TY - JOUR T1 - Activation of Extracellular Signal-Regulated Kinase by Stretch-Induced Injury in Astrocytes Involves Extracellular ATP and P2 Purinergic Receptors JF - The Journal of Neuroscience JO - J. Neurosci. SP - 2348 LP - 2356 DO - 10.1523/JNEUROSCI.23-06-02348.2003 VL - 23 IS - 6 AU - Joseph T. Neary AU - Yuan Kang AU - Karen A. Willoughby AU - Earl F. Ellis Y1 - 2003/03/15 UR - http://www.jneurosci.org/content/23/6/2348.abstract N2 - Gliosis is characterized by hypertrophic and hyperplastic responses of astrocytes to brain injury. To determine whether injury of astrocytes produced by an in vitro model of brain trauma activates extracellular signal-regulated protein kinase (ERK), a key regulator of cellular proliferation and differentiation, astrocytes cultured on deformable SILASTIC membranes were subjected to rapid, reversible strain (stretch)-induced injury. Activation of ERK was observed 1 min after injury, was maximal from 10 to 30 min, and remained elevated for 3 hr. Activation of ERK was dependent on the rate and magnitude of injury; maximum ERK activation was observed after a 20–60 msec, 7.5 mm membrane displacement. ERK activation was blocked by inhibiting MEK, the upstream activator of ERK. Activation of ERK was reduced when calcium influx was diminished. When extracellular ATP was hydrolyzed by apyrase or ATP/P2 receptors were blocked, injury-induced ERK activation was significantly reduced. P2 receptor antagonist studies indicated a role for P2X2 and P2Y1, but not P2X1, P2X3, or P2X7, receptors in injury-induced ERK activation. These findings demonstrate for the first time that ATP released by mechanical injury is one of the signals that triggers ERK activation and suggest a role for extracellular ATP, P2 purinergic receptors, and calcium-dependent ERK signaling in the astrocytic response to brain trauma. ER -