Metabolic shift induced by systemic activation of T cells in PD-1-deficient mice perturbs brain monoamines and emotional behavior.

T cells reorganize their metabolic profiles after being activated, but the systemic metabolic effect of sustained activation of the immune system has remained unexplored. Here we report that augmented T cell responses in Pdcd1-/- mice, which lack the inhibitory receptor PD-1, induced a metabolic serum signature characterized by depletion of amino acids. We found that the depletion of amino acids in serum was due to the accumulation of amino acids in activated Pdcd1-/- T cells in the lymph nodes. A systemic decrease in tryptophan and tyrosine led to substantial deficiency in the neurotransmitters serotonin and dopamine in the brain, which resulted in behavioral changes dominated by anxiety-like behavior and exacerbated fear responses. Together these data indicate that excessive activation of T cells causes a systemic metabolomic shift with consequences that extend beyond the immune system.

Sex-dependent differences in the ability of nicotine to modulate discrimination learning and cognitive flexibility in mice.

Nicotine, an addictive compound found in tobacco, functions as an agonist of nicotinic acetylcholine receptors (nAChRs) in the brain. Interestingly, nicotine has been reported to act as a cognitive enhancer in both human subjects and experimental animals. However, its effects in animal studies have not always been consistent, and sex differences have been identified in the effects of nicotine on several behaviors. Specifically, the role that sex plays in modulating the effects of nicotine on discrimination learning and cognitive flexibility in rodents is still unclear. Here, we evaluated sex-dependent differences in the effect of daily nicotine intraperitoneal (i.p.) administration at various doses (0.125, 0.25, and 0.5 mg/kg) on visual discrimination (VD) learning and reversal (VDR) learning in mice. In male mice, 0.5 mg/kg nicotine significantly improved performance in the VDR, but not the VD, task, while 0.5 mg/kg nicotine significantly worsened performance in the VD, but not VDR task in female mice. Furthermore, 0.25 mg/kg nicotine significantly worsened performance in the VD and VDR task only in female mice. Next, to investigate the cellular mechanisms that underlie the sex difference in the effects of nicotine on cognition, transcriptomic analyses were performed focusing on the medial prefrontal cortex tissue samples from male and female mice that had received continuous administration of nicotine for 3 or 18 days. As a result of pathway enrichment analysis and protein-protein interaction analysis using gene sets of differentially expressed genes, decreased expression of postsynaptic-related genes in males and increased expression of innate immunity-related genes in females were identified as possible molecular mechanisms related to sex differences in the effects of nicotine on cognition in discrimination learning and cognitive flexibility. Our result suggests that nicotine modulates cognitive function in a sex-dependent manner by alternating the expression of specific gene sets in the medial prefrontal cortex.

Behavioral and neurological effects of Vrk1 deficiency in zebrafish.

Vaccinia-related kinase 1 (VRK1) is a serine/threonine kinase, for which mutations have been reported cause to neurodegenerative diseases, including spinal muscular atrophy, characterized by microcephaly, motor dysfunction, and impaired cognitive function, in humans. Partial Vrk1 knockdown in mice has been associated with microcephaly and impaired motor function. However, the pathophysiological relationship between VRK1 and neurodegenerative disorders and the precise mechanism of VRK1-related microcephaly and motor function deficits have not been fully investigated. To address this, in this study, we established vrk1-deficient (vrk1-/-) zebrafish and found that they show mild microcephaly and impaired motor function with a low brain dopamine content. Furthermore, vrk1-/- zebrafish exhibited decreased cell proliferation, defects in nuclear envelope formation, and heterochromatin formation in the brain. To our knowledge, this is the first report demonstrating the important role of VRK1 in microcephaly and motor dysfunction in vivo using vrk1-/- zebrafish. These findings contribute to elucidating the pathophysiological mechanisms underlying VRK1-mediated neurodegenerative diseases associated with microcephaly.

Vrk2 deficiency elicits aggressive behavior in female zebrafish.

Vaccinia-related kinase 2 (VRK2) is a serine/threonine kinase initially identified in highly proliferative cells such as thymocytes and fetal liver cells, and it is involved in cell proliferation and survival. VRK2 is also expressed in the brain; however, its molecular function in the central nervous system is mostly unknown. Many genome-wide association studies (GWASs) have reported that VRK2 is a potential candidate molecule for neuropsychiatric diseases such as schizophrenia in humans. However, the pathophysiological relationship between VRK2 and neuropsychiatric disorders has not been fully investigated. In this study, we evaluated vrk2-deficient (vrk2-/- ) zebrafish and found that vrk2-/- female zebrafish showed aggressive behavior and different social preference compared with control (vrk2+/+ ) zebrafish, with low gamma-aminobutyric acid (GABA) content in the brain and high density of neuronal dendrites when compared to vrk2+/+ zebrafish. These findings suggest that female vrk2-/- zebrafish were indeed a model of malbehavior characterized by aggression and social interaction, which can be attributed to the low levels of GABA content in their brain.

