Association mechanism between Arabidopsis immune coreceptor BAK1 and Pseudomonas syringae effector HopF2.

Brassinosteroid activated kinase 1 (BAK1) is a cell-surface coreceptor which plays multiple roles in innate immunity of plants. HopF2 is an effector secreted by the bacterial pathogen Pseudomonas syringae pv. tomato DC3000 into Arabidopsis and suppresses host immune system through interaction with BAK1 as well as its downstream kinase MKK5. The association mechanism of HopF2 to BAK1 remains unclear, which prohibits our understanding and subsequent interfering of their interaction for pathogen management. Herein, we found the kinase domain of BAK1 (BAK1-KD) is sufficient for HopF2 association. With a combination of hydrogen/deuterium exchange mass spectrometry and mutational assays, we found a region of BAK1-KD N-lobe and a region of HopF2 head subdomain are critical for intermolecular interaction, which is also supported by unbiased protein-protein docking with ClusPro and kinase activity assay. Collectively, this research presents the interaction mechanism between Arabidopsis BAK1 and P. syringae HopF2, which could pave the way for bactericide development that blocking the functioning of HopF2 toward BAK1.

Control of lateral root formation by rapamycin-induced dimerization of engineered RGI/BAK1 and by BIR3 chimera.

Leucine-rich repeat receptor kinases (LRR-RKs) play a pivotal role in diverse aspects of growth, development, and immunity in plants by sensing extracellular signals. Typically, LRR-RKs are activated through the ligand-induced interaction with a SOMATIC EMBRYOGENESIS RECEPTOR KINASE (SERK) coreceptor, triggering downstream signaling. ROOT MERISTEM GROWTH FACTOR1 (RGF1) INSENSITIVEs (RGIs) LRR-RLK receptors promote primary root meristem activity while inhibiting lateral root (LR) development in response to RGF peptide. In this study, we employed rapamycin-induced dimerization (RiD) and BAK1-INTERACTING RECEPTOR-LIKE KINASE3 (BIR3) chimera approaches to explore the gain-of-function of RGI1, RGI4, and RGI5. Rapamycin induced the association of cytosolic kinase domains (CKDs) of RGI1 and the BAK1 coreceptor, activating both mitogen-activated protein kinase 3 (MPK3) and MPK6. Rapamycin significantly inhibited LR formation in RiD-RGI1/RGI4/RGI5-BAK1 plants. Using transgenic Arabidopsis expressing RGI1CKD fused to the BIR3-LRR chimera under estradiol control, we observed a substantial reduction in LR density upon ß-estradiol treatment. Additionally, we identified a decrease in root gravitropism in BIR3 chimera plants. In contrast, RiD-RGI/BAK1 plants did not exhibit defects in root gravitropism, implying the importance of combinatorial interactions between RGIs and SERK coreceptors in the inhibition of root gravitropism. Constitutive activation of RGIs with BAK1 in RiD-RGI/BAK1 plants by rapamycin treatment resulted in the inhibition of primary root growth, resembling the inhibitory effects observed with high concentrations of phytohormones on primary root elongation. Our findings highlight that the interactions between CKDs of RGIs and BAK1, constitutively induced by rapamycin or BIR3 chimera, efficiently control LR development.

Properties of FDA-approved small molecule protein kinase inhibitors: A 2024 update.

Owing to the dysregulation of protein kinase activity in many diseases including cancer, this enzyme family has become one of the most important drug targets in the 21st century. There are 80 FDA-approved therapeutic agents that target about two dozen different protein kinases and seven of these drugs were approved in 2023. Of the approved drugs, thirteen target protein-serine/threonine protein kinases, four are directed against dual specificity protein kinases (MEK1/2), twenty block nonreceptor protein-tyrosine kinases, and 43 inhibit receptor protein-tyrosine kinases. The data indicate that 69 of these drugs are prescribed for the treatment of neoplasms. Six drugs (abrocitinib, baricitinib, deucravacitinib, ritlecitinib, tofacitinib, upadacitinib) are used for the treatment of inflammatory diseases (atopic dermatitis, rheumatoid arthritis, psoriasis, alopecia areata, and ulcerative colitis). Of the 80 approved drugs, nearly two dozen are used in the treatment of multiple diseases. The following seven drugs received FDA approval in 2023: capivasertib (HER2-positive breast cancer), fruquintinib (metastatic colorectal cancer), momelotinib (myelofibrosis), pirtobrutinib (mantle cell lymphoma, chronic lymphocytic leukemia, small lymphocytic lymphoma), quizartinib (Flt3-mutant acute myelogenous leukemia), repotrectinib (ROS1-positive lung cancer), and ritlecitinib (alopecia areata). All of the FDA-approved drugs are orally effective with the exception of netarsudil, temsirolimus, and trilaciclib. This review summarizes the physicochemical properties of all 80 FDA-approved small molecule protein kinase inhibitors including the molecular weight, number of hydrogen bond donors/acceptors, polar surface area, potency, solubility, lipophilic efficiency, and ligand efficiency.

