oxidative stress response pathways. Consistently, 24 months old TREM2 knock‐out mice showed lower transcription of microglial (Aif1 and Tmem119), oxidative stress markers (Inos, Cyba, and Cybb) and complement components (C1qa, C1qb, C1qc, C3, C4b, Itgam, and Itgb2), decreased microglial numbers and expression of the microglial activation marker Cd68, as well as accumulation of oxidized lipids. Cultured microglia of TREM2 knock‐out mice showed reduced phagocytosis and oxidative burst. Thus, microglial TREM2 contributes to age‐related microglial changes, phagocytic oxidative burst, and loss of neurons with possible detrimental effects during physiological aging.
Collapse
Affiliation(s)
- Bettina Linnartz-Gerlach
- Neural Regeneration, Institute of Reconstructive Neurobiology, University Hospital of Bonn, University of Bonn, Bonn, Germany
| | - Liviu-Gabriel Bodea
- Neural Regeneration, Institute of Reconstructive Neurobiology, University Hospital of Bonn, University of Bonn, Bonn, Germany.,Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, St Lucia, Queensland, Australia
| | - Christine Klaus
- Neural Regeneration, Institute of Reconstructive Neurobiology, University Hospital of Bonn, University of Bonn, Bonn, Germany
| | - Aurélien Ginolhac
- Life Sciences Research Unit, University of Luxembourg, Belvaux, Luxembourg
| | - Rashi Halder
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Lasse Sinkkonen
- Life Sciences Research Unit, University of Luxembourg, Belvaux, Luxembourg
| | - Jochen Walter
- Department of Neurology, University Bonn, Bonn, Germany
| | - Marco Colonna
- Washington University School of Medicine, Department of Pathology & Immunology, St. Louis, Missouri
| | - Harald Neumann
- Neural Regeneration, Institute of Reconstructive Neurobiology, University Hospital of Bonn, University of Bonn, Bonn, Germany
| |
Collapse
|
67
|
Chang B, Quan Q, Li Y, Qiu H, Peng J, Gu Y. Treatment of Osteoporosis, with a Focus on 2 Monoclonal Antibodies. Med Sci Monit 2018; 24:8758-8766. [PMID: 30508820 PMCID: PMC6289028 DOI: 10.12659/msm.912309] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 08/20/2018] [Indexed: 01/22/2023] Open
Abstract
Osteoporosis is a common skeletal disease characterized by bone loss and subsequent increased risk of fragility fractures. Recent advances in our mechanistic understanding of molecular communications among osteoblasts, osteoclasts, and osteocytes give insight into the important roles of the canonical Wnt/β-catenin pathway and the RANK/RANKL/OPG pathway in the process of bone remodeling. Due to the translation of the canonical Wnt/β-catenin pathway and the RANK/RANKL/OPG pathway in the regulation of osteoblasts and osteoclasts, new targets have been studied in recent years, such as sclerostin and receptor activator of NF-κB ligand (RANKL). In this review, we first introduce the signaling pathways involved in interactions among osteoblasts, osteoclasts, and osteocytes. Next, we describe clinical trials of denosumab and romosozumab, which are monoclonal antibodies that target RANKL and sclerostin, respectively. We analyze the efficacy of these drugs and provide a profile for the management of osteoporosis.
Collapse
Affiliation(s)
- Biao Chang
- Department of Laser Medicine, Chinese People’s Liberation Army General Hospital, Beijing, P.R. China
| | - Qi Quan
- Department of Orthopedics, Chinese People’s Liberation Army General Hospital, Beijing, P.R. China
| | - Yunqi Li
- Department of Laser Medicine, Chinese People’s Liberation Army General Hospital, Beijing, P.R. China
| | - Haixia Qiu
- Department of Laser Medicine, Chinese People’s Liberation Army General Hospital, Beijing, P.R. China
| | - Jiang Peng
- Department of Orthopedics, Chinese People’s Liberation Army General Hospital, Beijing, P.R. China
| | - Ying Gu
- Department of Laser Medicine, Chinese People’s Liberation Army General Hospital, Beijing, P.R. China
| |
Collapse
|
68
|
Zheng H, Cheng B, Li Y, Li X, Chen X, Zhang YW. TREM2 in Alzheimer's Disease: Microglial Survival and Energy Metabolism. Front Aging Neurosci 2018; 10:395. [PMID: 30532704 PMCID: PMC6265312 DOI: 10.3389/fnagi.2018.00395] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 11/13/2018] [Indexed: 12/16/2022] Open
Abstract
Alzheimer’s disease (AD) is the leading cause of age-related dementia among the elderly population. Recent genetic studies have identified rare variants of the gene encoding the triggering receptor expressed on myeloid cells-2 (TREM2) as significant genetic risk factors in late-onset AD (LOAD). TREM2 is specifically expressed in brain microglia and modulates microglial functions in response to key AD pathologies such as amyloid-β (Aβ) plaques and tau tangles. In this review article, we discuss recent research progress in our understanding on the role of TREM2 in microglia and its relevance to AD pathologies. In addition, we discuss evidence describing new TREM2 ligands and the role of TREM2 signaling in microglial survival and energy metabolism. A comprehensive understanding of TREM2 function in the pathogenesis of AD offers a unique opportunity to explore the potential of this microglial receptor as an alternative target in AD therapy.
Collapse
Affiliation(s)
- Honghua Zheng
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, China.,Shenzhen Research Institute, Xiamen University, Shenzhen, China
| | - Baoying Cheng
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, China
| | - Yanfang Li
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, China.,Shenzhen Research Institute, Xiamen University, Shenzhen, China
| | - Xin Li
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, China
| | - Xiaofen Chen
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, China.,Shenzhen Research Institute, Xiamen University, Shenzhen, China
| | - Yun-Wu Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, China
| |
Collapse
|
69
|
Zhou Y, Ulland TK, Colonna M. TREM2-Dependent Effects on Microglia in Alzheimer's Disease. Front Aging Neurosci 2018; 10:202. [PMID: 30038567 PMCID: PMC6046445 DOI: 10.3389/fnagi.2018.00202] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 06/13/2018] [Indexed: 12/31/2022] Open
Abstract
Alzheimer's disease (AD) is a late-onset dementia characterized by the deposition of amyloid plaques and formation of neurofibrillary tangles (NFTs) which lead to neuronal loss and cognitive deficits. Abnormal protein aggregates in the AD brain are also associated with reactive microglia and astrocytes. Whether this glial response is beneficial or detrimental in AD pathology is under debate. Microglia are the resident innate immune cells in the central nervous system (CNS) that survey the surrounding environment. Genome-wide association studies (GWAS) have identified the R47H variant of triggering receptor expressed on myeloid cell 2 (TREM2) as a risk factor for late-onset AD (LOAD) with an odds ratio of 4.5. TREM2 is an immunoreceptor primarily present on microglia in the CNS that binds to polyanionic molecules. The transmembrane domain of TREM2 signals through DAP12, an adaptor protein that contains an immunoreceptor tyrosine-based activation motif (ITAM), which mediates TREM2 signaling and promotes microglial activation and survival. In mouse models of AD, Trem2 haplodeficiency and deficiency lead to reduced microglial clustering around amyloid β (Aβ) plaques, suggesting TREM2 is required for plaque-associated microglial responses. Recently, TREM2 has been shown to enhance microglial metabolism through the mammalian target of rapamycin (mTOR) pathway. Although aberrant metabolism has long been associated with AD, not much was known regarding how metabolism in microglia might affect disease progression. In this review, we discuss the role of TREM2 and metabolism in AD pathology, highlighting how TREM2-mediated microglial metabolism modulates AD pathogenesis.
Collapse
Affiliation(s)
| | | | - Marco Colonna
- Department of Pathology and Immunology, Washington University in St. Louis, St. Louis, MO, United States
| |
Collapse
|
70
|
Dengler-Crish CM, Ball HC, Lin L, Novak KM, Cooper LN. Evidence of Wnt/β-catenin alterations in brain and bone of a tauopathy mouse model of Alzheimer's disease. Neurobiol Aging 2018; 67:148-158. [DOI: 10.1016/j.neurobiolaging.2018.03.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 03/17/2018] [Accepted: 03/17/2018] [Indexed: 10/17/2022]
|
71
|
Park-Min KH. Mechanisms involved in normal and pathological osteoclastogenesis. Cell Mol Life Sci 2018; 75:2519-2528. [PMID: 29670999 PMCID: PMC9809143 DOI: 10.1007/s00018-018-2817-9] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 03/29/2018] [Accepted: 04/13/2018] [Indexed: 01/05/2023]
Abstract
Osteoclasts are bone-resorbing cells that play an essential role in bone remodeling. Defects in osteoclasts result in unbalanced bone remodeling and are linked to many bone diseases including osteoporosis, rheumatoid arthritis, primary bone cancer, and skeletal metastases. Receptor activator of NF-kappaB ligand (RANKL) is a classical inducer of osteoclast formation. In the presence of macrophage-colony-stimulating factor, RANKL and co-stimulatory signals synergistically regulate osteoclastogenesis. However, recent discoveries of alternative pathways for RANKL-independent osteoclastogenesis have led to a reassessment of the traditional mechanisms that regulate osteoclast formation. In this review, we provide an overview of signaling pathways and other regulatory elements governing osteoclastogenesis. We also identify how osteoclastogenesis is altered in pathological conditions and discuss therapeutic targets in osteoclasts for the treatment of skeletal diseases.
