Intracellular Ca2+ Sensing: Its Role in Calcium Homeostasis and Signaling

Amplifying Ca2+ overload by engineered biomaterials for synergistic cancer therapy

Ca2+ overload is one of the most widely causes of inducing apoptosis, pyroptosis, immunogenic cell death, autophagy, paraptosis, necroptosis, and calcification of tumor cells, and has become the most valuable therapeutic strategy in the field of cancer treatment. Nevertheless, several challenges remain in translating Ca2+ overload-mediated therapeutic strategies into clinical applications, such as the precise control of Ca2+ dynamics, specificity of Ca2+ homeostasis dysregulation, as well as comprehensive mechanisms of Ca2+ regulation. Given this, we comprehensively reviewed the Ca2+-driven intracellular signaling pathways and the application of Ca2+-based biomaterials (such as CaCO3-, CaP-, CaO2-, CaSi-, CaF2-, and CaH2-) in mediating cancer diagnosis, treatment, and immunotherapy. Meanwhile, the latest researches on Ca2+ overload-mediated therapeutic strategies, as well as those combined with multiple-model therapies in mediating cancer immunotherapy are further highlighted. More importantly, the critical challenges and the future prospects of the Ca2+ overload-mediated therapeutic strategies are also discussed. By consolidating recent findings and identifying future research directions, this review aimed to advance the field of oncology therapy and contribute to the development of more effective and targeted treatment modalities.

The HRAS-binding C2 domain of PLCη2 suppresses tumor-like synoviocytes and experimental arthritis in rheumatoid arthritis

Fibroblast-like synoviocytes (FLSs), which are stromal cells that play key roles in rheumatoid arthritis (RA) pathophysiology, are characterized by a tumor-like phenotype and immunostimulatory actions. C2 domains in various proteins play roles in intracellular signaling and altering cellular characteristics, and some C2 domain-containing proteins exacerbate or alleviate certain malignant or inflammatory diseases. However, the roles of C2 domains in regulating the functions of RA FLSs remain unclear. Here we performed functional C2 domainomics with 144 C2 domain-containing viral vectors and identified the C2 domain of PLCη2 as a key regulator of RA FLSs. In mice, overexpressing PLCη2 or only its C2 domain PLCη2 (PLCη2_C2) diminished the proliferation, migration, invasion and inflammatory responses of RA FLSs, mitigating RA pathology; the absence of PLCη2 amplified these proinflammatory and destructive processes in RA FLSs in vivo. Mechanistically, PLCη2 and PLCη2_C2 participate in the pathological signaling of RA FLSs in a calcium-independent manner through protein-protein interactions. Specifically, PLCη2_C2 disrupted HRAS-RAF1 interactions, suppressing downstream signaling pathways, including the NF-κB, JAK-STAT and MAPK pathways. Collectively, these findings establish PLCη2 and PLCη2_C2 as novel inhibitory regulators in RA, suggesting promising therapeutic avenues for addressing FLS-driven disease mechanisms.

Calcium-mediated regulation of mitophagy: implications in neurodegenerative diseases

Calcium signaling plays a pivotal role in diverse cellular processes through precise spatiotemporal regulation and interaction with effector proteins across distinct subcellular compartments. Mitochondria, in particular, act as central hubs for calcium buffering, orchestrating energy production, redox balance and apoptotic signaling, among others. While controlled mitochondrial calcium uptake supports ATP synthesis and metabolic regulation, excessive accumulation can trigger oxidative stress, mitochondrial membrane permeabilization, and cell death. Emerging findings underscore the intricate interplay between calcium homeostasis and mitophagy, a selective type of autophagy for mitochondria elimination. Although the literature is still emerging, this review delves into the bidirectional relationship between calcium signaling and mitophagy pathways, providing compelling mechanistic insights. Furthermore, we discuss how disruptions in calcium homeostasis impair mitophagy, contributing to mitochondrial dysfunction and the pathogenesis of common neurodegenerative diseases.

Intracellular metal ion-based chemistry for programmed cell death

Intracellular metal ions play essential roles in multiple physiological processes, including catalytic action, diverse cellular processes, intracellular signaling, and electron transfer. It is crucial to maintain intracellular metal ion homeostasis which is achieved by the subtle balance of storage and release of metal ions intracellularly along with the influx and efflux of metal ions at the interface of the cell membrane. Dysregulation of intracellular metal ions has been identified as a key mechanism in triggering programmed cell death (PCD). Despite the importance of metal ions in initiating PCD, the molecular mechanisms of intracellular metal ions within these processes are infrequently discussed. An in-depth understanding and review of the role of metal ions in triggering PCD may better uncover novel tools for cancer diagnosis and therapy. Specifically, the essential roles of calcium (Ca2+), iron (Fe2+/3+), copper (Cu+/2+), and zinc (Zn2+) ions in triggering PCD are primarily explored in this review, and other ions like manganese (Mn2+/3+/4+), cobalt (Co2+/3+) and magnesium ions (Mg2+) are briefly discussed. Further, this review elaborates on the underlying chemical mechanisms and summarizes these metal ions triggering PCD in cancer therapy. This review bridges chemistry, immunology, and biology to foster the rational regulation of metal ions to induce PCD for cancer therapy.

Roles of calcium in ameloblasts during tooth development: A scoping review

Objectives

Calcium ions (Ca2+) play crucial role in tooth development, particularly in maintaining enamel density during amelogenesis. Ameloblasts require specific proteins such as amelogenin, ameloblastin, enamelin, kallikrein, and collagen for enamel growth. Recent research has highlighted the importance of calcium and fluoride ions, as well as the TRPM7, STIM, and SOCE pathways, in regulating various stages of enamel formation. This review synthesizes current knowledge, focusing on preclinical data elucidating the molecular mechanisms of calcium transport in ameloblasts, during normal tooth development and in response to external stimuli.

Methods

This scoping review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The literature search, conducted in December 2023, spanned multiple databases including PubMed (8.363 records), Google Scholar (5.630 records), and Science Direct (21.810 records). The primary aim was to examine the influence of calcium ion regulation on ameloblast development, with a focus on preclinical studies.

Results

After an initial screening of 396 titles and abstracts, 11 full-text articles (four in vitro studies and seven animal studies) met the inclusion and exclusion criteria. The studies, assessed for quality using the CAMRADES tool, ranged from low to moderate. Calcium deficiency, nutritional supplements, fluoride exposure, TRPM7, STIM proteins, and the SOCE pathway were found to influence amelogenesis.

Conclusion

Calcium transport mechanisms play a critical role in enamel formation, with factors such as TRPM7, Kir 4.2, CRAC channels, and the SOCE pathway supporting enamel mineralization, while disruptions like hypoxia, fluoride exposure, and circadian imbalances negatively impact amelogenesis. Understanding the interplay between calcium, environmental, and nutritional factors provides valuable insights into ameloblast function and offers potential avenues for improving enamel quality and addressing defects.

ATP2A3 in Primary Aldosteronism: Machine Learning-Based Discovery and Functional Validation

BACKGROUND

Aldosterone-producing adenomas (APAs) are a common cause of primary aldosteronism that can lead to cardiovascular complications if left untreated. Machine learning-based bioinformatics approaches have emerged as powerful tools for identifying potential disease markers, gaining widespread recognition in biomedical research. We aimed to use machine learning to discover novel biomarkers of APAs to identify new pathophysiological mechanisms.

METHODS

We applied 2 machine learning algorithms to published RNA sequencing data to identify APA feature genes. Validation was performed using APA tissue samples, spatial transcriptomics, pig adrenal glands, and in vitro assays in a human adrenocortical cell line.

RESULTS

Machine learning identified ATP2A3 as a key feature gene in APA, and its upregulation in APAs compared with the adjacent cortex was confirmed by spatial transcriptomics. In human adrenocortical cells, angiotensin II treatment increased ATP2A3 gene expression 9.15-fold. Silencing ATP2A3 decreased basal CYP11B2 expression and aldosterone secretion by 3.51-fold and 1.46-fold, respectively, and by 1.77-fold and 1.94-fold under angiotensin II stimulation. Dietary sodium restriction in pigs significantly increased ATP2A3 mRNA and protein levels. Spatial transcriptomics showed that APA cells exhibited higher ATP2A3 gene expression compared with all other adrenal cell types. The suppressive effect of ATP2A3 silencing on CYP11B2 expression was further enhanced by Ca2+ inhibitors.

CONCLUSIONS

The ATP2A3 gene is highly expressed in APA and is a key regulator of CYP11B2 expression and aldosterone production.

