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Guimarães GC, Coelho JBC, Silva JGO, de Sant'Ana ACC, de Sá CAC, Moreno JM, Reis LM, de Oliveira Guimarães CS. Obesity, diabetes and risk of bone fragility: How BMAT behavior is affected by metabolic disturbances and its influence on bone health. Osteoporos Int 2024; 35:575-588. [PMID: 38055051 DOI: 10.1007/s00198-023-06991-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Accepted: 11/26/2023] [Indexed: 12/07/2023]
Abstract
PURPOSE Osteoporosis is a metabolic bone disease characterized by decreased bone strength and mass, which predisposes patients to fractures and is associated with high morbidity and mortality. Like osteoporosis, obesity and diabetes are systemic metabolic diseases associated with modifiable risk factors and lifestyle, and their prevalence is increasing. They are related to decreased quality of life, functional loss and increased mortality, generating high costs for health systems and representing a worldwide public health problem. Growing evidence reinforces the role of bone marrow adipose tissue (BMAT) as an influential factor in the bone microenvironment and systemic metabolism. Given the impact of obesity and diabetes on metabolism and their possible effect on the bone microenvironment, changes in BMAT behavior may explain the risk of developing osteoporosis in the presence of these comorbidities. METHODS This study reviewed the scientific literature on the behavior of BMAT in pathological metabolic conditions, such as obesity and diabetes, and its potential involvement in the pathogenesis of bone fragility. RESULTS Published data strongly suggest a relationship between increased BMAT adiposity and the risk of bone fragility in the context of obesity and diabetes. CONCLUSION By secreting a broad range of factors, BMAT modulates the bone microenvironment and metabolism, ultimately affecting skeletal health. A better understanding of the relationship between BMAT expansion and metabolic disturbances observed in diabetic and obese patients will help to identify regulatory pathways and new targets for the treatment of bone-related diseases, with BMAT as a potential therapeutic target.
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Affiliation(s)
| | - João Bosco Costa Coelho
- Department of Veterinary Medicine, Federal University of Lavras, Lavras, Minas Gerais, Brazil
| | | | | | | | - Júlia Marques Moreno
- Department of Medicine, Federal University of Lavras, Lavras, Minas Gerais, Brazil
| | - Lívia Marçal Reis
- Department of Medicine, Federal University of Lavras, Lavras, Minas Gerais, Brazil
| | - Camila Souza de Oliveira Guimarães
- Department of Medicine, Federal University of Lavras, Lavras, Minas Gerais, Brazil.
- Departamento de Medicina, Universidade Federal de Lavras, Câmpus Universitário, Caixa Postal 3037, CEP 37200-900, Lavras, Minas Gerais, Brasil.
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2
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Huang W, Yu K, Kang M, Wang Q, Liao W, Liang P, Liu G, Cao Y, Miao J. Identification and functional analysis of three novel osteogenic peptides isolated from tilapia scale collagen hydrolysate. Food Res Int 2022; 162:111993. [DOI: 10.1016/j.foodres.2022.111993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Revised: 09/25/2022] [Accepted: 09/26/2022] [Indexed: 11/04/2022]
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3
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Macias-Velasco JF, St Pierre CL, Wayhart JP, Yin L, Spears L, Miranda MA, Carson C, Funai K, Cheverud JM, Semenkovich CF, Lawson HA. Parent-of-origin effects propagate through networks to shape metabolic traits. eLife 2022; 11:e72989. [PMID: 35356864 PMCID: PMC9075957 DOI: 10.7554/elife.72989] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 03/25/2022] [Indexed: 11/16/2022] Open
Abstract
Parent-of-origin effects are unexpectedly common in complex traits, including metabolic and neurological traits. Parent-of-origin effects can be modified by the environment, but the architecture of these gene-by-environmental effects on phenotypes remains to be unraveled. Previously, quantitative trait loci (QTL) showing context-specific parent-of-origin effects on metabolic traits were mapped in the F16 generation of an advanced intercross between LG/J and SM/J inbred mice. However, these QTL were not enriched for known imprinted genes, suggesting another mechanism is needed to explain these parent-of-origin effects phenomena. We propose that non-imprinted genes can generate complex parent-of-origin effects on metabolic traits through interactions with imprinted genes. Here, we employ data from mouse populations at different levels of intercrossing (F0, F1, F2, F16) of the LG/J and SM/J inbred mouse lines to test this hypothesis. Using multiple populations and incorporating genetic, genomic, and physiological data, we leverage orthogonal evidence to identify networks of genes through which parent-of-origin effects propagate. We identify a network comprised of three imprinted and six non-imprinted genes that show parent-of-origin effects. This epistatic network forms a nutritional responsive pathway and the genes comprising it jointly serve cellular functions associated with growth. We focus on two genes, Nnat and F2r, whose interaction associates with serum glucose levels across generations in high-fat-fed females. Single-cell RNAseq reveals that Nnat expression increases and F2r expression decreases in pre-adipocytes along an adipogenic trajectory, a result that is consistent with our observations in bulk white adipose tissue.
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Affiliation(s)
- Juan F Macias-Velasco
- Department of Genetics, Washington University School of MedicineSaint LouisUnited States
| | - Celine L St Pierre
- Department of Genetics, Washington University School of MedicineSaint LouisUnited States
| | - Jessica P Wayhart
- Department of Genetics, Washington University School of MedicineSaint LouisUnited States
| | - Li Yin
- Department of Medicine, Washington University School of MedicineSaint LouisUnited States
| | - Larry Spears
- Department of Medicine, Washington University School of MedicineSaint LouisUnited States
| | - Mario A Miranda
- Department of Genetics, Washington University School of MedicineSaint LouisUnited States
| | - Caryn Carson
- Department of Genetics, Washington University School of MedicineSaint LouisUnited States
| | - Katsuhiko Funai
- Diabetes and Metabolism Research Center, University of UtahSalt Lake CityUnited States
| | | | - Clay F Semenkovich
- Department of Medicine, Washington University School of MedicineSaint LouisUnited States
| | - Heather A Lawson
- Department of Genetics, Washington University School of MedicineSaint LouisUnited States
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4
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Freid R, Hussein AI, Schlezinger JJ. Tributyltin protects against ovariectomy-induced trabecular bone loss in C57BL/6J mice with an attenuated effect in high fat fed mice. Toxicol Appl Pharmacol 2021; 431:115736. [PMID: 34619157 PMCID: PMC8545923 DOI: 10.1016/j.taap.2021.115736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 09/25/2021] [Accepted: 09/29/2021] [Indexed: 11/27/2022]
Abstract
Risk factors for poor bone quality include estrogen loss at menopause, a high fat diet and exposures to drugs/chemicals that activate peroxisome proliferator activated receptor gamma (PPARγ). We previously reported that the PPARγ and retinoid X receptor dual ligand, tributyltin (TBT), repressed periosteal bone formation but enhanced trabecular bone formation in vivo. Here, we examined the interaction of diet, ovariectomy (OVX) and TBT exposure on bone structure. C57BL/6J mice underwent either sham surgery or OVX at 10 weeks of age. At 12 weeks of age, they were placed on a low (10% kcal) or high (45% kcal) fat, sucrose-matched diet and treated with vehicle or TBT (1 or 5 mg/kg) for 14 weeks. OVX increased body weight gain in mice on either diet. TBT enhanced body weight gain in intact mice fed a high fat diet, but decreased weight gain in OVX mice. Elemental tin concentrations increased dose-dependently in bone. TBT had marginal effects on cortical and trabecular bone in intact mice fed either diet. OVX caused a reduction in cortical and trabecular bone, regardless of diet. In high fat fed OVX mice, TBT further reduced cortical thickness, bone area and total area. Interestingly, TBT protected against OVX-induced trabecular bone loss in low fat fed mice. The protective effect of TBT was nullified by the high fat. These results show that TBT protects against trabecular bone loss, even in the presence of a strongly resorptive environment, at an even lower level of exposure than we showed repressed homeostatic resorption.
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Affiliation(s)
- Rachel Freid
- Environmental Health, Boston University School of Public Health, USA
| | - Amira I Hussein
- Orthopaedic Surgery, Boston University School of Medicine, Boston, MA 02118, USA
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5
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Li H, Yang C, Lan M, Liao X, Tang Z. Arctigenin promotes bone formation involving PI3K/Akt/PPARγ signaling pathway. Chem Biol Drug Des 2020; 95:451-459. [PMID: 31883507 DOI: 10.1111/cbdd.13659] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/19/2019] [Accepted: 12/23/2019] [Indexed: 12/12/2022]
Affiliation(s)
- Hongbo Li
- Department of Orthopedics Jiangxi provincial People's Hospital Affiliated to Nanchang University Nanchang China
| | - Chunli Yang
- Department of Intensive Care Jiangxi provincial People's Hospital Affiliated to Nanchang University Nanchang China
| | - Min Lan
- Department of Orthopedics Jiangxi provincial People's Hospital Affiliated to Nanchang University Nanchang China
| | - Xingen Liao
- Department of Orthopedics Jiangxi provincial People's Hospital Affiliated to Nanchang University Nanchang China
| | - Zhiming Tang
- Department of Orthopedics Jiangxi provincial People's Hospital Affiliated to Nanchang University Nanchang China
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6
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Li X, Ning L, Ma J, Xie Z, Zhao X, Wang G, Wan X, Qiu P, Yao T, Wang H, Fan S, Wan S. The PPAR-γ antagonist T007 inhibits RANKL-induced osteoclastogenesis and counteracts OVX-induced bone loss in mice. Cell Commun Signal 2019; 17:136. [PMID: 31655621 PMCID: PMC6815399 DOI: 10.1186/s12964-019-0442-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 09/20/2019] [Indexed: 02/12/2023] Open
Abstract
Background Osteoclasts are key determinant cellular components implicated in the development and progression of disorders driven by bone damage. Herein, we studied the upshot of T007, an antagonist of peroxisome proliferator-activated receptor-gamma (PPARγ), on osteoclastogenesis using cell and animal models. Results The in vitro assays revealed that T007 hindered the osteoclastogenesis caused by the treatment with the receptor activator of nuclear factor-κB ligand (RANKL) through inhibiting the levels of PPARγ in cells. The PPARγ siRNA partially reproduced the inhibitory action of T007. The opposite findings were produced after PPARγ overexpression. Furthermore, T007 prevented from bone loss in a mouse model of osteoporosis induced by ovariectomy (OVX). These findings implied that T007 is a potential efficient drug for the prophylaxis and cure of osteoclast-related disorders. Conclusions Taken together, our findings demonstrated that T007 impedes osteoclastogenesis and will be useful for the therapy of bone related diseases, essentially osteoporosis.
