Divergent Biochemical Properties and Disparate Impact of Arrhythmogenic Calmodulin Mutations on Zebrafish Cardiac Function.

Calmodulin (CaM) is a ubiquitous, small cytosolic calcium (Ca)-binding sensor that plays a vital role in many cellular processes by binding and regulating the activity of over 300 protein targets. In cardiac muscle, CaM modulates directly or indirectly the activity of several proteins that play a key role in excitation-contraction coupling (ECC), such as ryanodine receptor type 2 (RyR2), l-type Ca (Ca1.2), sodium (NaV1.

Development of Recombinant PLC-Zeta Protein as a Therapeutic Intervention for the Clinical Treatment of Oocyte Activation Failure.

The sperm-specific phospholipase C zeta (PLCζ) protein is widely considered as the predominant physiological stimulus for initiating the Ca release responsible for oocyte activation during mammalian fertilization. The increasing number of genetic and clinical reports that directly link PLCζ defects and/or deficiencies with oocyte activation failure (OAF) necessitates the use of a powerful therapeutic intervention to overcome such cases of male factor infertility. Currently, in vitro fertilization (IVF) clinics treat OAF cases after intracytoplasmic sperm injection (ICSI) with Ca ionophores.

Biochemical and structural impact of two novel missense mutations in cystathionine β-synthase gene associated with homocystinuria.

Homocystinuria is a rare disease caused by mutations in the CBS gene that results in a deficiency of cystathionine β-synthase (CBS). CBS is an essential pyridoxal 5'-phosphate (PLP)-dependent enzyme in the transsulfuration pathway, responsible for combining serine with homocysteine to produce cystathionine, whose activity is enhanced by the allosteric regulator S-adenosylmethionine (SAM). CBS also plays a role in generating hydrogen sulfide (H2S), a gaseous signaling molecule with diverse regulatory functions within the vascular, nervous, and immune systems.

BRCA1 and Its Vulnerable C-Terminal BRCT Domain: Structure, Function, Genetic Mutations and Links to Diagnosis and Treatment of Breast and Ovarian Cancer.

The is a tumor suppressor gene that encodes for the BRCA1 protein, which plays a vital role in DNA repair, cell cycle regulation, and the maintenance of genomic stability. The BRCA1 protein interacts with a variety of other proteins that play essential roles in gene regulation and embryonic development. It is a large protein composed of multiple domains.

Arrhythmia-Associated Calmodulin E105A Mutation Alters the Binding Affinity of CaM to a Ryanodine Receptor 2 CaM-Binding Pocket.

Calmodulin (CaM) is a small, multifunctional calcium (Ca)-binding sensor that binds and regulates the open probability of cardiac ryanodine receptor 2 (RyR2) at both low and high cytosolic Ca concentrations. Recent isothermal titration calorimetry (ITC) studies of a number of peptides that correspond to different regions of human RyR2 showed that two regions of human RyR2 (3584-3602aa and 4255-4271aa) bind with high affinity to CaM, suggesting that these two regions might contribute to a putative RyR2 intra-subunit CaM-binding pocket. Moreover, a previously characterized de novo long QT syndrome (LQTS)-associated missense CaM mutation (E105A) which was identified in a 6-year-old boy, who experienced an aborted first episode of cardiac arrest revealed that this mutation dysregulates normal cardiac function in zebrafish by a complex mechanism that involves alterations in both CaM-Ca and CaM-RyR2 interactions.

Metal-binding cyclodextrins: Synthesis and complexation with Zn and Ga cations towards antimicrobial applications.

Highly resistant bacteria producing metallo-β-lactamases (MBLs) to evade β-lactam antibiotics, constitute a major cause of life-threatening infections world-wide. MBLs exert their hydrolytic action via Zn cations in their active center. Presently, there are no approved drugs to target MBLs and combat the associated antimicrobial resistance (AMR).

ApoM binds endotoxin contributing to neutralization and clearance by High Density Lipoprotein.

Background: HDL possesses anti-inflammatory properties, however, the exact mechanism is not fully understood. Endotoxin is a potent inducers of TLR4 signaling, leading to inflammatory mediators' release. It has been estimated that TLR4 recognizes about 5% of circulating lipopolysaccharide whereas 95% is cleared by plasma lipoproteins, mainly HDL.

Life-threatening arrhythmogenic CaM mutations disrupt CaM binding to a distinct RyR2 CaM-binding pocket.

