All Publications

  • A positively tuned voltage indicator for extended electrical recordings in the brain. Nature methods Evans, S. W., Shi, D., Chavarha, M., Plitt, M. H., Taxidis, J., Madruga, B., Fan, J. L., Hwang, F., van Keulen, S. C., Suomivuori, C., Pang, M. M., Su, S., Lee, S., Hao, Y. A., Zhang, G., Jiang, D., Pradhan, L., Roth, R. H., Liu, Y., Dorian, C. C., Reese, A. L., Negrean, A., Losonczy, A., Makinson, C. D., Wang, S., Clandinin, T. R., Dror, R. O., Ding, J. B., Ji, N., Golshani, P., Giocomo, L. M., Bi, G., Lin, M. Z. 2023; 20 (7): 1104-1113


    Genetically encoded voltage indicators (GEVIs) enable optical recording of electrical signals in the brain, providing subthreshold sensitivity and temporal resolution not possible with calcium indicators. However, one- and two-photon voltage imaging over prolonged periods with the same GEVI has not yet been demonstrated. Here, we report engineering of ASAP family GEVIs to enhance photostability by inversion of the fluorescence-voltage relationship. Two of the resulting GEVIs, ASAP4b and ASAP4e, respond to 100-mV depolarizations with ≥180% fluorescence increases, compared with the 50% fluorescence decrease of the parental ASAP3. With standard microscopy equipment, ASAP4e enables single-trial detection of spikes in mice over the course of minutes. Unlike GEVIs previously used for one-photon voltage recordings, ASAP4b and ASAP4e also perform well under two-photon illumination. By imaging voltage and calcium simultaneously, we show that ASAP4b and ASAP4e can identify place cells and detect voltage spikes with better temporal resolution than commonly used calcium indicators. Thus, ASAP4b and ASAP4e extend the capabilities of voltage imaging to standard one- and two-photon microscopes while improving the duration of voltage recordings.

    View details for DOI 10.1038/s41592-023-01913-z

    View details for PubMedID 37429962

  • Kinase pathway inhibition restores PSD95 induction in neurons lacking fragile X mental retardation protein. Proceedings of the National Academy of Sciences of the United States of America Yang, Y. n., Geng, Y. n., Jiang, D. n., Ning, L. n., Kim, H. J., Jeon, N. L., Lau, A. n., Chen, L. n., Lin, M. Z. 2019


    Fragile X syndrome (FXS) is the leading monogenic cause of autism and intellectual disability. FXS is caused by loss of expression of fragile X mental retardation protein (FMRP), an RNA-binding protein that regulates translation of numerous mRNA targets, some of which are present at synapses. While protein synthesis deficits have long been postulated as an etiology of FXS, how FMRP loss affects distributions of newly synthesized proteins is unknown. Here we investigated the role of FMRP in regulating expression of new copies of the synaptic protein PSD95 in an in vitro model of synaptic plasticity. We find that local BDNF application promotes persistent accumulation of new PSD95 at stimulated synapses and dendrites of cultured neurons, and that this accumulation is absent in FMRP-deficient mouse neurons. New PSD95 accumulation at sites of BDNF stimulation does not require known mechanisms regulating FMRP-mRNA interactions but instead requires the PI3K-mTORC1-S6K1 pathway. Surprisingly, in FMRP-deficient neurons, BDNF induction of new PSD95 accumulation can be restored by mTORC1-S6K1 blockade, suggesting that constitutively high mTORC1-S6K1 activity occludes PSD95 regulation by BDNF and that alternative pathways exist to mediate induction when mTORC1-S6K1 is inhibited. This study provides direct evidence for deficits in local protein synthesis and accumulation of newly synthesized protein in response to local stimulation in FXS, and supports mTORC1-S6K1 pathway inhibition as a potential therapeutic approach for FXS.

    View details for DOI 10.1073/pnas.1812056116

    View details for PubMedID 31118285

  • GABAergic deficits and schizophrenia-like behaviors in a mouse model carrying patient-derived neuroligin-2 R215H mutation. Molecular brain Jiang, D. Y., Wu, Z., Forsyth, C. T., Hu, Y., Yee, S. P., Chen, G. 2018; 11 (1): 31


    Schizophrenia (SCZ) is a severe mental disorder characterized by delusion, hallucination, and cognitive deficits. We have previously identified from schizophrenia patients a loss-of-function mutation Arg215→His215 (R215H) of neuroligin 2 (NLGN2) gene, which encodes a cell adhesion molecule critical for GABAergic synapse formation and function. Here, we generated a novel transgenic mouse line with neuroligin-2 (NL2) R215H mutation. The single point mutation caused a significant loss of NL2 protein in vivo, reduced GABAergic transmission, and impaired hippocampal activation. Importantly, R215H KI mice displayed anxiety-like behavior, impaired pre-pulse inhibition (PPI), cognition deficits and abnormal stress responses, recapitulating several key aspects of schizophrenia-like behaviors. Our results demonstrate a significant impact of a single point mutation NL2 R215H on brain functions, providing a novel animal model for the study of schizophrenia and neuropsychiatric disorders.

