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Kumar A, Brown RA, Roufaeil DB, Gupta A, Lipford EL, Muthusamy D, Zalzman A, Hertzano R, Lowe T, Stains JP, Zalzman M. DeepFreeze 3D-biofabrication for Bioengineering and Storage of Stem Cells in Thick and Large-Scale Human Tissue Analogs. Adv Sci (Weinh) 2024; 11:e2306683. [PMID: 38183347 PMCID: PMC10953591 DOI: 10.1002/advs.202306683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Indexed: 01/08/2024]
Abstract
3D bioprinting holds great promise for meeting the increasing need for transplantable tissues and organs. However, slow printing, interlayer mixing, and the extended exposure of cells to non-physiological conditions in thick structures still hinder clinical applications. Here the DeepFreeze-3D (DF-3D) procedure and bioink for creating multilayered human-scale tissue mimetics is presented for the first time. The bioink is tailored to support stem cell viability, throughout the rapid freeform DF-3D biofabrication process. While the printer nozzle is warmed to room temperature, each layer solidifies at contact with the stage (-80 °C), or the subsequent layers, ensuring precise separation. After thawing, the encapsulated stem cells remain viable without interlayer mixing or delamination. The composed cell-laden constructs can be cryogenically stored and thawed when needed. Moreover, it is shown that under inductive conditions the stem cells differentiate into bone-like cells and grow for months after thawing, to form large tissue-mimetics in the scale of centimeters. This is important, as this approach allows the generation and storage of tissue mimetics in the size and thickness of human tissues. Therefore, DF-3D biofabrication opens new avenues for generating off-the-shelf human tissue analogs. It further holds the potential for regenerative treatments and for studying tissue pathologies caused by disease, tumor, or trauma.
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Affiliation(s)
- Alok Kumar
- Department of Biochemistry and Molecular BiologyUniversity of Maryland School of MedicineBaltimoreMD21201USA
- Cardiovascular Research CenterMassachusetts General Hospital (MGH)Harvard Medical SchoolBostonMA02114USA
| | - Robert A. Brown
- Department of Biochemistry and Molecular BiologyUniversity of Maryland School of MedicineBaltimoreMD21201USA
| | - Daniel Benyamien Roufaeil
- Department of Biochemistry and Molecular BiologyUniversity of Maryland School of MedicineBaltimoreMD21201USA
| | - Aditi Gupta
- Department of Biochemistry and Molecular BiologyUniversity of Maryland School of MedicineBaltimoreMD21201USA
- Neurotology BranchNIDCD, NIHBethesdaMarylandUnited States
| | - Erika L. Lipford
- Department of Otorhinolaryngology‐Head and Neck SurgeryUniversity of Maryland School of MedicineBaltimoreMD21201USA
| | - Divya Muthusamy
- Department of Oral and Maxillofacial SurgeryUniversity of Maryland School of DentistryBaltimoreMD21201USA
- Fischell Department of BioengineeringUniversity of Maryland A. James Clark School of EngineeringCollege ParkMD20742USA
| | - Amihai Zalzman
- Department of Biochemistry and Molecular BiologyUniversity of Maryland School of MedicineBaltimoreMD21201USA
| | - Ronna Hertzano
- Department of Otorhinolaryngology‐Head and Neck SurgeryUniversity of Maryland School of MedicineBaltimoreMD21201USA
- Neurotology BranchNIDCD, NIHBethesdaMarylandUnited States
| | - Tao Lowe
- Department of Oral and Maxillofacial SurgeryUniversity of Maryland School of DentistryBaltimoreMD21201USA
- Fischell Department of BioengineeringUniversity of Maryland A. James Clark School of EngineeringCollege ParkMD20742USA
| | - Joseph P. Stains
- Department of OrthopedicsUniversity of Maryland School of MedicineBaltimoreMD21201USA
| | - Michal Zalzman
- Department of Biochemistry and Molecular BiologyDepartment of Otorhinolaryngology‐Head and Neck SurgeryMarlene and Stewart Greenbaum Cancer CenterThe Center for Stem Cell Biology and Regenerative MedicineUniversity of Maryland School of MedicineBaltimoreMD21201USA
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2
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Leser JM, Torre OM, Gould NR, Guo Q, Buck HV, Kodama J, Otsuru S, Stains JP. Osteoblast-lineage calcium/calmodulin-dependent kinase 2 delta and gamma regulates bone mass and quality. Proc Natl Acad Sci U S A 2023; 120:e2304492120. [PMID: 37976259 PMCID: PMC10666124 DOI: 10.1073/pnas.2304492120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 09/30/2023] [Indexed: 11/19/2023] Open
Abstract
Bone regulates its mass and quality in response to diverse mechanical, hormonal, and local signals. The bone anabolic or catabolic responses to these signals are often received by osteocytes, which then coordinate the activity of osteoblasts and osteoclasts on bone surfaces. We previously established that calcium/calmodulin-dependent kinase 2 (CaMKII) is required for osteocytes to respond to some bone anabolic cues in vitro. However, a role for CaMKII in bone physiology in vivo is largely undescribed. Here, we show that conditional codeletion of the most abundant isoforms of CaMKII (delta and gamma) in mature osteoblasts and osteocytes [Ocn-cre:Camk2d/Camk2g double-knockout (dCKO)] caused severe osteopenia in both cortical and trabecular compartments by 8 wk of age. In addition to having less bone mass, dCKO bones are of worse quality, with significant deficits in mechanical properties, and a propensity to fracture. This striking skeletal phenotype is multifactorial, including diminished osteoblast activity, increased osteoclast activity, and altered phosphate homeostasis both systemically and locally. These dCKO mice exhibited decreased circulating phosphate (hypophosphatemia) and increased expression of the phosphate-regulating hormone fibroblast growth factor 23. Additionally, dCKO mice expressed less bone-derived tissue nonspecific alkaline phosphatase protein than control mice. Consistent with altered phosphate homeostasis, we observed that dCKO bones were hypo-mineralized with prominent osteoid seams, analogous to the phenotypes of mice with hypophosphatemia. Altogether, these data reveal a fundamental role for osteocyte CaMKIIδ and CaMKIIγ in the maintenance of bone mass and bone quality and link osteoblast/osteocyte CaMKII to phosphate homeostasis.
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Affiliation(s)
- Jenna M. Leser
- Department of Othopaedics, University of Maryland School of Medicine, Baltimore, MD21201
| | - Olivia M. Torre
- Department of Othopaedics, University of Maryland School of Medicine, Baltimore, MD21201
| | - Nicole R. Gould
- Department of Othopaedics, University of Maryland School of Medicine, Baltimore, MD21201
| | - Qiaoyue Guo
- Department of Othopaedics, University of Maryland School of Medicine, Baltimore, MD21201
| | - Heather V. Buck
- Department of Othopaedics, University of Maryland School of Medicine, Baltimore, MD21201
| | - Joe Kodama
- Department of Othopaedics, University of Maryland School of Medicine, Baltimore, MD21201
| | - Satoru Otsuru
- Department of Othopaedics, University of Maryland School of Medicine, Baltimore, MD21201
| | - Joseph P. Stains
- Department of Othopaedics, University of Maryland School of Medicine, Baltimore, MD21201
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3
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Kim SP, Seward AH, Garcia-Diaz J, Alekos N, Gould NR, Aja S, Stains JP, Wolfgang MJ, Riddle RC. Peroxisome proliferator activated receptor-γ in osteoblasts controls bone formation and fat mass by regulating sclerostin expression. iScience 2023; 26:106999. [PMID: 37534168 PMCID: PMC10391670 DOI: 10.1016/j.isci.2023.106999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 05/01/2023] [Accepted: 05/25/2023] [Indexed: 08/04/2023] Open
Abstract
The nuclear receptor peroxisome proliferator activated receptor-γ (PPARγ) is a key contributor to metabolic function via its adipogenic and insulin-sensitizing functions, but it has negative effects on skeletal homeostasis. Here, we questioned whether the skeletal and metabolic actions of PPARγ are linked. Ablating Pparg expression in osteoblasts and osteocytes produced a high bone mass phenotype, secondary to increased osteoblast activity, and a reduction in subcutaneous fat mass because of reduced fatty acid synthesis and increased fat oxidation. The skeletal and metabolic phenotypes in Pparg mutants proceed from the regulation of sclerostin production by PPARγ. Mutants exhibited reductions in skeletal Sost expression and serum sclerostin levels while increasing production normalized both phenotypes. Importantly, disrupting the production of sclerostin synergized with the insulin-sensitizing actions of a PPARγ agonist while preventing bone loss. These data suggest that modulating sclerostin action may prevent bone loss associated with anti-diabetic therapies and augment their metabolic actions.
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Affiliation(s)
- Soohyun P. Kim
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Avery H. Seward
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jean Garcia-Diaz
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Nathalie Alekos
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Nicole R. Gould
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Susan Aja
- Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Joseph P. Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Michael J. Wolfgang
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ryan C. Riddle
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Research and Development Service, Baltimore Veterans Administration Medical Center, Baltimore, MD 21201, USA
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4
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Bernier M, Enamorado IN, Gómez-Cabrera MC, Calvo-Rubio M, González-Reyes JA, Price NL, Cortés-Rodríguez AB, Rodríguez-Aguilera JC, Rodríguez-López S, Mitchell SJ, Murt KN, Kalafut K, Williams KM, Ward CW, Stains JP, Brea-Calvo G, Villalba JM, Cortassa S, Aon MA, de Cabo R. Age-dependent impact of two exercise training regimens on genomic and metabolic remodeling in skeletal muscle and liver of male mice. NPJ Aging 2022; 8:8. [PMID: 35927269 PMCID: PMC9237062 DOI: 10.1038/s41514-022-00089-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 05/11/2022] [Indexed: 11/09/2022]
Abstract
Skeletal muscle adapts to different exercise training modalities with age; however, the impact of both variables at the systemic and tissue levels is not fully understood. Here, adult and old C57BL/6 male mice were assigned to one of three groups: sedentary, daily high-intensity intermittent training (HIIT), or moderate intensity continuous training (MICT) for 4 weeks, compatible with the older group's exercise capacity. Improvements in body composition, fasting blood glucose, and muscle strength were mostly observed in the MICT old group, while effects of HIIT training in adult and old animals was less clear. Skeletal muscle exhibited structural and functional adaptations to exercise training, as revealed by electron microscopy, OXPHOS assays, respirometry, and muscle protein biomarkers. Transcriptomics analysis of gastrocnemius muscle combined with liver and serum metabolomics unveiled an age-dependent metabolic remodeling in response to exercise training. These results support a tailored exercise prescription approach aimed at improving health and ameliorating age-associated loss of muscle strength and function in the elderly.
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Affiliation(s)
- Michel Bernier
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Ignacio Navas Enamorado
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
- Translational Medicine Section, Akouos, Inc., 645 Summer St, Boston, MA, 02210, USA
| | - Mari Carmen Gómez-Cabrera
- Freshage Research Group, Department of Physiology, Faculty of Medicine, University of Valencia, and CIBERFES, Fundación Investigación Hospital Clínico Universitario/INCLIVA, Valencia, Spain
| | - Miguel Calvo-Rubio
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
- Departamento de Biología Celular, Fisiología e Inmunología, Campus de Excelencia Internacional Agroalimentario, ceiA3, Universidad de Córdoba, Campus de Rabanales, Edificio Severo Ochoa, 3ª planta, 14014, Córdoba, Spain
| | - Jose Antonio González-Reyes
- Departamento de Biología Celular, Fisiología e Inmunología, Campus de Excelencia Internacional Agroalimentario, ceiA3, Universidad de Córdoba, Campus de Rabanales, Edificio Severo Ochoa, 3ª planta, 14014, Córdoba, Spain
| | - Nathan L Price
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | | | | | - Sandra Rodríguez-López
- Departamento de Biología Celular, Fisiología e Inmunología, Campus de Excelencia Internacional Agroalimentario, ceiA3, Universidad de Córdoba, Campus de Rabanales, Edificio Severo Ochoa, 3ª planta, 14014, Córdoba, Spain
| | - Sarah J Mitchell
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Kelsey N Murt
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Krystle Kalafut
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Katrina M Williams
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Christopher W Ward
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Gloria Brea-Calvo
- Centro Andaluz de Biología del Desarrollo and CIBERER, Instituto de Salud Carlos III, Universidad Pablo de Olavide - CSIC - JA, Sevilla, 41013, Spain
| | - Jose M Villalba
- Departamento de Biología Celular, Fisiología e Inmunología, Campus de Excelencia Internacional Agroalimentario, ceiA3, Universidad de Córdoba, Campus de Rabanales, Edificio Severo Ochoa, 3ª planta, 14014, Córdoba, Spain
| | - Sonia Cortassa
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Miguel A Aon
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Rafael de Cabo
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD, 21224, USA.
