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The BiP co-chaperone DNAJC3 protects cells during ER stress. In mice, the deficiency of DNAJC3 leads to beta-cell apoptosis and the gradual onset of hyperglycemia. In humans, biallelic DNAJC3 variants cause a multisystem disease, including early-onset diabetes mellitus. Recently, hyperinsulinemic hypoglycemia (HH) has been recognized as part of this syndrome. This report presents a case study of an individual with HH caused by DNAJC3 variants and provides an overview of the metabolic phenotype of individuals with HH and DNAJC3 variants. The study demonstrates that HH may be a primary symptom of DNAJC3 deficiency and can persist until adolescence. Additionally, glycemia and insulin release were analyzed in young DNACJ3 knockout (K.O.) mice, which are equivalent to human infants. In the youngest experimentally accessible age group of 4-week-old mice, the in vivo glycemic phenotype was already dominated by a reduced total insulin secretion capacity. However, on a cellular level, the degree of insulin release of DNAJC3 K.O. islets was higher during periods of increased synthetic activity (high-glucose stimulation). We propose that calcium leakage from the ER into the cytosol, due to disrupted DNAJC3-controlled gating of the Sec61 channel, is the most likely mechanism for HH. This is the first genetic mechanism explaining HH solely by the disruption of intracellular calcium homeostasis. Clinicians should screen for HH in DNAJC3 deficiency and consider DNAJC3 variants in the differential diagnosis of congenital hyperinsulinism. [ABSTRACT FROM AUTHOR]

Cardiovascular complications are major clinical hallmarks of acute and post-acute coronavirus disease 2019 (COVID-19). However, the mechanistic details of SARS-CoV-2 infectivity of endothelial cells remain largely unknown. Here, we demonstrate that the receptor binding domain (RBD) of the SARS-CoV-2 spike (S) protein shares a similarity with the proline-rich binding ena/VASP homology (EVH1) domain and identified the endoplasmic reticulum (ER) resident calreticulin (CALR) as an S-RBD interacting protein. Our biochemical analysis showed that CALR, via its proline-rich (P) domain, interacts with S-RBD and modulates proteostasis of the S protein. Treatment of cells with the proteasomal inhibitor bortezomib increased the expression of the S protein independent of CALR, whereas the lysosomal/autophagy inhibitor bafilomycin 1A, which interferes with the acidification of lysosome, selectively augmented the S protein levels in a CALR-dependent manner. More importantly, the shRNA-mediated knockdown of CALR increased SARS-CoV-2 infection and impaired calcium homeostasis of human endothelial cells. This study provides new insight into the infectivity of SARS-CoV-2, calcium hemostasis, and the role of CALR in the ER-lysosome-dependent proteolysis of the spike protein, which could be associated with cardiovascular complications in COVID-19 patients. [ABSTRACT FROM AUTHOR]

Highly neurotoxic A1-reactive astrocytes have been associated with several human neurodegenerative diseases. Complement protein C3 expression is strongly upregulated in A1 astrocytes, and this protein has been shown to be a specific biomarker of these astrocytes. Several cytokines released in neurodegenerative diseases have been shown to upregulate the production of amyloid β protein precursor (APP) and neurotoxic amyloid β (Aβ) peptides in reactive astrocytes. Also, aberrant Ca2+ signals have been proposed as a hallmark of astrocyte functional remodeling in Alzheimer's disease mouse models. In this work, we induced the generation of A1-like reactive astrocytes after the co-treatment of U251 human astroglioma cells with a cocktail of the cytokines TNF-α, IL1-α and C1q. These A1-like astrocytes show increased production of APP and Aβ peptides compared to untreated U251 cells. Additionally, A1-like astrocytes show a (75 ± 10)% decrease in the Ca2+ stored in the endoplasmic reticulum (ER), (85 ± 10)% attenuation of Ca2+ entry after complete Ca2+ depletion of the ER, and three-fold upregulation of plasma membrane calcium pump expression, with respect to non-treated Control astrocytes. These altered intracellular Ca2+ dynamics allow A1-like astrocytes to efficiently counterbalance the enhanced release of Ca2+ from the ER, preventing a rise in the resting cytosolic Ca2+ concentration. [ABSTRACT FROM AUTHOR]

