Profiling of adenine-derived signaling molecules, cytokinins, in myotubes reveals fluctuations in response to lipopolysaccharide-induced cell stress.

Cytokinins (CTKs) are a diverse collection of evolutionarily conserved adenine-derived signaling molecules classically studied as phytohormones; however, their roles and production have been less studied in mammalian systems. Skeletal muscles are sensitive to cellular cues such as inflammation and in response, alter their secretome to regulate the muscle stem cell and myofiber niche. Using cultured C2C12 muscle cells, we profiled CTK levels to understand (1) whether CTKs are part of the muscle secretome and (2) whether CTKs are responsive to cellular stress.

Aptamer-, heparin- or cocktail-based inhibition of S1-ACE2 protein complexes.

The Spike protein (S1) from the Severe acute respiratory syndrome 2 virus binds to angiotensin converting enzyme 2 (ACE2) receptor to initiate infection. Hence, antiviral therapeutic targeting the S1-ACE2 interface is of interest. Herein, we compare the inhibition efficacy of an aptamer to heparin or their cocktail, against wild-type (WT), Omicron, Delta, and Lambda S1-ACE2 complexes.

Role of Triggers on the Structural and Functional Facets of TAR DNA-binding Protein 43.

Nuclear TAR DNA-binding protein 43 (TDP-43) mitigates cellular function, but the dynamic nucleus-cytoplasm shuttling of TDP-43 is disrupted in diseases, such as Amyotrophic Lateral Sclerosis (ALS). The polymorphic nature of the TDP-43 structures in vitro and in vivo is a result of environmental factors leading to the protein pathogenesis. Once the triggers which mitigate TDP-43 biochemistry are identified, new therapies can be developed.

Selective detection of nitrotyrosine using dual-fluorescent carbon dots.

The post-translational modification of amino acid plays a critical role in normal and diseased biological states. Specifically, nitrotyrosine (nTyr) has been linked to diseases, including neurodegeneration, among others. Hence, alternative methods are required for detection and differentiation of nTyr from other structurally similar analogues, such as Tyrosine (Tyr) or phosphotyrosine (pTyr).

Functionalized resorcinarenes effectively disrupt the aggregation of αA66-80 crystallin peptide related to cataracts.

Cataracts, an eye lens clouding disease, are debilitating and while operable, remain without a cure. αA66-80 crystallin peptide abundant in cataracted eye lenses contributes to aggregation of αA-crystallin protein leading to cataracts. Inspired by the versatility of macrocycles and programmable guest selectivity through discrete functionalizations, we report on three water-soluble ionic resorcinarene receptors (, , and ) that disrupt the aggregation of αA66-80 crystallin peptide.

Phosphorylated TAR DNA-binding protein-43: Aggregation and antibody-based inhibition.

TAR DNA-binding protein-43 (TDP-43) pathology, including fibrillar aggregates and mutations, develops in amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration (FTLD) and limbic-predominant age-related TDP-43 encephalopathy (LATE). Hyperphosphorylation and aggregation of TDP-43 contribute to pathology and are viable therapeutic targets for ALS. In vivo inhibition of TDP-43 aggregation was evaluated using anti-TDP-43 antibodies with promising outcomes.

The multifunctional dopamine D/D receptor agonists also possess inhibitory activity against the full-length tau441 protein aggregation.

Neurodegeneration leads to variety of diseases which are linked to aberrant protein or peptide aggregation, as a one possible mechanism. Hence, small drug molecules targeting aggregation are of interest. Tau protein aggregation is one of the biomarkers of neurodegenerative diseases and is a viable drug target.

A dip-and-read optical aptasensor for detection of tau protein.

Neurodegeneration currently remains without a differential diagnosis or cure. Tau protein is one of the biomarkers of neurodegenerative diseases commonly known as tauopathies. Tau protein plays an integral role in stabilizing microtubules and cell structure; however, due to post-translational modifications, tau protein undergoes self-assembly into cytotoxic structures and is co-localized intra- and extracellularly.

Functionalization of Ruthenium(II)(η -p-cymene)(3-hydroxy-2-pyridone) Complexes with (Thio)Morpholine: Synthesis and Bioanalytical Studies.

