The expression changes of cystathionine-β-synthase in brain cortex after traumatic brain injury

Cystathionine-β-synthase (CBS) catalyzes the condensation of serine with homocysteine to form cystathionine and occupies a crucial regulatory position between the methionine cycle and the biosynthesis of cysteine by transsulfuration. It was reported that CBS was a novel marker of both differentiation and proliferation for certain cell types, suggesting that CBS represents a survival-promoting protein. However, its expression and function in the central nervous system lesion are not well understood. To investigate changes of CBS after traumatic brain injury (TBI) and its possible role, mice TBI model was established by controlled cortical impact system, and the expression and cellular localization of CBS after TBI was investigated in the present study. Western blot analysis revealed that CBS was present in normal mice brain cortex. It gradually decreased, reached a valley at the third day after TBI, and then restored to basal level. Importantly, more CBS was colocalized with neuron. In addition, Western blot detection showed that the third day postinjury was also the apoptosis peak indicated by the elevated expression of caspase-3. Importantly, immunohistochemistry analysis revealed that injury-induced expression of CBS was colabeled by Bcl-2 and had no co-localization with caspase-3. These data suggested that CBS may be implicated in the apoptosis of neuron and involved in the pathophysiology of brain after TBI.