Palmitoylation and regulation of potassium-dependent sodium/calcium exchangers (NCKX)

Cellular Ca2+ homeostasis is critical for normal cell physiology and is regulated by several mechanisms. Two major players in intracellular Ca2+ homeostasis in multiple tissues belong to the SLC8 (Na+/Ca2+ exchangers (NCXs); NCX1-3) and SLC24 (K+ dependent Na+/Ca2+ exchangers (NCKXs); NCKX1-5) families. It has been established that NCXs and NCKX4 are palmitoylated, and that palmitoylation promotes NCX1 inactivation. However, there is still little known about NCKXs' palmitoylation. We found that (1) NCKX3 and NCKX5, but not NCKX1, are palmitoylated, (2) Cys to Ala mutation at position 467 for NCXK3 and 325 for NCKX5 notably diminished palmitoylation and (3) reduced palmitoylation enhanced NCKX3 activity. Our findings bring novel insights into NCKX1, NCKX3 and NCKX5 palmitoylation and establish palmitoylation as an endogenous regulator of NCKX3 activity, paving the way for investigations evaluating the role of palmitoylation in NCKX3 function in health and disease.

Discovery, Characterization, and Anti-XOD Activity of Calcium Metallophore from Coix lacryma-jobi

In this work, coixalkyne A (1), a natural polynuclear calcium complex with a novel cross-shaped molecular architecture, was isolated from Coix lacryma-jobi L. along with the undescribed analogue coixalkyne B (2). Their structures were identified by means of NMR spectroscopy, ECD calculations, and single-crystal X-ray diffraction. It is noteworthy that the calcium ligands of 1 as well as compound 2 possess rare terminal alkynes and a nor-carbon sesquiterpene (C14) framework. The antihyperuricemic activity of C. lacryma-jobi and xanthine oxidase (XOD) inhibitory effects of 1-2 were elucidated by in vivo and in vitro assays, while the possible mechanism of action was suggested by molecular docking. Different from the reported chemical synthesis and protein calcium carriers, the discovery of compounds 1 and 2 provided new proof for the natural calcium metallophore in plants with xanthine oxidase inhibitory activity.

Harnessing natural saponins: Advancements in mitochondrial dysfunction and therapeutic applications

BACKGROUND

Mitochondrial dysfunction plays a crucial role in the development of a variety of diseases, notably neurodegenerative disorders, cardiovascular diseases, metabolic syndrome, and cancer. Natural saponins, which are intricate glycosides characterized by steroidal or triterpenoid structures, have attracted interest due to their diverse pharmacological benefits, including anti-inflammatory, antiviral, and anti-aging effects.

PURPOSE

This review synthesizes recent advancements in understanding mitochondrial dysfunction and explores how saponins can modulate mitochondrial function. It focuses on their potential applications in neuroprotection, cardiovascular health, and oncology.

STUDY DESIGN

The review incorporates a comprehensive literature analysis, highlighting the interplay between saponins and mitochondrial signaling pathways. Specific attention is given to the effects of saponins like ginsenoside Rg2 and 20(S)-protopanaxatriol on mitophagy and their neuroprotective, anti-aging, and synergistic therapeutic effects when combined.

METHODS

We conducted a comprehensive review of current research and clinical trials using PubMed, Google Scholar, and SciFinder databases. The search focused on saponins' role in mitochondrial function and their therapeutic effects, including "saponins", "mitochondria" and "mitochondrial function". The analysis primarily focused on articles published between 2011 and 2024.

RESULTS

The findings indicate that certain saponins can enhance mitophagy and modulate mitochondrial signaling pathways, showing promise in neuroprotection and anti-aging. Additionally, combinations of saponins have demonstrated synergistic effects in myocardial protection and cancer therapy, potentially improving therapeutic outcomes.

CONCLUSION

Although saponins exhibit significant potential in modulating mitochondrial functions and developing innovative therapeutic strategies, their clinical applications are constrained by low bioavailability. Rigorous clinical trials are essential to translate these findings into effective clinical therapies, ultimately improving patient outcomes through a deeper understanding of saponins' impact on mitochondrial function.

Calcium balance through mutual orchestrated inter-organelle communication: A pleiotropic target for combating Alzheimer's disease

Dysfunctional intraneuronal organelles in Alzheimer's Disease (AD) propel aberrant calcium handling, triggering molecular miscommunication within organelles such as mitochondria, endoplasmic reticulum, and lysosomes. This disruption in organelle function not only impairs cellular homeostasis but also exacerbates neurodegenerative processes involving the accumulation of amyloid-β (Aβ) and hyperphosphorylated tau, amplifying the disease's vicious cycle. In this review, the concept of Mutual Orchestrated Inter-organelle Communication (MOIC) proposes potential therapeutic avenues for restoring Ca2+ homeostasis in AD, offering a theoretical framework for developing disease-modifying treatments. The intricate nature of AD necessitates a shift towards combination therapies targeting MOIC-associated pathways, presenting a more effective approach than monotherapy.

Enhancing alginate dialdehyde-gelatin (ADA-GEL) based hydrogels for biofabrication by addition of phytotherapeutics and mesoporous bioactive glass nanoparticles (MBGNs)

This study explores the 3D printing of alginate dialdehyde-gelatin (ADA-GEL) inks incorporating phytotherapeutic agents, such as ferulic acid (FA), and silicate mesoporous bioactive glass nanoparticles (MBGNs) at two different concentrations. 3D scaffolds with bioactive properties suitable for bone tissue engineering (TE) were obtained. The degradation and swelling behaviour of films and 3D printed scaffolds indicated an accelerated trend with increasing MBGN content, while FA appeared to stabilize the samples. Determination of the degree of crosslinking validated the increased stability of hydrogels due to the addition of FA and 0.1% (w/v) MBGNs. The incorporation of MBGNs not only improved the effective moduli and conferred bioactive properties through the formation of hydroxyapatite (HAp) on the surface of ADA-GEL-based samples but also enhanced VEGF-A expression of MC3T3-E1 cells. The beneficial impact of FA and low concentrations of MBGNs in ADA-GEL-based inks for 3D (bio)printing applications was corroborated through various printing experiments, resulting in higher printing resolution, as also confirmed by rheological measurements. Cytocompatibility investigations revealed enhanced MC3T3-E1 cell activity and viability. Furthermore, the presence of mineral phases, as confirmed by an in vitro biomineralization assay, and increased ALP activity after 21 days, attributed to the addition of FA and MBGNs, were demonstrated. Considering the acquired structural and biological properties, along with efficient drug delivery capability, enhanced biological activity, and improved 3D printability, the newly developed inks exhibit promising potential for biofabrication and bone TE.

Goose astrovirus induces apoptosis and endoplasmic reticulum stress in gosling hepatocytes

The ongoing Goose astrovirus (GoAstV) epidemic, which primarily infects goslings causing severe liver damage, has inflicted considerable damage on the poultry industry. Endoplasmic reticulum stress (ERS) is a significant modulator of several viral infections, while severe ERS may result in apoptosis. This study examined the roles and possible mechanisms of ERS and apoptosis in GoAstV-induced liver injury in goslings. Two hundred Xingguo gray geese were chosen and randomly separated into two groups (Con and Dis). The Dis group received a subcutaneous injection of GoAstV genotype 2 (GoAstV-2) JX01 (2 × 106 TCID50/0.2 mL), whereas the Con group received a subcutaneous injection of 0.2 mL physiological saline, both at 1 day of life. Subsequent analyses demonstrate that the levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) increased following GoAstV infection. Hematoxylin and eosin (HE) staining revealed swollen and ruptured hepatocytes, with significant inflammatory cell infiltration. Electron microscopy revealed expansion of the endoplasmic reticulum (ER) and aggregation of chromatin at the periphery. TUNEL testing further demonstrated an increase in the quantity of positive cells. RT-qPCR and Western blot analyses indicated that GoAstV infection enhanced the expression of ER Ca2+ release channels (IP3R and RYR) and calmodulin-dependent protein kinase II (CaMKII), while decreasing the expression of ER Ca2+ uptake channels (SERCA). Further, GoAstV infection activated ERS-related factors, including GRP78, IRE1α, PERK, ATF6, eIF2α, ATF4, CHOP, TRAF2, and JNK, induced the expression of pro-apoptotic factors (Caspase-3, Caspase-9, and Bax), and inhibited the mRNA and protein expression of the anti-apoptotic factor Bcl-2. Correlation analysis further revealed a potential relationship among ERS gene expression, apoptotic gene expression, and liver injury. In summary, GoAstV infection can lead to liver injury by interfering with ER Ca2+ homeostasis, exacerbating ERS and inducing hepatocyte apoptosis.

Calcium Imaging in Brain Tissue Slices

Calcium imaging is a method that was first developed in the mid-1970s yet kept developing until current days to allow accurate measurement of free calcium ions in tissues. This widely used method has provided significant advances to our understanding of cellular signal transduction, including the discovery of subcellular compartmentalization of neurons and astrocytes, the identification of multiple signaling pathways, and mapping the functional connectivity between astrocytes and neuronal networks. Here we describe a method for the loading and imaging of cell-permeable AM ester calcium-sensitive dyes for the in vitro measurement of free intracellular Ca2+ ions in acute brain slices.

