Regulation of Local Translation, Synaptic Plasticity, and Cognitive Function by CNOT7

Local translation of mRNAs in dendrites is vital for synaptic plasticity and learning and memory. Tight regulation of this translation is key to preventing neurological disorders resulting from aberrant local translation. Here we find that CNOT7, the major deadenylase in eukaryotic cells, takes on the distinct role of regulating local translation in the hippocampus. Depletion of CNOT7 from cultured neurons affects the poly(A) state, localization, and translation of dendritic mRNAs while having little effect on the global neuronal mRNA population. Following synaptic activity, CNOT7 is rapidly degraded resulting in polyadenylation and a change in the localization of its target mRNAs. We find that this degradation of CNOT7 is essential for synaptic plasticity to occur as keeping CNOT7 levels high prevents these changes. This regulation of dendritic mRNAs by CNOT7 is necessary for normal neuronal function in vivo, as depletion of CNOT7 also disrupts learning and memory in mice. We utilized deep sequencing to identify the neuronal mRNAs whose poly(A) state is governed by CNOT7. Interestingly these mRNAs can be separated into two distinct populations: ones that gain a poly(A) tail following CNOT7 depletion and ones that surprisingly lose their poly(A) tail following CNOT7 depletion. These two populations are also distinct based on the lengths of their 3’ UTRs and their codon usage, suggesting that these key features may dictate how CNOT7 acts on its target mRNAs. This work reveals a central role for CNOT7 in the hippocampus where it governs local translation and higher cognitive function

Dynamic Control of Dendritic mRNA Expression by CNOT7 Regulates Synaptic Efficacy and Higher Cognitive Function

Translation of mRNAs in dendrites mediates synaptic plasticity, the probable cellular basis of learning and memory. Coordination of translational inhibitory and stimulatory mechanisms, as well as dendritic transport of mRNA, is necessary to ensure proper control of this local translation. Here, we find that the deadenylase CNOT7 dynamically regulates dendritic mRNA translation and transport, as well as synaptic plasticity and higher cognitive function. In cultured hippocampal neurons, synaptic stimulation induces a rapid decrease in CNOT7, which, in the short-term, results in poly(A) tail lengthening of target mRNAs. However, at later times following stimulation, decreased poly(A) and dendritic localization of mRNA take place, similar to what is observed when CNOT7 is depleted over several days. In mice, CNOT7 is essential for hippocampal-dependent learning and memory. This study identifies CNOT7 as an important regulator of RNA transport and translation in dendrites, as well as higher cognitive function

Expansion of regulatory T cells by CD28 superagonistic antibodies attenuates neurodegeneration in A53T-α-synuclein Parkinson’s disease mice

Abstract Background Regulatory CD4+CD25+FoxP3+ T cells (Treg) are a subgroup of T lymphocytes involved in maintaining immune balance. Disturbance of Treg number and impaired suppressive function of Treg correlate with Parkinson’s disease severity. Superagonistic anti-CD28 monoclonal antibodies (CD28SA) activate Treg and cause their expansion to create an anti-inflammatory environment. Methods Using the AAV1/2-A53T-α-synuclein Parkinson’s disease mouse model that overexpresses the pathogenic human A53T-α-synuclein (hαSyn) variant in dopaminergic neurons of the substantia nigra, we assessed the neuroprotective and disease-modifying efficacy of a single intraperitoneal dose of CD28SA given at an early disease stage. Results CD28SA led to Treg expansion 3 days after delivery in hαSyn Parkinson’s disease mice. At this timepoint, an early pro-inflammation was observed in vehicle-treated hαSyn Parkinson’s disease mice with elevated percentages of CD8+CD69+ T cells in brain and increased levels of interleukin-2 (IL-2) in the cervical lymph nodes and spleen. These immune responses were suppressed in CD28SA-treated hαSyn Parkinson’s disease mice. Early treatment with CD28SA attenuated dopaminergic neurodegeneration in the SN of hαSyn Parkinson’s disease mice accompanied with reduced brain numbers of activated CD4+, CD8+ T cells and CD11b+ microglia observed at the late disease-stage 10 weeks after AAV injection. In contrast, a later treatment 4 weeks after AAV delivery failed to reduce dopaminergic neurodegeneration. Conclusions Our data indicate that immune modulation by Treg expansion at a timepoint of overt inflammation is effective for treatment of hαSyn Parkinson’s disease mice and suggest that the concept of early immune therapy could pose a disease-modifying option for Parkinson’s disease patients

Neurodegeneration by α-synuclein-specific T cells in AAV-A53T-α-synuclein Parkinson’s disease mice

Background Antigen-specific neuroinflammation and neurodegeneration are characteristic for neuroimmunological diseases. In Parkinson’s disease (PD) pathogenesis, α-synuclein is a known culprit. Evidence for α-synuclein-specific T cell responses was recently obtained in PD. Still, a causative link between these α-synuclein responses and dopaminergic neurodegeneration had been lacking. We thus addressed the functional relevance of α-synuclein-specific immune responses in PD in a mouse model. Methods We utilized a mouse model of PD in which an Adeno-associated Vector 1/2 serotype (AAV1/2) expressing human mutated A53T-α-Synuclein was stereotactically injected into the substantia nigra (SN) of either wildtype C57BL/6 or Recombination-activating gene 1 (RAG1)$^{-/-}$ mice. Brain, spleen, and lymph node tissues from different time points following injection were then analyzed via FACS, cytokine bead assay, immunohistochemistry and RNA-sequencing to determine the role of T cells and inflammation in this model. Bone marrow transfer from either CD4$^{+}$/CD8$^{-}$, CD4$^{-}$/CD8$^{+}$, or CD4$^{+}$/CD8$^{+}$ (JHD$^{-/-}$) mice into the RAG-1$^{-/-}$ mice was also employed. In addition to the in vivo studies, a newly developed A53T-α-synuclein-expressing neuronal cell culture/immune cell assay was utilized. Results AAV-based overexpression of pathogenic human A53T-α-synuclein in dopaminergic neurons of the SN stimulated T cell infiltration. RNA-sequencing of immune cells from PD mouse brains confirmed a pro-inflammatory gene profile. T cell responses were directed against A53T-α-synuclein-peptides in the vicinity of position 53 (68–78) and surrounding the pathogenically relevant S129 (120–134). T cells were required for α-synuclein-induced neurodegeneration in vivo and in vitro, while B cell deficiency did not protect from dopaminergic neurodegeneration. Conclusions Using T cell and/or B cell deficient mice and a newly developed A53T-α-synuclein-expressing neuronal cell culture/immune cell assay, we confirmed in vivo and in vitro that pathogenic α-synuclein peptide-specific T cell responses can cause dopaminergic neurodegeneration and thereby contribute to PD-like pathology