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Yang X, Chen M, Wang S, Hu X, Zhou J, Yuan H, Zhu E, Wang B. Cortactin controls bone homeostasis through regulating the differentiation of osteoblasts and osteoclasts. Stem Cells 2024; 42:662-674. [PMID: 38655781 DOI: 10.1093/stmcls/sxae031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Accepted: 04/10/2024] [Indexed: 04/26/2024]
Abstract
Cortactin (CTTN), a cytoskeletal protein and substrate of Src kinase, is implicated in tumor aggressiveness. However, its role in bone cell differentiation remains unknown. The current study revealed that CTTN was upregulated during osteoblast and adipocyte differentiation. Functional experiments demonstrated that CTTN promoted the in vitro differentiation of mesenchymal stem/progenitor cells into osteogenic and adipogenic lineages. Mechanistically, CTTN was able to stabilize the protein level of mechanistic target of rapamycin kinase (mTOR), leading to the activation of mTOR signaling. In-depth investigation revealed that CTTN could bind with casitas B lineage lymphoma-c (c-CBL) and counteract the function of c-CBL, a known E3 ubiquitin ligase responsible for the proteasomal degradation of mTOR. Silencing c-Cbl alleviated the impaired differentiation of osteoblasts and adipocytes caused by CTTN siRNA, while silencing mTOR mitigated the stimulation of osteoblast and adipocyte differentiation induced by CTTN overexpression. Notably, transplantation of CTTN-silenced bone marrow stromal cells (BMSCs) into the marrow of mice led to a reduction in trabecular bone mass, accompanied by a decrease in osteoblasts and an increase in osteoclasts. Furthermore, CTTN-silenced BMSCs expressed higher levels of receptor activator of nuclear factor κB ligand (RANKL) than control BMSCs did and promoted osteoclast differentiation when cocultured with bone marrow-derived osteoclast precursor cells. This study provides evidence that CTTN favors osteoblast differentiation by counteracting the c-CBL-induced degradation of mTOR and inhibits osteoclast differentiation by downregulating the expression of RANKL. It also suggests that maintaining an appropriate level of CTTN expression may be advantageous for maintaining bone homeostasis.
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Affiliation(s)
- Xiaoli Yang
- NHC Key Lab of Hormones and Development, Tianjin Key Lab of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Institute of Endocrinology, Tianjin Medical University, Tianjin 300134, People's Republic of China
| | - Meng Chen
- Department of hematology, the First Affiliated Hospital of Nanchang University, Nanchang 330006, People's Republic of China
| | - Shuang Wang
- NHC Key Lab of Hormones and Development, Tianjin Key Lab of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Institute of Endocrinology, Tianjin Medical University, Tianjin 300134, People's Republic of China
| | - Xingli Hu
- NHC Key Lab of Hormones and Development, Tianjin Key Lab of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Institute of Endocrinology, Tianjin Medical University, Tianjin 300134, People's Republic of China
| | - Jie Zhou
- NHC Key Lab of Hormones and Development, Tianjin Key Lab of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Institute of Endocrinology, Tianjin Medical University, Tianjin 300134, People's Republic of China
| | - Hairui Yuan
- NHC Key Lab of Hormones and Development, Tianjin Key Lab of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Institute of Endocrinology, Tianjin Medical University, Tianjin 300134, People's Republic of China
| | - Endong Zhu
- NHC Key Lab of Hormones and Development, Tianjin Key Lab of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Institute of Endocrinology, Tianjin Medical University, Tianjin 300134, People's Republic of China
| | - Baoli Wang
- NHC Key Lab of Hormones and Development, Tianjin Key Lab of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Institute of Endocrinology, Tianjin Medical University, Tianjin 300134, People's Republic of China
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2
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Jiang B, Zheng J, Yao H, Wang Y, Song F, Huang C. IRX5 suppresses osteogenic differentiation of hBMSCs by inhibiting protein synthesis. J Cell Physiol 2024; 239:e31286. [PMID: 38666481 DOI: 10.1002/jcp.31286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 03/21/2024] [Accepted: 04/16/2024] [Indexed: 06/14/2024]
Abstract
In our previous study, IRX5 has been revealed a significant role in adipogenesis of hBMSCs. Considering the expansion of adipose tissue in bone marrow in aged and ovariectomy-related osteoporosis, the effect of IRX5 on the osteogenesis of BMSCs still needs to be elucidated. In vivo, models of aging-induced and ovariectomy-induced osteoporotic mice, and in vitro studies of IRX5 gene gain- and loss-of-function in hBMSCs were employed. Histology, immunofluorescence, qRT-PCR, and Western blot analysis were performed to detect the functions of IRX5 in hBMSCs osteogenic differentiation. RNA-seq, transmission electron microscopy, Seahorse mito-stress assay, and Surface Sensing of Translation assay were conducted to explore the effect of mammalian/mechanistic target of rapamycin (mTOR)-mediated ribosomal translation and mitochondrial functions in the regulation of hBMSCs differentiation by IRX5. As a result, elevated IRX5 protein expression levels were observed in the bone marrow of osteoporotic mice compared to normal mice. IRX5 overexpression attenuated osteogenic processes, whereas IRX5 knockdown resulted in enhanced osteogenesis in hBMSCs. RNA-seq and enrichment analysis unveiled that IRX5 overexpression exerted inhibitory effects on ribosomal translation and mitochondrial functions. Furthermore, the application of the mTOR activator, MHY1485, effectively reversed the inhibitory impact of IRX5 on osteogenesis and mitochondrial functions in hBMSCs. In summary, our findings suggest that IRX5 restricts mTOR-mediated ribosomal translation, consequently impairing mitochondrial OxPhos, which in turn results in osteogenic dysfunction of hBMSCs.
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Affiliation(s)
- Bulin Jiang
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Hubei, China
- Department of Prosthodontics, Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Clinical Research Center for Oral Diseases of Zhejiang Province; Key Laboratory of Oral Biomedical Research of Zhejiang Province, Hangzhou, Zhejiang, China
| | - Jiqi Zheng
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Hubei, China
| | - Hantao Yao
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Hubei, China
| | - Yake Wang
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Hubei, China
| | - Fangfang Song
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Hubei, China
| | - Cui Huang
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Hubei, China
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3
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Nie J, Ma S, Zhang Y, Yu S, Yang J, Li A, Pei D. COPI Vesicle Disruption Inhibits Mineralization via mTORC1-Mediated Autophagy. Int J Mol Sci 2023; 25:339. [PMID: 38203512 PMCID: PMC10779376 DOI: 10.3390/ijms25010339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 12/21/2023] [Accepted: 12/22/2023] [Indexed: 01/12/2024] Open
Abstract
Bone mineralization is a sophisticated regulated process composed of crystalline calcium phosphate and collagen fibril. Autophagy, an evolutionarily conserved degradation system, whereby double-membrane vesicles deliver intracellular macromolecules and organelles to lysosomes for degradation, has recently been shown to play an essential role in mineralization. However, the formation of autophagosomes in mineralization remains to be determined. Here, we show that Coat Protein Complex I (COPI), responsible for Golgi-to-ER transport, plays a pivotal role in autophagosome formation in mineralization. COPI vesicles were increased after osteoinduction, and COPI vesicle disruption impaired osteogenesis. Mechanistically, COPI regulates autophagy activity via the mTOR complex 1 (mTORC1) pathway, a key regulator of autophagy. Inhibition of mTOR1 rescues the impaired osteogenesis by activating autophagy. Collectively, our study highlights the functional importance of COPI in mineralization and identifies COPI as a potential therapeutic target for treating bone-related diseases.
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Affiliation(s)
| | | | | | | | | | | | - Dandan Pei
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi’an Jiaotong University, Xi’an 710004, China
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4
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Man K, Mazumder S, Dahotre NB, Yang Y. Surface Nanostructures Enhanced Biocompatibility and Osteoinductivity of Laser-Additively Manufactured CoCrMo Alloys. ACS OMEGA 2023; 8:47658-47666. [PMID: 38144145 PMCID: PMC10734289 DOI: 10.1021/acsomega.3c04305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 09/19/2023] [Indexed: 12/26/2023]
Abstract
Cobalt-chromium-molybdenum (CoCrMo) alloys are widely used in orthopedic implants due to their excellent corrosion and wear resistance and superior mechanical properties. However, their limited capability to promote cell adhesion and new bone tissue formation, poor blood compatibility, and risk of microbial infection can lead to implant failure or reduced implant lifespan. Surface structure modification has been used to improve the cytocompatibility and blood compatibility of implant materials and reduce the risk of infection. In this study, we prepared CoCrMo alloys with surface nanostructures of various aspect ratios (AR) using laser-directed energy deposition (L-DED) and biocorrosion. Our results showed that medium and high AR nanostructures reduced platelet adhesion, while all of the alloys demonstrated good blood compatibility and antibacterial properties. Moreover, the medium and high AR nanostructures promoted cell adhesion and spreading of both preosteoblast MC3T3 cells and human bone marrow mesenchymal stem cells (hMSCs). Furthermore, the nanostructure promoted the osteogenic differentiation of both cell types compared with the flat control surface, with a substantial enhancing effect for the medium and high ARs. Our study proposes a promising approach for developing implant materials with improved clinical outcomes.
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Affiliation(s)
- Kun Man
- Department
of Biomedical Engineering, University of
North Texas, Denton, Texas 76207, United States
- Center
for Agile and Adaptive Additive Manufacturing, University of North Texas, Denton, Texas 76207, United States
| | - Sangram Mazumder
- Center
for Agile and Adaptive Additive Manufacturing, University of North Texas, Denton, Texas 76207, United States
- Department
of Materials Science and Engineering, University
of North Texas, Denton, Texas 76207, United States
| | - Narendra B. Dahotre
- Center
for Agile and Adaptive Additive Manufacturing, University of North Texas, Denton, Texas 76207, United States
- Department
of Materials Science and Engineering, University
of North Texas, Denton, Texas 76207, United States
| | - Yong Yang
- Department
of Biomedical Engineering, University of
North Texas, Denton, Texas 76207, United States
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5
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Kang Z, Wu B, Zhang L, Liang X, Guo D, Yuan S, Xie D. Metabolic regulation by biomaterials in osteoblast. Front Bioeng Biotechnol 2023; 11:1184463. [PMID: 37324445 PMCID: PMC10265685 DOI: 10.3389/fbioe.2023.1184463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Accepted: 05/19/2023] [Indexed: 06/17/2023] Open
Abstract
The repair of bone defects resulting from high-energy trauma, infection, or pathological fracture remains a challenge in the field of medicine. The development of biomaterials involved in the metabolic regulation provides a promising solution to this problem and has emerged as a prominent research area in regenerative engineering. While recent research on cell metabolism has advanced our knowledge of metabolic regulation in bone regeneration, the extent to which materials affect intracellular metabolic remains unclear. This review provides a detailed discussion of the mechanisms of bone regeneration, an overview of metabolic regulation in bone regeneration in osteoblasts and biomaterials involved in the metabolic regulation for bone regeneration. Furthermore, it introduces how materials, such as promoting favorable physicochemical characteristics (e.g., bioactivity, appropriate porosity, and superior mechanical properties), incorporating external stimuli (e.g., photothermal, electrical, and magnetic stimulation), and delivering metabolic regulators (e.g., metal ions, bioactive molecules like drugs and peptides, and regulatory metabolites such as alpha ketoglutarate), can affect cell metabolism and lead to changes of cell state. Considering the growing interests in cell metabolic regulation, advanced materials have the potential to help a larger population in overcoming bone defects.
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Affiliation(s)
- Zhengyang Kang
- Department of Orthopedics, The Second People’s Hospital of Panyu Guangzhou, Guangzhou, China
- Department of Joint Surgery and Sports Medicine, Center for Orthopedic Surgery, Orthopedic Hospital of Guangdong Province, The Third Affiliated Hospital of Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diseases, The Third Affiliated Hospital of Southern Medical University, Guangzhou, China
| | - Bin Wu
- Department of Orthopedics, The Second People’s Hospital of Panyu Guangzhou, Guangzhou, China
| | - Luhui Zhang
- Department of Joint Surgery and Sports Medicine, Center for Orthopedic Surgery, Orthopedic Hospital of Guangdong Province, The Third Affiliated Hospital of Southern Medical University, Guangzhou, China
| | - Xinzhi Liang
- Department of Joint Surgery and Sports Medicine, Center for Orthopedic Surgery, Orthopedic Hospital of Guangdong Province, The Third Affiliated Hospital of Southern Medical University, Guangzhou, China
| | - Dong Guo
- Department of Joint Surgery and Sports Medicine, Center for Orthopedic Surgery, Orthopedic Hospital of Guangdong Province, The Third Affiliated Hospital of Southern Medical University, Guangzhou, China
| | - Shuai Yuan
- Department of Joint Surgery and Sports Medicine, Center for Orthopedic Surgery, Orthopedic Hospital of Guangdong Province, The Third Affiliated Hospital of Southern Medical University, Guangzhou, China
| | - Denghui Xie
- Department of Joint Surgery and Sports Medicine, Center for Orthopedic Surgery, Orthopedic Hospital of Guangdong Province, The Third Affiliated Hospital of Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diseases, The Third Affiliated Hospital of Southern Medical University, Guangzhou, China
- Guangxi Key Laboratory of Bone and Joint Degeneration Diseases, Youjiang Medical University For Nationalities, Baise, China
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Tang J, Yang L, Guan F, Miller H, Camara NOS, James LK, Benlagha K, Kubo M, Heegaard S, Lee P, Lei J, Zeng H, He C, Zhai Z, Liu C. The role of Raptor in lymphocytes differentiation and function. Front Immunol 2023; 14:1146628. [PMID: 37283744 PMCID: PMC10239924 DOI: 10.3389/fimmu.2023.1146628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 04/28/2023] [Indexed: 06/08/2023] Open
Abstract
Raptor, a key component of mTORC1, is required for recruiting substrates to mTORC1 and contributing to its subcellular localization. Raptor has a highly conserved N-terminus domain and seven WD40 repeats, which interact with mTOR and other mTORC1-related proteins. mTORC1 participates in various cellular events and mediates differentiation and metabolism. Directly or indirectly, many factors mediate the differentiation and function of lymphocytes that is essential for immunity. In this review, we summarize the role of Raptor in lymphocytes differentiation and function, whereby Raptor mediates the secretion of cytokines to induce early lymphocyte metabolism, development, proliferation and migration. Additionally, Raptor regulates the function of lymphocytes by regulating their steady-state maintenance and activation.
