Phosphatidylethanolamine-binding protein 1 protects CA1 neurons against ischemic damage via ERK-CREB signaling in Mongolian gerbils

Abstract

In the present study, we made a PEP-1-phosphatidylethanolamine-binding protein 1 (PEP-1-PEBP1) fusion protein to facilitate the transduction of PEBP1 into cells and observed significant ameliorative effects of PEP-1-PEBP1 against H2O2-induced neuronal damage and the formation of reactive oxygen species in the HT22 hippocampal cells. In addition, administration of PEP-1-PEBP1 fusion protein ameliorated H2O2-induced phosphorylation of extracellular signal-regulated kinases (ERK1/2) and facilitated the phosphorylation of cyclic-AMP response element binding protein (CREB) in HT22 cells after exposure to H2O2. We also investigated the temporal and spatial changes of phosphorylated phosphatidylethanolamine-binding protein 1 (pPEBP1) in the hippocampus, after 5 min of transient forebrain ischemia in gerbils. In the sham-operated animals, pPEBP1 immunoreactivity was not detectable in the hippocampal CA1 region. pPEBP1 immunoreactivity was significantly increased in the hippocampal CA1 region, 1–2 days after ischemia, compared to that in the sham-operated group and pPEBP1 immunoreactivity was returned to levels in sham-operated group at 3–4 days after ischemia. pPEBP1 immunoreactivity significantly increased at day 7 after ischemia and decreased to sham-operated group levels by day 10 after ischemia/reperfusion. In addition, administration of PEP-1-PEBP1 fusion protein significantly reduced the ischemia-induced hyperactivity of locomotion, 1 day after ischemia and PEP-1-PEBP1 reduced neuronal damage and reactive gliosis (astrocytosis and microgliosis) in the gerbil hippocampal CA1 region, 4 days after ischemia. Administration of PEP-1-PEBP1 fusion protein ameliorated the ischemia-induced phosphorylation of ERK at 3 h and 6 h after ischemia/reperfusion and accelerated the phosphorylation of CREB in ischemic hippocampus at 6 h after ischemia. These results suggest that the increase in PEBP1 phosphorylation causes neuronal damage in the hippocampus and treatment with PEP-1-PEBP1 fusion protein provides neuroprotection from increasing phosphorylation of ERK-CREB pathways in the hippocampal CA1 region, during ischemic damage.