Loss of F-box Only Protein 2 (Fbxo2) Disrupts Levels and Localization of Select NMDA Receptor Subunits, and Promotes Aberrant Synaptic Connectivity

Atkin, Graham; Moore, Stanford; Lü, Yuan; Nelson, Rick F.; Tipper, Nathan; Rajpal, Gautam; Hunt, Jack; Tennant, William; Hell, Johannes; Murphy, Geoffrey G.; Paulson, Henry L.

doi:10.1523/jneurosci.3013-14.2015

Cited by 39 publications

(41 citation statements)

References 78 publications

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“…Changes in the proportion of excitatory synaptic contacts formed either on dendritic spines or shafts should have significant effects on network function and plasticity (46)(47)(48). Previous studies, however, failed to produce generally accepted evidence on the net effect of an unbalanced ratio of these two types of synapse (46,(49)(50)(51)(52). Our data demonstrate that the increase of synapses on dendritic shaft caused by nArgBP2 KD does not compensate for the alteration of excitatory synaptic transmission due to the loss of synapses on dendritic spines.…”

Section: Discussioncontrasting

confidence: 49%

nArgBP2 regulates excitatory synapse formation by controlling dendritic spine morphology

Lee

Kim

Han

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Neural Abelson-related gene-binding protein 2 (nArgBP2) was originally identified as a protein that directly interacts with synapseassociated protein 90/postsynaptic density protein 95-associated protein 3 (SAPAP3), a postsynaptic scaffolding protein critical for the assembly of glutamatergic synapses. Although genetic deletion of nArgBP2 in mice leads to manic/bipolar-like behaviors resembling many aspects of symptoms in patients with bipolar disorder, the actual function of nArgBP2 at the synapse is completely unknown. Here, we found that the knockdown (KD) of nArgBP2 by specific small hairpin RNAs (shRNAs) resulted in a dramatic change in dendritic spine morphology. Reintroducing shRNA-resistant nArgBP2 reversed these defects. In particular, nArgBP2 KD impaired spinesynapse formation such that excitatory synapses terminated mostly at dendritic shafts instead of spine heads in spiny neurons, although inhibitory synapse formation was not affected. nArgBP2 KD further caused a marked increase of actin cytoskeleton dynamics in spines, which was associated with increased Wiskott-Aldrich syndrome protein-family verprolin homologous protein 1 (WAVE1)/p21-activated kinase (PAK) phosphorylation and reduced activity of cofilin. These effects of nArgBP2 KD in spines were rescued by inhibiting PAK or activating cofilin combined with sequestration of WAVE. Together, our results suggest that nArgBP2 functions to regulate spine morphogenesis and subsequent spine-synapse formation at glutamatergic synapses. They also raise the possibility that the aberrant regulation of synaptic actin filaments caused by reduced nArgBP2 expression may contribute to the manifestation of the synaptic dysfunction observed in manic/bipolar disorder. nArgBP2 | dendritic spines | excitatory synapse | actin | bipolar disorder T he postsynaptic enriched adaptor protein neural Abelsonrelated gene-binding protein 2 (nArgBP2), a neural-specific splice variant of the ubiquitous ArgBP2, was originally identified as a binding partner of synapse-associated protein 90/postsynaptic density protein 95-associated protein 3 (SAPAP3) (1). It belongs to a family of adaptor proteins that are involved in the regulation of cell adhesion, actin cytoskeleton organization, and growth factor receptor signaling (2). This protein family is characterized by a sorbin homology (SoHo) domain in the NH 2 -terminal region and three Src homology 3 (SH3) domains in the COOH-terminal region (3). Although the SoHo domain remains poorly characterized, the SH3 domains bind signaling protein kinases, the ubiquitin ligase, and protein involved in the regulation of focal adhesions and adhering junctions (1, 4-6). The NH 2 -terminal region of nArgBP2, which contains the SoHo domain, interacts with spectrin, whereas the COOH-terminal SH3 domains bind dynamin, synaptojanin, Wiskott-Aldrich syndrome protein-family verprolin homologous protein (WAVE) isoforms, and WAVE regulatory proteins (3), all of which participate in the regulation of the actin cytoskeleton. We also found that the down-re...

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Section: Discussioncontrasting

confidence: 49%

nArgBP2 regulates excitatory synapse formation by controlling dendritic spine morphology

Lee

Kim

Han

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…NMDARs play central roles in synaptic plasticity and mediate neurotoxicity when over-stimulated. F-box only protein 2 (Fbxo2) could precisely regulate NMDARs by ubiquitination (Atkin et al 2015). In the HIP of the OVX rats, Fbxo2 was increased to 133.5% of the level in the SHAM rats (Fig.…”

Section: Resultsmentioning

confidence: 96%

Evidence of altered depression and dementia‐related proteins in the brains of young rats after ovariectomy