Hydroxypyr(id)ones constitute an emerging platform for the design of drug molecules, owing to their favorable biocompatibility and toxicity profiles. Herein, [Ru (η -p-cymene)] complexes with 3-hydroxy-2-pyridinone functionalized with morpholine and thiomorpholine, as a means often used in medicinal chemistry to alter the physicochemical properties of drug compounds, are reported. The compounds underwent hydrolysis of the Ru-Cl bond and the aqua species were stable for up to 48 h in aqueous solution, as observed by H NMR spectroscopy and ESI-MS.

A Bioorganometallic Approach to Study Histidine Kinase Autophosphorylations.

Auto-phosphorylation of bacterial histidine kinases PhoR, PhoQ, and EnvZ has been investigated using adenosine-5'-[γ-ferrocene] triphosphate (Fc-ATP) as a cosubstrate for the first time. The study has been carried out in solution and on surface. Results from biochemical multiplex assay and surface electrochemical/optical methods are consistent, which successfully demonstrates that Fc-ATP is an efficient cosubstrate for histidine kinase auto-phosphorylations.

Effects of antibodies to phosphorylated and non-phosphorylated tau on in vitro tau phosphorylation at Serine-199: Preliminary report.

Unlabelled: Phosphorylation of multiple amino acids on tau protein ("hyperphosphorylation") is required for the development of tau pathology in Alzheimer's disease. Administration of anti-tau antibodies to transgenic "tauopathy mice" has been shown to reduce their tau pathology but the mechanisms responsible are unclear. To examine the effects of anti-tau antibodies on tau phosphorylation, we used western blots to study the effects of three antibodies to phosphorylated tau (pTau), namely anti-pTau S199, T231, and S396, and three antibodies to non-phosphorylated tau on in vitro phosphorylation of recombinant human tau-441 at S199.

Clickable 5'-γ-ferrocenyl adenosine triphosphate bioconjugates in kinase-catalyzed phosphorylations.

Clickable co-substrate: A tri-functional 5'-γ-ferrocenyl adenosine triphosphate (Fc-ATP) derivative containing a clickable site was synthesized. This compound is an effective co-substrate in kinase-catalyzed phosphorylation reactions, which can be detected by both electrochemical and immunoassay detection methods. The clickable reaction site makes direct modification possible, which greatly expands its application.

Electron transfer in peptides.

In this review, we discuss the factors that influence electron transfer in peptides. We summarize experimental results from solution and surface studies and highlight the ongoing debate on the mechanistic aspects of this fundamental reaction. Here, we provide a balanced approach that remains unbiased and does not favor one mechanistic view over another.

Effects of tau domain-specific antibodies and intravenous immunoglobulin on tau aggregation and aggregate degradation.

Tau pathology, including neurofibrillary tangles, develops in Alzheimer's disease (AD). The aggregation and hyperphosphorylation of tau are potential therapeutic targets for AD. Administration of anti-tau antibodies reduces tau pathology in transgenic "tauopathy" mice; however, the optimal tau epitopes and conformations to target are unclear.

A protein-based electrochemical biosensor for detection of tau protein, a neurodegenerative disease biomarker.

A protein-based electrochemical biosensor was developed for detection of tau protein aimed towards electrochemically sensing misfolding proteins. The electrochemical assay monitors tau-tau binding and misfolding during the early stage of tau oligomerization. Electrochemical impedance spectroscopy was used to detect the binding event between solution tau protein and immobilized tau protein (tau-Au), acting as a recognition element.

Electrochemical detection of the Fc-STAT3 phosphorylation and STAT3-Fc-STAT3 dimerization and inhibition.

Signal transducer and activator of transcription 3 (STAT3) protein is involved in regulatory functions in cell proliferation, differentiation and survival, and is linked to cancer phenotype and tumorigenesis. Towards developing new methodologies for screening STAT3 interactions, the electrochemical method based on the use of redox active protein was proposed. The electrochemical signal, due to the redox (ferrocene)-labeled STAT3 protein immobilized on a gold surface, was modulated due to protein dimerization with the unlabeled STAT3 molecule.

Probing copper/tau protein interactions electrochemically.

Alzheimer's disease (AD) is a neurodegenerative disorder that is characterized by peptide and protein misfolding and aggregation, in part due to the presence of excess metal ions such as copper(II) [Cu(II)]. Recently, the brain levels of Cu(II) complexes in vivo were linked to the oxidative stress in neurodegenerative disorders, including AD. Amyloid β-peptide (Aβ), found outside neuronal cells, has been investigated extensively in connection with Cu(II) ion toxicity; however, the effects of metallation on tau are less known.

Electrochemical investigations into kinase-catalyzed transformations of tau protein.

