Proteome wide analysis of SUMO interacting proteins from Huntingtons disease R6/2 mouse striatum shows alterations in enrichment of functional synaptic proteins

ABSTRACT: Huntingtons disease (HD) is a neurodegenerative disorder caused by an expanded CAG repeat mutation in the Huntingtin (HTT) gene. The mutation impacts neuronal protein homeostasis and cortical/striatal circuitry. SUMOylation, a post translational modification with broad cellular effects, directly modifies the Huntingtin protein (HTT), along with other key neuronal and synaptic proteins. Here we investigated proteome wide changes in striatal protein SUMOylation/protein SUMO interactions in the context of HD using R6/2 transgenic and non-transgenic (NT) control mice by performing SUMO protein enrichment from tissue followed by mass spectrometry. Significant changes in enrichment of known and previously unknown SUMOylated or SUMO interacting proteins were observed including those involved in presynaptic function and cytomatrix at the active zone scaffolding, cytoskeleton organization, and glutamatergic signaling. A network based approach identified altered pathways in HD tissue to include clathrin mediated endocytosis signaling, synaptogenesis signaling, synaptic long term potentiation, and SNARE signaling. Furthermore, the metabotropic glutamate receptor 7 (mGluR7), a key player in glutamatergic signaling, a core signaling pathway disrupted in HD was SUMO enriched and we show SUMO modification is enhanced by the E3 SUMO ligase Protein Inhibitor of Activated STAT1 (PIAS1). To evaluate functional measures of neuronal activity in HD cells in vitro we utilized primary neuronal cultures from R6/2 and NT mice and evaluated how modulation of SUMOylation via reduction of PIAS1 may impact specific readouts. A receptor internalization assay showed decreased mGluR7 internalization in R6/2 neurons compared to NT, and siRNA mediated knockdown of PIAS1 prevented this HD phenotype. In addition, microelectrode array analysis on primary neuron cultures indicated early timepoint hyperactivity in HD cells, while later timepoints demonstrated deficits in several measurements of neuronal activity within cortical neurons. HD phenotypes were rescued at select timepoints following knockdown of PIAS1. Taken together our results provide a mouse brain SUMO ome resource and show that significant alterations occur within the post-translational landscape and SUMO protein interactions for synaptic proteins in HD.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Mus Musculus (ncbitaxon:10090)

SUBMITTER: Jennifer Van Eyk  

PROVIDER: MSV000093185 | MassIVE | Wed Oct 25 02:35:00 BST 2023

SECONDARY ACCESSION(S): PXD046378

REPOSITORIES: MassIVE