Endoplasmic reticulum (ER) stress has been demonstrated to play important roles in the pathogenesis of various cardiovascular diseases. The ER stress pathway is therefore a promising therapeutic target in cardiovascular disease. Although Panax notoginseng saponins (PNS) are one of the patent medicines that are traditionally used to treat cardiovascular disorders, their effects on ER stress in cardiac myocytes remain unexploited so far. This study investigates the effects of PNS on ER stress and its associated cell apoptosis along with the related mechanism in cardiac myocytes. PNS compounds were identified via high-performance liquid chromatograph (HPLC) assay. PNS-pretreated H9c2 cells, HL-1 cells, and primary cultured neonatal rat cardiomyocytes were stimulated with thapsigargin (TG) to induce ER stress response and apoptosis. ER stress response was tested by immunofluorescence or immunoblot of the ER protein chaperones—calnexin, binding immunoglobulin protein (BiP) and the C/EBP homologous protein (CHOP). Cell viability was tested by methyl thiazolyl tetrazolium (MTT) assay. Cell apoptosis was detected by immunoblot of Cleaved caspase-3 and flow cytometry analysis of Annexin V/propidium iodide (PI) staining. Cytosolic, mitochondrial, and ER calcium dynamics were investigated by calcium imaging. Moreover, a ryanodine receptor type-2 (RyR2) overexpression stable cell line was generated to verify the mechanism of RyR2 involved in PNS in the inhibition of ER stress and cell apoptosis. We demonstrate here that PNS protected cardiac myocytes from ER stress response and associated cell death in a concentration-dependent manner. Importantly, PNS reduced the elevation of cytosolic calcium, mitochondria calcium, as well as ER calcium in response to either TG or histamine treatment. PNS protection in ER stress was regulated by RyR2 expression. In summary, PNS protection against TG-induced ER stress response and its associated cell apoptosis in cardiac myocytes is calcium dependent. Through the regulation of ER calcium release mediated by RyR2, a novel mechanism for PNS in the prevention of cardiovascular diseases is thereby identified.

(1) Background: Members of the TRPC3/TRPC6/TRPC7 subfamily of canonical transient receptor potential (TRP) channels share an amino acid similarity of more than 80% and can form heteromeric channel complexes. They are directly gated by diacylglycerols in a protein kinase C-independent manner. To assess TRPC3 channel functions without concomitant protein kinase C activation, direct activators are highly desirable. (2) Methods: By screening 2000 bioactive compounds in a Ca2+ influx assay, we identified artemisinin as a TRPC3 activator. Validation and characterization of the hit was performed by applying fluorometric Ca2+ influx assays and electrophysiological patch-clamp experiments in heterologously or endogenously TRPC3-expressing cells. (3) Results: Artemisinin elicited Ca2+ entry through TRPC3 or heteromeric TRPC3:TRPC6 channels, but did not or only weakly activated TRPC6 and TRPC7. Electrophysiological recordings confirmed the reversible and repeatable TRPC3 activation by artemisinin that was inhibited by established TRPC3 channel blockers. Rectification properties and reversal potentials were similar to those observed after stimulation with a diacylglycerol mimic, indicating that artemisinin induces a similar active state as the physiological activator. In rat pheochromocytoma PC12 cells that endogenously express TRPC3, artemisinin induced a Ca2+ influx and TRPC3-like currents. (4) Conclusions: Our findings identify artemisinin as a new biologically active entity to activate recombinant or native TRPC3-bearing channel complexes in a membrane-confined fashion. [ABSTRACT FROM AUTHOR]

Rotenone is a neurotoxin that is an active component of many pesticides which has been shown to induce Parkinsonism in animal models. We show that the cytotoxicity of exposure to nanomolar concentrations of rotenone in cultures of mature cerebellar granule neurons (CGN) in serum-free medium is not due to phagocytosis by glial contamination. A concentration as low as 5.65 ± 0.51 nM of rotenone was enough to trigger 50% cell death of mature CGN in culture after 12 h. The addition of serum proteins to the culture medium attenuated rotenone neurotoxicity, and this can account at least in part for the requirement of higher rotenone concentrations to elicit neuronal cytotoxicity reported in previous works. Creatine partial protection against CGN death promoted by 5 nM rotenone correlated with creatine protection against rotenone-induced mitochondrial depolarization and oxidative stress. Furthermore, creatine largely attenuated the early dysregulation of cytosolic Ca2+ concentration after acute rotenone treatment. Noteworthy, our results also revealed that the sustained alteration of Ca2+ homeostasis induced by rotenone takes place at the onset of the enhancement of intracellular oxidative stress and before mitochondrial depolarization, pointing out that cytosolic Ca2+ dysregulation is a very early event in the rotenone toxicity to CGN. [ABSTRACT FROM AUTHOR]

