Neuronal calcium sensor-1: a multifunctional regulator of secretion

2003 ◽  
Vol 31 (4) ◽  
pp. 828-832 ◽  
Author(s):  
S. Hilfiker

Ca2+ ions play a crucial role not only as the trigger for neurotransmitter release, but also in other aspects of brain function, such as short-term and long-term modulation of synaptic efficacy, which may underlie certain forms of learning and memory. The actions of Ca2+ are mediated by Ca2+-binding proteins, including a group of proteins known as neuronal calcium sensor (NCS) proteins. The NCS family includes NCS-1, visinin-like proteins, recoverins, guanylate cyclase-activating proteins and potassium channel-interacting proteins. Some members of this family, such as recoverin and guanylate cyclase-activating protein, are only expressed in photoreceptor cells and have been implicated in the control of visual transduction pathways, while the functional roles of the other members are largely unknown. NCS-1 was originally identified in Drosophila in a screen for neuronal hyperexcitability mutants. NCS-1 is an N-terminally myristoylated protein that contains four EF-hand motifs, three of which are able to bind Ca2+ in the submicromolar range. Overexpression of NCS-1 has been shown to enhance evoked neurotransmitter release, paired-pulse facilitation and exocytosis in several neuronal and neuroendocrine cell types. Recent experiments suggest that NCS-1 interacts directly with phosphatidylinositol 4-hydroxykinase in yeast as well as mammalian cells, suggesting that it may enhance neuronal secretion by modulating cellular trafficking steps in a phosphoinositide-dependent manner. In contrast, an involvement of NCS-1 in the expression and regulation of voltage-gated Ca2+ channels and K+ channels has also been proposed, which may be attributed, at least in part, to the effects of NCS-1 on vesicular trafficking pathways. The present review describes current knowledge about the cellular functions and molecular mechanisms by which NCS-1 may regulate neurotransmitter release.

2000 ◽  
Vol 353 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Robert D. BURGOYNE ◽  
Jamie L. WEISS

Ca2+ plays a central role in the function of neurons as the trigger for neurotransmitter release, and many aspects of neuronal activity, from rapid modulation to changes in gene expression, are controlled by Ca2+. These actions of Ca2+ must be mediated by Ca2+-binding proteins, including calmodulin, which is involved in Ca2+ regulation, not only in neurons, but in most other cell types. A large number of other EF-hand-containing Ca2+-binding proteins are known. One family of these, the neuronal calcium sensor (NCS) proteins, has a restricted expression in retinal photoreceptors or neurons and neuroendocrine cells, suggesting that they have specialized roles in these cell types. Two members of the family (recoverin and guanylate cyclase-activating protein) have established roles in the regulation of phototransduction. Despite close sequence similarities, the NCS proteins have distinct neuronal distributions, suggesting that they have different functions. Recent work has begun to demonstrate the physiological roles of members of this protein family. These include roles in the modulation of neurotransmitter release, control of cyclic nucleotide metabolism, biosynthesis of polyphosphoinositides, regulation of gene expression and in the direct regulation of ion channels. In the present review we describe the known sequences and structures of the NCS proteins, information on their interactions with target proteins and current knowledge about their cellular and physiological functions.


2018 ◽  
Author(s):  
Evgeny Zatulovskiy ◽  
Daniel F. Berenson ◽  
Benjamin R. Topacio ◽  
Jan M. Skotheim

Cell size is fundamental to function in different cell types across the human body because it sets the scale of organelle structures, biosynthesis, and surface transport1,2. Tiny erythrocytes squeeze through capillaries to transport oxygen, while the million-fold larger oocyte divides without growth to form the ~100 cell pre-implantation embryo. Despite the vast size range across cell types, cells of a given type are typically uniform in size likely because cells are able to accurately couple cell growth to division3–6. While some genes whose disruption in mammalian cells affects cell size have been identified, the molecular mechanisms through which cell growth drives cell division have remained elusive7–12. Here, we show that cell growth acts to dilute the cell cycle inhibitor Rb to drive cell cycle progression from G1 to S phase in human cells. In contrast, other G1/S regulators remained at nearly constant concentration. Rb is a stable protein that is synthesized during S and G2 phases in an amount that is independent of cell size. Equal partitioning to daughter cells of chromatin bound Rb then ensures that all cells at birth inherit a similar amount of Rb protein. RB overexpression increased cell size in tissue culture and a mouse cancer model, while RB deletion decreased cell size and removed the inverse correlation between cell size at birth and the duration of G1 phase. Thus, Rb-dilution by cell growth in G1 provides a long-sought cell autonomous molecular mechanism for cell size homeostasis.


