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Increased risk of neurodegenerative diseases has been envisaged for air pollution exposure. On the other hand, environmental risk factors, including air pollution, have been suggested for Amyotrophic Lateral Sclerosis (ALS) pathomechanism. Therefore, the neurotoxicity of ultrafine particulate matter (PM0.1) (PM < 0.1 μm size) and its sub-20 nm nanoparticle fraction (NP20) has been investigated in motor neuronal-like cells and primary cortical neurons, mainly affected in ALS. The present data showed that PM0.1 and NP20 exposure induced endoplasmic reticulum (ER) stress, as occurred in cortex and spinal cord of ALS mice carrying G93A mutation in SOD1 gene. Furthermore, NSC-34 motor neuronal-like cells exposed to PM0.1 and NP20 shared the same proteomic profile on some apoptotic factors with motor neurons treated with the L-BMAA, a neurotoxin inducing Amyotrophic Lateral Sclerosis/Parkinson-Dementia Complex (ALS/PDC). Of note ER stress induced by PM0.1 and NP20 in motor neurons was associated to pathological changes in ER morphology and dramatic reduction of organellar Ca 2+ level through the dysregulation of the Ca 2+ -pumps SERCA2 and SERCA3, the Ca 2+ -sensor STIM1, and the Ca 2+ -release channels RyR3 and IP3R3. Furthermore, the mechanism deputed to ER Ca 2+ refilling (e.g. the so called store operated calcium entry-SOCE) and the relative currents ICRAC were also altered by PM0.1 and NP20 exposure. Additionally, these carbonaceous particles caused the exacerbation of L-BMAA-induced ER stress and Caspase-9 activation. In conclusion, this study shows that PM0.1 and NP20 induced the aberrant expression of ER proteins leading to dysmorphic ER, organellar Ca 2+ dysfunction, ER stress and neurotoxicity, providing putative correlations with the neurodegenerative process occurring in ALS., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The intricate glia interaction occurring after stroke strongly depend on the maintenance of intraglial ionic homeostasis. Among the several ionic channels and transporters, the plasmamembrane Na + /Ca 2+ exchanger (NCX) represents a key player in maintaining astroglial Na + and Ca 2+ homeostasis. Here, using a combined in vitro, in vivo and ex vivo experimental strategy we evaluated whether microglia responding to ischemic injury may influence the morphological and the transcriptional plasticity of post-ischemic astrocytes. Astrocyte plasticity was monitored by the expression of the transcription factor Acheate-scute like 1 (Ascl1), which plays a central role in the commitment of astrocytes towards the neuronal lineage. Furthermore, we explored the implication of NCX1 expression and activity in mediating Ascl1-dependent post-ischemic astrocyte remodeling. We demonstrated that: (a) in astrocytes co-cultured with microglia the exposure to oxygen and glucose deprivation followed by 7 days of reoxygenation induced a prevalence of bipolar astrocytes overexpressing Ascl1 and NCX1, whereas this did not occur in monocultured astrocytes; (b) the reoxygenation of anoxic astrocytes with the conditioned medium derived from IL-4 stimulated microglia strongly elicited the astrocytic co-expression of Ascl1 and NCX1; (c) Ascl1 expression in anoxic astrocytes was dependenton NCX1 since its silencing prevented Ascl1 expression both in in vitro and in post-ischemic ex vivo experimental conditions. Collectively, the results of our study support the idea that, after brain ischemia, astrocyte-microglia crosstalk can influence astrocytic morphology and its Ascl1 expression. This phenomenon is strictly dependent on ischemia-induced increase of NCX1 which in turn induces Ascl1 overexpression possibly through astrocytic Ca 2+ elevation., (Copyright © 2022. Published by Elsevier Ltd.)

