scholarly journals Phosphorylation by PKC and PKA regulate the kinase activity and downstream signaling of WNK4

2017 ◽  
Vol 114 (5) ◽  
pp. E879-E886 ◽  
Author(s):  
Maria Castañeda-Bueno ◽  
Juan Pablo Arroyo ◽  
Junhui Zhang ◽  
Jeremy Puthumana ◽  
Orlando Yarborough ◽  
...  
Keyword(s):  
Kinase Activity ◽  
Cultured Cells ◽  
Kinase Domain ◽  
Tandem Mass ◽  
Volume Depletion ◽  
Kinase Activation ◽  
Downstream Signaling ◽  
Electrolyte Homeostasis

With-no-lysine kinase 4 (WNK4) regulates electrolyte homeostasis and blood pressure. WNK4 phosphorylates the kinases SPAK (Ste20-related proline alanine-rich kinase) and OSR1 (oxidative stress responsive kinase), which then phosphorylate and activate the renal Na-Cl cotransporter (NCC). WNK4 levels are regulated by binding to Kelch-like 3, targeting WNK4 for ubiquitylation and degradation. Phosphorylation of Kelch-like 3 by PKC or PKA downstream of AngII or vasopressin signaling, respectively, abrogates binding. We tested whether these pathways also affect WNK4 phosphorylation and activity. By tandem mass spectrometry and use of phosphosite-specific antibodies, we identified five WNK4 sites (S47, S64, S1169, S1180, S1196) that are phosphorylated downstream of AngII signaling in cultured cells and in vitro by PKC and PKA. Phosphorylation at S64 and S1196 promoted phosphorylation of the WNK4 kinase T-loop at S332, which is required for kinase activation, and increased phosphorylation of SPAK. Volume depletion induced phosphorylation of these sites in vivo, predominantly in the distal convoluted tubule. Thus, AngII, in addition to increasing WNK4 levels, also modulates WNK4 kinase activity via phosphorylation of sites outside the kinase domain.

Nuclear receptor-binding protein 1: a novel tumour suppressor and pseudokinase

2013 ◽  
Vol 41 (4) ◽  
pp. 1055-1060 ◽  
Author(s):  
Jason S. Kerr ◽  
Catherine H. Wilson
Keyword(s):  
Nuclear Receptor ◽  
Receptor Binding ◽  
Kinase Activity ◽  
Binding Protein ◽  
Kinase Domain ◽  
Present Review ◽  
Critical Components ◽  
Receptor Binding Protein

Pseudokinases are a class of kinases which are structurally designated as lacking kinase activity. Despite the lack of kinase domain sequence conservation, there is increasing evidence that a number of pseudokinases retain kinase activity and/or have critical cellular functions, casting aside previous notions that pseudokinases simply exist as redundant kinases. Moreover, a number of recent studies have implicated pseudokinases as critical components in cancer formation and progression. The present review discusses the interactions and potential functions that nuclear receptor-binding protein 1, a pseudokinase recently described to have a tumour-suppressive role in cancer, may play in cellular homoeostasis and protein regulation. The recent findings highlighted in the present review emphasize the requirement to fully determine the function of pseudokinases in vitro and in vivo, the understanding of which may ultimately uncover new directions for drug discovery.

scholarly journals Negative regulation of Raf-1 by phosphorylation of serine 621.

1996 ◽  
Vol 16 (10) ◽  
pp. 5409-5418 ◽  
Author(s):  
H Mischak ◽  
T Seitz ◽  
P Janosch ◽  
M Eulitz ◽  
H Steen ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Kinase Activity ◽  
Phosphorylation Site ◽  
Kinase Domain ◽  
Negative Regulation ◽  
Catalytic Function ◽  
Dependent Protein ◽  
The One

