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1.
BMJ Open ; 13(12): e074837, 2023 12 21.
Article in English | MEDLINE | ID: mdl-38135333

ABSTRACT

INTRODUCTION: Perioperative rehabilitation (PORT) has shown a positive effect on patients undergoing cardiac surgery. However, there are minimal data on the impact of short-term PORT in cardiac surgery, which is associated with higher postoperative morbidity and mortality. The trial will assess the efficacy of short-term PORT in reducing in-hospital mortality, postoperative pulmonary complications and length of stay, compared with the usual care in cardiac surgical patients. METHODS AND ANALYSIS: This is a single-centre prospective, randomised, open, controlled trial with a 1:1 ratio. Consecutive 800 adult patients undergoing elective valve surgery will be randomised to either usual care or in-hospital short-term PORT that consists of education, inspiratory muscle training, active cycle of breathing techniques and early mobilisation. The primary outcome of this study will be a composite of in-hospital all-cause mortality, incidence of postoperative pulmonary complications and the ratio of postoperative hospitalisation >7 days. ETHICS AND DISSEMINATION: The PORT study was granted by the Medical Research Ethics Committee of Guangdong Provincial People's Hospital in August 2018. Findings will be disseminated to patients, clinicians and commissioning groups through peer-reviewed publication. TRIAL REGISTRATION NUMBER: NCT03709511.


Subject(s)
Cardiac Surgical Procedures , Postoperative Complications , Adult , Humans , Prospective Studies , Postoperative Complications/etiology , Cardiac Surgical Procedures/adverse effects , Heart , Elective Surgical Procedures , Randomized Controlled Trials as Topic
2.
Metabolites ; 12(11)2022 Oct 28.
Article in English | MEDLINE | ID: mdl-36355118

ABSTRACT

Dairy cow mammary gland fibrosis causes huge economic losses to livestock production, however, research on dairy cow mammary gland fibrosis is in its infancy and it lacks effective treatments. Therefore, the purpose of this experiment was to explore the correlation between mastitis and fibrosis and mitochondrial damage, and to further explore its pathogenesis. In vivo, mammary tissue and milk samples were collected from healthy cows (n = 10) and mastitis cows (n = 10). The results of the study showed that compared with the control group, the mastitis tissue showed tissue damage, accumulation of collagen fibers, and the content of TGF-ß1 in mammary tissue and milk was significantly increased; the level of inflammatory mediators was significantly increased; the fibrotic phenotype, collagen 1, α-SMA, vimentin gene, and protein levels were significantly increased, while the E-cadherin gene and protein levels were significantly decreased. In vitro, based on TGF-ß1-induced bMECs, the above experimental results were further confirmed, and TGF-ß1 significantly promoted the fibrotic phenotype of bMECs. On the other hand, in vivo results showed that fibrotic mammary tissue had a significantly stronger mitochondrial damage phenotype and significantly higher ROS than the control group. In vitro, the results also found that TGF-ß1 induced a significant increase in the mitochondrial damage phenotype of bMECs, accompanied by a large amount of ROS production. Furthermore, in a TGF-ß1-induced bMEC model, inhibiting the accumulation of ROS effectively alleviated the elevated fibrotic phenotype of TGF-ß1-induced bMECs. In conclusion, the fibrotic phenotype of mammary gland tissue in dairy cows with mastitis was significantly increased, and mastitis disease was positively correlated with mammary fibrotic lesions. In an in vitro and in vivo model of cow mammary fibrosis, bMECs have impaired mitochondrial structure and dysfunction. Inhibiting the accumulation of ROS effectively alleviates the elevated fibrotic phenotype, which may be a potential therapeutic approach to alleviate mammary fibrosis.

