Assay Of Protein Kinase Activity Research Articles

Sex-specific cardiovascular remodeling leads to a divergent sex-dependent development of heart failure in aged hypertensive rats

IntroductionThe prevalence of heart failure with preserved ejection fraction (HFpEF) is continuously rising and predominantly affects older women often hypertensive and/or obese or diabetic. Indeed, there is evidence on sex differences in the development of HF. Hence, we studied cardiovascular performance dependent on sex and age as well as pathomechanisms on a cellular and molecular level.MethodsWe studied 15-week- and 1-year-old female and male hypertensive transgenic rats carrying the mouse Ren-2 renin gene (TG) and compared them to wild-type (WT) controls at the same age. We tracked blood pressure and cardiac function via echocardiography. After sacrificing the 1-year survivors we studied vascular smooth muscle and endothelial function. Isolated single skinned cardiomyocytes were used to determine passive stiffness and Ca2+-dependent force. In addition, Western blots were applied to analyse the phosphorylation status of sarcomeric regulatory proteins, titin and of protein kinases AMPK, PKG, CaMKII as well as their expression. Protein kinase activity assays were used to measure activities of CaMKII, PKG and angiotensin-converting enzyme (ACE).ResultsTG male rats showed significantly higher mortality at 1 year than females or WT male rats. Left ventricular (LV) ejection fraction was specifically reduced in male, but not in female TG rats, while LV diastolic dysfunction was evident in both TG sexes, but LV hypertrophy, increased LV ACE activity, and reduced AMPK activity as evident from AMPK hypophosphorylation were specific to male rats. Sex differences were also observed in vascular and cardiomyocyte function showing different response to acetylcholine and Ca2+-sensitivity of force production, respectively cardiomyocyte functional changes were associated with altered phosphorylation states of cardiac myosin binding protein C and cardiac troponin I phosphorylation in TG males only. Cardiomyocyte passive stiffness was increased in TG animals. On a molecular level titin phosphorylation pattern was altered, though alterations were sex-specific. Thus, also the reduction of PKG expression and activity was more pronounced in TG females. However, cardiomyocyte passive stiffness was restored by PKG and CaMKII treatments in both TG sexes.ConclusionHere we demonstrated divergent sex-specific cardiovascular adaptation to the over-activation of the renin-angiotensin system in the rat. Higher mortality of male TG rats in contrast to female TG rats was observed as well as reduced LV systolic function, whereas females mainly developed HFpEF. Though both sexes developed increased myocardial stiffness to which an impaired titin function contributes to a sex-specific molecular mechanism. The functional derangements of titin are due to a sex-specific divergent regulation of PKG and CaMKII systems.

Plasmonic nanoparticle-assisted single-molecule dynamic binding for protein kinase activity digital counting.

In this work, we design a new approach for digital counting-based protein kinase activity assay by using plasmonic nanoparticle-assisted single-molecule dynamic binding. This method breaks the concentration-dependent limitation in single-molecule detection and displays good selectivity and sensitivity with a detection limit as low as 0.0001 U mL-1 for the protein kinase A (PKA) assay, which would find broad applications in drug screening and medical investigations.

The OsBDR1-MPK3 module negatively regulates blast resistance by suppressing the jasmonate signaling and terpenoid biosynthesis pathway.

Receptor-like kinases (RLKs) may initiate signaling pathways by perceiving and transmitting environmental signals to cellular machinery and play diverse roles in plant development and stress responses. The rice genome encodes more than one thousand RLKs, but only a small number have been characterized as receptors for phytohormones, polypeptides, elicitors, and effectors. Here, we screened the function of 11 RLKs in rice resistance to the blast fungus Magnaporthe oryzae (M. oryzae) and identified a negative regulator named BDR1 (Blast Disease Resistance 1). The expression of BDR1 was rapidly increased under M. oryzae infection, while silencing or knockout of BDR1 significantly enhanced M. oryzae resistance in two rice varieties. Protein interaction and kinase activity assays indicated that BDR1 directly interacted with and phosphorylated mitogen-activated kinase 3 (MPK3). Knockout of BDR1 compromised M. oryzae-induced MPK3 phosphorylation levels. Moreover, transcriptome analysis revealed that M. oryzae-elicited jasmonate (JA) signaling and terpenoid biosynthesis pathway were negatively regulated by BDR1 and MPK3. Mutation of JA biosynthetic (allene oxide cyclase (AOC)/signaling (MYC2) genes decreased rice resistance to M. oryzae. Besides diterpenoid, the monoterpene linalool and the sesquiterpene caryophyllene were identified as unique defensive compounds against M. oryzae, and their biosynthesis genes (TPS3 and TPS29) were transcriptionally regulated by JA signaling and suppressed by BDR1 and MPK3. These findings demonstrate the existence of a BDR1-MPK3 cascade that negatively mediates rice blast resistance by affecting JA-related defense responses.

