Article

Ubiquitin-specific peptidase 46 (Usp46) regulates mouse immobile behavior in the tail suspension test through the GABAergic system.

Division of Biomodeling, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan.
PLoS ONE (Impact Factor: 3.53). 01/2012; 7(6):e39084. DOI: 10.1371/journal.pone.0039084
Source: PubMed

ABSTRACT The tail suspension test (TST) is widely recognized as a useful experimental paradigm for assessing antidepressant activity and depression-like behavior. We have previously identified ubiquitin-specific peptidase 46 (Usp46) as a quantitative trait gene responsible for decreasing immobility time in the TST in mice. This Usp46 mutation has a 3-bp deletion coding for lysine in the open reading frame, and we indicated that Usp46 is implicated in the regulation of the GABAergic system. However, it is not known precisely how the immobile behavior is regulated by the GABAergic system. Therefore, in the present study, we examined whether the immobility time is influenced by drugs affecting the action mediated by GABA(A) receptor using both 3-bp deleted (the Usp46 mutant) and null Usp46 (Usp46 KO) mice. Nitrazepam, an agonist at the benzodiazepine-binding site of the GABA(A) receptor, which potentiates the action of GABA, produced a dose-dependent increase in TST immobility time in the Usp46 mutant mice without affecting general behaviors. The Usp46 KO mice exhibited short immobility times comparable to the Usp46 mutant mice, which was also increased by nitrazepam administration. The effects of nitrazepam in the Usp46 mutant and KO mice were antagonized by flumazenil. These results indicate that the 3-bp deleted Usp46 mutation causes a loss-of-function phenotype, and that the GABA(A) receptor might participate in the regulation of TST immobility time.

0 Bookmarks
 · 
126 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We have previously identified which encodes for ubiquitin-specific peptidase 46, as a quantitative trait gene affecting the immobility time of mice in the tail suspension test (TST) and forced swimming test. The mutation that we identified was a 3-bp deletion coding for lysine (Lys 92), and mice with this mutation (MT mice), as well as KO mice exhibited shorter TST immobility times. Behavioral pharmacology suggests that the gamma aminobutyric acid A (GABA) receptor is involved in regulating TST immobility time. In order to understand how far controls behavioral phenotypes, which could be related to mental disorders in humans, we subjected MT and KO mice to multiple behavioral tests, including the open field test, ethanol preference test, ethanol-induced loss of righting reflex test, sucrose preference test, novelty-suppressed feeding test, marble burying test, and novel object recognition test. Although behavioral phenotypes of the MT and KO mice were not always identical, deficiency of significantly affected performance in all these tests. In the open field test, activity levels were lower in KO mice than wild type (WT) or MT mice. Both MT and KO mice showed lower ethanol preference and shorter recovery times after ethanol administration. Compared to WT mice, MT and KO mice exhibited decreased sucrose preference, took longer latency periods to bite pellets, and buried more marbles in the sucrose preference test, novelty-suppressed feeding test, and marble burying test, respectively. In the novel object recognition test, neither MT nor KO mice showed an increase in exploration of a new object 24 hours after training. These findings indicate that regulates a wide range of behavioral phenotypes that might be related to human mental disorders and provides insight into the function of USP46 deubiquitinating enzyme in the neural system.
    PLoS ONE 01/2013; 8(3):e58566. · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The deubiquitinating enzyme heterodimeric complex, USP1/UAF1, regulates the Fanconi Anemia DNA repair pathway. Absence of this complex leads to increased cellular levels of ubiquitinated FANCD2 (FANCD2-Ub) and ubiquitinated PCNA (PCNA-Ub). Mice deficient in the catalytic subunit of this complex, USP1, exhibit a Fanconi Anemia (FA)-like phenotype and have a cellular deficiency in homologous recombination (HR) repair. Here, we have characterized mice deficient in the UAF1 subunit. Uaf1(+/-) mice were small at birth and exhibited reduced fertility, thus resembling Usp1(-/-) mice. Unexpectedly, homozygous Uaf1(-/-) embryos died at day E7.5. These mutant embryos were small and developmentally retarded. As expected, Uaf1 deficiency in mice led to increased levels of cellular Fancd2-Ub and Pcna-Ub. Uaf1(+/-) MEFs exhibited profound chromosome instability, genotoxin hypersensitivity, and a significant defect in homologous recombination repair. Moreover, Uaf1(-/-) mouse embryonic stem cells (mESCs) showed chromosome instability, genotoxin hypersensitivity, and impaired Fancd2 foci assembly. Similar to USP1 knockdown, UAF1 knockdown in tumor cells caused suppression of tumor growth in vivo. Taken together, our data demonstrate the important regulatory role of the USP1/UAF1 complex in HR repair, through its regulation of the FANCD2-Ub and PCNA-Ub cellular pools.
    Molecular and cellular biology 09/2013; · 6.06 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ubiquitination has emerged as an essential signaling mechanism in eukaryotes. Deubiquitinases (DUBs) counteract the activities of the ubiquitination machinery and provide another level of control in cellular ubiquitination. Not surprisingly, DUBs are subjected to stringent regulations. Besides regulation by the noncatalytic domains present in the DUB sequences, DUB-interacting proteins are increasingly realized as essential regulators for DUB activity and function. This review focuses on DUBs that are associated with WD40-repeat proteins. Many human ubiquitin-specific proteases (USPs) were found to interact with WD40-repeat proteins, but little is known as to how this interaction regulates the activity and function of USPs. In recent years, significant progress has been made in understanding a prototypical WD40-repeat protein-containing DUB complex that comprises USP1 and USP1-associated factor 1 (UAF1). It has been shown that UAF1 activates USP1 through a potential active-site modulation, and the complex formation between USP1 and UAF1 is regulated by serine phosphorylation. Recently, human USPs have been recognized as a promising target class for inhibitor discovery. Small molecule inhibitors targeting several human USPs have been reported. USP1 is involved in two major DNA damage response pathways, DNA translesion synthesis and the Fanconi anemia pathway. Inhibiting the USP1/UAF1 deubiquitinase complex represents a new strategy to potentiate cancer cells to DNA-crosslinking agents and to overcome resistance that has plagued clinical cancer chemotherapy. The progress in inhibitor discovery against USPs and the WD40-repeat protein-containing USP complex will be discussed.
    Cell biochemistry and biophysics 06/2013; · 3.34 Impact Factor

Full-text (2 Sources)

View
1 Download
Available from