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Sample records for protein kinases reveals

  1. The crystal structure of choline kinase reveals a eukaryotic protein kinase fold

    SciTech Connect

    Peisach, D.; Gee, P.; Kent, K.; Xu, Z.

    2010-03-08

    Choline kinase catalyzes the ATP-dependent phosphorylation of choline, the first committed step in the CDP-choline pathway for the biosynthesis of phosphatidylcholine. The 2.0 {angstrom} crystal structure of a choline kinase from C. elegans (CKA-2) reveals that the enzyme is a homodimeric protein with each monomer organized into a two-domain fold. The structure is remarkably similar to those of protein kinases and aminoglycoside phosphotransferases, despite no significant similarity in amino acid sequence. Comparisons to the structures of other kinases suggest that ATP binds to CKA-2 in a pocket formed by highly conserved and catalytically important residues. In addition, a choline binding site is proposed to be near the ATP binding pocket and formed by several structurally flexible loops.

  2. In silico analysis reveals 75 members of mitogen-activated protein kinase kinase kinase gene family in rice.

    PubMed

    Rao, Kudupudi Prabhakara; Richa, Tambi; Kumar, Kundan; Raghuram, Badmi; Sinha, Alok Krishna

    2010-06-01

    Mitogen-Activated Protein Kinase Kinase Kinases (MAPKKKs) are important components of MAPK cascades, which are universal signal transduction modules and play important role in plant growth and development. In the sequenced Arabidopsis genome 80 MAPKKKs were identified and currently being analysed for its role in different stress. In rice, economically important monocot cereal crop only five MAPKKKs were identified so far. In this study using computational analysis of sequenced rice genome we have identified 75 MAPKKKs. EST hits and full-length cDNA sequences (from KOME or Genbank database) of 75 MAPKKKs supported their existence. Phylogenetic analyses of MAPKKKs from rice and Arabidopsis have classified them into three subgroups, which include Raf, ZIK and MEKK. Conserved motifs in the deduced amino acid sequences of rice MAPKKKs strongly supported their identity as members of Raf, ZIK and MEKK subfamilies. Further expression analysis of the MAPKKKs in MPSS database revealed that their transcripts were differentially regulated in various stress and tissue-specific libraries.

  3. Structures of apicomplexan calcium-dependent protein kinases reveal mechanism of activation by calcium

    SciTech Connect

    Wernimont, Amy K; Artz, Jennifer D.; Jr, Patrick Finerty; Lin, Yu-Hui; Amani, Mehrnaz; Allali-Hassani, Abdellah; Senisterra, Guillermo; Vedadi, Masoud; Tempel, Wolfram; Mackenzie, Farrell; Chau, Irene; Lourido, Sebastian; Sibley, L. David; Hui, Raymond

    2010-09-21

    Calcium-dependent protein kinases (CDPKs) have pivotal roles in the calcium-signaling pathway in plants, ciliates and apicomplexan parasites and comprise a calmodulin-dependent kinase (CaMK)-like kinase domain regulated by a calcium-binding domain in the C terminus. To understand this intramolecular mechanism of activation, we solved the structures of the autoinhibited (apo) and activated (calcium-bound) conformations of CDPKs from the apicomplexan parasites Toxoplasma gondii and Cryptosporidium parvum. In the apo form, the C-terminal CDPK activation domain (CAD) resembles a calmodulin protein with an unexpected long helix in the N terminus that inhibits the kinase domain in the same manner as CaMKII. Calcium binding triggers the reorganization of the CAD into a highly intricate fold, leading to its relocation around the base of the kinase domain to a site remote from the substrate binding site. This large conformational change constitutes a distinct mechanism in calcium signal-transduction pathways.

  4. Protein synthesis inhibitors reveal differential regulation of mitogen-activated protein kinase and stress-activated protein kinase pathways that converge on Elk-1.

    PubMed Central

    Zinck, R; Cahill, M A; Kracht, M; Sachsenmaier, C; Hipskind, R A; Nordheim, A

    1995-01-01

    Inhibitors of protein synthesis, such as anisomycin and cycloheximide, lead to superinduction of immediate-early genes. We demonstrate that these two drugs activate intracellular signaling pathways involving both the mitogen-activated protein kinase (MAPK) and stress-activated protein kinase (SAPK) cascades. The activation of either pathway correlates with phosphorylation of the c-fos regulatory transcription factor Elk-1. In HeLa cells, anisomycin stabilizes c-fos mRNA when protein synthesis is inhibited to only 50%. Under these conditions, anisomycin, in contrast to cycloheximide, rapidly induces kinase activation and efficient Elk-1 phosphorylation. However, full inhibition of translation by either drug leads to prolonged activation of SAPK activity, while MAPK induction is transient. This correlates with prolonged Elk-1 phosphorylation and c-fos transcription. Elk-1 induction and c-fos activation are also observed in KB cells, in which anisomycin strongly induces SAPKs but not MAPKs. Purified p54 SAPK alpha efficiently phosphorylates the Elk-1 C-terminal domain in vitro and comigrates with anisomycin-activated kinases in in-gel kinase assays. Thus, Elk-1 provides a potential convergence point for the MAPK and SAPK signaling pathways. The activation of signal cascades and control of transcription factor function therefore represent prominent processes in immediate-early gene superinduction. PMID:7651411

  5. The Protein Architecture of Human Secretory Vesicles Reveals Differential Regulation of Signaling Molecule Secretion by Protein Kinases

    PubMed Central

    Taupenot, Laurent; Ziegler, Michael; O'Connor, Daniel T.; Ma, Qi; Smoot, Michael; Ideker, Trey; Hook, Vivian

    2012-01-01

    Secretory vesicles are required for release of chemical messengers to mediate intercellular signaling among human biological systems. It is necessary to define the organization of the protein architecture of the ‘human’ dense core secretory vesicles (DCSV) to understand mechanisms for secretion of signaling molecules essential for cellular regulatory processes. This study, therefore, conducted extensive quantitative proteomics and systems biology analyses of human DCSV purified from human pheochromocytoma. Over 600 human DCSV proteins were identified with quantitative evaluation of over 300 proteins, revealing that most proteins participate in producing peptide hormones and neurotransmitters, enzymes, and the secretory machinery. Systems biology analyses provided a model of interacting DCSV proteins, generating hypotheses for differential intracellular protein kinases A and C signaling pathways. Activation of cellular PKA and PKC pathways resulted in differential secretion of neuropeptides, catecholamines, and β-amyloid of Alzheimer's disease for mediating cell-cell communication. This is the first study to define a model of the protein architecture of human DCSV for human disease and health. PMID:22916103

  6. A comprehensive protein-protein interactome for yeast PAS kinase 1 reveals direct inhibition of respiration through the phosphorylation of Cbf1.

    PubMed

    DeMille, Desiree; Bikman, Benjamin T; Mathis, Andrew D; Prince, John T; Mackay, Jordan T; Sowa, Steven W; Hall, Tacie D; Grose, Julianne H

    2014-07-15

    Per-Arnt-Sim (PAS) kinase is a sensory protein kinase required for glucose homeostasis in yeast, mice, and humans, yet little is known about the molecular mechanisms of its function. Using both yeast two-hybrid and copurification approaches, we identified the protein-protein interactome for yeast PAS kinase 1 (Psk1), revealing 93 novel putative protein binding partners. Several of the Psk1 binding partners expand the role of PAS kinase in glucose homeostasis, including new pathways involved in mitochondrial metabolism. In addition, the interactome suggests novel roles for PAS kinase in cell growth (gene/protein expression, replication/cell division, and protein modification and degradation), vacuole function, and stress tolerance. In vitro kinase studies using a subset of 25 of these binding partners identified Mot3, Zds1, Utr1, and Cbf1 as substrates. Further evidence is provided for the in vivo phosphorylation of Cbf1 at T211/T212 and for the subsequent inhibition of respiration. This respiratory role of PAS kinase is consistent with the reported hypermetabolism of PAS kinase-deficient mice, identifying a possible molecular mechanism and solidifying the evolutionary importance of PAS kinase in the regulation of glucose homeostasis.

  7. Microbial Protein-tyrosine Kinases*

    PubMed Central

    Chao, Joseph D.; Wong, Dennis; Av-Gay, Yossef

    2014-01-01

    Microbial ester kinases identified in the past 3 decades came as a surprise, as protein phosphorylation on Ser, Thr, and Tyr amino acids was thought to be unique to eukaryotes. Current analysis of available microbial genomes reveals that “eukaryote-like” protein kinases are prevalent in prokaryotes and can converge in the same signaling pathway with the classical microbial “two-component” systems. Most microbial tyrosine kinases lack the “eukaryotic” Hanks domain signature and are designated tyrosine kinases based upon their biochemical activity. These include the tyrosine kinases termed bacterial tyrosine kinases (BY-kinases), which are responsible for the majority of known bacterial tyrosine phosphorylation events. Although termed generally as bacterial tyrosine kinases, BY-kinases can be considered as one family belonging to the superfamily of prokaryotic protein-tyrosine kinases in bacteria. Other members of this superfamily include atypical “odd” tyrosine kinases with diverse mechanisms of protein phosphorylation and the “eukaryote-like” Hanks-type tyrosine kinases. Here, we discuss the distribution, phylogeny, and function of the various prokaryotic protein-tyrosine kinases, focusing on the recently discovered Mycobacterium tuberculosis PtkA and its relationship with other members of this diverse family of proteins. PMID:24554699

  8. Phosphoproteomic Profiling Reveals Epstein-Barr Virus Protein Kinase Integration of DNA Damage Response and Mitotic Signaling.

    PubMed

    Li, Renfeng; Liao, Gangling; Nirujogi, Raja Sekhar; Pinto, Sneha M; Shaw, Patrick G; Huang, Tai-Chung; Wan, Jun; Qian, Jiang; Gowda, Harsha; Wu, Xinyan; Lv, Dong-Wen; Zhang, Kun; Manda, Srikanth S; Pandey, Akhilesh; Hayward, S Diane

    2015-12-01

    Epstein-Barr virus (EBV) is etiologically linked to infectious mononucleosis and several human cancers. EBV encodes a conserved protein kinase BGLF4 that plays a key role in the viral life cycle. To provide new insight into the host proteins regulated by BGLF4, we utilized stable isotope labeling by amino acids in cell culture (SILAC)-based quantitative proteomics to compare site-specific phosphorylation in BGLF4-expressing Akata B cells. Our analysis revealed BGLF4-mediated hyperphosphorylation of 3,046 unique sites corresponding to 1,328 proteins. Frequency analysis of these phosphosites revealed a proline-rich motif signature downstream of BGLF4, indicating a broader substrate recognition for BGLF4 than its cellular ortholog cyclin-dependent kinase 1 (CDK1). Further, motif analysis of the hyperphosphorylated sites revealed enrichment in ATM, ATR and Aurora kinase substrates while functional analyses revealed significant enrichment of pathways related to the DNA damage response (DDR), mitosis and cell cycle. Phosphorylation of proteins associated with the mitotic spindle assembly checkpoint (SAC) indicated checkpoint activation, an event that inactivates the anaphase promoting complex/cyclosome, APC/C. Furthermore, we demonstrated that BGLF4 binds to and directly phosphorylates the key cellular proteins PP1, MPS1 and CDC20 that lie upstream of SAC activation and APC/C inhibition. Consistent with APC/C inactivation, we found that BGLF4 stabilizes the expression of many known APC/C substrates. We also noted hyperphosphorylation of 22 proteins associated the nuclear pore complex, which may contribute to nuclear pore disassembly and SAC activation. A drug that inhibits mitotic checkpoint activation also suppressed the accumulation of extracellular EBV virus. Taken together, our data reveal that, in addition to the DDR, manipulation of mitotic kinase signaling and SAC activation are mechanisms associated with lytic EBV replication. All MS data have been deposited in

  9. Phosphoproteomic Profiling Reveals Epstein-Barr Virus Protein Kinase Integration of DNA Damage Response and Mitotic Signaling

    PubMed Central

    Li, Renfeng; Pinto, Sneha M.; Shaw, Patrick G.; Huang, Tai-Chung; Wan, Jun; Qian, Jiang; Gowda, Harsha; Wu, Xinyan; Lv, Dong-Wen; Zhang, Kun; Manda, Srikanth S.; Pandey, Akhilesh; Hayward, S. Diane

    2015-01-01

    Epstein-Barr virus (EBV) is etiologically linked to infectious mononucleosis and several human cancers. EBV encodes a conserved protein kinase BGLF4 that plays a key role in the viral life cycle. To provide new insight into the host proteins regulated by BGLF4, we utilized stable isotope labeling by amino acids in cell culture (SILAC)-based quantitative proteomics to compare site-specific phosphorylation in BGLF4-expressing Akata B cells. Our analysis revealed BGLF4-mediated hyperphosphorylation of 3,046 unique sites corresponding to 1,328 proteins. Frequency analysis of these phosphosites revealed a proline-rich motif signature downstream of BGLF4, indicating a broader substrate recognition for BGLF4 than its cellular ortholog cyclin-dependent kinase 1 (CDK1). Further, motif analysis of the hyperphosphorylated sites revealed enrichment in ATM, ATR and Aurora kinase substrates while functional analyses revealed significant enrichment of pathways related to the DNA damage response (DDR), mitosis and cell cycle. Phosphorylation of proteins associated with the mitotic spindle assembly checkpoint (SAC) indicated checkpoint activation, an event that inactivates the anaphase promoting complex/cyclosome, APC/C. Furthermore, we demonstrated that BGLF4 binds to and directly phosphorylates the key cellular proteins PP1, MPS1 and CDC20 that lie upstream of SAC activation and APC/C inhibition. Consistent with APC/C inactivation, we found that BGLF4 stabilizes the expression of many known APC/C substrates. We also noted hyperphosphorylation of 22 proteins associated the nuclear pore complex, which may contribute to nuclear pore disassembly and SAC activation. A drug that inhibits mitotic checkpoint activation also suppressed the accumulation of extracellular EBV virus. Taken together, our data reveal that, in addition to the DDR, manipulation of mitotic kinase signaling and SAC activation are mechanisms associated with lytic EBV replication. All MS data have been deposited in

  10. Functional Mapping of Protein Kinase A Reveals Its Importance in Adult Schistosoma mansoni Motor Activity

    PubMed Central

    de Saram, Paulu S. R.; Ressurreição, Margarida; Davies, Angela J.; Rollinson, David; Emery, Aidan M.; Walker, Anthony J.

    2013-01-01

    Cyclic AMP (cAMP)-dependent protein kinase/protein kinase A (PKA) is the major transducer of cAMP signalling in eukaryotic cells. Here, using laser scanning confocal microscopy and ‘smart’ anti-phospho PKA antibodies that exclusively detect activated PKA, we provide a detailed in situ analysis of PKA signalling in intact adult Schistosoma mansoni, a causative agent of debilitating human intestinal schistosomiasis. In both adult male and female worms, activated PKA was consistently found associated with the tegument, oral and ventral suckers, oesophagus and somatic musculature. In addition, the seminal vesicle and gynaecophoric canal muscles of the male displayed activated PKA whereas in female worms activated PKA localized to the ootype wall, the ovary, and the uterus particularly around eggs during expulsion. Exposure of live worms to the PKA activator forskolin (50 µM) resulted in striking PKA activation in the central and peripheral nervous system including at nerve endings at/near the tegument surface. Such neuronal PKA activation was also observed without forskolin treatment, but only in a single batch of worms. In addition, PKA activation within the central and peripheral nervous systems visibly increased within 15 min of worm-pair separation when compared to that observed in closely coupled worm pairs. Finally, exposure of adult worms to forskolin induced hyperkinesias in a time and dose dependent manner with 100 µM forskolin significantly increasing the frequency of gross worm movements to 5.3 times that of control worms (P≤0.001). Collectively these data are consistent with PKA playing a central part in motor activity and neuronal communication, and possibly interplay between these two systems in S. mansoni. This study, the first to localize a protein kinase when exclusively in an activated state in adult S. mansoni, provides valuable insight into the intricacies of functional protein kinase signalling in the context of whole schistosome physiology

  11. Functional mapping of protein kinase A reveals its importance in adult Schistosoma mansoni motor activity.

    PubMed

    de Saram, Paulu S R; Ressurreição, Margarida; Davies, Angela J; Rollinson, David; Emery, Aidan M; Walker, Anthony J

    2013-01-01

    Cyclic AMP (cAMP)-dependent protein kinase/protein kinase A (PKA) is the major transducer of cAMP signalling in eukaryotic cells. Here, using laser scanning confocal microscopy and 'smart' anti-phospho PKA antibodies that exclusively detect activated PKA, we provide a detailed in situ analysis of PKA signalling in intact adult Schistosoma mansoni, a causative agent of debilitating human intestinal schistosomiasis. In both adult male and female worms, activated PKA was consistently found associated with the tegument, oral and ventral suckers, oesophagus and somatic musculature. In addition, the seminal vesicle and gynaecophoric canal muscles of the male displayed activated PKA whereas in female worms activated PKA localized to the ootype wall, the ovary, and the uterus particularly around eggs during expulsion. Exposure of live worms to the PKA activator forskolin (50 µM) resulted in striking PKA activation in the central and peripheral nervous system including at nerve endings at/near the tegument surface. Such neuronal PKA activation was also observed without forskolin treatment, but only in a single batch of worms. In addition, PKA activation within the central and peripheral nervous systems visibly increased within 15 min of worm-pair separation when compared to that observed in closely coupled worm pairs. Finally, exposure of adult worms to forskolin induced hyperkinesias in a time and dose dependent manner with 100 µM forskolin significantly increasing the frequency of gross worm movements to 5.3 times that of control worms (P≤0.001). Collectively these data are consistent with PKA playing a central part in motor activity and neuronal communication, and possibly interplay between these two systems in S. mansoni. This study, the first to localize a protein kinase when exclusively in an activated state in adult S. mansoni, provides valuable insight into the intricacies of functional protein kinase signalling in the context of whole schistosome physiology.

  12. Phosphoproteomic analysis of protein kinase C signaling in Saccharomyces cerevisiae reveals Slt2 mitogen-activated protein kinase (MAPK)-dependent phosphorylation of eisosome core components.

    PubMed

    Mascaraque, Victoria; Hernáez, María Luisa; Jiménez-Sánchez, María; Hansen, Rasmus; Gil, Concha; Martín, Humberto; Cid, Víctor J; Molina, María

    2013-03-01

    The cell wall integrity (CWI) pathway of the model organism Saccharomyces cerevisiae has been thoroughly studied as a paradigm of the mitogen-activated protein kinase (MAPK) pathway. It consists of a classic MAPK module comprising the Bck1 MAPK kinase kinase, two redundant MAPK kinases (Mkk1 and Mkk2), and the Slt2 MAPK. This module is activated under a variety of stimuli related to cell wall homeostasis by Pkc1, the only member of the protein kinase C family in budding yeast. Quantitative phosphoproteomics based on stable isotope labeling of amino acids in cell culture is a powerful tool for globally studying protein phosphorylation. Here we report an analysis of the yeast phosphoproteome upon overexpression of a PKC1 hyperactive allele that specifically activates CWI MAPK signaling in the absence of external stimuli. We found 82 phosphopeptides originating from 43 proteins that showed enhanced phosphorylation in these conditions. The MAPK S/T-P target motif was significantly overrepresented in these phosphopeptides. Hyperphosphorylated proteins provide putative novel targets of the Pkc1-cell wall integrity pathway involved in diverse functions such as the control of gene expression, protein synthesis, cytoskeleton maintenance, DNA repair, and metabolism. Remarkably, five components of the plasma-membrane-associated protein complex known as eisosomes were found among the up-regulated proteins. We show here that Pkc1-induced phosphorylation of the eisosome core components Pil1 and Lsp1 was not exerted directly by Pkc1, but involved signaling through the Slt2 MAPK module.

  13. Phosphoproteomics reveals malaria parasite Protein Kinase G as a signalling hub regulating egress and invasion

    PubMed Central

    Alam, Mahmood M.; Solyakov, Lev; Bottrill, Andrew R.; Flueck, Christian; Siddiqui, Faiza A.; Singh, Shailja; Mistry, Sharad; Viskaduraki, Maria; Lee, Kate; Hopp, Christine S.; Chitnis, Chetan E.; Doerig, Christian; Moon, Robert W.; Green, Judith L.; Holder, Anthony A.; Baker, David A.; Tobin, Andrew B.

    2015-01-01

    Our understanding of the key phosphorylation-dependent signalling pathways in the human malaria parasite, Plasmodium falciparum, remains rudimentary. Here we address this issue for the essential cGMP-dependent protein kinase, PfPKG. By employing chemical and genetic tools in combination with quantitative global phosphoproteomics, we identify the phosphorylation sites on 69 proteins that are direct or indirect cellular targets for PfPKG. These PfPKG targets include proteins involved in cell signalling, proteolysis, gene regulation, protein export and ion and protein transport, indicating that cGMP/PfPKG acts as a signalling hub that plays a central role in a number of core parasite processes. We also show that PfPKG activity is required for parasite invasion. This correlates with the finding that the calcium-dependent protein kinase, PfCDPK1, is phosphorylated by PfPKG, as are components of the actomyosin complex, providing mechanistic insight into the essential role of PfPKG in parasite egress and invasion. PMID:26149123

  14. Atomic Structure of GRK5 Reveals Distinct Structural Features Novel for G Protein-coupled Receptor Kinases*♦

    PubMed Central

    Komolov, Konstantin E.; Bhardwaj, Anshul; Benovic, Jeffrey L.

    2015-01-01

    G protein-coupled receptor kinases (GRKs) are members of the protein kinase A, G, and C families (AGC) and play a central role in mediating G protein-coupled receptor phosphorylation and desensitization. One member of the family, GRK5, has been implicated in several human pathologies, including heart failure, hypertension, cancer, diabetes, and Alzheimer disease. To gain mechanistic insight into GRK5 function, we determined a crystal structure of full-length human GRK5 at 1.8 Å resolution. GRK5 in complex with the ATP analog 5′-adenylyl β,γ-imidodiphosphate or the nucleoside sangivamycin crystallized as a monomer. The C-terminal tail (C-tail) of AGC kinase domains is a highly conserved feature that is divided into three segments as follows: the C-lobe tether, the active-site tether (AST), and the N-lobe tether (NLT). This domain is fully resolved in GRK5 and reveals novel interactions with the nucleotide and N-lobe. Similar to other AGC kinases, the GRK5 AST is an integral part of the nucleotide-binding pocket, a feature not observed in other GRKs. The AST also mediates contact between the kinase N- and C-lobes facilitating closure of the kinase domain. The GRK5 NLT is largely displaced from its previously observed position in other GRKs. Moreover, although the autophosphorylation sites in the NLT are >20 Å away from the catalytic cleft, they are capable of rapid cis-autophosphorylation suggesting high mobility of this region. In summary, we provide a snapshot of GRK5 in a partially closed state, where structural elements of the kinase domain C-tail are aligned to form novel interactions to the nucleotide and N-lobe not previously observed in other GRKs. PMID:26032409

  15. Cross-talk between the two divergent insulin signaling pathways is revealed by the protein kinase B (Akt)-mediated phosphorylation of adapter protein APS on serine 588.

    PubMed

    Katsanakis, Kostas D; Pillay, Tahir S

    2005-11-11

    The APS adapter protein is recruited to the autophosphorylated kinase domain of the insulin receptor and initiates the phosphatidylinositol 3-kinase (PI3K)-independent pathway of insulin-stimulated glucose transport by recruiting CAP and c-Cbl. In this study, we have identified APS as a novel substrate for protein kinase B/Akt using an antibody that exhibits insulin-dependent immunoreactivity with a phosphospecific antibody raised against the protein kinase B substrate consensus sequence RXRXX(pS/pT) and a phosphospecific antibody that recognizes serine 21/9 of glycogen synthase kinase-3alpha/beta. This phosphorylation of APS is observed in both 3T3-L1 adipocytes and transfected cells. The insulin-stimulated serine phosphorylation of APS was inhibited by a PI3-kinase inhibitor, LY290004, a specific protein kinase B (PKB) inhibitor, deguelin, and knockdown of Akt. Serine 588 of APS is contained in a protein kinase B consensus sequence for phosphorylation conserved in APS across multiple species but not found in other members of this family, including SH2-B and Lnk. Mutation of serine 588 to alanine abolished the insulin-stimulated serine phosphorylation of APS and prevented the localization of APS to membrane ruffles. A glutathione S-transferase fusion protein containing amino acids 534-621 of APS was phosphorylated by purified PKB in vitro, and mutation of serine 588 abolished the PKB-mediated phosphorylation of APS in vitro. Taken together, this study identifies APS as a novel physiological substrate for PKB and the first serine phosphorylation site on APS. These data therefore reveal the molecular cross-talk between the insulin-activated PI3-kinase-dependent and -independent pathways previously thought to be distinct and divergent.

  16. A Forward Genetic Screen Reveals that Calcium-dependent Protein Kinase 3 Regulates Egress in Toxoplasma

    PubMed Central

    Ehret, Emma; Butz, Heidi; Garbuz, Tamila; Oswald, Benji P.; Settles, Matt; Boothroyd, John; Arrizabalaga, Gustavo

    2012-01-01

    Egress from the host cell is a crucial and highly regulated step in the biology of the obligate intracellular parasite, Toxoplasma gondii. Active egress depends on calcium fluxes and appears to be a crucial step in escaping the attack from the immune system and, potentially, in enabling the parasites to shuttle into appropriate cells for entry into the brain of the host. Previous genetic screens have yielded mutants defective in both ionophore-induced egress and ionophore-induced death. Using whole genome sequencing of one mutant and subsequent analysis of all mutants from these screens, we find that, remarkably, four independent mutants harbor a mis-sense mutation in the same gene, TgCDPK3, encoding a calcium-dependent protein kinase. All four mutations are predicted to alter key regions of TgCDPK3 and this is confirmed by biochemical studies of recombinant forms of each. By complementation we confirm a crucial role for TgCDPK3 in the rapid induction of parasite egress and we establish that TgCDPK3 is critical for formation of latent stages in the brains of mice. Genetic knockout of TgCDPK3 confirms a crucial role for this kinase in parasite egress and a non-essential role for it in the lytic cycle. PMID:23209419

  17. Protein kinase R reveals an evolutionary model for defeating viral mimicry

    PubMed Central

    Elde, Nels C.; Child, Stephanie J.; Geballe, Adam P.; Malik, Harmit S.

    2008-01-01

    Distinguishing self from non-self is a fundamental biological challenge. Many pathogens exploit the challenge of self discrimination by employing mimicry to subvert key cellular processes including the cell cycle, apoptosis, and cytoskeletal dynamics1-5. Other mimics interfere with immunity6, 7. Poxviruses encode K3L, a mimic of eIF2α, which is the substrate of Protein Kinase R (PKR), an important component of innate immunity in vertebrates8, 9. The PKR-K3L interaction exemplifies the conundrum imposed by viral mimicry. To be effective, PKR must recognize a conserved substrate (eIF2α) while avoiding rapidly evolving substrate mimics like K3L. Using the PKR-K3L system and a combination of phylogenetic and functional analyses, we uncover evolutionary strategies by which host proteins can overcome mimicry. We find that PKR has evolved under dramatic episodes of positive selection in primates. The ability of PKR to evade viral mimics is partly due to positive selection at sites most intimately involved in eIF2α recognition. We also find that adaptive changes on multiple surfaces of PKR produce combinations of substitutions that increase the odds of defeating mimicry. Thus, while it can appear that pathogens gain insurmountable advantages by mimicking cellular components, host factors like PKR can compete in molecular ‘arms races’ with mimics because of remarkable evolutionary flexibility at protein interaction interfaces challenged by mimicry. PMID:19043403

  18. Delineation of Platelet Activation Pathway of Scutellarein Revealed Its Intracellular Target as Protein Kinase C.

    PubMed

    Tian, Xiaoxuan; Chang, Lianying; Ma, Guangyin; Wang, Taiyi; Lv, Ming; Wang, Zhilong; Chen, Liping; Wang, Yuefei; Gao, Xiumei; Zhu, Yan

    2016-01-01

    Erigeron breviscapus has been widely used in traditional Chinese medicine (TCM) and its total flavonoid component is commonly used to treat ischemic stroke, coronary heart disease, diabetes and hypertension. Scutellarin is the major ingredient of E. breviscapus and scutellarein is one of the main bioactive metabolites of scutellarin in vivo, but the latter's pharmacological activities have not been fully characterized. Provided evidence that could inhibit platelet aggregation, the effect of scutellarein on rat washed platelets and its underlying mechanisms were evaluated in our research. Scutellarein inhibited platelet adhesion and aggregation induced by multiple G protein coupled receptor agonists such as thrombin, U46619 and ADP, in a concentration-dependent manner. Furthermore, the mild effect of scutellarein on intracellular Ca(2+) mobilization and cyclic AMP (cAMP) level was observed. On the other hand, the role of scutellarein as potential protein kinase C (PKC) inhibitor was confirmed by PKC activity analysis and molecular docking. The phorbol myristate acetate-induced platelets aggregation assay with or without ADP implied that the scutellarein takes PKC(s) as its primary target(s), and acts on it in a reversible way. Finally, scutellarein as a promising agent exhibited a high inhibition effect on ADP-induced platelet aggregation among its analogues. This study clarifies the PKC-related signaling pathway involved in antiplatelet action of scutellarein, and may be beneficial for the treatment of cardiovascular diseases. PMID:26581323

  19. Combined computational and experimental analysis reveals mitogen-activated protein kinase-mediated feedback phosphorylation as a mechanism for signaling specificity.

    PubMed

    Hao, Nan; Yildirim, Necmettin; Nagiec, Michal J; Parnell, Stephen C; Errede, Beverly; Dohlman, Henrik G; Elston, Timothy C

    2012-10-01

    Different environmental stimuli often use the same set of signaling proteins to achieve very different physiological outcomes. The mating and invasive growth pathways in yeast each employ a mitogen-activated protein (MAP) kinase cascade that includes Ste20, Ste11, and Ste7. Whereas proper mating requires Ste7 activation of the MAP kinase Fus3, invasive growth requires activation of the alternate MAP kinase Kss1. To determine how MAP kinase specificity is achieved, we used a series of mathematical models to quantitatively characterize pheromone-stimulated kinase activation. In accordance with the computational analysis, MAP kinase feedback phosphorylation of Ste7 results in diminished activation of Kss1, but not Fus3. These findings reveal how feedback phosphorylation of a common pathway component can limit the activity of a competing MAP kinase through feedback phosphorylation of a common activator, and thereby promote signal fidelity. PMID:22875986

  20. Manipulation of Mitogen-Activated Protein Kinase Kinase Signaling in the Arabidopsis Stomatal Lineage Reveals Motifs That Contribute to Protein Localization and Signaling Specificity[W][OPEN

    PubMed Central

    Lampard, Gregory R.; Wengier, Diego L.; Bergmann, Dominique C.

    2014-01-01

    When multiple mitogen-activated protein kinase (MAPK) components are recruited recurrently to transduce signals of different origins, and often opposing outcomes, mechanisms to enforce signaling specificity are of utmost importance. These mechanisms are largely uncharacterized in plant MAPK signaling networks. The Arabidopsis thaliana stomatal lineage was previously used to show that when rendered constitutively active, four MAPK kinases (MKKs), MKK4/5/7/9, are capable of perturbing stomatal development and that these kinases comprise two pairs, MKK4/5 and MKK7/9, with both overlapping and divergent functions. We characterized the contributions of specific structural domains of these four “stomatal” MKKs to MAPK signaling output and specificity both in vitro and in vivo within the three discrete cell types of the stomatal lineage. These results verify the influence of functional docking (D) domains of MKKs on MAPK signal output and identify novel regulatory functions for previously uncharacterized structures within the N termini of MKK4/5. Beyond this, we present a novel function of the D-domains of MKK7/9 in regulating the subcellular localization of these kinases. These results provide tools to broadly assess the extent to which these and additional motifs within MKKs function to regulate MAPK signal output throughout the plant. PMID:25172143

  1. A comprehensive protein–protein interactome for yeast PAS kinase 1 reveals direct inhibition of respiration through the phosphorylation of Cbf1

    PubMed Central

    DeMille, Desiree; Bikman, Benjamin T.; Mathis, Andrew D.; Prince, John T.; Mackay, Jordan T.; Sowa, Steven W.; Hall, Tacie D.; Grose, Julianne H.

    2014-01-01

    Per-Arnt-Sim (PAS) kinase is a sensory protein kinase required for glucose homeostasis in yeast, mice, and humans, yet little is known about the molecular mechanisms of its function. Using both yeast two-hybrid and copurification approaches, we identified the protein–protein interactome for yeast PAS kinase 1 (Psk1), revealing 93 novel putative protein binding partners. Several of the Psk1 binding partners expand the role of PAS kinase in glucose homeostasis, including new pathways involved in mitochondrial metabolism. In addition, the interactome suggests novel roles for PAS kinase in cell growth (gene/protein expression, replication/cell division, and protein modification and degradation), vacuole function, and stress tolerance. In vitro kinase studies using a subset of 25 of these binding partners identified Mot3, Zds1, Utr1, and Cbf1 as substrates. Further evidence is provided for the in vivo phosphorylation of Cbf1 at T211/T212 and for the subsequent inhibition of respiration. This respiratory role of PAS kinase is consistent with the reported hypermetabolism of PAS kinase–deficient mice, identifying a possible molecular mechanism and solidifying the evolutionary importance of PAS kinase in the regulation of glucose homeostasis. PMID:24850888

  2. A novel immuno-competitive capture mass spectrometry strategy for protein-protein interaction profiling reveals that LATS kinases regulate HCV replication through NS5A phosphorylation.

    PubMed

    Meistermann, Hélène; Gao, Junjun; Golling, Sabrina; Lamerz, Jens; Le Pogam, Sophie; Tzouros, Manuel; Sankabathula, Sailaja; Gruenbaum, Lore; Nájera, Isabel; Langen, Hanno; Klumpp, Klaus; Augustin, Angélique

    2014-11-01

    Mapping protein-protein interactions is essential to fully characterize the biological function of a protein and improve our understanding of diseases. Affinity purification coupled to mass spectrometry (AP-MS) using selective antibodies against a target protein has been commonly applied to study protein complexes. However, one major limitation is a lack of specificity as a substantial part of the proposed binders is due to nonspecific interactions. Here, we describe an innovative immuno-competitive capture mass spectrometry (ICC-MS) method to allow systematic investigation of protein-protein interactions. ICC-MS markedly increases the specificity of classical immunoprecipitation (IP) by introducing a competition step between free and capturing antibody prior to IP. Instead of comparing only one experimental sample with a control, the methodology generates a 12-concentration antibody competition profile. Label-free quantitation followed by a robust statistical analysis of the data is then used to extract the cellular interactome of a protein of interest and to filter out background proteins. We applied this new approach to specifically map the interactome of hepatitis C virus (HCV) nonstructural protein 5A (NS5A) in a cellular HCV replication system and uncovered eight new NS5A-interacting protein candidates along with two previously validated binding partners. Follow-up biological validation experiments revealed that large tumor suppressor homolog 1 and 2 (LATS1 and LATS2, respectively), two closely related human protein kinases, are novel host kinases responsible for NS5A phosphorylation at a highly conserved position required for optimal HCV genome replication. These results are the first illustration of the value of ICC-MS for the analysis of endogenous protein complexes to identify biologically relevant protein-protein interactions with high specificity.

  3. Targeted massively parallel sequencing of angiosarcomas reveals frequent activation of the mitogen activated protein kinase pathway

    PubMed Central

    Murali, Rajmohan; Chandramohan, Raghu; Möller, Inga; Scholz, Simone L.; Berger, Michael; Huberman, Kety; Viale, Agnes; Pirun, Mono; Socci, Nicholas D.; Bouvier, Nancy; Bauer, Sebastian; Artl, Monika; Schilling, Bastian; Schimming, Tobias; Sucker, Antje; Schwindenhammer, Benjamin; Grabellus, Florian; Speicher, Michael R.; Schaller, Jörg; Hillen, Uwe; Schadendorf, Dirk; Mentzel, Thomas; Cheng, Donavan T.; Wiesner, Thomas; Griewank, Klaus G.

    2015-01-01

    Angiosarcomas are rare malignant mesenchymal tumors of endothelial differentiation. The clinical behavior is usually aggressive and the prognosis for patients with advanced disease is poor with no effective therapies. The genetic bases of these tumors have been partially revealed in recent studies reporting genetic alterations such as amplifications of MYC (primarily in radiation-associated angiosarcomas), inactivating mutations in PTPRB and R707Q hotspot mutations of PLCG1. Here, we performed a comprehensive genomic analysis of 34 angiosarcomas using a clinically-approved, hybridization-based targeted next-generation sequencing assay for 341 well-established oncogenes and tumor suppressor genes. Over half of the angiosarcomas (n = 18, 53%) harbored genetic alterations affecting the MAPK pathway, involving mutations in KRAS, HRAS, NRAS, BRAF, MAPK1 and NF1, or amplifications in MAPK1/CRKL, CRAF or BRAF. The most frequently detected genetic aberrations were mutations in TP53 in 12 tumors (35%) and losses of CDKN2A in 9 tumors (26%). MYC amplifications were generally mutually exclusive of TP53 alterations and CDKN2A loss and were identified in 8 tumors (24%), most of which (n = 7, 88%) arose post-irradiation. Previously reported mutations in PTPRB (n = 10, 29%) and one (3%) PLCG1 R707Q mutation were also identified. Our results demonstrate that angiosarcomas are a genetically heterogeneous group of tumors, harboring a wide range of genetic alterations. The high frequency of genetic events affecting the MAPK pathway suggests that targeted therapies inhibiting MAPK signaling may be promising therapeutic avenues in patients with advanced angiosarcomas. PMID:26440310

  4. Quantitative phosphoproteomics identifies SnRK2 protein kinase substrates and reveals the effectors of abscisic acid action.

    PubMed

    Wang, Pengcheng; Xue, Liang; Batelli, Giorgia; Lee, Shinyoung; Hou, Yueh-Ju; Van Oosten, Michael J; Zhang, Huiming; Tao, W Andy; Zhu, Jian-Kang

    2013-07-01

    Sucrose nonfermenting 1 (SNF1)-related protein kinase 2s (SnRK2s) are central components of abscisic acid (ABA) signaling pathways. The snrk2.2/2.3/2.6 triple-mutant plants are nearly completely insensitive to ABA, suggesting that most of the molecular actions of ABA are triggered by the SnRK2s-mediated phosphorylation of substrate proteins. Only a few substrate proteins of the SnRK2s are known. To identify additional substrate proteins of the SnRK2s and provide insight into the molecular actions of ABA, we used quantitative phosphoproteomics to compare the global changes in phosphopeptides in WT and snrk2.2/2.3/2.6 triple mutant seedlings in response to ABA treatment. Among the 5,386 unique phosphorylated peptides identified in this study, we found that ABA can increase the phosphorylation of 166 peptides and decrease the phosphorylation of 117 peptides in WT seedlings. In the snrk2.2/2.3/2.6 triple mutant, 84 of the 166 peptides, representing 58 proteins, could not be phosphorylated, or phosphorylation was not increased under ABA treatment. In vitro kinase assays suggest that most of the 58 proteins can serve as substrates of the SnRK2s. The SnRK2 substrates include proteins involved in flowering time regulation, RNA and DNA binding, miRNA and epigenetic regulation, signal transduction, chloroplast function, and many other cellular processes. Consistent with the SnRK2 phosphorylation of flowering time regulators, the snrk2.2/2.3/2.6 triple mutant flowered significantly earlier than WT. These results shed new light on the role of the SnRK2 protein kinases and on the downstream effectors of ABA action, and improve our understanding of plant responses to adverse environments.

  5. Quantitative phosphoproteomics identifies SnRK2 protein kinase substrates and reveals the effectors of abscisic acid action

    PubMed Central

    Wang, Pengcheng; Xue, Liang; Batelli, Giorgia; Lee, Shinyoung; Hou, Yueh-Ju; Van Oosten, Michael J.; Zhang, Huiming; Tao, W. Andy; Zhu, Jian-Kang

    2013-01-01

    Sucrose nonfermenting 1 (SNF1)-related protein kinase 2s (SnRK2s) are central components of abscisic acid (ABA) signaling pathways. The snrk2.2/2.3/2.6 triple-mutant plants are nearly completely insensitive to ABA, suggesting that most of the molecular actions of ABA are triggered by the SnRK2s-mediated phosphorylation of substrate proteins. Only a few substrate proteins of the SnRK2s are known. To identify additional substrate proteins of the SnRK2s and provide insight into the molecular actions of ABA, we used quantitative phosphoproteomics to compare the global changes in phosphopeptides in WT and snrk2.2/2.3/2.6 triple mutant seedlings in response to ABA treatment. Among the 5,386 unique phosphorylated peptides identified in this study, we found that ABA can increase the phosphorylation of 166 peptides and decrease the phosphorylation of 117 peptides in WT seedlings. In the snrk2.2/2.3/2.6 triple mutant, 84 of the 166 peptides, representing 58 proteins, could not be phosphorylated, or phosphorylation was not increased under ABA treatment. In vitro kinase assays suggest that most of the 58 proteins can serve as substrates of the SnRK2s. The SnRK2 substrates include proteins involved in flowering time regulation, RNA and DNA binding, miRNA and epigenetic regulation, signal transduction, chloroplast function, and many other cellular processes. Consistent with the SnRK2 phosphorylation of flowering time regulators, the snrk2.2/2.3/2.6 triple mutant flowered significantly earlier than WT. These results shed new light on the role of the SnRK2 protein kinases and on the downstream effectors of ABA action, and improve our understanding of plant responses to adverse environments. PMID:23776212

  6. Chemoproteomics Reveals Novel Protein and Lipid Kinase Targets of Clinical CDK4/6 Inhibitors in Lung Cancer.

    PubMed

    Sumi, Natalia J; Kuenzi, Brent M; Knezevic, Claire E; Remsing Rix, Lily L; Rix, Uwe

    2015-12-18

    Several selective CDK4/6 inhibitors are in clinical trials for non-small cell lung cancer (NSCLC). Palbociclib (PD0332991) is included in the phase II/III Lung-MAP trial for squamous cell lung carcinoma (LUSQ). We noted differential cellular activity between palbociclib and the structurally related ribociclib (LEE011) in LUSQ cells. Applying an unbiased mass spectrometry-based chemoproteomics approach in H157 cells and primary tumor samples, we here report distinct proteome-wide target profiles of these two drug candidates in LUSQ, which encompass novel protein and, for palbociclib only, lipid kinases. In addition to CDK4 and 6, we observed CDK9 as a potent target of both drugs. Palbociclib interacted with several kinases not targeted by ribociclib, such as casein kinase 2 and PIK3R4, which regulate autophagy. Furthermore, palbociclib engaged several lipid kinases, most notably, PIK3CD and PIP4K2A/B/C. Accordingly, we observed modulation of autophagy and inhibition of AKT signaling by palbociclib but not ribociclib.

  7. Analyses of Compact Trichinella Kinomes Reveal a MOS-Like Protein Kinase with a Unique N-Terminal Domain.

    PubMed

    Stroehlein, Andreas J; Young, Neil D; Korhonen, Pasi K; Chang, Bill C H; Sternberg, Paul W; La Rosa, Giuseppe; Pozio, Edoardo; Gasser, Robin B

    2016-01-01

    Parasitic worms of the genus Trichinella (phylum Nematoda; class Enoplea) represent a complex of at least twelve taxa that infect a range of different host animals, including humans, around the world. They are foodborne, intracellular nematodes, and their life cycles differ substantially from those of other nematodes. The recent characterization of the genomes and transcriptomes of all twelve recognized taxa of Trichinella now allows, for the first time, detailed studies of their molecular biology. In the present study, we defined, curated, and compared the protein kinase complements (kinomes) of Trichinella spiralis and T. pseudospiralis using an integrated bioinformatic workflow employing transcriptomic and genomic data sets. We examined how variation in the kinome might link to unique aspects of Trichinella morphology, biology, and evolution. Furthermore, we utilized in silico structural modeling to discover and characterize a novel, MOS-like kinase with an unusual, previously undescribed N-terminal domain. Taken together, the present findings provide a basis for comparative investigations of nematode kinomes, and might facilitate the identification of Enoplea-specific intervention and diagnostic targets. Importantly, the in silico modeling approach assessed here provides an exciting prospect of being able to identify and classify currently unknown (orphan) kinases, as a foundation for their subsequent structural and functional investigation. PMID:27412987

  8. Analyses of Compact Trichinella Kinomes Reveal a MOS-Like Protein Kinase with a Unique N-Terminal Domain

    PubMed Central

    Stroehlein, Andreas J.; Young, Neil D.; Korhonen, Pasi K.; Chang, Bill C. H.; Sternberg, Paul W.; La Rosa, Giuseppe; Pozio, Edoardo; Gasser, Robin B.

    2016-01-01

    Parasitic worms of the genus Trichinella (phylum Nematoda; class Enoplea) represent a complex of at least twelve taxa that infect a range of different host animals, including humans, around the world. They are foodborne, intracellular nematodes, and their life cycles differ substantially from those of other nematodes. The recent characterization of the genomes and transcriptomes of all twelve recognized taxa of Trichinella now allows, for the first time, detailed studies of their molecular biology. In the present study, we defined, curated, and compared the protein kinase complements (kinomes) of Trichinella spiralis and T. pseudospiralis using an integrated bioinformatic workflow employing transcriptomic and genomic data sets. We examined how variation in the kinome might link to unique aspects of Trichinella morphology, biology, and evolution. Furthermore, we utilized in silico structural modeling to discover and characterize a novel, MOS-like kinase with an unusual, previously undescribed N-terminal domain. Taken together, the present findings provide a basis for comparative investigations of nematode kinomes, and might facilitate the identification of Enoplea-specific intervention and diagnostic targets. Importantly, the in silico modeling approach assessed here provides an exciting prospect of being able to identify and classify currently unknown (orphan) kinases, as a foundation for their subsequent structural and functional investigation. PMID:27412987

  9. Identification of Open Stomata1-Interacting Proteins Reveals Interactions with Sucrose Non-fermenting1-Related Protein Kinases2 and with Type 2A Protein Phosphatases That Function in Abscisic Acid Responses.

    PubMed

    Waadt, Rainer; Manalansan, Bianca; Rauniyar, Navin; Munemasa, Shintaro; Booker, Matthew A; Brandt, Benjamin; Waadt, Christian; Nusinow, Dmitri A; Kay, Steve A; Kunz, Hans-Henning; Schumacher, Karin; DeLong, Alison; Yates, John R; Schroeder, Julian I

    2015-09-01

    The plant hormone abscisic acid (ABA) controls growth and development and regulates plant water status through an established signaling pathway. In the presence of ABA, pyrabactin resistance/regulatory component of ABA receptor proteins inhibit type 2C protein phosphatases (PP2Cs). This, in turn, enables the activation of Sucrose Nonfermenting1-Related Protein Kinases2 (SnRK2). Open Stomata1 (OST1)/SnRK2.6/SRK2E is a major SnRK2-type protein kinase responsible for mediating ABA responses. Arabidopsis (Arabidopsis thaliana) expressing an epitope-tagged OST1 in the recessive ost1-3 mutant background was used for the copurification and identification of OST1-interacting proteins after osmotic stress and ABA treatments. These analyses, which were confirmed using bimolecular fluorescence complementation and coimmunoprecipitation, unexpectedly revealed homo- and heteromerization of OST1 with SnRK2.2, SnRK2.3, OST1, and SnRK2.8. Furthermore, several OST1-complexed proteins were identified as type 2A protein phosphatase (PP2A) subunits and as proteins involved in lipid and galactolipid metabolism. More detailed analyses suggested an interaction network between ABA-activated SnRK2-type protein kinases and several PP2A-type protein phosphatase regulatory subunits. pp2a double mutants exhibited a reduced sensitivity to ABA during seed germination and stomatal closure and an enhanced ABA sensitivity in root growth regulation. These analyses add PP2A-type protein phosphatases as another class of protein phosphatases to the interaction network of SnRK2-type protein kinases.

  10. Identification of Open Stomata1-Interacting Proteins Reveals Interactions with Sucrose Non-fermenting1-Related Protein Kinases2 and with Type 2A Protein Phosphatases That Function in Abscisic Acid Responses.

    PubMed

    Waadt, Rainer; Manalansan, Bianca; Rauniyar, Navin; Munemasa, Shintaro; Booker, Matthew A; Brandt, Benjamin; Waadt, Christian; Nusinow, Dmitri A; Kay, Steve A; Kunz, Hans-Henning; Schumacher, Karin; DeLong, Alison; Yates, John R; Schroeder, Julian I

    2015-09-01

    The plant hormone abscisic acid (ABA) controls growth and development and regulates plant water status through an established signaling pathway. In the presence of ABA, pyrabactin resistance/regulatory component of ABA receptor proteins inhibit type 2C protein phosphatases (PP2Cs). This, in turn, enables the activation of Sucrose Nonfermenting1-Related Protein Kinases2 (SnRK2). Open Stomata1 (OST1)/SnRK2.6/SRK2E is a major SnRK2-type protein kinase responsible for mediating ABA responses. Arabidopsis (Arabidopsis thaliana) expressing an epitope-tagged OST1 in the recessive ost1-3 mutant background was used for the copurification and identification of OST1-interacting proteins after osmotic stress and ABA treatments. These analyses, which were confirmed using bimolecular fluorescence complementation and coimmunoprecipitation, unexpectedly revealed homo- and heteromerization of OST1 with SnRK2.2, SnRK2.3, OST1, and SnRK2.8. Furthermore, several OST1-complexed proteins were identified as type 2A protein phosphatase (PP2A) subunits and as proteins involved in lipid and galactolipid metabolism. More detailed analyses suggested an interaction network between ABA-activated SnRK2-type protein kinases and several PP2A-type protein phosphatase regulatory subunits. pp2a double mutants exhibited a reduced sensitivity to ABA during seed germination and stomatal closure and an enhanced ABA sensitivity in root growth regulation. These analyses add PP2A-type protein phosphatases as another class of protein phosphatases to the interaction network of SnRK2-type protein kinases. PMID:26175513

  11. Identification of Open Stomata1-Interacting Proteins Reveals Interactions with Sucrose Non-fermenting1-Related Protein Kinases2 and with Type 2A Protein Phosphatases That Function in Abscisic Acid Responses1[OPEN

    PubMed Central

    Waadt, Rainer; Manalansan, Bianca; Rauniyar, Navin; Munemasa, Shintaro; Booker, Matthew A.; Brandt, Benjamin; Waadt, Christian; Nusinow, Dmitri A.; Kay, Steve A.; Kunz, Hans-Henning; Schumacher, Karin; DeLong, Alison; Yates, John R.; Schroeder, Julian I.

    2015-01-01

    The plant hormone abscisic acid (ABA) controls growth and development and regulates plant water status through an established signaling pathway. In the presence of ABA, pyrabactin resistance/regulatory component of ABA receptor proteins inhibit type 2C protein phosphatases (PP2Cs). This, in turn, enables the activation of Sucrose Nonfermenting1-Related Protein Kinases2 (SnRK2). Open Stomata1 (OST1)/SnRK2.6/SRK2E is a major SnRK2-type protein kinase responsible for mediating ABA responses. Arabidopsis (Arabidopsis thaliana) expressing an epitope-tagged OST1 in the recessive ost1-3 mutant background was used for the copurification and identification of OST1-interacting proteins after osmotic stress and ABA treatments. These analyses, which were confirmed using bimolecular fluorescence complementation and coimmunoprecipitation, unexpectedly revealed homo- and heteromerization of OST1 with SnRK2.2, SnRK2.3, OST1, and SnRK2.8. Furthermore, several OST1-complexed proteins were identified as type 2A protein phosphatase (PP2A) subunits and as proteins involved in lipid and galactolipid metabolism. More detailed analyses suggested an interaction network between ABA-activated SnRK2-type protein kinases and several PP2A-type protein phosphatase regulatory subunits. pp2a double mutants exhibited a reduced sensitivity to ABA during seed germination and stomatal closure and an enhanced ABA sensitivity in root growth regulation. These analyses add PP2A-type protein phosphatases as another class of protein phosphatases to the interaction network of SnRK2-type protein kinases. PMID:26175513

  12. A kinase inhibitor screen reveals protein kinase C-dependent endocytic recycling of ErbB2 in breast cancer cells.

    PubMed

    Bailey, Tameka A; Luan, Haitao; Tom, Eric; Bielecki, Timothy Alan; Mohapatra, Bhopal; Ahmad, Gulzar; George, Manju; Kelly, David L; Natarajan, Amarnath; Raja, Srikumar M; Band, Vimla; Band, Hamid

    2014-10-31

    ErbB2 overexpression drives oncogenesis in 20-30% cases of breast cancer. Oncogenic potential of ErbB2 is linked to inefficient endocytic traffic into lysosomes and preferential recycling. However, regulation of ErbB2 recycling is incompletely understood. We used a high-content immunofluorescence imaging-based kinase inhibitor screen on SKBR-3 breast cancer cells to identify kinases whose inhibition alters the clearance of cell surface ErbB2 induced by Hsp90 inhibitor 17-AAG. Less ErbB2 clearance was observed with broad-spectrum PKC inhibitor Ro 31-8220. A similar effect was observed with Go 6976, a selective inhibitor of classical Ca(2+)-dependent PKCs (α, β1, βII, and γ). PKC activation by PMA promoted surface ErbB2 clearance but without degradation, and ErbB2 was observed to move into a juxtanuclear compartment where it colocalized with PKC-α and PKC-δ together with the endocytic recycling regulator Arf6. PKC-α knockdown impaired the juxtanuclear localization of ErbB2. ErbB2 transit to the recycling compartment was also impaired upon PKC-δ knockdown. PMA-induced Erk phosphorylation was reduced by ErbB2 inhibitor lapatinib, as well as by knockdown of PKC-δ but not that of PKC-α. Our results suggest that activation of PKC-α and -δ mediates a novel positive feedback loop by promoting ErbB2 entry into the endocytic recycling compartment, consistent with reported positive roles for these PKCs in ErbB2-mediated tumorigenesis. As the endocytic recycling compartment/pericentrion has emerged as a PKC-dependent signaling hub for G-protein-coupled receptors, our findings raise the possibility that oncogenesis by ErbB2 involves previously unexplored PKC-dependent endosomal signaling.

  13. Transcriptomic analysis reveals numerous diverse protein kinases and transcription factors involved in desiccation tolerance in the resurrection plant Myrothamnus flabellifolia

    PubMed Central

    Ma, Chao; Wang, Hong; Macnish, Andrew J; Estrada-Melo, Alejandro C; Lin, Jing; Chang, Youhong; Reid, Michael S; Jiang, Cai-Zhong

    2015-01-01

    The woody resurrection plant Myrothamnus flabellifolia has remarkable tolerance to desiccation. Pyro-sequencing technology permitted us to analyze the transcriptome of M. flabellifolia during both dehydration and rehydration. We identified a total of 8287 and 8542 differentially transcribed genes during dehydration and rehydration treatments respectively. Approximately 295 transcription factors (TFs) and 484 protein kinases (PKs) were up- or down-regulated in response to desiccation stress. Among these, the transcript levels of 53 TFs and 91 PKs increased rapidly and peaked early during dehydration. These regulators transduce signal cascades of molecular pathways, including the up-regulation of ABA-dependent and independent drought stress pathways and the activation of protective mechanisms for coping with oxidative damage. Antioxidant systems are up-regulated, and the photosynthetic system is modified to reduce ROS generation. Secondary metabolism may participate in the desiccation tolerance of M. flabellifolia as indicated by increases in transcript abundance of genes involved in isopentenyl diphosphate biosynthesis. Up-regulation of genes encoding late embryogenesis abundant proteins and sucrose phosphate synthase is also associated with increased tolerance to desiccation. During rehydration, the transcriptome is also enriched in transcripts of genes encoding TFs and PKs, as well as genes involved in photosynthesis, and protein synthesis. The data reported here contribute comprehensive insights into the molecular mechanisms of desiccation tolerance in M. flabellifolia. PMID:26504577

  14. Transcriptomic analysis reveals numerous diverse protein kinases and transcription factors involved in desiccation tolerance in the resurrection plant Myrothamnus flabellifolia.

    PubMed

    Ma, Chao; Wang, Hong; Macnish, Andrew J; Estrada-Melo, Alejandro C; Lin, Jing; Chang, Youhong; Reid, Michael S; Jiang, Cai-Zhong

    2015-01-01

    The woody resurrection plant Myrothamnus flabellifolia has remarkable tolerance to desiccation. Pyro-sequencing technology permitted us to analyze the transcriptome of M. flabellifolia during both dehydration and rehydration. We identified a total of 8287 and 8542 differentially transcribed genes during dehydration and rehydration treatments respectively. Approximately 295 transcription factors (TFs) and 484 protein kinases (PKs) were up- or down-regulated in response to desiccation stress. Among these, the transcript levels of 53 TFs and 91 PKs increased rapidly and peaked early during dehydration. These regulators transduce signal cascades of molecular pathways, including the up-regulation of ABA-dependent and independent drought stress pathways and the activation of protective mechanisms for coping with oxidative damage. Antioxidant systems are up-regulated, and the photosynthetic system is modified to reduce ROS generation. Secondary metabolism may participate in the desiccation tolerance of M. flabellifolia as indicated by increases in transcript abundance of genes involved in isopentenyl diphosphate biosynthesis. Up-regulation of genes encoding late embryogenesis abundant proteins and sucrose phosphate synthase is also associated with increased tolerance to desiccation. During rehydration, the transcriptome is also enriched in transcripts of genes encoding TFs and PKs, as well as genes involved in photosynthesis, and protein synthesis. The data reported here contribute comprehensive insights into the molecular mechanisms of desiccation tolerance in M. flabellifolia. PMID:26504577

  15. Redox Regulation of Protein Kinases

    PubMed Central

    Truong, Thu H.; Carroll, Kate S.

    2015-01-01

    Protein kinases represent one of the largest families of genes found in eukaryotes. Kinases mediate distinct cellular processes ranging from proliferation, differentiation, survival, and apoptosis. Ligand-mediated activation of receptor kinases can lead to the production of endogenous H2O2 by membrane-bound NADPH oxidases. In turn, H2O2 can be utilized as a secondary messenger in signal transduction pathways. This review presents an overview of the molecular mechanisms involved in redox regulation of protein kinases and its effects on signaling cascades. In the first half, we will focus primarily on receptor tyrosine kinases (RTKs), whereas the latter will concentrate on downstream non-receptor kinases involved in relaying stimulant response. Select examples from the literature are used to highlight the functional role of H2O2 regarding kinase activity, as well as the components involved in H2O2 production and regulation during cellular signaling. In addition, studies demonstrating direct modulation of protein kinases by H2O2 through cysteine oxidation will be emphasized. Identification of these redox-sensitive residues may help uncover signaling mechanisms conserved within kinase subfamilies. In some cases, these residues can even be exploited as targets for the development of new therapeutics. Continued efforts in this field will further basic understanding of kinase redox regulation, and delineate the mechanisms involved in physiologic and pathological H2O2 responses. PMID:23639002

  16. Protein Crystals of Raf Kinase

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This image shows crystals of the protein raf kinase grown on Earth (photo a) and on USML-2 (photo b). The space-grown crystals are an order of magnitude larger. Principal Investigator: Dan Carter of New Century Pharmaceuticals

  17. Oncoprotein protein kinase

    DOEpatents

    Karin, Michael; Hibi, Masahiko; Linn, Anning

    1996-01-01

    An isolated polypeptide (JNK) characterized by having a molecular weight of 46kD as determined by reducing SDS-PAGE, having serine and threonine kinase activity, phosphorylating the c-Jun N-terminal activation domain and polynucleotide sequences and method of detection of JNK.

  18. Oncoprotein protein kinase

    DOEpatents

    Karin, M.; Hibi, M.; Lin, A.

    1997-02-25

    An isolated polypeptide (JNK) characterized by having a molecular weight of 46 kD as determined by reducing SDS-PAGE is disclosed. The polypeptide has serine and threonine kinase activity, phosphorylating the c-Jun N-terminal activation domain and polynucleotide sequences. The method of detection of JNK is also provided. JNK phosphorylates c-Jun N-terminal activation domain which affects gene expression from AP-1 sites. 44 figs.

  19. Oncoprotein protein kinase

    DOEpatents

    Karin, Michael; Hibi, Masahiko; Lin, Anning

    2004-03-16

    An isolated polypeptide (JNK) characterized by having a molecular weight of 46 kD as determined by reducing SDS-PAGE, having serine and threonine kinase activity, phosphorylating the c-Jun N-terminal activation domain and polynucleotide sequences and method of detection of JNK are provided herein. JNK phosphorylates c-Jun N-terminal activation domain which affects gene expression from AP-1 sites.

  20. Oncoprotein protein kinase

    DOEpatents

    Karin, Michael; Hibi, Masahiko; Lin, Anning; Davis, Roger; Derijard, Benoit

    2003-02-04

    An isolated polypeptide (JNK) characterized by having a molecular weight of 46kD as determined by reducing SDS-PAGE, having serine and threonine kinase activity, phosphorylating the c-Jun N-terminal activation domain and polynucleotide sequences and method of detection of JNK are provided herein. JNK phosphorylates c-Jun N-terminal activation domain which affects gene expression from AP-1 sites.

  1. Oncoprotein protein kinase

    DOEpatents

    Karin, Michael; Hibi, Masahiko; Lin, Anning

    1998-01-01

    An isolated polypeptide (JNK) characterized by having a molecular weight of 46 kD as determined by reducing SDS-PAGE, having serine and threonine kinase activity, phosphorylating the c-Jun N-terminal activation domain and polynucleotide sequences and method of detection of JNK are provided herein. JNK phosphorylates c-Jun N-terminal activation domain which affects gene expression from AP-1 sites.

  2. Oncoprotein protein kinase

    DOEpatents

    Karin, Michael; Hibi, Masahiko; Lin, Anning

    1999-01-01

    An isolated polypeptide (JNK) characterized by having a molecular weight of 46 kD or 55 kD as determined by reducing SDS-PAGE, having serine and theonine kinase activity, phosphorylating the c-Jun N-terminal activation domain and polynucleotide sequences and method of detection of JNK are provided herein. JNK phosphorylates c-Jun N-terminal activation domain which affects gene expression from AP-1 sites.

  3. Oncoprotein protein kinase

    DOEpatents

    Karin, Michael; Hibi, Masahiko; Lin, Anning; Davis, Roger; Derijard, Benoit

    2005-03-08

    An isolated polypeptide (JNK) characterized by having a molecular weight of 46 kD as determined by reducing SDS-PAGE, having serine and threonine kinase activity, phosphorylating the c-Jun N-terminal activation domain and polynucleotide sequences and method of detection of JNK are provided herein. JNK phosphorylates c-Jun N-terminal activation domain which affects gene expression from AP-1 sites.

  4. Oncoprotein protein kinase

    DOEpatents

    Karin, Michael; Hibi, Masahiko; Lin, Anning

    1997-01-01

    An isolated polypeptide (JNK) characterized by having a molecular weight of 46kD as determined by reducing SDS-PAGE, having serine and threonine kinase activity, phosphorylating the c-Jun N-terminal activation domain and polynucleotide sequences and method of detection of JNK are provided herein. JNK phosphorylates c-Jun N-terminal activation domain which affects gene expression from AP-1 sites.

  5. Oncoprotein protein kinase

    DOEpatents

    Karin, Michael; Hibi, Masahiko; Lin, Anning

    1997-01-01

    An isolated polypeptide (JNK) characterized by having a molecular weight of 46 kD as determined by reducing SDS-PAGE, having serine and threonine kinase activity, phosphorylating the c-Jun N-terminal activation domain and polynucleotide sequences and method of detection of JNK are provided herein. JNK phosphorylates c-Jun N-terminal activation domain which affects gene expression from AP-1 sites.

  6. Oncoprotein protein kinase

    DOEpatents

    Davis, Roger; Derijard, Benoit; Karin, Michael; Hibi, Masahiko; Lin, Anning

    2005-01-25

    An isolated polypeptide (JNK) characterized by having a molecular weight of 46 kD as determined by reducing SDS-PAGE, having serine and threonine kinase activity, phosphorylating the c-Jun N-terminal activation domain and polynucleotide sequences and method of detection of JNK are provided herein. JNK phosphorylates c-Jun N-terminal activation domain which affects gene expression from AP-1 sites.

  7. Oncoprotein protein kinase

    DOEpatents

    Karin, Michael; Lin, Anning

    1999-11-30

    An isolated polypeptide (JNK) characterized by having a molecular weight of 46 kD or 55 kD as determined by reducing SDS-PAGE, having serine and theonine kinase activity, phosphorylating the c-Jun N-terminal activation domain and polynucleotide sequences and method of detection of JNK are provided herein. JNK phosphorylates c-Jun N-terminal activation domain which affects gene expression from AP-1 sites.

  8. Bivalent Inhibitors of Protein Kinases

    PubMed Central

    Gower, Carrie M.; Chang, Matthew E. K.; Maly, Dustin J.

    2015-01-01

    Protein kinases are key players in a large number of cellular signaling pathways. Dysregulated kinase activity has been implicated in a number of diseases, and members of this enzyme family are of therapeutic interest. However, due to the fact that most inhibitors interact with the highly conserved ATP-binding sites of kinases, it is a significant challenge to develop pharmacological agents that target only one of the greater than 500 kinases present in humans. A potential solution to this problem is the development of bisubstrate and bivalent kinase inhibitors, in which an active site-directed moiety is tethered to another ligand that targets a location outside of the ATP-binding cleft. Because kinase signaling specificity is modulated by regions outside of the ATP-binding site, strategies that exploit these interactions have the potential to provide reagents with high target selectivity. This review highlights examples of kinase interaction sites that can potentially be exploited by bisubstrate and bivalent inhibitors. Furthermore, an overview of efforts to target these interactions with bisubstrate and bivalent inhibitors is provided. Finally, several examples of the successful application of these reagents in a cellular setting are described. PMID:24564382

  9. Protein kinase A signalling in Schistosoma mansoni cercariae and schistosomules.

    PubMed

    Hirst, Natasha L; Lawton, Scott P; Walker, Anthony J

    2016-06-01

    Cyclic AMP (cAMP)-dependent protein kinase/protein kinase A regulates multiple processes in eukaryotes by phosphorylating diverse cellular substrates, including metabolic and signalling enzymes, ion channels and transcription factors. Here we provide insight into protein kinase A signalling in cercariae and 24h in vitro cultured somules of the blood parasite, Schistosoma mansoni, which causes human intestinal schistosomiasis. Functional mapping of activated protein kinase A using anti-phospho protein kinase A antibodies and confocal laser scanning microscopy revealed activated protein kinase A in the central and peripheral nervous system, oral-tip sensory papillae, oesophagus and excretory system of intact cercariae. Cultured 24h somules, which biologically represent the skin-resident stage of the parasite, exhibited similar activation patterns in oesophageal and nerve tissues but also displayed striking activation at the tegument and activation in a region resembling the germinal 'stem' cell cluster. The adenylyl cyclase activator, forskolin, stimulated somule protein kinase A activation and produced a hyperkinesia phenotype. The biogenic amines, serotonin and dopamine known to be present in skin also induced protein kinase A activation in somules, whereas neuropeptide Y or [Leu(31),Pro(34)]-neuropeptide Y attenuated protein kinase A activation. However, neuropeptide Y did not block the forskolin-induced somule hyperkinesia. Bioinformatic investigation of potential protein associations revealed 193 medium confidence and 59 high confidence protein kinase A interacting partners in S. mansoni, many of which possess putative protein kinase A phosphorylation sites. These data provide valuable insight into the intricacies of protein kinase A signalling in S. mansoni and a framework for further physiological investigations into the roles of protein kinase A in schistosomes, particularly in the context of interactions between the parasite and the host. PMID:26777870

  10. The Crystal Structure of Cancer Osaka Thyroid Kinase Reveals an Unexpected Kinase Domain Fold*

    PubMed Central

    Gutmann, Sascha; Hinniger, Alexandra; Fendrich, Gabriele; Drückes, Peter; Antz, Sylvie; Mattes, Henri; Möbitz, Henrik; Ofner, Silvio; Schmiedeberg, Niko; Stojanovic, Aleksandar; Rieffel, Sebastien; Strauss, André; Troxler, Thomas; Glatthar, Ralf; Sparrer, Helmut

    2015-01-01

    Macrophages are important cellular effectors in innate immune responses and play a major role in autoimmune diseases such as rheumatoid arthritis. Cancer Osaka thyroid (COT) kinase, also known as mitogen-activated protein kinase kinase kinase 8 (MAP3K8) and tumor progression locus 2 (Tpl-2), is a serine-threonine (ST) kinase and is a key regulator in the production of pro-inflammatory cytokines in macrophages. Due to its pivotal role in immune biology, COT kinase has been identified as an attractive target for pharmaceutical research that is directed at the discovery of orally available, selective, and potent inhibitors for the treatment of autoimmune disorders and cancer. The production of monomeric, recombinant COT kinase has proven to be very difficult, and issues with solubility and stability of the enzyme have hampered the discovery and optimization of potent and selective inhibitors. We developed a protocol for the production of recombinant human COT kinase that yields pure and highly active enzyme in sufficient yields for biochemical and structural studies. The quality of the enzyme allowed us to establish a robust in vitro phosphorylation assay for the efficient biochemical characterization of COT kinase inhibitors and to determine the x-ray co-crystal structures of the COT kinase domain in complex with two ATP-binding site inhibitors. The structures presented in this study reveal two distinct ligand binding modes and a unique kinase domain architecture that has not been observed previously. The structurally versatile active site significantly impacts the design of potent, low molecular weight COT kinase inhibitors. PMID:25918157

  11. The Crystal Structure of Cancer Osaka Thyroid Kinase Reveals an Unexpected Kinase Domain Fold.

    PubMed

    Gutmann, Sascha; Hinniger, Alexandra; Fendrich, Gabriele; Drückes, Peter; Antz, Sylvie; Mattes, Henri; Möbitz, Henrik; Ofner, Silvio; Schmiedeberg, Niko; Stojanovic, Aleksandar; Rieffel, Sebastien; Strauss, André; Troxler, Thomas; Glatthar, Ralf; Sparrer, Helmut

    2015-06-12

    Macrophages are important cellular effectors in innate immune responses and play a major role in autoimmune diseases such as rheumatoid arthritis. Cancer Osaka thyroid (COT) kinase, also known as mitogen-activated protein kinase kinase kinase 8 (MAP3K8) and tumor progression locus 2 (Tpl-2), is a serine-threonine (ST) kinase and is a key regulator in the production of pro-inflammatory cytokines in macrophages. Due to its pivotal role in immune biology, COT kinase has been identified as an attractive target for pharmaceutical research that is directed at the discovery of orally available, selective, and potent inhibitors for the treatment of autoimmune disorders and cancer. The production of monomeric, recombinant COT kinase has proven to be very difficult, and issues with solubility and stability of the enzyme have hampered the discovery and optimization of potent and selective inhibitors. We developed a protocol for the production of recombinant human COT kinase that yields pure and highly active enzyme in sufficient yields for biochemical and structural studies. The quality of the enzyme allowed us to establish a robust in vitro phosphorylation assay for the efficient biochemical characterization of COT kinase inhibitors and to determine the x-ray co-crystal structures of the COT kinase domain in complex with two ATP-binding site inhibitors. The structures presented in this study reveal two distinct ligand binding modes and a unique kinase domain architecture that has not been observed previously. The structurally versatile active site significantly impacts the design of potent, low molecular weight COT kinase inhibitors.

