Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 95
Filter
1.
Sci Rep ; 14(1): 7951, 2024 Apr 04.
Article in English | MEDLINE | ID: mdl-38575721

ABSTRACT

Mangrove forests reduce wave attack along tropical and sub-tropical coastlines, decreasing the wave loads acting on coastal protection structures. Mangrove belts seaward of embankments can therefore lower their required height and decrease their slope protection thickness. Wave reduction by mangroves depends on tree frontal surface area and stability against storms, but both aspects are often oversimplified or neglected in coastal protection designs. Here we present a framework to evaluate how mangrove belts influence embankment designs, including mangrove growth over time and failure by overturning and trunk breakage. This methodology is applied to Sonneratia apetala mangroves seaward of embankments in Bangladesh, considering forest widths between 10 and 1000 m (cross-shore). For water depths of 5 m, wave reduction by mangrove forests narrower than 1 km mostly affects the slope protection and the bank erodibility, whereas the required embankment height is less influenced by mangroves. Sonneratia apetala trees experience a relative maximum in wave attenuation capacity at 10 years age, due to their large submerged canopy area. Once trees are more than 20 years old, their canopy is emergent, and most wave attenuation is caused by trunk and roots. Canopy emergence exposes mangroves to wind loads, which are much larger than wave loads, and can cause tree failure during cyclones. These results stress the importance of including tree surface area and stability models when predicting coastal protection by mangroves.

2.
J Chem Theory Comput ; 20(3): 1448-1464, 2024 Feb 13.
Article in English | MEDLINE | ID: mdl-38279917

ABSTRACT

The accuracy of classical force fields (FFs) has been shown to be limited for the simulation of cation-protein systems despite their importance in understanding the processes of life. Improvements can result from optimizing the parameters of classical FFs or by extending the FF formulation by terms describing charge transfer (CT) and polarization (POL) effects. In this work, we introduce our implementation of the CTPOL model in OpenMM, which extends the classical additive FF formula by adding CT and POL. Furthermore, we present an open-source parametrization tool, called FFAFFURR, that enables the (system-specific) parametrization of OPLS-AA and CTPOL models. The performance of our workflow was evaluated by its ability to reproduce quantum chemistry energies and by molecular dynamics simulations of a zinc-finger protein.

3.
BMC Microbiol ; 21(1): 341, 2021 12 13.
Article in English | MEDLINE | ID: mdl-34903172

ABSTRACT

BACKGROUND: Fungal infections impact over 25% of the global population. For the opportunistic fungal pathogen, Cryptococcus neoformans, infection leads to cryptococcosis. In the presence of the host, disease is enabled by elaboration of sophisticated virulence determinants, including polysaccharide capsule, melanin, thermotolerance, and extracellular enzymes. Conversely, the host protects itself from fungal invasion by regulating and sequestering transition metals (e.g., iron, zinc, copper) important for microbial growth and survival. RESULTS: Here, we explore the intricate relationship between zinc availability and fungal virulence via mass spectrometry-based quantitative proteomics. We observe a core proteome along with a distinct zinc-regulated protein-level signature demonstrating a shift away from transport and ion binding under zinc-replete conditions towards transcription and metal acquisition under zinc-limited conditions. In addition, we revealed a novel connection among zinc availability, thermotolerance, as well as capsule and melanin production through the detection of a Wos2 ortholog in the secretome under replete conditions. CONCLUSIONS: Overall, we provide new biological insight into cellular remodeling at the protein level of C. neoformans under regulated zinc conditions and uncover a novel connection between zinc homeostasis and fungal virulence determinants.