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5
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Iyer SR, Shah SB, Ward CW, Stains JP, Folker ES, Lovering RM. Inhibition of YAP signaling improves recovery in injured skeletal muscle. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.r5346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Shama R. Iyer
- OrthopaedicsUniversity of Maryland School of MedicineBaltimoreMD
| | - Sameer B. Shah
- Departments of Orthopaedic Surgery and BioengineeringUniversity of California San DiegoSan DiegoCA
| | | | - Joseph P. Stains
- OrthopaedicsUniversity of Maryland School of MedicineBaltimoreMD
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6
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Leser JM, Harriot A, Buck HV, Ward CW, Stains JP. Aging, Osteo-Sarcopenia, and Musculoskeletal Mechano-Transduction. Front Rehabil Sci 2021; 2:782848. [PMID: 36004321 PMCID: PMC9396756 DOI: 10.3389/fresc.2021.782848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 11/10/2021] [Indexed: 11/13/2022]
Abstract
The decline in the mass and function of bone and muscle is an inevitable consequence of healthy aging with early onset and accelerated decline in those with chronic disease. Termed osteo-sarcopenia, this condition predisposes the decreased activity, falls, low-energy fractures, and increased risk of co-morbid disease that leads to musculoskeletal frailty. The biology of osteo-sarcopenia is most understood in the context of systemic neuro-endocrine and immune/inflammatory alterations that drive inflammation, oxidative stress, reduced autophagy, and cellular senescence in the bone and muscle. Here we integrate these concepts to our growing understanding of how bone and muscle senses, responds and adapts to mechanical load. We propose that age-related alterations in cytoskeletal mechanics alter load-sensing and mechano-transduction in bone osteocytes and muscle fibers which underscores osteo-sarcopenia. Lastly, we examine the evidence for exercise as an effective countermeasure to osteo-sarcopenia.
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Affiliation(s)
| | | | | | | | - Joseph P. Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, United States
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7
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Gould NR, Leser JM, Torre OM, Khairallah RJ, Ward CW, Stains JP. In vitro Fluid Shear Stress Induced Sclerostin Degradation and CaMKII Activation in Osteocytes. Bio Protoc 2021; 11:e4251. [PMID: 35005095 PMCID: PMC8678913 DOI: 10.21769/bioprotoc.4251] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 09/18/2021] [Accepted: 09/27/2021] [Indexed: 11/19/2023] Open
Abstract
Bone is a dynamic tissue that adapts to changes in its mechanical environment. Mechanical stimuli pressurize interstitial fluid in the lacunar-canalicular system within the bone matrix, causing fluid shear stress (FSS) across bone embedded, mechano-sensitive osteocytes. Therefore, modeling this mechanical stimulus in vitro is vital for identifying mechano-transduction cascades that contribute to the regulation of mechano-responsive proteins, such as the Wnt/β-catenin antagonist, sclerostin, which is reduced in response to FSS. Recently, we reported the rapid post-translational degradation of sclerostin protein in bone cells following FSS. Given the fundamental nature of sclerostin to bone physiology and the nuances of studying its rapid post-translational control, here, we detail our FSS protocol, and adaptations that can be made, to stimulate Ocy454 osteocyte-like cells to study sclerostin protein in vitro. While this protocol is optimized for detecting sclerostin degradation by western blot, this protocol can be adapted to examine transcriptional changes with RT-qPCR, cellular dynamics with live cell imaging, or secreted factors in the FSS buffer. This protocol utilizes 3D-printed FSS tips that are compatible with commercially available 96-well plates, allowing for high experimental accessibility, versatility, and throughput. However, this protocol can be adapted for any FSS chamber. It can also be combined with pharmacological inhibitors or genetic manipulations to interrogate the role of specific cellular components. In all, this experimental set-up and protocol is highly adaptable to allow for many experimental outcomes to examine many aspects of cell mechano-transduction.
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Affiliation(s)
- Nicole R. Gould
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, USA
| | - Jenna M. Leser
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, USA
| | - Olivia M. Torre
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, USA
| | | | - Christopher W. Ward
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, USA
| | - Joseph P. Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, USA
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8
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Aljohani H, Senbanjo LT, Al Qranei M, Stains JP, Chellaiah MA. Methylsulfonylmethane Increases the Alveolar Bone Density of Mandibles in Aging Female Mice. Front Physiol 2021; 12:708905. [PMID: 34671266 PMCID: PMC8521043 DOI: 10.3389/fphys.2021.708905] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 09/06/2021] [Indexed: 11/13/2022] Open
Abstract
Methylsulfonylmethane (MSM) is a naturally occurring anti-inflammatory compound that effectively treats multiple degenerative diseases such as osteoarthritis and acute pancreatitis. Our previous studies have demonstrated the ability of MSM to differentiate stem cells from human exfoliated deciduous (SHED) teeth into osteoblast-like cells. This study examined the systemic effect of MSM in 36-week-old aging C57BL/6 female mice in vivo by injecting MSM for 13 weeks. Serum analyses showed an increase in expression levels of bone formation markers [osteocalcin (OCN) and procollagen type 1 intact N-terminal propeptide (P1NP)] and a reduction in bone resorption markers [tartrate-resistant acid phosphatase (TRAP) and C-terminal telopeptide of type I collag (CTX-I)] in MSM-injected animals. Micro-computed tomographic images demonstrated an increase in trabecular bone density in mandibles. The trabecular bone density tended to be higher in the femur, although the increase was not significantly different between the MSM- and phosphate-buffered saline (PBS)-injected mice. In mandibles, an increase in bone density with a corresponding decrease in the marrow cavity was observed in the MSM-injected mice. Furthermore, immunohistochemical analyses of the mandibles for the osteoblast-specific marker - OCN, and the mesenchymal stem cell-specific marker - CD105 showed a significant increase and decrease in OCN and CD105 positive cells, respectively. Areas of bone loss were observed in the inter-radicular region of mandibles in control mice. However, this loss was considerably decreased due to stimulation of bone formation in response to MSM injection. In conclusion, our study has demonstrated the ability of MSM to induce osteoblast formation and function in vivo, resulting in increased bone formation in the mandible. Hence, the application of MSM and stem cells of interest may be the right combination in alveolar bone regeneration under periodontal or other related diseases that demonstrate bone loss.
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Affiliation(s)
- Hanan Aljohani
- Department of Oncology and Diagnostic Sciences, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD, United States.,Department of Oral Medicine and Diagnostics Sciences, School of Dentistry, King Saud University, Riyadh, Saudi Arabia
| | - Linda T Senbanjo
- Department of Oncology and Diagnostic Sciences, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD, United States
| | - Mohammed Al Qranei
- Department of Oncology and Diagnostic Sciences, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD, United States.,Department of Preventive Dental Sciences, School of Dentistry, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
| | - Joseph P Stains
- Department of Orthopedics, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Meenakshi A Chellaiah
- Department of Oncology and Diagnostic Sciences, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD, United States
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Geist Hauserman J, Stavusis J, Joca HC, Robinett JC, Hanft L, Vandermeulen J, Zhao R, Stains JP, Konstantopoulos K, McDonald KS, Ward C, Kontrogianni-Konstantopoulos A. Sarcomeric deficits underlie MYBPC1-associated myopathy with myogenic tremor. JCI Insight 2021; 6:e147612. [PMID: 34437302 PMCID: PMC8525646 DOI: 10.1172/jci.insight.147612] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 08/25/2021] [Indexed: 12/02/2022] Open
Abstract
Myosin binding protein-C slow (sMyBP-C) comprises a subfamily of cytoskeletal proteins encoded by MYBPC1 that is expressed in skeletal muscles where it contributes to myosin thick filament stabilization and actomyosin cross-bridge regulation. Recently, our group described the causal association of dominant missense pathogenic variants in MYBPC1 with an early-onset myopathy characterized by generalized muscle weakness, hypotonia, dysmorphia, skeletal deformities, and myogenic tremor, occurring in the absence of neuropathy. To mechanistically interrogate the etiologies of this MYBPC1-associated myopathy in vivo, we generated a knock-in mouse model carrying the E248K pathogenic variant. Using a battery of phenotypic, behavioral, and physiological measurements spanning neonatal to young adult life, we found that heterozygous E248K mice faithfully recapitulated the onset and progression of generalized myopathy, tremor occurrence, and skeletal deformities seen in human carriers. Moreover, using a combination of biochemical, ultrastructural, and contractile assessments at the level of the tissue, cell, and myofilaments, we show that the loss-of-function phenotype observed in mutant muscles is primarily driven by disordered and misaligned sarcomeres containing fragmented and out-of-register internal membranes that result in reduced force production and tremor initiation. Collectively, our findings provide mechanistic insights underscoring the E248K-disease pathogenesis and offer a relevant preclinical model for therapeutic discovery.
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Affiliation(s)
- Janelle Geist Hauserman
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Janis Stavusis
- Latvian Biomedical Research and Study Centre, Riga, Latvia
| | - Humberto C. Joca
- Department of Orthopedics, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Joel C. Robinett
- Department of Medical Pharmacology and Physiology, University of Missouri, School of Medicine Columbia, Missouri, USA
| | - Laurin Hanft
- Department of Medical Pharmacology and Physiology, University of Missouri, School of Medicine Columbia, Missouri, USA
| | - Jack Vandermeulen
- Department of Orthopedics, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Runchen Zhao
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - Joseph P. Stains
- Department of Orthopedics, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | | | - Kerry S. McDonald
- Department of Medical Pharmacology and Physiology, University of Missouri, School of Medicine Columbia, Missouri, USA
| | - Christopher Ward
- Department of Orthopedics, University of Maryland School of Medicine, Baltimore, Maryland, USA
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10
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Abstract
Bone is a mechano-responsive tissue that adapts to changes in its mechanical environment. Increases in strain lead to increased bone mass acquisition, whereas decreases in strain lead to a loss of bone mass. Given that mechanical stress is a regulator of bone mass and quality, it is important to understand how bone cells sense and transduce these mechanical cues into biological changes to identify druggable targets that can be exploited to restore bone cell mechano-sensitivity or to mimic mechanical load. Many studies have identified individual cytoskeletal components - microtubules, actin, and intermediate filaments - as mechano-sensors in bone. However, given the high interconnectedness and interaction between individual cytoskeletal components, and that they can assemble into multiple discreet cellular structures, it is likely that the cytoskeleton as a whole, rather than one specific component, is necessary for proper bone cell mechano-transduction. This review will examine the role of each cytoskeletal element in bone cell mechano-transduction and will present a unified view of how these elements interact and work together to create a mechano-sensor that is necessary to control bone formation following mechanical stress.
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Affiliation(s)
- Nicole R Gould
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Olivia M Torre
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Jenna M Leser
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA..
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11
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Aljohani H, Stains JP, Majumdar S, Srinivasan D, Senbanjo L, Chellaiah MA. Peptidomimetic inhibitor of L-plastin reduces osteoclastic bone resorption in aging female mice. Bone Res 2021; 9:22. [PMID: 33837180 PMCID: PMC8035201 DOI: 10.1038/s41413-020-00135-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 11/22/2020] [Accepted: 11/26/2020] [Indexed: 12/12/2022] Open
Abstract
L-plastin (LPL) was identified as a potential regulator of the actin-bundling process involved in forming nascent sealing zones (NSZs), which are precursor zones for mature sealing zones. TAT-fused cell-penetrating small molecular weight LPL peptide (TAT- MARGSVSDEE, denoted as an inhibitory LPL peptide) attenuated the formation of NSZs and impaired bone resorption in vitro in osteoclasts. Also, the genetic deletion of LPL in mice demonstrated decreased eroded perimeters and increased trabecular bone density. In the present study, we hypothesized that targeting LPL with the inhibitory LPL peptide in vivo could reduce osteoclast function and increase bone density in a mice model of low bone mass. We injected aging C57BL/6 female mice (36 weeks old) subcutaneously with the inhibitory and scrambled peptides of LPL for 14 weeks. Micro-CT and histomorphometry analyses demonstrated an increase in trabecular bone density of femoral and tibial bones with no change in cortical thickness in mice injected with the inhibitory LPL peptide. A reduction in the serum levels of CTX-1 peptide suggests that the increase in bone density is associated with a decrease in osteoclast function. No changes in bone formation rate and mineral apposition rate, and the serum levels of P1NP indicate that the inhibitory LPL peptide does not affect osteoblast function. Our study shows that the inhibitory LPL peptide can block osteoclast function without impairing the function of osteoblasts. LPL peptide could be developed as a prospective therapeutic agent to treat osteoporosis.
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Affiliation(s)
- Hanan Aljohani
- Department of Oncology and Diagnostic Sciences, School of Dentistry, University of Maryland, Baltimore, MD, USA
- Department of Oral Medicine and Diagnostics Sciences, King Saud University, School of Dentistry, Riyadh, Kingdom of Saudi Arabia
| | - Joseph P Stains
- Department of Orthopedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sunipa Majumdar
- Department of Oncology and Diagnostic Sciences, School of Dentistry, University of Maryland, Baltimore, MD, USA
| | - Deepa Srinivasan
- Department of Oncology and Diagnostic Sciences, School of Dentistry, University of Maryland, Baltimore, MD, USA
| | - Linda Senbanjo
- Department of Oncology and Diagnostic Sciences, School of Dentistry, University of Maryland, Baltimore, MD, USA
| | - Meenakshi A Chellaiah
- Department of Oncology and Diagnostic Sciences, School of Dentistry, University of Maryland, Baltimore, MD, USA.
