Detection of Arc/Arg3.1 oligomers in rat brain: constitutive and synaptic activity-evoked dimer expression in vivo

ABSTRACT: The immediate early gene product activity-regulated cytoskeleton-associate protein (Arc or Arg3.1) is a major regulator long-term synaptic plasticity with critical roles in postnatal cortical development and memory formation. However, the molecular basis of Arc function is not defined. Arc is a hub protein with interaction partners in the postsynaptic neuronal compartment and nucleus. In vitro biochemical and biophysical analysis of purified recombinant Arc show formation of low-order oligomers and larger particles including retrovirus-like capsids. Here, we provide evidence for naturally occurring Arc oligomers in mammalian brain. Using in situ protein crosslinking to trap weak Arc-Arc interactions, we identified in various preparations a prominent Arc immunoreactive band on SDS-PAGE of molecular mass corresponding to a dimer. While heavier Arc species or putative trimers and tetramers were detected, they were of lower abundance. In the dentate gyrus (DG) of adult anesthetized rats, induction of long-term potentiation (LTP) by high-frequency stimulation (HFS) of medial perforant synapses or by brief intrahippocampal infusion of BDNF led to a massive increase in Arc dimer expression. Arc immunoprecipitation of crosslinked DG tissue showed enhanced expression of dimer during four hours of LTP maintenance. Mass spectrometric proteomic analysis of immunoprecipitated, gel-excised bands corroborated detection of Arc dimer. Furthermore, Arc dimer was constitutively expressed in naïve cortical, hippocampal and DG tissue, with lowest levels in the DG. Taken together the results implicate Arc dimers as the predominant low-oligomeric form in mammalian brain, exhibiting regional differences in its constitutive expression and pronounced enhanced expression during DG LTP.

INSTRUMENT(S): Orbitrap Exploris 480

ORGANISM(S): Rattus Norvegicus (rat)

TISSUE(S): Brain

SUBMITTER: Tadiwos Feyissa Mergiya  

LAB HEAD: Clive, Raymond Evjen, Bramham

PROVIDER: PXD039612 | Pride | 2023-07-20

REPOSITORIES: Pride