Calmodulin (CaM) modulates the activity of several proteins that play a key role in excitation-contraction coupling (ECC). In cardiac muscle, the major binding partner of CaM is the type-2 ryanodine receptor (RyR2) and altered CaM binding contributes to defects in sarcoplasmic reticulum (SR) calcium (Ca) release. Many genetic studies have reported a series of CaM missense mutations in patients with a history of severe arrhythmogenic cardiac disorders.

SPERM FACTORS AND EGG ACTIVATION: The structure and function relationship of sperm PLCZ1.

In 2002, sperm-specific phospholipase C zeta1 (PLCZ1) was discovered and through these 20 years, it has been established as the predominant sperm oocyte-activating factor. PLCZ1 cRNA expression or direct protein microinjection into mammalian oocytes triggers calcium (Ca2+) oscillations indistinguishable from those observed at fertilization. The imperative role of PLCZ1 in oocyte activation is revealed by the vast number of human mutations throughout the PLCZ1 gene that have been identified and directly linked with certain forms of male infertility due to oocyte activation deficiency.

Essential Role of Sperm-Specific PLC-Zeta in Egg Activation and Male Factor Infertility: An Update.

Sperm-specific phospholipase C zeta (PLCζ) is widely considered to be the physiological stimulus responsible for generating calcium (Ca) oscillations that induce egg activation and early embryonic development during mammalian fertilization. In the mammalian testis, PLCζ expression is detected at spermiogenesis following elongated spermatid differentiation. Sperm-delivered PLCζ induces Ca release via the inositol 1,4,5-trisphosphate (InsP) signaling pathway.

Arrhythmogenic calmodulin E105A mutation alters cardiac RyR2 regulation leading to cardiac dysfunction in zebrafish.

Calmodulin (CaM) is a universal calcium (Ca )-binding messenger that regulates many vital cellular events. In cardiac muscle, CaM associates with ryanodine receptor 2 (RyR2) and regulates excitation-contraction coupling. Mutations in human genes CALM1, CALM2, and CALM3 have been associated with life-threatening heart disorders, such as long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia.

Orientation of Biotin-Binding Sites in Streptavidin Adsorbed onto the Surface of Polythiophene Films.

The orientation of biotin-binding sites of streptavidin adsorbed to thin films of three polythiophenes (PTs), namely, regioregular poly(3-hexylthiophene) (RP3HT), regiorandom poly(3-butylthiophene) (P3BT), and poly(3,3‴-didodecylquaterthiophene) (PQT12), has been investigated. Polymer films were examined prior to and after protein adsorption with atomic force microscopy and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Principal component analysis (PCA) applied to ToF-SIMS data revealed subtle changes in surface chemistry of polymer films and orientation of adsorbed streptavidin.

Hypertrophic cardiomyopathy-linked variants of cardiac myosin-binding protein C3 display altered molecular properties and actin interaction.

The most common inherited cardiac disorder, hypertrophic cardiomyopathy (HCM), is characterized by thickening of heart muscle, for which genetic mutations in cardiac myosin-binding protein C3 () gene, is the leading cause. Notably, patients with HCM display a heterogeneous clinical presentation, onset and prognosis. Thus, delineating the molecular mechanisms that explain how disparate variants lead to HCM is essential for correlating the impact of specific genotypes on clinical severity.

Designed positively charged cyclodextrin hosts with enhanced binding of penicillins as carriers for the delivery of antibiotics: The case of oxacillin.

In an effort to identify the optimal cyclodextrin (CD) host for delivery of penicillins to mammalian cells that will also offer protection against β-lactamase-induced hydrolysis, nuclear magnetic resonance (NMR) spectroscopy and isothermal titration calorimetry (ITC) have been employed to study the inclusion complexes formed in aqueous solution between designed CD derivatives and two aminopenicillins, ampicillin and amoxicillin, and two antistaphylococcal penicillins, methicillin and oxacillin. Anionic and cationic thioether-substituted-β- and -γCD derivatives were thus synthesized and compared with the neutral, parent CDs for complexation with the penicillins. The synthesized derivatives were shown to present ∼20% elongated cavity space in solution.

Mutations in PLCδ1 associated with hereditary leukonychia display divergent PIP2 hydrolytic function.

Hereditary leukonychia is a rare genetic nail disorder characterized by distinctive whitening of the nail plate of all 20 nails. Hereditary leukonychia may exist as an isolated feature, or in simultaneous occurrence with other cutaneous or systemic pathologies. Associations between hereditary leukonychia and mutations in the gene encoding phospholipase C delta-1 (PLCδ1) have previously been identified.