The elevation of cyclic AMP (cAMP) levels in the cell downregulates the activity of the Raf-1 kinase. It has been suggested that this effect is due to the activation of cAMP-dependent protein kinase (PKA), which can directly phosphorylate Raf-1 in vitro. In this study, we confirmed this hypothesis by coexpressing Raf-1 with the constitutively active catalytic subunit of PKA, which could fully reproduce the inhibition previously achieved by cAMP. PKA-phosphorylated Raf-1 exhibits a reduced affinity for GTP-loaded Ras as well as impaired catalytic activity. As the binding to GTP-loaded Ras induces Raf-1 activation in the cell, we examined which mechanism is required for PKA-mediated Raf-1 inhibition in vivo. A Raf-1 point mutant (RafR89L), which is unable to bind Ras, as well as the isolated Raf-1 kinase domain were still fully susceptible to inhibition by PKA, demonstrating that the phosphorylation of the Raf-1 kinase suffices for inhibition. By the use of mass spectroscopy and point mutants, PKA phosphorylation site was mapped to a single site in the Raf-1 kinase domain, serine 621. Replacement of serine 621 by alanine or cysteine or destruction of the PKA consensus motif by changing arginine 618 resulted in the loss of catalytic activity. Notably, a mutation of serine 619 to alanine did not significantly affect kinase activity or regulation by activators or PKA. Changing serine 621 to aspartic acid yielded a Raf-1 protein which, when expressed to high levels in Sf-9 insect cells, retained a very low inducible kinase activity that was resistant to PKA downregulation. The purified Raf-1 kinase domain displayed slow autophosphorylation of serine 621, which correlated with a decrease in catalytic function. The Raf-1 kinase domain activated by tyrosine phosphorylation could be downregulated by PKA. Specific removal of the phosphate residue at serine 621 reactivated the catalytic activity. These results are most consistent with a dual role of serine 621. On the one hand, serine 621 appears essential for catalytic activity; on the other hand, it serves as a phosphorylation site which confers negative regulation.

scholarly journals Src acts as the target of matrine to inhibit the proliferation of cancer cells by regulating phosphorylation signaling pathways

2020 ◽  
Author(s):  
Xi Zhang ◽  
Hui Xu ◽  
Xiaoyang Bi ◽  
Guoqing Hou ◽  
Andong Liu ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Cancer Cells ◽  
Signaling Pathways ◽  
Kinase Activity ◽  
Src Kinase ◽  
Kinase Domain ◽  
Akt Phosphorylation ◽  
In Vivo Experiments

Background and Purpose: Identification of accurate targets is essential for a successful development of targeted therapy in cancer. Studies have shown that matrine has antitumor activity against many types of cancers. However, the direct target in cancer cells of its anticancer effect has not been identified. The purpose of this study was to find the molecular target of matrine to inhibit the proliferation of cancer cells and explore its mechanism of action. Experimental Approach: The effect of matrine on the proliferation of cancer cells were examined by MTT assay. Pull-down assay and liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) were performed to explore the target of matrine. A series of in vitro and in vivo experiments were conducted to reveal the mechanisms by which matrine targeted Src to regulate the downstream signaling pathways of Src in cancer cells. Key Results: Herein we showed that matrine inhibited the proliferation of cancer in vitro and in vivo. Pull-down assay with matrine-amino coupling resins (MA beads) and LC-MS/MS identified Src as the target of matrine. Src kinase domain is required for its interaction with matrine and Ala392 in the kinase domain participated in matrine-Src interaction. Intriguingly, matrine was proven to inhibit Src kinase activity in a non-ATP-competitive manner by blocking the autophosphorylation of Tyr419. Matrine down-regulated the phosphorylation levels of MAPK/ERK, JAK2/STAT3 and PI3K/Akt signaling pathways. Conclusions and Implications: Collectively, matrine targeted Src, inhibited kinase activity and down-regulated its downstream MAPK/ERK, JAK2/STAT3 and PI3K/Akt phosphorylation signaling pathways to inhibit the proliferation of cancer cells.

scholarly journals Discovery of a Potent RIPK3 Inhibitor for the Amelioration of Necroptosis-Associated Inflammatory Injury

2020 ◽  
Vol 8 ◽  
Author(s):  
Kaijiang Xia ◽  
Fang Zhu ◽  
Chengkui Yang ◽  
Shuwei Wu ◽  
Yu Lin ◽  
...  
Keyword(s):  
Kinase Activity ◽  
Potent Inhibitor ◽  
Inflammatory Diseases ◽  
Death Receptor ◽  
Kinase Domain ◽  
Pharmacokinetic Parameters ◽  
Cellular Activation ◽  
Regulated Necrosis