3.
Aging (Albany NY) ; 13(23): 25377-25392, 2021 12 10.
Article in English | MEDLINE | ID: mdl-34890369

ABSTRACT

Mammary gland fibrosis is a chronic and irreversible disease. Tartary buckwheat flavonoids (TBF) are a natural product of flavonoid extracts from buckwheat and have a wide range of biological activities. The purpose of this experiment was to explore whether HFD during pregnancy and lactation induces fibrosis of the mammary tissue and whether TBF alleviates the damage caused by HFD, along with its underlying mechanism. The HFD significantly increased the levels of TNF-α, IL-6, IL-1ß, and MPO; significantly damaged the integrity of the blood-milk barrier; significantly increased the levels of collagen 1, vimentin and α-SMA, and reduced the level of E-cadherin. However, these effects were alleviated by TBF. Mechanistic studies showed that TBF inhibited the activation of AKT/NF-κB signaling and predicted the AKT amino acid residues that formed hydrogen bonds with TBF; in addition, these studies not only revealed that TBF promoted the expression of the tight junction proteins (TJs) claudin-3, occludin and ZO-1 and inhibited the activation of TGF-ß/Smad signaling but also predicted the Smad MH2 amino acid residues that formed hydrogen bonds with TBF. Conclusion: HFD consumption during pregnancy and lactation induced the tendency of mammary fibrosis. TBF alleviated the tendency of mammary fibrosis by inhibiting the activation of AKT/NF-κB, repairing the blood-milk barrier and inhibiting the activation of TGF-ß/Smad signaling.


Subject(s)
Diet, High-Fat/adverse effects , Fagopyrum/chemistry , Flavonoids/pharmacology , Mammary Glands, Animal/pathology , Plant Extracts/pharmacology , Animals , Blotting, Western , Female , Fibrosis , Lactation/drug effects , Male , Mammary Glands, Animal/drug effects , Mice, Inbred ICR , Pregnancy/drug effects
4.
Aging (Albany NY) ; 13(15): 19460-19474, 2021 08 12.
Article in English | MEDLINE | ID: mdl-34383710

ABSTRACT

Mastitis is a disease that seriously threatens the health of the mammary gland after delivery. Pedunculoside (PE) is the main bioactive component of Aquifoliaceae. The purpose of this experiment is to explore the effects of PE on mastitis and its underlying mechanisms. Our research results showed that PE could significantly inhibit the increase in the levels of inflammatory mediators such as TNF-α, IL-6, IL-1ß, MPO and iNOS during mastitis. Mechanism studies have found that PE could significantly inhibit the phosphorylation of AKT protein and binds to the ASP-184 site. Further research found that PE also inhibited the activation of AKT's downstream pro-inflammatory signals NF-κB and MAPK. In addition, PE effectively promote the expression of tight junction proteins occludin and claudin-3 during inflammation, maintaining the integrity of the blood-milk barrier. In summary, our research shows that PE inhibits the phosphorylation of AKT/NF-κB and MAPK signals; It also relieves mastitis by repairing the blood-milk barrier.


Subject(s)
Glucose/analogs & derivatives , Inflammation/prevention & control , MAP Kinase Signaling System/drug effects , Mastitis/prevention & control , Triterpenes/therapeutic use , Animals , Female , Glucose/pharmacology , Glucose/therapeutic use , Inflammation/metabolism , Inflammation Mediators/metabolism , Lipopolysaccharides , Male , Mastitis/chemically induced , Mastitis/metabolism , Mice , NF-kappa B/metabolism , Triterpenes/pharmacology
5.
J Biol Chem ; 293(33): 12962-12974, 2018 08 17.
Article in English | MEDLINE | ID: mdl-29954946

ABSTRACT

Store-operated Ca2+ entry signals are mediated by plasma membrane Orai channels activated through intermembrane coupling with Ca2+-sensing STIM proteins in the endoplasmic reticulum (ER). The nature of this elaborate Orai-gating mechanism has remained enigmatic. Based on the Drosophila Orai structure, mammalian Orai1 channels are hexamers comprising three dimeric subunit pairs. We utilized concatenated Orai1 dimers to probe the function of key domains within the channel pore and gating regions. The Orai1-E106Q selectivity-filter mutant, widely considered a dominant pore blocker, was surprisingly nondominant within concatenated heterodimers with Orai1-WT. The Orai1-E106Q/WT heterodimer formed STIM1-activated nonselective cation channels with significantly enlarged apparent pore diameter. Other Glu-106 substitutions entirely blocked the function of heterodimers with Orai1-WT. The hydrophobic pore-lining mutation V102C, which constitutively opens channels, was suppressed by Orai1-WT in the heterodimer. In contrast, the naturally occurring R91W pore-lining mutation associated with human immunodeficiency was completely dominant-negative over Orai-WT in heterodimers. Heterodimers containing the inhibitory K85E mutation extending outward from the pore helix gave an interesting partial effect on both channel activation and STIM1 binding, indicating an important allosteric link between the cytosolic Orai1 domains. The Orai1 C-terminal STIM1-binding domain mutation L273D powerfully blocked STIM1-induced channel activation. The Orai1-L273D/WT heterodimer had drastically impaired STIM1-induced channel gating but, unexpectedly, retained full STIM1 binding. This reveals the critical role of Leu-273 in transducing the STIM1-binding signal into the allosteric conformational change that initiates channel gating. Overall, our results provide important new insights into the role of key functional domains that mediate STIM1-induced gating of the Orai1 channel.