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Affiliation(s)
- Jianing Tang
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Lu Yang
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Fei Guan
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Heather Miller
- Cytek Biosciences, R&D Clinical Reagents, Fremont, CA, United States
| | - Niels Olsen Saraiva Camara
- Department of Immunology, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, SP, Brazil
| | - Louisa K. James
- Centre for Immunobiology, Bizard Institute, Queen Mary University of London, London, United Kingdom
| | - Kamel Benlagha
- Université de Paris, Institut de Recherche Saint-Louis, EMiLy, Paris, France
| | - Masato Kubo
- Laboratory for Cytokine Regulation, Center for Integrative Medical Science (IMS), Rikagaku Kenkyusho, Institute of Physical and Chemical Research (RIKEN) Yokohama Institute, Yokohama, Japan
| | - Steffen Heegaard
- Department of Ophthalmology, Rigshospitalet Glostrup, Copenhagen, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Pamela Lee
- Department of Paediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, Hong Kong SAR, China
| | - Jiahui Lei
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Hu Zeng
- Department of Immunology, Mayo Clinic, Rochester, MN, United States
- Division of Rheumatology, Department of Medicine, Mayo Clinic, Rochester, MN, United States
| | - Chengwei He
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa, Macao SAR, China
| | - Zhimin Zhai
- Department of Hematology, The Second Hospital of Anhui Medical University, Hefei, China
| | - Chaohong Liu
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, Hubei, China
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Strontium ion attenuates osteoarthritis through inhibiting senescence and enhancing autophagy in fibroblast-like synoviocytes. Mol Biol Rep 2023; 50:1437-1446. [PMID: 36472726 DOI: 10.1007/s11033-022-08112-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 11/09/2022] [Indexed: 12/12/2022]
Abstract
Osteoarthritis (OA) mainly occurs in the elderly population and seriously affects their quality of life (QOL). Strontium (Sr) ions have shown positive effects on bone tissue and are promising for OA treatment. However, the adequate treatment dosage and underlying mechanisms are unclear. This study investigated the effects and underlying mechanisms of different concentrations of Sr ions in a mouse model of OA induced by destabilization of the medial meniscus (DMM) surgery. DMM-induced OA mice received intra-articular injections of different concentrations of Sr ions, and a suitable concentration of Sr ions was found to improve OA. Furthermore, we investigated the mechanism by which Sr ions mediate senescence and autophagy in fibroblast-like synoviocytes (FLSs) in the synovial tissues of DMM-induced OA mice. OA mice treated with 10 µl of 5 mmol/L SrCl2 showed the greatest improvement in pain-related behavior and cartilage damage. In addition, in vivo and in vitro experiments revealed that Sr ions inhibit senescence and improve the autophagic function of FLSs. We also found that enhancement of the autophagic function of FLSs could effectively slow down senescence. Therefore, we show that Sr ions through the AMPK/mTOR/LC3B-II signal axis improve FLSs autophagy function and delay FLSs senescence, and furthermore, improve OA. These results suggest that senescence and autophagy function of FLSs may serve as promising targets for OA treatment, and that Sr ions may inhibit OA progression through these two targets.
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8
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H’ng CH, Khaladkar A, Rosello-Diez A. Look who's TORking: mTOR-mediated integration of cell status and external signals during limb development and endochondral bone growth. Front Cell Dev Biol 2023; 11:1153473. [PMID: 37152288 PMCID: PMC10154674 DOI: 10.3389/fcell.2023.1153473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Accepted: 04/03/2023] [Indexed: 05/09/2023] Open
Abstract
The balance of cell proliferation and size is key for the control of organ development and repair. Moreover, this balance has to be coordinated within tissues and between tissues to achieve robustness in the organ's pattern and size. The tetrapod limb has been used to study these topics during development and repair, and several conserved pathways have emerged. Among them, mechanistic target of rapamycin (mTOR) signaling, despite being active in several cell types and developmental stages, is one of the least understood in limb development, perhaps because of its multiple potential roles and interactions with other pathways. In the body of this review, we have collated and integrated what is known about the role of mTOR signaling in three aspects of tetrapod limb development: 1) limb outgrowth; 2) chondrocyte differentiation after mesenchymal condensation and 3) endochondral ossification-driven longitudinal bone growth. We conclude that, given its ability to interact with the most common signaling pathways, its presence in multiple cell types, and its ability to influence cell proliferation, size and differentiation, the mTOR pathway is a critical integrator of external stimuli and internal status, coordinating developmental transitions as complex as those taking place during limb development. This suggests that the study of the signaling pathways and transcription factors involved in limb patterning, morphogenesis and growth could benefit from probing the interaction of these pathways with mTOR components.
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Affiliation(s)
- Chee Ho H’ng
- Australian Regenerative Medicine Institute, Monash University, Clayton, VIC, Australia
| | - Ashwini Khaladkar
- Department of Biochemistry, Central University of Hyderabad, Hyderabad, India
| | - Alberto Rosello-Diez
- Australian Regenerative Medicine Institute, Monash University, Clayton, VIC, Australia
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
- *Correspondence: Alberto Rosello-Diez, ,
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9
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Ahmadi A, Mazloomnejad R, Kasravi M, Gholamine B, Bahrami S, Sarzaeem MM, Niknejad H. Recent advances on small molecules in osteogenic differentiation of stem cells and the underlying signaling pathways. Stem Cell Res Ther 2022; 13:518. [PMID: 36371202 PMCID: PMC9652959 DOI: 10.1186/s13287-022-03204-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 10/09/2022] [Indexed: 11/15/2022] Open
Abstract
Bone-related diseases are major contributors to morbidity and mortality in elderly people and the current treatments result in insufficient healing and several complications. One of the promising areas of research for healing bone fractures and skeletal defects is regenerative medicine using stem cells. Differentiating stem cells using agents that shift cell development towards the preferred lineage requires activation of certain intracellular signaling pathways, many of which are known to induce osteogenesis during embryological stages. Imitating embryological bone formation through activation of these signaling pathways has been the focus of many osteogenic studies. Activation of osteogenic signaling can be done by using small molecules. Several of these agents, e.g., statins, metformin, adenosine, and dexamethasone have other clinical uses but have also shown osteogenic capacities. On the other hand, some other molecules such as T63 and tetrahydroquinolines are not as well recognized in the clinic. Osteogenic small molecules exert their effects through the activation of signaling pathways known to be related to osteogenesis. These pathways include more well-known pathways including BMP/Smad, Wnt, and Hedgehog as well as ancillary pathways including estrogen signaling and neuropeptide signaling. In this paper, we review the recent data on small molecule-mediated osteogenic differentiation, possible adjunctive agents with these molecules, and the signaling pathways through which each small molecule exerts its effects.
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Affiliation(s)
- Armin Ahmadi
- Department of Pharmacology, School of Medicine, Shahid Beheshti University of Medical Sciences, P.O. Box: 1985711151, Tehran, Iran
| | - Radman Mazloomnejad
- Department of Pharmacology, School of Medicine, Shahid Beheshti University of Medical Sciences, P.O. Box: 1985711151, Tehran, Iran
| | - Mohammadreza Kasravi
- Department of Pharmacology, School of Medicine, Shahid Beheshti University of Medical Sciences, P.O. Box: 1985711151, Tehran, Iran
| | - Babak Gholamine
- Department of Pharmacology, School of Medicine, Shahid Beheshti University of Medical Sciences, P.O. Box: 1985711151, Tehran, Iran
| | - Soheyl Bahrami
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology in AUVA Research Center, Vienna, Austria
| | - Mohammad Mahdi Sarzaeem
- Department of Orthopedic Surgery, Imam Hossein Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hassan Niknejad
- Department of Pharmacology, School of Medicine, Shahid Beheshti University of Medical Sciences, P.O. Box: 1985711151, Tehran, Iran.
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10
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Role of Essential Amino Acids in Age-Induced Bone Loss. Int J Mol Sci 2022; 23:ijms231911281. [PMID: 36232583 PMCID: PMC9569615 DOI: 10.3390/ijms231911281] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 09/16/2022] [Accepted: 09/20/2022] [Indexed: 11/16/2022] Open
Abstract
Age-induced osteoporosis is a global problem. Essential amino acids (EAAs) work as an energy source and a molecular pathway modulator in bone, but their functions have not been systematically reviewed in aging bone. This study aimed to discuss the contribution of EAAs on aging bone from in vitro, in vivo, and human investigations. In aged people with osteoporosis, serum EAAs were detected changing up and down, without a well-established conclusion. The supply of EAAs in aged people either rescued or did not affect bone mineral density (BMD) and bone volume. In most signaling studies, EAAs were proven to increase bone mass. Lysine, threonine, methionine, tryptophan, and isoleucine can increase osteoblast proliferation, activation, and differentiation, and decrease osteoclast activity. Oxidized L-tryptophan promotes bone marrow stem cells (BMSCs) differentiating into osteoblasts. However, the oxidation product of tryptophan called kynurenine increases osteoclast activity, and enhances the differentiation of adipocytes from BMSCs. Taken together, in terms of bone minerals and volume, more views consider EAAs to have a positive effect on aging bone, but the function of EAAs in bone metabolism has not been fully demonstrated and more studies are needed in this area in the future.
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11
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Cai H, Wang Z, Tang W, Ke X, Zhao E. Recent advances of the mammalian target of rapamycin signaling in mesenchymal stem cells. Front Genet 2022; 13:970699. [PMID: 36110206 PMCID: PMC9468880 DOI: 10.3389/fgene.2022.970699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 08/11/2022] [Indexed: 11/22/2022] Open
Abstract
Mammalian target of rapamycin (mTOR) is a serine/threonine kinase involved in a variety of cellular functions, such as cell proliferation, metabolism, autophagy, survival and cytoskeletal organization. Furthermore, mTOR is made up of three multisubunit complexes, mTOR complex 1, mTOR complex 2, and putative mTOR complex 3. In recent years, increasing evidence has suggested that mTOR plays important roles in the differentiation and immune responses of mesenchymal stem cells (MSCs). In addition, mTOR is a vital regulator of pivotal cellular and physiological functions, such as cell metabolism, survival and ageing, where it has emerged as a novel therapeutic target for ageing-related diseases. Therefore, the mTOR signaling may develop a large impact on the treatment of ageing-related diseases with MSCs. In this review, we discuss prospects for future research in this field.
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Affiliation(s)
- Huarui Cai
- State Key Laboratory of Silkworm Genome Biology, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
- Cancer Center, Medical Research Institute, Southwest University, Chongqing, China
| | - Zhongze Wang
- State Key Laboratory of Silkworm Genome Biology, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
- Cancer Center, Medical Research Institute, Southwest University, Chongqing, China
| | - Wenhan Tang
- State Key Laboratory of Silkworm Genome Biology, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
| | - Xiaoxue Ke
- State Key Laboratory of Silkworm Genome Biology, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
- Cancer Center, Medical Research Institute, Southwest University, Chongqing, China
- *Correspondence: Xiaoxue Ke, ; Erhu Zhao,
| | - Erhu Zhao
- State Key Laboratory of Silkworm Genome Biology, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
- Cancer Center, Medical Research Institute, Southwest University, Chongqing, China
- *Correspondence: Xiaoxue Ke, ; Erhu Zhao,
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12
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Bae S, Oh B, Tsai J, Park PSU, Greenblatt MB, Giannopoulou EG, Park-Min KH. The crosstalk between MYC and mTORC1 during osteoclastogenesis. Front Cell Dev Biol 2022; 10:920683. [PMID: 36060812 PMCID: PMC9437285 DOI: 10.3389/fcell.2022.920683] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 07/19/2022] [Indexed: 12/02/2022] Open
Abstract
Osteoclasts are bone-resorbing cells that undergo extensive changes in morphology throughout their differentiation. Altered osteoclast differentiation and activity lead to changes in pathological bone resorption. The mammalian target of rapamycin (mTOR) is a kinase, and aberrant mTOR complex 1 (mTORC1) signaling is associated with altered bone homeostasis. The activation of mTORC1 is biphasically regulated during osteoclastogenesis; however, the mechanism behind mTORC1-mediated regulation of osteoclastogenesis and bone resorption is incompletely understood. Here, we found that MYC coordinates the dynamic regulation of mTORC1 activation during osteoclastogenesis. MYC-deficiency blocked the early activation of mTORC1 and also reversed the decreased activity of mTORC1 at the late stage of osteoclastogenesis. The suppression of mTORC1 activity by rapamycin in mature osteoclasts enhances bone resorption activity despite the indispensable role of high mTORC1 activation in osteoclast formation in both mouse and human cells. Mechanistically, MYC induces Growth arrest and DNA damage-inducible protein (GADD34) expression and suppresses mTORC1 activity at the late phase of osteoclastogenesis. Taken together, our findings identify a MYC-GADD34 axis as an upstream regulator of dynamic mTORC1 activation in osteoclastogenesis and highlight the interplay between MYC and mTORC1 pathways in determining osteoclast activity.
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Affiliation(s)
- Seyeon Bae
- Arthritis and Tissue Degeneration Program, David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, NY, United States
- Department of Medicine, Weill Cornell Medical College, New York, NY, United States
| | - Brian Oh
- Arthritis and Tissue Degeneration Program, David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, NY, United States
| | - Jefferson Tsai
- Arthritis and Tissue Degeneration Program, David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, NY, United States
| | - Peter Sang Uk Park
- Arthritis and Tissue Degeneration Program, David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, NY, United States
| | | | - Eugenia G. Giannopoulou
- Arthritis and Tissue Degeneration Program, David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, NY, United States
- Biological Sciences Department, New York City College of Technology, City University of New York, Brooklyn, NY, United States
| | - Kyung-Hyun Park-Min
- Arthritis and Tissue Degeneration Program, David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, NY, United States
- Department of Medicine, Weill Cornell Medical College, New York, NY, United States
- BCMB Allied Program, Weill Cornell Graduate School of Medical Sciences, New York, NY, United States
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13
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The Effects of Nutrition on Linear Growth. Nutrients 2022; 14:nu14091752. [PMID: 35565716 PMCID: PMC9100533 DOI: 10.3390/nu14091752] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 04/10/2022] [Accepted: 04/17/2022] [Indexed: 12/16/2022] Open
Abstract
Linear growth is a complex process and is considered one of the best indicators of children’s well-being and health. Genetics, epigenetics and environment (mainly stress and availability of nutrients) are the main regulators of growth. Nutrition exerts its effects on growth throughout the course of life with different, not completely understood mechanisms. Cells have a sophisticated sensing system, which allows growth processes to occur in the presence of an adequate nutrient availability. Most of the nutritional influence on growth is mediated by hormonal signals, in turn sensitive to nutritional cues. Both macro- and micro-nutrients are required for normal growth, as demonstrated by the impairment of growth occurring when their intake is insufficient. Clinical conditions characterized by abnormal nutritional status, including obesity and eating disorders, are associated with alterations of growth pattern, confirming the tight link between growth and nutrition. The precise molecular mechanisms connecting nutrition to linear growth are far from being fully understood and further studies are required. A better understanding of the interplay between nutrients and the endocrine system will allow one to develop more appropriate and effective nutritional interventions for optimizing child growth.
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14
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mTORC1 induces plasma membrane depolarization and promotes preosteoblast senescence by regulating the sodium channel Scn1a. Bone Res 2022; 10:25. [PMID: 35256591 PMCID: PMC8901653 DOI: 10.1038/s41413-022-00204-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 11/16/2021] [Accepted: 01/17/2022] [Indexed: 12/18/2022] Open
Abstract
Senescence impairs preosteoblast expansion and differentiation into functional osteoblasts, blunts their responses to bone formation-stimulating factors and stimulates their secretion of osteoclast-activating factors. Due to these adverse effects, preosteoblast senescence is a crucial target for the treatment of age-related bone loss; however, the underlying mechanism remains unclear. We found that mTORC1 accelerated preosteoblast senescence in vitro and in a mouse model. Mechanistically, mTORC1 induced a change in the membrane potential from polarization to depolarization, thus promoting cell senescence by increasing Ca2+ influx and activating downstream NFAT/ATF3/p53 signaling. We further identified the sodium channel Scn1a as a mediator of membrane depolarization in senescent preosteoblasts. Scn1a expression was found to be positively regulated by mTORC1 upstream of C/EBPα, whereas its permeability to Na+ was found to be gated by protein kinase A (PKA)-induced phosphorylation. Prosenescent stresses increased the permeability of Scn1a to Na+ by suppressing PKA activity and induced depolarization in preosteoblasts. Together, our findings identify a novel pathway involving mTORC1, Scn1a expression and gating, plasma membrane depolarization, increased Ca2+ influx and NFAT/ATF3/p53 signaling in the regulation of preosteoblast senescence. Pharmaceutical studies of the related pathways and agents might lead to novel potential treatments for age-related bone loss.