Objectives Transient receptor potential canonical type 3 ( TRPC3) channels are activated in B lymphoblast cell lines from patients with bipolar disorder ( BD), and its expression is reduced by chronic lithium treatment, implicating TRPC3 in the intracellular calcium (Ca2+) dyshomeostasis of BD. Thrombin, via a protease-activated receptor, moderates Ca2+ signaling and TRPC3 in astrocytes, and also cell proliferation. We examined whether lithium pretreatment attenuates thrombin-stimulated TRPC3 expression and function in astrocytes, and levels of the calcium-binding peptide, S100B, which is expressed mainly in these cells. Methods Human astroglioma, U-87 MG, cells were pretreated with 1 mmol L−1 LiCl for 1 day (acute), 3 days (subacute), and 7 days (chronic). To examine the role of TRPC3, genetically stable knockdown TRPC3 cells ( TRPC3Low cells) were constructed using U-87 MG cells. Thrombin (2.0 U/mL)-stimulated Ca2+ mobilization was measured by ratiometric fluorimetry. Changes in TRPC3 and S100B expression levels were determined by quantitative reverse transcription-polymerase chain reaction and immunoblotting, respectively. Cell proliferation was also measured using the WST-8 assay. Results In this cell model, thrombin-stimulated Ca2+ mobilization, and both TRPC3 and S100B expression were suppressed by chronic LiCl pretreatment and the knockdown of TRPC3. Additionally, cell proliferation was attenuated in TRPC3Low cells, compared with the negative control vector-transfected cell. Conclusions The reduced Ca2+ mobilization and S100B expression levels following chronic LiCl pretreatment and in TRPC3Low cells support the notion that TRPC3 modulates S100B expression and is the target of the LiCl effect. Downregulation of TRPC3 may be an important mechanism by which lithium ameliorates pathophysiological intracellular Ca2+ disturbances as observed in BD, accounting, in part, for its mood-stabilizing effects. [ABSTRACT FROM AUTHOR]

Objectives. Intracellular calcium (Ca2+) dyshomeostasis (ICDH) has been implicated in bipolar disorder (BD) pathophysiology. We previously showed that SNP rs956572 in the B-cell CLL/lymphoma 2 (Bcl-2) gene associates with elevated B lymphoblast (BLCL) intracellular Ca2+concentrations ([Ca2+]B) differentially in BD-I. Genome-wide association studies strongly support the association between BD and the SNP rs1006737, located within the L-type voltage-dependent Ca2+channel α1C subunit gene (CACNA1C). Here we investigated whether thisCACNA1Cvariant also associates with ICDH and interacts with SNP rs956572 on [Ca2+]Bin BD-I.Methods. CACNA1CSNP rs1006737 was genotyped in 150 BD-I, 65 BD-II, 30 major depressive disorder patients, and 70 healthy subjects with available BLCL [Ca2+]BandBcl-2SNP rs956572 genotype measures.Results. SNP rs1006737 was significantly associated with BD-I. The [Ca2+]Bwas significantly higher in BD-I rs1006737 A compared with healthy A allele carriers and also in healthy GG compared with A allele carriers. There was no significant interaction between SNP rs1006737 and SNP rs956572 on [Ca2+]B.Conclusions. Our study further supports the association of SNP rs1006737 with BD-I and suggests thatCACNA1CSNP rs1006737 andBcl-2SNP rs956572, or specific causal variants in LD with these proxies, act independently to increase risk and ICDH in BD-I. [ABSTRACT FROM AUTHOR]