    View details for DOI 10.1186/s13041-018-0375-6

    View details for PubMedID 29859117

    View details for PubMedCentralID PMC5984814

  • DREADD in parvalbumin interneurons of the dentate gyrus modulates anxiety, social interaction and memory extinction. Current molecular medicine Zou, D., Chen, L., Deng, D., Jiang, D., Dong, F., McSweeney, C., Zhou, Y., Liu, L., Chen, G., Wu, Y., Mao, Y. 2016; 16 (1): 91-102


    Parvalbumin (PV)-positive interneurons in the hippocampus play a critical role in animal memory, such as spatial working memory. However, how PV-positive interneurons in the subregions of the hippocampus affect animal behaviors remains poorly defined. Here, we achieved specific and reversible activation of PV-positive interneurons using designer receptors exclusively activated by designer drugs (DREADD) technology. Inducible DREADD expression was demonstrated in vitro in cultured neurons, in which co-transfection of the hM3D-Gq-mCherry vector with a Cre plasmid resulted in a cellular response to hM3Dq ligand clozapine-N-oxide (CNO) stimulation. In addition, the dentate gyrus (DG) of PV-Cre mice received bilateral injection of control lentivirus or lentivirus expressing double floxed hM3D-Gq-mCherry. Selective activation of PV-positive interneurons in the DG did not affect locomotor activity or depression-related behavior in mice. Interestingly, stimulation of PV-positive interneurons induced an anxiolytic effect. Activation of PVpositive interneurons appears to impair social interaction to novelty, but has no effect on social motivation. However, this defect is likely due to the anxiolytic effect as the exploratory behavior of mice expressing hM3DGq is significantly increased. Mice expressing hM3D-Gq did not affect novel object recognition. Activation of PV-positive interneurons in the DG maintains intact cued and contextual fear memory but facilitates fear extinction. Collectively, our results demonstrated that proper control of PV interneurons activity in the DG is critical for regulation of the anxiety, social interaction and fear extinction. These results improve our fundamental understanding of the physiological role of PV-positive interneurons in the hippocampus.

    View details for DOI 10.2174/1566524016666151222150024

    View details for PubMedID 26733123

    View details for PubMedCentralID PMC4997952

  • Homeostatic competition between phasic and tonic inhibition. The Journal of biological chemistry Wu, X., Huang, L., Wu, Z., Zhang, C., Jiang, D., Bai, Y., Wang, Y., Chen, G. 2013; 288 (35): 25053-25065


    The GABAA receptors are the major inhibitory receptors in the brain and are localized at both synaptic and extrasynaptic membranes. Synaptic GABAA receptors mediate phasic inhibition, whereas extrasynaptic GABAA receptors mediate tonic inhibition. Both phasic and tonic inhibitions regulate neuronal activity, but whether they regulate each other is not very clear. Here, we investigated the functional interaction between synaptic and extrasynaptic GABAA receptors through various molecular manipulations. Overexpression of extrasynaptic α6β3δ-GABAA receptors in mouse hippocampal pyramidal neurons significantly increased tonic currents. Surprisingly, the increase of tonic inhibition was accompanied by a dramatic reduction of the phasic inhibition, suggesting a possible homeostatic regulation of the total inhibition. Overexpressing the α6 subunit alone induced an up-regulation of δ subunit expression and suppressed phasic inhibition similar to overexpressing the α6β3δ subunits. Interestingly, blocking all GABAA receptors after overexpressing α6β3δ receptors could not restore the synaptic GABAergic transmission, suggesting that receptor activation is not required for the homeostatic interplay. Furthermore, insertion of a gephyrin-binding-site (GBS) into the α6 and δ subunits recruited α6(GBS)β3δ(GBS) receptors to postsynaptic sites but failed to rescue synaptic GABAergic transmission. Thus, it is not the positional effect of extrasynaptic α6β3δ receptors that causes the down-regulation of phasic inhibition. Overexpressing α5β3γ2 subunits similarly reduced synaptic GABAergic transmission. We propose a working model that both synaptic and extrasynaptic GABAA receptors may compete for limited receptor slots on the plasma membrane to maintain a homeostatic range of the total inhibition.

