Intracellular Calcium Regulation Research Articles

Transcriptome analysis of effects of Tecrl deficiency on cardiometabolic and calcium regulation in cardiac tissue.

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a hereditary heart disease characterized by bidirectional or polymorphic ventricular tachycardia and an increased risk of sudden cardiac death. Although trans-2,3-enoyl-CoA reductase like (TECRL) is a newly reported pathogenic gene leading to CPVT that can influence intracellular calcium regulation, the unidentified mechanism underlying the pathogenesis of TECRL deficiency-mediated CPVT remains mainly elusive. In the present study, Tecrl knockout (KO) mice were established and the differentially expressed genes (DEGs) were investigated by RNA-sequencing from the heart tissues. In addition, 857 DEGs were identified in Tecrl KO mice. Subsequently, a weighted gene co-expression network analysis was conducted to discern the pivotal pathways implicated in the Tecrl-mediated regulatory network. Moreover, pathway mapping analyses demonstrated that essential metabolism-related pathways were significantly enriched, notably the fatty acid metabolic process and calcium regulation. Collectively, the data suggested a synergistic relationship between Tecrl deficiency and cardiometabolic and calcium regulation during the development of CPVT. Therefore, further studies on the potential function of TECRL in cardiac tissues would be beneficial to elucidate the pathogenesis of CPVT.

Targeting SLC3A2 Sensitizes AML Cells Towards NK Cell-Mediated Killing

Acute myeloid leukemia (AML) is an aggressive hematological malignancy with poor prognosis; hence, new therapeutic strategies are urgently needed. Natural Killer (NK) cells play a key role in tumor immune surveillance, but their anti-tumor activity in AML is often attenuated due to immunosuppressive effects of the malignant cells. Thus, strategies to restore NK cell function has therapeutic potential by boosting endogenous NK cells. In particular, the identification of cell surface proteins on AML cells that inhibit NK cell-mediated killing may reveal new targets for antibody-based therapies. To identify such targets, we performed a pooled CRISPR screen directed to 1389 cell surface genes in Mono-mac-6 (MM6), a human AML cell line. The MM6 cells were co-cultured with primary human NK cells for four days in media supplemented with the cytokines IL-2 and IL-15. Among the top hits were several genes coding for MHC class I molecules, which are known negative regulators of NK cells, demonstrating that the screen was robust. Notably, the screen also identified that SLC3A2 disruption sensitized the MM6 cells towards NK cell-mediated killing. SLC3A2 encodes the heavy chain of the transmembrane protein CD98 (CD98hc), which plays a key role in integrin signaling, regulation of intracellular calcium and the transport of L-type amino acids. CRISPR-mediated deletion of SLC3A2 in MM6 cells resulted in a two-fold downregulation of the transcripts of several inhibitory ligands of NK cells, including HLA-A, HLA-B, HLA-C and HLA-E. Upon co-culture, loss of SLC3A2 expression in MM6 cells induced an upregulation of the degranulation marker CD107a on NK cells (p<0.01), resulting in increased killing of the AML cells. CD98hc consists of two functional domains - one responsible for integrin signaling and the other responsible for amino acid transport. To identify which of these processes affect the sensitivity of AML cells towards NK cell-mediated killing, we performed rescue experiments by overexpression of mutated SLC3A2 cDNAs following SLC3A2 knockdown in MM6 cells. Overexpression of SLC3A2 wild-type or an integrin signaling deficient SLC3A2 cDNA rescued the inhibitory effect on NK cells. In contrast, the SLC3A2 variant that lacked the amino acid transportation domain failed to inhibit NK cells. These findings suggest that it is the amino acid transportation function of SLC3A2 that regulates the sensitivity of AML cells to NK cells. To validate these findings, we cultured MM6 cells in media deprived of three key amino acids (leucine, isoleucine and phenylalanine) transported across the plasma membrane by CD98. Consistent with our previous findings, culturing the MM6 cells in the amino acid deprived media resulted in a two-fold downregulation of HLA class I molecules (p<0.001) accompanied by an increased killing by NK cells. To assess the clinical relevance of these findings, we measured CD98hc expression on AML patient samples and corresponding normal bone marrow cells. CD98 levels were about 1.8-fold higher (p<0,001) in the AML samples (n = 30) compared to normal bone marrow cells (n = 5). Treating the AML patient cells with a monoclonal antibody targeting CD98 resulted in a 1.63-fold increase (p<0.0001) in NK cell-mediated killing. Corresponding treatments using normal bone marrow cells resulted in a 1.36-fold (p<0.01) increase in NK cell-mediated killing. Intriguingly, the CD98 antibody also negatively affected the viability (1.41-fold, p<0.0001) of AML patient cells in the absence of NK cells, this effect was not observed on normal bone marrow cells. Taken together, we here performed CRISPR screening on AML cells co-cultured with NK cells and identified SLC3A2 as a novel regulator of NK cells. Mechanistically, it is the amino acid transport function of SLC3A2 that regulate the sensitization of AML cells towards NK cell killing. Targeting of CD98 using a monoclonal antibody selectively increased NK cell-mediated killing of AML patient cells compared to normal bone marrow cells. These findings highlight CD98 as a new promising target on AML that boost NK cell-mediated tumor immune surveillance.