Subject(s)
Cryptococcus neoformans/pathogenicity , Molecular Chaperones/metabolism , Proteome/metabolism , Secretome/metabolism , Zinc/metabolism , Cryptococcus neoformans/metabolism , Fungal Capsules/metabolism , Fungal Proteins/genetics , Fungal Proteins/metabolism , Melanins/metabolism , Molecular Chaperones/genetics , Mutation , Proteomics , Thermotolerance , Virulence/genetics
4.
Gynecol Oncol Rep ; 37: 100822, 2021 Aug.
Article in English | MEDLINE | ID: mdl-34258362

ABSTRACT

INTRODUCTION: Recent image-guided brachytherapy data suggests, dose-escalation to a cumulative EQD2 (equivalent dose delivered at 2 Gy/#) of ≥87 Gy is associated with significantly better disease control. We present a clinical audit of a pragmatic radical radiotherapy protocol for advanced cervical cancer, using fewer fractions of brachytherapy than in the presently most popular protocol. MATERIAL & METHODS: Between July 2015 and December 2018, 96 consecutive advanced cervical carcinoma patients were treated by pelvic external beam radiotherapy (EBRT) (50 Gy/25fractions/5 weeks) ± weekly intravenous chemotherapy followed by image guided high dose rate (HDR) brachytherapy, using intracavitary/interstitial/hybrid techniques (intended point A dose: 8 Gy/fractions) × 3 fractions (cumulative target EQD2 ≥ 86 Gy). Insertion was done individually for each fraction of treatment. RESULTS: All patients completed their intended radiation protocol. 93.8% patients achieved complete response, while 6.2% patients achieved only partial response; no patients had stable/progressive disease. Out of the patients with partial response, 4.2% (4 out of 5 cases) cases of central/nodal residual disease underwent salvage surgery. At a median follow up of 21 months, 8.3% (8) patients had local failure, 1.1% (1) had nodal failure and 3.1% (3) had distant failures. Median Failure Free Survival was 29 months (26.5-31.5 months). On follow up, 6.3% and 3.2% patients had grade 2 or worse rectal and bladder morbidities respectively. CONCLUSION: The protocol under study has been safe and effective in achieving dose-escalated radical chemoradiation in advanced cervical carcinoma. The use of fewer insertions of brachytherapy is logistically easier & can also be expected to improve compliance.

5.
Benef Microbes ; 12(4): 27-34, 2021 Aug 30.
Article in English | MEDLINE | ID: mdl-34057053

ABSTRACT

The gut microbiome during infancy is directly involved in the digestion of human milk, development of the immune system, and long-term health outcomes. Gut dysbiosis in early life has been linked to multiple short-term ailments, from diaper dermatitis and poor stooling habits, to poor sleep and fussiness, with mixed results in the scientific literature on the efficacy of probiotics for symptom resolution. Despite the growing interest in probiotics for consumer use, observed symptomatic relief is rarely documented. This study aims to evaluate observed symptomatic relief from at-home use of activated Bifidobacterium infantis EVC001 in infants. Consumer feedback was collected over a 2-year period via a 30-day post-purchase online survey of B. infantis EVC001 (Evivo®) customers. Outcome measures included observed changes in diaper rash, symptoms of colic, and sleep behaviours in infants fed B. infantis EVC001. A total of 1,621 respondents completed the survey. Before purchasing B. infantis EVC001, the majority of respondents visited the product website, researched infant probiotics online, or consulted with their doctor or other healthcare professional. Of the participants whose infants had ever experienced diaper rash, 72% (n=448) reported improvements, and 57% of those reported complete resolution of this problem. Of those who responded to questions about gassiness/fussiness, naptime sleep, and night-time sleep behaviours, 63% (n=984), 33% (n=520), and 52% (n=806) reported resolution or improvements, respectively. Although clinical data regarding probiotic use are often inconclusive for symptom resolution, home use of B. infantis EVC001 in infants improved diaper rash, gassiness/fussiness, and sleep quality within the first week of use in a significant number of respondents who engaged in a voluntary post-purchase survey. These outcomes may be a result of the unique genetic capacity of B. infantis EVC001 to colonise the infant gut highlighting the importance of strain selection in evaluating the effects of probiotic products.