Effects of Light and Water Agitation on Hatching Processes in False Clownfish Amphiprion ocellaris

False clownfish (Amphiprion ocellaris) employ a hatching strategy regulated by environmental cues, wherein parents provide water flow to encourage embryos to hatch after sunset on the hatching day. Despite previous studies demonstrating the necessity of complete darkness and water agitation for hatching, the regulatory mechanisms underlying these environmental cues remain elusive. This study aimed to investigate how darkness and water agitation affect the secretion of hatching enzymes and the hatching movements of embryos in false clownfish. Assessment of chorion digestion and live imaging of Ca2+ in hatching glands using GCaMP6s, a Ca2+ indicator, revealed that darkness stimulation triggers the secretion of hatching enzymes by increasing Ca2+ levels in hatching gland cells. On the other hand, water agitation primarily stimulated hatching movements in embryos, which led to the rupture of their egg envelopes. These results suggest that changes in light environments following sunset induce embryos to secrete hatching enzymes and that water agitation provided by parents stimulates hatching movements. These responses to environmental cues, light and water agitation, contribute to the rapid and synchronous hatching in false clownfish.

Can Magnoflorine Improve Memory? Immunohistochemical Studies on Parvalbumin Immunoreactive Neurons and Fibers of Mice Hippocampus

Background/Objectives: We assessed the influence of long-term injection of magnoflorine (MAG) on memory acquisition in mice for the first time. Methods: This isoquinoline alkaloid that belongs to the aporphines was isolated from the roots of Berberis vulgaris by centrifugal partition chromatography (CPC) using a biphasic solvent system composed of chloroform: methanol: water in the ratio 4:3:3 (v/v/v) with 20 mM of hydrochloric acid and triethylamine, within 64 min. Results: Our results indicated that long-term injection of MAG 20 mg/kg dose improve the long-term memory acquisition in mice that were evaluated in the passive avoidance (PA) test with no toxicity records. The analysis of brain lysates and animal plasma by HPLC-ESI-QTOF-MS/MS showed the ability of the compound to cross the blood-brain barrier, and an elevated level of phosphatidylcholine PC (14:1(9Z)/14:1(9Z)) with the molecular formula of C36H69NO8P was observed in both treated groups with 10 mg/kg and 20 mg/kg MAG in comparison to the control group. Conclusions: This phenomenon may explain MAG's cognition-enhancing properties as the PC may induce the synthesis and strengthening of neuronal cells. Also, the 7-day-long administration of MAG at 10 mg/kg and 20 mg/kg increased the mean number of parvalbumin (PV)-IR neurons in the hippocampus. Statistically, the largest PV-IR neurons were observed at the 20 mg/kg dose, which may indicate a potential effect of MAG on Ca2+ metabolism. However, no statistical differences were observed in the mean number of PV-IR nerve fibers in both doses of MAG, regardless of the hippocampal fields. This positive effect of MAG on hippocampal neurons provides further support for the neuroprotective effect of this alkaloid.

Mechanism of starvation induced autophagy and apoptosis in the midgut of silkworm, Bombyx mori, based on calcium homeostasis

Starvation can induce autophagy and apoptosis in intestinal cells. To elucidate the underlying mechanisms, we investigated autophagy and apoptosis in the midgut of the model insect, silkworm (Bombyx mori), focusing on calcium homeostasis. The results indicated that the body weight of silkworms decreased, along with damage to the morphology of their digestive tracts and midguts after starvation treatment. Additionally, mitochondrial swelling, autophagy and apoptosis were observable. Further investigation revealed that starvation upregulated the transcription of Ca2+ release channel-associated genes (e.g., BmIP3R, BmRyR) but suppressed the expression of Ca2+ efflux genes (BmPMCA), resulting in Ca2+ overload in midgut cells and subsequent upregulation of BmCalpain transcription. In addition, starvation increased the transcription of key autophagy genes (BmATG5, BmATG7, BmATG8) and the expression of the LC3-II protein. Upon prolonged starvation, the NtATG5 protein levels increased, a process that facilitated the transition from autophagy to apoptosis. These results indicate that Ca2+ overload activates the calpain-mediated apoptosis pathway and promotes apoptosis of midgut cells. The present study reveals the significant role that Ca2+ plays in the occurrence and transformation of autophagy and apoptosis induced by starvation treatment, thus providing a new research strategy for investigating the damage caused by starvation in biological organisms.

The Bordetella effector protein BteA induces host cell death by disruption of calcium homeostasis

Bordetella pertussis is the causative agent of whooping cough in humans, a disease that has recently experienced a resurgence. In contrast, Bordetella bronchiseptica infects the respiratory tract of various mammalian species, causing a range of symptoms from asymptomatic chronic carriage to acute illness. Both pathogens utilize type III secretion system (T3SS) to deliver the effector protein BteA into host cells. Once injected, BteA triggers a cascade of events leading to caspase 1-independent necrosis through a mechanism that remains incompletely understood. We demonstrate that BteA-induced cell death is characterized by the fragmentation of the cellular endoplasmic reticulum and mitochondria, the formation of necrotic balloon-like protrusions, and plasma membrane permeabilization. Importantly, genome-wide CRISPR-Cas9 screen targeting 19,050 genes failed to identify any host factors required for BteA cytotoxicity, suggesting that BteA does not require a single nonessential host factor for its cytotoxicity. We further reveal that BteA triggers a rapid and sustained influx of calcium ions, which is associated with organelle fragmentation and plasma membrane permeabilization. The sustained elevation of cytosolic Ca2+ levels results in mitochondrial calcium overload, mitochondrial swelling, cristolysis, and loss of mitochondrial membrane potential. Inhibition of calcium channels with 2-APB delays both the Ca2+ influx and BteA-induced cell death. Our findings indicate that BteA exploits essential host processes and/or redundant pathways to disrupt calcium homeostasis and mitochondrial function, ultimately leading to host cell death.IMPORTANCEThe respiratory pathogens Bordetella pertussis and Bordetella bronchiseptica exhibit cytotoxicity toward a variety of mammalian cells, which depends on the type III secretion effector BteA. Moreover, the increased virulence of B. bronchiseptica is associated with enhanced expression of T3SS and BteA. However, the molecular mechanism underlying BteA cytotoxicity is elusive. In this study, we performed a CRISPR-Cas9 screen, revealing that BteA-induced cell death depends on essential or redundant host processes. Additionally, we demonstrate that BteA disrupts calcium homeostasis, which leads to mitochondrial dysfunction and cell death. These findings contribute to closing the gap in our understanding of the signaling cascades targeted by BteA.

Effects of Ca2+ on the Structure and Dynamics of PIP3 in Model Membranes Containing PC and PS

Phosphatidylinositol phosphates (PIPs) are a family of seven different eukaryotic membrane lipids that have a large role in cell viability, despite their minor concentration in eukaryotic cellular membranes. PIPs tightly regulate cellular processes, such as cellular growth, metabolism, immunity, and development through direct interactions with partner proteins. Understanding the biophysical properties of PIPs in the complex membrane environment is important to understand how PIPs selectively regulate a partner protein. Here, we investigate the structure and dynamics of PIP3 in lipid bilayers that are simplified models of the natural membrane environment. We probe the effects of the anionic lipid phosphatidylserine (PS) and the divalent cation Ca2+ by using full-length lipids in well-formed bilayers. We used solution and solid-state NMR on naturally abundant 1H, 31P, and 13C atoms combined with molecular dynamics (MD) simulations to characterize the structure and dynamics of PIPs. 1H and 31P 1D spectra show good resolution at temperatures above the phase transition with isolated peaks in the headgroup, interfacial, and bilayer regions. Site-specific assignment of the chemical shifts of these reporters enables the measurement of the effects of Ca2+ and PS at the single atom level. In particular, the resolved 31P signals of the PIP3 headgroup allow for extremely well-localized information about PIP3 phosphate dynamics, which the MD simulations can further explain. A quantitative assessment of cross-polarization kinetics provides additional dynamics measurements for the PIP3 headgroups.

Neutrophil diversity and function in health and disease

Neutrophils, the most abundant type of granulocyte, are widely recognized as one of the pivotal contributors to the acute inflammatory response. Initially, neutrophils were considered the mobile infantry of the innate immune system, tasked with the immediate response to invading pathogens. However, recent studies have demonstrated that neutrophils are versatile cells, capable of regulating various biological processes and impacting both human health and disease. Cytokines and other active mediators regulate the functional activity of neutrophils by activating multiple receptors on these cells, thereby initiating downstream signal transduction pathways. Dysfunctions in neutrophils and disruptions in neutrophil homeostasis have been implicated in the pathogenesis of numerous diseases, including cancer and inflammatory disorders, often due to aberrant intracellular signaling. This review provides a comprehensive synthesis of neutrophil biological functions, integrating recent advancements in this field. Moreover, it examines the biological roles of receptors on neutrophils and downstream signaling pathways involved in the regulation of neutrophil activity. The pathophysiology of neutrophils in numerous human diseases and emerging therapeutic approaches targeting them are also elaborated. This review also addresses the current limitations within the field of neutrophil research, highlighting critical gaps in knowledge that warrant further investigation. In summary, this review seeks to establish a comprehensive and multidimensional model of neutrophil regulation, providing new perspectives for potential clinical applications and further research.