Abstract 17328: A Case of Reversible Severe Systolic Cardiomyopathy; Thinking Outside the Box

Introduction: Non-ischemic systolic cardiomyopathy is associated with significant morbidity and mortality. Prompt evaluation and timely removal of the potential insult may lead to reverse remodeling and recovery of the left ventricular (LV) systolic function. Case: A 39-year-old female with BMI 40 presented with dyspnea and bilateral lower extremity edema. Vital signs significant for mild tachycardia and hypertension. ECG showed sinus tachycardia. Physical exam revealed bibasilar crackles and 3+ pitting edema of the lower extremities. Laboratory significant for NTpro BNP 563 pg/dL and TSH <0.005 IU/mL with a free T4 of 2.73 ng/dL. Chest x-ray showed pulmonary vascular congestion. Echocardiogram showed severely reduced LV systolic function with ejection fraction (EF) of 27%, global LV hypokinesis and diastolic LV diameter of 6.85 cm. No significant atrial or ventricular arrhythmias noted on Telemetry. A CT angiography of the coronary arteries showed no evidence of calcification or obstructive coronary disease. Additional labs revealed severely elevated TSH receptor antibody and thyroid stimulating immunoglobulin. Diffuse thyroid enlargement noted on ultrasound. Patient was diagnosed with Grave’s disease (GD) with Burch-Wartofsky score of 30 indicating an impending thyroid storm. She was treated with Metoprolol and Methimazole. She underwent intravenous diuresis and was started on guideline-directed medical therapy for systolic cardiomyopathy. In follow-up after 6 months, her TSH had normalized. On repeat imaging, her LVEF improved to > 50% with diastolic LV diameter of 5.6 cm. Discussion: This patient was diagnosed with non-ischemic dilated systolic cardiomyopathy due to severe hyperthyroidism from GD. Thyrotoxicosis-induced systolic cardiomyopathy occurs in about 1% of patients with GD and is associated with increased morbidity and mortality. Excess thyroid hormones in thyrotoxicosis can affect multiple regulatory and structural genes of cardiac myocytes resulting in abnormal intracellular calcium regulation and impaired LV systolic and diastolic function. Our experience is consistent with literature demonstrating the importance of timely diagnosis and treatment of this reversible cause of systolic cardiomyopathy.

ITPR1-associated spinocerebellar ataxia with craniofacial features-additional evidence for germline mosaicism.