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15
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Zhang L, Fu X, Ni L, Liu C, Zheng Y, You H, Li M, Xiu C, Zhang L, Gong T, Luo N, Zhang Z, He G, Hu S, Yang H, Chen D, Chen J. Hedgehog Signaling Controls Bone Homeostasis by Regulating Osteogenic/Adipogenic Fate of Skeletal Stem/Progenitor Cells in Mice. J Bone Miner Res 2022; 37:559-576. [PMID: 34870341 DOI: 10.1002/jbmr.4485] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Revised: 11/22/2021] [Accepted: 11/28/2021] [Indexed: 12/14/2022]
Abstract
Skeletal stem/progenitor cells (SSPCs) can differentiate into osteogenic or adipogenic lineage. The mechanism governing lineage allocation of SSPCs is still not completely understood. Hedgehog (Hh) signaling plays an essential role in specifying osteogenic fate of mesenchymal progenitors during embryogenesis. However, it is still unclear whether Hh signaling is required for lineage allocation of SSPCs in postnatal skeleton, and whether its dysregulation is related to age-related osteoporosis. Here, we demonstrated that Hh signaling was activated in metaphyseal SSPCs during osteogenic differentiation in the adult skeleton, and its activity decreased with aging. Inactivation of Hh signaling by genetic ablation of Smo, a key molecule in Hh signaling, in Osx-Cre-targeted SSPCs and hypertrophic chondrocytes led to decreased bone formation and increased bone marrow adiposity, two key pathological features of age-related osteoporosis. Moreover, we found that the bone-fat imbalance phenotype caused by Smo deletion mainly resulted from aberrant allocation of SSPCs toward adipogenic lineage at the expense of osteogenic differentiation, but not due to accelerated transdifferentiation of chondrocytes into adipocytes. Mechanistically, we found that Hh signaling regulated osteoblast versus adipocyte fate of SSPCs partly through upregulating Wnt signaling. Thus, our results indicate that Hh signaling regulates bone homeostasis and age-related osteoporosis by acting as a critical switch of cell fate decisions of Osx-Cre-targeted SSPCs in mice and suggest that Hh signaling may serve as a potential therapeutic target for the treatment of osteoporosis and other metabolic bone diseases. © 2021 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Liwei Zhang
- Orthopedic Department, Taizhou Hospital Affiliated to Wenzhou Medical University, Zhejiang, China.,Orthopedic Institute, Medical College, Soochow University, Suzhou, China
| | - Xuejie Fu
- Orthopedic Institute, Medical College, Soochow University, Suzhou, China
| | - Li Ni
- Department of Orthopaedics, The First Affiliated Hospital of Soochow University, Suzhou, China
| | - Cunchang Liu
- Orthopedic Institute, Medical College, Soochow University, Suzhou, China
| | - Yixin Zheng
- Orthopedic Institute, Medical College, Soochow University, Suzhou, China
| | - Hongji You
- Orthopedic Institute, Medical College, Soochow University, Suzhou, China
| | - Meng Li
- Orthopedic Institute, Medical College, Soochow University, Suzhou, China
| | - Chunmei Xiu
- Orthopedic Institute, Medical College, Soochow University, Suzhou, China
| | - Lei Zhang
- Orthopedic Institute, Medical College, Soochow University, Suzhou, China
| | - Tingting Gong
- Orthopedic Institute, Medical College, Soochow University, Suzhou, China
| | - Na Luo
- Orthopedic Institute, Medical College, Soochow University, Suzhou, China
| | - Zunyi Zhang
- Key Laboratory of Mammalian Organogenesis and Regeneration, Hangzhou Normal University, Zhejiang, China
| | - Guangxu He
- Department of Orthopedics, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Shijun Hu
- Institute for Cardiovascular Science, Medical College, Soochow University, Suzhou, China
| | - Huilin Yang
- Orthopedic Institute, Medical College, Soochow University, Suzhou, China.,Department of Orthopaedics, The First Affiliated Hospital of Soochow University, Suzhou, China
| | - Di Chen
- Faculty of Pharmaceutical Sciences, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Jianquan Chen
- Orthopedic Institute, Medical College, Soochow University, Suzhou, China.,Department of Orthopaedics, The First Affiliated Hospital of Soochow University, Suzhou, China
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16
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Wang X, Zhang X, Han Y, Duan X, Wang J, Yan H, Wang S, Xu Y, Zhu Z, Wang L, Huang Y, Lin Q, Tan X, Zhuo J, Zhang H, Mao M, Gou W, Yi Z, Li X. Role of the major histocompatibility complex class II protein presentation pathway in bone immunity imbalance in postmenopausal osteoporosis. Front Endocrinol (Lausanne) 2022; 13:876067. [PMID: 36034452 PMCID: PMC9402988 DOI: 10.3389/fendo.2022.876067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 07/13/2022] [Indexed: 11/13/2022] Open
Abstract
Bone immunity regulates osteoclast differentiation and bone resorption and is a potential target for the treatment of postmenopausal osteoporosis (PMOP). The molecular network between bone metabolism and the immune system is complex. However, the molecular mechanism underlying the involvement of the major histocompatibility complex class II (MHC-II) molecule protein presentation pathway in PMOP remains to be elucidated. The MHC-II molecule is a core molecule of the protein presentation pathway. It is combined with the processed short peptide and presented to T lymphocytes, thereby activating them to become effector T cells. T-cell-derived inflammatory factors promote bone remodeling in PMOP. Moreover, the MHC-II molecule is highly expressed in osteoclast precursors. MHC-II transactivator (CIITA) is the main regulator of MHC-II gene expression and the switch for protein presentation. CIITA is also a major regulator of osteoclast differentiation and bone homeostasis. Therefore, we hypothesized that the MHC-II promotes osteoclast differentiation, providing a novel pathogenic mechanism and a potential target for the treatment of PMOP.
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Affiliation(s)
- Xiaoning Wang
- College of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Xin Zhang
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Yidan Han
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Xinwei Duan
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Jianchang Wang
- College of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Hui Yan
- College of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Shanshan Wang
- College of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Yunteng Xu
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Zaishi Zhu
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Lili Wang
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
- Fujian Key Laboratory of Integrative Medicine on Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Yanfeng Huang
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Qing Lin
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Xue Tan
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Junkuan Zhuo
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Haifeng Zhang
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Min Mao
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Weiying Gou
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Zhouping Yi
- Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
| | - Xihai Li
- College of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, China
- Fujian Key Laboratory of Integrative Medicine on Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, China
- *Correspondence: Xihai Li,
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17
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Filik Y, Bauer K, Hadzijusufovic E, Haider P, Greiner G, Witzeneder N, Hoermann G, Hohensinner PJ, Gleixner KV, Wojta J, Sperr WR, Valent P. PI3-kinase inhibition as a strategy to suppress the leukemic stem cell niche in Ph+ chronic myeloid leukemia. Am J Cancer Res 2021; 11:6042-6059. [PMID: 35018241 PMCID: PMC8727792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 11/03/2021] [Indexed: 06/14/2023] Open
Abstract
Recent data suggest that the disease-associated microenvironment, known as the leukemic stem cell (LSC) niche, is substantially involved in drug resistance of LSC in BCR-ABL1+ chronic myeloid leukemia (CML). Attacking the LSC niche in CML may thus be an effective approach to overcome drug resistance. We have recently shown that osteoblasts are a major site of niche-mediated LSC resistance against second- and third-generation tyrosine kinase inhibitors (TKI) in CML. In the present study, we screened for drugs that are capable of suppressing the growth and viability of osteoblasts and/or other niche cells and can thereby overcome TKI resistance of CML LSC. Proliferation was analyzed by determining 3H-thymidine uptake in niche-related cells, and apoptosis was measured by Annexin-V/DAPI-staining and flow cytometry. We found that the dual PI3 kinase (PI3K) and mTOR inhibitor BEZ235 and the selective pan-PI3K inhibitor copanlisib suppress proliferation of primary osteoblasts (BEZ235 IC50: 0.05 μM; copanlisib IC50: 0.05 μM), the osteoblast cell line CAL-72 (BEZ235 IC50: 0.5 μM; copanlisib IC50: 1 μM), primary umbilical vein-derived endothelial cells (BEZ235 IC50: 0.5 μM; copanlisib IC50: 0.5 μM), and the vascular endothelial cell line HMEC-1 (BEZ235 IC50: 1 μM; copanlisib IC50: 1 μM), whereas no comparable effects were seen with the mTOR inhibitor rapamycin. Furthermore, we show that BEZ235 and copanlisib cooperate with nilotinib and ponatinib in suppressing proliferation and survival of osteoblasts and endothelial cells. Finally, BEZ235 and copanlisib were found to overcome osteoblast-mediated resistance against nilotinib and ponatinib in K562 cells, KU812 cells and primary CD34+/CD38- CML LSC. Together, targeting osteoblastic niche cells through PI3K inhibition may be a new effective approach to overcome niche-induced TKI resistance in CML. Whether this approach can be translated into clinical application and can counteract drug resistance of LSC in patients with CML remains to be determined in clinical trials.
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Affiliation(s)
- Yüksel Filik
- Ludwig Boltzmann Institute for Hematology and Oncology, Medical University of ViennaVienna, Austria
- Department of Internal Medicine I, Division of Hematology and Hemostaseology, Medical University of ViennaVienna, Austria
| | - Karin Bauer
- Ludwig Boltzmann Institute for Hematology and Oncology, Medical University of ViennaVienna, Austria
- Department of Internal Medicine I, Division of Hematology and Hemostaseology, Medical University of ViennaVienna, Austria
| | - Emir Hadzijusufovic
- Ludwig Boltzmann Institute for Hematology and Oncology, Medical University of ViennaVienna, Austria
- Department of Internal Medicine I, Division of Hematology and Hemostaseology, Medical University of ViennaVienna, Austria
- Department/Clinic for Companion Animals and Horses, Clinic for Small Animals, Clinical Unit of Internal Medicine, University of Veterinary Medicine ViennaVienna, Austria
| | - Patrick Haider
- Department of Internal Medicine II, Division of Cardiology, Medical University of ViennaVienna, Austria
| | - Georg Greiner
- Ludwig Boltzmann Institute for Hematology and Oncology, Medical University of ViennaVienna, Austria
- Department of Laboratory Medicine, Medical University of ViennaVienna, Austria
- Ihr Labor, Medical Diagnostic LaboratoriesVienna, Austria
| | - Nadine Witzeneder
- Ludwig Boltzmann Institute for Hematology and Oncology, Medical University of ViennaVienna, Austria
- Department of Laboratory Medicine, Medical University of ViennaVienna, Austria
| | - Gregor Hoermann
- Ludwig Boltzmann Institute for Hematology and Oncology, Medical University of ViennaVienna, Austria
- Department of Laboratory Medicine, Medical University of ViennaVienna, Austria
- MLL Munich Leukemia LaboratoryMunich, Germany
| | - Philipp J Hohensinner
- Department of Internal Medicine II, Division of Cardiology, Medical University of ViennaVienna, Austria
| | - Karoline V Gleixner
- Ludwig Boltzmann Institute for Hematology and Oncology, Medical University of ViennaVienna, Austria
- Department of Internal Medicine I, Division of Hematology and Hemostaseology, Medical University of ViennaVienna, Austria
| | - Johann Wojta
- Department of Internal Medicine II, Division of Cardiology, Medical University of ViennaVienna, Austria
- Ludwig Boltzmann Institute for Cardiovascular Research, Medical University of ViennaVienna, Austria
| | - Wolfgang R Sperr
- Ludwig Boltzmann Institute for Hematology and Oncology, Medical University of ViennaVienna, Austria
- Department of Internal Medicine I, Division of Hematology and Hemostaseology, Medical University of ViennaVienna, Austria
| | - Peter Valent
- Ludwig Boltzmann Institute for Hematology and Oncology, Medical University of ViennaVienna, Austria
- Department of Internal Medicine I, Division of Hematology and Hemostaseology, Medical University of ViennaVienna, Austria
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18
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Lojk J, Marc J. Roles of Non-Canonical Wnt Signalling Pathways in Bone Biology. Int J Mol Sci 2021; 22:10840. [PMID: 34639180 PMCID: PMC8509327 DOI: 10.3390/ijms221910840] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/01/2021] [Accepted: 10/05/2021] [Indexed: 01/15/2023] Open
Abstract
The Wnt signalling pathway is one of the central signalling pathways in bone development, homeostasis and regulation of bone mineral density. It consists of numerous Wnt ligands, receptors and co-receptors, which ensure tight spatiotemporal regulation of Wnt signalling pathway activity and thus tight regulation of bone tissue homeostasis. This enables maintenance of optimal mineral density, tissue healing and adaptation to changes in bone loading. While the role of the canonical/β-catenin Wnt signalling pathway in bone homeostasis is relatively well researched, Wnt ligands can also activate several non-canonical, β-catenin independent signalling pathways with important effects on bone tissue. In this review, we will provide a thorough overview of the current knowledge on different non-canonical Wnt signalling pathways involved in bone biology, focusing especially on the pathways that affect bone cell differentiation, maturation and function, processes involved in bone tissue structure regulation. We will describe the role of the two most known non-canonical pathways (Wnt/planar cell polarity pathways and Wnt/Ca2+ pathway), as well as other signalling pathways with a strong role in bone biology that communicate with the Wnt signalling pathway through non-canonical Wnt signalling. Our goal is to bring additional attention to these still not well researched but important pathways in the regulation of bone biology in the hope of prompting additional research in the area of non-canonical Wnt signalling pathways.
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Affiliation(s)
- Jasna Lojk
- Department of Clinical Biochemistry, Faculty of Pharmacy, University of Ljubljana, 1000 Ljubljana, Slovenia;
| | - Janja Marc
- Department of Clinical Biochemistry, Faculty of Pharmacy, University of Ljubljana, 1000 Ljubljana, Slovenia;
- University Clinical Center Ljubljana, Clinical Department of Clinical Chemistry and Biochemistry, 1000 Ljubljana, Slovenia
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19
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Parikh P, Semba R, Manary M, Swaminathan S, Udomkesmalee E, Bos R, Poh BK, Rojroongwasinkul N, Geurts J, Sekartini R, Nga TT. Animal source foods, rich in essential amino acids, are important for linear growth and development of young children in low- and middle-income countries. MATERNAL AND CHILD NUTRITION 2021; 18:e13264. [PMID: 34467645 PMCID: PMC8710096 DOI: 10.1111/mcn.13264] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 07/02/2021] [Accepted: 08/02/2021] [Indexed: 11/28/2022]
Abstract
Growth faltering under 5 years of age is unacceptably high worldwide, and even more children, while not stunted, fail to reach their growth potential. The time between conception and 2 years of age is critical for development. The period from 6 to 23 months, when complementary foods are introduced, coincides with a time when growth faltering and delayed neurocognitive developments are most common. Fortunately, this is also the period when diet exercises its greatest influence. Growing up in an adverse environment, with a deficient diet, as typically seen in low‐ and middle‐income countries (LMICs), hampers growth and development of children and prevents them from realising their full developmental and economic future potential. Sufficient nutrient availability and utilisation are paramount to a child's growth and development trajectory, especially in the period after breastfeeding. This review highlights the importance of essential amino acids (EAAs) in early life for linear growth and, likely, neurocognitive development. The paper further discusses signalling through mammalian target of rapamycin complex 1 (mTORC1) as one of the main amino acid (AA)‐sensing hubs and the master regulator of both growth and neurocognitive development. Children in LMICs, despite consuming sufficient total protein, do not meet their EAA requirements due to poor diet diversity and low‐quality dietary protein. AA deficiencies in early life can cause reductions in linear growth and cognition. Ensuring AA adequacy in diets, particularly through inclusion of nutrient‐dense animal source foods from 6 to 23 months, is strongly encouraged in LMICs in order to compensate for less than optimal growth during complementary feeding.
