Chaperonin containing TCP1 (CCT) is an essential protein that controls proteostasis following spinal cord damage. In particular, CCT2 plays an important role in neuronal death in various neurological disorders; however, few studies have investigated the effects of CCT2 on ischemic damage in the spinal cord. In the present study, we synthesized a cell-permeable Tat-CCT2 fusion protein and observed its effects on H2O2-induced oxidative damage in NSC34 motoneuron-like cells and in the spinal cord after ischemic injury. Tat-CCT2, but not its control protein CCTs, was delivered into NSC34 cells in a concentration- and incubation time-dependent manner, and a clear cytosolic location of the delivered protein was observed. In addition, the delivered protein gradually degraded, and nearly control levels were observed 24h after Tat-CCT2 treatment. Tat-CCT2 treatment significantly ameliorated 200 µM H2O2-induced neuronal damage in NSC34 cells at 8.0 µM protein treatment. Additionally, Tat-CCT2 significantly ameliorated H2O2-induced reactive oxygen species formation and DNA fragmentation. In the rabbit spinal cord, Tat-CCT2 was efficiently delivered into the spinal cord 4h after 0.125mg/kg protein treatment. In addition, treatment with Tat-CCT2 significantly improved the neurological scores based on the Tarlov criteria 24 and 72h after ischemia/reperfusion. Moreover, the number of surviving neurons in the ventral horn of the spinal cord was significantly increased in the Tat-CCT2-treated group 3 and 7 days after ischemia compared to vehicle-treated group. Treatment with Tat-CCT2 alleviated the ischemia-induced oxidative stress and ferroptosis-related factor (malondialdehyde, 8-iso-prostaglandin F2α, and high mobility group box 1) and pro-inflammatory cytokine (interleukin-1β, interleukin-6, and tumor necrosis factor-α) releases in the ventral horn of the spinal cord 8 and 24h after ischemia/reperfusion. In addition, Tat-CCT2 treatment significantly ameliorated ischemia-induced microglial activation in the ventral horn of spinal cord 24h after reperfusion. These results suggest that Tat-CCT2 mitigates ischemia-induced neuronal damage in the spinal cord.
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