Necroptosis is a form of regulated necrosis that requires the activation of receptor-interacting kinase 3 (RIPK3 or RIP3) and its phosphorylation of the substrate MLKL (mixed lineage kinase domain-like protein). Necroptosis has emerged as important cell death involved in the pathogenesis of various diseases including inflammatory diseases, degenerative diseases, and cancer. Here, we discovered a small molecule Zharp-99 as a potent inhibitor of necroptosis through blocking the kinase activity of RIPK3. Zharp-99 efficiently blocks necroptosis induced by ligands of the death receptor and Toll-like receptor as well as viral infection in human, rat and mouse cells. Zharp-99 strongly inhibits cellular activation of RIPK3, and MLKL upon necroptosis stimuli. Zharp-99 directly blocks the kinase activity of RIPK3 without affecting RIPK1 kinase activity at the tested concentration. Importantly, Zharp-99 exerts effective protection against TNF-α induced systemic inflammatory response syndrome in the mouse model. Zharp-99 displays favorable in vitro safety profiles and in vivo pharmacokinetic parameters. Thus, our study demonstrates Zharp-99 as a potent inhibitor of RIPK3 kinase and also highlights its potential for further development of new approaches for treating necroptosis-associated inflammatory disorders.

scholarly journals AMPK directly activates mTORC2 to promote cell survival during acute energetic stress

2019 ◽  
Vol 12 (585) ◽  
pp. eaav3249 ◽  
Author(s):  
Dubek Kazyken ◽  
Brian Magnuson ◽  
Cagri Bodur ◽  
Hugo A. Acosta-Jaquez ◽  
Deqiang Zhang ◽  
...  
Keyword(s):  
Cell Survival ◽  
Cultured Cells ◽  
Kinase Assay ◽  
Dependent Manner ◽  
Downstream Signaling ◽  
Energetic Stress ◽  
Diabetes Drug ◽  
Tumor Suppressive Function

AMP-activated protein kinase (AMPK) senses energetic stress and, in turn, promotes catabolic and suppresses anabolic metabolism coordinately to restore energy balance. We found that a diverse array of AMPK activators increased mTOR complex 2 (mTORC2) signaling in an AMPK-dependent manner in cultured cells. Activation of AMPK with the type 2 diabetes drug metformin (GlucoPhage) also increased mTORC2 signaling in liver in vivo and in primary hepatocytes in an AMPK-dependent manner. AMPK-mediated activation of mTORC2 did not result from AMPK-mediated suppression of mTORC1 and thus reduced negative feedback on PI3K flux. Rather, AMPK associated with and directly phosphorylated mTORC2 (mTOR in complex with rictor). As determined by two-stage in vitro kinase assay, phosphorylation of mTORC2 by recombinant AMPK was sufficient to increase mTORC2 catalytic activity toward Akt. Hence, AMPK phosphorylated mTORC2 components directly to increase mTORC2 activity and downstream signaling. Functionally, inactivation of AMPK, mTORC2, and Akt increased apoptosis during acute energetic stress. By showing that AMPK activates mTORC2 to increase cell survival, these data provide a potential mechanism for how AMPK paradoxically promotes tumorigenesis in certain contexts despite its tumor-suppressive function through inhibition of growth-promoting mTORC1. Collectively, these data unveil mTORC2 as a target of AMPK and the AMPK-mTORC2 axis as a promoter of cell survival during energetic stress.

scholarly journals Twitchin kinase inhibits muscle activity

2017 ◽  
Vol 28 (12) ◽  
pp. 1591-1600 ◽  
Author(s):  
Yohei Matsunaga ◽  
Hyundoo Hwang ◽  
Barbara Franke ◽  
Rhys Williams ◽  
McKenna Penley ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Kinase Activity ◽  
Kinase Domain ◽  
Wild Type ◽  
Competitive Fitness ◽  
Binding Partners ◽  
Fibronectin Domains ◽  
First Time

Muscle sarcomeres contain giant polypeptides composed of multiple immunoglobulin and fibronectin domains and one or two protein kinase domains. Although binding partners for a number of this family’s kinase domains have been identified, the catalytic necessity of these kinase domains remains unknown. In addition, various members of this kinase family are suspected pseudokinases with no or little activity. Here we address catalytic necessity for the first time, using the prototypic invertebrate representative twitchin (UNC-22) from Caenorhabditis elegans. In in vitro experiments, change of a conserved lysine (K) that is involved in ATP coordination to alanine (A) resulted in elimination of kinase activity without affecting the overall structure of the kinase domain. The same mutation, unc-22(sf21), was generated in the endogenous twitchin gene. The unc-22(sf21) worms have well-organized sarcomeres. However, unc-22(sf21) mutants move faster than wild-type worms and, by optogenetic experiments, contract more. Wild-type nematodes exhibited greater competitive fitness than unc-22(sf21) mutants. Thus the catalytic activity of twitchin kinase has a role in vivo, where it inhibits muscle activity and is likely maintained by selection.