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Affiliation(s)
| | - Richard Semba
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Mark Manary
- Department of Paediatrics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Sumathi Swaminathan
- St John's Research Institute, St John's National Academy of Health Sciences, Bangalore, Karnataka, India
| | | | - Rolf Bos
- FrieslandCampina, Amersfoort, The Netherlands
| | - Bee Koon Poh
- Nutritional Sciences Programme & Centre for Community Health, Faculty of Health Sciences, University Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | | | - Jan Geurts
- FrieslandCampina, Amersfoort, The Netherlands
| | - Rini Sekartini
- Faculty of Medicine, Department of Pediatrics, University of Indonesia and Cipto Mangunkusumo Hospital, Jakarta, Indonesia
| | - Tran Thuy Nga
- Department of Occupational and School Nutrition, National Institute of Nutrition (NIN), Hanoi, Vietnam
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20
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Wu D, Cline-Smith A, Shashkova E, Perla A, Katyal A, Aurora R. T-Cell Mediated Inflammation in Postmenopausal Osteoporosis. Front Immunol 2021; 12:687551. [PMID: 34276675 PMCID: PMC8278518 DOI: 10.3389/fimmu.2021.687551] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 06/04/2021] [Indexed: 12/11/2022] Open
Abstract
Osteoporosis is the most prevalent metabolic bone disease that affects half the women in the sixth and seventh decade of life. Osteoporosis is characterized by uncoupled bone resorption that leads to low bone mass, compromised microarchitecture and structural deterioration that increases the likelihood of fracture with minimal trauma, known as fragility fractures. Several factors contribute to osteoporosis in men and women. In women, menopause - the cessation of ovarian function, is one of the leading causes of primary osteoporosis. Over the past three decades there has been growing appreciation that the adaptive immune system plays a fundamental role in the development of postmenopausal osteoporosis, both in humans and in mouse models. In this review, we highlight recent data on the interactions between T cells and the skeletal system in the context of postmenopausal osteoporosis. Finally, we review recent studies on the interventions to ameliorate osteoporosis.
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Affiliation(s)
| | | | | | | | | | - Rajeev Aurora
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, St. Louis, MO, United States
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21
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Gao Q, Hou Y, Li Z, Hu J, Huo D, Zheng H, Zhang J, Yao X, Gao R, Wu X, Sui L. mTORC2 regulates hierarchical micro/nano topography-induced osteogenic differentiation via promoting cell adhesion and cytoskeletal polymerization. J Cell Mol Med 2021; 25:6695-6708. [PMID: 34114337 PMCID: PMC8278073 DOI: 10.1111/jcmm.16672] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Revised: 04/16/2021] [Accepted: 05/08/2021] [Indexed: 12/12/2022] Open
Abstract
Surface topography acts as an irreplaceable role in the long‐term success of intraosseous implants. In this study, we prepared the hierarchical micro/nano topography using selective laser melting combined with alkali heat treatment (SLM‐AHT) and explored the underlying mechanism of SLM‐AHT surface‐elicited osteogenesis. Our results show that cells cultured on SLM‐AHT surface possess the largest number of mature FAs and exhibit a cytoskeleton reorganization compared with control groups. SLM‐AHT surface could also significantly upregulate the expression of the cell adhesion‐related molecule p‐FAK, the osteogenic differentiation‐related molecules RUNX2 and OCN as well as the mTORC2 signalling pathway key molecule Rictor. Notably, after the knocked‐down of Rictor, there were no longer significant differences in the gene expression levels of the cell adhesion‐related molecules and osteogenic differentiation‐related molecules among the three titanium surfaces, and the cells on SLM‐AHT surface failed to trigger cytoskeleton reorganization. In conclusion, the results suggest that mTORC2 can regulate the hierarchical micro/nano topography‐mediated osteogenesis via cell adhesion and cytoskeletal reorganization.
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Affiliation(s)
- Qian Gao
- Department of Prosthodontics, Tianjin Medical University School and Hospital of Stomatology, Tianjin, China.,Tianjin Key Laboratory of Medical Epigenetics, Department of Cell Biology, 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics, Tianjin Medical University, Tianjin, China
| | - Yuying Hou
- Tianjin Key Laboratory of Medical Epigenetics, Department of Cell Biology, 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics, Tianjin Medical University, Tianjin, China
| | - Zhe Li
- Department of Prosthodontics, Tianjin Medical University School and Hospital of Stomatology, Tianjin, China
| | - Jinyang Hu
- Tianjin Key Laboratory of Medical Epigenetics, Department of Cell Biology, 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics, Tianjin Medical University, Tianjin, China.,Department of Neurosurgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Dawei Huo
- Tianjin Key Laboratory of Medical Epigenetics, Department of Cell Biology, 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics, Tianjin Medical University, Tianjin, China
| | - Huimin Zheng
- Department of Prosthodontics, Tianjin Medical University School and Hospital of Stomatology, Tianjin, China.,Tianjin Key Laboratory of Medical Epigenetics, Department of Cell Biology, 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics, Tianjin Medical University, Tianjin, China
| | - Junjiang Zhang
- Department of Prosthodontics, Tianjin Medical University School and Hospital of Stomatology, Tianjin, China
| | - Xiaoyu Yao
- Department of Prosthodontics, Tianjin Medical University School and Hospital of Stomatology, Tianjin, China
| | - Rui Gao
- International Education College, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Xudong Wu
- Tianjin Key Laboratory of Medical Epigenetics, Department of Cell Biology, 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics, Tianjin Medical University, Tianjin, China
| | - Lei Sui
- Department of Prosthodontics, Tianjin Medical University School and Hospital of Stomatology, Tianjin, China
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22
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Tangseefa P, Martin SK, Arthur A, Panagopoulos V, Page AJ, Wittert GA, Proud CG, Fitter S, Zannettino ACW. Deletion of Rptor in Preosteoblasts Reveals a Role for the Mammalian Target of Rapamycin Complex 1 (mTORC1) Complex in Dietary-Induced Changes to Bone Mass and Glucose Homeostasis in Female Mice. JBMR Plus 2021; 5:e10486. [PMID: 33977204 PMCID: PMC8101617 DOI: 10.1002/jbm4.10486] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 02/22/2021] [Accepted: 02/28/2021] [Indexed: 12/11/2022] Open
Abstract
The mammalian target of rapamycin complex 1 (mTORC1) complex is the major nutrient sensor in mammalian cells that responds to amino acids, energy levels, growth factors, and hormones, such as insulin, to control anabolic and catabolic processes. We have recently shown that suppression of the mTORC1 complex in bone‐forming osteoblasts (OBs) improved glucose handling in male mice fed a normal or obesogenic diet. Mechanistically, this occurs, at least in part, by increasing OB insulin sensitivity leading to upregulation of glucose uptake and glycolysis. Given previously reported sex‐dependent differences observed upon antagonism of mTORC1 signaling, we investigated the metabolic and skeletal effects of genetic inactivation of preosteoblastic‐mTORC1 in female mice. Eight‐week‐old control diet (CD)‐fed Rptorob−/− mice had a low bone mass with a significant reduction in trabecular bone volume and trabecular number, reduced cortical bone thickness, and increased marrow adiposity. Despite no changes in body composition, CD‐fed Rptorob−/− mice exhibited significant lower fasting insulin and glucose levels and increased insulin sensitivity. Upon high‐fat diet (HFD) feeding, Rptorob−/− mice were resistant to a diet‐induced increase in whole‐body and total fat mass and protected from the development of diet‐induced insulin resistance. Notably, although 12 weeks of HFD increased marrow adiposity, with minimal changes in both trabecular and cortical bone in the female control mice, marrow adiposity was significantly reduced in HFD‐fed Rptorob−/− compared to both HFD‐fed control and CD‐fed Rptorob−/− mice. Collectively, our results demonstrate that mTORC1 function in preosteoblasts is crucial for skeletal development and skeletal regulation of glucose homeostasis in both male and female mice. Importantly, loss of mTORC1 function in OBs results in metabolic and physiological adaptations that mirror a caloric restriction phenotype (under CD) and protects against HFD‐induced obesity, associated insulin resistance, and marrow adiposity expansion. These results highlight the critical contribution of the skeleton in the regulation of whole‐body energy homeostasis. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Pawanrat Tangseefa
- Adelaide Medical School, Faculty of Health and Medical Science University of Adelaide Adelaide South Australia Australia.,Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute Adelaide South Australia Australia
| | - Sally K Martin
- Adelaide Medical School, Faculty of Health and Medical Science University of Adelaide Adelaide South Australia Australia.,Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute Adelaide South Australia Australia
| | - Agnieszka Arthur
- Adelaide Medical School, Faculty of Health and Medical Science University of Adelaide Adelaide South Australia Australia.,Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute Adelaide South Australia Australia
| | - Vasilios Panagopoulos
- Adelaide Medical School, Faculty of Health and Medical Science University of Adelaide Adelaide South Australia Australia.,Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute Adelaide South Australia Australia
| | - Amanda J Page
- Adelaide Medical School, Faculty of Health and Medical Science University of Adelaide Adelaide South Australia Australia.,Nutrition, Diabetes & Gut Health Program, Lifelong Health Theme, South Australian Health and Medical Research Institute Adelaide South Australia Australia
| | - Gary A Wittert
- Adelaide Medical School, Faculty of Health and Medical Science University of Adelaide Adelaide South Australia Australia.,Nutrition, Diabetes & Gut Health Program, Lifelong Health Theme, South Australian Health and Medical Research Institute Adelaide South Australia Australia.,Freemasons Foundation Centre for Men's Health University of Adelaide Adelaide South Australia Australia
| | - Christopher G Proud
- Nutrition, Diabetes & Gut Health Program, Lifelong Health Theme, South Australian Health and Medical Research Institute Adelaide South Australia Australia.,School of Biological Sciences, University of Adelaide Adelaide South Australia Australia
| | - Stephen Fitter
- Adelaide Medical School, Faculty of Health and Medical Science University of Adelaide Adelaide South Australia Australia.,Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute Adelaide South Australia Australia
| | - Andrew C W Zannettino
- Adelaide Medical School, Faculty of Health and Medical Science University of Adelaide Adelaide South Australia Australia.,Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute Adelaide South Australia Australia.,Central Adelaide Local Health Network Adelaide South Australia Australia
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23
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The mTORC1 complex in pre-osteoblasts regulates whole-body energy metabolism independently of osteocalcin. Bone Res 2021; 9:10. [PMID: 33551450 PMCID: PMC7868369 DOI: 10.1038/s41413-020-00123-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 09/23/2020] [Accepted: 10/26/2020] [Indexed: 12/13/2022] Open
Abstract
Overnutrition causes hyperactivation of mTORC1-dependent negative feedback loops leading to the downregulation of insulin signaling and development of insulin resistance. In osteoblasts (OBs), insulin signaling plays a crucial role in the control of systemic glucose homeostasis. We utilized mice with conditional deletion of Rptor to investigate how the loss of mTORC1 function in OB affects glucose metabolism under normal and overnutrition dietary states. Compared to the controls, chow-fed Rptorob−/− mice had substantially less fat mass and exhibited adipocyte hyperplasia. Remarkably, upon feeding with high-fat diet, mice with pre- and post-natal deletion of Rptor in OBs were protected from diet-induced obesity and exhibited improved glucose metabolism with lower fasting glucose and insulin levels, increased glucose tolerance and insulin sensitivity. This leanness and resistance to weight gain was not attributable to changes in food intake, physical activity or lipid absorption but instead was due to increased energy expenditure and greater whole-body substrate flexibility. RNA-seq revealed an increase in glycolysis and skeletal insulin signaling pathways, which correlated with the potentiation of insulin signaling and increased insulin-dependent glucose uptake in Rptor-knockout osteoblasts. Collectively, these findings point to a critical role for the mTORC1 complex in the skeletal regulation of whole-body glucose metabolism and the skeletal development of insulin resistance.
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24
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Shen L, Sharma D, Yu Y, Long F, Karner CM. Biphasic regulation of glutamine consumption by WNT during osteoblast differentiation. J Cell Sci 2021; 134:jcs251645. [PMID: 33262314 PMCID: PMC7823158 DOI: 10.1242/jcs.251645] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 11/19/2020] [Indexed: 01/01/2023] Open
Abstract
Osteoblasts are the principal bone-forming cells. As such, osteoblasts have enhanced demand for amino acids to sustain high rates of matrix synthesis associated with bone formation. The precise systems utilized by osteoblasts to meet these synthetic demands are not well understood. WNT signaling is known to rapidly stimulate glutamine uptake during osteoblast differentiation. Using a cell biology approach, we identified two amino acid transporters, γ(+)-LAT1 and ASCT2 (encoded by Slc7a7 and Slc1a5, respectively), as the primary transporters of glutamine in response to WNT. ASCT2 mediates the majority of glutamine uptake, whereas γ(+)-LAT1 mediates the rapid increase in glutamine uptake in response to WNT. Mechanistically, WNT signals through the canonical β-catenin (CTNNB1)-dependent pathway to rapidly induce Slc7a7 expression. Conversely, Slc1a5 expression is regulated by the transcription factor ATF4 downstream of the mTORC1 pathway. Targeting either Slc1a5 or Slc7a7 using shRNA reduced WNT-induced glutamine uptake and prevented osteoblast differentiation. Collectively, these data highlight the critical nature of glutamine transport for WNT-induced osteoblast differentiation.This article has an associated First Person interview with the joint first authors of the paper.
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Affiliation(s)
- Leyao Shen
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC 27710, USA
| | - Deepika Sharma
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC 27710, USA
| | - Yilin Yu
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC 27710, USA
| | - Fanxin Long
- Translational Research Program in Pediatric Orthopaedics, The Children's Hospital of Philadelphia, Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Courtney M Karner
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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25
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Myeloma Cells Deplete Bone Marrow Glutamine and Inhibit Osteoblast Differentiation Limiting Asparagine Availability. Cancers (Basel) 2020; 12:cancers12113267. [PMID: 33167336 PMCID: PMC7694402 DOI: 10.3390/cancers12113267] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 11/02/2020] [Accepted: 11/03/2020] [Indexed: 12/16/2022] Open
Abstract
Simple Summary Osteolytic bone lesions represent an important clinical feature of multiple myeloma (MM). MM cells metabolize very high amounts of glutamine (Gln) and significantly lower Gln in the bone marrow. In this contribution we demonstrate that MM-dependent Gln depletion impairs the differentiation of bone marrow mesenchymal stromal cells into osteoblasts, the cells that form new bone tissue. We also found that osteoblast differentiation is associated with increased expression of glutaminase, the main enzyme that metabolizes Gln, SNAT2, a transporter able to accumulate Gln into the cells, and asparagine synthetase, the enzyme that uses Gln to obtain asparagine (Asn). Asn rescued osteoblast differentiation of Gln-starved mesenchymal stromal cells. These results demonstrate that MM cells impair osteoblast differentiation, hindering mesenchymal Asn synthesis through Gln depletion. Besides providing a metabolic mechanism underlying osteolytic lesions in MM, these results suggest that Asn supplementation may prevent bone disease in MM patients. Abstract Multiple myeloma (MM) cells consume huge amounts of glutamine and, as a consequence, the amino acid concentration is lower-than-normal in the bone marrow (BM) of MM patients. Here we show that MM-dependent glutamine depletion induces glutamine synthetase in stromal cells, as demonstrated in BM biopsies of MM patients, and reproduced in vitro by co-culturing human mesenchymal stromal cells (MSCs) with MM cells. Moreover, glutamine depletion hinders osteoblast differentiation of MSCs, which is also severely blunted by the spent, low-glutamine medium of MM cells, and rescued by glutamine restitution. Glutaminase and the concentrative glutamine transporter SNAT2 are induced during osteoblastogenesis in vivo and in vitro, and both needed for MSCs differentiation, pointing to enhanced the requirement for the amino acid. Osteoblastogenesis also triggers the induction of glutamine-dependent asparagine synthetase (ASNS), and, among non-essential amino acids, asparagine rescues differentiation of glutamine-starved MSCs, by restoring the transcriptional profiles of differentiating MSCs altered by glutamine starvation. Thus, reduced asparagine availability provides a mechanistic link between MM-dependent Gln depletion in BM and impairment of osteoblast differentiation. Inhibition of Gln metabolism in MM cells and supplementation of asparagine to stromal cells may, therefore, constitute novel approaches to prevent osteolytic lesions in MM.
