Recent studies demonstrate that
reactive oxygen species (ROS) are important mediators of
acute pancreatitis, whether induced experimentally or in necrotizing
pancreatitis in humans; however, the cellular processes involved remain unclear.
Adapter protein CrkII, plays a central role for convergence of cellular signals from different stimuli.
Cholecystokinin (CCK), which induces
pancreatitis, stimulates CrkII
tyrosine phosphorylation and
CrkII protein complexes, raising the possibility it can be important in the acinar cell responses to ROS. Therefore, our aim was to investigate whether CrkII signaling is involved in the
biological response of rat pancreatic acini to H2O2 and the intracellular mediators implicated. Treatment of isolated rat pancreatic acini with H2O2 rapidly stimulates CrkII phosphorylation, measured as electrophoretic mobility shift and by using a
phosphospecific antibody (pTyr221).
Tyrosine kinase blocker B44 inhibits the higher phosphorylation state, demonstrating that it occurs mainly in
tyrosine residues. H2O2-induced CrkII phosphorylation is time- and concentration-dependent, showing maximal effect with 3 mM H2O2 at 5 min. The intracellular pathways induced by H2O2 leading to CrkII
tyrosine phosphorylation do not involve PKC, intracellular
calcium, PI3-K or the actin cytoskeleton integrity. ROS generation clearly promotes the formation of
protein complex CrkII-PYK2. In conclusion, ROS clearly affect the key
adapter protein CrkII signaling by two ways: stimulation of CkII phosphorylation and a functional consequence: formation of
CrkII-protein complexes. Because of its central role in activating more distal pathways, CrkII might likely play an important role in the ability of ROS to induce pancreatic cellular injury and
pancreatitis.