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12
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Gould NR, Williams KM, Joca HC, Torre OM, Lyons JS, Leser JM, Srikanth MP, Hughes M, Khairallah RJ, Feldman RA, Ward CW, Stains JP. Disparate bone anabolic cues activate bone formation by regulating the rapid lysosomal degradation of sclerostin protein. eLife 2021; 10:e64393. [PMID: 33779549 PMCID: PMC8032393 DOI: 10.7554/elife.64393] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 03/26/2021] [Indexed: 02/06/2023] Open
Abstract
The downregulation of sclerostin in osteocytes mediates bone formation in response to mechanical cues and parathyroid hormone (PTH). To date, the regulation of sclerostin has been attributed exclusively to the transcriptional downregulation of the Sost gene hours after stimulation. Using mouse models and rodent cell lines, we describe the rapid, minute-scale post-translational degradation of sclerostin protein by the lysosome following mechanical load and PTH. We present a model, integrating both new and established mechanically and hormonally activated effectors into the regulated degradation of sclerostin by lysosomes. Using a mouse forelimb mechanical loading model, we find transient inhibition of lysosomal degradation or the upstream mechano-signaling pathway controlling sclerostin abundance impairs subsequent load-induced bone formation by preventing sclerostin degradation. We also link dysfunctional lysosomes to aberrant sclerostin regulation using human Gaucher disease iPSCs. These results reveal how bone anabolic cues post-translationally regulate sclerostin abundance in osteocytes to regulate bone formation.
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Affiliation(s)
- Nicole R Gould
- Department of Orthopaedics, University of Maryland School of MedicineBaltimoreUnited States
| | - Katrina M Williams
- Department of Orthopaedics, University of Maryland School of MedicineBaltimoreUnited States
| | - Humberto C Joca
- Center for Biomedical Engineering and Technology, University of Maryland School of MedicineBaltimoreUnited States
| | - Olivia M Torre
- Department of Orthopaedics, University of Maryland School of MedicineBaltimoreUnited States
| | - James S Lyons
- Department of Orthopaedics, University of Maryland School of MedicineBaltimoreUnited States
| | - Jenna M Leser
- Department of Orthopaedics, University of Maryland School of MedicineBaltimoreUnited States
| | - Manasa P Srikanth
- Department of Microbiology and Immunology, University of Maryland School of MedicineBaltimoreUnited States
| | - Marcus Hughes
- Department of Orthopaedics, University of Maryland School of MedicineBaltimoreUnited States
| | | | - Ricardo A Feldman
- Department of Microbiology and Immunology, University of Maryland School of MedicineBaltimoreUnited States
| | - Christopher W Ward
- Department of Orthopaedics, University of Maryland School of MedicineBaltimoreUnited States
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of MedicineBaltimoreUnited States
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13
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Pratt SJP, Lee RM, Chang KT, Hernández-Ochoa EO, Annis DA, Ory EC, Thompson KN, Bailey PC, Mathias TJ, Ju JA, Vitolo MI, Schneider MF, Stains JP, Ward CW, Martin SS. Mechanoactivation of NOX2-generated ROS elicits persistent TRPM8 Ca 2+ signals that are inhibited by oncogenic KRas. Proc Natl Acad Sci U S A 2020; 117:26008-26019. [PMID: 33020304 PMCID: PMC7584994 DOI: 10.1073/pnas.2009495117] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Changes in the mechanical microenvironment and mechanical signals are observed during tumor progression, malignant transformation, and metastasis. In this context, understanding the molecular details of mechanotransduction signaling may provide unique therapeutic targets. Here, we report that normal breast epithelial cells are mechanically sensitive, responding to transient mechanical stimuli through a two-part calcium signaling mechanism. We observed an immediate, robust rise in intracellular calcium (within seconds) followed by a persistent extracellular calcium influx (up to 30 min). This persistent calcium was sustained via microtubule-dependent mechanoactivation of NADPH oxidase 2 (NOX2)-generated reactive oxygen species (ROS), which acted on transient receptor potential cation channel subfamily M member 8 (TRPM8) channels to prolong calcium signaling. In contrast, the introduction of a constitutively active oncogenic KRas mutation inhibited the magnitude of initial calcium signaling and severely blunted persistent calcium influx. The identification that oncogenic KRas suppresses mechanically-induced calcium at the level of ROS provides a mechanism for how KRas could alter cell responses to tumor microenvironment mechanics and may reveal chemotherapeutic targets for cancer. Moreover, we find that expression changes in both NOX2 and TRPM8 mRNA predict poor clinical outcome in estrogen receptor (ER)-negative breast cancer patients, a population with limited available treatment options. The clinical and mechanistic data demonstrating disruption of this mechanically-activated calcium pathway in breast cancer patients and by KRas activation reveal signaling alterations that could influence cancer cell responses to the tumor mechanical microenvironment and impact patient survival.
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Affiliation(s)
- Stephen J P Pratt
- Program in Biochemistry and Molecular Biology, School of Medicine, University of Maryland, Baltimore, MD 21201;
- Department of Pharmacology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Marlene and Stewart Greenebaum National Cancer Institute Comprehensive Cancer Center, School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Rachel M Lee
- Department of Pharmacology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Marlene and Stewart Greenebaum National Cancer Institute Comprehensive Cancer Center, School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Katarina T Chang
- Department of Pharmacology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Marlene and Stewart Greenebaum National Cancer Institute Comprehensive Cancer Center, School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Erick O Hernández-Ochoa
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Maryland, Baltimore, MD 21201
| | - David A Annis
- Department of Pharmacology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Marlene and Stewart Greenebaum National Cancer Institute Comprehensive Cancer Center, School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Eleanor C Ory
- Department of Pharmacology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Marlene and Stewart Greenebaum National Cancer Institute Comprehensive Cancer Center, School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Keyata N Thompson
- Department of Pharmacology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Marlene and Stewart Greenebaum National Cancer Institute Comprehensive Cancer Center, School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Patrick C Bailey
- Program in Biochemistry and Molecular Biology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Department of Pharmacology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Marlene and Stewart Greenebaum National Cancer Institute Comprehensive Cancer Center, School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Trevor J Mathias
- Department of Pharmacology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Marlene and Stewart Greenebaum National Cancer Institute Comprehensive Cancer Center, School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Julia A Ju
- Department of Pharmacology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Marlene and Stewart Greenebaum National Cancer Institute Comprehensive Cancer Center, School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Michele I Vitolo
- Department of Pharmacology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Marlene and Stewart Greenebaum National Cancer Institute Comprehensive Cancer Center, School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Martin F Schneider
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Joseph P Stains
- Department of Orthopaedics, School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Christopher W Ward
- Department of Orthopaedics, School of Medicine, University of Maryland, Baltimore, MD 21201
- School of Nursing, University of Maryland, Baltimore, MD 21201
| | - Stuart S Martin
- Department of Pharmacology, School of Medicine, University of Maryland, Baltimore, MD 21201;
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD 21201
- Marlene and Stewart Greenebaum National Cancer Institute Comprehensive Cancer Center, School of Medicine, University of Maryland, Baltimore, MD 21201
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14
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Pratt SJP, Lee RM, Hernandez-Ochoa EO, Ory EC, Thompson KN, Bailey PC, Mathias TJ, Ju JA, Vitolo MI, Schneider MF, Stains JP, Ward CW, Martin SS. Abstract 2575: Mechanoactivation of NOX2-generated ROS elicits persistent TRPM8 Ca2+ signals that are inhibited by oncogenic KRas. Cancer Res 2020. [DOI: 10.1158/1538-7445.am2020-2575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Changes in the mechanical microenvironment and mechanical signals are observed during tumor progression, malignant transformation, and metastasis. In this context, understanding the molecular details of mechanotransduction signaling may provide unique therapeutic targets. Here we report that normal breast epithelial cells are mechanically sensitive, responding to mechanical stimuli through a two-part calcium signaling mechanism. We observed an immediate, robust rise in intracellular calcium (within seconds) followed by a persistent extracellular calcium influx (up to 30 minutes). This persistent calcium was sustained via microtubule-dependent mechano-activation of NADPH oxidase 2 (NOX2)-generated reactive oxygen species (ROS), which acted on TRPM8 channels to prolong calcium signaling. In contrast, the introduction of a constitutively-active oncogenic KRas mutation inhibited the magnitude of initial calcium signaling and severely blunted persistent calcium influx. The identification that oncogenic KRas suppresses mechanically-induced calcium at the level of ROS provides a novel mechanism for how KRas could alter cell responses to tumor microenvironment mechanics and may reveal new chemotherapeutic targets for cancer. Moreover, we find that expression changes in both NOX2 and TRPM8 mRNA predicts poor clinical outcome in estrogen receptor (ER) negative breast cancer patients, a population with limited available treatment options. The clinical and mechanistic data demonstrating disruption of this mechanically-activated calcium pathway in breast cancer patients and by KRas activation reveal novel signaling alterations that could influence cancer cell responses to the tumor mechanical microenvironment and impact patient survival.
Citation Format: Stephen JP Pratt, Rachel M. Lee, Erick O. Hernandez-Ochoa, Eleanor C. Ory, Keyata N. Thompson, Patrick C. Bailey, Trevor J. Mathias, Julia A. Ju, Michele I. Vitolo, Martin F. Schneider, Joseph P. Stains, Christopher W. Ward, Stuart S. Martin. Mechanoactivation of NOX2-generated ROS elicits persistent TRPM8 Ca2+ signals that are inhibited by oncogenic KRas [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2575.
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Affiliation(s)
| | | | | | | | | | | | | | - Julia A. Ju
- University of Maryland, Baltimore, Baltimore, MD
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15
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Williams KM, Leser JM, Gould NR, Joca HC, Lyons JS, Khairallah RJ, Ward CW, Stains JP. TRPV4 calcium influx controls sclerostin protein loss independent of purinergic calcium oscillations. Bone 2020; 136:115356. [PMID: 32272228 PMCID: PMC7605285 DOI: 10.1016/j.bone.2020.115356] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 04/03/2020] [Accepted: 04/03/2020] [Indexed: 02/09/2023]
Abstract
Skeletal remodeling is driven in part by the osteocyte's ability to respond to its mechanical environment by regulating the abundance of sclerostin, a negative regulator of bone mass. We have recently shown that the osteocyte responds to fluid shear stress via the microtubule network-dependent activation of NADPH oxidase 2 (NOX2)-generated reactive oxygen species and subsequent opening of TRPV4 cation channels, leading to calcium influx, activation of CaMKII, and rapid sclerostin protein downregulation. In addition to the initial calcium influx, purinergic receptor signaling and calcium oscillations occur in response to mechanical load and prior to rapid sclerostin protein loss. However, the independent contributions of TRPV4-mediated calcium influx and purinergic calcium oscillations to the rapid sclerostin protein downregulation remain unclear. Here, we showed that NOX2 and TRPV4-dependent calcium influx is required for calcium oscillations, and that TRPV4 activation is both necessary and sufficient for sclerostin degradation. In contrast, calcium oscillations are neither necessary nor sufficient to acutely decrease sclerostin protein abundance. However, blocking oscillations with apyrase prevented fluid shear stress induced changes in osterix (Sp7), osteoprotegerin (Tnfrsf11b), and sclerostin (Sost) gene expression. In total, these data provide key mechanistic insights into the way bone cells translate mechanical cues to target a key effector of bone formation, sclerostin.
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Affiliation(s)
- Katrina M Williams
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Jenna M Leser
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Nicole R Gould
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Humberto C Joca
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - James S Lyons
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | | | - Christopher W Ward
- Department of Orthopaedics, University of Maryland School of Nursing, Baltimore, MD 21201, USA.