Calcium homeostasis of osteoblasts (OBs) has an important role in the physiology and pathology of bone tissue. In order to study the mechanisms of intracellular calcium homeostasis, MC3T3-E1 cells and Sprague-Dawley rats were treated with different concentrations of fluoride. Then, we examined intracellular-free calcium ion ([Ca]i) in MC3T3-E1 cells as well as mRNA and protein levels of Cav1.2, the main subunit of L-type voltage-dependent calcium channels (VDCCs), Na/Ca exchange carriers (NCS), and plasma membrane Ca-ATPase (PMCA), inositol 1,4,5-trisphosphate receptor (IP3R) channels, sarco/endoplasmic reticulum calcium ATPase 2b (SERCA2b)/ATP2A2 in vitro, and rat bone tissues in vivo. Our results showed that [Ca]i of fluoride-treated OBs increased in a concentration-dependent manner with an increase in the concentration of fluoride. We also found that the low dose of fluoride led to high expression levels of Cav1.2, NCS-1, and PMCA and low expression levels of IP3R and SERCA2b/ATP2A2, while the high dose of fluoride induced an increase in SERCA2b/ATP2A2 levels and decrease in Cav1.2, PMCA, NCS-1, and IP3R levels. These results demonstrate that calcium channels and calcium pumps of plasma and endoplasmic reticulum (ER) membranes keep intracellular calcium homeostasis by regulating Cav1.2, NCS-1, PMCA, IP3R, and SERCA2b/ATP2A2 expression. [ABSTRACT FROM AUTHOR]

Little is known about metabolic syndrome (MetS)-associated cardiomyopathy, especially in relation to the role and contribution of beta-adrenoceptor (β-AR) subtypes. Therefore, we examined the roles of β-AR subtypes in the cardiac function of rats with MetS (MetS group) and compared it with that of rats with streptozotocin (STZ)-induced diabetes (STZ group). Compared with the normal control rats, the protein levels of cardiac β1- and β2-AR in the MetS group were significantly decreased and with no changes in their mRNA levels, whereas the protein levels of β3-AR were similar to those of the controls. However, as shown previously, the protein levels of cardiac β1- and β2-AR in the STZ group were decreased, whereas the β3-AR levels were significantly increased by comparison with the controls. Additionally, the mRNA levels of β3- and β3-AR were increased, but β1-AR mRNA was decreased in the STZ group. Furthermore, left ventricular developed pressure responses to β3-AR agonist BRL37344 were increased in the STZ group but not in the MetS group, whereas for both groups, the responses to noradrenaline were not different from those of the controls. However, the response to stimulation with high concentrations of fenoterol was depressed in the MetS group, compared with the controls, but not in the STZ group. Consequently, our data suggest that the contribution of the β-AR system to cardiac dysfunction in the rats with MetS is not the same as that in the STZ group, although they have similar cardiac dysfunction with similar ultrastructural changes to the myocardium. [ABSTRACT FROM AUTHOR]

Abstract: TRPV3, a thermosensitive cation channel, is predominantly expressed in keratinocytes. It contributes to physiological processes such as thermosensation, nociception, and skin development. TRPV3 is polymodally regulated by chemical agonists, innocuous heat, intracellular acidification or by membrane depolarization. By manipulating the content of plasma membrane cholesterol, a key modulator of the physicochemical properties of biological membranes, we here addressed the question, how the lipid environment influences TRPV3. Cholesterol supplementation robustly potentiated TRPV3 channel activity by sensitising it to lower concentrations of chemical activators. In addition, the thermal activation of TRPV3 is significantly shifted to lower temperatures in cholesterol-enriched cells. The sensitising effect of cholesterol was not caused by an increased plasma membrane targeting of the channel. In HaCaT keratinocytes, which natively express TRPV3, a cholesterol-mediated sensitisation of TRPV3-like responses was reproduced. The cholesterol-dependent modulation of TRPV3 activity may provide a molecular mechanism to interpret its involvement in keratinocyte differentiation. [Copyright &y& Elsevier]

Aims Zinc exists in biological systems as bound and histochemically reactive free Zn2+. It is an essential structural constituent of many proteins, including enzymes from cellular signalling pathways, in which it functions as a signalling molecule. In cardiomyocytes at rest, Zn2+ concentration is in the nanomolar range. Very little is known about precise mechanisms controlling the intracellular distribution of Zn2+ and its variations during cardiac function. Methods and results Live-cell detection of intracellular Zn2+ has become feasible through the recent development of Zn2+-sensitive and –selective fluorophores able to distinguish Zn2+ from Ca2+. Here, in freshly isolated rat cardiomyocytes, we investigated the rapid changes in Zn2+ homeostasis using the Zn2+-specific fluorescent dye, FluoZin-3, in comparison to Ca2+-dependent fluo-3 fluorescence. Zn2+ sparks and Zn2+ transients, in quiescent and electrically stimulated cardiomyocytes, respectively, were visualized in a similar manner to known rapid Ca2+ changes. Both Zn2+ sparks and Zn2+ transients required Ca2+ entry. Inhibiting the sarcoplasmic reticulum Ca2+ release or increasing the Ca2+ load in a low-Na+ solution suppressed or increased Zn2+ movements, respectively. Mitochondrial inhibitors slightly reduced both Zn2+ sparks and Zn2+ transients. Oxidation by H2O2 facilitated and acidic pH inhibited the Ca2+-dependent Zn2+ release. Conclusion It is proposed that Zn2+ release during the cardiac cycle results mostly from intracellular free Ca2+ increase, triggering production of reactive oxygen species that induce changes in metal-binding properties of metallothioneins and other redox-active proteins, aside from ionic exchange on these proteins. [ABSTRACT FROM AUTHOR]

