scholarly journals When and why an essential popular mineral—calcium—is an effective antifungal adjuvant against the human pathogen?

2020 ◽  
Author(s):  
Chi Zhang ◽  
Yiran Ren ◽  
Huiyu Gu ◽  
Lu Gao ◽  
Yuanwei Zhang ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
Calcium Homeostasis ◽  
Storage Capacity ◽  
Cytosolic Calcium ◽  
Mineral Nutrient ◽  
Calcium Dependent ◽  
Calcium Storage ◽  
Intracellular Compartments ◽  
Dependent Protein ◽  
Exogenous Calcium

AbstractIn eukaryotes, calcium not only is an essential mineral nutrient but also serves as an intracellular second messenger that is necessary for many physiological processes. Here, we show that exogenous calcium is toxic when fungal cells lack functional calcineurin, a calcium-dependent protein phosphatase that acts as the central regulator of the calcium signaling pathway. By monitoring intracellular calcium, particularly by tracking vacuolar calcium dynamics in living cells through a novel procedure using modified aequorin, we found that calcineurin dysfunction perturbed calcium homeostasis in intracellular compartments including the cytosol, mitochondria, and vacuole, leading to drastic autophagy global organelle fragmentation, and even lastly resulting in cell death upon an extracellular calcium stimulus. Notably, the defective phenotypes seen with calcineurin mutants can be significantly suppressed by alleviating a cytosolic calcium overload or increasing vacuolar calcium storage capacity, suggesting toxicity of exogenous calcium to calcineurin mutants is tightly associated with abnormal cytosolic calcium accumulation and vacuolar calcium storage capacity deficiency. Our findings provide insights into how calcineurin regulates intracellular calcium homeostasis for cell survival and may have important implications for antifungal therapy and clinical drug administration.

scholarly journals Artemisinin Induces Calcium-Dependent Protein Secretion in the Protozoan Parasite Toxoplasma gondii

2007 ◽  
Vol 6 (11) ◽  
pp. 2147-2156 ◽  
Author(s):  
Kisaburo Nagamune ◽  
Wandy L. Beatty ◽  
L. David Sibley
Keyword(s):  
Endoplasmic Reticulum ◽  
Toxoplasma Gondii ◽  
Intracellular Calcium ◽  
Protein Secretion ◽  
Calcium Homeostasis ◽  
Drug Targets ◽  
Calcium Oscillations ◽  
Calcium Atpase ◽  
Host Cells ◽  
Calcium Dependent

ABSTRACT Intracellular calcium controls several crucial cellular events in apicomplexan parasites, including protein secretion, motility, and invasion into and egress from host cells. The plant compound thapsigargin inhibits the sarcoplasmic-endoplasmic reticulum calcium ATPase (SERCA), resulting in elevated calcium and induction of protein secretion in Toxoplasma gondii. Artemisinins are natural products that show potent and selective activity against parasites, making them useful for the treatment of malaria. While the mechanism of action is uncertain, previous studies have suggested that artemisinin may inhibit SERCA, thus disrupting calcium homeostasis. We cloned the single-copy gene encoding SERCA in T. gondii (TgSERCA) and demonstrate that the protein localizes to the endoplasmic reticulum in the parasite. In extracellular parasites, TgSERCA partially relocalized to the apical pole, a highly active site for regulated secretion of micronemes. TgSERCA complemented a calcium ATPase-defective yeast mutant, and this activity was inhibited by either thapsigargin or artemisinin. Treatment of T. gondii with artemisinin triggered calcium-dependent secretion of microneme proteins, similar to the SERCA inhibitor thapsigargin. Artemisinin treatment also altered intracellular calcium in parasites by increasing the periodicity of calcium oscillations and inducing recurrent, strong calcium spikes, as imaged using Fluo-4 labeling. Collectively, these results demonstrate that artemisinin perturbs calcium homeostasis in T. gondii, supporting the idea that Ca2+-ATPases are potential drug targets in parasites.

