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TMEM16A, a Ca2+‐activated Cl− channel, is known to modulate the excitability of various types of cells; however, its function in central neurons is largely unknown. Here, we show the specific expression of TMEM16A in the medial habenula (mHb) via RNAscope in situ hybridization, immunohistochemistry, and electrophysiology. When TMEM16A is ablated in the mHb cholinergic neurons (TMEM16A cKO mice), the slope of after‐hyperpolarization of spontaneous action potentials decreases and the firing frequency is reduced. Reduced mHb activity also decreases the activity of the interpeduncular nucleus (IPN). Moreover, TMEM16A cKO mice display anxiogenic behaviors and deficits in social interaction without despair‐like phenotypes or cognitive dysfunctions. Finally, chemogenetic inhibition of mHb cholinergic neurons using the DREADD (Designer Receptors Exclusively Activated by Designer Drugs) approach reveals similar behavioral phenotypes to those of TMEM16A cKO mice. We conclude that TMEM16A plays a key role in anxiety‐related behaviors regulated by mHb cholinergic neurons and could be a potential therapeutic target against anxiety‐related disorders. Synopsis: The TMEM16A chloride channel has an excitatory role in cholinergic neurons of the medial habenula (mHb). Mice deficient for TMEM16A in mHb cholinergic neurons display anxiety‐related behaviors. TMEM16A is expressed in the medial habenula (mHb), and reduced activity of the mHb due to TMEM16A ablation reduces activity of the interpeduncular nucleus.Mice deficient for TMEM16A in mHb cholinergic neurons and mice with reduced activity of mHb neurons due to chemogenetic inhibition display anxiogenic behaviors and social interaction deficits.TMEM16A might be a potential therapeutic target against anxiety‐related disorders. [ABSTRACT FROM AUTHOR]

In neurons, intracellular membrane rafts are essential for specific actions of brain-derived neurotrophic factor ( BDNF), which include the regulation of axon outgrowth, growth cone turning and synaptic transmission. Virtually, all the actions of BDNF are mediated by binding to its receptor, TrkB. The association of TrkB with the tyrosine kinase, Fyn, is critical for its localization to intracellular membrane rafts. Here, we show that synapsins, a family of highly amphipathic neuronal phosphoproteins, regulate membrane raft lipid composition and consequently, the ability of BDNF to regulate axon/neurite development and potentiate synaptic transmission. In the brains of mice lacking all synapsins, the expression of both BDNF and TrkB were increased, suggesting that BDNF/TrkB-mediated signaling is impaired. Consistent with this finding, synapsin-depleted neurons exhibit altered raft lipid composition, deficient targeting of Fyn to rafts, attenuated TrkB activation, and abrogation of BDNF-stimulated axon outgrowth and synaptic potentiation. Conversely, overexpression of synapsins in neuroblastoma cells results in corresponding reciprocal changes in raft lipid composition, increased localization of Fyn to rafts and promotion of BDNF-stimulated neurite formation. In the presence of synapsins, the ratio of cholesterol to estimated total phospholipids converged to 1, suggesting that synapsins act by regulating the ratio of lipids in intracellular membranes, thereby promoting lipid raft formation. These studies reveal a mechanistic link between BDNF and synapsins, impacting early development and synaptic transmission. [ABSTRACT FROM AUTHOR]

RC3/neurogranin is a postsynaptic protein and plays pivotal roles in spatial learning and emotional anxiety as well as synaptic plasticity. The expression level of RC3 is dynamically changed during developmental stages, but the function of RC3 in brain development is not well understood yet. Neurotrophins interact with tropomyosin-related kinase receptors to activate Ras-extracellular signal-regulated kinase (ERK) pathway and can also induce neuronal differentiation. In this study, we demonstrate that RC3 inhibits Ras-ERK pathway by interaction with Ras and controls neurite outgrowth induced by neurotrophins. In PC12 cells, RC3 inhibits nerve growth factor (NGF)-induced activation of Ras and thereby ERK1/2 signaling cascade as well as neurite outgrowth induced by NGF. We found Ras is the target of the inhibitory function of RC3, because RC3 interacts with Ras and suppresses the elevated affinity of Ras to Ras-binding domain of Raf-1. Meanwhile, already activated Raf-1 by Ras activity is not affected by RC3. Furthermore, depletion of RC3 by RNA interference drastically enhances the stimulation of ERK1/2 and neurite outgrowth induced by brain-derived neurotrophic factor in hippocampal neurons. These findings suggest that RC3 is a novel natural inhibitor of Ras-ERK1/2 signaling axis, leading to negatively regulate neuronal differentiation induced by neurotrophins. [ABSTRACT FROM AUTHOR]

Astrocytes, the most abundant cell type in the brain, are non-excitable cells and play critical roles in brain function. Mature astrocytes typically exhibit a linear current–voltage relationship termed passive conductance, which is believed to enable astrocytes to maintain potassium homeostasis in the brain. We previously demonstrated that TWIK-1/TREK-1 heterodimeric channels mainly contribute to astrocytic passive conductance. However, the molecular identity of astrocytic passive conductance is still controversial and needs to be elucidated. Here, we report that spadin, an inhibitor of TREK-1, can dramatically reduce astrocytic passive conductance in brain slices. A series of gene silencing experiments demonstrated that spadin-sensitive currents are mediated by TWIK-1/TREK-1 heterodimeric channels in cultured astrocytes and hippocampal astrocytes from brain slices. Our study clearly showed that TWIK-1/TREK-1-heterodimeric channels can act as the main molecular machinery of astrocytic passive conductance, and suggested that spadin can be used as a specific inhibitor to control astrocytic passive conductance. [ABSTRACT FROM AUTHOR]

Anoctamin-1 (ANO1) is a Ca 2+ -activated chloride channel (CaCC) that plays important physiological roles in normal and cancerous tissues. However, the plasma membrane trafficking mechanisms of ANO1 remain poorly characterized. In yeast two-hybrid screening experiments, we observed direct interactions of ANO1 with β-COP, which is a subunit of Coat Protein Complex I (COPI). This interaction was then confirmed using several in vitro and in vivo binding assays. Moreover, the cotransfection of β-COP with ANO1 into HEK293T cells led to decreased the surface expression and the channel activity of ANO1. Accordingly, endogenous ANO1 was associated with β-COP in U251 glioblastoma cells, and silencing of β-COP enhanced surface expression and whole-cell currents of ANO1 in these cells. Taken together, these data suggest that β-COP negatively regulates ANO1 surface expression. [ABSTRACT FROM AUTHOR]