Astrocytes are a crucial type of glial cells in the central nervous system, not only maintaining brain homeostasis, but also actively participating in the transmission of information within the brain. Astrocytes have a complex structure that includes the soma, various levels of processes, and end-feet. With the advancement of genetically encoded calcium indicators and imaging technologies, researchers have discovered numerous localized and small calcium activities in the fine processes and end-feet. These calcium activities were termed as microdomain calcium activities, which significantly differ from the calcium activities in the soma and can influence the activity of local neurons, synapses, and blood vessels. This article elaborates the detection and analysis, characteristics, sources, and functions of microdomain calcium activities, and discusses the impact of aging and neurodegenerative diseases on these activities, aiming to enhance the understanding of the role of astrocytes in the brain and to provide new insights for the treatment of brain disorders.
Astrocytes/cytology* ; Humans ; Animals ; Calcium/metabolism* ; Calcium Signaling/physiology* ; Brain/physiology* ; Aging/physiology* ; Membrane Microdomains/physiology* ; Neurodegenerative Diseases/physiopathology*

Stromal interaction molecules (STIM)s are Ca²⁺ sensors in internal Ca²⁺ stores of the endoplasmic reticulum. They activate the store-operated Ca²⁺ channels, which are the main source of Ca²⁺ entry in non-excitable cells. Moreover, STIM proteins interact with other Ca²⁺ channel subunits and active transporters, making STIMs an important intermediate molecule in orchestrating a wide variety of Ca²⁺ influxes into excitable cells. Nevertheless, little is known about the role of STIM proteins in brain functioning. Being involved in many signaling pathways, STIMs replenish internal Ca²⁺ stores in neurons and mediate synaptic transmission and neuronal excitability. Ca²⁺ dyshomeostasis is a signature of many pathological conditions of the brain, including neurodegenerative diseases, injuries, stroke, and epilepsy. STIMs play a role in these disturbances not only by supporting abnormal store-operated Ca²⁺ entry but also by regulating Ca²⁺ influx through other channels. Here, we review the present knowledge of STIMs in neurons and their involvement in brain pathology.
Neurons/metabolism* ; Animals ; Humans ; Calcium/metabolism* ; Stromal Interaction Molecules/metabolism* ; Calcium Signaling/physiology* ; Calcium Channels/metabolism* ; Brain/metabolism*

Hemorrhagic shock is a common clinical emergency that can aggravate cell injury after resuscitation. Astrocytes are crucial for the survival of neurons because they regulate the surrounding ionic microenvironment of neurons. Although hemorrhagic shock and resuscitation (HSR) injury can impair cognition, it remains unclear how this insult directly affects astrocytes. In this study, we established an HSR model by bleeding and re-transfusion in mice. The social interaction test and new object recognition test were applied to evaluate post-operative cognitive changes, and the results suggest that mice experience cognitive impairment following exposure to HSR. In the HSR group, the power spectral density of β and γ oscillations decreased, and the coupling of the θ oscillation phase and γ oscillation amplitude was abnormal, which indicated abnormal neuronal oscillation and cognitive impairment after HSR exposure. In brief, cognitive impairment in mice is strongly correlated with Ca²⁺ signal strength in lateral septum astrocytes following HSR.
Animals ; Astrocytes/metabolism* ; Shock, Hemorrhagic/metabolism* ; Resuscitation/adverse effects* ; Male ; Mice ; Calcium Signaling/physiology* ; Mice, Inbred C57BL ; Septal Nuclei/metabolism* ; Cognitive Dysfunction/etiology* ; Disease Models, Animal ; Cognition Disorders/etiology*

Microglial functions are linked to Ca²⁺ signaling, with endoplasmic reticulum (ER) calcium stores playing a crucial role. Microglial abnormality is a hallmark of Alzheimer's disease (AD), but how ER Ca²⁺ receptors regulate microglial functions under physiological and AD conditions remains unclear. We found reduced ryanodine receptor 2 (Ryr2) expression in microglia from an AD mouse model. Modulation of RyR2 using S107, a RyR-Calstabin stabilizer, blunted spontaneous Ca²⁺ transients in controls and normalized Ca²⁺ transients in AD mice. S107 enhanced ATP-induced migration and phagocytosis while reducing ramification in control microglia; however, these effects were absent in AD microglia. Our findings indicate that RyR2 stabilization promotes an activation state shift in control microglia, a mechanism impaired in AD. These results highlight the role of ER Ca²⁺ receptors in both homeostatic and AD microglia, providing insights into microglial Ca²⁺ malfunctions in AD.
Animals ; Microglia/pathology* ; Alzheimer Disease/pathology* ; Phagocytosis/drug effects* ; Ryanodine Receptor Calcium Release Channel/metabolism* ; Disease Models, Animal ; Mice ; Cell Movement/drug effects* ; Mice, Transgenic ; Calcium Signaling/physiology* ; Calcium/metabolism* ; Mice, Inbred C57BL ; Male ; Endoplasmic Reticulum/metabolism*