scholarly journals The Relevance of Amyloid β-Calmodulin Complexation in Neurons and Brain Degeneration in Alzheimer’s Disease

2021 ◽  
Vol 22 (9) ◽  
pp. 4976
Author(s):  
Joana Poejo ◽  
Jairo Salazar ◽  
Ana M. Mata ◽  
Carlos Gutierrez-Merino
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Calcium Homeostasis ◽  
Neuronal Excitability ◽  
Amyloid Β ◽  
Cytosolic Calcium ◽  
Aβ Oligomers ◽  
Calcium Dependent ◽  
Calmodulin Binding ◽  
Brain Degeneration

Intraneuronal amyloid β (Aβ) oligomer accumulation precedes the appearance of amyloid plaques or neurofibrillary tangles and is neurotoxic. In Alzheimer’s disease (AD)-affected brains, intraneuronal Aβ oligomers can derive from Aβ peptide production within the neuron and, also, from vicinal neurons or reactive glial cells. Calcium homeostasis dysregulation and neuronal excitability alterations are widely accepted to play a key role in Aβ neurotoxicity in AD. However, the identification of primary Aβ-target proteins, in which functional impairment initiating cytosolic calcium homeostasis dysregulation and the critical point of no return are still pending issues. The micromolar concentration of calmodulin (CaM) in neurons and its high affinity for neurotoxic Aβ peptides (dissociation constant ≈ 1 nM) highlight a novel function of CaM, i.e., the buffering of free Aβ concentrations in the low nanomolar range. In turn, the concentration of Aβ-CaM complexes within neurons will increase as a function of time after the induction of Aβ production, and free Aβ will rise sharply when accumulated Aβ exceeds all available CaM. Thus, Aβ-CaM complexation could also play a major role in neuronal calcium signaling mediated by calmodulin-binding proteins by Aβ; a point that has been overlooked until now. In this review, we address the implications of Aβ-CaM complexation in the formation of neurotoxic Aβ oligomers, in the alteration of intracellular calcium homeostasis induced by Aβ, and of dysregulation of the calcium-dependent neuronal activity and excitability induced by Aβ.

Toxoplasma gondii induces changes in intracellular calcium in macrophages

Parasitology ◽  
2007 ◽  
Vol 134 (14) ◽  
pp. 1973-1979 ◽  
Author(s):  
K. S. MASEK ◽  
P. ZHU ◽  
B. D. FREEDMAN ◽  
C. A. HUNTER
Keyword(s):  
Toxoplasma Gondii ◽  
Intracellular Calcium ◽  
Host Recognition ◽  
Obligate Intracellular ◽  
Calcium Dependent ◽  
Obligate Intracellular Parasite ◽  
Calcium Storage ◽  
Innate Recognition ◽  
Ratiometric Imaging

SUMMARYToxoplasma gondii is an obligate intracellular parasite that interacts with calcium storage organelles and induces calcium-dependent signalling in macrophages. This study was performed to determine whether Toxoplasma induces changes in intracellular calcium in these cells. Ratiometric imaging of live, Fura-2 loaded macrophages challenged with T. gondii revealed robust elevations in intracellular calcium. These elevations were late in onset, beginning 15–20 min after addition of parasites and occurred in up to 20% of macrophages in an imaging field. Further characterization of these events revealed that they follow from challenge with live T. gondii, but not heat-killed parasites or soluble Toxoplasma antigen (STAg). Parasite-induced calcium elevations derived from extracellular sources, and were independent of host recognition factors MyD88 and CCR5. These findings indicate that Toxoplasma gondii alters calcium homeostasis in macrophages and this activity is independent of known pathways involved in the innate recognition of this organism.

scholarly journals Calcium-Dependent Calpain Proteases Are Implicated in Processing of the Hepatitis C Virus NS5A Protein