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Affiliation(s)
- Xiang Li
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, 3 East Qingchun Road, Hangzhou, 310016, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, 310016, China
| | - Lei Ning
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, 3 East Qingchun Road, Hangzhou, 310016, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, 310016, China
| | - Jianjun Ma
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, 3 East Qingchun Road, Hangzhou, 310016, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, 310016, China
| | - Ziang Xie
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, 3 East Qingchun Road, Hangzhou, 310016, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, 310016, China
| | - Xiangde Zhao
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, 3 East Qingchun Road, Hangzhou, 310016, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, 310016, China
| | - Gangliang Wang
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, 3 East Qingchun Road, Hangzhou, 310016, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, 310016, China
| | - Xinyu Wan
- First Clinical Medical College, Wenzhou Medical University, Wenzhou, 325035, China
| | - Pengcheng Qiu
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, 3 East Qingchun Road, Hangzhou, 310016, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, 310016, China
| | - Teng Yao
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, 3 East Qingchun Road, Hangzhou, 310016, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, 310016, China
| | - Haoming Wang
- The Third Hospital of Hebei Medical University, Shijiazhuang, 050051, China
| | - Shunwu Fan
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, 3 East Qingchun Road, Hangzhou, 310016, China. .,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, 310016, China.
| | - Shuanglin Wan
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, 3 East Qingchun Road, Hangzhou, 310016, China. .,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, 310016, China.
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Kim YH, Jang WG, Oh SH, Kim JW, Lee MN, Song JH, Yang JW, Zang Y, Koh JT. Fenofibrate induces PPARα and BMP2 expression to stimulate osteoblast differentiation. Biochem Biophys Res Commun 2019; 520:459-465. [PMID: 31607484 DOI: 10.1016/j.bbrc.2019.10.048] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 10/03/2019] [Indexed: 10/25/2022]
Abstract
The peroxisome proliferator-activated receptor (PPAR)-α agonist fenofibrate is used as a lipid-lowering agent to reduce cholesterol and triglyceride in blood. In this study, we investigated whether fenofibrate affects osteoblast differentiation of osteogenic precursor cells. Quantitative real-time PCR and alkaline phosphatase (ALP) staining assays revealed that fenofibrate can enhance the osteoblast differentiation of C3H10T1/2 and MC3T3-E1 cells. In contrast with fenofibrate, the PPARγ agonist rosiglitazone decreased or did not affect the expression of osteogenic genes in these cells. Fenofibrate dose- and time-dependently increased PPARα expression, and concomitantly increased the expression of bone morphogenetic protein 2 (BMP2). Knockdown of PPARα abolished fenofibrate-induced BMP2 expression, activity of the BMP2 promoter gene, and calcium deposition. The chromatin immunoprecipitation assay demonstrated that fenofibrate increased BMP2 expression by inducing direct binding of PPARα to the BMP2 promoter region. Taken together, we suggest that fenofibrate has a stimulatory effect on osteoblast differentiation via the elevation of PPARα levels and the PPARα-mediated BMP2 expression. Our findings provide fenofibrate as a useful agent for controlling hypercholesterolemic patients with osteoporosis.
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Affiliation(s)
- Yu-Ha Kim
- Hard Tissue Biointerface Research Center, School of Dentistry, Chonnam National University, Gwangju, Republic of Korea; Department of Pharmacology and Dental Therapeutics, School of Dentistry, Chonnam National University, Gwangju, Republic of Korea
| | - Won-Gu Jang
- Department of Biotechnology, School of Engineering, Daegu University, Gyeongsan, Republic of Korea
| | - Sin-Hye Oh
- Hard Tissue Biointerface Research Center, School of Dentistry, Chonnam National University, Gwangju, Republic of Korea; Department of Pharmacology and Dental Therapeutics, School of Dentistry, Chonnam National University, Gwangju, Republic of Korea
| | - Jung-Woo Kim
- Hard Tissue Biointerface Research Center, School of Dentistry, Chonnam National University, Gwangju, Republic of Korea; Department of Pharmacology and Dental Therapeutics, School of Dentistry, Chonnam National University, Gwangju, Republic of Korea
| | - Mi Nam Lee
- Hard Tissue Biointerface Research Center, School of Dentistry, Chonnam National University, Gwangju, Republic of Korea; Department of Pharmacology and Dental Therapeutics, School of Dentistry, Chonnam National University, Gwangju, Republic of Korea
| | - Ju Han Song
- Hard Tissue Biointerface Research Center, School of Dentistry, Chonnam National University, Gwangju, Republic of Korea; Department of Pharmacology and Dental Therapeutics, School of Dentistry, Chonnam National University, Gwangju, Republic of Korea
| | - Jin-Woo Yang
- Hard Tissue Biointerface Research Center, School of Dentistry, Chonnam National University, Gwangju, Republic of Korea; Department of Pharmacology and Dental Therapeutics, School of Dentistry, Chonnam National University, Gwangju, Republic of Korea
| | - Yaran Zang
- Hard Tissue Biointerface Research Center, School of Dentistry, Chonnam National University, Gwangju, Republic of Korea; Department of Pharmacology and Dental Therapeutics, School of Dentistry, Chonnam National University, Gwangju, Republic of Korea
| | - Jeong-Tae Koh
- Hard Tissue Biointerface Research Center, School of Dentistry, Chonnam National University, Gwangju, Republic of Korea; Department of Pharmacology and Dental Therapeutics, School of Dentistry, Chonnam National University, Gwangju, Republic of Korea.
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8
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Ma ZP, Zhang ZF, Yang YF, Yang Y. Sesamin Promotes Osteoblastic Differentiation and Protects Rats from Osteoporosis. Med Sci Monit 2019; 25:5312-5320. [PMID: 31314750 PMCID: PMC6659468 DOI: 10.12659/msm.915529] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Background Osteoporosis is a common osteopathy, resulting in fractures, especially in elder people. Sesamin has many pharmacological effects, including supplying calcium. However, how sesamin might prevent osteoporosis is still under study. Material/Methods Bone marrow stromal cells (BMSCs) extracted from rat femur were induced for osteoblastic differentiation. Cell proliferation, alkaline phosphatase (ALP), osterix (OSX), SRY-box 9 (SOX9), runt-related transcription factor 2 (RUNX2), osteocalcin (OCN), β-catenin, low density lipoprotein receptor-related protein 5 (LRP5), and glycogen synthase kinase-3β (GSK-3β) levels in BMSCs were detected in the presence or absence of sesamin (1 μM or 10 μM). In addition, FH535 (1 μM) was used to silence Wnt/β-catenin in vitro. Ovariectomized (OVX) rats were established and intragastrically administrated sesamin (80 mg/kg), and then the rat bones were analyzed by micro-computed tomography. Osteocalcin and collagen type I were measured in the rat femurs. Results Sesamin had no influence on BMSC proliferation. Higher sesamin concentration promoted Wnt/β-catenin activity and enhanced more expressions of ALP, OSX, SOX9, RUNX2, and OCN, gradually and significantly (P<0.05). Silencing Wnt/β-catenin weakened the enhancement on RUNX2 and OCN expression. Sesamin (80 mg/kg) promoted bone structure in ovariectomized rats, and significantly enhanced osteocalcin and collage type I expression (P<0.05). Conclusions Sesamin promoted osteoblastic differentiation of rat BMSCs by regulating the Wnt/β-catenin pathway, and improved rat bone structure. Sesamin could have therapeutic and preventive effects on osteoporosis.
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Affiliation(s)
- Zhong-Ping Ma
- Department of Orthopedics, The Second Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia, China (mainland)
| | - Zhi-Feng Zhang
- Department of Orthopedics, The Second Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia, China (mainland)
| | - Yi-Feng Yang
- Department of Orthopedics, The Second Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia, China (mainland)
| | - Yun Yang
- Department of Orthopedics, The Second Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia, China (mainland)
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9
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Harasymowicz NS, Dicks A, Wu CL, Guilak F. Physiologic and pathologic effects of dietary free fatty acids on cells of the joint. Ann N Y Acad Sci 2019; 1440:36-53. [PMID: 30648276 DOI: 10.1111/nyas.13999] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 12/08/2018] [Accepted: 12/14/2018] [Indexed: 12/14/2022]
Abstract
Fatty acids (FAs) are potent organic compounds that not only can be used as an energy source during nutrient deprivation but are also involved in several essential signaling cascades in cells. Therefore, a balanced intake of different dietary FAs is critical for the maintenance of cellular functions and tissue homeostasis. A diet with an imbalanced fat composition creates a risk for developing metabolic syndrome and various musculoskeletal diseases, including osteoarthritis (OA). In this review, we summarize the current state of knowledge and mechanistic insights regarding the role of dietary FAs, such as saturated FAs, omega-6 polyunsaturated FAs (PUFAs), and omega-3 PUFAs on joint inflammation and OA pathogeneses. In particular, we review how different types of dietary FAs and their derivatives distinctly affect a variety of cells within the joint, including chondrocytes, osteoblasts, osteoclasts, and synoviocytes. Understanding the molecular mechanisms underlying the effects of FAs on metabolic behavior, anabolic, and catabolic processes, as well as the inflammatory response of joint cells, may help identify therapeutic targets for the prevention of metabolic joint diseases.
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Affiliation(s)
- Natalia S Harasymowicz
- Department of Orthopaedic Surgery, Washington University, St. Louis, Missouri.,Shriners Hospitals for Children-St. Louis, St. Louis, Missouri
| | - Amanda Dicks
- Department of Orthopaedic Surgery, Washington University, St. Louis, Missouri.,Shriners Hospitals for Children-St. Louis, St. Louis, Missouri.,Department of Biomedical Engineering, Washington University, St. Louis, Missouri
| | - Chia-Lung Wu
- Department of Orthopaedic Surgery, Washington University, St. Louis, Missouri.,Shriners Hospitals for Children-St. Louis, St. Louis, Missouri
| | - Farshid Guilak
- Department of Orthopaedic Surgery, Washington University, St. Louis, Missouri.,Shriners Hospitals for Children-St. Louis, St. Louis, Missouri.,Department of Biomedical Engineering, Washington University, St. Louis, Missouri
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10
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Beekman KM, Veldhuis-Vlug AG, van der Veen A, den Heijer M, Maas M, Kerckhofs G, Parac-Vogt TN, Bisschop PH, Bravenboer N. The effect of PPARγ inhibition on bone marrow adipose tissue and bone in C3H/HeJ mice. Am J Physiol Endocrinol Metab 2019; 316:E96-E105. [PMID: 30457914 DOI: 10.1152/ajpendo.00265.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Bone marrow adipose tissue (BMAT) increases after menopause, and increased BMAT is associated with osteoporosis and prevalent vertebral fractures. Peroxisome proliferator-activated receptor-γ (PPARγ) activation promotes adipogenesis and inhibits osteoblastogenesis; therefore, PPARγ is a potential contributor to the postmenopausal increase in BMAT and decrease in bone mass. The aim of this study is to determine if PPARγ inhibition can prevent ovariectomy-induced BMAT increase and bone loss in C3H/HeJ mice. Fourteen-week-old female C3H/HeJ mice ( n = 40) were allocated to four intervention groups: sham surgery (Sham) or ovariectomy (OVX; isoflurane anesthesia) with either vehicle (Veh) or PPARγ antagonist administration (GW9662; 1 mg·kg-1·day-1, daily intraperitoneal injections) for 3 wk. We measured BMAT volume, adipocyte size, adipocyte number. and bone structural parameters in the proximal metaphysis of the tibia using polyoxometalate-based contrast enhanced-nanocomputed topogaphy. Bone turnover was measured in the contralateral tibia using histomorphometry. The effects of surgery and treatment were analyzed by two-way ANOVA. OVX increased the BMAT volume fraction (Sham + Veh: 2.9 ± 2.7% vs. OVX + Veh: 8.1 ± 5.0%: P < 0.001), average adipocyte diameter (Sham + Veh: 19.3 ± 2.6 μm vs. OVX + Veh: 23.1 ± 3.4 μm: P = 0.001), and adipocyte number (Sham + Veh: 584 ± 337cells/μm3 vs. OVX + Veh: 824 ± 113cells/μm3: P = 0.03), while OVX decreased bone volume fraction (Sham + Veh: 15.5 ± 2.8% vs. OVX + Veh: 7.7 ± 1.9%; P < 0.001). GW9662 had no effect on BMAT, bone structural parameters, or bone turnover. In conclusion, ovariectomy increased BMAT and decreased bone volume in C3H/HeJ mice. The PPARγ antagonist GW9662 had no effect on BMAT or bone volume in C3H/HeJ mice, suggesting that BMAT accumulation is regulated independently of PPARγ in C3H/HeJ mice.