Uemura T, Green M, Corson TW, Perova T, Li PP, Warsh JJ. Bcl-2 SNP rs956572 associates with disrupted intracellular calcium homeostasis in bipolar I disorder. Bipolar Disord 2011: 13: 41-51. © 2011 The Authors. Journal compilation © 2011 John Wiley & Sons A/S. Disrupted intracellular calcium (Ca) homeostasis (ICH) related to mitochondrial and/or endoplasmic reticulum (ER) dysfunction has been implicated in bipolar disorder (BD). The anti-apoptotic protein B-cell CLL/lymphoma 2 (Bcl-2), encoded in a putative BD susceptibility locus, modulates ER-Ca dynamics. Recently, an intronic single-nucleotide polymorphism (SNP) in the Bcl-2 gene, rs956572, was suggested as a functionally active SNP that influences its messenger RNA (mRNA) and protein level as well as human gray matter volume. We sought to evaluate the impact of this variant on ICH in BD. Basal intracellular Ca concentrations ([Ca]) and rs956572 genotypes were determined in B lymphoblast cell lines (BLCLs) from bipolar I disorder (BD-I) (n = 150), bipolar II disorder (BD-II) (n = 65), and major depressive disorder (n = 30) patients, and from healthy subjects (n = 70). Bcl-2 mRNA and protein levels were determined by quantitative reverse transcriptase polymerase chain reaction and immunoblotting, respectively. Functional interactions of rs956572 with ICH were assessed by thapsigargin- and lysophosphatidic acid (LPA)-stimulated Ca responses. Although rs956572 variation was not significantly associated with BD, BD-I, or BD-II, BLCL [Ca] was significantly higher in BD-I G/G patients compared with other genotypes and with healthy subjects. Bcl-2 mRNA and protein levels were lowest in BD-I G/G patients. Compared with A carriers, BD-I patients with G/G variants showed a modest enhancing effect on thapsigargin- and LPA-stimulated Ca responses. These findings support the notion that genetic variation in Bcl-2 affecting its expression impacts ICH in BD. Moreover, we show here for the first time that this interactive effect is diagnostically specific to BD-I. [ABSTRACT FROM AUTHOR]

The adenine nucleotides ADP and ATP are probably the most important endogenous inhibitors of the mitochondrial permeability transition (MPT). We studied the inhibitory effects of adenine nucleotides on brain MPT by measuring mitochondrial swelling and Ca and cytochrome c release. We observed that in the presence of either ADP or ATP, at 250 μM, brain mitochondria accumulated more than 1 μmol Ca × mg protein. ADP or ATP also prevented Ca-induced mitochondrial swelling and cytochrome c release. Interestingly, ATP lost most of its inhibitory effects on MPT when the experiments were carried out in the presence of ATP-regenerating systems. These results indicate that MPT inhibition observed in the presence of added ATP could be mainly due to hydrolysis of ATP to ADP. From mitochondrial swelling measurements, half-maximal inhibitory values ( K) of 4.5 and 98 μM were obtained for ADP and ATP, respectively. In addition, a delayed mitochondrial swelling sensitive to higher ADP concentrations was observed. Mitochondrial anoxia/reoxygenation did not interfere with the inhibitory effect of ADP on Ca-induced MPT, but oxidative phosphorylation markedly decreased this effect. We conclude that ADP is a potent inhibitor of brain MPT whereas ATP is a weaker inhibitor of this phenomenon. Our results suggest that ADP can have an important protective role against MPT-mediated tissue damage under conditions of brain ischemia and hypoglycemia. [ABSTRACT FROM AUTHOR]