Collapse
Affiliation(s)
- Kyung-Hyun Park-Min
- Arthritis and Tissue Degeneration Program, David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, 535 East 70th Street, New York, 10021, NY, USA.
- Department of Medicine, Weill Cornell Medical College, New York, 10065, NY, USA.
| |
Collapse
|
72
|
Pereira M, Petretto E, Gordon S, Bassett JHD, Williams GR, Behmoaras J. Common signalling pathways in macrophage and osteoclast multinucleation. J Cell Sci 2018; 131:131/11/jcs216267. [PMID: 29871956 DOI: 10.1242/jcs.216267] [Citation(s) in RCA: 126] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Macrophage cell fusion and multinucleation are fundamental processes in the formation of multinucleated giant cells (MGCs) in chronic inflammatory disease and osteoclasts in the regulation of bone mass. However, this basic cell phenomenon is poorly understood despite its pathophysiological relevance. Granulomas containing multinucleated giant cells are seen in a wide variety of complex inflammatory disorders, as well as in infectious diseases. Dysregulation of osteoclastic bone resorption underlies the pathogenesis of osteoporosis and malignant osteolytic bone disease. Recent reports have shown that the formation of multinucleated giant cells and osteoclast fusion display a common molecular signature, suggesting shared genetic determinants. In this Review, we describe the background of cell-cell fusion and the similar origin of macrophages and osteoclasts. We specifically focus on the common pathways involved in osteoclast and MGC fusion. We also highlight potential approaches that could help to unravel the core mechanisms underlying bone and granulomatous disorders in humans.
Collapse
Affiliation(s)
- Marie Pereira
- Centre for Inflammatory Disease, Imperial College London, London W12 0NN, UK
| | - Enrico Petretto
- Duke-NUS Medical School, Singapore 169857, Republic of Singapore
| | - Siamon Gordon
- Graduate Institute of Biomedical Sciences, Chang Gung University, Taoyuan City 33302, Taiwan.,Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - J H Duncan Bassett
- Molecular Endocrinology Laboratory, Department of Medicine, Imperial College London, London W12 0NN, UK
| | - Graham R Williams
- Molecular Endocrinology Laboratory, Department of Medicine, Imperial College London, London W12 0NN, UK
| | - Jacques Behmoaras
- Centre for Inflammatory Disease, Imperial College London, London W12 0NN, UK
| |
Collapse
|
73
|
Dengler-Crish CM, Smith MA, Wilson GN. Early Evidence of Low Bone Density and Decreased Serotonergic Synthesis in the Dorsal Raphe of a Tauopathy Model of Alzheimer's Disease. J Alzheimers Dis 2018; 55:1605-1619. [PMID: 27814296 PMCID: PMC5181667 DOI: 10.3233/jad-160658] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Reduced bone mineral density (BMD) and its clinical sequelae, osteoporosis, occur at a much greater rate in patients with Alzheimer’s disease (AD), often emerging early in the disease before significant cognitive decline is seen. Reduced BMD translates to increased bone fracture risk, decreased quality of life, and increased mortality for AD patients. However, the mechanism responsible for this observation is unclear. We hypothesize that bone loss is an additional component of an AD prodrome-changes that emerge prior to dementia and are mediated by dysfunction of the central serotonergic pathways. We characterized the skeletal phenotype of htau mice that express human forms of the microtubule-associated protein tau that become pathologically hyperphosphorylated in AD. Using radiographic densitometry, we measured BMD in female and male htau mice from 2–6 months of age–time-points prior to the presence of significant tauopathy in the hippocampal/entorhinal regions characteristic of this model. We found a significantly reduced BMD phenotype in htau mice that was most pronounced in males. Using western blotting and immunofluorescence, we showed overall reduced tryptophan hydroxylase (TPH) protein in htau brainstem and a 70% reduction in TPH-positive cells in the dorsal raphe nucleus (DRN)–a pivotal structure in the regulation of the adult skeleton. Elevations of hyperphosphorylated tau (ptau) proteins were also measured in brainstem, and co-labeled immunofluorescence studies showed presence of ptau in TPH-positive cells of the DRN as early as 4 months of age in htau mice. Together, these findings demonstrate that reduced BMD occurs earlier than overt degeneration in a tau-based AD model and that pathological changes in tau phosphorylation occur in the serotonin-producing neurons of the brainstem raphe in these mice. This illuminates a need to define a mechanistic relationship between bone loss and serotonergic deficits in early AD.
Collapse
Affiliation(s)
| | - Matthew A Smith
- Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA.,Integrated Pharmaceutical Medicine Program, Northeast Ohio Medical University, Rootstown, OH, USA
| | - Gina N Wilson
- Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA.,Biomedical Sciences Graduate Program, Kent State University, Kent, OH, USA
| |
Collapse
|
74
|
Raha AA, Henderson JW, Stott SRW, Vuono R, Foscarin S, Friedland RP, Zaman SH, Raha-Chowdhury R. Neuroprotective Effect of TREM-2 in Aging and Alzheimer's Disease Model. J Alzheimers Dis 2018; 55:199-217. [PMID: 27662313 DOI: 10.3233/jad-160663] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Neuroinflammation and activation of innate immunity are early events in neurodegenerative diseases including Alzheimer's disease (AD). Recently, a rare mutation in the gene Triggering receptor expressed on myeloid cells 2 (TREM2) has been associated with a substantial increase in the risk of developing late onset AD. To uncover the molecular mechanisms underlying this association, we investigated the RNA and protein expression of TREM2 in APP/PS1 transgenic mice. Our findings suggest that TREM2 not only plays a critical role in inflammation, but is also involved in neuronal cell survival and in neurogenesis. We have shown that TREM2 is a soluble protein transported by macrophages through ventricle walls and choroid plexus, and then enters the brain parenchyma via radial glial cells. TREM2 protein is essential for neuroplasticity and myelination. During the late stages of life, a lack of TREM2 protein may accelerate aging processes and neuronal cell loss and reduce microglial activity, ultimately leading to neuroinflammation. As inflammation plays a major role in neurodegenerative diseases, a lack of TREM2 could be a missing link between immunomodulation and neuroprotection.
Collapse
Affiliation(s)
- Animesh Alexander Raha
- John Van Geest Centre for Brain Repair, Department of Clinical Neuroscience, University of Cambridge, Cambridge, UK
| | - James W Henderson
- John Van Geest Centre for Brain Repair, Department of Clinical Neuroscience, University of Cambridge, Cambridge, UK
| | - Simon R W Stott
- John Van Geest Centre for Brain Repair, Department of Clinical Neuroscience, University of Cambridge, Cambridge, UK
| | - Romina Vuono
- John Van Geest Centre for Brain Repair, Department of Clinical Neuroscience, University of Cambridge, Cambridge, UK
| | - Simona Foscarin
- John Van Geest Centre for Brain Repair, Department of Clinical Neuroscience, University of Cambridge, Cambridge, UK
| | | | - Shahid H Zaman
- Cambridge Intellectual & Developmental Disabilities Research Group, Department of Psychiatry, University of Cambridge, Cambridge, UK
| | - Ruma Raha-Chowdhury
- John Van Geest Centre for Brain Repair, Department of Clinical Neuroscience, University of Cambridge, Cambridge, UK
| |
Collapse
|
75
|
Canalis E. MANAGEMENT OF ENDOCRINE DISEASE: Novel anabolic treatments for osteoporosis. Eur J Endocrinol 2018; 178:R33-R44. [PMID: 29113980 PMCID: PMC5819362 DOI: 10.1530/eje-17-0920] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 11/07/2017] [Accepted: 11/07/2017] [Indexed: 12/15/2022]
Abstract
Skeletal anabolic agents enhance bone formation, which is determined by the number and function of osteoblasts. Signals that influence the differentiation and function of cells of the osteoblast lineage play a role in the mechanism of action of anabolic agents in the skeleton. Wnts induce the differentiation of mesenchymal stem cells toward osteoblasts, and insulin-like growth factor I (IGF-I) enhances the function of mature osteoblasts. The activity of Wnt and IGF-I is controlled by proteins that bind to the growth factor or to its receptors. Sclerostin is a Wnt antagonist that binds to Wnt co-receptors and prevents Wnt signal activation. Teriparatide, a 1-34 amino terminal fragment of parathyroid hormone (PTH), and abaloparatide, a modified 1-34 amino terminal fragment of PTH-related peptide (PTHrp), induce IGF-I, increase bone mineral density (BMD), reduce the incidence of vertebral and non-vertebral fractures and are approved for the treatment of postmenopausal osteoporosis. Romosozumab, a humanized anti-sclerostin antibody, increases bone formation, decreases bone resorption, increases BMD and reduces the incidence of vertebral fractures. An increased incidence of cardiovascular events has been associated with romosozumab, which is yet to be approved for the treatment of osteoporosis. In conclusion, cell and molecular studies have formed the foundation for the development of new anabolic therapies for osteoporosis with proven efficacy on the incidence of new fractures.
