Kinase Isoforms Research Articles

Discovery of novel naphthalene-based diarylamides as pan-Raf kinase inhibitors with promising anti-melanoma activity: rational design, synthesis, in vitro and in silico screening.

Raf kinase enzymes are often dysregulated in melanoma. While sorafenib demonstrates strong activity against wild-type B-Raf, it fails to effectively inhibit the mutated form of B-Raf. In this study, sorafenib served as a lead compound for the development of new derivatives designed to enhance inhibitory activity across multiple Raf isoforms (pan-Raf inhibitors). Novel naphthalene-based diarylamide derivatives were subsequently designed, synthesized, and evaluated for their biological activity against various Raf kinase isoforms and the melanoma A375 cell line. Among these, compound 9a, containing a difluoromethoxy group, demonstrated strong inhibitory activity across B-RafWT, B-RafV600E, and c-Raf. Additionally, it induced G2/M phase arrest and triggered dose-dependent apoptosis, effectively suppressing both cell proliferation and survival. Compound 9a also exhibited high selectivity for Raf isoforms with minimal off-target effects, underscoring its specificity and therapeutic potential for Raf-driven malignancies.

Coptisine improves LPS-induced anxiety-like behaviors by regulating the Warburg effect in microglia via PKM2.

Neuroinflammation mediated by microglia is considered the primary cause and pathological process of anxiety. Abnormal glycolysis of microglia is observed during microglia activation. However, whether regulating the Warburg effect in microglia can effectively intervene anxiety and its potential mechanisms have not been elucidated. This study focused on coptisine (Cop), a natural alkaloid that regulates the glycolysis and function of microglia affecting anxiety. The effects of Cop on anxiety-like behaviors, hippocampal synaptic function, and excessive activation of microglia were assessed in lipopolysaccharide (LPS) induced mouse models of anxiety. Microglia expressing mutant pyruvate kinase isoform M2 (PKM2) were used to further investigate the molecular mechanism by which Cop regulates the phenotype of microglia. neuroinflammatory is emerging Further research revealed that Cop attaches to the amino acid residue phenylalanine 26 of PKM2, shifting the dynamic equilibrium of PKM2 towards tetramers, and enhancing its pyruvate kinase activity. This interaction prevented LPS-induced Warburg effect and inactivated PKM2/hypoxia-inducible factor-1α (HIF-1α) pathway in microglia. In conclusion, Cop attenuates anxiety by regulating the Warburg effect in microglia. Our work revealed the role of PKM2/(HIF-1α) pathway in anxiety for the first time. Importantly, the molecular mechanism by which Cop ameliorates anxiety-like behaviors is through modulation of the dimeric/tetrameric form of PKM2, indicating the usefulness of PKM2 as a key potential target for the treatment of anxiety.

Sphingosine kinase 2 (SphK2) depletion alters redox metabolism and enhances inflammation in a diet-induced MASH mouse model.

Sphingosine-1 phosphate (S1P) is a bioactive lipid molecule that modulates inflammation and hepatic lipid metabolism in MASLD, which affects 1 in 3 people and increases the risk of liver fibrosis and hepatic cancer. S1P can be generated by 2 isoforms of sphingosine kinase (SphK). SphK1 is well-studied in metabolic diseases. In contrast, SphK2 function is not well characterized. Both sphingolipid and redox metabolism dysregulation contribute to MASLD pathologic progression. While SphK2 localizes to both the nucleus and mitochondria, its specific role in early MASH is not well defined. This study examined SphK2 depletion effects on hepatic redox metabolism, mitochondrial function, and inflammation in a 16-week western diet plus sugar water (WDSW)-induced mouse model of early MASH. WDSW-SphK2-/- mice exhibit increased hepatic lipid accumulation and hepatic redox dysregulation. In addition, mitochondria-localized cholesterol and S1P precursors were increased. We traced SphK2-/--mediated mitochondrial electron transport chain impairment to respiratory complex-IV and found that decreased mitochondrial redox metabolism coincided with increased oxidase gene expression and oxylipin production. Consistent with this relationship, we observed pronounced increases in hepatic inflammatory gene expression, prostaglandin accumulation, and innate immune homing in WDSW-SphK2-/- mice compared to WDSW-wild-type mice. These studies suggest SphK2-derived S1P maintains hepatic redox metabolism and describe the potential consequences of SphK2 depletion on proinflammatory gene expression, lipid mediator production, and immune infiltration in MASH progression.