Signal-regulated Unmasking of Nuclear Localization Motif in the PAS Domain Regulates the Nuclear Translocation of PASK.

The ligand-regulated PAS domains are one of the most diverse signal-integrating domains found in proteins from prokaryotes to humans. By biochemically connecting cellular processes with their environment, PAS domains facilitate an appropriate cellular response. PAS domain-containing Kinase (PASK) is an evolutionarily conserved protein kinase that plays important signaling roles in mammalian stem cells to establish stem cell fate. We have shown that the nuclear translocation of PASK is stimulated by differentiation signaling cues in muscle stem cells. However, the mechanistic basis of the regulation of PASK nucleo-cytoplasmic translocation remains unknown. Here, we show that the PAS-A domain of PASK contains a putative monopartite nuclear localization sequence (NLS) motif. This NLS is inhibited in cells through intramolecular association with a short linear motif, termed the PAS Interacting Motif (PIM), found upstream of the kinase domain. This interaction serves to retain PASK in the cytosol in the absence of signaling cues. Consistent with that, we show that metabolic inputs induce PASK nuclear import, likely by disrupting this association. We suggest that a route for such linkage may occur through the PAS-A ligand binding cavity. We show that PIM recruitment and artificial ligand binding to the PAS-A domain occur at neighboring locations that could facilitate metabolic control of the PAS-PIM interaction. Thus, the intramolecular interaction in PASK integrates metabolic signaling cues for nuclear translocation and could be targeted to control the balance between self-renewal and differentiation in stem cells.

Identification of High-Affinity Inhibitors of TANK-Binding Kinase 1 (TBK1): A Promising Frontier for Controlling Inflammatory Signaling in Cancer.

BACKGROUND: TANK-binding kinase 1 (TBK1) is an important serine/threonine kinase involved in inflammatory signaling pathways, influencing cellular processes such as proliferation, programmed cell death, autophagy, and immune response regulation. Dysregulation of TBK1 has been linked to cancer progression and neurodegenerative disorders, making it an attractive target for therapeutic development. This study aimed to identify potential TBK1 inhibitors using a structure-based virtual screening approach. METHODS: We conducted a comprehensive screening of the ZINC database to identify compounds with high binding affinity for TBK1, employing molecular docking as the primary selection criterion. The top candidates were then subjected to extensive 200 ns molecular dynamics (MD) simulations to assess the conformational dynamics of TBK1 and the stability of the protein-ligand complexes, with a focus on ZINC02095133 and ZINC02130647. RESULTS: The findings revealed that TBK1 forms stable complexes with ZINC02095133 and ZINC02130647, demonstrating consistent interactions throughout the MD simulations. This suggests that these compounds hold promise as potential lead molecules for future therapies targeting TBK1. CONCLUSIONS: This study identifies ZINC02095133 and ZINC02130647 as promising TBK1 inhibitors with therapeutic potential. However, further experimental validation and optimization are required to develop novel inhibitors for diseased conditions associated with TBK1 signaling. These findings pave the way for future investigations into the clinical utility of these compounds in combating TBK1-related pathologies.

Discovering potential inhibitors of Raf proto-oncogene serine/threonine kinase 1: a virtual screening approach towards anticancer drug development.

