Calcium Uptake Research Articles

NR1D1 controls skeletal muscle calcium homeostasis through myoregulin repression.

The sarcoplasmic reticulum (SR) plays an important role in calcium homeostasis. SR calcium mishandling is described in pathological conditions, such as myopathies. Here, we investigated whether the nuclear receptor subfamily 1 group D member (NR1D1, also called REV-ERBα) regulates skeletal muscle SR calcium homeostasis. Our data demonstrate that NR1D1 deficiency in mice impaired sarco/endoplasmic reticulum calcium ATPase–dependent (SERCA-dependent) SR calcium uptake. NR1D1 acts on calcium homeostasis by repressing the SERCA inhibitor myoregulin through direct binding to its promoter. Restoration of myoregulin counteracted the effects of NR1D1 overexpression on SR calcium content. Interestingly, myoblasts from patients with Duchenne muscular dystrophy displayed lower NR1D1 expression, whereas pharmacological NR1D1 activation ameliorated SR calcium homeostasis and improved muscle structure and function in dystrophic mdx/Utr+/– mice. Our findings demonstrate that NR1D1 regulates muscle SR calcium homeostasis, pointing to its therapeutic potential for mitigating myopathy.

Piezo1 stimulates mitochondrial function via cAMP signaling.

Mechanical signals stimulate mitochondrial function but the molecular mechanisms are not clear. Here, we show that the mechanically sensitive ion channel Piezo1 plays a critical role in mitochondrial adaptation to mechanical stimulation. The activation of Piezo1 induced mitochondrial calcium uptake and oxidative phosphorylation (OXPHOS). In contrast, loss of Piezo1 reduced the mitochondrial oxygen consumption rate (OCR) and adenosine triphosphate (ATP) production in calvarial cells and these changes were associated with increased expression of the phosphodiesterases Pde4a and lower cyclic AMP (cAMP) levels. In addition, Piezo1 increased cAMP production and the activation of a cAMP-responsive transcriptional reporter. Consistent with this, cAMP was sufficient to increase mitochondrial OCR and the inhibition of phosphodiesterases augmented the increase in OCR induced by Piezo1. Moreover, the inhibition of cAMP production or activity of protein kinase A, a kinase activated by cAMP, prevented the increase in OCR induced by Piezo1. These results demonstrate that cAMP signaling contributes to the increase in mitochondrial OXPHOS induced by activation of Piezo1.

Morphological and molecular insights of calcium in peanut pod development

Calcium is an important secondary macronutrient after nitrogen, phosphorus and potassium for the proper development of the plant. It is typically important for the formation of cell walls, cell members and accumulates in the plant cells. Calcium deficiency occurs rarely in nature but excess calcium limits plant communities on calcareous soils. In peanut, calcium uptake by plants from the soil will remain in the plant tissues and will not be transported back to developing pods where calcium requirement is more. The geotropic growth of peanut pods had capacity of absorption of calcium from the soil for filling and development of pods. Application of calcium before the pod development stage in peanut is required to have sufficient calcium available to the pods which could help an increase in yield up to 20–30%. The calcium-related genes in different metabolic pathways help in the regulation of embryo abortion in peanut and also a well-documented role in mediating plant responses to abiotic and biotic stimuli. This article provides a summary of the role of calcium, its management details, the transport of calcium into plants through the soil and overview of calcium genes in peanut pod development.

Update on platelet procoagulant mechanisms in health and in bleeding disorders.

