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Elzamzami FD, Samal A, Arun AS, Dharmaraj T, Prasad NR, Rendon-Jonguitud A, DeVine L, Walston JD, Cole RN, Wilson KL. Native lamin A/C proteomes and novel partners from heart and skeletal muscle in a mouse chronic inflammation model of human frailty. Front Cell Dev Biol 2023; 11:1240285. [PMID: 37936983 PMCID: PMC10626543 DOI: 10.3389/fcell.2023.1240285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 10/05/2023] [Indexed: 11/09/2023] Open
Abstract
Clinical frailty affects ∼10% of people over age 65 and is studied in a chronically inflamed (Interleukin-10 knockout; "IL10-KO") mouse model. Frailty phenotypes overlap the spectrum of diseases ("laminopathies") caused by mutations in LMNA. LMNA encodes nuclear intermediate filament proteins lamin A and lamin C ("lamin A/C"), important for tissue-specific signaling, metabolism and chromatin regulation. We hypothesized that wildtype lamin A/C associations with tissue-specific partners are perturbed by chronic inflammation, potentially contributing to dysfunction in frailty. To test this idea we immunoprecipitated native lamin A/C and associated proteins from skeletal muscle, hearts and brains of old (21-22 months) IL10-KO versus control C57Bl/6 female mice, and labeled with Tandem Mass Tags for identification and quantitation by mass spectrometry. We identified 502 candidate lamin-binding proteins from skeletal muscle, and 340 from heart, including 62 proteins identified in both tissues. Candidates included frailty phenotype-relevant proteins Perm1 and Fam210a, and nuclear membrane protein Tmem38a, required for muscle-specific genome organization. These and most other candidates were unaffected by IL10-KO, but still important as potential lamin A/C-binding proteins in native heart or muscle. A subset of candidates (21 in skeletal muscle, 30 in heart) showed significantly different lamin A/C-association in an IL10-KO tissue (p < 0.05), including AldoA and Gins3 affected in heart, and Lmcd1 and Fabp4 affected in skeletal muscle. To screen for binding, eleven candidates plus prelamin A and emerin controls were arrayed as synthetic 20-mer peptides (7-residue stagger) and incubated with recombinant purified lamin A "tail" residues 385-646 under relatively stringent conditions. We detected strong lamin A binding to peptides solvent exposed in Lmcd1, AldoA, Perm1, and Tmem38a, and plausible binding to Csrp3 (muscle LIM protein). These results validated both proteomes as sources for native lamin A/C-binding proteins in heart and muscle, identified four candidate genes for Emery-Dreifuss muscular dystrophy (CSRP3, LMCD1, ALDOA, and PERM1), support a lamin A-interactive molecular role for Tmem38A, and supported the hypothesis that lamin A/C interactions with at least two partners (AldoA in heart, transcription factor Lmcd1 in muscle) are altered in the IL10-KO model of frailty.