Objective: Recent case-control studies implicate the transient receptor potential melastatin 2 ( TRPM2) channel in conferring risk for bipolar disorder (BD), though the risk variants differed. As confounding effects of population structure could not be unequivocally ruled out as the basis for the discordance, we tested the association of TRPM2 with BD in a family design, which is immune to population stratification, for those TRPM2 single nucleotide polymorphisms (SNPs) previously reported as associated with BD. Methods: The exon 11 SNP (rs1556314) and four informative intronic SNPs (rs1785437, rs1618355, rs933151, and rs749909) were genotyped in 300 BD families by TaqMan allelic discrimination and results were analyzed using χ2 test, transmission disequilibrium test, and pedigree-based association. SNP rs1556314 was also genotyped in our case-control sample set comprised of 184 BD and 195 healthy Caucasian subjects. Results: The SNP rs1556314 in exon 11 was significantly associated with bipolar disorder type I (BD-I) (p = 0.011, ppermutation = 0.015) in the case-control dataset and in the family design (p = 0.018, ppermutation = 0.052, TDTPHASE). Interestingly, the C-T-A haplotype of SNPs rs1618355, rs933151, and rs749909 was significantly associated with early age at onset in BD-I families. Conclusion: Significant association of TRPM2 genetic variants with BD in case-control and family datasets further supports a role for TRPM2 in the pathogenesis of this disorder. Overtransmission of the G allele of rs1556314 at exon 11 of TRPM2 in BD-I but not bipolar disorder type II (BD-II) further supports different genetic contributions to the pathogenesis of these bipolar phenotypes. [ABSTRACT FROM AUTHOR]

CD38 is a type-II transmembrane glycoprotein occurring in several hematopoietic and mature blood cells as well as in other cell types, including neurons. Although classified as an orphan receptor, CD38 is also a bifunctional ectoenzyme that catalyzes both the conversion of NAD+ to nicotinamide and cyclic ADP-ribose (cADPR), via an ADP-ribosyl cyclase reaction, and also the hydrolysis of cADPR to ADP-ribose (hydrolase). Major unresolved questions concern the correlation between receptor and catalytic properties of CD38, and also the apparent contradiction between ectocellular generation and intracellular Ca2+-mobilizing activity of cADPR. Results are presented that provide some explanations to this topological paradox in two different cell types. In cultured rat cerebellar granule neurons, extracellular cADPR (either generated by CD38 or directly added) elicited an enhanced intracellular Ca2+ response to KCl-induced depolarization, a process that can be qualified as a Ca2+-induced Ca2+ release (CICR) mechanism. On the other hand, in the CD38+ human Namalwa B lymphoid cells, NAD+ (and thiol compounds as well) induced a two-step process of self-aggregation followed by endocytosis of CD38, which resulted in a shift of cADPR metabolism from the cell surface to the cytosol. Both distinctive types of cellular responses to extracellular NAD+ seem to be suitable to elicit changes in the intracellular Ca2+ homeostasis. [ABSTRACT FROM AUTHOR]

Nucleobindin-1 is an EF-hand calcium-binding protein with a distinctive profile, predominantly localized to the Golgi in insect and wide-ranging vertebrate cell types, alike. Its putative involvements in intracellular calcium (Ca 2+ ) homeostasis have never been phenotypically characterized in any model organism. We have analyzed an adult-viable mutant that completely disrupts the G protein α-subunit binding and activating (GBA) motif of Drosophila Nucleobindin-1 (dmNUCB1). Such disruption does not manifest any obvious fitness-related, morphological/developmental, or behavioral abnormalities. A single copy of this mutation or the knockdown of dmnucb1 in restricted sets of cells variously rescues pleiotropic mutant phenotypes arising from impaired inositol 1,4,5-trisphosphate receptor (IP3R) activity (in turn depleting cytoplasmic Ca 2+ levels across diverse tissue types). Additionally, altered dmNUCB1 expression or function considerably reverses lifespan and mobility improvements effected by IP3R mutants, in a Drosophila model of amyotrophic lateral sclerosis. Homology modeling-based analyses further predict a high degree of conformational conservation in Drosophila , of biochemically validated structural determinants in the GBA motif that specify in vertebrates, the unconventional Ca 2+ -regulated interaction of NUCB1 with Gαi subunits. The broad implications of our findings are hypothetically discussed, regarding potential roles for NUCB1 in GBA-mediated, Golgi-associated Ca 2+ signaling, in health and disease.