Platelet procoagulant mechanisms are emerging to be complex and important to achieving haemostasis. The mechanisms include the release of procoagulant molecules from platelet storage granules, and strong agonist-induced expression of procoagulant phospholipids on the outer platelet membrane for tenase and prothrombinase assembly. The release of dense granule polyphosphate is important to platelet procoagulant function as it promotes the activation of factors XII, XI and V, inhibits tissue factor pathway inhibitor and fibrinolysis, and strengthens fibrin clots. Platelet procoagulant function also involves the release of partially activated factor V from platelets. Scott syndrome has provided important insights on the mechanisms that regulate procoagulant phospholipids expression on the external platelet membrane, which require strong agonist stimulation that increase cystolic calcium levels, mitochondrial calcium uptake, the loss of flippase function and activation of the transmembrane scramblase protein anoctamin 6. There have been advances in the methods used to directly and indirectly assess platelet procoagulant function in health and disease. Assessments of thrombin generation with platelet rich plasma samples has provided new insights on how platelet procoagulant function is altered in inherited platelet disorders, and how platelets influence the bleeding phenotype of a number of severe coagulation factor deficiencies. Several therapies, including desmopressin and recombinant factor VIIa, improve thrombin generation by platelets. There is growing interest in targeting platelet procoagulant function for therapeutic benefit. This review highlights recent advances in our understanding of platelet-dependent procoagulant mechanisms in health and in bleeding disorders.

Impact of Calcium Influx on Endoplasmic Reticulum in Excitotoxic Neurons: Role of Chemical Chaperone 4-PBA.

Excessive activation of α-amino-3-hydroxy-5-methyl-4-isoxazole propoinic acid (AMPA) receptors instigates excitotoxicity via enhanced calcium influx in the neurons thus inciting deleterious consequences. Additionally, Endoplasmic Reticulum (ER) is pivotal in maintaining the intracellular calcium balance. Considering this, studying the aftermath of enhanced calcium uptake by neurons and its effect on ER environment can assist in delineating the pathophysiological events incurred by excitotoxicty. The current study was premeditated to decipher the role of ER pertaining to calcium homeostasis in AMPA-induced excitotoxicity. The findings showed, increased intracellular calcium levels (measured by flowcytometry and spectroflourimeter using Fura 2AM) in AMPA excitotoxic animals (male Sprague dawely rats) (intra-hippocampal injection of 10mM AMPA). Further, ER resident proteins like calnexin, PDI and ERp72 were found to be upregulated, which further modulated the functioning of ER membrane calcium channels viz. IP3R, RyR, and SERCA pump. Altered calcium homeostasis further led to ER stress and deranged the protein folding capacity of ER post AMPA toxicity, which was ascertained by unfolded protein response (UPR) pathway markers such as IRE1α, eIF2α, and ATF6α. Chemical chaperone, 4-phenybutric acid (4-PBA), ameliorated the protein folding capacity and subsequent UPR markers. In addition, modulation of calcium channels and calcium regulating machinery of ER post 4-PBA administration restored the calcium homeostasis. Therefore the study reinforces the significance of ER stress, a debilitating outcome of impaired calcium homeostasis, under AMPA-induced excitotoxicity. Also, employing chaperone-based therapeutic approach to curb ER stress can restore the calcium imbalance in the neuropathological diseases.

Mitochondrial calcium uptake capacity is lower than calcium retention capacity in the presence and absence of cyclosporin A

Mitochondrial calcium uptake capacity is lower than calcium retention capacity in the presence and absence of cyclosporin A

Palmitoylation regulates cellular distribution of and transmembrane Ca flux through TrpM7

The bifunctional cation channel/kinase TrpM7 is ubiquitously expressed and regulates embryonic development and pathogenesis of several common diseases. The TrpM7 integral membrane ion channel domain regulates transmembrane movement of divalent cations, and its kinase domain controls gene expression via histone phosphorylation. Mechanisms regulating TrpM7 are elusive. It exists in two populations in the cell: at the cell surface where it controls divalent cation fluxes, and in intracellular vesicles where it controls zinc uptake and release. Here we report that TrpM7 is palmitoylated at a cluster of cysteines at the C terminal end of its Trp domain. Palmitoylation controls the exit of TrpM7 from the endoplasmic reticulum and the distribution of TrpM7 between cell surface and intracellular pools. Using the Retention Using Selective Hooks (RUSH) system, we demonstrate that palmitoylated TrpM7 traffics from the Golgi to the surface membrane whereas non-palmitoylated TrpM7 is sequestered in intracellular vesicles. We identify the Golgi-resident enzyme zDHHC17 and surface membrane-resident enzyme zDHHC5 as responsible for palmitoylating TrpM7 and find that TrpM7-mediated transmembrane calcium uptake is significantly reduced when TrpM7 is not palmitoylated. The closely related channel/kinase TrpM6 is also palmitoylated on the C terminal side of its Trp domain. Our findings demonstrate that palmitoylation controls ion channel activity of TrpM7 and that TrpM7 trafficking is dependant on its palmitoylation. We define a new mechanism for post translational modification and regulation of TrpM7 and other Trps.