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Affiliation(s)
- Kerensa M Beekman
- Amsterdam Movement Sciences, Section of Endocrinology, Department of Internal Medicine, Vrije Universiteit, Amsterdam University Medical Center , Amsterdam , The Netherlands
- Amsterdam Movement Sciences, Department of Radiology and Nuclear Medicine, University of Amsterdam, Amsterdam University Medical Center , Amsterdam , The Netherlands
| | - Annegreet G Veldhuis-Vlug
- Amsterdam Movement Sciences, Department of Endocrinology and Metabolism, University of Amsterdam, Amsterdam University Medical Center , Amsterdam , The Netherlands
| | - Albert van der Veen
- Department of Physics and Medical Technology, Vrije Universiteit, Amsterdam University Medical Center , Amsterdam , The Netherlands
- Department Cardiology, Vrije Universiteit, Amsterdam University Medical Center , Amsterdam , The Netherlands
| | - Martin den Heijer
- Amsterdam Movement Sciences, Section of Endocrinology, Department of Internal Medicine, Vrije Universiteit, Amsterdam University Medical Center , Amsterdam , The Netherlands
| | - Mario Maas
- Amsterdam Movement Sciences, Department of Radiology and Nuclear Medicine, University of Amsterdam, Amsterdam University Medical Center , Amsterdam , The Netherlands
| | - Greet Kerckhofs
- Biomechanics Laboratory, Institute of Mechanics, Materials, and Civil Engineering, Université Catholique de Louvain , Louvain-la-Neuve , Belgium
- Department Materials Engineering, KU Leuven , Leuven , Belgium
- Prometheus, Division of Skeletal Tissue Engineering, KU Leuven , Leuven , Belgium
| | - Tatjana N Parac-Vogt
- Laboratory of Bioinorganic Chemistry, Chemistry Department, KU Leuven , Leuven , Belgium
| | - Peter H Bisschop
- Amsterdam Movement Sciences, Department of Endocrinology and Metabolism, University of Amsterdam, Amsterdam University Medical Center , Amsterdam , The Netherlands
| | - Nathalie Bravenboer
- Amsterdam Movement Sciences, Research Laboratory Bone and Calcium Metabolism, Department of Clinical Chemistry, Vrije Universiteit, Amsterdam University Medical Center , Amsterdam , The Netherlands
- Department of Internal Medicine, Leiden University Medical Center , Leiden, The Netherlands
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11
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Li Y, Meng Y, Yu X. The Unique Metabolic Characteristics of Bone Marrow Adipose Tissue. Front Endocrinol (Lausanne) 2019; 10:69. [PMID: 30800100 PMCID: PMC6375842 DOI: 10.3389/fendo.2019.00069] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 01/24/2019] [Indexed: 02/05/2023] Open
Abstract
Bone marrow adipose tissue (MAT) is distinct from white adipose tissue (WAT) or brown adipose tissue (BAT) for its location, feature and function. As a largely ignored adipose depot, it is situated in bone marrow space and resided with bone tissue side-by-side. MAT is considered not only as a regulator of bone metabolism through paracrine, but also as a functionally particular adipose tissue that may contribute to global metabolism. Adipokines, inflammatory factors and other molecules derived from bone marrow adipocytes may exert systematic effects. In this review, we summary the evidence from several aspects including development, distribution, histological features and phenotype to elaborate the basic characteristics of MAT. We discuss the association between bone metabolism and MAT, and highlight our current understanding of this special adipose tissue. We further demonstrate the probable relationship between MAT and energy metabolism, as well as glucose metabolism. On the basis of preliminary results from animal model and clinical studies, we propose that MAT has its unique secretory and metabolic function, although there is no in-depth study at present.
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Affiliation(s)
- Yujue Li
- Laboratory of Endocrinology and Metabolism, Department of Endocrinology and Metabolism and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Yang Meng
- Laboratory of Endocrinology and Metabolism, Department of Endocrinology and Metabolism and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
- Department of Orthopedics, West China Hospital, Sichuan University, Chengdu, China
| | - Xijie Yu
- Laboratory of Endocrinology and Metabolism, Department of Endocrinology and Metabolism and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
- *Correspondence: Xijie Yu ;
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12
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Abstract
PURPOSE OF REVIEW Mesenchymal stem cells (MSCs) located in the bone marrow have the capacity to differentiate into multiple cell lineages, including osteoblast and adipocyte. Adipocyte density within marrow is inversely associated with bone mass during aging and in some pathological conditions, contributing to the prevailing view that marrow adipocytes play a largely negative role in bone metabolism. However, a negative association between marrow adipocytes and bone balance is not universal. Although MAT levels appear tightly regulated, establishing the precise physiological significance of MAT has proven elusive. Here, we review recent literature aimed at delineating the function of MAT. RECENT FINDINGS An important physiological function of MAT may be to provide an expandable/contractible fat depot, which is critical for minimization of energy requirements for sustaining optimal hematopoiesis. Because the energy requirements for storing fat are negligible compared to those required to maintain hematopoiesis, even small reductions in hematopoietic tissue volume to match a reduced requirement for hematopoiesis could represent an important reduction in energy cost. Such a physiological function would require tight coupling between hematopoietic stem cells and MSCs to regulate the balance between MAT and hematopoiesis. Kit-ligand, an important regulator of proliferation, differentiation, and survival of hematopoietic cells, may function as a prototypic factor coupling MAT and hematopoiesis. Crosstalk between hematopoietic and mesenchymal cells in the bone marrow may contribute to establishing the balance between MAT levels and hematopoiesis.
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Affiliation(s)
- Russell T Turner
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, 97331, USA
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR, 97331, USA
| | - Stephen A Martin
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, 97331, USA
| | - Urszula T Iwaniec
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, 97331, USA.
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR, 97331, USA.
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13
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Zhu S, He H, Gao C, Luo G, Xie Y, Wang H, Tian L, Chen X, Yu X, He C. Ovariectomy-induced bone loss in TNFα and IL6 gene knockout mice is regulated by different mechanisms. J Mol Endocrinol 2018; 60:185-198. [PMID: 29339399 DOI: 10.1530/jme-17-0218] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 01/15/2018] [Indexed: 02/05/2023]
Abstract
We examined the effects of tumor necrosis factor-α (TNFα) and interleukin-6 (IL6) gene knockout in preserving the bone loss induced by ovariectomy (OVX) and the mechanisms involved in bone metabolism. Twenty female wild-type (WT), TNFα-knockout (TNFα-/-) or IL6-knockout (IL6-/-) mice aged 12 weeks were sham-operated (SHAM) or subjected to OVX and killed after 4 weeks. Bone mass and skeletal microarchitecture were determined using micro-CT. Bone marrow stromal cells (BMSCs) from all three groups (WT, TNFα-/- and IL6-/-) were induced to differentiate into osteoblasts or osteoclasts and treated with 17-β-estradiol. Bone metabolism was assessed by histological analysis, serum analyses and qRT-PCR. OVX successfully induced a high turnover in all mice, but a repair effect was observed in TNFα-/- and IL6-/- mice. The ratio of femoral trabecular bone volume to tissue volume, trabecular number and trabecular thickness were significantly decreased in WT mice subjected to OVX, but increased in TNFα-/- mice (1.62, 1.34, 0.27-fold respectively; P < 0.01) and IL6-/- mice (1.34, 0.80, 0.22-fold respectively; P < 0.01). Furthermore, we observed a 29.6% increase in the trabecular number in TNFα-/- mice when compared to the IL6-/- mice. Both, TNFα-/- and IL6-/- BMSCs exhibited decreased numbers of TRAP-positive cells and an increase in ALP-positive cells, with or without E2 treatment (P < 0.05). While the knockout of TNFα or IL6 significantly upregulated mRNA expressions of osteoblast-related genes (Runx2 and Col1a1) and downregulated osteoclast-related mRNA for TRAP, MMP9 and CTSK in vivo and in vitro, TNFα knockout appeared to have roles beyond IL6 knockout in upregulating Col1a1 mRNA expression and downregulating mRNA expressions of WNT-related genes (DKK1 and Sost) and TNF-related activation-induced genes (TRAF6). TNFα seemed to be more potentially invasive in inhibiting bone formation and enhancing TRAF6-mediated osteoclastogenesis than IL6, implying that the regulatory mechanisms of TNFα and IL6 in bone metabolism may be different.