Collapse
Affiliation(s)
- Ernesto Canalis
- Departments of Orthopaedic Surgery and Medicine, UConn Musculoskeletal Institute, UConn Health, Farmington, Connecticut, USA
| |
Collapse
|
76
|
Mecca C, Giambanco I, Donato R, Arcuri C. Microglia and Aging: The Role of the TREM2-DAP12 and CX3CL1-CX3CR1 Axes. Int J Mol Sci 2018; 19:E318. [PMID: 29361745 PMCID: PMC5796261 DOI: 10.3390/ijms19010318] [Citation(s) in RCA: 136] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 01/17/2018] [Accepted: 01/18/2018] [Indexed: 12/21/2022] Open
Abstract
Depending on the species, microglial cells represent 5-20% of glial cells in the adult brain. As the innate immune effector of the brain, microglia are involved in several functions: regulation of inflammation, synaptic connectivity, programmed cell death, wiring and circuitry formation, phagocytosis of cell debris, and synaptic pruning and sculpting of postnatal neural circuits. Moreover, microglia contribute to some neurodevelopmental disorders such as Nasu-Hakola disease (NHD), and to aged-associated neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), and others. There is evidence that human and rodent microglia may become senescent. This event determines alterations in the microglia activation status, associated with a chronic inflammation phenotype and with the loss of neuroprotective functions that lead to a greater susceptibility to the neurodegenerative diseases of aging. In the central nervous system (CNS), Triggering Receptor Expressed on Myeloid Cells 2-DNAX activation protein 12 (TREM2-DAP12) is a signaling complex expressed exclusively in microglia. As a microglial surface receptor, TREM2 interacts with DAP12 to initiate signal transduction pathways that promote microglial cell activation, phagocytosis, and microglial cell survival. Defective TREM2-DAP12 functions play a central role in the pathogenesis of several diseases. The CX3CL1 (fractalkine)-CX3CR1 signaling represents the most important communication channel between neurons and microglia. The expression of CX3CL1 in neurons and of its receptor CX3CR1 in microglia determines a specific interaction, playing fundamental roles in the regulation of the maturation and function of these cells. Here, we review the role of the TREM2-DAP12 and CX3CL1-CX3CR1 axes in aged microglia and the involvement of these pathways in physiological CNS aging and in age-associated neurodegenerative diseases.
Collapse
Affiliation(s)
- Carmen Mecca
- Department of Experimental Medicine, Perugia Medical School, University of Perugia, Piazza Lucio Severi 1, 06132 Perugia, Italy.
| | - Ileana Giambanco
- Department of Experimental Medicine, Perugia Medical School, University of Perugia, Piazza Lucio Severi 1, 06132 Perugia, Italy.
| | - Rosario Donato
- Department of Experimental Medicine, Perugia Medical School, University of Perugia, Piazza Lucio Severi 1, 06132 Perugia, Italy.
- Centro Universitario per la Ricerca sulla Genomica Funzionale, Perugia Medical School, University of Perugia, Piazza Lucio Severi 1, 06132 Perugia, Italy.
| | - Cataldo Arcuri
- Department of Experimental Medicine, Perugia Medical School, University of Perugia, Piazza Lucio Severi 1, 06132 Perugia, Italy.
| |
Collapse
|
77
|
Marino S, Bishop RT, Logan JG, Mollat P, Idris AI. Pharmacological evidence for the bone-autonomous contribution of the NFκB/β-catenin axis to breast cancer related osteolysis. Cancer Lett 2017; 410:180-190. [DOI: 10.1016/j.canlet.2017.09.034] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 09/18/2017] [Accepted: 09/21/2017] [Indexed: 01/21/2023]
|
78
|
Zhang W, Lu W, Ananthan S, Suto MJ, Li Y. Discovery of novel frizzled-7 inhibitors by targeting the receptor's transmembrane domain. Oncotarget 2017; 8:91459-91470. [PMID: 29207657 PMCID: PMC5710937 DOI: 10.18632/oncotarget.20665] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 06/28/2017] [Indexed: 02/06/2023] Open
Abstract
Frizzled (Fzd) proteins are seven transmembrane receptors that belong to a novel and separated family of G-protein-coupled receptors (GPCRs). The Fzd receptors can respond to Wnt proteins to activate the canonical β-catenin pathway which is important for both initiation and progression of cancers. Disruption of the Wnt/β-catenin signal thus represents an opportunity for rational cancer prevention and therapy. Of the 10 members of the Fzd family, Fzd7 is the most important member involved in cancer development and progression. In the present studies, we applied structure-based virtual screening targeting the transmembrane domain (TMD) of Fzd7 to select compounds that could potentially bind to the Fzd7-TMD and block the Wnt/Fzd7 signaling and further evaluated them in biological assays. Six small molecule compounds were confirmed as Fzd7 inhibitors. The best hit, SRI37892, significantly blocked the Wnt/Fzd7 signaling with IC50 values in the sub-micromolar range and inhibited cancer cell proliferation with IC50 values around 2 μM. Our results provide the first proof of concept of targeting Fzd-TMD for the development of Wnt/Fzd modulators. The identified small molecular Fzd7 inhibitors can serve as a useful tool for studying the regulation mechanism(s) of Wnt/Fzd7 signaling as well as a starting point for the development of cancer therapeutic agents.
Collapse
Affiliation(s)
- Wei Zhang
- Department of Chemistry, Drug Discovery Division, Southern Research Institute, Birmingham, Alabama 35205, United States
| | - Wenyan Lu
- Department of Oncology, Drug Discovery Division, Southern Research Institute, Birmingham, Alabama 35205, United States
| | - Subramaniam Ananthan
- Department of Chemistry, Drug Discovery Division, Southern Research Institute, Birmingham, Alabama 35205, United States
| | - Mark J Suto
- Department of Chemistry, Drug Discovery Division, Southern Research Institute, Birmingham, Alabama 35205, United States
| | - Yonghe Li
- Department of Oncology, Drug Discovery Division, Southern Research Institute, Birmingham, Alabama 35205, United States
| |
Collapse
|
79
|
Jay TR, von Saucken VE, Landreth GE. TREM2 in Neurodegenerative Diseases. Mol Neurodegener 2017; 12:56. [PMID: 28768545 PMCID: PMC5541421 DOI: 10.1186/s13024-017-0197-5] [Citation(s) in RCA: 252] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 07/20/2017] [Indexed: 12/12/2022] Open
Abstract
TREM2 variants have been identified as risk factors for Alzheimer's disease (AD) and other neurodegenerative diseases (NDDs). Because TREM2 encodes a receptor exclusively expressed on immune cells, identification of these variants conclusively demonstrates that the immune response can play an active role in the pathogenesis of NDDs. These TREM2 variants also confer the highest risk for developing Alzheimer's disease of any risk factor identified in nearly two decades, suggesting that understanding more about TREM2 function could provide key insights into NDD pathology and provide avenues for novel immune-related NDD biomarkers and therapeutics. The expression, signaling and function of TREM2 in NDDs have been extensively investigated in an effort to understand the role of immune function in disease pathogenesis and progression. We provide a comprehensive review of our current understanding of TREM2 biology, including new insights into the regulation of TREM2 expression, and TREM2 signaling and function across NDDs. While many open questions remain, the current body of literature provides clarity on several issues. While it is still often cited that TREM2 expression is decreased by pro-inflammatory stimuli, it is now clear that this is true in vitro, but inflammatory stimuli in vivo almost universally increase TREM2 expression. Likewise, while TREM2 function is classically described as promoting an anti-inflammatory phenotype, more than half of published studies demonstrate a pro-inflammatory role for TREM2, suggesting that its role in inflammation is much more complex. Finally, these components of TREM2 biology are applied to a discussion of how TREM2 impacts NDD pathologies and the latest assessment of how these findings might be applied to immune-directed clinical biomarkers and therapeutics.