Inositol 1,4,5-triphosphate receptor type 1 (ITPR1) is an endoplasmic reticulum-bound intracellular inositol triphosphate receptor involved in the regulation of intracellular calcium. Pathogenic variants in ITPR1 are associated with spinocerebellar ataxia (SCA) types 15/16 and 29 and have recently been implicated in a facial microsomia syndrome. In this report, we present a family with three affected individuals found to have a heterozygous missense c.800C > T (predicted p.Thr267Met) who present clinically with a SCA29-like syndrome. All three individuals presented with varying degrees of ataxia, developmental delay, and apparent intellectual disability, as well as craniofacial involvement-an uncommon finding in patients with SCA29. The variant was identified using clinical exome sequencing and validated with Sanger sequencing. It is presumed to be inherited via parental germline mosaicism. We present our findings to provide additional evidence for germline mosaic inheritance of SCA29, as well as to expand the clinical phenotype of the syndrome.

Lercanidipine alleviates doxorubicin-induced lung injury by regulating PERK/CHOP and Bax/Bcl 2/Cyt c pathways.

Doxorubicin (DOX), which is used to treat various cancers and hematological malignancies, has limited therapeutic application due to its toxicity in tissues and organs. These toxic effects occur through alterations in intracellular calcium regulation, elevated cell stress and oxidative damage, and increased apoptosis. Lercanidipine (LRD) is a long-acting antihypertensive calcium channel blocker with anti-inflammatory, anti-apoptotic, and antioxidant effects. The aim of this study was to investigate the effect of LRD on DOX-induced lung toxicity. Four groups (control, DOX, DOX + 0.5 LRD, and DOX + 2 LRD) totaling 32 rats were established. TNF-α levels in the lung tissues were detected by immunohistochemistry, and the tissues were subjected to histopathological examination. In determining oxidative stress, total antioxidant status (TAS) and total oxidative stress (TOS) were determined using spectrophotometry, and the oxidative stress index (OSI) value was calculated. The mRNA relative expression levels of the genes were evaluated by RT-qPCR. It was determined that inflammatory and oxidative stress markers and pro-apoptotic gene levels were increased and anti-apoptotic gene levels were decreased in the lung tissues of the DOX-administered group. In addition, histopathological changes were significantly increased. Although it was not statistically significant, inflammation, oxidative stress, and apoptosis were reduced, as were other histopathological indicators, in the group that received LRD (0.5mg/kg). Inflammation, oxidative stress, and apoptosis were found to be statistically reduced and corroborated by histological findings in the group given LRD (2mg/kg). In conclusion, it was determined that LRD had an ameliorative effect on DOX-induced lung toxicity in an experimental animal model.

L-type calcium channel antagonist isradipine age-dependently decreases plaque associated dystrophic neurites in 5XFAD mouse model

Epidemiological studies suggest that L-type calcium channel (LTCC) antagonists may reduce the incidence of age-associated neurodegenerative diseases including Alzheimer's disease (AD). However, the neuroprotective mechanism of LTCC antagonists is unknown. Amyloid-β (Aβ) pathology disrupts intracellular calcium signaling, which regulates lysosomes and microglial responses. Neurons near Aβ plaques develop dystrophic neurites, which are abnormal swellings that accumulate lysosomes. Further, microglia accumulate around Aβ plaques and secrete inflammatory cytokines. We hypothesized that antagonism of LTCCs with isradipine would reduce Aβ plaque-associated dystrophic neurites and inflammatory microglia in the 5XFAD mouse model by restoring normal intracellular calcium regulation. To test this hypothesis, we treated 6- and 9-month-old 5XFAD mice with isradipine and tested behavior, examined Aβ plaques, microglia, and dystrophic neurites. We found that isradipine treatment age-dependently reduces dystrophic neurites and leads to trending decreases in Aβ but does not modulate plaque associated microglia regardless of age. Our findings provide insight into how antagonizing LTCCs alters specific cell types in the Aβ plaque environment, providing valuable information for potential treatment targets in future AD studies.