Subject(s)
Bifidobacterium longum subspecies infantis , Colic , Diaper Rash , Probiotics , Sleep , Bifidobacterium , Colic/therapy , Diaper Rash/therapy , Humans , Infant , Probiotics/therapeutic use
6.
Allergy ; 76(10): 2952-2964, 2021 10.
Article in English | MEDLINE | ID: mdl-33811358

ABSTRACT

Older adults, especially men and/or those with diabetes, hypertension, and/or obesity, are prone to severe COVID-19. In some countries, older adults, particularly those residing in nursing homes, have been prioritized to receive COVID-19 vaccines due to high risk of death. In very rare instances, the COVID-19 vaccines can induce anaphylaxis, and the management of anaphylaxis in older people should be considered carefully. An ARIA-EAACI-EuGMS (Allergic Rhinitis and its Impact on Asthma, European Academy of Allergy and Clinical Immunology, and European Geriatric Medicine Society) Working Group has proposed some recommendations for older adults receiving the COVID-19 vaccines. Anaphylaxis to COVID-19 vaccines is extremely rare (from 1 per 100,000 to 5 per million injections). Symptoms are similar in younger and older adults but they tend to be more severe in the older patients. Adrenaline is the mainstay treatment and should be readily available. A flowchart is proposed to manage anaphylaxis in the older patients.


Subject(s)
Anaphylaxis , COVID-19 , Aged , Anaphylaxis/etiology , Anaphylaxis/prevention & control , COVID-19 Vaccines , Epinephrine , Humans , Male , SARS-CoV-2
7.
Allergy ; 76(8): 2354-2366, 2021 08.
Article in English | MEDLINE | ID: mdl-33730365

ABSTRACT

BACKGROUND: Although there are many asymptomatic patients, one of the problems of COVID-19 is early recognition of the disease. COVID-19 symptoms are polymorphic and may include upper respiratory symptoms. However, COVID-19 symptoms may be mistaken with the common cold or allergic rhinitis. An ARIA-EAACI study group attempted to differentiate upper respiratory symptoms between the three diseases. METHODS: A modified Delphi process was used. The ARIA members who were seeing COVID-19 patients were asked to fill in a questionnaire on the upper airway symptoms of COVID-19, common cold and allergic rhinitis. RESULTS: Among the 192 ARIA members who were invited to respond to the questionnaire, 89 responded and 87 questionnaires were analysed. The consensus was then reported. A two-way ANOVA revealed significant differences in the symptom intensity between the three diseases (p < .001). CONCLUSIONS: This modified Delphi approach enabled the differentiation of upper respiratory symptoms between COVID-19, the common cold and allergic rhinitis. An electronic algorithm will be devised using the questionnaire.


Subject(s)
Asthma , COVID-19 , Common Cold , Rhinitis, Allergic , Consensus , Humans , Rhinitis, Allergic/diagnosis , SARS-CoV-2
8.
Article in English | MEDLINE | ID: mdl-33681484

ABSTRACT

INTRODUCTION: The risk of radiotherapy-associated cardiovascular disease has been a concern for decades in breast cancer survivors. The objective of our study is to evaluate the dosimetric benefit of Deep Inspiratory Breath-hold technique (DIBH) on organs-at-risk (OAR) sparing in left-sided breast cancer radiotherapy and to find out pre-treatment predictors of cardiac doses for guiding patient selection for DIBH. MATERIAL AND METHODS: Pre-radiotherapy planning CT scans were done in Free Breathing (FB) and in DIBH [using Active Breathing Coordinator system (ABC™)] in 31 left sided breast cancer patients. 3DCRT plans were generated for both scans. Comparison of anatomical and dosimetric variables were done using paired t test and correlation was evaluated using Pearson correlation. Linear regression was used to get independent predictors of cardiac sparing and Receiver Operating Characteristic (ROC) curve analysis was done to find out the specific threshold of the predictors. RESULTS: There was a 39.15% reduction in mean heart dose in DIBH compared to FB (2.4 Gy vs 4.01 Gy) (p < 0.001), 19% reduction in maximum Left Anterior Descending (LAD) dose and a 9.9% reduction in ipsilateral lung mean dose (p = 0.036) with DIBH. A significant correlation was observed between reduction in Heart Volume in Field (HVIF) and Maximum Heart Depth (MHD) with reduction in mean heart dose. Reduction in HVIF (ΔHVIF) independently predicted cardiac sparing. CONCLUSION: DIBH leads to significant reduction in OAR doses and is suggested for all patients of left-sided breast cancer undergoing radiotherapy. However, HVIF and MHD predicted for cardiac sparing and threshold criteria of ΔHVIF and ΔMHD may be used by centres with high workload to select patients for DIBH.

