Mechanical loading disrupts osteocyte plasma membranes which initiates mechanosensation events in bone

Yu, Kanglun; Sellman, David P.; Bahraini, Anoosh; Hagan, Mackenzie L.; Elsherbini, Ahmed; Vanpelt, Kayce T.; Marshall, Peyton L.; Hamrick, Mark W.; McNeil, Anna K.; McNeil, Paul L.; McGee‐Lawrence, Meghan E.

doi:10.1002/jor.23665

Cited by 38 publications

(64 citation statements)

References 49 publications

(123 reference statements)

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“…ATP has been shown to act as a primary signaling molecule directing cell to cell TPMD-induced calcium waves in osteocytes 7 . It was recently reported that the production and release of extracellular vesicles rich in ATP is facilitated by intracellular calcium release in osteocytes 32 .…”

Section: Discussionmentioning

confidence: 99%

Transient Cell Membrane Disruptions induce Calcium Waves in Corneal Keratocytes

Chen

McGee‐Lawrence

et al. 2020

Sci Rep

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the purpose of this study was to determine if transient cell membrane disruptions (tpMDs) in single keratocytes can trigger signaling events in neighboring keratocytes. Stromal cells were cultured from human corneas (HcSc) and mouse corneas (McSc). tpMDs were produced using a multiphoton microscope in Cal-520-AM loaded cells. TPMD-induced calcium increases (Ca ++ i ) were measured in ca ++containing and ca ++ -free solutions containing thapsigargin, ryanodine, BAPTA-AM, 18-α-glycyrrhetinic acid (18α-GA), apyrase, BCTC, AMG 9810, or AMTB. Fluorescence intensity was recorded as the number of cells responding and the area under the fluorescence versus time curve. The maximum distance of responding neighboring cells in ex vivo human corneas was measured. Connexin 43 protein in HCSC and MCSC was examined using immunofluorescence staining, and corneal rubbing was applied to confirm whether TPMDs occur following mechanical manipulation. Our results demonstrate that single cell tpMDs result in ca ++ waves in neighboring keratocytes both in culture and within ex vivo corneas. the source of ca ++ is both intra-and extra-cellular, and the signal can be mediated by ATP and/or gap junctions, and is species dependent. Stromal rubbing confirmed that TPMDs do occur following mechanical manipulation. Keratocyte tpMDs and their associated signaling events are likely common occurrences following minor or major corneal trauma.The cornea is the anterior-most segment of the eye, and is the most powerful refractive element of the eye. Histologically, the cornea contains an outwardly-facing epithelium, a stroma containing keratocytes and nerves, and in inner-facing endothelium. Stromal keratocytes are dispersed among stromal collagen fibers, forming a network of cells interconnected via gap junctions 1-4 . Keratocytes are typically quiescent under normal physiological conditions. Following corneal injury, keratocytes activate and become myofibroblasts, which migrate to the wound area and are heavily involved in the wound repair process.In many cell types, including gastrointestinal tract cells, myocytes, and osteocytes, physiological mechanical loading can create transient micro-tears in the cell membrane termed transient plasma membrane disruptions (TPMDs) 5-8 , which is a common form of cell injury. These TPMDs are typically repaired rapidly (within 10 to 60 seconds) to allow for continued cell survival. Importantly, TPMDs foster molecular flux across cell membranes and promote tissue adaptation by initiating cellular mechanotransduction signaling. A TPMD facilitates rapid extracellular calcium influx at the site of membrane injury, which can trigger a number of downstream intra-and extracellular signaling events.TPMDs and their associated intercellular signaling responses may occur frequently in corneal keratocytes as a result of mechanical stimulation initiated by, for example, eye rubbing and minor or major corneal trauma. Mechanical stimulation has been postulated to be the source of TPMDs in bone osteocytes, which reside in bony ...

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Section: Discussionmentioning

confidence: 99%

Transient Cell Membrane Disruptions induce Calcium Waves in Corneal Keratocytes

Chen

McGee‐Lawrence

et al. 2020

Sci Rep

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“…Several groups have demonstrated that mechanicallyinduced membrane disruptions occur routinely under physiological conditions in different tissues, including muscle fibers (29), gastrointestinal tract (30), heart (31), aorta (32) and bone (7,8). Despite these injuries, cell death is minimal because cells can rapidly repair these injuries (33).…”

Section: Atp Release Due To Mechanical Injurymentioning

confidence: 99%

“…We have recently reported that physiologically-relevant mechanical loading routinely injured bone cells in vitro and in vivo, resulting in release of ATP through plasma membrane disruptions, and stimulation of calcium responses in the neighbouring cells (7). These membrane disruptions in bone cells are counteracted by rapid vesicle-mediated membrane repair (7,8), which limits ATP spillage. Thus, contrary to previous generalizations that ATP is released as a bolus proportional to mechanical stimulus (9), our data suggest that mechanically-stimulated ATP release contains dynamic information about both the extent of the injury and the rate of repair.…”