An Integral Recognition and Signaling for Electrochemical Assay of Protein Kinase Activity and Inhibitor by Reduced Graphene Oxide-Polydopamine-Silver Nanoparticle-Ti4+ Nanocomposite.

A novel electrochemical biosensing method for protein kinase (PKA) activity was demonstrated by using a reduced graphene oxide-polydopamine-silver nanoparticle-Ti4+ (rGO-PDA-AgNPs-Ti4+) nanocomposite. The obtained nanocomposite possessed an integral capability for phosphopeptide recognition and signal readout. The polydopamine modified reduced graphene oxide (rGO-PDA) was firstly prepared based on a self-polymerization method of dopamine. The silver ions were adsorbed onto polydopamine (PDA) layer and directly reduced into silver nanoparticles (AgNPs), which was used for electrochemical signal reporting. Then, the Ti4+ cations were attached onto the PDA layer for phosphopeptide recognition according to the strong coordination ability of PDA with Ti4+ and phosphate group. The prepared rGO-PDA-AgNPs-Ti4+ nanocomposites were characterized with different methods. The developed rGO-PDA-AgNPs-Ti4+ nanocomposites were then employed for electrochemical analysis of PKA-catalyzed kemptide phosphorylation. The sensitive detection toward PKA activity was realized with an experimental detection limit of about 0.01 U/mL. It may be also extended for the inhibitor evaluation. Thus, it provided a facile and sensitive means for electrochemical analysis of PKA activity and inhibitor screening.

Electrochemical assay of protein kinase activity based on the Fe3O4@PNE-Ti4+ functionalized PDMS microchip

A new strategy for the sensitive assay of protein kinase activity has been constructed using Fe3O4@PNE-Ti4+ nanocomposite as stationary phase in microchip electrophoresis. Through the self-polymerization of norepinephrine in weak alkaline solution, a thin poly(norepinephrine) (PNE) film can be spontaneously formed on the surface of Fe3O4 nanoparticles (NPs) to produce Fe3O4@PNE NPs. Due to the good magnetic property, Fe3O4@PNE NPs can be easily fixed in poly(dimethylsiloxane) (PDMS) channel under external magnetic field. On the other hand, the catechol hydroxyl groups in PNE can chelate Ti4+ to form Fe3O4@PNE-Ti4+ in PDMS channel. When peptides are phosphorylated by protein kinase A (PKA) in the presence of adenosine 5′-triphosphate (ATP), the Fe3O4@PNE-Ti4+ packed in PDMS channels can specifically coordinate with the phosphorylated sites of phosphopeptides, but the non-phosphorylated peptides cannot bind with Ti4+. Thus, the retention time of the phosphorylated peptides in the Fe3O4@PNE-Ti4+ packed PDMS channel was increased, and phosphorylated peptides and non-phosphorylated peptides can be separated successfully. Due to the high loading of Ti4+ on the Fe3O4@PNE, this strategy can be used for the enrichment of phosphorylated peptides and electrochemical assay of PKA activity. This method can also be used for quantitative analysis of PKA activity in cell lysate, indicating its potential application in clinical diagnosis.