Massive Idiopathic Myocardial Calcification Associated With ANK2 Mutation of Uncertain Significance

Massive myocardial calcification is a rare condition for which both diagnosis and therapy are not clearly established in the literature. Although imaging features are often nonspecific, the combination of imaging pattern and clinical history may help determine the clinical implications of myocardial calcification. Here, we report a case of massive idiopathic calcification associated with a rare heterozygous ANK2 mutation of uncertain significance. Mutations in ANK2 are linked to abnormal regulation of intracellular sodium and calcium, predisposing patients to arrhythmias, but there is no description of myocardial calcification.

Age-dependent effect of insulin in the regulation of intracellular calcium in ventricular cardiomyocytes.

In this study, we wanted to verify whether the effect of insulin on calcium homeostasis depends on the heart's development stage. Using a quantitative 3D confocal microscopy, we tested the effect of a high insulin concentration (100 µU) in freshly cultured ventricular cardiomyocytes from newborn and adult rats. Our results showed that the cytosolic basal level of calcium was higher in newborn cardiomyocytes with no change in the nuclear basal calcium level compared with the adult cardiomyocytes; in addition, insulin induced a slow increase of cytosolic and nuclear calcium in newborn ventricular cardiomyocytes, followed by two phases. However, the first phase of slow cytosolic and nuclear calcium increase was absent in adult rat ventricular cardiomyocytes. Furthermore, the time to the onset of increase of cytosolic and nuclear calcium was longer in newborn cardiomyocytes compared with adults. Moreover, the time to peak of the calcium transient was shorter in newborns than in adult cardiomyocytes. These results demonstrate that insulin differently regulates calcium homeostasis in newborns than in adult cardiomyocytes. Thus, newborn rat cardiomyocytes, commonly used in research as a model for adult cardiomyocytes, should be used with caution when dealing with insulin in normal and disease conditions.

Betaine promotes osteogenic differentiation in immortalized human dental pulp-derived cells

ObjectivesThis study aimed to evaluate the effect of betaine (BET) on immortalized human dental pulp stem cell (ihDP) osteogenic differentiation.Materials and methodshDPs were immortalized using SV40 T-antigen transfection. Characterization, multilineage differentiation, proliferation, cell cycle, colony-forming unit, and cellular senescence were evaluated (n = 4). The effect of BET on ihDP response was assessed (n = 4). Osteogenic differentiation was detected using ALP, ARS staining, and RT-qPCR (n = 4). To investigate the involvement of calcium signaling, the cells were pretreated with either 8-(NN-diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8) or thapsigargin before BET treatment (n = 6).ResultsihDPs retained similar phenotypic characteristics presented in hDPs but exhibited an increase in cell proliferation and extended culture to passage 25. An increased proportion of cells in S and G2/M phases without senescence was observed in ihDPs. BET (50 mM) treatment significantly increased mineral deposition at 14 days and upregulated ALP, MSX2, BMP2, and RUNX2 expression. TMB-8 pretreatment reduced the effect of BET-induced ihDP osteogenic differentiation, whereas thapsigargin promoted osteogenic differentiation in ihDPs synergistically with BET.ConclusionihDPs showed superior proliferation ability and a longer life span, which could serve as a promising cell for regenerative dentistry. BET promoted odonto/osteogenic differentiation via intracellular calcium regulation.

Calcium and activity-dependent signaling in the developing cerebral cortex.