Excessive calcium (Ca 2+ ) release from the endoplasmic reticulum (ER) represents an important hallmark of several neurodegenerative diseases. ER is recharged from Ca 2+ through the so-called Store-Operated Calcium Entry (SOCE) thus providing Ca 2+ signals to regulate critical cell functions. Single transmembrane-spanning domain protein stromal interacting molecule 1 (STIM1), mainly residing in the ER, and plasmalemmal channel Orai1 represent the SOCE key components at neuronal level. However, many other proteins participate to ER Ca 2+ refilling including the Na + /Ca 2+ exchanger isoform 1 (NCX1), whose regulation by ER remains unknown. In this study, we tested the possibility that neuronal NCX1 may take part to SOCE through the interaction with STIM1. In rat primary cortical neurons and in nerve growth factor (NGF)-differentiated PC12 cells NCX1 knocking down by siRNA strategy significantly prevented SOCE as well as SOCE pharmacological inhibition by SKF-96365 and 2-APB. A significant reduction of SOCE was recorded also in synaptosomes from ncx1 - / - mice brain compared with ncx1 + / + mice. Double labeling confocal experiments showed a large co-localization between NCX1 and STIM1 in rat primary cortical neurons. Accordingly, NCX1 and STIM1 co-immunoprecipitated and functionally interacted each other during ischemic preconditioning, a phenomenon inducing ischemic tolerance. However, STIM1 knocking down reduced NCX1 activity recorded by either patch-clamp electrophysiology or Fura-2 single-cell microfluorimetry. Furthermore, canonical transient receptor potential channel 6 (TRPC6) was identified as the mechanism mediating local increase of sodium (Na + ) useful to drive NCX1 reverse mode and, therefore, NCX1-mediated Ca 2+ refilling. In fact, TRPC6 not only interacted with STIM1, as shown by the co-localization and co-immunoprecipitation with the ER Ca 2+ sensor, but it also mediated 1,3-Benzenedicarboxylic acid, 4,4'-[1,4,10-trioxa-7,13-diazacyclopentadecane-7,13-diylbis(5-methoxy-6,12-benzofurandiyl)]bis-, tetrakis[(acetyloxy)methyl] ester (SBFI)-monitored Na + increase elicited by thapsigargin in primary cortical neurons. Accordingly, efficient TRPC6 knockdown prevented thapsigargin-induced intracellular Na + elevation and SOCE. Collectively, we identify NCX1 as a new partner of STIM1 in mediating SOCE, whose activation in the reverse mode may be facilitated by the local increase of Na + concentration due to the interaction between STIM1 and TRPC6 in primary cortical neurons., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

As a pivotal player in regulating sodium (Na + ) and calcium (Ca 2+ ) homeostasis and signalling in excitable cells, the Na + /Ca 2+ exchanger (NCX) is involved in many neurodegenerative disorders in which an imbalance of intracellular Ca 2+ and/or Na + concentrations occurs, including Alzheimer's disease (AD). Although NCX has been mainly implicated in neuroprotective mechanisms counteracting Ca 2+ dysregulation, several studies highlighted its role in the neuronal responses to intracellular Na + elevation occurring in several pathophysiological conditions. Since the alteration of Na + and Ca 2+ homeostasis significantly contributes to synaptic dysfunction and neuronal loss in AD, it is of crucial importance to analyze the contribution of NCX isoforms in the homeostatic responses at neuronal and synaptic levels. Some studies found that an increase of NCX activity in brains of AD patients was correlated with neuronal survival, while other research groups found that protein levels of two NCX subtypes, NCX2 and NCX3, were modulated in parietal cortex of late stage AD brains. In particular, NCX2 positive synaptic terminals were increased in AD cohort while the number of NCX3 positive terminals were reduced. In addition, NCX1, NCX2 and NCX3 isoforms were up-regulated in those synaptic terminals accumulating amyloid-beta (Aβ), the neurotoxic peptide responsible for AD neurodegeneration. More recently, the hyperfunction of a specific NCX subtype, NCX3, has been shown to delay endoplasmic reticulum stress and apoptotic neuronal death in hippocampal neurons exposed to Aβ insult. Despite some issues about the functional role of NCX in synaptic failure and neuronal loss require further studies, these findings highlight the putative neuroprotective role of NCX in AD and open new strategies to develop new druggable targets for AD therapy., Competing Interests: Declaration of Competing Interest The authors declare no competing interest., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Since the discovery of the three isoforms of the Na + /Ca 2+ exchanger, NCX1, NCX2 and NCX3 in 1990s, many studies have been devoted to identifying their specific roles in different tissues under several physiological