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26
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Small Molecule–Mediated Enhanced Osteogenesis of Human Mesenchymal Stem Cells: a Probable Alternate for BMP-2. REGENERATIVE ENGINEERING AND TRANSLATIONAL MEDICINE 2020. [DOI: 10.1007/s40883-020-00179-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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27
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Pal S, Rashid M, Singh SK, Porwal K, Singh P, Mohamed R, Gayen JR, Wahajuddin M, Chattopadhyay N. Skeletal restoration by phosphodiesterase 5 inhibitors in osteopenic mice: Evidence of osteoanabolic and osteoangiogenic effects of the drugs. Bone 2020; 135:115305. [PMID: 32126313 DOI: 10.1016/j.bone.2020.115305] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 02/12/2020] [Accepted: 02/28/2020] [Indexed: 12/16/2022]
Abstract
Phosphodiesterases (PDEs) hydrolyze cyclic nucleotides and thereby regulate diverse cellular functions. The reports on the skeletal effects of PDE inhibitors are conflicting. Here, we screened 17 clinically used non-xanthine PDE inhibitors (selective and non-selective) using mouse calvarial osteoblasts (MCO) where the readout was osteoblast differentiation. From this screen, we identified sildenafil and vardenafil (both PDE5 inhibitors) having the least osteogenic EC50. Both drugs significantly increased vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2) expressions in MCO and the nitric oxide synthase inhibitor L-NAME completely blocked VEGF expression induced by these drugs. Sunitinib, a tyrosine receptor kinase inhibitor that also blocks VEGFR2 blocked sildenafil-/vardenafil-induced osteoblast differentiation. At half of their human equivalent doses, i.e. 6.0 mg/kg sildenafil and 2.5 mg/kg vardenafil, the maximum bone marrow level of sildenafil was 32% and vardenafil was 21% of their blood levels. At these doses, both drugs enhanced bone regeneration at the femur osteotomy site and completely restored bone mass, microarchitecture, and strength in OVX mice. Furthermore, both drugs increased surface referent bone formation and serum bone formation marker (P1NP) without affecting the resorption marker (CTX-1). Both drugs increased the expression of VEGF and VEGFR2 in bones and osteoblasts and increased skeletal vascularity. Sunitinib completely blocked the bone restorative and vascular effects of sildenafil and vardenafil in OVX mice. Taken together, our study suggested that sildenafil and vardenafil at half of their adult human doses completely reversed osteopenia in OVX mice by an osteogenic mechanism that was associated with enhanced skeletal vascularity.
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Affiliation(s)
- Subhashis Pal
- Division of Endocrinology, Central Drug Research Institute (CDRI), Council of Scientific and Industrial Research (CSIR), Lucknow 226031, India
| | - Mamunur Rashid
- Pharmaceutics & Pharmacokinetics Division, CDRI-CSIR, Lucknow 226031, India
| | | | - Konica Porwal
- Division of Endocrinology, Central Drug Research Institute (CDRI), Council of Scientific and Industrial Research (CSIR), Lucknow 226031, India
| | - Priya Singh
- Division of Endocrinology, Central Drug Research Institute (CDRI), Council of Scientific and Industrial Research (CSIR), Lucknow 226031, India
| | - Riyazuddin Mohamed
- Pharmaceutics & Pharmacokinetics Division, CDRI-CSIR, Lucknow 226031, India
| | - Jiaur R Gayen
- Pharmaceutics & Pharmacokinetics Division, CDRI-CSIR, Lucknow 226031, India
| | | | - Naibedya Chattopadhyay
- Division of Endocrinology, Central Drug Research Institute (CDRI), Council of Scientific and Industrial Research (CSIR), Lucknow 226031, India.
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28
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Liu GB, Pan YM, Liu YS, Hu JH, Zhang XD, Zhang DW, Wang Y, Feng YK, Yu JB, Cheng YX. Ghrelin promotes neural differentiation of adipose tissue-derived mesenchymal stem cell via AKT/mTOR and β-catenin signaling pathways. Kaohsiung J Med Sci 2020; 36:405-416. [PMID: 32003536 DOI: 10.1002/kjm2.12188] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 01/07/2020] [Indexed: 02/04/2023] Open
Abstract
Adipose tissue-derived mesenchymal stem cells (ADSCs) are multipotent cells that can differentiate into various cell types. This study aimed to investigate the effect of ghrelin on the neural differentiation of rat ADSCs and underlying molecular mechanisms. Rat ADSCs were isolated and third-passage ADSCs were used in this study. The isolated ADSCs were characterized by flow cytometry analysis for MSCs' surface expression markers as evidenced by positive for CD90, CD44, and CD29 and negative for CD34, CD45, and CD11b/2f/c. The multilineage differentiation of ADSCs was confirmed by adipogenic, osteogenic, and neural differentiation. After induction of neurogenesis, the differentiated cells were identified by development of neuron-like morphology and expression of neural markers including glial fibrillary acidic protein, Nestin, MAP2, and β-Tubulin III using immunofluorescence and western blot. Ghrelin concentration dependently elevated the proportion of neural-like cells and branching dendrites, as well as upregulated the expression of neural markers. Further, the expression of nuclear β-catenin, p-GSK-3β, p-AKT, and p-mTOR was increased by ghrelin, indicating an activation of β-catenin and AKT/mTOR signaling after the ghrelin treatment. Importantly, inhibition of β-catenin or AKT/mTOR signaling suppressed ghrelin-induced neurogenesis. Therefore, we demonstrate that ghrelin promotes neural differentiation of ADSCs through the activation of β-catenin and AKT/mTOR signaling pathways.
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Affiliation(s)
- Gui-Bo Liu
- Department of Anatomy, School of Basic Medical Sciences, Mudanjiang Medical College, Mudanjiang, People's Republic of China.,Institute of Neural Tissue Engineering, Mudanjiang Medical College, Mudanjiang, People's Republic of China
| | - Yan-Ming Pan
- Department of Anatomy, School of Basic Medical Sciences, Mudanjiang Medical College, Mudanjiang, People's Republic of China.,Key Laboratory of Cancer Prevention and Treatment of Heilongjiang Province, Mudanjiang Medical College, Mudanjiang, People's Republic of China
| | - Yun-Shuang Liu
- Department of Medical Imaging, Hongqi Hospital of Mudanjiang Medical College, Mudanjiang, People's Republic of China
| | - Jia-Hang Hu
- Department of Medical Imaging, Hongqi Hospital of Mudanjiang Medical College, Mudanjiang, People's Republic of China
| | - Xiao-Dong Zhang
- Department of Infectious Diseases, Hongqi Hospital of Mudanjiang Medical College, Mudanjiang, People's Republic of China
| | - Da-Wei Zhang
- Department of Anatomy, School of Basic Medical Sciences, Mudanjiang Medical College, Mudanjiang, People's Republic of China
| | - Ying Wang
- Department of Anatomy, School of Basic Medical Sciences, Mudanjiang Medical College, Mudanjiang, People's Republic of China.,Institute of Neural Tissue Engineering, Mudanjiang Medical College, Mudanjiang, People's Republic of China
| | - Yu-Kuan Feng
- Department of Anatomy, School of Basic Medical Sciences, Mudanjiang Medical College, Mudanjiang, People's Republic of China
| | - Jian-Bo Yu
- Key Laboratory of Cancer Prevention and Treatment of Heilongjiang Province, Mudanjiang Medical College, Mudanjiang, People's Republic of China.,Pathology Diagnosis Center, The First Clinical Medical School of Mudanjiang Medical College, Mudanjiang, People's Republic of China
| | - Yong-Xia Cheng
- Key Laboratory of Cancer Prevention and Treatment of Heilongjiang Province, Mudanjiang Medical College, Mudanjiang, People's Republic of China.,Pathology Diagnosis Center, The First Clinical Medical School of Mudanjiang Medical College, Mudanjiang, People's Republic of China.,Institute of Stem Cells, Mudanjiang Medical College, Mudanjiang, People's Republic of China
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Salt-inducible kinase 1 regulates bone anabolism via the CRTC1-CREB-Id1 axis. Cell Death Dis 2019; 10:826. [PMID: 31672960 PMCID: PMC6823377 DOI: 10.1038/s41419-019-1915-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 07/21/2019] [Accepted: 08/20/2019] [Indexed: 12/11/2022]
Abstract
New bone anabolic agents for the effective treatment of bone metabolic diseases like osteoporosis are of high clinical demand. In the present study, we reveal the function of salt-inducible kinase 1 (SIK1) in regulating osteoblast differentiation. Gene knockdown of SIK1 but not of SIK2 or SIK3 expression in primary preosteoblasts increased osteoblast differentiation and bone matrix mineralization. SIK1 also regulated the proliferation of osteoblastic precursor cells in osteogenesis. This negative control of osteoblasts required the catalytic activity of SIK1. SIK1 phosphorylated CREB regulated transcription coactivator 1 (CRTC1), preventing CRTC1 from enhancing CREB transcriptional activity for the expression of osteogenic genes like Id1. Furthermore, SIK1 knockout (KO) mice had higher bone mass, osteoblast number, and bone formation rate versus littermate wild-type (WT) mice. Preosteoblasts from SIK1 KO mice showed more osteoblastogenic potential than did WT cells, whereas osteoclast generation among KO and WT precursors was indifferent. In addition, bone morphogenic protein 2 (BMP2) suppressed both SIK1 expression as well as SIK1 activity by protein kinase A (PKA)–dependent mechanisms to stimulate osteogenesis. Taken together, our results indicate that SIK1 is a key negative regulator of preosteoblast proliferation and osteoblast differentiation and that the repression of SIK1 is crucial for BMP2 signaling for osteogenesis. Therefore, we propose SIK1 to be a useful therapeutic target for the development of bone anabolic strategies.
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30
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Miyamoto H, Sawaji Y, Iwaki T, Masaoka T, Fukada E, Date M, Yamamoto K. Intermittent pulsed electromagnetic field stimulation activates the mTOR pathway and stimulates the proliferation of osteoblast‐like cells. Bioelectromagnetics 2019; 40:412-421. [DOI: 10.1002/bem.22207] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 06/26/2019] [Indexed: 02/04/2023]
Affiliation(s)
- Hironori Miyamoto
- Department of Orthopedic SurgeryTokyo Medical University Tokyo Japan
| | - Yasunobu Sawaji
- Department of Orthopedic SurgeryTokyo Medical University Tokyo Japan
| | - Takahiro Iwaki
- Department of Orthopedic SurgeryTokyo Medical University Tokyo Japan
| | - Toshinori Masaoka
- Department of Orthopedic SurgeryTokyo Medical University Tokyo Japan
| | - Eiichi Fukada
- Laboratory of PiezoelectricityKobayasi Institute of Physical Research Tokyo Japan
| | - Munehiro Date
- Laboratory of PiezoelectricityKobayasi Institute of Physical Research Tokyo Japan
| | - Kengo Yamamoto
- Department of Orthopedic SurgeryTokyo Medical University Tokyo Japan
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31
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Xiao L, Zhou Y, Friis T, Beagley K, Xiao Y. S1P-S1PR1 Signaling: the "Sphinx" in Osteoimmunology. Front Immunol 2019; 10:1409. [PMID: 31293578 PMCID: PMC6603153 DOI: 10.3389/fimmu.2019.01409] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 06/04/2019] [Indexed: 12/24/2022] Open
Abstract
The fundamental interaction between the immune and skeletal systems, termed as osteoimmunology, has been demonstrated to play indispensable roles in the maintenance of balance between bone resorption and formation. The pleiotropic sphingolipid metabolite, sphingosine 1-phosphate (S1P), together with its cognate receptor, sphingosine-1-phosphate receptor-1 (S1PR1), are known as key players in osteoimmunology due to the regulation on both immune system and bone remodeling. The role of S1P-S1PR1 signaling in bone remodeling can be directly targeting both osteoclastogenesis and osteogenesis. Meanwhile, inflammatory cell function and polarization in both adaptive immune (T cell subsets) and innate immune cells (macrophages) are also regulated by this signaling axis, suggesting that S1P-S1PR1 signaling could aslo indirectly regulate bone remodeling via modulating the immune system. Therefore, it could be likely that S1P-S1PR1 signaling might take part in the maintenance of continuous bone turnover under physiological conditions, while lead to the pathogenesis of bone deformities during inflammation. In this review, we summarized the immunological regulation of S1P-S1PR1 signal axis during bone remodeling with an emphasis on how osteo-immune regulators are affected by inflammation, an issue with relevance to chronical bone disorders such as rheumatoid arthritis, spondyloarthritis and periodontitis.
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Affiliation(s)
- Lan Xiao
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia.,The Australia-China Centre for Tissue Engineering and Regenerative Medicine, Queensland University of Technology, Brisbane, QLD, Australia
| | - Yinghong Zhou
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia.,The Australia-China Centre for Tissue Engineering and Regenerative Medicine, Queensland University of Technology, Brisbane, QLD, Australia.,Key Laboratory of Oral Medicine, Guangzhou Institute of Oral Disease, Stomatology Hospital of Guangzhou Medical University, Guangzhou, China
| | - Thor Friis
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Kenneth Beagley
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia.,The Australia-China Centre for Tissue Engineering and Regenerative Medicine, Queensland University of Technology, Brisbane, QLD, Australia
| | - Yin Xiao
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia.,The Australia-China Centre for Tissue Engineering and Regenerative Medicine, Queensland University of Technology, Brisbane, QLD, Australia.,Key Laboratory of Oral Medicine, Guangzhou Institute of Oral Disease, Stomatology Hospital of Guangzhou Medical University, Guangzhou, China
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32
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Al Saedi A, A. Goodman C, E. Myers D, Hayes A, Duque G. Rapamycin Affects Palmitate-Induced Lipotoxicity in Osteoblasts by Modulating Apoptosis and Autophagy. J Gerontol A Biol Sci Med Sci 2019; 75:58-63. [DOI: 10.1093/gerona/glz149] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Indexed: 01/01/2023] Open
Abstract
Abstract
Bone marrow fat infiltration is one of the hallmarks of aging and osteoporotic bones. Marrow adipocytes produce substantial amounts of palmitic acid (PA). PA is toxic to bone-forming osteoblasts in vitro, affecting their differentiation, function, and survival. Since rapamycin (RAP)-induced inhibition of target of rapamycin complex 1 (mTORC1) activates autophagy and prevents apoptosis, we hypothesized that RAP may preserve osteoblast viability and reduce PA-induced lipotoxicity. Normal human osteoblasts were incubated with RAP in the presence of a lipotoxic concentration of PA or vehicle for 24 and 48 hours. Expression of LC3 protein levels and the phosphorylation of the direct mTORC1 target p70S6K1-T389 were quantified by Western blot. Lysosomes and autophagosomes were studied using confocal fluorescence imaging, lysotracker, and live-cell imaging. RAP reduced PA-induced apoptosis. In addition, PA-induced autophagosome formation increased substantially over the time-course, an effect that was significantly regulated by the presence of RAP in the media. In addition, LC3I/II ratios were higher in PA-induced cells with RAP whereas p70S6K1-T389 were lower in PA and RAP together. In summary, this study highlights the role of the RAP-sensitive mTORC1 pathway in normal human osteoblasts under lipotoxic conditions. RAP-associated therapies could, potentially, be targeted for specific roles in osteoporosis and aging bone.