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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16
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Joca HC, Harriot A, Leser J, Coleman A, Shi G, Stains JP, Ward CW. Microtubule Remodeling Contributes to the Loss of Force and Power in Aging Skeletal Muscle. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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17
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Chellaiah MA, Moorer MC, Majumdar S, Aljohani H, Morley SC, Yingling V, Stains JP. L-Plastin deficiency produces increased trabecular bone due to attenuation of sealing ring formation and osteoclast dysfunction. Bone Res 2020; 8:3. [PMID: 31993243 PMCID: PMC6976634 DOI: 10.1038/s41413-019-0079-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 08/19/2019] [Accepted: 08/26/2019] [Indexed: 12/17/2022] Open
Abstract
Bone resorption requires the formation of complex, actin-rich cytoskeletal structures. During the early phase of sealing ring formation by osteoclasts, L-plastin regulates actin-bundling to form the nascent sealing zones (NSZ). Here, we show that L-plastin knockout mice produce osteoclasts that are deficient in the formation of NSZs, are hyporesorptive, and make superficial resorption pits in vitro. Transduction of TAT-fused full-length L-plastin peptide into osteoclasts from L-plastin knockout mice rescued the formation of nascent sealing zones and sealing rings in a time-dependent manner. This response was not observed with mutated full-length L-plastin (Ser-5 and -7 to Ala-5 and -7) peptide. In contrast to the observed defect in the NSZ, L-plastin deficiency did not affect podosome formation or adhesion of osteoclasts in vitro or in vivo. Histomorphometry analyses in 8- and 12-week-old female L-plastin knockout mice demonstrated a decrease in eroded perimeters and an increase in trabecular bone density, without a change in bone formation by osteoblasts. This decrease in eroded perimeters supports that osteoclast function is attenuated in L-plastin knockouts. Micro-CT analyses confirmed a marked increase in trabecular bone mass. In conclusion, female L-plastin knockout mice had increased trabecular bone density due to impaired bone resorption by osteoclasts. L-plastin could be a potential target for therapeutic interventions to treat trabecular bone loss.
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Affiliation(s)
- Meenakshi A. Chellaiah
- Department of Oncology and Diagnostic Sciences, School of Dentistry, University of Maryland, Baltimore, MD USA
| | - Megan C. Moorer
- Department of Orthopedics, University of Maryland School of Medicine, Baltimore, MD USA
| | - Sunipa Majumdar
- Department of Oncology and Diagnostic Sciences, School of Dentistry, University of Maryland, Baltimore, MD USA
| | - Hanan Aljohani
- Department of Oncology and Diagnostic Sciences, School of Dentistry, University of Maryland, Baltimore, MD USA
| | - Sharon C. Morley
- Department of Pediatrics, Division of Infectious Diseases, and Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO USA
| | - Vanessa Yingling
- Department of Kinesiology, California State University, East Bay, Hayward, CA USA
| | - Joseph P. Stains
- Department of Orthopedics, University of Maryland School of Medicine, Baltimore, MD USA
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18
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Balenga N, Koh J, Azimzadeh P, Hogue J, Gabr M, Stains JP, Olson JA. Parathyroid-Targeted Overexpression of Regulator of G-Protein Signaling 5 (RGS5) Causes Hyperparathyroidism in Transgenic Mice. J Bone Miner Res 2019; 34:955-963. [PMID: 30690792 PMCID: PMC8210536 DOI: 10.1002/jbmr.3674] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 12/14/2018] [Accepted: 12/18/2018] [Indexed: 12/20/2022]
Abstract
The relationship between impaired calcium sensing, dysregulated parathyroid hormone (PTH) secretion, and parathyroid cell proliferation in parathyroid neoplasia is not understood. We previously reported that a GTPase activating protein, regulator of G-protein signaling 5 (RGS5) is overexpressed in a subset of parathyroid tumors associated with primary hyperparathyroidism (PHPT) and that RGS5 can inhibit signaling from the calcium-sensing receptor (CASR). In vivo, we found that RGS5-null mice have abnormally low PTH levels. To gain a better understanding of the potential role of RGS5 overexpression in parathyroid neoplasia and PHPT and to investigate whether inhibition of CASR signaling can lead to parathyroid neoplasia, we created and characterized a transgenic mouse strain overexpressing RGS5 specifically in the parathyroid gland. These mice develop hyperparathyroidism, bone changes reflective of elevated PTH, and parathyroid neoplasia. Further, expression of exogenous RGS5 in normal human parathyroid cells results in impaired signaling from CASR and negative feedback on PTH secretion. These results provide evidence that RGS5 can modulate signaling from CASR and support a role for RGS5 in the pathogenesis of PHPT through inhibition of CASR signaling. © 2019 American Society for Bone and Mineral Research.
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Affiliation(s)
- Nariman Balenga
- Division of General and Oncologic Surgery, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - James Koh
- Department of Surgery, University of California at San Francisco, San Francisco, CA, USA
| | - Pedram Azimzadeh
- Division of General and Oncologic Surgery, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Joyce Hogue
- Department of Surgery, University of California at San Francisco, San Francisco, CA, USA
| | - Mostafa Gabr
- Department of Surgery, University of California at San Francisco, San Francisco, CA, USA
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - John A Olson
- Division of General and Oncologic Surgery, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
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19
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Iyer SR, Shah SB, Ward CW, Stains JP, Spangenburg EE, Folker ES, Lovering RM. Differential YAP nuclear signaling in healthy and dystrophic skeletal muscle. Am J Physiol Cell Physiol 2019; 317:C48-C57. [PMID: 30995108 DOI: 10.1152/ajpcell.00432.2018] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Mechanical forces regulate muscle development, hypertrophy, and homeostasis. Force-transmitting structures allow mechanotransduction at the sarcolemma, cytoskeleton, and nuclear envelope. There is growing evidence that Yes-associated protein (YAP) serves as a nuclear relay of mechanical signals and can induce a range of downstream signaling cascades. Dystrophin is a sarcolemma-associated protein, and its absence underlies the pathology in Duchenne muscular dystrophy. We tested the hypothesis that the absence of dystrophin in muscle would result in reduced YAP signaling in response to loading. Following in vivo contractile loading in muscles of healthy (wild-type; WT) mice and mice lacking dystrophin (mdx), we performed Western blots of whole and fractionated muscle homogenates to examine the ratio of phospho (cytoplasmic) YAP to total YAP and nuclear YAP, respectively. We show that in vivo contractile loading induced a robust increase in YAP expression and its nuclear localization in WT muscles. Surprisingly, in mdx muscles, active YAP expression was constitutively elevated and unresponsive to load. Results from qRT-PCR analysis support the hyperactivation of YAP in vivo in mdx muscles, as evidenced by increased gene expression of YAP downstream targets. In vitro assays of isolated myofibers plated on substrates with high stiffness showed YAP nuclear labeling for both genotypes, indicating functional YAP signaling in mdx muscles. We conclude that while YAP signaling can occur in the absence of dystrophin, dystrophic muscles have altered mechanotransduction, whereby constitutively active YAP results in a failure to respond to load, which could be attributed to the increased state of "pre-stress" with increased cytoskeletal and extracellular matrix stiffness.
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Affiliation(s)
- Shama R Iyer
- Department of Orthopaedics, University of Maryland School of Medicine , Baltimore, Maryland
| | - Sameer B Shah
- Department of Orthopaedic Surgery, University of California San Diego , La Jolla, California.,Department of Bioengineering, University of California San Diego , La Jolla, California
| | - Christopher W Ward
- Department of Orthopaedics, University of Maryland School of Medicine , Baltimore, Maryland
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine , Baltimore, Maryland
| | - Espen E Spangenburg
- Department of Physiology, East Carolina Diabetes and Obesity Institute, East Carolina University , Greenville, North Carolina
| | - Eric S Folker
- Department of Biology, Boston College , Chestnut Hill, Massachusetts
| | - Richard M Lovering
- Department of Orthopaedics, University of Maryland School of Medicine , Baltimore, Maryland.,Department of Physiology, University of Maryland School of Medicine , Baltimore, Maryland
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20
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Long KK, O’Shea KM, Khairallah RJ, Howell K, Paushkin S, Chen KS, Cote SM, Webster MT, Stains JP, Treece E, Buckler A, Donovan A. Specific inhibition of myostatin activation is beneficial in mouse models of SMA therapy. Hum Mol Genet 2019; 28:1076-1089. [PMID: 30481286 PMCID: PMC6423420 DOI: 10.1093/hmg/ddy382] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 10/29/2018] [Accepted: 10/31/2018] [Indexed: 12/22/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a neuromuscular disease characterized by loss of α-motor neurons, leading to profound skeletal muscle atrophy. Patients also suffer from decreased bone mineral density and increased fracture risk. The majority of treatments for SMA, approved or in clinic trials, focus on addressing the underlying cause of disease, insufficient production of full-length SMN protein. While restoration of SMN has resulted in improvements in functional measures, significant deficits remain in both mice and SMA patients following treatment. Motor function in SMA patients may be additionally improved by targeting skeletal muscle to reduce atrophy and improve muscle strength. Inhibition of myostatin, a negative regulator of muscle mass, offers a promising approach to increase muscle function in SMA patients. Here we demonstrate that muSRK-015P, a monoclonal antibody which specifically inhibits myostatin activation, effectively increases muscle mass and function in two variants of the pharmacological mouse model of SMA in which pharmacologic restoration of SMN has taken place either 1 or 24 days after birth to reflect early or later therapeutic intervention. Additionally, muSRK-015P treatment improves the cortical and trabecular bone phenotypes in these mice. These data indicate that preventing myostatin activation has therapeutic potential in addressing muscle and bone deficiencies in SMA patients. An optimized variant of SRK-015P, SRK-015, is currently in clinical development for treatment of SMA.
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Affiliation(s)
| | | | | | - Kelly Howell
- SMA Foundation, 888 7th Avenue #400, New York, NY
| | | | - Karen S Chen
- SMA Foundation, 888 7th Avenue #400, New York, NY
| | - Shaun M Cote
- Scholar Rock Inc., 620 Memorial Drive, Cambridge, MA
| | | | - Joseph P Stains
- Department of Orthopedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Erin Treece
- Scholar Rock Inc., 620 Memorial Drive, Cambridge, MA
| | - Alan Buckler
- Scholar Rock Inc., 620 Memorial Drive, Cambridge, MA
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21
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Stains JP. Connexin43 Gap Junctions and the Control of Skeletal Remodeling. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.200.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Joseph P Stains
- OrthopaedicsUniversity of MarylandSchool of MedicineBaltimoreMD
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22
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Robertson AD, Chiaramonti AM, Nguyen TP, Jaffe DE, Holmes RE, Hanna EL, Rhee JG, Barfield WR, Fourney WB, Stains JP, Pellegrini VD. Failure of Indomethacin and Radiation to Prevent Blast-induced Heterotopic Ossification in a Sprague-Dawley Rat Model. Clin Orthop Relat Res 2019; 477:644-654. [PMID: 30601320 PMCID: PMC6382204 DOI: 10.1097/corr.0000000000000594] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Accepted: 11/13/2018] [Indexed: 01/31/2023]
Abstract
BACKGROUND Although use of nonsteroidal antiinflammatory drugs and low-dose irradiation has demonstrated efficacy in preventing heterotopic ossification (HO) after THA and surgical treatment of acetabular fractures, these modalities have not been assessed after traumatic blast amputations where HO is a common complication that can arise in the residual limb. QUESTIONS/PURPOSES The purpose of this study was to investigate the effectiveness of indomethacin and irradiation in preventing HO induced by high-energy blast trauma in a rat model. METHODS Thirty-six Sprague-Dawley rats underwent hind limb blast amputation with a submerged explosive under water followed by irrigation and primary wound closure. One group (n = 12) received oral indomethacin for 10 days starting on postoperative Day 1. Another group (n = 12) received a single dose of 8 Gy irradiation to the residual limb on postoperative Day 3. A control group (n = 12) did not receive either. Wound healing and clinical course were monitored in all animals until euthanasia at 24 weeks. Serial radiographs were taken immediately postoperatively, at 10 days, and every 4 weeks thereafter to monitor the time course of ectopic bone formation until euthanasia. Five independent graders evaluated the 24-week radiographs to quantitatively assess severity and qualitatively assess the pattern of HO using a modified Potter scale from 0 to 3. Assessment of grading reproducibility yielded a Fleiss statistic of 0.41 and 0.37 for severity and type, respectively. By extrapolation from human clinical trials, a minimum clinically important difference in HO severity was empirically determined to be two full grades or progression of absolute grade to the most severe. RESULTS We found no differences in mean HO severity scores among the three study groups (indomethacin 0.90 ± 0.46 [95% confidence interval {CI}, 0.60-1.19]; radiation 1.34 ± 0.59 [95% CI, 0.95-1.74]; control 0.95 ± 0.55 [95% CI, 0.60-1.30]; p = 0.100). For qualitative HO type scores, the radiation group had a higher HO type than both indomethacin and controls, but indomethacin was no different than controls (indomethacin 1.08 ± 0.66 [95% CI, 0.67-1.50]; radiation 1.89 ± 0.76 [95% CI, 1.38-2.40]; control 1.10 ± 0.62 [95% CI, 0.70-1.50]; p = 0.013). The lower bound of the 95% CI on mean severity in the indomethacin group and the upper bound of the radiation group barely spanned a full grade and involved only numeric grades < 2, suggesting that even if a small difference in severity could be detected, it would be less than our a priori-defined minimum clinically important difference and any differences that might be present are unlikely to be clinically meaningful. CONCLUSIONS This work unexpectedly demonstrated that, compared with controls, indomethacin and irradiation provide no effective prophylaxis against HO in the residual limb after high-energy blast amputation in a rat model. Such an observation is contrary to the civilian experience and may be potentially explained by either a different pathogenesis for blast-induced HO or a stimulus that overwhelms conventional regimens used to prevent HO in the civilian population. CLINICAL RELEVANCE HO in the residual limb after high-energy traumatic blast amputation will likely require novel approaches for prevention and management.