2018 ◽  
Vol 47 (1) ◽  
pp. 469-497 ◽  
Author(s):  
Axel T. Brunger ◽  
Ucheor B. Choi ◽  
Ying Lai ◽  
Jeremy Leitz ◽  
Qiangjun Zhou

This review summarizes current knowledge of synaptic proteins that are central to synaptic vesicle fusion in presynaptic active zones, including SNAREs (soluble N-ethylmaleimide sensitive factor attachment protein receptors), synaptotagmin, complexin, Munc18 (mammalian uncoordinated-18), and Munc13 (mammalian uncoordinated-13), and highlights recent insights in the cooperation of these proteins for neurotransmitter release. Structural and functional studies of the synaptic fusion machinery suggest new molecular models of synaptic vesicle priming and Ca2+-triggered fusion. These studies will be a stepping-stone toward answering the question of how the synaptic vesicle fusion machinery achieves such high speed and sensitivity.


2004 ◽  
Vol 279 (15) ◽  
pp. 15142-15152 ◽  
Author(s):  
Kensuke Oikawa ◽  
Shoji Kimura ◽  
Naoko Aoki ◽  
Yoshiaki Atsuta ◽  
Yumi Takiyama ◽  
...  

2012 ◽  
Vol 2012 ◽  
pp. 1-18 ◽  
Author(s):  
Andreas Till ◽  
Ronak Lakhani ◽  
Sarah F. Burnett ◽  
Suresh Subramani

Peroxisomes are single-membrane-bounded organelles present in the majority of eukaryotic cells. Despite the existence of great diversity among different species, cell types, and under different environmental conditions, peroxisomes contain enzymes involved inβ-oxidation of fatty acids and the generation, as well as detoxification, of hydrogen peroxide. The exigency of all eukaryotic cells to quickly adapt to different environmental factors requires the ability to precisely and efficiently control peroxisome number and functionality. Peroxisome homeostasis is achieved by the counterbalance between organelle biogenesis and degradation. The selective degradation of superfluous or damaged peroxisomes is facilitated by several tightly regulated pathways. The most prominent peroxisome degradation system uses components of the general autophagy core machinery and is therefore referred to as “pexophagy.” In this paper we focus on recent developments in pexophagy and provide an overview of current knowledge and future challenges in the field. We compare different modes of pexophagy and mention shared and distinct features of pexophagy in yeast model systems, mammalian cells, and other organisms.


PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9799
Author(s):  
Priyanka Upadhyai ◽  
Vishal Singh Guleria ◽  
Prajna Udupa

Primary cilia are non-motile sensory antennae present on most vertebrate cell surfaces. They serve to transduce and integrate diverse external stimuli into functional cellular responses vital for development, differentiation and homeostasis. Ciliary characteristics, such as length, structure and frequency are often tailored to distinct differentiated cell states. Primary cilia are present on a variety of skeletal cell-types and facilitate the assimilation of sensory cues to direct skeletal development and repair. However, there is limited knowledge of ciliary variation in response to the activation of distinct differentiation cascades in different skeletal cell-types. C3H10T1/2, MC3T3-E1 and ATDC5 cells are mesenchymal stem cells, preosteoblast and prechondrocyte cell-lines, respectively. They are commonly employed in numerous in vitro studies, investigating the molecular mechanisms underlying osteoblast and chondrocyte differentiation, skeletal disease and repair. Here we sought to evaluate the primary cilia length and frequencies during osteogenic differentiation in C3H10T1/2 and MC3T3-E1 and chondrogenic differentiation in ATDC5 cells, over a period of 21 days. Our data inform on the presence of stable cilia to orchestrate signaling and dynamic alterations in their features during extended periods of differentiation. Taken together with existing literature these findings reflect the occurrence of not only lineage but cell-type specific variation in ciliary attributes during differentiation. These results extend our current knowledge, shining light on the variabilities in primary cilia features correlated with distinct differentiated cell phenotypes. It may have broader implications in studies using these cell-lines to explore cilia dependent cellular processes and treatment modalities for skeletal disorders centered on cilia modulation.