Biodosimetry for High-Dose Exposures Based on Dicentric Analysis in Lymphocytes Released from the G2-Block by Caffeine.

High-dose assessments using the conventional dicentric assay are essentially restricted to doses up to 5 Gy and only to lymphocytes that succeed to proceed to first post-exposure mitosis. Since G2-checkpoint activation facilitates DNA damage recognition and arrest of damaged cells, caffeine is used to release G2-blocked lymphocytes overcoming the mitotic index and dicentric yield saturation problems, enabling thus dicentric analysis even at high-dose exposures. Using the fluorescence in situ hybridization technique with telomere and centromere peptide nucleic acid probes, the released lymphocytes, identified as metaphases with decondensed chromosomes following 1.

Comparative Experimental and Computational Study of Monoalkyl Chain Phosphatidylcholine-Containing Thermoresponsive Liposomes.

Liposomes containing lysophospholipids are intensively studied as drug delivery systems that are stable at normal body temperature but exhibit fast release of their drug load at slightly elevated temperatures. In this study, the stability and release properties of dipalmitoylglycerophosphocholine (DPPC)-based liposomes incorporating the commonly used lysophosphatidylocholine (lyso-PC), and a series of monoalkyl chain ether-linked phosphatidylcholine, i.e.

Distinctive malfunctions of calmodulin mutations associated with heart RyR2-mediated arrhythmic disease.

Calmodulin (CaM) is a cytoplasmic calcium sensor that interacts with the cardiac ryanodine receptor (RyR2), a large Ca(2+) channel complex that mediates Ca(2+) efflux from the sarcoplasmic reticulum (SR) to activate cardiac muscle contraction. Direct CaM association with RyR2 is an important physiological regulator of cardiac muscle excitation-contraction coupling and defective CaM-RyR2 protein interaction has been reported in cases of heart failure. Recent genetic studies have identified CaM missense mutations in patients with a history of severe cardiac arrhythmogenic disorders that present divergent clinical features, including catecholaminergic polymorphic ventricular tachycardia (CPVT), long QT syndrome (LQTS) and idiopathic ventricular fibrillation (IVF).

Altered RyR2 regulation by the calmodulin F90L mutation associated with idiopathic ventricular fibrillation and early sudden cardiac death.

Calmodulin (CaM) association with the cardiac muscle ryanodine receptor (RyR2) regulates excitation-contraction coupling. Defective CaM-RyR2 interaction is associated with heart failure. A novel CaM mutation (CaM(F90L)) was recently identified in a family with idiopathic ventricular fibrillation (IVF) and early onset sudden cardiac death.

From nucleobases to nucleolipids: an ITC approach on the thermodynamics of their interactions in aqueous solutions.

Hybrid constructions based on nucleosides and lipophilic components, known as nucleolipids, have become an extremely interesting class of molecules, especially for their potential biomedical applications. In this matter, it seemed important to define the nature and estimate the strength of their interaction with polynucleotides by different ways. We report in this work a systematic investigation through isothermal titration calorimetry of the thermodynamics of the association and dissociation of adenine and thymine derivatives, not previously performed.

CdSe nanoparticles dispersed in ferroelectric smectic liquid crystals: effects upon the smectic order and the smectic-A to chiral smectic-C phase transition.

Spherical CdSe nanoparticles, surface-treated with oleylamine and tri-octylphosphine, dispersed in ferroelectric liquid crystals, can efficiently target disclination lines, substantially altering the macroscopic properties of the host compound. Here we present an ac calorimetry and x-ray diffraction study demonstrating that for a large range of nanoparticle concentrations the smectic-A layer thickness increases monotonically. This provides evidence for enhanced accumulation of nanoparticles at the smectic layers.

ATP interacts with the CPVT mutation-associated central domain of the cardiac ryanodine receptor.

Background: This study was designed to determine whether the cardiac ryanodine receptor (RyR2) central domain, a region associated with catecholamine polymorphic ventricular tachycardia (CPVT) mutations, interacts with the RyR2 regulators, ATP and the FK506-binding protein 12.6 (FKBP12.6).

Studies on the essential intramolecular interaction between the A1 and A2 domains of von Willebrand factor.

Haemostasis depends on the balanced participation of von Willebrand factor (vWF), a large multimeric and multidomain glycoprotein with essential role during the initial steps of blood clotting. Mature vWF circulates in plasma with the form of multimers comprised of several domains with diverse functions. More specifically, the A1 domain of vWF plays crucial role in haemostasis, regulating the mechanism of platelet adhesion in sites of vascular injury while A2 domain regulates the normal turnover of vWF.