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Affiliation(s)
- Astor D Robertson
- A. D. Robertson, T. P. Nguyen, D. E. Jaffe, J. P. Stains, Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA A. M. Chiaramonti, R. E. Holmes, E. L. Hanna, W. R. Barfield, V. D. Pellegrini, Department of Orthopaedics and Physical Medicine, Medical University of South Carolina, Charleston, SC, USA J. G. Rhee, Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA W. B. Fourney, Department of Mechanical Engineering, University of Maryland, College Park, MD, USA
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Harriot A, Coleman A, Iyer SR, Venagas C, Shi G, Lovering RM, Joca HC, Stains JP, Ward CW. Increased Microtubule Density and Level of Detyrosination Occur Coincident with Sarcomere Malformations in Diseased and Aging Skeletal Muscle. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.2188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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24
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Gupta A, Leser JM, Gould NR, Buo AM, Moorer MC, Stains JP. Connexin43 regulates osteoprotegerin expression via ERK1/2 -dependent recruitment of Sp1. Biochem Biophys Res Commun 2019; 509:728-733. [PMID: 30626485 DOI: 10.1016/j.bbrc.2018.12.173] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 12/27/2018] [Indexed: 02/08/2023]
Abstract
In bone, connexin43 expression in cells of the osteoblast lineage plays an important role in restraining osteoclastogenesis and bone resorption. While there is a consensus around the notion that the anti-osteoclastogenic factor, osteoprotegerin, is a driver of this effect, how connexin43 regulates osteoprotegerin gene expression is unclear. Here, we show that loss of connexin43 decreased osteoprotegerin gene expression and reduced ERK1/2 activation. Conversely, overexpression of connexin43 increased osteoprotegerin expression and enhanced ERK1/2 activation. This increase in phospho-ERK1/2 is required for connexin43 to induce transcription from the osteoprotegerin proximal promoter. Connexin43 increased promoter activity via a specific 200 base pair region of the osteoprotegerin promoter located at -1486 to -1286 with respect to the transcriptional start site, a region which includes four Sp1 binding elements. Further, activation of this promoter region required an intact functional connexin43, as hypomorphic or dominant negative connexin43 mutant constructs, including one with increased hemichannel activity, were unable to stimulate osteoprotegerin expression as strongly as wild type connexin43. Using chromatin immunoprecipitations, we show that connexin43 expression enhanced the recruitment of Sp1, but not Runx2, to the osteoprotegerin proximal promoter. In total, these data show that connexin43-dependent gap junctional communication among osteoblast cells permits efficient ERK1/2 activation. ERK1/2 signaling promotes the recruitment of the potent transcriptional activator, Sp1, to the osteoprotegerin proximal promoter, resulting in robust transcription of anti-osteoclastogenic factor, osteoprotegerin.
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Affiliation(s)
- Aditi Gupta
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, United States.
| | - Jenna M Leser
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, United States.
| | - Nicole R Gould
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, United States.
| | - Atum M Buo
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, United States.
| | - Megan C Moorer
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, United States.
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, United States.
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Choi JY, Lai JK, Xiong ZM, Ren M, Moorer MC, Stains JP, Cao K. Diminished Canonical β-Catenin Signaling During Osteoblast Differentiation Contributes to Osteopenia in Progeria. J Bone Miner Res 2018; 33:2059-2070. [PMID: 30001457 PMCID: PMC7739562 DOI: 10.1002/jbmr.3549] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 06/25/2018] [Accepted: 06/30/2018] [Indexed: 12/31/2022]
Abstract
Patients with Hutchinson-Gilford progeria syndrome (HGPS) have low bone mass and an atypical skeletal geometry that manifests in a high risk of fractures. Using both in vitro and in vivo models of HGPS, we demonstrate that defects in the canonical WNT/β-catenin pathway, seemingly at the level of the efficiency of nuclear import of β-catenin, impair osteoblast differentiation and that restoring β-catenin activity rescues osteoblast differentiation and significantly improves bone mass. Specifically, we show that HGPS patient-derived iPSCs display defects in osteoblast differentiation, characterized by a decreased alkaline phosphatase activity and mineralizing capacity. We demonstrate that the canonical WNT/β-catenin pathway, a major signaling cascade involved in skeletal homeostasis, is impaired by progerin, causing a reduction in the active β-catenin in the nucleus and thus decreased transcriptional activity, and its reciprocal cytoplasmic accumulation. Blocking farnesylation of progerin restores active β-catenin accumulation in the nucleus, increasing signaling, and ameliorates the defective osteogenesis. Moreover, in vivo analysis of the Zmpste24-/- HGPS mouse model demonstrates that treatment with a sclerostin-neutralizing antibody (SclAb), which targets an antagonist of canonical WNT/β-catenin signaling pathway, fully rescues the low bone mass phenotype to wild-type levels. Together, this study reveals that the β-catenin signaling cascade is a therapeutic target for restoring defective skeletal microarchitecture in HGPS. © 2018 American Society for Bone and Mineral Research.
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Affiliation(s)
- Ji Young Choi
- Department of Cell Biology and Molecular Genetics, University of Maryland College Park, MD 20742
| | - Jim K Lai
- Department of Orthopedics, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Zheng-Mei Xiong
- Department of Cell Biology and Molecular Genetics, University of Maryland College Park, MD 20742
| | - Margaret Ren
- Department of Cell Biology and Molecular Genetics, University of Maryland College Park, MD 20742
| | - Megan C Moorer
- Department of Orthopedics, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Joseph P Stains
- Department of Orthopedics, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Kan Cao
- Department of Cell Biology and Molecular Genetics, University of Maryland College Park, MD 20742
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26
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Pratt SJP, Hernández-Ochoa EO, Lee RM, Ory EC, Lyons JS, Joca HC, Johnson A, Thompson K, Bailey P, Lee CJ, Mathias T, Vitolo MI, Trudeau M, Stains JP, Ward CW, Schneider MF, Martin SS. Real-time scratch assay reveals mechanisms of early calcium signaling in breast cancer cells in response to wounding. Oncotarget 2018; 9:25008-25024. [PMID: 29861849 PMCID: PMC5982755 DOI: 10.18632/oncotarget.25186] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 04/03/2018] [Indexed: 01/11/2023] Open
Abstract
Aggressive cellular phenotypes such as uncontrolled proliferation and increased migration capacity engender cellular transformation, malignancy and metastasis. While genetic mutations are undisputed drivers of cancer initiation and progression, it is increasingly accepted that external factors are also playing a major role. Two recently studied modulators of breast cancer are changes in the cellular mechanical microenvironment and alterations in calcium homeostasis. While many studies investigate these factors separately in breast cancer cells, very few do so in combination. This current work sets a foundation to explore mechano-calcium relationships driving malignant progression in breast cancer. Utilizing real-time imaging of an in vitro scratch assay, we were able to resolve mechanically-sensitive calcium signaling in human breast cancer cells. We observed rapid initiation of intracellular calcium elevations within seconds in cells at the immediate wound edge, followed by a time-dependent increase in calcium in cells at distances up to 500μm from the scratch wound. Calcium signaling to neighboring cells away from the wound edge returned to baseline within seconds. Calcium elevations at the wound edge however, persisted for up to 50 minutes. Rigorous quantification showed that extracellular calcium was necessary for persistent calcium elevation at the wound edge, but intercellular signal propagation was dependent on internal calcium stores. In addition, intercellular signaling required extracellular ATP and activation of P2Y2 receptors. Through comparison of scratch-induced signaling from multiple cell lines, we report drastic reductions in response from aggressively tumorigenic and metastatic cells. The real-time scratch assay established here provides quantitative data on the molecular mechanisms that support rapid scratch-induced calcium signaling in breast cancer cells. These mechanisms now provide a clear framework for investigating which short-term calcium signals promote long-term changes in cancer cell biology.
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Affiliation(s)
- Stephen J P Pratt
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Marlene and Stewart Greenebaum NCI Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Erick O Hernández-Ochoa
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Rachel M Lee
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Marlene and Stewart Greenebaum NCI Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Eleanor C Ory
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Marlene and Stewart Greenebaum NCI Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - James S Lyons
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Humberto C Joca
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Ashley Johnson
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Keyata Thompson
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Marlene and Stewart Greenebaum NCI Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Patrick Bailey
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Marlene and Stewart Greenebaum NCI Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Cornell J Lee
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Marlene and Stewart Greenebaum NCI Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Trevor Mathias
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Marlene and Stewart Greenebaum NCI Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Michele I Vitolo
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Marlene and Stewart Greenebaum NCI Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Matt Trudeau
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Christopher W Ward
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA.,School of Nursing, University of Maryland, Baltimore, MD, USA
| | - Martin F Schneider
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Stuart S Martin
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA.,Marlene and Stewart Greenebaum NCI Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD, USA
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Lerner M, Iyer SR, Stains JP, Henn F, Bennett CH, Lovering RM. Use of Mesenchymal Stem Cells to Treat Muscle Strain Injuries. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000538229.94153.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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28
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Lyons JS, Joca HC, Law RA, Williams KM, Kerr JP, Shi G, Khairallah RJ, Martin SS, Konstantopoulos K, Ward CW, Stains JP. Microtubules tune mechanotransduction through NOX2 and TRPV4 to decrease sclerostin abundance in osteocytes. Sci Signal 2017; 10:10/506/eaan5748. [PMID: 29162742 DOI: 10.1126/scisignal.aan5748] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The adaptation of the skeleton to its mechanical environment is orchestrated by mechanosensitive osteocytes, largely by regulating the abundance of sclerostin, a secreted inhibitor of bone formation. We defined a microtubule-dependent mechanotransduction pathway that linked fluid shear stress to reactive oxygen species (ROS) and calcium (Ca2+) signals that led to a reduction in sclerostin abundance in cultured osteocytes. We demonstrated that microtubules stabilized by detyrosination, a reversible posttranslational modification of polymerized α-tubulin, determined the stiffness of the cytoskeleton, which set the mechanoresponsive range of cultured osteocytes to fluid shear stress. We showed that fluid shear stress through the microtubule network activated NADPH oxidase 2 (NOX2)-generated ROS that target the Ca2+ channel TRPV4 to elicit Ca2+ influx. Furthermore, tuning the abundance of detyrosinated tubulin affected cytoskeletal stiffness to define the mechanoresponsive range of cultured osteocytes to fluid shear stress. Finally, we demonstrated that NOX2-ROS elicited Ca2+ signals that activated the kinase CaMKII to decrease the abundance of sclerostin protein. Together, these discoveries may identify potentially druggable targets for regulating osteocyte mechanotransduction to affect bone quality.
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Affiliation(s)
- James S Lyons
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Humberto C Joca
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Robert A Law
- Department of Chemical & Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Katrina M Williams
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Jaclyn P Kerr
- Department of Orthopaedics, University of Maryland School of Nursing, Baltimore, MD 21201, USA
| | - Guoli Shi
- Department of Orthopaedics, University of Maryland School of Nursing, Baltimore, MD 21201, USA
| | | | - Stuart S Martin
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | | | - Christopher W Ward
- Department of Orthopaedics, University of Maryland School of Nursing, Baltimore, MD 21201, USA.
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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Chiaramonti AM, Robertson AD, Nguyen TP, Jaffe DE, Hanna EL, Holmes R, Barfield WR, Fourney WL, Stains JP, Pellegrini VD. Pulsatile Lavage of Musculoskeletal Wounds Causes Muscle Necrosis and Dystrophic Calcification in a Rat Model. J Bone Joint Surg Am 2017; 99:1851-1858. [PMID: 29088040 DOI: 10.2106/jbjs.17.00330] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND Adequate irrigation of open musculoskeletal injuries is considered the standard of care to decrease bacterial load and other contaminants. While the benefit of debris removal compared with the risk of further seeding by high-pressure lavage has been studied, the effects of irrigation on muscle have been infrequently reported. Our aim in the present study was to assess relative damage to muscle by pulsatile lavage compared with bulb-syringe irrigation. METHODS In an animal model of heterotopic ossification, 24 Sprague-Dawley rats underwent hindlimb blast amputation via detonation of a submerged explosive, with subsequent through-the-knee surgical amputation proximal to the zone of injury. All wounds were irrigated and underwent primary closure. In 12 of the animals, pulsatile lavage (20 psi [138 kPa]) was used as the irrigation method, and in the other 12 animals, bulb-syringe irrigation was performed. A third group of 6 rats did not undergo the blast procedure but instead underwent surgical incision into the left thigh muscle followed by pulsatile lavage. Serial radiographs of the animals were made to monitor the formation of soft-tissue radiopaque lesions until euthanasia at 6 months. Image-guided muscle biopsies were performed at 8 weeks and 6 months (at euthanasia) on representative animals from each group. Histological analysis was performed with hematoxylin and eosin, alizarin red, and von Kossa staining on interval biopsy and postmortem specimens. RESULTS All animals managed with pulsatile lavage, with or without blast injury, developed soft-tissue radiopaque lesions, whereas no animal that had bulb-syringe irrigation developed these lesions (p = 0.001). Five of the 12 animals that underwent blast amputation with pulsatile lavage experienced wound complications, whereas no animal in the other 2 groups experienced wound complications (p = 0.014). Radiopaque lesions appeared approximately 10 days postoperatively, increased in density until approximately 16 weeks, then demonstrated signs of variable regression. Histological analysis of interval biopsy and postmortem specimens demonstrated tissue damage with inflammatory cells, cell death, and dystrophic calcification. CONCLUSIONS Pulsatile lavage of musculoskeletal wounds can cause irreversible insult to tissue, resulting in myonecrosis and dystrophic calcification. CLINICAL RELEVANCE The benefits and offsetting harm of pulsatile lavage (20 psi) should be considered before its routine use in the management of musculoskeletal wounds.