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Affiliation(s)
- Siyi Zhu
- Rehabilitation Medicine CenterWest China Hospital, Sichuan University, Chengdu, China
- Rehabilitation Key Laboratory of Sichuan ProvinceWest China Hospital, Sichuan University, Chengdu, China
- Laboratory of Endocrinology and MetabolismDepartment of Endocrinology, National Key Laboratory of Biotherapy/Collaborative Innovation Center of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Hongchen He
- Rehabilitation Medicine CenterWest China Hospital, Sichuan University, Chengdu, China
| | - Chengfei Gao
- Rehabilitation Medicine CenterWest China Hospital, Sichuan University, Chengdu, China
- Rehabilitation Key Laboratory of Sichuan ProvinceWest China Hospital, Sichuan University, Chengdu, China
- Institute for Disaster Management and ReconstructionSichuan University-The Hong Kong Polytechnic University, Chengdu, China
| | - Guojing Luo
- Laboratory of Endocrinology and MetabolismDepartment of Endocrinology, National Key Laboratory of Biotherapy/Collaborative Innovation Center of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Ying Xie
- Laboratory of Endocrinology and MetabolismDepartment of Endocrinology, National Key Laboratory of Biotherapy/Collaborative Innovation Center of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Haiming Wang
- Rehabilitation Medicine CenterWest China Hospital, Sichuan University, Chengdu, China
- Rehabilitation Key Laboratory of Sichuan ProvinceWest China Hospital, Sichuan University, Chengdu, China
| | - Li Tian
- Laboratory of Endocrinology and MetabolismDepartment of Endocrinology, National Key Laboratory of Biotherapy/Collaborative Innovation Center of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Xiang Chen
- Laboratory of Endocrinology and MetabolismDepartment of Endocrinology, National Key Laboratory of Biotherapy/Collaborative Innovation Center of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Xijie Yu
- Laboratory of Endocrinology and MetabolismDepartment of Endocrinology, National Key Laboratory of Biotherapy/Collaborative Innovation Center of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Chengqi He
- Rehabilitation Medicine CenterWest China Hospital, Sichuan University, Chengdu, China
- Rehabilitation Key Laboratory of Sichuan ProvinceWest China Hospital, Sichuan University, Chengdu, China
- Institute for Disaster Management and ReconstructionSichuan University-The Hong Kong Polytechnic University, Chengdu, China
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14
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Zhou S, Wang G, Qiao L, Ge Q, Chen D, Xu Z, Shi D, Dai J, Qin J, Teng H, Jiang Q. Age-dependent variations of cancellous bone in response to ovariectomy in C57BL/6J mice. Exp Ther Med 2018; 15:3623-3632. [PMID: 29545892 DOI: 10.3892/etm.2018.5839] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 12/21/2017] [Indexed: 11/05/2022] Open
Abstract
The ovariectomized (OVX) mouse model has been widely accepted to be suitable for the study of postmenopausal osteoporosis. However, whether C57BL/6J mice, a commonly used genetic background mouse strain, is an appropriate model for postmenopausal osteoporosis remains controversial. The present study investigated the effect of the OVX model on alterations in bone density and microarchitecture in C57BL/6J female mice of different ages. C57BL/6J mice were divided into 8-, 12- and 16-week-old groups (OVX8, OVX12 and OVX16) from the beginning of OVX. At 8 weeks post-surgery, the mice were anesthetized and micro-computed tomography was used to analyze the bone density and microarchitecture. The results revealed that OVX-induced loss of cancellous bone was greatest in OVX8, moderate in OVX12, and only a weak bone loss was observed in the OVX16 group when compared with the SHAM16 control group. In addition, the effect of genetic backgrounds in response to the OVX model were examined. Several other strains of mice, including inbred (BALB/c) and outbred (ICR and Kunming), were used in the present study, all of which were subjected to OVX at 8 weeks of age. The present findings revealed that the highest rate of bone loss was detected in C57BL/6J female mice. In addition, treatment with estrogen (17β-estradiol, 30 µg/kg five times per week) led to a significant increase in bone density in C57BL/6J mice compared with the other strains of mice. Therefore, these results may provide novel insights into the age- and strain-associated effect of OVX on regulating turnover of bone in female mice. The present findings also suggest 8-week-old C57BL/6J mice as an animal model for postmenopausal osteoporosis and preclinical testing of potential therapies for this disease.
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Affiliation(s)
- Sheng Zhou
- The Center of Diagnosis and Treatment for Joint Disease, Drum Tower Hospital, Medical School, Nanjing University, Nanjing, Jiangsu 210008, P.R. China
| | - Guanghu Wang
- The Center of Diagnosis and Treatment for Joint Disease, Drum Tower Hospital, Medical School, Nanjing University, Nanjing, Jiangsu 210008, P.R. China
| | - Liang Qiao
- The Center of Diagnosis and Treatment for Joint Disease, Drum Tower Hospital, Medical School, Nanjing University, Nanjing, Jiangsu 210008, P.R. China
| | - Qiting Ge
- Joint Research Center for Bone and Joint Disease, Model Animal Research Center (MARC), Nanjing University, Nanjing, Jiangsu 210061, P.R. China
| | - Dongyang Chen
- The Center of Diagnosis and Treatment for Joint Disease, Drum Tower Hospital, Medical School, Nanjing University, Nanjing, Jiangsu 210008, P.R. China
| | - Zhihong Xu
- The Center of Diagnosis and Treatment for Joint Disease, Drum Tower Hospital, Medical School, Nanjing University, Nanjing, Jiangsu 210008, P.R. China
| | - Dongquan Shi
- The Center of Diagnosis and Treatment for Joint Disease, Drum Tower Hospital, Medical School, Nanjing University, Nanjing, Jiangsu 210008, P.R. China
| | - Jin Dai
- The Center of Diagnosis and Treatment for Joint Disease, Drum Tower Hospital, Medical School, Nanjing University, Nanjing, Jiangsu 210008, P.R. China
| | - Jinzhong Qin
- Joint Research Center for Bone and Joint Disease, Model Animal Research Center (MARC), Nanjing University, Nanjing, Jiangsu 210061, P.R. China
| | - Huajian Teng
- The Center of Diagnosis and Treatment for Joint Disease, Drum Tower Hospital, Medical School, Nanjing University, Nanjing, Jiangsu 210008, P.R. China.,Joint Research Center for Bone and Joint Disease, Model Animal Research Center (MARC), Nanjing University, Nanjing, Jiangsu 210061, P.R. China
| | - Qing Jiang
- The Center of Diagnosis and Treatment for Joint Disease, Drum Tower Hospital, Medical School, Nanjing University, Nanjing, Jiangsu 210008, P.R. China.,Joint Research Center for Bone and Joint Disease, Model Animal Research Center (MARC), Nanjing University, Nanjing, Jiangsu 210061, P.R. China
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15
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Thompson WR, Yen SS, Uzer G, Xie Z, Sen B, Styner M, Burridge K, Rubin J. LARG GEF and ARHGAP18 orchestrate RhoA activity to control mesenchymal stem cell lineage. Bone 2018; 107:172-180. [PMID: 29208526 PMCID: PMC5743610 DOI: 10.1016/j.bone.2017.12.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 11/29/2017] [Accepted: 12/01/2017] [Indexed: 02/02/2023]
Abstract
The quantity and quality of bone depends on osteoblastic differentiation of mesenchymal stem cells (MSCs), where adipogenic commitment depletes the available pool for osteogenesis. Cell architecture influences lineage decisions, where interfering with cytoskeletal structure promotes adipogenesis. Mechanical strain suppresses MSC adipogenesis partially through RhoA driven enhancement of cytoskeletal structure. To understand the basis of force-driven RhoA activation, we considered critical GEFs (activators) and GAPs (inactivators) on bone marrow MSC lineage fate. Knockdown of LARG accelerated adipogenesis and repressed basal RhoA activity. Importantly, mechanical activation of RhoA was almost entirely inhibited following LARG depletion, and the ability of strain to inhibit adipogenesis was impaired. Knockdown of ARHGAP18 increased basal RhoA activity and actin stress fiber formation, but did not enhance mechanical strain activation of RhoA. ARHGAP18 null MSCs exhibited suppressed adipogenesis assessed by Oil-Red-O staining and Western blot of adipogenic markers. Furthermore, ARHGAP18 knockdown enhanced osteogenic commitment, confirmed by alkaline phosphatase staining and qPCR of Sp7, Alpl, and Bglap genes. This suggests that ARHGAP18 conveys tonic inhibition of MSC cytoskeletal assembly, returning RhoA to an "off state" and affecting cell lineage in the static state. In contrast, LARG is recruited during dynamic mechanical strain, and is necessary for mechanical suppression of adipogenesis. In summary, mechanical activation of RhoA in mesenchymal progenitors is dependent on LARG, while ARHGAP18 limits RhoA delineated cytoskeletal structure in static cultures. Thus, on and off GTP exchangers work through RhoA to influence MSC fate and responses to static and dynamic physical factors in the microenvironment.
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Affiliation(s)
- William R Thompson
- Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, United States.
| | - Sherwin S Yen
- Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, United States.
| | - Gunes Uzer
- Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, United States; Department of Mechanical and Biomedical Engineering, Boise State University, Boise, ID 83725, United States.
| | - Zhihui Xie
- Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, United States.
| | - Buer Sen
- Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, United States.
| | - Maya Styner
- Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, United States.
| | - Keith Burridge
- Department of Cell Biology and Physiology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, United States.
| | - Janet Rubin
- Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, United States.
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16
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Shen G, Ren H, Qiu T, Zhang Z, Zhao W, Yu X, Huang J, Tang J, Liang D, Yao Z, Yang Z, Jiang X. Mammalian target of rapamycin as a therapeutic target in osteoporosis. J Cell Physiol 2017; 233:3929-3944. [PMID: 28834576 DOI: 10.1002/jcp.26161] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 08/21/2017] [Indexed: 12/19/2022]
Abstract
The mechanistic target of rapamycin (mTOR) plays a key role in sensing and integrating large amounts of environmental cues to regulate organismal growth, homeostasis, and many major cellular processes. Recently, mounting evidences highlight its roles in regulating bone homeostasis, which sheds light on the pathogenesis of osteoporosis. The activation/inhibition of mTOR signaling is reported to positively/negatively regulate bone marrow mesenchymal stem cells (BMSCs)/osteoblasts-mediated bone formation, adipogenic differentiation, osteocytes homeostasis, and osteoclasts-mediated bone resorption, which result in the changes of bone homeostasis, thereby resulting in or protect against osteoporosis. Given the likely importance of mTOR signaling in the pathogenesis of osteoporosis, here we discuss the detailed mechanisms in mTOR machinery and its association with osteoporosis therapy.