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Affiliation(s)
- Fatima D. Elzamzami
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Arushi Samal
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Adith S. Arun
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Tejas Dharmaraj
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Neeti R. Prasad
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Alex Rendon-Jonguitud
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Lauren DeVine
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Jeremy D. Walston
- Division of Geriatric Medicine and Gerontology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Robert N. Cole
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Katherine L. Wilson
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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2
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Birks S, Howard S, O’Rourke C, Thompson WR, Lau A, Uzer G. Osterix-driven LINC complex disruption in vivo diminishes bone microarchitecture in 8-week male mice but not after 6-week voluntary wheel running. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.24.554623. [PMID: 37662368 PMCID: PMC10473717 DOI: 10.1101/2023.08.24.554623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
The Linker of Nucleoskeleton and Cytoskeleton (LINC) complex is a crucial connective component between the nuclear envelope and the cytoskeleton involving various cellular processes including nuclear positioning, nuclear architecture, and mechanotransduction. How LINC complexes regulate bone formation in vivo, however, is not well understood. To start bridging this gap, here we created a LINC disruption murine model using transgenic mice expressing Cre recombinase enzyme under the control of the Osterix (Osx-Cre) which is primarily active in pre-osteoblasts and floxed Tg(CAG-LacZ/EGFP-KASH2) mice. Tg(CAG-LacZ/EGFP-KASH2) mice contain a lox-STOP-lox flanked LacZ gene which is deleted upon cre recombination allowing for the overexpression of an EGFP-KASH2 fusion protein. This overexpressed protein disrupts endogenous Nesprin-Sun binding leading to disruption of LINC complexes. Thus, crossing these two lines results in a Osx-driven LINC disruption (ODLD) specific to pre-osteoblasts. In this study, we investigated how this LINC disruption affects exercise induced bone accrual. ODLD cells had decreased osteogenic and adipogenic potential in vitro compared to non-disrupted controls and sedentary ODLD mice showed decreased bone quality at 8-weeks. Upon access to a voluntary running wheel ODLD animals showed increased running time and distance; however, our 6-week exercise intervention did not significantly affect bone microarchitecture and bone mechanical properties.
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Affiliation(s)
- Scott Birks
- Boise State University, Micron School of Materials Science and Engineering
| | - Sean Howard
- Boise State University, Mechanical and Biomedical Engineering
| | | | | | - Anthony Lau
- The College of New Jersey, Biomedical Engineering
| | - Gunes Uzer
- Boise State University, Mechanical and Biomedical Engineering
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3
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Kurgan N, Stoikos J, Baranowski BJ, Yumol J, Dhaliwal R, Sweezey-Munroe JB, Fajardo VA, Gittings W, Macpherson REK, Klentrou P. Sclerostin Influences Exercise-Induced Adaptations in Body Composition and White Adipose Tissue Morphology in Male Mice. J Bone Miner Res 2023; 38:541-555. [PMID: 36606556 DOI: 10.1002/jbmr.4768] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 12/12/2022] [Accepted: 01/03/2023] [Indexed: 01/07/2023]
Abstract
Sclerostin is an inhibitor of the osteogenic Wnt/β-catenin signaling pathway that also has an endocrine role in regulating adipocyte differentiation and metabolism. Additionally, subcutaneous white adipose tissue (scWAT) sclerostin content decreases following exercise training (EXT). Therefore, we hypothesized that EXT-induced reductions in adipose tissue sclerostin may play a role in regulating adaptations in body composition and whole-body metabolism. To test this hypothesis, 10-week-old male C57BL/6J mice were either sedentary (SED) or performing 1 hour of treadmill running at ~65% to 70% maximum oxygen consumption (VO2max ) 5 day/week (EXT) for 4 weeks and had subcutaneous injections of either saline (C) or recombinant sclerostin (S) (0.1 mg/kg body mass) 5 day/week; thus, making four groups (SED-C, EXT-C, SED-S, and EXT-S; n = 12/group). No differences in body mass were observed between experimental groups, whereas food intake was higher in EXT (p = 0.03) and S (p = 0.08) groups. There was a higher resting energy expenditure in all groups compared to SED-C. EXT-C had increased lean mass and decreased fat mass percentage compared to SED-C and SED-S. No differences in body composition were observed in either the SED-S or EXT-S groups. Lower scWAT (inguinal), epididymal white adipose tissue (eWAT) (visceral epididymal) mass, and scWAT adipocyte cell size and increased percentage of multilocular cells in scWAT were observed in the EXT-C group compared to SED-C, whereas lower eWAT was only observed in the EXT-S group. EXT mice had increased scWAT low-density lipoprotein receptor-related protein 4 (Lrp4) and mitochondrial content and sclerostin treatment only inhibited increased Lrp4 content with EXT. Together, these results provide evidence that reductions in resting sclerostin with exercise training may influence associated alterations in energy metabolism and body composition, particularly in scWAT. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Nigel Kurgan
