Transmission of mechanical information by purinergic signaling

Abstract

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.

High-affinity P2Y2and low-affinity P2X7receptor interaction modulates ATP-mediated calcium signaling in murine osteoblasts

“…Second, we have found that in the absence of P2X7, both primary and secondary responses are significantly altered. While local ATP concentrations at the site of micro-injury may support the involvement of P2X7 in generating the Ca 2+ response of the primary cell (Mikolajewicz et al, 2019;Mikolajewicz, Zimmermann, et al, 2018), the observed changes in the secondary responses are surprising, since we have previously shown that the amount of ATP released in these experiments is below the concentrations required for P2X7 activation (Mikolajewicz, Zimmermann, et al, 2018). Nevertheless, this observation is consistent with previously suggested alterations in mechanotransductive signaling in P2X7 deficient mice (Ke et al, 2003;D.…”

“…To investigate the potential functional consequences of the complex interactions between P2Y2 and P2X7, we examined how the absence of each of these receptors affects ATP-mediated mechanotransduction. We have previously shown that mechanical stimulation of a single “ primary ” osteoblast with a glass micropipette leads to the release of 10 −5 to 10 −4 M ATP into the pericellular space, which then diffuses to stimulate neighbouring non-mechanically perturbed “ secondary ” cells (Mikolajewicz et al, 2019; Mikolajewicz, Zimmermann, et al, 2018). Here, we mechanically stimulated a single fura2-loaded osteoblast from parental C2-OB, or clones deficient in P2Y2, P2ry2 Δ, or P2X7, P2rx7 Δ and recorded [Ca 2+ ] i responses in the primary and secondary cells ( Fig.…”

“…This study thus provides important insights into the biophysical mechanisms underlying ATP-dependent Ca 2+ response signatures, which are important in mediating bone mechanoadaptation. in cytosolic free Ca 2+ concentration ([Ca 2+ ] i ) is one of the hallmarks of ATP-induced signaling in many cell types, including bone-forming osteoblasts (Grol, Pereverzev, Sims, & Dixon, 2013;Mackay, Mikolajewicz, Komarova, & Khadra, 2016;Mikolajewicz, Sehayek, Wiseman, & Komarova, 2019;Mikolajewicz, Zimmermann, Willie, & Komarova, 2018;S. Xing et al, 2016).…”

“…P2XRs are fast acting (∼10 ms activation), allowing the permeation of Na + , K + and Ca 2+ through the channel (Coddou, Yan, Obsil, Huidobro-Toro, & Stojilkovic, 2011) whereas P2YRs activate various types of secondary messengers, and thus act on a slower timescale than P2XRs (Erb & Weisman, 2012). Elevations in cytosolic free Ca 2+ concentration ([Ca 2+ ] i ) is one of the hallmarks of ATP-induced signaling in many cell types, including bone-forming osteoblasts (Grol, Pereverzev, Sims, & Dixon, 2013; Mackay, Mikolajewicz, Komarova, & Khadra, 2016; Mikolajewicz, Sehayek, Wiseman, & Komarova, 2019; Mikolajewicz, Zimmermann, Willie, & Komarova, 2018; S. Xing et al, 2016). The mechanism by which P2XRs and P2YRs alter [Ca 2+ ] i differs: P2XR activation increases Ca 2+ influx across the plasma membrane (North, 2002) while P2YR activation enhances Ca 2+ release from the endoplasmic reticulum (ER) by stimulating the G q protein signaling pathway, ultimately leading to the production of inositol triphosphate (IP 3 ) and the activation of IP 3 receptors (IP 3 Rs) (Burnstock, 2018).…”

Metaanalisis peranan teknologi proses pengolahan terhadap penurunan alergenisitas ikan

“…Informasi 95% CI dilambangkan sebagai garis horizontal dalam forest plot. Garis horizontal yang tidak melewati garis vertikal atau titik 0,00 menandakan terdapat perbedaan yang signifikan antara dua kelompok yang dibandingkan (Mikolajewicz & Komarova, 2019).…”