Calcium influx can be stimulated by various intra- and extracellular signals to set coordinated gene expression programs into motion. As such, the precise regulation of intracellular calcium represents a nexus between environmental cues and intrinsic genetic programs. Mounting genetic evidence points to a role for the deregulation of intracellular calcium signaling in neuropsychiatric disorders of developmental origin. These findings have prompted renewed enthusiasm for understanding the roles of calcium during normal and dysfunctional prenatal development. In this Review, we describe the fundamental mechanisms through which calcium is spatiotemporally regulated and directs early neurodevelopmental events. We also discuss unanswered questions about intracellular calcium regulation during the emergence of neurodevelopmental disease, and provide evidence that disruption of cell-specific calcium homeostasis and/or redeployment of developmental calcium signaling mechanisms may contribute to adult neurological disorders. We propose that understanding the normal developmental events that build the nervous system will rely on gaining insights into cell type-specific calcium signaling mechanisms. Such an understanding will enable therapeutic strategies targeting calcium-dependent mechanisms to mitigate disease.

Quercetin protects H9c2 cells against hyperosmotic shock via regulation of intracellular calcium and mitochondrial potential

Quercetin protects H9c2 cells against hyperosmotic shock via regulation of intracellular calcium and mitochondrial potential

Pan-cancer analyses reveal the genetic and pharmacogenomic landscape of transient receptor potential channels

Transient-receptor potential (TRP) channels comprise a diverse family of ion channels, which play important roles in regulation of intracellular calcium. Emerging evidence has revealed the critical roles of TRP channels in tumor development and progression. However, we still lack knowledge about the genetic and pharmacogenomics landscape of TRP genes across cancer types. Here, we comprehensively characterized the genetic and transcriptome alterations of TRP genes across >10,000 patients of 33 cancer types. We revealed prevalent somatic mutations and copy number variation in TRP genes. In particular, mutations located in transmembrane regions of TRP genes were likely to be deleterious mutations (p-values < 0.001). Genetic alterations were correlated with transcriptome dysregulation of TRP genes, and we found that TRPM2, TRPM8, and TPRA1 showed extent dysregulation in cancer. Patients with TRP gene alterations were with significantly higher hypoxia scores, tumor mutation burdens, tumor stages and grades, and poor survival. The alterations of TRP genes were significantly associated with the activity of cancer-related pathways. Moreover, we found that the expression of TRP genes were potentially useful for development of targeted therapies. Our study provided the landscape of genomic and transcriptomic alterations of TPRs across 33 cancer types, which is a comprehensive resource for guiding both mechanistic and therapeutic analyses of the roles of TRP genes in cancer. Identifying the TRP genes with extensive genetic alterations will directly contribute to cancer therapy in the context of predictive, preventive, and personalized medicine.

Galvanotaxis of ciliates: spatiotemporal dynamics of Coleps hirtus under electric fields

Galvanotaxis describes the functional response of organisms to electric fields. In ciliates, the electric field influences the electrophysiology, and thus, the cilia beat dynamics. This leads to a change of the swimming direction toward the cathode. The dynamical response to electric fields of Coleps hirtus has not been studied since the observations of Verworn in 1890 Pflüger Arch. 46 267–303. While galvanotaxis has been studied in other ciliates, C. hirtus exhibit properties not found elsewhere, such as biomineralization processes of alveolar plates with impact on the intracellular calcium regulation and a bimodal resting membrane potential, which leads to unique electrophysiological driven bimodal swimming dynamics. Here, we statistically analyze the galvanotactic dynamics of C. hirtus by automated cell tracking routines. We found that the number of cells that show a galvanotactic response, increases with the increase of the applied electric field strength with a mean at about 2.1 V cm−1. The spatiotemporal swimming dynamics change and lead to a statistical increase of linear elongated cell trajectories that point toward the cathode. Further, the increase of the electric fields decreases the mean velocity variance for electric fields larger than about 1.3 V cm−1, while showing no significant change in the absolute velocity for any applied electric field. Fully functional galvanotactic responses were observed at a minimum extracellular calcium concentration of about 5 μM. The results add important insights to the current understanding of cellular dynamics of ciliates and suggest that the currently accepted model lacks the inclusion of the swimming dynamics and the complex calcium regulatory system of the cell. The results of this study not only extend the fundamental understanding of current physical models for galvanotaxis and C. hirtus dynamics, but also open possibilities for technical applications, such as biosensors or microrobots in the future.