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada.,Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Joshua Stoikos
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada.,Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Bradley J Baranowski
- Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada.,Centre for Neuroscience, Brock University, St. Catharines, ON, Canada
| | - Jenalyn Yumol
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada.,Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Roopan Dhaliwal
- Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada.,Centre for Neuroscience, Brock University, St. Catharines, ON, Canada
| | - Jake B Sweezey-Munroe
- Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada.,Centre for Neuroscience, Brock University, St. Catharines, ON, Canada
| | - Val A Fajardo
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada.,Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - William Gittings
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada.,Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Rebecca E K Macpherson
- Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada.,Centre for Neuroscience, Brock University, St. Catharines, ON, Canada
| | - Panagiota Klentrou
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada.,Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
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4
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Rubin J, Styner M. The skeleton in a physical world. Exp Biol Med (Maywood) 2022; 247:2213-2222. [PMID: 35983849 PMCID: PMC9899984 DOI: 10.1177/15353702221113861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
All organisms exist within a physical space and respond to physical forces as part of daily life. In higher organisms, the skeleton is critical for locomotion in the physical environment, providing a carapace upon which the animal can move to accomplish functions necessary for living. As such, the skeleton has responded evolutionarily, and does in real-time, to physical stresses placed on it to ensure that its structure supports its function in the sea, in the air, and on dry land. In this article, we consider how those cells responsible for remodeling skeletal structure respond to mechanical force including load magnitude, frequency, and cyclicity, and how force rearranges cellular structure in turn. The effects of these forces to balance the mesenchymal stem cell supply of bone-forming osteoblasts and energy storing adipocytes are addressed. That this phenotypic switching is achieved at the level of both gene transactivation and alteration of structural epigenetic controls of gene expression is considered. Finally, as clinicians, we consider this information as it applies to a prescriptive for intelligent exercise.
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Bermeo S, Al Saedi A, Vidal C, Khalil M, Pang M, Troen BR, Myers D, Duque G. Treatment with an inhibitor of fatty acid synthase attenuates bone loss in ovariectomized mice. Bone 2019; 122:114-122. [PMID: 30779961 DOI: 10.1016/j.bone.2019.02.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 02/03/2019] [Accepted: 02/15/2019] [Indexed: 02/02/2023]
Abstract
Bone and fat cells have an antagonistic relationship. Adipocytes exert a toxic effect on bone cells in vitro through the secretion of fatty acids, which are synthesized by fatty acid synthase (FAS). Inhibition of FAS in vitro rescues osteoblasts from fat-induced toxicity and cell death. In this study, we hypothesized that FAS inhibition would mitigate the loss of bone mass in ovariectomized (OVX) mice. We treated OVX C57BL/6 mice with cerulenin (a known inhibitor of FAS) for 6 weeks and compared their bone phenotype with vehicle-treated controls. Cerulenin-treated mice exhibited a significant decrease in body weight, triglycerides, leptin, and marrow and subcutaneous fat without changes in serum glucose or calciotropic hormones. These effects were associated with attenuation of bone loss and normalization of the bone phenotype in the cerulenin-treated OVX group compared to the vehicle-treated OVX group. Our results demonstrate that inhibition of FAS enhances bone formation, induces uncoupling between osteoblasts and osteoclasts, and favors mineralization, thus providing evidence that inhibition of FAS could constitute a new anabolic therapy for osteoporosis.
