Activation of p38 MAPK in the substantia nigra leads to nuclear translocation of NF-κB in MPTP-treated mice: implication in Parkinson's disease

Abstract

Activation and translocation of the transcription factor nuclear factor kappa B (NF-κB) from cytoplasm to the nucleus has been reported in models of Parkinson's disease (PD). Our focus was to discern the upstream events which ultimately lead to NF-κB nuclear translocation using animal model of PD. We demonstrate that p38 activation results in downstream phosphorylation of NF-κB and accumulation of p65 subunit of NF-κB selectively in ventral midbrain but not in striatum. Treatment with p38 inhibitor, SB239063, prevented downstream phosphorylation of IκBα and p65 translocation to the nucleus in the ventral midbrain. Phosphorylation of anti-apoptotic Bcl2, an NF-κB target gene by p38 to inactive pBcl2ser87 was also attenuated by SB239063. Increased staining of p65 in the nuclei of cells in the substantia nigra but not in the ventral tegmental area of MPTP-treated mice further suggests a role for NF-κB in PD. In agreement with the above, sustained caspase activation is seen in the ventral midbrain but not in striatum. We demonstrate the region specific p38-mediated activation of NF-κB following MPTP treatment demonstrating the role of p38/NF-κB signaling in the pathogenesis and progression of the disease. Selective inhibitors of p38 may therefore, help preserve the surviving neurons in PD and slow down the disease progression.