S-acylation of Ca2+ transport proteins in cancer

Alterations in cellular calcium (Ca2+) signals have been causally associated with the development and progression of human cancers. Cellular Ca2+ signals are generated by channels, pumps, and exchangers that move Ca2+ ions across membranes and are decoded by effector proteins in the cytosol or in organelles. S-acylation, the reversible addition of 16-carbon fatty acids to proteins, modulates the activity of Ca2+ transporters by altering their affinity for lipids, and enzymes mediating this reversible post-translational modification have also been linked to several types of cancers. Here, we compile studies reporting an association between Ca2+ transporters or S-acylation enzymes with specific cancers, as well as studies reporting or predicting the S-acylation of Ca2+ transporters. We then discuss the potential role of S-acylation in the oncogenic potential of a subset of Ca2+ transport proteins involved in cancer.

An Orai1 gain-of-function tubular aggregate myopathy mouse model phenocopies key features of the human disease

Tubular aggregate myopathy (TAM) is a heritable myopathy primarily characterized by progressive muscle weakness, elevated levels of creatine kinase (CK), hypocalcemia, exercise intolerance, and the presence of tubular aggregates (TAs). Here, we generated a knock-in mouse model based on a human gain-of-function mutation which results in a severe, early-onset form of TAM, by inducing a glycine-to-serine point mutation in the ORAI1 pore (Orai1G100S/+ or GS mice). By 8 months of age, GS mice exhibited significant muscle weakness, exercise intolerance, elevated CK levels, hypocalcemia, and robust TA presence. Unexpectedly, constitutive Ca2+ entry in mutant mice was observed in muscle only during early development and was abolished in adult skeletal muscle, partly due to reduced ORAI1 expression. Consistent with proteomic results, significant mitochondrial damage and dysfunction was observed in skeletal muscle of GS mice. Thus, GS mice represent a powerful model for investigation of the pathophysiological mechanisms that underlie key TAM symptoms, as well as those compensatory responses that limit the damaging effects of uncontrolled ORAI1-mediated Ca2+ influx.

The effect of elevating extracellular CaCl2: Important considerations for tissue engineering applications

Polysaccharides such as sodium alginate, pectin and gellan gum are widely used biomaterials, for their ability to easily form hydrogels in the presence of divalent metal ions, such as calcium - a process often cited as a mild crosslinking mechanism. However, when using these materials as substrates for tissue engineering, there is a lack of extensive studies that investigate the impact of elevated calcium concentrations on cell health and behaviour. In this study, we performed an in-depth exploration to understand the potential effects of raising extracellular CaCl2 on cell viability, proliferation, morphology and migration. We used an established glioblastoma (GBM) cell line (U251), human dermal fibroblasts (HDF), and murine osteoblasts (MC3T3) to assess the consequences of using CaCl2 in tissue engineered models to help reevaluate biomaterial suitability and enhance standardisation practices in the field of tissue engineering. Our findings revealed that the addition of CaCl2 induced notable morphological changes in GBM cells when cultured in 3D hydrogels with excess CaCl2 added, leading to a transition from mesenchymal to amoeboid phenotypes, even at a concentration as low as 8 mM. Furthermore, cell viability was reduced in a concentration-dependent manner across all cell types, and migration was also affected. Despite the widespread use of high CaCl2 concentrations to facilitate scaffold gelation, our research unveils that there can be significant risks to cell viability, proliferation, morphology, and migration when such practices are not preceded by cell line-specific experimentation and thorough standardization procedures. This highlights the importance of careful consideration and optimisation of CaCl2 concentration when used as a crosslinking agent for hydrogels intended for use in tissue engineering applications that demand accurate recapitulation of cellular responses and physiological conditions.

Homology-based identification and structural analysis of Pangasius hypophthalmus Annexins and Serine proteases to search molecules for wound healing applications

Chronic wounds and burns are a worldwide healthcare problem that erodes patients' well-being and healthcare systems. This silent and costly epidemic requires new, cost-efficient solutions to improve patients' physical and economic welfare. Eschar-degrading vegetal and bacterial proteases have been utilized as a solution. However, these proteins are evolutionarily far from those present in human wound healing. Serine protease (SP) and annexin (ANX) proteins interact within the skin healing process. A homology-based identification pipeline can help in discovering selective human SP and ANX analogs in the epithelial tissue of the fast-healing species, Pangasius hypophthalmus. In the present work, we found 14 candidates for RT-PCR in P. hypophthalmus using homology inference. The genetically detected candidates were then structurally and sequentially analyzed to understand their possible relation to SPs and ANXs involved in human wound healing. A total of six TBLASTN/BLASTX candidates (four SPs and two ANXs) were detected in P. hypophthalmus skin. Structural analysis revealed that all SP candidates resembled human KLK4, KLK5, KLK6, and KLK8, whereas all ANX only resembled human ANXA4. Structure and sequence analysis revealed high conservation of ANX Ca2+ binding sites (GDXD) and SP catalytic triad (HDS) motifs. In addition, structural analysis revealed that SP substrate selectivity position 186 was the main difference between human KLK5 and P. hypophthalmus SPs. These findings may allow the proposal and testing of more selective formulations, broadening treatments beyond debridement.

Mitochondrial Dysfunction in Cardiac Disease: The Fort Fell

Myocardial cells and the extracellular matrix achieve their functions through the availability of energy. In fact, the mechanical and electrical properties of the heart are heavily dependent on the balance between energy production and consumption. The energy produced is utilized in various forms, including kinetic, dynamic, and thermal energy. Although total energy remains nearly constant, the contribution of each form changes over time. Thermal energy increases, while dynamic and kinetic energy decrease, ultimately becoming insufficient to adequately support cardiac function. As a result, toxic byproducts, unfolded or misfolded proteins, free radicals, and other harmful substances accumulate within the myocardium. This leads to the failure of crucial processes such as myocardial contraction-relaxation coupling, ion exchange, cell growth, and regulation of apoptosis and necrosis. Consequently, both the micro- and macro-architecture of the heart are altered. Energy production and consumption depend on the heart's metabolic resources and the functional state of the cardiac structure, including cardiomyocytes, non-cardiomyocyte cells, and their metabolic and energetic behavior. Mitochondria, which are intracellular organelles that produce more than 95% of ATP, play a critical role in fulfilling all these requirements. Therefore, it is essential to gain a deeper understanding of their anatomy, function, and homeostatic properties.

Gene expression plasticity governing symbiosis during natural coral bleaching

The increasing global frequency and severity of coral bleaching events, driven by the loss of endosymbiotic algae, pose a significant threat to these vital ecosystems. However, gene expression plasticity offers a potential mechanism for rapid and effective acclimatization to environmental changes. We employed dual transcriptomics to examine the gene expression profile of Seriatopora hystrix, an ecologically important scleractinian coral, across healthy, mildly bleached, and severely bleached colonies collected from the waters of Likupang, North Sulawesi, Indonesia. Our analysis revealed that coral bleaching is associated with gene plasticity in calcium signaling and focal adhesion within coral hosts, as well as with endoplasmic reticulum stress in symbionts. Notably, we identified specific genes associated with innate immunity that were predominantly overexpressed in mildly bleached coral hosts. This overexpression implies that high expression plasticity of these key genes might contribute to bleaching resistance and the preservation of the host-symbiont relationship. Our findings offer a detailed insight into the dynamics of bleaching resistance in S. hystrix, shedding light on the variability of bleaching risks in Indonesian reefs and underscoring the coral's ability to utilize gene expression plasticity for immediate survival and potential long-term adaptation to climate changes.

Phase Separation of FUS with Poly(ADP-ribosyl)ated PARP1 Is Controlled by Polyamines, Divalent Metal Cations, and Poly(ADP-ribose) Structure

Fused in sarcoma (FUS) is involved in the formation of nuclear biomolecular condensates associated with poly(ADP-ribose) [PAR] synthesis catalyzed by a DNA damage sensor such as PARP1. Here, we studied FUS microphase separation induced by poly(ADP-ribosyl)ated PARP1WT [PAR-PARP1WT] or its catalytic variants PARP1Y986S and PARP1Y986H, respectively, synthesizing (short PAR)-PARP1Y986S or (short hyperbranched PAR)-PARP1Y986H using dynamic light scattering, fluorescence microscopy, turbidity assays, and atomic force microscopy. We observed that biologically relevant cations such as Mg2+, Ca2+, or Mn2+ or polyamines (spermine4+ or spermidine3+) were essential for the assembly of FUS with PAR-PARP1WT and FUS with PAR-PARP1Y986S in vitro. We estimated the range of the FUS-to-PAR-PARP1 molar ratio and the cation concentration that are favorable for the stability of the protein's microphase-separated state. We also found that FUS microphase separation induced by PAR-PARP1Y986H (i.e., a PARP1 variant attaching short hyperbranched PAR to itself) can occur in the absence of cations. The dependence of PAR-PARP1-induced FUS microphase separation on cations and on the branching of the PAR structure points to a potential role of the latter in the regulation of the formation of FUS-related biological condensates and requires further investigation.