The mitochondrial calcium uniporter engages UCP1 to form a thermoporter that promotes thermogenesis

Uncoupling protein 1 (UCP1)-mediated adaptive thermogenesis protects mammals against hypothermia and metabolic dysregulation. Whether and how mitochondrial calcium regulates this process remains unclear. Here, we show that mitochondrial calcium uniporter (MCU) recruits UCP1 through essential MCU regulator (EMRE) to form an MCU-EMRE-UCP1 complex upon adrenergic stimulation. This complex formation increases mitochondrial calcium uptake to accelerate the tricarboxylic acid cycle and supply more protons that promote uncoupled respiration, functioning as a thermogenic uniporter. Mitochondrial calcium uptake 1 (MICU1) negatively regulates thermogenesis probably through inhibiting thermogenic uniporter formation. Accordingly, the deletion of Mcu or Emre in brown adipocytes markedly impairs thermogenesis and exacerbates obesity and metabolic dysfunction. Remarkably, the enhanced assembly of the thermogenic uniporter via Micu1 knockout or expressing linked EMRE-UCP1 results in opposite phenotypes. Thus, we have uncovered a "thermoporter" that provides a driving force for the UCP1 operation in thermogenesis, which could be leveraged to combat obesity and associated metabolic disorders.

Abstract P3053: Mitochondrial Calcium Accumulation Drives The Progression Of Non-ischemic Heart Failure: Integrated Lessons From Genetic Mouse Models

Acute mitochondrial calcium ( m Ca 2+ ) uptake stimulates bioenergetics to meet increased ATP demand, but when excessive predisposes to necrotic cell death. A major unresolved controversy is whether chronic alterations in cardiomyocyte m Ca 2+ homeostasis contribute to maladaptive remodeling and contractile dysfunction in non-ischemic heart disease. We hypothesized that cardiomyocyte m Ca 2+ accumulation drives cardiac maladaptation in response to stressors that chronically increase workload and cytosolic Ca 2+ cycling. We subjected mice with adult, cardiomyocyte-specific manipulation of m Ca 2+ uptake through the mitochondrial calcium uniporter ( Mcu deletion, Mcu -cKO; MCU overexpression, MCU-Tg) or m Ca 2+ efflux through the mitochondrial sodium-calcium exchanger, NCLX (NCLX overexpression, NCLX-OE), to chronic pressure or neurohormonal overload. Fractional shortening failed to increase in Mcu -cKO mice over the first days of isoproterenol (Iso) infusion. Mortality was increased in Mcu -cKO mice over this period, and this effect was recapitulated in NCLX-OE mice infused with angiotensin II + phenylephrine (PE), although contractility did not decline in either case. Hypertrophic responses to chronic stress were attenuated in NCLX-OE but not Mcu -cKO hearts, and adenoviral NCLX expression limited mitochondrial metabolism, protein synthesis, and cell growth in neonatal rat cardiomyocytes treated with PE. These data indicate that m Ca 2+ accumulation is required for cardiac hypertrophy, but MCU is not. MCU-Tg hearts decompensated towards failure with 1-2 weeks of Iso. Although these hearts exhibited increased cardiomyocyte necrosis, deletion of the mPTP regulator cyclophilin D failed to rescue contractility, suggesting that m Ca 2+ overload causes cardiac failure, even independent of permeability transition. Fitting with this view, NCLX-OE attenuated the decline in contractile function that occurred with 12-week pressure overload. We conclude that despite initial adaptive effects, sustained m Ca 2+ elevation drives the progression of non-ischemic heart disease triggered by a chronic increase in cardiac workload. Our findings raise concern over proposed therapeutic strategies aiming to augment m Ca 2+ accumulation in heart failure.