  12. Protein Kinase A: A Master Kinase of Granulosa Cell Differentiation

    PubMed Central

    Puri, Pawan; Little-Ihrig, Lynda; Chandran, Uma; Law, Nathan C.; Hunzicker-Dunn, Mary; Zeleznik, Anthony J.

    2016-01-01

    Activation of protein kinase A (PKA) by follicle stimulating hormone (FSH) transduces the signal that drives differentiation of ovarian granulosa cells (GCs). An unresolved question is whether PKA is sufficient to initiate the complex program of GC responses to FSH. We compared signaling pathways and gene expression profiles of GCs stimulated with FSH or expressing PKA-CQR, a constitutively active mutant of PKA. Both FSH and PKA-CQR stimulated the phosphorylation of proteins known to be involved in GC differentiation including CREB, ß-catenin, AKT, p42/44 MAPK, GAB2, GSK-3ß, FOXO1, and YAP. In contrast, FSH stimulated the phosphorylation of p38 MAP kinase but PKA-CQR did not. Microarray analysis revealed that 85% of transcripts that were up-regulated by FSH were increased to a comparable extent by PKA-CQR and of the transcripts that were down-regulated by FSH, 76% were also down-regulated by PKA-CQR. Transcripts regulated similarly by FSH and PKA-CQR are involved in steroidogenesis and differentiation, while transcripts more robustly up-regulated by PKA-CQR are involved in ovulation. Thus, PKA, under the conditions of our experimental approach appears to function as a master upstream kinase that is sufficient to initiate the complex pattern of intracellular signaling pathway and gene expression profiles that accompany GC differentiation. PMID:27324437

  13. Genetic interactions of yeast eukaryotic translation initiation factor 5A (eIF5A) reveal connections to poly(A)-binding protein and protein kinase C signaling.

    PubMed Central

    Valentini, Sandro R; Casolari, Jason M; Oliveira, Carla C; Silver, Pamela A; McBride, Anne E

    2002-01-01

    The highly conserved eukaryotic translation initiation factor eIF5A has been proposed to have various roles in the cell, from translation to mRNA decay to nuclear protein export. To further our understanding of this essential protein, three temperature-sensitive alleles of the yeast TIF51A gene have been characterized. Two mutant eIF5A proteins contain mutations in a proline residue at the junction between the two eIF5A domains and the third, strongest allele encodes a protein with a single mutation in each domain, both of which are required for the growth defect. The stronger tif51A alleles cause defects in degradation of short-lived mRNAs, supporting a role for this protein in mRNA decay. A multicopy suppressor screen revealed six genes, the overexpression of which allows growth of a tif51A-1 strain at high temperature; these genes include PAB1, PKC1, and PKC1 regulators WSC1, WSC2, and WSC3. Further results suggest that eIF5A may also be involved in ribosomal synthesis and the WSC/PKC1 signaling pathway for cell wall integrity or related processes. PMID:11861547

  14. SUMOylation regulates the SNF1 protein kinase.

    PubMed

    Simpson-Lavy, Kobi J; Johnston, Mark

    2013-10-22

    The AMP-activated protein kinase (AMPK) is a major stress sensor of mammalian cells. AMPK's homolog in the yeast Saccharomyces cerevisiae, the SNF1 protein kinase, is a central regulator of carbon metabolism that inhibits the Snf3/Rgt2-Rgt1 glucose sensing pathway and activates genes involved in respiration. We present evidence that glucose induces modification of the Snf1 catalytic subunt of SNF1 with the small ubiquitin-like modifier protein SUMO, catalyzed by the SUMO (E3) ligase Mms21. Our results suggest that SUMOylation of Snf1 inhibits its function in two ways: by interaction of SUMO attached to lysine 549 with a SUMO-interacting sequence motif located near the active site of Snf1, and by targeting Snf1 for destruction via the Slx5-Slx8 (SUMO-directed) ubiquitin ligase. These findings reveal another way SNF1 function is regulated in response to carbon source.

  15. Mitogen-activated protein kinase cascades in Vitis vinifera

    PubMed Central

    Çakır, Birsen; Kılıçkaya, Ozan

    2015-01-01

    Protein phosphorylation is one of the most important mechanisms to control cellular functions in response to external and endogenous signals. Mitogen-activated protein kinases (MAPK) are universal signaling molecules in eukaryotes that mediate the intracellular transmission of extracellular signals resulting in the induction of appropriate cellular responses. MAPK cascades are composed of four protein kinase modules: MAPKKK kinases (MAPKKKKs), MAPKK kinases (MAPKKKs), MAPK kinases (MAPKKs), and MAPKs. In plants, MAPKs are activated in response to abiotic stresses, wounding, and hormones, and during plant pathogen interactions and cell division. In this report, we performed a complete inventory of MAPK cascades genes in Vitis vinifera, the whole genome of which has been sequenced. By comparison with MAPK, MAPK kinases, MAPK kinase kinases and MAPK kinase kinase kinase kinase members of Arabidopsis thaliana, we revealed the existence of 14 MAPKs, 5 MAPKKs, 62 MAPKKKs, and 7 MAPKKKKs in Vitis vinifera. We identified orthologs of V. vinifera putative MAPKs in different species, and ESTs corresponding to members of MAPK cascades in various tissues. This work represents the first complete inventory of MAPK cascades in V. vinifera and could help elucidate the biological and physiological functions of these proteins in V. vinifera. PMID:26257761

  16. Constitutively Active Mitogen-Activated Protein Kinase Versions Reveal Functions of Arabidopsis MPK4 in Pathogen Defense Signaling[C][W

    PubMed Central

    Berriri, Souha; Garcia, Ana Victoria; dit Frey, Nicolas Frei; Rozhon, Wilfried; Pateyron, Stéphanie; Leonhardt, Nathalie; Montillet, Jean-Luc; Leung, Jeffrey; Hirt, Heribert; Colcombet, Jean

    2012-01-01

    Plant mitogen-activated protein kinases (MAPKs) are involved in important processes, including stress signaling and development. In a functional yeast screen, we identified mutations that render Arabidopsis thaliana MAPKs constitutively active (CA). Importantly, CA-MAPKs maintain their specificity toward known activators and substrates. As a proof-of-concept, Arabidopsis MAPK4 (MPK4) function in plant immunity was investigated. In agreement with the phenotype of mpk4 mutants, CA-MPK4 plants were compromised in pathogen-induced salicylic acid accumulation and disease resistance. MPK4 activity was found to negatively regulate pathogen-associated molecular pattern-induced reactive oxygen species production but had no impact on callose deposition, indicating that CA-MPK4 allows discriminating between processes regulated by MPK4 activity from processes indirectly affected by mpk4 mutation. Finally, MPK4 activity was also found to compromise effector-triggered immunity conditioned by the Toll Interleukin-1 Receptor–nucleotide binding (NB)–Leu-rich repeat (LRR) receptors RPS4 and RPP4 but not by the coiled coil–NB-LRR receptors RPM1 and RPS2. Overall, these data reveal important insights on how MPK4 regulates plant defenses and establishes that CA-MAPKs offer a powerful tool to analyze the function of plant MAPK pathways. PMID:23115249

  17. Structures of cGMP-Dependent Protein Kinase (PKG) Iα Leucine Zippers Reveal an Interchain Disulfide Bond Important for Dimer Stability.

    PubMed

    Qin, Liying; Reger, Albert S; Guo, Elaine; Yang, Matthew P; Zwart, Peter; Casteel, Darren E; Kim, Choel

    2015-07-28

    cGMP-dependent protein kinase (PKG) Iα is a central regulator of smooth muscle tone and vasorelaxation. The N-terminal leucine zipper (LZ) domain dimerizes and targets PKG Iα by interacting with G-kinase-anchoring proteins. The PKG Iα LZ contains C42 that is known to form a disulfide bond upon oxidation and to activate PKG Iα. To understand the molecular details of the PKG Iα LZ and C42-C42' disulfide bond, we determined crystal structures of the PKG Iα wild-type (WT) LZ and C42L LZ. Our data demonstrate that the C42-C42' disulfide bond dramatically stabilizes PKG Iα and that the C42L mutant mimics the oxidized WT LZ structurally.

  18. Structures of cGMP-Dependent Protein Kinase (PKG) Iα Leucine Zippers Reveal an Interchain Disulfide Bond Important for Dimer Stability

    PubMed Central

    Qin, Liying; Reger, Albert S.; Guo, Elaine; Yang, Matthew P.; Zwart, Peter; Casteel, Darren E.; Kim, Choel

    2016-01-01

    cGMP-dependent protein kinase (PKG) Iα is a central regulator of smooth muscle tone and vasorelaxation. The N-terminal leucine zipper (LZ) domain dimerizes and targets PKG Iα by interacting with G-kinase-anchoring proteins. The PKG Iα LZ contains C42 that is known to form a disulfide bond upon oxidation and to activate PKG Iα. To understand the molecular details of the PKG Iα LZ and C42–C42′ disulfide bond, we determined crystal structures of the PKG Iα wild-type (WT) LZ and C42L LZ. Our data demonstrate that the C42–C42′ disulfide bond dramatically stabilizes PKG Iα and that the C42L mutant mimics the oxidized WT LZ structurally. PMID:26132214

  19. The Multiple Personalities of the Regulatory Subunit of Protein Kinase CK2: CK2 Dependent and CK2 Independent Roles Reveal a Secret Identity for CK2β

    PubMed Central

    2005-01-01

    Protein kinase CK2 (formerly casein kinase II), an enzyme that participates in a wide variety of cellular processes, has traditionally been classified as a stable tetrameric complex consisting of two catalytic CK2α or CK2α' subunits and two regulatory CK2β subunits. While consideration of CK2 as a tetrameric complex remains relevant, significant evidence has emerged to challenge the view that its individual subunits exist exclusively within these complexes. This review will summarize biochemical and genetic evidence indicating that the regulatory CK2β subunit exists and performs functions independently of CK2 tetramers. For example, unbalanced expression of catalytic and regulatory CK2 subunits has been observed in a variety of tissues and tumors. Furthermore, localization studies including live cell imaging have demonstrated that while the catalytic and regulatory subunits of CK2 exhibit extensive co-localization, independent mobility of the individual CK2 subunits can also be observed within cells. Identification of proteins that interact with CK2β in the absence of catalytic CK2 subunits reinforces the notion that CK2β has functions distinct from CK2 and begins to offer insights into these CK2-independent functions. In this respect, the discovery that CK2β can interact with and modulate the activity of a number of other serine/threonine protein kinases including A-Raf, c-Mos and Chk1 is particularly striking. This review will discuss the interactions between CK2β and these protein kinases with special emphasis on the properties of CK2β that mediate these interactions and on the implications of these interactions in yielding new prospects for elucidation of the cellular functions of CK2β. PMID:15951851

  20. Auxin efflux by PIN-FORMED proteins is activated by two different protein kinases, D6 PROTEIN KINASE and PINOID.

    PubMed

    Zourelidou, Melina; Absmanner, Birgit; Weller, Benjamin; Barbosa, Inês C R; Willige, Björn C; Fastner, Astrid; Streit, Verena; Port, Sarah A; Colcombet, Jean; de la Fuente van Bentem, Sergio; Hirt, Heribert; Kuster, Bernhard; Schulze, Waltraud X; Hammes, Ulrich Z; Schwechheimer, Claus

    2014-06-19

    The development and morphology of vascular plants is critically determined by synthesis and proper distribution of the phytohormone auxin. The directed cell-to-cell distribution of auxin is achieved through a system of auxin influx and efflux transporters. PIN-FORMED (PIN) proteins are proposed auxin efflux transporters, and auxin fluxes can seemingly be predicted based on the--in many cells--asymmetric plasma membrane distribution of PINs. Here, we show in a heterologous Xenopus oocyte system as well as in Arabidopsis thaliana inflorescence stems that PIN-mediated auxin transport is directly activated by D6 PROTEIN KINASE (D6PK) and PINOID (PID)/WAG kinases of the Arabidopsis AGCVIII kinase family. At the same time, we reveal that D6PKs and PID have differential phosphosite preferences. Our study suggests that PIN activation by protein kinases is a crucial component of auxin transport control that must be taken into account to understand auxin distribution within the plant.

  1. Plant protein kinase substrates identification using protein microarrays.

    PubMed

    Ma, Shisong; Dinesh-Kumar, Savithramma P

    2015-01-01

    Protein kinases regulate signaling pathways by phosphorylating their targets. They play critical roles in plant signaling networks. Although many important protein kinases have been identified in plants, their substrates are largely unknown. We have developed and produced plant protein microarrays with more than 15,000 purified plant proteins. Here, we describe a detailed protocol to use these microarrays to identify plant protein kinase substrates via in vitro phosphorylation assays on these arrays. PMID:25930701

  2. Crystal structures of two aminoglycoside kinases bound with a eukaryotic protein kinase inhibitor.

    PubMed

    Fong, Desiree H; Xiong, Bing; Hwang, Jiyoung; Berghuis, Albert M

    2011-05-09

    Antibiotic resistance is recognized as a growing healthcare problem. To address this issue, one strategy is to thwart the causal mechanism using an adjuvant in partner with the antibiotic. Aminoglycosides are a class of clinically important antibiotics used for the treatment of serious infections. Their usefulness has been compromised predominantly due to drug inactivation by aminoglycoside-modifying enzymes, such as aminoglycoside phosphotransferases or kinases. These kinases are structurally homologous to eukaryotic Ser/Thr and Tyr protein kinases and it has been shown that some can be inhibited by select protein kinase inhibitors. The aminoglycoside kinase, APH(3')-IIIa, can be inhibited by CKI-7, an ATP-competitive inhibitor for the casein kinase 1. We have determined that CKI-7 is also a moderate inhibitor for the atypical APH(9)-Ia. Here we present the crystal structures of CKI-7-bound APH(3')-IIIa and APH(9)-Ia, the first structures of a eukaryotic protein kinase inhibitor in complex with bacterial kinases. CKI-7 binds to the nucleotide-binding pocket of the enzymes and its binding alters the conformation of the nucleotide-binding loop, the segment homologous to the glycine-rich loop in eukaryotic protein kinases. Comparison of these structures with the CKI-7-bound casein kinase 1 reveals features in the binding pockets that are distinct in the bacterial kinases and could be exploited for the design of a bacterial kinase specific inhibitor. Our results provide evidence that an inhibitor for a subset of APHs can be developed in order to curtail resistance to aminoglycosides.

  3. Characterization of protein kinases from Blepharisma intermedium.

    PubMed

    Beyer, J

    1975-12-01

    Three protein kinases (EC 2.7.1.37) were detected in Blepharisma and partially purified. The enzymes were most active with histone as substrate protein. The stability of the bond between phosphate and protein acceptor showed the characteristics of seryl- or threonylphosphate. Protein kinase I was solubilized by ultrasonication or freezing and thawing, while the enzymes II and III were readily solubilized by mild homogenization. Protein II and III were noticeably activated by cAMP and cGMP, while protein kinase I was inhibited by cAMP. Associated with protein kinase II and III activity was the ability to bind labeled cAMP. The following molecular weights were determined: 90000 for enzyme I, 280000 for enzyme II, and 95000 for enzyme III. Various apparent Michaelis constants were estimated.

  4. Purine inhibitors of protein kinases, G proteins and polymerases

    DOEpatents

    Gray, Nathanael S.; Schultz, Peter; Kim, Sung-Hou; Meijer, Laurent

    2001-07-03

    The present invention relates to purine analogs that inhibit, inter alia, protein kinases, G-proteins and polymerases. In addition, the present invention relates to methods of using such purine analogs to inhibit protein kinases, G-proteins, polymerases and other cellular processes and to treat cellular proliferative diseases.

  5. Ternary structure reveals mechanism of a membrane diacylglycerol kinase

    SciTech Connect

    Li, Dianfan; Stansfeld, Phillip J.; Sansom, Mark S. P.; Keogh, Aaron; Vogeley, Lutz; Howe, Nicole; Lyons, Joseph A.; Aragao, David; Fromme, Petra; Fromme, Raimund; Basu, Shibom; Grotjohann, Ingo; Kupitz, Christopher; Rendek, Kimberley; Weierstall, Uwe; Zatsepin, Nadia A.; Cherezov, Vadim; Liu, Wei; Bandaru, Sateesh; English, Niall J.; Gati, Cornelius; Barty, Anton; Yefanov, Oleksandr; Chapman, Henry N.; Diederichs, Kay; Messerschmidt, Marc; Boutet, Sébastien; Williams, Garth J.; Marvin Seibert, M.; Caffrey, Martin

    2015-12-17

    Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternary structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. As a result, the active site architecture shows clear evidence of having arisen by convergent evolution.

  6. Ternary structure reveals mechanism of a membrane diacylglycerol kinase

    PubMed Central

    Li, Dianfan; Stansfeld, Phillip J.; Sansom, Mark S. P.; Keogh, Aaron; Vogeley, Lutz; Howe, Nicole; Lyons, Joseph A.; Aragao, David; Fromme, Petra; Fromme, Raimund; Basu, Shibom; Grotjohann, Ingo; Kupitz, Christopher; Rendek, Kimberley; Weierstall, Uwe; Zatsepin, Nadia A.; Cherezov, Vadim; Liu, Wei; Bandaru, Sateesh; English, Niall J.; Gati, Cornelius; Barty, Anton; Yefanov, Oleksandr; Chapman, Henry N.; Diederichs, Kay; Messerschmidt, Marc; Boutet, Sébastien; Williams, Garth J.; Marvin Seibert, M.; Caffrey, Martin

    2015-01-01

    Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternary structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. The active site architecture shows clear evidence of having arisen by convergent evolution. PMID:26673816

  7. Ternary structure reveals mechanism of a membrane diacylglycerol kinase.

    PubMed

    Li, Dianfan; Stansfeld, Phillip J; Sansom, Mark S P; Keogh, Aaron; Vogeley, Lutz; Howe, Nicole; Lyons, Joseph A; Aragao, David; Fromme, Petra; Fromme, Raimund; Basu, Shibom; Grotjohann, Ingo; Kupitz, Christopher; Rendek, Kimberley; Weierstall, Uwe; Zatsepin, Nadia A; Cherezov, Vadim; Liu, Wei; Bandaru, Sateesh; English, Niall J; Gati, Cornelius; Barty, Anton; Yefanov, Oleksandr; Chapman, Henry N; Diederichs, Kay; Messerschmidt, Marc; Boutet, Sébastien; Williams, Garth J; Marvin Seibert, M; Caffrey, Martin

    2015-12-17

    Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternary structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. The active site architecture shows clear evidence of having arisen by convergent evolution.

  8. Ternary structure reveals mechanism of a membrane diacylglycerol kinase

    NASA Astrophysics Data System (ADS)

    Li, Dianfan; Stansfeld, Phillip J.; Sansom, Mark S. P.; Keogh, Aaron; Vogeley, Lutz; Howe, Nicole; Lyons, Joseph A.; Aragao, David; Fromme, Petra; Fromme, Raimund; Basu, Shibom; Grotjohann, Ingo; Kupitz, Christopher; Rendek, Kimberley; Weierstall, Uwe; Zatsepin, Nadia A.; Cherezov, Vadim; Liu, Wei; Bandaru, Sateesh; English, Niall J.; Gati, Cornelius; Barty, Anton; Yefanov, Oleksandr; Chapman, Henry N.; Diederichs, Kay; Messerschmidt, Marc; Boutet, Sébastien; Williams, Garth J.; Marvin Seibert, M.; Caffrey, Martin

    2015-12-01

    Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternary structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. The active site architecture shows clear evidence of having arisen by convergent evolution.

  9. Ternary structure reveals mechanism of a membrane diacylglycerol kinase.

    PubMed

    Li, Dianfan; Stansfeld, Phillip J; Sansom, Mark S P; Keogh, Aaron; Vogeley, Lutz; Howe, Nicole; Lyons, Joseph A; Aragao, David; Fromme, Petra; Fromme, Raimund; Basu, Shibom; Grotjohann, Ingo; Kupitz, Christopher; Rendek, Kimberley; Weierstall, Uwe; Zatsepin, Nadia A; Cherezov, Vadim; Liu, Wei; Bandaru, Sateesh; English, Niall J; Gati, Cornelius; Barty, Anton; Yefanov, Oleksandr; Chapman, Henry N; Diederichs, Kay; Messerschmidt, Marc; Boutet, Sébastien; Williams, Garth J; Marvin Seibert, M; Caffrey, Martin

    2015-01-01

    Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternary structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. The active site architecture shows clear evidence of having arisen by convergent evolution. PMID:26673816

  10. Systematic deletion analysis of fission yeast protein kinases.

    PubMed

    Bimbó, Andrea; Jia, Yonghui; Poh, Siew Lay; Karuturi, R Krishna Murthy; den Elzen, Nicole; Peng, Xu; Zheng, Liling; O'Connell, Matthew; Liu, Edison T; Balasubramanian, Mohan K; Liu, Jianhua

    2005-04-01

    Eukaryotic protein kinases are key molecules mediating signal transduction that play a pivotal role in the regulation of various biological processes, including cell cycle progression, cellular morphogenesis, development, and cellular response to environmental changes. A total of 106 eukaryotic protein kinase catalytic-domain-containing proteins have been found in the entire fission yeast genome, 44% (or 64%) of which possess orthologues (or nearest homologues) in humans, based on sequence similarity within catalytic domains. Systematic deletion analysis of all putative protein kinase-encoding genes have revealed that 17 out of 106 were essential for viability, including three previously uncharacterized putative protein kinases. Although the remaining 89 protein kinase mutants were able to form colonies under optimal growth conditions, 46% of the mutants exhibited hypersensitivity to at least 1 of the 17 different stress factors tested. Phenotypic assessment of these mutants allowed us to arrange kinases into functional groups. Based on the results of this assay, we propose also the existence of four major signaling pathways that are involved in the response to 17 stresses tested. Microarray analysis demonstrated a significant correlation between the expression signature and growth phenotype of kinase mutants tested. Our complete microarray data sets are available at http://giscompute.gis.a-star.edu.sg/~gisljh/kinome. PMID:15821139

  11. Global Analysis of Serine/Threonine and Tyrosine Protein Phosphatase Catalytic Subunit Genes in Neurospora crassa Reveals Interplay Between Phosphatases and the p38 Mitogen-Activated Protein Kinase

    PubMed Central

    Ghosh, Arit; Servin, Jacqueline A.; Park, Gyungsoon; Borkovich, Katherine A.

    2013-01-01

    Protein phosphatases are integral components of the cellular signaling machinery in eukaryotes, regulating diverse aspects of growth and development. The genome of the filamentous fungus and model organism Neurospora crassa encodes catalytic subunits for 30 protein phosphatase genes. In this study, we have characterized 24 viable N. crassa phosphatase catalytic subunit knockout mutants for phenotypes during growth, asexual development, and sexual development. We found that 91% of the mutants had defects in at least one of these traits, whereas 29% possessed phenotypes in all three. Chemical sensitivity screens were conducted to reveal additional phenotypes for the mutants. This resulted in the identification of at least one chemical sensitivity phenotype for 17 phosphatase knockout mutants, including novel chemical sensitivities for two phosphatase mutants lacking a growth or developmental phenotype. Hence, chemical sensitivity or growth/developmental phenotype was observed for all 24 viable mutants. We investigated p38 mitogen-activated protein kinase (MAPK) phosphorylation profiles in the phosphatase mutants and identified nine potential candidates for regulators of the p38 MAPK. We demonstrated that the PP2C class phosphatase pph-8 (NCU04600) is an important regulator of female sexual development in N. crassa. In addition, we showed that the Δcsp-6 (ΔNCU08380) mutant exhibits a phenotype similar to the previously identified conidial separation mutants, Δcsp-1 and Δcsp-2, that lack transcription factors important for regulation of conidiation and the circadian clock. PMID:24347630

  12. Evolutionary Ancestry of Eukaryotic Protein Kinases and Choline Kinases.

    PubMed

    Lai, Shenshen; Safaei, Javad; Pelech, Steven

    2016-03-01

    The reversible phosphorylation of proteins catalyzed by protein kinases in eukaryotes supports an important role for eukaryotic protein kinases (ePKs) in the emergence of nucleated cells in the third superkingdom of life. Choline kinases (ChKs) could also be critical in the early evolution of eukaryotes, because of their function in the biosynthesis of phosphatidylcholine, which is unique to eukaryotic membranes. However, the genomic origins of ePKs and ChKs are unclear. The high degeneracy of protein sequences and broad expansion of ePK families have made this fundamental question difficult to answer. In this study, we identified two class-I aminoacyl-tRNA synthetases with high similarities to consensus amino acid sequences of human protein-serine/threonine kinases. Comparisons of primary and tertiary structures supported that ePKs and ChKs evolved from a common ancestor related to glutaminyl aminoacyl-tRNA synthetases, which may have been one of the key factors in the successful of emergence of ancient eukaryotic cells from bacterial colonies.

  13. Leishmania amazonensis: PKC-like protein kinase modulates the (Na++K+)ATPase activity.

    PubMed

    Almeida-Amaral, Elmo Eduardo de; Caruso-Neves, Celso; Lara, Lucienne Silva; Pinheiro, Carla Mônica; Meyer-Fernandes, José Roberto

    2007-08-01

    The present study aimed to identify the presence of protein kinase C-like (PKC-like) in Leishmania amazonensis and to elucidate its possible role in the modulation of the (Na(+)+K(+))ATPase activity. Immunoblotting experiments using antibody against a consensus sequence (Ac 543-549) of rabbit protein kinase C (PKC) revealed the presence of a protein kinase of 80 kDa in L. amazonensis. Measurements of protein kinase activity showed the presence of both (Ca(2+)-dependent) and (Ca(2+)-independent) protein kinase activity in plasma membrane and cytosol. Phorbol ester (PMA) activation of the Ca(2+)-dependent protein kinase stimulated the (Na(+)+K(+))ATPase activity, while activation of the Ca(2+)-independent protein kinase was inhibitory. Both effects of protein kinase on the (Na(+)+K(+))ATPase of the plasma membrane were lower than that observed in intact cells. PMA induced the translocation of protein kinase from cytosol to plasma membrane, indicating that the maximal effect of protein kinase on the (Na(+)+K(+))ATPase activity depends on the synergistic action of protein kinases from both plasma membrane and cytosol. This is the first demonstration of a protein kinase activated by PMA in L. amazonensis and the first evidence for a possible role in the regulation of the (Na(+)+K(+))ATPase activity in this trypanosomatid. Modulation of the (Na(+)+K(+))ATPase by protein kinase in a trypanosomatid opens up new possibilities to understand the regulation of ion homeostasis in this parasite. PMID:17475255

  14. Protein kinase profiling assays: a technology review.

    PubMed

    Wang, Yuren; Ma, Haiching

    2015-11-01

    Protein kinases have become one of the most intensively pursued classes of drug targets for many diseases such as cancers and inflammatory diseases. Kinase profiling work seeks to understand general selectivity trends of lead compounds across the kinome, which help with target selection, compound prioritization, and potential implications in toxicity. Under the current drug discovery process, screening of compounds against comprehensive panels of kinases and their mutants has become the standard approach. Many screening assays and technologies which are compatible for high-throughput screening (HTS) against kinases have been extensively pursued and developed.

  15. Actions of Rho family small G proteins and p21-activated protein kinases on mitogen-activated protein kinase family members.

    PubMed Central

    Frost, J A; Xu, S; Hutchison, M R; Marcus, S; Cobb, M H

    1996-01-01

    The mitogen-activated protein (MAP) kinases are a family of serine/threonine kinases that are regulated by distinct extracellular stimuli. The currently known members include extracellular signal-regulated protein kinase 1 (ERK1), ERK2, the c-Jun N-terminal kinase/stress-activated protein kinases (JNK/SAPKs), and p38 MAP kinases. We find that overexpression of the Ste20-related enzymes p21-activated kinase 1 (PAK1) and PAK2 in 293 cells is sufficient to activate JNK/SAPK and to a lesser extent p38 MAP kinase but not ERK2. Rat MAP/ERK kinase kinase 1 can stimulate the activity of each of these MAP kinases. Although neither activated Rac nor the PAKs stimulate ERK2 activity, overexpression of either dominant negative Rac2 or the N-terminal regulatory domain of PAK1 inhibits Ras-mediated activation of ERK2, suggesting a permissive role for Rac in the control of the ERK pathway. Furthermore, constitutively active Rac2, Cdc42hs, and RhoA synergize with an activated form of Raf to increase ERK2 activity. These findings reveal a previously unrecognized connection between Rho family small G proteins and the ERK pathway. PMID:8668187

  16. Dynamics of Protein Kinases: Insights from Nuclear Magnetic Resonance

    PubMed Central

    Xiao, Yao; Liddle, Jennifer C.; Pardi, Arthur; Ahn, Natalie G.

    2015-01-01

    CONSPECTUS Protein kinases are ubiquitous enzymes with critical roles in cellular processes and pathology. As a result, researchers have studied their activity and regulatory mechanisms extensively. Thousands of X-ray structures give snapshots of the architectures of protein kinases in various states of activation and ligand binding. However, the extent of and manner by which protein motions and conformational dynamics underlie the function and regulation of these important enzymes is not well understood. Nuclear magnetic resonance (NMR) methods provide complementary information about protein conformation and dynamics in solution. However, until recently, the large size of these enzymes prevented researchers from using these methods with kinases. Developments in transverse relaxation-optimized spectroscopy (TROSY)-based techniques and more efficient isotope labeling strategies are now allowing researchers to carry out NMR studies on full-length protein kinases. In this Account, we describe recent insights into the role of dynamics in protein kinase regulation and catalysis that have been gained from NMR measurements of chemical shift changes and line broadening, residual dipolar couplings, and relaxation. These findings show strong associations between protein motion and events that control kinase activity. Dynamic and conformational changes occurring at ligand binding sites and other regulatory domains of these proteins propagate to conserved kinase core regions that mediate catalytic function. NMR measurements of slow time scale (microsecond to millisecond) motions also reveal that kinases carry out global exchange processes that synchronize multiple residues and allosteric interconversion between conformational states. Activating covalent modifications or ligand binding to form the Michaelis complex can induce these global processes. Inhibitors can also exploit the exchange properties of kinases by using conformational selection to form dynamically quenched

  17. Proteomic and Metabolic Analyses of S49 Lymphoma Cells Reveal Novel Regulation of Mitochondria by cAMP and Protein Kinase A.

    PubMed

    Wilderman, Andrea; Guo, Yurong; Divakaruni, Ajit S; Perkins, Guy; Zhang, Lingzhi; Murphy, Anne N; Taylor, Susan S; Insel, Paul A

    2015-09-01

    Cyclic AMP (cAMP), acting via protein kinase A (PKA), regulates many cellular responses, but the role of mitochondria in such responses is poorly understood. To define such roles, we used quantitative proteomic analysis of mitochondria-enriched fractions and performed functional and morphologic studies of wild-type (WT) and kin(-) (PKA-null) murine S49 lymphoma cells. Basally, 75 proteins significantly differed in abundance between WT and kin(-) S49 cells. WT, but not kin(-), S49 cells incubated with the cAMP analog 8-(4-chlorophenylthio)adenosine cAMP (CPT-cAMP) for 16 h have (a) increased expression of mitochondria-related genes and proteins, including ones in pathways of branched-chain amino acid and fatty acid metabolism and (b) increased maximal capacity of respiration on branched-chain keto acids and fatty acids. CPT-cAMP also regulates the cellular rate of ATP-utilization, as the rates of both ATP-linked respiration and proton efflux are decreased in WT but not kin(-) cells. CPT-cAMP protected WT S49 cells from glucose or glutamine deprivation, In contrast, CPT-cAMP did not protect kin(-) cells or WT cells treated with the PKA inhibitor H89 from glutamine deprivation. Under basal conditions, the mitochondrial structure of WT and kin(-) S49 cells is similar. Treatment with CPT-cAMP produced apoptotic changes (i.e. decreased mitochondrial density and size and loss of cristae) in WT, but not kin(-) cells. Together, these findings show that cAMP acts via PKA to regulate multiple aspects of mitochondrial function and structure. Mitochondrial perturbation thus likely contributes to cAMP/PKA-mediated cellular responses. PMID:26203188

  18. Proteomic and Metabolic Analyses of S49 Lymphoma Cells Reveal Novel Regulation of Mitochondria by cAMP and Protein Kinase A.

    PubMed

    Wilderman, Andrea; Guo, Yurong; Divakaruni, Ajit S; Perkins, Guy; Zhang, Lingzhi; Murphy, Anne N; Taylor, Susan S; Insel, Paul A

    2015-09-01

    Cyclic AMP (cAMP), acting via protein kinase A (PKA), regulates many cellular responses, but the role of mitochondria in such responses is poorly understood. To define such roles, we used quantitative proteomic analysis of mitochondria-enriched fractions and performed functional and morphologic studies of wild-type (WT) and kin(-) (PKA-null) murine S49 lymphoma cells. Basally, 75 proteins significantly differed in abundance between WT and kin(-) S49 cells. WT, but not kin(-), S49 cells incubated with the cAMP analog 8-(4-chlorophenylthio)adenosine cAMP (CPT-cAMP) for 16 h have (a) increased expression of mitochondria-related genes and proteins, including ones in pathways of branched-chain amino acid and fatty acid metabolism and (b) increased maximal capacity of respiration on branched-chain keto acids and fatty acids. CPT-cAMP also regulates the cellular rate of ATP-utilization, as the rates of both ATP-linked respiration and proton efflux are decreased in WT but not kin(-) cells. CPT-cAMP protected WT S49 cells from glucose or glutamine deprivation, In contrast, CPT-cAMP did not protect kin(-) cells or WT cells treated with the PKA inhibitor H89 from glutamine deprivation. Under basal conditions, the mitochondrial structure of WT and kin(-) S49 cells is similar. Treatment with CPT-cAMP produced apoptotic changes (i.e. decreased mitochondrial density and size and loss of cristae) in WT, but not kin(-) cells. Together, these findings show that cAMP acts via PKA to regulate multiple aspects of mitochondrial function and structure. Mitochondrial perturbation thus likely contributes to cAMP/PKA-mediated cellular responses.

  19. Proteomic and Metabolic Analyses of S49 Lymphoma Cells Reveal Novel Regulation of Mitochondria by cAMP and Protein Kinase A*

    PubMed Central

    Wilderman, Andrea; Guo, Yurong; Divakaruni, Ajit S.; Perkins, Guy; Zhang, Lingzhi; Murphy, Anne N.; Taylor, Susan S.; Insel, Paul A.

    2015-01-01

    Cyclic AMP (cAMP), acting via protein kinase A (PKA), regulates many cellular responses, but the role of mitochondria in such responses is poorly understood. To define such roles, we used quantitative proteomic analysis of mitochondria-enriched fractions and performed functional and morphologic studies of wild-type (WT) and kin− (PKA-null) murine S49 lymphoma cells. Basally, 75 proteins significantly differed in abundance between WT and kin− S49 cells. WT, but not kin−, S49 cells incubated with the cAMP analog 8-(4-chlorophenylthio)adenosine cAMP (CPT-cAMP) for 16 h have (a) increased expression of mitochondria-related genes and proteins, including ones in pathways of branched-chain amino acid and fatty acid metabolism and (b) increased maximal capacity of respiration on branched-chain keto acids and fatty acids. CPT-cAMP also regulates the cellular rate of ATP-utilization, as the rates of both ATP-linked respiration and proton efflux are decreased in WT but not kin− cells. CPT-cAMP protected WT S49 cells from glucose or glutamine deprivation, In contrast, CPT-cAMP did not protect kin− cells or WT cells treated with the PKA inhibitor H89 from glutamine deprivation. Under basal conditions, the mitochondrial structure of WT and kin− S49 cells is similar. Treatment with CPT-cAMP produced apoptotic changes (i.e. decreased mitochondrial density and size and loss of cristae) in WT, but not kin− cells. Together, these findings show that cAMP acts via PKA to regulate multiple aspects of mitochondrial function and structure. Mitochondrial perturbation thus likely contributes to cAMP/PKA-mediated cellular responses. PMID:26203188

  20. Green fluorescent protein tagging of extracellular signal-regulated kinase and p38 pathways reveals novel dynamics of pathway activation during primary and metastatic growth.

    PubMed

    Aguirre-Ghiso, Julio A; Ossowski, Liliana; Rosenbaum, Sarah K

    2004-10-15

    We describe a novel approach that allows detection of primary and metastatic cells in vivo in which either the extracellular signal-regulated kinase (ERK) or the p38 pathway is activated. Our recent findings showed that ERK and p38 kinases regulate, respectively, programs dictating cell proliferation (high ERK-to-p38 ratio) or growth arrest and dormancy (low ERK-to-p38 ratio) in vivo. Thus, we were able to use green fluorescent protein (GFP) to reflect ERK and p38 activities and, consequently, the proliferative state of cancer cells. This was accomplished by transfecting tumorigenic T-HEp3 and HT1080 cells, and dormant D-HEp3 cells, with plasmids coding for Elk-GAL4 or CHOP-GAL4 fusion proteins that, when phosphorylated by either ERK or p38, respectively, transactivated a GFP-reporter gene. The fate of these cells was examined in culture, in primary sites, and in spontaneous metastasis in chick embryos and nude mice. In culture GFP level was directly proportional to the previously established levels of ERK or p38 activation. In contrast, during the first 24 hours of in vivo inoculation, both the tumorigenic and the dormant cells strongly activated the p38 pathway. However, in the tumorigenic cells, p38 activity was rapidly silenced, correcting the ERK/p38 imbalance and contributing to high ERK activity throughout the entire period of tumor growth. In contrast, in the small nodules formed by dormant cells, the level of ERK activity was dramatically reduced, whereas p38 activity remained high. Strong activation of ERK was evident in metastatic sites, whereas p38 activation was silenced in this anatomic location as well. These results show that it is possible to directly measure cancer cell response to microenvironment with this reporter system and that only proliferation-competent cells have the ability to rapidly adapt ERK and p38 signaling for proliferative success. This approach allows isolation and further characterization of metastatic cells with specific

  1. Endogenous protein phosphorylation and protein kinase activity in winged bean.

    PubMed

    Mukhopadhyay, K; Singh, M

    1997-10-01

    In winged bean (Psophocarpus tetragonolobus) protein kinases (E.C. 2.7.1.37) were found in all tissues studied. There was a significant increase in kinase activity during seed development, with a concomitant enhancement in the phosphorylation of a number of polypeptides; this was reversed in germinating seed cotyledons. Protein phosphorylation was apparently correlated with the increase in the protein content of the developing seed and the growing axis. At least three distinct autophosphorylating proteins could be distinguished in the developing seeds after SDS-PAGE, indicating the presence of different types of protein kinases in winged bean.

  2. Transcriptome analysis of cyclic AMP-dependent protein kinase A-regulated genes reveals the production of the novel natural compound fumipyrrole by Aspergillus fumigatus.

    PubMed

    Macheleidt, Juliane; Scherlach, Kirstin; Neuwirth, Toni; Schmidt-Heck, Wolfgang; Straßburger, Maria; Spraker, Joseph; Baccile, Joshua A; Schroeder, Frank C; Keller, Nancy P; Hertweck, Christian; Heinekamp, Thorsten; Brakhage, Axel A

    2015-04-01

    Aspergillus fumigatus is an opportunistic human pathogenic fungus causing life-threatening infections in immunocompromised patients. Adaptation to different habitats and also virulence of the fungus depends on signal perception and transduction by modules such as the cyclic AMP-dependent protein kinase A (PKA) pathway. Here, by transcriptome analysis, 632 differentially regulated genes of this important signaling cascade were identified, including 23 putative transcriptional regulators. The highest upregulated transcription factor gene was located in a previously unknown secondary metabolite gene cluster, which we named fmp, encoding an incomplete non-ribosomal peptide synthetase, FmpE. Overexpression of the regulatory gene fmpR using the Tet(On) system led to the specific expression of the other six genes of the fmp cluster. Metabolic profiling of wild type and fmpR overexpressing strain by HPLC-DAD and HPLC-HRESI-MS and structure elucidation by NMR led to identification of 5-benzyl-1H-pyrrole-2-carboxylic acid, which we named fumipyrrole. Fumipyrrole was not described as natural product yet. Chemical synthesis of fumipyrrole confirmed its structure. Interestingly, deletion of fmpR or fmpE led to reduced growth and sporulation of the mutant strains. Although fmp cluster genes were transcribed in infected mouse lungs, deletion of fmpR resulted in wild-type virulence in a murine infection model.

  3. Purine inhibitors of protein kinases, G proteins and polymerases

    DOEpatents

    Gray, Nathanael S.; Schultz, Peter; Kim, Sung-Hou; Meijer, Laurent

    2004-10-12

    The present invention relates to 2-N-substituted 6-(4-methoxybenzylamino)-9-isopropylpurines that inhibit, inter alia, protein kinases, G-proteins and polymerases. In addition, the present invention relates to methods of using such 2-N-substituted 6-(4-methoxybenzylamino)-9-isopropylpurines to inhibit protein kinases, G-proteins, polymerases and other cellular processes and to treat cellular proliferative diseases.

  4. Protein kinase activators alter glial cholesterol esterification

    SciTech Connect

    Jeng, I.; Dills, C.; Klemm, N.; Wu, C.

    1986-05-01

    Similar to nonneural tissues, the activity of glial acyl-CoA cholesterol acyltransferase is controlled by a phosphorylation and dephosphorylation mechanism. Manipulation of cyclic AMP content did not alter the cellular cholesterol esterification, suggesting that cyclic AMP is not a bioregulator in this case. Therefore, the authors tested the effect of phorbol-12-myristate 13-acetate (PMA) on cellular cholesterol esterification to determine the involvement of protein kinase C. PMA has a potent effect on cellular cholesterol esterification. PMA depresses cholesterol esterification initially, but cells recover from inhibition and the result was higher cholesterol esterification, suggesting dual effects of protein kinase C. Studies of other phorbol analogues and other protein kinase C activators such as merezein indicate the involvement of protein kinase C. Oleoyl-acetyl glycerol duplicates the effect of PMA. This observation is consistent with a diacyl-glycerol-protein kinase-dependent reaction. Calcium ionophore A23187 was ineffective in promoting the effect of PMA. They concluded that a calcium-independent and protein C-dependent pathway regulated glial cholesterol esterification.

  5. Effects of protein phosphatase and kinase inhibitors on the cardiac L- type Ca current suggest two sites are phosphorylated by protein kinase A and another protein kinase

    PubMed Central

    1995-01-01

    We previously showed (Frace, A.M. and H.C. Hartzell. 1993. Journal of Physiology. 472:305-326) that internal perfusion of frog atrial myocytes with the nonselective protein phosphatase inhibitors microcystin or okadaic acid produced an increase in the L-type Ca current (ICa) and a decrease in the delayed rectifier K current (IK). We hypothesized that microcystin revealed the activity of a protein kinase (PKX) that was basally active in the cardiac myocyte that could phosphorylate the Ca and K channels or regulators of the channels. The present studies were aimed at determining the nature of PKX and its phosphorylation target. The effect of internal perfusion with microcystin on ICa or IK was not attenuated by inhibitors of protein kinase A (PKA). However, the effect of microcystin on ICa was largely blocked by the nonselective protein kinase inhibitors staurosporine (10- 30 nM), K252a (250 nM), and H-7 (10 microM). Staurosporine and H-7 also decreased the stimulation of ICa by isoproterenol, but K252a was more selective and blocked the ability of microcystin to stimulate ICa without significantly reducing isoproterenol-stimulated current. Internal perfusion with selective inhibitors of protein kinase C (PKC), including the autoinhibitory pseudosubstrate PKC peptide (PKC(19-31)) and a myristoylated derivative of this peptide had no effect. External application of several PKC inhibitors had negative side effects that prevented their use as selective PKC inhibitors. Nevertheless, we conclude that PKX is not PKC. PKA and PKX phosphorylate sites with different sensitivities to the phosphatase inhibitors calyculin A and microcystin. In contrast to the results with ICa, the effect of microcystin on IK was not blocked by any of the kinase inhibitors tested, suggesting that the effect of microcystin on IK may not be mediated by a protein kinase but may be due to a direct effect of microcystin on the IK channel. PMID:8786340

  6. Focused Proteomics Revealed a Novel Rho-kinase Signaling Pathway in the Heart.

    PubMed

    Yura, Yoshimitsu; Amano, Mutsuki; Takefuji, Mikito; Bando, Tomohiro; Suzuki, Kou; Kato, Katsuhiro; Hamaguchi, Tomonari; Hasanuzzaman Shohag, Md; Takano, Tetsuya; Funahashi, Yasuhiro; Nakamuta, Shinichi; Kuroda, Keisuke; Nishioka, Tomoki; Murohara, Toyoaki; Kaibuchi, Kozo

    2016-08-23

    Protein phosphorylation plays an important role in the physiological regulation of cardiac function. Myocardial contraction and pathogenesis of cardiac diseases have been reported to be associated with adaptive or maladaptive protein phosphorylation; however, phosphorylation signaling in the heart is not fully elucidated. We recently developed a novel kinase-interacting substrate screening (KISS) method for exhaustive screening of protein kinase substrates, using mass spectrometry and affinity chromatography. First, we examined protein phosphorylation by extracellular signal-regulated kinase (ERK) and protein kinase A (PKA), which has been relatively well studied in cardiomyocytes. The KISS method showed that ERK and PKA mediated the phosphorylation of known cardiac-substrates of each kinase such as Rps6ka1 and cTnI, respectively. Using this method, we found about 330 proteins as Rho-kinase-mediated substrates, whose substrate in cardiomyocytes is unknown. Among them, CARP/Ankrd1, a muscle ankyrin repeat protein, was confirmed as a novel Rho-kinase-mediated substrate. We also found that non-phosphorylatable form of CARP repressed cardiac hypertrophy-related gene Myosin light chain-2v (MLC-2v) promoter activity, and decreased cell size of heart derived H9c2 myoblasts more efficiently than wild type-CARP. Thus, focused proteomics enable us to reveal a novel signaling pathway in the heart. PMID:27334702

  7. Studies of mice with cyclic AMP-dependent protein kinase (PKA) defects reveal the critical role of PKA's catalytic subunits in anxiety.

    PubMed

    Briassoulis, George; Keil, Margaret F; Naved, Bilal; Liu, Sophie; Starost, Matthew F; Nesterova, Maria; Gokarn, Nirmal; Batistatos, Anna; Wu, T John; Stratakis, Constantine A

    2016-07-01

    Cyclic adenosine mono-phosphate-dependent protein kinase (PKA) is critically involved in the regulation of behavioral responses. Previous studies showed that PKA's main regulatory subunit, R1α, is involved in anxiety-like behaviors. The purpose of this study was to determine how the catalytic subunit, Cα, might affect R1α's function and determine its effects on anxiety-related behaviors. The marble bury (MB) and elevated plus maze (EPM) tests were used to assess anxiety-like behavior and the hotplate test to assess nociception in wild type (WT) mouse, a Prkar1a heterozygote (Prkar1a(+/-)) mouse with haploinsufficiency for the regulatory subunit (R1α), a Prkaca heterozygote (Prkaca(+/-)) mouse with haploinsufficiency for the catalytic subunit (Cα), and a double heterozygote mouse (Prkar1a(+/-)/Prkaca(+/-)) with haploinsufficiency for both R1α and Cα. We then examined specific brain nuclei involved in anxiety. Results of MB test showed a genotype effect, with increased anxiety-like behavior in Prkar1a(+/-) and Prkar1a(+/-)/Prkaca(+/-) compared to WT mice. In the EPM, Prkar1a(+/-) spent significantly less time in the open arms, while Prkaca(+/-) and Prkar1a(+/-)/Prkaca(+/-) mice displayed less exploratory behavior compared to WT mice. The loss of one Prkar1a allele was associated with a significant increase in PKA activity in the basolateral (BLA) and central (CeA) amygdala and ventromedial hypothalamus (VMH) in both Prkar1a(+/-) and Prkar1a(+/-)/Prkaca(+/-) mice. Alterations of PKA activity induced by haploinsufficiency of its main regulatory or most important catalytic subunits result in anxiety-like behaviors. The BLA, CeA, and VMH are implicated in mediating these PKA effects in brain. PMID:26992826

  8. Oncoprotein protein kinase antibody kit

    DOEpatents

    Karin, Michael; Hibi, Masahiko; Lin, Anning

    2008-12-23

    An isolated polypeptide (JNK) characterized by having a molecular weight of 46 kD as determined by reducing SDS-PAGE, having serine and threonine kinase activity, phosphorylating the c-Jun N-terminal activation domain and polynucleotide sequences and method of detection of JNK are provided herein. JNK phosphorylates c-Jun N-terminal activation domain which affects gene expression from AP-1 sites.

  9. Allosteric activation of apicomplexan calcium-dependent protein kinases.

    PubMed

    Ingram, Jessica R; Knockenhauer, Kevin E; Markus, Benedikt M; Mandelbaum, Joseph; Ramek, Alexander; Shan, Yibing; Shaw, David E; Schwartz, Thomas U; Ploegh, Hidde L; Lourido, Sebastian

    2015-09-01

    Calcium-dependent protein kinases (CDPKs) comprise the major group of Ca2+-regulated kinases in plants and protists. It has long been assumed that CDPKs are activated, like other Ca2+-regulated kinases, by derepression of the kinase domain (KD). However, we found that removal of the autoinhibitory domain from Toxoplasma gondii CDPK1 is not sufficient for kinase activation. From a library of heavy chain-only antibody fragments (VHHs), we isolated an antibody (1B7) that binds TgCDPK1 in a conformation-dependent manner and potently inhibits it. We uncovered the molecular basis for this inhibition by solving the crystal structure of the complex and simulating, through molecular dynamics, the effects of 1B7-kinase interactions. In contrast to other Ca2+-regulated kinases, the regulatory domain of TgCDPK1 plays a dual role, inhibiting or activating the kinase in response to changes in Ca2+ concentrations. We propose that the regulatory domain of TgCDPK1 acts as a molecular splint to stabilize the otherwise inactive KD. This dependence on allosteric stabilization reveals a novel susceptibility in this important class of parasite enzymes.

  10. Non-degradative Ubiquitination of Protein Kinases

    PubMed Central

    Ball, K. Aurelia; Johnson, Jeffrey R.; Lewinski, Mary K.; Guatelli, John; Verschueren, Erik; Krogan, Nevan J.; Jacobson, Matthew P.

    2016-01-01

    Growing evidence supports other regulatory roles for protein ubiquitination in addition to serving as a tag for proteasomal degradation. In contrast to other common post-translational modifications, such as phosphorylation, little is known about how non-degradative ubiquitination modulates protein structure, dynamics, and function. Due to the wealth of knowledge concerning protein kinase structure and regulation, we examined kinase ubiquitination using ubiquitin remnant immunoaffinity enrichment and quantitative mass spectrometry to identify ubiquitinated kinases and the sites of ubiquitination in Jurkat and HEK293 cells. We find that, unlike phosphorylation, ubiquitination most commonly occurs in structured domains, and on the kinase domain, ubiquitination is concentrated in regions known to be important for regulating activity. We hypothesized that ubiquitination, like other post-translational modifications, may alter the conformational equilibrium of the modified protein. We chose one human kinase, ZAP-70, to simulate using molecular dynamics with and without a monoubiquitin modification. In Jurkat cells, ZAP-70 is ubiquitinated at several sites that are not sensitive to proteasome inhibition and thus may have other regulatory roles. Our simulations show that ubiquitination influences the conformational ensemble of ZAP-70 in a site-dependent manner. When monoubiquitinated at K377, near the C-helix, the active conformation of the ZAP-70 C-helix is disrupted. In contrast, when monoubiquitinated at K476, near the kinase hinge region, an active-like ZAP-70 C-helix conformation is stabilized. These results lead to testable hypotheses that ubiquitination directly modulates kinase activity, and that ubiquitination is likely to alter structure, dynamics, and function in other protein classes as well. PMID:27253329

  11. Non-degradative Ubiquitination of Protein Kinases.

    PubMed

    Ball, K Aurelia; Johnson, Jeffrey R; Lewinski, Mary K; Guatelli, John; Verschueren, Erik; Krogan, Nevan J; Jacobson, Matthew P

    2016-06-01

    Growing evidence supports other regulatory roles for protein ubiquitination in addition to serving as a tag for proteasomal degradation. In contrast to other common post-translational modifications, such as phosphorylation, little is known about how non-degradative ubiquitination modulates protein structure, dynamics, and function. Due to the wealth of knowledge concerning protein kinase structure and regulation, we examined kinase ubiquitination using ubiquitin remnant immunoaffinity enrichment and quantitative mass spectrometry to identify ubiquitinated kinases and the sites of ubiquitination in Jurkat and HEK293 cells. We find that, unlike phosphorylation, ubiquitination most commonly occurs in structured domains, and on the kinase domain, ubiquitination is concentrated in regions known to be important for regulating activity. We hypothesized that ubiquitination, like other post-translational modifications, may alter the conformational equilibrium of the modified protein. We chose one human kinase, ZAP-70, to simulate using molecular dynamics with and without a monoubiquitin modification. In Jurkat cells, ZAP-70 is ubiquitinated at several sites that are not sensitive to proteasome inhibition and thus may have other regulatory roles. Our simulations show that ubiquitination influences the conformational ensemble of ZAP-70 in a site-dependent manner. When monoubiquitinated at K377, near the C-helix, the active conformation of the ZAP-70 C-helix is disrupted. In contrast, when monoubiquitinated at K476, near the kinase hinge region, an active-like ZAP-70 C-helix conformation is stabilized. These results lead to testable hypotheses that ubiquitination directly modulates kinase activity, and that ubiquitination is likely to alter structure, dynamics, and function in other protein classes as well.

  12. Pyruvate Kinase M2 Regulates Gene Transcription by Acting as A Protein Kinase

    PubMed Central

    Gao, Xueliang; Wang, Haizhen; Jenny, J. Yang; Liu, Xiaowei; Liu, Zhi-Ren

    2012-01-01

    Summary Pyruvate kinase isoform M2 (PKM2) is a glycolysis enzyme catalyzing conversion of phosphoenolpyruvate (PEP) to pyruvate with transferring a phosphate from PEP to ADP. We report here that PKM2 localizes to the cell nucleus. The levels of nuclear PKM2 correlate with cell proliferation. PKM2 activates transcription of MEK5 by phosphorylating stat3 at Y705. In vitro phosphorylation assays show that PKM2 is a protein kinase using PEP as phosphate donor. ADP competes with the protein substrate binding, indicating that the substrate may bind to the ADP site of PKM2. Our experiments suggest that PKM2 dimer is an active protein kinase, while the tetramer is an active pyruvate kinase. Expression a PKM2 mutant that exists as a dimer promotes cell proliferation, indicating that protein kinase activity of PKM2 plays a role in promoting cell proliferation. Our study reveals an important link between metabolism alteration and gene expression during tumor transformation and progression. PMID:22306293

  13. SR protein kinases promote splicing of nonconsensus introns.

    PubMed

    Lipp, Jesse J; Marvin, Michael C; Shokat, Kevan M; Guthrie, Christine

    2015-08-01

    Phosphorylation of the spliceosome is essential for RNA splicing, yet how and to what extent kinase signaling affects splicing have not been defined on a genome-wide basis. Using a chemical genetic approach, we show in Schizosaccharomyces pombe that the SR protein kinase Dsk1 is required for efficient splicing of introns with suboptimal splice sites. Systematic substrate mapping in fission yeast and human cells revealed that SRPKs target evolutionarily conserved spliceosomal proteins, including the branchpoint-binding protein Bpb1 (SF1 in humans), by using an RXXSP consensus motif for substrate recognition. Phosphorylation of SF1 increases SF1 binding to introns with nonconsensus splice sites in vitro, and mutation of such sites to consensus relieves the requirement for Dsk1 and phosphorylated Bpb1 in vivo. Modulation of splicing efficiency through kinase signaling pathways may allow tuning of gene expression in response to environmental and developmental cues. PMID:26167880

  14. Phosphorylation of protein phosphatase inhibitor-1 by protein kinase C.

    PubMed

    Sahin, Bogachan; Shu, Hongjun; Fernandez, Joseph; El-Armouche, Ali; Molkentin, Jeffery D; Nairn, Angus C; Bibb, James A

    2006-08-25

    Inhibitor-1 becomes a potent inhibitor of protein phosphatase 1 when phosphorylated by cAMP-dependent protein kinase at Thr(35). Moreover, Ser(67) of inhibitor-1 serves as a substrate for cyclin-dependent kinase 5 in the brain. Here, we report that dephosphoinhibitor-1 but not phospho-Ser(67) inhibitor-1 was efficiently phosphorylated by protein kinase C at Ser(65) in vitro. In contrast, Ser(67) phosphorylation by cyclin-dependent kinase 5 was unaffected by phospho-Ser(65). Protein kinase C activation in striatal tissue resulted in the concomitant phosphorylation of inhibitor-1 at Ser(65) and Ser(67), but not Ser(65) alone. Selective pharmacological inhibition of protein phosphatase activity suggested that phospho-Ser(65) inhibitor-1 is dephosphorylated by protein phosphatase 1 in the striatum. In vitro studies confirmed these findings and suggested that phospho-Ser(67) protects phospho-Ser(65) inhibitor-1 from dephosphorylation by protein phosphatase 1 in vivo. Activation of group I metabotropic glutamate receptors resulted in the up-regulation of diphospho-Ser(65)/Ser(67) inhibitor-1 in this tissue. In contrast, the activation of N-methyl-d-aspartate-type ionotropic glutamate receptors opposed increases in striatal diphospho-Ser(65)/Ser(67) inhibitor-1 levels. Phosphomimetic mutation of Ser(65) and/or Ser(67) did not convert inhibitor-1 into a protein phosphatase 1 inhibitor. On the other hand, in vitro and in vivo studies suggested that diphospho-Ser(65)/Ser(67) inhibitor-1 is a poor substrate for cAMP-dependent protein kinase. These observations extend earlier studies regarding the function of phospho-Ser(67) and underscore the possibility that phosphorylation in this region of inhibitor-1 by multiple protein kinases may serve as an integrative signaling mechanism that governs the responsiveness of inhibitor-1 to cAMP-dependent protein kinase activation.

  15. Ternary structure reveals mechanism of a membrane diacylglycerol kinase

    DOE PAGESBeta

    Li, Dianfan; Stansfeld, Phillip J.; Sansom, Mark S. P.; Keogh, Aaron; Vogeley, Lutz; Howe, Nicole; Lyons, Joseph A.; Aragao, David; Fromme, Petra; Fromme, Raimund; et al

    2015-12-17

    Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternarymore » structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. As a result, the active site architecture shows clear evidence of having arisen by convergent evolution.« less

  16. Problem-Solving Test: "In Vitro" Protein Kinase A Reaction

    ERIC Educational Resources Information Center

    Szeberenyi, Jozsef

    2009-01-01

    Phosphorylation of proteins by protein kinases is an important mechanism in the regulation of protein activity. Among hundreds of protein kinases present in human cells, PKA, the first kinase discovered, belongs to the most important and best characterized group of these enzymes. The author presents an experiment that analyzes the "in vitro"…

  17. Non-ATP competitive protein kinase inhibitors.

    PubMed

    Garuti, L; Roberti, M; Bottegoni, G

    2010-01-01

    Protein kinases represent an attractive target in oncology drug discovery. Most of kinase inhibitors are ATP-competitive and are called type I inhibitors. The ATP-binding pocket is highly conserved among members of the kinase family and it is difficult to find selective agents. Moreover, the ATP-competitive inhibitors must compete with high intracellular ATP levels leading to a discrepancy between IC50s measured by biochemical versus cellular assays. The non-ATP competitive inhibitors, called type II and type III inhibitors, offer the possibility to overcome these problems. These inhibitors act by inducing a conformational shift in the target enzyme such that the kinase is no longer able to function. In the DFG-out form, the phenylalanine side chain moves to a new position. This movement creates a hydrophobic pocket available for occupation by the inhibitor. Some common features are present in these inhibitors. They contain a heterocyclic system that forms one or two hydrogen bonds with the kinase hinge residue. They also contain a hydrophobic moiety that occupies the pocket formed by the shift of phenylalanine from the DFG motif. Moreover, all the inhibitors bear a hydrogen bond donor-acceptor pair, usually urea or amide, that links the hinge-binding portion to the hydrophobic moiety and interacts with the allosteric site. Examples of non ATP-competitive inhibitors are available for various kinases. In this review small molecules capable of inducing the DFG-out conformation are reported, especially focusing on structural feature, SAR and biological properties.

  18. Kinase inhibitor profiling reveals unexpected opportunities to inhibit disease-associated mutant kinases

    PubMed Central

    Duong-Ly, Krisna C.; Devarajan, Karthik; Liang, Shuguang; Horiuchi, Kurumi Y.; Wang, Yuren; Ma, Haiching; Peterson, Jeffrey R.

    2016-01-01

    Summary Small-molecule kinase inhibitors have typically been designed to inhibit wild-type kinases rather than the mutant forms that frequently arise in diseases such as cancer. Mutations can have serious clinical implications by increasing kinase catalytic activity or conferring therapeutic resistance. To identify opportunities to repurpose inhibitors against disease-associated mutant kinases, we conducted a large-scale functional screen of 183 known kinase inhibitors against 76 recombinant, mutant kinases. The results revealed lead compounds with activity against clinically important mutant kinases including ALK, LRRK2, RET, and EGFR as well as unexpected opportunities for repurposing FDA-approved kinase inhibitors as leads for additional indications. Furthermore, using T674I PDGFRα as an example, we show how single-dose screening data can provide predictive structure-activity data to guide subsequent inhibitor optimization. This study provides a resource for the development of inhibitors against numerous disease-associated mutant kinases and illustrates the potential of unbiased profiling as an approach to compound-centric inhibitor development. PMID:26776524

  19. Protein kinase C controls activation of the DNA integrity checkpoint

    PubMed Central

    Soriano-Carot, María; Quilis, Inma; Bañó, M. Carmen; Igual, J. Carlos

    2014-01-01

    The protein kinase C (PKC) superfamily plays key regulatory roles in numerous cellular processes. Saccharomyces cerevisiae contains a single PKC, Pkc1, whose main function is cell wall integrity maintenance. In this work, we connect the Pkc1 protein to the maintenance of genome integrity in response to genotoxic stresses. Pkc1 and its kinase activity are necessary for the phosphorylation of checkpoint kinase Rad53, histone H2A and Xrs2 protein after deoxyribonucleic acid (DNA) damage, indicating that Pkc1 is required for activation of checkpoint kinases Mec1 and Tel1. Furthermore, Pkc1 electrophoretic mobility is delayed after inducing DNA damage, which reflects that Pkc1 is post-translationally modified. This modification is a phosphorylation event mediated by Tel1. The expression of different mammalian PKC isoforms at the endogenous level in yeast pkc1 mutant cells revealed that PKCδ is able to activate the DNA integrity checkpoint. Finally, downregulation of PKCδ activity in HeLa cells caused a defective activation of checkpoint kinase Chk2 when DNA damage was induced. Our results indicate that the control of the DNA integrity checkpoint by PKC is a mechanism conserved from yeast to humans. PMID:24792164

  20. Protein kinase A alterations in adrenocortical tumors.

    PubMed

    Espiard, S; Ragazzon, B; Bertherat, J

    2014-11-01

    Stimulation of the cAMP pathway by adrenocorticotropin (ACTH) is essential for adrenal cortex maintenance, glucocorticoid and adrenal androgens synthesis, and secretion. Various molecular and cellular alterations of the cAMP pathway have been observed in endocrine tumors. Protein kinase A (PKA) is a central key component of the cAMP pathway. Molecular alterations of PKA subunits have been observed in adrenocortical tumors. PKA molecular defects can be germline in hereditary disorders or somatic in sporadic tumors. Heterozygous germline inactivating mutations of the PKA regulatory subunit RIα gene (PRKAR1A) can be observed in patients with ACTH-independent Cushing's syndrome (CS) due to primary pigmented nodular adrenocortical disease (PPNAD). PRKAR1A is considered as a tumor suppressor gene. Interestingly, these mutations can also be observed as somatic alterations in sporadic cortisol-secreting adrenocortical adenomas. Germline gene duplication of the catalytic subunits Cα (PRKACA) has been observed in patients with PPNAD. Furthermore, exome sequencing revealed recently activating somatic mutations of PRKACA in about 40% of cortisol-secreting adrenocortical adenomas. In vitro and in vivo functional studies help in the progress to understand the mechanisms of adrenocortical tumors development due to PKA regulatory subunits alterations. All these alterations are observed in benign oversecreting tumors and are mimicking in some way cAMP pathway constitutive activation. On the long term, unraveling these alterations will open new strategies of pharmacological treatment targeting the cAMP pathway in adrenal tumors and cortisol-secretion disorders. PMID:25105543

  1. Mycobacterium tuberculosis Serine/Threonine Protein Kinases

    PubMed Central

    PRISIC, SLADJANA; HUSSON, ROBERT N.

    2014-01-01

    The Mycobacterium tuberculosis genome encodes 11 serine/threonine protein kinases (STPKs). A similar number of two-component systems are also present, indicating that these two signal transduction mechanisms are both important in the adaptation of this bacterial pathogen to its environment. The M. tuberculosis phosphoproteome includes hundreds of Ser- and Thr-phosphorylated proteins that participate in all aspects of M. tuberculosis biology, supporting a critical role for the STPKs in regulating M. tuberculosis physiology. Nine of the STPKs are receptor type kinases, with an extracytoplasmic sensor domain and an intracellular kinase domain, indicating that these kinases transduce external signals. Two other STPKs are cytoplasmic and have regulatory domains that sense changes within the cell. Structural analysis of some of the STPKs has led to advances in our understanding of the mechanisms by which these STPKs are activated and regulated. Functional analysis has provided insights into the effects of phosphorylation on the activity of several proteins, but for most phosphoproteins the role of phosphorylation in regulating function is unknown. Major future challenges include characterizing the functional effects of phosphorylation for this large number of phosphoproteins, identifying the cognate STPKs for these phosphoproteins, and determining the signals that the STPKs sense. Ultimately, combining these STPK-regulated processes into larger, integrated regulatory networks will provide deeper insight into M. tuberculosis adaptive mechanisms that contribute to tuberculosis pathogenesis. Finally, the STPKs offer attractive targets for inhibitor development that may lead to new therapies for drug-susceptible and drug-resistant tuberculosis. PMID:25429354

  2. Factors influencing the inhibition of protein kinases.

    PubMed

    Brockhoff, Marielle; Hau, Jean-Christophe; Fontana, Patrizia; Zimmermann, Catherine; Pover, Alain De; Erdmann, Dirk; Chène, Patrick

    2012-04-01

    The protein kinase field is a very active research area in the pharmaceutical industry and many activities are ongoing to identify inhibitors of these proteins. The design of new chemical entities with improved pharmacological properties requires a deeper understanding of the factors that modulate inhibitor-kinase interactions. In this report, we studied the effect of two of these factors--the magnesium ion cofactor and the protein substrate--on inhibitors of the type I insulin-like growth factor receptor. Our results show that the concentration of magnesium ion influences the potency of adenosine triphosphate (ATP) competitive inhibitors, suggesting an explanation for the observation that such compounds retain their nanomolar potency in cells despite the presence of millimolar levels of ATP. We also showed that the peptidic substrate affects the potency of these inhibitors in a different manner, suggesting that the influence of this substrate on compound potency should be taken into consideration during drug discovery.

  3. Protein Kinase D family kinases: roads start to segregate.

    PubMed

    Wille, Christoph; Seufferlein, Thomas; Eiseler, Tim

    2014-01-01

    Highly invasive pancreatic tumors are often recognized in late stages due to a lack of clear symptoms and pose major challenges for treatment and disease management. Broad-band Protein Kinase D (PKD) inhibitors have recently been proposed as additional treatment option for this disease. PKDs are implicated in the control of cancer cell motility, angiogenesis, proliferation and metastasis. In particular, PKD2 expression is elevated in pancreatic cancer, whereas PKD1 expression is comparably lower. In our recent study we report that both kinases control PDAC cell invasive properties in an isoform-specific, but opposing manner. PKD1 selectively mediates anti-migratory/anti-invasive features by preferential regulation of the actin-regulatory Cofilin-phosphatase Slingshot1L (SSH1L). PKD2, on the other hand enhances invasion and angiogenesis of PDAC cells in 3D-ECM cultures and chorioallantois tumor models by stimulating expression and secretion of matrix-metalloproteinase 7 and 9 (MMP7/9). MMP9 also enhances PKD2-mediated tumor angiogenesis releasing extracellular matrix-bound VEGF-A. We thus suggest high PKD2 expression and loss of PKD1 may be beneficial for tumor cells to enhance their matrix-invading abilities. In our recent study we demonstrate for the first time PKD1 and 2 isoform-selective effects on pancreatic cancer cell invasion, in-vitro and in-vivo, defining isoform-specific regulation of PKDs as a major future issue. PMID:24847910

  4. Crystal Structure of the Protein Kinase Domain of Yeast AMP-Activated Protein Kinase Snf1

    SciTech Connect

    Rudolph,M.; Amodeo, G.; Bai, Y.; Tong, L.