Bifunctional nanoprobe for simultaneous detection of intracellular reactive oxygen species and temperature in single cells

Living cells can rapidly adjust their metabolic activities in response to external stimuli, leading to fluctuations in intracellular temperature and reactive oxygen species (ROS) levels. Monitoring these parameters is essential for understanding cellular metabolism, particularly during dynamic biological processes. In this study, we present a bifunctional nanoprobe capable of simultaneous measurement of ROS levels and temperature within single cells. The nanoprobe features two individually addressable nanoelectrodes, with platinum (Pt) and nickel (Ni) coatings on both sides. At the tip, these two metal layers form a nano-thermocouple, enabling precise intracellular temperature measurements, while the Pt layer facilitates selective ROS detection. This dual functionality allows for real-time monitoring of cellular responses during synergistic chemo-photothermal therapy of cancer cells and zebrafish embryos subjected to mitochondrial toxic stress. Our results demonstrate that the nanoprobe effectively measures increases in temperature and ROS levels in HeLa cells undergoing chemo-photothermal therapy, as well as in chemically stimulated zebrafish embryos. By providing detailed analysis of submicrometer-scale temperature and ROS variations within living cells, this nanoprobe offers valuable insights into cellular processes and holds promise for early disease detection and drug development.

Calcium Transport and Enrichment in Microorganisms: A Review

Calcium is a vital trace element for the human body, and its deficiency can result in a range of pathological conditions, including rickets and osteoporosis. Despite the numerous types of calcium supplements currently available on the market, these products are afflicted with a number of inherent deficiencies, such as low calcium content, poor aqueous solubility, and low human absorption rate. Many microorganisms, particularly beneficial microorganisms, including edible fungi, lactic acid bacteria, and yeast, are capable of absorbing and enriching calcium, a phenomenon that has been widely documented. This opens the door to the potential utilization of microorganisms as novel calcium enrichment carriers. However, the investigation of calcium-rich foods from microorganisms still faces many obstacles, including a poor understanding of calcium metabolic pathways in microorganisms, a relatively low calcium enrichment rate, and the slow growth of strains. Therefore, in order to promote the development of calcium-rich products from microorganisms, this paper provides an overview of the impacts of calcium addition on strain growth, calcium enrichment rate, antioxidant system, and secondary metabolite production. Additionally, it highlights calcium transport and enrichment mechanisms in microorganism cells and offers a detailed account of the progress made on calcium-binding proteins, calcium transport pathways, and calcium storage and release. This paper offers insights for further research on the relevant calcium enrichment in microorganism cells.

A cyclic peptide toolkit reveals mechanistic principles of peptidylarginine deiminase IV regulation

Peptidylarginine deiminase IV (PADI4, PAD4) deregulation promotes the development of autoimmunity, cancer, atherosclerosis and age-related tissue fibrosis. PADI4 additionally mediates immune responses and cellular reprogramming, although the full extent of its physiological roles is unexplored. Despite detailed molecular knowledge of PADI4 activation in vitro, we lack understanding of its regulation within cells, largely due to a lack of appropriate systems and tools. Here, we develop and apply a set of potent and selective PADI4 modulators. Using the mRNA-display-based RaPID system, we screen >1012 cyclic peptides for high-affinity, conformation-selective binders. We report PADI4_3, a cell-active inhibitor specific for the active conformation of PADI4; PADI4_7, an inert binder, which we functionalise for the isolation and study of cellular PADI4; and PADI4_11, a cell-active PADI4 activator. Structural studies with PADI4_11 reveal an allosteric binding mode that may reflect the mechanism that promotes cellular PADI4 activation. This work contributes to our understanding of PADI4 regulation and provides a toolkit for the study and modulation of PADI4 across (patho)physiological contexts.

TRPM2-mediated feed-forward loop promotes chondrocyte damage in osteoarthritis via calcium-cGAS-STING-NF-κB pathway

INTRODUCTIONS

Osteoarthritis (OA) is a significant contributor to disability in the elderly population. However, current therapeutic options are limited. The transient receptor potential melastatin 2 (TRPM2) is involved in a range of disease processes, yet its role in OA remains unclear.

OBJECTIVES

To investigate the role of TRPM2 in OA.

METHODS

Cartilage samples were collected from patients with osteoarthritis (OA) and mice with OA to examine TRPM2 expression levels. To investigate the effects of TRPM2 modulation on the destabilization of the medial meniscus (DMM) induced knee OA in mice, we utilized TRPM2 knockout mice and employed adenovirus-mediated overexpression of TRPM2. Furthermore, siRNA-mediated TRPM2 knockdown or plasmid-mediated TRPM2 overexpression was conducted to explore the role of TRPM2 in IL-1β-induced chondrocytes. The regulatory mechanism of IL-1β on TRPM2 expression was screened by signaling pathway inhibitors, and the transcription factors and binding sites of TRPM2 were predicted using the database. The binding of RELA (NF-κB-p65) to the Trpm2 promoter was verified by chip-PCR and ChIP-qPCR. The therapeutic potential of Ca2+ chelation with BAPTA-AM for the treatment of osteoarthritis (OA) was investigated.

RESULTS

An increased expression of TRPM2 was observed in the cartilage of OA patients and OA mice. Furthermore, mice deficient in Trpm2 exhibited a protective effect against DMM-induced OA progression. In contrast, TRPM2 overexpression resulted in exacerbation of DMM-induced OA and thepromotion of an OA-like phenotype of chondrocytes. TRPM2 was upregulated by IL-1β in an NF-κB-p65-dependent manner. Subsequently, the TRPM2-Ca2+-mtDNA-cGAS-STING-NF-κB axis in the progression of OA was validated. Furthermore, inhibition of the TRPM2-Ca2+ axis with BAPTA-AM effectively attenuated established OA.

CONCLUSIONS

Our data collectively revealed a pathological feedback loop involving TRPM2, Ca2+, mtDNA, cGAS, STING, and NF-κB in OA chondrocytes. This suggests that disrupting this loop could be a viable therapeutic approach for OA.

Role of astrocytes in Alzheimer's disease pathogenesis and the impact of exercise-induced remodeling

Alzheimer's disease (AD) is a prevalent and debilitating brain disorder that worsens progressively with age, characterized by cognitive decline and memory impairment. The accumulation of amyloid-beta (Aβ) leading to amyloid plaques and hyperphosphorylation of Tau, resulting in intracellular neurofibrillary tangles (NFTs), are primary pathological features of AD. Despite significant research investment and effort, therapies targeting Aβ and NFTs have proven limited in efficacy for treating or slowing AD progression. Consequently, there is a growing interest in non-invasive therapeutic strategies for AD prevention. Exercise, a low-cost and non-invasive intervention, has demonstrated promising neuroprotective potential in AD prevention. Astrocytes, among the most abundant glial cells in the brain, play essential roles in various physiological processes and are implicated in AD initiation and progression. Exercise delays pathological progression and mitigates cognitive dysfunction in AD by modulating astrocyte morphological and phenotypic changes and fostering crosstalk with other glial cells. This review aims to consolidate the current understanding of how exercise influences astrocyte dynamics in AD, with a focus on elucidating the molecular and cellular mechanisms underlying astrocyte remodeling. The review begins with an overview of the neuropathological changes observed in AD, followed by an examination of astrocyte dysfunction as a feature of the disease. Lastly, the review explores the potential therapeutic implications of exercise-induced astrocyte remodeling in the context of AD.

Unlocking the electrochemical functions of biomolecular condensates

Biomolecular condensation is a key mechanism for organizing cellular processes in a spatiotemporal manner. The phase-transition nature of this process defines a density transition of the whole solution system. However, the physicochemical features and the electrochemical functions brought about by condensate formation are largely unexplored. We here illustrate the fundamental principles of how the formation of condensates generates distinct electrochemical features in the dilute phase, the dense phase and the interfacial region. We discuss the principles by which these distinct chemical and electrochemical environments can modulate biomolecular functions through the effects brought about by water, ions and electric fields. We delineate the potential impacts on cellular behaviors due to the modulation of chemical and electrochemical environments through condensate formation. This Perspective is intended to serve as a general road map to conceptualize condensates as electrochemically active entities and to assess their functions from a physical chemistry aspect.