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Affiliation(s)
- Sandra Bermeo
- Sydney Medical School Nepean, The University of Sydney, Penrith, NSW 2750, Australia; Facultad de Ciencias Básicas y Biomédicas, Universidad Simón Bolívar, Barranquilla, Colombia
| | - Ahmed Al Saedi
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St Albans, VIC 3021, Australia; Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St Albans, VIC 3021, Australia
| | - Christopher Vidal
- Sydney Medical School Nepean, The University of Sydney, Penrith, NSW 2750, Australia
| | - Mamdouh Khalil
- ANZAC Research Institute, Sydney Medical School Concord, The University of Sydney, Concord, NSW 2137, Australia
| | - Manhui Pang
- Division of Geriatrics and Palliative Medicine, Jacobs School of Medicine and Biomedical Sciences and Research Service, Veterans Affairs Western New York Healthcare System, University at Buffalo, Buffalo, NY, USA
| | - Bruce R Troen
- Division of Geriatrics and Palliative Medicine, Jacobs School of Medicine and Biomedical Sciences and Research Service, Veterans Affairs Western New York Healthcare System, University at Buffalo, Buffalo, NY, USA
| | - Damian Myers
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St Albans, VIC 3021, Australia; Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St Albans, VIC 3021, Australia
| | - Gustavo Duque
- Sydney Medical School Nepean, The University of Sydney, Penrith, NSW 2750, Australia; Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St Albans, VIC 3021, Australia; Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St Albans, VIC 3021, Australia.
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6
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Al Saedi A, Gunawardene P, Bermeo S, Vogrin S, Boersma D, Phu S, Singh L, Suriyaarachchi P, Duque G. Lamin A expression in circulating osteoprogenitors as a potential biomarker for frailty: The Nepean Osteoporosis and Frailty (NOF) Study. Exp Gerontol 2017; 102:69-75. [PMID: 29203402 DOI: 10.1016/j.exger.2017.11.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 11/15/2017] [Accepted: 11/22/2017] [Indexed: 01/10/2023]
Abstract
Lamin A is a protein of the nuclear lamina. Low levels of lamin A expression are associated with osteosarcopenia in mice. In this study, we hypothesized that low lamin A expression is also associated with frailty in humans. We aimed to develop a non-invasive method to quantify lamin A expression in epithelial and circulating osteoprogenitor (COP) cells, and to determine the relationship between lamin A expression and frailty in older individuals. COP cells and buccal swabs were obtained from 66 subjects (median age 74; 60% female; 26 non-frail, 23 pre-frail, and 17 frail) participating at the Nepean Osteoporosis and Frailty (NOF) Study. We quantified physical performance and disability, and stratified frailty in this population. Lamin A expression in epithelial and COP cells was quantified by flow cytometry. Linear regression models estimated the relationship between lamin A expression in buccal and COP cells, and prevalent disability and frailty. Lamin A expression in buccal cells showed no association with either disability or frailty. Low lamin A expression values in COP cells were associated with frailty. Frail individuals showed 60% lower levels of lamin A compared to non-frail (95% CI -36 to -74%, p<0.001) and 62% lower levels compared to pre-frail (95%CI -40 to -76%, p<0.001). In summary, we have identified lamin A expression in COP cells as a strong indicator of frailty. Further work is needed to understand lamin A expression as a risk stratifier, biomarker, or therapeutic target in frail older persons.
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Affiliation(s)
- Ahmed Al Saedi
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, Melbourne, VIC, Australia; Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, Melbourne, VIC, Australia.
| | - Piumali Gunawardene
- Sydney Medical School Nepean, The University of Sydney, Penrith, NSW, Australia; Department of Geriatric Medicine, Nepean Hospital, Penrith, NSW, Australia
| | - Sandra Bermeo
- Sydney Medical School Nepean, The University of Sydney, Penrith, NSW, Australia.
| | - Sara Vogrin
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, Melbourne, VIC, Australia; Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, Melbourne, VIC, Australia.
| | - Derek Boersma
- Department of Geriatric Medicine, Nepean Hospital, Penrith, NSW, Australia.
| | - Steven Phu
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, Melbourne, VIC, Australia; Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, Melbourne, VIC, Australia.
| | - Lakshman Singh
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, Melbourne, VIC, Australia; Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, Melbourne, VIC, Australia.
| | | | - Gustavo Duque
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, Melbourne, VIC, Australia; Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, Melbourne, VIC, Australia; Sydney Medical School Nepean, The University of Sydney, Penrith, NSW, Australia.