9.
Curr Med Chem ; 28(19): 3803-3824, 2021.
Article in English | MEDLINE | ID: mdl-32693756

ABSTRACT

The novel coronavirus (SARS-CoV-2) pandemic has created a global public health emergency. The pandemic is causing substantial morbidity, mortality and significant economic loss. Currently, no approved treatments for COVID-19 are available, and it is likely to takes at least 12-18 months to develop a new vaccine. Therefore, there is an urgent need to find new therapeutics that can be progressed to clinical development as soon as possible. Repurposing regulatory agency-approved drugs and experimental drugs with known safety profiles can provide important repositories of compounds that can be fast-tracked to clinical development. Globally, over 500 clinical trials involving repurposed drugs have been registered, and over 150 have been initiated, including some backed by the World Health Organisation (WHO). This review is intended as a guide to research into small-molecule therapies to treat COVID-19; it discusses the SARS-CoV-2 infection cycle and identifies promising viral therapeutic targets, reports on a number of promising pre-approved small-molecule drugs with reference to over 150 clinical trials worldwide, and offers a perspective on the future of the field.


Subject(s)
COVID-19 , Antiviral Agents/therapeutic use , Drug Repositioning , Humans , Pandemics , SARS-CoV-2
13.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 5588-5591, 2020 07.
Article in English | MEDLINE | ID: mdl-33019244

ABSTRACT

One significant hindrance to effective diagnosis of movement disorders (MDs) and analysis of their progression is the requirement for patients to conduct tests in the presence of a clinician. Here is presented a pilot study for diagnosis of essential tremor (ET), the world's most common MD, through analysis of a tablet- or mobile-based drawing task that may be selected at will, with the spiral- and line-drawing tasks of the Fahn-Tolosa-Marin tremor rating scale serving as our task in this work. This system replaces the need for pen-and-paper drawing tests while permitting advanced quantitative analysis of drawing smoothness, pressure applied, and other measures. Data is securely recorded and stored in the cloud, from which all analysis was conducted remotely. This will enable longitudinal analysis of patient disease progression without the need for excessive clinical visits. Several features were extracted and recursive feature elimination applied to rank the features' individual contribution to our classifier. Maximum cross-validated classification accuracy on a preliminary sample set was 98.3%. Future work will involve collecting healthy subject data from an age-controlled population and extending this diagnostic application to additional conditions, as well as incorporating regression-based symptom severity analysis. This highly promising new technology has the potential to substantially alleviate the demands placed on both clinicians and patients by bringing MD treatment more into line with the era of personalized medicine.


Subject(s)
Essential Tremor , Telemedicine , Essential Tremor/diagnosis , Humans , Pilot Projects , Tablets , Tremor/diagnosis
14.
J Chem Phys ; 153(14): 144102, 2020 Oct 14.
Article in English | MEDLINE | ID: mdl-33086838

ABSTRACT

Explicit description of atomic polarizability is critical for the accurate treatment of inter-molecular interactions by force fields (FFs) in molecular dynamics (MD) simulations aiming to investigate complex electrostatic environments such as metal-binding sites of metalloproteins. Several models exist to describe key monovalent and divalent cations interacting with proteins. Many of these models have been developed from ion-amino-acid interactions and/or aqueous-phase data on cation solvation. The transferability of these models to cation-protein interactions remains uncertain. Herein, we assess the accuracy of existing FFs by their abilities to reproduce hierarchies of thousands of Ca2+-dipeptide interaction energies based on density-functional theory calculations. We find that the Drude polarizable FF, prior to any parameterization, better approximates the QM interaction energies than any of the non-polarizable FFs. Nevertheless, it required improvement in order to address polarization catastrophes where, at short Ca2+-carboxylate distances, the Drude particle of oxygen overlaps with the divalent cation. To ameliorate this, we identified those conformational properties that produced the poorest prediction of interaction energies to reduce the parameter space for optimization. We then optimized the selected cation-peptide parameters using Boltzmann-weighted fitting and evaluated the resulting parameters in MD simulations of the N-lobe of calmodulin. We also parameterized and evaluated the CTPOL FF, which incorporates charge-transfer and polarization effects in additive FFs. This work shows how QM-driven parameter development, followed by testing in condensed-phase simulations, may yield FFs that can accurately capture the structure and dynamics of ion-protein interactions.