    2005-01-01

    AMP-activated protein kinase (AMPK) is a master metabolic regulator, and is an important target for drug development against diabetes, obesity, and other diseases. AMPK is a hetero-trimeric enzyme, with a catalytic ({alpha}) subunit, and two regulatory ({beta} and {gamma}) subunits. Here we report the crystal structure at 2.2 Angstrom resolution of the protein kinase domain (KD) of the catalytic subunit of yeast AMPK (commonly known as SNF1). The Snf1-KD structure shares strong similarity to other protein kinases, with a small N-terminal lobe and a large C-terminal lobe. Two negative surface patches in the structure may be important for the recognition of the substrates of this kinase.

  5. Identification of four plastid-localized protein kinases.

    PubMed

    Richter, Andreas S; Gartmann, Hans; Fechler, Mona; Rödiger, Anja; Baginsky, Sacha; Grimm, Bernhard

    2016-06-01

    In chloroplasts, protein phosphorylation regulates important processes, including metabolism, photosynthesis, gene expression, and signaling. Because the hitherto known plastid protein kinases represent only a fraction of existing kinases, we aimed at the identification of novel plastid-localized protein kinases that potentially phosphorylate enzymes of the tetrapyrrole biosynthesis (TBS) pathway. We screened publicly available databases for proteins annotated as putative protein kinase family proteins with predicted chloroplast localization. Additionally, we analyzed chloroplast fractions which were separated by sucrose density gradient centrifugation by mass spectrometry. We identified four new candidates for protein kinases, which were confirmed to be plastid localized by expression of GFP-fusion proteins in tobacco leaves. A phosphorylation assay with the purified kinases confirmed the protein kinase activity for two of them. PMID:27214872

  6. A-kinase Anchoring Protein 79/150 Recruits Protein Kinase C to Phosphorylate Roundabout Receptors.

    PubMed

    Samelson, Bret K; Gore, Bryan B; Whiting, Jennifer L; Nygren, Patrick J; Purkey, Alicia M; Colledge, Marcie; Langeberg, Lorene K; Dell'Acqua, Mark L; Zweifel, Larry S; Scott, John D

    2015-05-29

    Anchoring proteins direct protein kinases and phosphoprotein phosphatases toward selected substrates to control the efficacy, context, and duration of neuronal phosphorylation events. The A-kinase anchoring protein AKAP79/150 interacts with protein kinase A (PKA), protein kinase C (PKC), and protein phosphatase 2B (calcineurin) to modulate second messenger signaling events. In a mass spectrometry-based screen for additional AKAP79/150 binding partners, we have identified the Roundabout axonal guidance receptor Robo2 and its ligands Slit2 and Slit3. Biochemical and cellular approaches confirm that a linear sequence located in the cytoplasmic tail of Robo2 (residues 991-1070) interfaces directly with sites on the anchoring protein. Parallel studies show that AKAP79/150 interacts with the Robo3 receptor in a similar manner. Immunofluorescent staining detects overlapping expression patterns for murine AKAP150, Robo2, and Robo3 in a variety of brain regions, including hippocampal region CA1 and the islands of Calleja. In vitro kinase assays, peptide spot array mapping, and proximity ligation assay staining approaches establish that human AKAP79-anchored PKC selectively phosphorylates the Robo3.1 receptor subtype on serine 1330. These findings imply that anchored PKC locally modulates the phosphorylation status of Robo3.1 in brain regions governing learning and memory and reward.

  7. Characterization of three mitogen-activated protein kinases (MAPK) genes reveals involvement of ERK and JNK, not p38 in defense against bacterial infection in Yesso scallop Patinopecten yessoensis.

    PubMed

    Sun, Yan; Zhang, Lingling; Zhang, Meiwei; Li, Ruojiao; Li, Yangping; Hu, Xiaoli; Wang, Shi; Bao, Zhenmin

    2016-07-01

    Mitogen-activated protein kinases (MAPKs) are protein Ser/Thr kinases that play a vital role in innate immune responses by converting extracellular stimuli into a wide range of cellular responses. Although MAPKs have been extensively studied in various vertebrates and invertebrates, our current understanding of MAPK signaling cascade in scallop is in its infancy. In this study, three MAPK genes (PyERK, PyJNK, and Pyp38) were identified from Yesso scallop Patinopecten yessoensis. The open reading frame of PyERK, PyJNK, and Pyp38 was 1104, 1227, and 1104 bp, encoding 367, 408, and 367 amino acids, respectively. Conservation in some splicing sites was revealed across the three PyMAPKs, suggesting the common descent of MAPKs genes. The expression profiles of PyMAPKs over the course of ten different developmental stages showed that they had different expression patterns. In adult scallops, PyMAPKs were primarily expressed in muscles, hemocytes, gill, and mantle. To gain insights into their role in innate immunity, we investigated their expression profiles after infection with Gram-positive bacteria (Micrococcus luteus) and Gram-negative bacteria (Vibrio anguillarum). Significant difference in gene expression was only found in PyERK and PyJNK, but not Pyp38, suggesting Pyp38 may not participate in immune response to bacterial infection. Besides, PyERK and PyJNK exhibited more drastic change against the invasion of V. anguillarum than M. luteus, suggesting they could be more sensitive to Gram-negative bacteria than Gram-positive bacteria. This study provides valuable resource for elucidating the role of MAPK signal pathway in bivalve innate immune response. PMID:27155450

  8. Protein Kinase C δ: a Gatekeeper of Immune Homeostasis.

    PubMed

    Salzer, Elisabeth; Santos-Valente, Elisangela; Keller, Bärbel; Warnatz, Klaus; Boztug, Kaan

    2016-10-01

    Human autoimmune disorders present in various forms and are associated with a life-long burden of high morbidity and mortality. Many different circumstances lead to the loss of immune tolerance and often the origin is suspected to be multifactorial. Recently, patients with autosomal recessive mutations in PRKCD encoding protein kinase c delta (PKCδ) have been identified, representing a monogenic prototype for one of the most prominent forms of humoral systemic autoimmune diseases, systemic lupus erythematosus (SLE). PKCδ is a signaling kinase with multiple downstream target proteins and with functions in various signaling pathways. Interestingly, mouse models have indicated a special role of the ubiquitously expressed protein in the control of B-cell tolerance revealed by the severe autoimmunity in Prkcd (-/-) knockout mice as the major phenotype. As such, the study of PKCδ deficiency in humans has tremendous potential in enhancing our knowledge on the mechanisms of B-cell tolerance. PMID:27541826

  9. Protein Kinase C δ: a Gatekeeper of Immune Homeostasis.

    PubMed

    Salzer, Elisabeth; Santos-Valente, Elisangela; Keller, Bärbel; Warnatz, Klaus; Boztug, Kaan

    2016-10-01

    Human autoimmune disorders present in various forms and are associated with a life-long burden of high morbidity and mortality. Many different circumstances lead to the loss of immune tolerance and often the origin is suspected to be multifactorial. Recently, patients with autosomal recessive mutations in PRKCD encoding protein kinase c delta (PKCδ) have been identified, representing a monogenic prototype for one of the most prominent forms of humoral systemic autoimmune diseases, systemic lupus erythematosus (SLE). PKCδ is a signaling kinase with multiple downstream target proteins and with functions in various signaling pathways. Interestingly, mouse models have indicated a special role of the ubiquitously expressed protein in the control of B-cell tolerance revealed by the severe autoimmunity in Prkcd (-/-) knockout mice as the major phenotype. As such, the study of PKCδ deficiency in humans has tremendous potential in enhancing our knowledge on the mechanisms of B-cell tolerance.

  10. Pyrrolopyridine inhibitors of mitogen-activated protein kinase-activated protein kinase 2 (MK-2).

    PubMed

    Anderson, David R; Meyers, Marvin J; Vernier, William F; Mahoney, Matthew W; Kurumbail, Ravi G; Caspers, Nicole; Poda, Gennadiy I; Schindler, John F; Reitz, David B; Mourey, Robert J

    2007-05-31

    A new class of potent kinase inhibitors selective for mitogen-activated protein kinase-activated protein kinase 2 (MAPKAP-K2 or MK-2) for the treatment of rheumatoid arthritis has been prepared and evaluated. These inhibitors have IC50 values as low as 10 nM against the target and have good selectivity profiles against a number of kinases including CDK2, ERK, JNK, and p38. These MK-2 inhibitors have been shown to suppress TNFalpha production in U397 cells and to be efficacious in an acute inflammation model. The structure-activity relationships of this series, the selectivity for MK-2 and their activity in both in vitro and in vivo models are discussed. The observed selectivity is discussed with the aid of an MK-2/inhibitor crystal structure.

  11. Regulation of mitogen-activated protein kinases by a calcium/calmodulin-dependent protein kinase cascade.

    PubMed Central

    Enslen, H; Tokumitsu, H; Stork, P J; Davis, R J; Soderling, T R

    1996-01-01

    Membrane depolarization of NG108 cells gives rapid (< 5 min) activation of Ca2+/calmodulin-dependent protein kinase IV (CaM-KIV), as well as activation of c-Jun N-terminal kinase (JNK). To investigate whether the Ca2+-dependent activation of mitogen-activated protein kinases (ERK, JNK, and p38) might be mediated by the CaM kinase cascade, we have transfected PC12 cells, which lack CaM-KIV, with constitutively active mutants of CaM kinase kinase and/or CaM-KIV (CaM-KKc and CaM-KIVc, respectively). In the absence of depolarization, CaM-KKc transfection had no effect on Elk-dependent transcription of a luciferase reporter gene, whereas CaM-KIVc alone or in combination with CaM-KKc gave 7- to 10-fold and 60- to 80-fold stimulations, respectively, which were blocked by mitogen-activated protein (MAP) kinase phosphatase cotransfection. When epitope-tagged constructs of MAP kinases were co-transfected with CaM-KKc plus CaM-KIVc, the immunoprecipitated MAP kinases were activated 2-fold (ERK-2) and 7- to 10-fold (JNK-1 and p38). The JNK and p38 pathways were further investigated using specific c-Jun or ATF2-dependent transcriptional assays. We found that c-Jun/ATF2-dependent transcriptions were enhanced 7- to 10-fold by CaM-KIVc and 20- to 30-fold by CaM-KKc plus CaM-KIVc. In the case of the Jun-dependent transcription, this effect was not due to direct phosphorylation of c-Jun by activated CaM-KIV, since transcription was blocked by a dominant-negative JNK and by two MAP kinase phosphatases. Mutation of the phosphorylation site (Thr196) in CaM-KIV, which mediates its activation by CaM-KIV kinase, prevented activation of Elk-1, c-Jun, and ATF2 by the CaM kinase cascade. These results establish a new Ca2+-dependent mechanism for regulating MAP kinase pathways and resultant transcription. Images Fig. 1 Fig. 3 Fig. 4 PMID:8855261

  12. Transduction proteins of olfactory receptor cells: identification of guanine nucleotide binding proteins and protein kinase C

    SciTech Connect

    Anholt, R.R.H.; Mumby, S.M.; Stoffers, D.A.; Girard, P.R.; Kuo, J.F.; Snyder, S.H.

    1987-02-10

    The authors have analyzed guanine nucleotide binding proteins (G-proteins) in the olfactory epithelium of Rana catesbeiana using subunit-specific antisera. The olfactory epithelium contained the ..cap alpha.. subunits of three G-proteins, migrating on polyacrylamide gels in SDS with apparent molecular weights of 45,000, 42,000, and 40,000, corresponding to G/sub s/, G/sub i/, and G/sub o/, respectively. A single ..beta.. subunit with an apparent molecular weight of 36,000 was detected. An antiserum against the ..cap alpha.. subunit of retinal transducin failed to detect immunoreactive proteins in olfactory cilia detached from the epithelium. The olfactory cilia appeared to be enriched in immunoreactive G/sub s..cap alpha../ relative to G/sub ichemically bond/ and G/sub ochemically bond/ when compared to membranes prepared from the olfactory epithelium after detachment of the cilia. Bound antibody was detected by autoradiography after incubation with (/sup 125/I)protein. Immunohistochemical studies using an antiserum against the ..beta.. subunit of G-proteins revealed intense staining of the ciliary surface of the olfactory epithelium and of the axon bundles in the lamina propria. In contrast, an antiserum against a common sequence of the ..cap alpha.. subunits preferentially stained the cell membranes of the olfactory receptor cells and the acinar cells of Bowman's glands and the deep submucosal glands. In addition to G-proteins, they have identified protein kinase C in olfactory cilia via a protein kinase C specific antiserum and via phorbol ester binding. However, in contrast to the G-proteins, protein kinase C occurred also in cilia isolated from respiratory epithelium.

  13. Protein kinase A alterations in endocrine tumors.

    PubMed

    Yu, B; Ragazzon, B; Rizk-Rabin, M; Bertherat, J

    2012-09-01

    Various molecular and cellular alterations of the cyclic adenosine monophosphate (cAMP) pathway have been observed in endocrine tumors. Since protein kinase A (PKA) is a central key component of the cAMP pathway, studies of the alterations of PKA subunits in endocrine tumors reveal new aspects of the mechanisms of cAMP pathway alterations in human diseases. So far, most alterations have been observed for the regulatory subunits, mainly PRKAR1A and to a lower extent, PRKAR2B. One of the best examples of such alteration today is the multiple neoplasia syndrome Carney complex (CNC). The most common endocrine gland manifestations of CNC are pituitary GH-secreting adenomas, thyroid tumors, testicular tumors, and ACTH-independent Cushing's syndrome due to primary pigmented nodular adrenocortical disease (PPNAD). Heterozygous germline inactivating mutations of the PKA regulatory subunit RIα gene (PRKAR1A) are observed in about two-third of CNC patients, and also in patients with isolated PPNAD. PRKAR1A is considered as a tumor suppressor gene. Interestingly, these mutations can also be observed as somatic alterations in sporadic endocrine tumors. More than 120 different PRKAR1A mutations have been found today. Most of them lead to an unstable mutant mRNA, which will be degraded by nonsense mediated mRNA decay. In vitro and in vivo functional studies are in progress to understand the mechanisms of endocrine tumor development due to PKA regulatory subunits inactivation. PRKAR1A mutations stimulate in most models PKA activity, mimicking in some way cAMP pathway constitutive activation. Cross-talks with other signaling pathways summarized in this review have been described and might participate in endocrine tumorigenesis. PMID:22752956

  14. Contribution of casein kinase 2 and spleen tyrosine kinase to CFTR trafficking and protein kinase A-induced activity.

    PubMed

    Luz, Simão; Kongsuphol, Patthara; Mendes, Ana Isabel; Romeiras, Francisco; Sousa, Marisa; Schreiber, Rainer; Matos, Paulo; Jordan, Peter; Mehta, Anil; Amaral, Margarida D; Kunzelmann, Karl; Farinha, Carlos M

    2011-11-01

    Previously, the pleiotropic "master kinase" casein kinase 2 (CK2) was shown to interact with CFTR, the protein responsible for cystic fibrosis (CF). Moreover, CK2 inhibition abolished CFTR conductance in cell-attached membrane patches, native epithelial ducts, and Xenopus oocytes. CFTR possesses two CK2 phosphorylation sites (S422 and T1471), with unclear impact on its processing and trafficking. Here, we investigated the effects of mutating these CK2 sites on CFTR abundance, maturation, and degradation coupled to effects on ion channel activity and surface expression. We report that CK2 inhibition significantly decreased processing of wild-type (wt) CFTR, with no effect on F508del CFTR. Eliminating phosphorylation at S422 and T1471 revealed antagonistic roles in CFTR trafficking: S422 activation versus T1471 inhibition, as evidenced by a severe trafficking defect for the T1471D mutant. Notably, mutation of Y512, a consensus sequence for the spleen tyrosine kinase (SYK) possibly acting in a CK2 context adjacent to the common CF-causing defect F508del, had a strong effect on both maturation and CFTR currents, allowing the identification of this kinase as a novel regulator of CFTR. These results reinforce the importance of CK2 and the S422 and T1471 residues for regulation of CFTR and uncover a novel regulation of CFTR by SYK, a recognized controller of inflammation.

  15. Soybean nodule autoregulation receptor kinase phosphorylates two kinase-associated protein phosphatases in vitro.

    PubMed

    Miyahara, Akira; Hirani, Tripty A; Oakes, Marie; Kereszt, Attila; Kobe, Bostjan; Djordjevic, Michael A; Gresshoff, Peter M

    2008-09-12

    The NARK (nodule autoregulation receptor kinase) gene, a negative regulator of cell proliferation in nodule primordia in several legumes, encodes a receptor kinase that consists of an extracellular leucine-rich repeat and an intracellular serine/threonine protein kinase domain. The putative catalytic domain of NARK was expressed and purified as a maltose-binding or a glutathione S-transferase fusion protein in Escherichia coli. The recombinant NARK proteins showed autophosphorylation activity in vitro. Several regions of the NARK kinase domain were shown by mass spectrometry to possess phosphoresidues. The kinase-inactive protein K724E failed to autophosphorylate, as did three other proteins corresponding to phenotypically detected mutants defective in whole plant autoregulation of nodulation. A wild-type NARK fusion protein transphosphorylated a kinase-inactive mutant NARK fusion protein, suggesting that it is capable of intermolecular autophosphorylation in vitro. In addition, Ser-861 and Thr-963 in the NARK kinase catalytic domain were identified as phosphorylation sites through site-directed mutagenesis. The genes coding for the kinase-associated protein phosphatases KAPP1 and KAPP2, two putative interacting components of NARK, were isolated. NARK kinase domain phosphorylated recombinant KAPP proteins in vitro. Autophosphorylated NARK kinase domain was, in turn, dephosphorylated by both KAPP1 and KAPP2. Our results suggest a model for signal transduction involving NARK in the control of nodule development.

  16. Modulation of the chromatin phosphoproteome by the Haspin protein kinase.

    PubMed

    Maiolica, Alessio; de Medina-Redondo, Maria; Schoof, Erwin M; Chaikuad, Apirat; Villa, Fabrizio; Gatti, Marco; Jeganathan, Siva; Lou, Hua Jane; Novy, Karel; Hauri, Simon; Toprak, Umut H; Herzog, Franz; Meraldi, Patrick; Penengo, Lorenza; Turk, Benjamin E; Knapp, Stefan; Linding, Rune; Aebersold, Ruedi

    2014-07-01

    Recent discoveries have highlighted the importance of Haspin kinase activity for the correct positioning of the kinase Aurora B at the centromere. Haspin phosphorylates Thr(3) of the histone H3 (H3), which provides a signal for Aurora B to localize to the centromere of mitotic chromosomes. To date, histone H3 is the only confirmed Haspin substrate. We used a combination of biochemical, pharmacological, and mass spectrometric approaches to study the consequences of Haspin inhibition in mitotic cells. We quantified 3964 phosphorylation sites on chromatin-associated proteins and identified a Haspin protein-protein interaction network. We determined the Haspin consensus motif and the co-crystal structure of the kinase with the histone H3 tail. The structure revealed a unique bent substrate binding mode positioning the histone H3 residues Arg(2) and Lys(4) adjacent to the Haspin phosphorylated threonine into acidic binding pockets. This unique conformation of the kinase-substrate complex explains the reported modulation of Haspin activity by methylation of Lys(4) of the histone H3. In addition, the identification of the structural basis of substrate recognition and the amino acid sequence preferences of Haspin aided the identification of novel candidate Haspin substrates. In particular, we validated the phosphorylation of Ser(137) of the histone variant macroH2A as a target of Haspin kinase activity. MacroH2A Ser(137) resides in a basic stretch of about 40 amino acids that is required to stabilize extranucleosomal DNA, suggesting that phosphorylation of Ser(137) might regulate the interactions of macroH2A and DNA. Overall, our data suggest that Haspin activity affects the phosphorylation state of proteins involved in gene expression regulation and splicing.

  17. Src-homology 3 domain of protein kinase p59fyn mediates binding to phosphatidylinositol 3-kinase in T cells.

    PubMed Central

    Prasad, K V; Janssen, O; Kapeller, R; Raab, M; Cantley, L C; Rudd, C E

    1993-01-01

    The Src-related tyrosine kinase p59fyn(T) plays an important role in the generation of intracellular signals from the T-cell antigen receptor TCR zeta/CD3 complex. A key question concerns the nature and the binding sites of downstream components that interact with this Src-related kinase. p59fyn(T) contains Src-homology 2 and 3 domains (SH2 and SH3) with a capacity to bind to intracellular proteins. One potential downstream target is phosphatidylinositol 3-kinase (PI 3-kinase). In this study, we demonstrate that anti-CD3 and anti-Fyn immunoprecipitates possess PI 3-kinase activity as assessed by TLC and HPLC. Both free and receptor-bound p59fyn(T) were found to bind to the lipid kinase. Further, our results indicate that Src-related kinases have developed a novel mechanism to interact with PI 3-kinase. Precipitation using GST fusion proteins containing Fyn SH2, SH3, and SH2/SH3 domains revealed that PI 3-kinase bound principally to the SH3 domain of Fyn. Fyn SH3 bound directly to the p85 subunit of PI 3-kinase as expressed in a baculoviral system. Anti-CD3 crosslinking induced an increase in the detection of Fyn SH3-associated PI 3-kinase activity. Thus PI 3-kinase is a target of SH3 domains and is likely to play a major role in the signals derived from the TCR zeta/CD3-p59fyn complex. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8394019

  18. Monoclonal antibodies against type II rat brain protein kinase

    SciTech Connect

    Nakabayashi, C.H.; Huang, K.P.

    1987-05-01

    Three monoclonal antibodies (8/1, 10/10, and 25/3) against rat brain type II protein kinase C (PKC) were used to carry out the immunochemical characterization of this kinase. These antibodies immunoprecipitated the type II PKC in a dose-dependent manner but did neither to type I nor type III isozyme. Purified type II PKC has a molecular weight of 82,000 and consists of heterogeneous isoelectric point species, all of which are cross reactive with these antibodies. Immunoblot analysis of the tryptic fragments from PKC revealed that all three antibodies recognized the 33-38-KDa fragments, the phospholipid/phorbol ester-binding domain, but not the 45-48-KDa fragments, the kinase catalytic domain. The immune complexes of the kinase and the antibodies retained the kinase activity which was dependent on Ca/sup 2 +/ and phosphatidylserine (PS) and further activated by diacylglycerol. With antibody 8/1, the apparent Km values of the kinase for Ca/sup 2 +/ and PS were not influenced. The initial rate and final extent of autophosphorylation were reduced. The concentration of PS required for half-maximal (/sup 3/H)phorbol 12,13-dibutyrate (PDBu) binding was increased and the total PDBu binding was reduced. In the presence of optimum concentrations of Ca/sup 2 +/ and PS, the Kd of PDBu was unaffected by the antibody but the total binding was reduced. These results demonstrate that the PS/PDBu-binding domain contains the major epitope for the antibodies and the antibody mainly influences the PS/PDBu binding to the kinase.

  19. Photoinduced structural changes to protein kinase A

    NASA Astrophysics Data System (ADS)

    Rozinek, Sarah C.; Thomas, Robert J.; Brancaleon, Lorenzo

    2014-03-01

    The importance of porphyrins in organisms is underscored by the ubiquitous biological and biochemical functions that are mediated by these compounds and by their potential biomedical and biotechnological applications. Protoporphyrin IX (PPIX) is the precursor to heme and has biomedical applications such as its use as a photosensitizer in phototherapy and photodetection of cancer. Among other applications, our group has demonstrated that low-irradiance exposure to laser irradiation of PPIX, Fe-PPIX, or meso-tetrakis (4-sulfonatophenyl) porphyrin (TSPP) non-covalently docked to a protein causes conformational changes in the polypeptide. Such approach can have remarkable consequences in the study of protein structure/function relationship and can be used to prompt non-native protein properties. Therefore we have investigated protein kinase A (PKA), a more relevant protein model towards the photo-treatment of cancer. PKA's enzymatic functions are regulated by the presence of cyclic adenosine monophosphate for intracellular signal transduction involved in, among other things, stimulation of transcription, tumorigenesis in Carney complex and migration of breast carcinoma cells. Since phosphorylation is a necessary step in some cancers and inflammatory diseases, inhibiting the protein kinase, and therefore phosphorylation, may serve to treat these diseases. Changes in absorption, steady-state fluorescence, and fluorescence lifetime indicate: 1) both TSPP and PPIX non-covalently bind to PKA where they maintain photoreactivity; 2) absorptive photoproduct formation occurs only when PKA is bound to TSPP and irradiated; and 3) PKA undergoes secondary structural changes after irradiation with either porphyrin bound. These photoinduced changes could affect the protein's enzymatic and signaling capabilities.

  20. 3pK, a new mitogen-activated protein kinase-activated protein kinase located in the small cell lung cancer tumor suppressor gene region.

    PubMed Central

    Sithanandam, G; Latif, F; Duh, F M; Bernal, R; Smola, U; Li, H; Kuzmin, I; Wixler, V; Geil, L; Shrestha, S

    1996-01-01

    NotI linking clones, localized to the human chromosome 3p21.3 region and homozygously deleted in small cell lung cancer cell lines NCI-H740 and NCI-H1450, were used to search for a putative tumor suppressor gene(s). One of these clones, NL1G210, detected a 2.5-kb mRNA in all examined human tissues, expression being especially high in the heart and skeletal muscle. Two overlapping cDNA clones containing the entire open reading frame were isolated from a human heart cDNA library and fully characterized. Computer analysis and a search of the GenBank database to reveal high sequence identity of the product of this gene to serine-threonine kinases, especially to mitogen-activated protein kinase-activated protein kinase 2, a recently described substrate of mitogen-activated kinases. Sequence identitiy was 72% at the nucleotide level and 75% at the amino acid level, strongly suggesting that this protein is a serine-threonine kinase. Here we demonstrate that the new gene, referred to as 3pK (for chromosome 3p kinase), in fact encodes a mitogen-activated protein kinase-regulated protein serine-threonine kinase with a novel substrate specificity. PMID:8622688

  1. Cross-phosphorylation of bacterial serine/threonine and tyrosine protein kinases on key regulatory residues

    PubMed Central

    Shi, Lei; Pigeonneau, Nathalie; Ravikumar, Vaishnavi; Dobrinic, Paula; Macek, Boris; Franjevic, Damjan; Noirot-Gros, Marie-Francoise; Mijakovic, Ivan

    2014-01-01

    Bacteria possess protein serine/threonine and tyrosine kinases which resemble eukaryal kinases in their capacity to phosphorylate multiple substrates. We hypothesized that the analogy might extend further, and bacterial kinases may also undergo mutual phosphorylation and activation, which is currently considered as a hallmark of eukaryal kinase networks. In order to test this hypothesis, we explored the capacity of all members of four different classes of serine/threonine and tyrosine kinases present in the firmicute model organism Bacillus subtilis to phosphorylate each other in vitro and interact with each other in vivo. The interactomics data suggested a high degree of connectivity among all types of kinases, while phosphorylation assays revealed equally wide-spread cross-phosphorylation events. Our findings suggest that the Hanks-type kinases PrkC, PrkD, and YabT exhibit the highest capacity to phosphorylate other B. subtilis kinases, while the BY-kinase PtkA and the two-component-like kinases RsbW and SpoIIAB show the highest propensity to be phosphorylated by other kinases. Analysis of phosphorylated residues on several selected recipient kinases suggests that most cross-phosphorylation events concern key regulatory residues. Therefore, cross-phosphorylation events are very likely to influence the capacity of recipient kinases to phosphorylate substrates downstream in the signal transduction cascade. We therefore conclude that bacterial serine/threonine and tyrosine kinases probably engage in a network-type behavior previously described only in eukaryal cells. PMID:25278935

  2. Profiling Protein Kinases and Other ATP Binding Proteins in Arabidopsis Using Acyl-ATP Probes*

    PubMed Central

    Villamor, Joji Grace; Kaschani, Farnusch; Colby, Tom; Oeljeklaus, Julian; Zhao, David; Kaiser, Markus; Patricelli, Matthew P.; van der Hoorn, Renier A. L.

    2013-01-01

    Many protein activities are driven by ATP binding and hydrolysis. Here, we explore the ATP binding proteome of the model plant Arabidopsis thaliana using acyl-ATP (AcATP)1 probes. These probes target ATP binding sites and covalently label lysine residues in the ATP binding pocket. Gel-based profiling using biotinylated AcATP showed that labeling is dependent on pH and divalent ions and can be competed by nucleotides. The vast majority of these AcATP-labeled proteins are known ATP binding proteins. Our search for labeled peptides upon in-gel digest led to the discovery that the biotin moiety of the labeled peptides is oxidized. The in-gel analysis displayed kinase domains of two receptor-like kinases (RLKs) at a lower than expected molecular weight, indicating that these RLKs lost the extracellular domain, possibly as a result of receptor shedding. Analysis of modified peptides using a gel-free platform identified 242 different labeling sites for AcATP in the Arabidopsis proteome. Examination of each individual labeling site revealed a preference of labeling in ATP binding pockets for a broad diversity of ATP binding proteins. Of these, 24 labeled peptides were from a diverse range of protein kinases, including RLKs, mitogen-activated protein kinases, and calcium-dependent kinases. A significant portion of the labeling sites could not be assigned to known nucleotide binding sites. However, the fact that labeling could be competed with ATP indicates that these labeling sites might represent previously uncharacterized nucleotide binding sites. A plot of spectral counts against expression levels illustrates the high specificity of AcATP probes for protein kinases and known ATP binding proteins. This work introduces profiling of ATP binding activities of a large diversity of proteins in plant proteomes. The data have been deposited in ProteomeXchange with the identifier PXD000188. PMID:23722185

  3. Protein kinase C directly phosphorylates the insulin receptor in vitro and reduces its protein-tyrosine kinase activity.

    PubMed Central

    Bollag, G E; Roth, R A; Beaudoin, J; Mochly-Rosen, D; Koshland, D E

    1986-01-01

    The beta subunit of purified insulin receptor is phosphorylated on a serine residue by purified preparations of protein kinase C (ATP: protein phosphotransferase, EC 2.7.1.37). This phosphorylation is inhibited by antibodies to protein kinase C and stimulated by phospholipids, diacylglycerol, and Ca2+. The phosphorylation of the receptor by protein kinase C does not affect its insulin-binding activity but does inhibit by 65% the receptor's intrinsic tyrosine-specific protein kinase activity (ATP: protein-tyrosine O-phosphotransferase, EC 2.7.1.112). These results indicate that activators of protein kinase C, such as phorbol esters, desensitize cells to insulin by direct protein kinase C action on the insulin receptor. Images PMID:3526339

  4. Protein Kinase A Opposes the Phosphorylation-dependent Recruitment of Glycogen Synthase Kinase 3β to A-kinase Anchoring Protein 220.

    PubMed

    Whiting, Jennifer L; Nygren, Patrick J; Tunquist, Brian J; Langeberg, Lorene K; Seternes, Ole-Morten; Scott, John D

    2015-08-01

    The proximity of an enzyme to its substrate can influence rate and magnitude of catalysis. A-kinase anchoring protein 220 (AKAP220) is a multivalent anchoring protein that can sequester a variety of signal transduction enzymes. These include protein kinase A (PKA) and glycogen synthase kinase 3β (GSK3β). Using a combination of molecular and cellular approaches we show that GSK3β phosphorylation of Thr-1132 on AKAP220 initiates recruitment of this kinase into the enzyme scaffold. We also find that AKAP220 anchors GSK3β and its substrate β-catenin in membrane ruffles. Interestingly, GSK3β can be released from the multienzyme complex in response to PKA phosphorylation on serine 9, which suppresses GSK3β activity. The signaling scaffold may enhance this regulatory mechanism, as AKAP220 has the capacity to anchor two PKA holoenzymes. Site 1 on AKAP220 (residues 610-623) preferentially interacts with RII, whereas site 2 (residues 1633-1646) exhibits a dual specificity for RI and RII. In vitro affinity measurements revealed that site 2 on AKAP220 binds RII with ∼10-fold higher affinity than site 1. Occupancy of both R subunit binding sites on AKAP220 could provide a mechanism to amplify local cAMP responses and enable cross-talk between PKA and GSK3β.

  5. Calcium-Dependent Protein Kinase Genes in Corn Roots

    NASA Technical Reports Server (NTRS)

    Takezawa, D.; Patil, S.; Bhatia, A.; Poovaiah, B. W.

    1996-01-01

    Two cDNAs encoding Ca-2(+) - Dependent Protein Kinases (CDPKs), Corn Root Protein Kinase 1 and 2 (CRPK 1, CRPK 2) were isolated from the root tip library of corn (Zea mays L., cv. Merit) and their nucleotide sequences were determined. Deduced amino acid sequences of both the clones have features characteristic of plant CDPKS, including all 11 conserved serine/threonine kinase subdomains, a junction domain and a calmodulin-like domain with four Ca-2(+), -binding sites. Northern analysis revealed that CRPKI mRNA is preferentially expressed in roots, especially in the root tip; whereas, the expression of CRPK2 mRNA was very low in all the tissues tested. In situ hybridization experiments revealed that CRPKI mRNA is highly expressed in the root apex, as compared to other parts of the root. Partially purified CDPK from the root tip phosphorylates syntide-2, a common peptide substrate for plant CDPKs, and the phosphorylation was stimulated 7-fold by the addition of Ca-2(+). Our results show that two CDPK isoforms are expressed in corn roots and they may be involved in the Ca-2(+)-dependent signal transduction process.

  6. The Roles of Protein Kinases in Learning and Memory

    ERIC Educational Resources Information Center

    Giese, Karl Peter; Mizuno, Keiko

    2013-01-01

    In the adult mammalian brain, more than 250 protein kinases are expressed, but only a few of these kinases are currently known to enable learning and memory. Based on this information it appears that learning and memory-related kinases either impact on synaptic transmission by altering ion channel properties or ion channel density, or regulate…

  7. Chemoproteomic characterization of protein kinase inhibitors using immobilized ATP.

    PubMed

    Duncan, James S; Haystead, Timothy A J; Litchfield, David W

    2012-01-01

    Protein kinase inhibitors have emerged as indispensable tools for the elucidation of the biological functions of specific signal transduction pathways and as promising candidates for molecular-targeted therapy. However, because many protein kinase inhibitors are ATP-competitive inhibitors targeting the catalytic site of specific protein kinases, the large number of protein kinases that are encoded within eukaryotic genomes and the existence of many other cellular proteins that bind ATP result in the prospect of off-target effects for many of these compounds. Many of the potential off-target effects remain unrecognized because protein kinase inhibitors are often developed and tested primarily on the basis of in vitro assays using purified components. To overcome this limitation, we describe a systematic approach to characterize ATP-competitive protein kinase inhibitors employing ATP-sepharose to capture the purine-binding proteome from cell extracts. Protein kinase inhibitors can be used in competition experiments to prevent binding of specific cellular proteins to ATP-sepharose or to elute bound proteins from ATP-sepharose. Collectively, these strategies can enable validation of interactions between a specific protein kinase and an inhibitor in complex mixtures and can yield the identification of inhibitor targets.

  8. Mitogen-activated Protein Kinase Kinase Kinase 1 Protects against Nickel-induced Acute Lung Injury

    PubMed Central

    Mongan, Maureen; Tan, Zongqing; Chen, Liang; Peng, Zhimin; Dietsch, Maggie; Su, Bing; Leikauf, George; Xia, Ying

    2008-01-01

    Nickel compounds are environmental and occupational hazards that pose serious health problems and are causative factors of acute lung injury. The c-jun N-terminal kinases (JNKs) are regulated through a mitogen-activated protein (MAP) 3 kinase-MAP2 kinase cascade and have been implicated in nickel toxicity. In this study, we used genetically modified cells and mice to investigate the involvement of two upstream MAP3Ks, MAP3K1 and 2, in nickel-induced JNK activation and acute lung injury. In mouse embryonic fibroblasts, levels of JNK activation and cytotoxicity induced by nickel were similar in the Map3k2-null and wild-type cells but were much lower in the Map3k1/Map3k2 double-null cells. Conversely, the levels of JNK activation and cytotoxicity were unexpectedly much higher in the Map3k1-null cells. In adult mouse tissue, MAP3K1 was widely distributed but was abundantly expressed in the bronchiole epithelium of the lung. Accordingly, MAP3K1 ablation in mice resulted in severe nickel-induced acute lung injury and reduced survival. Based on these findings, we propose a role for MAP3K1 in reducing JNK activation and protecting the mice from nickel-induced acute lung injury. PMID:18467339

  9. Suppression of death-associated protein kinase 2 by interaction with 14-3-3 proteins.

    PubMed

    Yuasa, Keizo; Ota, Reina; Matsuda, Shinya; Isshiki, Kinuka; Inoue, Masahiro; Tsuji, Akihiko

    2015-08-14

    Death-associated protein kinase 2 (DAPK2), a Ca(2+)/calmodulin-regulated serine/threonine kinase, induces apoptosis. However, the signaling mechanisms involved in this process are unknown. Using a proteomic approach, we identified 14-3-3 proteins as novel DAPK2-interacting proteins. The 14-3-3 family has the ability to bind to phosphorylated proteins via recognition of three conserved amino acid motifs (mode 1-3 motifs), and DAPK2 contains the mode 3 motif ((pS/pT)X1-2-COOH). The interaction of 14-3-3 proteins with DAPK2 was dependent on the phosphorylation of Thr(369), and effectively suppressed DAPK2 kinase activity and DAPK2-induced apoptosis. Furthermore, we revealed that the 14-3-3 binding site Thr(369) of DAPK2 was phosphorylated by the survival kinase Akt. Our findings suggest that DAPK2-induced apoptosis is negatively regulated by Akt and 14-3-3 proteins.

  10. CDPKs are dual-specificity protein kinases and tyrosine autophosphorylation attenuates kinase activity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calcium-dependent protein kinases (CDPKs or CPKs) are classified as serine/threonine protein kinases but we made the surprising observation that soybean CDPK' and several Arabidopsis isoforms (AtCPK4 and AtCPK34) could also autophosphorylate on tyrosine residues. In studies with His6-GmCDPK', we ide...

  11. Regulation of hippocampus-dependent memory by cyclic AMP-dependent protein kinase

    PubMed Central

    Abel, Ted; Nguyen, Peter V.

    2010-01-01

    The hippocampus is crucial for the consolidation of new declarative long-term memories. Genetic and behavioral experimentation have revealed that several protein kinases are critical for the formation of hippocampus-dependent long-term memories. Cyclic-AMP dependent protein kinase (PKA) is a serine–threonine kinase that has been strongly implicated in the expression of specific forms of hippocampus-dependent memory. We review evidence that PKA is required for hippocampus-dependent memory in mammals, and we highlight some of the proteins that have been implicated as targets of PKA. Future directions and open questions regarding the role of PKA in memory storage are also described. PMID:18394470

  12. Casein kinase 1 proteomics reveal prohibitin 2 function in molecular clock.

    PubMed

    Kategaya, Lorna S; Hilliard, Aisha; Zhang, Louying; Asara, John M; Ptáček, Louis J; Fu, Ying-Hui

    2012-01-01

    Throughout the day, clock proteins synchronize changes in animal physiology (e.g., wakefulness and appetite) with external cues (e.g., daylight and food). In vertebrates, both casein kinase 1 delta and epsilon (CK1δ and CK1ε) regulate these circadian changes by phosphorylating other core clock proteins. In addition, CK1 can regulate circadian-dependent transcription in a non-catalytic manner, however, the mechanism is unknown. Furthermore, the extent of functional redundancy between these closely related kinases is debated. To further advance knowledge about CK1δ and CK1ε mechanisms of action in the biological clock, we first carried out proteomic analysis of both kinases in human cells. Next, we tested interesting candidates in a cell-based circadian readout which resulted in the discovery of PROHIBITIN 2 (PHB2) as a modulator of period length. Decreasing the expression of PHB2 increases circadian-driven transcription, thus revealing PHB2 acts as an inhibitor in the molecular clock. While stable binding of PHB2 to either kinase was not detected, knocking down CK1ε expression increases PHB2 protein levels and, unexpectedly, knocking down CK1δ decreases PHB2 transcript levels. Thus, isolating CK1 protein complexes led to the identification of PHB2 as an inhibitor of circadian transcription. Furthermore, we show that CK1δ and CK1ε differentially regulate the expression of PHB2.

  13. Genome-wide identification and analysis of expression profiles of maize mitogen-activated protein kinase kinase kinase.

    PubMed

    Kong, Xiangpei; Lv, Wei; Zhang, Dan; Jiang, Shanshan; Zhang, Shizhong; Li, Dequan

    2013-01-01

    Mitogen-activated protein kinase (MAPK) cascades are highly conserved signal transduction model in animals, yeast and plants. Plant MAPK cascades have been implicated in development and stress responses. Although MAPKKKs have been investigated in several plant species including Arabidopsis and rice, no systematic analysis has been conducted in maize. In this study, we performed a bioinformatics analysis of the entire maize genome and identified 74 MAPKKK genes. Phylogenetic analyses of MAPKKKs from maize, rice and Arabidopsis have classified them into three subgroups, which included Raf, ZIK and MEKK. Evolutionary relationships within subfamilies were also supported by exon-intron organizations and the conserved protein motifs. Further expression analysis of the MAPKKKs in microarray databases revealed that MAPKKKs were involved in important signaling pathways in maize different organs and developmental stages. Our genomics analysis of maize MAPKKK genes provides important information for evolutionary and functional characterization of this family in maize.

  14. Identification of intracellular receptor proteins for activated protein kinase C.

    PubMed Central

    Mochly-Rosen, D; Khaner, H; Lopez, J

    1991-01-01

    Protein kinase C (PKC) translocates from the cytosol to the particulate fraction on activation. This activation-induced translocation of PKC is thought to reflect PKC binding to the membrane lipids. However, immunological and biochemical data suggest that PKC may bind to proteins in the cytoskeletal elements in the particulate fraction and in the nuclei. Here we describe evidence for the presence of intracellular receptor proteins that bind activated PKC. Several proteins from the detergent-insoluble material of the particulate fraction bound PKC in the presence of phosphatidylserine and calcium; binding was further increased with the addition of diacylglycerol. Binding of PKC to two of these proteins was concentration-dependent, saturable, and specific, suggesting that these binding proteins are receptors for activated C-kinase, termed here "RACKs." PKC binds to RACKs via a site on PKC distinct from the substrate binding site. We suggest that binding to RACKs may play a role in activation-induced translocation of PKC. Images PMID:1850844

  15. A sensitive flow cytometry-based nucleotide excision repair assay unexpectedly reveals that mitogen-activated protein kinase signaling does not regulate the removal of UV-induced DNA damage in human cells.

    PubMed

    Rouget, Raphael; Auclair, Yannick; Loignon, Martin; Affar, El Bachir; Drobetsky, Elliot A

    2008-02-29

    In response to diverse genotoxic stimuli (e.g. UV and cisplatin), the mitogen-activated protein kinases ERK1/2, JNK1/2, and p38alpha/beta become rapidly phosphorylated and in turn activate multiple downstream effectors that modulate apoptosis and/or growth arrest. Furthermore, previous lines of evidence have strongly suggested that ERK1/2 and JNK1/2 participate in global-genomic nucleotide excision repair, a critical antineoplastic pathway that removes helix-distorting DNA adducts induced by a variety of mutagenic agents, including UV. To rigorously evaluate the potential role of mitogen-activated protein kinases in global-genomic nucleotide excision repair, various human cell strains (primary skin fibroblasts, primary lung fibroblasts, and HCT116 colon carcinoma cells) were treated with highly specific chemical inhibitors, which, following UV exposure, (i) abrogated the capacities of ERK1/2, JNK1/2, or p38alpha/beta to phosphorylate specific downstream effectors and (ii) characteristically modulated cellular proliferation, clonogenic survival, and/or apoptosis. A highly sensitive flow cytometry-based nucleotide excision repair assay recently optimized and validated in our laboratory was then employed to directly demonstrate that the kinetics of UV DNA photoadduct repair are highly similar in mock-treated versus mitogen-activated protein kinase inhibitor-treated cells. These data on primary and tumor cells treated with pharmacological inhibitors were fully corroborated by repair studies using (i) short hairpin RNA-mediated knockdown of ERK1/2 or JNK1/2 in human U2OS osteosarcoma cells and (ii) expression of a dominant negative p38alpha mutant in human primary lung fibroblasts. Our results provide solid evidence for the first time, in disaccord with a burgeoning perception, that mitogen-activated protein kinase signaling does not influence the efficiency of human global-genomic nucleotide excision repair.

  16. The pharmacogenomics of drug resistance to protein kinase inhibitors.

    PubMed

    Gillis, Nancy K; McLeod, Howard L

    2016-09-01

    Dysregulation of growth factor cell signaling is a major driver of most human cancers. This has led to development of numerous drugs targeting protein kinases, with demonstrated efficacy in the treatment of a wide spectrum of cancers. Despite their high initial response rates and survival benefits, the majority of patients eventually develop resistance to these targeted therapies. This review article discusses examples of established mechanisms of drug resistance to anticancer therapies, including drug target mutations or gene amplifications, emergence of alternate signaling pathways, and pharmacokinetic variation. This reveals a role for pharmacogenomic analysis to identify and monitor for resistance, with possible therapeutic strategies to combat chemoresistance. PMID:27620953

  17. The pharmacogenomics of drug resistance to protein kinase inhibitors.

    PubMed

    Gillis, Nancy K; McLeod, Howard L

    2016-09-01

    Dysregulation of growth factor cell signaling is a major driver of most human cancers. This has led to development of numerous drugs targeting protein kinases, with demonstrated efficacy in the treatment of a wide spectrum of cancers. Despite their high initial response rates and survival benefits, the majority of patients eventually develop resistance to these targeted therapies. This review article discusses examples of established mechanisms of drug resistance to anticancer therapies, including drug target mutations or gene amplifications, emergence of alternate signaling pathways, and pharmacokinetic variation. This reveals a role for pharmacogenomic analysis to identify and monitor for resistance, with possible therapeutic strategies to combat chemoresistance.

  18. Recent advances in designing substrate-competitive protein kinase inhibitors.

    PubMed

    Han, Ki-Cheol; Kim, So Yeon; Yang, Eun Gyeong

    2012-01-01

    Protein kinases play central roles in cellular signaling pathways and their abnormal phosphorylation activity is inseparably linked with various human diseases. Therefore, modulation of kinase activity using potent inhibitors is an attractive strategy for the treatment of human disease. While most protein kinase inhibitors in clinical development are mainly targeted to the highly conserved ATP-binding sites and thus likely promiscuously inhibit multiple kinases including kinases unrelated to diseases, protein substrate-competitive inhibitors are more selective and expected to be promising therapeutic agents. Most substrate-competitive inhibitors mimic peptides derived from substrate proteins, or from inhibitory domains within kinases or inhibitor proteins. In addition, bisubstrate inhibitors are generated by conjugating substrate-competitive peptide inhibitors to ATP-competitive inhibitors to improve affinity and selectivity. Although structural information on protein kinases provides invaluable guidance in designing substrate-competitive inhibitors, other strategies including bioinformatics, computational modeling, and high-throughput screening are often employed for developing specific substrate-competitive kinase inhibitors. This review focuses on recent advances in the design and discovery of substrate-competitive inhibitors of protein kinases.

  19. Association of protein kinase FA/GSK-3alpha (a proline-directed kinase and a regulator of protooncogenes) with human cervical carcinoma dedifferentiation/progression.

    PubMed

    Yang, S D; Yu, J S; Lee, T T; Ni, M H; Yang, C C; Ho, Y S; Tsen, T Z

    1995-10-01

    Computer analysis of protein phosphorylation-sites sequence revealed that most transcriptional factors and viral oncoproteins are prime targets for regulation of proline-directed protein phosphorylation, suggesting an association of proline-directed protein kinase (PDPK) family with neoplastic transformation and tumorigenesis. In this report, an immunoprecipitate activity assay of protein kinase FA/glycogen synthase kinase-3alpha (kinase FA/GSK-3alpha) (a particular member of PDPK family) has been optimized for human cervical tissue and used to demonstrate for the first time significantly increased (P < 0.001) activity in poorly differentiated cervical carcinoma (82.8 +/- 6.6 U/mg of protein), moderately differentiated carcinoma (36.2 +/- 3.4 U/mg of protein), and well-differentiated carcinoma (18.3 +/- 2.4 U/mg of protein) from 36 human cervical carcinoma samples when compared to 12 normal controls (4.9 +/- 0.6 U/mg of protein). Immunoblotting analysis further revealed that increased activity of kinase FA/GSK-3alpha in cervical carcinoma is due to overexpression of protein synthesis of the kinase. Taken together, the results provide initial evidence that overexpression of protein synthesis and cellular activity of kinase FA/GSK-3alpha may be involved in human cervical carcinoma dedifferentiation/progression, supporting an association of proline-directed protein kinase with neoplastic transformation and tumorigenesis. Since protein kinase FA/GSK-3alpha may function as a possible regulator of transcription factors/proto-oncogenes, the results further suggest that kinase FA/GSK-3alpha may play a potential role in human cervical carcinogenesis, especially in its dedifferentiation and progression.

  20. Structural investigation of protein kinase C inhibitors

    NASA Technical Reports Server (NTRS)

    Barak, D.; Shibata, M.; Rein, R.

    1991-01-01

    The phospholipid and Ca2+ dependent protein kinase (PKC) plays an essential role in a variety of cellular events. Inhibition of PKC was shown to arrest growth in tumor cell cultures making it a target for possible antitumor therapy. Calphostins are potent inhibitors of PKC with high affinity for the enzyme regulatory site. Structural characteristics of calphostins, which confer the inhibitory activity, are investigated by comparing their optimized structures with the existing models for PKC activation. The resulting model of inhibitory activity assumes interaction with two out of the three electrostatic interaction sites postulated for activators. The model shows two sites of hydrophobic interaction and enables the inhibitory activity of gossypol to be accounted for.

  1. The extended protein kinase C superfamily.

    PubMed Central

    Mellor, H; Parker, P J

    1998-01-01

    Members of the mammalian protein kinase C (PKC) superfamily play key regulatory roles in a multitude of cellular processes, ranging from control of fundamental cell autonomous activities, such as proliferation, to more organismal functions, such as memory. However, understanding of mammalian PKC signalling systems is complicated by the large number of family members. Significant progress has been made through studies based on comparative analysis, which have defined a number of regulatory elements in PKCs which confer specific location and activation signals to each isotype. Further studies on simple organisms have shown that PKC signalling paradigms are conserved through evolution from yeast to humans, underscoring the importance of this family in cellular signalling and giving novel insights into PKC function in complex mammalian systems. PMID:9601053

  2. Diversity, classification and function of the plant protein kinase superfamily

    PubMed Central

    Lehti-Shiu, Melissa D.; Shiu, Shin-Han

    2012-01-01

    Eukaryotic protein kinases belong to a large superfamily with hundreds to thousands of copies and are components of essentially all cellular functions. The goals of this study are to classify protein kinases from 25 plant species and to assess their evolutionary history in conjunction with consideration of their molecular functions. The protein kinase superfamily has expanded in the flowering plant lineage, in part through recent duplications. As a result, the flowering plant protein kinase repertoire, or kinome, is in general significantly larger than other eukaryotes, ranging in size from 600 to 2500 members. This large variation in kinome size is mainly due to the expansion and contraction of a few families, particularly the receptor-like kinase/Pelle family. A number of protein kinases reside in highly conserved, low copy number families and often play broadly conserved regulatory roles in metabolism and cell division, although functions of plant homologues have often diverged from their metazoan counterparts. Members of expanded plant kinase families often have roles in plant-specific processes and some may have contributed to adaptive evolution. Nonetheless, non-adaptive explanations, such as kinase duplicate subfunctionalization and insufficient time for pseudogenization, may also contribute to the large number of seemingly functional protein kinases in plants. PMID:22889912

  3. The Crystal Structure of the Active Form of the C-Terminal Kinase Domain of Mitogen- and Stress-Activated Protein Kinase 1

    SciTech Connect

    Malakhova, Margarita; D'Angelo, Igor; Kim, Hong-Gyum; Kurinov, Igor; Bode, Ann M.; Dong, Zigang

    2010-06-25

    Mitogen- and stress-activated protein kinase 1 (MSK1) is a growth-factor-stimulated serine/threonine kinase that is involved in gene transcription regulation and proinflammatory cytokine stimulation. MSK1 is a dual kinase possessing two nonidentical protein kinase domains in one polypeptide. We present the active conformation of the crystal structures of its C-terminal kinase domain in apo form and in complex with a nonhydrolyzable ATP analogue at 2.0 {angstrom} and 2.5 {angstrom} resolutions, respectively. Structural analysis revealed substantial differences in the contacts formed by the C-terminal helix, which is responsible for the inactivity of other autoinhibited kinases. In the C-terminal kinase domain of MSK1, the C-terminal {alpha}L-helix is located in the surface groove, but forms no hydrogen bonds with the substrate-binding loop or nearby helices, and does not interfere with the protein's autophosphorylation activity. Mutational analysis confirmed that the {alpha}L-helix is inherently nonautoinhibitory. Overexpression of the single C-terminal kinase domain in JB6 cells resulted in tumor-promoter-induced neoplastic transformation in a manner similar to that induced by the full-length MSK1 protein. The overall results suggest that the C-terminal kinase domain of MSK1 is regulated by a novel {alpha}L-helix-independent mechanism, suggesting that a diverse mechanism of autoinhibition and activation might be adopted by members of a closely related protein kinase family.

  4. Insulin accelerates inter-endosomal GLUT4 traffic via phosphatidylinositol 3-kinase and protein kinase B.

    PubMed

    Foster, L J; Li, D; Randhawa, V K; Klip, A

    2001-11-23

    Insulin enhances plasmalemmal-directed traffic of glucose transporter-4 (GLUT4), but it is unknown whether insulin regulates GLUT4 traffic through endosomal compartments. In L6 myoblasts expressing Myc-tagged GLUT4, insulin markedly stimulated the rate of GLUT4myc recycling. In myoblasts stimulated with insulin to maximize surface GLUT4myc levels, we followed the rates of surface-labeled GLUT4myc endocytosis and chased its intracellular distribution in space and time using confocal immunofluorescence microscopy. Surface-labeled GLUT4myc internalized rapidly (t(12) 3 min), reaching the early endosome by 2 min and the transferrin receptor-rich, perinuclear recycling endosome by 20 min. Upon re-addition of insulin, the t(12) of GLUT4 disappearance from the plasma membrane was unchanged (3 min), but strikingly, GLUT4myc reached the recycling endosome by 10 and left by 20 min. This effect of insulin was blocked by the phosphatidylinositol 3-kinase inhibitor LY294002 or by transiently transfected dominant-negative phosphatidylinositol 3-kinase and protein kinase B mutants. In contrast, insulin did not alter the rate of arrival of rhodamine-labeled transferrin at the recycling endosome. These results reveal a heretofore unknown effect of insulin to accelerate inter-endosomal travel rates of GLUT4 and identify the recycling endosome as an obligatory stage in insulin-dependent GLUT4 recycling.

  5. Coordinate regulation of IkappaB kinases by mitogen-activated protein kinase kinase kinase 1 and NF-kappaB-inducing kinase.

    PubMed

    Nemoto, S; DiDonato, J A; Lin, A

    1998-12-01

    IkappaB kinases (IKKalpha and IKKbeta) are key components of the IKK complex that mediates activation of the transcription factor NF-kappaB in response to extracellular stimuli such as inflammatory cytokines, viral and bacterial infection, and UV irradiation. Although NF-kappaB-inducing kinase (NIK) interacts with and activates the IKKs, the upstream kinases for the IKKs still remain obscure. We identified mitogen-activated protein kinase kinase kinase 1 (MEKK1) as an immediate upstream kinase of the IKK complex. MEKK1 is activated by tumor necrosis factor alpha (TNF-alpha) and interleukin-1 and can potentiate the stimulatory effect of TNF-alpha on IKK and NF-kappaB activation. The dominant negative mutant of MEKK1, on the other hand, partially blocks activation of IKK by TNF-alpha. MEKK1 interacts with and stimulates the activities of both IKKalpha and IKKbeta in transfected HeLa and COS-1 cells and directly phosphorylates the IKKs in vitro. Furthermore, MEKK1 appears to act in parallel to NIK, leading to synergistic activation of the IKK complex. The formation of the MEKK1-IKK complex versus the NIK-IKK complex may provide a molecular basis for regulation of the IKK complex by various extracellular signals.

  6. PINCH proteins regulate cardiac contractility by modulating integrin-linked kinase-protein kinase B signaling.

    PubMed

    Meder, Benjamin; Huttner, Inken G; Sedaghat-Hamedani, Farbod; Just, Steffen; Dahme, Tillman; Frese, Karen S; Vogel, Britta; Köhler, Doreen; Kloos, Wanda; Rudloff, Jessica; Marquart, Sabine; Katus, Hugo A; Rottbauer, Wolfgang

    2011-08-01

    Integrin-linked kinase (ILK) is an essential component of the cardiac mechanical stretch sensor and is bound in a protein complex with parvin and PINCH proteins, the so-called ILK-PINCH-parvin (IPP) complex. We have recently shown that inactivation of ILK or β-parvin activity leads to heart failure in zebrafish via reduced protein kinase B (PKB/Akt) activation. Here, we show that PINCH proteins localize at sarcomeric Z disks and costameres in the zebrafish heart and skeletal muscle. To investigate the in vivo role of PINCH proteins for IPP complex stability and PKB signaling within the vertebrate heart, we inactivated PINCH1 and PINCH2 in zebrafish. Inactivation of either PINCH isoform independently leads to instability of ILK, loss of stretch-responsive anf and vegf expression, and progressive heart failure. The predominant cause of heart failure in PINCH morphants seems to be loss of PKB activity, since PKB phosphorylation at serine 473 is significantly reduced in PINCH-deficient hearts and overexpression of constitutively active PKB reconstitutes cardiac function in PINCH morphants. These findings highlight the essential function of PINCH proteins in controlling cardiac contractility by granting IPP/PKB-mediated signaling.

  7. Unveiling the Novel Dual Specificity Protein Kinases in Bacillus anthracis

    PubMed Central

    Arora, Gunjan; Sajid, Andaleeb; Arulanandh, Mary Diana; Singhal, Anshika; Mattoo, Abid R.; Pomerantsev, Andrei P.; Leppla, Stephen H.; Maiti, Souvik; Singh, Yogendra

    2012-01-01

    Dual specificity protein kinases (DSPKs) are unique enzymes that can execute multiple functions in the cell, which are otherwise performed exclusively by serine/threonine and tyrosine protein kinases. In this study, we have characterized the protein kinases Bas2152 (PrkD) and Bas2037 (PrkG) from Bacillus anthracis. Transcriptional analyses of these kinases showed that they are expressed in all phases of growth. In a serendipitous discovery, both kinases were found to be DSPKs. PrkD was found to be similar to the eukaryotic dual specificity Tyr phosphorylation-regulated kinase class of dual specificity kinases, which autophosphorylates on Ser, Thr, and Tyr residues and phosphorylates Ser and Thr residues on substrates. PrkG was found to be a bona fide dual specificity protein kinase that mediates autophosphorylation and substrate phosphorylation on Ser, Thr, and Tyr residues. The sites of phosphorylation in both of the kinases were identified through mass spectrometry. Phosphorylation on Tyr residues regulates the kinase activity of PrkD and PrkG. PrpC, the only known Ser/Thr protein phosphatase, was also found to possess dual specificity. Genistein, a known Tyr kinase inhibitor, was found to inhibit the activities of PrkD and PrkG and affect the growth of B. anthracis cells, indicating a possible role of these kinases in cell growth and development. In addition, the glycolytic enzyme pyruvate kinase was found to be phosphorylated by PrkD on Ser and Thr residues but not by PrkG. Thus, this study provides the first evidence of DSPKs in B. anthracis that belong to different classes and have different modes of regulation. PMID:22711536

  8. Rac-1 and Raf-1 kinases, components of distinct signaling pathways, activate myotonic dystrophy protein kinase

    NASA Technical Reports Server (NTRS)

    Shimizu, M.; Wang, W.; Walch, E. T.; Dunne, P. W.; Epstein, H. F.

    2000-01-01

    Myotonic dystrophy protein kinase (DMPK) is a serine-threonine protein kinase encoded by the myotonic dystrophy (DM) locus on human chromosome 19q13.3. It is a close relative of other kinases that interact with members of the Rho family of small GTPases. We show here that the actin cytoskeleton-linked GTPase Rac-1 binds to DMPK, and coexpression of Rac-1 and DMPK activates its transphosphorylation activity in a GTP-sensitive manner. DMPK can also bind Raf-1 kinase, the Ras-activated molecule of the MAP kinase pathway. Purified Raf-1 kinase phosphorylates and activates DMPK. The interaction of DMPK with these distinct signals suggests that it may play a role as a nexus for cross-talk between their respective pathways and may partially explain the remarkable pleiotropy of DM.

  9. Protein kinase C catalyses the phosphorylation and activation of rat liver phospholipid methyltransferase.

    PubMed Central

    Villalba, M; Pajares, M A; Renart, M F; Mato, J M

    1987-01-01

    When a partially purified rat liver phospholipid methyltransferase is incubated with [gamma-32P]ATP and rat brain protein kinase C, phospholipid methyltransferase (Mr 50,000, pI 4.75) becomes phosphorylated. Phosphorylation of the enzyme showed Ca2+/lipid-dependency. Protein kinase C-dependent phosphorylation of phospholipid methyltransferase was accompanied by an approx. 2-fold activation of the enzyme activity. Activity changes and enzyme phosphorylation showed the same time course. Activation of the enzyme also showed Ca2+/lipid-dependency. Protein kinase C mediates phosphorylation of predominantly serine residues of the methyltransferase. One major peak of phosphorylation was identified by analysis of tryptic phosphopeptides by isoelectrofocusing. This peak (pI 5.2) differs from that phosphorylated by the cyclic AMP-dependent protein kinase (pI 7.2), demonstrating the specificity of phosphorylation of protein kinase C. Tryptic-peptide mapping by h.p.l.c. of the methyltransferase phosphorylated by protein kinase C revealed one major peak of radioactivity, which could be resolved into two labelled phosphopeptides by t.l.c. The significance of protein kinase C-mediated phosphorylation of phospholipid methyltransferase is discussed. Images Fig. 1. Fig. 4. PMID:3593229

  10. Src family protein tyrosine kinases induce autoactivation of Bruton's tyrosine kinase.

    PubMed Central

    Mahajan, S; Fargnoli, J; Burkhardt, A L; Kut, S A; Saouaf, S J; Bolen, J B

    1995-01-01

    Bruton's tyrosine kinase (Btk) is tyrosine phosphorylated and enzymatically activated following ligation of the B-cell antigen receptor. These events are temporally regulated, and Btk activation follows that of various members of the Src family of protein tyrosine kinases, thus raising the possibility that Src kinases participate in the Btk activation process. We have evaluated the mechanism underlying Btk enzyme activation and have explored the potential regulatory relationship between Btk and Src protein kinases. We demonstrate in COS transient-expression assays that Btk can be activated through intramolecular autophosphorylation at tyrosine 551 and that Btk autophosphorylation is required for Btk catalytic functions. Coexpression of Btk with members of the Src family of protein tyrosine kinases, but not Syk, led to Btk tyrosine phosphorylation and activation. Using a series of point mutations in Blk (a representative Src protein kinase) and Btk, we show that Src kinases activate Btk through an indirect mechanism that requires membrane association of the Src enzymes as well as functional Btk SH3 and SH2 domains. Our results are compatible with the idea that Src protein tyrosine kinases contribute to Btk activation by indirectly stimulating Btk intramolecular autophosphorylation. PMID:7565679

  11. Src family protein tyrosine kinases induce autoactivation of Bruton's tyrosine kinase.

    PubMed

    Mahajan, S; Fargnoli, J; Burkhardt, A L; Kut, S A; Saouaf, S J; Bolen, J B

    1995-10-01

    Bruton's tyrosine kinase (Btk) is tyrosine phosphorylated and enzymatically activated following ligation of the B-cell antigen receptor. These events are temporally regulated, and Btk activation follows that of various members of the Src family of protein tyrosine kinases, thus raising the possibility that Src kinases participate in the Btk activation process. We have evaluated the mechanism underlying Btk enzyme activation and have explored the potential regulatory relationship between Btk and Src protein kinases. We demonstrate in COS transient-expression assays that Btk can be activated through intramolecular autophosphorylation at tyrosine 551 and that Btk autophosphorylation is required for Btk catalytic functions. Coexpression of Btk with members of the Src family of protein tyrosine kinases, but not Syk, led to Btk tyrosine phosphorylation and activation. Using a series of point mutations in Blk (a representative Src protein kinase) and Btk, we show that Src kinases activate Btk through an indirect mechanism that requires membrane association of the Src enzymes as well as functional Btk SH3 and SH2 domains. Our results are compatible with the idea that Src protein tyrosine kinases contribute to Btk activation by indirectly stimulating Btk intramolecular autophosphorylation. PMID:7565679

  12. Cytoskeletal protein kinases: titin and its relations in mechanosensing.

    PubMed

    Gautel, Mathias

    2011-07-01

    Titin, the giant elastic ruler protein of striated muscle sarcomeres, contains a catalytic kinase domain related to a family of intrasterically regulated protein kinases. The most extensively studied member of this branch of the human kinome is the Ca(2+)-calmodulin (CaM)-regulated myosin light-chain kinases (MLCK). However, not all kinases of the MLCK branch are functional MLCKs, and about half lack a CaM binding site in their C-terminal autoinhibitory tail (AI). A unifying feature is their association with the cytoskeleton, mostly via actin and myosin filaments. Titin kinase, similar to its invertebrate analogue twitchin kinase and likely other "MLCKs", is not Ca(2+)-calmodulin-activated. Recently, local protein unfolding of the C-terminal AI has emerged as a common mechanism in the activation of CaM kinases. Single-molecule data suggested that opening of the TK active site could also be achieved by mechanical unfolding of the AI. Mechanical modulation of catalytic activity might thus allow cytoskeletal signalling proteins to act as mechanosensors, creating feedback mechanisms between cytoskeletal tension and tension generation or cellular remodelling. Similar to other MLCK-like kinases like DRAK2 and DAPK1, TK is linked to protein turnover regulation via the autophagy/lysosomal system, suggesting the MLCK-like kinases have common functions beyond contraction regulation. PMID:21416260

  13. Cloning of the mitogen-activated S6 kinase from rat liver reveals an enzyme of the second messenger subfamily

    SciTech Connect

    Kozma, S.C.; Ferrari, S. Bassand, P.; Siegmann, M.; Thomas, G. ); Totty, N. )

    1990-10-01

    Recently the authors reported the purification of a mitogen-activated S6 kinase from Swiss mouse 3T3 fibroblasts and rat liver. The rat liver protein was cleaved with cyanogen bromide or trypsin and 17 of the resulting peptides were sequenced. DNA primers were generated from 3 peptides that had homology to sequences of the conserved catalytic domain of protein kinases. These primers were used in the polymerase chain reaction to obtain a 0.4-kilobase DNA fragment. This fragment was either radioactively labeled and hybridized to Northern blots of poly(A){sup {sup plus}} mRNA or used to screen a rat liver cDNA library. Northern blot analysis revealed four transcripts of 2.5, 3.2, 4.0, and 6.0 kilobases, and five S6 kinase clones were obtained by screening the library. Only two of the clones, which were identical, encoded a full-length protein. This protein had a molecular weight of 56,160, which correlated closely to that of the dephosphorylated kinase determined by SDS/PAGE. The catalytic domain of the kinase resembles that of other serine/threonine kinases belonging to the second messenger subfamily of protein kinases.

  14. Insulin-induced Drosophila S6 kinase activation requires phosphoinositide 3-kinase and protein kinase B.

    PubMed Central

    Lizcano, Jose M; Alrubaie, Saif; Kieloch, Agnieszka; Deak, Maria; Leevers, Sally J; Alessi, Dario R

    2003-01-01

    An important mechanism by which insulin regulates cell growth and protein synthesis is through activation of the p70 ribosomal S6 protein kinase (S6K). In mammalian cells, insulin-induced PI3K (phosphoinositide 3-kinase) activation, generates the lipid second messenger PtdIns(3,4,5) P (3), which is thought to play a key role in triggering the activation of S6K. Although the major components of the insulin-signalling pathway are conserved in Drosophila, recent studies suggested that S6K activation does not require PI3K in this system. To investigate further the role of dPI3K (Drosophila PI3K) in dS6K (Drosophila S6K) activation, we examined the effect of two structurally distinct PI3K inhibitors on insulin-induced dS6K activation in Kc167 and S2 Drosophila cell lines. We found that both inhibitors prevented insulin-stimulated phosphorylation and activation of dS6K. To investigate further the role of the dPI3K pathway in regulating dS6K activation, we also used dsRNAi (double-stranded RNA-mediated interference) to decrease expression of dPI3K and the PtdIns(3,4,5) P (3) phosphatase dPTEN ( Drosophila phosphatase and tensin homologue deleted on chromosome 10) in Kc167 and S2 cells. Knock-down of dPI3K prevented dS6K activation, whereas knock-down of dPTEN, which would be expected to increase PtdIns(3,4,5) P (3) levels, stimulated dS6K activity. Moreover, when the expression of the dPI3K target, dPKB (Drosophila protein kinase B), was decreased to undetectable levels, we found that insulin could no longer trigger dS6K activation. This observation provides the first direct demonstration that dPKB is required for insulin-stimulated dS6K activation. We also present evidence that the amino-acid-induced activation of dS6K in the absence of insulin, thought to be mediated by dTOR (Drosophila target of rapamycin), which is unaffected by the inhibition of dPI3K by wortmannin. The results of the present study support the view that, in Drosophila cells, dPI3K and dPKB, as well d

  15. Transphosphorylation of E. coli proteins during production of recombinant protein kinases provides a robust system to characterize kinase specificity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Protein kinase specificity is of fundamental importance to pathway regulation and signal transduction. Here, we report a convenient system to monitor the activity and specificity of recombinant protein kinases expressed in E.coli. We apply this to the study of the cytoplasmic domain of the plant rec...