Raf proto-oncogene serine/threonine kinase 1 (RAF1 or c-Raf) is a serine/threonine protein kinase crucial in regulating cell growth, differentiation, and survival. Any disruption or overexpression of RAF1 can result in neoplastic transformation and other disorders such as cardiomyopathy, Noonan syndrome, leopard syndrome, etc. RAF1 has been identified as a potential therapeutic target in drug development against various complex diseases, including cancer, due to its remarkable role in disease progression. Here, we carried out a multitier virtual screening study involving different in-silico approaches to discover potential inhibitors of RAF1. After applying the Lipinski rule of five, we retrieved all phytocompounds from the IMPPAT database based on their physicochemical properties. We performed a molecular docking-based virtual screening and got top hits with the best binding affinity and ligand efficiency. Then we screened out the selected hits using the PAINS filter, ADMET properties, and other druglike features. Eventually, PASS evaluation identifies two phytocompounds, Moracin C and Tectochrysin, with appreciable anti-cancerous properties. Finally, all-atom molecular dynamics simulation (MDS) followed by interaction analysis was performed on the elucidated compounds in complex with RAF1 for 200 ns to investigate their time-evolution dynamics and interaction mechanism. Molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) and Dynamical Cross-Correlation Matrix (DCCM) analyses then followed these results from the simulated trajectories. According to the results, the elucidated compounds stabilize the RAF1 structure and lead to fewer conformational alterations. The results of the current study indicated that Moracin C and Tectochrysin could serve as potential inhibitors of RAF1 after required validation.Communicated by Ramaswamy H. Sarma.

Identification of mitogen-activated protein kinase 7 inhibitors from natural products: Combined virtual screening and dynamic simulation studies.

Mitogen-activated protein kinase 7 (MAPK7) is a serine/threonine protein kinase that belongs to the MAPK family and plays a vital role in various cellular processes such as cell proliferation, differentiation, gene transcription, apoptosis, metabolism, and cell survival. The elevated expression of MAPK7 has been associated with the onset and progression of multiple aggressive tumors in humans, underscoring the potential of targeting MAPK7 pathways in therapeutic research. This pursuit holds promise for the advancement of anticancer drug development by developing potential MAPK7 inhibitors. To look for potential MAPK7 inhibitors, we exploited structure-based virtual screening of natural products from the ZINC database. First, the Lipinski rule of five criteria was used to filter a large library of ~90,000 natural compounds, followed by ADMET and pan-assay interference compounds (PAINS) filters. Then, top hits were chosen based on their strong binding affinity as determined by molecular docking. Further, interaction analysis was performed to find effective and specific compounds that can precisely bind to the binding pocket of MAPK7. Consequently, two compounds, ZINC12296700 and ZINC02123081, exhibited significant binding affinity and demonstrated excellent drug-like properties. All-atom molecular dynamics simulations for 200 ns confirmed the stability of MAPK7-ZINC12296700 and MAPK7-ZINC02123081 docked complexes. According to the molecular mechanics Poisson-Boltzmann surface area investigation, the binding affinities of both complexes were considerable. Overall, the result suggests that ZINC12296700 and ZINC02123081 might be used as promising leads to develop novel MAPK7 inhibitors. Since these compounds would interfere with the kinase activity of MAPK7, therefore, may be implemented to control cell growth and proliferation in cancer after required validations.

Structure-Based Drug Design for Targeting IRE1: An in Silico Approach for Treatment of Cancer.

BACKGROUND: Endoplasmic Reticulum (ER) stress and Unfolded Protein Response (UPR) play a key role in cancer progression. The aggregation of incorrectly folded proteins in the ER generates ER stress, which in turn activates the UPR as an adaptive mechanism to fix ER proteostasis. Inositol-requiring enzyme 1 (IRE1) is the most evolutionary conserved ER stress sensor, which plays a pro-tumoral role in various cancers. Targeting its' active sites is one of the most practical approaches for the treatment of cancers. OBJECTIVE: In this study, we aimed to use the structure of 4µ8C as a template to produce newly designed compounds as IRE1 inhibitors. METHODS: Various functional groups were added to the 4µ8C, and their binding affinity to the target sites was assessed by conducting a covalent molecular docking study. The potential of the designed compound for further in vitro and in vivo studies was evaluated using ADMET analysis. RESULTS: Based on the obtained results, the addition of hydroxyl groups to 4µ8C enhanced the binding affinity of the designed compound to the target efficiently. Compound 17, which was constructed by the addition of one hydroxyl group to the structure of 4µ8C, can construct a strong covalent bond with Lys907. The outcomes of ADMET analysis indicated that compound 17 could be considered a drug-like molecule. CONCLUSION: Our results revealed that designed compound 17 could inhibit IRE1 activity. Therefore, this designed compound is a remarkable inhibitor of IRE1 and introduces a promising therapeutic strategy for cancer treatment.

Phosphorylation of Bub1 by Mph1 promotes Bub1 signaling at the kinetochore to ensure accurate chromosome segregation.