Collapse
Affiliation(s)
- Taylor R. Jay
- Department of Neurosciences, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106 USA
| | - Victoria E. von Saucken
- Department of Neurosciences, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106 USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, 320 W 15th Street, Indianapolis, IN 46202 USA
| | - Gary E. Landreth
- Department of Neurosciences, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106 USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, 320 W 15th Street, Indianapolis, IN 46202 USA
| |
Collapse
|
80
|
Disease Progression-Dependent Effects of TREM2 Deficiency in a Mouse Model of Alzheimer's Disease. J Neurosci 2017; 37:637-647. [PMID: 28100745 DOI: 10.1523/jneurosci.2110-16.2016] [Citation(s) in RCA: 297] [Impact Index Per Article: 42.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 11/30/2016] [Accepted: 12/05/2016] [Indexed: 11/21/2022] Open
Abstract
Neuroinflammation is an important contributor to Alzheimer's disease (AD) pathogenesis, as underscored by the recent identification of immune-related genetic risk factors for AD, including coding variants in the gene TREM2 (triggering receptor expressed on myeloid cells 2). Understanding TREM2 function promises to provide important insights into how neuroinflammation contributes to AD pathology. However, studies so far have produced seemingly conflicting results, with reports that amyloid pathology can be both decreased and increased in TREM2-deficient AD mouse models. In this study, we unify these previous findings by demonstrating that TREM2 deficiency ameliorates amyloid pathology early, but exacerbates it late in disease progression in the APPPS1-21 mouse model of AD. We also demonstrate that TREM2 deficiency decreases plaque-associated myeloid cell accumulation by reducing cell proliferation, specifically late in pathology. In addition, TREM2 deficiency reduces myeloid cell internalization of amyloid throughout pathology, but decreases inflammation-related gene transcript levels selectively late in disease progression. Together, these results suggest that TREM2 plays distinct functional roles at different stages in AD pathology. SIGNIFICANCE STATEMENT Alzheimer's disease (AD) is a devastating neurodegenerative disorder and there are currently no effective treatments that modify disease progression. However, the recent identification of genetic risk factors for AD promises to provide new insight into AD biology and possible new therapeutic targets. Among these risk factors, variants in the gene TREM2 (triggering receptor expressed on myeloid cells 2) confer greatly elevated risk for developing the disease. We demonstrate that TREM2 deficiency has opposing effects on AD-related pathologies at early and late stages of disease progression, unifying previous work in the field. In addition, we examine how TREM2 affects the function of the brain immune cell populations in which it is expressed throughout disease progression to understand possible mechanisms underlying its differential impacts on pathology.
Collapse
|
81
|
Ma L, Zhao S, Li Z. Effects of parathyroidectomy on bone metabolism in haemodialysis patients with secondary hyperparathyroidism. Scandinavian Journal of Clinical and Laboratory Investigation 2017; 77:527-534. [PMID: 28741963 DOI: 10.1080/00365513.2017.1354256] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
OBJECTIVE To evaluate the outcome of bone metabolism and bone mineral density (BMD) in haemodialysis patients after parathyroidectomy (PTX). METHODS A total of 31 haemodialysis patients with secondary hyperparathyroidism (SHPT) were treated with PTX. BMD of lumbar spine (LS) and femoral neck (FN) was determined by dual energy X-ray absorptiometry. RESULTS Parathyroidectomy ledds to significant decrease of serum β-crosslaps (β-CTX), osteocalcin (OC) and procollagen type I amino-terminal propeptide (PINP) while serum sclerostin (SOST) increased after surgery. BMD was markedly improved in both LS and FN after PTX. Z-scores analysis further confirmed that PTX significantly benefited bone metabolism in haemodialysis patients, which well correlated with the improvement of serum iPTH and OC. CONCLUSIONS Parathyroidectomy leads to significant improvement of serum OC, PINP, β-CTX and SOST, which may beneficially modify calcium-phosphorus metabolism and BMD in haemodialysis patients with SHPT.
Collapse
Affiliation(s)
- Lijie Ma
- a Department of Nephrology , Beijing Chaoyang Hospital, Capital Medical University , Beijing , China
| | - Sumei Zhao
- a Department of Nephrology , Beijing Chaoyang Hospital, Capital Medical University , Beijing , China
| | - Zhongxin Li
- b Department of Nephrology , Beijing Lu He Hospital, Capital Medical University , Beijing , China
| |
Collapse
|
82
|
Joeng KS, Lee YC, Lim J, Chen Y, Jiang MM, Munivez E, Ambrose C, Lee BH. Osteocyte-specific WNT1 regulates osteoblast function during bone homeostasis. J Clin Invest 2017. [PMID: 28628032 DOI: 10.1172/jci92617] [Citation(s) in RCA: 125] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Mutations in WNT1 cause osteogenesis imperfecta (OI) and early-onset osteoporosis, identifying it as a key Wnt ligand in human bone homeostasis. However, how and where WNT1 acts in bone are unclear. To address this mechanism, we generated late-osteoblast-specific and osteocyte-specific WNT1 loss- and gain-of-function mouse models. Deletion of Wnt1 in osteocytes resulted in low bone mass with spontaneous fractures similar to that observed in OI patients. Conversely, Wnt1 overexpression from osteocytes stimulated bone formation by increasing osteoblast number and activity, which was due in part to activation of mTORC1 signaling. While antiresorptive therapy is the mainstay of OI treatment, it has limited efficacy in WNT1-related OI. In this study, anti-sclerostin antibody (Scl-Ab) treatment effectively improved bone mass and dramatically decreased fracture rate in swaying mice, a model of global Wnt1 loss. Collectively, our data suggest that WNT1-related OI and osteoporosis are caused in part by decreased mTORC1-dependent osteoblast function resulting from loss of WNT1 signaling in osteocytes. As such, this work identifies an anabolic function of osteocytes as a source of Wnt in bone development and homoeostasis, complementing their known function as targets of Wnt signaling in regulating osteoclastogenesis. Finally, this study suggests that Scl-Ab is an effective genotype-specific treatment option for WNT1-related OI and osteoporosis.
Collapse
Affiliation(s)
- Kyu Sang Joeng
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Yi-Chien Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Joohyun Lim
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Yuqing Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Ming-Ming Jiang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Elda Munivez
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Catherine Ambrose
- Department of Orthopedic Surgery, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Brendan H Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| |
Collapse
|
83
|
Kleinberger G, Brendel M, Mracsko E, Wefers B, Groeneweg L, Xiang X, Focke C, Deußing M, Suárez-Calvet M, Mazaheri F, Parhizkar S, Pettkus N, Wurst W, Feederle R, Bartenstein P, Mueggler T, Arzberger T, Knuesel I, Rominger A, Haass C. The FTD-like syndrome causing TREM2 T66M mutation impairs microglia function, brain perfusion, and glucose metabolism. EMBO J 2017; 36:1837-1853. [PMID: 28559417 DOI: 10.15252/embj.201796516] [Citation(s) in RCA: 146] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 04/21/2017] [Accepted: 04/27/2017] [Indexed: 12/31/2022] Open
Abstract
Genetic variants in the triggering receptor expressed on myeloid cells 2 (TREM2) increase the risk for several neurodegenerative diseases including Alzheimer's disease and frontotemporal dementia (FTD). Homozygous TREM2 missense mutations, such as p.T66M, lead to the FTD-like syndrome, but how they cause pathology is unknown. Using CRISPR/Cas9 genome editing, we generated a knock-in mouse model for the disease-associated Trem2 p.T66M mutation. Consistent with a loss-of-function mutation, we observe an intracellular accumulation of immature mutant Trem2 and reduced generation of soluble Trem2 similar to patients with the homozygous p.T66M mutation. Trem2 p.T66M knock-in mice show delayed resolution of inflammation upon in vivo lipopolysaccharide stimulation and cultured macrophages display significantly reduced phagocytic activity. Immunohistochemistry together with in vivo TSPO small animal positron emission tomography (μPET) demonstrates an age-dependent reduction in microglial activity. Surprisingly, perfusion magnetic resonance imaging and FDG-μPET imaging reveal a significant reduction in cerebral blood flow and brain glucose metabolism. Thus, we demonstrate that a TREM2 loss-of-function mutation causes brain-wide metabolic alterations pointing toward a possible function of microglia in regulating brain glucose metabolism.