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Affiliation(s)
- Gengyang Shen
- Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Hui Ren
- Department of Spinal Surgery, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Ting Qiu
- Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Zhida Zhang
- Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Wenhua Zhao
- Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Xiang Yu
- Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Jinjing Huang
- Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Jingjing Tang
- Department of Spinal Surgery, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - De Liang
- Department of Spinal Surgery, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Zhensong Yao
- Department of Spinal Surgery, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Zhidong Yang
- Department of Spinal Surgery, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Xiaobing Jiang
- Department of Spinal Surgery, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China.,Laboratory Affiliated to National Key Discipline of Orthopaedic and Traumatology of Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, China
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17
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Hao L, Fu J, Tian Y, Wu J. Systematic analysis of lncRNAs, miRNAs and mRNAs for the identification of biomarkers for osteoporosis in the mandible of ovariectomized mice. Int J Mol Med 2017; 40:689-702. [PMID: 28713971 PMCID: PMC5547976 DOI: 10.3892/ijmm.2017.3062] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 06/29/2017] [Indexed: 12/19/2022] Open
Abstract
Osteoporosis is a complex and multifactorial disease caused by an imbalance between bone formation and resorption. Post-menopausal women with endogenous estrogen deficiency suffer from systemic bone loss and osteoporosis, and are at high risk of this affecting the jaw bones. MicroRNAs (miRNAs or miRs) have been implicated in the mechanisms of metabolic bone diseases and are expressed at differential levels in alveolar bone following ovariectomy. In the present study, we systematically analyzed the expression profiles of miRNAs, mRNAs and long non-coding RNA (lncRNAs) in the mandible of ovariectomized (OVX) mice. A complex miRNA-mRNA-lncRNA regulatory network was constructed based on differentially expressed RNAs. Two core differentially expressed genes (DEGs), namely, LRP2 binding protein (Lrp2bp) and perilipin 4 (Plin4), significantly influenced the network targeted by differentially expressed miRNAs. Moreover, peroxisome proliferator-activated receptor (PPAR) and insulin signaling pathways were significantly dysregulated in the mandible of OVX mice. Several differentially expressed lncRNAs were also implicated in the two signaling pathways, which influenced mandible development by forming competing endogenous RNA. On the whole, our data indicate that the comprehensive analysis of miRNAs, mRNAs and lncRNAs provides insight into the pathogenesis of estrogen deficiency-induced osteoporosis in the mandible. This study proposes potential biomarkers for diagnosis or therapeutic targets for osteoporosis which may aid in the development of novel drugs for the treatment of osteoporosis.
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Affiliation(s)
- Lingyu Hao
- Department of Prosthodontics, School and Hospital of Stomatology, Tongji University and Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Shanghai 200072, P.R. China
| | - Jiayao Fu
- Department of Prosthodontics, School and Hospital of Stomatology, Tongji University and Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Shanghai 200072, P.R. China
| | - Yawen Tian
- Department of Prosthodontics, School and Hospital of Stomatology, Tongji University and Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Shanghai 200072, P.R. China
| | - Junhua Wu
- Department of Prosthodontics, School and Hospital of Stomatology, Tongji University and Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Shanghai 200072, P.R. China
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18
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Veldhuis-Vlug AG, Rosen CJ. Mechanisms of marrow adiposity and its implications for skeletal health. Metabolism 2017; 67:106-114. [PMID: 28081773 PMCID: PMC5325679 DOI: 10.1016/j.metabol.2016.11.013] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 11/02/2016] [Accepted: 11/22/2016] [Indexed: 12/11/2022]
Abstract
The bone marrow niche is composed of cells from hematopoietic and mesenchymal origin. Both require energy to power differentiation and these processes are intimately connected to systemic metabolic homeostasis. Glycolysis is the preferred substrate for mesenchymal stromal cells in the niche, although fatty acid oxidation and glutaminolysis are important during stage specific differentiation. Autophagy and lipophagy, in part triggered by adenosine monophosphate-activated protein kinase (AMPK), may also play an important but temporal specific role in osteoblast differentiation. Enhanced marrow adiposity is caused by clinical factors that are genetically, environmentally, and hormonally mediated. These determinants mediate a switch from the osteogenic to the adipogenic lineage. Preliminary evidence supports an important role for fuel utilization in those cell fate decisions. Although both the origin and function of the marrow adipocyte remain to be determined, and in some genetic mouse models high marrow adiposity may co-exist with greater bone mass, in humans changes in marrow adiposity are closely linked to adverse changes in skeletal metabolism. This supports an intimate relationship between bone and fat in the marrow. Future studies will likely shed more light on the relationship of cellular as well as whole body metabolism on the ultimate fate of bone marrow stromal cells.
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19
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Ge C, Cawthorn WP, Li Y, Zhao G, Macdougald OA, Franceschi RT. Reciprocal Control of Osteogenic and Adipogenic Differentiation by ERK/MAP Kinase Phosphorylation of Runx2 and PPARγ Transcription Factors. J Cell Physiol 2016. [PMID: 26206105 DOI: 10.1002/jcp.25102] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In many skeletal diseases, including osteoporosis and disuse osteopenia, defective osteoblast differentiation is associated with increased marrow adipogenesis. The relative activity of two transcription factors, RUNX2 and PPARγ, controls whether a mesenchymal cell will differentiate into an osteoblast or adipocyte. Herein we show that the ERK/MAP kinase pathway, an important mediator of mechanical and hormonal signals in bone, stimulates osteoblastogenesis and inhibits adipogenesis via phosphorylation of RUNX2 and PPARγ. Induction of osteoblastogenesis in ST2 mesenchymal cells was associated with increased MAPK activity and RUNX2 phosphorylation. Under these conditions PPARγ phosphorylation also increased, but adipogenesis was inhibited. In contrast, during adipogenesis MAPK activity and phosphorylation of both transcription factors was reduced. RUNX2 phosphorylation and transcriptional activity were directly stimulated by MAPK, a response requiring phosphorylation at S301 and S319. MAPK also inhibited PPARγ-dependent transcription via S112 phosphorylation. Stimulation of MAPK increased osteoblastogenesis and inhibited adipogenesis, while dominant-negative suppression of activity had the opposite effect. In rescue experiments using Runx2(-/-) mouse embryo fibroblasts (MEFs), wild type or, to a greater extent, phosphomimetic mutant RUNX2 (S301E,S319E) stimulated osteoblastogenesis while suppressing adipogenesis. In contrast, a phosphorylation-deficient RUNX2 mutant (S301A,S319A) had reduced activity. Conversely, wild type or, to a greater extent, phosphorylation-resistant S112A mutant PPARγ strongly stimulated adipogenesis and inhibited osteoblastogenesis in Pparg(-/-) MEFs, while S112E mutant PPARγ was less active. Competition between RUNX2 and PPARγ was also observed at the transcriptional level. Together, these studies highlight the importance of MAP kinase signaling and RUNX2/PPARγ phosphorylation in the control of osteoblast and adipocyte lineages.
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Affiliation(s)
- Chunxi Ge
- Department of Periodontics and Oral Medicine, School of Dentistry, University of Michigan, Ann Arbor, Michigan
| | - William P Cawthorn
- Molecular and Integrative Physiology, University of Michigan School of Medicine, Ann Arbor, Michigan
| | - Yan Li
- Department of Periodontics and Oral Medicine, School of Dentistry, University of Michigan, Ann Arbor, Michigan
| | - Guisheng Zhao
- Department of Periodontics and Oral Medicine, School of Dentistry, University of Michigan, Ann Arbor, Michigan
| | - Ormond A Macdougald
- Molecular and Integrative Physiology, University of Michigan School of Medicine, Ann Arbor, Michigan
| | - Renny T Franceschi
- Department of Periodontics and Oral Medicine, School of Dentistry, University of Michigan, Ann Arbor, Michigan.,Biological Chemistry, University of Michigan School of Medicine, Ann Arbor, Michigan
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20
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Lindenmaier LB, Philbrick KA, Branscum AJ, Kalra SP, Turner RT, Iwaniec UT. Hypothalamic Leptin Gene Therapy Reduces Bone Marrow Adiposity in ob/ob Mice Fed Regular and High-Fat Diets. Front Endocrinol (Lausanne) 2016; 7:110. [PMID: 27579023 PMCID: PMC4985531 DOI: 10.3389/fendo.2016.00110] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 08/02/2016] [Indexed: 12/14/2022] Open
Abstract
Low bone mass is often associated with elevated bone marrow adiposity. Since osteoblasts and adipocytes are derived from the same mesenchymal stem cell (MSC) progenitor, adipocyte formation may increase at the expense of osteoblast formation. Leptin is an adipocyte-derived hormone known to regulate energy and bone metabolism. Leptin deficiency and high-fat diet-induced obesity are associated with increased marrow adipose tissue (MAT) and reduced bone formation. Short-duration studies suggest that leptin treatment reduces MAT and increases bone formation in leptin-deficient ob/ob mice fed a regular diet. Here, we determined the long-duration impact of increased hypothalamic leptin on marrow adipocytes and osteoblasts in ob/ob mice following recombinant adeno-associated virus (rAAV) gene therapy. Eight- to 10-week-old male ob/ob mice were randomized into four groups: (1) untreated, (2) rAAV-Lep, (3) rAAV-green fluorescent protein (rAAV-GFP), or (4) pair-fed to rAAV-Lep. For vector administration, mice were injected intracerebroventricularly with either rAAV-leptin gene therapy (rAAV-Lep) or rAAV-GFP (9 × 10(7) particles) and maintained for 30 weeks. In a second study, the impact of increased hypothalamic leptin levels on MAT was determined in mice fed high-fat diets; ob/ob mice were randomized into two groups and treated with either rAAV-Lep or rAAV-GFP. At 7 weeks post-vector administration, half the mice in each group were switched to a high-fat diet for 8 weeks. Wild-type (WT) controls included age-matched mice fed regular or high-fat diet. High-fat diet resulted in a threefold increase in MAT in WT mice, whereas MAT was increased by leptin deficiency up to 50-fold. Hypothalamic leptin gene therapy increased osteoblast perimeter and osteoclast perimeter with minor change in cancellous bone architecture. The gene therapy decreased MAT levels in ob/ob mice fed regular or high-fat diet to values similar to WT mice fed regular diet. These findings suggest that leptin plays an important role in regulating the differentiation of MSCs to adipocytes and osteoblasts, a process that may be dysregulated by high-fat diet. However, the results also illustrate that reducing MAT by increasing leptin levels does not necessarily result in increased bone mass.
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Affiliation(s)
- Laurence B. Lindenmaier
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA
| | - Kenneth A. Philbrick
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA
| | - Adam J. Branscum
- Biostatistics Program, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA
| | - Satya P. Kalra
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL, USA
| | - Russell T. Turner
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR, USA
| | - Urszula T. Iwaniec
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR, USA
- *Correspondence: Urszula T. Iwaniec,
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21
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Zhang Y, Feng P, Yang J. High glucose-associated osmolality promotes adipocytogenic differentiation of primary rat osteoblasts in a protein kinase A and phosphatidylinositol 3-kinase/Akt-dependent manner. Biologia (Bratisl) 2015. [DOI: 10.1515/biolog-2015-0156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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22
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Liu JJ, Foo JP, Liu S, Lim SC. The role of fibroblast growth factor 21 in diabetes and its complications: A review from clinical perspective. Diabetes Res Clin Pract 2015; 108:382-9. [PMID: 25796513 DOI: 10.1016/j.diabres.2015.02.032] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 02/13/2015] [Accepted: 02/22/2015] [Indexed: 01/24/2023]
Abstract
Fibroblast growth factor 21 (FGF21) has been well-recognized as a metabolic hormone and a promising target for treatment of metabolic diseases. The level of endogenous FGF21 is elevated in patients with impaired glucose tolerance and progressively increased from patients with overt type 2 diabetes to those with micro- and macro-vascular complications, presumably as a compensation or response to the deterioration of metabolic imbalance. A few exploratory in vivo studies, including a recent clinical trial, showed that exogenous FGF21 mimetics targeting FGF21 signaling can attain beneficial metabolic effects not with-standing the already elevated ambient FGF21 levels. In addition, some clinically available pharmacologic agents such as fenofibrates and metformin may modulate energy and macronutrients metabolism by acting through FGF21. This review mainly focuses on the role of FGF21 in development, progression and treatment of type 2 diabetes from a clinical perspective.