The formation of neurofibrillary tangles by hyperphosphorylated tau is a well-recognized hallmark of Alzheimer's disease. Resulting from malfunctioning protein kinases, hyperphosphorylated tau is unable to bind microtubules properly, causing it to self-associate and aggregate. The effects of tau phosphorylation on tau conformation and aggregation are still largely unexplored.

Surface plasmon resonance imaging of amyloid-β aggregation kinetics in the presence of epigallocatechin gallate and metals.

A number of human protein misfolding disorders, including Alzheimer's disease (AD), are closely related to the accumulation of β-sheet-rich amyloid fibrils or aggregates. Neuronal toxicity in AD has been linked to the interactions of amyloid-β (Aβ) with metals, especially Zn(2+), Cu(2+), and Fe(3+), which leads to the production of reactive oxygen species. Nucleation-dependent Aβ aggregation, or "seeding", is thought to propagate fibril formation.

Structure-activity relationships of targeted RuII(η6-p-cymene) anticancer complexes with flavonol-derived ligands.

RuII(arene) complexes have been shown to be promising anticancer agents, capable of overcoming major drawbacks of currently used chemotherapeutics. We have synthesized RuII(η6-arene) compounds carrying bioactive flavonol ligands with the aim to obtain multitargeted anticancer agents. To validate this concept, studies on the mode of action of the complexes were conducted which indicated that they form covalent bonds to DNA, have only minor impact on the cell cycle, but inhibit CDK2 and topoisomerase IIα in vitro.

Electrochemical investigations of Tau protein phosphorylations and interactions with Pin1.

Phosphorylation of Tau by the protein kinase GSK-3β was monitored by electrochemical impedance spectroscopy of immobilized Tau on gold surfaces. As a result of Tau phosphorylation, the film resistance decreases significantly due to conformational changes and reorganization of the immobilized phosphorylated Tau (pTau) protein, which in turn enables the interactions of pTau with the peptidyl-prolyl cis/trans isomerase, Pin1. Interactions are specific to phospho-Ser (pSer) and phospho-Thr (pThr) residues of pTau.

Versatile strategy for biochemical, electrochemical and immunoarray detection of protein phosphorylations.

Protein kinases catalyze the phosphorylation of cellular proteins involved in the regulation of many cellular processes and have emerged as promising targets for the treatment of several diseases. Conventional assays to monitor protein kinase activity are limited because they typically rely on transfer of radioactive phosphate or phospho-specific antibodies that recognize specific substrates or sequence motifs. To overcome the limitations of conventional assays, we have developed a versatile approach based on transfer of ferrocene-phosphate that can be readily monitored using electrochemical detection or detection with antiferrocene antibodies in an immunoarray format.

Hierarchical organization of ferrocene-peptides.

Hierarchical self-assembly of disubstituted ferrocene (Fc)-peptide conjugates that possess Gly-Val-Phe and Gly-Val-Phe-Phe peptide substituents leads to the formation of nano- and micro-sized assemblies. Hydrogen-bonding and hydrophobic interactions provide directionality to the assembly patterns. The self-assembling behavior of these compounds was studied in solution by using (1)H NMR and circular dichroism (CD) spectroscopies.

Electrochemical investigations into Tau protein phosphorylations.

Hyperphosphorylation of Tau, a protein that stabilizes microtubules, leads to the breakdown of the microtubular structure and ultimately to the formation of neurofibrillar tangles within neurons. Here, we report monitoring of Tau phosphorylations electrochemically, using Tau protein films chemically linked to gold surfaces and 5'-γ-ferrocenyl (Fc) adenosine triphosphate (Fc-ATP) as a co-substrate. Fc-phosphorylation reactions of Tau are explored using the three protein kinases, glycogen synthase kinase (GSK-3β), sarcoma (Src)-related kinase, and protein kinase A (PKA), which catalyze Fc-phosphorylation of different residues and regions within Tau.

Electrochemical screening of the indole/quinolone derivatives as potential protein kinase CK2 inhibitors.

An electrochemical method based on the bioorganometallic Fc-ATP cosubstrate for kinase-catalyzed phosphorylation reactions was used for monitoring casein kinase 2 (CK2) phosphorylations in the absence and presence of five indole/quinolone-based potential inhibitors. Fc-phosphorylation of immobilized peptide RRRDDDSDDD on Au surfaces resulted in a current density at approximately 460 ± 10 mV. An electrochemical redox signal was significantly decreased in the presence of inhibitors.