Author(s):  
Joanna Ewa Sowa ◽  
Krzysztof Tokarski

AbstractAccumulating evidence highlights chemokines as key mediators of the bidirectional crosstalk between neurons and glial cells aimed at preserving brain functioning. The multifaceted role of these immune proteins in the CNS is mirrored by the complexity of the mechanisms underlying its biological function, including biased signaling. Neurons, only in concert with glial cells, are essential players in the modulation of brain homeostatic functions. Yet, attempts to dissect these complex multilevel mechanisms underlying coordination are still lacking. Therefore, the purpose of this review is to summarize the current knowledge about mechanisms underlying chemokine regulation of neuron–glia crosstalk linking molecular, cellular, network, and behavioral levels. Following a brief description of molecular mechanisms by which chemokines interact with their receptors and then summarizing cellular patterns of chemokine expression in the CNS, we next delve into the sequence and mechanisms of chemokine-regulated neuron–glia communication in the context of neuroprotection. We then define the interactions with other neurotransmitters, neuromodulators, and gliotransmitters. Finally, we describe their fine-tuning on the network level and the behavioral relevance of their modulation. We believe that a better understanding of the sequence and nature of events that drive neuro-glial communication holds promise for the development of new treatment strategies that could, in a context- and time-dependent manner, modulate the action of specific chemokines to promote brain repair and reduce the neurological impairment.


Author(s):  
Pierre R. Moreau ◽  
Vanesa Tomas Bosch ◽  
Maria Bouvy-Liivrand ◽  
Kadri Õunap ◽  
Tiit Örd ◽  
...  

Objective: Atherosclerosis is the underlying cause of most cardiovascular diseases. The main cell types associated with disease progression in the vascular wall are endothelial cells, smooth muscle cells, and macrophages. Although their role in atherogenesis has been extensively described, molecular mechanisms underlying gene expression changes remain unknown. The objective of this study was to characterize microRNA (miRNA)-related regulatory mechanisms taking place in the aorta during atherosclerosis: Approach and Results: We analyzed the changes in primary human aortic endothelial cells and human umbilical vein endothelial cell, human aortic smooth muscle cell, and macrophages (CD14+) under various proatherogenic stimuli by integrating GRO-seq, miRNA-seq, and RNA-seq data. Despite the highly cell-type-specific expression of multi-variant pri-miRNAs, the majority of mature miRNAs were found to be common to all cell types and dominated by 2 to 5 abundant miRNA species. We demonstrate that transcription contributes significantly to the mature miRNA levels although this is dependent on miRNA stability. An analysis of miRNA effects in relation to target mRNA pools highlighted pathways and targets through which miRNAs could affect atherogenesis in a cell-type-dependent manner. Finally, we validate miR-100-5p as a cell-type specific regulator of inflammatory and HIPPO-YAP/TAZ-pathways. Conclusions: This integrative approach allowed us to characterize miRNA dynamics in response to a proatherogenic stimulus and identify potential mechanisms by which miRNAs affect atherogenesis in a cell-type-specific manner.


2021 ◽  
Vol 12 ◽  
Author(s):  
Orlando A. Acevedo ◽  
Roslye V. Berrios ◽  
Linmar Rodríguez-Guilarte ◽  
Bastián Lillo-Dapremont ◽  
Alexis M. Kalergis

The induction of trained immunity represents an emerging concept defined as the ability of innate immune cells to acquire a memory phenotype, which is a typical hallmark of the adaptive response. Key points modulated during the establishment of trained immunity include epigenetic, metabolic and functional changes in different innate-immune and non-immune cells. Regarding to epigenetic changes, it has been described that long non-coding RNAs (LncRNAs) act as molecular scaffolds to allow the assembly of chromatin-remodeling complexes that catalyze epigenetic changes on chromatin. On the other hand, relevant metabolic changes that occur during this process include increased glycolytic rate and the accumulation of metabolites from the tricarboxylic acid (TCA) cycle, which subsequently regulate the activity of histone-modifying enzymes that ultimately drive epigenetic changes. Functional consequences of established trained immunity include enhanced cytokine production, increased antigen presentation and augmented antimicrobial responses. In this article, we will discuss the current knowledge regarding the ability of different cell subsets to acquire a trained immune phenotype and the molecular mechanisms involved in triggering such a response. This knowledge will be helpful for the development of broad-spectrum therapies against infectious diseases based on the modulation of epigenetic and metabolic cues regulating the development of trained immunity.


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