Manipulating long-term fates of sonoporated cells by regulating intracellular calcium for improving sonoporation-based delivery

Sonoporation-based delivery has great promise for noninvasive drug and gene therapy. After short-term membrane resealing, the long-term function recovery of sonoporated cells affects the efficiency and biosafety of sonoporation-based delivery. It is necessary to identify the key early biological signals that influence cell fate and to develop strategies for manipulating the long-term fates of sonoporated cells. Here, we used a customized experimental platform with a single cavitating microbubble induced by a single ultrasound pulse (frequency: 1.5 MHz, pulse length:13.33 μs, peak negative pressure: ∼0.40 MPa) to elicit single-site reversible sonoporation on a single HeLa cell model. We used a living-cell microscopic imaging system to trace the long-term fates of sonoporated HeLa cells in real-time for 48 h. Fluorescence from intracellular propidium iodide and Fluo-4 was used to evaluate the degree of sonoporation and intracellular calcium fluctuation (ICF), respectively. Changes in cell morphology were used to assess the long-term cell fates (i.e., proliferation, arrest, or death). We found that heterogeneously sonoporated cells had different long-term fates. With increasing degree of sonoporation, the probability of normal (proliferation) and abnormal fates (arrest and death) in sonoporated cells decreased and increased, respectively. We identified ICF as an important early event for triggering different long-term fates. Reversibly sonoporated cells exhibited stronger proliferation and restoration at lower extents of ICF. We then regulated ICF dynamics in sonoporated cells using 2-APB or BAPTA treatment to reduce calcium release from intracellular organelles and enhance intracellular calcium clearance, respectively. This significantly enhanced the proliferation and restoration of sonoporated cells and reduced the occurrence of cell-cycle arrest and death. Finally, we found that the long-term fates of sonoporated cells at multiple sites and neighboring cells were also dependent on the extent of ICF, and that 2-APB significantly enhanced their viability and reduced death. Thus, using a single HeLa cell model, we demonstrated that regulating intracellular calcium can effectively enhance the proliferation and restoration capabilities of sonoporated cells, therefore rescuing the long-term viability of sonoporated cells. These findings add to our understanding of the biophysical process of sonoporation and help design new strategies for improving the efficiency and biosafety of sonoporation-based delivery.

Oxalate-upregulated annexin A6 promotes the formation of calcium oxalate kidney stones by exacerbating calcium release-mediated oxidative stress injury in renal tubular epithelial cells and crystal-cell adhesion

Kidney stones result from abnormal biomineralization, although the mechanism behind their formation remains unclear. Annexin A6 (AnxA6), a calcium-dependent lipid-binding protein, is associated with several mineralization-related diseases, but its role in kidney stones is unknown. This study aimed to explore the role and mechanism of AnxA6 in calcium oxalate (CaOx) kidney stones. An in vitro model in which renal tubular epithelial cells (RTECs) were treated with 1 mmol/L oxalate was established, and AnxA6 protein and mRNA expression were examined. Genetic engineering, drug intervention, and biochemical assays were used to investigate the role of AnxA6. The results revealed that AnxA6 was significantly overexpressed in the CaOx model. AnxA6 knockdown in RTECs reduced oxalate-induced oxidative stress, ROS accumulation, and mitochondrial damage, whereas AnxA6 overexpression exacerbated these effects. Blocking ryanodine receptor-mediated calcium release reversed AnxA6-induced oxidative damage. Additionally, AnxA6 increased oxalate adhesion to RTECs by binding to oxalate. In conclusion, AnxA6 contributes to CaOx kidney stone formation by promoting both oxidative stress via calcium release and crystal-cell adhesion by binding to oxalate. This study offers new insight into CaOx kidney stone formation.

Metals in nanomotion: probing the role of extracellular vesicles in intercellular metal transfer

Metals in living organisms and environments are essential for key biological functions such as enzymatic activity, and DNA and RNA synthesis. This means that disruption of metal ion homeostasis and exchange between cells can lead to diseases. EVs are believed to play an essential role in transporting metals between cells, but the mechanism of metal packaging and exchange remains to be elucidated. Here, we established the elemental composition of EVs at the nanoscale and single-vesicle level and showed that the metal content depends on the cell type and culture microenvironment. We also demonstrated that EVs participate in the exchange of metal elements between cells. Specifically, we used two classes of EVs derived from papaya fermented fluid (PaEVs), and decidual mesenchymal stem/stromal cells (DEVs). To show that EVs transfer metal elements to cells, we treated human osteoblast-like cells (MG63) and bone marrow mesenchymal stem cells (BMMSCs) with both classes of EVs. We found that both classes of EVs contained various metal elements, such as Ca, P, Mg, Fe, Na, Zn, and K, originating from their parent cells, but their relative concentrations did not mirror the ones found in the parent cells. Single-particle analysis of P, Ca, and Fe in DEVs and PaEVs revealed varying element masses. Assuming spherical geometry, the mean mass of P was converted to a mean size of 62 nm in DEVs and 24 nm in PaEVs, while the mean sizes of Ca and Fe in DEVs were smaller, converting to 20 nm and 30 nm respectively. When EVs interacted with BMMSCs and MG63, DEVs increased Ca, P, and Fe concentrations in BMMSCs and increased Fe concentration in MG63, while PaEVs increased Ca concentrations in BMMSCs and had no effect on MG63. The EV cargo, including proteins, nucleic acids, and lipids, differs from their origin in composition, and this variation extends to the element composition of EVs in our study. This fundamental understanding of EV-mediated metal exchange between cells could offer a new way of assessing EV functionality by measuring their elemental composition. Additionally, it will contribute novel insights into the mechanisms underlying EV production and their biological activity.

Calcium signaling in mitochondrial intermembrane space

The mitochondrial intermembrane space (IMS) is a highly protected compartment, second only to the matrix. It is a crucial bridge, coordinating mitochondrial activities with cellular processes such as metabolites, protein, lipid, and ion exchange. This regulation influences signaling pathways for metabolic activities and cellular homeostasis. The IMS harbors various proteins critical for initiating apoptotic cascades and regulating reactive oxygen species production by controlling the respiratory chain. Calcium (Ca2+), a key intracellular secondary messenger, enter the mitochondrial matrix via the IMS, regulating mitochondrial bioenergetics, ATP production, modulating cell death pathways. IMS acts as a regulatory site for Ca2+ entry due to the presence of different Ca2+ sensors such as MICUs, solute carriers (SLCs); ion exchangers (LETM1/SCaMCs); S100A1, mitochondrial glycerol-3-phosphate dehydrogenase, and EFHD1, each with unique Ca2+ binding motifs and spatial localizations. This review primarily emphasizes the role of these IMS-localized Ca2+ sensors concerning their spatial localization, mechanism, and molecular functions. Additionally, we discuss how these sensors contribute to the progression and pathogenesis of various human health conditions and diseases.

A bibliometric and visualization analysis of entosis research from 2007 to 2024

Objective

In 2007, entosis was proposed as a form of programmed cell death, distinct from apoptosis. This process involves a living cell (internalized cell) actively invading a neighboring live cell of the same type (host cell), forming a cell-in-cell structure. Recently, entosis has been increasingly associated with cancer, leading to significant advancements in research. Despite this progress, a comprehensive and unbiased review of the current state of entosis research is lacking. This study aims to evaluate the developments in the field of entosis over the past decade and highlight emerging research trends.

Materials and methods

We performed a literature search for studies published since the introduction of the entosis concept, using the Web of Science Core Collection database. The bibliometric analysis was conducted using VOSviewer, CiteSpace, Microsoft Excel, and the Bibliometrix R package.

Results

A total of 196 articles from 39 countries and 346 institutions were included. Between 2007 and 2024, research on entosis has seen rapid growth, with most publications originating from China and the United States. The United States also leads in total citations, with Memorial Sloan Kettering Cancer Center emerging as the top research institution. Sun Qiang is the most prolific author in this field, while Overholtzer M has the highest number of citations. Current Molecular Medicine has published the most articles related to entosis. Frequently occurring keywords include "entosis," "cannibalism," "autophagy," and "apoptosis." In recent years, keywords such as "phagocytosis," "drug resistance," and "human cancers" have surged, indicating a growing focus on understanding the role of entosis in tumor progression and exploring its potential as a therapeutic target for cancer treatment.

Conclusions

This study provides the first bibliometric analysis of entosis, detailing its evolution over the last decade. It highlights critical areas of interest, including the development of inhibitors targeting entosis and their potential clinical applications. This research aims to guide future investigations and serve as a valuable resource for scholars exploring entosis in cancer biology.