Abstract OEC102: Unbiased Discovery Of Allograft Inflammatory Factor 1 As A New And Critical Immunometabolic Regulatory Node During Cardiac Injury

Introduction: Myocardial infarction (MI) mobilizes macrophages, which are the central protagonists of tissue repair in the infarcted heart. While macrophages are necessary for repair after MI, they can also contribute to adverse remodeling and progression to heart failure. We sought to identify novel mediators of maladaptive macrophage responses by performing single cell RNA sequencing of a patient with ischemic cardiomyopathy. This led to the unbiased identification of Allograft inflammatory factor 1 ( AIF1 ) as the most significant differentially expressed gene in macrophages compared to other cardiac cells during human heart failure. Hypothesis: Since AIF1 was specifically expressed in macrophages during ischemic heart failure, we next tested the hypothesis that AIF1 promoted maladaptive macrophage responses after MI. Methods and Results: Using autopsy samples from human acute MI patients or a murine model of permanent occlusion MI, we found that AIF1 was increased in macrophages, but not neutrophils or monocytes, after MI. To test the functional significance of AIF1 expression in macrophages after MI, we generated bone marrow chimeric mice where Aif1 -deficiency was restricted to only cells of hematopoietic origin. Despite comparable levels of surgically induced injury, loss of Aif1 was associated with increased proreparative macrophages, smaller infarct sizes, and preservation of cardiac function compared to wild-type controls. Therapeutic targeting of Aif1 with anti-sense oligonucleotides also conferred cardioprotective responses after MI. Mechanistically, AIF1 promoted actin polymerization in bone marrow-derived macrophages after TLR4 stimulation leading to increased glycolytic metabolism and inflammatory IL-6 and TNF-α production. AIF1 also suppressed calcium uptake in the mitochondria to limit mitochondrial metabolism and anti-inflammatory IL-10 production. Conclusion: These data newly reveal a proinflammatory role for AIF1 in the infarcted heart through inflammatory glycolytic reprogramming of macrophages, which required both calcium mobilization and actin polymerization. Targeted knockdown of AIF1 led to cardioprotection supporting further exploration of macrophage AIF1 as a therapeutic target after MI.

Genomic insights into genetic diploidization in the homosporous fern Adiantum nelumboides.

Whole-genome duplication has been recognized as a major process in speciation of land plants, especially in ferns. Whereas genome downsizing contributes greatly to the post-genome shock responses of polyploid flowering plants, diploidization of polyploid ferns diverges by maintaining most of the duplicated DNA and is thus expected to be dominated by genic processes. As a consequence, fern genomes provide excellent opportunities to study ecological speciation enforced by expansion of protein families via polyploidy. To test the key predictions of this hypothesis, we reported the de novo genome sequence of Adiantum nelumboides, a tetraploid homosporous fern. The obtained draft genome had a size of 6.27 Gb assembled into 11,767 scaffolds with the contig N50 of 1.37 Mb. Repetitive DNA sequences contributed with about 81.7%, a remarkably high proportion of the genome. With 69,568, the number of predicted protein-coding genes exceeded those reported in most other land plant genomes. Intragenomic synteny analyses recovered 443 blocks with the average block size of 1.29 Mb and the average gene content of 16 genes. The results are consistent with the hypothesis of high ancestral chromosome number, lack of substantial genome downsizing, and dominance of genic diploidization. As expected in the calciphilous plants, a notable number of detected genes were involved in calcium uptake and transport. In summary, the genome sequence of a tetraploid homosporous fern not only provides access to a genomic resource of a derived fern, but also supports the hypothesis of maintenance of high chromosome numbers and duplicated DNA in young polyploid ferns.