Subject(s)
Calcium-Binding Proteins/metabolism , Calcium/metabolism , Dipeptides/metabolism , Calcium/chemistry , Calcium-Binding Proteins/chemistry , Databases, Chemical , Dipeptides/chemistry , Molecular Dynamics Simulation , Protein Binding , Static Electricity , Thermodynamics
15.
Vascul Pharmacol ; 132: 106776, 2020 09.
Article in English | MEDLINE | ID: mdl-32707323

ABSTRACT

Phosphatidylinositol 4,5-bisphosphate (PIP2) acts as substrate and unmodified ligand for Gq-protein-coupled receptor signalling in vascular smooth muscle cells (VSMCs) that is central for initiating contractility. The present work investigated how PIP2 might perform these two potentially conflicting roles by studying the effect of myristoylated alanine-rich C kinase substrate (MARCKS), a PIP2-binding protein, on vascular contractility in rat and mouse mesenteric arteries. Using wire myography, MANS peptide (MANS), a MARCKS inhibitor, produced robust contractions with a pharmacological profile suggesting a predominantly role for L-type (CaV1.2) voltage-gated Ca2+ channels (VGCC). Knockdown of MARCKS using morpholino oligonucleotides reduced contractions induced by MANS and stimulation of α1-adrenoceptors and thromboxane receptors with methoxamine (MO) and U46619 respectively. Immunocytochemistry and proximity ligation assays demonstrated that MARCKS and CaV1.2 proteins co-localise at the plasma membrane in unstimulated tissue, and that MANS and MO reduced these interactions and induced translocation of MARCKS from the plasma membrane to the cytosol. Dot-blots revealed greater PIP2 binding to MARCKS than CaV1.2 in unstimulated tissue, with this binding profile reversed following stimulation by MANS and MO. MANS evoked an increase in peak amplitude and shifted the activation curve to more negative membrane potentials of whole-cell voltage-gated Ca2+ currents, which were prevented by depleting PIP2 levels with wortmannin. This present study indicates for the first time that MARCKS is important regulating vascular contractility and suggests that disinhibition of MARCKS by MANS or vasoconstrictors may induce contraction through releasing PIP2 into the local environment where it increases voltage-gated Ca2+ channel activity.


Subject(s)
Calcium Channels, L-Type/metabolism , Muscle, Smooth, Vascular/metabolism , Myristoylated Alanine-Rich C Kinase Substrate/metabolism , Phosphatidylinositol 4,5-Diphosphate/metabolism , Vasoconstriction , Animals , Calcium Channel Blockers/pharmacology , Calcium Channels, L-Type/drug effects , Mesenteric Artery, Superior/metabolism , Mice, 129 Strain , Muscle, Smooth, Vascular/drug effects , Myristoylated Alanine-Rich C Kinase Substrate/antagonists & inhibitors , Myristoylated Alanine-Rich C Kinase Substrate/genetics , Peptide Fragments/pharmacology , Rats, Wistar , Signal Transduction , Vasoconstriction/drug effects , Vasoconstrictor Agents/pharmacology
16.
J Med Chem ; 63(13): 6941-6958, 2020 07 09.
Article in English | MEDLINE | ID: mdl-32515951