or pathophysiological conditions. In particular, several seminal experimental works laid the foundation for better understanding gene and protein structures, tissue distribution, and regulatory functions of each antiporter isoform. On the other hand, despite the efforts in the development of specific compounds selectively targeting NCX1, NCX2 or NCX3 to test their physiological or pathophysiological roles, several drawbacks hampered the achievement of these goals. In fact, at present no isoform-specific compounds have been yet identified. Moreover, these compounds, despite their potency, possess some nonspecific actions against other ion antiporters, ion channels, and channel receptors. As a result, it is difficult to discriminate direct effects of inhibition/activation of NCX isoforms from the inhibitory or stimulatory effects exerted on other antiporters, channels, receptors, or enzymes. To overcome these difficulties, some research groups used transgenic, knock-out and knock-in mice for NCX isoforms as the most straightforward and fruitful strategy to characterize the biological role exerted by each antiporter isoform. The present review will survey the techniques used to study the roles of NCXs and the current knowledge obtained from these genetic modified mice focusing on the advantages obtained with these strategies in understanding the contribution exerted by each isoform., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Numerous lines of evidence indicate that nuclear calcium concentration ([Ca 2+ ] n ) may be controlled independently from cytosolic events by a local machinery. In particular, the perinuclear space between the inner nuclear membrane (INM) and the outer nuclear membrane (ONM) of the nuclear envelope (NE) likely serves as an intracellular store for Ca 2+ ions. Since ONM is contiguous with the endoplasmic reticulum (ER), the perinuclear space is adjacent to the lumen of ER thus allowing a direct exchange of ions and factors between the two organelles. Moreover, INM and ONM are fused at the nuclear pore complex (NPC), which provides the only direct passageway between the nucleoplasm and cytoplasm. However, due to the presence of ion channels, exchangers and transporters, it has been generally accepted that nuclear ion fluxes may occur across ONM and INM. Within the INM, the Na + /Ca 2+ exchanger (NCX) isoform 1 seems to play an important role in handling Ca 2+ through the different nuclear compartments. Particularly, nuclear NCX preferentially allows local Ca 2+ flowing from nucleoplasm into NE lumen thanks to the Na + gradient created by the juxtaposed Na + /K + -ATPase. Such transfer reduces abnormal elevation of [Ca 2+ ] n within the nucleoplasm thus modulating specific transductional pathways and providing a protective mechanism against cell death. Despite very few studies on this issue, here we discuss those making major contribution to the field, also addressing the pathophysiological implication of nuclear NCX malfunction., Competing Interests: Declaration of Competing Interest The authors declare no competing interests., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Intracellular [Na + ] i and [Ca 2+ ] i imbalance significantly contribute to neuro-axonal dysfunctions and maladaptive myelin repair or remyelination failure in chronic inflammatory demyelinating diseases such as multiple sclerosis. Progress in recent years has led to significant advances in understanding how [Ca 2+ ] i signaling network drive degeneration or remyelination of demyelinated axons. The Na + /Ca 2+ exchangers (NCXs), a transmembrane protein family including three members encoded by ncx1, ncx2, and ncx3 genes, are emerging important regulators of [Na + ] i and [Ca 2+ ] i both in neurons and glial cells. Here we review recent advance highlighting the role of NCX exchangers in axons and myelin-forming cells, i.e. oligodendrocytes, which represent the major targets of the aberrant inflammatory attack in multiple sclerosis. The contribution of NCX subtypes to axonal pathology and myelin synthesis will be discussed. Although a definitive understanding of mechanisms regulating axonal pathology and remyelination failure in chronic demyelinating diseases is still lacking and requires further investigation, current knowledge suggest that NCX activity plays a crucial role in these processes. Defining the relative contributions of each NCX transporter in axon pathology and myelinating glia will constitute not only a major advance in understanding in detail the intricate mechanism of neurodegeneration and remyelination failure in demyelinating diseases but also will help to identify neuroprotective or remyelinating strategies targeting selective NCX exchangers as a means of treating MS., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Astrocyte