Proteomics insights into the effects of MSTN on muscle glucose and lipid metabolism in genetically edited cattle

The molecular mechanism underlying myostatin (MSTN)-regulated metabolic cross-talk remains poorly understood. In this study, we performed comparative proteomic and phosphoproteomic analyses of gluteus muscle tissues from MSTN-/- transgenic cattle using a shotgun-based tandem mass tag (TMT) 6-plex labeling method to explore the signaling pathway of MSTN in metabolic cross-talk and cellular metabolism during muscle development. A total of 72 differentially expressed proteins (DEPs) and 36 differentially expressed phosphoproteins (DEPPs) were identified in MSTN-/- cattle compared to wild-type cattle. Bioinformatics analyses showed that MSTN knockout increased the activity of many key enzymes involved in fatty acid β-oxidation and glycolysis processes in cattle. Furthermore, comprehensive pathway analyses and hypothesis-driven AMP-activated protein kinase (AMPK) activity assays suggested that MSTN knockout triggers the activation of AMPK signaling pathways to regulate glucose and lipid metabolism by increasing the AMP/ATP ratio. Our results shed new light on the potential regulatory mechanism of MSTN associated with metabolic cross-talk in muscle development, which can be used in animal breeding to improve meat production in livestock animals, and can also provide valuable insight into treatments for obesity and diabetes mellitus in humans.

Reduced Graphene Oxide-Zirconium Dioxide-Thionine Nanocomposite Integrating Recognition, Amplification, and Signaling for an Electrochemical Assay of Protein Kinase Activity and Inhibitor Screening.

Protein kinase activity analysis is essential and important for elucidation of many fundamental biological processes, disease diagnosis, and drug discovery. Herein, a novel electrochemical biosensing method for protein kinase (PKA) activity was demonstrated by the use of a reduced graphene oxide-zirconium dioxide-thionine (rGO-ZrO2-Thi) nanocomposite, which interestingly served as an integral phosphopeptide-recognizing, signal amplifying and reporting platform. The ZrO2 nanoparticle-decorated reduced graphene oxide (rGO-ZrO2) was first prepared by a hydrothermal reaction route, and then the thionine was conjugated onto the rGO surface via π-π stacking as an excellent electrochemical probe. The prepared rGO-ZrO2-Thi nanocomposites were well-characterized by various techniques. With the full advantage of specific recognition of ZrO2 nanoparticles for the phosphate group, signal amplification, and transduction of abundant thionines onto the rGO surface, and excellent conductivity of rGO, the rGO-ZrO2-Thi nanocomposite endowed a label-free and one-step electrochemical analysis of kemptide phosphorylation catalyzed by PKA. The detection limit for PKA activity was experimentally achieved as 0.005 U/mL, which was evidently lower than most of the reported methods. The proposed sensing strategy could be also applied for an efficient inhibitor evaluation. Therefore, it offered an excellent pathway for a generic and sensitive electrochemical assay of PKA activity and inhibitor.

A fluorometric method for the assay of protein kinase activity

Protein kinases constitute one of the largest protein families in nature. Current methods to assay their activity involve the use of radioactive ATP or very expensive reagents. In this work, we developed a highly sensitive, cost-effective and straightforward protocol to measure protein kinase activity using a microplate layout. Released ADP is converted into NAD+, which is quantified by its fluorescent properties after alkaline treatment (linear range 0-10 nmol ADP). To validate our protocol, we characterized a recombinant calcium-dependent protein kinase from potato. Overall, this tool represents a critical step forward in the functional characterization of protein kinases.

Aptamer based electrochemical assay for protein kinase activity by coupling hybridization chain reaction

The present work reported a simple, lable-free and sensitive electrochemical method for the detection of protein kinase A (PKA) activity. This method was based on the specific recognition of aptamer and the aptamer-induced hybridization chain reaction (HCR) amplification strategy. The aptasensor was constructed by immobilizing capture probe on a gold electrode via an Au-S bond. When adenosine triphosphate (ATP) aptamer was introduced, its one terminus hybridized with capture probe and the other hybridized with the complementary region of an auxiliary probe, which other region triggered HCR between two hairpin DNA (H1 and H2) to form a long DNA concatamer. At last a large number of electroactive methyle blue (MB) molecules were assembled on the dsDNA concatamer, which generated a significantly amplified electrochemical signal. In the presence of ATP, the HCR would not be performed because the aptamer specifically bond to ATP and the electrochemical response would decrease. However, when ATP and PKA coexisted, the electrochemical response would recovery because that ATP had been translated into ADP by PKA. So the activity of PKA could be effectively monitored according to the change of electrochemical signal. Based on the HCR amplification strategy, the aptasensor showed a wide linear range (4 - 4 ×105 U L-1) and a low detection limit (1.5 U L-1) for the detection of PKA. Furthermore, the method was applied to study the inhibitory effect of H-89 on PKA activity. The developed aptasensor was also used to the analysis of drug-induced PKA activity in cell lysates, indicating the potential application of the developed method in the fields of clinical diagnostics and discovery of new targeted drugs.