Subject(s)
Endoplasmic Reticulum/metabolism , Ion Channel Gating , Mutation, Missense , Neoplasm Proteins/metabolism , ORAI1 Protein/metabolism , Protein Multimerization , Stromal Interaction Molecule 1/metabolism , Allosteric Regulation , Amino Acid Substitution , Animals , Drosophila melanogaster , Endoplasmic Reticulum/genetics , HEK293 Cells , Humans , Neoplasm Proteins/genetics , ORAI1 Protein/genetics , Protein Domains , Stromal Interaction Molecule 1/genetics
6.
Proc Natl Acad Sci U S A ; 115(15): E3398-E3407, 2018 04 10.
Article in English | MEDLINE | ID: mdl-29581306

ABSTRACT

The transmembrane docking of endoplasmic reticulum (ER) Ca2+-sensing STIM proteins with plasma membrane (PM) Orai Ca2+ channels is a critical but poorly understood step in Ca2+ signal generation. STIM1 protein dimers unfold to expose a discrete STIM-Orai activating region (SOAR1) that tethers and activates Orai1 channels within discrete ER-PM junctions. We reveal that each monomer within the SOAR dimer interacts independently with single Orai1 subunits to mediate cross-linking between Orai1 channels. Superresolution imaging and mobility measured by fluorescence recovery after photobleaching reveal that SOAR dimer cross-linking leads to substantial Orai1 channel clustering, resulting in increased efficacy and cooperativity of Orai1 channel function. A concatenated SOAR1 heterodimer containing one monomer point mutated at its critical Orai1 binding residue (F394H), although fully activating Orai channels, is completely defective in cross-linking Orai1 channels. Importantly, the naturally occurring STIM2 variant, STIM2.1, has an eight-amino acid insert in its SOAR unit that renders it functionally identical to the F394H mutant in SOAR1. Contrary to earlier predictions, the SOAR1-SOAR2.1 heterodimer fully activates Orai1 channels but prevents cross-linking and clustering of channels. Interestingly, combined expression of full-length STIM1 with STIM2.1 in a 5:1 ratio causes suppression of sustained agonist-induced Ca2+ oscillations and protects cells from Ca2+ overload, resulting from high agonist-induced Ca2+ release. Thus, STIM2.1 exerts a powerful regulatory effect on signal generation likely through preventing Orai1 channel cross-linking. Overall, STIM-mediated cross-linking of Orai1 channels is a hitherto unrecognized functional paradigm that likely provides an organizational microenvironment within ER-PM junctions with important functional impact on Ca2+ signal generation.


Subject(s)
Neoplasm Proteins/chemistry , Neoplasm Proteins/metabolism , ORAI1 Protein/chemistry , ORAI1 Protein/metabolism , Stromal Interaction Molecule 1/chemistry , Stromal Interaction Molecule 1/metabolism , Stromal Interaction Molecule 2/chemistry , Stromal Interaction Molecule 2/metabolism , Calcium/metabolism , Dimerization , Endoplasmic Reticulum/chemistry , Endoplasmic Reticulum/genetics , Endoplasmic Reticulum/metabolism , Humans , Membrane Proteins/chemistry , Membrane Proteins/genetics , Membrane Proteins/metabolism , Neoplasm Proteins/genetics , ORAI1 Protein/genetics , Protein Domains , Stromal Interaction Molecule 1/genetics , Stromal Interaction Molecule 2/genetics
7.
Adv Exp Med Biol ; 993: 83-98, 2017.
Article in English | MEDLINE | ID: mdl-28900910