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Affiliation(s)
- Ahmed Al Saedi
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St. Albans, Victoria
- Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St. Albans, Victoria
| | - Craig A. Goodman
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St. Albans, Victoria
- Institute of Health and Sport, Victoria University, Melbourne, Victoria, Australia
| | - Damian E. Myers
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St. Albans, Victoria
- Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St. Albans, Victoria
| | - Alan Hayes
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St. Albans, Victoria
- Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St. Albans, Victoria
- Institute of Health and Sport, Victoria University, Melbourne, Victoria, Australia
| | - Gustavo Duque
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St. Albans, Victoria
- Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St. Albans, Victoria
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33
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Zheng H, Liu J, Tycksen E, Nunley R, McAlinden A. MicroRNA-181a/b-1 over-expression enhances osteogenesis by modulating PTEN/PI3K/AKT signaling and mitochondrial metabolism. Bone 2019; 123:92-102. [PMID: 30898695 PMCID: PMC6491221 DOI: 10.1016/j.bone.2019.03.020] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 03/13/2019] [Accepted: 03/16/2019] [Indexed: 12/14/2022]
Abstract
MicroRNAs are small non-coding RNAs that play important roles in many cellular processes including proliferation, metabolism and differentiation. They function by binding to specific regions within the 3'UTR of target mRNAs resulting in suppression of protein synthesis and modulation of potentially many cellular pathways. We previously showed that miRNA expression levels differed between cells from distinct regions of developing human embryonic long bones. Specifically, we found that miR-181a-1 was significantly more highly expressed in hypertrophic chondrocytes compared to proliferating differentiated or progenitor chondrocytes, suggesting a potential role in regulating chondrocyte hypertrophy and/or endochondral bone formation. The goal of this study was to determine how miR-181a-1 together with its clustered miRNA, miR-181b-1, regulates osteogenesis. We show that over-expression of the miR-181a/b-1 cluster enhanced osteogenesis and that cellular pathways associated with protein synthesis and mitochondrial metabolism were significantly up-regulated. Metabolic assays revealed that the oxygen consumption rate and ATP-linked respiration were increased by miR-181a/b-1. To further decipher a potential mechanism causing these metabolic changes, we showed that PTEN (phosphatase and tensin homolog) levels were suppressed following miR-181a/b-1 over-expression, and that PI3K/AKT signaling was subsequently increased. Over-expression of PTEN was found to attenuate the enhancing effects of miR-181a/b-1, providing further evidence that miR-181a/b-1 regulates the PTEN/PI3K/AKT axis to enhance osteogenic differentiation and mitochondrial metabolism. These findings have important implications for the design of miR-181a/b targeting strategies to treat bone conditions such as fractures or heterotopic ossification.
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Affiliation(s)
- Hongjun Zheng
- Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, MO, United States of America.
| | - Jin Liu
- Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, MO, United States of America.
| | - Eric Tycksen
- Genome Technology Access Center, Washington University School of Medicine, St Louis, MO, United States of America.
| | - Ryan Nunley
- Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, MO, United States of America.
| | - Audrey McAlinden
- Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, MO, United States of America; Department of Cell Biology, Washington University School of Medicine, St. Louis, MO, United States of America; Shriners Hospital for Children - St Louis, St Louis, MO, United States of America.
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34
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Cheng Y, Huang L, Wang Y, Huo Q, Shao Y, Bao H, Li Z, Liu Y, Li X. Strontium promotes osteogenic differentiation by activating autophagy via the the AMPK/mTOR signaling pathway in MC3T3‑E1 cells. Int J Mol Med 2019; 44:652-660. [PMID: 31173178 PMCID: PMC6605659 DOI: 10.3892/ijmm.2019.4216] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 05/24/2019] [Indexed: 12/23/2022] Open
Abstract
Strontium (Sr) is an alkaline earth metal that exerts the dual effect of improving bone formation and suppressing bone resorption, resulting in increased bone apposition rates and bone mineral density. However, the mechanisms through which Sr exerts these beneficial effects on bone have yet to be fully elucidated. The present study aimed to reveal the underlying molecular mechanisms associated with Sr‑induced osteogenic differentiation. The effects of Sr on cell proliferation and osteogenic differentiation were analyzed by MTT assay, RT‑qPCR, western blot analysis, alkaline phosphatase (ALP) and Alizarin red staining assays. The extent of autophagy was determined by monodansylcadaverine (MDC) staining and western blot analysis of two markers of cellular autophagic activity, the steatosis‑associated protein, sequestosome‑1 (SQSTM1/p62), and the two isoforms of microtubule‑associated protein 1 light chain 3 (LC3), LC‑3‑I/II. The expression levels of AMP‑activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) were also detected by western blot analysis. Sr at a concentration of 3 mM exerted the most pronounced effect on osteogenic differentiation, without any apparent cell toxicity. At the same time, cellular autophagy was active during this process. Subsequently, autophagy was blocked by 3‑methyladenine, and the enhancement of osteogenic differentiation in response to Sr was abrogated. Additionally, the phosphorylation level of AMPK was significantly increased, whereas that of mTOR was significantly decreased, in the Sr‑treated group. Taken together, the findings of the present study demonstrate that Sr stimulates AMPK‑activated autophagy to induce the osteogenic differentiation of MC3T3‑E1 cells.
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Affiliation(s)
- You Cheng
- School of Medical Laboratory, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Lunhui Huang
- School of Medical Laboratory, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Yichao Wang
- Department of Clinical Laboratory Medicine, Taizhou University Hospital, Taizhou, Zhejiang 318000, P.R. China
| | - Qianyu Huo
- School of Medical Laboratory, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Yanhong Shao
- School of Medical Laboratory, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Huijing Bao
- School of Medical Laboratory, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Zhaoyang Li
- School of Materials Science and Engineering, Tianjin University, Tianjin 300350, P.R. China
| | - Yunde Liu
- School of Medical Laboratory, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Xue Li
- School of Medical Laboratory, Tianjin Medical University, Tianjin 300070, P.R. China
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35
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Bateman JF, Sampurno L, Maurizi A, Lamandé SR, Sims NA, Cheng TL, Schindeler A, Little DG. Effect of rapamycin on bone mass and strength in the α2(I)-G610C mouse model of osteogenesis imperfecta. J Cell Mol Med 2018; 23:1735-1745. [PMID: 30597759 PMCID: PMC6378195 DOI: 10.1111/jcmm.14072] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 10/15/2018] [Accepted: 11/10/2018] [Indexed: 12/23/2022] Open
Abstract
Osteogenesis imperfecta (OI) is commonly caused by heterozygous type I collagen structural mutations that disturb triple helix folding and integrity. This mutant‐containing misfolded collagen accumulates in the endoplasmic reticulum (ER) and induces a form of ER stress associated with negative effects on osteoblast differentiation and maturation. Therapeutic induction of autophagy to degrade the mutant collagens could therefore be useful in ameliorating the ER stress and deleterious downstream consequences. To test this, we treated a mouse model of mild to moderate OI (α2(I) G610C) with dietary rapamycin from 3 to 8 weeks of age and effects on bone mass and mechanical properties were determined. OI bone mass and mechanics were, as previously reported, compromised compared to WT. While rapamycin treatment improved the trabecular parameters of WT and OI bones, the biomechanical deficits of OI bones were not rescued. Importantly, we show that rapamycin treatment suppressed the longitudinal and transverse growth of OI, but not WT, long bones. Our work demonstrates that dietary rapamycin offers no clinical benefit in this OI model and furthermore, the impact of rapamycin on OI bone growth could exacerbate the clinical consequences during periods of active bone growth in patients with OI caused by collagen misfolding mutations.
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Affiliation(s)
- John F Bateman
- Murdoch Children's Research Institute, Parkville, Victoria, Australia.,Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Lisa Sampurno
- Murdoch Children's Research Institute, Parkville, Victoria, Australia
| | - Antonio Maurizi
- Murdoch Children's Research Institute, Parkville, Victoria, Australia.,Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Shireen R Lamandé
- Murdoch Children's Research Institute, Parkville, Victoria, Australia.,Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia
| | - Natalie A Sims
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia.,Department of Medicine at St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Tegan L Cheng
- Orthopaedic Research and Biotechnology Unit, The Children's Hospital at Westmead, Sydney, New South Wales, Australia
| | - Aaron Schindeler
- Orthopaedic Research and Biotechnology Unit, The Children's Hospital at Westmead, Sydney, New South Wales, Australia
| | - David G Little
- Orthopaedic Research and Biotechnology Unit, The Children's Hospital at Westmead, Sydney, New South Wales, Australia
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36
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Jiang YY, Zhou ZF, Zhu YJ, Chen FF, Lu BQ, Cao WT, Zhang YG, Cai ZD, Chen F. Enzymatic Reaction Generates Biomimic Nanominerals with Superior Bioactivity. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1804321. [PMID: 30417599 DOI: 10.1002/smll.201804321] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Indexed: 05/22/2023]
Abstract
In vivo mineralization is a multistep process involving mineral-protein complexes and various metastable compounds in vertebrates. In this complex process, the minerals produced in the mitochondrial matrix play a critical role in initiating extracellular mineralization. However, the functional mechanisms of the mitochondrial minerals are still a mystery. Herein, an in vitro enzymatic reaction strategy is reported for the generation of biomimic amorphous calcium phosphate (EACP) nanominerals by an alkaline phosphatase (ALP)-catalyzed hydrolysis of adenosine triphosphate (ATP) in a weakly alkalescent aqueous condition (pH 8.0-8.5), which is partially similar to the mitochondrial environment. Significantly, the EACP nanomineral obviously promotes autophagy and osteogenic differentiation of human bone marrow-derived mesenchymal stem cells by activating an AMPK related pathway, and displays a high performance in promoting bone regeneration. These results provide in vitro evidence for the effect of ATP on the formation and stabilization of the mineral in the mineralization process, demonstrating a potential strategy for the preparation of the biomimic mineral for treating bone related diseases.
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Affiliation(s)
- Ying-Ying Jiang
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, P. R. China
- Department of Orthopedics, Spinal Pain Research Institute, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, 200072, P. R. China
| | - Zi-Fei Zhou
- Department of Orthopedics, Spinal Pain Research Institute, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, 200072, P. R. China
- Department of Orthopedic Surgery, Shanghai General Hospital, Shanghai Jiao Tong University, Shanghai, 200080, P. R. China
| | - Ying-Jie Zhu
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, P. R. China
| | - Fei-Fei Chen
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, P. R. China
| | - Bing-Qiang Lu
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, P. R. China
| | - Wen-Tao Cao
- Department of Orthopedics, Spinal Pain Research Institute, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, 200072, P. R. China
| | - Yong-Gang Zhang
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, P. R. China
| | - Zheng-Dong Cai
- Department of Orthopedic Surgery, Shanghai General Hospital, Shanghai Jiao Tong University, Shanghai, 200080, P. R. China
| | - Feng Chen
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, P. R. China
- Department of Orthopedics, Spinal Pain Research Institute, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, 200072, P. R. China
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37
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Li Y, Li J, Zhou Q, Liu Y, Chen W, Xu H. mTORC1 signaling is essential for neurofibromatosis type I gene modulated osteogenic differentiation of BMSCs. J Cell Biochem 2018; 120:2886-2896. [DOI: 10.1002/jcb.26626] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 12/19/2017] [Indexed: 12/23/2022]
Affiliation(s)
- YiQiang Li
- Department of Pediatric Orthopaedics, GuangZhou Women and Children's Medical Center, Guangzhou Medical University Guangzhou China
| | - JingChun Li
- Department of Pediatric Orthopaedics, GuangZhou Women and Children's Medical Center, Guangzhou Medical University Guangzhou China
| | - QingHe Zhou
- Department of Pediatric Orthopaedics, GuangZhou Women and Children's Medical Center, Guangzhou Medical University Guangzhou China
| | - Yuanzhong Liu
- Department of Pediatric Orthopaedics, GuangZhou Women and Children's Medical Center, Guangzhou Medical University Guangzhou China
| | - WeiDong Chen
- Department of Pediatric Orthopaedics, GuangZhou Women and Children's Medical Center, Guangzhou Medical University Guangzhou China
| | - HongWen Xu
- Department of Pediatric Orthopaedics, GuangZhou Women and Children's Medical Center, Guangzhou Medical University Guangzhou China
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38
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NUMB maintains bone mass by promoting degradation of PTEN and GLI1 via ubiquitination in osteoblasts. Bone Res 2018; 6:32. [PMID: 30455992 PMCID: PMC6226489 DOI: 10.1038/s41413-018-0030-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 01/22/2018] [Accepted: 03/13/2018] [Indexed: 02/05/2023] Open
Abstract
The adaptor protein NUMB is involved in asymmetric division and cell fate determination and recognized as an antagonist of Notch. Previous studies have proved that Notch activation in osteoblasts contributes to a high bone mass. In this study, however, an osteopenic phenotype was found in 9-week-old mice using osteoblastic specific Col1a1–2.3-Cre to ablate both Numb and its homologue Numbl . The trabecular bone mass decreased dramatically while the cortical bone mass was unaffected. Here, the Notch signal was not activated, while the tensin homologue deleted on human chromosome 10 (PTEN), which dephosphorylates phosphatidylinositide 3-kinases, was elevated, attenuating protein kinase B (Akt). The ubiquitination assay revealed that NUMB may physiologically promote PTEN ubiquitination in the presence of neural precursor cell-expressed developmentally downregulated protein 4–1. In addition, the deficiency of Numb/Numbl also activated the Hedgehog pathway through GLI1. This process was found to improve the ratio of the receptor activator of nuclear factor-kB ligand to osteoprotegerin, which enhanced the differentiation of osteoclasts and bone resorption . In conclusion, this study provides an insight into new functons of NUMB and NUMBL on bone homeostasis. The related proteins NUMB and NUMBL maintain the survival of bone-generating osteoblast cells. NUMB was previously recognized to antagonize Notch signaling pathway ; In this study, it observes that genetically altered mice, unable to express the two proteins, suffered from degraded bone quality. This suggests that the two proteins play a more complex, nuanced role in the process of bone mass maintenance. The team’s studies showed that NUMB and NUMBL suppression inhibits a signaling pathway important to skeletal development and protein synthesis in osteoblasts, though raise that further investigations are essential to elucidate the exact mechanistic action of these proteins. The authors of this study suggest that NUMB constitutes a potential target for therapies targeting bone loss and reduced bone strength in patients with osteoporosis.
