Histone demethylase PHF2 activates CREB and promotes memory consolidation.

Long-term memory formation is attributed to experience-dependent gene expression. Dynamic changes in histone methylation are essential for the epigenetic regulation of memory consolidation-related genes. Here, we demonstrate that the plant homeodomain finger protein 2 (PHF2) histone demethylase is upregulated in the mouse hippocampus during the experience phase and plays an essential role in memory formation. PHF2 promotes the expression of memory-related genes by epigenetically reinforcing the TrkB-CREB signaling pathway. In behavioral tests, memory formation is enhanced by transgenic overexpression of PHF2 in mice, but is impaired by silencing PHF2 in the hippocampus. Electrophysiological studies reveal that PHF2 elevates field excitatory postsynaptic potential (fEPSP) and NMDA receptor-mediated evoked excitatory postsynaptic current (EPSC) in CA1 pyramidal neurons, suggesting that PHF2 promotes long-term potentiation. This study provides insight into the epigenetic regulation of learning and memory formation, which advances our knowledge to improve memory in patients with degenerative brain diseases.

Evaluation of the pathogenicity of GJB3 and GJB6 variants associated with nonsyndromic hearing loss.

A number of genes responsible for hearing loss are related to ion recycling and homeostasis in the inner ear. Connexins (Cx26 encoded by GJB2, Cx31 encoded by GJB3 and Cx30 encoded by GJB6) are core components of gap junctions in the inner ear. Gap junctions are intercellular communication channels and important factors that are associated with hearing loss. To date, a molecular genetics study of GJB3 and GJB6 as a causative gene for hearing loss has not been performed in Korea. This study was therefore performed to elucidate the genetic characteristics of Korean patients with nonsyndromic sensorineural hearing loss and to determine the pathological mechanism of hearing loss by analyzing the intercellular communication function of Cx30 and Cx31 variants. Sequencing analysis of the GJB3 and GJB6 genes in our population revealed a total of nine variants, including four novel variants in the two genes. Three of the novel variants (Cx31-p.V27M, Cx31-p.V43M and Cx-30-p.I248V) and two previously reported variants (Cx31-p.V84I and Cx30-p.A40V) were selected for functional studies using a pathogenicity prediction program and assessed for whether the mutations were located in a conserved region of the protein. The results of biochemical and ionic coupling tests showed that both the Cx31-p.V27M and Cx31-p.V84I variants did not function normally when each was expressed as a heterozygote with the wild-type Cx31. This study demonstrated that two variants of Cx31 were pathogenic mutations with deleterious effect. This information will be valuable in understanding the pathogenic role of GJB3 and GJB6 mutations associated with hearing loss.

Correlated signatures of social behavior in cerebellum and anterior cingulate cortex.

The cerebellum has been implicated in the regulation of social behavior. Its influence is thought to arise from communication, via the thalamus, to forebrain regions integral in the expression of social interactions, including the anterior cingulate cortex (ACC). However, the signals encoded or the nature of the communication between the cerebellum and these brain regions is poorly understood. Here, we describe an approach that overcomes technical challenges in exploring the coordination of distant brain regions at high temporal and spatial resolution during social behavior. We developed the E-Scope, an electrophysiology-integrated miniature microscope, to synchronously measure extracellular electrical activity in the cerebellum along with calcium imaging of the ACC. This single coaxial cable device combined these data streams to provide a powerful tool to monitor the activity of distant brain regions in freely behaving animals. During social behavior, we recorded the spike timing of multiple single units in cerebellar right Crus I (RCrus I) Purkinje cells (PCs) or dentate nucleus (DN) neurons while synchronously imaging calcium transients in contralateral ACC neurons. We found that during social interactions a significant subpopulation of cerebellar PCs were robustly inhibited, while most modulated neurons in the DN were activated, and their activity was correlated with positively modulated ACC neurons. These distinctions largely disappeared when only non-social epochs were analyzed suggesting that cerebellar-cortical interactions were behaviorally specific. Our work provides new insights into the complexity of cerebellar activation and co-modulation of the ACC during social behavior and a valuable open-source tool for simultaneous, multimodal recordings in freely behaving mice.