Evaluation of Taraxacum officinale phytoconstituents as potential JNK1 inhibitors: Perspectives from ADMET, molecular docking, molecular dynamics, and density functional theory

Evaluation of Taraxacum officinale phytoconstituents as potential JNK1 inhibitors: Perspectives from ADMET, molecular docking, molecular dynamics, and density functional theory

Interdependency and differential expression of ERK1 and ERK2 in breast and melanoma cell lines

BackgroundRegulatory mechanism of ERK1 and ERK2, their mechanisms of action, and how they impact on development, growth, and homeostasis of different organisms have been given much emphasis for long. ERK1 and 2 though are isoforms of ERK mitogen-activated protein kinase but are coded by two different genes MAPK3 and MAPK1 respectively and show differential expressions and interdependency in different cancer cell lines. Our previous investigations substantially stated the effect of ERK1 and ERK2 on different extracellular molecules like MMPs and integrins, responsible for cell growth and differentiation. Here, we aim to study individual roles of ERK1 and ERK2 and their interdependency in progression and invasiveness in various cancer cell lines.MethodsDifferent cancer cell lines namely B16F10 (melanoma), MCF7, and MDAMB231 (breast cancer) for studying this particular question were used. Methodologies like gelatin zymography, immunoprecipitation, Western blotting, cell invasion assay, wound healing assay, siRNA transfection, and double transfection procedures were followed for our study.ResultsOur findings suggest compensation for ERK2 deficiency by pERK1, clear ERK2 predominance in MCF7 cell line, ERK1-ERK2 interdependency in MDAMB231 cells with regard to compensating each other, and significant role of both ERK1 and ERK2 in modulation of MMP9.ConclusionIf summarized, our results prove the contribution of ERK2 in compensating ERK1 loss and vice versa and an evident role of ERK1 in cancer cell invasiveness.

Computational Design, Chemical Synthesis, and Bioevaluation of Pyrimidinyl‐Indoles for Targeting Breast Cancer Cells

AbstractCancer is a global health challenge, despite significant advancements in research. Addressing this issue, we report the design, synthesis and biological evaluation of pyrimidinyl indoles as potential antineoplastic agents. Pyrimidinyl indoles interact with pyruvate kinase isoform M2 (PKM2), which is commonly overexpressed in oral, lung, breast and colorectal cancers. In silico studies indicated that these molecules are having affinity towards PKM2 and targeting key residues such as Phe26, Leu27, Tyr390, Gln393, Leu394 and Glu397 at the interfacial active site region between the two chains of PKM2. Thereafter compounds were designed, synthesized and characterized using nuclear magnetic resonance (NMR), infrared spectroscopy (IR) and mass spectrometry (MS). This was followed by in vitro screening using cell lines and enzyme‐coupled assays. One of the designed PKM2 inhibitor demonstrated potent anticancer activity against MCF‐7 (Breast Cancer) cells while sparing normal MCF‐10 A breast cells. Molecular dynamics (MD) simulation studies showed that the developed inhibitor stabilized the PKM2 active site over a 100 ns simulation.

Tetramerization of PKM2 Alleviates Traumatic Brain Injury by Ameliorating Mitochondrial Damage in Microglia.