  16. Structures of Down syndrome kinases, DYRKs, reveal mechanisms of kinase activation and substrate recognition.

    PubMed

    Soundararajan, Meera; Roos, Annette K; Savitsky, Pavel; Filippakopoulos, Panagis; Kettenbach, Arminja N; Olsen, Jesper V; Gerber, Scott A; Eswaran, Jeyanthy; Knapp, Stefan; Elkins, Jonathan M

    2013-06-01

    Dual-specificity tyrosine-(Y)-phosphorylation-regulated kinases (DYRKs) play key roles in brain development, regulation of splicing, and apoptosis, and are potential drug targets for neurodegenerative diseases and cancer. We present crystal structures of one representative member of each DYRK subfamily: DYRK1A with an ATP-mimetic inhibitor and consensus peptide, and DYRK2 including NAPA and DH (DYRK homology) box regions. The current activation model suggests that DYRKs are Ser/Thr kinases that only autophosphorylate the second tyrosine of the activation loop YxY motif during protein translation. The structures explain the roles of this tyrosine and of the DH box in DYRK activation and provide a structural model for DYRK substrate recognition. Phosphorylation of a library of naturally occurring peptides identified substrate motifs that lack proline in the P+1 position, suggesting that DYRK1A is not a strictly proline-directed kinase. Our data also show that DYRK1A wild-type and Y321F mutant retain tyrosine autophosphorylation activity. PMID:23665168

  17. Structures of Down Syndrome Kinases, DYRKs, Reveal Mechanisms of Kinase Activation and Substrate Recognition

    PubMed Central

    Soundararajan, Meera; Roos, Annette K.; Savitsky, Pavel; Filippakopoulos, Panagis; Kettenbach, Arminja N.; Olsen, Jesper V.; Gerber, Scott A.; Eswaran, Jeyanthy; Knapp, Stefan; Elkins, Jonathan M.

    2013-01-01

    Summary Dual-specificity tyrosine-(Y)-phosphorylation-regulated kinases (DYRKs) play key roles in brain development, regulation of splicing, and apoptosis, and are potential drug targets for neurodegenerative diseases and cancer. We present crystal structures of one representative member of each DYRK subfamily: DYRK1A with an ATP-mimetic inhibitor and consensus peptide, and DYRK2 including NAPA and DH (DYRK homology) box regions. The current activation model suggests that DYRKs are Ser/Thr kinases that only autophosphorylate the second tyrosine of the activation loop YxY motif during protein translation. The structures explain the roles of this tyrosine and of the DH box in DYRK activation and provide a structural model for DYRK substrate recognition. Phosphorylation of a library of naturally occurring peptides identified substrate motifs that lack proline in the P+1 position, suggesting that DYRK1A is not a strictly proline-directed kinase. Our data also show that DYRK1A wild-type and Y321F mutant retain tyrosine autophosphorylation activity. PMID:23665168

  18. Plant Raf-like kinase integrates abscisic acid and hyperosmotic stress signaling upstream of SNF1-related protein kinase2.

    PubMed

    Saruhashi, Masashi; Kumar Ghosh, Totan; Arai, Kenta; Ishizaki, Yumiko; Hagiwara, Kazuya; Komatsu, Kenji; Shiwa, Yuh; Izumikawa, Keiichi; Yoshikawa, Harunori; Umezawa, Taishi; Sakata, Yoichi; Takezawa, Daisuke

    2015-11-17

    Plant response to drought and hyperosmosis is mediated by the phytohormone abscisic acid (ABA), a sesquiterpene compound widely distributed in various embryophyte groups. Exogenous ABA as well as hyperosmosis activates the sucrose nonfermenting 1 (SNF1)-related protein kinase2 (SnRK2), which plays a central role in cellular responses against drought and dehydration, although the details of the activation mechanism are not understood. Analysis of a mutant of the moss Physcomitrella patens with reduced ABA sensitivity and reduced hyperosmosis tolerance revealed that a protein kinase designated "ARK" (for "ABA and abiotic stress-responsive Raf-like kinase") plays an essential role in the activation of SnRK2. ARK encoded by a single gene in P. patens belongs to the family of group B3 Raf-like MAP kinase kinase kinases (B3-MAPKKKs) mediating ethylene, disease resistance, and salt and sugar responses in angiosperms. Our findings indicate that ARK, as a novel regulatory component integrating ABA and hyperosmosis signals, represents the ancestral B3-MAPKKKs, which multiplied, diversified, and came to have specific functions in angiosperms. PMID:26540727

  19. Dual activators of Protein Kinase R (PKR) and Protein Kinase R Like Kinase (PERK) Identify Common and Divergent Catalytic Targets

    PubMed Central

    Ming, Jie; Sun, Hong; Cao, Peng; Fusco, Dahlene N.; Chung, Raymond T.; Chorev, Michael; Jin, Qi; Aktas, Bertal H.

    2013-01-01

    Chemical genetics has evolved into a powerful tool for studying gene function in normal- and patho-biology. PKR and PERK, two eukaryotic translation initiation factor 2 alpha (eIF2α) kinases, play critical roles in maintenance of cellular hemostasis, metabolic stability, and anti-viral defenses. Both kinases interact with and phosphorylate additional substrates including tumor suppressor p53 and nuclear protein 90. Loss of function of both kinases has been studied by reverse genetics and recently identified inhibitors. In contrast, activating probes for studying the role of catalytic activity of these kinases are not available. We identified a 3-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-5,7-dihydroxy-4H-chromen-4-one (DHBDC) as specific dual activator of PKR and PERK by screening a chemical library of 20,000 small molecules in a dual luciferase surrogate eIF2α phosphorylation assay. We present here extensive biological characterization and preliminary structure-activity relationship of DHBDC, which phosphorylate eIF2α by activating PKR and PERK but no other eIF2α kinases. These agents also activate downstream effectors of eIF2α phosphorylation; inducing CHOP and suppressing cyclin D1 expression and inhibiting cancer cell proliferation, all in a manner dependent on PKR and PERK. Consistent with the role of eIF2α phosphorylation in viral infection, DHBDC inhibits proliferation of human hepatitis C virus. Finally, DHBDC induces phosphorylation of Ikβα, and activates NF-κB pathway. Surprisingly, activation of NF-κB pathway is dependent on PERK but independent of PKR activity. These data indicate that DHBDC is an invaluable probe for elucidating the role of PKR and PERK in normal- and patho-biology. PMID:23784735

  20. Regulation of tomato Prf by Pto-like protein kinases.

    PubMed

    Mucyn, Tatiana S; Wu, Ai-Jiuan; Balmuth, Alexi L; Arasteh, Julia Maryam; Rathjen, John P

    2009-04-01

    Tomato Prf encodes a nucleotide-binding domain shared by Apaf-1, certain R proteins, and CED-4 fused to C-terminal leucine-rich repeats (NBARC-LRR) protein that is required for bacterial immunity to Pseudomonas syringae and sensitivity to the organophosphate fenthion. The signaling pathways involve two highly related protein kinases. Pto kinase mediates direct recognition of the bacterial effector proteins AvrPto or AvrPtoB. Fen kinase is required for fenthion sensitivity and recognition of bacterial effectors related to AvrPtoB. The role of Pto and its association with Prf has been characterized but Fen is poorly described. We show that, similar to Pto, Fen requires N-myristoylation and kinase activity for signaling and interacts with the N-terminal domain of Prf. Thus, the mechanisms of activation of Prf by the respective protein kinases are similar. Prf-Fen interaction is underlined by coregulatory mechanisms in which Prf negatively regulates Fen, most likely by controlling kinase activity. We further characterized negative regulation of Prf by Pto, and show that regulation is mediated by the previously described negative regulatory patch. Remarkably, the effectors released negative regulation of Prf in a manner dependent on Pto kinase activity. The data suggest a model in which Prf associates generally with Pto-like kinases in tightly regulated complexes, which are activated by effector-mediated disruption of negative regulation. Release of negative regulation may be a general feature of activation of NBARC-LRR proteins by cognate effectors.

  1. The Arabidopsis CDPK-SnRK superfamily of protein kinases.

    PubMed

    Hrabak, Estelle M; Chan, Catherine W M; Gribskov, Michael; Harper, Jeffrey F; Choi, Jung H; Halford, Nigel; Kudla, Jorg; Luan, Sheng; Nimmo, Hugh G; Sussman, Michael R; Thomas, Martine; Walker-Simmons, Kay; Zhu, Jian-Kang; Harmon, Alice C

    2003-06-01

    The CDPK-SnRK superfamily consists of seven types of serine-threonine protein kinases: calcium-dependent protein kinase (CDPKs), CDPK-related kinases (CRKs), phosphoenolpyruvate carboxylase kinases (PPCKs), PEP carboxylase kinase-related kinases (PEPRKs), calmodulin-dependent protein kinases (CaMKs), calcium and calmodulin-dependent protein kinases (CCaMKs), and SnRKs. Within this superfamily, individual isoforms and subfamilies contain distinct regulatory domains, subcellular targeting information, and substrate specificities. Our analysis of the Arabidopsis genome identified 34 CDPKs, eight CRKs, two PPCKs, two PEPRKs, and 38 SnRKs. No definitive examples were found for a CCaMK similar to those previously identified in lily (Lilium longiflorum) and tobacco (Nicotiana tabacum) or for a CaMK similar to those in animals or yeast. CDPKs are present in plants and a specific subgroup of protists, but CRKs, PPCKs, PEPRKs, and two of the SnRK subgroups have been found only in plants. CDPKs and at least one SnRK have been implicated in decoding calcium signals in Arabidopsis. Analysis of intron placements supports the hypothesis that CDPKs, CRKs, PPCKs and PEPRKs have a common evolutionary origin; however there are no conserved intron positions between these kinases and the SnRK subgroup. CDPKs and SnRKs are found on all five Arabidopsis chromosomes. The presence of closely related kinases in regions of the genome known to have arisen by genome duplication indicates that these kinases probably arose by divergence from common ancestors. The PlantsP database provides a resource of continuously updated information on protein kinases from Arabidopsis and other plants.

  2. Specific dephosphorylation of Janus Kinase 2 by protein tyrosine phosphatases.

    PubMed

    Li, Jianzhuo; Liu, Xidong; Chu, Huiying; Fu, Xueqi; Li, Tianbao; Hu, Lianghai; Xing, Shu; Li, Guohui; Gu, Jingkai; Zhao, Zhizhuang Joe

    2015-01-01

    Many protein kinases are activated through phosphorylation of an activation loop thereby turning on downstream signaling pathways. Activation of JAK2, a nonreceptor tyrosine kinase with an important role in growth factor and cytokine signaling, requires phosphorylation of the 1007 and 1008 tyrosyl residues. Dephosphorylation of these two sites by phosphatases presumably inactivates the enzyme, but the underlying mechanism is not known. In this study, we employed MALDI-TOF/TOF and triple quadrupole mass spectrometers to analyze qualitatively and quantitatively the dephosphorylation process by using synthetic peptides derived from the tandem autophosphorylation sites (Y1007 and Y1008) of human JAK2. We found that tyrosine phosphatases catalyzed the dephosphorylation reaction sequentially, but different enzymes exhibited different selectivity. Protein tyrosine phosphatase 1B caused rapid dephosphorylation of Y1008 followed by Y1007, while SHP1 and SHP2 selectively dephosphorylated Y1008 only, and yet HePTP randomly removed a single phosphate from either Y1007 or Y1008, leaving behind mono-phosphorylated peptides. The specificity of dephosphorylation was further confirmed by molecular modeling. The data reveal multiple modes of JAK2 regulation by tyrosine phosphatases, reflecting a complex, and intricate interplay between protein phosphorylation and dephosphorylation.

  3. Developing irreversible inhibitors of the protein kinase cysteinome

    PubMed Central

    Liu, Qingsong; Sabnis, Yogesh; Zhao, Zheng; Zhang, Tinghu; Buhrlage, Sara J.; Jones, Lyn H.; Gray, Nathanael S.

    2013-01-01

    Protein kinases are a large family of approximately 530 highly conserved enzymes that transfer a γ-phosphate group from ATP to a variety of amino acid residues such as tyrosine, serine and threonine which serves as a ubiquitous mechanism for cellular signal transduction. The clinical success of a number of kinase-directed drugs and the frequent observation of disease causing mutations in protein kinases suggest that a large number of kinases may represent therapeutically relevant targets. To-date the majority of clinical and preclinical kinase inhibitors are ATP-competitive, non-covalent inhibitors that achieve selectivity through recognition of unique features of particular protein kinases. Recently there has been renewed interest in the development of irreversible inhibitors that form covalent bonds with cysteine or other nucleophilic residues in the ATP-binding pocket. Irreversible kinase inhibitors have a number of potential advantages including prolonged pharmacodynamics, suitability for rational design, high potency and ability to validate pharmacological specificity through mutation of the reactive cysteine residue. Here we review recent efforts to develop cysteine-targeted irreversible protein kinase inhibitors and discuss their modes of recognizing the ATP-binding pocket and their biological activity profiles. In addition, we provided an informatics assessment of the potential ‘kinase-cysteinome’ and discuss strategies for the efficient development of new covalent inhibitors. PMID:23438744

  4. Exploring the function of protein kinases in schistosomes: perspectives from the laboratory and from comparative genomics

    PubMed Central

    Walker, Anthony J.; Ressurreição, Margarida; Rothermel, Rolf

    2014-01-01

    Eukaryotic protein kinases are well conserved through evolution. The genome of Schistosoma mansoni, which causes intestinal schistosomiasis, encodes over 250 putative protein kinases with all of the main eukaryotic groups represented. However, unraveling functional roles for these kinases is a considerable endeavor, particularly as protein kinases regulate multiple and sometimes overlapping cell and tissue functions in organisms. In this article, elucidating protein kinase signal transduction and function in schistosomes is considered from the perspective of the state-of-the-art methodologies used and comparative organismal biology, with a focus on current advances and future directions. Using the free-living nematode Caenorhabditis elegans as a comparator we predict roles for various schistosome protein kinases in processes vital for host invasion and successful parasitism such as sensory behavior, growth and development. It is anticipated that the characterization of schistosome protein kinases in the context of parasite function will catalyze cutting edge research into host-parasite interactions and will reveal new targets for developing drug interventions against human schistosomiasis. PMID:25132840

  5. Modulators of Stomatal Lineage Signal Transduction Alter Membrane Contact Sites and Reveal Specialization among ERECTA Kinases.

    PubMed

    Ho, Chin-Min Kimmy; Paciorek, Tomasz; Abrash, Emily; Bergmann, Dominique C

    2016-08-22

    Signal transduction from a cell's surface to its interior requires dedicated signaling elements and a cellular environment conducive to signal propagation. Plant development, defense, and homeostasis rely on plasma membrane receptor-like kinases to perceive endogenous and environmental signals, but little is known about their immediate downstream targets and signaling modifiers. Using genetics, biochemistry, and live-cell imaging, we show that the VAP-RELATED SUPPRESSOR OF TMM (VST) family is required for ERECTA-mediated signaling in growth and cell-fate determination and reveal a role for ERECTA-LIKE2 in modulating signaling by its sister kinases. We show that VSTs are peripheral plasma membrane proteins that can form complexes with integral ER-membrane proteins, thereby potentially influencing the organization of the membrane milieu to promote efficient and differential signaling from the ERECTA-family members to their downstream intracellular targets.

  6. Identification of novel pheromone-response regulators through systematic overexpression of 120 protein kinases in yeast.

    PubMed

    Burchett, S A; Scott, A; Errede, B; Dohlman, H G

    2001-07-13

    Protein kinases are well known to transmit and regulate signaling pathways. To identify additional regulators of the pheromone signaling apparatus in yeast, we evaluated an array of 120 likely protein kinases encoded by the yeast genome. Each kinase was fused to glutathione S-transferase, overexpressed, and tested for changes in pheromone responsiveness in vivo. As expected, several known components of the pathway (YCK1, STE7, STE11, FUS3, and KSS1) impaired the growth arrest response. Seven other kinases also interfered with pheromone-induced growth arrest; in rank order they are as follows: YKL116c (renamed PRR1) = YDL214c (renamed PRR2) > YJL141c (YAK1, SRA1) > YNR047w = YCR091w (KIN82) = YIL095w (PRK1) > YCL024w (KCC4). Inhibition of pheromone signaling by PRR1, but not PRR2, required the glutathione S-transferase moiety. Both kinases inhibited gene transcription after stimulation with pheromone, a constitutively active kinase mutant STE11-4, or overexpression of the transcription factor STE12. Neither protein altered the ability of the mitogen-activated protein kinase (MAPK) Fus3 to feedback phosphorylate a known substrate, the MAPK kinase Ste7. These results reveal two new components of the pheromone-signaling cascade in yeast, each acting at a point downstream of the MAPK. PMID:11337509

  7. Resolution of thylakoid polyphenol oxidase and a protein kinase

    SciTech Connect

    Race, H.L.; Davenport, J.W.; Hind, G.

    1995-12-31

    The predominant protein kinase activity in octylglucoside (OG) extracts of spinach thylakoids has been attributed to a 64-kDa protein, tp64. Recent work calls into question the relation between tp64 and protein kinase activity, which were fractionated apart using fluid phase IEF and hydroxylapatite chromatography. Hind et al. sequenced tp64 from the cDNA and showed it to be a polyphenol oxidase (PPO) homolog. Its transit peptide indicates a location for the mature protein within the thylakoid lumen, where there is presumably no ATP and where it is remote from the presumed kinase substrates: the stromally exposed regions of integral PS-II membrane proteins. Here the authors suggest that the kinase is a 64-kDa protein distinct from tp64.

  8. Distinct roles for extracellular-signal-regulated protein kinase (ERK) mitogen-activated protein kinases and phosphatidylinositol 3-kinase in the regulation of Mcl-1 synthesis.

    PubMed Central

    Schubert, K M; Duronio, V

    2001-01-01

    Alterations in the expression of various Bcl-2 family members may act as one means by which a cell's survival may be regulated. The mechanism by which cytokines regulate expression of Bcl-2 family members was examined in the haemopoietic cell line TF-1. Cytokine-induced Mcl-1 protein expression was shown to be controlled through a pathway dependent upon phosphatidylinositol 3-kinase (PI 3-kinase). The cytokine-induced increase in mRNA transcription was not dependent upon PI 3-kinase, thus dissociating the immediate-early transcription factors responsible for Mcl-1 transcription from the PI 3-kinase signalling pathway. In contrast, Mcl-1 mRNA levels were dependent upon MEK [mitogen-activated protein kinase (MAPK)/extracellular-signal-regulated protein kinase kinase] activation, suggesting a role for the Ras/MEK/MAPK pathway in Mcl-1 transcription. Activation of PI 3-kinase was shown to be necessary to stimulate Mcl-1 protein translation. This was not due to any effect on prolonging the half-life of the protein. Finally, the lipid second messenger ceramide was shown to cause a reduction in Mcl-1 protein translation, probably via its ability to inhibit protein kinase B activation, providing further clues regarding the death-inducing effect of this lipid. PMID:11368774

  9. Cross-species sequence analysis reveals multiple charged residue-rich domains that regulate nuclear/cytoplasmic partitioning and membrane localization of a kinase anchoring protein 12 (SSeCKS/Gravin).

    PubMed

    Streb, Jeffrey W; Miano, Joseph M

    2005-07-29

    A kinase anchoring proteins (AKAPs) assemble and compartmentalize multiprotein signaling complexes at discrete subcellular locales and thus confer specificity to transduction cascades using ubiquitous signaling enzymes, such as protein kinase A. Intrinsic targeting domains in each AKAP determine the subcellular localization of these complexes and, along with protein-protein interaction domains, form the core of AKAP function. As a foundational step toward elucidating the relationship between location and function, we have used cross-species sequence analysis and deletion mapping to facilitate the identification of the targeting determinants of AKAP12 (also known as SSeCKS or Gravin). Three charged residue-rich regions were identified that regulate two aspects of AKAP12 localization, nuclear/cytoplasmic partitioning and perinuclear/cell periphery targeting. Using deletion mapping and green fluorescent protein chimeras, we uncovered a heretofore unrecognized nuclear localization potential. Five nuclear localization signals, including a novel class of this type of signal termed X2-NLS, are found in the central region of AKAP12 and are important for nuclear targeting. However, this nuclear localization is suppressed by the negatively charged C terminus that mediates nuclear exclusion. In this condition, the distribution of AKAP12 is regulated by an N-terminal targeting domain that simultaneously directs perinuclear and peripheral AKAP12 localization. Three basic residue-rich regions in the N-terminal targeting region have similarity to the MARCKS proteins and were found to control AKAP12 localization to ganglioside-rich regions at the cell periphery. Our data suggest that AKAP12 localization is regulated by a hierarchy of targeting domains and that the localization of AKAP12-assembled signaling complexes may be dynamically regulated. PMID:15923193

  10. Nicotinamide riboside kinase structures reveal new pathways to NAD+.

    PubMed

    Tempel, Wolfram; Rabeh, Wael M; Bogan, Katrina L; Belenky, Peter; Wojcik, Marzena; Seidle, Heather F; Nedyalkova, Lyudmila; Yang, Tianle; Sauve, Anthony A; Park, Hee-Won; Brenner, Charles

    2007-10-01

    The eukaryotic nicotinamide riboside kinase (Nrk) pathway, which is induced in response to nerve damage and promotes replicative life span in yeast, converts nicotinamide riboside to nicotinamide adenine dinucleotide (NAD+) by phosphorylation and adenylylation. Crystal structures of human Nrk1 bound to nucleoside and nucleotide substrates and products revealed an enzyme structurally similar to Rossmann fold metabolite kinases and allowed the identification of active site residues, which were shown to be essential for human Nrk1 and Nrk2 activity in vivo. Although the structures account for the 500-fold discrimination between nicotinamide riboside and pyrimidine nucleosides, no enzyme feature was identified to recognize the distinctive carboxamide group of nicotinamide riboside. Indeed, nicotinic acid riboside is a specific substrate of human Nrk enzymes and is utilized in yeast in a novel biosynthetic pathway that depends on Nrk and NAD+ synthetase. Additionally, nicotinic acid riboside is utilized in vivo by Urh1, Pnp1, and Preiss-Handler salvage. Thus, crystal structures of Nrk1 led to the identification of new pathways to NAD+. PMID:17914902

  11. [Protein kinase C activation induces platelet apoptosis].

    PubMed

    Zhao, Li-Li; Chen, Meng-Xing; Zhang, Ming-Yi; Dai, Ke-Sheng

    2013-10-01

    Platelet apoptosis elucidated by either physical or chemical compound or platelet storage occurs wildly, which might play important roles in controlling the numbers and functions of circulated platelets, or in the development of some platelet-related diseases. However, up to now, a little is known about the regulatory mechanisms of platelet apoptosis. Protein kinase C (PKC) is highly expressed in platelets and plays central roles in regulating platelet functions. Although there is evidence indicating that PKC is involved in the regulation of apoptosis of nucleated cells, it is still unclear whether PKC plays a role in platelet apoptosis. The aim of this study was to investigate the role of PKC in platelet apoptosis. The effects of PKC on mitochondrial membrane potential (ΔΨm), phosphatidylserine (PS) exposure, and caspase-3 activation of platelets were analyzed by flow cytometry and Western blot. The results showed that the ΔΨm depolarization in platelets was induced by PKC activator in time-dependent manner, and the caspase-3 activation in platelets was induced by PKC in concentration-dependent manner. However, the platelets incubated with PKC inhibitor did not results in ΔΨm depolarization and PS exposure. It is concluded that the PKC activation induces platelet apoptosis through influencing the mitochondrial functions and activating caspase 3. The finds suggest a novel mechanism for PKC in regulating platelet numbers and functions, which has important pathophysiological implications for thrombosis and hemostasis.

  12. Direct Phosphorylation and Activation of a Mitogen-Activated Protein Kinase by a Calcium-Dependent Protein Kinase in Rice[C][W

    PubMed Central

    Xie, Kabin; Chen, Jianping; Wang, Qin; Yang, Yinong

    2014-01-01

    The mitogen-activated protein kinase (MAPK) is a pivotal point of convergence for many signaling pathways in eukaryotes. In the classical MAPK cascade, a signal is transmitted via sequential phosphorylation and activation of MAPK kinase kinase, MAPK kinase (MKK), and MAPK. The activation of MAPK is dependent on dual phosphorylation of a TXY motif by an MKK, which is considered the sole kinase to phosphorylate and activate MAPK. Here, we report a novel regulatory mechanism of MAPK phosphorylation and activation besides the canonical MAPK cascade. A rice (Oryza sativa) calcium-dependent protein kinase (CDPK), CPK18, was identified as an upstream kinase of MAPK (MPK5) in vitro and in vivo. Curiously, CPK18 was shown to phosphorylate and activate MPK5 without affecting the phosphorylation of its TXY motif. Instead, CPK18 was found to predominantly phosphorylate two Thr residues (Thr-14 and Thr-32) that are widely conserved in MAPKs from land plants. Further analyses reveal that the newly identified CPK18-MPK5 pathway represses defense gene expression and negatively regulates rice blast resistance. Our results suggest that land plants have evolved an MKK-independent phosphorylation pathway that directly connects calcium signaling to the MAPK machinery. PMID:25035404

  13. [The role of Gilgamesh protein kinase in Drosophila melanogaster spermatogenesis].

    PubMed

    Nerusheva, O O; Dorogova, N V; Gubanova, N V; Omel'ianchuk, L V

    2008-09-01

    The cellular function of the gilgamesh mutation (89B9-12) of casein kinase gene in Drosophila spermatogenesis was studied. It was demonstrated that the sterility resulting from this mutation is connected with the abnormalities in spermatid individualization. A phylogenetic study of the protein sequences of casein kinases 1 from various organisms was conducted. The Gilgamesh protein was shown to be phylogenetically closer to the cytoplasmic casein kinase family, represented by the YCK3, YCK2, and YCK1 proteins of Saccharomyces cerevisiae and animal gamma-casein kinases. It is known that these yeast casein kinases are involved in vesicular trafficking, which, in turn, is related in its genetic control to the cell membrane remodeling during spermatid individualization. Thus, the data of phylogenetic analysis fit well the results obtained by studying the mutation phenotype. PMID:18846817

  14. Multiple regulatory domains on the Byr2 protein kinase.

    PubMed Central

    Tu, H; Barr, M; Dong, D L; Wigler, M

    1997-01-01

    Byr2 protein kinase, a homolog of mammalian mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEKK) and Saccharomyces cerevisiae STE11, is required for pheromone-induced sexual differentiation in the fission yeast Schizosaccharomyces pombe. Byr2 functions downstream of Ste4, Ras1, and the membrane-associated receptor-coupled heterotrimeric G-protein alpha subunit, Gpa1. Byr2 has a distinctive N-terminal kinase regulatory domain and a characteristic C-terminal kinase catalytic domain. Ste4 and Ras1 interact with the regulatory domain of Byr2 directly. Here, we define the domains of Byr2 that bind Ste4 and Ras1 and show that the Byr2 regulatory domain binds to the catalytic domain in the two-hybrid system. Using Byr2 mutants, we demonstrate that these direct physical interactions are all required for proper signaling. In particular, the physical association between Byr2 regulatory and catalytic domains appears to result in autoinhibition, the loss of which results in kinase activation. Furthermore, we provide evidence that Shk1, the S. pombe homolog of the STE20 protein kinase, can directly antagonize the Byr2 intramolecular interaction, possibly by phosphorylating Byr2. PMID:9315645

  15. RAF protein-serine/threonine kinases: Structure and regulation

    SciTech Connect

    Roskoski, Robert

    2010-08-27

    Research highlights: {yields} The formation of unique side-to-side RAF dimers is required for full kinase activity. {yields} RAF kinase inhibitors block MEK activation in cells containing oncogenic B-RAF. {yields} RAF kinase inhibitors can lead to the paradoxical increase in RAF kinase activity. -- Abstract: A-RAF, B-RAF, and C-RAF are a family of three protein-serine/threonine kinases that participate in the RAS-RAF-MEK-ERK signal transduction cascade. This cascade participates in the regulation of a large variety of processes including apoptosis, cell cycle progression, differentiation, proliferation, and transformation to the cancerous state. RAS mutations occur in 15-30% of all human cancers, and B-RAF mutations occur in 30-60% of melanomas, 30-50% of thyroid cancers, and 5-20% of colorectal cancers. Activation of the RAF kinases requires their interaction with RAS-GTP along with dephosphorylation and also phosphorylation by SRC family protein-tyrosine kinases and other protein-serine/threonine kinases. The formation of unique side-to-side RAF dimers is required for full kinase activity. RAF kinase inhibitors are effective in blocking MEK1/2 and ERK1/2 activation in cells containing the oncogenic B-RAF Val600Glu activating mutation. RAF kinase inhibitors lead to the paradoxical increase in RAF kinase activity in cells containing wild-type B-RAF and wild-type or activated mutant RAS. C-RAF plays a key role in this paradoxical increase in downstream MEK-ERK activation.

  16. Citron kinase enhances ubiquitination of HIV-1 Gag protein and intracellular HIV-1 budding.

    PubMed

    Ding, Jiwei; Zhao, Jianyuan; Sun, Lei; Mi, Zeyun; Cen, Shan

    2016-09-01

    Assembly and budding of human immunodeficiency virus type 1 (HIV-1) particles is a complex process involving a number of host proteins. We have previously reported that the RhoA effector citron kinase enhances HIV-1 production. However, the underlying mechanism is not clear. In this study, we found that citron kinase interacted with HIV-1 Gag protein via its zinc finger and leucine zipper domains. Electron microscopy analysis revealed that citron kinase induced viral particle assembly in multivesicular bodies (MVBs). Citron kinase enhanced ubiquitination of HIV-1 Gag protein. Knockdown of Nedd4L, a member of the HECT ubiquitin E3 ligase family, partly decreased the ability of citron kinase to enhance HIV-1 production and reduced ubiquitination of HIV-1 Gag. Interestingly, the function of citron kinase to promote HIV-1 budding was severely impaired when endogenous ALIX was knocked down. Overexpression of the AAA-type ATPase VPS4 eliminated citron-kinase-mediated enhancement of HIV-1 production. Our results suggest that citron kinase interacts with HIV-1 Gag and enhances HIV-1 production by promoting Gag ubiquitination and inducing viral release via the MVB pathway. PMID:27339686

  17. Protein tyrosine kinase and mitogen-activated protein kinase signalling pathways contribute to differences in heterophil-mediated innate immune responsiveness between two lines of broilers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Protein tyrosine phosphorylation mediates signal transduction of cellular processes, with protein tyrosine kinases (PTKs) regulating virtually all signaling events. The mitogen-activated protein kinase (MAPK) super-family consists of three conserved pathways that convert receptor activation into ce...

  18. Purification and characterization of a casein kinase 2-type protein kinase from pea nuclei

    NASA Technical Reports Server (NTRS)

    Li, H.; Roux, S. J.

    1992-01-01

    Almost all the polyamine-stimulated protein kinase activity associated with the chromatin fraction of nuclei purified from etiolated pea (Pisum sativum L.) plumules is present in a single enzyme that can be extracted from chromatin by 0.35 molar NaCl. This protein kinase can be further purified over 2000-fold by salt fractionation and anion-exchange and casein-agarose column chromatography, after which it is more than 90% pure. The purified kinase has a specific activity of about 650 nanomoles per minute per milligram protein in the absence of polyamines, with either ATP or GTP as phosphoryl donor. Spermidine can stimulate its activity fourfold, with half-maximal activation at about 2 millimolar. Spermine and putrescine also stimulate activity, although somewhat less effectively. This kinase has a tetrameric alpha 2 beta 2 structure with a native molecular weight of 130,000, and subunit molecular weights of 36,000 for the catalytic subunit (alpha) and 29,000 for the regulatory subunit (beta). In western blot analyses, only the alpha subunit reacts strongly with polyclonal antibodies to a Drosophila casein kinase II. The pea kinase can use casein and phosvitin as artificial substrates, phosphorylating both the serine and threonine residues of casein. It has a pH optimum near 8.0, a Vmax of 1.5 micromoles per minute per milligram protein, and a Km for ATP of approximately 75 micromolar. Its activity can be almost completely inhibited by heparin at 5 micrograms per milliliter, but is relatively insensitive to concentrations of staurosporine, K252a, and chlorpromazine that strongly antagonize Ca(2+) -regulated protein kinases. These results are discussed in relation to recent findings that casein kinase 2-type kinases may phosphorylate trans-acting factors that bind to light-regulated promoters in plants.

  19. Sequence and Structure Signatures of Cancer Mutation Hotspots in Protein Kinases

    PubMed Central

    Dixit, Anshuman; Yi, Lin; Gowthaman, Ragul; Torkamani, Ali; Schork, Nicholas J.; Verkhivker, Gennady M.

    2009-01-01

    Protein kinases are the most common protein domains implicated in cancer, where somatically acquired mutations are known to be functionally linked to a variety of cancers. Resequencing studies of protein kinase coding regions have emphasized the importance of sequence and structure determinants of cancer-causing kinase mutations in understanding of the mutation-dependent activation process. We have developed an integrated bioinformatics resource, which consolidated and mapped all currently available information on genetic modifications in protein kinase genes with sequence, structure and functional data. The integration of diverse data types provided a convenient framework for kinome-wide study of sequence-based and structure-based signatures of cancer mutations. The database-driven analysis has revealed a differential enrichment of SNPs categories in functional regions of the kinase domain, demonstrating that a significant number of cancer mutations could fall at structurally equivalent positions (mutational hotspots) within the catalytic core. We have also found that structurally conserved mutational hotspots can be shared by multiple kinase genes and are often enriched by cancer driver mutations with high oncogenic activity. Structural modeling and energetic analysis of the mutational hotspots have suggested a common molecular mechanism of kinase activation by cancer mutations, and have allowed to reconcile the experimental data. According to a proposed mechanism, structural effect of kinase mutations with a high oncogenic potential may manifest in a significant destabilization of the autoinhibited kinase form, which is likely to drive tumorigenesis at some level. Structure-based functional annotation and prediction of cancer mutation effects in protein kinases can facilitate an understanding of the mutation-dependent activation process and inform experimental studies exploring molecular pathology of tumorigenesis. PMID:19834613

  20. Phosphorylation and activation of calcineurin by glycogen synthase (casein) kinase-1 and cyclic AMP-dependent protein kinase

    SciTech Connect

    Singh, T.J.; Wang, J.H.

    1986-05-01

    Calcineurin is a phosphoprotein phosphatase that is activated by divalent cations and further stimulated by calmodulin. In this study calcineurin is shown to be a substrate for both glycogen synthase (casein) kinase-1 (CK-1) and cyclic AMP-dependent protein kinase (A-kinase). Either kinase can catalyze the incorporation of 1.0-1.4 mol /sup 32/P/mol calcineurin. Analysis by SDS-PAGE revealed that only the ..cap alpha.. subunit is phosphorylated. Phosphorylation of calcineurin by either kinase leads to its activation. Using p-nitrophenyl phosphate as a substrate the authors observed a 2-3 fold activation of calcineurin by either Mn/sup 2 +/ or Ni/sup 2 +/ (in the presence or absence of calmodulin) after phosphorylation of calcineurin by either CK-1 or A-kinase. In the absence of Mn/sup 2 +/ or Ni/sup 2 +/ phosphorylated calcineurin, like the nonphosphorylated enzyme, showed very little activity. Ni/sup 2 +/ was a more potent activator of phosphorylated calcineurin compared to Mn/sup 2 +/. Higher levels of activation (5-8 fold) of calcineurin by calmodulin was observed when phosphorylated calcineurin was pretreated with Ni/sup 2 +/ before measurement of phosphatase activity. These results indicate that phosphorylation may be an important mechanism by which calcineurin activity is regulated by Ca/sup 2 +/.

  1. Recent developments of protein kinase inhibitors as potential AD therapeutics.

    PubMed

    Tell, Volkmar; Hilgeroth, Andreas

    2013-01-01

    Present Alzheimer's disease (AD) therapies suffer from inefficient effects on AD symptoms like memory or cognition, especially in later states of the disease. Used acteylcholine esterase inhibitors or the NMDA receptor antagonist memantine address one target structure which is involved in a complex, multifactorial disease progression. So the benefit for patients is presently poor. A more close insight in the AD progression identified more suggested target structures for drug development. Strategies of AD drug development concentrate on novel target structures combined with the established ones dedicated for combined therapy regimes, preferably by the use of one drug which may address two target structures. Protein kinases have been identified as promising target structures because they are involved in AD progression pathways like pathophysiological tau protein phosphorylations and amyloid β toxicity. The review article will shortly view early inhibitors of single protein kinases like glycogen synthase kinase (gsk3) β and cyclin dependent kinase 5. Novel inhibitors will be discussed which address novel AD relevant protein kinases like dual-specificity tyrosine phosphorylation regulated kinase 1A (DYRK1A). Moreover, multitargeting inhibitors will be presented which target several protein kinases and those which are suspected in influencing other AD relevant processes. Such a multitargeting is the most promising strategy to effectively hamper the multifactorial disease progression and thus gives perspective hopes for a future better patient benefit. PMID:24312003

  2. Recent developments of protein kinase inhibitors as potential AD therapeutics

    PubMed Central

    Tell, Volkmar; Hilgeroth, Andreas

    2013-01-01

    Present Alzheimer’s disease (AD) therapies suffer from inefficient effects on AD symptoms like memory or cognition, especially in later states of the disease. Used acteylcholine esterase inhibitors or the NMDA receptor antagonist memantine address one target structure which is involved in a complex, multifactorial disease progression. So the benefit for patients is presently poor. A more close insight in the AD progression identified more suggested target structures for drug development. Strategies of AD drug development concentrate on novel target structures combined with the established ones dedicated for combined therapy regimes, preferably by the use of one drug which may address two target structures. Protein kinases have been identified as promising target structures because they are involved in AD progression pathways like pathophysiological tau protein phosphorylations and amyloid β toxicity. The review article will shortly view early inhibitors of single protein kinases like glycogen synthase kinase (gsk3) β and cyclin dependent kinase 5. Novel inhibitors will be discussed which address novel AD relevant protein kinases like dual-specificity tyrosine phosphorylation regulated kinase 1A (DYRK1A). Moreover, multitargeting inhibitors will be presented which target several protein kinases and those which are suspected in influencing other AD relevant processes. Such a multitargeting is the most promising strategy to effectively hamper the multifactorial disease progression and thus gives perspective hopes for a future better patient benefit. PMID:24312003

  3. Mitogen-Activated Protein Kinase Kinase 3 Is Required for Regulation during Dark-Light Transition.

    PubMed

    Lee, Horim

    2015-07-01

    Plant growth and development are coordinately orchestrated by environmental cues and phytohormones. Light acts as a key environmental factor for fundamental plant growth and physiology through photosensory phytochromes and underlying molecular mechanisms. Although phytochromes are known to possess serine/threonine protein kinase activities, whether they trigger a signal transduction pathway via an intracellular protein kinase network remains unknown. In analyses of mitogen-activated protein kinase kinase (MAPKK, also called MKK) mutants, the mkk3 mutant has shown both a hypersensitive response in plant hormone gibberellin (GA) and a less sensitive response in red light signaling. Surprisingly, light-induced MAPK activation in wild-type (WT) seedlings and constitutive MAPK phosphorylation in dark-grown mkk3 mutant seedlings have also been found, respectively. Therefore, this study suggests that MKK3 acts in negative regulation in darkness and in light-induced MAPK activation during dark-light transition. PMID:26082029

  4. Plant Raf-like kinase integrates abscisic acid and hyperosmotic stress signaling upstream of SNF1-related protein kinase2

    PubMed Central

    Saruhashi, Masashi; Kumar Ghosh, Totan; Arai, Kenta; Ishizaki, Yumiko; Hagiwara, Kazuya; Komatsu, Kenji; Shiwa, Yuh; Izumikawa, Keiichi; Yoshikawa, Harunori; Umezawa, Taishi; Sakata, Yoichi; Takezawa, Daisuke

    2015-01-01

    Plant response to drought and hyperosmosis is mediated by the phytohormone abscisic acid (ABA), a sesquiterpene compound widely distributed in various embryophyte groups. Exogenous ABA as well as hyperosmosis activates the sucrose nonfermenting 1 (SNF1)-related protein kinase2 (SnRK2), which plays a central role in cellular responses against drought and dehydration, although the details of the activation mechanism are not understood. Analysis of a mutant of the moss Physcomitrella patens with reduced ABA sensitivity and reduced hyperosmosis tolerance revealed that a protein kinase designated “ARK” (for “ABA and abiotic stress-responsive Raf-like kinase”) plays an essential role in the activation of SnRK2. ARK encoded by a single gene in P. patens belongs to the family of group B3 Raf-like MAP kinase kinase kinases (B3-MAPKKKs) mediating ethylene, disease resistance, and salt and sugar responses in angiosperms. Our findings indicate that ARK, as a novel regulatory component integrating ABA and hyperosmosis signals, represents the ancestral B3-MAPKKKs, which multiplied, diversified, and came to have specific functions in angiosperms. PMID:26540727

  5. Regulatory crosstalk by protein kinases on CFTR trafficking and activity

    NASA Astrophysics Data System (ADS)

    Farinha, Carlos Miguel; Swiatecka-Urban, Agnieszka; Brautigan, David; Jordan, Peter

    2016-01-01

    Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is a member of the ATP binding cassette (ABC) transporter superfamily that functions as a cAMP-activated chloride ion channel in fluid-transporting epithelia. There is abundant evidence that CFTR activity (i.e. channel opening and closing) is regulated by protein kinases and phosphatases via phosphorylation and dephosphorylation. Here, we review recent evidence for the role of protein kinases in regulation of CFTR delivery to and retention in the plasma membrane. We review this information in a broader context of regulation of other transporters by protein kinases because the overall functional output of transporters involves the integrated control of both their number at the plasma membrane and their specific activity. While many details of the regulation of intracellular distribution of CFTR and other transporters remain to be elucidated, we hope that this review will motivate research providing new insights into how protein kinases control membrane transport to impact health and disease.

  6. Regulatory Crosstalk by Protein Kinases on CFTR Trafficking and Activity.

    PubMed

    Farinha, Carlos M; Swiatecka-Urban, Agnieszka; Brautigan, David L; Jordan, Peter

    2016-01-01

    Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is a member of the ATP binding cassette (ABC) transporter superfamily that functions as a cAMP-activated chloride ion channel in fluid-transporting epithelia. There is abundant evidence that CFTR activity (i.e., channel opening and closing) is regulated by protein kinases and phosphatases via phosphorylation and dephosphorylation. Here, we review recent evidence for the role of protein kinases in regulation of CFTR delivery to and retention in the plasma membrane. We review this information in a broader context of regulation of other transporters by protein kinases because the overall functional output of transporters involves the integrated control of both their number at the plasma membrane and their specific activity. While many details of the regulation of intracellular distribution of CFTR and other transporters remain to be elucidated, we hope that this review will motivate research providing new insights into how protein kinases control membrane transport to impact health and disease.

  7. Regulatory Crosstalk by Protein Kinases on CFTR Trafficking and Activity

    PubMed Central

    Farinha, Carlos M.; Swiatecka-Urban, Agnieszka; Brautigan, David L.; Jordan, Peter

    2016-01-01

    Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is a member of the ATP binding cassette (ABC) transporter superfamily that functions as a cAMP-activated chloride ion channel in fluid-transporting epithelia. There is abundant evidence that CFTR activity (i.e., channel opening and closing) is regulated by protein kinases and phosphatases via phosphorylation and dephosphorylation. Here, we review recent evidence for the role of protein kinases in regulation of CFTR delivery to and retention in the plasma membrane. We review this information in a broader context of regulation of other transporters by protein kinases because the overall functional output of transporters involves the integrated control of both their number at the plasma membrane and their specific activity. While many details of the regulation of intracellular distribution of CFTR and other transporters remain to be elucidated, we hope that this review will motivate research providing new insights into how protein kinases control membrane transport to impact health and disease. PMID:26835446

  8. 4-Anilino-6-phenyl-quinoline inhibitors of mitogen activated protein kinase-activated protein kinase 2 (MK2).

    PubMed

    Olsson, Henric; Sjö, Peter; Ersoy, Oguz; Kristoffersson, Anna; Larsson, Joakim; Nordén, Bo

    2010-08-15

    A class of inhibitors of mitogen activated protein kinase-activated kinase 2 (MK2) was discovered via high-throughput screening. This compound class demonstrates activity against the enzyme with sub-microM IC(50) values, and suppresses LPS-induced TNFalpha levels in THP-1 cells. MK2 inhibition kinetic measurements indicated mixed binding approaching non-ATP competitive inhibition.

  9. Protein kinase C sensitizes olfactory adenylate cyclase

    PubMed Central

    1993-01-01

    Effects of neurotransmitters on cAMP-mediated signal transduction in frog olfactory receptor cells (ORCs) were studied using in situ spike recordings and radioimmunoassays. Carbachol, applied to the mucosal side of olfactory epithelium, amplified the electrical response of ORCs to cAMP-generating odorants, but did not affect unstimulated cells. A similar augmentation of odorant response was observed in the presence of phorbol dibutyrate (PDBu), an activator of protein kinase C (PKC). The electrical response to forskolin, an activator of adenylate cyclase (AC), was also enhanced by PDBu, and it was attenuated by the PKC inhibitor Goe 6983. Forskolin-induced accumulation of cAMP in olfactory tissue was potentiated by carbachol, serotonin, and PDBu to a similar extent. Potentiation was completely suppressed by the PKC inhibitors Goe 6983, staurosporine, and polymyxin B, suggesting that the sensitivity of olfactory AC to stimulation by odorants and forskolin was increased by PKC. Experiments with deciliated olfactory tissue indicated that sensitization of AC was restricted to sensory cilia of ORCs. To study the effects of cell Ca2+ on these mechanisms, the intracellular Ca2+ concentration of olfactory tissue was either increased by ionomycin or decreased by BAPTA/AM. Increasing cell Ca2+ had two effects on cAMP production: (a) the basal cAMP production was enhanced by a mechanism sensitive to inhibitors of calmodulin; and (b) similar to phorbol ester, cell Ca2+ caused sensitization of AC to stimulation by forskolin, an effect sensitive to Goe 6983. Decreasing cell Ca2+ below basal levels rendered AC unresponsive to stimulation by forskolin. These data suggest that a crosstalk mechanism is functional in frog ORCs, linking the sensitivity of AC to the activity of PKC. At increased activity of PKC, olfactory AC becomes more responsive to stimulation by odorants, forskolin, and cell Ca2+. Neurotransmitters appear to use this crosstalk mechanism to regulate olfactory

  10. Regulation of Wnt/β-Catenin Signaling by Protein Kinases

    PubMed Central

    Verheyen, Esther M.; Gottardi, Cara J.

    2011-01-01

    The Wnt/β-catenin signaling pathway plays essential roles during development and adult tissue homeostasis. Inappropriate activation of the pathway can result in a variety of malignancies. Protein kinases have emerged as key regulators at multiple steps of the Wnt pathway. In this review, we present a synthesis covering the latest information on how Wnt signaling is regulated by diverse protein kinases. PMID:19623618

  11. Regulated protein kinases and phosphatases in cell cycle decisions

    PubMed Central

    Novak, Bela; Kapuy, Orsolya; Domingo-Sananes, Maria Rosa; Tyson, John J

    2013-01-01

    Many aspects of cell physiology are controlled by protein kinases and phosphatases, which together determine the phosphorylation state of targeted substrates. Some of these target proteins are themselves kinases or phosphatases or other components of a regulatory network characterized by feedback and feed-forward loops. In this review we describe some common regulatory motifs involving kinases, phosphatases, and their substrates, focusing particularly on bistable switches involved in cellular decision processes. These general principles are applied to cell cycle transitions, with special emphasis on the roles of regulated phosphatases in orchestrating progression from one phase to the next of the DNA replication-division cycle. PMID:20678910

  12. The Energy Landscape Analysis of Cancer Mutations in Protein Kinases

    PubMed Central

    Dixit, Anshuman; Verkhivker, Gennady M.

    2011-01-01

    The growing interest in quantifying the molecular basis of protein kinase activation and allosteric regulation by cancer mutations has fueled computational studies of allosteric signaling in protein kinases. In the present study, we combined computer simulations and the energy landscape analysis of protein kinases to characterize the interplay between oncogenic mutations and locally frustrated sites as important catalysts of allostetric kinase activation. While structurally rigid kinase core constitutes a minimally frustrated hub of the catalytic domain, locally frustrated residue clusters, whose interaction networks are not energetically optimized, are prone to dynamic modulation and could enable allosteric conformational transitions. The results of this study have shown that the energy landscape effect of oncogenic mutations may be allosteric eliciting global changes in the spatial distribution of highly frustrated residues. We have found that mutation-induced allosteric signaling may involve a dynamic coupling between structurally rigid (minimally frustrated) and plastic (locally frustrated) clusters of residues. The presented study has demonstrated that activation cancer mutations may affect the thermodynamic equilibrium between kinase states by allosterically altering the distribution of locally frustrated sites and increasing the local frustration in the inactive form, while eliminating locally frustrated sites and restoring structural rigidity of the active form. The energy landsape analysis of protein kinases and the proposed role of locally frustrated sites in activation mechanisms may have useful implications for bioinformatics-based screening and detection of functional sites critical for allosteric regulation in complex biomolecular systems. PMID:21998754

  13. Characterization of a tomato protein kinase gene induced by infection by Potato spindle tuber viroid.

    PubMed

    Hammond, R W; Zhao, Y

    2000-09-01

    Viroids--covalently closed, circular RNA molecules in the size range of 250 to 450 nucleotides-are the smallest known infectious agents and cause a number of diseases of crop plants. Viroids do not encode proteins and replicate within the nucleus without a helper virus. In many cases, viroid infection results in symptoms of stunting, epinasty, and vein clearing. In our study of the molecular basis of the response of tomato cv. Rutgers to infection by Potato spindle tuber viroid (PSTVd), we have identified a specific protein kinase gene, pkv, that is transcriptionally activated in plants infected with either the intermediate or severe strain of PSTVd, at a lower level in plants inoculated with a mild strain, and not detectable in mock-inoculated plants. A full-length copy of the gene encoding the 55-kDa PKV (protein kinase viroid)-induced protein has been isolated and sequence analysis revealed significant homologies to cyclic nucleotide-dependent protein kinases. Although the sequence motifs in the catalytic domain suggest that it is a serine/threonine protein kinase, the recombinant PKV protein autophosphorylates in vitro on serine and tyrosine residues, suggesting that it is a putative member of the class of dual-specificity protein kinases. PMID:10975647

  14. Mapping of protein-protein interactions within the DNA-dependent protein kinase complex.

    PubMed Central

    Gell, D; Jackson, S P

    1999-01-01

    In mammalian cells, the Ku and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) proteins are required for the correct and efficient repair of DNA double-strand breaks. Ku comprises two tightly-associated subunits of approximately 69 and approximately 83 kDa, which are termed Ku70 and Ku80 (or Ku86), respectively. Previously, a number of regions of both Ku subunits have been demonstrated to be involved in their interaction, but the molecular mechanism of this interaction remains unknown. We have identified a region in Ku70 (amino acid residues 449-578) and a region in Ku80 (residues 439-592) that participate in Ku subunit interaction. Sequence analysis reveals that these interaction regions share sequence homology and suggests that the Ku subunits are structurally related. On binding to a DNA double-strand break, Ku is able to interact with DNA-PKcs, but how this interaction is mediated has not been defined. We show that the extreme C-terminus of Ku80, specifically the final 12 amino acid residues, mediates a highly specific interaction with DNA-PKcs. Strikingly, these residues appear to be conserved only in Ku80 sequences from vertebrate organisms. These data suggest that Ku has evolved to become part of the DNA-PK holo-enzyme by acquisition of a protein-protein interaction motif at the C-terminus of Ku80. PMID:10446239

  15. The C-terminal tail of protein kinase D2 and protein kinase D3 regulates their intracellular distribution

    SciTech Connect

    Papazyan, Romeo; Rozengurt, Enrique; Rey, Osvaldo . E-mail: orey@mednet.ucla.edu

    2006-04-14

    We generated a set of GFP-tagged chimeras between protein kinase D2 (PKD2) and protein kinase D3 (PKD3) to examine in live cells the contribution of their C-terminal region to their intracellular localization. We found that the catalytic domain of PKD2 and PKD3 can localize to the nucleus when expressed without other kinase domains. However, when the C-terminal tail of PKD2 was added to its catalytic domain, the nuclear localization of the resulting protein was inhibited. In contrast, the nuclear localization of the CD of PKD3 was not inhibited by its C-terminal tail. Furthermore, the exchange of the C-terminal tail of PKD2 and PKD3 in the full-length proteins was sufficient to exchange their intracellular localization. Collectively, these data demonstrate that the short C-terminal tail of these kinases plays a critical role in determining their cytoplasmic/nuclear localization.

  16. Analysis of Substrates of Protein Kinase C Isoforms in Human Breast Cells By The Traceable Kinase Method

    PubMed Central

    Chen, Xiangyu; Zhao, Xin; Abeyweera, Thushara P.; Rotenberg, Susan A.

    2012-01-01

    A previous report (Biochemistry 46: 2364–2370, 2007) described the application of The Traceable Kinase Method to identify substrates of PKCα in non-transformed human breast MCF-10A cells. Here, a non-radioactive variation of this method compared the phospho-protein profiles of three traceable PKC isoforms (α, δ and ζ) for the purpose of identifying novel, isoform-selective substrates. Each FLAG-tagged traceable kinase was expressed and co-immunoprecipitated along with high affinity substrates. The isolated kinase and its associated substrates were subjected to an in vitro phosphorylation reaction with traceable kinase-specific N6-phenyl-ATP, and the resulting phospho-proteins were analyzed by Western blot with an antibody that recognizes the phosphorylated PKC consensus site. Phospho-protein profiles generated by PKC-α and -δ were similar and differed markedly from that of PKC-ζ. Mass spectrometry of selected bands revealed known PKC substrates and several potential substrates that included the small GTPase-associated effector protein Cdc42 effector protein-4 (CEP4). Of those potential substrates tested, only CEP4 was phosphorylated by pure PKC-α, –δ, and −ζ isoforms in vitro, and by endogenous PKC isoforms in MCF-10A cells treated with DAG-lactone, a membrane permeable PKC activator. Under these conditions, the stoichiometry of CEP4 phosphorylation was 3.2 ± 0.5 (mol phospho-CEP4/mol CEP4). Following knock-down with isoform-specific shRNA-encoding plasmids, phosphorylation of CEP4 was substantially decreased in response to silencing of each of the three isoforms (PKC–α, –δ, or –ζ), whereas testing of kinase-dead mutants supported a role for only PKC-α and –δ in CEP4 phosphorylation. These findings identify CEP4 as a novel intracellular PKC substrate that is phosphorylated by multiple PKC isoforms. PMID:22897107

  17. Leishmania Infection Engages Non-Receptor Protein Kinases Differentially to Persist in Infected Hosts

    PubMed Central

    Zhang, Naixin; Kima, Peter E.

    2016-01-01

    Protein kinases play important roles in the regulation of cellular activities. In cells infected by pathogens, there is an increasing appreciation that dysregulated expression of protein kinases promotes the success of intracellular infections. In Leishmania-infected cells, expression and activation of protein kinases, such as the mitogen-activated protein kinases, kinases in the PI3-kinase signaling pathway, and kinases in the NF-κB-signaling pathway, are modulated in some manner. Several recent reviews have discussed our current understanding of the roles of these kinases in Leishmania infections. Apart from the kinases in the pathways enumerated above, there are other host cell protein kinases that are activated during the Leishmania infection of mammalian cells whose roles also appear to be significant. This review discusses recent observations on the Abl family of protein kinases and the protein kinase regulated by RNA in Leishmania infections. PMID:27148265

  18. Leishmania Infection Engages Non-Receptor Protein Kinases Differentially to Persist in Infected Hosts.

    PubMed

    Zhang, Naixin; Kima, Peter E

    2016-01-01

    Protein kinases play important roles in the regulation of cellular activities. In cells infected by pathogens, there is an increasing appreciation that dysregulated expression of protein kinases promotes the success of intracellular infections. In Leishmania-infected cells, expression and activation of protein kinases, such as the mitogen-activated protein kinases, kinases in the PI3-kinase signaling pathway, and kinases in the NF-κB-signaling pathway, are modulated in some manner. Several recent reviews have discussed our current understanding of the roles of these kinases in Leishmania infections. Apart from the kinases in the pathways enumerated above, there are other host cell protein kinases that are activated during the Leishmania infection of mammalian cells whose roles also appear to be significant. This review discusses recent observations on the Abl family of protein kinases and the protein kinase regulated by RNA in Leishmania infections.

  19. Targeting protein kinases in central nervous system disorders

    PubMed Central

    Chico, Laura K.; Van Eldik, Linda J.; Watterson, D. Martin

    2010-01-01

    Protein kinases are a growing drug target class in disorders in peripheral tissues, but the development of kinase-targeted therapies for central nervous system (CNS) diseases remains a challenge, largely owing to issues associated specifically with CNS drug discovery. However, several candidate therapeutics that target CNS protein kinases are now in various stages of preclinical and clinical development. We review candidate compounds and discuss selected CNS protein kinases that are emerging as important therapeutic targets. In addition, we analyse trends in small-molecule properties that correlate with key challenges in CNS drug discovery, such as blood–brain barrier penetrance and cytochrome P450-mediated metabolism, and discuss the potential of future approaches that will integrate molecular-fragment expansion with pharmacoinformatics to address these challenges. PMID:19876042

  20. The Dimeric Architecture of Checkpoint Kinases Mec1ATR and Tel1ATM Reveal a Common Structural Organization*

    PubMed Central

    Sawicka, Marta; Wanrooij, Paulina H.; Darbari, Vidya C.; Tannous, Elias; Hailemariam, Sarem; Bose, Daniel; Makarova, Alena V.; Burgers, Peter M.; Zhang, Xiaodong

    2016-01-01

    The phosphatidylinositol 3-kinase-related protein kinases are key regulators controlling a wide range of cellular events. The yeast Tel1 and Mec1·Ddc2 complex (ATM and ATR-ATRIP in humans) play pivotal roles in DNA replication, DNA damage signaling, and repair. Here, we present the first structural insight for dimers of Mec1·Ddc2 and Tel1 using single-particle electron microscopy. Both kinases reveal a head to head dimer with one major dimeric interface through the N-terminal HEAT (named after Huntingtin, elongation factor 3, protein phosphatase 2A, and yeast kinase TOR1) repeat. Their dimeric interface is significantly distinct from the interface of mTOR complex 1 dimer, which oligomerizes through two spatially separate interfaces. We also observe different structural organizations of kinase domains of Mec1 and Tel1. The kinase domains in the Mec1·Ddc2 dimer are located in close proximity to each other. However, in the Tel1 dimer they are fully separated, providing potential access of substrates to this kinase, even in its dimeric form. PMID:27129217

  1. Protein Kinases and Parkinson’s Disease

    PubMed Central

    Mehdi, Syed Jafar; Rosas-Hernandez, Hector; Cuevas, Elvis; Lantz, Susan M.; Barger, Steven W.; Sarkar, Sumit; Paule, Merle G.; Ali, Syed F.; Imam, Syed Z.

    2016-01-01

    Currently, the lack of new drug candidates for the treatment of major neurological disorders such as Parkinson’s disease has intensified the search for drugs that can be repurposed or repositioned for such treatment. Typically, the search focuses on drugs that have been approved and are used clinically for other indications. Kinase inhibitors represent a family of popular molecules for the treatment and prevention of various cancers, and have emerged as strong candidates for such repurposing because numerous serine/threonine and tyrosine kinases have been implicated in the pathobiology of Parkinson’s disease. This review focuses on various kinase-dependent pathways associated with the expression of Parkinson’s disease pathology, and evaluates how inhibitors of these pathways might play a major role as effective therapeutic molecules. PMID:27657053

  2. Human immunodeficiency virus type 1 Nef binds directly to Lck and mitogen-activated protein kinase, inhibiting kinase activity.

    PubMed Central

    Greenway, A; Azad, A; Mills, J; McPhee, D

    1996-01-01

    It is now well established that human immunodeficiency virus type I (HIV-1) Nef contributes substantially to disease pathogenesis by augmenting virus replication and markedly perturbing T-cell function. The effect of Nef on host cell activation could be explained in part by its interaction with specific cellular proteins involved in signal transduction, including at least a member of the src family kinase, Lck, and the serine/threonine kinase, mitogen-activated protein kinase (MAPK). Recombinant Nef directly interacted with purified Lck and MAPK in coprecipitation experiments and binding assays. A proline-rich repeat sequence [(Pxx)4] in Nef occurring between amino acid residues 69 to 78 is highly conserved and bears strong resemblance to a defined consensus sequence identified as an SH3 binding domain present in several proteins which can interact with the SH3 domain of various signalling and cytoskeletal proteins. Binding and coprecipitation assays with short synthetic peptides corresponding to the proline-rich repeat sequence [(Pxx)4] of Nef and the SH2, SH3, or SH2 and SH3 domains of Lck revealed that the interaction between these two proteins is at least in part mediated by the proline repeat sequence of Nef and the SH3 domain of Lck. In addition to direct binding to full-length Nef, MAPK was also shown to bind the same proline repeat motif. Nef protein significantly decreased the in vitro kinase activity of Lck and MAPK. Inhibition of key members of signalling cascades, including those emanating from the T-cell receptor, by the HIV-1 Nef protein undoubtedly alters the ability of the infected T cell to respond to antigens or cytokines, facilitating HIV-1 replication and contributing to HIV-1-induced disease pathogenesis. PMID:8794306

  3. Protein kinase A and casein kinases mediate sequential phosphorylation events in the circadian negative feedback loop.

    PubMed

    Huang, Guocun; Chen, She; Li, Shaojie; Cha, Joonseok; Long, Chengzu; Li, Lily; He, Qiyang; Liu, Yi

    2007-12-15

    Regulation of circadian clock components by phosphorylation plays essential roles in clock functions and is conserved from fungi to mammals. In the Neurospora circadian negative feedback loop, FREQUENCY (FRQ) protein inhibits WHITE COLLAR (WC) complex activity by recruiting the casein kinases CKI and CKII to phosphorylate the WC proteins, resulting in the repression of frq transcription. On the other hand, CKI and CKII progressively phosphorylate FRQ to promote FRQ degradation, a process that is a major determinant of circadian period length. Here, by using whole-cell isotope labeling and quantitative mass spectrometry methods, we show that the WC-1 phosphorylation events critical for the negative feedback process occur sequentially-first by a priming kinase, then by the FRQ-recruited casein kinases. We further show that the cyclic AMP-dependent protein kinase A (PKA) is essential for clock function and inhibits WC activity by serving as a priming kinase for the casein kinases. In addition, PKA also regulates FRQ phosphorylation, but unlike CKI and CKII, PKA stabilizes FRQ, similar to the stabilization of human PERIOD2 (hPER2) due to the phosphorylation at the familial advanced sleep phase syndrome (FASPS) site. Thus, PKA is a key clock component that regulates several critical processes in the circadian negative feedback loop. PMID:18079175

  4. A Novel Mode of Protein Kinase Inhibition Exploiting Hydrophobic Motifs of Autoinhibited Kinases

    SciTech Connect

    S Eathiraj; R Palma; M Hirschi; E Volckova; E Nakuci; J Castro; C Chen; T Chan; D France; M Ashwell

    2011-12-31

    Protein kinase inhibitors with enhanced selectivity can be designed by optimizing binding interactions with less conserved inactive conformations because such inhibitors will be less likely to compete with ATP for binding and therefore may be less impacted by high intracellular concentrations of ATP. Analysis of the ATP-binding cleft in a number of inactive protein kinases, particularly in the autoinhibited conformation, led to the identification of a previously undisclosed non-polar region in this cleft. This ATP-incompatible hydrophobic region is distinct from the previously characterized hydrophobic allosteric back pocket, as well as the main pocket. Generalized hypothetical models of inactive kinases were constructed and, for the work described here, we selected the fibroblast growth factor receptor (FGFR) tyrosine kinase family as a case study. Initial optimization of a FGFR2 inhibitor identified from a library of commercial compounds was guided using structural information from the model. We describe the inhibitory characteristics of this compound in biophysical, biochemical, and cell-based assays, and have characterized the binding mode using x-ray crystallographic studies. The results demonstrate, as expected, that these inhibitors prevent activation of the autoinhibited conformation, retain full inhibitory potency in the presence of physiological concentrations of ATP, and have favorable inhibitory activity in cancer cells. Given the widespread regulation of kinases by autoinhibitory mechanisms, the approach described herein provides a new paradigm for the discovery of inhibitors by targeting inactive conformations of protein kinases.

  5. Involvement of mitogen-activated protein kinase activation in the signal-transduction pathways of the soya bean oxidative burst.

    PubMed Central

    Taylor, A T; Kim, J; Low, P S

    2001-01-01

    The oxidative burst constitutes one of the most rapid defence responses characterized in the Plant Kingdom. We have observed that four distinct elicitors of the soya bean oxidative burst activate kinases of masses approximately 44 kDa and approximately 47 kDa. Evidence that these kinases regulate production of reactive oxygen species include: (i) their rapid activation by oxidative burst elicitors, (ii) their tight temporal correlation between activation/deactivation of the kinases and activation/deactivation of the oxidative burst, (iii) the identical pharmacological profile of kinase activation and oxidant production for 13 commonly used inhibitors, and (iv) the autologous activation of both kinases and oxidant production by calyculin A and cantharidin, two phosphatase inhibitors. Immunological and biochemical studies reveal that the activated 44 kDa and 47 kDa kinases are mitogen-activated protein (MAP) kinase family members. The kinases prefer myelin basic protein as a substrate, and they phosphorylate primarily on threonine residues. The kinases are themselves phosphorylated on tyrosine residues, and this phosphorylation is required for activity. Finally, both kinases are recognized by an antibody against activated MAP kinase immediately after (but not before) cell stimulation by elicitors. Based on these and other observations, a preliminary sequence of signalling steps linking elicitor stimulation, kinase activation and Ca(2+) entry, to initiation of oxidant production, is proposed. PMID:11311144

  6. Protein Kinase C and Extracellular Signal-Regulated Kinase Regulate Movement, Attachment, Pairing and Egg Release in Schistosoma mansoni

    PubMed Central

    Ressurreição, Margarida; De Saram, Paulu; Kirk, Ruth S.; Rollinson, David; Emery, Aidan M.; Page, Nigel M.; Davies, Angela J.; Walker, Anthony J.

    2014-01-01

    Protein kinases C (PKCs) and extracellular signal-regulated kinases (ERKs) are evolutionary conserved cell signalling enzymes that coordinate cell function. Here we have employed biochemical approaches using ‘smart’ antibodies and functional screening to unravel the importance of these enzymes to Schistosoma mansoni physiology. Various PKC and ERK isotypes were detected, and were differentially phosphorylated (activated) throughout the various S. mansoni life stages, suggesting isotype-specific roles and differences in signalling complexity during parasite development. Functional kinase mapping in adult worms revealed that activated PKC and ERK were particularly associated with the adult male tegument, musculature and oesophagus and occasionally with the oesophageal gland; other structures possessing detectable activated PKC and/or ERK included the Mehlis' gland, ootype, lumen of the vitellaria, seminal receptacle and excretory ducts. Pharmacological modulation of PKC and ERK activity in adult worms using GF109203X, U0126, or PMA, resulted in significant physiological disturbance commensurate with these proteins occupying a central position in signalling pathways associated with schistosome muscular activity, neuromuscular coordination, reproductive function, attachment and pairing. Increased activation of ERK and PKC was also detected in worms following praziquantel treatment, with increased signalling associated with the tegument and excretory system and activated ERK localizing to previously unseen structures, including the cephalic ganglia. These findings support roles for PKC and ERK in S. mansoni homeostasis, and identify these kinase groups as potential targets for chemotherapeutic treatments against human schistosomiasis, a neglected tropical disease of enormous public health significance. PMID:24921927

  7. Archaeal protein kinases and protein phosphatases: insights from genomics and biochemistry.

    PubMed Central

    Kennelly, Peter J

    2003-01-01

    Protein phosphorylation/dephosphorylation has long been considered a recent addition to Nature's regulatory arsenal. Early studies indicated that this molecular regulatory mechanism existed only in higher eukaryotes, suggesting that protein phosphorylation/dephosphorylation had emerged to meet the particular signal-transduction requirements of multicellular organisms. Although it has since become apparent that simple eukaryotes and even bacteria are sites of protein phosphorylation/dephosphorylation, the perception widely persists that this molecular regulatory mechanism emerged late in evolution, i.e. after the divergence of the contemporary phylogenetic domains. Only highly developed cells, it was reasoned, could afford the high 'overhead' costs inherent in the acquisition of dedicated protein kinases and protein phosphatases. The advent of genome sequencing has provided an opportunity to exploit Nature's phylogenetic diversity as a vehicle for critically examining this hypothesis. In tracing the origins and evolution of protein phosphorylation/dephosphorylation, the members of the Archaea, the so-called 'third domain of life', will play a critical role. Whereas several studies have demonstrated that archaeal proteins are subject to modification by covalent phosphorylation, relatively little is known concerning the identities of the proteins affected, the impact on their functional properties, or the enzymes that catalyse these events. However, examination of several archaeal genomes has revealed the widespread presence of several ostensibly 'eukaryotic' and 'bacterial' protein kinase and protein phosphatase paradigms. Similar findings of 'phylogenetic trespass' in members of the Eucarya (eukaryotes) and the Bacteria suggest that this versatile molecular regulatory mechanism emerged at an unexpectedly early point in development of 'life as we know it'. PMID:12444920

  8. Light-assisted small molecule screening against protein kinases

    PubMed Central

    Inglés-Prieto, Álvaro; Reichhart, Eva; Muellner, Markus K.; Nowak, Matthias; Nijman, Sebastian M.; Grusch, Michael; Janovjak, Harald

    2015-01-01

    High-throughput live-cell screens are intricate elements of systems biology studies and drug discovery pipelines. Here, we demonstrate an optogenetics-assisted method that obviates the addition of chemical activators and reporters, reduces the number of operational steps and increases information content in a cell-based small molecule screen against human protein kinases including an orphan receptor tyrosine kinase. This blueprint for all-optical screening can be adapted to many drug targets and cellular processes. PMID:26457372

  9. Fast kinase domain-containing protein 3 is a mitochondrial protein essential for cellular respiration

    SciTech Connect

    Simarro, Maria; Gimenez-Cassina, Alfredo; Kedersha, Nancy; Lazaro, Jean-Bernard; Adelmant, Guillaume O.; Marto, Jarrod A.; Rhee, Kirsten; Tisdale, Sarah; Danial, Nika; Benarafa, Charaf; Orduna, Anonio; Anderson, Paul

    2010-10-22

    Research highlights: {yields} Five members of the FAST kinase domain-containing proteins are localized to mitochondria in mammalian cells. {yields} The FASTKD3 interactome includes proteins involved in various aspects of mitochondrial metabolism. {yields} Targeted knockdown of FASTKD3 significantly reduces basal and maximal mitochondrial oxygen consumption. -- Abstract: Fas-activated serine/threonine phosphoprotein (FAST) is the founding member of the FAST kinase domain-containing protein (FASTKD) family that includes FASTKD1-5. FAST is a sensor of mitochondrial stress that modulates protein translation to promote the survival of cells exposed to adverse conditions. Mutations in FASTKD2 have been linked to a mitochondrial encephalomyopathy that is associated with reduced cytochrome c oxidase activity, an essential component of the mitochondrial electron transport chain. We have confirmed the mitochondrial localization of FASTKD2 and shown that all FASTKD family members are found in mitochondria. Although human and mouse FASTKD1-5 genes are expressed ubiquitously, some of them are most abundantly expressed in mitochondria-enriched tissues. We have found that RNA interference-mediated knockdown of FASTKD3 severely blunts basal and stress-induced mitochondrial oxygen consumption without disrupting the assembly of respiratory chain complexes. Tandem affinity purification reveals that FASTKD3 interacts with components of mitochondrial respiratory and translation machineries. Our results introduce FASTKD3 as an essential component of mitochondrial respiration that may modulate energy balance in cells exposed to adverse conditions by functionally coupling mitochondrial protein synthesis to respiration.