The Plasma Membrane Ca2+-ATPase, a Molecular Target for Tau-induced Cytosolic Calcium Dysregulation

Disruption of calcium (Ca2+) homeostasis is emerging as a prevalent feature of aging and aging-associated neurodegenerative diseases, including Alzheimer’s disease (AD), the most common type of tauopathy. This disease is characterized by the combined presence of extracellular neuritic plaques composed by amyloid β-peptides (Aβ) and neurofibrillary tangles of tau. The association of calcium dyshomeostasis with Aβ has been extensively studied, however its link with tau has been less investigated. Thus, this review will concentrate on the functional link between tau and the plasma membrane Ca2+ pump (PMCA) and other membrane proteins involved in the regulation of intracellular calcium and/or its association with neurodegeneration.

Astroglia in the Vulnerability to and Maintenance of Stress-Mediated Neuropathology and Depression.

Significant stress exposure and psychiatric depression are associated with morphological, biochemical, and physiological disturbances of astrocytes in specific brain regions relevant to the pathophysiology of those disorders, suggesting that astrocytes are involved in the mechanisms underlying the vulnerability to or maintenance of stress-related neuropathology and depression. To understand those mechanisms a variety of studies have probed the effect of various modalities of stress exposure on the metabolism, gene expression and plasticity of astrocytes. These studies have uncovered the participation of various cellular pathways, such as those for intracellular calcium regulation, neuroimmune responses, extracellular ionic regulation, gap junctions-based cellular communication, and regulation of neurotransmitter and gliotransmitter release and uptake. More recently epigenetic modifications resulting from exposure to chronic forms of stress or to early life adversity have been suggested to affect not only neuronal mechanisms but also gene expression and physiology of astrocytes and other glial cells. However, much remains to be learned to understand the specific role of those and other modifications in the astroglial contribution to the vulnerability to and maintenance of stress-related disorders and depression, and for leveraging that knowledge to achieve more effective psychiatric therapies.

Multi-Scale Computational Modeling of Spatial Calcium Handling From Nanodomain to Whole-Heart: Overview and Perspectives.

Regulation of intracellular calcium is a critical component of cardiac electrophysiology and excitation-contraction coupling. The calcium spark, the fundamental element of the intracellular calcium transient, is initiated in specialized nanodomains which co-locate the ryanodine receptors and L-type calcium channels. However, calcium homeostasis is ultimately regulated at the cellular scale, by the interaction of spatially separated but diffusively coupled nanodomains with other sub-cellular and surface-membrane calcium transport channels with strong non-linear interactions; and cardiac electrophysiology and arrhythmia mechanisms are ultimately tissue-scale phenomena, regulated by the interaction of a heterogeneous population of coupled myocytes. Recent advances in imaging modalities and image-analysis are enabling the super-resolution reconstruction of the structures responsible for regulating calcium homeostasis, including the internal structure of nanodomains themselves. Extrapolating functional and imaging data from the nanodomain to the whole-heart is non-trivial, yet essential for translational insight into disease mechanisms. Computational modeling has important roles to play in relating structural and functional data at the sub-cellular scale and translating data across the scales. This review covers recent methodological advances that enable image-based modeling of the single nanodomain and whole cardiomyocyte, as well as the development of multi-scale simulation approaches to integrate data from nanometer to whole-heart. Firstly, methods to overcome the computational challenges of simulating spatial calcium dynamics in the nanodomain are discussed, including image-based modeling at this scale. Then, recent whole-cell models, capable of capturing a range of different structures (such as the T-system and mitochondria) and cellular heterogeneity/variability are discussed at two different levels of discretization. Novel methods to integrate the models and data across the scales and simulate stochastic dynamics in tissue-scale models are then discussed, enabling elucidation of the mechanisms by which nanodomain remodeling underlies arrhythmia and contractile dysfunction. Perspectives on model differences and future directions are provided throughout.

