GSK3β negatively regulates TRAX, a scaffold protein implicated in mental disorders, for NHEJ-mediated DNA repair in neurons

Abstract

Translin-associated protein X (TRAX) is a scaffold protein with various functions and has been associated with mental illnesses, including schizophrenia. We have previously demonstrated that TRAX interacts with a Gsα protein-coupled receptor, the A 2A adenosine receptor (A 2A R), and mediates the function of this receptor in neuritogenesis. In addition, stimulation of the A 2A R markedly ameliorates DNA damage evoked by elevated oxidative stress in neurons derived from induced pluripotent stem cells (iPSCs). Here, we report that glycogen synthase kinase 3 beta (GSK3β) and disrupted-inschizophrenia 1 (DISC1) are two novel interacting proteins of TRAX. We present evidence to suggest that the stimulation of A 2A R markedly facilitated DNA repair through the TRAX/DISC1/GSK3β complex in a rat neuronal cell line (PC12), primary mouse neurons, and human medium spiny neurons derived from iPSCs. A 2A R stimulation led to the inhibition of GSK3β, thus dissociating the TRAX/DISC1/GSK3β complex and facilitating the non-homologous end-joining pathway (NHEJ) by enhancing the activation of a DNA-dependent protein kinase via phosphorylation at Thr 2609 . Similarly, pharmacological inhibition of GSK3β by SB216763 also facilitated the TRAX-mediated repair of oxidative DNA damage. Collectively, GSK3β binds with TRAX and negatively affects its ability to facilitate NHEJ repair. The suppression of GSK3β by A 2A R activation or a GSK3β inhibitor releases TRAX for the repair of oxidative DNA damage. Our findings shed new light on the molecular mechanisms underlying diseases associated with DNA damage and provides a novel target (i.e., the TRAX/DISC1/GSK3β complex) for future therapeutic development for mental disorders.

Increased amphetamine-induced hyperactivity intranslin (Tsn)KO mice is driven by elevated adiposity

“…For TX immunostaining, sections were washed with PBS three times and blocked with 3% BSA and 0.1% Triton X-100 in PBS for 1h, followed by incubation with primary antibodies against trax [27] overnight at 4°C. After three washes, the sections were incubated with biotinylated goat anti-rabbit (Vector Laboratories) in PBS for 1h at room temperature.…”

“…Furthermore, TX binds to the C-terminal tail of the A2a adenosine receptor, which is selectively expressed in D2R-positive striatal neurons [27]. Accordingly, we used A2a adenosine receptor-Cre mice (Adora2a-Cre KG139) to check whether conditional deletion of Tsnax, the gene encoding TX, from D2R-positive striatal neurons affects the locomotor response to amphetamine.…”

Trax: A versatile signaling protein plays key roles in synaptic plasticity and DNA repair

“…In a separate line of research, Chern and co-workers [5,6] have uncovered a key role for trax in DNA repair. The initial studies that led to the identification of translin and its partner protein, trax sought to identify DNA binding proteins that mediate chromosomal translocations associated with malignant transformations, such as those involving Bcl-2 [1,2].…”

“…As A 2A R is G s α-coupled receptor that activates the cAMP/PKA pathway [28], Chien et al [5] asked if dissociation of trax from this receptor is mediated by this pathway. Furthermore, A 2A R stimulation has been shown to trigger phosphorylation of GSK3β, which suppresses its activity.…”

“…In one line of research, Park et al [3] implicate trax, working in combination with translin, in mediating an important form of synaptic plasticity in the hippocampus, referred to as synaptic tagging and capture [4]. In a completely separate area of investigation, Chern and co-workers [5,6] have demonstrated in fibroblasts and neurons that trax, acting without translin, plays a key role in a major signaling pathway that repairs double-stranded DNA breaks. Thus, these findings suggest that trax plays critical roles in multiple signaling pathways and that further studies are warranted to elucidate how these ostensibly disparate functions may be related.…”