Collapse
Affiliation(s)
- Gernot Kleinberger
- Biomedical Center (BMC), Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Matthias Brendel
- Department of Nuclear Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Eva Mracsko
- NORD Discovery & Translational Area, Roche Pharmaceutical Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Benedikt Wefers
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Institute of Developmental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Linda Groeneweg
- NORD Discovery & Translational Area, Roche Pharmaceutical Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Xianyuan Xiang
- Biomedical Center (BMC), Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Carola Focke
- Department of Nuclear Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Maximilian Deußing
- Department of Nuclear Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Marc Suárez-Calvet
- Biomedical Center (BMC), Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany.,German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
| | - Fargol Mazaheri
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
| | - Samira Parhizkar
- Biomedical Center (BMC), Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Nadine Pettkus
- Biomedical Center (BMC), Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Wolfgang Wurst
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.,German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Institute of Developmental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany.,Technische Universität München, Freising-Weihenstephan, Germany
| | - Regina Feederle
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.,German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Helmholtz Center Munich, German Research Center for Environmental Health, Institute for Diabetes and Obesity, Core Facility Monoclonal Antibody Development, Munich, Germany
| | - Peter Bartenstein
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.,Department of Nuclear Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Thomas Mueggler
- NORD Discovery & Translational Area, Roche Pharmaceutical Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Thomas Arzberger
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Center for Neuropathology and Prion Research, Ludwig-Maximilians-Universität München, Munich, Germany.,Department of Psychiatry and Psychotherapy, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Irene Knuesel
- NORD Discovery & Translational Area, Roche Pharmaceutical Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Axel Rominger
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.,Department of Nuclear Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Christian Haass
- Biomedical Center (BMC), Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany .,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.,German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
| |
Collapse
|
84
|
Kober DL, Brett TJ. TREM2-Ligand Interactions in Health and Disease. J Mol Biol 2017; 429:1607-1629. [PMID: 28432014 DOI: 10.1016/j.jmb.2017.04.004] [Citation(s) in RCA: 137] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 04/06/2017] [Accepted: 04/10/2017] [Indexed: 01/04/2023]
Abstract
The protein triggering receptor expressed on myeloid cells-2 (TREM2) is an immunomodulatory receptor with a central role in myeloid cell activation and survival. In recent years, the importance of TREM2 has been highlighted by the identification of coding variants that increase risk for Alzheimer's disease and other neurodegenerative diseases. Animal studies have further shown the importance of TREM2 in neurodegenerative and other inflammatory disease models including chronic obstructive pulmonary disease, multiple sclerosis, and stroke. A mechanistic understanding of TREM2 function remains elusive, however, due in part to the absence of conclusive information regarding the identity of endogenous TREM2 ligands. While many TREM2 ligands have been proposed, their physiological role and mechanism of engagement remain to be determined. In this review, we highlight the suggested roles of TREM2 in these diseases and the recent advances in our understanding of TREM2 and discuss putative TREM2-ligand interactions and their potential roles in signaling during health and disease. We develop a model based on the TREM2 structure to explain how different TREM2 ligands might interact with the receptor and how disease risk variants may alter ligand interactions. Finally, we propose future experimental directions to establish the role and importance of these different interactions on TREM2 function.
Collapse
Affiliation(s)
- Daniel L Kober
- Molecular Microbiology and Microbial Pathogenesis Program, Washington University School of Medicine, St. Louis, MO 63110, USA; Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Tom J Brett
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA.
| |
Collapse
|
85
|
Matsumoto Y, Larose J, Kent OA, Lim M, Changoor A, Zhang L, Storozhuk Y, Mao X, Grynpas MD, Cong F, Rottapel R. RANKL coordinates multiple osteoclastogenic pathways by regulating expression of ubiquitin ligase RNF146. J Clin Invest 2017; 127:1303-1315. [PMID: 28287403 DOI: 10.1172/jci90527] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 01/17/2017] [Indexed: 12/12/2022] Open
Abstract
Bone undergoes continuous remodeling due to balanced bone formation and resorption mediated by osteoblasts and osteoclasts, respectively. Osteoclasts arise from the macrophage lineage, and their differentiation is dependent on RANKL, a member of the TNF family of cytokines. Here, we have provided evidence that RANKL controls the expression of 3BP2, an adapter protein that is required for activation of SRC tyrosine kinase and simultaneously coordinates the attenuation of β-catenin, both of which are required to execute the osteoclast developmental program. We found that RANKL represses the transcription of the E3 ubiquitin ligase RNF146 through an NF-κB-related inhibitory element in the RNF146 promoter. RANKL-mediated suppression of RNF146 results in the stabilization of its substrates, 3BP2 and AXIN1, which consequently triggers the activation of SRC and attenuates the expression of β-catenin, respectively. Depletion of RNF146 caused hypersensitivity to LPS-induced TNF-α production in vivo. RNF146 thus acts as an inhibitory switch to control osteoclastogenesis and cytokine production and may be a control point underlying the pathogenesis of chronic inflammatory diseases.
Collapse
|
86
|
Liu C, Liu Y, Zhang W, Liu X. Screening for potential genes associated with bone overgrowth after mid-shaft femur fracture in a rat model. J Orthop Surg Res 2017; 12:8. [PMID: 28095896 PMCID: PMC5240322 DOI: 10.1186/s13018-017-0510-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 12/30/2016] [Indexed: 01/15/2023] Open
Abstract
Background We investigated the underlying molecular mechanisms of bone overgrowth after femoral fracture by using high-throughput bioinformatics approaches. Methods The gene expression profile of GSE3298 (accession number) was obtained from the Gene Expression Omnibus database. Sixteen femoral growth plate samples, including nine samples without fracture and seven fracture samples for seven time points, were used for analysis. The Limma package was applied to identify differentially expressed genes (DEGs) between fractured and intact samples. The DAVID online tool was used for Gene ontology functional and pathway enrichment analysis. A protein-protein interaction (PPI) network established by String software was used to identify interactions between significant DEGs, and network modules were detected using plug-in MCODE. Additionally, a transcription regulatory network was constructed based on the ENCODE Project and PPI network. Results A total of 680 DEGs were screened in fractured femoral growth plate samples compared with controls, including 238 up- and 442 down-regulated genes. These DEGs were significantly involved in the calcium signaling pathway and cancer pathway. A PPI network was constructed with 167 nodes and 233 edges, and module analysis demonstrated that CCL2, CSF2, NOS2, and DLC1 may stimulate bone overgrowth after femoral fracture via anti-apoptosis-related functions. A transcription regulatory network was constructed with 387 interacting pairs, and overlapping nodes were significantly enriched in intracellular signaling cascade and regulation of cell proliferation, among others. Conclusions Bone overgrowth was associated with changes in the expression of identified DEGs such as CCL2, NOS2, CSF2, and DLC1 in the femoral head. They may be important in regulating bone overgrowth via the anti-apoptosis of osteoblasts. Electronic supplementary material The online version of this article (doi:10.1186/s13018-017-0510-6) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Chibing Liu
- The Second Hospital of Jilin University, Ziqiang St 218 Nan Guan District, Changchun, 130041, China
| | | | - Weizhong Zhang
- China-Japan Union Hospital of Jilin University, Changchun, Jilin, 130000, China
| | - Xiuxin Liu
- The Six Affiliated Hospital of Xinjiang Medical University Medical Examination Center, Autonomous Region, Five Star South Road, No. 39, Urumqi City, Xinjiang Uygur, 830002, China.
| |
Collapse
|
87
|
TREM2 Promotes Microglial Survival by Activating Wnt/β-Catenin Pathway. J Neurosci 2017; 37:1772-1784. [PMID: 28077724 DOI: 10.1523/jneurosci.2459-16.2017] [Citation(s) in RCA: 199] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 12/26/2016] [Accepted: 01/05/2017] [Indexed: 11/21/2022] Open
Abstract
Triggering Receptor Expressed on Myeloid cells 2 (TREM2), which is expressed on myeloid cells including microglia in the CNS, has recently been identified as a risk factor for Alzheimer's disease (AD). TREM2 transmits intracellular signals through its transmembrane binding partner DNAX-activating protein 12 (DAP12). Homozygous mutations inactivating TREM2 or DAP12 lead to Nasu-Hakola disease; however, how AD risk-conferring variants increase AD risk is not clear. To elucidate the signaling pathways underlying reduced TREM2 expression or loss of function in microglia, we respectively knocked down and knocked out the expression of TREM2 in in vitro and in vivo models. We found that TREM2 deficiency reduced the viability and proliferation of primary microglia, reduced microgliosis in Trem2-/- mouse brains, induced cell cycle arrest at the G1/S checkpoint, and decreased the stability of β-catenin, a key component of the canonical Wnt signaling pathway responsible for maintaining many biological processes, including cell survival. TREM2 stabilized β-catenin by inhibiting its degradation via the Akt/GSK3β signaling pathway. More importantly, treatment with Wnt3a, LiCl, or TDZD-8, which activates the β-catenin-mediated Wnt signaling pathway, rescued microglia survival and microgliosis in Trem2-/- microglia and/or in Trem2-/- mouse brain. Together, our studies demonstrate a critical role of TREM2-mediated Wnt/β-catenin pathway in microglial viability and suggest that modulating this pathway therapeutically may help to combat the impaired microglial survival and microgliosis associated with AD.SIGNIFICANCE STATEMENT Mutations in the TREM2 (Triggering Receptor Expressed on Myeloid cells 2) gene are associated with increased risk for Alzheimer's disease (AD) with effective sizes comparable to that of the apolipoprotein E (APOE) ε4 allele, making it imperative to understand the molecular pathway(s) underlying TREM2 function in microglia. Our findings shed new light on the relationship between TREM2/DNAX-activating protein 12 (DAP12) signaling and Wnt/β-catenin signaling and provide clues as to how reduced TREM2 function might impair microglial survival in AD pathogenesis. We demonstrate that TREM2 promotes microglial survival by activating the Wnt/β-catenin signaling pathway and that it is possible to restore Wnt/β-catenin signaling when TREM2 activity is disrupted or reduced. Therefore, we demonstrate the potential for manipulating the TREM2/β-catenin signaling pathway for the treatment of AD.