Fang

Zeng

et al. 2018

Journal of Neurochemistry

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Menopause, a risk factor for brain dysfunction in women, is characterized by neuropsychological symptoms including depression and dementia, which are closely related to alterations in different brain regions after menopause. However, little is known about the variability in pathophysiologic changes associated with menopause in the brain. Here, we observed that menopause in rats induced by bilateral ovariectomy (OVX) showed depressive and dementia-related behaviors along with neuronal loss in the prefrontal cortex (PFC), hippocampus (HIP), hypothalamus (HYP), and amygdala (AMY) by Nissl staining. Meanwhile, by immunohistochemical staining, increased microglia in the HIP and AMY and increased astrocytes in the PFC, HYP, and AMY were shown. Using quantitative proteomics, we identified 146 differentially expressed proteins in the brains of OVX rats, for example, 20 in the PFC, 41 in the HIP, 17 in the HYP, and 79 in the AMY, and performed further detection by western blotting. A link between neuronal loss and apoptosis was suggested, as evidenced by increases in adenylate kinase 2 (AK2), B-cell lymphoma 2 associated X (Bax), cleaved caspase 3, and phosphorylated p53 and decreases in Huntingtin-interacting protein K, hexokinase, and phosphorylated B-cell lymphoma 2 (Bcl-2), and apoptosis might be triggered by endoplasmic reticulum stress (probed by increased glucose-regulated protein 78 (GRP78), cleaved caspase 12, phosphorylated protein kinase R (PKR)-like endoplasmic reticulum kinase, inositol-requiring enzyme-1 and activating transcription factor 6), and mitochondrial dysfunction (probed by increased cytochrome c and cleaved caspase 3 and decreased sideroflexin-1 (SFXN1) and NADH dehydrogenase (ubiquinone) 1 α subcomplex 11 (NDUFA11)). Activation of autophagy was also indicated by increased autophagy-related 7, γ-aminobutyric acid (GABA) receptor-associated protein-like 2, and oxysterol-binding protein-related protein 1 and confirmed by increased microtubule-associated protein light chain 3 (LC3II/I), autophagy-related 5, and Beclin1 in the HIP and AMY. In the AMY, which is important in emotion, higher GABA transporter 3 and lower vesicular glutamate transporter 1 levels indicated an imbalance between excitatory and inhibitory neurotransmission, and the increased calretinin and decreased calbindin levels suggested an adjustment of GABAergic transmission after OVX. In addition, cytoskeletal abnormalities including tau hyperphosphorylation, dysregulated Ca² signals, and glutamic synaptic impairments were observed in the brains of OVX rats. Collectively, our study showed the changes in different brain regions related to depression and dementia during menopause.

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“…Sections were then washed in TBS for 3 min × 10 min and incubated for 72 h in primary antibody specific for glutamate receptors and transporters at 4 • C ( Table 1). Specificity of the primary antibodies has been tested using western blotting and reported previously for each of the antibodies GluA1 (Zhu et al, 2017;Song et al, 2019), GluA2 (Banerjee et al, 2013;Hussain and Davanger, 2015), GluN1 (Morimura et al, 2017;Seigneur and Südhof, 2018), GluN2A (Atkin et al, 2015;Konstantoudaki et al, 2016), VGluT1 (Venniro et al, 2017;Nakano et al, 2018), VGluT2 (Hernández et al, 2015;Nakano et al, 2018), and Aβ 1−42 (Kwakowsky et al, 2016) (Figures 1A-D). Following 3 min × 10 min washes in TBS, the sections were incubated at RT for 1 h in secondary antibodies goat anti-mouse Alexa Fluor 647 (1:500, A21236, Thermo Fisher, Waltham, MA, United States), goat anti-rabbit Alexa Fluor 488 (1:500, A11034, Thermo Fisher), and goat anti-guinea pig Alexa Fluor 594 (1:500, A11076, Thermo Fisher) diluted in TTB.…”

Section: Fluorescent Immunohistochemistrymentioning

confidence: 98%

The Acute Effects of Amyloid-Beta1–42 on Glutamatergic Receptor and Transporter Expression in the Mouse Hippocampus

et al. 2020

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Alzheimer's disease (AD) is the leading type of dementia worldwide. Despite an increasing burden of disease due to a rapidly aging population, there is still a lack of complete understanding of the precise pathological mechanisms which drive its progression. Glutamate is the main excitatory neurotransmitter in the brain and plays an essential role in the normal function and excitability of neuronal networks. While previous studies have shown alterations in the function of the glutamatergic system in AD, the underlying etiology of beta amyloid (Aβ 1−42) induced changes has not been explored. Here we have investigated the acute effects of stereotaxic hippocampal Aβ 1−42 injection on specific glutamatergic receptors and transporters in the mouse hippocampus, using immunohistochemistry and confocal microscopy 3 days after Aβ 1−42 injection in aged male C57BL/6 mice, before the onset of neuronal cell death. We show that acute injection of Aβ 1−42 is sufficient to induce cognitive deficits 3 days post-injection. We also report no significant changes in glutamate receptor subunits GluA1, GluA2, VGluT1, and VGluT2 in response to acute injection of Aβ 1−42 when compared with the ACSF-vehicle injected mice. However, we observed increased expression in the DG hilus and ventral stratum (str.) granulosum, CA3 str. radiatum and str. oriens, and CA1 str. radiatum of the GluN1 subunit, and increased expression within the CA3 str. radiatum and decreased expression within the DG str. granulosum of the GluN2A subunit in Aβ 1−42 injected mice compared to NC, and a similar trend observed when compared to ACSF-injected mice. We also observed alterations in expression patterns of glutamatergic receptor subunits and transporters within specific layers of hippocampal subregions in response to a microinjection stimulus. These findings indicate that the pathological alterations in the glutamatergic system observed in AD are likely to be partially a result of both acute and chronic exposure to Aβ 1−42 and implies a much more complex circuit mechanism associated with glutamatergic dysfunction than simply glutamate-mediated excitotoxic neuronal death.

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Loss of F-box Only Protein 2 (Fbxo2) Disrupts Levels and Localization of Select NMDA Receptor Subunits, and Promotes Aberrant Synaptic Connectivity

Cited by 39 publications

References 78 publications

nArgBP2 regulates excitatory synapse formation by controlling dendritic spine morphology

nArgBP2 regulates excitatory synapse formation by controlling dendritic spine morphology

Evidence of altered depression and dementia‐related proteins in the brains of young rats after ovariectomy

The Acute Effects of Amyloid-Beta1–42 on Glutamatergic Receptor and Transporter Expression in the Mouse Hippocampus

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