ABSTRACT

Store-operated Ca2+ entry fulfills a crucial role in controlling Ca2+ signals in almost all cells. The Ca2+-sensing stromal interaction molecule (STIM) proteins in the endoplasmic reticulum (ER) undergo complex conformational changes in response to depleted ER luminal Ca2+, allowing them to unfold and become trapped in ER-plasma membrane (PM) junctions. Dimers of STIM proteins trap and gate the plasma membrane Orai Ca2+ channels within these junctions to generate discrete zones of high Ca2+ and regulate sensitive Ca2+-dependent intracellular signaling pathways. The STIM-Orai activating region (SOAR) of STIM1 becomes exposed upon store depletion and promotes trapping of Orai1 at the PM. Residue Phe-394 within SOAR forms an integral part of the high-affinity Orai1-interacting site. Our results demonstrate that only a single active site within the dimeric SOAR domain of STIM1 is required for the activation of Orai1 channel activity. This unimolecular model is strongly supported by evidence of variable STIM1:Orai1 stoichiometry reported in many studies. We hypothesize that unimolecular coupling promotes cross-linking of channels, localizing Ca2+ signals, and regulating channel activity. We have also identified a key "nexus" region in Orai1 near the C-terminal STIM1-binding site that can be mutated to constitutively activate Ca2+ entry, mimicking STIM1 activated channels. This suggests that STIM1 mediates gating of Orai1 in an allosteric manner via interaction with the Orai1 C-terminus alone. This model suggests the dual role of STIM1 in regulating both localization and gating of Orai1 channels and has important implications for the regulation of SOCE-mediated downstream signaling and the kinetics of channel activation.


Subject(s)
Calcium/metabolism , ORAI1 Protein/metabolism , Stromal Interaction Molecule 1/metabolism , Animals , Calcium Signaling/physiology , Cell Membrane/metabolism , Humans
8.
Cell Calcium ; 63: 8-13, 2017 05.
Article in English | MEDLINE | ID: mdl-28087079

ABSTRACT

In virtually all cells, store-operated Ca2+ entry signals are vital in controlling a spectrum of functions. The signals are mediated by STIM proteins in the ER and Orai channels in the PM which undergo a dynamic coupling process within discrete ER-PM junctional regions. This coupling is initiated by depletion of ER stored Ca2+ triggering STIM proteins to undergo an intricate activation process. Thereafter, STIM proteins become trapped in the ER-PM junctions where they tether and gate PM Orai Ca2+ channels. STIM1 exists as a dimer, with a single STIM-Orai activating region (SOAR) buried in the resting protein that becomes exposed upon activation. An exposed region on SOAR including the Phe-394 residue forms a critical Orai1 interacting site. Using dimeric SOAR concatemers, we reveal only one of the two sites in the SOAR dimer is needed for Orai1 activation. This unimolecular interaction of SOAR with Orai1 suggests STIM1 can cross-link Orai channels with important significance for Ca2+ signaling. A critical "nexus" region in Orai1 close to the STIM1-binding site can be mutated to constitutively activate the channel mimicking the gating action of STIM1. This indicates STIM1 remotely controls Orai1 channel gating through an allosteric switch triggered by STIM1 binding only to the exposed C-terminal tail of the Orai1 channel.


Subject(s)
Calcium/metabolism , Ion Channel Gating/physiology , ORAI1 Protein/metabolism , Stromal Interaction Molecule 1/metabolism , Animals , Humans
9.
Nat Commun ; 7: 13725, 2016 12 08.
Article in English | MEDLINE | ID: mdl-27929067

ABSTRACT

The ubiquitously expressed Orai Ca2+ channels are gated through a unique process of intermembrane coupling with the Ca2+-sensing STIM proteins. Despite the significance of Orai1-mediated Ca2+ signals, how gating of Orai1 is triggered by STIM1 remains unknown. A widely held gating model invokes STIM1 binding directly to Orai1 pore-forming helix. Here we report that an Orai1 C-terminal STIM1-binding site, situated far from the N-terminal pore helix, alone provides the trigger that is necessary and sufficient for channel gating. We identify a critical 'nexus' within Orai1 connecting the peripheral C-terminal STIM1-binding site to the Orai1 core helices. Mutation of the nexus transforms Orai1 into a persistently open state exactly mimicking the action of STIM1. We suggest that the Orai1 nexus transduces the STIM1-binding signal through a conformational change in the inner core helices, and that STIM1 remotely gates the Orai1 channel without the necessity for direct STIM1 contact with the pore-forming helix.


