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Kulkarni S, Saha M, Slosberg J, Singh A, Nagaraj S, Becker L, Zhang C, Bukowski A, Wang Z, Liu G, Leser JM, Kumar M, Bakhshi S, Anderson MJ, Lewandoski M, Vincent E, Goff LA, Pasricha PJ. Age-associated changes in lineage composition of the enteric nervous system regulate gut health and disease. eLife 2023; 12:RP88051. [PMID: 38108810 PMCID: PMC10727506 DOI: 10.7554/elife.88051] [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] [Indexed: 12/19/2023] Open
Abstract
The enteric nervous system (ENS), a collection of neural cells contained in the wall of the gut, is of fundamental importance to gastrointestinal and systemic health. According to the prevailing paradigm, the ENS arises from progenitor cells migrating from the neural crest and remains largely unchanged thereafter. Here, we show that the lineage composition of maturing ENS changes with time, with a decline in the canonical lineage of neural-crest derived neurons and their replacement by a newly identified lineage of mesoderm-derived neurons. Single cell transcriptomics and immunochemical approaches establish a distinct expression profile of mesoderm-derived neurons. The dynamic balance between the proportions of neurons from these two different lineages in the post-natal gut is dependent on the availability of their respective trophic signals, GDNF-RET and HGF-MET. With increasing age, the mesoderm-derived neurons become the dominant form of neurons in the ENS, a change associated with significant functional effects on intestinal motility which can be reversed by GDNF supplementation. Transcriptomic analyses of human gut tissues show reduced GDNF-RET signaling in patients with intestinal dysmotility which is associated with reduction in neural crest-derived neuronal markers and concomitant increase in transcriptional patterns specific to mesoderm-derived neurons. Normal intestinal function in the adult gastrointestinal tract therefore appears to require an optimal balance between these two distinct lineages within the ENS.
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Affiliation(s)
- Subhash Kulkarni
- Division of Gastroenterology, Dept of Medicine, Beth Israel Deaconess Medical CenterBostonUnited States
- Division of Medical Sciences, Harvard Medical SchoolBostonUnited States
| | - Monalee Saha
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Jared Slosberg
- Department of Genetic Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Alpana Singh
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Sushma Nagaraj
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Laren Becker
- Division of Gastroenterology, Stanford University – School of MedicineStanfordUnited States
| | - Chengxiu Zhang
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Alicia Bukowski
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Zhuolun Wang
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Guosheng Liu
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Jenna M Leser
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Mithra Kumar
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Shriya Bakhshi
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Matthew J Anderson
- Center for Cancer Research, National Cancer InstituteFrederickUnited States
| | - Mark Lewandoski
- Center for Cancer Research, National Cancer InstituteFrederickUnited States
| | - Elizabeth Vincent
- Department of Genetic Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Loyal A Goff
- Department of Neuroscience, Johns Hopkins University – School of MedicineBaltimoreUnited States
- Kavli Neurodiscovery Institute, Johns Hopkins University – School of MedicineBaltimoreUnited States
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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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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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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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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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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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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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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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