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Affiliation(s)
- Alexander M Chiaramonti
- 1Department of Orthopaedics, Medical University of South Carolina, Charleston, South Carolina 2Departments of Orthopaedics (A.D.R., T.P.N., D.E.J., and J.P.S.) and Engineering (W.L.F.), University of Maryland School of Medicine, Baltimore, Maryland
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30
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Buo AM, Tomlinson RE, Eidelman ER, Chason M, Stains JP. Connexin43 and Runx2 Interact to Affect Cortical Bone Geometry, Skeletal Development, and Osteoblast and Osteoclast Function. J Bone Miner Res 2017; 32:1727-1738. [PMID: 28419546 PMCID: PMC5550348 DOI: 10.1002/jbmr.3152] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 03/30/2017] [Accepted: 04/10/2017] [Indexed: 12/30/2022]
Abstract
The coupling of osteoblasts and osteocytes by connexin43 (Cx43) gap junctions permits the sharing of second messengers that coordinate bone cell function and cortical bone acquisition. However, details of how Cx43 converts shared second messengers into signals that converge onto essential osteogenic processes are incomplete. Here, we use in vitro and in vivo methods to show that Cx43 and Runx2 functionally interact to regulate osteoblast gene expression and proliferation, ultimately affecting cortical bone properties. Using compound hemizygous mice for the Gja1 (Cx43) and Runx2 genes, we observed a skeletal phenotype not visible in wild-type or singly hemizygous animals. Cortical bone analysis by micro-computed tomography (μCT) revealed that 8-week-old male, compound Gja1+/- Runx2+/- mice have a marked increase in cross-sectional area, endosteal and periosteal bone perimeter, and an increase in porosity compared to controls. These compound Gja1+/- Runx2+/- mice closely approximate the cortical bone phenotypes seen in osteoblast-specific Gja1-conditional knockout models. Furthermore, μCT analysis of skulls revealed an altered interparietal bone geometry in compound hemizygotes. Consistent with this finding, Alizarin red/Alcian blue staining of 2-day-old Gja1+/- Runx2+/- neonates showed a hypomorphic interparietal bone, an exacerbation of the open fontanelles, and a further reduction in the hypoplastic clavicles compared to Runx2+/- neonates. Expression of osteoblast genes, including osteocalcin, osterix, periostin, and Hsp47, was markedly reduced in tibial RNA extracts from compound hemizygous mice, and osteoblasts from compound hemizygous mice exhibited increased proliferative capacity. Further, the reduced osteocalcin expression and hyperproliferative nature of osteoblasts from Cx43 deficient mice was rescued by Runx2 expression. In summary, these findings provide evidence that Cx43 and Runx2 functionally intersect in vivo to regulate cortical bone properties and affect osteoblast differentiation and proliferation, and likely contributes to aspects of the skeletal phenotype of Cx43 conditional knockout mice. © 2017 American Society for Bone and Mineral Research.
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Affiliation(s)
- Atum M Buo
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Ryan E Tomlinson
- Department of Orthopedic Surgery, Johns Hopkins University, Baltimore, MD, USA
| | - Eric R Eidelman
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Max Chason
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA
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Abstract
PURPOSE OF THE REVIEW This review highlights recent developments into how intercellular communication through connexin43 facilitates bone modeling and remodeling. RECENT FINDINGS Connexin43 is required for both skeletal development and maintenance, particularly in cortical bone, where it carries out multiple functions, including preventing osteoclastogenesis, restraining osteoprogenitor proliferation, promoting osteoblast differentiation, coordinating organized collagen matrix deposition, and maintaining osteocyte survival. Emerging data shows that connexin43 regulates both the exchange of small molecules among osteoblast lineage cells and the docking of signaling proteins to the gap junction, affecting the efficiency of signal transduction. Understanding how and what connexin43 communicates to coordinate tissue remodeling has therapeutic implications in bone. Altering the information shared by intercellular communication and/or targeting the recruitment of signaling machinery to the gap junction could be used to impact the skeletal homeostatic set point, either driving osteogenesis or inhibiting resorption.
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Affiliation(s)
- Megan C Moorer
- Department of Orthopaedics, University of Maryland School of Medicine, 100 Penn Street, Allied Health Building, Room 540E, Baltimore, MD, 21201, USA
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, 100 Penn Street, Allied Health Building, Room 540E, Baltimore, MD, 21201, USA.
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32
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Moorer MC, Hebert C, Tomlinson RE, Iyer SR, Chason M, Stains JP. Defective signaling, osteoblastogenesis and bone remodeling in a mouse model of connexin 43 C-terminal truncation. J Cell Sci 2017; 130:531-540. [PMID: 28049723 PMCID: PMC5312734 DOI: 10.1242/jcs.197285] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 11/28/2016] [Indexed: 01/29/2023] Open
Abstract
In skeletal tissue, loss or mutation of the gap junction protein connexin 43 (Cx43, also known as GJA1) in cells of the osteoblast lineage leads to a profound cortical bone phenotype and defective tissue remodeling. There is mounting evidence in bone cells that the C-terminus (CT) of Cx43 is a docking platform for signaling effectors and is required for efficient downstream signaling. Here, we examined this function, using a mouse model of Cx43 CT-truncation (Gja1 K258Stop). Relative to Gja1+/- controls, male Gja1-/K258Stop mice have a cortical bone phenotype that is remarkably similar to those reported for deletion of the entire Cx43 gene in osteoblasts. Furthermore, we show that the Cx43 CT binds several signaling proteins that are required for optimal osteoblast function, including PKCδ, ERK1 and ERK2 (ERK1/2, also known as MAPK3 and MAPK1, respectively) and β-catenin. Deletion of the Cx43 CT domain affects these signaling cascades, impacting osteoblast proliferation, differentiation, and collagen processing and organization. These data imply that, at least in bone, Cx43 gap junctions not only exchange signals, but also recruit the appropriate effector molecules to the Cx43 CT in order to efficiently activate signaling cascades that affect cell function and bone acquisition.
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Affiliation(s)
- Megan C Moorer
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Carla Hebert
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Ryan E Tomlinson
- Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Shama R Iyer
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Max Chason
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Calabrese GM, Mesner LD, Stains JP, Tommasini SM, Horowitz MC, Rosen CJ, Farber CR. Integrating GWAS and Co-expression Network Data Identifies Bone Mineral Density Genes SPTBN1 and MARK3 and an Osteoblast Functional Module. Cell Syst 2017; 4:46-59.e4. [PMID: 27866947 PMCID: PMC5269473 DOI: 10.1016/j.cels.2016.10.014] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 08/26/2016] [Accepted: 10/18/2016] [Indexed: 02/07/2023]
Abstract
Bone mineral density (BMD) is a highly heritable predictor of osteoporotic fracture. Genome-wide association studies (GWAS) for BMD have identified dozens of associations; yet, the genes responsible for most associations remain elusive. Here, we used a bone co-expression network to predict causal genes at BMD GWAS loci based on the premise that genes underlying a disease are often functionally related and functionally related genes are often co-expressed. By mapping genes implicated by BMD GWAS onto a bone co-expression network, we predicted and inferred the function of causal genes for 30 of 64 GWAS loci. We experimentally confirmed that two of the genes predicted to be causal, SPTBN1 and MARK3, are potentially responsible for the effects of GWAS loci on chromosomes 2p16.2 and 14q32.32, respectively. This approach provides a roadmap for the dissection of additional BMD GWAS associations. Furthermore, it should be applicable to GWAS data for a wide range of diseases.
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Affiliation(s)
- Gina M Calabrese
- Center for Public Health Genomics, University of Virginia, Charlottesville, VA 22908, USA
| | - Larry D Mesner
- Center for Public Health Genomics, University of Virginia, Charlottesville, VA 22908, USA
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Steven M Tommasini
- Department of Orthopaedics and Rehabilitation, Yale School of Medicine, New Haven, CT 06520-8071, USA
| | - Mark C Horowitz
- Department of Orthopaedics and Rehabilitation, Yale School of Medicine, New Haven, CT 06520-8071, USA
| | - Clifford J Rosen
- Maine Medical Center Research Institute, 81 Research Drive, Scarborough, ME 04074, USA
| | - Charles R Farber
- Center for Public Health Genomics, University of Virginia, Charlottesville, VA 22908, USA; Departments of Public Health Sciences and Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA.
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Iyer SR, Xu S, Stains JP, Bennett CH, Lovering RM. Superparamagnetic Iron Oxide Nanoparticles in Musculoskeletal Biology. Tissue Eng Part B Rev 2017; 23:373-385. [PMID: 27998240 DOI: 10.1089/ten.teb.2016.0437] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The use of platelet-rich plasma and mesenchymal stem cells has garnered much attention in orthopedic medicine, focusing on the biological aspects of cell function. However, shortly after systemic delivery, or even a local injection, few of the transplanted stem cells or platelets remain at the target site. Improvement in delivery, and the ability to track and monitor injected cells, would greatly improve clinical translation. Nanoparticles can effectively and quickly label most cells in vitro, and evidence to date suggests such labeling does not compromise the proliferation or differentiation of cells. A specific type of nanoparticle, the superparamagnetic iron oxide nanoparticle (SPION), is already employed as a magnetic resonance imaging (MRI) contrast agent. SPIONs can be coupled with cells or bioactive molecules (antibodies, proteins, drugs, etc.) to form an injectable complex for in vivo use. The biocompatibility, magnetic properties, small size, and custom-made surface coatings also enable SPIONs to be used for delivering and monitoring of small molecules, drugs, and cells, specifically to muscle, bone, or cartilage. Because SPIONs consist of cores made of iron oxides, targeting of SPIONs to a specific muscle, bone, or joint in the body can be enhanced with the help of applied gradient magnetic fields. Moreover, MRI has a high sensitivity to SPIONs and can be used for noninvasive determination of successful delivery and monitoring distribution in vivo. Gaps remain in understanding how the physical and chemical properties of nanomaterials affect biological systems. Nonetheless, SPIONs hold great promise for regenerative medicine, and progress is being made rapidly toward clinical applications in orthopedic medicine.
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Affiliation(s)
- Shama R Iyer
- 1 Department of Orthopaedics, University of Maryland School of Medicine , Baltimore, Maryland
| | - Su Xu
- 2 Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine , Baltimore, Maryland
| | - Joseph P Stains
- 1 Department of Orthopaedics, University of Maryland School of Medicine , Baltimore, Maryland
| | - Craig H Bennett
- 1 Department of Orthopaedics, University of Maryland School of Medicine , Baltimore, Maryland
| | - Richard M Lovering
- 1 Department of Orthopaedics, University of Maryland School of Medicine , Baltimore, Maryland.,3 Department of Physiology, University of Maryland School of Medicine , Baltimore, Maryland
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Iyer SR, Shah SB, Valencia AP, Schneider MF, Hernández-Ochoa EO, Stains JP, Blemker SS, Lovering RM. Altered nuclear dynamics in MDX myofibers. J Appl Physiol (1985) 2016; 122:470-481. [PMID: 27979987 DOI: 10.1152/japplphysiol.00857.2016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 12/02/2016] [Accepted: 12/06/2016] [Indexed: 01/17/2023] Open
Abstract
Duchenne muscular dystrophy (DMD) is a genetic disorder in which the absence of dystrophin leads to progressive muscle degeneration and weakness. Although the genetic basis is known, the pathophysiology of dystrophic skeletal muscle remains unclear. We examined nuclear movement in wild-type (WT) and muscular dystrophy mouse model for DMD (MDX) (dystrophin-null) mouse myofibers. We also examined expression of proteins in the linkers of nucleoskeleton and cytoskeleton (LINC) complex, as well as nuclear transcriptional activity via histone H3 acetylation and polyadenylate-binding nuclear protein-1. Because movement of nuclei is not only LINC dependent but also microtubule dependent, we analyzed microtubule density and organization in WT and MDX myofibers, including the application of a unique 3D tool to assess microtubule core structure. Nuclei in MDX myofibers were more mobile than in WT myofibers for both distance traveled and velocity. MDX muscle shows reduced expression and labeling intensity of nesprin-1, a LINC protein that attaches the nucleus to the microtubule and actin cytoskeleton. MDX nuclei also showed altered transcriptional activity. Previous studies established that microtubule structure at the cortex is disrupted in MDX myofibers; our analyses extend these findings by showing that microtubule structure in the core is also disrupted. In addition, we studied malformed MDX myofibers to better understand the role of altered myofiber morphology vs. microtubule architecture in the underlying susceptibility to injury seen in dystrophic muscles. We incorporated morphological and microtubule architectural concepts into a simplified finite element mathematical model of myofiber mechanics, which suggests a greater contribution of myofiber morphology than microtubule structure to muscle biomechanical performance.NEW & NOTEWORTHY Microtubules provide the means for nuclear movement but show altered organization in the muscular dystrophy mouse model (MDX) (dystrophin-null) muscle. Here, MDX myofibers show increased nuclear movement, altered transcriptional activity, and altered linkers of nucleoskeleton and cytoskeleton complex expression compared with healthy myofibers. Microtubule architecture was incorporated in finite element modeling of passive stretch, revealing a role of fiber malformation, commonly found in MDX muscle. The results suggest that alterations in microtubule architecture in MDX muscle affect nuclear movement, which is essential for muscle function.