Mitochondria-associated endoplasmic reticulum membranes (MAMs) are the physical connection sites between mitochondria and endoplasmic reticulum (ER). As the compartments controlling substance and information communications between ER and mitochondria, MAMs were involved in the regulation of various pathophysiological processes, such as calcium homeostasis, mitochondrial morphology and function, lipid metabolism and autophagy. In the past decades, accumulating lines of evidence have revealed the pivotal role of MAMs in diverse cardiovascular diseases (CVD). Aging is one of the major independent risk factors for CVD, which causes progressive degeneration of the cardiovascular system, leading to increased morbidity and mortality of CVD. This review aims to summarize the research progress of MAMs in age-related CVD, and explore new targets for its prevention and treatment.
Humans ; Mitochondrial Membranes ; Cardiovascular Diseases/metabolism* ; Calcium Signaling/physiology* ; Mitochondria/physiology* ; Endoplasmic Reticulum/metabolism*

OBJECTIVE: To explore the expression, localization and regulatory effect on mitochondrial calcium signaling of Rictor in embryonic stem cell-derived cardiomyocytes (ESC-CMs). METHODS: Classical embryonic stem cell cardiomyogenesis model was used for differentiation of mouse embryonic stem cells into cardiomyocytes. The location of Rictor in ESC-CMs was investigated by immunofluorescence and Western blot. The expression of Rictor in mouse embryonic stem cells was interfered with lentiviral technology, then the superposition of mitochondria and endoplasmic reticulum (ER) in ESC-CMs was detected with immunofluorescence method; the cellular ultrastructure of ESC-CMs was observed by transmission electron microscope; the mitochondrial calcium transients of ESC-CMs was detected by living cell workstation;immunoprecipitation was used to detect the interaction between 1,5,5-trisphosphate receptor (IP3 receptor, IP3R), glucose-regulated protein 75 (Grp75) and voltage-dependent anion channel 1 (VDAC1) in mitochondrial outer membrane; the expression of mitochondrial fusion protein (mitonusin-2, Mfn2) was detected by Western blot. RESULTS: Rictor was mainly localized in the endoplasmic reticulum and mitochondrial-endoplasmic reticulum membrane (MAM) in ESC-CMs. Immunofluorescence results showed that Rictor was highly overlapped with ER and mitochondria in ESC-CMs. After mitochondrial and ER were labeled with Mito-Tracker Red and ER-Tracker Green, it was demonstrated that the mitochondria of the myocardial cells in the Rictor group were scattered, and the superimposition rate of mitochondria and ER was lower than that of the negative control group (<0.01). The MAM structures were decreased in ESC-CMs after knockdown of Rictor. The results of the living cell workstation showed that the amplitude of mitochondrial calcium transients by ATP stimulation in ESC-CMs was decreased after knockdown of Rictor (<0.01). The results of co-immunoprecipitation showed that the interaction between IP3R, Grp75 and VDAC1 in the MAM structure of the cardiomyocytes in the Rictor group was significantly attenuated (<0.01); the results of Western blot showed that the expression of Mfn2 protein was significantly decreased (<0.01). CONCLUSIONS Using lentiviral technology to interfere Rictor expression in mouse embryonic stem cells, the release of calcium from the endoplasmic reticulum to mitochondria in ESC-CMs decreases, which may be affected by reducing the interaction of IP3R, Grp75, VDAC1 and decreasing the expression of Mfn2, leading to the damage of MAM structure.
Animals ; Calcium Signaling ; genetics ; Gene Expression Regulation ; genetics ; Gene Knockdown Techniques ; Mice ; Mitochondria ; physiology ; Mouse Embryonic Stem Cells ; Myocytes, Cardiac ; physiology ; Protein Transport ; Rapamycin-Insensitive Companion of mTOR Protein ; genetics ; metabolism

The recent development of tools to decipher the intricacies of neural networks has improved our understanding of brain function. Optogenetics allows one to assess the direct outcome of activating a genetically-distinct population of neurons. Neurons are tagged with light-sensitive channels followed by photo-activation with an appropriate wavelength of light to functionally activate or silence them, resulting in quantifiable changes in the periphery. Capturing and manipulating activated neuron ensembles, is a recently-designed technique to permanently label activated neurons responsible for a physiological function and manipulate them. On the other hand, neurons can be transfected with genetically-encoded Ca indicators to capture the interplay between them that modulates autonomic end-points or somatic behavior. These techniques work with millisecond temporal precision. In addition, neurons can be manipulated chronically to simulate physiological aberrations by transfecting designer G-protein-coupled receptors exclusively activated by designer drugs. In this review, we elaborate on the fundamental concepts and applications of these techniques in research.
Animals ; Autonomic Pathways ; physiology ; Calcium Signaling ; physiology ; Humans ; Nerve Net ; physiology ; Neurons ; physiology ; Optogenetics ; methods ; Receptors, G-Protein-Coupled ; physiology