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. Microglial activation and neuroinflammation are key cellular events that determine the outcome of TBI, especially neuronal and cognitive function. Studies have suggested that the metabolic characteristics of microglia dictate their inflammatory response. The pyruvate kinase isoform M2 (PKM2), a key glycolytic enzyme, is involved in the regulation of various cellular metabolic processes, including mitochondrial metabolism. This suggests that PKM2 may also participate in the regulation of microglial activation during TBI. Therefore, the present study aimed to evaluate the role of PKM2 in regulating microglial activation and neuroinflammation and its effects on cognitive function following TBI. A controlled cortical impact (CCI) mouse model and inflammation-induced primary mouse microglial cells in vitro were used to investigate the potential effects of PKM2 inhibition and regulation. PKM2 was significantly increased during the acute and subacute phases of TBI and was predominantly detected in microglia rather than in neurons. Our results demonstrate that shikonin and TEPP-46 can inhibit microglial inflammation, improving mitochondria, improving mouse behavior, reducing brain defect volume, and alleviating pathological changes after TBI. There is a difference in the intervention of shikonin and TEPP-46 on PKM2. Shikonin directly inhibits General PKM2; TEPP-46 can promote the expression of PKM2 tetramer. In vitro experiments, TEPP-46 can promote the expression of PKM2 tetramer, enhance the interaction between PKM2 and MFN2, improve mitochondria, alleviate neuroinflammation. General inhibition and tetramerization activation of PKM2 attenuated cognitive function caused by TBI, whereas PKM2 tetramerization exhibited a better treatment effect. Our experiments demonstrated the non-metabolic role of PKM2 in the regulation of microglial activation following TBI. Both shikonin and TEPP-46 can inhibit pro-inflammatory factors, but only TEPP-46 can promote PKM2 tetramerization and upregulate the release of anti-inflammatory factors from microglia.

Development of Brain Penetrant Pyridazine Pantothenate Kinase Activators.

Conversion of pantothenate to phosphopantothenate in humans is the first dedicated step in the coenzyme A (CoA) biosynthesis pathway and is mediated by four isoforms of pantothenate kinase. These enzymes are allosterically regulated by acyl-CoA levels, which control the rate of CoA biosynthesis. Small molecule activators of the PANK enzymes that overcome feedback suppression increase CoA levels in cultured cells and animals and have shown great potential for the treatment of pantothenate kinase-associated neurodegeneration and propionic acidemias. In this study, we detail the further optimization of PANK pyridazine activators using structure-guided design and focus on the cellular CoA activation potential, metabolic stability, and solubility as the primary drivers of the structure-activity relationship. These studies led to the prioritization of three late-stage preclinical lead PANK modulators with improved pharmacokinetic profiles and the ability to substantially increase brain CoA levels. Compound 22 (BBP-671) eventually advanced into clinical testing for the treatment of PKAN and propionic acidemia.

Sclerostin inhibits Protein kinase C inhibitor GÖ6976 induced osteogenic differentiation of dental follicle cells

Human dental follicle cells (DFCs) as multipotent stem cells are currently investigated within the field of regenerative medicine considering their potential for the regeneration of dental tissues, bone defects caused by periodontal or degenerative diseases and the treatment of craniofacial disorders. However, molecular mechanisms of the differentiation into mineralizing cells are still inadequately understood. Previous studies have shown that GÖ6976, an inhibitor of classical isoforms of protein kinase C (PKC), enhanced ostogenic differentiation of DFCs. A possible mechanism for increased osteogenic differentiation could be the regulation of ossification inhibitors. This study therefore investigated whether the osteogenic differentiation inhibitor sclerostin (SOST) is regulated by GÖ6976 and whether the addition of sclerostin attenuates the stimulating effect of the PKC inhibitor. We demonstrated that the expression of the sclerostin gene decreased after PKC inhibition by GÖ6976 and that its gene expression is likely maintained by PKC via the BMP signaling pathway. Furthermore, supplementation of osteogenic differentiation medium with sclerostin impairs GÖ6976-induced differentiation of DFCs. Our data suggest that regulation of sclerostin mediates PKC inhibition-induced mineralization of DFCs.

Abstract Mo011: Selective silencing of p38δ is cardioprotective in female mice during doxorubicin chemotherapy