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7
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Qi Z, Liu W, Lu J. The mechanisms underlying the beneficial effects of exercise on bone remodeling: Roles of bone-derived cytokines and microRNAs. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 122:131-139. [PMID: 27179638 DOI: 10.1016/j.pbiomolbio.2016.05.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 05/02/2016] [Accepted: 05/07/2016] [Indexed: 12/31/2022]
Abstract
Bone remodeling is highly dynamic and complex in response to mechanical loading, such as exercise. In this review, we concluded that a number of individual factors are disturbing the clinical effects of exercise on bone remodeling. We updated the progress made on the differentiation of osteoblasts and osteoclasts in response to mechanical loading, hoping to provide a theoretical basis to improve bone metabolism with exercise. Increasing evidences indicate that bone is not only a structural scaffold but also an endocrine organ, which secretes osteocalcin and FGF23. Both of them have been known as a circulating hormone to promote insulin sensitivity and reduce body fat mass. The effects of exercise on these bone-derived cytokines provide a better understanding of how exercise-induced "osteokine" affects the whole-body homeostasis. Additionally, we discussed recent studies highlighting the post-transcriptional regulation of microRNAs in bone remodeling. We focus on the involvement of the microRNAs in osteoblastogenesis and osteoclastogenesis, and suggest that microRNAs may be critical for exercise-induced bone remodeling.
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Affiliation(s)
- Zhengtang Qi
- The Key Laboratory of Adolescent Health Assessment and Exercise Intervention (East China Normal University), Ministry of Education, Shanghai 200241, China; School of Physical Education and Health, East China Normal University, Shanghai 200241, China
| | - Weina Liu
- The Key Laboratory of Adolescent Health Assessment and Exercise Intervention (East China Normal University), Ministry of Education, Shanghai 200241, China; School of Physical Education and Health, East China Normal University, Shanghai 200241, China.
| | - Jianqiang Lu
- School of Kinesiology, Shanghai University of Sport, Shanghai 200438, China.
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Uzer G, Fuchs RK, Rubin J, Thompson WR. Concise Review: Plasma and Nuclear Membranes Convey Mechanical Information to Regulate Mesenchymal Stem Cell Lineage. Stem Cells 2016; 34:1455-63. [PMID: 26891206 DOI: 10.1002/stem.2342] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 12/14/2015] [Accepted: 12/29/2015] [Indexed: 12/21/2022]
Abstract
Numerous factors including chemical, hormonal, spatial, and physical cues determine stem cell fate. While the regulation of stem cell differentiation by soluble factors is well-characterized, the role of mechanical force in the determination of lineage fate is just beginning to be understood. Investigation of the role of force on cell function has largely focused on "outside-in" signaling, initiated at the plasma membrane. When interfaced with the extracellular matrix, the cell uses integral membrane proteins, such as those found in focal adhesion complexes to translate force into biochemical signals. Akin to these outside-in connections, the internal cytoskeleton is physically linked to the nucleus, via proteins that span the nuclear membrane. Although structurally and biochemically distinct, these two forms of mechanical coupling influence stem cell lineage fate and, when disrupted, often lead to disease. Here we provide an overview of how mechanical coupling occurs at the plasma and nuclear membranes. We also discuss the role of force on stem cell differentiation, with focus on the biochemical signals generated at the cell membrane and the nucleus, and how those signals influence various diseases. While the interaction of stem cells with their physical environment and how they respond to force is complex, an understanding of the mechanical regulation of these cells is critical in the design of novel therapeutics to combat diseases associated with aging, cancer, and osteoporosis. Stem Cells 2016;34:1455-1463.