Regulation of sensorimotor gating via Disc1/Huntingtin-mediated Bdnf transport in the cortico-striatal circuit.

Sensorimotor information processing underlies normal cognitive and behavioral traits and has classically been evaluated through prepulse inhibition (PPI) of a startle reflex. PPI is a behavioral dimension deregulated in several neurological and psychiatric disorders, yet the mechanisms underlying the cross-diagnostic nature of PPI deficits across these conditions remain to be understood. To identify circuitry mechanisms for PPI, we performed circuitry recording over the prefrontal cortex and striatum, two brain regions previously implicated in PPI, using wild-type (WT) mice compared to Disc1-locus-impairment (LI) mice, a model representing neuropsychiatric conditions. We demonstrated that the corticostriatal projection regulates neurophysiological responses during the PPI testing in WT, whereas these circuitry responses were disrupted in Disc1-LI mice. Because our biochemical analyses revealed attenuated brain-derived neurotrophic factor (Bdnf) transport along the corticostriatal circuit in Disc1-LI mice, we investigated the potential role of Bdnf in this circuitry for regulation of PPI. Virus-mediated delivery of Bdnf into the striatum rescued PPI deficits in Disc1-LI mice. Pharmacologically augmenting Bdnf transport by chronic lithium administration, partly via phosphorylation of Huntingtin (Htt) serine-421 and its integration into the motor machinery, restored striatal Bdnf levels and rescued PPI deficits in Disc1-LI mice. Furthermore, reducing the cortical Bdnf expression negated this rescuing effect of lithium, confirming the key role of Bdnf in lithium-mediated PPI rescuing. Collectively, the data suggest that striatal Bdnf supply, collaboratively regulated by Htt and Disc1 along the corticostriatal circuit, is involved in sensorimotor gating, highlighting the utility of dimensional approach in investigating pathophysiological mechanisms across neuropsychiatric disorders.

Preliminary study of the social withdrawal (hikikomori) spectrum in French adolescents: focusing on the differences in pathology and related factors compared with Japanese adolescents.

BACKGROUND: Social withdrawal (hikikomori) has become an internationally recognized phenomenon, but its pathology and related factors are not yet fully known. We previously conducted a statistical case-control study on adolescent patients with hikikomori in Japan, which revealed the non-specificity of pathology in patients with hikikomori. Further, environmental factors, such as the lack of communication between parents and Internet overuse, were found to be significant predictors of hikikomori severity. Here, we aimed to conduct a similar preliminary case-control study in France and to compare the results with those from the study conducted in Japan. METHODS: Parents of middle school students who underwent psychiatric outpatient treatment for hikikomori (n = 10) and control group parents (n = 115) completed the Child Behavior Checklist to evaluate their child's psychopathological characteristics and the Parental Assessment of Environment and Hikikomori Severity Scales, as in our previous study in Japan. We compared the descriptive statistics and intergroup differences in France with those from the previous study conducted in Japan. In the multiple regression analysis to find predictors of hikikomori severity in French and also Japanese subjects, the same dependent and independent variables were chosen for the present study (both differed from the previous study). These were used in order to make accurate intercountry comparisons. RESULTS: The comparisons revealed no differences in the pathology of hikikomori between Japan and France. Specifically, both studies found similarly increased scores for all symptom scales, with no specific bias. However, the statistical predictors of hikikomori severity in France (lack of communication between parents and child and lack of communication with the community) differed from those in Japan (lack of communication between parents). CONCLUSION: Hikikomori in Japan and France could be considered essentially the same phenomenon; moreover, our findings demonstrated the universal non-specificity and unbiasedness of the hikikomori pathology. This suggests that hikikomori is not a single clinical category with a specific psychopathology; instead, it is a common phenotype with various underlying pathologies. However, different strategies may be required in each country to prevent the onset and progression of hikikomori.

Trends in big data analyses by multicenter collaborative translational research in psychiatry.

