Phosphorylation‐dependent control of Activity‐regulated cytoskeleton‐associated protein (Arc) protein by TNIK

Abstract

Activity-regulated cytoskeleton-associated protein (Arc) is an immediate early gene product that support neuroplastic changes important for cognitive function and memory formation. As a protein with homology to the retroviral Gag protein, a particular characteristic of Arc is its capacity to self-assemble into virus-like capsids that can package mRNAs and transfer those transcripts to other cells. Although a lot has been uncovered about the contributions of Arc to neuron biology and behavior, very little is known about how different functions of Arc are coordinately regulated both temporally and spatially in neurons. The answer to this question we hypothesized must involve the occurrence of different protein post-translational modifications acting to confer specificity. In this study, we used mass spectrometry and sequence prediction strategies to map novel Arc phosphorylation sites. Our approach led us to recognize serine 67 (S67) and threonine 278 (T278) as residues that can be modified by TNIK, which is a kinase abundantly expressed in neurons that shares many functional overlaps with Arc and has, along with its interacting proteins such as the NMDA receptor, and been implicated as a risk factor for psychiatric disorders. Furthermore, characterization of each residue using site-directed mutagenesis to create S67 and T278 mutant variants revealed that TNIK action at those amino acids can strongly influence Arc's subcellular distribution and self-assembly as capsids. Together, our findings reveal an unsuspected connection between Arc and TNIK. Better understanding of the interplay between these two proteins in neuronal cells could lead to new insights about apparition and progression of psychiatric disorders.

High-affinity anti-Arc nanobodies provide tools for structural and functional studies

“…Thr278 of the Arc-CTD undergoes phosphorylation by TNIK kinase in Neuro2A cells, and a phosphomimicking mutation reduces the ability of recombinant mouse Arc to form capsids [ 78 ]. Furthermore, the G277D mutation was suggested to reduce the ability of Arc to oligomerise [ 42 ].…”

Pinus halepensis Essential Oil Ameliorates Aβ1-42-Induced Brain Injury by Diminishing Anxiety, Oxidative Stress, and Neuroinflammation in Rats

“…Arc is a plasticity-related gene, belonging to the immediate–early gene family [ 96 ]. Its induction occurs shortly after synaptic activation, being expressed in the excitatory neurons because of behavioral assessments [ 97 ].…”

Molecular physiology of Arc/Arg3.1: The oligomeric state hypothesis of synaptic plasticity

“…T278 is located in the short linear hinge between the N‐lobe and C‐lobe. Transmission EM analysis of recombinant Arc WT protein showed round capsid‐like structures, whereas samples of ArcT278D phosphomimetic showed aggregates but were devoid of capsids 70 . DLS analysis also showed large diameter aggregates and a smaller diameter subpopulation.…”

“…The dynamic role of the new Arc in actin filament reorganization fits with the function of a monomer or dimer, rather than a more metabolically stable oligomer (Figure 6, state 2). Although Arc does not bind F‐actin directly, it associates with the F‐actin‐binding protein drebrin A 64,70 . Drebrin A is a major regulator of F‐actin stability and spine stability.…”