Effects of MICU1-Mediated Mitochondrial Calcium Uptake on Energy Metabolism and Quality of Vitrified-Thawed Mouse Metaphase II Oocytes

Background: Oocyte vitrification has been widely used in the treatment of infertility and fertility preservation. However, vitrification-induced mitochondrial damage adversely affects oocyte development. Several studies have reported that mitochondrial calcium uptake protein 1 (MICU1) regulates the uptake of mitochondrial calcium by the mitochondrial calcium uniporter (MCU) and subsequently controls aerobic metabolism and oxidative stress in mitochondria, but research considering oocytes remains unreported. We evaluated whether the addition of MICU1 modulators enhances mitochondrial activity, pyruvate metabolism, and developmental competence after warming of MII oocytes. Methods: Retrieved MII oocytes of mice were classified as vitrified or control groups. After thawing, oocytes of vitrified group were cultured with or without DS16570511 (MICU1 inhibitor) and MCU-i4 (MICU1 activator) for 2 h. Results: Mitochondrial Ca2+ concentration, pyruvate dephosphorylation level, and MICU1 expression of MII oocytes were significantly increased after vitrification. These phenomena were further exacerbated by the addition of MCU-i4 and reversed by the addition of DS16570511 after warming. However, the mitochondrial membrane potential (MMP) and adenosine triphosphate (ATP) in vitrified-warmed MII oocytes drop significantly after vitrification, which was improved after MCU-i4 treatment and decreased significantly after DS16570511 treatment. The vitrification process was able to elicit a development competence reduction. After parthenogenetic activation, incubation of the thawed oocytes with MCU-i4 did not alter the cleavage and blastocyst rates. Moreover, incubation of the thawed oocytes with DS16570511 reduced the cleavage and blastocyst rates. Conclusions: MICU1-mediated increasing mitochondrial calcium uptake after vitrification of the MII oocytes promoted the pyruvate oxidation, and this process may maintain oocyte development competence by compensating for the consumption of ATP under stress state.

Cannabidiol: Influence on B Cells, Peripheral Blood Mononuclear Cells, and Peripheral Blood Mononuclear Cell/Rheumatoid Arthritis Synovial Fibroblast Cocultures.

Background: Cannabidiol (CBD), one major nonintoxicating phytocannabinoid from Cannabis sativa demonstrated anti-inflammatory effects in animal models of several inflammatory conditions, including arthritis. However, it is still unknown which cell types mediate these anti-inflammatory effects of CBD, and, since CBD binds to a plethora of receptors and enzymes, it is complicated to pinpoint its mechanism of action. In this study, we elucidate the effects of CBD on B cells and peripheral blood mononuclear cells (PBMCs) in respect to survival, calcium mobilization, drug uptake, and cytokine (IL-6, IL-10, and TNF) and immunoglobulin production. Methods: Modulation of intracellular calcium and drug uptake in B cells was determined by using the fluorescent dyes Cal-520 and PoPo3, respectively. Cytokine and immunoglobulin production was evaluated by enzyme-linked immunosorbent assay. PBMC composition and B cell survival after CBD treatment was assessed by flow cytometry. Results: B cells express two major target receptors for CBD, TRPV2 (transient receptor potential vanilloid 2) and TRPA1 (transient receptor potential ankyrin 1), which are not regulated by B cell activation. CBD increased intracellular calcium levels in mouse and human B cells, which was accompanied by enhanced uptake of PoPo3. These effects were not dependent on transient receptor potential channel activation. CBD increased the number of early apoptotic B cells at the expense of viable cells and diminished interleukin (IL)-10 and tumor necrosis factor (TNF) production when activated T cell independently. In PBMCs, CBD increased IL-10 production when B cells were activated T cell dependent, while decreasing TNF levels when activated T cell independently. In PBMC/rheumatoid synovial fibroblast cocultures, CBD reduced IL-10 production when B cells were activated T cell independently. Immunoglobulin M production was augmented by CBD when B cells were activated with CpG. Conclusion: CBD is able to provide pro- and anti-inflammatory effects in isolated B cells and PBMCs. This is dependent on the activating stimulus (T cell dependent or independent) and concentration of CBD. Therefore, CBD might be used to dampen B cell activity in autoimmune conditions such as rheumatoid arthritis, in which B cells are activated by specific autoantigens.