A novel photoelectrochemical biosensor for protein kinase activity assay based on phosphorylated graphite-like carbon nitride

Protein kinases are general and significant regulators in the cell signaling pathway, and it is still greatly desired to achieve simple and quick kinase detection. Herein, we develop a simple and sensitive photoelectrochemical strategy for the detection of protein kinase activity based on the bond between phosphorylated peptide and phosphorylated graphite-like carbon nitride (P-g-C3N4) conjugates triggered by Zr(4+) ion coordination. Under optimal conditions, the increased photocurrent is proportional to the protein kinase A (PKA) concentration ranging from 0.05 to 50U/mL with a detection limit of 0.077U/mL. Moreover, this photoelectrochemical assay can be also applied to quantitative analysis of kinase inhibition. The results indicated that the IC50 value (inhibitor concentration producing 50% inhibitor) for ellagic acid was 9.1μM. Moreover, the developed method is further applied to detect PKA activity in real samples, which contains serum from healthy person and gastric cancer patients and breast tissue from healthy person and breast cancer patients. Therefore, the established protocol provides a new and simple tool for assay of kinase activity and its inhibitors with low cost and high sensitivity.

Zirconium-metalloporphyrin frameworks as a three-in-one platform possessing oxygen nanocage, electron media, and bonding site for electrochemiluminescence protein kinase activity assay.

A Zr-based metal-organic framework with zinc tetrakis(carboxyphenyl)-porphyrin (ZnTCPP) groups (MOF-525-Zn) was utilized to develop a novel electrochemiluminescence (ECL) biosensor for highly sensitive protein kinase activity assay. In this work, in terms of ECL measurements and cyclic voltammetry, the cathodic ECL behaviors of MOF-525-Zn in aqueous media were thoroughly investigated for the first time. The photoelectric active groups ZnTCPP on the MOF-525-Zn frameworks could promote the generation of singlet oxygen ((1)O2) via a series of electrochemical and chemical reactions, resulting in a strong and stable red irradiation at 634 nm. Additionally, the surfactant tetraoctylammonium bromide (TOAB) further facilitated dissolved oxygen to interact with the active sites ZnTCPP of MOF-525-Zn. Furthermore, the inorganic Zr-O clusters of MOF-525-Zn were simultaneously served as the recognition sites of phosphate groups. And then, an ultrasensitive ECL sensor was proposed for protein kinase A (PKA) activity detection with a linear range from 0.01 to 20 U mL(-1) and a sensitive detection limit of 0.005 U mL(-1). This biosensor can also be applied for quantitative kinase inhibitor screening. Finally, it exhibits good performance with high stability and acceptable fabrication reproducibility, which provide a valuable strategy for clinic diagnostics and therapeutics.

A robust and quantitative assay platform for multiplexed, high throughput screening of protein kinase inhibitors.

We present a new platform for multiplexed protein kinase activity assay using TiO2 decorated graphene oxide (GO), which is applicable to high throughput inhibitor screening. On the basis of the strong affinity of TiO2 for the phosphate group and the fluorescence quenching capability of GO, phosphorylation of substrates by protein kinases was quantitatively measured in a short time.

Novel protein kinase activity assays based on functional nanomaterials

Protein phosphorylation catalyzed by protein kinase is one of the most ubiquitous and important post-translational modification and aberrant phosphorylation is closely related with a variety of human diseases, especially cancer. As the critical component of intracellular signal pathways, protein kinases are involved in regulating a number of important physiological processes, such as cell growth, metabolism, differentiation, and proliferation. Therefore, developing potent and specific analytical methods of protein kinases are of great significance for biochemical fundamental research, disease diagnosis and treatment, and drug development. In recent years, the growing number of functional nanomaterials have been exploited in the development of protein kinase biosensors. Due to their unique optical, electrical, chemical, and catalytic properties, nanomaterials play crucial roles in several key processes in bio-sensing, such as signal generation and transduction, biosensing interface fabrication, as well as biochemical signal amplification, which greatly improves the analytical performance of kinase biosensors. This paper briefly summarizes the generally used molecular recognition mechanisms of kinase detections, then gives a systematic overview of the nanomaterials-based protein kinases assays classified by the different analytical techniques. Consequently, the future development of protein kinase biosensors is prospected.