Bub1 is a conserved mitotic kinase involved in signaling of the spindle assembly checkpoint. Multiple phosphorylation sites on Bub1 have been characterized, yet it is challenging to understand the interplay between the multiple phosphorylation sites due to the limited availability of phosphospecific antibodies. In addition, phosphoregulation of Bub1 in Schizosaccharomyces pombe is poorly understood. Here we report the identification of a new Mph1/Mps1-mediated phosphorylation site, i.e., Ser532, of Bub1 in Schizosaccharomyces pombe. A phosphospecific antibody against phosphorylated Bub1-Ser532 was developed. Using the phosphospecific antibody, we demonstrated that phosphorylation of Bub1-Ser352 was mediated specifically by Mph1/Mps1 and took place during early mitosis. Moreover, live-cell microscopy showed that inhibition of the phosphorylation of Bub1 at Ser532 impaired the localization of Bub1, Mad1, and Mad2 to the kinetochore. In addition, inhibition of the phosphorylation of Bub1 at Ser532 caused anaphase B lagging chromosomes. Hence, our study constitutes a model in which Mph1/Mps1-mediated phosphorylation of fission yeast Bub1 promotes proper kinetochore localization of Bub1 and faithful chromosome segregation.

Epinephrine inhibits PI3Kα via the Hippo kinases.

The phosphoinositide 3-kinase p110α is an essential mediator of insulin signaling and glucose homeostasis. We interrogated the human serine, threonine, and tyrosine kinome to search for novel regulators of p110α and found that the Hippo kinases phosphorylate p110α at T1061, which inhibits its activity. This inhibitory state corresponds to a conformational change of a membrane-binding domain on p110α, which impairs its ability to engage membranes. In human primary hepatocytes, cancer cell lines, and rodent tissues, activation of the Hippo kinases MST1/2 using forskolin or epinephrine is associated with phosphorylation of T1061 and inhibition of p110α, impairment of downstream insulin signaling, and suppression of glycolysis and glycogen synthesis. These changes are abrogated when MST1/2 are genetically deleted or inhibited with small molecules or if the T1061 is mutated to alanine. Our study defines an inhibitory pathway of PI3K signaling and a link between epinephrine and insulin signaling.

Structure and regulation of full-length human leucine-rich repeat kinase 1.

The human leucine-rich repeat kinases (LRRKs), LRRK1 and LRRK2 are large and unusually complex multi-domain kinases, which regulate fundamental cellular processes and have been implicated in human disease. Structures of LRRK2 have recently been determined, but the structure and molecular mechanisms regulating the activity of the LRRK1 as well as differences in the regulation of LRRK1 and LRRK2 remain unclear. Here, we report a cryo-EM structure of the LRRK1 monomer and a lower-resolution cryo-EM map of the LRRK1 dimer. The monomer structure, in which the kinase is in an inactive conformation, reveals key interdomain interfaces that control kinase activity as we validate experimentally. Both the LRRK1 monomer and dimer are structurally distinct compared to LRRK2. Overall, our results provide structural insights into the activation of the human LRRKs, which advance our understanding of their physiological and pathological roles.

Pathogenic mutation hotspots in protein kinase domain structure.

Control of eukaryotic cellular function is heavily reliant on the phosphorylation of proteins at specific amino acid residues, such as serine, threonine, tyrosine, and histidine. Protein kinases that are responsible for this process comprise one of the largest families of evolutionarily related proteins. Dysregulation of protein kinase signaling pathways is a frequent cause of a large variety of human diseases including cancer, autoimmune, neurodegenerative, and cardiovascular disorders. In this study, we mapped all pathogenic mutations in 497 human protein kinase domains from the ClinVar database to the reference structure of Aurora kinase A (AURKA) and grouped them by the relevance to the disease type. Our study revealed that the majority of mutation hotspots associated with cancer are situated within the catalytic and activation loops of the kinase domain, whereas non-cancer-related hotspots tend to be located outside of these regions. Additionally, we identified a hotspot at residue R371 of the AURKA structure that has the highest number of exclusively non-cancer-related pathogenic mutations (21) and has not been previously discussed.

Investigating MARK4 inhibitory potential of Bacopaside II: Targeting Alzheimer's disease.