Introduction: Dose-dependent cardiotoxicity limits the efficacy of chemotherapeutic agent doxorubicin (DOX). p38δ is one of four p38 mitogen-activated protein kinase isoforms that regulate DOX-induced cardiotoxicity (DIC). p38δ genetic deletion protects female mice from DIC. In the absence of selective pharmacologic inhibitors of p38δ, docosanoic acid (DCA) conjugate-mediated delivery of chemically engineered small interfering RNA (siRNA) provides a novel avenue to achieve selective, efficient, durable, and nontoxic in vivo p38δ silencing in the heart. Hypothesis: The selective silencing of p38δ is cardioprotective from DIC in female mice. Methods: Following the screening of a panel of p38δ-selective siRNA sequences, the lead siRNA si-p38δ-1, with the highest silencing efficacy and potency in vitro, was identified. 15-week-old female mice were subcutaneously injected with 20 mg/kg of DCA-conjugated chemically stabilized si-p38δ-1 (n = 3) or the non-targeting control (NTC) siRNA (n = 3) twice 10 hours apart. p38δ silencing in mouse hearts was measured 14 days later by assessing mRNA and protein expression. To evaluate the effect of p38δ silencing after acute DOX treatment, the mice were administered si-p38δ-1 (n = 5) or NTC (n = 5), followed by DOX treatment (30 mg/kg) six days later. The study concluded 11 days after DOX treatment. Morbidity was assessed by assigning health scores daily. Electrocardiography, echocardiography, and optical mapping were performed to evaluate cardiac function. Results: si-p38δ-1 led to 80% silencing of p38δ in mouse hearts 14 days after administration, without any cardiotoxic effects. si-p38δ-1-treated female mice exhibited diminished DOX-induced morbidity (p = 0.003) and were protected from developing calcium alternans (CAs) 11 days post-DOX treatment, compared to NTC-treated counterparts. Thus, DOX-induced CAs, indicative of calcium mishandling, were observed in 75% (3/4) NTC-treated mice and 0% (0/5) si-p38δ-1-treated mice. Conclusion: Efficient and well-tolerated in vivo p38δ silencing by si-p38δ-1 in mouse hearts mitigated DOX-induced morbidity and calcium mishandling in female mice, highlighting the therapeutic potential of p38δ silencing for alleviating DIC in female cancer patients.

In silico Screening and in vitro Cytotoxicity Study of Achyranthes aspera Phytochemicals Against Oral Cancer: A Possible Step towards the Development of Anti-cancer Agents.

Oral cancer poses a significant threat to public health worldwide. In addition, because many chemotherapy treatments have negative side effects, natural herbs may be beneficial for oral cancer therapy. Achyranthes aspera (AA), a potential medicinal herb, exerts various pharmacological and biochemical activities. The present study aimed to predict the anti-oral cancer potential of AA using in silico tools and cell death by in vitro testing. A total of fourteen bioactive constituents from AA herb were selected using phytochemical databases. The toxicity of AA herb extract was analysed through MTT assay against oral carcinoma A253 cell line. The binding activities of the phytocomponents against serine/ threonine-specific protein kinases isoforms, namely Akt1 (PDB ID: 3qkk) and Akt2 (PDB ID: 2jdo) proteins, were analysed using Discovery Studio 2021 and PyRx docking software. Cell viability data revealed that AA extract decreased the viability and reduced the number of live cells of the oral carcinoma A253 cell line in a dose-dependent manner. The halfmaximal concentration (IC50) value of AA was assessed as 204.74 μg/ml. Based on binding affinity, saponin C (-CDOCKER energy = -77.9862), oleanolic acid (-CDOCKER energy = - 49.4349), spinasterol (-CDOCKER energy = -38.1246), 36,47-dihydroxyhenpentacontan-4-one (-CDOCKER energy = -32.4386), and 20-hydroxyecdysone (-CDOCKER energy = -31.9138) were identified as the best compounds against Akt1, while, compounds saponin C (-CDOCKER energy = -134.412), oleanolic acid (-CDOCKER energy = -90.0846), spinasterol (-CDOCKER energy = -78.3213), 20-hydroxyecdysone (-CDOCKER energy = -80.1049), and ecdysone (- CDOCKER energy = -73.3885) were identified as Akt2 inhibitors. These top compounds fulfilled drug score values, pharmacokinetic and physicochemical characteristics, and druglikeness parameters. The present findings reveal that the lead phytomolecules of AA could be effective and developed as a prospective drug against oral cancer.

Checkpoint Kinase 1 Stimulates Endogenous Cardiomyocyte Renewal and Cardiac Repair by Binding to Pyruvate Kinase Isoform M2 C-Domain and Activating Cardiac Metabolic Reprogramming in a Porcine Model of Myocardial Ischemia/Reperfusion Injury.