A real-time, fluorescence-based assay for Rho-associated protein kinase activity

Inhibitors of Rho-associated protein kinase (ROCK) enzymatic activity have been shown to reduce the invasive phenotype observed in metastatic hepatocellular carcinoma (HCC). We describe the design, synthesis, and evaluation of a direct probe for ROCK activity utilizing a phosphorylation-sensitive sulfonamido-oxine fluorophore, termed Sox. The Sox fluorophore undergoes an increase in fluorescence upon phosphorylation of a proximal amino acid via chelation-enhanced fluorescence (CHEF, ex.=360nm and em.=485nm), allowing for the direct visualization of the rate of phosphate addition to a peptide substrate over time. Our optimal probe design, ROCK-S1, is capable of sensitively reporting ROCK activity with a limit of detection of 10pM and a high degree of reproducibility (Z'-factor=0.6 at 100pM ROCK2). As a proof-of-principle for high-throughput screening (HTS) we demonstrate the ability to rapidly assess the efficacy of a 78 member, small molecule library against ROCK2 using a robotics platform. We identify two previously unreported ROCK2 inhibitor scaffolds, PHA665752 and IKK16, with IC50 values of 3.6μM and 247nM respectively. Lastly, we define conditions for selectively monitoring ROCK activity in the presence of potential off-target enzymes (PKCα, PKA, and PAK) with similar substrate specificities.

A dual-potential electrochemiluminescence ratiometric approach based on graphene quantum dots and luminol for highly sensitive detection of protein kinase activity.

A novel Au NP mediated dual-potential ECL ratiometric approach for highly sensitive protein kinase activity and inhibition assay has been developed based on the simultaneous decrease of cathodic ECL from GQDs and enhancement of anodic ECL from luminol in the same bioanalysis.

Gold Nanoparticle Enhanced Electrochemical Assay for Protein Kinase Activity Using a Synthetic Chemosensor on a Microchip

Phosphorylation by protein kinases is a predominant form of protein regulation. Abnormal phosphorylation of protein is linked to several medical conditions. In this paper, we report a disposable electrochemical microchip for protein kinase activity assay based on a synthetic chemosensor. The approach involves the phosphate-specific chemosensors linked to gold nanoparticles, anchored on an electrochemical sensor fabricated on the plastic film, and the enzyme substrate labeled with ferrocene tag. In the presence of protein kinase, the substrate undergoes phosphorylation, which subsequently binds to the chemosensor, and then the ferrocene tag of the enzymatic product generates strong oxidation current under voltammetry. Gold nanoparticles were employed as a bridge between the electrode and chemosensor, which significantly enhanced the current signal. A limit of detection of the enzyme was estimated to be 0.05 U/mL with a linear dynamic range between 2–50 U/mL. Furthermore, the interference and inhibition studies were also successfully carried out using this strategy. The method proposes the potential for application in the development of a kinase assay system.

Homogeneous electrochemical assay for protein kinase activity.

Herein, we report a homogeneous assay for protein kinase activity using an electrochemistry-based probe. The approach involves a peptide substrate conjugated with a redox tag and the phosphate-specific receptor immobilized on an electrode surface. The peptide substrate phosphorylated by a protein kinase binds to the receptor site of the probe, which results in a redox current under voltammetric measurement. Our method was successfully applied even in the presence of citrated human blood and modified to enable a single-use, chip-based electrochemical assay for kinase activity.