Intracellular MUC20 variant 2 maintains mitochondrial calcium homeostasis and enhances drug resistance in gastric cancer.

Signet ring cell carcinoma (SRCC) is a particular histologic variant of gastric cancer (GC). However, the critical factor related to the aggressive characteristics of SRCC has not been determined. We collected surgically resected tissues from 360 GC patients in the Kumamoto University cohort and generated survival curves via the Kaplan-Meier method. In vitro, we identified the specific transcript variant of MUC20 in SRCC cells by direct sequencing and investigated the role of MUC20 in GC progression using GC cells with MUC20 silencing and forced expression. In vivo, we examined chemoresistance using MUC20 variant 2 (MUC20v2)-overexpressing non-SRCC cells to construct a xenograft mouse model. We analyzed a comprehensive GC cell line database to identify the specifically expressed genes in gastric SRCC. We focused on MUC20 and investigated its role in GC progression. Survival analysis revealed that GC patients with high MUC20 expression exhibited a poor prognosis and that MUC20 expression was significantly correlated with SRCC histological type. Moreover, we found that gastric SRCC cells specifically expressed MUC20v2, which was dominantly expressed in the cytoplasm. Silencing MUC20v2 caused cell death with characteristic morphological changes in gastric SRCC cells. To further determine the types of cell death, we examined apoptosis, pyroptosis and ferroptosis by detecting cleaved PARP, gasdermin E-N-terminal (GSDME-N), and lipid reactive oxygen species (ROS) levels, respectively. We found that apoptosis and pyroptosis occurred in MUC20-silenced gastric SRCC cells. In addition, MUC20v2-overexpressing GC cells exhibited chemoresistance to cisplatin (CDDP) and paclitaxel (PTX). RNA sequencing revealed that the pathways involved in intracellular calcium regulation were significantly upregulated in MUC20v2-overexpressing GC cells. Notably, forced expression of MUC20v2 in the cytoplasm of GC cells led to the maintenance of mitochondrial calcium homeostasis and mitochondrial membrane potential (MMP), which promoted cell survival and chemoresistance by suppressing apoptosis and pyroptosis. Finally, we investigated the significance of MUC20v2 in a xenograft model treated with CDDP and showed that MUC20v2 overexpression caused chemoresistance by inhibiting cell death. These findings highlight the novel functions of MUC20v2, which may confer cell survival and drug resistance in GC cells. MUC20v2 protects GC cells from apoptosis and pyroptosis by maintaining mitochondrial calcium levels and mitochondrial membrane potential and subsequently induces drug resistance.

TUNAR lncRNA Encodes a Microprotein that Regulates Neural Differentiation and Neurite Formation by Modulating Calcium Dynamics.

Long noncoding RNAs (lncRNAs) are regulatory molecules which have been traditionally considered as “non-coding”. Strikingly, recent evidence has demonstrated that many non-coding regions, including lncRNAs, do in fact contain small-open reading frames that code for small proteins that have been called microproteins. Only a few of them have been characterized so far, but they display key functions in a wide variety of cellular processes. Here, we show that TUNAR lncRNA encodes an evolutionarily conserved microprotein expressed in the nervous system that we have named pTUNAR. pTUNAR deficiency in mouse embryonic stem cells improves their differentiation potential towards neural lineage both in vitro and in vivo. Conversely, pTUNAR overexpression impairs neuronal differentiation by reduced neurite formation in different model systems. At the subcellular level, pTUNAR is a transmembrane protein that localizes in the endoplasmic reticulum and interacts with the calcium transporter SERCA2. pTUNAR overexpression reduces cytoplasmatic calcium, consistent with a possible role of pTUNAR as an activator of SERCA2. Altogether, our results suggest that our newly discovered microprotein has an important role in neural differentiation and neurite formation through the regulation of intracellular calcium. From a more general point of view, our results provide a proof of concept of the role of lncRNAs-encoded microproteins in neural differentiation.