The regenerative capacity of the adult mammalian hearts is limited. Numerous studies have explored mechanisms of adult cardiomyocyte cell-cycle withdrawal. This translational study evaluated the effects and underlying mechanism of rhCHK1 (recombinant human checkpoint kinase 1) on the survival and proliferation of cardiomyocyte and myocardial repair after ischemia/reperfusion injury in swine. Intramyocardial injection of rhCHK1 protein (1 mg/kg) encapsulated in hydrogel stimulated cardiomyocyte proliferation and reduced cardiac inflammation response at 3 days after ischemia/reperfusion injury, improved cardiac function and attenuated ventricular remodeling, and reduced the infarct area at 28 days after ischemia/reperfusion injury. Mechanistically, multiomics sequencing analysis demonstrated enrichment of glycolysis and mTOR (mammalian target of rapamycin) pathways after rhCHK1 treatment. Co-Immunoprecipitation (Co-IP) experiments and protein docking prediction showed that CHK1 (checkpoint kinase 1) directly bound to and activated the Serine 37 (S37)and Tyrosine 105 (Y105) sites of PKM2 (pyruvate kinase isoform M2) to promote metabolic reprogramming. We further constructed plasmids that knocked out different CHK1 and PKM2 amino acid domains and transfected them into Human Embryonic Kidney 293T (HEK293T) cells for CO-IP experiments. Results showed that the 1-265 domain of CHK1 directly binds to the 157-400 amino acids of PKM2. Furthermore, hiPSC-CM (human iPS cell-derived cardiomyocyte) invitro and invivo experiments both demonstrated that CHK1 stimulated cardiomyocytes renewal and cardiac repair by activating PKM2 C-domain-mediated cardiac metabolic reprogramming. This study demonstrates that the 1-265 amino acid domain of CHK1 binds to the 157-400 domain of PKM2 and activates PKM2-mediated metabolic reprogramming to promote cardiomyocyte proliferation and myocardial repair after ischemia/reperfusion injury in adult pigs.

GENERATION AND CHARACTERIZATION OF POLYCLONAL ANTIBODIES SPECIFIC TO HUMAN ESTROGEN RECEPTOR ERα

Aim. The purpose of the study was to generate and characterize anti-hERα polyclonal antibodies for elucidation of functional relationships between isoforms of estrogen receptor ERα and isoforms of ribosomal protein S6 kinase — S6K1. Methods. cDNA cloning. Expression of recombinant proteins in bacterial system. Affinity purification of His-tag fused recombinant proteins using Ni-NTA chromatography from bacterial lysates. Generation of polyclonal sera by mice immunization. Western blot analysis and immunoprecipitation. Results. cDNA coding for full length hERα was cloned into expression vector pET28a in frame with His-tag sequence. Recombinant hERα-His protein was expressed in E.Coli and purified by Ni-NTA chromatography. Purified hERα-His was used as antigen for mice immunization and generation of polyclonal antibodies. Specificity of polyclonal antibodies was analyzed by Western blot and immunoprecipitation of hERα from MCf-7 cell lysates. Conclusions. Generated anti-hERα polyclonal antibodies are of conformational type since specifically recognized hERα only in immunoprecipitation but not in Western blot. Created polyclonal antibodies a suitable for detection and analysis of hERα protein complexes.