2004 ◽  
Vol 78 (21) ◽  
pp. 11865-11878 ◽  
Author(s):  
M. Kalamvoki ◽  
P. Mavromara
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Viral Replication ◽  
Intracellular Calcium ◽  
Calcium Homeostasis ◽  
Mammalian Cells ◽  
Calcium Dependent ◽  
Ns5a Protein ◽  
Genotype 1A ◽  
Immunofluorescence Studies

ABSTRACT The nonstructural 5A (NS5A) protein of the hepatitis C virus (HCV) is a multifunctional phosphoprotein that is implicated in viral replication and HCV-mediated pathogenesis. We report here that the NS5A protein from the HCV genotype 1a is processed into shorter distinct forms when expressed in mammalian cells (Vero, HepG2, HuH-7, and WRL68) infected with an NS5A-expressing HSV-1-based amplicon vector or when transiently transfected with NS5A-expressing plasmids in the absence of exogenous apoptotic stimuli. Inhibitor studies combined with cell-free cleavage assays suggest that calcium-dependent calpain proteases, in addition to caspase-like proteases, are involved in NS5A processing. Interestingly, His-tagging experiments indicated that all the detectable NS5A-cleaved products are N-terminal forms of the protein. Additionally, immunofluorescence studies showed that, despite proteolytic cleavage, the NS5A protein exhibits a cytoplasm-perinuclear localization similar to that of the full-length protein. Thus, our results are consistent with recent data that demonstrated that NS5A is capable of perturbing intracellular calcium homeostasis and suggest that NS5A is both an inducer and a substrate of the calcium-dependent calpain protease(s). This may imply that cleavage of NS5A by calpain(s) could play a role in the modulation of NS5A function.

Effect of verapamil on cytoplasmic distribution of granules and microfilaments in amphibian urinary bladder

1988 ◽  
Vol 46 ◽  
pp. 324-325
Author(s):  
A.J. Mia ◽  
L.X. Oakford ◽  
T. Yorio
Keyword(s):  
Urinary Bladder ◽  
Water Flow ◽  
Morphological Changes ◽  
Granular Cell ◽  
Cytosolic Calcium ◽  
Calcium Storage ◽  
Amphibian Urinary Bladder ◽  
Vesicular Membrane ◽  
High Concentrations ◽  
Cytoskeletal System

The amphibian urinary bladder has been used as a ‘model’ system for studies of the mechanism of action of antidiuretic hormone (ADH) in stimulating transepithelial water flow. The increase in water permeability is accompanied by morphological changes that include the stimulation of apical microvilli, mobilization of microtubules and microfilaments and vesicular membrane fusion events . It has been shown that alterations in the cytosolic calcium concentrations can inhibit ADH transmembrane water flow and induce alterations in the epithelial cell cytomorphology, including the cytoskeletal system . Recently, the subapical granules of the granular cell in the amphibian urinary bladder have been shown to contain high concentrations of calcium, and it was suggested that these cytoplasmic constituents may act as calcium storage sites for intracellular calcium homeostasis. The present study utilizes the calcium antagonist, verapamil, to examine the effect of calcium deprivation on the cytomorphological features of epithelial cells from amphibian urinary bladder, with particular emphasis on subapical granule and microfilament distribution.

Calcium-Dependent Protein Kinases (CDPK) in Abiotic Stress Tolerance

2018 ◽  
Vol 34 (2) ◽  
pp. 259-265 ◽  
Author(s):  
Hemant B Kardile ◽  
◽  
Vikrant ◽  
Nirmal Kant Sharma ◽  
Ankita Sharma ◽  
...  
Keyword(s):  
Abiotic Stress ◽  
Stress Tolerance ◽  
Protein Kinases ◽  
Abiotic Stress Tolerance ◽  
Calcium Dependent ◽  
Dependent Protein ◽  
Calcium Dependent Protein Kinases

scholarly journals A Novel Calcium-Dependent Protein Kinase 1 Inhibitor Potently Prevents Toxoplasma gondii Transmission to Foetuses in Mouse