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Affiliation(s)
- Shama R Iyer
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland
| | - Sameer B Shah
- Departments of Orthopaedic Surgery and Bioengineering, University of California San Diego, La Jolla, California
| | - Ana P Valencia
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland
| | - Martin F Schneider
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Erick O Hernández-Ochoa
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland
| | - Silvia S Blemker
- Department of Biomedical Engineering and Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia; and
| | - Richard M Lovering
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland; .,Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
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Lyons JS, Iyer SR, Lovering RM, Ward CW, Stains JP. Novel multi-functional fluid flow device for studying cellular mechanotransduction. J Biomech 2016; 49:4173-4179. [PMID: 27887728 DOI: 10.1016/j.jbiomech.2016.11.051] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 11/09/2016] [Accepted: 11/12/2016] [Indexed: 11/15/2022]
Abstract
Cells respond to their mechanical environment by initiating multiple mechanotransduction signaling pathways. Defects in mechanotransduction have been implicated in a number of pathologies; thus, there is need for convenient and efficient methods for studying the mechanisms underlying these processes. A widely used and accepted technique for mechanically stimulating cells in culture is the introduction of fluid flow on cell monolayers. Here, we describe a novel, multifunctional fluid flow device for exposing cells to fluid flow in culture. This device integrates with common lab equipment including routine cell culture plates and peristaltic pumps. Further, it allows the fluid flow treated cells to be examined with outcomes at the cell and molecular level. We validated the device using the biologic response of cultured UMR-106 osteoblast-like cells in comparison to a commercially available system of laminar sheer stress to track live cell calcium influx in response to fluid flow. In addition, we demonstrate the fluid flow-dependent activation of phospho-ERK in these cells, consistent with the findings in other fluid flow devices. This device provides a low cost, multi-functional alternative to currently available systems, while still providing the ability to generate physiologically relevant conditions for studying processes involved in mechanotransduction in vitro.
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Affiliation(s)
- James S Lyons
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Shama R Iyer
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Richard M Lovering
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | | | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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Moorer MC, Buo AM, Garcia-Pelagio KP, Stains JP, Bloch RJ. Deficiency of the intermediate filament synemin reduces bone mass in vivo. Am J Physiol Cell Physiol 2016; 311:C839-C845. [PMID: 27605453 DOI: 10.1152/ajpcell.00218.2016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 09/06/2016] [Indexed: 12/31/2022]
Abstract
While the type IV intermediate filament protein, synemin, has been shown to play a role in striated muscle and neuronal tissue, its presence and function have not been described in skeletal tissue. Here, we report that genetic ablation of synemin in 14-wk-old male mice results in osteopenia that includes a more than 2-fold reduction in the trabecular bone fraction in the distal femur and a reduction in the cross-sectional area at the femoral middiaphysis due to an attendant reduction in both the periosteal and endosteal perimeter. Analysis of serum markers of bone formation and static histomorphometry revealed a statistically significant defect in osteoblast activity and osteoblast number in vivo. Interestingly, primary osteoblasts isolated from synemin-null mice demonstrate markedly enhanced osteogenic capacity with a concomitant reduction in cyclin D1 mRNA expression, which may explain the loss of osteoblast number observed in vivo. In total, these data suggest an important, previously unknown role for synemin in bone physiology.
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Affiliation(s)
- Megan C Moorer
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland; and
| | - Atum M Buo
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland; and
| | - Karla P Garcia-Pelagio
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland; and
| | - Robert J Bloch
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
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Gupta A, Anderson H, Buo AM, Moorer MC, Ren M, Stains JP. Communication of cAMP by connexin43 gap junctions regulates osteoblast signaling and gene expression. Cell Signal 2016; 28:1048-57. [PMID: 27156839 DOI: 10.1016/j.cellsig.2016.04.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 04/15/2016] [Accepted: 04/28/2016] [Indexed: 11/30/2022]
Abstract
Connexin43 (Cx43) containing gap junctions play an important role in bone homeostasis, yet little is known about the second messengers communicated by Cx43 among bone cells. Here, we used MC3T3-E1 pre-osteoblasts and UMR106 rat osteosarcoma cells to test the hypothesis that cAMP is a second messenger communicated by bone cells through Cx43 containing gap junctions in a manner that is sufficient to impact osteoblast function. Overexpression of Cx43 markedly enhanced the activity of a cAMP-response element driven transcriptional luciferase reporter (CRE-luc) and increased phospho-CREB and phospho-ERK1/2 levels following expression of a constitutively active Gsα or by treatment with prostaglandin E2 (PGE2), 3-Isobutyl-1-methyl xanthine (IBMX) or forskolin. The Cx43-dependent potentiation of signaling in PGE2 treated cells was not accompanied by a further increase in cAMP levels, suggesting that the cAMP was shared between cells rather than Cx43 enhancing cAMP production. To support this, we developed a novel assay in which one set of cells expressing constitutively active Gsα (donor cells) were co-cultured with a second set of cells expressing a CRE-luc reporter (acceptor cells). Using this assay, activation of a CRE-luc reporter in the acceptor cells was both Cx43- and cell contact-dependent, indicating communication of cAMP among cells. Finally, we showed that Cx43 increased the cAMP-dependent mRNA expression of receptor activator of nuclear factor kappa B ligand (RANKL) and enhanced the repression of the sclerostin mRNA, implying a potential mechanism for the modulation of tissue remodeling. In total, these data demonstrate that Cx43 can communicate cAMP between cells and, more importantly, that the communicated cAMP is sufficient to impact signal transduction cascades and the expression of key bone effector molecules between interconnected cells.
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Affiliation(s)
- Aditi Gupta
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Hidayah Anderson
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Atum M Buo
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Megan C Moorer
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Margaret Ren
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA.
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Iyer S, Gupta A, Valencia AP, Stains JP, Lovering RM. Eccentric Contractions Promote Osteoclast Activity in the Tibia. Med Sci Sports Exerc 2016. [DOI: 10.1249/01.mss.0000485929.66262.ea] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
Shaping of the skeleton (modeling) and its maintenance throughout life (remodeling) require coordinated activity among bone forming (osteoblasts) and resorbing cells (osteoclasts) and osteocytes (bone embedded cells). The gap junction protein connexin43 (Cx43) has emerged as a key modulator of skeletal growth and homeostasis. The skeletal developmental abnormalities present in oculodentodigital and craniometaphyseal dysplasias, both linked to Cx43 gene (GJA1) mutations, demonstrate that the skeleton is a major site of Cx43 action. Via direct action on osteolineage cells, including altering production of pro-osteoclastogenic factors, Cx43 contributes to peak bone mass acquisition, cortical modeling of long bones, and maintenance of bone quality. Cx43 also contributes in diverse ways to bone responsiveness to hormonal and mechanical signals. Skeletal biology research has revealed the complexity of Cx43 function; in addition to forming gap junctions and "hemichannels", Cx43 provides a scaffold for signaling molecules. Hence, Cx43 actively participates in generation and modulation of cellular signals driving skeletal development and homeostasis. Pharmacological interference with Cx43 may in the future help remedy deterioration of bone quality occurring with aging, disuse and hormonal imbalances.
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Affiliation(s)
- Joseph P Stains
- Department of Orthopaedics, University of Maryland, School of Medicine, Baltimore, MD, United States
| | - Roberto Civitelli
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University in St. Louis, Campus Box 8301, 425 South Euclid, St. Louis, MO 63110, United States.
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Stains JP, Civitelli R. A Functional Assay to Assess Connexin 43-Mediated Cell-to-Cell Communication of Second Messengers in Cultured Bone Cells. Methods Mol Biol 2016; 1437:193-201. [PMID: 27207296 PMCID: PMC4959905 DOI: 10.1007/978-1-4939-3664-9_14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Cell-to-cell transfer of small molecules is a fundamental way by which multicellular organisms coordinate function. Recent work has highlighted the complexity of biologic responses downstream of gap junctions. As the connexin-regulated effectors are coming into focus, there is a need to develop functional assays that allow specific testing of biologically relevant second messengers. Here, we describe a modification of the classic gap junction parachute assay to assess biologically relevant molecules passed through gap junctions.
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Affiliation(s)
- Joseph P. Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Roberto Civitelli
- Department of Medicine, Division of Bone and Mineral Diseases, Washington University, St Louis, MO, USA
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Casagrande D, Stains JP, Murthi AM. Identification of shoulder osteoarthritis biomarkers: comparison between shoulders with and without osteoarthritis. J Shoulder Elbow Surg 2015; 24:382-90. [PMID: 25595362 PMCID: PMC4331258 DOI: 10.1016/j.jse.2014.11.039] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 11/12/2014] [Accepted: 11/15/2014] [Indexed: 02/01/2023]
Abstract
BACKGROUND The biologic factors associated with shoulder osteoarthritis (OA) have not been elucidated. The purpose of this study was to investigate osteoarthritic biomarkers of the shoulder. To our knowledge, this is the first study to analyze shoulder cartilage for OA-associated genes and to examine human shoulder cartilage for a possible biomarker, connexin 43 (Cx43). MATERIALS AND METHODS Cartilage from 16 osteoarthritic and 10 nonosteoarthritic humeral heads was assessed for expression of the following genes by real-time polymerase chain reaction: types I, II, and X collagen; matrix metalloproteinases (MMPs); tissue inhibitors of MMP (TIMPs); interleukins; versican; cyclooxygenase 2 (Cox-2); inducible nitric oxide synthase (iNOS); tumor necrosis factor α (TNF-α); aggrecanase 2 (ADAMTS5); and Cx43. RESULTS In osteoarthritic shoulders, Cx43, Cox-2, versican, collagen type I, ADAMTS5, MMP-3, and TNF-α expressions were significantly increased compared with controls. TIMP-3 and iNOS trended toward significance, with robust expression in osteoarthritic shoulders and low expression in nonosteoarthritic shoulders. In osteoarthritic shoulders, gene expression of Cx43, ADAMTS5, collagen type I, Cox-2, versican, and TIMP-3 showed predominance (85-, 33-, 13-, 12-, 11.5-, and 3-fold increases, respectively) relative to nonosteoarthritic controls. Spearman correlation analysis showed significant correlations between Cx43 and collagen (types I, II, and X), MMP-9, TIMP-2 and TIMP-3, versican, Cox-2, iNOS, and ADAMTS5. CONCLUSIONS Certain genes are markedly upregulated in osteoarthritic shoulders compared with nonosteoarthritic shoulders, with Cx43, Cox-2, versican, collagen type I, ADAMTS5, MMP-3, and TNF-α expression being significantly increased. These genes might be useful biomarkers for examining shoulder OA. CLINICAL RELEVANCE Identification of osteoarthritic biomarkers can help us better understand shoulder OA and build the foundation for future research on disease progression and treatments.