The underlying pathologies of psychiatric disorders, which cause substantial personal and social losses, remain unknown, and their elucidation is an urgent issue. To clarify the core pathological mechanisms underlying psychiatric disorders, in addition to laboratory-based research that incorporates the latest findings, it is necessary to conduct large-sample-size research and verify reproducibility. For this purpose, it is critical to conduct multicenter collaborative research across various fields, such as psychiatry, neuroscience, molecular biology, genomics, neuroimaging, cognitive science, neurophysiology, psychology, and pharmacology. Moreover, collaborative research plays an important role in the development of young researchers. In this respect, the Enhancing Neuroimaging Genetics through Meta-Analysis (ENIGMA) consortium and Cognitive Genetics Collaborative Research Organization (COCORO) have played important roles. In this review, we first overview the importance of multicenter collaborative research and our target psychiatric disorders. Then, we introduce research findings on the pathophysiology of psychiatric disorders from neurocognitive, neurophysiological, neuroimaging, genetic, and basic neuroscience perspectives, focusing mainly on the findings obtained by COCORO. It is our hope that multicenter collaborative research will contribute to the elucidation of the pathological basis of psychiatric disorders.

Modeling a human CLP1 mutation in mouse identifies an accumulation of tyrosine pre-tRNA fragments causing pontocerebellar hypoplasia type 10.

Cleavage factor polyribonucleotide kinase subunit 1 (CLP1), an RNA kinase, plays essential roles in protein complexes involved in the 3'-end formation and polyadenylation of mRNA and the tRNA splicing endonuclease complex, which is involved in precursor tRNA splicing. The mutation R140H in human CLP1 causes pontocerebellar hypoplasia type 10 (PCH10), which is characterized by microcephaly and axonal peripheral neuropathy. Previously, we reported that RNA fragments derived from isoleucine pre-tRNA introns (Ile-introns) accumulate in fibroblasts of patients with PCH10. Therefore, it has been suggested that this intronic RNA fragment accumulation may trigger PCH10 onset. However, the molecular mechanism underlying PCH10 pathogenesis remains elusive. Thus, we generated knock-in mutant mice that harbored a CLP1 mutation consistent with R140H. As expected, these mice showed progressive loss of the upper motor neurons, resulting in impaired locomotor activity, although the phenotype was milder than that of the human variant. Mechanistically, we found that the R140H mutation causes intracellular accumulation of Ile-introns derived from isoleucine pre-tRNAs and 5' tRNA fragments derived from tyrosine pre-tRNAs, suggesting that these two types of RNA fragments were cooperatively or independently involved in the onset and progression of the disease. Taken together, the CLP1-R140H mouse model provided new insights into the pathogenesis of neurodegenerative diseases, such as PCH10, caused by genetic mutations in tRNA metabolism-related molecules.

Combined pattern of childhood psycho-behavioral characteristics in patients with schizophrenia: a retrospective study in Japan.

BACKGROUND: Although epidemiological and genetic studies have provided scientific evidence that places schizophrenia into the framework of early neurodevelopmental disorders, the psycho-behavioral characteristics of children that later go on to develop schizophrenia have not been sufficiently clarified. This study aimed to retrospectively identify characteristics specific to patients with schizophrenia during childhood via their guardians' reporting of these characteristics. METHODS: Participants included 54 outpatients with schizophrenia in their twenties who fulfilled DSM-IV-TR criteria. Additionally, 192 normal healthy subjects participated as sex- and age-matched controls. The guardians of all participants were recruited to rate participants' childhood characteristics from 6 to 8 years of age on a modified version of the Child Behavior Checklist (CBCL), which was used as a retrospective assessment questionnaire. Using t-tests, logistic regression, and Receiver Operating Characteristic (ROC) curve analysis, we estimated the psycho-behavioral characteristics specific to schizophrenia during childhood. Using the obtained logistic regression model, we prototyped a risk-predicting algorithm based on the CBCL scores. RESULTS: Among the eight CBCL subscale t-scores, "withdrawn" (p = 0.002), "thought problems" (p = 0.001), and "lack of aggressive behavior" (p = 0.002) were each significantly associated with the later diagnosis of schizophrenia, although none of these mean scores were in the clinical range at the time of childhood. The algorithm of the logistic regression model, based on eight CBCL subscales, had an area under the ROC curve of 82.8% (95% CI: 76-89%), which indicated that this algorithm's prediction of late development of schizophrenia has moderate accuracy. CONCLUSIONS: The results suggest that according to guardian reports, participants showed psycho-behavioral characteristics during childhood, different to those of healthy controls, which could be predictive of the later development of schizophrenia. Our newly developed algorithm is available to use in future studies to further test its validity.