Collapse
|
88
|
Yang Z, Kim S, Mahajan S, Zamani A, Faccio R. Phospholipase Cγ1 (PLCγ1) Controls Osteoclast Numbers via Colony-stimulating Factor 1 (CSF-1)-dependent Diacylglycerol/β-Catenin/CyclinD1 Pathway. J Biol Chem 2016; 292:1178-1186. [PMID: 27941021 DOI: 10.1074/jbc.m116.764928] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 12/09/2016] [Indexed: 01/22/2023] Open
Abstract
Phospholipases Cγ (PLCγ) 1 and 2 are a class of highly homologous enzymes modulating a variety of cellular pathways through production of inositol 1,4,5-trisphosphate and diacylglycerol (DAG). Our previous studies demonstrated the importance of PLCγ2 in osteoclast (OC) differentiation by modulating inositol 1,4,5-trisphosphate-mediated calcium oscillations and the up-regulation of the transcription factor NFATc1. Surprisingly, despite being expressed throughout osteoclastogenesis, PLCγ1 did not compensate for PLCγ2 deficiency. Because both isoforms are activated during osteoclastogenesis, it is plausible that PLCγ1 modulates OC development independently of PLCγ2. Here, we utilized PLCγ1-specific shRNAs to delete PLCγ1 in OC precursors derived from wild type (WT) mice. Differently from PLCγ2, we found that PLCγ1 shRNA significantly suppresses OC differentiation by limiting colony-stimulating factor 1 (CSF-1)-dependent proliferation and β-catenin/cyclinD1 levels. Confirming the specificity toward CSF-1 signaling, PLCγ1 is recruited to the CSF-1 receptor following exposure to the cytokine. To understand how PLCγ1 controls cell proliferation, we turned to its downstream effector, DAG. By utilizing cells lacking the DAG kinase ζ, which have increased DAG levels, we demonstrate that DAG modulates CSF-1-dependent proliferation and β-catenin/cyclinD1 levels in OC precursors. Most importantly, the proliferation and osteoclastogenesis defects observed in the absence of PLCγ1 are normalized in PLCγ1/DAG kinase ζ double null cells. Taken together, our study shows that PLCγ1 controls OC numbers via a CSF-1-dependent DAG/β-catenin/cyclinD1 pathway.
Collapse
Affiliation(s)
- Zhengfeng Yang
- From the Department of Orthopaedics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Seokho Kim
- From the Department of Orthopaedics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Sahil Mahajan
- From the Department of Orthopaedics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Ali Zamani
- From the Department of Orthopaedics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Roberta Faccio
- From the Department of Orthopaedics, Washington University School of Medicine, St. Louis, Missouri 63110
| |
Collapse
|
89
|
Han J, Wang M, Ren M, Lou H. Contributions of triggering-receptor-expressed-on-myeloid-cells-2 to neurological diseases. Int J Neurosci 2016; 127:368-375. [PMID: 27871212 DOI: 10.1080/00207454.2016.1264072] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Jie Han
- Department of Pharmacology, School of Medicine, Shandong University, Jinan 250012, China
- Department of Radiation Oncology, Shandong Cancer Hospital and Institute affiliated to Shandong University, Jinan 250012, China
| | - Miaomiao Wang
- Department of Hematology, Qilu Hospital, Shandong University, Jinan 250012, China
| | - Manru Ren
- Department of Pharmacology, School of Medicine, Shandong University, Jinan 250012, China
| | - Haiyan Lou
- Department of Pharmacology, School of Medicine, Shandong University, Jinan 250012, China
| |
Collapse
|
90
|
Bronzuoli MR, Iacomino A, Steardo L, Scuderi C. Targeting neuroinflammation in Alzheimer's disease. J Inflamm Res 2016; 9:199-208. [PMID: 27843334 PMCID: PMC5098782 DOI: 10.2147/jir.s86958] [Citation(s) in RCA: 172] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Almost 47 million people suffer from dementia worldwide, with an estimated new case diagnosed every 3.2 seconds. Alzheimer’s disease (AD) accounts for approximately 60%–80% of all dementia cases. Given this evidence, it is clear dementia represents one of the greatest global public health challenges. Currently used drugs alleviate the symptoms of AD but do not treat the underlying causes of dementia. Hence, a worldwide quest is under way to find new treatments to stop, slow, or even prevent AD. Besides the classic targets of the oldest therapies, represented by cholinergic and glutamatergic systems, β-amyloid (Aβ) plaques, and tau tangles, new therapeutic approaches have other targets. One of the newest and most promising strategies is the control of reactive gliosis, a multicellular response to brain injury. This phenomenon occurs as a consequence of a persistent glial activation, which leads to cellular dysfunctions and neuroinflammation. Reactive gliosis is now considered a key abnormality in the AD brain. It has been demonstrated that reactive astrocytes surround both Aβ plaques and tau tangles. In this condition, glial cells lose some of their homeostatic functions and acquire a proinflammatory phenotype amplifying neuronal damage. So, molecules that are able to restore their physiological functions and control the neuroinflammatory process offer new therapeutic opportunities for this devastating disease. In this review, we describe the role of neuroinflammation in the AD pathogenesis and progression and then provide an overview of the recent research with the aim of developing new therapies to treat this disorder.
Collapse
Affiliation(s)
- Maria Rosanna Bronzuoli
- Department of Physiology and Pharmacology "Vittorio Erspamer", Sapienza University of Rome, Rome, Italy
| | - Aniello Iacomino
- Faculty of Psychology, University of Rome "G. Marconi", Rome, Italy
| | - Luca Steardo
- Department of Physiology and Pharmacology "Vittorio Erspamer", Sapienza University of Rome, Rome, Italy
| | - Caterina Scuderi
- Department of Physiology and Pharmacology "Vittorio Erspamer", Sapienza University of Rome, Rome, Italy
| |
Collapse
|
91
|
Ruiz P, Martin-Millan M, Gonzalez-Martin MC, Almeida M, González-Macias J, Ros MA. CathepsinKCre mediated deletion of βcatenin results in dramatic loss of bone mass by targeting both osteoclasts and osteoblastic cells. Sci Rep 2016; 6:36201. [PMID: 27804995 PMCID: PMC5090355 DOI: 10.1038/srep36201] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 10/12/2016] [Indexed: 12/19/2022] Open
Abstract
It is well established that activation of Wnt/βcatenin signaling in the osteoblast lineage leads to an increase in bone mass through a dual mechanism: increased osteoblastogenesis and decreased osteoclastogenesis. However, the effect of this pathway on the osteoclast lineage has been less explored. Here, we aimed to examine the effects of Wnt/βcatenin signaling in mature osteoclasts by generating mice lacking βcatenin in CathepsinK-expressing cells (Ctnnb1f/f;CtsKCre mice). These mice developed a severe low-bone-mass phenotype with onset in the second month and in correlation with an excessive number of osteoclasts, detected by TRAP staining and histomorphometric quantification. We found that WNT3A, through the canonical pathway, promoted osteoclast apoptosis and therefore attenuated the number of M-CSF and RANKL-derived osteoclasts in vitro. This reveals a cell-autonomous effect of Wnt/βcatenin signaling in controlling the life span of mature osteoclasts. Furthermore, bone Opg expression in Ctnnb1f/f;CtsKCre mice was dramatically decreased pointing to an additional external activation of osteoclasts. Accordingly, expression of CathepsinK was detected in TRAP-negative cells of the inner periosteal layer also expressing Col1. Our results indicate that the bone phenotype of Ctnnb1f/f;CtsKCre animals combines a cell-autonomous effect in the mature osteoclast with indirect effects due to the additional targeting of osteoblastic cells.