Efficacy of organic-based carrier material for plant beneficial rhizobacteria application in okra under normal and salt-affected soil conditions.

Plant beneficial rhizobacteria (PBR) improve salt tolerance and plant yield in vegetable plants by producing 1-aminocyclopropane-1-carboxylate-deaminase, indole-3-acetic acid and phosphate solubilization. Organic-based carrier material is needed to ensure the PBR's uniform application, distribution, survival and functioning in a variety of fields. The PBR also use carbon present in the carrier as food and energy source. The selection of a suitable organic-based carrier material for the application of the PBR in normal and saline soils always has received less attention. The current study compared the PBR suitability of different organic-based carrier materials (biochar, biogas residues [BGRs] and coconut powder) and evaluated their effects on okra productivity under normal and saline soil conditions. In a pot experiment, the PBR strain Bacillus sp. MR-1/2 (accession number, MG548383) was applied with/or without organic-based carrier materials to okra grown in three different soils: S1 (EC 1.0dS m-1 ), S2 (EC 3.0dS m-1 ) and S3 (EC 5.0dS m-1 ). The experiment was set up in a completely randomized design with five replicates in factorial arrangement. Results indicated that in soil S1, PBR + BGR increased the number of pods per plant, plant dry weight and indole compounds by 64%, 68% and 17% while reduced the electrolyte leakage (ELL), malonaldehyde (MDA) contents and stress ethylene level by 17%, 55% and 38%, respectively over the PBR application without any carrier. Similarly, in soil S2, the treatment PBR + BGR increased the number of pods by 81%, plant dry weight by 40% and indole compounds by 13% while reduced the ELL by 17%, MDA contents by 50% and stress ethylene by 30% over the PBR alone treatment. In soil S3, PBR + biochar increased the number of pods by 51%, plant dry weight by 62% and indole compounds by 20%, while reduced the ELL by 21%, MDA by 40% and indole compounds by 54% over the PBR alone treatment. Results concluded that in soil S1 and S2 (normal soils), BGR as carrier for PBR showed best results, while in soil S3, biochar as carrier for PBR resulted in enhanced potassium (K+ ) and calcium (Ca+2 ) uptake and increased the productivity of okra. Response of different carrier materials in supporting PBR under different soil conditions was variable. This study will help in the selection and use of best suitable carrier material for PBR application under different soil conditions. It is recommended that farmer should use BGR as carrier material for PBR application in normal soils while biochar should be used as carrier for the PBR application in saline soil.

МІКРОКЛОНАЛЬНЕ РОЗМНОЖЕННЯ ФУНДУКА

For the rapid introduction of large quantities of high-quality hazelnut planting material, it is important to use various modifications of microclonal propagation: classic on gel media, bioreactors with periodic flooding (TiS) and photoautotrophic methods. At the first stage of classical methods there are three main problems: phenol formation; endogenous contamination; selection of trophic and hormonal determinants of in vitro ontogenesis. In cases of infection of mother plants with viruses, viroids, it is mandatory to use meristem explants with a size of not more than 0.3 mm, followed by diagnosis of the effectiveness of recovery. To prevent self-intoxication with phenol-like oxidation products, a set of measures is used to prepare explant donors and modify nutrient media. The most common artificial nutrient media are Driver and Buzzard (DKW) and Nas and Read (NRM). Hazelnuts are sensitive to excess nitrogen and calcium and copper deficiency in artificial nutrient media. On media with a high N content, regenerants have shortened and thickened shoots, often with signs of hypehydration. Inhibition of calcium uptake by nitrogen leads to necrotization of shoot tips and root tips. The incorporation of iron ions into the metabolism of a plant depends on their valence and the form of chelating agents. During the multiplication and induction of rhizogenesis in aseptic conditions, mainly synthetic cytokinin benzylaminopurine and auxin indolylbutyric acid are used. The effectiveness of hormones increases with the use of combinations within groups, in particular cytokinins are benzylaminopurine and kinetin. At the stage of multiplication there is a predominance of cytokinins over auxins, and at the stage of rhizogenesis the number of auxins in the environment is greater than the number of cytokinins. Of the organic components, vitamins B1, B6, C, PP, amino acids and inositol are added to the environment. Ex vitro acclimatization of plants is carried out on peat-pearlite substrates in closed soil or modules of photoautrophic microclonal propagation with increased light intensity and high carbon dioxide content. The photoautotrophic method combines animation, rhizogenesis and acclimatization at the same time. The effectiveness of adaptation to factor-nestatic conditions increases with mycorrhizae by fungi of the genera Glomus, Trichoderma, Tuber in the transfer of plants from aseptic conditions.