Section: Introductionmentioning

confidence: 99%

Transmission of mechanical information by purinergic signaling

Mikolajewicz

Sehayek

Wiseman

et al. 2018

Preprint

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The human skeleton constantly interacts and adapts to the physical world. We have previously reported that physiologically-relevant mechanical forces lead to small, repairable membrane injuries in bone-forming osteoblasts, resulting in the release of ATP and stimulation of purinergic (P2) calcium responses in neighbouring cells. The goal of this study was to develop a theoretical model describing injury-related ATP and ADP release, extracellular diffusion and degradation, and purinergic responses in neighboring cells. The model was validated using experimental data obtained by measuring intracellular free calcium ([Ca 2+ ]i) elevations following mechanical stimulation of a single osteoblast. The validated single-cell injury model was then scaled to a tissue-level injury to investigate how purinergic responses communicate information about injuries with varying geometries. We found that total ATP released, peak extracellular ATP concentration and the ADP-mediated signaling component contributed complementary information regarding the mechanical stimulation event. The total amount of ATP released governed the maximal distance from the injury at which purinergic responses were stimulated, as well as the overall number of responders. The peak ATP concentration reflected the severity of an individual cell injury and determined signal propagation velocity and temporal synchrony of responses. Peak ATP concentrations also discriminated between minor and severe injuries that led to the release of similar total amounts of ATP due to differences in injury repair dynamics. The third component was ADP-mediated signaling which became relevant only in larger tissue-level injuries, and it conveyed information about the distance to the injury site and its geometry. Taken together, this study identified specific features of extracellular ATP/ADP spatiotemporal signals that encode the severity of the mechanical stimulus, the distance from the stimulus, as well as the mechanoresilient status of the tissue.

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“…It has been suggested that fluid drag forces on the osteocyte pericellular matrix (i.e., glycocalyx) are important for osteocyte mechanotransduction, and that fiber volume fraction in the osteocyte pericellular matrix is decreased in aged as compared to younger bone (Wang et al, ), but a direct relationship between osteocyte pericellular matrix and impaired mechanosensation with aging has not yet been demonstrated. We and others have shown that transient plasma membrane disruptions (PMD) develop in osteocytes with mechanical loading both in vitro (fluid flow) and in vivo (exercise), and that these PMD initiate mechanotransduction (Hagan et al, ; Mikolajewicz, Sehayek, Wiseman, & Komarova, ; Mikolajewicz, Zimmermann, Willie, & Komarova, ; Yu et al, ), suggesting that osteocytes may use PMD to detect mechanical loads and direct the activity of remodeling cells to properly adapt the matrix as needed. The effects of aging on osteocyte PMD formation, however, have not been reported.…”

Section: Introductionmentioning

confidence: 99%

Decreased pericellular matrix production and selection for enhanced cell membrane repair may impair osteocyte responses to mechanical loading in the aging skeleton

Hagan

Zhu

et al. 2019

Aging Cell

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Transient plasma membrane disruptions (PMD) occur in osteocytes with in vitro and in vivo loading, initiating mechanotransduction. The goal here was to determine whether osteocyte PMD formation or repair is affected by aging. Osteocytes from old (24 months) mice developed fewer PMD (−76% females, −54% males) from fluid shear than young (3 months) mice, and old mice developed fewer osteocyte PMD (−51%) during treadmill running. This was due at least in part to decreased pericellular matrix production, as studies revealed that pericellular matrix is integral to formation of osteocyte PMD, and aged osteocytes produced less pericellular matrix (−55%). Surprisingly, osteocyte PMD repair rate was faster (+25% females, +26% males) in osteocytes from old mice, and calcium wave propagation to adjacent nonwounded osteocytes was blunted, consistent with impaired mechanotransduction downstream of PMD in osteocytes with fast PMD repair in previous studies. Inducing PMD via fluid flow in young osteocytes in the presence of oxidative stress decreased postwounding cell survival and promoted accelerated PMD repair in surviving cells, suggesting selective loss of slower-repairing osteocytes. Therefore, as oxidative stress increases during aging, slower-repairing osteocytes may be unable to successfully repair PMD, leading to slower-repairing osteocyte death in favor of faster-repairing osteocyte survival. Since PMD are an important initiator of mechanotransduction, age-related decreases in pericellular matrix and loss of slower-repairing osteocytes may impair the ability of bone to properly respond to mechanical loading with bone formation. These data suggest that PMD formation and repair mechanisms represent new targets for improving bone mechanosensitivity with aging.

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Mechanical loading disrupts osteocyte plasma membranes which initiates mechanosensation events in bone

Cited by 38 publications

References 49 publications

Transient Cell Membrane Disruptions induce Calcium Waves in Corneal Keratocytes

Transient Cell Membrane Disruptions induce Calcium Waves in Corneal Keratocytes

Transmission of mechanical information by purinergic signaling

Decreased pericellular matrix production and selection for enhanced cell membrane repair may impair osteocyte responses to mechanical loading in the aging skeleton

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