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39
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Di Vito A, Giudice A, Chiarella E, Malara N, Bennardo F, Fortunato L. In Vitro Long-Term Expansion and High Osteogenic Potential of Periodontal Ligament Stem Cells: More Than a Mirage. Cell Transplant 2018; 28:129-139. [PMID: 30369260 PMCID: PMC6322134 DOI: 10.1177/0963689718807680] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The periodontal ligament displays a reservoir of mesenchymal stem cells which can account for periodontal regeneration. Despite the numerous studies directed at the definition of optimal culture conditions for long-term expansion of periodontal ligament stem cells (PDLSCs), no consensus has been reached as to what is the ideal protocol. The aim of the present study was to determine the optimal medium formulation for long-term expansion and stemness maintenance of PDLSCs, in order to obtain a sufficient number of cells for therapeutic approaches. For this purpose, the effects of three different culture medium formulations were evaluated on PDLSCs obtained from three periodontal ligament samples of the same patient: minimum essential medium Eagle, alpha modification (α-MEM), Dulbecco's modified Eagle's medium (DMEM), both supplemented with 10% fetal bovine serum (FBS), and a new medium formulation, Ham's F12 medium, supplemented with 10% FBS, heparin 0.5 U/ml, epidermal growth factor (EGF) 50 ng/ml, fibroblast growth factor (FGF) 25 ng/ml, and bovine serum albumin (BSA) 1% (enriched Ham's F12 medium; EHFM). PDLSCs grown in EHFM displayed a higher PE-CD73 mean fluorescence intensity compared with cells maintained in α-MEM and DMEM, even at later passages. Cells maintained in EHFM displayed an increased population doubling and a reduced population doubling time compared with cells grown in DMEM or α-MEM. α-MEM, DMEM and EHFM with added dexamethasone, 2-phospho-L-ascorbic acid, and β-glycerophosphate were all able to promote alkaline phosphatase activity; however, no calcium deposition was detected in PDLSCs cultured in EHFM-differentiation medium. When EHFM-, α-MEM- and DMEM-expanded PDLSCs were transferred to a commercial culture medium for the osteogenesis, mineralization became much more evident in confluent monolayers of EHFM-expanded PDLSCs compared with DMEM and α-MEM. The results suggest EHFM is the optimal medium formulation for growth and stemness maintenance of primary PDLSCs. Moreover, EHFM confers higher osteogenic potential to PDLSCs compared with cells maintained in the other culture media. Overall, the results of the present work confirmed the advantages of using EHFM for long-term expansion of mesenchymal cells in vitro and the preservation of high osteogenic potential.
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Affiliation(s)
- Anna Di Vito
- 1 Department of Clinical and Experimental Medicine, University Magna Graecia of Catanzaro, Campus Universitario "Salvatore Venuta" Viale Europa - Loc. Germaneto, Catanzaro, Italy
| | - Amerigo Giudice
- 2 Department of Health Science, University Magna Graecia of Catanzaro, Catanzaro, Italy
| | - Emanuela Chiarella
- 1 Department of Clinical and Experimental Medicine, University Magna Graecia of Catanzaro, Campus Universitario "Salvatore Venuta" Viale Europa - Loc. Germaneto, Catanzaro, Italy
| | - Natalia Malara
- 1 Department of Clinical and Experimental Medicine, University Magna Graecia of Catanzaro, Campus Universitario "Salvatore Venuta" Viale Europa - Loc. Germaneto, Catanzaro, Italy
| | - Francesco Bennardo
- 2 Department of Health Science, University Magna Graecia of Catanzaro, Catanzaro, Italy
| | - Leonzio Fortunato
- 2 Department of Health Science, University Magna Graecia of Catanzaro, Catanzaro, Italy
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40
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Li K, Xiu C, Zhou Q, Ni L, Du J, Gong T, Li M, Saijilafu, Yang H, Chen J. A dual role of cholesterol in osteogenic differentiation of bone marrow stromal cells. J Cell Physiol 2018; 234:2058-2066. [PMID: 30317648 DOI: 10.1002/jcp.27635] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 09/27/2018] [Indexed: 12/14/2022]
Affiliation(s)
- Kun Li
- Department of OrthopaedicsThe First Affiliated Hospital of Soochow UniversitySuzhou China
- Department of Orthopedic Institute, Medical College, Soochow UniversitySuzhou China
| | - Chunmei Xiu
- Department of Orthopedic Institute, Medical College, Soochow UniversitySuzhou China
| | - Qiang Zhou
- Department of RadiologyThe First Affiliated Hospital of Soochow UniversitySuzhou China
| | - Li Ni
- Department of OrthopaedicsThe First Affiliated Hospital of Soochow UniversitySuzhou China
- Department of Orthopedic Institute, Medical College, Soochow UniversitySuzhou China
| | - Jun Du
- Department of Orthopedic Magnetic Resonance ChamberThe First Affiliated Hospital of Soochow UniversitySuzhou China
| | - Tingting Gong
- Department of Orthopedic Institute, Medical College, Soochow UniversitySuzhou China
| | - Meng Li
- Department of OrthopaedicsThe First Affiliated Hospital of Soochow UniversitySuzhou China
- Department of Orthopedic Institute, Medical College, Soochow UniversitySuzhou China
| | - Saijilafu
- Department of OrthopaedicsThe First Affiliated Hospital of Soochow UniversitySuzhou China
- Department of Orthopedic Institute, Medical College, Soochow UniversitySuzhou China
| | - Huilin Yang
- Department of OrthopaedicsThe First Affiliated Hospital of Soochow UniversitySuzhou China
- Department of Orthopedic Institute, Medical College, Soochow UniversitySuzhou China
| | - Jianquan Chen
- Department of OrthopaedicsThe First Affiliated Hospital of Soochow UniversitySuzhou China
- Department of Orthopedic Institute, Medical College, Soochow UniversitySuzhou China
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41
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Martin SK, Fitter S, El Khawanky N, Grose RH, Walkley CR, Purton LE, Ruegg MA, Hall MN, Gronthos S, Zannettino ACW. mTORC1 plays an important role in osteoblastic regulation of B-lymphopoiesis. Sci Rep 2018; 8:14501. [PMID: 30266921 PMCID: PMC6162303 DOI: 10.1038/s41598-018-32858-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 09/17/2018] [Indexed: 01/05/2023] Open
Abstract
Skeletal osteoblasts are important regulators of B-lymphopoiesis, serving as a rich source of factors such as CXCL12 and IL-7 which are crucial for B-cell development. Recent studies from our laboratory and others have shown that deletion of Rptor, a unique component of the mTORC1 nutrient-sensing complex, early in the osteoblast lineage development results in defective bone development in mice. In this study, we now demonstrate that mTORC1 signalling in pre-osteoblasts is required for normal B-lymphocyte development in mice. Targeted deletion of Rptor in osterix-expressing pre-osteoblasts (Rptorob-/-) leads to a significant reduction in the number of B-cells in the bone marrow, peripheral blood and spleen at 4 and 12 weeks of age. Rptorob-/- mice also exhibit a significant reduction in pre-B and immature B-cells in the BM, indicative of a block in B-cell development from the pro-B to pre-B cell stage. Circulating levels of IL-7 and CXCL12 are also significantly reduced in Rptorob-/- mice. Importantly, whilst Rptor-deficient osteoblasts are unable to support HSC differentiation to B-cells in co-culture, this can be rescued by the addition of exogenous IL-7 and CXCL12. Collectively, these findings demonstrate that mTORC1 plays an important role in extrinsic osteoblastic regulation of B-cell development.
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Affiliation(s)
- Sally K Martin
- Myeloma Research Laboratory, Adelaide Medical School, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, Australia.,The South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Stephen Fitter
- Myeloma Research Laboratory, Adelaide Medical School, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, Australia.,The South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Nadia El Khawanky
- The South Australian Health and Medical Research Institute, Adelaide, Australia.,School of Medicine, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, Australia.,Department of Hematology and Oncology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Randall H Grose
- The South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Carl R Walkley
- Stem Cell Regulation Unit, St Vincent's Institute of Medical Research, Melbourne, Australia
| | - Louise E Purton
- Stem Cell Regulation Unit, St Vincent's Institute of Medical Research, Melbourne, Australia
| | | | | | - Stan Gronthos
- The South Australian Health and Medical Research Institute, Adelaide, Australia.,Mesenchymal Stem Cell Laboratory, Adelaide Medical School, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, Australia
| | - Andrew C W Zannettino
- Myeloma Research Laboratory, Adelaide Medical School, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, Australia. .,The South Australian Health and Medical Research Institute, Adelaide, Australia.
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42
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Farr JN, Almeida M. The Spectrum of Fundamental Basic Science Discoveries Contributing to Organismal Aging. J Bone Miner Res 2018; 33:1568-1584. [PMID: 30075061 PMCID: PMC6327947 DOI: 10.1002/jbmr.3564] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 07/25/2018] [Accepted: 07/27/2018] [Indexed: 12/22/2022]
Abstract
Aging research has undergone unprecedented advances at an accelerating rate in recent years, leading to excitement in the field as well as opportunities for imagination and innovation. Novel insights indicate that, rather than resulting from a preprogrammed series of events, the aging process is predominantly driven by fundamental non-adaptive mechanisms that are interconnected, linked, and overlap. To varying degrees, these mechanisms also manifest with aging in bone where they cause skeletal fragility. Because these mechanisms of aging can be manipulated, it might be possible to slow, delay, or alleviate multiple age-related diseases and their complications by targeting conserved genetic signaling pathways, controlled functional networks, and basic biochemical processes. Indeed, findings in various mammalian species suggest that targeting fundamental aging mechanisms (eg, via either loss-of-function or gain-of-function mutations or administration of pharmacological therapies) can extend healthspan; ie, the healthy period of life free of chronic diseases. In this review, we summarize the evidence supporting the role of the spectrum of fundamental basic science discoveries contributing to organismal aging, with emphasis on mammalian studies and in particular aging mechanisms in bone that drive skeletal fragility. These mechanisms or aging hallmarks include: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication. Because these mechanisms are linked, interventions that ameliorate one hallmark can in theory ameliorate others. In the field of bone and mineral research, current challenges include defining the relative contributions of each aging hallmark to the natural skeletal aging process, better understanding the complex interconnections among the hallmarks, and identifying the most effective therapeutic strategies to safely target multiple hallmarks. Based on their interconnections, it may be feasible to simultaneously interfere with several fundamental aging mechanisms to alleviate a wide spectrum of age-related chronic diseases, including osteoporosis. © 2018 American Society for Bone and Mineral Research.
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Affiliation(s)
- Joshua N Farr
- Division of Endocrinology and Metabolism and Kogod Center on Aging, Mayo Clinic, Rochester, MN, USA
| | - Maria Almeida
- Division of Endocrinology and Metabolism, Center for Osteoporosis and Metabolic Bone Diseases, University of Arkansas for Medical Sciences, Little Rock, AR, USA
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43
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Liu Q, Liu C, Yang Y, Yang H, Chen J. Osteocyte‐intrinsic mTORC1 signaling restrains trabecular bone accrual in mice. J Cell Biochem 2018; 119:8743-8749. [PMID: 30160781 DOI: 10.1002/jcb.27470] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 07/18/2018] [Indexed: 12/22/2022]
Affiliation(s)
- Qingbai Liu
- Department of Orthopaedics The First Affiliated Hospital of Soochow University Suzhou China
- Department of Orthopedics Lianshui County People's Hospital Huaian China
| | - Cunchang Liu
- Orthopedic Institute, Medical College, Soochow University Suzhou China
| | - Yanjun Yang
- Orthopedic Institute, Medical College, Soochow University Suzhou China
| | - Huilin Yang
- Department of Orthopaedics The First Affiliated Hospital of Soochow University Suzhou China
- Orthopedic Institute, Medical College, Soochow University Suzhou China
| | - Jianquan Chen
- Department of Orthopaedics The First Affiliated Hospital of Soochow University Suzhou China
- Orthopedic Institute, Medical College, Soochow University Suzhou China
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44
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Wang Y, Xiao M, Tao C, Chen J, Wang Z, Yang J, Chen Z, Zou Z, Liu A, Cai D, Jiang Y, Ding C, Li M, Bai X. Inactivation of mTORC1 Signaling in Osterix-Expressing Cells Impairs B-cell Differentiation. J Bone Miner Res 2018; 33:732-742. [PMID: 29206332 DOI: 10.1002/jbmr.3352] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 11/23/2017] [Accepted: 11/26/2017] [Indexed: 01/17/2023]
Abstract
Osteoblasts provide a microenvironmental niche for B-cell commitment and maturation in the bone marrow (BM). Any abnormity of osteoblasts function may result in the defect of B lymphopoiesis. Signaling from mechanistic target of rapamycin complex 1 (mTORC1) has been implicated in regulating the expansion and differentiation of osteoblasts. Thus, we raise a hypothesis that mTORC1 signaling in osteoblasts plays a vital role in B-cell development. Inactivation of mTORC1 in osterix-expressing cells (mainly osteoblast lineage) through Osx-Cre-directed deletion of Raptor (an mTORC1-specific component) resulted in a reduction in the total B-cell population in the BM, which was due to a block in early B-cell development from the pro-B to pre-B cell stage. Further mechanistic studies revealed that this defect was the result of reduction of interleukin-7 (IL-7) expression in osterix-expressing immature osteoblasts, which caused the abnormality of IL-7/Stat5 signaling in early B lymphocytes, leading to an increased apoptosis of pre-B plus immature B cells. In vitro and in vivo studies demonstrated that the addition of exogenous IL-7 partially restored B lymphopoiesis in the BM of Raptor mutant mice. Furthermore, total BM cells cultured in conditioned media from Raptor null immature osteoblasts or media with anti-IL-7 neutralizing antibody failed to differentiate into pre-B and immature B cells, indicating that inactivation of mTORC1 in immature osteoblast cannot fully support normal B-cell development. Taken together, these findings demonstrate a novel role for mTORC1 in the regulation of bone marrow environments that support B-cell differentiation via regulating IL-7 expression. © 2017 American Society for Bone and Mineral Research.