Social behaviour is important for many animals, especially humans. It governs interactions between individuals and groups. One of the regions involved in social behaviour is the cerebellum, a part of the brain commonly known for controlling movement. It is likely that the cerebellum connects and influences other socially important areas in the brain, such as the anterior cingulate cortex. How exactly these regions communicate during social interaction is not well understood. One of the challenges studying communication between areas in the brain has been a lack of tools that can measure neural activity in multiple regions at once. To address this problem, Hur et al. developed a device called the E-Scope. The E-Scope can measure brain activity from two places in the brain at the same time. It can simultaneously record imaging and electrophysiological data of the different neurons. It is also small enough to be attached to animals without inhibiting their movements. Hur et al. tested the E-Scope by studying neurons in two regions of the cerebellum, called the right Crus I and the dentate nucleus, and in the anterior cingulate cortex during social interactions in mice. The E-Scope recorded from the animals as they interacted with other mice and compared them with those in mice that interacted with objects. During social interactions, Purkinje cells in the right Crus I were mostly less active, while neurons in the dentate nucleus and anterior cingulate cortex became overall more active. These results suggest that communication between the cerebellum and the anterior cingulate cortex is an important part of how the mouse brain coordinates social behaviour. The study of Hur et al. deepens our understanding of the function of the cerebellum in social behaviour. The E-Scope is an openly available tool to allow researchers to record communication between remote brain areas in small animals. This could be important to researchers trying to understand conditions like autism, which can involve difficulties in social interaction, or injuries to the cerebellum resulting in personality changes.

Long-term potentiation of excitatory synaptic strength in spinothalamic tract neurons of the rat spinal cord.

Spinal dorsal horn nociceptive neurons have been shown to undergo long-term synaptic plasticity, including long-term potentiation (LTP) and long-term depression (LTD). Here, we focused on the spinothalamic tract (STT) neurons that are the main nociceptive neurons projecting from the spinal cord to the thalamus. Optical technique using fluorescent dye has made it possible to identify the STT neurons in the spinal cord. Evoked fast mono-synaptic, excitatory postsynaptic currents (eEPSCs) were measured in the STT neurons. Time-based tetanic stimulation (TBS) was employed to induce long-term potentiation (LTP) in the STT neurons. Coincident stimulation of both pre- and postsynaptic neurons using TBS showed immediate and persistent increase in AMPA receptor-mediated EPSCs. LTP can also be induced by postsynaptic spiking together with pharmacological stimulation using chemical NMDA. TBS-induced LTP observed in STT neurons was blocked by internal BAPTA, or Ni(2+), a T-type VOCC blocker. However, LTP was intact in the presence of L-type VOCC blocker. These results suggest that long-term plastic change of STT neurons requires NMDA receptor activation and postsynaptic calcium but is differentially sensitive to T-type VOCCs.

Correlated signatures of social behavior in cerebellum and anterior cingulate cortex.

The cerebellum has been implicated in the regulation of social behavior. Its influence is thought to arise from communication, via the thalamus, to forebrain regions integral in the expression of social interactions, including the anterior cingulate cortex (ACC). However, the signals encoded or the nature of the communication between the cerebellum and these brain regions is poorly understood. Here, we describe an approach that overcomes technical challenges in exploring the coordination of distant brain regions at high temporal and spatial resolution during social behavior. We developed the E-Scope, an electrophysiology-integrated miniature microscope, to synchronously measure extracellular electrical activity in the cerebellum along with calcium imaging of the ACC. This single coaxial cable device combined these data streams to provide a powerful tool to monitor the activity of distant brain regions in freely behaving animals. During social behavior, we recorded the spike timing of multiple single units in cerebellar right Crus I (RCrus I) Purkinje cells (PCs) or dentate nucleus (DN) neurons while synchronously imaging calcium transients in contralateral ACC neurons. We found that during social interactions a significant subpopulation of cerebellar PCs were robustly inhibited, while most modulated neurons in the DN were activated, and their activity was correlated with positively modulated ACC neurons. These distinctions largely disappeared when only non-social epochs were analyzed suggesting that cerebellar-cortical interactions were behaviorally specific. Our work provides new insights into the complexity of cerebellar activation and co-modulation of the ACC during social behavior and a valuable open-source tool for simultaneous, multimodal recordings in freely behaving mice.