    View details for DOI 10.1074/jbc.M113.491464

    View details for PubMedID 23839941

    View details for PubMedCentralID PMC3757170

  • An EJC factor RBM8a regulates anxiety behaviors. Current molecular medicine Alachkar, A., Jiang, D., Harrison, M., Zhou, Y., Chen, G., Mao, Y. 2013; 13 (6): 887-99


    Neuroplasticity depends on the precise timing of gene expression, which requires accurate control of mRNA stability and rapid elimination of abnormal mRNA. Nonsense-mediated mRNA decay (NMD) is an RNA surveillance mechanism that ensures the speedy degradation of mRNAs carrying premature termination codons (PTCs). This mechanism relies on several key Exon Junction Complex (EJC) factors to distinguish PTCs from normal stop codons. NMD degrades not only aberrant transcripts carrying PTCs, but also normal transcripts harboring a normal stop codon [1]. Intriguingly, mutations in an NMD factor, Upf3b, have been found in patients with autism [2, 3]. A binding partner of Upf3b, RBM8a, is located in the 1q21.1 copy-number variation (CNV) associated with mental retardation, autism [4], schizophrenia [5], and microcephaly [6]. However, the functions of EJC factors and their roles in behavioral regulation are still elusive. RBM8a protein is a core component of the EJC that plays an important role in NMD. Recent genetic study indicated that RBM8a gain-of-function significantly associated with intellectual disability [7]. In this study we investigated the effect of RBM8a overexpression on affective behaviors in mice. Lentivirus expressing RBM8a was infused into the hippocampus of adult mice to conduct behavioral studies including social interaction, open field, elevated plus maze, and forced swimming tests. Our results showed that overexpression of RBM8a in the mouse dentate gyrus (DG) leads to increased anxiety-like behavior, abnormal social interaction and decreased immobile time in forced swimming test (FST). To examine the underlying mechanism, we found that overexpressing RBM8a in cultured primary neurons lead to significant higher frequency of miniature excitatory postsynaptic currents (mEPSCs). To explore the underlying mechanism of RBM8a mediated behavioral changes, RNA-immunoprecipitation (RNA-IP) detected that RBM8a binds to CaMK2, GluR1 and Egr1 mRNA, suggesting that RBM8a may target neuronal genes to regulate behaviors. This is the first study that demonstrates the key role of RBM8a on the emotional behaviors in mice. These results reveal new neural mechanisms by which NMD modulates behaviors and potentially provide a better understanding of pathophysiology underlying psychiatric disorders.

    View details for DOI 10.2174/15665240113139990019

    View details for PubMedID 23638902

  • Regulation of epileptiform activity by two distinct subtypes of extrasynaptic GABA(A) receptors MOLECULAR BRAIN Sun, Y., Wu, Z., Kong, S., Jiang, D., Pitre, A., Wang, Y., Chen, G. 2013; 6: 21


    GABAergic deficit is one of the major mechanisms underlying epileptic seizures. Previous studies have mainly focused on alterations of synaptic GABAergic inhibition during epileptogenesis. Recent work suggested that tonic inhibition may also play a role in regulating epileptogenesis, but the underlying mechanism is not well understood.We employed molecular and pharmacological tools to investigate the role of tonic inhibition during epileptogenesis both in vitro and in vivo. We overexpressed two distinct subtypes of extrasynaptic GABAA receptors, α5β3γ2 and α6β3δ receptors, in cultured hippocampal neurons. We demonstrated that overexpression of both α5β3γ2 and α6β3δ receptors enhanced tonic inhibition and reduced epileptiform activity in vitro. We then showed that injection of THIP (5 μM), a selective agonist for extrasynaptic GABAA receptors at low concentration, into rat brain also suppressed epileptiform burst activity and behavioral seizures in vivo. Mechanistically, we discovered that low concentration of THIP had no effect on GABAergic synaptic transmission and did not affect the basal level of action potentials, but significantly inhibited high frequency neuronal activity induced by epileptogenic agents.Our studies suggest that extrasynaptic GABAA receptors play an important role in controlling hyperexcitatory activity, such as that during epileptogenesis, but a less prominent role in modulating a low level of basal activity. We propose that tonic inhibition may play a greater role under pathological conditions than in physiological conditions in terms of modulating neural network activity.

    View details for DOI 10.1186/1756-6606-6-21

    View details for Web of Science ID 000318914200001

    View details for PubMedID 23634821

    View details for PubMedCentralID PMC3652748