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Affiliation(s)
- Gunes Uzer
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Robyn K Fuchs
- School of Health and Rehabilitation Sciences, Department of Physical Therapy, Indiana University, Indianapolis, Indiana, USA
| | - Janet Rubin
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - William R Thompson
- School of Health and Rehabilitation Sciences, Department of Physical Therapy, Indiana University, Indianapolis, Indiana, USA
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9
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Abstract
Fat and bone have a complicated relationship. Although obesity has been associated with low fracture risk, there is increasing evidence that some of the factors that are released by peripheral fat into the circulation may also have a deleterious effect on bone mass, thus, predisposing to fractures. More importantly, the local interaction between fat and bone within the bone marrow seems to play a significant role in the pathogenesis of age-related bone loss and osteoporosis. This "local interaction" occurs inside the bone marrow and is associated with the autocrine and paracrine release of fatty acids and adipokines, which affect the cells in their vicinity including the osteoblasts, reducing their function and survival. In this review, we explore the particularities of the fat and bone cell interactions within the bone marrow, their significance in the pathogenesis of osteoporosis, and the potential therapeutic applications that regulating marrow fat may have in the near future as a novel pharmacologic treatment for osteoporosis.
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Affiliation(s)
- Sandra Bermeo
- Ageing Bone Research Program, Sydney Medical School Nepean, The University of Sydney, Level 5, South Block, Nepean Hospital, Penrith, NSW., Australia, 2750
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10
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Sehgal P, Chaturvedi P, Kumaran RI, Kumar S, Parnaik VK. Lamin A/C haploinsufficiency modulates the differentiation potential of mouse embryonic stem cells. PLoS One 2013; 8:e57891. [PMID: 23451281 PMCID: PMC3581495 DOI: 10.1371/journal.pone.0057891] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 01/28/2013] [Indexed: 02/06/2023] Open
Abstract
Background Lamins are structural proteins that are the major determinants of nuclear architecture and play important roles in various nuclear functions including gene regulation and cell differentiation. Mutations in the human lamin A gene cause a spectrum of genetic diseases that affect specific tissues. Most available mouse models for laminopathies recapitulate disease symptoms for muscle diseases and progerias. However, loss of human lamin A/C also has highly deleterious effects on fetal development. Hence it is important to understand the impact of lamin A/C expression levels on embryonic differentiation pathways. Methodology and Principal Findings We have investigated the differentiation potential of mouse embryonic stem cells containing reduced levels of lamin A/C by detailed lineage analysis of embryoid bodies derived from these cells by in vitro culture. We initially carried out a targeted disruption of one allele of the mouse lamin A/C gene (Lmna). Undifferentiated wild-type and Lmna+/− embryonic stem cells showed similar expression of pluripotency markers and cell cycle profiles. Upon spontaneous differentiation into embryoid bodies, markers for visceral endoderm such as α-fetoprotein were highly upregulated in haploinsufficient cells. However, neuronal markers such as β-III tubulin and nestin were downregulated. Furthermore, we observed a reduction in the commitment of Lmna+/− cells into the myogenic lineage, but no discernible effects on cardiac, adipocyte or osteocyte lineages. In the next series of experiments, we derived embryonic stem cell clones expressing lamin A/C short hairpin RNA and examined their differentiation potential. These cells expressed pluripotency markers and, upon differentiation, the expression of lineage-specific markers was altered as observed with Lmna+/− embryonic stem cells. Conclusions We have observed significant effects on embryonic stem cell differentiation to visceral endoderm, neuronal and myogenic lineages upon depletion of lamin A/C. Hence our results implicate lamin A/C level as an important determinant of lineage-specific differentiation during embryonic development.
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Affiliation(s)
- Poonam Sehgal
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | | | - R. Ileng Kumaran
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | - Satish Kumar
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | - Veena K. Parnaik
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
- * E-mail:
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11
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Demontiero O, Vidal C, Duque G. Aging and bone loss: new insights for the clinician. Ther Adv Musculoskelet Dis 2012; 4:61-76. [PMID: 22870496 DOI: 10.1177/1759720x11430858] [Citation(s) in RCA: 317] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
It is well known that the underlying mechanisms of osteoporosis in older adults are different than those associated with estrogen deprivation. Age-related bone loss involves a gradual and progressive decline, which is also seen in men. Markedly increased bone resorption leads to the initial fall in bone mineral density. With increasing age, there is also a significant reduction in bone formation. This is mostly due to a shift from osteoblastogenesis to predominant adipogenesis in the bone marrow, which also has a lipotoxic effect that affects matrix formation and mineralization. We review new evidence on the pathophysiology of age-related bone loss with emphasis upon the mechanism of action of current osteoporosis treatments. New potential treatments are also considered, including therapeutic approaches to osteoporosis in the elderly that focus on the pathophysiology and potential reversal of adipogenic shift in bone.