  10. Varicella-Zoster Virus Open Reading Frame 66 Protein Kinase and Its Relationship to Alphaherpesvirus US3 Kinases

    PubMed Central

    Erazo, Angela

    2014-01-01

    The varicella-zoster virus (VZV) open reading frame (ORF) 66 encodes a basophilic kinase orthologous to the US3 protein kinases found in all alphaherpesviruses. This review summarizes current information on the ORF66 kinase, and outlines apparent differences from other US3 kinases, as well as some of the conserved functions. One critical difference is the VZV ORF66 kinase targeting of the major regulatory VZV IE62 protein to control its nuclear import and assembly into the VZV virion, which is so far unprecedented in the alphaherpesviruses. However, ORF66 targets some cellular targets which are also targeted by US3 kinases of other herpesviruses, including the histone deacetylase-1 and 2 proteins, pathways that lead to changes in actin dynamics, and the targeting of substrates of protein kinase A, including the nuclear matrix protein matrin 3. PMID:20186610

  11. Tomato 14-3-3 protein TFT7 interacts with a MAP kinase kinase to regulate immunity-associated programmed cell death mediated by diverse disease resistance proteins.

    PubMed

    Oh, Chang-Sik; Martin, Gregory B

    2011-04-22

    Programmed cell death (PCD) associated with immunity is triggered when a plant disease resistance (R) protein recognizes a corresponding pathogen virulence protein. In tomato, detection by the host Pto kinase of the Pseudomonas syringae proteins AvrPto or AvrPtoB causes localized PCD. Previously, we reported that both MAPKKKα (mitogen-activated protein kinase kinase kinase) and the tomato 14-3-3 protein 7 (TFT7) positively regulate Pto-mediated PCD in tomato and Nicotiana benthamiana. In addition, in contrast to MAPKKKα, TFT7 is required for PCD mediated by four other R proteins. Here we investigate why TFT7 is required for PCD induced by diverse R proteins in plants. We discovered that a MAPKK, SlMKK2, which acts downstream of SlMAPKKKα, also interacts with TFT7 in plant cells. Gene silencing experiments revealed that the orthologous genes of both SlMKK2 and TFT7 in N. benthamiana are required for PCD mediated by the same set of R proteins. SlMKK2 and its orthologs contain a 14-3-3 binding site in their N terminus, and Thr(33) in this site is required for interaction with TFT7 in vivo. Like the structurally similar human 14-3-3ε protein, TFT7 forms a homodimer in vivo. Because TFT7 interacts with both SlMAPKKKα and SlMKK2 and also forms a homodimer, we propose that TFT7 may coordinately recruit these client proteins for efficient signal transfer, leading to PCD induction. PMID:21378171

  12. Protein Kinases of the Hippo Pathway: Regulation and Substrates

    PubMed Central

    Avruch, Joseph; Zhou, Dawang; Fitamant, Julien; Bardeesy, Nabeel; Mou, Fan; Barrufet, Laura Regué

    2012-01-01

    The “Hippo” signaling pathway has emerged as a major regulator of cell proliferation and survival in metazoans. The pathway, as delineated by genetic and biochemical studies in Drosophila, consists of a kinase cascade regulated by cell-cell contact and cell polarity that inhibits the transcriptional coactivator Yorkie and its proliferative, anti-differentiation, antiapoptotic transcriptional program. The core pathway components are the GC kinase Hippo, which phosphorylates the noncatalytic polypeptide Mats/Mob1 and, with the assistance of the scaffold protein Salvador, phosphorylates the ndr-family kinase Lats. In turn phospho-Lats, after binding to phospho-Mats, autoactivates and phosphorylates Yorkie, resulting in its nuclear exit. Hippo also uses the scaffold protein Furry and a different Mob protein to control another ndr-like kinase, the morphogenetic regulator Tricornered. Architecturally homologous kinase cascades consisting of a GC kinase, a Mob protein, a scaffolding polypeptide and an ndr-like kinase are well described in yeast; in S. cerevisiae e.g., the MEN pathway promotes mitotic exit whereas the RAM network, using a different GC kinase, Mob protein, scaffold and ndr-like kinase, regulates cell polarity and morphogenesis. In mammals, the Hippo orthologues Mst1 and Mst2 utilize the Salvador ortholog WW45/Sav1 and other scaffolds to regulate the kinases Lats1/Lats2 and ndr1/ndr2. As in Drosophila, murine Mst1/Mst2, in a redundant manner, negatively regulate the Yorkie ortholog YAP in the epithelial cells of the liver and gut; loss of both Mst1 and Mst2 results in hyperproliferation and tumorigenesis that can be largely negated by reduction or elimination of YAP. Despite this conservation, considerable diversification in pathway composition and regulation is already evident; in skin e.g., YAP phosphorylation is independent of Mst1Mst2 and Lats1Lats2. Moreover, in lymphoid cells, Mst1/Mst2, under the control of the Rap1 GTPase and independent of YAP

  13. Chimeric calcium/calmodulin-dependent protein kinase in tobacco: differential regulation by calmodulin isoforms

    NASA Technical Reports Server (NTRS)

    Liu, Z.; Xia, M.; Poovaiah, B. W.

    1998-01-01

    cDNA clones of chimeric Ca2+/calmodulin-dependent protein kinase (CCaMK) from tobacco (TCCaMK-1 and TCCaMK-2) were isolated and characterized. The polypeptides encoded by TCCaMK-1 and TCCaMK-2 have 15 different amino acid substitutions, yet they both contain a total of 517 amino acids. Northern analysis revealed that CCaMK is expressed in a stage-specific manner during anther development. Messenger RNA was detected when tobacco bud sizes were between 0.5 cm and 1.0 cm. The appearance of mRNA coincided with meiosis and became undetectable at later stages of anther development. The reverse polymerase chain reaction (RT-PCR) amplification assay using isoform-specific primers showed that both of the CCaMK mRNAs were expressed in anther with similar expression patterns. The CCaMK protein expressed in Escherichia coli showed Ca2+-dependent autophosphorylation and Ca2+/calmodulin-dependent substrate phosphorylation. Calmodulin isoforms (PCM1 and PCM6) had differential effects on the regulation of autophosphorylation and substrate phosphorylation of tobacco CCaMK, but not lily CCaMK. The evolutionary tree of plant serine/threonine protein kinases revealed that calmodulin-dependent kinases form one subgroup that is distinctly different from Ca2+-dependent protein kinases (CDPKs) and other serine/threonine kinases in plants.

  14. Purification and characterization of echinoderm casein kinase II. Regulation by protein kinase C.

    PubMed Central

    Sanghera, J S; Charlton, L A; Paddon, H B; Pelech, S L

    1992-01-01

    Casein kinase II (CKII) is one of several protein kinases that become activated before germinal-vesicle breakdown in maturing sea-star oocytes. Echinoderm CKII was purified over 11,000-fold with a recovery of approximately 10% by sequential fractionation of the oocyte cytosol on tyrosine-agarose, heparin-agarose, casein-agarose and MonoQ. The purified enzyme contained 45, 38 and 28 kDa polypeptides, which corresponded to its alpha, alpha' and beta subunits respectively. The beta-subunit was autophosphorylated on one major tryptic peptide on serine residues, whereas the alpha'-subunit incorporated phosphate into at least two tryptic peptides primarily on threonine residues. Western-blotting analysis of sea-star oocyte extracts with two different anti-peptide antibodies that recognized conserved regions of the alpha-subunit indicated that the protein levels of the alpha- and alpha'-subunits of CKII were unchanged during oocyte maturation. The purified CKII was partly inactivated (by 25%) by preincubation with protein-serine/threonine phosphatase 2A, but protein-tyrosine phosphatases had no effect. The beta-subunit of CKII was phosphorylated on a serine residue(s) up to 0.54 mol of P/mol of beta-subunit by purified protein kinase C, and this correlated with a 1.5-fold enhancement of its phosphotransferase activity with phosvitin as a substrate. CKII was not a substrate for the maturation-activated myelin basic protein kinase p44mpk from sea-star oocytes, nor for cyclic-AMP-dependent protein kinase. These studies point to possible regulation of CKII by protein phosphorylation. Images Fig. 2. Fig. 3. Fig. 4. Fig. 6. Fig. 7. PMID:1590772

  15. Mitogen-activated protein kinase and abscisic acid signal transduction.

    PubMed

    Heimovaara-Dijkstra, S; Testerink, C; Wang, M

    2000-01-01

    The phytohormone abscisic acid (ABA) is a classical plant hormone, responsible for regulation of abscission, diverse aspects of plant and seed development, stress responses and germination. It was found that ABA signal transduction in plants can involve the activity of type 2C-phosphatases (PP2C), calcium, potassium, pH and a transient activation of MAP kinase. The ABA signal transduction cascades have been shown to be tissue-specific, the transient activation of MAP kinase has until now only been found in barley aleurone cells. However, type 2C phosphatases are involved in the induction of most ABA responses, as shown by the PP2C-deficient abi-mutants. These phosphatases show high homology with phosphatases that regulate MAP kinase activity in yeast. In addition, the role of farnesyl transferase as a negative regulator of ABA responses also indicates towards involvement of MAP kinase in ABA signal transduction. Farnesyl transferase is known to regulate Ras proteins, Ras proteins in turn are known to regulate MAP kinase activation. Interestingly, Ras-like proteins were detected in barley aleurone cells. Further establishment of the involvement of MAP kinase in ABA signal transduction and its role therein, still awaits more study.

  16. SOS2-LIKE PROTEIN KINASE5, an SNF1-RELATED PROTEIN KINASE3-Type Protein Kinase, Is Important for Abscisic Acid Responses in Arabidopsis through Phosphorylation of ABSCISIC ACID-INSENSITIVE51[OPEN

    PubMed Central

    Zhou, Xiaona; Hao, Hongmei; Zhang, Yuguo; Bai, Yili; Zhu, Wenbo; Qin, Yunxia; Yuan, Feifei; Zhao, Feiyi; Wang, Mengyao; Hu, Jingjiang; Xu, Hong; Guo, Aiguang; Zhao, Huixian; Zhao, Yang; Cao, Cuiling; Yang, Yongqing; Schumaker, Karen S.; Guo, Yan; Xie, Chang Gen

    2015-01-01

    Abscisic acid (ABA) plays an essential role in seed germination. In this study, we demonstrate that one SNF1-RELATED PROTEIN KINASE3-type protein kinase, SOS2-LIKE PROTEIN KINASE5 (PKS5), is involved in ABA signal transduction via the phosphorylation of an interacting protein, ABSCISIC ACID-INSENSITIVE5 (ABI5). We found that pks5-3 and pks5-4, two previously identified PKS5 superactive kinase mutants with point mutations in the PKS5 FISL/NAF (a conserved peptide that is necessary for interaction with SOS3 or SOS3-LIKE CALCIUM BINDING PROTEINs) motif and the kinase domain, respectively, are hypersensitive to ABA during seed germination. PKS5 was found to interact with ABI5 in yeast (Saccharomyces cerevisiae), and this interaction was further confirmed in planta using bimolecular fluorescence complementation. Genetic studies revealed that ABI5 is epistatic to PKS5. PKS5 phosphorylates a serine (Ser) residue at position 42 in ABI5 and regulates ABA-responsive gene expression. This phosphorylation was induced by ABA in vivo and transactivated ABI5. Expression of ABI5, in which Ser-42 was mutated to alanine, could not fully rescue the ABA-insensitive phenotypes of the abi5-8 and pks5-4abi5-8 mutants. In contrast, mutating Ser-42 to aspartate rescued the ABA insensitivity of these mutants. These data demonstrate that PKS5-mediated phosphorylation of ABI5 at Ser-42 is critical for the ABA regulation of seed germination and gene expression in Arabidopsis (Arabidopsis thaliana). PMID:25858916

  17. Expression, purification and crystallization of a human tau-tubulin kinase 2 that phosphorylates tau protein

    SciTech Connect

    Kitano-Takahashi, Michiko; Morita, Hiroyuki; Kondo, Shin; Tomizawa, Kayoko; Kato, Ryohei; Tanio, Michikazu; Shirota, Yoshiko; Takahashi, Hiroshi; Sugio, Shigetoshi; Kohno, Toshiyuki

    2007-07-01

    The kinase domain (residues 1–331) of human tau-tubulin kinase 2 was expressed in insect cells, purified and crystallized. Diffraction data have been collected to 2.9 Å resolution. Tau-tubulin kinase 2 (TTBK2) is a Ser/Thr kinase that putatively phosphorylates residues Ser208 and Ser210 (numbered according to a 441-residue human tau isoform) in tau protein. Functional analyses revealed that a recombinant kinase domain (residues 1–331) of human TTBK2 expressed in insect cells with a baculovirus overexpression system retains kinase activity for tau protein. The kinase domain of TTBK2 was crystallized using the hanging-drop vapour-diffusion method. The crystals belong to space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 55.6, b = 113.7, c = 117.3 Å, α = β = γ = 90.0°. Diffraction data were collected to 2.9 Å resolution using synchrotron radiation at BL24XU of SPring-8.

  18. Feedback phosphorylation of an RGS protein by MAP kinase in yeast.

    PubMed

    Garrison, T R; Zhang, Y; Pausch, M; Apanovitch, D; Aebersold, R; Dohlman, H G

    1999-12-17

    Regulators of G protein signaling (RGS proteins) are well known to accelerate G protein GTPase activity in vitro and to promote G protein desensitization in vivo. Less is known about how RGS proteins are themselves regulated. To address this question we purified the RGS in yeast, Sst2, and used electrospray ionization mass spectrometry to identify post-translational modifications. This analysis revealed that Sst2 is phosphorylated at Ser-539 and that phosphorylation occurs in response to pheromone stimulation. Ser-539 lies within a consensus mitogen-activated protein (MAP) kinase phosphorylation site, Pro-X-Ser-Pro. Phosphorylation is blocked by mutations in the MAP kinase genes (FUS3, KSS1), as well as by mutations in components needed for MAP kinase activation (STE11, STE7, STE4, STE18). Phosphorylation is also blocked by replacing Ser-539 with Ala, Asp, or Glu (but not Thr). These point mutations do not alter pheromone sensitivity, as determined by growth arrest and reporter transcription assays. However, phosphorylation appears to slow the rate of Sst2 degradation. These findings indicate that the G protein-regulated MAP kinase in yeast can act as a feedback regulator of Sst2, itself a regulator of G protein signaling. PMID:10593933

  19. The molecular basis of targeting protein kinases in cancer therapeutics.

    PubMed

    Tsai, Chung-Jung; Nussinov, Ruth

    2013-08-01

    In this paper, we provide an overview of targeted anticancer therapies with small molecule kinase inhibitors. First, we discuss why a single constitutively active kinase emanating from a variety of aberrant genetic alterations is capable of transforming a normal cell, leading it to acquire the hallmarks of a cancer cell. To draw attention to the fact that kinase inhibition in targeted cancer therapeutics differs from conventional cytotoxic chemotherapy, we exploit a conceptual framework explaining why suppressed kinase activity will selectively kill only the so-called oncogene 'addicted' cancer cell, while sparing the healthy cell. Second, we introduce the protein kinase superfamily in light of its common active conformation with precisely positioned structural elements, and the diversified auto-inhibitory conformations among the kinase families. Understanding the detailed activation mechanism of individual kinases is essential to relate the observed oncogenic alterations to the elevated constitutively active state, to identify the mechanism of consequent drug resistance, and to guide the development of the next-generation inhibitors. To clarify the vital importance of structural guidelines in studies of oncogenesis, we explain how somatic mutations in EGFR result in kinase constitutive activation. Third, in addition to the common theme of secondary (acquired) mutations that prevent drug binding from blocking a signaling pathway which is hijacked by the aberrant activated kinase, we discuss scenarios of drug resistance and relapse by compensating lesions that bypass the inactivated pathway in a vertical or horizontal fashion. Collectively, these suggest that the future challenge of cancer therapy with small molecule kinase inhibitors will rely on the discovery of distinct combinations of optimized drugs to target individual subtypes of different cancers.

  20. PCTAIRE Kinase 3/Cyclin-dependent Kinase 18 Is Activated through Association with Cyclin A and/or Phosphorylation by Protein Kinase A*

    PubMed Central

    Matsuda, Shinya; Kominato, Kyohei; Koide-Yoshida, Shizuyo; Miyamoto, Kenji; Isshiki, Kinuka; Tsuji, Akihiko; Yuasa, Keizo

    2014-01-01

    PCTAIRE kinase 3 (PCTK3)/cyclin-dependent kinase 18 (CDK18) is an uncharacterized member of the CDK family because its activator(s) remains unidentified. Here we describe the mechanisms of catalytic activation of PCTK3 by cyclin A2 and cAMP-dependent protein kinase (PKA). Using a pulldown experiment with HEK293T cells, cyclin A2 and cyclin E1 were identified as proteins that interacted with PCTK3. An in vitro kinase assay using retinoblastoma protein as the substrate showed that PCTK3 was specifically activated by cyclin A2 but not by cyclin E1, although its activity was lower than that of CDK2. Furthermore, immunocytochemistry analysis showed that PCTK3 colocalized with cyclin A2 in the cytoplasm and regulated cyclin A2 stability. Amino acid sequence analysis revealed that PCTK3 contained four putative PKA phosphorylation sites. In vitro and in vivo kinase assays showed that PCTK3 was phosphorylated by PKA at Ser12, Ser66, and Ser109 and that PCTK3 activity significantly increased via phosphorylation at Ser12 by PKA even in the absence of cyclin A2. In the presence of cyclin A2, PCTK3 activity was comparable to CDK2 activity. We also found that PCTK3 knockdown in HEK293T cells induced polymerized actin accumulation in peripheral areas and cofilin phosphorylation. Taken together, our results provide the first evidence for the mechanisms of catalytic activation of PCTK3 by cyclin A2 and PKA and a physiological function of PCTK3. PMID:24831015

  1. Amino acid microsequencing of internal tryptic peptides of heme-regulated eukaryotic initiation factor 2 alpha subunit kinase: homology to protein kinases.

    PubMed Central

    Chen, J J; Pal, J K; Petryshyn, R; Kuo, I; Yang, J M; Throop, M S; Gehrke, L; London, I M

    1991-01-01

    We have purified the heme-regulated eukaryotic initiation factor 2 alpha subunit (eIF-2 alpha) kinase (HRI) from rabbit reticulocytes for amino acid microsequencing. This kinase is a single 92-kDa polypeptide and migrates in perfect alignment with 32P-labeled HRI on SDS/PAGE. Its functions of binding ATP and of autophosphorylation and eIF-2 alpha phosphorylation are inhibited by hemin. The amino acid sequences of three tryptic peptides of HRI have been obtained. A search of the data base of the National Biomedical Research Foundation reveals that these amino acid sequences are unique and that two of these three sequences show homology to protein kinases. HRI peptide P-52 contains Asp-Phe-Gly, which is the most highly conserved short stretch of amino acids in catalytic domain VII of protein kinases. HRI peptide P-74 contains the conserved amino acid residues Asp-(Met)-Tyr-Ser-(Val)-Gly-Val found in catalytic domain IX of protein kinases [Hanks, S. K., Quinn, A. M. & Hunter, T. (1988) Science 241, 42-52]. These findings are consistent with the autokinase and eIF-2 alpha kinase activities of HRI. Synthetic HRI peptide P-74 is a very potent inhibitor of eIF-2 alpha phosphorylation by HRI. Since little is known about the function of conserved domain IX, P-74 peptide may be useful in elucidating the role of this domain of protein kinases. Images PMID:1671169

  2. RNAi Screen Reveals an Abl Kinase-Dependent Host Cell Pathway Involved in Pseudomonas aeruginosa Internalization

    PubMed Central

    Pielage, Julia F.; Powell, Kimberly R.; Kalman, Daniel; Engel, Joanne N.

    2008-01-01

    Internalization of the pathogenic bacterium Pseudomonas aeruginosa by non-phagocytic cells is promoted by rearrangements of the actin cytoskeleton, but the host pathways usurped by this bacterium are not clearly understood. We used RNAi-mediated gene inactivation of ∼80 genes known to regulate the actin cytoskeleton in Drosophila S2 cells to identify host molecules essential for entry of P. aeruginosa. This work revealed Abl tyrosine kinase, the adaptor protein Crk, the small GTPases Rac1 and Cdc42, and p21-activated kinase as components of a host signaling pathway that leads to internalization of P. aeruginosa. Using a variety of complementary approaches, we validated the role of this pathway in mammalian cells. Remarkably, ExoS and ExoT, type III secreted toxins of P. aeruginosa, target this pathway by interfering with GTPase function and, in the case of ExoT, by abrogating P. aeruginosa–induced Abl-dependent Crk phosphorylation. Altogether, this work reveals that P. aeruginosa utilizes the Abl pathway for entering host cells and reveals unexpected complexity by which the P. aeruginosa type III secretion system modulates this internalization pathway. Our results furthermore demonstrate the applicability of using RNAi screens to identify host signaling cascades usurped by microbial pathogens that may be potential targets for novel therapies directed against treatment of antibiotic-resistant infections. PMID:18369477

  3. A membrane-anchored protein kinase involved in Brassica self-incompatibility signaling.

    PubMed

    Murase, Kohji; Shiba, Hiroshi; Iwano, Megumi; Che, Fang-Sik; Watanabe, Masao; Isogai, Akira; Takayama, Seiji

    2004-03-01

    Self-incompatibility (SI) response in Brassica is initiated by haplotype-specific interactions between the pollen-borne ligand S locus protein 11/SCR and its stigmatic S receptor kinase, SRK. This binding induces autophosphorylation of SRK, which is then thought to trigger a signaling cascade that leads to self-pollen rejection. A recessive mutation of the modifier (m) gene eliminates the SI response in stigma. Positional cloning of M has revealed that it encodes a membrane-anchored cytoplasmic serine/threonine protein kinase, designated M locus protein kinase (MLPK). Transient expression of MLPK restores the ability of mm papilla cells to reject self-pollen, suggesting that MLPK is a positive mediator of Brassica SI signaling.

  4. MAPK-Activated Protein Kinases (MKs): Novel Insights and Challenges.

    PubMed

    Gaestel, Matthias

    2015-01-01

    Downstream of MAPKs, such as classical/atypical ERKs and p38 MAPKs, but not of JNKs, signaling is often mediated by protein kinases which are phosphorylated and activated by MAPKs and, therefore, designated MAPK-activated protein kinases (MAPKAPKs). Recently, novel insights into the specificity of the assembly of MAPK/MAPKAPK hetero-dimeric protein kinase signaling complexes have been gained. In addition, new functional aspects of MKs have been described and established functions have been challenged. This short review will summarize recent developments including the linear motif (LM) in MKs, the ERK-independent activation of RSK, the RSK-independent effects of some RSK-inhibitors and the challenged role of MK5/PRAK in tumor suppression. PMID:26779481

  5. A novel Toxoplasma gondii calcium-dependent protein kinase.

    PubMed

    Tzen, M; Benarous, R; Dupouy-Camet, J; Roisin, M P

    2007-06-01

    Toxoplasma gondii is an obligate intracellular parasite that infects all types of cells in humans. A family of calcium-dependent protein kinases (CDPKs), previously identified as important in the development of plants and protists, was recently shown to play a role in the infectivity of apicomplexans, and in motility and host cell invasion in particular. We report here the isolation of a new calcium-dependent protein kinase gene from the human toxoplasmosis parasite, Toxoplasma gondii. The gene consists of 12 exons. The encoded protein, TgCDPK4, consists of the four characteristic domains of members of the CDPK family and is most similar to PfCDPK2 from Plasmodium falciparum. We measured TgCDPK4 activity, induced by calcium influx, using a kinase assay. A calcium chelator (EGTA) inhibited this activity. These findings provide evidence of signal transduction involving members of the CDPK family in T. gondii.

  6. Cyclic AMP-dependent protein kinase activity in Trypanosoma cruzi.

    PubMed Central

    Ulloa, R M; Mesri, E; Esteva, M; Torres, H N; Téllez-Iñón, M T

    1988-01-01

    A cyclic AMP-dependent protein kinase activity from epimastigote forms of Trypanosoma cruzi was characterized. Cytosolic extracts were chromatographed on DEAE-cellulose columns, giving two peaks of kinase activity, which were eluted at 0.15 M- and 0.32 M-NaCl respectively. The second activity peak was stimulated by nanomolar concentrations of cyclic AMP. In addition, a cyclic AMP-binding protein co-eluted with the second kinase activity peak. Cyclic AMP-dependent protein kinase activity was further purified by gel filtration, affinity chromatography on histone-agarose and cyclic AMP-agarose, as well as by chromatography on CM-Sephadex. The enzyme ('holoenzyme') could be partially dissociated into two different components: 'catalytic' and 'regulatory'. The 'regulatory' component had specific binding for cyclic AMP, and it inhibited phosphotransferase activity of the homologous 'catalytic component' or of the 'catalytic subunit' from bovine heart. Cyclic AMP reversed these inhibitions. A 'holoenzyme preparation' was phosphorylated in the absence of exogenous phosphate acceptor and analysed by polyacrylamide-gel electrophoresis. A 56 kDa band was phosphorylated. The same preparation was analysed by Western blotting, by using polyclonal antibodies to the regulatory subunits of protein kinases type I or II. Both antibodies reacted with the 56 kDa band. Images Fig. 7. Fig. 8. PMID:2848508

  7. Biochemical Screening of Five Protein Kinases from Plasmodium falciparum against 14,000 Cell-Active Compounds

    PubMed Central

    Crowther, Gregory J.; Hillesland, Heidi K.; Keyloun, Katelyn R.; Reid, Molly C.; Lafuente-Monasterio, Maria Jose; Ghidelli-Disse, Sonja; Leonard, Stephen E.; He, Panqing; Jones, Jackson C.; Krahn, Mallory M.; Mo, Jack S.; Dasari, Kartheek S.; Fox, Anna M. W.; Boesche, Markus; El Bakkouri, Majida; Rivas, Kasey L.; Leroy, Didier; Hui, Raymond; Drewes, Gerard; Maly, Dustin J.; Van Voorhis, Wesley C.; Ojo, Kayode K.

    2016-01-01

    In 2010 the identities of thousands of anti-Plasmodium compounds were released publicly to facilitate malaria drug development. Understanding these compounds’ mechanisms of action—i.e., the specific molecular targets by which they kill the parasite—would further facilitate the drug development process. Given that kinases are promising anti-malaria targets, we screened ~14,000 cell-active compounds for activity against five different protein kinases. Collections of cell-active compounds from GlaxoSmithKline (the ~13,000-compound Tres Cantos Antimalarial Set, or TCAMS), St. Jude Children’s Research Hospital (260 compounds), and the Medicines for Malaria Venture (the 400-compound Malaria Box) were screened in biochemical assays of Plasmodium falciparum calcium-dependent protein kinases 1 and 4 (CDPK1 and CDPK4), mitogen-associated protein kinase 2 (MAPK2/MAP2), protein kinase 6 (PK6), and protein kinase 7 (PK7). Novel potent inhibitors (IC50 < 1 μM) were discovered for three of the kinases: CDPK1, CDPK4, and PK6. The PK6 inhibitors are the most potent yet discovered for this enzyme and deserve further scrutiny. Additionally, kinome-wide competition assays revealed a compound that inhibits CDPK4 with few effects on ~150 human kinases, and several related compounds that inhibit CDPK1 and CDPK4 yet have limited cytotoxicity to human (HepG2) cells. Our data suggest that inhibiting multiple Plasmodium kinase targets without harming human cells is challenging but feasible. PMID:26934697

  8. Biochemical Screening of Five Protein Kinases from Plasmodium falciparum against 14,000 Cell-Active Compounds.

    PubMed

    Crowther, Gregory J; Hillesland, Heidi K; Keyloun, Katelyn R; Reid, Molly C; Lafuente-Monasterio, Maria Jose; Ghidelli-Disse, Sonja; Leonard, Stephen E; He, Panqing; Jones, Jackson C; Krahn, Mallory M; Mo, Jack S; Dasari, Kartheek S; Fox, Anna M W; Boesche, Markus; El Bakkouri, Majida; Rivas, Kasey L; Leroy, Didier; Hui, Raymond; Drewes, Gerard; Maly, Dustin J; Van Voorhis, Wesley C; Ojo, Kayode K

    2016-01-01

    In 2010 the identities of thousands of anti-Plasmodium compounds were released publicly to facilitate malaria drug development. Understanding these compounds' mechanisms of action--i.e., the specific molecular targets by which they kill the parasite--would further facilitate the drug development process. Given that kinases are promising anti-malaria targets, we screened ~14,000 cell-active compounds for activity against five different protein kinases. Collections of cell-active compounds from GlaxoSmithKline (the ~13,000-compound Tres Cantos Antimalarial Set, or TCAMS), St. Jude Children's Research Hospital (260 compounds), and the Medicines for Malaria Venture (the 400-compound Malaria Box) were screened in biochemical assays of Plasmodium falciparum calcium-dependent protein kinases 1 and 4 (CDPK1 and CDPK4), mitogen-associated protein kinase 2 (MAPK2/MAP2), protein kinase 6 (PK6), and protein kinase 7 (PK7). Novel potent inhibitors (IC50 < 1 μM) were discovered for three of the kinases: CDPK1, CDPK4, and PK6. The PK6 inhibitors are the most potent yet discovered for this enzyme and deserve further scrutiny. Additionally, kinome-wide competition assays revealed a compound that inhibits CDPK4 with few effects on ~150 human kinases, and several related compounds that inhibit CDPK1 and CDPK4 yet have limited cytotoxicity to human (HepG2) cells. Our data suggest that inhibiting multiple Plasmodium kinase targets without harming human cells is challenging but feasible. PMID:26934697

  9. Immunological evidence for two physiological forms of protein kinase C.

    PubMed Central

    Woodgett, J R; Hunter, T

    1987-01-01

    Our recently described purification scheme for rat brain protein kinase C yields an enzyme consisting of a 78/80-kilodalton (kDa) doublet upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis (submitted for publication). Antisera against this preparation were raised in two rabbits. One of the antisera detected only the 80-kDa component by immunoblotting of purified protein kinase C and immunoprecipitated an 80-kDa [35S]methionine-labeled protein from a variety of human, rodent, and bovine cells, which was shown to represent protein kinase C by comparative one-dimensional peptide mapping. In contrast, the second antiserum detected both 78- and 80-kDa enzyme forms by immunoblotting and immunoprecipitated a [35S]methionine-labeled 78/80-kDa doublet from mammalian cells. One-dimensional peptide maps of these 78- and 80-kDa proteins were similar to those derived from the 78- and 80-kDa forms of purified protein kinase C, respectively. The two forms were not related by either partial proteolysis or differential phosphorylation, showing that two distinct forms of this enzyme exist in mammalian cells. Treatment of mouse B82 L cells with 2.5 micrograms of 12-O-tetradecanoylphorbol-13-acetate (TPA) per ml for 18 h resulted in complete loss of immunoprecipitable protein kinase C with a half time of disappearance of 48 min. Since the normal half-life of protein kinase C was greater than 24 h and the biosynthetic rate of the protein was not decreased after 18 h by TPA treatment, TPA induces down-regulation by increasing the degradation rate of the enzyme. Treatment of cells with 50 ng of TPA per ml followed by resolution of the membrane and cytosol in the presence of ethylene glycol-bis(beta-aminoethyl ether)N,N,N',N'-tetraacetic acid (EGTA) promoted an apparent translocation of both 78- and 80-kDa proteins from the cytosol to the membrane fraction. A similar translocation was effected by cell lysis in the presence of Ca2+, indicating the subcellular localization of

  10. Solution structure of the cAMP-dependent protein kinase

    SciTech Connect

    Trewhella, J.; Olah, G.A.; Walsh, D.A.; Mitchell, R.D.

    1998-12-31

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project as Los Alamos National Laboratory (LANL). Protein phosphorylation is well established as one of the most important mechanisms of signal transduction and cellular regulation. Two of the key enzymes that catalyze these phosphorylation reactions are the cAMP- (PKA) and cGMP- (PKG) dependent protein kinases. PKA has served as the prototypic model of this class of enzymes that now comprises in excess of 300 phylogenetically related proteins. A large number of these protein kinases are critical for the regulation of cell function and a full analysis of their similarities and differences is essential to understand their diverse physiological roles. The cAMP-dependent protein kinase has the subunit structure R2C2, in which C and R refer to the catalytic and regulatory subunits, respectively. The cGMP-dependent protein kinase (PKG) is highly homologous to PKA but is distinguished from it by having the regulatory and catalytic domains on a contiguous polypeptide. The studies described here use small-angle scattering and Fourier Transform InfraRed (FTIR) spectroscopy to study domain movements and conformational changes in these enzymes in different functional states in order to elucidate the molecular bases for the regulation of their activities.

  11. Ethanol increases affinity of protein kinase C for phosphatidylserine

    SciTech Connect

    Chin, J.H.

    1986-03-01

    Protein kinase C is a calcium-dependent enzyme that requires phospholipid for its activation. It is present in relatively high concentration in the brain and may be involved in neuronal function. The present experiments test whether the membrane disorder induced by ethanol affects the activity of kinase C by changing its interaction with membrane lipid. Fractions rich in kinase C were purified from rat brain cytosol by DEAE-cellulose chromatography and Sephadex G-200 gel filtration. Enzyme activity was assayed by measuring the phosphorylation of histone H1. As expected, phosphatidylserine activated the enzyme, and the stimulation was further increased by the addition of calcium and/or diacylglycerol. At low concentration of free calcium (0.5-1..mu..M), ethanol (800 mM0 enhanced kinase C activity if the presence of phospholipid. similar results were observed in the absence of calcium. Double reciprocal plots of the data showed that ethanol increased the affinity of the enzyme for phosphatidylserine without affecting the V/sub max. The stimulation of kinase C activity by ethanol was not observed at high calcium concentrations. These experiments suggest that ethanol may activated protein kinase C at physiological levels of calcium by facilitating its transfer into the hydrophobic membrane environment.

  12. The Roles of NDR Protein Kinases in Hippo Signalling

    PubMed Central

    Hergovich, Alexander

    2016-01-01

    The Hippo tumour suppressor pathway has emerged as a critical regulator of tissue growth through controlling cellular processes such as cell proliferation, death, differentiation and stemness. Traditionally, the core cassette of the Hippo pathway includes the MST1/2 protein kinases, the LATS1/2 protein kinases, and the MOB1 scaffold signal transducer, which together regulate the transcriptional co-activator functions of the proto-oncoproteins YAP and TAZ through LATS1/2-mediated phosphorylation of YAP/TAZ. Recent research has identified additional kinases, such as NDR1/2 (also known as STK38/STK38L) and MAP4Ks, which should be considered as novel members of the Hippo core cassette. While these efforts helped to expand our understanding of Hippo core signalling, they also began to provide insights into the complexity and redundancy of the Hippo signalling network. Here, we focus on summarising our current knowledge of the regulation and functions of mammalian NDR kinases, discussing parallels between the NDR pathways in Drosophila and mammals. Initially, we provide a general overview of the cellular functions of NDR kinases in cell cycle progression, centrosome biology, apoptosis, autophagy, DNA damage signalling, immunology and neurobiology. Finally, we put particular emphasis on discussing NDR1/2 as YAP kinases downstream of MST1/2 and MOB1 signalling in Hippo signalling. PMID:27213455

  13. Role of Protein Kinase C, PI3-kinase and Tyrosine Kinase in Activation of MAP Kinase by Glucose and Agonists of G-protein Coupled Receptors in INS-1 Cells

    PubMed Central

    Böcker, Dietmar

    2001-01-01

    MAP (mitogen-activated protein) kinase (also called Erk 1/2) plays a crucial role in cell proliferation and differentiation. Its impact on secretory events is less well established. The interplay of protein kinase C (PKC), PI3-kinase nd cellular tyrosine kinase with MAP kinase activity using inhibitors and compounds such as glucose, phorbol 12-myristate 13-acetate (PMA) and agonists of G-protein coupled receptors like gastrin releasing peptide (GRP), oxytocin (OT) and glucose-dependent insulinotropic peptide (GIP) was investigated in INS-1 cells, an insulin secreting cell line. MAP kinase activity was determined by using a peptide derived from the EGF receptor as a MAP kinase substrate and [ P 32 ]ATP. Glucose as well as GRP, OT and GIP exhibited a time-dependent increase in MAP kinase activity with a maximum at time point 2.5 min. All further experiments were performed using 2.5 min incubations. The flavone PD 098059 is known to bind to the inactive forms of MEK1 (MAPK/ERK-Kinase) thus preventing activation by upstream activators. 20 μM PD 098059 ( IC 50 =51 μM) inhibited MAP kinase stimulated by either glucose, GRP, OT, GIP or PMA. Inhibiton (“downregulation”) of PKC by a long term (22h) pretreatment with 1 μM PMA did not influence MAP kinase activity when augmented by either of the above mentioned compound. To investigate whether PI3-kinase and cellular tyrosine kinase are involved in G-protein mediated effects on MAP kinase, inhibitors were used: 100 nM wortmannin (PI3-kinase inhibitor) reduced the effects of GRP, OT and GIP but not that of PMA; 100 μM genistein (tyrosine kinase inhibitor) inhibited the stimulatory effect of either above mentioned compound on MAP kinase activation. Inhibition of MAP kinase by 20 μM PD 098059 did not influence insulin secretion modulated by either compound (glucose, GRP, OT or GIP). [ H 3 ]Thymidine incorporation, however, was severely inhibited by PD 098059. Thus MAP kinase is important for INS-1 cell proliferation but

  14. Structure-Based Design of an Organoruthenium Phosphatidyl-inositol-3-Kinase Inhibitor Reveals a Switch Governing Lipid Kinase Potency and Selectivity

    SciTech Connect

    Xie,P.; Williams, D.; Atilla-Gokcumen, G.; Milk, L.; Xiao, M.; Smalley, K.; Herlyn, M.; Meggers, E.; Marmorstein, R.

    2008-01-01

    Mutations that constitutively activate the phosphatidyl-inositol-3-kinase (PI3K) signaling pathway, including alterations in PI3K, PTEN, and AKT, are found in a variety of human cancers, implicating the PI3K lipid kinase as an attractive target for the development of therapeutic agents to treat cancer and other related diseases. In this study, we report on the combination of a novel organometallic kinase inhibitor scaffold with structure-based design to develop a PI3K inhibitor, called E5E2, with an IC50 potency in the mid-low-nanomolar range and selectivity against a panel of protein kinases. We also show that E5E2 inhibits phospho-AKT in human melanoma cells and leads to growth inhibition. Consistent with a role for the PI3K pathway in tumor cell invasion, E5E2 treatment also inhibits the migration of melanoma cells in a 3D spheroid assay. The structure of the PI3K?/E5E2 complex reveals the molecular features that give rise to this potency and selectivity toward lipid kinases with implications for the design of a subsequent generation of PI3K-isoform-specific organometallic inhibitors.

  15. ATM kinase: Much more than a DNA damage responsive protein.

    PubMed

    Guleria, Ayushi; Chandna, Sudhir

    2016-03-01

    ATM, mutation of which causes Ataxia telangiectasia, has emerged as a cardinal multifunctional protein kinase during past two decades as evidenced by various studies from around the globe. Further to its well established and predominant role in DNA damage response, ATM has also been understood to help in maintaining overall functional integrity of cells; since its mutation, inactivation or deficiency results in a variety of pathological manifestations besides DNA damage. These include oxidative stress, metabolic syndrome, mitochondrial dysfunction as well as neurodegeneration. Recently, high throughput screening using proteomics, metabolomics and transcriptomic studies revealed several proteins which might be acting as substrates of ATM. Studies that can help in identifying effective regulatory controls within the ATM-mediated pathways/mechanisms can help in developing better therapeutics. In fact, more in-depth understanding of ATM-dependent cellular signals could also help in the treatment of variety of other disease conditions since these pathways seem to control many critical cellular functions. In this review, we have attempted to put together a detailed yet lucid picture of the present-day understanding of ATM's role in various pathophysiological conditions involving DNA damage and beyond.

  16. Protein kinase Czeta mediated Raf-1/extracellular-regulated kinase activation by daunorubicin.

    PubMed

    Mas, Véronique Mansat-De; Hernandez, Hélène; Plo, Isabelle; Bezombes, Christine; Maestre, Nicolas; Quillet-Mary, Anne; Filomenko, Rodolphe; Demur, Cécile; Jaffrézou, Jean-Pierre; Laurent, Guy

    2003-02-15

    In light of the emerging concept of a protective function of the mitogen-activated protein kinase (MAPK) pathway under stress conditions, we investigated the influence of the anthracycline daunorubicin (DNR) on MAPK signaling and its possible contribution to DNR-induced cytotoxicity. We show that DNR increased phosphorylation of extracellular-regulated kinases (ERKs) and stimulated activities of both Raf-1 and extracellular-regulated kinase 1 (ERK1) within 10 to 30 minutes in U937 cells. ERK1 stimulation was completely blocked by either the mitogen-induced extracellular kinase (MEK) inhibitor PD98059 or the Raf-1 inhibitor 8-bromo-cAMP (cyclic adenosine monophosphate). However, only partial inhibition of Raf-1 and ERK1 stimulation was observed with the antioxidant N-acetylcysteine (N-Ac). Moreover, the xanthogenate compound D609 that inhibits DNR-induced phosphatidylcholine (PC) hydrolysis and subsequent diacylglycerol (DAG) production, as well as wortmannin that blocks phosphoinositide-3 kinase (PI3K) stimulation, only partially inhibited Raf-1 and ERK1 stimulation. We also observed that DNR stimulated protein kinase C zeta (PKCzeta), an atypical PKC isoform, and that both D609 and wortmannin significantly inhibited DNR-triggered PKCzeta activation. Finally, we found that the expression of PKCzeta kinase-defective mutant resulted in the abrogation of DNR-induced ERK phosphorylation. Altogether, these results demonstrate that DNR activates the classical Raf-1/MEK/ERK pathway and that Raf-1 activation is mediated through complex signaling pathways that involve at least 2 contributors: PC-derived DAG and PI3K products that converge toward PKCzeta. Moreover, we show that both Raf-1 and MEK inhibitors, as well as PKCzeta inhibition, sensitized cells to DNR-induced cytotoxicity.

  17. Unveiling Protein Kinase A Targets in Cryptococcus neoformans Capsule Formation.

    PubMed

    Alspaugh, J Andrew

    2016-01-01

    The protein kinase A (PKA) signal transduction pathway has been associated with pathogenesis in many fungal species. Geddes and colleagues [mBio 7(1):e01862-15, 2016, doi:10.1128/mBio.01862-15] used quantitative proteomics approaches to define proteins with altered abundance during protein kinase A (PKA) activation and repression in the opportunistic human fungal pathogen Cryptococcus neoformans. They observed an association between microbial PKA signaling and ubiquitin-proteasome regulation of protein homeostasis. Additionally, they correlated these processes with expression of polysaccharide capsule on the fungal cell surface, the main virulence-associated phenotype in this organism. Not only are their findings important for microbial pathogenesis, but they also support similar associations between human PKA signaling and ubiquitinated protein accumulation in neurodegenerative diseases. PMID:26861014

  18. Unveiling Protein Kinase A Targets in Cryptococcus neoformans Capsule Formation

    PubMed Central

    2016-01-01

    ABSTRACT The protein kinase A (PKA) signal transduction pathway has been associated with pathogenesis in many fungal species. Geddes and colleagues [mBio 7(1):e01862-15, 2016, doi:10.1128/mBio.01862-15] used quantitative proteomics approaches to define proteins with altered abundance during protein kinase A (PKA) activation and repression in the opportunistic human fungal pathogen Cryptococcus neoformans. They observed an association between microbial PKA signaling and ubiquitin-proteasome regulation of protein homeostasis. Additionally, they correlated these processes with expression of polysaccharide capsule on the fungal cell surface, the main virulence-associated phenotype in this organism. Not only are their findings important for microbial pathogenesis, but they also support similar associations between human PKA signaling and ubiquitinated protein accumulation in neurodegenerative diseases. PMID:26861014

  19. Targeting protein kinase A in cancer therapy: an update

    PubMed Central

    Sapio, Luigi; Di Maiolo, Francesca; Illiano, Michela; Esposito, Antonietta; Chiosi, Emilio; Spina, Annamaria; Naviglio, Silvio

    2014-01-01

    Protein Kinase A (PKA) is a well known member of the serine-threonin protein kinase superfamily. PKA, also known as cAMP-dependent protein kinase, is a multi-unit protein kinase that mediates signal transduction of G-protein coupled receptors through its activation upon cAMP binding. The widespread expression of PKA subunit genes, and the myriad of mechanisms by which cAMP is regulated within a cell suggest that PKA signaling is one of extreme importance to cellular function. It is involved in the control of a wide variety of cellular processes from metabolism to ion channel activation, cell growth and differentiation, gene expression and apoptosis. Importantly, since it has been implicated in the initiation and progression of many tumors, PKA has been proposed as a novel biomarker for cancer detection, and as a potential molecular target for cancer therapy. Here, we highlight some features of cAMP/PKA signaling that are relevant to cancer biology and present an update on targeting PKA in cancer therapy. PMID:26417307

  20. Regulation of protein kinase B/Akt activity and Ser473 phosphorylation by protein kinase Calpha in endothelial cells.

    PubMed

    Partovian, Chohreh; Simons, Michael

    2004-08-01

    Protein kinase Balpha (PKBalpha/Akt-1) is a key mediator of multiple signaling pathways involved in angiogenesis, cell proliferation and apoptosis among others. The unphosphorylated form of Akt-1 is virtually inactive and its full activation requires two phosphatidylinositol-3,4,5-triphosphate-dependent phosphorylation events, Thr308 by 3-phosphoinositide-dependent kinase-1 (PDK1) and Ser473 by an undefined kinase that has been termed PDK2. Recent studies have suggested that the Ser473 kinase is a plasma membrane raft-associated kinase. In this study we show that protein kinase Calpha (PKCalpha) translocates to the membrane rafts in response to insulin growth factor-1 (IGF-1) stimulation. Overexpression of PKCalpha increases Ser473 phosphorylation and Akt-1 activity, while inhibition of its activity or expression decreases IGF-1-dependent activation of Akt-1. Furthermore, in vitro, in the presence of phospholipids and calcium, PKCalpha directly phosphorylates Akt-1 at the Ser473 site. We conclude, therefore, that PKCalpha regulates Akt-1 activity via Ser473 phosphorylation and may function as PDK2 in endothelial cells. PMID:15157674

  1. Smooth-muscle mitogen-activated protein (MAP) kinase: purification and characterization, and the phosphorylation of caldesmon.

    PubMed Central

    Childs, T J; Mak, A S

    1993-01-01

    A single 42 kDa isoform of mitogen-activated protein (MAP) kinase is expressed in both embryonic and adult chicken gizzard. The gizzard MAP kinase, which cross-reacts with anti-p44mpk antibody, has been purified from adult chicken gizzard and partially characterized. The purification protocol employs phenyl-Sepharose, polylysine-agarose, hydroxyapatite, Mono-Q and phenyl-Superose column chromatography. The purified enzyme phosphorylates myelin basic protein and gizzard high-molecular-mass (h-)caldesmon. Sea-star p44mpk and gizzard MAP kinase phosphorylate h-caldesmon at identical sites at the C-terminal domain, as revealed by tryptic-peptide mapping of the phosphorylated protein. Phosphorylation of h-caldesmon by gizzard MAP kinase abolishes its interaction with polymerized tubulin. The specific activity of the purified gizzard kinase toward myelin basic protein is similar to that of brain tau kinase, but is only a fraction of that of activated sea-star p44mpk. This suggests that, although a large amount of MAP kinase is present in the gizzard, only a small percentage of the enzyme is activated normally. Autophosphorylation of the gizzard kinase, at least in part on tyrosine residues, activates its kinase activity. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 6 PMID:8280072

  2. Analysis of mitogen-activated protein kinase activity in yeast.

    PubMed

    Elion, Elaine A; Sahoo, Rupam

    2010-01-01

    Mitogen-activated protein (MAP) kinases play central roles in transmitting extracellular and intracellular information in a wide variety of situations in eukaryotic cells. Their activities are perturbed in a large number of diseases, and their activating kinases are currently therapeutic targets in cancer. MAPKs are highly conserved among all eukaryotes. MAPKs were first cloned from the yeast Saccharomyces cerevisiae. Yeast has five MAPKs and one MAPK-like kinase. The mating MAPK Fus3 is the best characterized yeast MAPK. Members of all subfamilies of human MAPKs can functionally substitute S. cerevisiae MAPKs, providing systems to use genetic approaches to study the functions of either yeast or human MAPKs and to identify functionally relevant amino acid residues that enhance or reduce the effects of therapeutically relevant inhibitors and regulatory proteins. Here, we describe an assay to measure Fus3 activity in immune complexes prepared from S. cerevisiae extracts. The assay conditions are applicable to other MAPKs, as well. PMID:20811996

  3. Microfluidic IEF technique for sequential phosphorylation analysis of protein kinases

    NASA Astrophysics Data System (ADS)

    Choi, Nakchul; Song, Simon; Choi, Hoseok; Lim, Bu-Taek; Kim, Young-Pil

    2015-11-01

    Sequential phosphorylation of protein kinases play the important role in signal transduction, protein regulation, and metabolism in living cells. The analysis of these phosphorylation cascades will provide new insights into their physiological functions in many biological functions. Unfortunately, the existing methods are limited to analyze the cascade activity. Therefore, we suggest a microfluidic isoelectric focusing technique (μIEF) for the analysis of the cascade activity. Using the technique, we show that the sequential phosphorylation of a peptide by two different kinases can be successfully detected on a microfluidic chip. In addition, the inhibition assay for kinase activity and the analysis on a real sample have also been conducted. The results indicate that μIEF is an excellent means for studies on phosphorylation cascade activity.

  4. The FRK1 mitogen-activated protein kinase kinase kinase (MAPKKK) from Solanum chacoense is involved in embryo sac and pollen development.

    PubMed

    Lafleur, Edith; Kapfer, Christelle; Joly, Valentin; Liu, Yang; Tebbji, Faiza; Daigle, Caroline; Gray-Mitsumune, Madoka; Cappadocia, Mario; Nantel, André; Matton, Daniel P

    2015-04-01

    The fertilization-related kinase 1 (ScFRK1), a nuclear-localized mitogen-activated protein kinase kinase kinase (MAPKKK) from the wild potato species Solanum chacoense, belongs to a small group of pMEKKs that do not possess an extended N- or C-terminal regulatory domain. Initially selected based on its highly specific expression profile following fertilization, in situ expression analyses revealed that the ScFRK1 gene is also expressed early on during female gametophyte development in the integument and megaspore mother cell and, later, in the synergid and egg cells of the embryo sac. ScFRK1 mRNAs are also detected in pollen mother cells. Transgenic plants with lower or barely detectable levels of ScFRK1 mRNAs lead to the production of small fruits with severely reduced seed set, resulting from a concomitant decline in the number of normal embryo sacs produced. Megagametogenesis and microgametogenesis were affected, as megaspores did not progress beyond the functional megaspore (FG1) stage and the microspore collapsed around the first pollen mitosis. As for other mutants that affect embryo sac development, pollen tube guidance was severely affected in the ScFRK1 transgenic lines. Gametophyte to sporophyte communication was also affected, as observed from a marked change in the transcriptomic profiles of the sporophytic tissues of the ovule. The ScFRK1 MAPKKK is thus involved in a signalling cascade that regulates both male and female gamete development. PMID:25576576

  5. Rapamycin induces mitogen-activated protein (MAP) kinase phosphatase-1 (MKP-1) expression through activation of protein kinase B and mitogen-activated protein kinase kinase pathways.

    PubMed

    Rastogi, Ruchi; Jiang, Zhongliang; Ahmad, Nisar; Rosati, Rita; Liu, Yusen; Beuret, Laurent; Monks, Robert; Charron, Jean; Birnbaum, Morris J; Samavati, Lobelia

    2013-11-22

    Mitogen-activated protein kinase phosphatase-1 (MKP-1), also known as dual specificity phosphatase-1 (DUSP-1), plays a crucial role in the deactivation of MAPKs. Several drugs with immune-suppressive properties modulate MKP-1 expression as part of their mechanism of action. We investigated the effect of mTOR inhibition through rapamycin and a dual mTOR inhibitor (AZD2014) on MKP-1 expression. Low dose rapamycin led to a rapid activation of both AKT and ERK pathways with a subsequent increase in MKP-1 expression. Rapamycin treatment led to phosphorylation of CREB, transcription factor 1 (ATF1), and ATF2, three transcription factors that bind to the cyclic AMP-responsive elements on the Mkp-1 promoter. Inhibition of either the MEK/ERK or the AKT pathway attenuated rapamycin-mediated MKP-1 induction. AZD2014 did not activate AKT but activated the ERK pathway, leading to a moderate MKP-1 induction. Using bone marrow-derived macrophages (BMDMs) derived from wild-type (WT) mice or mice deficient in AKT1 and AKT2 isoforms or BMDM from targeted deficiency in MEK1 and MEK2, we show that rapamycin treatment led to an increased MKP1 expression in BMDM from WT but failed to do so in BMDMs lacking the AKT1 isoform or MEK1 and MEK2. Importantly, rapamycin pretreatment inhibited LPS-mediated p38 activation and decreased nitric oxide and IL-6 production. Our work provides a conceptual framework for the observed immune modulatory effect of mTOR inhibition.

  6. HRR25, a putative protein kinase from budding yeast: Association with repair of damaged DNA

    SciTech Connect

    Hoekstra, M.F.; Ou, A.C.; DeMaggio, A.J.; Burbee, D.G. ); Liskay, R.M. ); Heffron, F. )

    1991-08-30

    In simple eukaryotes, protein kinases regulate mitotic and meiotic cell cycles, the response to polypeptide pheromones, and the initiation of nuclear DNA synthesis. The protein HRR25 from the budding yeast Saccharomyces cerevisiae was defined by the mutation hrr25-1. This mutation resulted in sensitivity to continuous expression of the HO double-strand endonuclease, to methyl methanesulfonate, and to x-irradiation. Homozygotes of hrr25-1 were unable to sporulate and disruption and deletion of HRR25 interfered with mitotic and meiotic cell division. Sequence analysis revealed two distinctive regions in the protein. The NH{sub 2}-terminus of HRR25 contains the hallmark features of protein kinases, whereas the COOH-terminus is rich in proline and glutamine. Mutations in HRR25 at conserved residues found in all protein kinases inactivated the gene, and these mutants exhibited the hrr25 null phenotypes. Taken together, the hrr25 mutant phenotypes and the features of the gene product indicate that HRR25 is a distinctive member of the protein kinase superfamily.

  7. Involvement of Protein Kinase D1 in Signal Transduction from the Protein Kinase C Pathway to the Tyrosine Kinase Pathway in Response to Gonadotropin-releasing Hormone*

    PubMed Central

    Higa-Nakamine, Sayomi; Maeda, Noriko; Toku, Seikichi; Yamamoto, Hideyuki

    2015-01-01

    The receptor for gonadotropin-releasing hormone (GnRH) belongs to the G protein-coupled receptors (GPCRs), and its stimulation activates extracellular signal-regulated protein kinase (ERK). We found that the transactivation of ErbB4 was involved in GnRH-induced ERK activation in immortalized GnRH neurons (GT1–7 cells). We found also that GnRH induced the cleavage of ErbB4. In the present study, we examined signal transduction for the activation of ERK and the cleavage of ErbB4 after GnRH treatment. Both ERK activation and ErbB4 cleavage were completely inhibited by YM-254890, an inhibitor of Gq/11 proteins. Down-regulation of protein kinase C (PKC) markedly decreased both ERK activation and ErbB4 cleavage. Experiments with two types of PKC inhibitors, Gö 6976 and bisindolylmaleimide I, indicated that novel PKC isoforms but not conventional PKC isoforms were involved in ERK activation and ErbB4 cleavage. Our experiments indicated that the novel PKC isoforms activated protein kinase D (PKD) after GnRH treatment. Knockdown and inhibitor experiments suggested that PKD1 stimulated the phosphorylation of Pyk2 by constitutively activated Src and Fyn for ERK activation. Taken together, it is highly possible that PKD1 plays a critical role in signal transduction from the PKC pathway to the tyrosine kinase pathway. Activation of the tyrosine kinase pathway may be involved in the progression of cancer. PMID:26338704

  8. Mitogen-Activated Protein Kinases and Mitogen Kinase Phosphatase 1: A Critical Interplay in Macrophage Biology

    PubMed Central

    Lloberas, Jorge; Valverde-Estrella, Lorena; Tur, Juan; Vico, Tania; Celada, Antonio

    2016-01-01

    Macrophages are necessary in multiple processes during the immune response or inflammation. This review emphasizes the critical role of the mitogen-activated protein kinases (MAPKs) and mitogen kinase phosphatase-1 (MKP-1) in the functional activities of macrophages. While the phosphorylation of MAPKs is required for macrophage activation or proliferation, MKP-1 dephosphorylates these kinases, thus playing a balancing role in the control of macrophage behavior. MKP-1 is a nuclear-localized dual-specificity phosphatase whose expression is regulated at multiple levels, including at the transcriptional and post-transcriptional level. The regulatory role of MKP-1 in the interplay between MAPK phosphorylation/dephosphorylation makes this molecule a critical regulator of macrophage biology and inflammation. PMID:27446931

  9. Mitogen-Activated Protein Kinases and Mitogen Kinase Phosphatase 1: A Critical Interplay in Macrophage Biology.

    PubMed

    Lloberas, Jorge; Valverde-Estrella, Lorena; Tur, Juan; Vico, Tania; Celada, Antonio

    2016-01-01

    Macrophages are necessary in multiple processes during the immune response or inflammation. This review emphasizes the critical role of the mitogen-activated protein kinases (MAPKs) and mitogen kinase phosphatase-1 (MKP-1) in the functional activities of macrophages. While the phosphorylation of MAPKs is required for macrophage activation or proliferation, MKP-1 dephosphorylates these kinases, thus playing a balancing role in the control of macrophage behavior. MKP-1 is a nuclear-localized dual-specificity phosphatase whose expression is regulated at multiple levels, including at the transcriptional and post-transcriptional level. The regulatory role of MKP-1 in the interplay between MAPK phosphorylation/dephosphorylation makes this molecule a critical regulator of macrophage biology and inflammation. PMID:27446931

  10. Glucagon receptor activates extracellular signal-regulated protein kinase 1/2 via cAMP-dependent protein kinase

    PubMed Central

    Jiang, Youwei; Cypess, Aaron M.; Muse, Evan D.; Wu, Cui-Rong; Unson, Cecilia G.; Merrifield, R. B.; Sakmar, Thomas P.

    2001-01-01

    We prepared a stable cell line expressing the glucagon receptor to characterize the effect of Gs-coupled receptor stimulation on extracellular signal-regulated protein kinase 1/2 (ERK1/2) activity. Glucagon treatment of the cell line caused a dose-dependent increase in cAMP concentration, activation of cAMP-dependent protein kinase (PKA), and transient release of intracellular calcium. Glucagon treatment also caused rapid dose-dependent phosphorylation and activation of mitogen-activated protein kinase kinase/ERK kinase (MEK1/2) and ERK1/2. Inhibition of either PKA or MEK1/2 blocked ERK1/2 activation by glucagon. However, no significant activation of several upstream activators of MEK, including Ras, Rap1, and Raf, was observed in response to glucagon treatment. In addition, chelation of intracellular calcium reduced glucagon-mediated ERK1/2 activation. In transient transfection experiments, glucagon receptor mutants that bound glucagon but failed to increase intracellular cAMP and calcium concentrations showed no glucagon-stimulated ERK1/2 phosphorylation. We conclude that glucagon-induced MEK1/2 and ERK1/2 activation is mediated by PKA and that an increase in intracellular calcium concentration is required for maximal ERK activation. PMID:11517300

  11. Isoform Specificity of Protein Kinase Cs in Synaptic Plasticity

    ERIC Educational Resources Information Center

    Sossin, Wayne S.

    2007-01-01

    Protein kinase Cs (PKCs) are implicated in many forms of synaptic plasticity. However, the specific isoform(s) of PKC that underlie(s) these events are often not known. We have used "Aplysia" as a model system in order to investigate the isoform specificity of PKC actions due to the presence of fewer isoforms and a large number of documented…

  12. Regulation of cholesterol esterification by protein kinase C

    SciTech Connect

    Jeng, I.; Dills, C.; Klemm, N.; Wu, C.

    1986-03-05

    They have recently identified acyl-CoA cholesterol acyltransferase as the key enzyme for cholesterol esterification in the central nervous system. They found that the activity of glial acyl-CoA cholesterol acyltransferase could be controlled by a phosphorylation-dephosphorylation mechanism. However, repeated attempts to identify cyclic AMP as the bioregulator for this reaction failed. Recently, they have studied the possible involvement of protein kinase C in the regulation of glial cholesterol esterification. Phorbol-12-myristate 13-acetate (PMA) can activate cellular cholesterol esterification in a complex, time-dependent manner. Phorbol analogues inactive toward protein kinase C are also ineffective in this assay. Furthermore, oleoyl-acetyl-glycerol mimics the effect of PMA, confirming the proposal that protein kinase C mediates the effect of these compounds and that the natural bioregulator is probably diacylglycerol. Receptor-mediated polyphosphatidyl-inositol cleavage often produces diacylglycerol and inositol triphosphate. The synergic effects of these two compounds are known to be necessary to elicit other biological responses. Their preliminary studies using calcium ionophore A23187 indicates that Ca/sup + +/ is not required for cellular cholesterol esterification. In sum, glial cholesterol esterification is probably regulated by a calcium-independent and protein kinase C-dependent reaction.

  13. Activation of Protein Kinase C-α and Src Kinase Increases Urea Transporter A1 α-2, 6 Sialylation

    PubMed Central

    Li, Xuechen; Yang, Baoxue; Chen, Minguang; Klein, Janet D.; Sands, Jeff M.

    2015-01-01

    The urea transporter A1 (UT-A1) is a glycosylated protein with two glycoforms: 117 and 97 kD. In diabetes, the increased abundance of the heavily glycosylated 117-kD UT-A1 corresponds to an increase of kidney tubule urea permeability. We previously reported that diabetes not only causes an increase of UT-A1 protein abundance but also, results in UT-A1 glycan changes, including an increase of sialic acid content. Because activation of the diacylglycerol (DAG)-protein kinase C (PKC) pathway is elevated in diabetes and PKC-α regulates UT-A1 urea transport activity, we explored the role of PKC in UT-A1 glycan sialylation. We found that activation of PKC specifically promotes UT-A1 glycan sialylation in both UT-A1-MDCK cells and rat kidney inner medullary collecting duct suspensions, and inhibition of PKC activity blocks high glucose-induced UT-A1 sialylation. Overexpression of PKC-α promoted UT-A1 sialylation and membrane surface expression. Conversely, PKC-α–deficient mice had significantly less sialylated UT-A1 compared with wild-type mice. Furthermore, the effect of PKC-α–induced UT-A1 sialylation was mainly mediated by Src kinase but not Raf-1 kinase. Functionally, increased UT-A1 sialylation corresponded with enhanced urea transport activity. Thus, our results reveal a novel mechanism by which PKC regulates UT-A1 function by increasing glycan sialylation through Src kinase pathways, which may have an important role in preventing the osmotic diuresis caused by glucosuria under diabetic conditions. PMID:25300290

  14. Ten things you should know about protein kinases: IUPHAR Review 14

    PubMed Central

    Fabbro, Doriano; Cowan-Jacob, Sandra W; Moebitz, Henrik

    2015-01-01

    Many human malignancies are associated with aberrant regulation of protein or lipid kinases due to mutations, chromosomal rearrangements and/or gene amplification. Protein and lipid kinases represent an important target class for treating human disorders. This review focus on ‘the 10 things you should know about protein kinases and their inhibitors', including a short introduction on the history of protein kinases and their inhibitors and ending with a perspective on kinase drug discovery. Although the ‘10 things’ have been, to a certain extent, chosen arbitrarily, they cover in a comprehensive way the past and present efforts in kinase drug discovery and summarize the status quo of the current kinase inhibitors as well as knowledge about kinase structure and binding modes. Besides describing the potentials of protein kinase inhibitors as drugs, this review also focus on their limitations, particularly on how to circumvent emerging resistance against kinase inhibitors in oncological indications. PMID:25630872

  15. Differential regulation of extracellular signal-regulated protein kinase 1 and Jun N-terminal kinase 1 by Ca2+ and protein kinase C in endothelin-stimulated Rat-1 cells.

    PubMed Central

    Cadwallader, K; Beltman, J; McCormick, F; Cook, S

    1997-01-01

    The extracellular signal-regulated protein kinase (ERK) and Jun N-terminal kinase (JNK) signalling cascades transduce signals from the cell cytoplasm to the nucleus, where they regulate gene expression. The activation of ERK1 by lysophosphatidic acid (LPA) and endothelin 1 (Et-1) was compared in Rat-1 cells. Both stimulated DNA synthesis to a similar degree but, in contrast with LPA, Et-1 did not stimulate sustained ERK1 activation, a signal that is thought to be important for the proliferation of fibroblasts. Et-1, but not LPA, was able to activate JNK1; pharmacological analysis revealed that the same EtA receptor mediates DNA synthesis, ERK1 and JNK1 activation. However, activation of JNK1 required higher concentrations of Et-1 than was required for stimulation of ERK1 or DNA synthesis. Signalling to ERK1 and JNK1 was partly inhibited by pertussis toxin, suggesting that both pathways are regulated in part by Gi or G0 proteins. Activation of JNK1 by Et-1 lagged behind ERK1 activation but was not dependent on it because PD98059, an inhibitor of mitogen-activated protein kinase (or ERK) kinase, was without effect on JNK1 activation. In contrast with recent studies, activation of protein kinase C (PKC) or Ca2+ fluxes inhibited activation of JNK1 but not ERK1; furthermore inhibition of PKC or sequestration of Ca2+ potentiated JNK1 activation by Et-1 but not by anisomycin, and again had little effect on ERK1 activation. These results demonstrate that the same G-protein-coupled receptor can activate both the ERK and JNK signal pathways but the two kinase cascades seem to be separate, parallel pathways that are differentially regulated by PKC and Ca2+. The results are discussed in terms of the role of ERK and JNK in proliferative signalling. PMID:9032468

  16. Protein kinase inhibitors against malignant lymphoma

    PubMed Central

    D’Cruz, Osmond J; Uckun, Fatih M

    2013-01-01

    Introduction Tyrosine kinases (TKs) are intimately involved in multiple signal transduction pathways regulating survival, activation, proliferation and differentiation of lymphoid cells. Deregulation or overexpression of specific oncogenic TKs is implicated in maintaining the malignant phenotype in B-lineage lymphoid malignancies. Several novel targeted TK inhibitors (TKIs) have recently emerged as active in the treatment of relapsed or refractory B-cell lymphomas that inhibit critical signaling pathways, promote apoptotic mechanisms or modulate the tumor microenvironment. Areas covered In this review, the authors summarize the clinical outcomes of newer TKIs in various B-cell lymphomas from published and ongoing clinical studies and abstracts from major cancer and hematology conferences. Expert opinion Multiple clinical trials have demonstrated that robust antitumor activity can be obtained with TKIs directed toward specific oncogenic TKs that are genetically deregulated in various subtypes of B-cell lymphomas. Clinical success of targeting TKIs is dependent upon on identifying reliable molecular and clinical markers associated with select cohorts of patients. Further understanding of the signaling pathways should stimulate the identification of novel molecular targets and expand the development of new therapeutic options and individualized therapies. PMID:23496343

  17. Selective Phosphorylation Inhibitor of Delta Protein Kinase C-Pyruvate Dehydrogenase Kinase Protein-Protein Interactions: Application for Myocardial Injury in Vivo.