Bile acid restrained T cell activation explains cholestasis aggravated hepatitis B virus infection.

Cholestasis is a common complication of hepatitis B virus (HBV) infection, characterized by increased intrahepatic and plasma bile acid levels. Cholestasis was found negatively associated with hepatitis outcome, however, the exact mechanism by which cholestasis impacts anti-viral immunity and impedes HBV clearance remains elusive. Here, we found that cholestatic mice are featured with dysfunctional T cells response, as indicated by decreased sub-population of CD25+ /CD69+ CD4+ and CD8+ cells, while CTLA-4+ CD4+ and CD8+ subsets were increased. Mechanistically, bile acids disrupt intracellular calcium homeostasis via inhibiting mitochondria calcium uptake and elevating cytoplasmic Ca2+ concentration, leading to STIM1 and ORAI1 decoupling and impaired store-operated Ca2+ entry which is essential for NFAT signaling and T cells activation. Moreover, in a transgenic mouse model of HBV infection, we confirmed that cholestasis compromised both CD4+ and CD8+ T cells activation resulting in poor viral clearance. Collectively, our results suggest that bile acids play pivotal roles in anti-HBV infection via controlling T cells activation and metabolism and that targeting the regulation of bile acids may be a therapeutic strategy for host-virus defense.

Pharmacological intervention of the FGF-PTH axis as a potential therapeutic for craniofacial ciliopathies.

ABSTRACTCiliopathies represent a disease class characterized by a broad range of phenotypes including polycystic kidneys and skeletal anomalies. Ciliopathic skeletal phenotypes are among the most common and most difficult to treat due to a poor understanding of the pathological mechanisms leading to disease. Using an avian model (talpid2) for a human ciliopathy with both kidney and skeletal anomalies (orofaciodigital syndrome 14), we identified disruptions in the FGF23–PTH axis that resulted in reduced calcium uptake in the developing mandible and subsequent micrognathia. Although pharmacological intervention with the U.S. Food and Drug Administration (FDA)-approved pan-FGFR inhibitor AZD4547 alone rescued expression of the FGF target SPRY2, it did not significantly rescue micrognathia. In contrast, treatment with a cocktail of AZD4547 and teriparatide acetate, a PTH agonist and FDA-approved treatment for osteoporosis, resulted in molecular, cellular and phenotypic rescue of ciliopathic micrognathia in talpid2 mutants. Together, these data provide novel insight into pathological molecular mechanisms associated with ciliopathic skeletal phenotypes and a potential therapeutic strategy for a pleiotropic disease class with limited to no treatment options.

Pharmacological sequestration of mitochondrial calcium uptake protects against dementia and β-amyloid neurotoxicity