Due to the complex circuitry and plethora of cell types involved in somatosensation, it is becoming increasingly important to be able to observe cellular activity at the population level. In addition, since cells rely on an intricate variety of extracellular factors, it is important to strive to maintain the physiological environment. Many electrophysiological techniques require the implementation of artificially-produced physiological environments and it can be difficult to assess the activity of many cells simultaneously. Moreover, imaging Ca transients using Ca-sensitive dyes often requires in vitro preparations or in vivo injections, which can lead to variable expression levels. With the development of more sensitive genetically-encoded Ca indicators (GECIs) it is now possible to observe changes in Ca transients in large populations of cells at the same time. Recently, groups have used a GECI called GCaMP to address fundamental questions in somatosensation. Researchers can now induce GCaMP expression in the mouse genome using viral or gene knock-in approaches and observe the activity of populations of cells in the pain pathway such as dorsal root ganglia (DRG), spinal neurons, or glia. This approach can be used in vivo and thus maintains the organism's biological integrity. The implementation of GCaMP imaging has led to many advances in our understanding of somatosensation. Here, we review the current findings in pain research using GCaMP imaging as well as discussing potential methodological considerations.
Afferent Pathways ; physiology ; Animals ; Calcium ; metabolism ; Calcium Signaling ; drug effects ; genetics ; Ganglia, Spinal ; metabolism ; Humans ; Pain ; metabolism ; pathology

The present study attempted to test a novel hypothesis that Ca(2+) sparks play an important role in arterial relaxation induced by tacrolimus. Recorded with confocal laser scanning microscopy, tacrolimus (10 µmol/L) increased the frequency of Ca(2+) sparks, which could be reversed by ryanodine (10 µmol/L). Electrophysiological experiments revealed that tacrolimus (10 µmol/L) increased the large-conductance Ca(2+)-activated K(+) currents (BKCa) in rat aortic vascular smooth muscle cells (AVSMCs), which could be blocked by ryanodine (10 µmol/L). Furthermore, tacrolimus (10 and 50 µmol/L) reduced the contractile force induced by norepinephrine (NE) or KCl in aortic vascular smooth muscle in a concentration-dependent manner, which could be also significantly attenuated by iberiotoxin (100 nmol/L) and ryanodine (10 µmol/L) respectively. In conclusion, tacrolimus could indirectly activate BKCa currents by increasing Ca(2+) sparks released from ryanodine receptors, which inhibited the NE- or KCl-induced contraction in rat aorta.
Animals ; Aorta ; cytology ; metabolism ; physiology ; Calcium Signaling ; Cells, Cultured ; Large-Conductance Calcium-Activated Potassium Channels ; metabolism ; Male ; Muscle, Smooth, Vascular ; drug effects ; metabolism ; physiology ; Myocytes, Smooth Muscle ; drug effects ; metabolism ; Norepinephrine ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Ryanodine ; pharmacology ; Tacrolimus ; pharmacology ; Vasoconstriction

BACKGROUNDAlcohol dependence (AD) is a serious and common public health problem. The identification of genes that contribute to the AD variation will improve our understanding of the genetic mechanism underlying this complex disease. Previous genome-wide association studies (GWAS) and candidate gene genetic association studies identified individual genes as candidates for alcohol phenotypes, but efforts to generate an integrated view of accumulative genetic variants and pathways under alcohol drinking are lacking.

METHODSWe applied enrichment gene set analysis to existing genetic association results to identify pertinent pathways to AD in this study. A total of 1 438 SNPs (P < 1.0 × 10(-3)) associated to alcohol drinking related traits have been collected from 31 studies (10 candidate gene association studies, 19 GWAS of SNPs, and 2 GWAS of copy number variants).

RESULTSAmong all of the KEGG pathways, the calcium signaling pathway (hsa04020) showed the most significant enrichment of associations (21 genes) to alcohol consumption phenotypes (P = 5.4 × 10(-5)). Furthermore, the calcium signaling pathway is the only pathway that turned out to be significant after multiple test adjustments, achieving Bonferroni P value of 0.8 × 10(-3) and FDR value of 0.6 × 10(-2), respectively. Interestingly, the calcium signaling pathway was previously found to be essential to regulate brain function, and genes in this pathway link to a depressive effect of alcohol consumption on the body.

CONCLUSIONSOur findings, together with previous biological evidence, suggest the importance of gene polymorphisms of calcium signaling pathway to AD susceptibility. Still, further investigations are warranted to uncover the role of this pathway in AD and related traits.

Alcoholism ; genetics ; Calcium Signaling ; genetics ; physiology ; Genetic Predisposition to Disease ; genetics ; Genome-Wide Association Study ; methods ; Humans ; Polymorphism, Single Nucleotide ; genetics