    PubMed

    Qvit, Nir; Disatnik, Marie-Hélène; Sho, Eiketsu; Mochly-Rosen, Daria

    2016-06-22

    Protein kinases regulate numerous cellular processes, including cell growth, metabolism, and cell death. Because the primary sequence and the three-dimensional structure of many kinases are highly similar, the development of selective inhibitors for only one kinase is challenging. Furthermore, many protein kinases are pleiotropic, mediating diverse and sometimes even opposing functions by phosphorylating multiple protein substrates. Here, we set out to develop an inhibitor of a selective protein kinase phosphorylation of only one of its substrates. Focusing on the pleiotropic delta protein kinase C (δPKC), we used a rational approach to identify a distal docking site on δPKC for its substrate, pyruvate dehydrogenase kinase (PDK). We reasoned that an inhibitor of PDK's docking should selectively inhibit the phosphorylation of only PDK without affecting phosphorylation of the other δPKC substrates. Our approach identified a selective inhibitor of PDK docking to δPKC with an in vitro Kd of ∼50 nM and reducing cardiac injury IC50 of ∼5 nM. This inhibitor, which did not affect the phosphorylation of other δPKC substrates even at 1 μM, demonstrated that PDK phosphorylation alone is critical for δPKC-mediated injury by heart attack. The approach we describe is likely applicable for the identification of other substrate-specific kinase inhibitors. PMID:27218445

  18. Protein kinase A signaling during bidirectional axenic differentiation in Leishmania.

    PubMed

    Bachmaier, Sabine; Witztum, Ronit; Tsigankov, Polina; Koren, Roni; Boshart, Michael; Zilberstein, Dan

    2016-02-01

    Parasitic protozoa of the genus Leishmania are obligatory intracellular parasites that cycle between the phagolysosome of mammalian macrophages, where they proliferate as intracellular amastigotes, and the midgut of female sand flies, where they proliferate as extracellular promastigotes. Shifting between the two environments induces signaling pathway-mediated developmental processes that enable adaptation to both host and vector. Developmentally regulated expression and phosphorylation of protein kinase A subunits in Leishmania and in Trypanosoma brucei point to an involvement of protein kinase A in parasite development. To assess this hypothesis in Leishmania donovani, we determined proteome-wide changes in phosphorylation of the conserved protein kinase A phosphorylation motifs RXXS and RXXT, using a phospho-specific antibody. Rapid dephosphorylation of these motifs was observed upon initiation of promastigote to amastigote differentiation in culture. No phosphorylated sites were detected in axenic amastigotes. To analyse the kinetics of (re)phosphorylation during axenic reverse differentiation from L. donovani amastigotes to promastigotes, we first established a map of this process with morphological and molecular markers. Upon initiation, the parasites rested for 6-12 h before proliferation of an asynchronous population resumed. After early changes in cell shape, the major changes in molecular marker expression and flagella biogenesis occurred between 24 and 33 h after initiation. RXXS/T re-phosphorylation and expression of the regulatory subunit PKAR1 correlated with promastigote maturation, indicating a promastigote-specific function of protein kinase A signaling. This is supported by the localization of PKAR1 to the flagellum, an organelle reduced to a remnant in amastigote forms. We conclude that a significant increase in protein kinase A-mediated phosphorylation is part of the ordered changes that characterise the amastigote to promastigote

  19. Development of Potent Adenosine Monophosphate Activated Protein Kinase (AMPK) Activators.

    PubMed

    Dokla, Eman M E; Fang, Chun-Sheng; Lai, Po-Ting; Kulp, Samuel K; Serya, Rabah A T; Ismail, Nasser S M; Abouzid, Khaled A M; Chen, Ching-Shih

    2015-11-01

    Previously, we reported the identification of a thiazolidinedione-based adenosine monophosphate activated protein kinase (AMPK) activator, compound 1 (N-[4-({3-[(1-methylcyclohexyl)methyl]-2,4-dioxothiazolidin-5-ylidene}methyl)phenyl]-4-nitro-3-(trifluoromethyl)benzenesulfonamide), which provided a proof of concept to delineate the intricate role of AMPK in regulating oncogenic signaling pathways associated with cell proliferation and epithelial-mesenchymal transition (EMT) in cancer cells. In this study, we used 1 as a scaffold to conduct lead optimization, which generated a series of derivatives. Analysis of the antiproliferative and AMPK-activating activities of individual derivatives revealed a distinct structure-activity relationship and identified 59 (N-(3-nitrophenyl)-N'-{4-[(3-{[3,5-bis(trifluoromethyl)phenyl]methyl}-2,4-dioxothiazolidin-5-ylidene)methyl]phenyl}urea) as the optimal agent. Relative to 1, compound 59 exhibits multifold higher potency in upregulating AMPK phosphorylation in various cell lines irrespective of their liver kinase B1 (LKB1) functional status, accompanied by parallel changes in the phosphorylation/expression levels of p70S6K, Akt, Foxo3a, and EMT-associated markers. Consistent with its predicted activity against tumors with activated Akt status, orally administered 59 was efficacious in suppressing the growth of phosphatase and tensin homologue (PTEN)-null PC-3 xenograft tumors in nude mice. Together, these findings suggest that 59 has clinical value in therapeutic strategies for PTEN-negative cancer and warrants continued investigation in this regard.

  20. Alterations in brain protein kinase C after experimental brain injury.

    PubMed

    Padmaperuma, B; Mark, R; Dhillon, H S; Mattson, M P; Prasad, M R

    1996-04-01

    Regional activities and levels of protein kinase C were measured after lateral fluid percussion brain injury in rats. At 5 min and 20 min after injury, neither cofactor-dependent nor -independent PKC activities in the cytosol and membrane fractions changed in the injured and contralateral cortices or in the ipsilateral hippocampus. Western blot analysis revealed decreases in the levels of cytosolic PKC alpha and PKC beta in the injured cortex after brain injury. In the same site, a significant increase in the levels of membrane PKC alpha and PKC beta was observed after injury. Although the level of PKC alpha did not change and that of PKC beta decreased in the cytosol of the ipsilateral hippocampus, these levels did not increase in the membrane fraction after injury. The levels of PKC gamma were generally unchanged in the cytosol and the membrane, except for its decrease in the cytosol of the hippocampus. There were no changes in the levels of any PKC isoform in either the cytosol or the membrane of the contralateral cortex after injury. The present results suggest a translocation of PKC alpha and PKC beta from the cytosol to the membrane in the injured cortex after brain injury. The observation that such a translocation occurs only in the brain regions that undergo substantial neuronal loss suggests that membrane PKC may play a role in neuronal damage after brain injury. PMID:8861605

  1. Positive feedback of protein kinase C proteolytic activation during apoptosis.

    PubMed Central

    Leverrier, Sabrina; Vallentin, Alice; Joubert, Dominique

    2002-01-01

    In contrast with protein kinase Calpha (PKCalpha) and PKCepsilon, which are better known for promoting cell survival, PKCdelta is known for its pro-apoptotic function, which is exerted mainly through a caspase-3-dependent proteolytic activation pathway. In the present study, we used the rat GH3B6 pituitary adenoma cell line to show that PKCalpha and PKCepsilon are activated and relocalized together with PKCdelta when apoptosis is induced by a genotoxic stress. Proteolytic activation is a crucial step used by the three isoforms since: (1) the catalytic domains of the PKCalpha, PKCepsilon or PKCdelta isoforms (CDalpha, CDepsilon and CDdelta respectively) accumulated, and this accumulation was dependent on the activity of both calpain and caspase; and (2) transient expression of CDalpha, CDepsilon or CDdelta sufficed to induce apoptosis. However, following this initial step of proteolytic activation, the pathways diverge; cytochrome c release and caspase-3 activation are induced by CDepsilon and CDdelta, but not by CDalpha. Another interesting finding of the present study is the proteolysis of PKCdelta induced by CDepsilon expression that revealed the existence of a cross-talk between PKC isoforms during apoptosis. Hence the PKC family may participate in the apoptotic process of pituitary adenoma cells at two levels: downstream of caspase and calpain, and via retro-activation of caspase-3, resulting in the amplification of its own proteolytic activation. PMID:12238950

  2. Phosphorylation of Protein Phosphatase Inhibitor-1 by Protein Kinase C*s

    PubMed Central

    Sahin, Bogachan; Shu, Hongjun; Fernandez, Joseph; El-Armouche, Ali; Molkentin, Jeffery D.; Nairn, Angus C.; Bibb, James A.

    2015-01-01

    Inhibitor-1 becomes a potent inhibitor of protein phosphatase 1 when phosphorylated by cAMP-dependent protein kinase at Thr35. Moreover, Ser67 of inhibitor-1 serves as a substrate for cyclin-dependent kinase 5 in the brain. Here, we report that dephosphoinhibitor-1 but not phospho-Ser67 inhibitor-1 was efficiently phosphorylated by protein kinase C at Ser65 in vitro. In contrast, Ser67 phosphorylation by cyclin-dependent kinase 5 was unaffected by phospho-Ser65. Protein kinase C activation in striatal tissue resulted in the concomitant phosphorylation of inhibitor-1 at Ser65 and Ser67, but not Ser65 alone. Selective pharmacological inhibition of protein phosphatase activity suggested that phospho-Ser65 inhibitor-1 is dephosphorylated by protein phosphatase 1 in the striatum. In vitro studies confirmed these findings and suggested that phospho-Ser67 protects phospho-Ser65 inhibitor-1 from dephosphorylation by protein phosphatase 1 in vivo. Activation of group I metabotropic glutamate receptors resulted in the up-regulation of diphospho-Ser65/Ser67 inhibitor-1 in this tissue. In contrast, the activation of N-methyl-D-aspartate-type ionotropic glutamate receptors opposed increases in striatal diphospho-Ser65/Ser67 inhibitor-1 levels. Phosphomimetic mutation of Ser65 and/or Ser67 did not convert inhibitor-1 into a protein phosphatase 1 inhibitor. On the other hand, in vitro and in vivo studies suggested that diphospho-Ser65/Ser67 inhibitor-1 is a poor substrate for cAMP-dependent protein kinase. These observations extend earlier studies regarding the function of phospho-Ser67 and underscore the possibility that phosphorylation in this region of inhibitor-1 by multiple protein kinases may serve as an integrative signaling mechanism that governs the responsiveness of inhibitor-1 to cAMP-dependent protein kinase activation. PMID:16772299

  3. Phosphorylation of the mRNA cap binding protein and eIF-4A by different protein kinases

    SciTech Connect

    Hagedorn, C.H.

    1987-05-01

    These studies were done to determine the identity of a protein kinase that phosphorylates the mRNA cap binding protein (CBP). Two chromatographic steps (dye and ligand and ion exchange HPLC) produced a 500x purification of an enzyme activity in rabbit reticulocytes that phosphorylated CBP at serine residues. Isoelectric focusing analysis of kinase treated CBP demonstrated 5 isoelectric species of which the 2 most anodic species were phosphorylated (contained /sup 32/P). This kinase activity phosphorylated CBP when it was isolated or in the eIF-4F complex. Purified protein kinase C, cAMP or cGMP dependent protein kinase, casein kinase I or II, myosin light chain kinase or insulin receptor kinase did not significantly phosphorylate isolated CBP or CBP in the eIF-4F complex. However, cAMP and cGMP dependent protein kinases and casein kinase II phosphorylated eIF-4A but did not phosphorylate the 46 kDa component of eIF-4F. cAMP dependent protein kinase phosphorylated a approx. 220 kDa protein doublet in eIF-4F preparations. These studies indicate that CBP kinase activity probably represents a previously unidentified protein kinase. In addition, eIF-4A appears to be phosphorylated by several protein kinases whereas the 46 kDa component of the eIF-4F complex was not.

  4. Characterization of nuclear protein kinases of Xenopus laevis oocytes

    SciTech Connect

    Leiva, L.; Gonzalez, C.; Allende, C.; Allende, J.

    1986-05-01

    Xenopus laevis oocytes contain large nuclei (germinal vesicles) that can be isolated in very pure form and which permit the study of enzymatic activities present in these organelles. Incubation of pure oocyte nuclear homogenates with /sup 32/P in a buffered solution containing 5 mM MgCl/sub 2/ results in the phosphorylation of a large number of proteins by endogenous protein kinases. This phosphorylation is not affected by the addition of cyclic nucleotides or calcium ion and calmodulin. On the other hand the nuclear kinases are considerably stimulated by spermine and spermidine and strongly inhibited by heparin (10 ..mu..g/ml). Addition of exogenous protein substrates shows that the major oocyte kinases are very active with casein and phosvitin as substrates but do not phosphorylate histones or protamines. DEAE-Sephadex chromatography of the nuclear extract fractionates the casein phosphorylating activity in two main peaks. The first peak is not retained on the column equilibrated with 0.1 M NH/sub 2/SO/sub 4/ and uses exclusively ATP as phosphate donor and is insensitive to polyamines or heparin. The second peak which corresponds to 70% of the casein phosphorylation elutes at 0.27 M NH/sub 2/SO/sub 4/ and uses both ATP and GTP as phosphate donors and is greatly stimulated by polyamines and completely inhibited by 10 ..mu..g/ml heparin. On this evidence the authors conclude that the major protein kinase peak corresponds to casein kinase type II which has been found in mammalian nuclei.

  5. GIT1/βPIX signaling proteins and PAK1 kinase regulate microtubule nucleation.

    PubMed

    Černohorská, Markéta; Sulimenko, Vadym; Hájková, Zuzana; Sulimenko, Tetyana; Sládková, Vladimíra; Vinopal, Stanislav; Dráberová, Eduarda; Dráber, Pavel

    2016-06-01

    Microtubule nucleation from γ-tubulin complexes, located at the centrosome, is an essential step in the formation of the microtubule cytoskeleton. However, the signaling mechanisms that regulate microtubule nucleation in interphase cells are largely unknown. In this study, we report that γ-tubulin is in complexes containing G protein-coupled receptor kinase-interacting protein 1 (GIT1), p21-activated kinase interacting exchange factor (βPIX), and p21 protein (Cdc42/Rac)-activated kinase 1 (PAK1) in various cell lines. Immunofluorescence microscopy revealed association of GIT1, βPIX and activated PAK1 with centrosomes. Microtubule regrowth experiments showed that depletion of βPIX stimulated microtubule nucleation, while depletion of GIT1 or PAK1 resulted in decreased nucleation in the interphase cells. These data were confirmed for GIT1 and βPIX by phenotypic rescue experiments, and counting of new microtubules emanating from centrosomes during the microtubule regrowth. The importance of PAK1 for microtubule nucleation was corroborated by the inhibition of its kinase activity with IPA-3 inhibitor. GIT1 with PAK1 thus represent positive regulators, and βPIX is a negative regulator of microtubule nucleation from the interphase centrosomes. The regulatory roles of GIT1, βPIX and PAK1 in microtubule nucleation correlated with recruitment of γ-tubulin to the centrosome. Furthermore, in vitro kinase assays showed that GIT1 and βPIX, but not γ-tubulin, serve as substrates for PAK1. Finally, direct interaction of γ-tubulin with the C-terminal domain of βPIX and the N-terminal domain of GIT1, which targets this protein to the centrosome, was determined by pull-down experiments. We propose that GIT1/βPIX signaling proteins with PAK1 kinase represent a novel regulatory mechanism of microtubule nucleation in interphase cells.

  6. Protein kinase C mechanisms that contribute to cardiac remodelling

    PubMed Central

    Newton, Alexandra C.; Antal, Corina E.; Steinberg, Susan F.

    2016-01-01

    Protein phosphorylation is a highly-regulated and reversible process that is precisely controlled by the actions of protein kinases and protein phosphatases. Factors that tip the balance of protein phosphorylation lead to changes in a wide range of cellular responses, including cell proliferation, differentiation and survival. The protein kinase C (PKC) family of serine/threonine kinases sits at nodal points in many signal transduction pathways; PKC enzymes have been the focus of considerable attention since they contribute to both normal physiological responses as well as maladaptive pathological responses that drive a wide range of clinical disorders. This review provides a background on the mechanisms that regulate individual PKC isoenzymes followed by a discussion of recent insights into their role in the pathogenesis of diseases such as cancer. We then provide an overview on the role of individual PKC isoenzymes in the regulation of cardiac contractility and pathophysiological growth responses, with a focus on the PKC-dependent mechanisms that regulate pump function and/or contribute to the pathogenesis of heart failure. PMID:27433023

  7. A threading approach to protein structure prediction: Studies on TNF-like molecules, Rev proteins, and protein kinases

    NASA Astrophysics Data System (ADS)

    Ihm, Yungok

    The main focus of this dissertation is the application of the threading approach to specific biological problems. The threading scheme developed in our group targets incorporating important structural features necessary for detecting structural similarity between the target sequence and the template structure. This enables us to use our threading method to solve problems for which sequence-based methods are not very much useful. We applied our threading method to predict the three-dimensional structures of lentivirus (EIAV, HIV-1, FIV, SIV) Rev proteins. Predicted structures of Rev proteins suggest that they share a structural similarity among themselves (four-helix bundle). Also, the threading approach has been utilized for screening for potential TNF-like molecules in Arabidopsis. The threading approach identified 35 potential TNF-like proteins in Arabidopsis, six of which are particularly interesting to be tested for the receptor kinase ligand activity. Threading method has also been used to identify potentially new protein kinases, which are not included in the protein kinase data base of C. elegans and Arabidopis. We identified eleven potentially new protein kinases and an additional protein worth investigating for protein kinase activity in C. elegans. Further, we identified ten potentially new protein kinases and additional four proteins worth investigating for the protein kinase activity in Arabidopsis.

  8. Identification and Validation of Inhibitor-Responsive Kinase Substrates using a New Paradigm to Measure Kinase-Specific Protein Phosphorylation Index

    PubMed Central

    Li, Xiang; Rao, Varsha; Jin, Jin; Guan, Bin; Anderes, Kenna L.; Bieberich, Charles J.

    2012-01-01

    Regulation of all cellular processes requires dynamic regulation of protein phosphorylation. We have developed an unbiased system to globally quantify the phosphorylation index for substrates of a specific kinase by independently quantifying phosphorylated and total substrate molecules in a reverse in-gel kinase assay. Non-phosphorylated substrate molecules are first quantified in the presence and absence of a specific stimulus. Total substrate molecules are then measured after complete chemical de-phosphorylation, and a ratio of phosphorylated to total substrate is derived. To demonstrate the utility of this approach, we profiled and quantified changes in phosphorylation index for Protein Kinase CK2 substrates that respond to a small-molecule inhibitor. A broad range of inhibitor-induced changes in phosphorylation was observed in cultured cells. Differences among substrates in the kinetics of phosphorylation change were also revealed. Comparison of CK2 inhibitor-induced changes in phosphorylation in cultured cells and in mouse peripheral blood lymphocytes in vivo revealed distinct kinetic and depth-of-response profiles. This technology provides a new approach to facilitate functional analyses of kinase-specific phosphorylation events. This strategy can be used to dissect the role of phosphorylation in cellular events, to facilitate kinase inhibitor target validation studies, and to inform in vivo analyses of kinase inhibitor drug efficacy. PMID:22663298

  9. Structures of 5-Methylthioribose Kinase Reveal Substrate Specificity and Unusual Mode of Nucleotide Binding

    SciTech Connect

    Ku,S.; Yip, P.; Cornell, K.; Riscoe, M.; Behr, J.; Guillerm, G.; Howell, P.

    2007-01-01

    The methionine salvage pathway is ubiquitous in all organisms, but metabolic variations exist between bacteria and mammals. 5-Methylthioribose (MTR) kinase is a key enzyme in methionine salvage in bacteria and the absence of a mammalian homolog suggests that it is a good target for the design of novel antibiotics. The structures of the apo-form of Bacillus subtilis MTR kinase, as well as its ADP, ADP-PO4, AMPPCP, and AMPPCP-MTR complexes have been determined. MTR kinase has a bilobal eukaryotic protein kinase fold but exhibits a number of unique features. The protein lacks the DFG motif typically found at the beginning of the activation loop and instead coordinates magnesium via a DXE motif (Asp{sup 250}-Glu{sup 252}). In addition, the glycine-rich loop of the protein, analogous to the 'Gly triad' in protein kinases, does not interact extensively with the nucleotide. The MTR substrate-binding site consists of Asp{sup 233} of the catalytic HGD motif, a novel twin arginine motif (Arg{sup 340}/Arg{sup 341}), and a semi-conserved W-loop, which appears to regulate MTR binding specificity. No lobe closure is observed for MTR kinase upon substrate binding. This is probably because the enzyme lacks the lobe closure/inducing interactions between the C-lobe of the protein and the ribosyl moiety of the nucleotide that are typically responsible for lobe closure in protein kinases. The current structures suggest that MTR kinase has a dissociative mechanism.

  10. Raf-1 kinase inhibitory protein expression in thyroid carcinomas.

    PubMed

    Kim, Hyun-Soo; Kim, Gou Young; Lim, Sung-Jig; Kim, Youn Wha

    2010-12-01

    Raf-1 kinase inhibitory protein (RKIP) has been implicated in several fundamental signal transduction pathways that control cellular growth, differentiation, apoptosis and migration. RKIP is reduced in a variety of human carcinomas, but RKIP expression in thyroid carcinomas has not been analyzed at the protein level. In this study, we examined the immunohistochemical expression of RKIP in various subtypes of thyroid carcinoma. Immunostaining for RKIP was performed on 104 cases of primary thyroid carcinoma (40 papillary, 29 follicular, 11 medullary, 11 poorly differentiated, and 13 anaplastic carcinomas) and 26 cases of nodal metastatic tumor (17 papillary, 4 medullary, and 5 anaplastic carcinomas). Normal thyroid tissue and all cases of follicular, papillary, and medullary carcinomas showed uniform, strong cytoplasmic immunoreactivity for RKIP. With the exception of one case, poorly differentiated carcinomas also revealed strong RKIP expression. In contrast, RKIP expression was completely absent in all anaplastic carcinomas. The transition zone from the differentiated carcinoma component (strong RKIP expression) to the anaplastic carcinoma component (no RKIP expression) demonstrated a completely opposite pattern of RKIP immunoreactivity. This reduction of RKIP expression in anaplastic carcinoma was statistically significant (P < 0.0001). Additionally, RKIP expression of nodal metastatic tumors corresponded with that of primary tumors: metastatic papillary and medullary carcinomas showed uniform, strong cytoplasmic RKIP immunoreactivity, in contrast, in metastatic anaplastic carcinomas, RKIP expression was completely absent. RKIP expression is significantly reduced in anaplastic thyroid carcinoma as compared to other subtypes of thyroid carcinoma. Further studies are necessary to elucidate the precise mechanism of RKIP action in anaplastic thyroid carcinoma.

  11. Sangivamycin, a nucleoside analogue, is a potent inhibitor of protein kinase C.

    PubMed

    Loomis, C R; Bell, R M

    1988-02-01

    Protein kinase C functions prominently in cell regulation via its pleiotropic role in signal transduction processes. Certain oncogene products resemble elements involved in transmembrane signaling, elevate cellular sn-1,2-diacylglycerol second messenger levels, and activate protein kinase C. Sangivamycin was unique among the nucleoside compounds tested in its ability to potently inhibit protein kinase C activity. Inhibition was competitive with respect to ATP for both protein kinase C and the catalytic fragment of protein kinase C prepared by trypsin digestion. Sangivamycin was a noncompetitive inhibitor with respect to histone and lipid cofactors (phosphatidylserine and diacylglycerol). Sangivamycin inhibited native protein kinase C and the catalytic fragment identically, with apparent Ki values of 11 and 15 microM, respectively. Sangivamycin was an effective an inhibitor of protein kinase C as H-7, an isoquinolinsulfonamide. Sangivamycin did not inhibit [3H]phorbol-12,13-dibutyrate binding to protein kinase C. Sangivamycin did not exert its action through the lipid binding/regulatory domain; inhibition was not affected by the presence of lipid or detergent. Unlike H-7, sangivamycin selectively inhibited protein kinase C compared to cAMP-dependent protein kinase. The discovery that protein kinase C is inhibited by sangivamycin and other antitumor agents suggests that protein kinase C may be a target for rational design of antitumor compounds. PMID:3338987

  12. Requirement of the FATC domain of protein kinase Tel1 for localization to DNA ends and target protein recognition.

    PubMed

    Ogi, Hiroo; Goto, Greicy H; Ghosh, Avik; Zencir, Sevil; Henry, Everett; Sugimoto, Katsunori

    2015-10-01

    Two large phosphatidylinositol 3-kinase-related protein kinases (PIKKs), ATM and ATR, play a central role in the DNA damage response pathway. PIKKs contain a highly conserved extreme C-terminus called the FRAP-ATM-TRRAP-C-terminal (FATC) domain. In budding yeast, ATM and ATR correspond to Tel1 and Mec1, respectively. In this study, we characterized functions of the FATC domain of Tel1 by introducing substitution or truncation mutations. One substitution mutation, termed tel1-21, and a truncation mutation, called tel1-ΔC, did not significantly affect the expression level. The tel1-21 mutation impaired the cellular response to DNA damage and conferred moderate telomere maintenance defect. In contrast, the tel1-ΔC mutation behaved like a null mutation, conferring defects in both DNA damage response and telomere maintenance. Tel1-21 protein localized to DNA ends as effectively as wild-type Tel1 protein, whereas Tel1-ΔC protein failed. Introduction of a hyperactive TEL1-hy mutation suppressed the tel1-21 mutation but not the tel1-ΔC mutation. In vitro analyses revealed that both Tel1-21 and Tel1-ΔC proteins undergo efficient autophosphorylation but exhibit decreased kinase activities toward the exogenous substrate protein, Rad53. Our results show that the FATC domain of Tel1 mediates localization to DNA ends and contributes to phosphorylation of target proteins.

  13. Role of diacylglycerol-regulated protein kinase C isotypes in growth factor activation of the Raf-1 protein kinase.

    PubMed

    Cai, H; Smola, U; Wixler, V; Eisenmann-Tappe, I; Diaz-Meco, M T; Moscat, J; Rapp, U; Cooper, G M

    1997-02-01

    The Raf protein kinases function downstream of Ras guanine nucleotide-binding proteins to transduce intracellular signals from growth factor receptors. Interaction with Ras recruits Raf to the plasma membrane, but the subsequent mechanism of Raf activation has not been established. Previous studies implicated hydrolysis of phosphatidylcholine (PC) in Raf activation; therefore, we investigated the role of the epsilon isotype of protein kinase C (PKC), which is stimulated by PC-derived diacylglycerol, as a Raf activator. A dominant negative mutant of PKC epsilon inhibited both proliferation of NIH 3T3 cells and activation of Raf in COS cells. Conversely, overexpression of active PKC epsilon stimulated Raf kinase activity in COS cells and overcame the inhibitory effects of dominant negative Ras in NIH 3T3 cells. PKC epsilon also stimulated Raf kinase in baculovirus-infected Spodoptera frugiperda Sf9 cells and was able to directly activate Raf in vitro. Consistent with its previously reported activity as a Raf activator in vitro, PKC alpha functioned similarly to PKC epsilon in both NIH 3T3 and COS cell assays. In addition, constitutively active mutants of both PKC alpha and PKC epsilon overcame the inhibitory effects of dominant negative mutants of the other PKC isotype, indicating that these diacylglycerol-regulated PKCs function as redundant activators of Raf-1 in vivo.

  14. Trans-activation of the DNA-damage signalling protein kinase Chk2 by T-loop exchange.

    PubMed

    Oliver, Antony W; Paul, Angela; Boxall, Katherine J; Barrie, S Elaine; Aherne, G Wynne; Garrett, Michelle D; Mittnacht, Sibylle; Pearl, Laurence H

    2006-07-12

    The protein kinase Chk2 (checkpoint kinase 2) is a major effector of the replication checkpoint. Chk2 activation is initiated by phosphorylation of Thr68, in the serine-glutamine/threonine-glutamine cluster domain (SCD), by ATM. The phosphorylated SCD-segment binds to the FHA domain of a second Chk2 molecule, promoting dimerisation of the protein and triggering phosphorylation of the activation segment/T-loop in the kinase domain. We have now determined the structure of the kinase domain of human Chk2 in complexes with ADP and a small-molecule inhibitor debromohymenialdisine. The structure reveals a remarkable dimeric arrangement in which T-loops are exchanged between protomers, to form an active kinase conformation in trans. Biochemical data suggest that this dimer is the biologically active state promoted by ATM-phosphorylation, and also suggests a mechanism for dimerisation-driven activation of Chk2 by trans-phosphorylation.

  15. Evidence that phytochrome functions as a protein kinase in plant light signalling

    PubMed Central

    Shin, Ah-Young; Han, Yun-Jeong; Baek, Ayoung; Ahn, Taeho; Kim, Soo Young; Nguyen, Thai Son; Son, Minky; Lee, Keun Woo; Shen, Yu; Song, Pill-Soon; Kim, Jeong-Il

    2016-01-01

    It has been suggested that plant phytochromes are autophosphorylating serine/threonine kinases. However, the biochemical properties and functional roles of putative phytochrome kinase activity in plant light signalling are largely unknown. Here, we describe the biochemical and functional characterization of Avena sativa phytochrome A (AsphyA) as a potential protein kinase. We provide evidence that phytochrome-interacting factors (PIFs) are phosphorylated by phytochromes in vitro. Domain mapping of AsphyA shows that the photosensory core region consisting of PAS-GAF-PHY domains in the N-terminal is required for the observed kinase activity. Moreover, we demonstrate that transgenic plants expressing mutant versions of AsphyA, which display reduced activity in in vitro kinase assays, show hyposensitive responses to far-red light. Further analysis reveals that far-red light-induced phosphorylation and degradation of PIF3 are significantly reduced in these transgenic plants. Collectively, these results suggest a positive relationship between phytochrome kinase activity and photoresponses in plants. PMID:27173885

  16. Estrogen stimulates protein tyrosine phosphorylation and Src kinase activity in avian osteoclasts.

    PubMed

    Brubaker, K D; Gay, C V

    1999-12-01

    The estrogen, 17beta-estradiol, stimulated a profound increase in phosphotyrosine immunostaining of proteins that localized along the site of attachment in avian osteoclasts within 1 min of treatment. By 10 min, this rapidly occurring event had returned to basal levels. Pretreatment with 1 microM herbimycin A, a tyrosine kinase inhibitor, prevented the response. Immunoblotting revealed that Src kinase was one of the phosphorylated intermediates. Src kinase also appeared to translocate to the periphery of the cells during the 1 min 17beta-estradiol treatment and became dispersed by 10 min. Src kinase activity measurements indicated an increase in phosphotransferase activity after the 1 min estradiol treatment; this effect diminished with longer exposures to estrogen. Pretreatment of osteoclasts with 1 microg/ml cytochalasin B, an inhibitor of actin polymerization, delayed the appearance of increased phosphotyrosine immunostaining at attachment sites, possibly through inhibition of Src kinase translocation. These findings demonstrate that estrogen stimulates rapid tyrosine phosphorylation in osteoclasts, a process that involves activation and translocation of Src kinase to the plasma membrane.

  17. Evidence that phytochrome functions as a protein kinase in plant light signalling.

    PubMed

    Shin, Ah-Young; Han, Yun-Jeong; Baek, Ayoung; Ahn, Taeho; Kim, Soo Young; Nguyen, Thai Son; Son, Minky; Lee, Keun Woo; Shen, Yu; Song, Pill-Soon; Kim, Jeong-Il

    2016-01-01

    It has been suggested that plant phytochromes are autophosphorylating serine/threonine kinases. However, the biochemical properties and functional roles of putative phytochrome kinase activity in plant light signalling are largely unknown. Here, we describe the biochemical and functional characterization of Avena sativa phytochrome A (AsphyA) as a potential protein kinase. We provide evidence that phytochrome-interacting factors (PIFs) are phosphorylated by phytochromes in vitro. Domain mapping of AsphyA shows that the photosensory core region consisting of PAS-GAF-PHY domains in the N-terminal is required for the observed kinase activity. Moreover, we demonstrate that transgenic plants expressing mutant versions of AsphyA, which display reduced activity in in vitro kinase assays, show hyposensitive responses to far-red light. Further analysis reveals that far-red light-induced phosphorylation and degradation of PIF3 are significantly reduced in these transgenic plants. Collectively, these results suggest a positive relationship between phytochrome kinase activity and photoresponses in plants. PMID:27173885

  18. Regulation of polar auxin transport by protein and lipid kinases

    PubMed Central

    Jaillais, Yvon

    2016-01-01

    The directional transport of auxin, known as polar auxin transport, allows asymmetric distribution of this hormone in different cells and tissues. This system creates local auxin maxima, minima and gradients that are instrumental in both organ initiation and shape determination. As such, polar auxin transport is crucial for all aspects of plant development but also for environmental interaction, notably in shaping plant architecture to its environment. Cell-to-cell auxin transport is mediated by a network of auxin carriers that are regulated at the transcriptional and post-translational levels. Here we review our current knowledge on some aspects of the ‘non-genomic’ regulation of auxin transport, putting an emphasis on how phosphorylation by protein and lipid kinases controls the polarity, intracellular trafficking, stability and activity of auxin carriers. We describe the role of several AGC kinases, including PINOID, D6PK and the blue light photoreceptor phot1, in phosphorylating auxin carriers from the PIN and ABCB families. We also highlight the function of some Receptor-Like Kinases (RLK) and two-component histidine kinase receptors in polar auxin transport, noticing that there are likely RLKs involved in coordinating auxin distribution yet to be discovered. In addition, we describe the emerging role of phospholipid phosphorylation in polarity establishment and intracellular trafficking of PIN proteins. We outline these various phosphorylation mechanisms in the context of primary and lateral root development, leaf cell shape acquisition as well as root gravitropism and shoot phototropism. PMID:27242371

  19. Regulation of polar auxin transport by protein and lipid kinases.

    PubMed

    Armengot, Laia; Marquès-Bueno, Maria Mar; Jaillais, Yvon

    2016-07-01

    The directional transport of auxin, known as polar auxin transport (PAT), allows asymmetric distribution of this hormone in different cells and tissues. This system creates local auxin maxima, minima, and gradients that are instrumental in both organ initiation and shape determination. As such, PAT is crucial for all aspects of plant development but also for environmental interaction, notably in shaping plant architecture to its environment. Cell to cell auxin transport is mediated by a network of auxin carriers that are regulated at the transcriptional and post-translational levels. Here we review our current knowledge on some aspects of the 'non-genomic' regulation of auxin transport, placing an emphasis on how phosphorylation by protein and lipid kinases controls the polarity, intracellular trafficking, stability, and activity of auxin carriers. We describe the role of several AGC kinases, including PINOID, D6PK, and the blue light photoreceptor phot1, in phosphorylating auxin carriers from the PIN and ABCB families. We also highlight the function of some receptor-like kinases (RLKs) and two-component histidine kinase receptors in PAT, noting that there are probably RLKs involved in co-ordinating auxin distribution yet to be discovered. In addition, we describe the emerging role of phospholipid phosphorylation in polarity establishment and intracellular trafficking of PIN proteins. We outline these various phosphorylation mechanisms in the context of primary and lateral root development, leaf cell shape acquisition, as well as root gravitropism and shoot phototropism. PMID:27242371

  20. Protein kinase C mu is located at the Golgi compartment

    PubMed Central

    1996-01-01

    Protein kinase C mu (PKC mu) displays unusual structural features like a pleckstrin homology domain and an amino-terminal hydrophobic region with a putative leader peptide and transmembrane sequence. As a discrete location often is a direct clue to the potential biological function of a kinase, antibodies directed against unique amino- and carboxy-terminal domains of PKC mu were used to localize the protein within intracellular compartments in immunofluorescence and subcellular fractionation studies. Confocal laser scanning microscopy showed colocalization of PKC mu with the resident Golgi marker protein beta 1,4 galactosyltransferase in PKC mu transfectants and in the human hepatocellular carcinoma cell line HepG2, expressing endogenous PKC mu. Long-term treatment of cells with brefeldin A, which disintegrates the Golgi apparatus, disrupted PKC mu-specific staining. Cosegregation of PKC mu with beta 1,4 galactosyltransferase, but not with the endosomal marker rab5, upon density gradient fractionation and Western blot analysis of HepG2 cell extracts, provides independent evidence for a Golgi localization of PKC mu. Moreover, cellular sulfate uptake and Golgi-specific glycosaminoglycan sulfation was enhanced in PKC mu transfectants. Together, these data suggest that PKC mu is a resident protein kinase of the core Golgi compartment and is involved in basal transport processes. PMID:8830770

  1. A secretory kinase complex regulates extracellular protein phosphorylation

    PubMed Central

    Cui, Jixin; Xiao, Junyu; Tagliabracci, Vincent S; Wen, Jianzhong; Rahdar, Meghdad; Dixon, Jack E

    2015-01-01

    Although numerous extracellular phosphoproteins have been identified, the protein kinases within the secretory pathway have only recently been discovered, and their regulation is virtually unexplored. Fam20C is the physiological Golgi casein kinase, which phosphorylates many secreted proteins and is critical for proper biomineralization. Fam20A, a Fam20C paralog, is essential for enamel formation, but the biochemical function of Fam20A is unknown. Here we show that Fam20A potentiates Fam20C kinase activity and promotes the phosphorylation of enamel matrix proteins in vitro and in cells. Mechanistically, Fam20A is a pseudokinase that forms a functional complex with Fam20C, and this complex enhances extracellular protein phosphorylation within the secretory pathway. Our findings shed light on the molecular mechanism by which Fam20C and Fam20A collaborate to control enamel formation, and provide the first insight into the regulation of secretory pathway phosphorylation. DOI: http://dx.doi.org/10.7554/eLife.06120.001 PMID:25789606

  2. Cellular reprogramming through mitogen-activated protein kinases

    PubMed Central

    Lee, Justin; Eschen-Lippold, Lennart; Lassowskat, Ines; Böttcher, Christoph; Scheel, Dierk

    2015-01-01

    Mitogen-activated protein kinase (MAPK) cascades are conserved eukaryote signaling modules where MAPKs, as the final kinases in the cascade, phosphorylate protein substrates to regulate cellular processes. While some progress in the identification of MAPK substrates has been made in plants, the knowledge on the spectrum of substrates and their mechanistic action is still fragmentary. In this focused review, we discuss the biological implications of the data in our original paper (Sustained mitogen-activated protein kinase activation reprograms defense metabolism and phosphoprotein profile in Arabidopsis thaliana; Frontiers in Plant Science 5: 554) in the context of related research. In our work, we mimicked in vivo activation of two stress-activated MAPKs, MPK3 and MPK6, through transgenic manipulation of Arabidopsis thaliana and used phosphoproteomics analysis to identify potential novel MAPK substrates. Here, we plotted the identified putative MAPK substrates (and downstream phosphoproteins) as a global protein clustering network. Based on a highly stringent selection confidence level, the core networks highlighted a MAPK-induced cellular reprogramming at multiple levels of gene and protein expression—including transcriptional, post-transcriptional, translational, post-translational (such as protein modification, folding, and degradation) steps, and also protein re-compartmentalization. Additionally, the increase in putative substrates/phosphoproteins of energy metabolism and various secondary metabolite biosynthesis pathways coincides with the observed accumulation of defense antimicrobial substances as detected by metabolome analysis. Furthermore, detection of protein networks in phospholipid or redox elements suggests activation of downstream signaling events. Taken in context with other studies, MAPKs are key regulators that reprogram cellular events to orchestrate defense signaling in eukaryotes. PMID:26579181

  3. Overexpression of human selenoprotein H in neuronal cells enhances mitochondrial biogenesis and function through activation of protein kinase A, protein kinase B, and cyclic adenosine monophosphate response element-binding protein pathway.

    PubMed

    Mehta, Suresh L; Mendelev, Natalia; Kumari, Santosh; Andy Li, P

    2013-03-01

    Mitochondrial biogenesis is activated by nuclear encoded transcription co-activator peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), which is regulated by several upstream factors including protein kinase A and Akt/protein kinase B. We have previously shown that selenoprotein H enhances the levels of nuclear regulators for mitochondrial biogenesis, increases mitochondrial mass and improves mitochondrial respiratory rate, under physiological condition. Furthermore, overexpression of selenoprotein H protects neuronal HT22 cells from ultraviolet B irradiation-induced cell damage by lowering reactive oxygen species production, and inhibiting activation of caspase-3 and -9, as well as p53. The objective of this study is to identify the cell signaling pathways by which selenoprotein H initiates mitochondrial biogenesis. We first confirmed our previous observation that selenoprotein H transfected HT22 cells increased the protein levels of nuclear-encoded mitochondrial biogenesis factors, peroxisome proliferator-activated receptor γ coactivator-1α, nuclear respiratory factor 1 and mitochondrial transcription factor A. We then observed that total and phosphorylation of protein kinase A, Akt/protein kinase B and cyclic adenosine monophosphate response element-binding protein (CREB) were significantly increased in selenoprotein H transfected cells compared to vector transfected HT22 cells. To verify whether the observed stimulating effects on mitochondrial biogenesis pathways are caused by selenoprotein H and mediated through CREB, we knocked down selenoprotein H mRNA level using siRNA and inhibited CREB with napthol AS-E phosphate in selenoprotein H transfected cells and repeated the measurements of the aforementioned biomarkers. Our results revealed that silencing of selenoprotein H not only decreased the protein levels of PGC-1α, nuclear respiratory factor 1 and mitochondrial transcription factor A, but also decreased the total and

  4. Signals fly when kinases meet Rho-of-plants (ROP) small G-proteins.

    PubMed

    Fehér, Attila; Lajkó, Dézi Bianka

    2015-08-01

    Rho-type small GTP-binding plant proteins function as two-state molecular switches in cellular signalling. There is accumulating evidence that Rho-of-plants (ROP) signalling is positively controlled by plant receptor kinases, through the ROP guanine nucleotide exchange factor proteins. These signalling modules regulate cell polarity, cell shape, hormone responses, and pathogen defence, among other things. Other ROP-regulatory proteins might also be subjected to protein phosphorylation by cellular kinases (e.g., mitogen-activated protein kinases or calcium-dependent protein kinases), in order to integrate various cellular signalling pathways with ROP GTPase-dependent processes. In contrast to the role of kinases in upstream ROP regulation, much less is known about the potential link between ROP GTPases and downstream kinase signalling. In other eukaryotes, Rho-type G-protein-activated kinases are widespread and have a key role in many cellular processes. Recent data indicate the existence of structurally different ROP-activated kinases in plants, but their ROP-dependent biological functions still need to be validated. In addition to these direct interactions, ROPs may also indirectly control the activity of mitogen-activated protein kinases or calcium-dependent protein kinases. These kinases may therefore function as upstream as well as downstream kinases in ROP-mediated signalling pathways, such as the phosphatidylinositol monophosphate kinases involved in cell polarity establishment. PMID:26089155

  5. Signals fly when kinases meet Rho-of-plants (ROP) small G-proteins.

    PubMed

    Fehér, Attila; Lajkó, Dézi Bianka

    2015-08-01

    Rho-type small GTP-binding plant proteins function as two-state molecular switches in cellular signalling. There is accumulating evidence that Rho-of-plants (ROP) signalling is positively controlled by plant receptor kinases, through the ROP guanine nucleotide exchange factor proteins. These signalling modules regulate cell polarity, cell shape, hormone responses, and pathogen defence, among other things. Other ROP-regulatory proteins might also be subjected to protein phosphorylation by cellular kinases (e.g., mitogen-activated protein kinases or calcium-dependent protein kinases), in order to integrate various cellular signalling pathways with ROP GTPase-dependent processes. In contrast to the role of kinases in upstream ROP regulation, much less is known about the potential link between ROP GTPases and downstream kinase signalling. In other eukaryotes, Rho-type G-protein-activated kinases are widespread and have a key role in many cellular processes. Recent data indicate the existence of structurally different ROP-activated kinases in plants, but their ROP-dependent biological functions still need to be validated. In addition to these direct interactions, ROPs may also indirectly control the activity of mitogen-activated protein kinases or calcium-dependent protein kinases. These kinases may therefore function as upstream as well as downstream kinases in ROP-mediated signalling pathways, such as the phosphatidylinositol monophosphate kinases involved in cell polarity establishment.

  6. Structural Bioinformatics and Protein Docking Analysis of the Molecular Chaperone-Kinase Interactions: Towards Allosteric Inhibition of Protein Kinases by Targeting the Hsp90-Cdc37 Chaperone Machinery

    PubMed Central

    Lawless, Nathan; Blacklock, Kristin; Berrigan, Elizabeth; Verkhivker, Gennady

    2013-01-01

    A fundamental role of the Hsp90-Cdc37 chaperone system in mediating maturation of protein kinase clients and supporting kinase functional activity is essential for the integrity and viability of signaling pathways involved in cell cycle control and organism development. Despite significant advances in understanding structure and function of molecular chaperones, the molecular mechanisms and guiding principles of kinase recruitment to the chaperone system are lacking quantitative characterization. Structural and thermodynamic characterization of Hsp90-Cdc37 binding with protein kinase clients by modern experimental techniques is highly challenging, owing to a transient nature of chaperone-mediated interactions. In this work, we used experimentally-guided protein docking to probe the allosteric nature of the Hsp90-Cdc37 binding with the cyclin-dependent kinase 4 (Cdk4) kinase clients. The results of docking simulations suggest that the kinase recognition and recruitment to the chaperone system may be primarily determined by Cdc37 targeting of the N-terminal kinase lobe. The interactions of Hsp90 with the C-terminal kinase lobe may provide additional “molecular brakes” that can lock (or unlock) kinase from the system during client loading (release) stages. The results of this study support a central role of the Cdc37 chaperone in recognition and recruitment of the kinase clients. Structural analysis may have useful implications in developing strategies for allosteric inhibition of protein kinases by targeting the Hsp90-Cdc37 chaperone machinery. PMID:24287464

  7. SMALL GRAIN 1, which encodes a mitogen-activated protein kinase kinase 4, influences grain size in rice.

    PubMed

    Duan, Penggen; Rao, Yuchun; Zeng, Dali; Yang, Yaolong; Xu, Ran; Zhang, Baolan; Dong, Guojun; Qian, Qian; Li, Yunhai

    2014-02-01

    Although grain size is one of the most important components of grain yield, little information is known about the mechanisms that determine final grain size in crops. Here we characterize rice small grain1 (smg1) mutants, which exhibit small and light grains, dense and erect panicles and comparatively slightly shorter plants. The short grain and panicle phenotypes of smg1 mutants are caused by a defect in cell proliferation. The smg1 mutations were identified, using a map-based cloning approach, in mitogen-activated protein kinase kinase 4 (OsMKK4). Relatively higher expression of OsMKK4/SMG1 was detected in younger organs than in older ones, consistent with its role in cell proliferation. Green fluorescent protein (GFP)-OsMKK4/SMG1 fusion proteins appear to be distributed ubiquitously in plant cells. Further results revealed that OsMKK4 influenced brassinosteroid (BR) responses and the expression of BR-related genes. Thus, our findings have identified OsMKK4 as a factor for grain size, and suggest a possible link between the MAPK pathways and BRs in grain growth.

  8. Chemical synthesis and biological validation of immobilized protein kinase inhibitory Leucettines.

    PubMed

    Burgy, Guillaume; Tahtouh, Tania; Durieu, Emilie; Foll-Josselin, Béatrice; Limanton, Emmanuelle; Meijer, Laurent; Carreaux, François; Bazureau, Jean-Pierre

    2013-04-01

    Leucettines, a family of marine sponge-derived 2-aminoimidazolone alkaloids, are potent inhibitors of DYRKs (dual-specificity, tyrosine phosphorylation regulated kinases) and CLKs (cdc2-like kinases). They constitute promising pharmacological leads for the treatment of several diseases, including Alzheimer's disease and Down syndrome. In order to investigate the scope of potential targets of Leucettine L41, a representative member of the chemical class, we designed an affinity chromatography strategy based on agarose-immobilized leucettines. A synthesis protocol for the attachment of a polyethylene (3 or 4 units) linker to L41 was first established. The linker attachment site on L41 was selected on the basis of the co-crystal structure of L41 with several kinases. L41 was then covalently bound to agarose beads through the primary amine located at the end of the linker. Control, kinase inactive Leucettine was also immobilized, as well as free linker devoid of ligand. Extracts of several mouse tissues revealed a complex pattern of interacting proteins, some of which probably resulting from non-specific, hydrophobic binding, while others representing bona fide Leucettine-interacting proteins. DYRK1A and GSK-3 (glycogen synthase kinase-3) were confirmed as interacting targets by Western blotting in various mouse tissues. The Leucettine affinity chromatography resin constitutes a powerful tool to purify and identify the targets of this new promising therapeutic class of molecules. PMID:23454515

  9. The Catalytic Subunit of DNA-Dependent Protein Kinase Coordinates with Polo-Like Kinase 1 to Facilitate Mitotic Entry.

    PubMed

    Lee, Kyung-Jong; Shang, Zeng-Fu; Lin, Yu-Fen; Sun, Jingxin; Morotomi-Yano, Keiko; Saha, Debabrata; Chen, Benjamin P C

    2015-04-01

    DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is the key regulator of the non-homologous end joining pathway of DNA double-strand break repair. We have previously reported that DNA-PKcs is required for maintaining chromosomal stability and mitosis progression. Our further investigations reveal that deficiency in DNA-PKcs activity caused a delay in mitotic entry due to dysregulation of cyclin-dependent kinase 1 (Cdk1), the key driving force for cell cycle progression through G2/M transition. Timely activation of Cdk1 requires polo-like kinase 1 (Plk1), which affects modulators of Cdk1. We found that DNA-PKcs physically interacts with Plk1 and could facilitate Plk1 activation both in vitro and in vivo. Further, DNA-PKcs-deficient cells are highly sensitive to Plk1 inhibitor BI2536, suggesting that the coordination between DNA-PKcs and Plk1 is not only crucial to ensure normal cell cycle progression through G2/M phases but also required for cellular resistance to mitotic stress. On the basis of the current study, it is predictable that combined inhibition of DNA-PKcs and Plk1 can be employed in cancer therapy strategy for synthetic lethality.

  10. Protein Kinase Cδ Mediates Neurogenic but Not Mitogenic Activation of Mitogen-Activated Protein Kinase in Neuronal Cells

    PubMed Central

    Corbit, Kevin C.; Foster, David A.; Rosner, Marsha Rich

    1999-01-01

    In several neuronal cell systems, fibroblast-derived growth factor (FGF) and nerve growth factor (NGF) act as neurogenic agents, whereas epidermal growth factor (EGF) acts as a mitogen. The mechanisms responsible for these different cellular fates are unclear. We report here that although FGF, NGF, and EGF all activate mitogen-activated protein (MAP) kinase (extracellular signal-related kinase [ERK]) in rat hippocampal (H19-7) and pheochromocytoma (PC12) cells, the activation of ERK by the neurogenic agents FGF and NGF is dependent upon protein kinase Cδ (PKCδ), whereas ERK activation in response to the mitogenic EGF is independent of PKCδ. Antisense PKCδ oligonucleotides or the PKCδ-specific inhibitor rottlerin inhibited FGF- and NGF-induced, but not EGF-induced, ERK activation. In contrast, EGF-induced ERK activation was inhibited by the phosphatidylinositol-3-kinase inhibitor wortmannin, which had no effect upon FGF-induced ERK activation. Rottlerin also inhibited the activation of MAP kinase kinase (MEK) in response to activated Raf, but had no effect upon c-Raf activity or ERK activation by activated MEK. These results indicate that PKCδ functions either downstream from or in parallel with c-Raf, but upstream of MEK. Inhibition of PKCδ also blocked neurite outgrowth induced by FGF and NGF in PC12 cells and by activated Raf in H19-7 cells, indicating a role for PKCδ in the neurogenic effects of FGF, NGF, and Raf. Interestingly, the PKCδ requirement is apparently cell type specific, since FGF-induced ERK activation was independent of PKCδ in NIH 3T3 murine fibroblasts, in which FGF is a mitogen. These data demonstrate that PKCδ contributes to growth factor specificity and response in neuronal cells and may also promote cell-type-specific differences in growth factor signaling. PMID:10330161

  11. AMP-activated protein kinase and metabolic control

    PubMed Central

    Viollet, Benoit; Andreelli, Fabrizio

    2011-01-01

    AMP-activated protein kinase (AMPK), a phylogenetically conserved serine/threonine protein kinase, is a major regulator of cellular and whole-body energy homeostasis that coordinates metabolic pathways in order to balance nutrient supply with energy demand. It is now recognized that pharmacological activation of AMPK improves blood glucose homeostasis, lipid profile and blood pressure in insulin-resistant rodents. Indeed, AMPK activation mimics the beneficial effects of physical activity or those of calorie restriction by acting on multiple cellular targets. In addition it is now demonstrated that AMPK is one of the probable (albeit indirect) targets of major antidiabetic drugs including, the biguanides (metformin) and thiazolidinediones, as well as of insulin sensitizing adipokines (e.g., adiponectin). Taken together, such findings highlight the logic underlying the concept of targeting the AMPK pathway for the treatment of metabolic syndrome and type 2 diabetes. PMID:21484577

  12. Compartmentalization role of A-kinase anchoring proteins (AKAPs) in mediating protein kinase A (PKA) signaling and cardiomyocyte hypertrophy.

    PubMed

    Rababa'h, Abeer; Singh, Sonal; Suryavanshi, Santosh V; Altarabsheh, Salah Eldien; Deo, Salil V; McConnell, Bradley K

    2014-12-24

    The Beta-adrenergic receptors (β-ARs) stimulation enhances contractility through protein kinase-A (PKA) substrate phosphorylation. This PKA signaling is conferred in part by PKA binding to A-kinase anchoring proteins (AKAPs). AKAPs coordinate multi-protein signaling networks that are targeted to specific intracellular locations, resulting in the localization of enzyme activity and transmitting intracellular actions of neurotransmitters and hormones to its target substrates. In particular, mAKAP (muscle-selective AKAP) has been shown to be present on the nuclear envelope of cardiomyocytes with various proteins including: PKA-regulatory subunit (RIIα), phosphodiesterase-4D3, protein phosphatase-2A, and ryanodine receptor (RyR2). Therefore, through the coordination of spatial-temporal signaling of proteins and enzymes, mAKAP controls cyclic-adenosine monophosphate (cAMP) levels very tightly and functions as a regulator of PKA-mediated substrate phosphorylation leading to changes in calcium availability and myofilament calcium sensitivity. The goal of this review is to elucidate the critical compartmentalization role of mAKAP in mediating PKA signaling and regulating cardiomyocyte hypertrophy by acting as a scaffolding protein. Based on our literature search and studying the structure-function relationship between AKAP scaffolding protein and its binding partners, we propose possible explanations for the mechanism by which mAKAP promotes cardiac hypertrophy.

  13. Flunitrazepam rapidly reduces GABAA receptor subunit protein expression via a protein kinase C-dependent mechanism

    PubMed Central

    Johnston, Jonathan D; Price, Sally A; Bristow, David R

    1998-01-01

    Acute flunitrazepam (1 μM) exposure for 1 h reduced GABAA receptor α1 (22±4%, mean±s.e.mean) and β2/3 (21±4%) subunit protein levels in cultured rat cerebellar granule cells. This rapid decrease in subunit proteins was completely prevented by bisindolymaleimide 1 (1 μM), an inhibitor of protein kinase C, but not by N-[2-((p-bromocinnamyl)amino)ethyl]-5-isoquinolinesulfonamide (H-89, 4.8 μM), an inhibitor of protein kinases A and G. These results suggest the existence of a benzodiazepine-induced mechanism to rapidly alter GABAA receptor protein expression, that appears to be dependent on protein kinase C activity. PMID:9723942

  14. Phosphorylation of synaptosomal cytoplasmic proteins: Inhibition of calcium-activated, phospholipid-dependent protein kinase (protein kinase c) by bay k 8644.

    PubMed

    Robinson, P J; Lovenberg, W

    1988-01-01

    The phosphorylation of specific substrates of calcium-activated, phospholipid-dependent protein kinase (protein kinase C) was examined in striatal synaptosomal cytoplasm. The phosphoprotein substrata were termed group C phosphoprotems and were divided into two subgroups: group C(1) phosphoproteins (P83, P45A, P21 and P18) were found in both cytoplasm and synaptosomal membranes and, although stimulated by phosphatidylserine, only required exogamous calcium for their labeling; group C(2) phosphoproteins (P120, P96, P21.5, P18.5 and P16) were found predominantly in the cytoplasm and were absolutely dependent upon exogenous calcium and phosphatidylserme for their labeling. Several criteria were used to identify these proteins as specific protein kinase C substrates: (a) their phosphorylation was stimulated to a greater extent by Ca(2+) /phosphatidylserine/diolein than by Ca(2+) alone or Cal(2+) /calmodulin (group C(1)) or was completely dependent upon Ca(2+) /phosphatdylserine/diolein (group C(2)); (b) supermaximal concentrations of the cAMP-dependent protein kinase inhibitor were without effect; (c) their phosphorylation was stimulated by oleic acid, which selectively activates protein kinase C in the absence of Ca(2+); (d) NaCl, which inhibited cAMP- and Ca(2+)/calmodulindependent phosphorylation, slightly increased phosphorylation of group C(1) and slightly decreased phosphorylation of group C(2) phosphoproteins. Maximal phosphorylation of P96 and other group C phosphoproteins occurred within 60 s and was followed by a slow decay rate while substrata of calmodulin-dependent protein kinase were maximally labeled within 20-30 s and rapidly dephosphorylated. The phosphorylation of all group C phosphoproteins was inhibited by the calcium channel agomst BAY K 8644, however, group C(2) phosphoproteins were considerably more sensitive. The IC(50) for inhibition of P96 labeling was 19 ?M. but for P83 was 190 ?M. Group B phosphoproteins were also slightly inhibited, and the

  15. Identification of human cyclin-dependent kinase 8, a putative protein kinase partner for cyclin C.

    PubMed

    Tassan, J P; Jaquenoud, M; Léopold, P; Schultz, S J; Nigg, E A

    1995-09-12

    Metazoan cyclin C was originally isolated by virtue of its ability to rescue Saccharomyces cerevisiae cells deficient in G1 cyclin function. This suggested that cyclin C might play a role in cell cycle control, but progress toward understanding the function of this cyclin has been hampered by the lack of information on a potential kinase partner. Here we report the identification of a human protein kinase, K35 [cyclin-dependent kinase 8 (CDK8)], that is likely to be a physiological partner of cyclin C. A specific interaction between K35 and cyclin C could be demonstrated after translation of CDKs and cyclins in vitro. Furthermore, cyclin C could be detected in K35 immunoprecipitates prepared from HeLa cells, indicating that the two proteins form a complex also in vivo. The K35-cyclin C complex is structurally related to SRB10-SRB11, a CDK-cyclin pair recently shown to be part of the RNA polymerase II holoenzyme of S. cerevisiae. Hence, we propose that human K35(CDK8)-cyclin C might be functionally associated with the mammalian transcription apparatus, perhaps involved in relaying growth-regulatory signals.

  16. Circulating protein synthesis rates reveal skeletal muscle proteome dynamics

    PubMed Central

    Shankaran, Mahalakshmi; King, Chelsea L.; Angel, Thomas E.; Holmes, William E.; Li, Kelvin W.; Colangelo, Marc; Price, John C.; Turner, Scott M.; Bell, Christopher; Hamilton, Karyn L.; Miller, Benjamin F.; Hellerstein, Marc K.

    2015-01-01

    Here, we have described and validated a strategy for monitoring skeletal muscle protein synthesis rates in rodents and humans over days or weeks from blood samples. We based this approach on label incorporation into proteins that are synthesized specifically in skeletal muscle and escape into the circulation. Heavy water labeling combined with sensitive tandem mass spectrometric analysis allowed integrated synthesis rates of proteins in muscle tissue across the proteome to be measured over several weeks. Fractional synthesis rate (FSR) of plasma creatine kinase M-type (CK-M) and carbonic anhydrase 3 (CA-3) in the blood, more than 90% of which is derived from skeletal muscle, correlated closely with FSR of CK-M, CA-3, and other proteins of various ontologies in skeletal muscle tissue in both rodents and humans. Protein synthesis rates across the muscle proteome generally changed in a coordinate manner in response to a sprint interval exercise training regimen in humans and to denervation or clenbuterol treatment in rodents. FSR of plasma CK-M and CA-3 revealed changes and interindividual differences in muscle tissue proteome dynamics. In human subjects, sprint interval training primarily stimulated synthesis of structural and glycolytic proteins. Together, our results indicate that this approach provides a virtual biopsy, sensitively revealing individualized changes in proteome-wide synthesis rates in skeletal muscle without a muscle biopsy. Accordingly, this approach has potential applications for the diagnosis, management, and treatment of muscle disorders. PMID:26657858

  17. New roles of G protein-coupled receptor kinase 2 (GRK2) in cell migration

    PubMed Central

    Penela, Petronila; Ribas, Catalina; Aymerich, Ivette

    2009-01-01

    G protein-coupled receptor kinase 2 (GRK2) was initially identified as a key player, together with β-arrestins, in the regulation of multiple G protein-coupled receptors (GPCR). Further research has revealed a complex GRK2 interactome, that includes a variety of proteins related to cell motility, and a role for GRK2 kinase activity in inhibiting chemokine-induced immune cell migration. In addition, we have recently reported that GRK2 positively regulates integrin and sphingosine-1-phosphate-dependent motility in epithelial cell types and fibroblasts, acting as a scaffold molecule. We suggest that the positive or negative correlation of GRK2 levels with cell migration would depend on the cell type, specific stimuli acting through plasma membrane receptors, or on the signalling context, leading to differential networks of interaction of GRK2 with cell migration-related signalosomes. PMID:19372742

  18. Role of protein kinase D signaling in pancreatic cancer.

    PubMed

    Guha, Sushovan; Tanasanvimon, Suebpong; Sinnett-Smith, James; Rozengurt, Enrique

    2010-12-15

    Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers with dismal survival rates. Its intransigence to conventional therapy renders PDAC an aggressive disease with early metastatic potential. Thus, novel targets for PDAC therapy are urgently needed. Multiple signal transduction pathways are implicated in progression of PDAC. These pathways stimulate production of intracellular messengers in their target cells to modify their behavior, including the lipid-derived diacylglycerol (DAG). One of the prominent intracellular targets of DAG is the protein kinase C (PKC) family. However, the mechanisms by which PKC-mediated signals are decoded by the cell remain incompletely understood. Protein kinase D1 (PKD or PKD1, initially called atypical PKCμ), is the founding member of a novel protein kinase family that includes two additional protein kinases that share extensive overall homology with PKD, termed PKD2, and PKD3. The PKD family occupies a unique position in the signal transduction pathways initiated by DAG and PKC. PKD lies downstream of PKCs in a novel signal transduction pathway implicated in the regulation of multiple fundamental biological processes. We and others have shown that PKD-mediated signaling pathways promote mitogenesis and angiogenesis in PDAC. Our recent observations demonstrate that PKD also potentiates chemoresistance and invasive potential of PDAC cells. This review will briefly highlight diverse biological roles of PKD family in multiple neoplasias including PDAC. Further, this review will underscore our latest advancement with the development of a potent PKD family inhibitor and its effect both in vitro and in vivo in PDAC. PMID:20621068

  19. The p38/RK mitogen-activated protein kinase pathway regulates interleukin-6 synthesis response to tumor necrosis factor.

    PubMed Central

    Beyaert, R; Cuenda, A; Vanden Berghe, W; Plaisance, S; Lee, J C; Haegeman, G; Cohen, P; Fiers, W

    1996-01-01

    Tumour necrosis factor (TNF) is a pleiotropic cytokine, the activities of which include effects on gene expression, cell growth and cell death. The biological signalling mechanisms which are responsible for these TNF effects remain largely unknown. Here we demonstrate that the stress-responsive p38 mitogen-activated protein (MAP) kinase is involved in TNF-induced cytokine expression. TNF Treatment of cell activated the p38 MAP kinase pathway, as revealed by increased phosphorylation of p38 MAP kinase itself, activation of the substrate protein MAPKAP kinase-2, and culminating in the phosphorylation of the heat shock protein 27 (hsp27). Pretreatment of cells with the highly specific p38 MAP kinase inhibitor SB203580 completely blocked this TNF-induced activation of MAPKAP kinase-2 and hsp27 phosphorylation. Under the same conditions, SB203580 also completely inhibited TNF-induced synthesis of interleukin (IL)-6 and expression of a reporter gene that was driven by a minimal promoter containing two NF-Kappa B elements. However, neither TNF-induced DNA binding of TNF-Kappa B nor TNF-induced phosphorylation of its subunits was modulated by SB203580, suggesting that NF-Kappa B is not a direct target for the p38 MAP kinase pathway. Interestingly, TNF-induced cytotoxicity was not affected by SB203580, indicating that p38 MAP kinase might be an interesting target to interfere selectively with TNF-induced gene activation. Images PMID:8617238

  20. Enzymatic characteristics of the c-Raf-1 protein kinase.

    PubMed

    Force, T; Bonventre, J V; Heidecker, G; Rapp, U; Avruch, J; Kyriakis, J M

    1994-02-15

    The c-Raf-1 protein kinase plays a central role in the mitogenic response of cells to growth factors, cytokines, and many oncogenes. Despite the critical importance of this enzyme, very little is known of its biochemical properties or mechanisms of regulation. In these experiments, we used the only candidate physiologic substrate identified as yet for c-Raf-1, mitogen-activated protein kinase kinase (MAPKK), to examine enzymatic characteristics and candidate modulators of c-Raf-1, c-Raf-1 was purified from Sf9 cells infected with recombinant baculovirus encoding a histidine-tagged c-Raf-1. The Km values of c-Raf-1 for ATP and MAPKK were 11.6 microM and 0.8 microM, respectively, and the stoichiometry of phosphorylation of MAPKK by c-Raf-1 was 1.67 mol of phosphate per mol of MAPKK. In contrast to prior reports, Mg2+ was the preferred cation at Mg2+ and Mn2+ concentrations > 5 mM. c-Raf-1 substrate specificity was extremely restricted, consistent with the identification of only one candidate physiologic substrate to date and highlighting the necessity of using MAPKK rather than artificial substrates in c-Raf-1 activity assays. Of multiple potential substrates tested, the only one phosphorylated to > 20% of the level of MAPKK phosphorylation was myelin basic protein (22%). Heat-denatured MAPKK was phosphorylated at only 2% the level of native MAPKK, indicating that the restricted substrate specificity may be due to tertiary-structural requirements. We also examined whether c-Raf-1 activity is modulated by lipid binding to the cysteine finger region in its regulatory domain. Of multiple mitogen-stimulated or cell-membrane lipids tested, only phosphatidylserine and diacylglycerol in the presence of Ca2+ (2.5 mM) increased c-Raf-1 kinase activity significantly (1.5-fold). The increase is probably not of physiologic significance because it was about two orders of magnitude less than the stimulation of protein kinase C by these lipids. On gel-filtration chromatography, the

  1. Enzymatic characteristics of the c-Raf-1 protein kinase.

    PubMed Central

    Force, T; Bonventre, J V; Heidecker, G; Rapp, U; Avruch, J; Kyriakis, J M

    1994-01-01

    The c-Raf-1 protein kinase plays a central role in the mitogenic response of cells to growth factors, cytokines, and many oncogenes. Despite the critical importance of this enzyme, very little is known of its biochemical properties or mechanisms of regulation. In these experiments, we used the only candidate physiologic substrate identified as yet for c-Raf-1, mitogen-activated protein kinase kinase (MAPKK), to examine enzymatic characteristics and candidate modulators of c-Raf-1, c-Raf-1 was purified from Sf9 cells infected with recombinant baculovirus encoding a histidine-tagged c-Raf-1. The Km values of c-Raf-1 for ATP and MAPKK were 11.6 microM and 0.8 microM, respectively, and the stoichiometry of phosphorylation of MAPKK by c-Raf-1 was 1.67 mol of phosphate per mol of MAPKK. In contrast to prior reports, Mg2+ was the preferred cation at Mg2+ and Mn2+ concentrations > 5 mM. c-Raf-1 substrate specificity was extremely restricted, consistent with the identification of only one candidate physiologic substrate to date and highlighting the necessity of using MAPKK rather than artificial substrates in c-Raf-1 activity assays. Of multiple potential substrates tested, the only one phosphorylated to > 20% of the level of MAPKK phosphorylation was myelin basic protein (22%). Heat-denatured MAPKK was phosphorylated at only 2% the level of native MAPKK, indicating that the restricted substrate specificity may be due to tertiary-structural requirements. We also examined whether c-Raf-1 activity is modulated by lipid binding to the cysteine finger region in its regulatory domain. Of multiple mitogen-stimulated or cell-membrane lipids tested, only phosphatidylserine and diacylglycerol in the presence of Ca2+ (2.5 mM) increased c-Raf-1 kinase activity significantly (1.5-fold). The increase is probably not of physiologic significance because it was about two orders of magnitude less than the stimulation of protein kinase C by these lipids. On gel-filtration chromatography, the

  2. Phosphorylation of Mycobacterium tuberculosis protein tyrosine kinase A PtkA by Ser/Thr protein kinases.

    PubMed

    Zhou, Peifu; Wong, Dennis; Li, Wu; Xie, Jianping; Av-Gay, Yossef

    2015-11-13

    Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), has inflicted about one third of mankind and claims millions of deaths worldwide annually. Signalling plays an important role in Mtb pathogenesis and persistence, and thus represents attractive resource for drug target candidates. Here, we show that protein tyrosine kinase A (PtkA) can be phosphorylated by Mtb endogenous eukaryotic-like Ser/Thr protein kinases (eSTPKs). Kinase assays showed that PknA, PknD, PknF, and PknK can phosphorylate PtkA in dose- and time-dependent manner. Enzyme kinetics suggests that PknA has the highest affinity and enzymatic efficiency towards PtkA. Furthermore, protein-protein interaction assay in surrogate host showed that PtkA interacts with multi-eSTPKs in vivo, including PknA. Lastly, we show that PtkA phosphorylation by eSTPKs occurs on threonine residues and may effect tyrosine phosphorylation levels and thus PtkA activity in vitro. These results demonstrate that PtkA can serve as a substrate to many eSTPKs and suggests that's its activity can be regulated. PMID:26417687

  3. Pachastrissamine (jaspine B) and its stereoisomers inhibit sphingosine kinases and atypical protein kinase C.

    PubMed

    Yoshimitsu, Yuji; Oishi, Shinya; Miyagaki, Jun; Inuki, Shinsuke; Ohno, Hiroaki; Fujii, Nobutaka

    2011-09-15

    Sphingosine kinases (SphKs) are oncogenic enzymes that regulate the critical balance between ceramide and sphingosine-1-phosphate. Much effort has been dedicated to develop inhibitors against these enzymes. Naturally occurring pachastrissamine (jaspine B) and all its stereoisomers were prepared and evaluated for their inhibitory effects against SphKs. All eight stereoisomers exhibited moderate to potent inhibitory activity against SphK1 and SphK2. Inhibitory effects were profiled against protein kinase C (PKC) isoforms by in vitro experiments. Atypical PKCs (PKCζ and PKCι) were inhibited by several pachastrissamine stereoisomers. The improved activity over N,N-dimethylsphingosine suggests that the cyclic scaffold in pachastrissamines facilitates potential favorable interactions with SphKs and PKCs.