Identifying Social Withdrawal (Hikikomori) Factors in Adolescents: Understanding the Hikikomori Spectrum.

Hikikomori is a Japanese term for social withdrawal, ranging from complete inability to venture outdoors to preferring to stay inside. The prevalence of hikikomori is high, up to 1.2% of the Japanese population, but only few studies have examined its emergence in adolescents. Therefore, we sought to identify environmental and psycho-behavioral characteristics related to hikikomori during adolescence. Parents of middle school students who underwent psychiatric outpatient treatment for hikikomori (n = 20) and control group parents (n = 88) completed the Child Behavior Checklist to evaluate their child's psycho-behavioral characteristics and novel scales to evaluate environmental characteristics and hikikomori severity. Scores for all eight Child Behavior Checklist subscales were significantly higher in the experimental group. Multiple regression analysis revealed that "anxious/depressed," "somatic complaints," "lack of communication between parents" and "overuse of the Internet" were significant predictors of hikikomori severity. These findings can help identify individuals who are at risk of developing hikikomori.

Dopamine D2L Receptor Deficiency Causes Stress Vulnerability through 5-HT1A Receptor Dysfunction in Serotonergic Neurons.

Mental disorders are caused by genetic and environmental factors. We here show that deficiency of an isoform of dopamine D2 receptor (D2R), D2LR, causes stress vulnerability in mouse. This occurs through dysfunction of serotonin [5-hydroxytryptamine (5-HT)] 1A receptor (5-HT1AR) on serotonergic neurons in the mouse brain. Exposure to forced swim stress significantly increased anxiety- and depressive-like behaviors in D2LR knock-out (KO) male mice compared with wild-type mice. Treatment with 8-OH-DPAT, a 5-HT1AR agonist, failed to alleviate the stress-induced behaviors in D2LR-KO mice. In forced swim-stressed D2LR-KO mice, 5-HT efflux in the medial prefrontal cortex was elevated and the expression of genes related to 5-HT levels was upregulated by the transcription factor PET1 in the dorsal raphe nucleus. Notably, D2LR formed a heteromer with 5-HT1AR in serotonergic neurons, thereby suppressing 5-HT1AR-activated G-protein-activated inwardly rectifying potassium conductance in D2LR-KO serotonergic neurons. Finally, D2LR overexpression in serotonergic neurons in the dorsal raphe nucleus alleviated stress vulnerability observed in D2LR-KO mice. Together, we conclude that disruption of the negative feedback regulation by the D2LR/5-HT1A heteromer causes stress vulnerability.SIGNIFICANCE STATEMENT Etiologies of mental disorders are multifactorial, e.g., interactions between genetic and environmental factors. In this study, using a mouse model, we showed that genetic depletion of an isoform of dopamine D2 receptor, D2LR, causes stress vulnerability associated with dysfunction of serotonin 1A receptor, 5-HT1AR in serotonergic neurons. The D2LR/5-HT1AR inhibitory G-protein-coupled heteromer may function as a negative feedback regulator to suppress psychosocial stress.

Lithium ion adduction enables UPLC-MS/MS-based analysis of multi-class 3-hydroxyl group-containing keto-steroids.

Steroids that contain a 3-hydroxyl group (3-OH steroids) are widely distributed in nature. During analysis with ESI-MS, they easily become dehydrated while in the protonated form, resulting in the production of several precursor ions and leading to low sensitivity of detection. To address this analytical challenge, here, we developed a method for the quantitation of 3-OH steroids by LC-MS/MS coupled with post-column addition of lithium (Li) ions to the mobile phase. The Li ion has a high affinity for the keto group of steroids, stabilizing their structures during ionization and permitting detection of analytes exclusively as the lithiated form. This not only improved the intensities of the precursor ions, but also promoted the formation of typical lithiated fragment ions. This improvement made the quantitation by multiple reaction monitoring more sensitive and reliable, as evidenced by 1.53-188 times enhanced detection sensitivity of 13 steroids that contained at least one keto and two hydroxyl groups or one keto and one 5-olefinic double bond, among 16 different 3-OH steroids. We deployed our newly developed method for profiling steroids in mouse brain tissue and identified six steroids in one tissue sample. Among these, 16-hydroxyestrone, tetrahydrocorticosterone, and 17α-hydroxypregnenolone were detected for the first time in the mouse brain. In summary, the method described here enables the detection of lithiated steroids by LC-MS/MS, including three 3-OH steroids not previously reported in the mouse brain. We anticipate that this new method may allow the determination of 3-OH steroids in different brain regions.