Mitigating effects of agmatine on myocardial infarction in rats subjected to isoproterenol

Isoproterenol (ISO) usage is limited by its potential for cardiotoxicity. We sought to investigate the potential of agmatine in mitigating ISO-induced cardiotoxicity. Agmatine (100 mg/kg/day) was intraperitoneally administered to Wistar rats for 7 days in the presence or absence of cardiotoxicity induced by subcutaneous injection of ISO (85 mg/kg) on the sixth and seventh days. ECG parameters, lactate dehydrogenase (LDH), malondialdehyde (MDA), and creatinine phosphokinase (CPK) were investigated. Changes in cardiac tissue were also investigated using H&E staining. The heart weight/body weight ratio increased in ISO-treated rats. In the agmatine + ISO group, the increased heart rate observed in ISO-treated rats was reversed (317.2 ± 10.5 vs 452.2 ± 10.61, P < 0.001). Agmatine ameliorated the change in PR, RR, and ST intervals and the QRS complex, which was reduced by ISO. Treatment with saline, ISO, and agmatine had no significant effect on papillary muscle stimulation (P > 0.05). The administration of agmatine to ISO-receiving group could mitigate several parameters when compared to ISO-receiving group including increasing papillary muscle contraction (0.83 vs 0.71 N/M2 respectively, P < 0.01), decreasing LDH levels (660 ng/ml vs 1080 ng/ml, respectively, P < 0.05), decreasing CPK levels (377 U/l vs 642 U/l, respectively, P < 0.05) and decreasing MDA levels (20.32 µM/l vs 46.83 µM/l, P < 0.001). Coadministration of agmatine and ISO is capable of ameliorating ISO cardiotoxicity by antioxidant effects and controlling the hemostasis of calcium in myocytes.

Role of Calcium in an Experimental Breast Cancer Model Induced by Radiation and Estrogen

Background: Breast cancer, a global health challenge, significantly impacts women worldwide, causing morbidity, disability, and mortality. Objectives: To analyze the role of genes encoding S100 calcium-binding proteins and their relationship with radiation as possible markers in breast carcinogenesis. Methods: The normal MCF-10F cell line was used to study the role of ionizing radiation and estrogen to induce distinct stages of malignancy giving rise to an in vitro experimental breast cancer model. Results: Analysis of an Affymetrix system revealed that the gene expression levels of the S100 calcium-binding protein P (S100P), the S100 calcium-binding protein A14 (S100A14), and the S100 calcium-binding protein A2 (S100A2) were greater in the Tumor2 than the non-tumorigenic Alpha3 or the tumorigenic Alpha5 cell lines; however, the S100 calcium-binding protein A8 (S100A8) and the S100 calcium-binding protein A9 (S100A9) expression levels were higher in A5 than T2 and A3 cell lines. A significant positive association was found between the estrogen receptor alpha gene (ESR1) and S100A14 in Basal and Her2 patients. The association between ESR1 and S100A8 and S100A9 expression levels was positive in Basal patients but negative in Her2, Luminal A, and Luminal B. S100P and S100A14 expression levels were higher in tumor tissues than in normal ones. The estrogen receptor status was positive in patients with high levels of the S10014 gene, but negative in S100A2, S100A8, and S100A9 expression levels. Conclusion: Cell dependence needs to be considered while designing new breast cancer treatments since gene signatures might vary depending on the type of tumor.

Genome-wide identification of CAMTA genes and their expression dependence on light and calcium signaling during seedling growth and development in mung bean

BACKGROUND

Calmodulin-binding transcription activator (CAMTA) is comprised of a group of transcription factors and plays an important role in the Ca2+ signaling pathway, mediating various molecular responses via interactions with other transcription factors and binding to the promoter region of specific genes. Mung beans (Vigna radiata) are one of the most commonly consumed commodities in Asia. To date, CAMTA proteins have not been characterized in this important crop plant.

RESULTS

Eight paralogous VrCAMTA genes were identified and found to be distributed on five of the 11 chromosomes. The proteins possessed CG-1 DNA-binding domains with bipartite NLS signals, ankyrin domains, CaM-binding IQ motifs, and CaM-binding domain (CaMBD). The 2 kb upstream regions of VrCAMTA genes contained sequence motifs of abscisic acid-responsive elements (ABRE) and ethylene-responsive elements (ERE), and binding sites for transcription factors of the bZIP and bHLH domains. Analysis of RNA-seq data from a public repository revealed ubiquitous expression of the VrCAMTA genes, as VrCAMTA1 was expressed at the highest level in seedling leaves, whereas VrCAMTA8 was expressed at the lowest level, which agreed with the RT-qPCR analysis performed on the first true leaves. On day four after leaf emergence, all VrCAMTA genes were upregulated, with VrCAMTA1 exhibiting the highest degree of upregulation. In darkness on day 4, upregulation was not observed in most VrCAMTA genes, except VrCAMTA7, for which a low degree of upregulation was found, whereas no difference was found in VrCAMTA8 expression between light and dark conditions. Treatment with calcium ionophores enhanced VrCAMTA expression under light and/or dark conditions at different times after leaf emergence, suggesting that calcium signaling is involved in the light-induced upregulation of VrCAMTA gene expression.

CONCLUSIONS

The expression dependence of nearly all VrCAMTA genes on light and calcium signaling suggests their possible differential but likely complementary roles during the early stages of mung bean growth and development.

Dual regulation of IP3 receptors by IP3 and PIP2 controls the transition from local to global Ca2+ signals

The spatial organization of inositol 1,4,5-trisphosphate (IP3)-evoked Ca2+ signals underlies their versatility. Low stimulus intensities evoke Ca2+ puffs, localized Ca2+ signals arising from a few IP3 receptors (IP3Rs) within a cluster tethered beneath the plasma membrane. More intense stimulation evokes global Ca2+ signals. Ca2+ signals propagate regeneratively as the Ca2+ released stimulates more IP3Rs. How is this potentially explosive mechanism constrained to allow local Ca2+ signaling? We developed methods that allow IP3 produced after G-protein coupled receptor (GPCR) activation to be intercepted and replaced by flash photolysis of a caged analog of IP3. We find that phosphatidylinositol 4,5-bisphosphate (PIP2) primes IP3Rs to respond by partially occupying their IP3-binding sites. As GPCRs stimulate IP3 formation, they also deplete PIP2, relieving the priming stimulus. Loss of PIP2 resets IP3R sensitivity and delays the transition from local to global Ca2+ signals. Dual regulation of IP3Rs by PIP2 and IP3 through GPCRs controls the transition from local to global Ca2+ signals.

Multi-Omics Profiling Unveils the Complexity and Dynamics of Immune Infiltrates in Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is a highly heterogeneous malignancy. The reasons behind the global rise in the incidence of ICC remain unclear, and there exists limited knowledge regarding the immune cells within the tumor microenvironment (TME). In this study, a more comprehensive analysis of multi-omics data was performed using machine learning methods. The study found that the immunoactivity of B cells, macrophages, and T cells in the infiltrating immune cells of ICC exhibits a significantly higher level of immunoactivity in comparison to other immune cells. During the immune sensing and response, the effect of antigen-presenting cells (APCs) such as B cells and macrophages on activating NK cells was weakened, while the effect of activating T cells became stronger. Simultaneously, four distinct subpopulations, namely BLp, MacrophagesLp, BHn, and THn, have been identified from the infiltrating immune cells, and their corresponding immune-related marker genes have been identified. The immune sensing and response model of ICC has been revised and constructed based on our current comprehension. This study not only helps to deepen the understanding the heterogeneity of infiltrating immune cells in ICC, but also may provide valuable insights into the diagnosis, evaluation, treatment, and prognosis of ICC.

Implicit Solvent with Explicit Ions Generalized Born Model in Molecular Dynamics: Application to DNA

The ion atmosphere surrounding highly charged biomolecules, such as nucleic acids, is crucial for their dynamics, structure, and interactions. Here, we develop an approach for the explicit treatment of ions within an implicit solvent framework suitable for atomistic simulations of biomolecules. The proposed implicit solvent/explicit ions model, GBION, is based on a modified generalized Born (GB) model; it includes separate, modified GB terms for solute-ion and ion-ion interactions. The model is implemented in the AMBER package (version 24), and its performance is thoroughly investigated in atomistic molecular dynamics (MD) simulations of double-stranded DNA on a microsecond time scale. The aggregate characteristics of monovalent (Na+ and K+) and trivalent (Cobalt Hexammine, CoHex3+) counterion distributions around double-stranded DNA predicted by the model are in reasonable agreement with the experiment (where available), all-atom explicit water MD simulations, and the expectation from the Manning condensation theory. The radial distributions of monovalent cations around DNA are reasonably close to the ones obtained using the explicit water model: expressed in units of energy, the maximum deviations of local ion concentrations from the explicit solvent reference are within 1 kBT, comparable to the corresponding deviations expected between different established explicit water models. The proposed GBION model is able to simulate DNA fragments in a large volume of solvent with explicit ions with little additional computational overhead compared with the fully implicit GB treatment of ions. Ions simulated using the developed model explore conformational space at least 2 orders of magnitude faster than in the explicit solvent. These advantages allowed us to observe and explore an unexpected "stacking" mode of DNA condensation in the presence of trivalent counterions (CoHex3+) that was revealed by recent experiments.

