Changes in the GEF-H1 pathways after traumatic brain injury.

Brains undergo significant remodeling after traumatic brain injury (TBI). The Rho guanine triphosphate (GTP)ase pathways control brain remodeling during development and under pathological conditions. How the Rho GTPase pathways are regulated in the brain after TBI remains largely unknown, however. This study used the rat fluid percussion injury model to investigate changes in the Rho GTPase pathways after TBI. The results showed that TBI leads to activation and translocation of RhoA and Rac1 proteins from cytosolic fraction to the membrane fraction after injury. Consistently, the Rho guanine nucleotide exchange factors GEF-H1 and Cool-2/αPix are significantly activated by dephosphorylation and accumulation in the cytosolic fractions during the post-TBI phase. Because the Rho GTPase pathways are key regulators of brain remodeling, these results depict regulatory mechanisms of the Rho GTPase pathways after TBI, and pave the way for the study of therapeutic agents targeting the Rho GTPase pathways for functional recovery after TBI.