A signal “on” photoelectrochemical biosensor for assay of protein kinase activity and its inhibitor based on graphite-like carbon nitride, Phos-tag and alkaline phosphatase

A highly sensitive and selective photoelectrochemical (PEC) biosensor is fabricated for the detection of protein kinase activity based on visible-light active graphite-like carbon nitride (g-C3N4) and the specific recognition utility of Phos-tag for protein kinase A (PKA)-induced phosphopeptides. For assembling the substrate peptides, g-C3N4 and gold nanoparticles (g-C3N4-AuNPs) complex is synthesized and characterized. When the immobilized peptides on g-C3N4-AuNPs modified ITO electrode are phosphorylated under PKA catalysis, they can be specifically identified and binded with biotin functionalized Phos-tag (Phos-tag-biotin) in the presence of Zn(2+). Then, through the specific interaction between biotin and avidin, avidin functionalized alkaline phosphatase (avidin-ALP) is further assembled to catalyze its substrate of l-ascorbic acid-2-phosphate trisodium salt (AAP) to produce electron donor of ascorbic acid (AA), resulting an increased photocurrent compared with the absence of phosphorylation event. Based on the specific identification effect of Phos-tag, the fabricated biosensor presents excellent selectivity for capturing the phosphorylated serine residues in the substrate peptides. With the good photoactivity of g-C3N4 and ALP-catalyzed signal amplification, the fabricated biosensor presents high sensitivity and low detection limit (0.015 unit/mL, S/N = 3) for PKA. The applicability of this PEC biosensor is further testified by the evaluation of PKA inhibition by HA-1077 with the IC50 value of 1.18μM. This new strategy is also successfully applied to detect the change of PKA activity in cancer cell lysate with and without drug stimulation. Therefore, the developed PEC method has great potential in screening of kinase inhibitors and highly sensitive detection of kinase activity.

A Phos-tag-based photoelectrochemical biosensor for assay of protein kinase activity and inhibitors

Abstract A novel, sensitive and label-free photoelectrochemical assay for monitoring the activity and inhibition of protein kinase A (PKA) was presented based on the specific recognition ability of biotinylated Phos-tag for kinase-induced phosphopeptides. When the assembled substrate peptides were phosphorylated by PKA, they could bind specifically to the biotinylated Phos-tag in the presence of Zn2+. Then streptavidins could be further captured on the electrode surface through their specific interaction towards biotin, resulting in a significant decrease on the photocurrent of substrate Bi2S3 modified ITO electrode. The decreased photocurrent was proportional to the PKA concentration ranging from 0.05 to 100 unit/mL with a detection limit of 0.017 unit/mL (S/N = 3). Moreover, this photoelectrochemical method could be also used to quantitative analysis of kinase inhibition. In the light of the inhibitor concentration dependant photocurrent signal, the IC50 value for ellagic acid and HA-1077 was estimated to be 3.23 and 1.77 μM, respectively. With changing the sequence of substrate peptide, this method could also be applied to detect other kinase activity and inhibitors. Therefore, the developed protocol provides a new and promising platform for assay of kinase activity and its inhibitors with low cost and high sensitivity.

A colormetric and fluorescent chemosensor for adenosine-5′-triphosphate based on rhodamine derivative

A rhodamine spirolactam derivative (1) was developed as a colormetric and fluorescent chemosensor for adenosine-5'-triphosphate (ATP) via hydrogen bonds interaction. As far as we know, this is the first case to explore ATP-induced ring-opening of spirolactam in rhodamine derivatives. It exhibited a highly sensitive "turn-on" fluorescent response toward ATP with a 47-fold fluorescence intensity enhancement under 20 equiv. of ATP added. The chemosensor can be applied to the quantification of ATP with a linear range covering from 1.0×10(-7) to 2.0×10(-4) M and a detection limit of 2.5×10(-8) M. The experiment results show that the response behavior of 1 toward ATP is pH independent in medium condition (pH 6.0-8.0). Most importantly, the novel chemosensor has well solved the problem of serious interferences from other nucleoside polyphosphates such as ADP and AMP generally met by previously reported typical fluorescent chemosensors for ATP. Moreover, the response of the chemosensor toward ATP is fast (response time less than 3 min). In addition, the chemosensor can be used for the fluorescence assay for protein kinase activity with satisfactory results. The chemosensor for ATP based on hydrogen bonds interaction provided a novel strategy for the design of colormetric and ratiometric fluorescent probes for other target anions with high sensitivity and selectivity.