Increased expression of AGS3 in rat brain cortex after traumatic brain injury

Receptor-independent activators of G protein signaling (AGS) offer alternative modes of signal processing for the G protein signaling system that has broad mechanistic and functional significance. Previous studies have demonstrated that AGS3, which belongs to the AGS family, is involved in a number of different cellular activities. However, the distribution and function of AGS3 in the central nervous system (CNS) remain unclear. To investigate whether AGS3 is involved in CNS injury and repair, we used an acute traumatic brain injury (TBI) model in adult rats. Western blot analysis and immunohistochemistry showed a significant upregulation of AGS3 in ipsilateral peritrauma cortex. Double immunofluorescence staining showed that AGS3 was coexpressed with NeuN but rarely with glial fibrillary acidic protein. In addition, we detected that active caspase-3 had colocalization with NeuN and AGS3, suggesting that AGS3 might be involved in the neuron apoptosis after TBI. To investigate the potential function of AGS3 further, a neuronal cell line, PC12, was employed to establish a cell apoptosis model. Western blot analysis indicated that AGS3 shared a similar dynamic variation in animal experiments, and phosphorylated cyclic AMP response element-binding protein (CREB) increased in parallel. Additionally, knocking down AGS3 with siRNA partially attenuated the protein level of phosphorylated CREB in PC12 stimulated by H2 O2 , while reinforcing active caspase-3 expression, demonstrating a probable antiapoptotic role through CREB played by AGS3 in neuronal apoptosis. We hypothesize that AGS3 might play an important antiapoptotic role through enhancing phosphorylation of CREB. © 2013 Wiley Periodicals, Inc.