Mechanical strain-induced Ca²⁺waves are propagated via ATP release and purinergic receptor activation

Abstract

Mechanical strain applied to prostate cancer cells induced an intracellular Ca(2+) (Ca(i)(2+)) wave spreading with a velocity of 15 microm/s. Ca(i)(2+) waves were not dependent on extracellular Ca(2+) and membrane potential because propagation was unaffected in high-K(+) and Ca(2+)-free solution. Waves did not depend on the cytoskeleton or gap junctions because cytochalasin B and nocodazole, which disrupt microfilaments and microtubules, respectively, and 1-heptanol, which uncouples gap junctions, were without effects. Fluorescence recovery after photobleaching experiments revealed an absence of gap junctional coupling. Ca(i)(2+) waves were inhibited by the purinergic receptor antagonists basilen blue and suramin; by pretreatment with ATP, UTP, ADP, UDP, 2-methylthio-ATP, and benzoylbenzoyl-ATP; after depletion of ATP by 2-deoxyglucose; and after ATP scavenging by apyrase. Waves were abolished by the anion channel inhibitors 5-nitro-2-(3-phenylpropylamino)benzoic acid, tamoxifen, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid, niflumic acid, and gadolinium. ATP release following strain was significantly inhibited by anion channel blockers. Hence, ATP is secreted via mechanosensitive anion channels and activates purinergic receptors on the same cell or neighboring cells in an autocrine and paracrine manner, thus leading to Ca(i)(2+) wave propagation.

Mechanically induced calcium signaling in chondrocytes in situ

“…Results from previous studies suggest that calcium signaling in chondrocytes occurs via stretch activated calcium channels 14,43 and/or via stretch activated release of ATP. [44][45][46][47][48] In order to investigate these possible mechanotransduction pathways, we plan to perform studies in which stretch activated calcium channels are inhibited by gadolinium and intracellular calcium release is inhibited via thapsigargin. 30,44,45 Calcium signaling occurred faster and had higher amplitudes at 378C than at 218C, indicating that Ca 2þ signaling is temperature dependent, as has been found for other cell types.…”

“…[44][45][46][47][48] In order to investigate these possible mechanotransduction pathways, we plan to perform studies in which stretch activated calcium channels are inhibited by gadolinium and intracellular calcium release is inhibited via thapsigargin. 30,44,45 Calcium signaling occurred faster and had higher amplitudes at 378C than at 218C, indicating that Ca 2þ signaling is temperature dependent, as has been found for other cell types. 34,35 This finding may have significant functional implications as cartilage is an avascular tissue known to change temperature significantly when exposed to ambient temperature changes 49,50 which, according to our results, may affect the ability of chondrocytes to respond to mechanical stimuli.…”

Orthodontic mechanotransduction and the role of the P2X7 receptor

“…It has been shown that P2 activation leads to increases in concentration of intracellular calcium and PGE2 release (Naemsch et al, 2001). ATP, which activates this pathway, is typically released by bone, endothelial and epithelial cells and fibroblasts under stress conditions, acting as a DAMP/alarmin (Bodin & Burnstock, 1998;Burnstock, 1999;Furuya, Sokabe & Furuya, 2005;Grygorczyk & Hanrahan, 1997;John & Barakat, 2001;Katsuragi & Migita, 2004;Katz, Boland & Santillan, 2006;Kerkweg & de Groot, 2005;Milner et al, 1992;Milner et al, 1990b;Ohata et al, 1997;Patel et al, 2005;Romanello et al, 2001;Sauer, Hescheler & Wartenberg, 2000;Yamamoto et al, 2003).…”

ATP masks stretch activation of epithelial sodium channels in A6 distal nephron cells

“…Because mechanical stretch can induce cellular ATP release (14,15), P 2 receptors might be stimulated by stretch. Since, in preliminary work, we have shown that ATP inhibits ENaC activity in A6 distal nephron cells, we hypothesized that the inhibitory effect of stretch-induced ATP release on ENaC might obscure a stretch-induced ENaC activation.…”