NCS-1 deficiency causes anxiety and depressive-like behavior with impaired non-aversive memory in mice

Sensing and regulating intracellular levels of calcium are essential for proper cellular function. In neurons, calcium sensing plays important roles in neuronal plasticity, neurotransmitter release, long-term synapse modification and ion channel activity. Neuronal calcium sensor-1 (NCS-1) is a member of the highly conserved neuronal calcium sensor family. Although NCS-1 has been associated with psychiatric conditions including autism, bipolar disorder and schizophrenia, it is unclear which role NCS-1 plays in behavior. To understand the involvement of NCS-1 in psychiatric conditions, we provided a comprehensive behavioral characterization of NCS-1 knockout (KO) mice. These mice grow and develop normally without apparent abnormalities in comparison to wild type littermates. However, open field showed that NCS-1 deficiency impairs novelty-induced exploratory activity in both KO and heterozygote (HT) mice. Moreover, NCS-1-deficiency also resulted in anxiety- and depressive-like behaviors as demonstrated by elevated plus maze, large open field, forced swim and tail suspension tasks. Furthermore, based on spontaneous object recognition test, non-aversive long-term memory was impaired in NCS-1 KO mice. In contrast, neither social behavior nor a kind of aversive memory was affected under NCS-1 deficiency. These data implicate NCS-1 in exploratory activity, memory and mood-related behaviors, suggesting that NCS-1 gene ablation may result in phenotypic abnormalities associated with neuropsychiatric disorders.

[Evolution of mechanisms of Ca(2+)-signalization. Role of Ca2+ in regulation of specialized cell functions]

The review considers peculiarities of Ca(2+)-signalization in electroexcitable cells of the higher eukaryotes. The light has been thrown upon the problems of Ca(2+)-dependent mechanisms of regulation of muscle contractility and of neuronal synaptic plasticity in the higher vertebrate animals. A particular attention has been paid to analysis of contribution of such poorly studied components of Ca(2+)-signalization as non-selective TRPC-channels, Orai channels, sensory STIMI proteins, Ca(2+)-controlled K(+)-channels of high and low conductivity, and neuronal Ca(2+)-sensors (NCS).

Multiple roles for frequenin/NCS-1 in synaptic function and development

The calcium-binding protein frequenin (Frq), discovered in the fruit fly Drosophila, and its mammalian homologue neuronal calcium sensor 1 (NCS-1) have been reported to affect several aspects of synaptic transmission, including basal levels of neurotransmission and short- and long-term synaptic plasticities. However, discrepant reports leave doubts about the functional roles of these conserved proteins. In this review, we attempt to resolve some of these seemingly contradictory reports. We discuss how stimulation protocols, sources of calcium (voltage-gated channels versus internal stores), and expression patterns (presynaptic versus postsynaptic) of Frq may result in the activation of various protein targets, leading to different synaptic effects. In addition, the potential interactions of Frq's C-terminal and N-terminal domains with other proteins are discussed. Frq also has a role in regulating neurite outgrowth, axonal regeneration, and synaptic development. We examine whether the effects of Frq on neurotransmitter release and neurite outgrowth are distinct or interrelated through homeostatic mechanisms. Learning and memory are affected by manipulations of Frq probably through changes in synaptic transmission and neurite outgrowth, raising the possibility that Frq may be implicated in human pathological conditions, including schizophrenia, bipolar disorder, and X-linked mental retardation.

Modulation of muscarinic signaling in PC12 cells overexpressing neuronal Ca2+ sensor-1 protein

It has been suggested that overexpression of neuronal Ca2+ sensor-1 (NCS-1) protein is implicated in the pathophysiology of neurodisorders such as schizophrenia, bipolar disturbance and X-linked mental retardation. The mechanism by which NCS-1 would be involved in the causes and/or consequences of these neurodisorders is still far from elucidation. Independent evidence has pointed NCS-1 as a key regulator of synaptic efficacy by altering the expression and activity of voltage-gated channels, inhibiting internalization of dopaminergic receptors, and altering phosphoinositide metabolism. In this study, we examined the possible participation of NCS-1 protein in signal transmission dependent on muscarinic receptor activation, using PC12 cells stably expressing NCS-1 (PC12-NCS-1). Carbachol (CCH; 300 microM) was able to evoke glutamate release more efficiently from PC12-NCS-1 (15.3+/-1.0nmol/mg of protein) than wild type cells (PC12-wt; 8.3+/-0.9nmol/mg of protein). This increase of glutamate release induced by CCH was independent on extracellular Ca2+ influx. Additionally, a larger increase of cytoplasmic levels of InsP3 (663.0+/-63.0 and 310.0+/-39.0% of fluorescence in A.U.) and [Ca2+]i (766.4+/-40.0 and 687.8+/-37.1nmol/L) was observed after CCH stimulus of PC12-NCS-1 compared with PC12-wt. Clearly distinction between intracellular Ca2+ dynamics was also observed in PC12-NCS-1 and PC12-wt. A larger increase followed by fast decay of [Ca2+]i was observed in PC12-NCS-1. A plateau with a delayed decay of [Ca2+]i was characteristic of PC12-wt [Ca2+]i response. Both enhancement of InsP3 production and glutamate release observed in PC12-NCS-1 were blocked by atropine (10 microM). Together, our data show that overexpression of NCS-1 in PC12 cells induces an enhancement of intracellular second messenger and transmitter release dependent on CCH response, suggesting that muscarinic signaling is "up-regulated" in this cell model.

Neuronal calcium sensor proteins: generating diversity in neuronal Ca2+ signalling

In neurons, intracellular calcium signals have crucial roles in activating neurotransmitter release and in triggering alterations in neuronal function. Calmodulin has been widely studied as a Ca(2+) sensor that has several defined roles in neuronal Ca(2+) signalling, but members of the neuronal calcium sensor protein family have also begun to emerge as key components in a number of regulatory pathways and have increased the diversity of neuronal Ca(2+) signalling pathways. The differing properties of these proteins allow them to have discrete, non-redundant functions.