Sphingosine kinase 2 regulates protein ubiquitination networks in neurons

Two sphingosine kinase isoforms, sphingosine kinase 1 (SPHK1) and sphingosine kinase 2 (SPHK2), synthesize the lipid sphingosine-1-phosphate (S1P) by phosphorylating sphingosine. SPHK1 is a cytoplasmic kinase, and SPHK2 is localized to the nucleus and other organelles. In the cytoplasm, the SPHK1/S1P pathway modulates autophagy and protein ubiquitination, among other processes. In the nucleus, the SPHK2/S1P pathway regulates transcription. Here, we hypothesized that the SPHK2/S1P pathway governs protein ubiquitination in neurons. We found that ectopic expression of SPHK2 increases ubiquitinated substrate levels in cultured neurons and pharmacologically inhibiting SPHK2 decreases protein ubiquitination. With mass spectrometry, we discovered that inhibiting SPHK2 affects lipid and synaptic protein networks as well as a ubiquitin-dependent protein network. Several ubiquitin-conjugating and hydrolyzing proteins, such as the E3 ubiquitin-protein ligases HUWE1 and TRIP12, the E2 ubiquitin-conjugating enzyme UBE2Z, and the ubiquitin-specific proteases USP15 and USP30, were downregulated by SPHK2 inhibition. Using RNA sequencing, we found that inhibiting SPHK2 altered lipid and neuron-specific gene networks, among others. Genes that encode the corresponding proteins from the ubiquitin-dependent protein network that we discovered with mass spectrometry were not affected by inhibiting SPHK2, indicating that the SPHK2/S1P pathway regulates ubiquitination at the protein level. We also show that both SPHK2 and HUWE1 were upregulated in the striatum of a mouse model of Huntington's disease, the BACHD mice, indicating that our findings are relevant to neurodegenerative diseases. Our results identify SPHK2/S1P as a novel regulator of protein ubiquitination networks in neurons and provide a new target for developing therapies for neurodegenerative diseases.

Diacylglycerol kinase delta overexpression improves glucose clearance and protects against the development of obesity

Diacylglycerol kinase (DGK) isoforms catalyze an enzymatic reaction that removes diacylglycerol (DAG) and thereby terminates protein kinase C signaling by converting DAG to phosphatidic acid. DGKδ (type II isozyme) downregulation causes insulin resistance, metabolic inflexibility, and obesity. Here we determined whether DGKδ overexpression prevents these metabolic impairments. We generated a transgenic mouse model overexpressing human DGKδ2 under the myosin light chain promoter (DGKδ TG). We performed deep metabolic phenotyping of DGKδ TG mice and wild-type littermates fed chow or high-fat diet (HFD). Mice were also provided free access to running wheels to examine the effects of DGKδ overexpression on exercise-induced metabolic outcomes. DGKδ TG mice were leaner than wild-type littermates, with improved glucose tolerance and increased skeletal muscle glycogen content. DGKδ TG mice were protected against HFD-induced glucose intolerance and obesity. DGKδ TG mice had reduced epididymal fat and enhanced lipolysis. Strikingly, DGKδ overexpression recapitulated the beneficial effects of exercise on metabolic outcomes. DGKδ overexpression and exercise had a synergistic effect on body weight reduction. Microarray analysis of skeletal muscle revealed common gene ontology signatures of exercise and DGKδ overexpression that were related to lipid storage, extracellular matrix, and glycerophospholipids biosynthesis pathways. Overexpression of DGKδ induces adaptive changes in both skeletal muscle and adipose tissue, resulting in protection against HFD-induced obesity. DGKδ overexpression recapitulates exercise-induced adaptations on energy homeostasis and skeletal muscle gene expression profiles.

Muscle-specific pyruvate kinase isoforms, PKM1 and PKM2, regulate mammalian SWI/SNF proteins and histone 3 phosphorylation during myoblast differentiation.

Pyruvate kinase is a glycolytic enzyme that converts phosphoenolpyruvate and ADP into pyruvate and ATP. There are two genes that encode pyruvate kinase in vertebrates; Pkm and Pkl encode muscle- and liver/erythrocyte-specific forms, respectively. Each gene encodes two isoenzymes due to alternative splicing. Both muscle-specific enzymes, PKM1 and PKM2, function in glycolysis, but PKM2 also has been implicated in gene regulation due to its ability to phosphorylate histone 3 threonine 11 (H3T11) in cancer cells. Here, we examined the roles of PKM1 and PKM2 during myoblast differentiation. RNA-seq analysis revealed that PKM2 promotes the expression of Dpf2/Baf45d and Baf250a/Arid1A. DPF2 and BAF250a are subunits that identify a specific sub-family of the mammalian SWI/SNF (mSWI/SNF) of chromatin remodeling enzymes that is required for the activation of myogenic gene expression during differentiation. PKM2 also mediated the incorporation of DPF2 and BAF250a into the regulatory sequences controlling myogenic gene expression. PKM1 did not affect expression but was required for nuclear localization of DPF2. Additionally, PKM2 was required not only for the incorporation of phosphorylated H3T11 in myogenic promoters but also for the incorporation of phosphorylated H3T6 and H3T45 at myogenic promoters via regulation of AKT and protein kinase C isoforms that phosphorylate those amino acids. Our results identify multiple unique roles for PKM2 and a novel function for PKM1 in gene expression and chromatin regulation during myoblast differentiation.