Effects of Hyperthermia on Intracellular Calcium Regulation in Uterine Smooth Muscle Cells

It is known that maternal fever and antenatal infection may lead to abnormal labor. However, the cellular mechanisms by which fever and infection affect labor are poorly understood. Here we investigate the effects of temperature on uterine smooth muscle cell (UtSM) cell calcium regulation as representation of uterine contractility. UtSM were treated with Lipopolysaccharide (LPS), at increasing temperatures (room temperature up to 390C). The aim of our study is to better understand the effects of both temperature and infection on underlying cellular mechanisms of abnormal labor.

Empagliflozin significantly prevents QTc prolongation due to amitriptyline intoxication via intracellular calcium regulation

Abstract Background Empagliflozin is a SGLT-2 inhibitor used in the treatment of Type 2 diabetes and has positive effects on cardiovascular outcomes. Amitriptyline can be used in many clinical indications but leads to cardiotoxicity by causing QT prolongation. Aim Our aim in the present study is to observe the effect of the concomitant use of amitriptyline and empagliflozin together, which have an effect on sodium and calcium balance in myocytes, on QTc by using ECG. Materials and methods Twenty-four male Wistar-Albino rats were randomized into four groups. The control group received only serum physiologic (1ml) via orogastric gavage (OG). The EMPA group received empagliflozin (10 mg/kg) via OG. The AMT group received amitriptyline (100 mg/kg) via OG. The AMT+EMPA group (n: 6) received amitriptyline and empagliflozin at same dose. Under anesthesia; QT and QTC intervals were measured at baseline, first, and second hours. Results The differences in QT and QTc values between the AMT group and control group were observed from the 1nd hour (Table 1, Figure 1). It was detected that the measurements of the control group were within normal limits. In the control group, QT was 77.33±9.02 ms at the basal, 73.50±2.26 ms at the 1st hour, 78.17±6.18 ms at the 2nd hour. QTc calculation was 165.42±18.34±10.5 ms at the basal, 166.63±17.92 msat the 1st hour, 184.65±12.86 ms at the 2nd hour. ECG findings of the EMPA group were within normal limits and similar to the control group (Table 1). The durations of QT interval and QTc calculations were found to be statistically longer in the AMT group than the control group at the 1st and 2nd hour (p≤0.001). Empagliflozin significantly ameliorated AMT-induced QT and QTc prolongation. The durations of QT interval were significantly lower at first (p&amp;lt;0,001) and 2nd hours (p&amp;lt;0.01) in the AMT+EMPA group compared to the AMT group. Moreover, QTc calculation was significantly lower in the AMT+EMP group than the AMT group at 1st and 2nd hour (P&amp;lt;0.01) (Table 1). Electrocardiographic comparisons of all groups for one second within the second hour can be seen in Figure 2. Conclusion In the present study, we have detected that empagliflozin significantly ameliorates amitriptyline induced QT prolongation. This effect is probably due to the opposite effects of these two agents in the intracellular calcium balance. It's known that; toxic dose of amitriptyline increases the amount of Sarcoplasmic Ca and the calcium permeability of Ryanodine channels, decreases SERCA-mediated Ca-reuptake by decreasing the calcium binding capacity of calsequestrin, and these leads QTc prolongation. It has been shown that empagliflozin increases Ca reuptake by causing a significant increase in SERCA activity, and decreases Ca sparks by causing inhibition of Ryanodine activity. With more clinical trials, the routine use of empagliflozin may be suggested to prevent QTc prolongation in the diabetic patients receiving amitriptyline. Funding Acknowledgement Type of funding sources: None. Table 1. QT, QTc durations and HR for groupsFigure 1. ECG traces – a: CON, b: EMPA, c: AMT, d: AMT+EMP