scholarly journals Kinase Function of Brassinosteroid Receptor Specified by Two Allosterically Regulated Subdomains

2022 ◽  
Vol 12 ◽  
Author(s):  
Khawar Ali ◽  
Wenjuan Li ◽  
Yaopeng Qin ◽  
Shanshan Wang ◽  
Lijie Feng ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Kinase Activity ◽  
The Other ◽  
Activation Loop ◽  
Biological Functions ◽  
Kinase Activation ◽  
Downstream Signaling ◽  
Signaling Function ◽  
Insight Into

Plants acquire the ability to adapt to the environment using transmembrane receptor-like kinases (RLKs) to sense the challenges from their surroundings and respond appropriately. RLKs perceive a variety of ligands through their variable extracellular domains (ECDs) that activate the highly conserved intracellular kinase domains (KDs) to control distinct biological functions through a well-developed downstream signaling cascade. A new study has emerged that brassinosteroid-insensitive 1 (BRI1) family and excess microsporocytes 1 (EMS1) but not GASSHO1 (GSO1) and other RLKs control distinct biological functions through the same signaling pathway, raising a question how the signaling pathway represented by BRI1 is specified. Here, we confirm that BRI1-KD is not functionally replaceable by GSO1-KD since the chimeric BRI1-GSO1 cannot rescue bri1 mutants. We then identify two subdomains S1 and S2. BRI1 with its S1 and S2 substituted by that of GSO1 cannot rescue bri1 mutants. Conversely, chimeric BRI1-GSO1 with its S1 and S2 substituted by that of BRI1 can rescue bri1 mutants, suggesting that S1 and S2 are the sufficient requirements to specify the signaling function of BRI1. Consequently, all the other subdomains in the KD of BRI1 are functionally replaceable by that of GSO1 although the in vitro kinase activities vary after replacements, suggesting their functional robustness and mutational plasticity with diverse kinase activity. Interestingly, S1 contains αC-β4 loop as an allosteric hotspot and S2 includes kinase activation loop, proposedly regulating kinase activities. Further analysis reveals that this specific function requires β4 and β5 in addition to αC-β4 loop in S1. We, therefore, suggest that BRI1 specifies its kinase function through an allosteric regulation of these two subdomains to control its distinct biological functions, providing a new insight into the kinase evolution.

scholarly journals CK1α, CK1δ, and CK1ε are necrosome components which phosphorylate serine 227 of human RIPK3 to activate necroptosis

2020 ◽  
Vol 117 (4) ◽  
pp. 1962-1970 ◽  
Author(s):  
Sarah Hanna-Addams ◽  
Shuzhen Liu ◽  
Hua Liu ◽  
She Chen ◽  
Zhigao Wang
Keyword(s):  
Kinase Activity ◽  
Kinase Domain ◽  
Necrotic Cell ◽  
Interacting Protein ◽  
Casein Kinase 1 ◽  
Mixed Lineage Kinase ◽  
Recognition Motif ◽  
Cell Death Pathway

Necroptosis is a regulated necrotic cell death pathway, mediated by a supermolecular complex called the necrosome, which contains receptor-interacting protein kinase 1 and 3 (RIPK1, RIPK3) and mixed-lineage kinase domain-like protein (MLKL). Phosphorylation of human RIPK3 at serine 227 (S227) has been shown to be required for downstream MLKL binding and necroptosis progression. Tandem immunoprecipitation of RIPK3 reveals that casein kinase 1 (CK1) family proteins associate with the necrosome upon necroptosis induction, and this interaction depends on the kinase activity of RIPK3. In addition, CK1 proteins colocalize with RIPK3 puncta during necroptosis. Importantly, CK1 proteins directly phosphorylate RIPK3 at S227 in vitro and in vivo. Loss of CK1 proteins abolishes S227 phosphorylation and blocks necroptosis. Furthermore, a RIPK3 mutant with mutations in the CK1 recognition motif fails to be phosphorylated at S227, does not bind or phosphorylate MLKL, and is unable to activate necroptosis. These results strongly suggest that CK1 proteins are necrosome components which are responsible for RIPK3-S227 phosphorylation.