  4. Cell signaling through protein kinase C oxidation and activation.

    PubMed

    Cosentino-Gomes, Daniela; Rocco-Machado, Nathália; Meyer-Fernandes, José Roberto

    2012-01-01

    Due to the growing importance of cellular signaling mediated by reactive oxygen species (ROS), proteins that are reversibly modulated by these reactant molecules are of high interest. In this context, protein kinases and phosphatases, which act coordinately in the regulation of signal transduction through the phosphorylation and dephosphorylation of target proteins, have been described to be key elements in ROS-mediated signaling events. The major mechanism by which these proteins may be modified by oxidation involves the presence of key redox-sensitive cysteine residues. Protein kinase C (PKC) is involved in a variety of cellular signaling pathways. These proteins have been shown to contain a unique structural feature that is susceptible to oxidative modification. A large number of scientific studies have highlighted the importance of ROS as a second messenger in numerous cellular processes, including cell proliferation, gene expression, adhesion, differentiation, senescence, and apoptosis. In this context, the goal of this review is to discuss the mechanisms by which PKCs are modulated by ROS and how these processes are involved in the cellular response. PMID:23109817

  5. Conformation and topology of diacylglycerol kinase in E.coli membranes revealed by solid-state NMR spectroscopy.

    PubMed

    Chen, Yanke; Zhang, Zhengfeng; Tang, Xinqi; Li, Jianping; Glaubitz, Clemens; Yang, Jun

    2014-05-26

    Solid-state NMR is a powerful tool for studying membrane proteins in a native-like lipid environment. 3D magic angle spinning (MAS) NMR was employed to characterize the structure of E.coli diacylglycerol kinase (DAGK) reconstituted into its native E.coli lipid membranes. The secondary structure and topology of DAGK revealed by solid-state NMR are different from those determined by solution-state NMR and X-ray crystallography. This study provides a good example for demonstrating the influence of membrane environments on the structure of membrane proteins.

  6. Neurite outgrowth of neuroblastoma cells overexpressing alpha and beta isoforms of Ca2+/calmodulin-dependent protein kinase II-effects of protein kinase inhibitors.

    PubMed

    Yamauchi, T; Yoshimura, Y; Nomura, T; Fujii, M; Sugiura, H

    1998-06-01

    Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) is one of the most abundant protein kinases in the brain and has a broad substrate specificity [M.K. Bennett, N.E. Erondu, M.B. Kennedy, Purification and characterization of a calmodulin-dependent protein kinase that is highly concentrated in brain, J. Biol. Chem. 258 (1983) 12735-12744 [1]; J.R. Goldenring, B. Gonzalez, J.S. McGuire, Jr., R.J. DeLorenzo, Purification and characterization of a calmodulin-dependent kinase from rat brain cytosol able to phosphorylate tubulin and microtubule-associated proteins, J. Biol. Chem. 258 (1983) 12632-12640 [4]; M.B. Kennedy, P. Greengard, Two calcium/calmodulin-dependent protein kinases, which are highly concentrated in brain, phosphorylate protein I at distinct sites, Proc. Natl. Acad. Sci. U.S.A. 78 (1981) 1293-1297 [10]; T. Yamauchi, H. Fujisawa, Evidence for three distinct forms of calmodulin-dependent protein kinases from rat brain, FEBS Lett. 116 (1980) 141-144 [20]; T. Yamauchi, H. Fujisawa, Purification and characterization of the brain calmodulin-dependent protein kinase (kinase II), which is involved in the activation of tryptophan 5-monooxygenase, Eur. J. Biochem. 132 (1983) 15-21 [21

  7. Expression of a gibberellin-induced leucine-rich repeat receptor-like protein kinase in deepwater rice and its interaction with kinase-associated protein phosphatase

    SciTech Connect

    Knaap, E. van der; Sauter, M.; Kende, H. . DOE Plant Research Lab.); Song, W.Y.; Ruan, D.L.; Ronald, P.C. . Dept. of Plant Pathology)

    1999-06-01

    The authors identified in deepwater rice (Oryza sativa L.) a gene encoding a leucine-rich repeat receptor-like transmembrane protein kinase, OsTMK (O. sativa transmembrane kinase). The transcript levels of OsTMK increased in the rice internode in response to gibberellin. Expression of OsTMK was especially high in regions undergoing cell division and elongation. The kinase domain of OsTMK was enzymatically active autophosphorylating on serine and threonine residues. A cDNA encoding a rice ortholog of a kinase-associated type 2C protein phosphatase (OsKAPP) was cloned. KAPPs are putative downstream components in kinase-mediated signal transduction pathways. The kinase interaction domain of OsKAPP was phosphorylated in vitro by the kinase domain of OsTMK. RNA gel-blot analysis indicated that the expression of OsTMK and OsKAPP was similar in different tissues of the rice plant. In protein-binding assays, OsKAPP interacted with a receptor-like protein kinase, RLK5 of Arabidopsis, but not with the protein kinase domains of the rice and maize receptor-like protein kinases Xa21 and ZmPK1, respectively.

  8. Tripolin A, a Novel Small-Molecule Inhibitor of Aurora A Kinase, Reveals New Regulation of HURP's Distribution on Microtubules

    PubMed Central

    Kesisova, Iliana A.; Nakos, Konstantinos C.; Tsolou, Avgi; Angelis, Dimitrios; Lewis, Joe; Chatzaki, Aikaterini; Agianian, Bogos; Giannis, Athanassios; Koffa, Maria D.

    2013-01-01

    Mitotic regulators exhibiting gain of function in tumor cells are considered useful cancer therapeutic targets for the development of small-molecule inhibitors. The human Aurora kinases are a family of such targets. In this study, from a panel of 105 potential small-molecule inhibitors, two compounds Tripolin A and Tripolin B, inhibited Aurora A kinase activity in vitro. In human cells however, only Tripolin A acted as an Aurora A inhibitor. We combined in vitro, in vivo single cell and in silico studies to demonstrate the biological action of Tripolin A, a non-ATP competitive inhibitor. Tripolin A reduced the localization of pAurora A on spindle microtubules (MTs), affected centrosome integrity, spindle formation and length, as well as MT dynamics in interphase, consistent with Aurora A inhibition by RNAi or other specific inhibitors, such as MLN8054 or MLN8237. Interestingly, Tripolin A affected the gradient distribution towards the chromosomes, but not the MT binding of HURP (Hepatoma Up-Regulated Protein), a MT-associated protein (MAP) and substrate of the Aurora A kinase. Therefore Tripolin A reveals a new way of regulating mitotic MT stabilizers through Aurora A phosphorylation. Tripolin A is predicted to bind Aurora A similarly but not identical to MLN8054, therefore it could be used to dissect pathways orchestrated by Aurora kinases as well as a scaffold for further inhibitor development. PMID:23516487

  9. Calcium-independent binding to interfacial phorbol esters causes protein kinase C to associate with membranes in the absence of acidic lipids.

    PubMed

    Mosior, M; Newton, A C

    1996-02-01

    The mechanism of interaction of phorbol esters with conventional protein kinase Cs was addressed by examining the direct binding of this class of activators to protein kinase C beta II. Binding measurements reveal that the major role of phorbol esters is to increase the affinity of protein kinase C for membranes by several orders of magnitude. The relative increase depends linearly on the mole fraction of phorbol esters in membranes, with the potency illustrated by the finding that 1 mol% phorbol 12-myristate 13-acetate (PMA) increases protein kinase C's membrane association by approximately 4 orders of magnitude. For comparison, diacylglycerol (DG), which also activates protein kinase C by increasing the enzyme's membrane affinity, is 2 orders of magnitude less effective than PMA in altering protein kinase C's membrane affinity. The remarkably high-affinity interaction with phorbol esters allowed us to measure the direct binding of protein kinase C to PMA in neutral membranes and, thus, to evaluate the effect of Ca2+ on the phorbol ester interaction in the absence of Ca2+ effects on the enzyme's interaction with acidic lipids. Changing the Ca2+ concentration over 5 orders of magnitude had no effect on the direct interaction of protein kinase C with PMA immobilized in phosphatidylcholine membranes. Thus, the Ca(2+)-binding site for membrane association and the phorbol ester-binding site do not interact allosterically. Lastly, a method that does not have the limitations of the Scatchard plot for analysis of amphitropic proteins was used to determine the dissociation constant of protein kinase C from phorbol esters: expressed relative to membrane lipids, the dissociation constant is 1.5 x 10(-5) mol %. In summary, our data reveal that (1) the direct binding of protein kinase C to phorbol esters, in the absence of interactions with acidic lipids, provides a major contribution to the free energy change involved in the association of protein kinase C with membranes and

  10. Rho-associated kinase, a novel serine/threonine kinase, as a putative target for small GTP binding protein Rho.

    PubMed Central

    Matsui, T; Amano, M; Yamamoto, T; Chihara, K; Nakafuku, M; Ito, M; Nakano, T; Okawa, K; Iwamatsu, A; Kaibuchi, K

    1996-01-01

    The small GTP binding protein Rho is implicated in cytoskeletal responses to extracellular signals such as lysophosphatidic acid to form stress fibers and focal contacts. Here we have purified a Rho-interacting protein with a molecular mass of approximately 164 kDa (p164) from bovine brain. This protein bound to GTPgammaS (a non-hydrolyzable GTP analog).RhoA but not to GDP.RhoA or GTPgammaS.RhoA with a mutation in the effector domain (RhoAA37).p164 had a kinase activity which was specifically stimulated by GTPgammaS.RhoA. We obtained the cDNA encoding p164 on the basis of its partial amino acid sequences and named it Rho-associated kinase (Rho-kinase). Rho-kinase has a catalytic domain in the N-terminal portion, a coiled coil domain in the middle portion and a zinc finger-like motif in the C-terminal portion. The catalytic domain shares 72% sequence homology with that of myotonic dystrophy kinase and the coiled coil domain contains a Rho-interacting interface. When COS7 cells were cotransfected with Rho-kinase and activated RhoA, some Rho-kinase was recruited to membranes. Thus it is likely that Rho-kinase is a putative target serine/threonine kinase for Rho and serves as a mediator of the Rho-dependent signaling pathway. Images PMID:8641286

  11. Mitogen-Activated Protein Kinases and Hypoxic/Ischemic Nephropathy.

    PubMed

    Luo, Fengbao; Shi, Jian; Shi, Qianqian; Xu, Xianlin; Xia, Ying; He, Xiaozhou

    2016-01-01

    Tissue hypoxia/ischemia is a pathological feature of many human disorders including stroke, myocardial infarction, hypoxic/ischemic nephropathy, as well as cancer. In the kidney, the combination of limited oxygen supply to the tissues and high oxygen demand is considered the main reason for the susceptibility of the kidney to hypoxic/ischemic injury. In recent years, increasing evidence has indicated that a reduction in renal oxygen tension/blood supply plays an important role in acute kidney injury, chronic kidney disease, and renal tumorigenesis. However, the underlying signaling mechanisms, whereby hypoxia alters cellular behaviors, remain poorly understood. Mitogen-activated protein kinases (MAPKs) are key signal-transducing enzymes activated by a wide range of extracellular stimuli, including hypoxia/ischemia. There are four major family members of MAPKs: the extracellular signal-regulated kinases-1 and -2 (ERK1/2), the c-Jun N-terminal kinases (JNK), p38 MAPKs, and extracellular signal-regulated kinase-5 (ERK5/BMK1). Recent studies, including ours, suggest that these MAPKs are differentially involved in renal responses to hypoxic/ischemic stress. This review will discuss their changes in hypoxic/ischemic pathophysiology with acute kidney injury, chronic kidney diseases and renal carcinoma. PMID:27544204

  12. Protein kinase D activity controls endothelial nitric oxide synthesis.

    PubMed

    Aicart-Ramos, Clara; Sánchez-Ruiloba, Lucía; Gómez-Parrizas, Mónica; Zaragoza, Carlos; Iglesias, Teresa; Rodríguez-Crespo, Ignacio

    2014-08-01

    Vascular endothelial growth factor (VEGF) regulates key functions of the endothelium, such as angiogenesis or vessel repair in processes involving endothelial nitric oxide synthase (eNOS) activation. One of the effector kinases that become activated in endothelial cells upon VEGF treatment is protein kinase D (PKD). Here, we show that PKD phosphorylates eNOS, leading to its activation and a concomitant increase in NO synthesis. Using mass spectrometry, we show that the purified active kinase specifically phosphorylates recombinant eNOS on Ser1179. Treatment of endothelial cells with VEGF or phorbol 12,13-dibutyrate (PDBu) activates PKD and increases eNOS Ser1179 phosphorylation. In addition, pharmacological inhibition of PKD and gene silencing of both PKD1 and PKD2 abrogate VEGF signaling, resulting in a clear diminished migration of endothelial cells in a wound healing assay. Finally, inhibition of PKD in mice results in an almost complete disappearance of the VEGF-induced vasodilatation, as monitored through determination of the diameter of the carotid artery. Hence, our data indicate that PKD is a new regulatory kinase of eNOS in endothelial cells whose activity orchestrates mammalian vascular tone. PMID:24928905

  13. Protein kinase CK2 interacts with Chk2 and phosphorylates Mre11 on serine 649

    SciTech Connect

    Kim, Seong-Tae . E-mail: stkim@med.skku.ac.kr

    2005-05-27

    The Mre11-Rad50-Nbs1 protein complex has been known to be involved in a variety of DNA metabolic events that involve DNA double-strand breaks (DSBs). The phosphorylation of Mre11 is increased in response to ionizing radiation, which suggests that phosphorylation of Mre11 may be an important regulatory mechanism of this complex. Mre11-phosphorylating kinase activities were observed in Chk2 immunoprecipitates and HeLa nuclear extracts. Through the tandem affinity tagging system and conventional chromatography, this kinase was purified and identified as protein kinase CK2. CK2 phosphorylates Mre11 in vitro. In vitro kinase assay with a series of truncated Mre11 proteins as substrates for CK2 and site-directed mutagenesis showed that serine 649 of Mre11 is mainly phosphorylated by CK2 in vitro. In vivo labeling and phosphopeptide mapping analysis revealed that this phosphorylation occurs in vivo. These data implicate CK2 as a potential upstream regulator of Mre11 function.

  14. COMPARTMENTALIZED PHOSPHORYLATION OF IAP BY PROTEIN KINASE A REGULATES CYTOPROTECTION

    PubMed Central

    Dohi, Takehiko; Xia, Fang; Altieri, Dario C.

    2007-01-01

    SUMMARY Cell death pathways are likely regulated in specialized subcellular microdomains, but how this occurs is not understood. Here, we show that cyclic AMP-dependent protein kinase A (PKA) phosphorylates the Inhibitor of Apoptosis (IAP) protein survivin on Ser20 in the cytosol, but not in mitochondria. This phosphorylation event disrupts the binding interface between survivin and its antiapoptotic cofactor, XIAP. Conversely, mitochondrial survivin or a non-PKA phosphorylatable survivin mutant binds XIAP avidly, enhances XIAP stability, synergistically inhibits apoptosis, and accelerates tumor growth, in vivo. Therefore, differential phosphorylation of survivin by PKA in subcellular microdomains regulates tumor cell apoptosis via its interaction with XIAP. PMID:17612487

  15. Modulation of neurosteroid potentiation by protein kinases at synaptic- and extrasynaptic-type GABAA receptors.

    PubMed

    Adams, Joanna M; Thomas, Philip; Smart, Trevor G

    2015-01-01

    GABAA receptors are important for inhibition in the CNS where neurosteroids and protein kinases are potent endogenous modulators. Acting individually, these can either enhance or depress receptor function, dependent upon the type of neurosteroid or kinase and the receptor subunit combination. However, in vivo, these modulators probably act in concert to fine-tune GABAA receptor activity and thus inhibition, although how this is achieved remains unclear. Therefore, we investigated the relationship between these modulators at synaptic-type α1β3γ2L and extrasynaptic-type α4β3δ GABAA receptors using electrophysiology. For α1β3γ2L, potentiation of GABA responses by tetrahydro-deoxycorticosterone was reduced after inhibiting protein kinase C, and enhanced following its activation, suggesting this kinase regulates neurosteroid modulation. In comparison, neurosteroid potentiation was reduced at α1β3(S408A,S409A)γ2L receptors, and unaltered by PKC inhibitors or activators, indicating that phosphorylation of β3 subunits is important for regulating neurosteroid activity. To determine whether extrasynaptic-type GABAA receptors were similarly modulated, α4β3δ and α4β3(S408A,S409A)δ receptors were investigated. Neurosteroid potentiation was reduced at both receptors by the kinase inhibitor staurosporine. By contrast, neurosteroid-mediated potentiation at α4(S443A)β3(S408A,S409A)δ receptors was unaffected by protein kinase inhibition, strongly suggesting that phosphorylation of α4 and β3 subunits is required for regulating neurosteroid activity at extrasynaptic receptors. Western blot analyses revealed that neurosteroids increased phosphorylation of β3(S408,S409) implying that a reciprocal pathway exists for neurosteroids to modulate phosphorylation of GABAA receptors. Overall, these findings provide important insight into the regulation of GABAA receptors in vivo, and into the mechanisms by which GABAergic inhibitory transmission may be simultaneously

  16. Pivotal Role of Mitogen-Activated Protein Kinase-Activated Protein Kinase 2 in Inflammatory Pulmonary Diseases

    PubMed Central

    Qian, Feng; Deng, Jing; Wang, Gang; Ye, Richard D.; Christman, John W.

    2016-01-01

    Mitogen-activated protein kinase (MAPK)-activated protein kinase (MK2) is exclusively regulated by p38 MAPK in vivo. Upon activation of p38 MAPK, MK2 binds with p38 MAPK, leading to phosphorylation of TTP, Hsp27, Akt and Cdc25 that are involved in regulation of various essential cellular functions. In this review, we discuss current knowledge about molecular mechanisms of MK2 in regulation of TNF-α production, NADPH oxidase activation, neutrophil migration, and DNA-damage-induced cell cycle arrest which are involved in the molecular pathogenesis of acute lung injury, pulmonary fibrosis, and non-small-cell lung cancer. Collectively current and emerging new information indicate that developing MK2 inhibitors and blocking MK2-mediated signal pathways is a potential therapeutic strategy for treatment of inflammatory and fibrotic lung diseases and lung cancer. PMID:26119506

  17. Quantitative phosphoproteomics of protein kinase SnRK1 regulated protein phosphorylation in Arabidopsis under submergence

    PubMed Central

    Cho, Hsing-Yi; Wen, Tuan-Nan; Wang, Ying-Tsui; Shih, Ming-Che

    2016-01-01

    SNF1 RELATED PROTEIN KINASE 1 (SnRK1) is proposed to be a central integrator of the plant stress and energy starvation signalling pathways. We observed that the Arabidopsis SnRK1.1 dominant negative mutant (SnRK1.1 K48M) had lower tolerance to submergence than the wild type, suggesting that SnRK1.1-dependent phosphorylation of target proteins is important in signalling pathways triggered by submergence. We conducted quantitative phosphoproteomics and found that the phosphorylation levels of 57 proteins increased and the levels of 27 proteins decreased in Col-0 within 0.5–3h of submergence. Among the 57 proteins with increased phosphorylation in Col-0, 38 did not show increased phosphorylation levels in SnRK1.1 K48M under submergence. These proteins are involved mainly in sugar and protein synthesis. In particular, the phosphorylation of MPK6, which is involved in regulating ROS responses under abiotic stresses, was disrupted in the SnRK1.1 K48M mutant. In addition, PTP1, a negative regulator of MPK6 activity that directly dephosphorylates MPK6, was also regulated by SnRK1.1. We also showed that energy conservation was disrupted in SnRK1.1 K48M, mpk6, and PTP1 S7AS8A under submergence. These results reveal insights into the function of SnRK1 and the downstream signalling factors related to submergence. PMID:27029354

  18. Interacting factors and cellular localization of SR protein-specific kinase Dsk1

    SciTech Connect

    Tang, Zhaohua; Luca, Maria; Taggart-Murphy, Laura; Portillio, Jessica; Chang, Cathey; Guven, Ayse; Lin, Ren-Jang; Murray, Johanne; Carr, Antony

    2012-10-01

    Schizosaccharomyces pombe Dsk1 is an SR protein-specific kinase (SRPK), whose homologs have been identified in every eukaryotic organism examined. Although discovered as a mitotic regulator with protein kinase activity toward SR splicing factors, it remains largely unknown about what and how Dsk1 contributes to cell cycle and pre-mRNA splicing. In this study, we investigated the Dsk1 function by determining interacting factors and cellular localization of the kinase. Consistent with its reported functions, we found that pre-mRNA processing and cell cycle factors are prominent among the proteins co-purified with Dsk1. The identification of these factors led us to find Rsd1 as a novel Dsk1 substrate, as well as the involvement of Dsk1 in cellular distribution of poly(A){sup +} RNA. In agreement with its role in nuclear events, we also found that Dsk1 is mainly localized in the nucleus during G{sub 2} phase and at mitosis. Furthermore, we revealed the oscillation of Dsk1 protein in a cell cycle-dependent manner. This paper marks the first comprehensive analysis of in vivo Dsk1-associated proteins in fission yeast. Our results reflect the conserved role of SRPK family in eukaryotic organisms, and provide information about how Dsk1 functions in pre-mRNA processing and cell-division cycle.

  19. Synthetic sulfoglycolipids targeting the serine-threonine protein kinase Akt.

    PubMed

    Costa, Barbara; Dangate, Milind; Vetro, Maria; Donvito, Giulia; Gabrielli, Luca; Amigoni, Loredana; Cassinelli, Giuliana; Lanzi, Cinzia; Ceriani, Michela; De Gioia, Luca; Filippi, Giulia; Cipolla, Laura; Zaffaroni, Nadia; Perego, Paola; Colombo, Diego

    2016-08-15

    The serine-threonine protein kinase Akt, also known as protein kinase B, is a key component of the phosphoinositide 3-kinase (PI3K)-Akt-mTOR axis. Deregulated activation of this pathway is frequent in human tumors and Akt-dependent signaling appears to be critical in cell survival. PI3K activation generates 3-phosphorylated phosphatidylinositols that bind Akt pleckstrin homology (PH) domain. The blockage of Akt PH domain/phosphoinositides interaction represents a promising approach to interfere with the oncogenic potential of over-activated Akt. In the present study, phosphatidyl inositol mimics based on a β-glucoside scaffold have been synthesized as Akt inhibitors. The compounds possessed one or two lipophilic moieties of different length at the anomeric position of glucose, and an acidic or basic group at C-6. Docking studies, ELISA Akt inhibition assays, and cellular assays on different cell models highlighted 1-O-octadecanoyl-2-O-β-d-sulfoquinovopyranosyl-sn-glycerol as the best Akt inhibitor among the synthesized compounds, which could be considered as a lead for further optimization in the design of Akt inhibitors.

  20. Regulation of cAMP-dependent Protein Kinases

    PubMed Central

    Diskar, Mandy; Zenn, Hans-Michael; Kaupisch, Alexandra; Kaufholz, Melanie; Brockmeyer, Stefanie; Sohmen, Daniel; Berrera, Marco; Zaccolo, Manuela; Boshart, Michael; Herberg, Friedrich W.; Prinz, Anke

    2010-01-01

    cAMP-dependent protein kinases are reversibly complexed with any of the four isoforms of regulatory (R) subunits, which contain either a substrate or a pseudosubstrate autoinhibitory domain. The human protein kinase X (PrKX) is an exemption as it is inhibited only by pseudosubstrate inhibitors, i.e. RIα or RIβ but not by substrate inhibitors RIIα or RIIβ. Detailed examination of the capacity of five PrKX-like kinases ranging from human to protozoa (Trypanosoma brucei) to form holoenzymes with human R subunits in living cells shows that this preference for pseudosubstrate inhibitors is evolutionarily conserved. To elucidate the molecular basis of this inhibitory pattern, we applied bioluminescence resonance energy transfer and surface plasmon resonance in combination with site-directed mutagenesis. We observed that the conserved αH-αI loop residue Arg-283 in PrKX is crucial for its RI over RII preference, as a R283L mutant was able to form a holoenzyme complex with wild type RII subunits. Changing the corresponding αH-αI loop residue in PKA Cα (L277R), significantly destabilized holoenzyme complexes in vitro, as cAMP-mediated holoenzyme activation was facilitated by a factor of 2–4, and lead to a decreased affinity of the mutant C subunit for R subunits, significantly affecting RII containing holoenzymes. PMID:20819953

  1. An autoregulatory region in protein kinase C: the pseudoanchoring site.

    PubMed Central

    Ron, D; Mochly-Rosen, D

    1995-01-01

    We have previously identified receptors for activated C kinase (RACKs) as components of protein kinase C (PKC) signaling. RACK1, a recently cloned 36-kDa RACK, has short sequences of homology to PKC. A possible explanation for the homologous sequences between the ligand (PKC) and its intracellular receptor (RACK1) may be that, similar to the pseudosubstrate autoregulatory sequence on PKC, there is also a pseudo-RACK1 binding site on the enzyme. If this is the case, peptides with these sequences (derived from either RACK1 or PKC) are expected to affect PKC binding to RACK1 in vitro and PKC-mediated functions in vivo. Here, we show that the PKC-derived peptide (pseudo-RACK1 peptide), but not its RACK1 homologue, modulated PKC function both in vitro and in vivo. Our data suggest that the pseudo-RACK1 peptide binds and activates PKC in the absence of PKC activators and thereby acts as an agonist of PKC function in vivo. Therefore, the pseudo-RACK1 sequence in PKC appears to be another autoregulatory site; when PKC is in an inactive conformation, the pseudo-RACK1 site interacts with the RACK-binding site. Activation of PKC exposes the RACK-binding site, enabling the association of the enzyme with its anchoring RACK. Similar pseudoanchoring sites may regulate the function of other protein kinases. Images Fig. 1 Fig. 2 Fig. 3 PMID:7831317

  2. Diacylglycerol kinase regulation of protein kinase D during oxidative stress-induced intestinal cell injury

    SciTech Connect

    Song Jun; Li Jing; Mourot, Joshua M.; Mark Evers, B.; Chung, Dai H.

    2008-10-17

    We recently demonstrated that protein kinase D (PKD) exerts a protective function during oxidative stress-induced intestinal epithelial cell injury; however, the exact role of DAG kinase (DGK){zeta}, an isoform expressed in intestine, during this process is unknown. We sought to determine the role of DGK during oxidative stress-induced intestinal cell injury and whether DGK acts as an upstream regulator of PKD. Inhibition of DGK with R59022 compound or DGK{zeta} siRNA transfection decreased H{sub 2}O{sub 2}-induced RIE-1 cell apoptosis as measured by DNA fragmentation and increased PKD phosphorylation. Overexpression of kinase-dead DGK{zeta} also significantly increased PKD phosphorylation. Additionally, endogenous nuclear DGK{zeta} rapidly translocated to the cytoplasm following H{sub 2}O{sub 2} treatment. Our findings demonstrate that DGK is involved in the regulation of oxidative stress-induced intestinal cell injury. PKD activation is induced by DGK{zeta}, suggesting DGK is an upstream regulator of oxidative stress-induced activation of the PKD signaling pathway in intestinal epithelial cells.

  3. Structure of Escherichia coli tyrosine Kinase Etk Reveals a Novel Activation Mechanism

    SciTech Connect

    Lee,D.; Zheng, J.; She, Y.; Jia, Z.

    2008-01-01

    While protein tyrosine (Tyr) kinases (PTKs) have been extensively characterized in eukaryotes, far less is known about their emerging counterparts in prokaryotes. The inner-membrane Wzc/Etk protein belongs to the bacterial PTK family, which has an important function in regulating the polymerization and transport of virulence-determining capsular polysaccharide (CPS). The kinase uses a unique two-step activation process involving intra-phosphorylation of a Tyr residue, although the molecular mechanism remains unknown. Herein, we report the first crystal structure of a bacterial PTK, the C-terminal kinase domain of Escherichia coli Tyr kinase (Etk) at 2.5-Angstroms resolution. The fold of the Etk kinase domain differs markedly from that of eukaryotic PTKs. Based on the observed structure and supporting mass spectrometric evidence of Etk, a unique activation mechanism is proposed that involves the phosphorylated Tyr residue, Y574, at the active site and its specific interaction with a previously unidentified key Arg residue, R614, to unblock the active site. Both in vitro kinase activity and in vivo antibiotics resistance studies using structure-guided mutants further support the novel activation mechanism.

  4. Activity of protein kinase C-α within the subfornical organ is necessary for fluid intake in response to brain angiotensin.

    PubMed

    Coble, Jeffrey P; Johnson, Ralph F; Cassell, Martin D; Johnson, Alan Kim; Grobe, Justin L; Sigmund, Curt D

    2014-07-01

    Angiotensin-II production in the subfornical organ acting through angiotensin-II type-1 receptors is necessary for polydipsia, resulting from elevated renin-angiotensin system activity. Protein kinase C and mitogen-activated protein kinase pathways have been shown to mediate effects of angiotensin-II in the brain. We investigated mechanisms that mediate brain angiotensin-II-induced polydipsia. We used double-transgenic sRA mice, consisting of human renin controlled by the neuron-specific synapsin promoter crossed with human angiotensinogen controlled by its endogenous promoter, which results in brain-specific overexpression of angiotensin-II, particularly in the subfornical organ. We also used the deoxycorticosterone acetate-salt model of hypertension, which exhibits polydipsia. Inhibition of protein kinase C, but not extracellular signal-regulated kinases, protein kinase A, or vasopressin V₁A and V₂ receptors, corrected the elevated water intake of sRA mice. Using an isoform selective inhibitor and an adenovirus expressing dominant negative protein kinase C-α revealed that protein kinase C-α in the subfornical organ was necessary to mediate elevated fluid and sodium intake in sRA mice. Inhibition of protein kinase C activity also attenuated polydipsia in the deoxycorticosterone acetate-salt model. We provide evidence that inducing protein kinase C activity centrally is sufficient to induce water intake in water-replete wild-type mice, and that cell surface localization of protein kinase C-α can be induced in cultured cells from the subfornical organ. These experimental findings demonstrate a role for central protein kinase C activity in fluid balance, and further mechanistically demonstrate the importance of protein kinase C-α signaling in the subfornical organ in fluid intake stimulated by angiotensin-II in the brain.

  5. Phosphorylation of Human Choline Kinase Beta by Protein Kinase A: Its Impact on Activity and Inhibition

    PubMed Central

    Chang, Ching Ching; Few, Ling Ling; Konrad, Manfred; See Too, Wei Cun

    2016-01-01

    Choline kinase beta (CKβ) is one of the CK isozymes involved in the biosynthesis of phosphatidylcholine. CKβ is important for normal mitochondrial function and muscle development as the lack of the ckβ gene in human and mice results in the development of muscular dystrophy. In contrast, CKα is implicated in tumorigenesis and has been extensively studied as an anticancer target. Phosphorylation of human CKα was found to regulate the enzyme’s activity and its subcellular location. This study provides evidence for CKβ phosphorylation by protein kinase A (PKA). In vitro phosphorylation of CKβ by PKA was first detected by phosphoprotein staining, as well as by in-gel kinase assays. The phosphorylating kinase was identified as PKA by Western blotting. CKβ phosphorylation by MCF-7 cell lysate was inhibited by a PKA-specific inhibitor peptide, and the intracellular phosphorylation of CKβ was shown to be regulated by the level of cyclic adenosine monophosphate (cAMP), a PKA activator. Phosphorylation sites were located on CKβ residues serine-39 and serine-40 as determined by mass spectrometry and site-directed mutagenesis. Phosphorylation increased the catalytic efficiencies for the substrates choline and ATP about 2-fold, without affecting ethanolamine phosphorylation, and the S39D/S40D CKβ phosphorylation mimic behaved kinetically very similar. Remarkably, phosphorylation drastically increased the sensitivity of CKβ to hemicholinium-3 (HC-3) inhibition by about 30-fold. These findings suggest that CKβ, in concert with CKα, and depending on its phosphorylation status, might play a critical role as a druggable target in carcinogenesis. PMID:27149373

  6. Protein-tyrosine Phosphatase and Kinase Specificity in Regulation of SRC and Breast Tumor Kinase* ♦

    PubMed Central

    Fan, Gaofeng; Aleem, Saadat; Yang, Ming; Miller, W. Todd; Tonks, Nicholas K.

    2015-01-01

    Despite significant evidence to the contrary, the view that phosphatases are “nonspecific” still pervades the field. Systems biology approaches to defining how signal transduction pathways are integrated at the level of whole organisms also often downplay the contribution of phosphatases, defining them as “erasers” that serve merely to restore the system to its basal state. Here, we present a study that counteracts the idea of “nonspecific phosphatases.” We have characterized two structurally similar and functionally related kinases, BRK and SRC, which are regulated by combinations of activating autophosphorylation and inhibitory C-terminal sites of tyrosine phosphorylation. We demonstrated specificity at the level of the kinases in that SRMS phosphorylated the C terminus of BRK, but not SRC; in contrast, CSK is the kinase responsible for C-terminal phosphorylation of SRC, but not BRK. For the phosphatases, we observed that RNAi-mediated suppression of PTP1B resulted in opposing effects on the activity of BRK and SRC and have defined the mechanisms underlying this specificity. PTP1B inhibited BRK by directly dephosphorylating the Tyr-342 autophosphorylation site. In contrast, PTP1B potentiated SRC activity, but not by dephosphorylating SRC itself directly; instead, PTP1B regulated the interaction between CBP/PAG and CSK. SRC associated with, and phosphorylated, the transmembrane protein CBP/PAG at Tyr-317, resulting in CSK recruitment. We identified PAG as a substrate of PTP1B, and dephosphorylation abolished recruitment of the inhibitory kinase CSK. Overall, these findings illustrate how the combinatorial effects of PTKs and PTPs may be integrated to regulate signaling, with both classes of enzymes displaying exquisite specificity. PMID:25897081

  7. Activation of p38 Mitogen-Activated Protein Kinase Promotes Epidermal Growth Factor Receptor Internalization

    PubMed Central

    Vergarajauregui, Silvia; Miguel, Anitza San; Puertollano, Rosa

    2006-01-01

    Endocytic trafficking plays an important role in the regulation of the epidermal growth factor receptor (EGFR). To address if cellular kinases regulate EGFR internalization, we used anisomycin, a potent activator of kinase cascades in mammalian cells, especially the stress-activated mitogen-activated protein (MAP) kinase subtypes. Here, we report that activation of p38 MAP kinase by anisomycin is sufficient to induce internalization of EGFR. Anisomycin and EGF employ different mechanisms to promote EGFR endocytosis as anisomycin-induced internalization does not require tyrosine kinase activity or ubiquitination of the receptor. In addition, anisomycin treatment did not result in delivery and degradation of EGFR at lysosomes. Incubation with a specific inhibitor of p38, or depletion of endogenous p38 by small interfering RNAs, abolished anisomycin-induced internalization of EGFR while having no effect on transferrin endocytosis, indicating that the effect of p38 activation on EGFR endocytosis is specific. Interestingly, inhibition of p38 activation also abolished endocytosis of EGFR induced by UV radiation. Our results reveal a novel role for p38 in the regulation of EGFR endocytosis and suggest that stimulation of EGFR internalization by p38 might represent a general mechanism to prevent generation of proliferative or anti-apoptotic signals under stress conditions. PMID:16683917

  8. FAST KINASE DOMAIN-CONTAINING PROTEIN 3 IS A MITOCHONDRIAL PROTEIN ESSENTIAL FOR CELLULAR RESPIRATION

    PubMed Central

    Simarro, Maria; Gimenez-Cassina, Alfredo; Kedersha, Nancy; Lazaro, Jean-Bernard; Adelmant, Guillaume O; Marto, Jarrod A; Rhee, Kirsten; Tisdale, Sarah; Danial, Nika; Benarafa, Charaf; Orduña, Anonio; Anderson, Paul

    2010-01-01

    Fas-activated serine/threonine phosphoprotein (FAST) is the founding member of the FAST kinase domain-containing protein (FASTKD) family that includes FASTKD1-5. FAST is a sensor of mitochondrial stress that modulates protein translation to promote the survival of cells exposed to adverse conditions. Mutations in FASTKD2 have been linked to a mitochondrial encephalomyopathy that is associated with reduced cytochrome c oxidase activity, an essential component of the mitochondrial electron transport chain. We have confirmed the mitochondrial localization of FASTKD2 and shown that all FASTKD family members are found in mitochondria. Although human and mouse FASTKD1-5 genes are expressed ubiquitously, some of them are most abundantly expressed in mitochondria-enriched tissues. We have found that RNA interference-mediated knockdown of FASTKD3 severely blunts basal and stress-induced mitochondrial oxygen consumption without disrupting the assembly of respiratory chain complexes. Tandem affinity purification reveals that FASTKD3 interacts with components of mitochondrial respiratory and translation machineries. Our results introduce FASTKD3 as an essential component of mitochondrial respiration that may modulate energy balance in cells exposed to adverse conditions by functionally coupling mitochondrial protein synthesis to respiration. PMID:20869947

  9. The calcium-dependent protein kinase CPK7 acts on root hydraulic conductivity.

    PubMed

    Li, Guowei; Boudsocq, Marie; Hem, Sonia; Vialaret, Jérôme; Rossignol, Michel; Maurel, Christophe; Santoni, Véronique

    2015-07-01

    The hydraulic conductivity of plant roots (Lp(r)) is determined in large part by the activity of aquaporins. Mechanisms occurring at the post-translational level, in particular phosphorylation of aquaporins of the plasma membrane intrinsic protein 2 (PIP2) subfamily, are thought to be of critical importance for regulating root water transport. However, knowledge of protein kinases and phosphatases acting on aquaporin function is still scarce. In the present work, we investigated the Lp(r) of knockout Arabidopsis plants for four Ca(2+)-dependent protein kinases. cpk7 plants showed a 30% increase in Lp(r) because of a higher aquaporin activity. A quantitative proteomic analysis of wild-type and cpk7 plants revealed that PIP gene expression and PIP protein quantity were not correlated and that CPK7 has no effect on PIP2 phosphorylation. In contrast, CPK7 exerts a negative control on the cellular abundance of PIP1s, which likely accounts for the higher Lp(r) of cpk7. In addition, this study revealed that the cellular amount of a few additional proteins including membrane transporters is controlled by CPK7. The overall work provides evidence for CPK7-dependent stability of specific membrane proteins. PMID:25366820

  10. Mitogen-activated protein kinase cascades in signaling plant growth and development.

    PubMed

    Xu, Juan; Zhang, Shuqun

    2015-01-01

    Mitogen-activated protein kinase (MAPK) cascades are ubiquitous signaling modules in eukaryotes. Early research of plant MAPKs has been focused on their functions in immunity and stress responses. Recent studies reveal that they also play essential roles in plant growth and development downstream of receptor-like protein kinases (RLKs). With only a limited number of MAPK components, multiple functional pathways initiated from different receptors often share the same MAPK components or even a complete MAPK cascade. In this review, we discuss how MAPK cascades function as molecular switches in response to spatiotemporal-specific ligand-receptor interactions and the availability of downstream substrates. In addition, we discuss other possible mechanisms governing the functional specificity of plant MAPK cascades, a question central to our understanding of MAPK functions.

  11. Analysis of protein kinase C requirement for exocytosis in permeabilized rat basophilic leukaemia RBL-2H3 cells: a GTP-binding protein(s) as a potential target for protein kinase C.

    PubMed Central

    Buccione, R; Di Tullio, G; Caretta, M; Marinetti, M R; Bizzarri, C; Francavilla, S; Luini, A; De Matteis, M A

    1994-01-01

    The role of protein kinase C in calcium-dependent exocytosis was investigated in permeabilized rat basophilic leukaemia cells. When protein kinase C was down-regulated by phorbol myristate acetate (1 microM for 3-6 h) or inhibited by pharmacological agents such as calphostin C (1 microM) or a protein kinase C-specific pseudo-substrate peptide inhibitor (100-200 microM), cells lost the ability to secrete in response to 10 microM free Ca2+. In contrast, a short treatment (15 min) with phorbol myristate acetate, which maximally activates protein kinase C, potentiated the effects of calcium. Biochemical analysis of protein kinase C-deprived cells indicated that loss of the Ca(2+)-induced secretory response correlated with disappearance of protein kinase C-alpha. In addition, at the concentrations effective for exocytosis, calcium caused translocation of protein kinase C-alpha to the membrane fraction and stimulated phospholipase C, suggesting that, in permeabilized cells, protein kinase C can be activated by calcium through generation of the phospholipase C metabolite diacylglycerol. The delta, epsilon and zeta Ca(2+)-independent protein kinase C isoenzymes were insensitive to phorbol myristate acetate-induced down-regulation and did not, as expected, translocate to the particulate fraction in response to calcium. Interestingly, secretory competence was restored in cells depleted of protein kinase C or in which protein kinase C itself was inhibited by non-hydrolysable GTP analogues, but not by GTP, suggesting that protein kinase C might regulate the ability of a G protein(s) directly controlling the exocytotic machinery to be activated by endogenous GTP. Images Figure 1 Figure 4 Figure 5 PMID:8129713

  12. Calcium-Oxidant Signaling Network Regulates AMP-activated Protein Kinase (AMPK) Activation upon Matrix Deprivation*

    PubMed Central

    Sundararaman, Ananthalakshmy; Amirtham, Usha; Rangarajan, Annapoorni

    2016-01-01

    The AMP-activated protein kinase (AMPK) has recently been implicated in anoikis resistance. However, the molecular mechanisms that activate AMPK upon matrix detachment remain unexplored. In this study, we show that AMPK activation is a rapid and sustained phenomenon upon matrix deprivation, whereas re-attachment to the matrix leads to its dephosphorylation and inactivation. Because matrix detachment leads to loss of integrin signaling, we investigated whether integrin signaling negatively regulates AMPK activation. However, modulation of focal adhesion kinase or Src, the major downstream components of integrin signaling, failed to cause a corresponding change in AMPK signaling. Further investigations revealed that the upstream AMPK kinases liver kinase B1 (LKB1) and Ca2+/calmodulin-dependent protein kinase kinase β (CaMKKβ) contribute to AMPK activation upon detachment. In LKB1-deficient cells, we found AMPK activation to be predominantly dependent on CaMKKβ. We observed no change in ATP levels under detached conditions at early time points suggesting that rapid AMPK activation upon detachment was not triggered by energy stress. We demonstrate that matrix deprivation leads to a spike in intracellular calcium as well as oxidant signaling, and both these intracellular messengers contribute to rapid AMPK activation upon detachment. We further show that endoplasmic reticulum calcium release-induced store-operated calcium entry contributes to intracellular calcium increase, leading to reactive oxygen species production, and AMPK activation. We additionally show that the LKB1/CaMKK-AMPK axis and intracellular calcium levels play a critical role in anchorage-independent cancer sphere formation. Thus, the Ca2+/reactive oxygen species-triggered LKB1/CaMKK-AMPK signaling cascade may provide a quick, adaptable switch to promote survival of metastasizing cancer cells. PMID:27226623

  13. Biochemical and genetic defects in the DNA-dependent protein kinase in murine scid lymphocytes.

    PubMed Central

    Danska, J S; Holland, D P; Mariathasan, S; Williams, K M; Guidos, C J

    1996-01-01

    The scid gene product has been identified as the 460-kDa catalytic subunit of the DNA-dependent protein kinase (DNA-PKcs p460), a member of the phosphatidylinositol 3-kinase family. DNA-PK activity is undetectable in scid cells, but the molecular basis for this defect has not been identified. Here we report that expression of p460 in scid lymphocyte precursors is detectable but is reduced at least 10-fold relative to that in wild-type lymphocytes. In addition, we show that the scid mutation disturbs p460 nuclear association, presumably affecting its role in DNA repair pathways. To examine the molecular basis for our observations, we used a degenerate PCR strategy to clone the C-terminal p460 kinase domain from wild-type and scid thymocytes. Northern (RNA) analysis with these probes revealed normal steady-state p460 mRNA levels in scid cells, suggesting that the reduced abundance of p460 protein is due to a posttranscriptional defect. Sequence comparisons identified a single-base-pair alteration in the scid C-terminal p460 kinase domain, resulting in a premature stop codon. This mutation is predicted to truncate p460 by approximately 8 kDa, but it preserves the conserved motifs required for kinase activity in members of the phosphoinositidyl 3-kinase family. Despite a computed molecular weight alteration of less than 2%, we were able to visualize this difference by Western blot (immunoblot) analysis of wild-type and scid p460. These data demonstrate that the scid DNA-PKes mutation is not a null allele and suggest a molecular rationale for the well-described leakiness of the scid phenotype. PMID:8816463

  14. Negative regulation of cyclin-dependent kinase 5 targets by protein kinase C

    PubMed Central

    Sahin, Bogachan; Hawasli, Ammar H.; Greene, Robert W.; Molkentin, Jeffery D.; Bibb, James A.

    2008-01-01

    Cyclin-dependent kinase 5 (Cdk5) is a proline-directed protein serine/threonine kinase essential for brain development and implicated in synaptic plasticity, dopaminergic neurotransmission, drug addiction, and neurodegenerative disorders. Relatively little is known about the molecular mechanisms that regulate the activity of Cdk5 in vivo. In order to determine whether protein kinase C (PKC) regulates Cdk5 activity in the central nervous system, the phosphorylation levels of two Cdk5 substrates were evaluated under conditions of altered PKC activity in vivo. Treatment of acute striatal slices with a PKC-activating phorbol ester caused a time- and dose-dependent decrease in the levels of phospho-Ser6 inhibitor-1, phospho-Ser67 inhibitor-1, and phospho-Thr75 dopamine- and cAMP-regulated phosphoprotein, Mr 32,000 (DARPP-32). This effect was reversed by the PKC inhibitor, Ro-32-0432. Moreover, phospho-Ser6 inhibitor-1, phospho-Ser67 inhibitor-1, and phospho-Thr75 DARPP-32 levels were elevated in brain tissue from mice lacking the gene for PKC-α. PKC did not phosphorylate Cdk5 or its cofactor, p25, in vitro. Striatal levels of the Cdk5 cofactor, p35, did not change in response to phorbol ester treatment. Furthermore, Cdk5 immunoprecipitated from striatal slices treated with phorbol ester had unaltered activity toward a control substrate in vitro. These results suggest that PKC exerts its effects on the phosphorylation state of Cdk5 substrates through an indirect mechanism that may involve the regulatory binding partners of Cdk5 other than its neuronal cofactors. PMID:18190909

  15. Negative regulation of cyclin-dependent kinase 5 targets by protein kinase C.

    PubMed

    Sahin, Bogachan; Hawasli, Ammar H; Greene, Robert W; Molkentin, Jeffery D; Bibb, James A

    2008-03-10

    Cyclin-dependent kinase 5 (Cdk5) is a proline-directed protein serine/threonine kinase essential for brain development and implicated in synaptic plasticity, dopaminergic neurotransmission, drug addiction, and neurodegenerative disorders. Relatively little is known about the molecular mechanisms that regulate the activity of Cdk5 in vivo. In order to determine whether protein kinase C (PKC) regulates Cdk5 activity in the central nervous system, the phosphorylation levels of two Cdk5 substrates were evaluated under conditions of altered PKC activity in vivo. Treatment of acute striatal slices with a PKC-activating phorbol ester caused a time- and dose-dependent decrease in the levels of phospho-Ser6 inhibitor-1, phospho-Ser67 inhibitor-1, and phospho-Thr75 dopamine- and cAMP-regulated phosphoprotein, Mr 32,000 (DARPP-32). This effect was reversed by the PKC inhibitor, Ro-32-0432. Moreover, phospho-Ser6 inhibitor-1, phospho-Ser67 inhibitor-1, and phospho-Thr75 DARPP-32 levels were elevated in brain tissue from mice lacking the gene for PKC-alpha. PKC did not phosphorylate Cdk5 or its cofactor, p25, in vitro. Striatal levels of the Cdk5 cofactor, p35, did not change in response to phorbol ester treatment. Furthermore, Cdk5 immunoprecipitated from striatal slices treated with phorbol ester had unaltered activity toward a control substrate in vitro. These results suggest that PKC exerts its effects on the phosphorylation state of Cdk5 substrates through an indirect mechanism that may involve the regulatory binding partners of Cdk5 other than its neuronal cofactors.

  16. Competition between members of the tribbles pseudokinase protein family shapes their interactions with mitogen activated protein kinase pathways.

    PubMed

    Guan, Hongtao; Shuaib, Aban; Leon, David Davila De; Angyal, Adrienn; Salazar, Maria; Velasco, Guillermo; Holcombe, Mike; Dower, Steven K; Kiss-Toth, Endre

    2016-01-01

    Spatio-temporal regulation of intracellular signalling networks is key to normal cellular physiology; dysregulation of which leads to disease. The family of three mammalian tribbles proteins has emerged as an important controller of signalling via regulating the activity of mitogen activated protein kinases (MAPK), the PI3-kinase induced signalling network and E3 ubiquitin ligases. However, the importance of potential redundancy in the action of tribbles and how the differences in affinities for the various binding partners may influence signalling control is currently unclear. We report that tribbles proteins can bind to an overlapping set of MAPK-kinases (MAPKK) in live cells and dictate the localisation of the complexes. Binding studies in transfected cells reveal common regulatory mechanisms and suggest that tribbles and MAPKs may interact with MAPKKs in a competitive manner. Computational modelling of the impact of tribbles on MAPK activation suggests a high sensitivity of this system to changes in tribbles levels, highlighting that these proteins are ideally placed to control the dynamics and balance of activation of concurrent signalling pathways. PMID:27600771

  17. Competition between members of the tribbles pseudokinase protein family shapes their interactions with mitogen activated protein kinase pathways

    PubMed Central

    Guan, Hongtao; Shuaib, Aban; Leon, David Davila De; Angyal, Adrienn; Salazar, Maria; Velasco, Guillermo; Holcombe, Mike; Dower, Steven K.; Kiss-Toth, Endre

    2016-01-01

    Spatio-temporal regulation of intracellular signalling networks is key to normal cellular physiology; dysregulation of which leads to disease. The family of three mammalian tribbles proteins has emerged as an important controller of signalling via regulating the activity of mitogen activated protein kinases (MAPK), the PI3-kinase induced signalling network and E3 ubiquitin ligases. However, the importance of potential redundancy in the action of tribbles and how the differences in affinities for the various binding partners may influence signalling control is currently unclear. We report that tribbles proteins can bind to an overlapping set of MAPK-kinases (MAPKK) in live cells and dictate the localisation of the complexes. Binding studies in transfected cells reveal common regulatory mechanisms and suggest that tribbles and MAPKs may interact with MAPKKs in a competitive manner. Computational modelling of the impact of tribbles on MAPK activation suggests a high sensitivity of this system to changes in tribbles levels, highlighting that these proteins are ideally placed to control the dynamics and balance of activation of concurrent signalling pathways. PMID:27600771

  18. Association of mitogen-activated protein kinases with microtubules in mouse macrophages

    PubMed Central

    1996-01-01

    Taxol, a microtubule-binding diterpene, mimics many effects of lipopolysaccharide (LPS) on mouse macrophages. The LPS-mimetic effects of taxol appear to be under the same genetic control as responses to LPS itself. Thus we have postulated a role for microtubule-associated proteins (MAP) in the response of macrophages to LPS. Stimulation of macrophages by LPS quickly induces the activation of mitogen-activated protein kinases (MAPK). MAPK are generally considered cytosolic enzymes. Herein we report that much of the LPS-activatable pool of MAPK in primary mouse peritoneal macrophages is microtubule associated. By immunofluorescence, MAPK were localized to colchicine- and nocodazole- disruptible filaments. From both mouse brain and RAW 264.7 macrophages, MAPK could be coisolated with polymerized tubulin. Fractionation of primary macrophages into cytosol-, microfilament-, microtubule-, and intermediated filament-rich extracts revealed that approximately 10% of MAPK but none of MAPK kinase (MEK1A and MEK2) was microtubule bound. Exposure of macrophages to LPS did not change the proportion of MAPK bound to microtubules, but preferentially activated the microtubule- associated pool. These findings confirm the prediction that LPS activates a kinase bound to microtubules. Together with LPS-mimetic actions of taxol and the shared genetic control of responses to LPS and taxol, these results support the hypothesis that a major LPS-signaling pathway in mouse macrophages may involve activation of one or more microtubule-associated kinases. PMID:8666946

  19. Inhibitory effects of homeodomain-interacting protein kinase 2 on the aorta-gonad-mapharsen hematopoiesis

    SciTech Connect

    Ohtsu, Naoki; Nobuhisa, Ikuo; Mochita, Miyuki; Taga, Tetsuya . E-mail: taga@kaiju.medic.kumamoto-u.ac.jp

    2007-01-01

    Definitive hematopoiesis starts in the aorta-gonad-mesonephros (AGM) region of the mouse embryo. Our previous studies revealed that STAT3, a gp130 downstream transcription factor, is required for AGM hematopoiesis and that homeodomain-interacting protein kinase 2 (HIPK2) phosphorylates serine-727 of STAT3. HIPK2 is a serine/threonine kinase known to be involved in transcriptional repression and apoptosis. In the present study, we examined the role of HIPK2 in hematopoiesis in mouse embryo. HIPK2 transcripts were found in fetal hematopoietic tissues such as the mouse AGM region and fetal liver. In cultured AGM cells, HIPK2 protein was detected in adherent cells. Functional analyses of HIPK2 were carried out by introducing wild-type and mutant HIPK2 constructs into AGM cultures. Production of CD45{sup +} hematopoietic cells was suppressed by forced expression of HIPK2 in AGM cultures. This suppression required the kinase domain and nuclear localization signals of HIPK2, but the kinase activity was dispensable. HIPK2-overexpressing AGM-derived nonadherent cells did not form cobblestone-like colonies in cultures with stromal cells. Furthermore, overexpression of HIPK2 in AGM cultures impeded the expansion of CD45{sup low}c-Kit{sup +} cells, which exhibit the immature hematopoietic progenitor phenotype. These data indicate that HIPK2 plays a negative regulatory role in AGM hematopoiesis in the mouse embryo.

  20. Genome-Wide Identification, Evolution, and Co-expression Network Analysis of Mitogen-Activated Protein Kinase Kinase Kinases in Brachypodium distachyon

    PubMed Central

    Feng, Kewei; Liu, Fuyan; Zou, Jinwei; Xing, Guangwei; Deng, Pingchuan; Song, Weining; Tong, Wei; Nie, Xiaojun

    2016-01-01

    Mitogen-activated protein kinase (MAPK) cascades are the conserved and universal signal transduction modules in all eukaryotes, which play the vital roles in plant growth, development, and in response to multiple stresses. In this study, we used bioinformatics methods to identify 86 MAPKKK protein encoded by 73 MAPKKK genes in Brachypodium. Phylogenetic analysis of MAPKKK family from Arabidopsis, rice, and Brachypodium has classified them into three subfamilies, of which 28 belonged to MEKK, 52 to Raf, and 6 to ZIK subfamily, respectively. Conserved protein motif, exon-intron organization, and splicing intron phase in kinase domains supported the evolutionary relationships inferred from the phylogenetic analysis. And gene duplication analysis suggested the chromosomal segment duplication happened before the divergence of the rice and Brachypodium, while all of three tandem duplicated gene pairs happened after their divergence. We further demonstrated that the MAPKKKs have evolved under strong purifying selection, implying the conservation of them. The splicing transcripts expression analysis showed that the splicesome translating longest protein tended to be adopted. Furthermore, the expression analysis of BdMAPKKKs in different organs and development stages as well as heat, virus and drought stresses revealed that the MAPKKK genes were involved in various signaling pathways. And the circadian analysis suggested there were 41 MAPKKK genes in Brachypodium showing cycled expression in at least one condition, of which seven MAPKKK genes expressed in all conditions and the promoter analysis indicated these genes possessed many cis-acting regulatory elements involved in circadian and light response. Finally, the co-expression network of MAPK, MAPKK, and MAPKKK in Brachypodium was constructed using 144 microarray and RNA-seq datasets, and ten potential MAPK cascades pathway were predicted. To conclude, our study provided the important information for evolutionary and

  1. Genome-Wide Identification, Evolution, and Co-expression Network Analysis of Mitogen-Activated Protein Kinase Kinase Kinases in Brachypodium distachyon

    PubMed Central

    Feng, Kewei; Liu, Fuyan; Zou, Jinwei; Xing, Guangwei; Deng, Pingchuan; Song, Weining; Tong, Wei; Nie, Xiaojun

    2016-01-01

    Mitogen-activated protein kinase (MAPK) cascades are the conserved and universal signal transduction modules in all eukaryotes, which play the vital roles in plant growth, development, and in response to multiple stresses. In this study, we used bioinformatics methods to identify 86 MAPKKK protein encoded by 73 MAPKKK genes in Brachypodium. Phylogenetic analysis of MAPKKK family from Arabidopsis, rice, and Brachypodium has classified them into three subfamilies, of which 28 belonged to MEKK, 52 to Raf, and 6 to ZIK subfamily, respectively. Conserved protein motif, exon-intron organization, and splicing intron phase in kinase domains supported the evolutionary relationships inferred from the phylogenetic analysis. And gene duplication analysis suggested the chromosomal segment duplication happened before the divergence of the rice and Brachypodium, while all of three tandem duplicated gene pairs happened after their divergence. We further demonstrated that the MAPKKKs have evolved under strong purifying selection, implying the conservation of them. The splicing transcripts expression analysis showed that the splicesome translating longest protein tended to be adopted. Furthermore, the expression analysis of BdMAPKKKs in different organs and development stages as well as heat, virus and drought stresses revealed that the MAPKKK genes were involved in various signaling pathways. And the circadian analysis suggested there were 41 MAPKKK genes in Brachypodium showing cycled expression in at least one condition, of which seven MAPKKK genes expressed in all conditions and the promoter analysis indicated these genes possessed many cis-acting regulatory elements involved in circadian and light response. Finally, the co-expression network of MAPK, MAPKK, and MAPKKK in Brachypodium was constructed using 144 microarray and RNA-seq datasets, and ten potential MAPK cascades pathway were predicted. To conclude, our study provided the important information for evolutionary and

  2. The Cytoplasmic Adaptor Protein Dok7 Activates the Receptor Tyrosine Kinase MuSK via Dimerization

    SciTech Connect

    Bergamin, E.; Hallock, P; Burden, S; Hubbard, S

    2010-01-01

    Formation of the vertebrate neuromuscular junction requires, among others proteins, Agrin, a neuronally derived ligand, and the following muscle proteins: LRP4, the receptor for Agrin; MuSK, a receptor tyrosine kinase (RTK); and Dok7 (or Dok-7), a cytoplasmic adaptor protein. Dok7 comprises a pleckstrin-homology (PH) domain, a phosphotyrosine-binding (PTB) domain, and C-terminal sites of tyrosine phosphorylation. Unique among adaptor proteins recruited to RTKs, Dok7 is not only a substrate of MuSK, but also an activator of MuSK's kinase activity. Here, we present the crystal structure of the Dok7 PH-PTB domains in complex with a phosphopeptide representing the Dok7-binding site on MuSK. The structure and biochemical data reveal a dimeric arrangement of Dok7 PH-PTB that facilitates trans-autophosphorylation of the kinase activation loop. The structure provides the molecular basis for MuSK activation by Dok7 and for rationalizing several Dok7 loss-of-function mutations found in patients with congenital myasthenic syndromes.

  3. Photoswitchable diacylglycerols enable optical control of protein kinase C.

    PubMed

    Frank, James Allen; Yushchenko, Dmytro A; Hodson, David J; Lipstein, Noa; Nagpal, Jatin; Rutter, Guy A; Rhee, Jeong-Seop; Gottschalk, Alexander; Brose, Nils; Schultz, Carsten; Trauner, Dirk

    2016-09-01

    Increased levels of the second messenger lipid diacylglycerol (DAG) induce downstream signaling events including the translocation of C1-domain-containing proteins toward the plasma membrane. Here, we introduce three light-sensitive DAGs, termed PhoDAGs, which feature a photoswitchable acyl chain. The PhoDAGs are inactive in the dark and promote the translocation of proteins that feature C1 domains toward the plasma membrane upon a flash of UV-A light. This effect is quickly reversed after the termination of photostimulation or by irradiation with blue light, permitting the generation of oscillation patterns. Both protein kinase C and Munc13 can thus be put under optical control. PhoDAGs control vesicle release in excitable cells, such as mouse pancreatic islets and hippocampal neurons, and modulate synaptic transmission in Caenorhabditis elegans. As such, the PhoDAGs afford an unprecedented degree of spatiotemporal control and are broadly applicable tools to study DAG signaling. PMID:27454932

  4. ATP-competitive inhibitors block protein kinase recruitment to the Hsp90-Cdc37 system.

    PubMed

    Polier, Sigrun; Samant, Rahul S; Clarke, Paul A; Workman, Paul; Prodromou, Chrisostomos; Pearl, Laurence H

    2013-05-01

    Protein kinase clients are recruited to the Hsp90 molecular chaperone system via Cdc37, which simultaneously binds Hsp90 and kinases and regulates the Hsp90 chaperone cycle. Pharmacological inhibition of Hsp90 in vivo results in degradation of kinase clients, with a therapeutic effect in dependent tumors. We show here that Cdc37 directly antagonizes ATP binding to client kinases, suggesting a role for the Hsp90-Cdc37 complex in controlling kinase activity. Unexpectedly, we find that Cdc37 binding to protein kinases is itself antagonized by ATP-competitive kinase inhibitors, including vemurafenib and lapatinib. In cancer cells, these inhibitors deprive oncogenic kinases such as B-Raf and ErbB2 of access to the Hsp90-Cdc37 complex, leading to their degradation. Our results suggest that at least part of the efficacy of ATP-competitive inhibitors of Hsp90-dependent kinases in tumor cells may be due to targeted chaperone deprivation.

  5. Quantitative proteome profiling of human myoma and myometrium tissue reveals kinase expression signatures with potential for therapeutic intervention.

    PubMed

    Lemeer, Simone; Gholami, Amin Moghaddas; Wu, Zhixiang; Kuster, Bernhard

    2015-01-01

    Uterine leiomyomas are benign tumors affecting a large proportion of the female population. Despite the very high prevalence, the molecular basis for understanding the onset and development of the disease are still poorly understood. In this study, we profiled the proteomes and kinomes of leiomyoma as well as myometrium samples from patients to a depth of >7000 proteins including 200 kinases. Statistical analysis identified a number of molecular signatures distinguishing healthy from diseased tissue. Among these, nine kinases (ADCK4, CDK5, CSNK2B, DDR1, EPHB1, MAP2K2, PRKCB, PRKG1, and RPS6KA5) representing a number of cellular signaling pathways showed particularly strong discrimination potential. Preliminary statistical analysis by receiver operator characteristics plots revealed very good performance for individual kinases (area under the curve, AUC of 0.70-0.94) as well as binary combinations thereof (AUC 0.70-1.00) that might be used to assess the activity of signaling pathways in myomas. Of note, the receptor tyrosine kinase DDR1 holds future potential as a drug target owing to its strong links to collagen signaling and the excessive formation of extracellular matrix typical for leiomyomas in humans. PMID:25327614

  6. Disease Phenotypes in a Mouse Model of RNA Toxicity Are Independent of Protein Kinase Cα and Protein Kinase

    PubMed Central

    Kim, Yun K.; Yadava, Ramesh S.; Mandal, Mahua; Mahadevan, Karunasai; Yu, Qing; Leitges, Michael; Mahadevan, Mani S.

    2016-01-01

    Myotonic dystrophy type 1(DM1) is the prototype for diseases caused by RNA toxicity. RNAs from the mutant allele contain an expanded (CUG)n tract within the 3' untranslated region of the dystrophia myotonica protein kinase (DMPK) gene. The toxic RNAs affect the function of RNA binding proteins leading to sequestration of muscleblind-like (MBNL) proteins and increased levels of CELF1 (CUGBP, Elav-like family member 1). The mechanism for increased CELF1 is not very clear. One favored proposition is hyper-phosphorylation of CELF1 by Protein Kinase C alpha (PKCα) leading to increased CELF1 stability. However, most of the evidence supporting a role for PKC-α relies on pharmacological inhibition of PKC. To further investigate the role of PKCs in the pathogenesis of RNA toxicity, we generated transgenic mice with RNA toxicity that lacked both the PKCα and PKCβ isoforms. We find that these mice show similar disease progression as mice wildtype for the PKC isoforms. Additionally, the expression of CELF1 is also not affected by deficiency of PKCα and PKCβ in these RNA toxicity mice. These data suggest that disease phenotypes of these RNA toxicity mice are independent of PKCα and PKCβ. PMID:27657532

  7. Structure and functions of plant calcium-dependent protein kinases.

    PubMed

    Klimecka, Maria; Muszyńska, Grazyna

    2007-01-01

    Calcium ions as second messengers play an essential role in many important cellular processes. In plants, transient changes in calcium content in the cytosol (calcium signatures) have been observed during growth, development and under stress conditions. Such diverse functions require many different calcium sensors. One of the largest and most differentiated group of calcium sensors are protein kinases, among them calcium-dependent protein kinases (CDPKs) which were identified only in plants and protists. CDPKs have a regulatory domain which is able to bind calcium ions. For regulation of CDPKs activities not only calcium ions but also specific phospholipids and autophosphorylation are responsible. CDPKs have many different substrates, which reflects the diversity of their functions. Potential protein substrates of CDPK are involved in carbon and nitrogen metabolism, phospholipid synthesis, defense responses, ion and water transport, cytoskeleton organization, transcription and hormone responses. Presently, participation of CDPKs in stress signal transduction pathways (e.g., cold, drought, high salinity, wounding) is intensively studied in many laboratories. An intriguing, but still not fully clarified problem is the cross-talk via CDPKs among different signaling pathways that enables signal integration at different levels and ensure appropriate downstream responses.

  8. (Na+ + K+)-ATPase Is a Target for Phosphoinositide 3-Kinase/Protein Kinase B and Protein Kinase C Pathways Triggered by Albumin*

    PubMed Central

    Peruchetti, Diogo B.; Pinheiro, Ana Acacia S.; Landgraf, Sharon S.; Wengert, Mira; Takiya, Christina M.; Guggino, William B.; Caruso-Neves, Celso

    2011-01-01

    In recent decades, evidence has confirmed the crucial role of albumin in the progression of renal disease. However, the possible role of signaling pathways triggered by physiologic concentrations of albumin in the modulation of proximal tubule (PT) sodium reabsorption has not been considered. In the present work, we have shown that a physiologic concentration of albumin increases the expression of the α1 subunit of (Na+ + K+)-ATPase in LLC-PK1 cells leading to an increase in enzyme activity. This process involves the sequential activation of PI3K/protein kinase B and protein kinase C pathways promoting inhibition of protein kinase A. This integrative network is inhibited when albumin concentration is increased, similar to renal disease, leading to a decrease in the α1 subunit of (Na+ + K+)-ATPase expression. Together, the results indicate that variation in albumin concentration in PT cells has an important effect on PT sodium reabsorption and, consequently, on renal sodium excretion. PMID:22057272

  9. Structural insight into nucleotide recognition by human death-associated protein kinase

    SciTech Connect

    McNamara, Laurie K.; Watterson, D. Martin; Brunzelle, Joseph S.

    2009-03-01

    The crystal structures of DAPK–ADP–Mg{sup 2+} and DAPK–AMP-PNP–Mg{sup 2+} complexes were determined at 1.85 and 2.00 Å resolution, respectively. Comparison of the two nucleotide-bound states with apo DAPK revealed localized changes in the glycine-rich loop region that were indicative of a transition from a more open state to a more closed state on binding of the nucleotide substrate and to an intermediate state with the bound nucleotide product. Death-associated protein kinase (DAPK) is a member of the Ca{sup 2+}/calmodulin-regulated family of serine/threonine protein kinases. The role of the kinase activity of DAPK in eukaryotic cell apoptosis and the ability of bioavailable DAPK inhibitors to rescue neuronal death after brain injury have made it a drug-discovery target for neurodegenerative disorders. In order to understand the recognition of nucleotides by DAPK and to gain insight into DAPK catalysis, the crystal structure of human DAPK was solved in complex with ADP and Mg{sup 2+} at 1.85 Å resolution. ADP is a product of the kinase reaction and product release is considered to be the rate-limiting step of protein kinase catalytic cycles. The structure of DAPK–ADP–Mg{sup 2+} was compared with a newly determined DAPK–AMP-PNP–Mg{sup 2+} structure and the previously determined apo DAPK structure (PDB code http://scripts.iucr.org/cgi-bin/cr.cgi?rm). The comparison shows that nucleotide-induced changes are localized to the glycine-rich loop region of DAPK.

  10. Protein kinase A dependent membrane protein phosphorylation and chloride conductance in endosomal vesicles from kidney cortex

    SciTech Connect

    Reenstra, W.W.; Bae, H.R.; Verkman, A.S. Univ. of California, San Francisco ); Sabolic, I. Harvard Medical School, Charlestown, MA )

    1992-01-14

    Regulation of Cl conductance by protein kinase A action, cell-free measurements of Cl transport and membrane protein phosphorylation were carried out in apical endocytic vesicles from rabbit kidney proximal tubule. Cl transport was measured by a stopped-flow quenching assay in endosomes labeled in vivo with the fluorescent Cl indicator 6-methoxy-N-(3-sulfopropyl)quinolinium. Phosphorylation was studied in a purified endosomal preparation by SDS-PAGE and autoradiography of membrane proteins labeled by ({gamma}-{sup 32}P)ATP. These results suggest that, in a cell-free system, protein kinase A increases Cl conductance in endosomes from kidney proximal tubule by a phosphorylation mechanism. The labeled protein has a size similar to that of the 64-kDa putative kidney Cl channel reported by Landry et al. but is much smaller than the {approximately}170-kDa cystic fibrosis transmembrane conductance regulatory protein.