The search for pyruvate kinase-R activators; from a HTS screening hit via an impurity to the discovery of a lead series

Pyruvate kinase (PK) is an essential component of cellular metabolism, converting ADP and phosphoenolpyruvate (PEP) to pyruvate in the final step of glycolysis. Of the four unique isoforms of pyruvate kinase, R (PKR) is expressed exclusively in red blood cells and is a tetrameric enzyme that depends on fructose-1,6-bisphosphate (FBP) for activation. PKR deficiency leads to hemolysis of red blood cells resulting in anemia. Activation of PKR in both sickle cell disease and beta-thalassemia patients could lead to improved red blood cell fitness and survival. The discovery of a novel series of substituted urea PKR activators, via the serendipitous identification and diligent characterization of a minor impurity in an High Throughput Screening (HTS) hit will be discussed.

Novel Dihydropteridinone Derivatives As Potent Inhibitors of the Understudied Human Kinases Vaccinia-Related Kinase 1 and Casein Kinase 1δ/ε.

Vaccinia-related kinase 1 (VRK1) and the δ and ε isoforms of casein kinase 1 (CK1) are linked to various disease-relevant pathways. However, the lack of tool compounds for these kinases has significantly hampered our understanding of their cellular functions and therapeutic potential. Here, we describe the structure-based development of potent inhibitors of VRK1, a kinase highly expressed in various tumor types and crucial for cell proliferation and genome integrity. Kinome-wide profiling revealed that our compounds also inhibit CK1δ and CK1ε. We demonstrate that dihydropteridinones 35 and 36 mimic the cellular outcomes of VRK1 depletion. Complementary studies with existing CK1δ and CK1ε inhibitors suggest that these kinases may play overlapping roles in cell proliferation and genome instability. Together, our findings highlight the potential of VRK1 inhibition in treating p53-deficient tumors and possibly enhancing the efficacy of existing cancer therapies that target DNA stability or cell division.

Regulation of Dopamine Receptor Subtypes by G Protein-Coupled Receptor Kinase Isoforms

Regulation of Dopamine Receptor Subtypes by G Protein-Coupled Receptor Kinase Isoforms

Design, synthesis, and biological evaluation of novel sesquiterpene lactone derivatives as PKM2 activators with potent anti-ulcerative colitis activities

Pyruvate kinase isoform 2 (PKM2) is closely related to the regulation of Th17/Treg balance, which is considered to be an effective strategy for UC therapy. Parthenolide (PTL), a natural product, only possesses moderate PKM2-activating activity. Thus, five series of PTL derivatives are designed and synthesized to improve PKM2-activated activities and anti-UC abilities. Through detailed structure optimization, B4 demonstrates potent T-cell anti-proliferation activity (IC50=0.43μM) and excellent PKM2-activated ability (AC50=0.144μM). Subsequently, through mass spectrometry analysis, B4 is identified to interact with Cys423 of PKM2 via covalent-bond. Molecular docking and molecular dynamic simulation results reveal that the trifluoromethoxy of B4 forms a stronger hydrophobic interaction with Ala401, Pro402, and Ile403. In addition, B4 has a significant effect only on Th17cell differentiation, thereby regulating the Th17/Treg balance. The effect of B4 on Th17/Treg imbalance can be attributed to inhibition of PKM2 dimer translocation and suppression of glucose metabolism. Finally, B4 can notably ameliorate the symptoms of dextran sulfate sodium (DSS)-induced colitis in mouse model in vivo. Thus, B4 is confirmed as a potent PKM2 activator, and has the potential to develop as a novel anti-UC agent.