Extracellular ATP signaling via P2X4 receptor and cAMP/PKA signaling mediate ATP oscillations essential for prechondrogenic condensation

Abstract

Prechondrogenic condensation is the most critical process in skeletal patterning. A previous study demonstrated that ATP oscillations driven by Ca 2C oscillations play a critical role in prechondrogenic condensation by inducing oscillatory secretion. However, it remains unknown what mechanisms initiate the Ca 2C -driven ATP oscillations, mediate the link between Ca 2C and ATP oscillations, and then result in oscillatory secretion in chondrogenesis. This study has shown that extracellular ATP signaling was required for both ATP oscillations and prechondrogenic condensation. Among P2 receptors, the P2X 4 receptor revealed the strongest expression level and mediated ATP oscillations in chondrogenesis. Moreover, blockage of P2X 4 activity abrogated not only chondrogenic differentiation but also prechondrogenic condensation. In addition, both ATP oscillations and secretion activity depended on cAMP/PKA signaling but not on K ATP channel activity and PKC or PKG signaling. This study proposes that Ca 2C -driven ATP oscillations essential for prechondrogenic condensation is initiated by extracellular ATP signaling via P2X 4 receptor and is mediated by cAMP/PKA signaling and that cAMP/PKA signaling induces oscillatory secretion to underlie prechondrogenic condensation, in cooperation with Ca 2C and ATP oscillations.

Purinergic signalling is required for calcium oscillations in migratory chondrogenic progenitor cells

“…Purinergic receptors are known to mediate Ca 2+ oscillations in various cell types [10,13,22,28]. In this work, we propose that purinergic signalling may be the main drive Ca 2+ of oscillations in CPCs as (1) breakdown of extracellular ATP and ADP by apyrase was able to completely abrogate Ca 2+ oscillations, and (2) the very same P2 purinergic receptors (i.e.…”

Investigation of the Inhibitory Effects of the Benzodiazepine Derivative, 5-BDBD on P2X4Purinergic Receptors by two Complementary Methods

“…In recent years, considerable efforts have been made to discover novel effective antagonists of P2X 4 Rs. Although the benzodiazepine derivative 5-BDBD has been recently proposed to selectively block P2X 4 Rs [27], only limited experiences have been available concerning its inhibitory properties [28,29,30,31]. Moreover, to the best of our knowledge, there are no previous studies attempting to compare the inhibitory effects of 5-BDBD using both electrophysiological and intracellular calcium measurements.…”

“…So far, limited experience has been available with 5-BDBD and there is no consensus about its pharmacologically relevant concentration range. In some studies low micromolar (5-10 μM) concentrations were used [28,29] whereas others applied significantly higher doses of 5-BDBD (30-100 μM) [30,31]. …”

Purinergic signalling in the musculoskeletal system

“…A recent study has also shown that intracellular oscillations in ATP have a critical role in pre-chondrogenic condensation, via P2X4 receptors [321] and mediate inductive action of fibroblast growth factor [322].…”