ABSTRACT

It is urgent to find new antibiotic classes with activity against multidrug-resistant (MDR) Gram-negative pathogens as the pipeline of antibiotics is essentially empty. Modified pyrrolobenzodiazepines with a C8-linked aliphatic heterocycle provide a new class of broad-spectrum antibacterial agents with activity against MDR Gram-negative bacteria, including WHO priority pathogens. The structure-activity relationship established that the third ring was particularly important for Gram-negative activity. Minimum inhibitory concentrations for the lead compounds ranged from 0.125 to 2 mg/L for MDR Gram-negative, excluding Pseudomonas aeruginosa, and between 0.03 and 1 mg/L for MDR Gram-positive species. The lead compounds were rapidly bactericidal with >5 log reduction in viable count within 4 h for Acinetobacter baumannii and Klebsiella pneumoniae. The lead compound inhibited DNA gyrase in gel-based assays, with an IC50 of 3.16 ± 1.36 mg/L. This study provides a new chemical scaffold for developing novel broad-spectrum antibiotics which can help replenish the pipeline of antibiotics.


Subject(s)
Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Benzodiazepines/chemistry , Benzodiazepines/pharmacology , Drug Design , Drug Resistance, Multiple/drug effects , Gram-Negative Bacteria/drug effects , Anti-Bacterial Agents/metabolism , Benzodiazepines/metabolism , Cell Line , DNA Gyrase/chemistry , DNA Gyrase/metabolism , Gram-Negative Bacteria/enzymology , Humans , Molecular Docking Simulation , Protein Conformation
17.
Opt Express ; 28(6): 8400-8406, 2020 Mar 16.
Article in English | MEDLINE | ID: mdl-32225466

ABSTRACT

We report on the excitation and polarization preserved propagation of a very large effective-area (Aeff ∼ 2240 µm2) higher-order-mode in an optical fiber. A laser signal operating in the 1 µm wavelength region is transported in a Bessel-like LP0,4 mode over a 10 m long section of the polarization-maintaining higher-order-mode fiber. We observe that the light propagates through the fiber with >10 dB polarization-extinction-ratio as the fiber is coiled into circular loops of 40 cm diameter.

18.
ACS Omega ; 4(25): 20873-20881, 2019 Dec 17.
Article in English | MEDLINE | ID: mdl-31867477

ABSTRACT

The development of new antitubercular agents for the treatment of infections caused by multidrug-resistant (MDR) Mycobacterium tuberculosis is an urgent priority. Pyrrolobenzodiazepines (PBDs) are a promising class of antibacterial agents that were initially discovered and isolated from a range of Streptomyces species. Recently, C8-linked PBD monomers have been shown to work by inhibiting DNA gyrase and have demonstrated activity against M. tuberculosis. However, both PBD monomers and dimers are toxic to eukaryotic cells, limiting their development as antibacterial agents. To eliminate the toxicity associated with PBDs and explore the effect of C8-modification with a known antibacterial agent with the same mechanism of action (i.e., ciprofloxacin, a gyrase inhibitor), we synthesized a C8-linked PBD-ciprofloxacin (PBD-CIP, 3) hybrid. The hybrid compound displayed minimum inhibitory concentration values of 0.4 or 2.1 µg/mL against drug-sensitive and drug-resistant M. tuberculosis strains, respectively. A molecular modeling study showed good interaction of compound 3 with wild-type M. tuberculosis DNA gyrase, suggesting gyrase inhibition as a possible mechanism of action. Compound 3 is a nontoxic combination hybrid that can be utilized as a new scaffold and further optimized to develop new antitubercular agents.