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43
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Lindberg I, Pang HW, Stains JP, Clark D, Yang AJ, Bonewald L, Li KZ. FGF23 is endogenously phosphorylated in bone cells. J Bone Miner Res 2015; 30:449-54. [PMID: 25195776 PMCID: PMC4750499 DOI: 10.1002/jbmr.2354] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 08/28/2014] [Accepted: 09/03/2014] [Indexed: 01/22/2023]
Abstract
Levels of serum phosphate are controlled by the peptide hormone FGF23, secreted from bone osteocytes. Elevated levels of circulating FGF23 are a key factor in several hypophosphatemic disorders and play a role in chronic kidney disease. Posttranslational processing of FGF23 includes multi-site O-glycosylation, which reduces intracellular cleavage by proprotein convertases. The FGF23 protein also contains four serine phosphorylation consensus sequences (S-X-D/E); in this work, we asked whether FGF23 is a substrate for secretory phosphorylation. Both HEK cells as well as IDG-SW3 cells, an osteocyte model, incorporated radiolabeled orthophosphate into intact FGF23, as well as into the 14-kDa carboxy-terminal-but not the 17-kDa N-terminal-fragment. Sequential serine-to-alanine site-directed mutagenesis of four kinase consensus sites showed that labeling occurred on three serines within the carboxy-terminal fragment, Ser180 (adjacent to the cleavage site), Ser207, and Ser212. Liquid chromatography-coupled mass spectroscopy indicated the presence of phosphate at Ser212 in recombinant R&D mouse FGF23(R179Q) , confirming labeling results. A phosphopeptide-specific antibody was raised against phospho-Ser212 and exhibited immunoreactivity in osteocytes present in mouse long bone, providing further evidence that FGF23 is naturally phosphorylated in bone. Bone SIBLING proteins are serine-phosphorylated by the ubiquitous Golgi secretory kinase FAM20C. Cotransfection of HEK and MC3T3 cells with FGF23 and active, but not inactive, FAM20C kinase increased the storage and release of FGF23 in radiolabeling experiments, indicating potential effects of phosphorylation on FGF23 stability. Collectively, these data point to an important role for phosphorylation of FGF23 in bone.
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Affiliation(s)
- Iris Lindberg
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
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Pratt SJP, Shah SB, Ward CW, Kerr JP, Stains JP, Lovering RM. Recovery of altered neuromuscular junction morphology and muscle function in mdx mice after injury. Cell Mol Life Sci 2014; 72:153-64. [PMID: 24947322 PMCID: PMC4282693 DOI: 10.1007/s00018-014-1663-7] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 05/14/2014] [Accepted: 06/02/2014] [Indexed: 12/02/2022]
Abstract
Duchenne muscular dystrophy (DMD) is a devastating neuromuscular disease in which weakness, increased susceptibility to muscle injury, and inadequate repair underlie the pathology. While most attention has focused within the muscle fiber, we recently demonstrated significant alterations in the neuromuscular junction (NMJ) morphology and resulting neuromuscular transmission failure (NTF) 24 h after injury in mdx mice (murine model for DMD). Here we determine the contribution of NMJ morphology and NTF to the recovery of muscle contractile function post-injury. NMJ morphology and NTF rates were assessed day 0 (immediately after injury) and days 1, 7, 14 and 21 after quadriceps injury. Eccentric injury of the quadriceps resulted in a significant loss of maximal torque in both WT (39 ± 6 %) and mdx (76 ± 8 %) with a full recovery in WT by day 7 and in mdx by day 21. Post-injury alterations in NMJ morphology and NTF were found only in mdx, were limited to days 0 and 1, and were independent of changes in MuSK or AChR expression. Such early changes at the NMJ after injury are consistent with mechanical disruption rather than newly forming NMJs. Furthermore, we show that the dense microtubule network that underlies the NMJ is significantly reduced and disorganized in mdx compared to WT. These structural changes at the NMJ may play a role in the increased NMJ disruption and the exaggerated loss of nerve-evoked muscle force seen after injury to dystrophic muscles.
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Affiliation(s)
- Stephen J. P. Pratt
- Department of Orthopaedics, University of Maryland School of Medicine, 100 Penn St. AHB, Room 540, Baltimore, MD 21201 USA
| | - Sameer B. Shah
- Department of Orthopaedic Surgery and Bioengineering, University of California, San Diego, USA
| | | | - Jaclyn P. Kerr
- Department of Physiology, University of Maryland School of Medicine, Baltimore, USA
| | - Joseph P. Stains
- Department of Orthopaedics, University of Maryland School of Medicine, 100 Penn St. AHB, Room 540, Baltimore, MD 21201 USA
| | - Richard M. Lovering
- Department of Orthopaedics, University of Maryland School of Medicine, 100 Penn St. AHB, Room 540, Baltimore, MD 21201 USA
- Department of Physiology, University of Maryland School of Medicine, Baltimore, USA
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Pratt SJP, Shah SB, Ward CW, Stains JP, Lovering RM. Recovery of Altered Neuromuscular Junction Morphology and Muscle Function in Mdx Mice. Med Sci Sports Exerc 2014. [DOI: 10.1249/01.mss.0000494229.92793.06] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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46
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Hebert C, Stains JP. An intact connexin43 is required to enhance signaling and gene expression in osteoblast-like cells. J Cell Biochem 2014; 114:2542-50. [PMID: 23744706 DOI: 10.1002/jcb.24603] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 05/16/2013] [Indexed: 11/09/2022]
Abstract
The cytoplasmic C-terminus of connexin43 (Cx43) interacts with numerous signaling complexes. We hypothesize that signal complex docking to the Cx43 C-terminus (CT) is required to propagate the molecules being shared by gap junctions. We have previously shown that Cx43 impacts the responsiveness of osteoblasts to FGF2 in a PKCδ- and ERK-dependent manner, converging on Runx2 activity. Here, we mapped the interaction domain of Cx43 and PKCδ to amino acids 243-302 of the Cx43 CT by GST pulldown assay. Using Runx2-responsive luciferase reporter assays, a Cx43 deletion construct (Cx43 S244Stop), which lacks the C-terminus (amino acids 244-382), failed to support the Cx43-dependent potentiation of transcription following FGF2 treatment in MC3T3 osteoblast-like cells. Similarly, overexpression of Cx43 S244Stop could not mimic the ability of the full length Cx43 to stimulate expression of osteoblast genes. In contrast to full length Cx43, overexpression of just the Cx43 CT (amino acids 236-382) inhibited both transcription from a Runx2 reporter and signaling via PKCδ and ERK. Inhibition of signaling by the CT did not occur in HeLa cells, which lack endogenous Cx43. In summary, the data support a model in which an intact Cx43 is required for both signal propagation/permeability (i.e., channel function) and local recruitment of signaling complexes to the CT (i.e., docking function) in order to mediate its cellular effects. Further, while the CT alone has channel independent activity, it is opposing to the effect of overexpression of the full length Cx43 channel in this cell context.
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Affiliation(s)
- Carla Hebert
- Department of Orthopedics, University of Maryland, School of Medicine, Baltimore, Maryland, 21201
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Buo AM, Stains JP. Gap junctional regulation of signal transduction in bone cells. FEBS Lett 2014; 588:1315-21. [PMID: 24486014 DOI: 10.1016/j.febslet.2014.01.025] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2013] [Revised: 01/17/2014] [Accepted: 01/20/2014] [Indexed: 11/30/2022]
Abstract
The role of gap junctions, particularly that of connexin43 (Cx43), has become an area of increasing interest in bone physiology. An abundance of studies have shown that Cx43 influences the function of osteoblasts and osteocytes, which ultimately impacts bone mass acquisition and skeletal homeostasis. However, the molecular details underlying how Cx43 regulates bone are only coming into focus and have proven to be more complex than originally thought. In this review, we focus on the diverse molecular mechanisms by which Cx43 gap junctions and hemichannels regulate cell signaling pathways, gene expression, mechanotransduction and cell survival in bone cells. This review will highlight key signaling factors that have been identified as downstream effectors of Cx43 and the impact of these pathways on distinct osteoblast and osteocyte functions.
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Affiliation(s)
- Atum M Buo
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, USA.
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Stains JP, Watkins MP, Grimston SK, Hebert C, Civitelli R. Molecular mechanisms of osteoblast/osteocyte regulation by connexin43. Calcif Tissue Int 2014; 94:55-67. [PMID: 23754488 PMCID: PMC3815501 DOI: 10.1007/s00223-013-9742-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 04/23/2013] [Indexed: 01/23/2023]
Abstract
Osteoblasts, osteocytes, and osteoprogenitor cells are interconnected into a functional network by gap junctions formed primarily by connexin43 (Cx43). Over the past two decades, it has become clear that Cx43 is important for the function of osteoblasts and osteocytes. This connexin contributes to the acquisition of peak bone mass and is a major modulator of cortical modeling. We review key data from human and mouse genetics on the skeletal consequences of ablation or mutation of the Cx43 gene (Gja1) and the molecular mechanisms by which Cx43 regulates the differentiation, function, and survival of osteogenic lineage cells. We also discuss putative second messengers that are communicated by Cx43 gap junctions, the role of hemichannels, and the function of Cx43 as a scaffold for signaling molecules. Current knowledge demonstrates that Cx43 is more than a passive channel; rather, it actively participates in the generation and modulation of cellular signals that drive skeletal development and homeostasis.
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Affiliation(s)
- Joseph P Stains
- Department of Orthopaedics, University of Maryland, School of Medicine, 100 Penn Street, Allied Health Building, Room 540E, Baltimore, MD, 21201, USA,
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Nanjundaiah SM, Stains JP, Moudgil KD. Kinetics and interplay of mediators of inflammation-induced bone damage in the course of adjuvant arthritis. Int J Immunopathol Pharmacol 2013; 26:37-48. [PMID: 23527707 DOI: 10.1177/039463201302600104] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation, bone erosion, and cartilage destruction in the joints. It is increasingly being realized that inflammation might play an important role in inducing bone damage in arthritis. However, there is limited validation of this concept in vivo in well-controlled experimental conditions. We addressed this issue using the adjuvant arthritis (AA) model of RA. In AA, the draining lymph nodes are the main sites of activation of pathogenic leukocytes, which then migrate into the joints leading to the induction of arthritis. We tested the temporal kinetics of mediators of bone damage [e.g., receptor activator of nuclear factor kappa-B ligand (RANKL), osteoprotegerin (OPG) and osteopontin (OPN)] and inflammation (pro-inflammatory cytokines and chemokines) in the draining lymph node cells (LNC) at different phases of AA, and then examined their inter-relationships. Our study revealed that, together with cytokines/chemokines, some of the mediators of bone remodeling are also produced in LNC. Various cytokines/chemokines showed distinct kinetics of expression as well as patterns of correlation with mediators of bone remodeling at different phases of the disease. Pro-inflammatory cytokines such as TNF-alpha are known to play an important role in bone damage. Interestingly, there was a positive correlation between TNF-alpha and RANKL, between RANKL and each of the 3 chemokines tested (RANTES, MIP-1alpha, and GRO/KC), and between TNF-alpha and RANTES. Our results in the AA model lend support to the concept of osteo-immune crosstalk during the course of autoimmune arthritis.
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Affiliation(s)
- S M Nanjundaiah
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
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Niger C, Luciotti MA, Buo AM, Hebert C, Ma V, Stains JP. The regulation of runt-related transcription factor 2 by fibroblast growth factor-2 and connexin43 requires the inositol polyphosphate/protein kinase Cδ cascade. J Bone Miner Res 2013; 28:1468-77. [PMID: 23322705 PMCID: PMC3657330 DOI: 10.1002/jbmr.1867] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 12/07/2012] [Accepted: 12/31/2012] [Indexed: 11/11/2022]
Abstract
Connexin43 (Cx43) plays a critical role in osteoblast function and bone mass accrual, yet the identity of the second messengers communicated by Cx43 gap junctions, the targets of these second messengers and how they regulate osteoblast function remain largely unknown. We have shown that alterations of Cx43 expression in osteoblasts can impact the responsiveness to fibroblast growth factor-2 (FGF2), by modulating the transcriptional activity of runt-related transcription factor 2 (Runx2). In this study, we examined the contribution of the phospholipase Cγ1/inositol polyphosphate/protein kinase C delta (PKCδ) cascade to the Cx43-dependent transcriptional response of MC3T3 osteoblasts to FGF2. Knockdown of expression and/or inhibition of function of phospholipase Cγ1, inositol polyphosphate multikinase, which generates inositol 1,3,4,5-tetrakisphosphate (InsP₄) and InsP₅, and inositol hexakisphosphate kinase 1/2, which generates inositol pyrophosphates, prevented the ability of Cx43 to potentiate FGF2-induced signaling through Runx2. Conversely, overexpression of phospholipase Cγ1 and inositol hexakisphosphate kinase 1/2 enhanced FGF2 activation of Runx2 and the effect of Cx43 overexpression on this response. Disruption of these pathways blocked the nuclear accumulation of PKCδ and the FGF2-dependent interaction of PKCδ and Runx2, reducing Runx2 transcriptional activity. These data reveal that FGF2-signaling involves the inositol polyphosphate cascade, including inositol hexakisphosphate kinase (IP6K), and demonstrate that IP6K regulates Runx2 and osteoblast gene expression. Additionally, these data implicate the water-soluble inositol polyphosphates as mediators of the Cx43-dependent amplification of the osteoblast response to FGF2, and suggest that these low molecular weight second messengers may be biologically relevant mediators of osteoblast function that are communicated by Cx43-gap junctions.
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Affiliation(s)
- Corinne Niger
- Department of Orthopaedics, University of Maryland, School of Medicine, Baltimore, MD, USA
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