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Affiliation(s)
- Yongkui Wang
- Academy of Orthopedics, Guangdong Province, The Third Affiliated Hospital, Southern Medical University, Guangzhou, China.,State Key Laboratory of Organ Failure Research, Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Min Xiao
- Academy of Orthopedics, Guangdong Province, The Third Affiliated Hospital, Southern Medical University, Guangzhou, China.,State Key Laboratory of Organ Failure Research, Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Chen Tao
- State Key Laboratory of Organ Failure Research, Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Jing Chen
- SunYat-sen University Cancer Center, Guangzhou, China
| | - Zhenyu Wang
- Academy of Orthopedics, Guangdong Province, The Third Affiliated Hospital, Southern Medical University, Guangzhou, China
| | - Jun Yang
- State Key Laboratory of Organ Failure Research, Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Zhenguo Chen
- State Key Laboratory of Organ Failure Research, Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Zhipeng Zou
- State Key Laboratory of Organ Failure Research, Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Anling Liu
- State Key Laboratory of Organ Failure Research, Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Daozhang Cai
- Academy of Orthopedics, Guangdong Province, The Third Affiliated Hospital, Southern Medical University, Guangzhou, China
| | - Yu Jiang
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, PA, USA
| | - Changhai Ding
- Academy of Orthopedics, Guangdong Province, The Third Affiliated Hospital, Southern Medical University, Guangzhou, China.,State Key Laboratory of Organ Failure Research, Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Mangmang Li
- State Key Laboratory of Organ Failure Research, Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Xiaochun Bai
- Academy of Orthopedics, Guangdong Province, The Third Affiliated Hospital, Southern Medical University, Guangzhou, China.,State Key Laboratory of Organ Failure Research, Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
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45
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mTOR signaling in skeletal development and disease. Bone Res 2018; 6:1. [PMID: 29423330 PMCID: PMC5802487 DOI: 10.1038/s41413-017-0004-5] [Citation(s) in RCA: 151] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 10/13/2017] [Accepted: 10/23/2017] [Indexed: 02/07/2023] Open
Abstract
The mammalian/mechanistic target of rapamycin (mTOR) is a serine/threonine protein kinase that integrates inputs from nutrients and growth factors to control many fundamental cellular processes through two distinct protein complexes mTORC1 and mTORC2. Recent mouse genetic studies have established that mTOR pathways play important roles in regulating multiple aspects of skeletal development and homeostasis. In addition, mTORC1 has emerged as a common effector mediating the bone anabolic effect of Igf1, Wnt and Bmp. Dysregulation of mTORC1 could contribute to various skeletal diseases including osteoarthritis and osteoporosis. Here we review the current understanding of mTOR signaling in skeletal development and bone homeostasis, as well as in the maintenance of articular cartilage. We speculate that targeting mTOR signaling may be a valuable approach for treating skeletal diseases. Drugs directed at a key cellular signaling pathway could prove useful for treating skeletal diseases. Jianquan Chen from Soochow University in Suzhou, China, and Fanxin Long from Washington University School of Medicine in St. Louis, Missouri, USA, provide an overview of how proteins involved in the mechanistic target of rapamycin (mTOR) signaling pathway sense and integrate a range of environmental cues to regulate bone and cartilage development. In particular, they review the differing roles of the two distinct mTOR-containing protein complexes, mTORC1 and mTORC2. Both seem to mediate bone formation and resorption but in different ways, with implications for how best to treat osteoarthritis, osteoporosis, and other degenerative skeletal diseases. The authors suggest that more specific mTOR inhibitors with minimal side effects are needed to help stimulate bone growth in these diseases.
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46
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Tang Y, Zhang L, Tu T, Li Y, Murray D, Tu Q, Chen JJ. MicroRNA-99a is a novel regulator of KDM6B-mediated osteogenic differentiation of BMSCs. J Cell Mol Med 2018; 22:2162-2176. [PMID: 29377540 PMCID: PMC5867145 DOI: 10.1111/jcmm.13490] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 11/12/2017] [Indexed: 12/19/2022] Open
Abstract
Skeletal tissue originates from mesenchymal stem cells (MSCs) with differentiation potential into the osteoblast lineage regulated by essential transcriptional and post‐transcriptional mechanisms. Recently, miRNAs and histone modifications have been identified as novel key regulators of osteogenic differentiation of MSCs. Here, we identified miR‐99a and its target lysine (K)‐specific demethylase 6B (KDM6B) gene as novel modulators of osteogenic differentiation of bone mesenchymal stem cells (BMSCs). Microarray profiling and further validation by quantitative real‐time RT‐PCR revealed that miR‐99a was up‐regulated during osteoblastic differentiation of BMSCs, and decreased in differentiated osteoblasts. Transfection of miR‐99a mimics inhibited osteoblastic commitment and differentiation of BMSCs, whereas inhibition of miR‐99a by inhibitors enhances these processes. KDM6B was determined as one of important targets of miR‐99a, which was further confirmed by luciferase assay of 3′‐UTR of KDM6B. Moreover, HOX gene level decreased after transfection of miR‐99a mimics in BMSCs, which indicated that KDM6B is a bona fide target of miR‐99a. Furthermore, in a model of in vivo bone regeneration, osteoblast‐specific gain‐ and loss‐of‐function experiments performed using cranial bone defects revealed that miR‐99a mimics‐transfected BMSCs reduced bone formation, and conversely, miR‐99a inhibitors‐transfected BMSCs increased in vivo bone formation. Tissue‐specific inhibition of miR‐99a may be a potential novel therapeutic approach for enhancing BMSCs‐based bone formation and regeneration.
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Affiliation(s)
- Yin Tang
- Division of Oral Biology, Tufts University School of Dental Medicine, Boston, MA, USA.,State Key Laboratory of Oral Disease, West China School & Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - Lan Zhang
- Division of Oral Biology, Tufts University School of Dental Medicine, Boston, MA, USA.,State Key Laboratory of Oral Disease, West China School & Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - Tianchi Tu
- Division of Oral Biology, Tufts University School of Dental Medicine, Boston, MA, USA
| | - Yijia Li
- Division of Oral Biology, Tufts University School of Dental Medicine, Boston, MA, USA
| | - Dana Murray
- Division of Oral Biology, Tufts University School of Dental Medicine, Boston, MA, USA
| | - Qisheng Tu
- Division of Oral Biology, Tufts University School of Dental Medicine, Boston, MA, USA
| | - Jake Jinkun Chen
- Division of Oral Biology, Tufts University School of Dental Medicine, Boston, MA, USA.,Department of Anatomy and Cell Biology, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA, USA
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Gu X, Fu X, Lu J, Saijilafu, Li B, Luo ZP, Chen J. Pharmacological inhibition of S6K1 impairs self-renewal and osteogenic differentiation of bone marrow stromal cells. J Cell Biochem 2017; 119:1041-1049. [PMID: 28853173 DOI: 10.1002/jcb.26272] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 07/07/2017] [Indexed: 12/21/2022]
Abstract
mTORC1 signaling not only plays important physiological roles in the regulation of proliferation and osteogenic differentiation of BMSCs, but also mediates exogenous Wnt-induced protein anabolism and osteoblast differentiation. However, the downstream effectors of the mTORC1 signaling in the above processes are still poorly understood. In this study, we explored the specific role of S6K1, one of the major targets of the mTORC1 pathway, in BMSCs self-renewal and osteogenic differentiation. We first found that S6K1 was active in primary mouse bone marrow stromal cells, and further activated upon osteogenic induction. We then determined the effects of S6K1 inhibition by LY2584702 Tosylate, a selective inhibitor of S6K1 (hereafter S6KI), using both primary mouse bone marrow stromal cells and ST2 cells. Colony-Forming Unit-Fibroblast (CFU-F) assays showed that S6KI dramatically reduced the total number of colonies formed in primary BMSCs cultures. Under the basal osteogenic culture condition, S6KI significantly inhibited mRNA expression of osteoblast marker genes (Sp7, Bglap, Ibsp, and Col1a1), ALP activity and matrix mineralization. Upon Wnt3a treatments, S6KI inhibited Wnt3a-induced osteoblast differentiation and expression of protein anabolism genes in ST2 cells, but to a much lesser degree than rapamycin (a specific inhibitor of mTORC1 signaling). Collectively, our findings have demonstrated that pharmacological inhibition of S6K1 impaired self-renewal and osteogenic differentiation of BMSCs, but only partially suppressed exogenous Wnt3a-induced osteoblast differentiation and protein anabolism.
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Affiliation(s)
- Xiaohui Gu
- Orthopaedic Department, Zhejiang Provincial People's Hospital, Hangzhou, Zhejiang, People's Republic of China.,Department of Orthopaedics, Orthopaedic Institute, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu, People's Republic of China
| | - Xuejie Fu
- Department of Orthopaedics, Orthopaedic Institute, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu, People's Republic of China
| | - Jihang Lu
- Department of Orthopaedics, Orthopaedic Institute, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu, People's Republic of China
| | - Saijilafu
- Department of Orthopaedics, Orthopaedic Institute, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu, People's Republic of China
| | - Bin Li
- Department of Orthopaedics, Orthopaedic Institute, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu, People's Republic of China
| | - Zong-Ping Luo
- Department of Orthopaedics, Orthopaedic Institute, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu, People's Republic of China
| | - Jianquan Chen
- Department of Orthopaedics, Orthopaedic Institute, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu, People's Republic of China
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Browne AJ, Kubasch ML, Göbel A, Hadji P, Chen D, Rauner M, Stölzel F, Hofbauer LC, Rachner TD. Concurrent antitumor and bone-protective effects of everolimus in osteotropic breast cancer. Breast Cancer Res 2017; 19:92. [PMID: 28793923 PMCID: PMC5551016 DOI: 10.1186/s13058-017-0885-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 07/21/2017] [Indexed: 12/20/2022] Open
Abstract
Background The mammalian target of rapamycin inhibitor everolimus is approved as an antitumor agent in advanced estrogen receptor-positive breast cancer. Surrogate bone marker data from clinical trials suggest effects on bone metabolism, but the mode of action of everolimus in bone biology remains unclear. In this study, we assessed potential bone-protective effects of everolimus in the context of osteotropic tumors. Methods The effects of everolimus on cancer cell viability in vitro and on tumor growth in vivo were assessed. Everolimus-regulated osteoclastogenesis and osteoblastogenesis were also assessed in vitro before we assessed the bone-protective effect of everolimus in a model where bone loss was induced in ovariectomized (OVX) mice. Finally, the role of everolimus in the progression of osteolytic bone disease was assessed in an intracardiac model of breast cancer bone metastases. Results At low concentrations (1 nM) in vitro, everolimus reduced the viability of human and murine cancer cell lines and impaired the osteoclastogenesis of osteoclast progenitors as assessed by quantitative real-time polymerase chain reaction and counting tartrate-resistant acid phosphatase-positive, multinucleated osteoclasts (p < 0.001). Everolimus had little or no deleterious effect on osteoblastogenesis in vitro, with concentrations of 1 and 10 nM increasing the messenger RNA expression of osteoblast marker genes (p ≤ 0.05) and leaving mineralization in differentiated human mesenchymal stem cells unchanged. Everolimus treatment (1 mg/kg body weight/day) prevented the bone loss observed in OVX mice and concurrently inhibited the metastatic growth of MDA-MB-231 cells by 70% (p < 0.002) while preserving bone mass in an intracardiac model of bone metastasis. Conclusions These results underline the antitumor effects of everolimus and highlight its bone-protective efficacy, warranting further research on the potential implications on bone health in populations prone to osteoporosis and bone metastases, such as postmenopausal women with breast cancer. Electronic supplementary material The online version of this article (doi:10.1186/s13058-017-0885-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Andrew J Browne
- Division of Endocrinology, Diabetes and Bone Diseases, Department of Medicine III, Technical University Dresden, Fetscherstraße 74, D-01307, Dresden, Germany.,Center for Healthy Aging, Technical University Dresden, Dresden, Germany
| | - Marie L Kubasch
- Division of Endocrinology, Diabetes and Bone Diseases, Department of Medicine III, Technical University Dresden, Fetscherstraße 74, D-01307, Dresden, Germany.,Center for Healthy Aging, Technical University Dresden, Dresden, Germany
| | - Andy Göbel
- Division of Endocrinology, Diabetes and Bone Diseases, Department of Medicine III, Technical University Dresden, Fetscherstraße 74, D-01307, Dresden, Germany.,Center for Healthy Aging, Technical University Dresden, Dresden, Germany
| | - Peyman Hadji
- Philipps University of Marburg, Marburg, Germany
| | - David Chen
- Novartis Pharmaceutical Corp., East Hanover, NJ, USA
| | - Martina Rauner
- Division of Endocrinology, Diabetes and Bone Diseases, Department of Medicine III, Technical University Dresden, Fetscherstraße 74, D-01307, Dresden, Germany.,Center for Healthy Aging, Technical University Dresden, Dresden, Germany
| | - Friedrich Stölzel
- Division of Hematology, Department of Medicine I, Technical University Dresden, Dresden, Germany
| | - Lorenz C Hofbauer
- Division of Endocrinology, Diabetes and Bone Diseases, Department of Medicine III, Technical University Dresden, Fetscherstraße 74, D-01307, Dresden, Germany.,Center for Healthy Aging, Technical University Dresden, Dresden, Germany.,German Cancer Consortium (DKTK), partner site Dresden and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Tilman D Rachner
- Division of Endocrinology, Diabetes and Bone Diseases, Department of Medicine III, Technical University Dresden, Fetscherstraße 74, D-01307, Dresden, Germany. .,Center for Healthy Aging, Technical University Dresden, Dresden, Germany.
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49
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mTOR/Raptor signaling is critical for skeletogenesis in mice through the regulation of Runx2 expression. Cell Death Differ 2017; 24:1886-1899. [PMID: 28686577 PMCID: PMC5635215 DOI: 10.1038/cdd.2017.110] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 05/08/2017] [Accepted: 05/31/2017] [Indexed: 02/07/2023] Open
Abstract
The mammalian target of rapamycin (mTOR)/regulatory-associated protein of mTOR (Raptor) pathway transmits and integrates different signals including growth factors, nutrients, and energy metabolism. Nearly all these signals have been found to play roles in skeletal biology. However, the contribution of mTOR/Raptor to osteoblast biology in vivo remains to be elucidated as the conclusions of recent studies are controversial. Here we report that mice with a deficiency of either mTOR or Raptor in preosteoblasts exhibited clavicular hypoplasia and delayed fontanelle fusion, similar to those found in human patients with cleidocranial dysplasia (CCD) haploinsufficient for the transcription factor runt-related transcription factor 2 (Runx2) or those identified in Runx2+/− mice. Mechanistic analysis revealed that the mTOR-Raptor-S6K1 axis regulates Runx2 expression through phosphorylation of estrogen receptor α, which binds to Distal-less homeobox 5 (DLX5) and augments the activity of Runx2 enhancer. Moreover, heterozygous mutation of raptor in osteoblasts aggravates the bone defects observed in Runx2+/− mice, indicating a genetic interaction between Raptor and Runx2. Collectively, these findings reveal that mTOR/Raptor signaling is essential for bone formation in vivo through the regulation of Runx2 expression. These results also suggest that a selective mTOR/Raptor antagonist, which has been developed for treatment of many diseases, may have the side effect of causing bone loss.
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50
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Lee WC, Guntur AR, Long F, Rosen CJ. Energy Metabolism of the Osteoblast: Implications for Osteoporosis. Endocr Rev 2017; 38:255-266. [PMID: 28472361 PMCID: PMC5460680 DOI: 10.1210/er.2017-00064] [Citation(s) in RCA: 249] [Impact Index Per Article: 35.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 04/25/2017] [Indexed: 01/14/2023]
Abstract
Osteoblasts, the bone-forming cells of the remodeling unit, are essential for growth and maintenance of the skeleton. Clinical disorders of substrate availability (e.g., diabetes mellitus, anorexia nervosa, and aging) cause osteoblast dysfunction, ultimately leading to skeletal fragility and osteoporotic fractures. Conversely, anabolic treatments for osteoporosis enhance the work of the osteoblast by altering osteoblast metabolism. Emerging evidence supports glycolysis as the major metabolic pathway to meet ATP demand during osteoblast differentiation. Glut1 and Glut3 are the principal transporters of glucose in osteoblasts, although Glut4 has also been implicated. Wnt signaling induces osteoblast differentiation and activates glycolysis through mammalian target of rapamycin, whereas parathyroid hormone stimulates glycolysis through induction of insulin-like growth factor-I. Glutamine is an alternate fuel source for osteogenesis via the tricarboxylic acid cycle, and fatty acids can be metabolized to generate ATP via oxidative phosphorylation although temporal specificity has not been established. More studies with new model systems are needed to fully understand how the osteoblast utilizes fuel substrates in health and disease and how that impacts metabolic bone diseases.
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Affiliation(s)
- Wen-Chih Lee
- Department of Orthopedic Surgery, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Anyonya R Guntur
- Maine Medical Center Research Institute, Scarborough, Maine 04074
| | - Fanxin Long
- Department of Orthopedic Surgery, Washington University School of Medicine, St. Louis, Missouri 63110.,Departments of Medicine and Developmental Biology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Clifford J Rosen
- Maine Medical Center Research Institute, Scarborough, Maine 04074
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