Microtubule affinity regulating kinase 4 (MARK4) is known to hyperphosphorylate tau protein, which subsequently causes Alzheimer's disease (AD). MARK4 is a well-validated drug target for AD; thus, we employed its structural features to discover potential inhibitors. On the other hand, complementary and alternative medicines (CAMs) have been used for the treatment of numerous diseases with little side effects. In this regard, Bacopa monnieri extracts have been extensively used to treat neurological disorders because of their neuroprotective roles. The plant extract is used as a memory enhancer and a brain tonic. Bacopaside II is a major component of Bacopa monnieri; thus, we studied its inhibitory effects and binding affinity towards the MARK4. Bacopaside II show a considerable binding affinity for MARK4 (K = 107 M-1) and inhibited kinase activity with an IC50 value of 5.4 µM. To get atomistic insights into the binding mechanism, we performed Molecular dynamics (MD) simulation studies for 100 ns. Bacopaside II binds strongly to the active site pocket residues of MARK4 and a number of hydrogen bonds remain stable throughout the MD trajectory. Our findings provide the basis for the therapeutic implication of Bacopaside and its derivatives in MARK4-related neurodegenerative diseases, especially AD and neuroinflammation.

HspB8 interacts with BAG3 in a "native-like" conformation forming a complex that displays chaperone-like activity.

The HspB8-BAG3 complex plays an important role in the protein quality control acting alone or within multi-components complexes. To clarify the mechanism underlying its activity, in this work we used biochemical and biophysical approaches to study the tendency of both proteins to auto-assemble and to form the complex. Solubility and Thioflavin T assays, Fourier transform infrared spectroscopy and atomic force microscopy analyses clearly showed the tendency of HspB8 to self-assemble at high concentration and to form oligomers in a "native-like" conformation; otherwise, BAG3 aggregates poorly. Noteworthy, also HspB8 and BAG3 associate in a "native-like" conformation, forming a stable complex. Furthermore, the high difference between dissociation constant values of HspB8-HspB8 interaction with respect to the binding to BAG3 obtained by surface plasmon resonance confirms that HspB8 is an obligated partner of BAG3 in vivo. Lastly, both proteins alone or in the complex are able to bind and affect the aggregation of the Josephin domain, the structured domain that triggers the ataxin-3 fibrillation. In particular, the complex displayed higher activity than HspB8 alone. All this considered, we can assert that the two proteins form a stable assembly with chaperone-like activity that could contribute to the physiological role of the complex in vivo.

QSAR study of tetrahydropteridin derivatives as polo-like kinase 1(PLK1) Inhibitors with molecular docking and dynamics study.

PLK1 is the key target for dealing with different cancer because it plays an important role in cell proliferation. According to the regulation of OECD, a QSAR model was developed from a dataset of 68 tetrahydropteridin derivatives. Three descriptors (maxHaaCH, ATSC7i, AATS7m) were considered for the development of the QSAR model. The reliability and predictability of the developed QSAR model were evaluated by various statistical parameters (r2 = 0.8213, r2ext = 0.8771 and CCCext = 0.9364). The maxHaaCH descriptor is positively correlated to pIC50 whereas, the ATSC7i and AATS7m are negatively correlated with pIC50. The QSAR model explains all the structural features and shows a good correlation with the activity. Based on molecular modelling techniques, five compounds (D1-D5) were designed. Molecular docking and dynamics studies of the most active compound were performed with PDB ID: 2RKU. The results of the present investigation may be employed to identify and develop effective inhibitors for the treatment of PLK1-related pathophysiological disorders.

Novel phytochemical inhibitors targeting monkeypox virus thymidine and serine/threonine kinase: integrating computational modeling and molecular dynamics simulation.

Due to the rapid spread of the monkeypox virus and rise in the number of cases, there is an urgent need for the development of effective drugs against the infection. Serine/threonine protein kinase (Ser/Thr kinase) and Thymidine Kinase (TK) plays an imperative role in the replication and virulence of monkeypox virus and thus is deliberated as an attractive target in anti-viral drug development. In the present study, the 3D structure of monkeypox virus Ser/Thr kinase and TK was generated via molecular modeling techniques and performed their thorough structural analysis. We have screened potent anti-viral phytochemicals from the literature to inhibit Ser/Thr kinase and TK. As part of the initial screening, the physicochemical properties of the compounds were examined. Following this, a structure-based molecular docking technique was used to select compounds based on their binding affinity towards Ser/Thr kinase and TK. In order to find more potent hits against Ser/Thr kinase and TK, further examinations of ADMET properties, PAINS patterns and blood-brain barrier permeability were conducted. As a result, thalimonine and galanthamine were identified from the screening process bearing appreciable binding affinity towards Ser/Thr kinase and TK respectively, which showed a worthy set of drug-like properties. In the end, molecular dynamics simulations were performed for 100 ns, which showed decent stability of both protein-ligand complex throughout the trajectory. Due to the possibility that both monkeypox virus target proteins may be inhibited by thalimonine and galanthamine, our study highlights the need to investigate in vivo effects of thalimonine and galanthamine.Communicated by Ramaswamy H. Sarma.