Collapse
Affiliation(s)
- Paula Ruiz
- Instituto de Investigación Marqués de Valdecilla, IDIVAL, Cardenal Herrera Oria s/n. 39011 Santander, Spain
| | - Marta Martin-Millan
- Instituto de Investigación Marqués de Valdecilla, IDIVAL, Cardenal Herrera Oria s/n. 39011 Santander, Spain.,Department of Internal Medicine, HUMV, Hospital Universitario Marqués de Valdecilla, Avenida de Valdecilla s/n, 39008 Santander, Cantabria, Spain
| | - M C Gonzalez-Martin
- Instituto de Biomedicina y Biotecnología de Cantabria, IBBTEC (CSIC-SODERCAN-Universidad de Cantabria). Albert Einstein 22, 39011 Santander, Spain
| | - Maria Almeida
- Center for Osteoporosis and Metabolic Bone Diseases, University of Arkansas for Medical Sciences and the Central Arkansas Veterans Healthcare System, Little Rock, AR, USA
| | - Jesús González-Macias
- Instituto de Investigación Marqués de Valdecilla, IDIVAL, Cardenal Herrera Oria s/n. 39011 Santander, Spain.,Department of Internal Medicine, HUMV, Hospital Universitario Marqués de Valdecilla, Avenida de Valdecilla s/n, 39008 Santander, Cantabria, Spain.,Departamento de Medicina y Psiquiatría. Facultad de Medicina. Universidad de Cantabria, Cardenal Herrera Oria, s/n. 39011 Santander, Spain.,Red Temática de Investigación Cooperativa en Envejecimiento y Fragilidad (RETICEF), Avenida de Valdecilla, s/n. Santander 39008, Spain
| | - Maria A Ros
- Instituto de Biomedicina y Biotecnología de Cantabria, IBBTEC (CSIC-SODERCAN-Universidad de Cantabria). Albert Einstein 22, 39011 Santander, Spain.,Departamento de Anatomía y Biología Celular, Facultad de Medicina, Universidad de Cantabria, Cardenal Herrera Oria, s/n. 39011 Santander, Spain
| |
Collapse
|
92
|
Novack DV, Mbalaviele G. Osteoclasts-Key Players in Skeletal Health and Disease. Microbiol Spectr 2016; 4:10.1128/microbiolspec.MCHD-0011-2015. [PMID: 27337470 PMCID: PMC4920143 DOI: 10.1128/microbiolspec.mchd-0011-2015] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Indexed: 12/12/2022] Open
Abstract
The differentiation of osteoclasts (OCs) from early myeloid progenitors is a tightly regulated process that is modulated by a variety of mediators present in the bone microenvironment. Once generated, the function of mature OCs depends on cytoskeletal features controlled by an αvβ3-containing complex at the bone-apposed membrane and the secretion of protons and acid-protease cathepsin K. OCs also have important interactions with other cells in the bone microenvironment, including osteoblasts and immune cells. Dysregulation of OC differentiation and/or function can cause bone pathology. In fact, many components of OC differentiation and activation have been targeted therapeutically with great success. However, questions remain about the identity and plasticity of OC precursors and the interplay between essential networks that control OC fate. In this review, we summarize the key principles of OC biology and highlight recently uncovered mechanisms regulating OC development and function in homeostatic and disease states.
Collapse
Affiliation(s)
- Deborah Veis Novack
- Musculoskeletal Research Center, Division of Bone and Mineral Diseases, Department of Medicine
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110
| | - Gabriel Mbalaviele
- Musculoskeletal Research Center, Division of Bone and Mineral Diseases, Department of Medicine
| |
Collapse
|
93
|
Abstract
Alzheimer's disease (AD), the most common cause of dementia in the elderly, is a complex neurodegenerative disease marked by the appearance of amyloid-β (Aβ) plaques and hyperphosphorylated tau tangles. Alzheimer's disease has a strong genetic component, and recent advances in genome technology have unearthed novel variants in several genes, which could provide insight into the pathogenic mechanisms that contribute to AD. Particularly interesting are variants in the microglial-expressed receptor TREM2 which are associated with a 2-4-fold increased risk of developing AD. Since the discovery of a link between TREM2 and AD, multiple studies have emerged testing whether partial or complete loss of TREM2 function contributed to Aβ deposition or Aβ-associated microgliosis. Although some confounding conflicting data have emerged from these studies regarding the role of TREM2 in regulating Aβ deposition within the hippocampus, the most consistent and striking observation is a strong decrease in microgliosis surrounding Aβ plaques in TREM2 haploinsufficient and TREM2 deficient mice. Interestingly, a similar impairment in microgliosis has been reported in mouse models of prion disease, stroke, and multiple sclerosis, suggesting a critical role for TREM2 in supporting microgliosis in response to pathology in the central nervous system. In this Review, we summarize recent reports on the role of TREM2 in AD pathology and hypothesized mechanisms by which TREM2 function could influence AD-induced microgliosis.
Collapse
Affiliation(s)
- Jason D. Ulrich
- Department of
Neurology, Knight Alzheimer’s
Disease Research Center, and Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - David M. Holtzman
- Department of
Neurology, Knight Alzheimer’s
Disease Research Center, and Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| |
Collapse
|
94
|
Zheng H, Liu CC, Atagi Y, Chen XF, Jia L, Yang L, He W, Zhang X, Kang SS, Rosenberry TL, Fryer JD, Zhang YW, Xu H, Bu G. Opposing roles of the triggering receptor expressed on myeloid cells 2 and triggering receptor expressed on myeloid cells-like transcript 2 in microglia activation. Neurobiol Aging 2016; 42:132-41. [PMID: 27143430 DOI: 10.1016/j.neurobiolaging.2016.03.004] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 02/14/2016] [Accepted: 03/06/2016] [Indexed: 01/12/2023]
Abstract
Mutations in triggering receptor expressed on myeloid cells 2 (TREM2), which has been proposed to regulate the inflammatory responses and the clearance of apoptotic neurons and/or amyloid-β, are genetically linked to increased risk for late-onset Alzheimer's disease (AD). Interestingly, a missense variant in TREM-like transcript 2 (TREML2), a structurally similar protein encoded by the same gene cluster with TREM2 on chromosome 6, has been shown to protect against AD. However, the molecular mechanisms by which TREM2 and TREML2 regulate the pathogenesis of AD, and their functional relationship, if any, remain unclear. Here, we show that lipopolysaccharide (LPS) stimulation significantly suppressed TREM2 but increased TREML2 expression in mouse brain. Consistent with this in vivo result, LPS or oligomeric amyloid-β treatment down regulated TREM2 but up-regulated TREML2 expression in primary microglia. Most important, modulation of TREM2 or TREML2 levels had opposing effects on inflammatory responses with enhancement or suppression of LPS-induced proinflammatory cytokine gene expression observed on TREM2 or TREML2 down regulation, respectively. In addition, the proliferation of primary microglia was significantly decreased when TREM2 was down regulated, whereas it was increased on TREML2 knockdown. Together, our results suggest that several microglial functions are strictly regulated by TREM2 and TREML2, whose dysfunctions likely contribute to AD pathogenesis by impairing brain innate immunity. Our findings provide novel mechanistic insights into the functions of TREM2 and TREML2 in microglia and have implications on designing new therapeutic strategies to treat AD.
Collapse
Affiliation(s)
- Honghua Zheng
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, PR China
| | - Chia-Chen Liu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA
| | - Yuka Atagi
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA
| | - Xiao-Fen Chen
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, PR China
| | - Lin Jia
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, PR China
| | - Longyu Yang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, PR China
| | - Wencan He
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, PR China
| | - Xilin Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, PR China
| | - Silvia S Kang
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA
| | | | - John D Fryer
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA; Neurobiology of Disease Graduate Program, Mayo Clinic, Jacksonville, FL, USA
| | - Yun-Wu Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, PR China; Degenerative Disease Research Program, Sanford-Burnham Medical Research Institute, La Jolla, CA, USA
| | - Huaxi Xu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, PR China; Degenerative Disease Research Program, Sanford-Burnham Medical Research Institute, La Jolla, CA, USA
| | - Guojun Bu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Medical College, Xiamen University, Xiamen, PR China; Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA; Neurobiology of Disease Graduate Program, Mayo Clinic, Jacksonville, FL, USA.
| |
Collapse
|
95
|
Colonna M, Wang Y. TREM2 variants: new keys to decipher Alzheimer disease pathogenesis. Nat Rev Neurosci 2016; 17:201-7. [PMID: 26911435 DOI: 10.1038/nrn.2016.7] [Citation(s) in RCA: 273] [Impact Index Per Article: 34.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Genome-wide association studies have identified rare variants of the gene that encodes triggering receptor expressed on myeloid cells 2 (TREM2) - an immune receptor that is found in brain microglia - as risk factors for non-familial Alzheimer disease (AD). Furthermore, animal studies have indicated that microglia have an important role in the brain response to amyloid-β (Aβ) plaques and that TREM2 variants may have an impact on such a function. We discuss how TREM2 may control the microglial response to Aβ and its impact on microglial senescence, as well as the interaction of TREM2 with other molecules that are encoded by gene variants associated with AD and the hypothetical consequences of the cleavage of TREM2 from the cell surface.
