CREB Inactivation by HDAC1/PP1γ Contributes to Dopaminergic Neurodegeneration in Parkinson's Disease

Abstract

Understanding the pathogenesis of nigral dopaminergic neurodegeneration is critical for developing mechanism-based treatments for Parkinson's disease (PD). In the nigral dopaminergic neurons of postmortem human PD brains, we found that CREB, a well-recognized pro-survival transcription factor in neurons, was inactivated by dephosphorylation at Ser133. CREB dephosphorylation correlated with decreased expression of NURR1, one of its target genes crucial for dopaminergic neuron survival, confirming that CREB function was impaired in nigral dopaminergic neurons in PD. An MPTP mouse model was used to further elucidate the mechanism underlying CREB dephosphorylation. Protein phosphatase 1γ (PP1γ), which dephosphorylates CREB, was constitutively associated with histone deacetylase 1 (HDAC1). HDAC1 promotes CREB Ser133 dephosphorylation via a stable interaction with PP1γ. We found that CREB interacted with the HDAC1/PP1γ complex during dopaminergic neurodegeneration. Importantly, increased CREB/HDAC1 interaction occurred in the nigral dopaminergic neurons of PD patients as demonstrated using a proximity ligation assay. Disrupting CREB/HDAC1 interaction via either overexpression of GAL4 M1, a CREB mutant, or administration of trichostatin A, a pan-HDAC inhibitor, restored the expression levels of phospho-CREB (Ser133) and NURR1, and protected nigral dopaminergic neurons in the MPTP-treated mouse brain. Collectively, our results demonstrated that HDAC1/PP1γ-mediated CREB inactivation contributed to dopaminergic neuronal degeneration. Disruption of CREB/HDAC1 interaction has the potential to be a new approach for PD therapy.

SIGNIFICANCE STATEMENT Parkinson's disease (PD) is the most common movement disorder attributed to the progressive loss of dopaminergic neurons in the substantia nigra. Understanding the pathogenesis of nigral dopaminergic neurodegeneration is critical for developing mechanism-based treatments for PD. We found in nigral dopaminergic neurons of postmortem human PD brains that CREB, a well-recognized pro-survival transcription factor in neurons, was inactivated by dephosphorylation at Ser133. HDAC1, constitutively associated with PP1γ, interacted with CREB to mediate its dephosphorylation during dopaminergic neurodegeneration. Disrupting CREB/HDAC1 interaction restored CREB activity and protected nigral dopaminergic neurons in the MPTP mouse brains. This work suggests that disruption of the CREB/HDAC1 interaction to restore CREB activity may be a potential therapeutic approach in PD.