Structure and regulation of the myotonic dystrophy kinase-related Cdc42-binding kinase.

Protein kinases of the dystonia myotonica protein kinase (DMPK) family are critical regulators of actomyosin contractility in cells. The DMPK kinase MRCK1 is required for the activation of myosin, leading to the development of cortical tension, apical constriction, and early gastrulation. Here, we present the structure, conformation, and membrane-binding properties of Caenorhabditis elegans MRCK1. MRCK1 forms a homodimer with N-terminal kinase domains, a parallel coiled coil of 55 nm, and a C-terminal tripartite module of C1, pleckstrin homology (PH), and citron homology (CNH) domains. We report the high-resolution structure of the membrane-binding C1-PH-CNH module of MRCK1 and, using high-throughput and conventional liposome-binding assays, determine its binding to specific phospholipids. We further characterize the interaction of the C-terminal CRIB motif with Cdc42. The length of the coiled-coil domain of DMPK kinases is remarkably conserved over millions of years of evolution, suggesting that they may function as molecular rulers to position kinase activity at a fixed distance from the membrane.

Discovery of Polo-like Kinase 4 Inhibitors for the Treatment of Cancer: A Mini Patent Review.

Polo-like kinase 4 (PLK4), a serine/threonine kinase, is a member of the PLK family. As a key regulator of the cell cycle, PLK4 controls centrosome duplication and mitosis. Abnormal PLK4's function can induce centrosome amplification, leading to tumorigenesis, therefore, PLK4 has been regarded as a promising target for cancer therapy, and PLK4 inhibitors have potentials to treat multiple cancers and other PLK4-associated human disorders, such as myelodysplastic syndrome. In addition, PLK4 may function as a DNA-damage sensitizer, therefore improving the efficacy of chemotherapy. To date, some small-molecule inhibitors with different chemical scaffolds targeting PLK4 have been reported, among which, CFI-400945 has entered clinical trials for the treatment of various solid tumors, myeloid leukemia, and myelodysplastic syndrome. In this review, the structure and biological functions of PLK4 with other homologous PLKs are compared; the roles of PLK4 in different cancers are reviewed; and PLK4 inhibitors disclosed in patent or literature are summarized. Used alone or in combination with other anticancer drugs in preclinical and clinical studies, PLK4 inhibitors have shown significant efficacy in the treatment of different cancers, demonstrating that PLK4 could be a critical target for cancer diagnosis and therapy. However, our understanding of PLK4 is still limited, and novel mechanisms of PLK4 should be identified in future studies.

Intracellular Ion Control of WNK Signaling.

The with no lysine (K) (WNK) kinases are an evolutionarily ancient group of kinases with atypical placement of the catalytic lysine and diverse physiological roles. Recent studies have shown that WNKs are directly regulated by chloride, potassium, and osmotic pressure. Here, we review the discovery of WNKs as chloride-sensitive kinases and discuss physiological contexts in which chloride regulation of WNKs has been demonstrated. These include the kidney, pancreatic duct, neurons, and inflammatory cells. We discuss the interdependent relationship of osmotic pressure and intracellular chloride in cell volume regulation. We review the recent demonstration of potassium regulation of WNKs and speculate on possible physiological roles. Finally, structural and mechanistic aspects of intracellular ion and osmotic pressure regulation of WNKs are discussed.

Salvianolic acid B, a new type I IRE1 kinase inhibitor, abrogates AngII-induced angiogenesis by interacting with IRE1 in its active conformation.

Angiotensin II (AngII)-mediated pathological angiogenesis is one of the important factors promoting the progression of atherosclerosis, tumour metastasis, and diabetic retinopathy. Here, we first demonstrate that salvianolic acid B (Sal B) attenuated AngII-induced angiogenesis by downregulating the IRE1/ASK1/JNK/p38MAPK signalling pathway and protected vascular endothelial cells from hypoxia-induced damage. These pharmacological consequences could be ascribed to the unique interactions between Sal B and the ATP-binding cavity of IREIα, leading to bi-directional roles of IRE1 kinase and endonuclease activity; this may possibly be one of the essential mechanisms of the bi-directional regulation of angiogenesis in different conditions. Moreover, our results indicated that IRE1 was a novel anti-angiogenesis target and type I IRE1 kinase inhibitor (e.g., Sal B, APY29) and might be a potentially eligible low-toxicity drug for treating AngII-mediated pathological angiogenesis.