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Affiliation(s)
- Jian-Jun Liu
- Clinical Research Unit, Khoo Teck Puat Hospital, Singapore.
| | - Joo Pin Foo
- Department of Medicine, Changi General Hospital, Singapore
| | - Sylvia Liu
- Clinical Research Unit, Khoo Teck Puat Hospital, Singapore
| | - Su Chi Lim
- Diabetes Center, Khoo Teck Puat Hospital, Singapore.
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23
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Bonnet N, Somm E, Rosen CJ. Diet and gene interactions influence the skeletal response to polyunsaturated fatty acids. Bone 2014; 68:100-7. [PMID: 25088402 PMCID: PMC4266596 DOI: 10.1016/j.bone.2014.07.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 07/09/2014] [Accepted: 07/22/2014] [Indexed: 11/16/2022]
Abstract
Diets rich in omega-3s have been thought to prevent both obesity and osteoporosis. However, conflicting findings are reported, probably as a result of gene by nutritional interactions. Peroxisome proliferator-activated receptor-gamma (PPARγ) is a nuclear receptor that improves insulin sensitivity but causes weight gain and bone loss. Fish oil is a natural agonist for PPARγ and thus may exert its actions through the PPARγ pathway. We examined the role of PPARγ in body composition changes induced by a fish or safflower oil diet using two strains of C57BL/6J (B6); i.e. B6.C3H-6T (6T) congenic mice created by backcrossing a small locus on Chr 6 from C3H carrying 'gain of function' polymorphisms in the Pparγ gene onto a B6 background, and C57BL/6J mice. After 9months of feeding both diets to female mice, body weight, percent fat and leptin levels were less in mice fed the fish oil vs those fed safflower oil, independent of genotype. At the skeletal level, fish oil preserved vertebral bone mineral density (BMD) and microstructure in B6 but not in 6T mice. Moreover, fish oil consumption was associated with an increase in bone marrow adiposity and a decrease in BMD, cortical thickness, ultimate force and plastic energy in femur of the 6T but not the B6 mice. These effects paralleled an increase in adipogenic inflammatory and resorption markers in 6T but not B6. Thus, compared to safflower oil, fish oil (high ratio omega-3/-6) prevents weight gain, bone loss, and changes in trabecular microarchitecture in the spine with age. These beneficial effects are absent in mice with polymorphisms in the Pparγ gene (6T), supporting the tenet that the actions of n-3 fatty acids on bone microstructure are likely to be genotype dependent. Thus caution must be used in interpreting dietary intervention trials with skeletal endpoints in mice and in humans.
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MESH Headings
- Adipose Tissue, Brown/anatomy & histology
- Adipose Tissue, Brown/drug effects
- Adipose Tissue, Brown/metabolism
- Adipose Tissue, White/anatomy & histology
- Adipose Tissue, White/drug effects
- Adipose Tissue, White/metabolism
- Adiposity/drug effects
- Adiposity/physiology
- Animals
- Biomarkers/metabolism
- Biomechanical Phenomena/drug effects
- Body Composition/drug effects
- Bone Density/drug effects
- Bone Marrow/drug effects
- Bone Marrow/physiology
- Bone and Bones/drug effects
- Bone and Bones/metabolism
- Cell Count
- Diet
- Dietary Supplements
- Fatty Acids, Omega-3/pharmacology
- Fatty Acids, Omega-6/pharmacology
- Female
- Femur/anatomy & histology
- Femur/drug effects
- Femur/physiology
- Fish Oils/pharmacology
- Gene Expression Regulation/drug effects
- Mice, Inbred C3H
- Mice, Inbred C57BL
- Organ Size/drug effects
- Osteoclasts/cytology
- Osteoclasts/drug effects
- Spine/anatomy & histology
- Spine/drug effects
- Spine/physiology
- Tibia/anatomy & histology
- Tibia/drug effects
- Tibia/physiology
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Affiliation(s)
- Nicolas Bonnet
- Division of Bone Diseases, Department of Internal Medicine Specialties, Geneva University Hospital & Faculty of Medicine, Geneva 14, Switzerland.
| | - Emmanuel Somm
- Service of Endocrinology, Diabetology, and Metabolism, Centre Hospitalier Universitaire Vaudois/Department of Physiology, Lausanne CH-1005, Switzerland; Division of Development and Growth, Department of Paediatrics, University of Geneva School of Medicine, 1211 Geneva 14, Switzerland
| | - Clifford J Rosen
- Maine Medical Center Research Institute, Scarborough, ME 04074, USA
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Sun H, Kim JK, Mortensen R, Mutyaba LP, Hankenson KD, Krebsbach PH. Osteoblast-targeted suppression of PPARγ increases osteogenesis through activation of mTOR signaling. Stem Cells 2014; 31:2183-92. [PMID: 23766271 DOI: 10.1002/stem.1455] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Revised: 05/03/2013] [Accepted: 05/21/2013] [Indexed: 01/21/2023]
Abstract
Nuclear receptor peroxisome proliferator-activated receptor-γ (PPARγ) is an essential transcription factor for adipocyte differentiation. In mesenchymal stem cells, PPARγ has been assumed to play a negative role in osteoblastic differentiation, by working in an adipogenesis dependent manner, due to the reciprocal relationship between osteoblast and adipocyte differentiation. However, the direct role of PPARγ in osteoblast function is not fully understood, due in part to inadequate model systems. Here, we describe an adenoviral-mediated PPARγ knockout system in which suppression of PPARγ in mesenchymal stem cells enhanced osteoblast differentiation and inhibited adipogenesis in vitro. Consistent with this in vitro observation, lipoatrophic A-ZIP/F1 mice, which do not form adipocytes, displayed a phenotype in which both cortical and trabecular bone was significantly increased compared with wild-type mice. We next developed an inducible osteoblast-targeted PPARγ knockout (Osx Cre/flox- PPARγ) mouse to determine the direct role of PPARγ in bone formation. Data from both in vitro cultures of mesenchymal stem cells and in vivo µCT analysis of bones suggest that suppression of PPARγ activity in osteoblasts significantly increased osteoblast differentiation and trabecular number. Endogenous PPARγ in mesenchymal stem cells and osteoblasts strongly inhibited Akt/mammalian target of rapamycin (mTOR)/p70S6k activity and led to decreased osteoblastic differentiation. Therefore, we conclude that PPARγ modulates osteoblast differentiation and bone formation through both direct and indirect mechanisms. The direct mode, as shown here, involves PPARγ regulation of the mTOR pathway, while the indirect pathway is dependent on the regulation of adipogenesis.
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Affiliation(s)
- Hongli Sun
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA
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25
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An JH, Ohn JH, Song JA, Yang JY, Park H, Choi HJ, Kim SW, Kim SY, Park WY, Shin CS. Changes of microRNA profile and microRNA-mRNA regulatory network in bones of ovariectomized mice. J Bone Miner Res 2014; 29:644-56. [PMID: 23929739 DOI: 10.1002/jbmr.2060] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 06/30/2013] [Accepted: 07/24/2013] [Indexed: 12/25/2022]
Abstract
Growing evidence shows the possibility of a role of microRNAs (miRNA) in regulating bone mass. We investigated the change of miRNAs and mRNA expression profiles in bone tissue in an ovariectomized mice model and evaluated the regulatory mechanism of bone mass mediated by miRNAs in an estrogen-deficiency state. Eight-week-old female C3H/HeJ mice underwent ovariectomy (OVX) or sham operation (Sham-op), and their femur and tibia were harvested to extract total bone RNAs after 4 weeks for microarray analysis. Eight miRNAs (miR-127, -133a, -133a*, -133b, -136, -206, -378, -378*) were identified to be upregulated after OVX, whereas one miRNA (miR-204) was downregulated. Concomitant analysis of mRNA microarray revealed that 658 genes were differentially expressed between OVX and Sham-op mice. Target prediction of differentially expressed miRNAs identified potential targets, and integrative analysis using the mRNA microarray results showed that PPARγ and CREB pathways are activated in skeletal tissues after ovariectomy. Among the potential candidates of miRNA, we further studied the role of miR-127 in vitro, which exhibited the greatest changes after OVX. We also studied the effects of miR-136, which has not been studied in the context of bone mass regulation. Transfection of miR-127 inhibitor has enhanced osteoblastic differentiation in UAMS-32 cells as measured by alkaline phosphatase activities and mRNA expression of osteoblast-specific genes, whereas miR-136 precursor has inhibited osteoblastic differentiation. Furthermore, transfection of both miR-127 and miR-136 inhibitors enhanced the osteocyte-like morphological changes and survival in MLO-Y4 cells, whereas precursors of miR-127 and -136 have aggravated dexamethasone-induced cell death. Both of the precursors enhanced osteoclastic differentiation in bone marrow macrophages, indicating that both miR-127 and -136 are negatively regulating bone mass. Taken together, these results suggest a novel insight into the association between distinct miRNAs expression and their possible role through regulatory network with mRNAs in the pathogenesis of estrogen deficiency-induced osteoporosis.