Kinase activity of mutant LRRK2 manifests differently in hetero-dimeric vs. homo-dimeric complexes

2019 ◽  
Vol 476 (3) ◽  
pp. 559-579 ◽  
Author(s):  
Emmanouela Leandrou ◽  
Eliana Markidi ◽  
Anna Memou ◽  
Katerina Melachroinou ◽  
Elisa Greggio ◽  
...  
Keyword(s):  
Kinase Activity ◽  
Cultured Cells ◽  
Kinase Domain ◽  
Small Gtpase ◽  
Wild Type ◽  
Risk Variant ◽  
Dimeric Complexes ◽  
Mutant Lrrk2 ◽  
Mutant Forms

Abstract The Parkinson's disease (PD) protein leucine-rich repeat kinase 2 (LRRK2) exists as a mixture of monomeric and dimeric species, with its kinase activity highly concentrated in the dimeric conformation of the enzyme. We have adapted the proximity biotinylation approach to study the formation and activity of LRRK2 dimers isolated from cultured cells. We find that the R1441C and I2020T mutations both enhance the rate of dimer formation, whereas, the G2019S kinase domain mutant is similar to WT, and the G2385R risk factor variant de-stabilizes dimers. Interestingly, we find a marked departure in the kinase activity between G2019S–LRRK2 homo-dimers and wild-type-G2019S hetero-dimers. While the homo-dimeric G2019S–LRRK2 exhibits the typical robust enhancement of kinase activity, hetero-dimers comprised of wild-type (WT) and G2019S–LRRK2 exhibit kinase activity similar to WT. Dimeric complexes of specific mutant forms of LRRK2 show reduced stability following an in vitro kinase reaction, in LRRK2 mutants for which the kinase activity is similar to WT. Phosphorylation of the small GTPase Rab10 follows a similar pattern in which hetero-dimers of WT and mutant LRRK2 show similar levels of phosphorylation of Rab10 to WT homo-dimers; while the levels of pRab10 are significantly increased in cells expressing mutant homo-dimers. Interestingly, while the risk variant G2385R leads to a de-stabilization of LRRK2 dimers, those dimers possess significantly elevated kinase activity. The vast majority of familial LRRK2-dependent PD cases are heterozygous; thus, these findings raise the possibility that a crucial factor in disease pathogenesis may be the accumulation of homo-dimeric mutant LRRK2.

scholarly journals Src Acts as the Target of Matrine to Inhibit the Proliferation of Cancer Cells by Regulating Phosphorylation Signaling Pathways

2020 ◽  
Author(s):  
Xi Zhang ◽  
Hui Xu ◽  
Xiaoyang Bi ◽  
Guoqing Hou ◽  
Andong Liu ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Cancer Cells ◽  
Signaling Pathways ◽  
Kinase Activity ◽  
Src Kinase ◽  
Kinase Domain ◽  
Competitive Binding Assay ◽  
In Vivo Experiments

Abstract Background: Identification of accurate targets is essential for a successful development of targeted therapy in cancer. Studies have shown that matrine has antitumor activity against many types of cancers, including lung cancer, breast cancer, liver cancer, pancreatic cancer, ovarian cancer and leukemia, etc. However, the direct target in cancer cells of its anticancer effect has not been identified. The purpose of this study was to find the molecular target of matrine to inhibit the proliferation of cancer cells and explore its mechanism of action. Methods: The effect of matrine on the proliferation of cancer cells were examined by MTT assay. Pull-down assay with matrine-amino coupling resins (MA beads) and liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) were performed to explore the target of matrine. The target of matrine was further validated by competitive binding assay, cellular thermal shift assay (CETSA) and drug affinity responsive target stability (DARTS). A series of in vitro and in vivo experiments were conducted to reveal the mechanisms by which matrine targeted Src to regulate the downstream signaling pathways of Src in cancer cells. Results: Herein we showed that matrine inhibited the proliferation of cancer in vitro and in vivo. Pull-down assay with MA beads and LC-MS/MS identified Src as the target of matrine. The findings provided solid evidences that matrine directly bound to Src and Src kinase domain is required for its interaction with matrine and Ala392 in the kinase domain participated in matrine-Src interaction. Intriguingly, matrine was proven to inhibit Src kinase activity in a non-ATP-competitive manner by blocking the autophosphorylation of Tyr419 in Src kinase domain. Matrine down-regulated the phosphorylation levels of MAPK/ERK, JAK2/STAT3 and PI3K/Akt signaling pathways via targeting Src.Conclusions: Collectively, matrine targeted Src, inhibited its kinase activity and down-regulated its downstream MAPK/ERK, JAK2/STAT3 and PI3K/Akt phosphorylation signaling pathways to inhibit the proliferation of cancer cells.

Sign in / Sign up

Export Citation Format

Share Document