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4203
Author(s):  
Héloïse Débare ◽  
Nathalie Moiré ◽  
Firmin Baron ◽  
Louis Lantier ◽  
Bruno Héraut ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Toxoplasma Gondii ◽  
Intraperitoneal Administration ◽  
Congenital Toxoplasmosis ◽  
Parasite Burden ◽  
Oral Route ◽  
Dependent Protein Kinase ◽  
Calcium Dependent ◽  
Dependent Protein ◽  
Calcium Dependent Protein Kinase

Treatments currently used to prevent congenital toxoplasmosis are non-specific of Toxoplasma gondii and have grievous side effects. To develop a more specific and less toxic drug, we have designed SP230, an imidazo[1,2-b]pyridazine salt targeting the Toxoplasma gondii calcium-dependent protein kinase 1 (TgCDPK1) and active against acute toxoplasmosis in mice. Efficiency of SP230 to inhibit foetal transmission of the parasite was evaluated in a mouse model of congenital toxoplasmosis. Swiss mice were infected at mid-pregnancy with tachyzoites or cysts of the ME49 strain of T. gondii by intraperitoneal and oral route, respectively, and treated with SP230 at 50 mg/kg for 5 days by the same routes. Parasite burden in organs of dams and in foetuses was measured by quantitative PCR. Intraperitoneal administration of SP230 drastically reduced the number of parasites (more than 97% of reduction) in the brain and lungs of dams, and led to a reduction of 66% of parasite burden in foetuses. Oral administration of SP230 was particularly efficient with 97% of reduction of parasite burdens in foetuses. SP230 did not impact number and weight of offspring in our conditions. This inhibitor of TgCDPK1 is a promising candidate for the development of alternative therapeutics to treat infected pregnant women.

scholarly journals Genetic mapping and transcriptomic characterization of a new fuzzless-tufted cottonseed mutant

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Qian-Hao Zhu ◽  
Warwick Stiller ◽  
Philippe Moncuquet ◽  
Stuart Gordon ◽  
Yuman Yuan ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Agronomic Traits ◽  
Gene Families ◽  
Mutant Phenotype ◽  
Wild Type ◽  
Calcium Dependent ◽  
Dependent Protein ◽  
Flanking Region ◽  
Comparative Transcriptomic Analysis

Abstract Fiber mutants are unique and valuable resources for understanding the genetic and molecular mechanisms controlling initiation and development of cotton fibers that are extremely elongated single epidermal cells protruding from the seed coat of cottonseeds. In this study, we reported a new fuzzless-tufted cotton mutant (Gossypium hirsutum) and showed that fuzzless-tufted near-isogenic lines (NILs) had similar agronomic traits and a higher ginning efficiency compared to their recurrent parents with normal fuzzy seeds. Genetic analysis revealed that the mutant phenotype is determined by a single incomplete dominant locus, designated N5. The mutation was fine mapped to an approximately 250-kb interval containing 33 annotated genes using a combination of bulked segregant sequencing, SNP chip genotyping, and fine mapping. Comparative transcriptomic analysis using 0–6 days post-anthesis (dpa) ovules from NILs segregating for the phenotypes of fuzzless-tufted (mutant) and normal fuzzy cottonseeds (wild-type) uncovered candidate genes responsible for the mutant phenotype. It also revealed that the flanking region of the N5 locus is enriched with differentially expressed genes (DEGs) between the mutant and wild-type. Several of those DEGs are members of the gene families with demonstrated roles in cell initiation and elongation, such as calcium-dependent protein kinase and expansin. The transcriptome landscape of the mutant was significantly reprogrammed in the 6 dpa ovules and, to a less extent, in the 0 dpa ovules, but not in the 2 and 4 dpa ovules. At both 0 and 6 dpa, the reprogrammed mutant transcriptome was mainly associated with cell wall modifications and transmembrane transportation, while transcription factor activity was significantly altered in the 6 dpa mutant ovules. These results imply a similar molecular basis for initiation of lint and fuzz fibers despite certain differences.

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