Subject(s)
Ion Channel Gating , Neoplasm Proteins/metabolism , ORAI1 Protein/metabolism , Stromal Interaction Molecule 1/metabolism , HEK293 Cells , Humans , Mutagenesis, Site-Directed , ORAI1 Protein/genetics
10.
J Biol Chem ; 291(50): 25764-25775, 2016 Dec 09.
Article in English | MEDLINE | ID: mdl-27780862

ABSTRACT

Orai channels mediate store-operated Ca2+ signals crucial in regulating transcription in many cell types, and implicated in numerous immunological and inflammatory disorders. Despite their central importance, controversy surrounds the basic subunit structure of Orai channels, with several biochemical and biophysical studies suggesting a tetrameric structure yet crystallographic evidence indicating a hexamer. We systematically investigated the subunit configuration of the functional Orai1 channel, generating a series of tdTomato-tagged concatenated Orai1 channel constructs (dimers to hexamers) expressed in CRISPR-derived ORAI1 knock-out HEK cells, stably expressing STIM1-YFP. Surface biotinylation demonstrated that the full-length concatemers were surface membrane-expressed. Unexpectedly, Orai1 dimers, trimers, tetramers, pentamers, and hexamers all mediated similar and substantial store-operated Ca2+ entry. Moreover, each Orai1 concatemer mediated Ca2+ currents with inward rectification and reversal potentials almost identical to those observed with expressed Orai1 monomer. In Orai1 tetramers, subunit-specific replacement with Orai1 E106A "pore-inactive" subunits revealed that functional channels utilize only the N-terminal dimer from the tetramer. In contrast, Orai1 E106A replacement in Orai1 hexamers established that all the subunits can contribute to channel formation, indicating a hexameric channel configuration. The critical Ca2+ selectivity filter-forming Glu-106 residue may mediate Orai1 channel assembly around a central Ca2+ ion within the pore. Thus, multiple E106A substitutions in the Orai1 hexamer may promote an alternative "trimer-of-dimers" channel configuration in which the C-terminal E106A subunits are excluded from the hexameric core. Our results argue strongly against a tetrameric configuration for Orai1 channels and indicate that the Orai1 channel functions as a hexamer.


Subject(s)
Calcium , ORAI1 Protein/metabolism , Protein Multimerization/physiology , Amino Acid Substitution , Gene Knockdown Techniques , HEK293 Cells , Humans , Mutation, Missense , ORAI1 Protein/genetics
11.
Nat Commun ; 6: 8395, 2015 Sep 24.
Article in English | MEDLINE | ID: mdl-26399906

ABSTRACT

The endoplasmic reticulum (ER) Ca(2+) sensor, STIM1, becomes activated when ER-stored Ca(2+) is depleted and translocates into ER-plasma membrane junctions where it tethers and activates Orai1 Ca(2+) entry channels. The dimeric STIM1 protein contains a small STIM-Orai-activating region (SOAR)--the minimal sequence sufficient to activate Orai1 channels. Since SOAR itself is a dimer, we constructed SOAR concatemer-dimers and introduced mutations at F394, which is critical for Orai1 coupling and activation. The F394H mutation in both SOAR monomers completely blocks dimer function, but F394H introduced in only one of the dimeric SOAR monomers has no effect on Orai1 binding or activation. This reveals an unexpected unimolecular coupling between STIM1 and Orai1 and argues against recent evidence suggesting dimeric interaction between STIM1 and two adjacent Orai1 channel subunits. The model predicts that STIM1 dimers may be involved in crosslinking between Orai1 channels with implications for the kinetics and localization of Orai1 channel opening.


Subject(s)
Calcium Channels/metabolism , Endoplasmic Reticulum/metabolism , Membrane Proteins/metabolism , Neoplasm Proteins/metabolism , Binding Sites/genetics , Blotting, Western , Calcium/metabolism , Chromatography, Gel , Cytosol/metabolism , Dimerization , Fluorescence Resonance Energy Transfer , HEK293 Cells , Humans , Membrane Proteins/genetics , Mutation , Neoplasm Proteins/genetics , ORAI1 Protein , Patch-Clamp Techniques , Protein Binding/genetics , Protein Structure, Tertiary , Stromal Interaction Molecule 1
12.
Cell Calcium ; 56(6): 482-92, 2014 Dec.
Article in English | MEDLINE | ID: mdl-25459299