dysfunction emerges early in Alzheimer's disease (AD) and may contribute to its pathology and progression. Recently, the voltage gated potassium channel K V 3.4 subunit, which underlies the fast-inactivating K + currents, has been recognized to be relevant for AD pathogenesis and is emerging as a new target candidate for AD. In the present study, we investigated both in in vitro and in vivo models of AD the expression and functional activity of K V 3.4 potassium channel subunits in astrocytes. In primary astrocytes our biochemical, immunohistochemical, and electrophysiological studies demonstrated a time-dependent upregulation of K V 3.4 expression and functional activity after exposure to amyloid-β (Aβ) oligomers. Consistently, astrocytic K V 3.4 expression was upregulated in the cerebral cortex, hippocampus, and cerebellum of 6-month-old Tg2576 mice. Further, confocal triple labeling studies revealed that in 6-month-old Tg2576 mice, K V 3.4 was intensely coexpressed with Aβ in nonplaque associated astrocytes. Interestingly, in the cortical and hippocampal regions of 12-month-old Tg2576 mice, plaque-associated astrocytes much more intensely expressed K V 3.4 subunits, but not Aβ. More important, we evidenced that the selective knockdown of K V 3.4 expression significantly downregulated both glial fibrillary acidic protein levels and Aβ trimers in the brain of 6-month-old Tg2576 mice. Collectively, our results demonstrate that the expression and function of K V 3.4 channel subunits are precociously upregulated in cultured astrocytes exposed to Aβ oligomers and in reactive astrocytes of AD Tg2576 mice., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Reactive oxygen species (ROS) have been implicated in the pathophysiology of many neurologic disorders and brain dysfunction. In the same pathological settings evidence has been provided in favour of a participation of intracellular Ca(2+) concentration altered homeostasis in the chain of events leading to neuronal apoptosis. In the present review literature reports and experimental data on the relationship between caspase activation and alteration of intracellular calcium concentrations in the mechanisms triggering neuronal apoptosis are discussed. The data gathered support the conclusion that during oxidative stress in neuronal cells the production of ROS triggers a mechanism that, through the release of cytochrome c from mitochondria and caspase-3 activation, leads to apoptosis; the concomitant ROS-mediated elevation of intracellular Ca(2+) concentration triggers caspase-2 activation but both events do not seem to be involved in cell death.

An ever increasing number of reports shows the involvement of free radicals in the functional and structural changes occurring in the brain as a part of the "normal" aging process. Given that plasma membrane and intracellular ion channels play a critical role in maintaining intracellular ion homeostasis, which is crucial for neuronal cell survival, in the present review we have attempted to elaborate on the idea that functional changes in ion channel activity induced by reactive oxygen species (ROS) and reactive nitrogen species (RNS) might occur during the aging process. To this aim, we have reviewed the available literature and the data obtained in our laboratory on the ability of ROS and RNS to modify the activity of several plasma membrane and intracellular ion channels and transporters, in an attempt to correlate such changes with those occurring with the aging process. Particular emphasis is given to voltage-gated Na(+), Ca(2+), and K(+) channels, although second messenger-activated channels like Ca(2+)- and ATP-dependent K(+) channels, and intracellular channels controlling intracellular Ca(2+) storage and release will also be discussed. On the basis of the available data it is not yet possible to establish a strict correlation between the changes in neuronal electrophysiological properties induced by oxidative modification at the level of ion channels and the neurodegenerative process accompanying brain aging. However, an increasing amount of information suggests that the modulatory effects exerted by ROS and RNS on ion channel proteins might have a relevant role for neuronal cell survival or death. Obviously, more work is needed to establish the possible involvement of ion channels and of their modulation by ROS and RNS as important mechanisms for the aging process. Only when a more complete molecular picture of the aging process will be available, it will be possible to test the fascinating hypothesis that aging might be pharmacologically delayed by modulating ROS and RNS action on ion channels or the biochemical pathways involved in their modulation., (Copyright 2002 Elsevier Science Inc.)