In vivo patch-clamp recording from locus coeruleus neurones in the rat brainstem.

Locus coeruleus (LC) neurones extend noradrenergic projections throughout the neuroaxis and are involved in homeostatic functions such as pain modulation, arousal and cardio-respiratory control. To address the cellular mechanisms underlying pain modulation we have developed a patch-clamp recording technique from LC neurones in anaesthetized rats. These recordings showed LC discharge in vivo to be driven by both spontaneous membrane potential oscillations and CNQX-sensitive EPSCs opposed by bicuculine-sensitive IPSCs. Hindlimb pinch evoked a biphasic action potential response underpinned by a slow monophasic excitatory current. This approach allows detailed characterisation of the synaptic and integrative mechanisms of LC responses to naturalistic stimulation.

Endothelial progenitor cells functionally express inward rectifier potassium channels.

Since the first isolation of endothelial progenitor cells (EPCs) from human peripheral blood in 1997, many researchers have conducted studies to understand the characteristics and therapeutic effects of EPCs in vascular disease models. Nevertheless, the electrophysiological properties of EPCs have yet to be clearly elucidated. The inward rectifier potassium channel (Kir) performs a major role in controlling the membrane potential and cellular events. Here, via the whole cell patch-clamp technique, we found inwardly rectifying currents in EPCs and that these currents were inhibited by Ba(2+) (100 µM) and Cs(+) (1 mM), known as Kir blockers, in a dose-dependent manner (Ba(2+), 91.2 ± 1.4% at -140 mV and Cs(+), 76.1 ± 6.9% at -140 mV, respectively). Next, using DiBAC(3), a fluorescence indicator of membrane potential, we verified that Ba(2+) induced an increase of fluorescence in EPCs (10 µM, 123 ± 2.8%), implying the depolarization of EPCs. At the mRNA and protein levels, we confirmed the existence of several Kir subtypes, including Kir2.x, 3.x, 4.x, and 6.x. In a functional experiment, we observed that, in the presence of Ba(2+), the number of tubes on Matrigel formed by EPCs was dose-dependently reduced (10 µM, 62.3 ± 6.5%). In addition, the proliferation of EPCs was increased in a dose-dependent fashion (10 µM, 157.9 ± 17.4%), and specific inhibition of Kir2.1 by small interfering RNA also increased the proliferation of EPCs (116.2 ± 2.5%). Our results demonstrate that EPCs express several types of Kir which may modulate the endothelial function and proliferation of EPCs.

Amylose-Lipid Complex as a Fat Replacement in the Preparation of Low-Fat White Pan Bread.

Amylose-lipid complex (ALC) was prepared with corn starch and stearic acid and used as a shortening replacement in white pan bread preparation. ALCs were prepared using various concentrations of stearic acid to corn starch (1%, 3%, 5%, and 7%) under different temperatures (55, 65, and 75 °C) and for different durations of time (30, 60, and 120 min); then, their complexing properties were assessed using iodine reagent and X-ray diffraction. The complexing reaction at 75 °C for 60 min showed the highest complexing index of the tested conditions; the in vitro digestibility of ALC was lower than that of corn starch. White pan bread was prepared with ALCs and their characteristics, including appearance, loaf volume, and starch retrogradation during storage at room temperature for four days, were compared with those of control bread. With increasing ALC replacement concentrations, loaf volume and shape were significantly affected; however, starch retrogradation was significantly retarded and energy value decreased by ALC replacement. Overall, 50% replacement of shortening by ALC appeared to be a reasonable level for retaining the basic characteristics of the bread while retarding the staling process. These results indicate that ALCs may be potentially useful in the bakery industry for preparing low calorie and low-fat products.