19.
Channels (Austin) ; 13(1): 410-423, 2019 12.
Article in English | MEDLINE | ID: mdl-31603369

ABSTRACT

We have previously provided pharmacological evidence that stimulation of calcium-sensing receptors (CaSR) induces endothelium-dependent relaxations of rabbit mesenteric arteries through activation of heteromeric TRPV4/TRPC1 channels and nitric oxide (NO) production. The present study further investigates the role of heteromeric TRPV4/TRPC1 channels in these CaSR-induced vascular responses by comparing responses in mesenteric arteries from wild-type (WT) and TRPC1-/- mice. In WT mice, stimulation of CaSR induced endothelium-dependent relaxations of pre-contracted tone and NO generation in endothelial cells (ECs), which were inhibited by the TRPV4 channel blocker RN1734 and the TRPC1 blocking antibody T1E3. In addition, TRPV4 and TRPC1 proteins were colocalised at, or close to, the plasma membrane of endothelial cells (ECs) from WT mice. In contrast, in TRPC1-/- mice, CaSR-mediated vasorelaxations and NO generation were greatly reduced, unaffected by T1E3, but blocked by RN1734. In addition, the TRPV4 agonist GSK1016790A (GSK) induced endothelium-dependent vasorelaxations which were blocked by RN1734 and T1E3 in WT mice, but only by RN1734 in TRPC1-/- mice. Moreover, GSK activated cation channel activity with a 6pS conductance in WT ECs but with a 52 pS conductance in TRPC1-/- ECs. These results indicate that stimulation of CaSR activates heteromeric TRPV4/TRPC1 channels and NO production in ECs, which are responsible for endothelium-dependent vasorelaxations. This study also suggests that heteromeric TRPV4-TRPC1 channels may form the predominant TRPV4-containing channels in mouse mesenteric artery ECs. Together, our data further implicates CaSR-induced pathways and heteromeric TRPV4/TRPC1 channels in the regulation of vascular tone.


Subject(s)
Mesenteric Arteries/metabolism , Nitric Oxide/metabolism , Receptors, Calcium-Sensing/metabolism , TRPC Cation Channels/metabolism , TRPV Cation Channels/metabolism , Animals , Calcium/metabolism , Calcium Signaling , Dimerization , Endothelial Cells/metabolism , Female , Male , Mice , Mice, Knockout , Rabbits , Receptors, Calcium-Sensing/genetics , TRPC Cation Channels/chemistry , TRPC Cation Channels/genetics , TRPV Cation Channels/chemistry , TRPV Cation Channels/genetics , Vasodilation
20.
J Biol Chem ; 294(44): 16337-16350, 2019 11 01.
Article in English | MEDLINE | ID: mdl-31527082

ABSTRACT

The calcium-sensing receptor (CaSR) is critical for skeletal development, but its mechanism of action in osteoblasts is not well-characterized. In the central nervous system (CNS), Homer scaffolding proteins form signaling complexes with two CaSR-related members of the G protein-coupled receptor (GPCR) family C, metabotropic glutamate receptor 1 (mGluR1) and mGluR5. Here, we show that CaSR and Homer1 are co-expressed in mineralized mouse bone and also co-localize in primary human osteoblasts. Co-immunoprecipitation experiments confirmed that Homer1 associates with CaSR in primary human osteoblasts. The CaSR-Homer1 protein complex, whose formation was increased in response to extracellular Ca2+, was bound to mechanistic target of rapamycin (mTOR) complex 2 (mTORC2), a protein kinase that phosphorylates and activates AKT Ser/Thr kinase (AKT) at Ser473 siRNA-based gene-silencing assays with primary osteoblasts revealed that both CaSR and Homer1 are required for extracellular Ca2+-stimulated AKT phosphorylation and thereby inhibit apoptosis and promote AKT-dependent ß-catenin stabilization and cellular differentiation. To confirm the role of the CaSR-Homer1 complex in AKT initiation, we show that in HEK-293 cells, co-transfection with both Homer1c and CaSR, but neither with Homer1c nor CaSR alone, establishes sensitivity of AKT-Ser473 phosphorylation to increases in extracellular Ca2+ concentrations. These findings indicate that Homer1 mediates CaSR-dependent AKT activation via mTORC2 and thereby stabilizes ß-catenin in osteoblasts.


Subject(s)
Homer Scaffolding Proteins/metabolism , Mechanistic Target of Rapamycin Complex 2/metabolism , Osteoblasts/metabolism , Proto-Oncogene Proteins c-akt/metabolism , Receptors, Calcium-Sensing/metabolism , beta Catenin/metabolism , Animals , Apoptosis/physiology , Calcium/metabolism , Female , HEK293 Cells , Humans , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Phosphorylation , Receptors, Calcium-Sensing/genetics , Signal Transduction , TOR Serine-Threonine Kinases/metabolism
SELECTION OF CITATIONS
SEARCH DETAIL