ABSTRACT

The coupling of ER Ca(2+)-sensing STIM proteins and PM Orai Ca(2+) entry channels generates "store-operated" Ca(2+) signals crucial in controlling responses in many cell types. The dimeric derivative of 2-aminoethoxydiphenyl borinate (2-APB), DPB162-AE, blocks functional coupling between STIM1 and Orai1 with an IC50 (200 nM) 100-fold lower than 2-APB. Unlike 2-APB, DPB162-AE does not affect L-type or TRPC channels or Ca(2+) pumps at maximal STIM1-Orai1 blocking levels. DPB162-AE blocks STIM1-induced Orai1 or Orai2, but does not block Orai3 or STIM2-mediated effects. We narrowed the DPB162-AE site of action to the STIM-Orai activating region (SOAR) of STIM1. DPB162-AE does not prevent the SOAR-Orai1 interaction but potently blocks SOAR-mediated Orai1 channel activation, yet its action is not as an Orai1 channel pore blocker. Using the SOAR-F394H mutant which prevents both physical and functional coupling to Orai1, we reveal DPB162-AE rapidly restores SOAR-Orai binding but only slowly restores Orai1 channel-mediated Ca(2+) entry. With the same SOAR mutant, 2-APB induces rapid physical and functional coupling to Orai1, but channel activation is transient. We infer that the actions of both 2-APB and DPB162-AE are directed toward the STIM1-Orai1 coupling interface. Compared to 2-APB, DPB162-AE is a much more potent and specific STIM1/Orai1 functional uncoupler. DPB162-AE provides an important pharmacological tool and a useful mechanistic probe for the function and coupling between STIM1 and Orai1 channels.


Subject(s)
Boron Compounds/pharmacology , Calcium Channels/drug effects , Membrane Glycoproteins/drug effects , Membrane Proteins/drug effects , Neoplasm Proteins/drug effects , Uncoupling Agents/pharmacology , Animals , Calcium/metabolism , Calcium Channels/metabolism , Cell Line , Fluorescence Resonance Energy Transfer , HEK293 Cells , Humans , Jurkat Cells , Leukemia, Basophilic, Acute , ORAI1 Protein , Rats , Stromal Interaction Molecule 1
13.
Mol Cell ; 54(3): 362-77, 2014 May 08.
Article in English | MEDLINE | ID: mdl-24746696

ABSTRACT

Mitochondrial autophagy, or mitophagy, is a major mechanism involved in mitochondrial quality control via selectively removing damaged or unwanted mitochondria. Interactions between LC3 and mitophagy receptors such as FUNDC1, which harbors an LC3-interacting region (LIR), are essential for this selective process. However, how mitochondrial stresses are sensed to activate receptor-mediated mitophagy remains poorly defined. Here, we identify that the mitochondrially localized PGAM5 phosphatase interacts with and dephosphorylates FUNDC1 at serine 13 (Ser-13) upon hypoxia or carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP) treatment. Dephosphorylation of FUNDC1 catalyzed by PGAM5 enhances its interaction with LC3, which is abrogated following knockdown of PGAM5 or the introduction of a cell-permeable unphosphorylated peptide encompassing the Ser-13 and LIR of FUNDC1. We further observed that CK2 phosphorylates FUNDC1 to reverse the effect of PGAM5 in mitophagy activation. Our results reveal a mechanistic signaling pathway linking mitochondria-damaging signals to the dephosphorylation of FUNDC1 by PGAM5, which ultimately induces mitophagy.


Subject(s)
Carrier Proteins/metabolism , Casein Kinase II/metabolism , Membrane Proteins/metabolism , Mitochondrial Proteins/metabolism , Mitophagy , Protein Processing, Post-Translational , Amino Acid Sequence , Consensus Sequence , Feedback, Physiological , HeLa Cells , Humans , Membrane Proteins/chemistry , Microtubule-Associated Proteins/metabolism , Mitochondrial Proteins/chemistry , Molecular Sequence Data , Phosphoprotein Phosphatases , Phosphorylation
14.
PLoS One ; 8(4): e62373, 2013.
Article in English | MEDLINE | ID: mdl-23638055