Collapse
Affiliation(s)
- Marco Colonna
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, Missouri 63108, USA
| | - Yaming Wang
- Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana 46285, USA
| |
Collapse
|
96
|
Walter J. The Triggering Receptor Expressed on Myeloid Cells 2: A Molecular Link of Neuroinflammation and Neurodegenerative Diseases. J Biol Chem 2015; 291:4334-41. [PMID: 26694609 DOI: 10.1074/jbc.r115.704981] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The triggering receptor expressed on myeloid cells (TREM) 2 is a member of the immunoglobulin superfamily of receptors and mediates signaling in immune cells via engagement of its co-receptor DNAX-activating protein of 12 kDa (DAP12). Homozygous mutations in TREM2 or DAP12 cause Nasu-Hakola disease, which is characterized by bone abnormalities and dementia. Recently, a variant of TREM2 has also been associated with an increased risk for Alzheimer disease. The selective expression of TREM2 on immune cells and its association with different forms of dementia indicate a contribution of this receptor in common pathways of neurodegeneration.
Collapse
Affiliation(s)
- Jochen Walter
- From the Department of Neurology, University of Bonn, 53127 Bonn, Germany
| |
Collapse
|
97
|
Zhang ZG, Li Y, Ng CT, Song YQ. Inflammation in Alzheimer's Disease and Molecular Genetics: Recent Update. Arch Immunol Ther Exp (Warsz) 2015; 63:333-44. [PMID: 26232392 DOI: 10.1007/s00005-015-0351-0] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 03/03/2015] [Indexed: 01/01/2023]
Abstract
Alzheimer's disease (AD) is a complex age-related neurodegenerative disorder of the central nervous system. Since the first description of AD in 1907, many hypotheses have been established to explain its causes. The inflammation theory is one of them. Pathological and biochemical studies of brains from AD individuals have provided solid evidence of the activation of inflammatory pathways. Furthermore, people with long-term medication of anti-inflammatory drugs have shown a reduced risk to develop the disease. After three decades of genetic study in AD, dozens of loci harboring genetic variants influencing inflammatory pathways in AD patients has been identified through genome-wide association studies (GWAS). The most well-known GWAS risk factor that is responsible for immune response and inflammation in AD development should be APOE ε4 allele. However, a growing number of other GWAS risk AD candidate genes in inflammation have recently been discovered. In the present study, we try to review the inflammation in AD and immunity-associated GWAS risk genes like HLA-DRB5/DRB1, INPP5D, MEF2C, CR1, CLU and TREM2.
Collapse
Affiliation(s)
- Zhi-Gang Zhang
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong, People's Republic of China
| | - Yan Li
- Energy Research Institute of Shandong Academy of Sciences, Jinan, Shandong, People's Republic of China
| | - Cheung Toa Ng
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong, People's Republic of China
| | - You-Qiang Song
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong, People's Republic of China. .,State Key Laboratory for Cognitive and Brain Sciences, The University of Hong Kong, Pokfulam, Hong Kong, People's Republic of China.
| |
Collapse
|
98
|
Colony-stimulating factor 1 receptor inhibition prevents microglial plaque association and improves cognition in 3xTg-AD mice. J Neuroinflammation 2015; 12:139. [PMID: 26232154 PMCID: PMC4522109 DOI: 10.1186/s12974-015-0366-9] [Citation(s) in RCA: 333] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 07/21/2015] [Indexed: 12/25/2022] Open
Abstract
Background Microglia are dependent upon colony-stimulating factor 1 receptor (CSF1R) signaling for their survival in the adult brain, with administration of the dual CSF1R/c-kit inhibitor PLX3397 leading to the near-complete elimination of all microglia brainwide. Here, we determined the dose-dependent effects of a specific CSF1R inhibitor (PLX5622) on microglia in both wild-type and the 3xTg-AD mouse model of Alzheimer’s disease. Methods Wild-type mice were treated with PLX5622 for up to 21 days, and the effects on microglial numbers were assessed. 3xTg-AD mice were treated with PLX5622 for 6 or 12 weeks and effects on microglial numbers and pathology subsequently assessed. Results High doses of CSF1R inhibitor eliminate most microglia from the brain, but a 75 % lower-dose results in sustained elimination of ~30 % of microglia in both wild-type and 3xTg-AD mice. No behavioral or cognitive deficits were found in mice either depleted of microglia or treated with lower CSF1R inhibitor concentrations. Aged 3xTg-AD mice treated for 6 or 12 weeks with lower levels of PLX5622 resulted in improved learning and memory. Aβ levels and plaque loads were not altered, but microglia in treated mice no longer associated with plaques, revealing a role for the CSF1R in the microglial reaction to plaques, as well as in mediating cognitive deficits. Conclusions We find that inhibition of CSF1R alone is sufficient to eliminate microglia and that sustained microglial elimination is concentration-dependent. Inhibition of the CSF1R at lower levels in 3xTg-AD mice prevents microglial association with plaques and improves cognition.
Collapse
|
99
|
Georgess D, Machuca-Gayet I, Blangy A, Jurdic P. Podosome organization drives osteoclast-mediated bone resorption. Cell Adh Migr 2015; 8:191-204. [PMID: 24714644 DOI: 10.4161/cam.27840] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Osteoclasts are the cells responsible for physiological bone resorption. A specific organization of their most prominent cytoskeletal structures, podosomes, is crucial for the degradation of mineralized bone matrix. Each podosome is constituted of an F-actin-enriched central core surrounded by a loose F-actin network, called the podosome cloud. In addition to intrinsic actin dynamics, podosomes are defined by their adhesion to the extracellular matrix, mainly via core-linking CD44 and cloud-linking integrins. These properties allow podosomes to collectively evolve into different patterns implicated in migration and bone resorption. Indeed, to resorb bone, osteoclasts polarize, actively secrete protons, and proteases into the resorption pit where these molecules are confined by a podosome-containing sealing zone. Here, we review recent advancements on podosome structure and regulatory pathways in osteoclasts. We also discuss the distinct functions of different podosome patterns during the lifespan of a single osteoclast.
Collapse
Affiliation(s)
- Dan Georgess
- Institut de Génomique Fonctionnelle de Lyon; Université de Lyon; Ecole Normale Supérieure de Lyon; Lyon, France
| | - Irma Machuca-Gayet
- Institut de Génomique Fonctionnelle de Lyon; Université de Lyon; Ecole Normale Supérieure de Lyon; Lyon, France
| | - Anne Blangy
- Centre de Recherche de Biochimie Macromoléculaire; CNRS UMR 5237; Montpellier University; Montpellier, France
| | - Pierre Jurdic
- Institut de Génomique Fonctionnelle de Lyon; Université de Lyon; Ecole Normale Supérieure de Lyon; Lyon, France
| |
Collapse
|
100
|
Osteoimmunology: Major and Costimulatory Pathway Expression Associated with Chronic Inflammatory Induced Bone Loss. J Immunol Res 2015; 2015:281287. [PMID: 26064999 PMCID: PMC4433696 DOI: 10.1155/2015/281287] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 12/10/2014] [Indexed: 12/28/2022] Open
Abstract
The field of osteoimmunology has emerged in response to the range of evidences demonstrating the close interrelationship between the immune system and bone metabolism. This is pertinent to immune-mediated diseases, such as rheumatoid arthritis and periodontal disease, where there are chronic inflammation and local bone erosion. Periprosthetic osteolysis is another example of chronic inflammation with associated osteolysis. This may also involve immune mediation when occurring in a patient with rheumatoid arthritis (RA). Similarities in the regulation and mechanisms of bone loss are likely to be related to the inflammatory cytokines expressed in these diseases. This review highlights the role of immune-related factors influencing bone loss particularly in diseases of chronic inflammation where there is associated localized bone loss. The importance of the balance of the RANKL-RANK-OPG axis is discussed as well as the more recently appreciated role that receptors and adaptor proteins involved in the immunoreceptor tyrosine-based activation motif (ITAM) signaling pathway play. Although animal models are briefly discussed, the focus of this review is on the expression of ITAM associated molecules in relation to inflammation induced localized bone loss in RA, chronic periodontitis, and periprosthetic osteolysis, with an emphasis on the soluble and membrane bound factor osteoclast-associated receptor (OSCAR).
Collapse
|