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Affiliation(s)
- Jee Hyun An
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea; Department of Internal Medicine, Konkuk University Medical Center, Seoul, Korea
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26
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Phorbaketal A inhibits adipogenic differentiation through the suppression of PPARγ-mediated gene transcription by TAZ. Eur J Pharmacol 2013; 718:181-7. [DOI: 10.1016/j.ejphar.2013.08.035] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 08/21/2013] [Accepted: 08/30/2013] [Indexed: 01/30/2023]
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27
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Cho SW, An JH, Park H, Yang JY, Choi HJ, Kim SW, Park YJ, Kim SY, Yim M, Baek WY, Kim JE, Shin CS. Positive regulation of osteogenesis by bile acid through FXR. J Bone Miner Res 2013; 28:2109-21. [PMID: 23609136 DOI: 10.1002/jbmr.1961] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Revised: 03/11/2013] [Accepted: 04/08/2013] [Indexed: 01/17/2023]
Abstract
Farnesoid X receptor (FXR) is a nuclear receptor that functions as a bile acid sensor controlling bile acid homeostasis. We investigated the role of FXR in regulating bone metabolism. We identified the expression of FXR in calvaria and bone marrow cells, which gradually increased during osteoblastic differentiation in vitro. In male mice, deletion of FXR (FXR(-/-) ) in vivo resulted in a significant reduction in bone mineral density by 4.3% to 6.6% in mice 8 to 20 weeks of age compared with FXR(+/+) mice. Histological analysis of the lumbar spine showed that FXR deficiency reduced the bone formation rate as well as the trabecular bone volume and thickness. Moreover, tartrate-resistant acid phosphatase (TRACP) staining of the femurs revealed that both the osteoclast number and osteoclast surface were significantly increased in FXR(-/-) mice compared with FXR(+/+) mice. At the cellular level, induction of alkaline phosphatase (ALP) activities was blunted in primary calvarial cells in FXR(-/-) mice compared with FXR(+/+) mice in concert with a significant reduction in type I collagen a1(Col1a1), ALP, and runt-related transcription factor 2 (Runx2) gene expressions. Cultures of bone marrow-derived macrophages from FXR(-/-) mice exhibited an increased number of osteoclast formations and protein expression of nuclear factor of activated T cells, cytoplasmic 1 (NFATc1). In female FXR(-/-) mice, although bone mineral density (BMD) was not significantly different from that in FXR(+/+) mice, bone loss was accelerated after an ovariectomy compared with FXR(+/+) mice. In vitro, activation of FXR by bile acids (chenodeoxycholic acid [CDCA] or 6-ECDCA) or FXR agonists (GW4064 or Fexaramine) significantly enhanced osteoblastic differentiation through the upregulation of Runx2 and enhanced extracellular signal-regulated kinase (ERK) and β-catenin signaling. FXR agonists also suppressed osteoclast differentiation from bone marrow macrophages. Finally, administration of a farnesol (FOH 1%) diet marginally prevented ovariectomy (OVX)-induced bone loss and enhanced bone mass gain in growing C57BL/6J mice. Taken together, these results suggest that FXR positively regulates bone metabolism through both arms of the bone remodeling pathways; ie, bone formation and resorption.
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Affiliation(s)
- Sun Wook Cho
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
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28
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Zhang Y, Yang JH. Activation of the PI3K/Akt pathway by oxidative stress mediates high glucose-induced increase of adipogenic differentiation in primary rat osteoblasts. J Cell Biochem 2013; 114:2595-602. [DOI: 10.1002/jcb.24607] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 05/31/2013] [Indexed: 11/12/2022]
Affiliation(s)
- Yu Zhang
- College of Life Science; University of Chinese Academy of Sciences; 19A Yuquan Road; Beijing; 100049; People's Republic of China
| | - Jian-Hong Yang
- College of Life Science; University of Chinese Academy of Sciences; 19A Yuquan Road; Beijing; 100049; People's Republic of China
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29
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Feeding blueberry diets to young rats dose-dependently inhibits bone resorption through suppression of RANKL in stromal cells. PLoS One 2013; 8:e70438. [PMID: 23936431 PMCID: PMC3735613 DOI: 10.1371/journal.pone.0070438] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 06/18/2013] [Indexed: 11/19/2022] Open
Abstract
Previous studies have demonstrated that weanling rats fed AIN-93G semi-purified diets supplemented with 10% whole blueberry (BB) powder for two weeks beginning on postnatal day 21 (PND21) significantly increased bone formation at PND35. However, the minimal level of dietary BB needed to produce these effects is, as yet, unknown. The current study examined the effects of three different levels of BB diet supplementation (1, 3, and 5%) for 35 days beginning on PND25 on bone quality, and osteoclastic bone resorption in female rats. Peripheral quantitative CT scan (pQCT) of tibia, demonstrated that bone mineral density (BMD) and content (BMC) were dose-dependently increased in BB-fed rats compared to controls (P<0.05). Significantly increased bone mass after feeding 5% BB extracts was also observed in a TEN (total enteral nutrition) rat model in which daily caloric and food intake was precisely controlled. Expression of RANKL (receptor activator of nuclear factor-κB ligand) a protein essential for osteoclast formation was dose-dependently decreased in the femur of BB animals. In addition, expression of PPARγ (peroxisome proliferator-activated receptor γ) which regulates bone marrow adipogenesis was suppressed in BB diet rats compared to non-BB diet controls. Finally, a set of in vitro cell cultures revealed that the inhibitory effect of BB diet rat serum on RANKL expression was more profound in mesenchymal stromal cells compared to its effect on mature osteoblasts, pre-adipocytes and osteocytes. These results suggest that inhibition of bone resorption may contribute to increased bone mass during early development after BB consumption.
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30
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Iwaniec UT, Turner RT. Failure to generate bone marrow adipocytes does not protect mice from ovariectomy-induced osteopenia. Bone 2013; 53:145-53. [PMID: 23246792 PMCID: PMC3564669 DOI: 10.1016/j.bone.2012.11.034] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 11/18/2012] [Accepted: 11/20/2012] [Indexed: 01/04/2023]
Abstract
A reciprocal association between bone marrow fat and bone mass has been reported in ovariectomized rodents, suggesting that bone marrow adipogenesis has a negative effect on bone growth and turnover balance. Mice with loss of function mutations in kit receptor (kit(W/W-v)) have no bone marrow adipocytes in tibia or lumbar vertebra. We therefore tested the hypothesis that marrow fat contributes to the development of osteopenia by comparing the skeletal response to ovariectomy (ovx) in growing wild type (WT) and bone marrow adipocyte-deficient kit(W/W-v) mice. Mice were ovx at 4 weeks of age and sacrificed 4 or 10 weeks post-surgery. Body composition was measured at necropsy by dual-energy X-ray absorptiometry. Cortical (tibia) and cancellous (tibia and lumbar vertebra) bone architecture were evaluated by microcomputed tomography. Bone marrow adipocyte size and density, osteoblast- and osteoclast-lined bone perimeters, and bone formation were determined by histomorphometry. Ovx resulted in an increase in total body fat mass at 10 weeks post-ovx in both genotypes, but the response was attenuated in the in kit(W/W-v) mice. Adipocytes were present in bone marrow of tibia and lumbar vertebra in WT mice and bone marrow adiposity increased following ovx. In contrast, marrow adipocytes were not detected in either intact or ovx kit(W/W-v) mice. However, ovx in WT and kit(W/W-v) mice resulted in statistically indistinguishable changes in cortical and cancellous bone mass, cortical and cancellous bone formation rate, and cancellous osteoblast and osteoclast-lined bone perimeters. In conclusion, our findings do not support a causal role for increased bone marrow fat as a mediator of ovx-induced osteopenia in mice.
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Affiliation(s)
- Urszula T Iwaniec
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA.
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31
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Yang JY, Cho SW, An JH, Jung JY, Kim SW, Kim SY, Kim JE, Shin CS. Osteoblast-targeted overexpression of TAZ increases bone mass in vivo. PLoS One 2013; 8:e56585. [PMID: 23441207 PMCID: PMC3575506 DOI: 10.1371/journal.pone.0056585] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Accepted: 01/11/2013] [Indexed: 01/28/2023] Open
Abstract
Osteoblasts are derived from mesenchymal progenitors. Differentiation to osteoblasts and adipocytes is reciprocally regulated. Transcriptional coactivator with a PDZ-binding motif (TAZ) is a transcriptional coactivator that induces differentiation of mesenchymal cells into osteoblasts while blocking differentiation into adipocytes. To investigate the role of TAZ on bone metabolism in vivo, we generated transgenic mice that overexpress TAZ under the control of the procollagen type 1 promoter (Col1-TAZ). Whole body bone mineral density (BMD) of 6- to 19-week-old Col-TAZ mice was 4% to 7% higher than that of their wild-type (WT) littermates, whereas no difference was noticed in Col.1-TAZ female mice. Microcomputed tomography analyses of proximal tibiae at 16 weeks of age demonstrated a significant increase in trabecular bone volume (26.7%) and trabecular number (26.6%) with a reciprocal decrease in trabecular spacing (14.2%) in Col1-TAZ mice compared with their WT littermates. In addition, dynamic histomorphometric analysis of the lumbar spine revealed increased mineral apposition rate (42.8%) and the serum P1NP level was also significantly increased (53%) in Col.1-TAZ mice. When primary calvaria cells were cultured in osteogenic medium, alkaline phosphatase (ALP) activity was significantly increased and adipogenesis was significantly suppressed in Col1-TAZ mice compared with their WT littermates. Quantitative real-time polymerase chain reaction analyses showed that expression of collagen type 1, bone sialoprotein, osteocalcin, ALP, osterix, and Runx2 was significantly increased in calvaria cells from Col1-TAZ mice compared to their WT littermates. In vitro, TAZ enhanced Runx2-mediated transcriptional activity while suppressing the peroxisome proliferator-activated receptor gamma signaling pathway. TAZ also enhanced transcriptional activity from 3TP-Lux, which reflects transforming growth factor-beta (TGF-β)-mediated signaling. In addition, TAZ enhanced TGF-β-dependent nuclear translocation of Smad2/3 and Smad4. Taken together, these results suggest that TAZ positively regulates bone formation in vivo, which seems to be mediated by enhancing both Runx2 and TGF-β signaling.
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Affiliation(s)
- Jae-Yeon Yang
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Sun Wook Cho
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Jee Hyun An
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Ju Yeon Jung
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Sang Wan Kim
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Seong Yeon Kim
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Jung Eun Kim
- Department of Molecular Medicine, Kyungpook National University School of Medicine, Daegu, Korea
| | - Chan Soo Shin
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
- * E-mail:
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32
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Yan W, Li X. Impact of diabetes and its treatments on skeletal diseases. Front Med 2013; 7:81-90. [DOI: 10.1007/s11684-013-0243-9] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2012] [Accepted: 12/04/2012] [Indexed: 01/22/2023]
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33
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An JH, Park H, Song JA, Ki KH, Yang JY, Choi HJ, Cho SW, Kim SW, Kim SY, Yoo JJ, Baek WY, Kim JE, Choi SJ, Oh W, Shin CS. Transplantation of human umbilical cord blood-derived mesenchymal stem cells or their conditioned medium prevents bone loss in ovariectomized nude mice. Tissue Eng Part A 2013; 19:685-96. [PMID: 23215868 DOI: 10.1089/ten.tea.2012.0047] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Umbilical cord blood (UCB) has recently been recognized as a new source of mesenchymal stem cells (MSCs) for use in stem cell therapy. We studied the effects of systemic injection of human UCB-MSCs and their conditioned medium (CM) on ovariectomy (OVX)-induced bone loss in nude mice. Ten-week-old female nude mice were divided into six groups: Sham-operated mice treated with vehicle (Sham-Vehicle), OVX mice subjected to UCB-MSCs (OVX-MSC), or human dermal fibroblast (OVX-DFB) transplantation, OVX mice treated with UCB-MSC CM (OVX-CM), zoledronate (OVX-Zol), or vehicle (OVX-Vehicle). Although the OVX-Vehicle group exhibited significantly less bone mineral density (BMD) gain compared with the Sham-Vehicle group, transplantation of hUCB-MSCs (OVX-MSC group) has effectively prevented OVX-induced bone mass attenuation. Notably, the OVX-CM group also showed BMD preservation comparable to the OVX-MSC group. In addition, microcomputed tomography analysis demonstrated improved trabecular parameters in both the OVX-MSC and OVX-CM groups compared to the OVX-Vehicle or OVX-DFB group. Histomorphometric analysis showed increased bone formation parameters, accompanied by increased serum procollagen type-I N-telopeptide levels in OVX-MSC and OVX-CM mice. However, cell-trafficking analysis failed to demonstrate engraftment of MSCs in bone tissue 48 h after cell infusion. In vitro, hUCB-MSC CM increased alkaline phosphatase (ALP) activity in human bone marrow-derived MSCs and mRNA expression of collagen type 1, Runx2, osterix, and ALP in C3H10T1/2 cells. Furthermore, hUCB-MSC CM significantly increased survival of osteocyte-like MLO-Y4 cells, while it inhibited osteoclastic differentiation. To summarize, transplantation of hUCB-MSCs could effectively prevent OVX-mediated bone loss in nude mice, which appears to be mediated by a paracrine mechanism rather than direct engraftment of the MSCs.