A red cell membrane-camouflaged nanoreactor for enhanced starvation/chemodynamic/ion interference therapy for breast cancer

In this study, a multifunctional Cu-doped CaO2 nanoreactor loaded with GOx and camouflaged with a folic acid-modified cell membranewas developed for breast cancer treatment. The as-developed composite nanoreactor showed a synergistic effect on calcium overload to damage mitochondria, thus killing tumor cells to achieve ion interference therapy (IIT). The loaded GOx could deplete glucose to "starve" tumor cells. The H2O2 released by CaO2 decomposition and enzyme catalytic reactions from GOx could not only be highly toxic in the tumor microenvironment but also enhance the efficiency of chemodynamic therapy (CDT) with Cu2+. The red blood cell membranes modified by folic acid achieved a combination of active targeting and passive targeting, thereby enhancing the targeting ability of the as-prepared multifunctional composite nanoreactor and prolonging its retention time at the tumor sites for more than 48 h.

Calcium-binding protein TgpCaBP regulates calcium storage of the zoonotic parasite Toxoplasma gondii

Toxoplasma gondii, the causative parasite of toxoplasmosis, is an apicomplexan parasite that infects warm-blooded mammals. The ability of the calcium-binding proteins (CBPs) to transport large amounts of Ca2+ appears to be critical for the biological activity of T. gondii. However, the functions of some members of the CBP family have not yet been deciphered. Here, we characterized a putative CBP of T. gondii, TgpCaBP (TGME49_229480), which is composed of four EF-hand motifs with Ca2+-binding capability. TgpCaBP was localized in the cytosol and ER of T. gondii, and parasites lacking the TgpCaBP gene exhibited diminished abilities in cell invasion, intracellular growth, egress, and motility. These phenomena were due to the abnormalities in intracellular Ca2+ efflux and ER Ca2+ storage, and the reduction in motility was associated with a decrease in the discharge of secretory proteins. Therefore, we propose that TgpCaBP is a Ca2+ transporter and signaling molecule involved in Ca2+ regulation and parasitization in the hosts.IMPORTANCECa2+ signaling is essential in the development of T. gondii. In this study, we identified a calcium-binding protein in T. gondii, named TgpCaBP, which actively regulates intracellular Ca2+ levels in the parasite. Deletion of the gene coding for TgpCaBP caused serious deficits in the parasite's ability to maintain a stable intracellular calcium environment, which also impaired the secretory protein discharged from the parasite, and its capacity of gliding motility, cell invasion, intracellular growth, and egress from host cells. In summary, we have identified a novel calcium-binding protein, TgpCaBP, in the zoonotic parasite T. gondii, which is a potential therapeutic target for toxoplasmosis.

Vitrification of Mammalian Oocytes: Recent Studies on Mitochondrial Dysfunction

Vitrification of reproductive cells is definitely essential and integral in animal breeding, as well as in assisted reproduction. However, issues accompanied with this technology such as decreased oocyte competency and relatively low embryo survival rates appear to be a tough conundrum that has long perplexed us. As significant organelles in cell metabolism, mitochondria play pivotal roles in numerous pathways. Nonetheless, extensive evidence has demonstrated that vitrification can seriously impair mitochondrial function in mammalian oocytes. Thus, in this article, we summarize the current progress in oocyte vitrification and particularly outline the common mitochondrial abnormalities alongside subsequent injury cascades seen in mammalian oocytes following vitrification. Based on existing literature, we tentatively come up with the potential mechanisms related to mitochondrial dysfunction and generalize efficacious ways which have been recommended to restore mitochondrial function.

Quantification of cytosolic 'free' calcium in isolated coral cells with confocal microscopy

Despite its prominent role as an intracellular messenger in all organisms, cytosolic free calcium ([Ca2+]i) has never been quantified in corals or cnidarians in general. Ratiometric calcium dyes and cell imaging have been key methods in successful research on [Ca2+]i in model systems, and could be applied to corals. Here, we developed a procedure to quantify [Ca2+]i in isolated cells from the model coral species Stylophora pistillata using Indo-1 and confocal microscopy. We quantified [Ca2+]i in coral cells with and without intracellular dinoflagellate symbionts, and verified our procedure on cultured mammalian cells. We then used our procedure to measure changes in [Ca2+]i in coral cells exposed to a classic inhibitor of [Ca2+]i regulation, thapsigargin, and also used it to record elevations in [Ca2+]i in coral cells undergoing apoptosis. Our procedure paves the way for future studies into intracellular calcium in corals and other cnidarians.

Spatiotemporal orchestration of calcium-cAMP oscillations on AKAP/AC nanodomains is governed by an incoherent feedforward loop

The nanoscale organization of enzymes associated with the dynamics of second messengers is critical for ensuring compartmentation and localization of signaling molecules in cells. Specifically, the spatiotemporal orchestration of cAMP and Ca2+ oscillations is critical for many cellular functions. Previous experimental studies have shown that the formation of nanodomains of A-kinase anchoring protein 79/150 (AKAP150) and adenylyl cyclase 8 (AC8) on the surface of pancreatic MIN6 β cells modulates the phase of Ca2+-cAMP oscillations from out-of-phase to in-phase. In this work, we develop computational models of the Ca2+/cAMP pathway and AKAP/AC nanodomain formation that give rise to the two important predictions: instead of an arbitrary phase difference, the out-of-phase Ca2+/cAMP oscillation reaches Ca2+ trough and cAMP peak simultaneously, which is defined as inversely out-of-phase; the in-phase and inversely out-of-phase oscillations associated with Ca2+-cAMP dynamics on and away from the nanodomains can be explained by an incoherent feedforward loop. Factors such as cellular surface-to-volume ratio, compartment size, and distance between nanodomains do not affect the existence of in-phase or inversely out-of-phase Ca2+/cAMP oscillation, but cellular surface-to-volume ratio and compartment size can affect the time delay for the inversely out-of-phase Ca2+/cAMP oscillation while the distance between two nanodomains does not. Finally, we predict that both the Turing pattern-generated nanodomains and experimentally measured nanodomains demonstrate the existence of in-phase and inversely out-of-phase Ca2+/cAMP oscillation when the AC8 is at a low level, consistent with the behavior of an incoherent feedforward loop. These findings unveil the key circuit motif that governs cAMP and Ca2+ oscillations and advance our understanding of how nanodomains can lead to spatial compartmentation of second messengers.

Calcium‐dependent antimicrobials: Nature‐inspired materials and designs

Bacterial infection remains a major complication answering for the failures of various implantable medical devices. Tremendous extraordinary advances have been published in the design and synthesis of antimicrobial materials addressing this issue; however, the clinical translation has largely been blocked due to the challenge of balancing the efficacy and safety of these materials. Here, calcium's biochemical features, natural roles in pathogens and the immune systems, and advanced uses in infection medications are illuminated, showing calcium is a promising target for developing implantable devices with less infection tendency. The paper gives a historical overview of biomedical uses of calcium and summarizes calcium's merits in coordination, hydration, ionization, and stereochemistry for acting as a structural former or trigger in biological systems. It focuses on the involvement of calcium in pathogens' integrity, motility, and metabolism maintenance, outlining the potential antimicrobial targets for calcium. It addresses calcium's uses in the immune systems that the authors can learn from for antimicrobial synthesis. Additionally, the advances in calcium's uses in infection medications are highlighted to sketch the future directions for developing implantable antimicrobial materials. In conclusion, calcium is at the nexus of antimicrobial defense, and future works on taking advantage of calcium in antimicrobial developments are promising in clinical translation.

Impact of Metal Ions on Cellular Functions: A Focus on Mesenchymal Stem/Stromal Cell Differentiation

Metals play a crucial role in the human body, especially as ions in metalloproteins. Essential metals, such as calcium, iron, and zinc are crucial for various physiological functions, but their interactions within biological networks are complex and not fully understood. Mesenchymal stem/stromal cells (MSCs) are essential for tissue regeneration due to their ability to differentiate into various cell types. This review article addresses the effects of physiological and unphysiological, but not directly toxic, metal ion concentrations, particularly concerning MSCs. Overloading or unbalancing of metal ion concentrations can significantly impair the function and differentiation capacity of MSCs. In addition, excessive or unbalanced metal ion concentrations can lead to oxidative stress, which can affect viability or inflammation. Data on the effects of metal ions on MSC differentiation are limited and often contradictory. Future research should, therefore, aim to clarify the mechanisms by which metal ions affect MSC differentiation, focusing on aspects such as metal ion interactions, ion concentrations, exposure duration, and other environmental conditions. Understanding these interactions could ultimately improve the design of biomaterials and implants to promote MSC-mediated tissue regeneration. It could also lead to the development of innovative therapeutic strategies in regenerative medicine.