ABSTRACT

Phosphoinositide-3-kinase α (PI3Kα) represents a potential novel drug target for pathological cardiac hypertrophy (PCH) and heart failure. Oligodeoxynucleotides containing CpG motifs (CpG-ODN) are classic agonists of Toll-like receptor 9 (TLR9), which typically activates PI3K-Akt signaling in immune cells; however, the role of the nucleotide TLR9 agonists in cardiac myocytes is largely unknown. Here we report that CpG-ODN C274 could both attenuate PCH and improve cardiac dysfunction by activating PI3Kα-Akt signaling cascade. In vitro studies indicated that C274 could blunt reactivation of fetal cardiac genes and cell enlargement induced by a hypertrophic agent, isoproterenol. The anti-hypertrophic effect of C274 was suppressed by a pan-PI3K inhibitor, LY294002, or a small interfering RNA targeting PI3Kα. In vivo studies demonstrated that PCH, as marked by increased heart weight (HW) and cardiac ANF mRNA, was normalized by pre-administration with C274. In addition, Doppler echocardiography detected cardiac ventricular dilation, and contractile dysfunction in isoproterenol-treated animals, consistent with massive replacement fibrosis, reflecting cardiac cell death. As expected, pre-treatment of mice with C274 could prevent cardiac dysfunction associated with diminished cardiac cell death and fibrosis. In conclusion, CpG-ODNs are novel cardioprotective agents possessing antihypertrophic and anti-cell death activity afforded by engagement of the PI3Kα-Akt signaling. CpG-ODNs may have clinical use curbing the progression of PCH and preventing heart failure.


Subject(s)
Adjuvants, Immunologic/therapeutic use , Cardiomegaly/drug therapy , Heart/drug effects , Oligodeoxyribonucleotides/therapeutic use , Phosphatidylinositol 3-Kinases/metabolism , Proto-Oncogene Proteins c-akt/metabolism , Adjuvants, Immunologic/pharmacology , Animals , Cardiomegaly/enzymology , Cardiomegaly/metabolism , Cardiomegaly/pathology , Cell Size/drug effects , Enzyme Activation/drug effects , Gene Expression Regulation, Developmental/drug effects , Heart/physiopathology , Mice , Mice, Inbred C57BL , Myocardium/metabolism , Myocardium/pathology , Oligodeoxyribonucleotides/pharmacology , Rats , Rats, Sprague-Dawley , Signal Transduction/drug effects
15.
Article in English | MEDLINE | ID: mdl-23545639

ABSTRACT

GNA1162, a predicted lipoprotein from Neisseria meningitidis, is a potential candidate for a universal vaccine against meningococcal disease caused by N. meningitidis serogroup B. Here, the crystal structure of GNA1162 at 1.89 Å resolution determined by single-wavelength anomalous dispersion (SAD) is reported. The structure of GNA1162 appears to be a dimer in the crystallographic asymmetric unit as well as in solution. The overall structure of the dimer indicates that each monomer inserts its C-terminal α5 helix into the hydrophobic groove of the other molecule. Moreover, the ß4 strands of each monomer lie antiparallel to each other and interact through multiple main-chain hydrogen bonds. Through structural comparisons and operon predictions, it is hypothesized that GNA1162 is part of a transport system and assists in transport and reassembly. The crystal structure of GNA1162 sheds light on its possible function and provides potentially valuable information for the design of a vaccine against meningococcal disease.


Subject(s)
Lipoproteins/chemistry , Neisseria meningitidis/chemistry , Models, Molecular , Protein Structure, Quaternary , Protein Structure, Tertiary , Structural Homology, Protein
16.
Proc Natl Acad Sci U S A ; 109(15): 5657-62, 2012 Apr 10.
Article in English | MEDLINE | ID: mdl-22451904

ABSTRACT

Calcium influx through the Ca(2+) release-activated Ca(2+) (CRAC) channel is an essential process in many types of cells. Upon store depletion, the calcium sensor in the endoplasmic reticulum, STIM1, activates Orai1, a CRAC channel in the plasma membrane. We have determined the structures of SOAR from Homo sapiens (hSOAR), which is part of STIM1 and is capable of constitutively activating Orai1, and the entire coiled coil region of STIM1 from Caenorhabditis elegans (ceSTIM1-CCR) in an inactive state. Our studies reveal that the formation of a SOAR dimer is necessary to activate the Orai1 channel. Mutations that disrupt SOAR dimerization or remove the cluster of positive residues abolish STIM1 activation of Orai1. We identified a possible inhibitory helix within the structure of ceSTIM1-CCR that tightly interacts with SOAR. Functional studies suggest that the inhibitory helix may keep the C-terminus of STIM1 in an inactive state. Our data allowed us to propose a model for STIM1 activation.