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Affiliation(s)
- Jee Hyun An
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
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34
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Baek K, Baek JH. The transcription factors myeloid elf-1-like factor (MEF) and distal-less homeobox 5 (Dlx5) inversely regulate the differentiation of osteoblasts and adipocytes in bone marrow. Adipocyte 2013; 2:50-54. [PMID: 23700553 PMCID: PMC3661131 DOI: 10.4161/adip.22019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
In bone marrow, the differentiation of osteoblasts and adipocytes is reciprocally regulated. This inverse regulation occurs mainly through complex signaling crosstalk between transcriptional factors such as peroxisome proliferator-activated receptor-γ (PPARγ) and runt-related transcription factor 2 (Runx2). This commentary addresses the role of myeloid elf-1 like factor (MEF) and distal-less homeobox 5 (Dlx5) in the lineage commitment of bone marrow mesenchymal stem cells into adipocytes and osteoblasts, respectively. MEF suppresses osteoblastogenesis by preventing Runx2 from binding to the promoters of target genes and enhancing adipogenesis via transactivation of PPARγ expression. Conversely, Dlx5 enhances osteoblastogenesis through upregulation of the expression of Runx2 and osteoblast marker genes while suppressing adipogenesis through the downregulation of PPARγ expression by sequestering the cAMP response element binding protein and CCAAT/enhancer-binding protein α. Studies designed to examine the effects of physiological and pathologic signals on the expression of MEF and Dlx5 will provide further insight to the function of these transcription factors in vivo.
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35
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Baek K, Cho JY, Hwang HR, Kwon A, Lee HL, Park HJ, Qadir AS, Ryoo HM, Woo KM, Baek JH. Myeloid Elf-1-like factor stimulates adipogenic differentiation through the induction of peroxisome proliferator-activated receptor γ expression in bone marrow. J Cell Physiol 2012; 227:3603-12. [PMID: 22307523 DOI: 10.1002/jcp.24064] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Myeloid Elf-1 like factor (MEF) is one of the Ets transcription factors known to regulate cell proliferation and differentiation. A previous report has shown that osteoblast-specific MEF transgenic mice (Col1a1-MEF TG mice) have low bone mass but high bone marrow adiposity. In the present study, we explored a previously unappreciated mechanism whereby MEF promotes adipogenesis in bone marrow. An adipogenic colony-forming unit assay showed that bone marrow cells derived from Col1a1-MEF TG mice had a higher adipogenic differentiation potential compared to those from wild-type. The levels of adipogenic marker genes expression in 3T3L1 cells were higher when co-cultured with Col1a1-MEF TG bone marrow cells than with wild-type cells. MC3T3-E1 preosteoblasts transfected with MEF secreted higher levels of 15-deoxy-delta (12, 14)-prostaglandin J(2), a potent endogenous ligand of peroxisome proliferator-activated receptor γ (PPARγ), under adipogenic conditions. MEF overexpression increased the adipogenic marker genes expression including PPARγ and lipid droplet accumulation in MC3T3-E1 preosteoblasts and 3T3L1 preadipocytes. Endogenous MEF expression levels increased as adipocyte differentiation proceeded. Knockdown of MEF by siRNA suppressed expression levels of adipogenic marker genes including PPARγ. MEF directly bound to the MEF binding element on the mouse PPARγ promoter, transactivating promoter activity. Immunohistochemical staining of tibia sections demonstrated that bone lining cells and bone marrow cells express higher levels of PPARγ protein in Col1a1-MEF TG mice than in wild-type mice. These results suggest that MEF transactivates PPARγ expression, which, in turn, enhances adipogenic differentiation. Furthermore, MEF overexpressing osteoblasts secrete higher levels of adipogenic factors, creating a marrow microenvironment that favors adipogenesis.
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Affiliation(s)
- Kyunghwa Baek
- Department of Molecular Genetics, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Korea
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Chen B, Li XD, Liu DX, Wang H, Xie P, Liu ZY, Hou GQ, Chang B, Du SX. Canonical Wnt signaling is required for Panax notoginseng saponin-mediated attenuation of the RANKL/OPG ratio in bone marrow stromal cells during osteogenic differentiation. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2012; 19:1029-34. [PMID: 22818895 DOI: 10.1016/j.phymed.2012.06.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Revised: 04/23/2012] [Accepted: 06/14/2012] [Indexed: 02/05/2023]
Abstract
Panax notoginseng saponins (PNS) are known to regulate the osteogenic differentiation of bone marrow stromal cells (BMSCs). In the present study, we investigated whether PNS could promote the osteogenic differentiation of BMSCs through modulating the Wnt/β-catenin signaling pathways, which are implicated in BMSCs osteogenesis. We found that PNS enhanced the mRNA expression of OPG, β-catenin, and cyclin D1 while decreased the mRNA expression of RANKL and PPARγ2. The actions of PNS on BMSCs were reversed (or partially) by DKK-1, a classical inhibitor of Wnt/β-catenin signaling. These results suggest that PNS stimulating bone formation by promoting the proliferation and osteogenic differentiation of BMSCs, and could also protect the skeletal system by decreasing bone resorption through reduction of RANKL/OPG expression via Wnt/β-catenin signaling pathways.
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Affiliation(s)
- Bin Chen
- Department of Orthopaedics, First Affiliated Hospital, Shantou University Medical College, 57 Chang Ping Road, Shantou, Guangdong 515041, China
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Saidak Z, Haÿ E, Marty C, Barbara A, Marie PJ. Strontium ranelate rebalances bone marrow adipogenesis and osteoblastogenesis in senescent osteopenic mice through NFATc/Maf and Wnt signaling. Aging Cell 2012; 11:467-74. [PMID: 22321691 DOI: 10.1111/j.1474-9726.2012.00804.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
With aging, bone marrow mesenchymal stromal cell (MSC) osteoblast differentiation decreases whereas MSC differentiation into adipocytes increases, resulting in increased adipogenesis and bone loss. Here, we investigated whether activation of cell signaling by strontium ranelate (SrRan) can reverse the excessive adipogenic differentiation associated with aging. In murine MSC cultures, SrRan increased Runx2 expression and matrix mineralization and decreased PPARγ2 expression and adipogenesis. This effect was associated with increased expression of the Wnt noncanonical representative Wnt5a and adipogenic modulator Maf and was abrogated by Wnt- and nuclear factor of activated T-cells (NFAT)c antagonists, implying a role for Wnt and NFATc/Maf signaling in the switch in osteoblastogenesis to adipogenesis induced by SrRan. To confirm this finding, we investigated the effect of SrRan in SAMP6 senescent mice, which exhibit decreased osteoblastogenesis, increased adipogenesis, and osteopenia. SrRan administration at a clinically relevant dose level increased bone mineral density, bone volume, trabecular thickness and number, as shown by densitometric, microscanning, and histomorphometric analyses in long bones and vertebrae. This attenuation of bone loss was related to increased osteoblast surface and bone formation rate and decreased bone marrow adipocyte volume and size. The restoration of osteoblast and adipocyte balance induced by SrRan was linked to increased Wnt5a and Maf expression in the bone marrow. The results indicate that SrRan acts on lineage allocation of MSCs by antagonizing the age-related switch in osteoblast to adipocyte differentiation via mechanisms involving NFATc/Maf and Wnt signaling, resulting in increased bone formation and attenuation of bone loss in senescent osteopenic mice.
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Abstract
There is increasing evidence that osteoporosis, similarly to obesity and diabetes, could be another disorder of energy metabolism. AMP-activated protein kinase (AMPK) has emerged over the last decade as a key sensing mechanism in the regulation of cellular energy homeostasis and is an essential mediator of the central and peripheral effects of many hormones on the metabolism of appetite, fat and glucose. Novel work demonstrates that the AMPK signaling pathway also plays a role in bone physiology. Activation of AMPK promotes bone formation in vitro and the deletion of α or β subunit of AMPK decreases bone mass in mice. Furthermore, AMPK activity in bone cells is regulated by the same hormones that regulate food intake and energy expenditure through AMPK activation in the brain and peripheral tissues. AMPK is also activated by antidiabetic drugs such as metformin and thiazolidinediones (TZDs), which also impact on skeletal metabolism. Interestingly, TZDs have detrimental skeletal side effects, causing bone loss and increasing the risk of fractures, although the role of AMPK mediation is still unclear. These data are presented in this review that also discusses the potential roles of AMPK in bone as well as the possibility for AMPK to be a future therapeutic target for intervention in osteoporosis.
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Affiliation(s)
- J Jeyabalan
- Royal Veterinary College, Royal College Street, London NW1 0TU, UK
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Thiazolidinediones on PPARγ: The Roles in Bone Remodeling. PPAR Res 2011; 2011:867180. [PMID: 22135675 PMCID: PMC3205770 DOI: 10.1155/2011/867180] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2011] [Revised: 10/04/2011] [Accepted: 10/05/2011] [Indexed: 01/02/2023] Open
Abstract
Thiazolidinediones (TZDs) are synthetic PPARγ (peroxisome proliferator-activated receptor gamma) agonists and a class of drugs for diabetes mellitus type 2 that can decrease blood sugar efficiently by enhancing insulin sensitivity. However, increased bone fracture risk in diabetic individuals treated with TZDs is one of the reported side effects. Recent studies show that TZDs such as rosiglitazone simultaneously inhibit osteoblast differentiation and activate osteoclast differentiation, leading to bone loss due to decreased bone formation and increased bone resorption. Furthermore, TZDs may activate PPARγ in tissues other than bone, such as the hypothalamus-pituitary-gonad (HPG) axis to indirectly regulate bone mass. This paper will focus on current new developments that implicate potential mechanisms for how PPARγ modulates skeletal homeostasis and how TZDs exert bone-loss side effects.
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