Ulk2 controls cortical excitatory-inhibitory balance via autophagic regulation of p62 and GABAA receptor trafficking in pyramidal neurons.

Autophagy plays an essential role in intracellular degradation and maintenance of cellular homeostasis in all cells, including neurons. Although a recent study reported a copy number variation of Ulk2, a gene essential for initiating autophagy, associated with a case of schizophrenia (SZ), it remains to be studied whether Ulk2 dysfunction could underlie the pathophysiology of the disease. Here we show that Ulk2 heterozygous (Ulk2+/-) mice have upregulated expression of sequestosome-1/p62, an autophagy-associated stress response protein, predominantly in pyramidal neurons of the prefrontal cortex (PFC), and exhibit behavioral deficits associated with the PFC functions, including attenuated sensorimotor gating and impaired cognition. Ulk2+/- neurons showed imbalanced excitatory-inhibitory neurotransmission, due in part to selective down-modulation of gamma-aminobutyric acid (GABA)A receptor surface expression in pyramidal neurons. Genetically reducing p62 gene dosage or suppressing p62 protein levels with an autophagy-inducing agent restored the GABAA receptor surface expression and rescued the behavioral deficits in Ulk2+/- mice. Moreover, expressing a short peptide that specifically interferes with the interaction of p62 and GABAA receptor-associated protein, a protein that regulates endocytic trafficking of GABAA receptors, also restored the GABAA receptor surface expression and rescued the behavioral deficits in Ulk2+/- mice. Thus, the current study reveals a novel mechanism linking deregulated autophagy to functional disturbances of the nervous system relevant to SZ, through regulation of GABAA receptor surface presentation in pyramidal neurons.

Exosc2 deficiency leads to developmental disorders by causing a nucleotide pool imbalance in zebrafish.

Exosc2 is one of the components of the exosome complex involved in RNA 3' end processing and degradation of various RNAs. Recently, EXOSC2 mutation has been reported in German families presenting short stature, hearing loss, retinitis pigmentosa, and premature aging. However, the in vivo function of EXOSC2 has been elusive. Herein, we generated Exosc2 knockout (exosc2-/-) zebrafish that showed larval lethality 13 days post fertilization, with microcephaly, loss of spinal motor neurons, myelin deficiency, and retinitis pigmentosa. Mechanistically, Exosc2 deficiency caused impaired mRNA turnover, resulting in a nucleotide pool imbalance. Rapamycin, which modulated mRNA turnover by inhibiting the mTOR pathway, improved nucleotide pool imbalance in exosc2-/- zebrafish, resulting in prolonged survival and partial rescue of neuronal defects. Taken together, our findings offer new insights into the disease pathogenesis caused by Exosc2 deficiency, and might help explain fundamental molecular mechanisms in neuronal diseases, such as Alzheimer's disease, amyotrophic lateral sclerosis, and spinal muscular atrophy.

Role of basal ganglia neurocircuitry in the pathology of psychiatric disorders.

Over the last few decades, advances in human and animal-based techniques have greatly enhanced our understanding of the neural mechanisms underlying psychiatric disorders. Many of these studies have indicated connectivity between and alterations within basal ganglia structures to be particularly pertinent to the development of symptoms associated with several of these disorders. Here we summarize the connectivity, molecular composition, and function of sites within basal ganglia neurocircuits. Then we review the current literature from both human and animal studies concerning altered basal ganglia function in five common psychiatric disorders: obsessive-compulsive disorder, substance-related and addiction disorders, major depressive disorder, generalized anxiety disorder, and schizophrenia. Finally, we present a model based upon the findings of these studies that highlights the striatum as a particularly attractive target for restoring normal function to basal ganglia neurocircuits altered within psychiatric disorder patients.

Role of PKA signaling in D2 receptor-expressing neurons in the core of the nucleus accumbens in aversive learning.

