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Otsuka M, Okinaga T, Ariyoshi W, Kitamura C, Nishihara T. Ameloblastin Upregulates Inflammatory Response Through Induction of IL-1β in Human Macrophages. J Cell Biochem 2017; 118:3308-3317. [PMID: 28295583 DOI: 10.1002/jcb.25983] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 03/08/2017] [Indexed: 11/10/2022]
Abstract
Ameloblastin (AMBN) is an enamel matrix protein that has various biological functions such as healing dental pulp and repairing bone fractures. In the present study, we clarified the effect of AMBN on the expression of an inflammatory cytokine, interleukin-1β (IL-1β) in lipopolysaccharide (LPS)-treated human macrophages. Real-time RT-PCR analysis showed that LPS treatment upregulated expression of the IL-1β gene in U937 cells. Interestingly, AMBN significantly enhanced IL-1β gene expression in LPS-treated U937 cells as well as the secretion of mature IL-1β into culture supernatants by these cells. AMBN also activated caspase-1 p10 expression in LPS-treated U937 cells. Pretreatment with a caspase-1 inhibitor, Z-YVAD-FMK, downregulated the mature IL-1β expression enhanced by AMBN treatment in LPS-treated U937 cells. A co-immunoprecipitation assay showed that treatment with LPS and AMBN upregulated toll-like receptor 4 (TLR4) and myeloid differentiation primary response gene 88 (MyD88) interactions, but there was no significant difference compared with LPS treatment alone in U937 cells. In contrast, western blot analysis revealed that AMBN remarkably prolonged the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), a member of the mitogen-activated protein kinase (MAPK) family. An ERK1/2-selective inhibitor, U0126, suppressed expression of the IL-1β gene as well as its protein expression in U937 cells treated with LPS and AMBN. Taken together, these results indicate that AMBN enhances IL-1β production in LPS-treated U937 cells through ERK1/2 phosphorylation and caspase-1 activation, suggesting that AMBN upregulates the inflammatory response in human macrophages and plays an important role in innate immunity. J. Cell. Biochem. 118: 3308-3317, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Mai Otsuka
- Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental University, Kitakyushu 803-8580, Japan.,Division of Endodontics and Restorative Dentistry, Department of Oral Functions, Kyushu Dental University, Kitakyushu 803-8580, Japan
| | - Toshinori Okinaga
- Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental University, Kitakyushu 803-8580, Japan
| | - Wataru Ariyoshi
- Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental University, Kitakyushu 803-8580, Japan
| | - Chiaki Kitamura
- Division of Endodontics and Restorative Dentistry, Department of Oral Functions, Kyushu Dental University, Kitakyushu 803-8580, Japan
| | - Tatsuji Nishihara
- Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental University, Kitakyushu 803-8580, Japan
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Lu X, Fukumoto S, Yamada Y, Evans CA, Diekwisch TG, Luan X. Ameloblastin, an Extracellular Matrix Protein, Affects Long Bone Growth and Mineralization. J Bone Miner Res 2016; 31:1235-46. [PMID: 26766111 DOI: 10.1002/jbmr.2788] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 01/06/2016] [Accepted: 01/08/2016] [Indexed: 11/07/2022]
Abstract
Matrix molecules such as the enamel-related calcium-binding phosphoprotein ameloblastin (AMBN) are expressed in multiple tissues, including teeth, bones, and cartilage. Here we have asked whether AMBN is of functional importance for timely long bone development and, if so, how it exerts its function related to osteogenesis. Adolescent AMBN-deficient mice (AMBN(Δ5-6) ) suffered from a 33% to 38% reduction in femur length and an 8.4% shorter trunk spinal column when compared with WT controls, whereas there was no difference between adult animals. On a cellular level, AMBN truncation resulted in a shortened growth plate and a 41% to 49% reduction in the number of proliferating tibia chondrocytes and osteoblasts. Bone marrow stromal cells (BMSCs) isolated from AMBN mutant mice displayed defects in proliferation and differentiation potential as well as cytoskeleton organization. Osteogenesis-related growth factors, such as insulin-like growth factor 1 (IGF1) and BMP7, were also significantly (46% to 73%) reduced in AMBN-deficient BMSCs. Addition of exogenous AMBN restored cytoskeleton structures in AMBN mutant BMSCs and resulted in a dramatic 400% to 600% increase in BMP2, BMP7, and Col1A expression. Block of RhoA diminished the effect of AMBN on osteogenic growth factor and matrix protein gene expression. Addition of exogenous BMP7 and IGF1 rescued the proliferation and differentiation potential of AMBN-deficient BMSCs. Confirming the effects of AMBN on long bone growth, back-crossing of mutant mice with full-length AMBN overexpressors resulted in a complete rescue of AMBN(Δ5-6) bone defects. Together, these data indicate that AMBN affects extracellular matrix production and cell adhesion properties in the long bone growth plate, resulting in altered cytoskeletal dynamics, increased osteogenesis-related gene expression, as well as osteoblast and chondrocyte proliferation. We propose that AMBN facilitates rapid long bone growth and an important growth spurt during the skeletogenesis of adolescent tooth-bearing vertebrates. © 2016 American Society for Bone and Mineral Research.
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Affiliation(s)
- Xuanyu Lu
- Department of Oral Biology, Brodie Laboratory for Craniofacial Genetics, University of Illinois College of Dentistry, Chicago, IL, USA
| | - Satoshi Fukumoto
- Craniofacial Developmental Biology and Regeneration Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Yoshihiko Yamada
- Craniofacial Developmental Biology and Regeneration Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Carla A Evans
- Department of Orthodontics, Brodie Laboratory for Craniofacial Genetics, University of Illinois College of Dentistry, Chicago, IL, USA
| | - Thomas Gh Diekwisch
- Department of Oral Biology, Brodie Laboratory for Craniofacial Genetics, University of Illinois College of Dentistry, Chicago, IL, USA
| | - Xianghong Luan
- Department of Oral Biology, Brodie Laboratory for Craniofacial Genetics, University of Illinois College of Dentistry, Chicago, IL, USA.,Department of Orthodontics, Brodie Laboratory for Craniofacial Genetics, University of Illinois College of Dentistry, Chicago, IL, USA
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