All forms of dementia including Alzheimer’s disease are currently incurable. Mitochondrial dysfunction and calcium alterations are shown to be involved in the mechanism of neurodegeneration in Alzheimer’s disease. Previously we have described the ability of compound Tg-2112x to protect neurons via sequestration of mitochondrial calcium uptake and we suggest that it can also be protective against neurodegeneration and development of dementia. Using primary co-culture neurons and astrocytes we studied the effect of Tg-2112x and its derivative Tg-2113x on β-amyloid-induced changes in calcium signal, mitochondrial membrane potential, mitochondrial calcium, and cell death. We have found that both compounds had no effect on β-amyloid or acetylcholine-induced calcium changes in the cytosol although Tg2113x, but not Tg2112x reduced glutamate-induced calcium signal. Both compounds were able to reduce mitochondrial calcium uptake and protected cells against β-amyloid-induced mitochondrial depolarization and cell death. Behavioral effects of Tg-2113x on learning and memory in fear conditioning were also studied in 3 mouse models of neurodegeneration: aged (16-month-old) C57Bl/6j mice, scopolamine-induced amnesia (3-month-old mice), and 9-month-old 5xFAD mice. It was found that Tg-2113x prevented age-, scopolamine- and cerebral amyloidosis-induced decrease in fear conditioning. In addition, Tg-2113x restored fear extinction of aged mice. Thus, reduction of the mitochondrial calcium uptake protects neurons and astrocytes against β-amyloid-induced cell death and contributes to protection against dementia of different ethology. These compounds could be used as background for the developing of a novel generation of disease-modifying neuroprotective agents.

A controversial issue: Can mitochondria modulate cytosolic calcium and contraction of skeletal muscle fibers?

Mitochondria are characterized by a high capacity to accumulate calcium thanks to the electrochemical gradient created by the extrusion of protons in the respiratory chain. Thereby calcium can enter crossing the inner mitochondrial membrane via MCU complex, a high-capacity, low-affinity transport mechanism. Calcium uptake serves numerous purposes, among them the regulation of three dehydrogenases of the citric cycle, apoptosis via permeability transition, and, in some cell types, modulation of cytosolic calcium transients. This Review is focused on mitochondrial calcium uptake in skeletal muscle fibers and aims to reanalyze its functional impact. In particular, we ask whether mitochondrial calcium uptake is relevant for the control of cytosolic calcium transients and therefore of contractile performance. Recent data suggest that this may be the case, at least in particular conditions, as modified expression of MCU complex subunits or of proteins involved in mitochondrial dynamics and ablation of the main cytosolic calcium buffer, parvalbumin.

Uptake of Phosphate, Calcium, and Vitamin D by the Pregnant Uterus of Sheep in Late Gestation: Regulation by Chorionic Somatomammotropin Hormone.

Minerals are required for the establishment and maintenance of pregnancy and regulation of fetal growth in mammals. Lentiviral-mediated RNA interference (RNAi) of chorionic somatomammotropin hormone (CSH) results in both an intrauterine growth restriction (IUGR) and a non-IUGR phenotype in sheep. This study determined the effects of CSH RNAi on the concentration and uptake of calcium, phosphate, and vitamin D, and the expression of candidate mRNAs known to mediate mineral signaling in caruncles (maternal component of placentome) and cotyledons (fetal component of placentome) on gestational day 132. CSH RNAi Non-IUGR pregnancies had a lower umbilical vein–umbilical artery calcium gradient (p < 0.05) and less cotyledonary calcium (p < 0.05) and phosphate (p < 0.05) compared to Control RNAi pregnancies. CSH RNAi IUGR pregnancies had less umbilical calcium uptake (p < 0.05), lower uterine arterial and venous concentrations of 25(OH)D (p < 0.05), and trends for lower umbilical 25(OH)D uptake (p = 0.059) compared to Control RNAi pregnancies. Furthermore, CSH RNAi IUGR pregnancies had decreased umbilical uptake of calcium (p < 0.05), less uterine venous 25(OH)D (vitamin D metabolite; p = 0.055), lower caruncular expression of SLC20A2 (sodium-dependent phosphate transporter; p < 0.05) mRNA, and lower cotyledonary expression of KL (klotho; p < 0.01), FGFR1 (fibroblast growth factor receptor 1; p < 0.05), FGFR2 (p < 0.05), and TRPV6 (transient receptor potential vanilloid member 6; p < 0.05) mRNAs compared to CSH RNAi Non-IUGR pregnancies. This study has provided novel insights into the regulatory role of CSH for calcium, phosphate, and vitamin D utilization in late gestation.