The nucleus accumbens (NAc) serves as a key neural substrate for aversive learning and consists of two distinct subpopulations of medium-sized spiny neurons (MSNs). The MSNs of the direct pathway (dMSNs) and the indirect pathway (iMSNs) predominantly express dopamine (DA) D1 and D2 receptors, respectively, and are positively and negatively modulated by DA transmitters via Gs- and Gi-coupled cAMP-dependent protein kinase A (PKA) signaling cascades, respectively. In this investigation, we addressed how intracellular PKA signaling is involved in aversive learning in a cell type-specific manner. When the transmission of either dMSNs or iMSNs was unilaterally blocked by pathway-specific expression of transmission-blocking tetanus toxin, infusion of PKA inhibitors into the intact side of the NAc core abolished passive avoidance learning toward an electric shock in the indirect pathway-blocked mice, but not in the direct pathway-blocked mice. We then examined temporal changes in PKA activity in dMSNs and iMSNs in behaving mice by monitoring Förster resonance energy transfer responses of the PKA biosensor with the aid of microendoscopy. PKA activity was increased in iMSNs and decreased in dMSNs in both aversive memory formation and retrieval. Importantly, the increased PKA activity in iMSNs disappeared when aversive memory was prevented by keeping mice in the conditioning apparatus. Furthermore, the increase in PKA activity in iMSNs by aversive stimuli reflected facilitation of aversive memory retention. These results indicate that PKA signaling in iMSNs plays a critical role in both aversive memory formation and retention.

Nucleus accumbens dopamine D2-receptor expressing neurons control behavioral flexibility in a place discrimination task in the IntelliCage.

Considerable evidence has demonstrated a critical role for the nucleus accumbens (NAc) in the acquisition and flexibility of behavioral strategies. These processes are guided by the activity of two discrete neuron types, dopamine D1- or D2-receptor expressing medium spiny neurons (D1-/D2-MSNs). Here we used the IntelliCage, an automated group-housing experimental cage apparatus, in combination with a reversible neurotransmission blocking technique to examine the role of NAc D1- and D2-MSNs in the acquisition and reversal learning of a place discrimination task. We demonstrated that NAc D1- and D2-MSNs do not mediate the acquisition of the task, but that suppression of activity in D2-MSNs impairs reversal learning and increased perseverative errors. Additionally, global knockout of the dopamine D2L receptor isoform produced a similar behavioral phenotype to D2-MSN-blocked mice. These results suggest that D2L receptors and NAc D2-MSNs act to suppress the influence of previously correct behavioral strategies allowing transfer of behavioral control to new strategies.

[Basal Ganglia Circuit Mechanisms in Cognitive Learning].

The nucleus accumbens (NAc), the ventral part of the striatum, plays a critical role in motivation, learning, and cognition in the basal ganglia circuit. Outputs of the NAc are transmitted through two parallel direct and indirect pathways. We have developed a reversible neurotransmission blocking (RNB) technique, in which neurotransmission of each pathway in the NAc is selectively blocked by specific expression of a transmission-blocking tetanus toxin (D-RNB or I-RNB). In visual cue and reversal tasks in the cross-maze, the NAc direct pathway was critical for learning acquisition. In contrast, the NAc indirect pathway was essential not only for learning flexibility, but also for subsequent acquisition of a new strategy. In place discrimination and serial reversal learning tasks in the IntelliCage, we showed that the NAc indirect pathway controls behavioral flexibility by suppressing the influence of previously correct behavioral strategies during the reversal stage. These basal ganglia circuit mechanisms provide new insight into pathophysiologies associated with compulsive behaviors, including addiction and obesity.

Nuclear-translocated Glyceraldehyde-3-phosphate Dehydrogenase Promotes Poly(ADP-ribose) Polymerase-1 Activation during Oxidative/Nitrosative Stress in Stroke.

In addition to its role in DNA repair, nuclear poly(ADP-ribose) polymerase-1 (PARP-1) mediates brain damage when it is over-activated by oxidative/nitrosative stress. Nonetheless, it remains unclear how PARP-1 is activated in neuropathological contexts. Here we report that PARP-1 interacts with a pool of glyceradehyde-3-phosphate dehydrogenase (GAPDH) that translocates into the nucleus under oxidative/nitrosative stress both in vitro and in vivo. A well conserved amino acid at the N terminus of GAPDH determines its protein binding with PARP-1. Wild-type (WT) but not mutant GAPDH, that lacks the ability to bind PARP-1, can promote PARP-1 activation. Importantly, disrupting this interaction significantly diminishes PARP-1 overactivation and protects against both brain damage and neurological deficits induced by middle cerebral artery occlusion/reperfusion in a rat stroke model. Together, these findings suggest that nuclear GAPDH is a key regulator of PARP-1 activity, and its signaling underlies the pathology of oxidative/nitrosative stress-induced brain damage including stroke.