Subject(s)
Caenorhabditis elegans Proteins/chemistry , Caenorhabditis elegans Proteins/metabolism , Caenorhabditis elegans/metabolism , Membrane Proteins/chemistry , Membrane Proteins/metabolism , Neoplasm Proteins/chemistry , Neoplasm Proteins/metabolism , Amino Acids/metabolism , Animals , Cluster Analysis , HEK293 Cells , HeLa Cells , Humans , Models, Biological , Models, Molecular , Protein Conformation , Protein Multimerization , Protein Structure, Tertiary , Stromal Interaction Molecule 1 , Structure-Activity Relationship
17.
J Biol Chem ; 286(47): 40782-91, 2011 Nov 25.
Article in English | MEDLINE | ID: mdl-21971046

ABSTRACT

Fetal cardiac gene reactivation is a hallmark of pathological cardiac hypertrophy (PCH) driven by cardiac transcription factors (TFs) such as nuclear factor of activated T-cells (NFATs). Nuclear import of dephosphorylated NFATs catalyzed by calcineurin (CaN) is a well-established hypertrophic mechanism. Here we report that NFATc4 expression is also up-regulated by newly expressed protein kinase D3 (PKD3) to induce PCH. In both in vitro and in vivo cardiac hypertrophic models, the normally undetectable PKD3 was profoundly up-regulated by isoproterenol followed by overt expression of cardiac TFs including NFATc4, NK family of transcription factor 2.5 (Nkx2.5), GATA4 and myocyte enhancer factor 2 (MEF2). Using gene silencing approaches, we demonstrate PKD3 is required for increasing the expression of NFATc4, Nkx2.5, and GATA4 while PKD1 is required for the increase in MEF2D expression. Upstream induction of PKD3 is driven by nuclear entry of CaN-activated NFATc1 and c3 but not c4. Therefore, PKD3 is a pivotal mediator of the CaN-NFATc1/c3-PKD3-NFATc4 hypertrophic signaling cascade and a potential new drug target for the PCH.


Subject(s)
Cardiomegaly/enzymology , Cardiomegaly/genetics , Protein Kinase C/metabolism , Transcription Factors/genetics , Transcription Factors/metabolism , Up-Regulation , Animals , Animals, Newborn , Cardiomegaly/metabolism , Isoproterenol/pharmacology , Myocytes, Cardiac/drug effects , Myocytes, Cardiac/metabolism , Protein Kinase C/genetics , Protein Kinases/metabolism , Rats , Rats, Sprague-Dawley , Transcriptional Activation/drug effects , Up-Regulation/drug effects
18.
Biochem Biophys Res Commun ; 409(1): 125-30, 2011 May 27.
Article in English | MEDLINE | ID: mdl-21554860

ABSTRACT

Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is a new promising target for prevention and treatment of cardiac hypertrophy and heart failure. There are three δ isoforms of CaMKII in the heart and previous studies focused primarily on δB and δC types. Here we report the δA isoform of CaMKII is also critically involved in cardiac hypertrophy. We found that δA was significantly upregulated in pathological cardiac hypertrophy in both neonatal and adult models. Upregulation of δA was accompanied by cell enlargement, sarcomere reorganization and reactivation of various hypertrophic cardiac genes including atrial natriuretic factor (ANF) and ß-myocin heavy chain (ß-MHC). Studies further indicated the pathological changes were largely blunted by silencing the δA gene and an underlying mechanism indicated selective interference with the HDAC4-MEF2 signaling pathway. These results provide new evidence for selective interfering cardiac hypertrophy and heart failure when CaMKII is considered as a therapeutic target.


Subject(s)
Calcium-Calmodulin-Dependent Protein Kinase Type 2/biosynthesis , Cardiomegaly/metabolism , Histone Deacetylases/metabolism , MADS Domain Proteins/metabolism , Myogenic Regulatory Factors/metabolism , Animals , Calcium-Calmodulin-Dependent Protein Kinase Type 2/genetics , Cardiomegaly/genetics , Cardiomegaly/pathology , Gene Silencing , Histone Deacetylases/genetics , Isoenzymes/genetics , Isoenzymes/metabolism , MEF2 Transcription Factors , Rats , Rats, Sprague-Dawley , Signal Transduction , Up-Regulation
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