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12
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Vidal C, Bermeo S, Fatkin D, Duque G. Role of the nuclear envelope in the pathogenesis of age-related bone loss and osteoporosis. BONEKEY REPORTS 2012; 1:62. [PMID: 23951459 DOI: 10.1038/bonekey.2012.62] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Accepted: 03/09/2012] [Indexed: 02/06/2023]
Abstract
The nuclear envelope is the most important border in the eukaryotic cell. The role of the nuclear envelope in cell differentiation and function is determined by a constant interaction between the elements of the nuclear envelope and the transcriptional regulators involved in signal transcription pathways. Among those components of the nuclear envelope, there is a growing evidence that changes in the expression of A-type lamins, which are essential components of the nuclear lamina, are associated with age-related changes in bone affecting the capacity of differentiation of mesenchymal stem cells into osteoblasts, favoring adipogenesis and affecting the function and survival of the osteocytes. Overall, as A-type lamins are considered as the 'guardians of the soma', these proteins are also essential for the integrity and quality of the bone and pivotal for the longevity of the musculoskeletal system.
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Affiliation(s)
- Christopher Vidal
- Ageing Bone Research Program, Sydney Medical School Nepean, The University of Sydney , Nepean Hospital , Penrith, New South Wales, Australia
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Anastasilakis AD, Polyzos SA, Toulis KA. Role of wingless tail signaling pathway in osteoporosis: an update of current knowledge. Curr Opin Endocrinol Diabetes Obes 2011; 18:383-8. [PMID: 21897222 DOI: 10.1097/med.0b013e32834afff2] [Citation(s) in RCA: 256] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE OF REVIEW Wingless tail (Wnt) pathway is crucial for osteoblast activation and action. This review summarizes the evidence published during the previous year on the emerging role of Wnt signaling alterations in the pathogenesis, diagnosis, and potential therapeutic approaches of osteoporosis. RECENT FINDINGS New insights into the mechanisms regulating Wnt/β-catenin canonical pathway, including the role of Kremen-2 receptor, lamin A/C protein, periostin, and pleiotropin in bone physiology, the crosstalk between the RUNX-2 transcription-factor cascade and the Wnt pathway, and the concept that individual Wnt ligands may have a unique and distinct mission in bone milieu, are presented. Nutritional habits may affect Wnt signaling in bone. Serum sclerostin and dickkopf-1 levels may serve as markers of bone metabolism and disease, although further standardization methods are required. Finally, the effect of current antiosteoporotic treatments on Wnt signaling is discussed, as well as the therapeutic potential of drugs targeting either Wnt signaling amplification or Wnt antagonists' attenuation. SUMMARY Although Wnt pathway is currently a field of thorough investigation, it is still far from been fully elucidated. Understanding its complex pathophysiology has evoked promising therapeutic approaches for osteoporosis. However, given that Wnt signaling is crucial for many tissues, emerging knowledge should be cautiously translated in therapeutics.
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Affiliation(s)
- Athanasios D Anastasilakis
- Department of Endocrinology, 424 General Military Hospital, Second Medical Clinic, Medical School, Aristotle University of Thessaloniki, Ippokration Hospital, Thessaloniki, Greece.
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Lamin A/C deficiency is associated with fat infiltration of muscle and bone. Mech Ageing Dev 2011; 132:552-9. [DOI: 10.1016/j.mad.2011.09.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Revised: 09/16/2011] [Accepted: 09/23/2011] [Indexed: 12/22/2022]
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