  11. Phosphorylation of polynucleotide kinase/ phosphatase by DNA-dependent protein kinase and ataxia-telangiectasia mutated regulates its association with sites of DNA damage

    PubMed Central

    Zolner, Angela E.; Abdou, Ismail; Ye, Ruiqiong; Mani, Rajam S.; Fanta, Mesfin; Yu, Yaping; Douglas, Pauline; Tahbaz, Nasser; Fang, Shujuan; Dobbs, Tracey; Wang, Chen; Morrice, Nick; Hendzel, Michael J.; Lees-Miller, Susan P.

    2011-01-01

    Human polynucleotide kinase/phosphatase (PNKP) is a dual specificity 5′-DNA kinase/3′-DNA phosphatase, with roles in base excision repair, DNA single-strand break repair and non-homologous end joining (NHEJ); yet precisely how PNKP functions in the repair of DNA double strand breaks (DSBs) remains unclear. We demonstrate that PNKP is phosphorylated by the DNA-dependent protein kinase (DNA-PK) and ataxia-telangiectasia mutated (ATM) in vitro. The major phosphorylation site for both kinases was serine 114, with serine 126 being a minor site. Ionizing radiation (IR)-induced phosphorylation of cellular PNKP on S114 was ATM dependent, whereas phosphorylation of PNKP on S126 required both ATM and DNA-PK. Inactivation of DNA-PK and/or ATM led to reduced PNKP at DNA damage sites in vivo. Cells expressing PNKP with alanine or aspartic acid at serines 114 and 126 were modestly radiosensitive and IR enhanced the association of PNKP with XRCC4 and DNA ligase IV; however, this interaction was not affected by mutation of PNKP phosphorylation sites. Purified PNKP protein with mutation of serines 114 and 126 had decreased DNA kinase and DNA phosphatase activities and reduced affinity for DNA in vitro. Together, our results reveal that IR-induced phosphorylation of PNKP by ATM and DNA-PK regulates PNKP function at DSBs. PMID:21824916

  12. Phosphorylation of polynucleotide kinase/ phosphatase by DNA-dependent protein kinase and ataxia-telangiectasia mutated regulates its association with sites of DNA damage.

    PubMed

    Zolner, Angela E; Abdou, Ismail; Ye, Ruiqiong; Mani, Rajam S; Fanta, Mesfin; Yu, Yaping; Douglas, Pauline; Tahbaz, Nasser; Fang, Shujuan; Dobbs, Tracey; Wang, Chen; Morrice, Nick; Hendzel, Michael J; Weinfeld, Michael; Lees-Miller, Susan P

    2011-11-01

    Human polynucleotide kinase/phosphatase (PNKP) is a dual specificity 5'-DNA kinase/3'-DNA phosphatase, with roles in base excision repair, DNA single-strand break repair and non-homologous end joining (NHEJ); yet precisely how PNKP functions in the repair of DNA double strand breaks (DSBs) remains unclear. We demonstrate that PNKP is phosphorylated by the DNA-dependent protein kinase (DNA-PK) and ataxia-telangiectasia mutated (ATM) in vitro. The major phosphorylation site for both kinases was serine 114, with serine 126 being a minor site. Ionizing radiation (IR)-induced phosphorylation of cellular PNKP on S114 was ATM dependent, whereas phosphorylation of PNKP on S126 required both ATM and DNA-PK. Inactivation of DNA-PK and/or ATM led to reduced PNKP at DNA damage sites in vivo. Cells expressing PNKP with alanine or aspartic acid at serines 114 and 126 were modestly radiosensitive and IR enhanced the association of PNKP with XRCC4 and DNA ligase IV; however, this interaction was not affected by mutation of PNKP phosphorylation sites. Purified PNKP protein with mutation of serines 114 and 126 had decreased DNA kinase and DNA phosphatase activities and reduced affinity for DNA in vitro. Together, our results reveal that IR-induced phosphorylation of PNKP by ATM and DNA-PK regulates PNKP function at DSBs.

  13. Detailed search for protein kinase(s) involved in plasma membrane H+-ATPase activity regulation of yeast cells.

    PubMed

    Pereira, Renata R; Castanheira, Diogo; Teixeira, Janaina A; Bouillet, Leoneide E M; Ribeiro, Erica M C; Trópia, Maria M J; Alvarez, Florencia; Correa, Lygia F M; Mota, Bruno E F; Conceição, Luis Eduardo F R; Castro, Ieso M; Brandão, Rogelio L

    2015-03-01

    This study displays a screening using yeast strains deficient in protein kinases known to exist in Saccharomyces cerevisiae. From 95 viable single mutants, 20 mutants appear to be affected in the glucose-induced extracellular acidification. The mutants that are unaffected in calcium signaling were tested for their sensitivity to hygromycin B. Furthermore, we verified whether the remaining mutants produced enzymes that are appropriately incorporated at plasma membrane. Finally, we measure the kinetic properties of the enzyme in purified plasma membranes from glucose-starved as well as glucose-fermenting cells. We confirmed the kinase Ptk2 involvement in H(+)-ATPase regulation (increase of affinity for ATP). However, the identification of the kinase(s) responsible for phosphorylation that leads to an increase in Vmax appears to be more complex. Complementary experiments were performed to check how those protein kinases could be related to the control of the plasma membrane H(+)-ATPase and/or the potential membrane. In summary, our results did not permit us to identify the protein kinase(s) involved in regulating the catalytic efficiency of the plasma membrane H(+)-ATPase. Therefore, our results indicate that the current regulatory model based on the phosphorylation of two different sites located in the C-terminus tail of the enzyme could be inappropriate.

  14. Parallel regulation of mitogen-activated protein kinase kinase 3 (MKK3) and MKK6 in Gq-signaling cascade.

    PubMed

    Yamauchi, J; Tsujimoto, G; Kaziro, Y; Itoh, H

    2001-06-29

    Heterotrimeric G protein G(q) stimulates the activity of p38 mitogen-activated protein kinase (MAPK) in mammalian cells. To investigate the signaling mechanism whereby alpha and betagamma subunits of G(q) activate p38 MAPK, we introduced kinase-deficient mutants of mitogen-activated protein kinase kinase 3 (MKK3), MKK4, and MKK6 into human embryonal kidney 293 cells. The activation of p38 MAPK by Galpha(q) and Gbetagamma was blocked by kinase-deficient MKK3 and MKK6 but not by kinase-deficient MKK4. In addition, Galpha(q) and Gbetagamma stimulated MKK3 and MKK6 activities. The MKK3 and MKK6 activations by Galpha(q), but not by Gbetagamma, were dependent on phospholipase C and c-Src. Galpha(q) stimulated MKK3 in a Rac- and Cdc42-dependent manner and MKK6 in a Rho-dependent manner. On the other hand, Gbetagamma activated MKK3 in a Rac- and Cdc42-dependent manner and MKK6 in a Rho-, Rac-, and Cdc42-dependent manner. Gbetagamma-induced MKK3 and MKK6 activations were dependent on a tyrosine kinase other than c-Src. These results suggest that Galpha(q) and Gbetagamma stimulate the activity of p38 MAPK by regulating MKK3 and MKK6 through parallel signaling pathways.

  15. N-Terminus of the Protein Kinase CLK1 Induces SR Protein Hyper-Phosphorylation

    PubMed Central

    Aubol, Brandon E.; Plocinik, Ryan M.; Keshwani, Malik M.; McGlone, Maria L.; Hagopian, Jonathan C.; Ghosh, Gourisankar; Fu, Xiang-Dong; Adams, Joseph A.

    2016-01-01

    SR proteins are essential splicing factors that are regulated through multisite phosphorylation of their RS (arginine-serine-rich) domains by two major families of protein kinases. The SRPKs efficiently phosphorylate the arginine-serine dipeptides in the RS domain using a conserved docking groove in the kinase domain. In contrast, CLKs lack a docking groove and phosphorylate both arginine-serine and serine-proline dipeptides, modifications that generate a hyper-phosphorylated state important for unique SR protein-dependent splicing activities. All CLKs contain long, flexible N-terminal extensions (140-300 residues) that resemble the RS domains present in their substrate SR proteins. We showed that the N-terminus in CLK1 contacts both the kinase domain and the RS domain of the SR protein SRSF1. This interaction not only is essential for facilitating hyper-phosphorylation but also induces cooperative binding of SRSF1 to RNA. The N-terminus of CLK1 enhances the total phosphoryl contents of a panel of physiological substrates including SRSF1, SRSF2, SRSF5 and Tra2β1 by 2–3-fold. These findings suggest that CLK1-dependent hyper-phosphorylation is the result of a general mechanism in which the N-terminus acts as a bridge connecting the kinase domain and the RS domain of the SR protein. PMID:24869919

  16. Nuclear translocation of doublecortin-like protein kinase and phosphorylation of a transcription factor JDP2

    SciTech Connect

    Nagamine, Tadashi; Nomada, Shohgo; Onouchi, Takashi; Kameshita, Isamu; Sueyoshi, Noriyuki

    2014-03-28

    Highlights: • Doublecortin-like protein kinase (DCLK) is a microtubule-associated protein kinase. • In living cells, DCLK was cleaved into two functional fragments. • zDCLK(kinase) was translocated into the nucleus by osmotic stresses. • Jun dimerization protein 2 (JDP2) was identified as zDCLK(kinase)-binding protein. • JDP2 was efficiently phosphorylated by zDCLK(kinase) only when histone was present. - Abstract: Doublecortin-like protein kinase (DCLK) is a microtubule-associated protein kinase predominantly expressed in brain. In a previous paper, we reported that zebrafish DCLK2 (zDCLK) was cleaved into two functional fragments; the N-terminal zDCLK(DC + SP) with microtubule-binding activity and the C-terminal zDCLK(kinase) with a Ser/Thr protein kinase activity. In this study, we demonstrated that zDCLK(kinase) was widely distributed in the cytoplasm and translocated into the nucleus when the cells were treated under hyperosmotic conditions with NaCl or mannitol. By two-hybrid screening using the C-terminal domain of DCLK, Jun dimerization protein 2 (JDP2), a nuclear transcription factor, was identified as zDCLK(kinase)-binding protein. Furthermore, JDP2 served as an efficient substrate for zDCLK(kinase) only when histone was present. These results suggest that the kinase fragment of DCLK is translocated into the nucleus upon hyperosmotic stresses and that the kinase efficiently phosphorylates JDP2, a possible target in the nucleus, with the aid of histones.

  17. Casein kinase I-like protein kinases encoded by YCK1 and YCK2 are required for yeast morphogenesis.

    PubMed Central

    Robinson, L C; Menold, M M; Garrett, S; Culbertson, M R

    1993-01-01

    Casein kinase I is an acidotropic protein kinase class that is widely distributed among eukaryotic cell types. In the yeast Saccharomyces cerevisiae, the casein kinase I isoform encoded by the gene pair YCK1 and YCK2 is a 60- to 62-kDa membrane-associated form. The Yck proteins perform functions essential for growth and division; either alone supports growth, but loss of function of both is lethal. We report here that casein kinase I-like activity is associated with a soluble Yck2-beta-galactosidase fusion protein in vitro and that thermolabile protein kinase activity is exhibited by a protein encoded by fusion of a temperature-sensitive yck2 allele with lacZ. Cells carrying the yck2-2ts allele arrest at restrictive temperature with multiple, elongated buds containing multiple nuclei. This phenotype suggests that the essential functions of the Yck proteins include roles in bud morphogenesis, possibly in control of cell growth polarity, and in cytokinesis or cell separation. Further, a genetic relationship between the yck2ts allele and deletion of CDC55 indicates that the function of Yck phosphorylation may be related to that of protein phosphatase 2A activity. Images PMID:8474447

  18. Protein kinase CK2 regulates metal toxicity in neuronal cells.

    PubMed

    Zaman, Mohammad S; Johnson, Adam J; Bobek, Gabriele; Kueh, Sindy; Kersaitis, Cindy; Bailey, Trevor D; Buskila, Yossi; Wu, Ming J

    2016-01-01

    Protein kinase CK2 is a pleiotropic tetrameric enzyme, regulating numerous biological processes from cell proliferation to stress response. This study demonstrates for the first time that CK2 is involved in the regulation of metal uptake and toxicity in neuronal cells. After the determination of inhibitory concentrations (IC50) for a range of metal salts (ZnSO4, Al(mal)3, CoCl2, CrO3, NaAsO2 and CaCl2) in Neuro-2a mouse neuroblastoma cells, the effect of CK2 on metal toxicity was investigated by three lines of experiments using CK2 inhibitors, metal ion specific fluorophores and siRNA-mediated knockdown of CK2 expression. The results showed that both CK2 inhibitors, 4,5,6,7-tetrabromobenzotriazole (TBB) and quinalizarin, markedly reduced the toxicity of Zn(ii), Al(iii), Co(ii), Cr(vi) and As(iii). Confocal microscopy imaging revealed that Zn(ii) uptake was accompanied by the increase of intracellular Ca(ii) in Neuro-2a cells treated with IC50 of ZnSO4 (240 μM), and such concurrent elevation of intracellular Zn(ii) and Ca(ii) was blocked by TBB and quinalizarin. The role of CK2 in metal uptake was further characterised using specific siRNA against each of the three subunits (CK2α, α' and β) and the data demonstrate that CK2α' is the prominent subunit regulating the metal toxicity. Finally, the role of CK2 in metal toxicity was found to be conserved in the distant species-Saccharomyces cerevisiae by employing the complete deletion mutants of CK2 (cka1Δ, cka2Δ, ckb1Δ and ckb2Δ). Taken together, these findings shed light on a new facet of CK2 functionality and provide a basis for further research on the regulation of Zn(ii) and Ca(ii) homeostasis by CK2.

  19. Global discovery of protein kinases and other nucleotide-binding proteins by mass spectrometry.

    PubMed

    Xiao, Yongsheng; Wang, Yinsheng

    2016-09-01

    Nucleotide-binding proteins, such as protein kinases, ATPases and GTP-binding proteins, are among the most important families of proteins that are involved in a number of pivotal cellular processes. However, global study of the structure, function, and expression level of nucleotide-binding proteins as well as protein-nucleotide interactions can hardly be achieved with the use of conventional approaches owing to enormous diversity of the nucleotide-binding protein family. Recent advances in mass spectrometry (MS) instrumentation, coupled with a variety of nucleotide-binding protein enrichment methods, rendered MS-based proteomics a powerful tool for the comprehensive characterizations of the nucleotide-binding proteome, especially the kinome. Here, we review the recent developments in the use of mass spectrometry, together with general and widely used affinity enrichment approaches, for the proteome-wide capture, identification and quantification of nucleotide-binding proteins, including protein kinases, ATPases, GTPases, and other nucleotide-binding proteins. The working principles, advantages, and limitations of each enrichment platform in identifying nucleotide-binding proteins as well as profiling protein-nucleotide interactions are summarized. The perspectives in developing novel MS-based nucleotide-binding protein detection platform are also discussed. © 2014 Wiley Periodicals, Inc. Mass Spec Rev 35:601-619, 2016.

  20. Casein kinase II protein kinase is bound to lamina-matrix and phosphorylates lamin-like protein in isolated pea nuclei

    NASA Technical Reports Server (NTRS)

    Li, H.; Roux, S. J.

    1992-01-01

    A casein kinase II (CK II)-like protein kinase was identified and partially isolated from a purified envelope-matrix fraction of pea (Pisum sativum L.) nuclei. When [gamma-32P]ATP was directly added to the envelope-matrix preparation, the three most heavily labeled protein bands had molecular masses near 71, 48, and 46 kDa. Protein kinases were removed from the preparation by sequential extraction with Triton X-100, EGTA, 0.3 M NaCl, and a pH 10.5 buffer, but an active kinase still remained bound to the remaining lamina-matrix fraction after these treatments. This kinase had properties resembling CK II kinases previously characterized from animal and plant sources: it preferred casein as an artificial substrate, could use GTP as efficiently as ATP as the phosphoryl donor, was stimulated by spermine, was calcium independent, and had a catalytic subunit of 36 kDa. Some animal and plant CK II kinases have regulatory subunits near 29 kDa, and a lamina-matrix-bound protein of this molecular mass was recognized on immunoblot by anti-Drosophila CK II polyclonal antibodies. Also found associated with the envelope-matrix fraction of pea nuclei were p34cdc2-like and Ca(2+)-dependent protein kinases, but their properties could not account for the protein kinase activity bound to the lamina. The 71-kDa substrate of the CK II-like kinase was lamin A-like, both in its molecular mass and in its cross-reactivity with anti-intermediate filament antibodies. Lamin phosphorylation is considered a crucial early step in the entry of cells into mitosis, so lamina-bound CK II kinases may be important control points for cellular proliferation.

  1. Mitogen-Activated Protein Kinase Kinase 3 Regulates Seed Dormancy in Barley.

    PubMed

    Nakamura, Shingo; Pourkheirandish, Mohammad; Morishige, Hiromi; Kubo, Yuta; Nakamura, Masako; Ichimura, Kazuya; Seo, Shigemi; Kanamori, Hiroyuki; Wu, Jianzhong; Ando, Tsuyu; Hensel, Goetz; Sameri, Mohammad; Stein, Nils; Sato, Kazuhiro; Matsumoto, Takashi; Yano, Masahiro; Komatsuda, Takao

    2016-03-21

    Seed dormancy has fundamental importance in plant survival and crop production; however, the mechanisms regulating dormancy remain unclear [1-3]. Seed dormancy levels generally decrease during domestication to ensure that crops successfully germinate in the field. However, reduction of seed dormancy can cause devastating losses in cereals like wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) due to pre-harvest sprouting, the germination of mature seed (grain) on the mother plant when rain occurs before harvest. Understanding the mechanisms of dormancy can facilitate breeding of crop varieties with the appropriate levels of seed dormancy [4-8]. Barley is a model crop [9, 10] and has two major seed dormancy quantitative trait loci (QTLs), SD1 and SD2, on chromosome 5H [11-19]. We detected a QTL designated Qsd2-AK at SD2 as the single major determinant explaining the difference in seed dormancy between the dormant cultivar "Azumamugi" (Az) and the non-dormant cultivar "Kanto Nakate Gold" (KNG). Using map-based cloning, we identified the causal gene for Qsd2-AK as Mitogen-activated Protein Kinase Kinase 3 (MKK3). The dormant Az allele of MKK3 is recessive; the N260T substitution in this allele decreases MKK3 kinase activity and appears to be causal for Qsd2-AK. The N260T substitution occurred in the immediate ancestor allele of the dormant allele, and the established dormant allele became prevalent in barley cultivars grown in East Asia, where the rainy season and harvest season often overlap. Our findings show fine-tuning of seed dormancy during domestication and provide key information for improving pre-harvest sprouting tolerance in barley and wheat. PMID:26948880

  2. Inducement of mitogen-activated protein kinases in frozen shoulders

    PubMed Central

    Kanbe, Katsuaki; Inoue, Kazuhiko; Inoue, Yasuo; Chen, Qian

    2010-01-01

    Background Mitogen-activated protein (MAP) kinases are well-known molecules that play key roles in mechanical stress signals during skeletal development. To test our hypothesis that the synovium in frozen shoulders is induced by MAP kinases, immunohistochemical analyses for detecting expression and signal transduction of MAP kinases were performed in synovial tissue obtained from the rotator interval (RI) in frozen shoulders. Methods Synovial tissues were examined from 10 frozen shoulder patients with a mean age of 55.4 years (46–62 years). Synovial tissues between the long head of the biceps tendon (LHB) and the RI in frozen shoulders were stained with hematoxylin and eosin (H&E) and then examined with immunohistochemical staining. Extracellular signal-regulated (ERK), the Jun N-terminal (JNK), and p38 mitogen-activated protein (MAP) kinases, nuclear factor κB (NF-κB), p50, CD29 (β1-integrin), matrix metalloproteinase (MMP)-3, interleukin-6 (IL-6), CD56, CD68, S-100, and vascular endothelial growth factor (VEGF) were analyzed to detect expression patterns. Results H&E showed vascular proliferation with fibrin and fibrous tissue in the synovium of frozen shoulders. ERK was expressed in the epithelial cells of vascular tissue, and JNK was expressed strongly in the interstitial cells around vascular tissue; p38 MAPK was not expressed. NF-κB was expressed in vascular tissue, and IL-6 was expressed around vascular tissue. CD29 (β1-integrin) was expressed in vascular tissue and in superficial cells of synovial tissue. MMP-3 and VEGF were expressed on the surface layer of synovial tissue and vascular tissue, and CD68 was expressed on the surface layer. Nerve-related proteins, CD56 and S-100, were expressed weakly. Conclusions Mechanical stress on the LHB and RI in the shoulder may induce ERK and JNK to express NF-κB by CD29 to develop capsule contracture, producing MMP-3, IL-6, and VEGF. PMID:19214689

  3. Osmotic Stress Induces Rapid Activation of a Salicylic Acid–Induced Protein Kinase and a Homolog of Protein Kinase ASK1 in Tobacco Cells

    PubMed Central

    Mikołajczyk, Monika; Awotunde, Olubunmi S.; Muszyńska, Grażyna; Klessig, Daniel F.; Dobrowolska, Grażyna

    2000-01-01

    In tobacco cells, osmotic stress induced the rapid activation of two protein kinases that phosphorylate myelin basic protein. Immunological studies demonstrated that the 48-kD kinase is the salicylic acid–induced protein kinase (SIPK), a member of the mitogen-activated protein kinase family. SIPK was activated 5 to 10 min after the cells were exposed to osmotic stresses, and its activity persisted for ∼30 min. In contrast, the 42-kD kinase was activated within 1 min after osmotic stress, and its activity was maintained for ∼2 hr. Moreover, in addition to myelin basic protein, the 42-kD kinase phosphorylated casein and two transcription factors, c-Jun and ATF-2. This latter enzyme was inactivated by a serine/threonine–specific phosphatase but, unlike SIPK, was not affected by a tyrosine-specific phosphatase. After the 42-kD kinase was purified to apparent homogeneity, tryptic peptide analysis indicated that it is a homolog of Arabidopsis serine/threonine kinase1 (ASK1). PMID:10634915

  4. Spatial Phosphoprotein Profiling Reveals a Compartmentalized Extracellular Signal-regulated Kinase Switch Governing Neurite Growth and Retraction

    SciTech Connect

    Wang, Yingchun; Yang, Feng; Fu, Yi; Huang, Xiahe; Wang, Wei; Jiang, Xining; Gritsenko, Marina A.; Zhao, Rui; Monroe, Matthew E.; Pertz, Olivier C.; Purvine, Samuel O.; Orton, Daniel J.; Jacobs, Jon M.; Camp, David G.; Smith, Richard D.; Klemke, Richard L.

    2011-05-20

    Abstract - Brain development and spinal cord regeneration require neurite sprouting and growth cone navigation in response to extension and collapsing factors present in the extracellular environment. These external guidance cues control neurite growth cone extension and retraction processes through intracellular protein phosphorylation of numerous cytoskeletal, adhesion, and polarity complex signaling proteins. However, the complex kinase/substrate signaling networks that mediate neuritogenesis have not been investigated. Here, we compare the neurite phosphoproteome under growth and retraction conditions using neurite purification methodology combined with mass spectrometry. More than 4000 non-redundant phosphorylation sites from 1883 proteins have been annotated and mapped to signaling pathways that control kinase/phosphatase networks, cytoskeleton remodeling, and axon/dendrite specification. Comprehensive informatics and functional studies revealed a compartmentalized ERK activation/deactivation cytoskeletal switch that governs neurite growth and retraction, respectively. Our findings provide the first system-wide analysis of the phosphoprotein signaling networks that enable neurite growth and retraction and reveal an important molecular switch that governs neuritogenesis.

  5. Effects of prodigiosin family compounds from Pseudoalteromonas sp. 1020R on the activities of protein phosphatases and protein kinases.

    PubMed

    Soliev, Azamjon B; Hosokawa, Kakushi; Enomoto, Keiichi

    2015-01-01

    Pseudoalteromonas sp. strain 1020R produces prodigiosin and its closely related congeners, which differ in the length of their alkyl side chains. These red-pigmented compounds were found to exhibit cytotoxicity against human leukemia cell lines. The compounds also showed dose-dependent inhibitory effects on protein phosphatase 2A and protein tyrosine phosphatase 1B (PTP1B), while remaining relatively inactive against protein kinases, including protein tyrosine kinase, Ca(2+)/calmodulin-dependent protein kinase and protein kinases A and C. Comparative studies of the individual pigmented compounds on PTP1B inhibition showed that as the chain length of the alkyl group at the C-3 position of the compound increased, the inhibitory effect on PTP1B decreased. These results suggest that protein phosphatases but not protein kinases might be involved in the cytotoxicity of the prodigiosin family of compounds against malignant cells.

  6. Functions of AMP-activated protein kinase in adipose tissue

    PubMed Central

    Daval, Marie; Foufelle, Fabienne; Ferré, Pascal

    2006-01-01

    AMP-activated protein kinase (AMPK) is involved in cellular energy homeostasis. Its functions have been extensively studied in muscles and liver. AMPK stimulates pathways which increase energy production (glucose transport, fatty acid oxidation) and switches off pathways which consume energy (lipogenesis, protein synthesis, gluconeogenesis). This has led to the concept that AMPK has an interesting pharmaceutical potential in situations of insulin resistance and it is indeed the target of existing drugs and hormones which improve insulin sensitivity. Adipose tissue is a key player in energy metabolism through the release of substrates and hormones involved in metabolism and insulin sensitivity. Activation of AMPK in adipose tissue can be achieved through situations such as fasting and exercise. Leptin and adiponectin as well as hypoglycaemic drugs are activators of adipose tissue AMPK. This activation probably involves changes in the AMP/ATP ratio and the upstream kinase LKB1. When activated, AMPK limits fatty acid efflux from adipocytes and favours local fatty acid oxidation. Since fatty acids have a key role in insulin resistance, especially in muscles, activating AMPK in adipose tissue might be found to be beneficial in insulin-resistant states, particularly as AMPK activation also reduces cytokine secretion in adipocytes. PMID:16709632

  7. Pyruvate kinase M2 is a phosphotyrosine-binding protein

    SciTech Connect

    Christofk, H.R.; Vander Heiden, M.G.; Wu, N.; Asara, J.M.; Cantley, L.C.

    2008-06-03

    Growth factors stimulate cells to take up excess nutrients and to use them for anabolic processes. The biochemical mechanism by which this is accomplished is not fully understood but it is initiated by phosphorylation of signalling proteins on tyrosine residues. Using a novel proteomic screen for phosphotyrosine-binding proteins, we have made the observation that an enzyme involved in glycolysis, the human M2 (fetal) isoform of pyruvate kinase (PKM2), binds directly and selectively to tyrosine-phosphorylated peptides. We show that binding of phosphotyrosine peptides to PKM2 results in release of the allosteric activator fructose-1,6-bisphosphate, leading to inhibition of PKM2 enzymatic activity. We also provide evidence that this regulation of PKM2 by phosphotyrosine signalling diverts glucose metabolites from energy production to anabolic processes when cells are stimulated by certain growth factors. Collectively, our results indicate that expression of this phosphotyrosine-binding form of pyruvate kinase is critical for rapid growth in cancer cells.

  8. Development of Novel Adenosine Monophosphate-Activated Protein Kinase Activators

    PubMed Central

    Guh, Jih-Hwa; Chang, Wei-Ling; Yang, Jian; Lee, Su-Lin; Wei, Shuo; Wang, Dasheng; Kulp, Samuel K.; Chen, Ching-Shih

    2010-01-01

    In light of the unique ability of thiazolidinediones to mediate peroxisome proliferator-activated receptor (PPAR)γ-independent activation of adenosine monophosphate-activated protein kinase (AMPK) and suppression of interleukin (IL)-6 production, we conducted a screening of an in-house, thiazolidinedione-based focused compound library to identify novel agents with these dual pharmacological activities. Cell-based assays pertinent to the activation status of AMPK and mammalian homolog of target of rapamycin (i.e., phosphorylation of AMPK and p70 ribosomal protein S6 kinase, respectively), and IL-6/IL-6 receptor signaling (i.e., IL-6 production and signal transducer and activator of transcription 3 phosphorylation, respectively) in lipopolysaccharide (LPS)-stimulated THP-1 human macrophages were used to screen this compound library, which led to the identification of compound 53 (N-{4-[3-(1-Methylcyclohexylmethyl)-2,4-dioxo-thiazolidin-5-ylidene-methyl]-phenyl}-4-nitro-3-trifluoromethyl-benzenesulfonamide) as the lead agent. Evidence indicates that this drug-induced suppression of LPS-stimulated IL-6 production was attributable to AMPK activation. Furthermore, compound 53-mediated AMPK activation was demonstrated in C-26 colon adenocarcinoma cells, indicating that it is not a cell line-specific event. PMID:20170185

  9. Protein kinase A activity and Hedgehog signaling pathway.

    PubMed

    Kotani, Tomoya

    2012-01-01

    Protein kinase A (PKA) is a well-known kinase that plays fundamental roles in a variety of biological processes. In Hedgehog-responsive cells, PKA plays key roles in proliferation and fate specification by modulating the transduction of Hedgehog signaling. In the absence of Hedgehog, a basal level of PKA activity represses the transcription of Hedgehog target genes. The main substrates of PKA in this process are the Ci/Gli family of bipotential transcription factors, which activate and repress Hedgehog target gene expression. PKA phosphorylates Ci/Gli, promoting the production of the repressor forms of Ci/Gli and thus repressing Hedgehog target gene expression. In contrast, the activation of Hedgehog signaling in response to Hedgehog increases the active forms of Ci/Gli, resulting in Hedgehog target gene expression. Because both decreased and increased levels of PKA activity cause abnormal cell proliferation and alter cell fate specification, the basal level of PKA activity in Hedgehog-responsive cells should be precisely regulated. However, the mechanism by which PKA activity is regulated remains obscure and appears to vary between cell types, tissues, and organisms. To date, two mechanisms have been proposed. One is a classical mechanism in which PKA activity is regulated by a small second messenger, cAMP; the other is a novel mechanism in which PKA activity is regulated by a protein, Misty somites. PMID:22391308

  10. [Perioperative alterations in polymorphonuclear leukocyte function mediated by protein kinase C].

    PubMed

    Yokota, K; Nishihira, T; Shineha, R; Ueda, H; Mori, S

    1994-03-01

    To characterize the perioperative alterations in polymorphonuclear leukocytes (PMN) function mediated by protein kinase C, we studied twenty six patients undergoing gastrointestinal surgery. Seventeen patients with thoracic esophageal cancer were underwent total thoracic esophagectomy through a right thoracotomy (severe surgical stress group). Nine patients underwent cholecystectomy (slight surgical stress group). Measurement of O2- production capacity was used as a reflection of the activity of NADPH oxidase, and the activity of myeloperoxidase-H2O2-halide system was evaluated using luminol-dependent chemiluminescence. O2- production stimulated by phorbol 12-myristate 13-acetate (PMA) was suppressed, reaching a minimum on POD 3. On the other hand, luminol dependent chemiluminescence increased significantly after surgery, reached a maximum on POD 3. These alterations were more remarkable in the severely stressed patients. These results suggest that postoperative PMN signal transduction mechanisms, mediated by protein kinase C, may activate myeloperoxidase-H2-O2-halide system but suppress NADPH oxidase system dependently of the degree of surgical stress, revealing a differential effect of protein kinase C activation on PMN microbicidal activity.

  11. Spatial Organization in Protein Kinase A Signaling Emerged at the Base of Animal Evolution.

    PubMed

    Peng, Mao; Aye, Thin Thin; Snel, Berend; van Breukelen, Bas; Scholten, Arjen; Heck, Albert J R

    2015-07-01

    In phosphorylation-directed signaling, spatial and temporal control is organized by complex interaction networks that diligently direct kinases toward distinct substrates to fine-tune specificity. How these protein networks originate and evolve into complex regulatory machineries are among the most fascinating research questions in biology. Here, spatiotemporal signaling is investigated by tracing the evolutionary dynamics of each functional domain of cAMP-dependent protein kinase (PKA) and its diverse set of A-kinase anchoring proteins (AKAPs). Homologues of the catalytic (PKA-C) and regulatory (PKA-R) domains of the (PKA-R)2-(PKA-C)2 holoenzyme were found throughout evolution. Most variation was observed in the RIIa of PKA-R, crucial for dimerization and docking to AKAPs. The RIIa domain was not observed in all PKA-R homologues. In the fungi and distinct protist lineages, the RIIa domain emerges within PKA-R, but it displays large sequence variation. These organisms do not harbor homologues of AKAPs, suggesting that efficient docking to direct spatiotemporal PKA activity evolved in multicellular eukaryotes. To test this in silico hypothesis, we experimentally screened organisms with increasing complexity by cAMP-based chemical proteomics to reveal that the occurrence of PKA-AKAP interactions indeed coincided and expanded within vertebrates, suggesting a crucial role for AKAPs in the advent of metazoan multicellularity. PMID:26066639

  12. Jun N-Terminal Protein Kinase Enhances Middle Ear Mucosal Proliferation during Bacterial Otitis Media▿

    PubMed Central

    Furukawa, Masayuki; Ebmeyer, Jörg; Pak, Kwang; Austin, Darrell A.; Melhus, Åsa; Webster, Nicholas J. G.; Ryan, Allen F.

    2007-01-01

    Mucosal hyperplasia is a characteristic component of otitis media. The present study investigated the participation of signaling via the Jun N-terminal protein kinase (JNK) mitogen-activated protein kinase in middle ear mucosal hyperplasia in animal models of bacterial otitis media. Otitis media was induced by the inoculation of nontypeable Haemophilus influenzae into the middle ear cavity. Western blotting revealed that phosphorylation of JNK isoforms in the middle ear mucosa preceded but paralleled mucosal hyperplasia in this in vivo rat model. Nuclear JNK phosphorylation was observed in many cells of both the mucosal epithelium and stroma by immunohistochemistry. In an in vitro model of primary rat middle ear mucosal explants, bacterially induced mucosal growth was blocked by the Rac/Cdc42 inhibitor Clostridium difficile toxin B, the mixed-lineage kinase inhibitor CEP11004, and the JNK inhibitor SP600125. Finally, the JNK inhibitor SP600125 significantly inhibited mucosal hyperplasia during in vivo bacterial otitis media in guinea pigs. Inhibition of JNK in vivo resulted in a diminished proliferative response, as shown by a local decrease in proliferating cell nuclear antigen protein expression by immunohistochemistry. We conclude that activation of JNK is a critical pathway for bacterially induced mucosal hyperplasia during otitis media, influencing tissue proliferation. PMID:17325051

  13. Activation of GABA(B) receptors inhibits protein kinase B/glycogen synthase kinase 3 signaling.

    PubMed

    Lu, Frances Fangjia; Su, Ping; Liu, Fang; Daskalakis, Zafiris J

    2012-11-28

    Accumulated evidence has suggested that potentiation of cortical GABAergic inhibitory neurotransmission may be a key mechanism in the treatment of schizophrenia. However, the downstream molecular mechanisms related to GABA potentiation remain unexplored. Recent studies have suggested that dopamine D2 receptor antagonists, which are used in the clinical treatment of schizophrenia, modulate protein kinase B (Akt)/glycogen synthase kinase (GSK)-3 signaling. Here we report that activation of GABA(B) receptors significantly inhibits Akt/GSK-3 signaling in a β-arrestin-dependent pathway. Agonist stimulation of GABA(B) receptors enhances the phosphorylation of Akt (Thr-308) and enhances the phosphorylation of GSK-3α (Ser-21)/β (Ser-9) in both HEK-293T cells expressing GABA(B) receptors and rat hippocampal slices. Furthermore, knocking down the expression of β-arrestin2 using siRNA abolishes the GABA(B) receptor-mediated modulation of GSK-3 signaling. Our data may help to identify potentially novel targets through which GABA(B) receptor agents may exert therapeutic effects in the treatment of schizophrenia.

  14. Association of Common Genetic Variants in Mitogen-activated Protein Kinase Kinase Kinase Kinase 4 with Type 2 Diabetes Mellitus in a Chinese Han Population

    PubMed Central

    Li, Ting-Ting; Qiao, Hong; Tong, Hui-Xin; Zhuang, Tian-Wei; Wang, Tong-Tong

    2016-01-01

    Background: A study has identified several novel susceptibility variants of the mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4) gene for type 2 diabetes mellitus (T2DM) within the German population. Among the variants, five single nucleotide polymorphisms (SNPs) of MAP4K4 (rs1003376, rs11674694, rs2236935, rs2236936, and rs6543087) showed significant association with T2DM or diabetes-related quantitative traits. We aimed to evaluate whether common SNPs in the MAP4K4 gene were associated with T2DM in the Chinese population. Methods: Five candidate SNPs were genotyped in 996 patients newly diagnosed with T2DM and in 976 control subjects, using the SNPscan™ method. All subjects were recruited from the Second Affiliated Hospital, Harbin Medical University from October 2010 to September 2013. We evaluated the T2DM risk conferred by individual SNPs and haplotypes using logistic analysis, and the association between the five SNPs and metabolic traits in the subgroups. Results: Of the five variants, SNP rs2236935T/C was significantly associated with T2DM in this study population (odds ratio = 1.293; 95% confidence interval: 1.034–1.619, P = 0.025). In addition, among the controls, rs1003376 was significantly associated with an increased body mass index (P = 0.045) and homeostatic model assessment-insulin resistance (P = 0.037). Conclusions: MAP4K4 gene is associated with T2DM in a Chinese Han population, and MAP4K4 gene variants may contribute to the risk toward the development of T2DM. PMID:27174326

  15. Cytoplasmic polyadenylation element binding protein-dependent protein synthesis is regulated by calcium/calmodulin-dependent protein kinase II.

    PubMed

    Atkins, Coleen M; Nozaki, Naohito; Shigeri, Yasushi; Soderling, Thomas R

    2004-06-01

    Phosphorylation of cytoplasmic polyadenylation element binding protein (CPEB) regulates protein synthesis in hippocampal dendrites. CPEB binds the 3' untranslated region (UTR) of cytoplasmic mRNAs and, when phosphorylated, initiates mRNA polyadenylation and translation. We report that, of the protein kinases activated in the hippocampus during synaptic plasticity, calcium/calmodulin-dependent protein kinase II (CaMKII) robustly phosphorylated the regulatory site (threonine 171) in CPEB in vitro. In postsynaptic density fractions or hippocampal neurons, CPEB phosphorylation increased when CaMKII was activated. These increases in CPEB phosphorylation were attenuated by a specific peptide inhibitor of CaMKII and by the general CaM-kinase inhibitor KN-93. Inhibitors of protein phosphatase 1 increased basal CPEB phosphorylation in neurons; this was also attenuated by a CaM-kinase inhibitor. To determine whether CaM-kinase activity regulates CPEB-dependent mRNA translation, hippocampal neurons were transfected with luciferase fused to a 3' UTR containing CPE-binding elements. Depolarization of neurons stimulated synthesis of luciferase; this was abrogated by inhibitors of protein synthesis, mRNA polyadenylation, and CaMKII. These results demonstrate that CPEB phosphorylation and translation are regulated by CaMKII activity and provide a possible mechanism for how dendritic protein synthesis in the hippocampus may be stimulated during synaptic plasticity.

  16. ProNormz--an integrated approach for human proteins and protein kinases normalization.

    PubMed

    Subramani, Suresh; Raja, Kalpana; Natarajan, Jeyakumar

    2014-02-01

    The task of recognizing and normalizing protein name mentions in biomedical literature is a challenging task and important for text mining applications such as protein-protein interactions, pathway reconstruction and many more. In this paper, we present ProNormz, an integrated approach for human proteins (HPs) tagging and normalization. In Homo sapiens, a greater number of biological processes are regulated by a large human gene family called protein kinases by post translational phosphorylation. Recognition and normalization of human protein kinases (HPKs) is considered to be important for the extraction of the underlying information on its regulatory mechanism from biomedical literature. ProNormz distinguishes HPKs from other HPs besides tagging and normalization. To our knowledge, ProNormz is the first normalization system available to distinguish HPKs from other HPs in addition to gene normalization task. ProNormz incorporates a specialized synonyms dictionary for human proteins and protein kinases, a set of 15 string matching rules and a disambiguation module to achieve the normalization. Experimental results on benchmark BioCreative II training and test datasets show that our integrated approach achieve a fairly good performance and outperforms more sophisticated semantic similarity and disambiguation systems presented in BioCreative II GN task. As a freely available web tool, ProNormz is useful to developers as extensible gene normalization implementation, to researchers as a standard for comparing their innovative techniques, and to biologists for normalization and categorization of HPs and HPKs mentions in biomedical literature. URL: http://www.biominingbu.org/pronormz.

  17. Identification and functional analysis of mitogen-activated protein kinase kinase kinase (MAPKKK) genes in canola (Brassica napus L.)

    PubMed Central

    Sun, Yun; Wang, Chen; Yang, Bo; Jiang, Yuan-Qing

    2014-01-01

    Mitogen-activated protein kinase (MAPK) signalling cascades, consisting of three types of reversibly phosphorylated kinases (MAPKKK, MAPKK, and MAPK), are involved in important processes including plant immunity and hormone responses. The MAPKKKs comprise the largest family in the MAPK cascades, yet only a few of these genes have been associated with physiological functions, even in the model plant Arabidopsis thaliana. Canola (Brassica napus L.) is one of the most important oilseed crops in China and worldwide. To explore MAPKKK functions in biotic and abiotic stress responses in canola, 66 MAPKKK genes were identified and 28 of them were cloned. Phylogenetic analysis of these canola MAPKKKs with homologous genes from representative species classified them into three groups (A–C), comprising four MAPKKKs, seven ZIKs, and 17 Raf genes. A further 15 interaction pairs between these MAPKKKs and the downstream BnaMKKs were identified through a yeast two-hybrid assay. The interactions were further validated through bimolecular fluorescence complementation (BiFC) analysis. In addition, by quantitative real-time reverse transcription–PCR, it was further observed that some of these BnaMAPKKK genes were regulated by different hormone stimuli, abiotic stresses, or fungal pathogen treatments. Interestingly, two novel BnaMAPKKK genes, BnaMAPKKK18 and BnaMAPKKK19, which could elicit hypersensitive response (HR)-like cell death when transiently expressed in Nicotiana benthamiana leaves, were successfully identified. Moreover, it was found that BnaMAPKKK19 probably mediated cell death through BnaMKK9. Overall, the present work has laid the foundation for further characterization of this important MAPKKK gene family in canola. PMID:24604738

  18. Identification and functional analysis of mitogen-activated protein kinase kinase kinase (MAPKKK) genes in canola (Brassica napus L.).

    PubMed

    Sun, Yun; Wang, Chen; Yang, Bo; Wu, Feifei; Hao, Xueyu; Liang, Wanwan; Niu, Fangfang; Yan, Jingli; Zhang, Hanfeng; Wang, Boya; Deyholos, Michael K; Jiang, Yuan-Qing

    2014-05-01

    Mitogen-activated protein kinase (MAPK) signalling cascades, consisting of three types of reversibly phosphorylated kinases (MAPKKK, MAPKK, and MAPK), are involved in important processes including plant immunity and hormone responses. The MAPKKKs comprise the largest family in the MAPK cascades, yet only a few of these genes have been associated with physiological functions, even in the model plant Arabidopsis thaliana. Canola (Brassica napus L.) is one of the most important oilseed crops in China and worldwide. To explore MAPKKK functions in biotic and abiotic stress responses in canola, 66 MAPKKK genes were identified and 28 of them were cloned. Phylogenetic analysis of these canola MAPKKKs with homologous genes from representative species classified them into three groups (A-C), comprising four MAPKKKs, seven ZIKs, and 17 Raf genes. A further 15 interaction pairs between these MAPKKKs and the downstream BnaMKKs were identified through a yeast two-hybrid assay. The interactions were further validated through bimolecular fluorescence complementation (BiFC) analysis. In addition, by quantitative real-time reverse transcription-PCR, it was further observed that some of these BnaMAPKKK genes were regulated by different hormone stimuli, abiotic stresses, or fungal pathogen treatments. Interestingly, two novel BnaMAPKKK genes, BnaMAPKKK18 and BnaMAPKKK19, which could elicit hypersensitive response (HR)-like cell death when transiently expressed in Nicotiana benthamiana leaves, were successfully identified. Moreover, it was found that BnaMAPKKK19 probably mediated cell death through BnaMKK9. Overall, the present work has laid the foundation for further characterization of this important MAPKKK gene family in canola. PMID:24604738

  19. The structure of Legionella pneumophila LegK4 type four secretion system (T4SS) effector reveals a novel dimeric eukaryotic-like kinase

    PubMed Central

    Flayhan, Ali; Bergé, Célia; Baïlo, Nathalie; Doublet, Patricia; Bayliss, Richard; Terradot, Laurent

    2015-01-01

    Bacterial pathogens subvert signalling pathways to promote invasion and/or replication into the host. LegK1-4 proteins are eukaryotic-like serine/threonine kinases that are translocated by the Dot/Icm type IV secretion system (T4SS) of several Legionella pneumophila strains. We present the crystal structures of an active fragment of the LegK4 protein in apo and substrate-bound states. The structure of LegK41–445 reveals a eukaryotic-like kinase domain flanked by a novel cap domain and a four-helix bundle. The protein self-assembles through interactions mediated by helices αF and αG that generate a dimeric interface not previously observed in a protein kinase. The helix αG is displaced compared to previous kinase structures, and its role in stabilization of the activation loop is taken on by the dimerisation interface. The apo-form of the protein has an open conformation with a disordered P-loop but a structured activation segment in absence of targeted phosphorylation. The nucleotide-binding site of LegK4 contains an unusual set of residues that mediate non-canonical interactions with AMP-PNP. Nucleotide binding results in limited changes in the active site, suggesting that LegK4 constitutive kinase activity does not depend on phosphorylation of the activation loop but on the stabilizing effects of the dimer. PMID:26419332

  20. Protein kinase A represses skeletal myogenesis by targeting myocyte enhancer factor 2D.

    PubMed

    Du, Min; Perry, Robert L S; Nowacki, Nathaniel B; Gordon, Joseph W; Salma, Jahan; Zhao, Jianzhong; Aziz, Arif; Chan, Joseph; Siu, K W Michael; McDermott, John C

    2008-05-01

    Activation of protein kinase A (PKA) by elevation of the intracellular cyclic AMP (cAMP) level inhibits skeletal myogenesis. Previously, an indirect modulation of the myogenic regulatory factors (MRFs) was implicated as the mechanism. Because myocyte enhancer factor 2 (MEF2) proteins are key regulators of myogenesis and obligatory partners for the MRFs, here we assessed whether these proteins could be involved in PKA-mediated myogenic repression. Initially, in silico analysis revealed several consensus PKA phosphoacceptor sites on MEF2, and subsequent analysis by in vitro kinase assays indicated that PKA directly and efficiently phosphorylates MEF2D. Using mass spectrometric determination of phosphorylated residues, we document that MEF2D serine 121 and serine 190 are targeted by PKA. Transcriptional reporter gene assays to assess MEF2D function revealed that PKA potently represses the transactivation properties of MEF2D. Furthermore, engineered mutation of MEF2D PKA phosphoacceptor sites (serines 121 and 190 to alanine) rendered a PKA-resistant MEF2D protein, which efficiently rescues myogenesis from PKA-mediated repression. Concomitantly, increased intracellular cAMP-mediated PKA activation also resulted in an enhanced nuclear accumulation of histone deacetylase 4 (HDAC4) and a subsequent increase in the MEF2D-HDAC4 repressor complex. Collectively, these data identify MEF2D as a primary target of PKA signaling in myoblasts that leads to inhibition of the skeletal muscle differentiation program.

  1. Rho kinase acts as a downstream molecule to participate in protein kinase Cε regulation of vascular reactivity after hemorrhagic shock in rats.

    PubMed

    Li, Tao; Zhu, Yu; Zang, Jia-tao; Peng, Xiao-yong; Lan, Dan; Yang, Guang-ming; Xu, Jing; Liu, Liang-ming

    2014-09-01

    Our previous study demonstrated that Rho kinase and protein kinase C (PKC) played important parts in the regulation of vascular reactivity after shock. Using superior mesenteric arteries (SMAs) from hemorrhagic shock rats and hypoxia-treated vascular smooth muscle cells (VSMCs), relationship of PKCε regulation of vascular reactivity to Rho kinase, as well as the signal transduction after shock, was investigated. The results showed that inhibition of Rho kinase with the Rho kinase-specific inhibitor Y-27632 antagonized the PKCε-specific agonist carbachol and highly expressed PKCε-induced increase of vascular reactivity in SMAs and VSMCs, whereas inhibition of PKCε with its specific inhibitory peptide did not antagonize the Rho kinase agonist (U-46619)-induced increase of vascular reactivity in SMAs and VSMCs. Activation of PKCε or highly expressed PKCε upregulated the activity of Rho kinase and the phosphorylation of PKC-dependent phosphatase inhibitor 17 (CPI-17), zipper interacting protein kinase (ZIPK), and integrin-linked kinase (ILK), whereas activation of Rho kinase increased only CPI-17 phosphorylation. The specific neutralization antibodies of ZIPK and ILK antagonized PKCε-induced increases in the activity of Rho kinase, but CPI-17 neutralization antibody did not antagonize this effect. These results suggested that Rho kinase takes part in the regulation of PKCε on vascular reactivity after shock. Rho kinase is downstream of PKCε. Protein kinase Cε activates Rho kinase via ZIPK and ILK; CPI-17 is downstream of Rho kinase.

  2. Huntingtin-associated protein 1 (HAP1) is a cGMP-dependent kinase anchoring protein (GKAP) specific for the cGMP-dependent protein kinase Iβ isoform.

    PubMed

    Corradini, Eleonora; Burgers, Pepijn P; Plank, Michael; Heck, Albert J R; Scholten, Arjen

    2015-03-20

    Protein-protein interactions are important in providing compartmentalization and specificity in cellular signal transduction. Many studies have hallmarked the well designed compartmentalization of the cAMP-dependent protein kinase (PKA) through its anchoring proteins. Much less data are available on the compartmentalization of its closest homolog, cGMP-dependent protein kinase (PKG), via its own PKG anchoring proteins (GKAPs). For the enrichment, screening, and discovery of (novel) PKA anchoring proteins, a plethora of methodologies is available, including our previously described chemical proteomics approach based on immobilized cAMP or cGMP. Although this method was demonstrated to be effective, each immobilized cyclic nucleotide did not discriminate in the enrichment for either PKA or PKG and their secondary interactors. Hence, with PKG signaling components being less abundant in most tissues, it turned out to be challenging to enrich and identify GKAPs. Here we extend this cAMP-based chemical proteomics approach using competitive concentrations of free cyclic nucleotides to isolate each kinase and its secondary interactors. Using this approach, we identified Huntingtin-associated protein 1 (HAP1) as a putative novel GKAP. Through sequence alignment with known GKAPs and secondary structure prediction analysis, we defined a small sequence domain mediating the interaction with PKG Iβ but not PKG Iα. In vitro binding studies and site-directed mutagenesis further confirmed the specificity and affinity of HAP1 binding to the PKG Iβ N terminus. These data fully support that HAP1 is a GKAP, anchoring specifically to the cGMP-dependent protein kinase isoform Iβ, and provide further evidence that also PKG spatiotemporal signaling is largely controlled by anchoring proteins.

  3. Protein kinase D enzymes – novel kinase targets in pancreatic cancer

    PubMed Central

    Liou, Geou-Yarh; Storz, Peter

    2016-01-01

    Summary Pancreatic ductal adenocarcinoma (PDA) is characterized by advanced stage desmoplastic tumors with a high prevalence of genetic abnormalities. Occurrence of PDA is linked to activating Kras mutations and aberrant epidermal growth factor receptor signaling, leading to additional activation of wildtype Kras. Since Kras is difficult to target, there is a constant need to identify novel targets acting downstream of this molecule in driving the formation or progression of PDA. Recently, it was shown that Protein kinase D enzymes not only are increasingly expressed in PDA, but also causatively linked to the development and progression of this cancer. They act downstream of both mutant Kras and growth factors and therefore may represent ideal novel targets. PMID:26174103

  4. AKT (protein kinase B) is implicated in meiotic maturation of porcine oocytes.

    PubMed

    Kalous, Jaroslav; Kubelka, Michal; Solc, Petr; Susor, Andrej; Motlík, Jan

    2009-10-01

    The aim of this study was to investigate the involvement of the serine/threonine protein kinase AKT (also called protein kinase B) in the control of meiosis of porcine denuded oocytes (DOs) matured in vitro. Western blot analysis revealed that the two principal AKT phosphorylation sites, Ser473 and Thr308, are phosphorylated at different stages of meiosis. In freshly isolated germinal vesicle (GV)-stage DOs, Ser473 was already phosphorylated. After the onset of oocyte maturation, the intensity of the Ser473 phosphorylation increased, however, which declined sharply when DOs underwent GV breakdown (GVBD) and remained at low levels in metaphase I- and II-stage (MI- and MII-stage). In contrast, phosphorylation of Thr308 was increased by the time of GVBD and reached maximum at MI-stage. A peak of AKT activity was noticed around GVBD and activity of AKT declined at MI-stage. To assess the role of AKT during meiosis, porcine DOs were cultured in 50 microM SH-6, a specific inhibitor of AKT. In SH-6-treated DOs, GVBD was not inhibited; on the contrary, a significant acceleration of meiosis resumption was observed. The dynamics of the Ser473 phosphorylation was not affected; however, phosphorylation of Thr308 was reduced, AKT activity was diminished at the time of GVBD, and meiotic progression was arrested in early MI-stage. Moreover, the activity of the cyclin-dependent kinase 1 (CDK1) and MAP kinase declined when SH-6-treated DOs underwent GVBD, indicating that AKT activity is involved in the regulation of CDK1 and MAP kinase. These results suggest that activity of AKT is not essential for induction of GVBD in porcine oocytes but plays a substantial role during progression of meiosis to MI/MII-stage.

  5. Endothelial protein kinase MAP4K4 promotes vascular inflammation and atherosclerosis

    PubMed Central

    Roth Flach, Rachel J.; Skoura, Athanasia; Matevossian, Anouch; Danai, Laura V.; Zheng, Wei; Cortes, Christian; Bhattacharya, Samit K.; Aouadi, Myriam; Hagan, Nana; Yawe, Joseph C.; Vangala, Pranitha; Menendez, Lorena Garcia; Cooper, Marcus P.; Fitzgibbons, Timothy P.; Buckbinder, Leonard; Czech, Michael P.

    2015-01-01

    Signalling pathways that control endothelial cell (EC) permeability, leukocyte adhesion and inflammation are pivotal for atherosclerosis initiation and progression. Here we demonstrate that the Sterile-20-like mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4), which has been implicated in inflammation, is abundantly expressed in ECs and in atherosclerotic plaques from mice and humans. On the basis of endothelial-specific MAP4K4 gene silencing and gene ablation experiments in Apoe−/− mice, we show that MAP4K4 in ECs markedly promotes Western diet-induced aortic macrophage accumulation and atherosclerotic plaque development. Treatment of Apoe−/− and Ldlr−/− mice with a selective small-molecule MAP4K4 inhibitor also markedly reduces atherosclerotic lesion area. MAP4K4 silencing in cultured ECs attenuates cell surface adhesion molecule expression while reducing nuclear localization and activity of NFκB, which is critical for promoting EC activation and atherosclerosis. Taken together, these results reveal that MAP4K4 is a key signalling node that promotes immune cell recruitment in atherosclerosis. PMID:26688060

  6. A novel mammalian protein kinase gene (mak) is highly expressed in testicular germ cells at and after meiosis.

    PubMed Central

    Matsushime, H; Jinno, A; Takagi, N; Shibuya, M

    1990-01-01

    We isolated a novel gene designated mak (male germ cell-associated kinase) by using weak cross-hybridization with a tyrosine kinase gene (v-ros). Sequence analysis of the cDNA corresponding to the 2.6-kilobase transcript revealed that the predicted product of rat mak consisted of 622 amino acids and contained protein kinase consensus motifs in its amino-terminal region. Comparison of the deduced amino acid sequence of mak in the kinase domain with those of other protein kinase genes demonstrated that mak was approximately 40% identical to the cdc2-CDC28 gene family in Schizosaccharomyces pombe, Saccharomyces cerevisiae, and humans but less identical to most other protein kinase gene products. Expression of mak was highly tissue specific, and its transcripts were detected almost exclusively in testicular cells entering and after meiosis but hardly detectable in ovarian cells including oocytes, after the dictyotene stage. These results suggest that the mak gene plays an important role in spermatogenesis. Images PMID:2183027

  7. Interaction between protein kinase C and protein kinase A can modulate transmitter release at the rat neuromuscular synapse.

    PubMed

    Santafé, M M; Garcia, N; Lanuza, M A; Tomàs, M; Tomàs, J

    2009-02-15

    We used intracellular recording to investigate the functional interaction between protein kinase C (PKC) and protein kinase A (PKA) signal transduction cascades in the control of transmitter release in the neuromuscular synapses from adult rats. Our results indicate that: 1) PKA and PKC are independently involved in asynchronous release. 2) Evoked acetylcholine (ACh) release is enhanced with the PKA agonist Sp-8-BrcAMP and the PKC agonist phorbol ester (PMA). 3) PKA has a constitutive role in promoting a component of normal evoked transmitter release because, when the kinase is inhibited with H-89, the release diminishes. However, the PKC inhibitor calphostin C (CaC) does not affect ACh release. 4) PKA regulates neurotransmission without PKC involvement because, after PMA or CaC modulation of the PKC activity, coupling to the ACh release of PKA can normally be stimulated with Sp-8-BrcAMP or inhibited with H-89. 5) After PKA inhibition with H-89, PKC stimulation with PMA (or inhibition with CaC) does not lead to any change in evoked ACh release. However, in PKA-stimulated preparations with Sp-8-BrcAMP, PKC becomes tonically active, thus potentiating a component of release that can now be blocked with CaC. In normal conditions, therefore, PKA was able to modulate ACh release independently of PKC activity, whereas PKA stimulation caused the PKC coupling to evoked release. In contrast, PKA inhibition prevent PKC stimulation (with the phorbol ester) and coupling to ACh output. There was therefore some dependence of PKC on PKA activity in the fine control of the neuromuscular synaptic functionalism and ACh release.

  8. Structure of Human G Protein-Coupled Receptor Kinase 2 in Complex with the Kinase Inhibitor Balanol

    SciTech Connect

    Tesmer, John J.G.; Tesmer, Valerie M.; Lodowski, David T.; Steinhagen, Henning; Huber, Jochen

    2010-07-19

    G protein-coupled receptor kinase 2 (GRK2) is a pharmaceutical target for the treatment of cardiovascular diseases such as congestive heart failure, myocardial infarction, and hypertension. To better understand how nanomolar inhibition and selectivity for GRK2 might be achieved, we have determined crystal structures of human GRK2 in complex with G{beta}{gamma} in the presence and absence of the AGC kinase inhibitor balanol. The selectivity of balanol among human GRKs is assessed.

  9. Autophosphorylation Activity of a Soluble Hexameric Histidine Kinase Correlates with the Shift in Protein Conformational Equilibrium

    PubMed Central

    Wojnowska, Marta; Yan, Jun; Sivalingam, Ganesh N.; Cryar, Adam; Gor, Jayesh; Thalassinos, Konstantinos; Djordjevic, Snezana

    2013-01-01

    Summary In a commonly accepted model, in response to stimuli, bacterial histidine kinases undergo a conformational transition between an active and inactive form. Structural information on histidine kinases is limited. By using ion mobility-mass spectrometry (IM-MS), we demonstrate an exchange between two conformational populations of histidine kinase ExsG that are linked to different levels of kinase activity. ExsG is an atypical signaling protein that incorporates an uncommon histidine kinase catalytic core at the C terminus preceded by an N-terminal “receiver domain” that is normally associated with the response regulator proteins in two-component signal transduction systems. IM-MS analysis and enzymatic assays indicate that phosphorylation of the ExsG receiver domain stabilizes the “compact” form of the protein and inhibits kinase core activity; in contrast, nucleotide binding required for kinase activity is associated with the more open conformation of ExsG. PMID:24210218

  10. Structure of shikimate kinase from Mycobacterium tuberculosis reveals the binding of shikimic acid.

    PubMed

    Pereira, José Henrique; de Oliveira, Jaim Simões; Canduri, Fernanda; Dias, Marcio Viniciusbertacine; Palma, Mário Sérgio; Basso, Luiz Augusto; Santos, Diógenes Santiago; de Azevedo, Walter Filgueira

    2004-12-01

    Tuberculosis made a resurgence in the mid-1980s and now kills approximately 3 million people a year. The re-emergence of tuberculosis as a public health threat, the high susceptibility of HIV-infected persons and the proliferation of multi-drug-resistant strains have created a need to develop new drugs. Shikimate kinase and other enzymes in the shikimate pathway are attractive targets for development of non-toxic antimicrobial agents, herbicides and anti-parasitic drugs, because the pathway is essential in these species whereas it is absent from mammals. The crystal structure of shikimate kinase from Mycobacterium tuberculosis (MtSK) complexed with MgADP and shikimic acid (shikimate) has been determined at 2.3 A resolution, clearly revealing the amino-acid residues involved in shikimate binding. This is the first three-dimensional structure of shikimate kinase complexed with shikimate. In MtSK, the Glu61 residue that is strictly conserved in shikimate kinases forms a hydrogen bond and salt bridge with Arg58 and assists in positioning the guanidinium group of Arg58 for shikimate binding. The carboxyl group of shikimate interacts with Arg58, Gly81 and Arg136 and the hydroxyl groups interact with Asp34 and Gly80. The crystal structure of MtSK-MgADP-shikimate will provide crucial information for the elucidation of the mechanism of the shikimate kinase-catalyzed reaction and for the development of a new generation of drugs against tuberculosis.

  11. Protein kinase and phosphatase activities of thylakoid membranes

    SciTech Connect

    Michel, H.; Shaw, E.K.; Bennett, J.

    1987-01-01

    Dephosphorylation of the 25 and 27 kDa light-harvesting Chl a/b proteins (LHCII) of the thylakoid membranes is catalyzed by a phosphatase which differs from previously reported thylakoid-bound phosphatases in having an alkaline pH optimum (9.0) and a requirement for Mg/sup 2 +/ ions. Dephosphorylation of the 8.3 kDa psb H gene product requires a Mg/sup 2 +/ ion concentration more than 200 fold higher than that for dephosphorylation of LHC II. The 8.3 kDa and 27 kDa proteins appear to be phosphorylated by two distinct kinases, which differ in substrate specificity and sensitivity to inhibitors. The plastoquinone antagonist 2,5-dibromo-3-methyl-6-isopropyl-benzoquinone (DBMIB) inhibits phosphorylation of the 27 kDa LHC II much more readily than phosphorylation of the 8.3 kDa protein. A similar pattern of inhibition is seen for two synthetic oligopeptides (MRKSATTKKAVC and ATQTLESSSRC) which are analogs of the phosphorylation sites of the two proteins. Possible modes of action of DBMIB are discussed. 45 refs., 7 figs., 3 tabs.

  12. Differential requirement of protein tyrosine kinases and protein kinase C in the regulation of T cell locomotion in three-dimensional collagen matrices.

    PubMed

    Entschladen, F; Niggemann, B; Zänker, K S; Friedl, P

    1997-10-01

    Locomotion of T lymphocytes within three-dimensional collagen matrices is regulated via different signaling states of the cells. Purified human CD4+ and CD8+ T cells developed a spontaneously locomoting subpopulation of about 25% of the whole population immediately after incorporation into a three-dimensional collagen matrix analyzed by time-lapse videomicroscopy. This spontaneous locomotion was accompanied by enhanced tyrosine phosphorylation of the focal adhesion kinase (FAK). Inhibition of protein tyrosine kinase (PTK) activity using genistein significantly reduced the spontaneous locomotory activity. This reduction was overcome by subsequent activation of protein kinase C (PKC) using PMA, which led to a persistent increase of locomotory activity to more than 60% of the cells. Thus, the PKC-driven type of locomotion was independent of PTK activity, whereas spontaneous locomotion was not altered by inhibition of PKC activity using calphostin C or inhibition of the serine/ threonine phosphatases pp1 and pp2A using okadaic acid. We presume that PTK activity, especially tyrosine phosphorylation of FAK, is decisively involved in the regulation of spontaneous T lymphocyte locomotion, which is independent of PKC activity. In contrast, PKC-driven locomotion is independent of tyrosine phosphorylation events, indicating that T lymphocyte locomotion is regulated by more than one signal transduction pathway. Furthermore, confocal microscopy analysis of phosphotyrosine residues, FAK, and PKC revealed an exclusive cellular distribution of these components, suggesting a regulation of T lymphocyte locomotion different from migration models developed for other cell types, which refer to a colocalization of FAK and PKC in focal adhesions.

  13. Protein Vivisection Reveals Elusive Intermediates in Folding

    SciTech Connect

    Zheng, Zhongzhou; Sosnick, Tobin R.

    2010-05-25

    Although most folding intermediates escape detection, their characterization is crucial to the elucidation of folding mechanisms. Here, we outline a powerful strategy to populate partially unfolded intermediates: A buried aliphatic residue is substituted with a charged residue (e.g., Leu {yields} Glu{sup -}) to destabilize and unfold a specific region of the protein. We applied this strategy to ubiquitin, reversibly trapping a folding intermediate in which the {beta}5-strand is unfolded. The intermediate refolds to a native-like structure upon charge neutralization under mildly acidic conditions. Characterization of the trapped intermediate using NMR and hydrogen exchange methods identifies a second folding intermediate and reveals the order and free energies of the two major folding events on the native side of the rate-limiting step. This general strategy may be combined with other methods and have broad applications in the study of protein folding and other reactions that require trapping of high-energy states.

  14. Protein vivisection reveals elusive intermediates in folding.

    PubMed

    Zheng, Zhongzhou; Sosnick, Tobin R

    2010-04-01

    Although most folding intermediates escape detection, their characterization is crucial to the elucidation of folding mechanisms. Here, we outline a powerful strategy to populate partially unfolded intermediates: A buried aliphatic residue is substituted with a charged residue (e.g., Leu-->Glu(-)) to destabilize and unfold a specific region of the protein. We applied this strategy to ubiquitin, reversibly trapping a folding intermediate in which the beta5-strand is unfolded. The intermediate refolds to a native-like structure upon charge neutralization under mildly acidic conditions. Characterization of the trapped intermediate using NMR and hydrogen exchange methods identifies a second folding intermediate and reveals the order and free energies of the two major folding events on the native side of the rate-limiting step. This general strategy may be combined with other methods and have broad applications in the study of protein folding and other reactions that require trapping of high-energy states.

  15. Polyclonal Antibodies to Phospholipid/Ca2+-Dependent Protein Kinase and Immunocytochemical Localization of the Enzyme in Rat Brain

    NASA Astrophysics Data System (ADS)

    Girard, Peggy R.; Mazzei, Gonzalo J.; Wood, John G.; Kuo, J. F.

    1985-05-01

    Antisera against phospholipid/Ca2+-dependent protein kinase (protein kinase C) were raised in rabbits. Immunospecificity of the polyclonal antibodies, as determined by immunoblot and ELISA, was shown by their reactivity to the enzyme but not to other protein kinases or any of many other proteins tested. Immunocytochemical localization of the kinase in rat brains revealed that although the enzyme was distributed broadly in different brain regions, it was highly restricted to the periphery of the nucleus of neurons in cerebral cortex and to axons and cells strongly resembling oligodendroglia in white-matter regions. Initial electron microscopy of cerebral cortex revealed that the enzyme was highly concentrated in the presynaptic terminals, and only rarely were labeled postsynaptic specialization elements seen. It is suggested that the discrete localization of the enzyme, which is distinct from that of the calmodulin/Ca2+-dependent system, may be related to certain biological and functional aspects of brain that are regulated by Ca2+ at the level of protein phosphorylation.

  16. Interleukin 2 activates extracellular signal-regulated protein kinase 2

    PubMed Central

    1993-01-01

    Interleukin 2 (IL-2) stimulated activation of the 42-kD extracellular signal-regulated kinase 2 (Erk2) in murine IL-3-dependent cells, expressing either high or intermediate affinity IL-2 receptors. Activation was both rapid, occurring within 5 min of IL-2 addition, and prolonged, remaining elevated for 30 min. Activation of Erk2 appeared to be necessary for IL-2 stimulation of proliferation, as deletion of a region of the cytoplasmic domain of the IL-2 receptor beta chain, essential for IL-2 stimulation of proliferation, abolished Erk2 activation by IL-2. Furthermore, cells that had been deprived of cytokine for 24 h were then refractory to IL-2 stimulation of both Erk2 activity and proliferation. However, elevation of Erk2 activity was not sufficient to stimulate proliferation, as protein kinase C activation stimulated Erk2 activity but not DNA synthesis. Also, cells exposed to IL-2 in the presence of rapamycin showed full Erk2 activation but not DNA synthesis. These data suggest that IL-2 must stimulate both Erk2 activity and a further pathway(s) to trigger cell proliferation. PMID:8376945

  17. The protein kinase TOUSLED facilitates RNAi in Arabidopsis

    PubMed Central

    Uddin, Mohammad Nazim; Dunoyer, Patrice; Schott, Gregory; Akhter, Salina; Shi, Chunlin; Lucas, William J.; Voinnet, Olivier; Kim, Jae-Yean

    2014-01-01

    RNA silencing is an evolutionarily conserved mechanism triggered by double-stranded RNA that is processed into 21- to 24-nt small interfering (si)RNA or micro (mi)RNA by RNaseIII-like enzymes called Dicers. Gene regulations by RNA silencing have fundamental implications in a large number of biological processes that include antiviral defense, maintenance of genome integrity and the orchestration of cell fates. Although most generic or core components of the various plant small RNA pathways have been likely identified over the past 15 years, factors involved in RNAi regulation through post-translational modifications are just starting to emerge, mostly through forward genetic studies. A genetic screen designed to identify factors required for RNAi in Arabidopsis identified the serine/threonine protein kinase, TOUSLED (TSL). Mutations in TSL affect exogenous and virus-derived siRNA activity in a manner dependent upon its kinase activity. By contrast, despite their pleiotropic developmental phenotype, tsl mutants show no defect in biogenesis or activity of miRNA or endogenous trans-acting siRNA. These data suggest a possible role for TSL phosphorylation in the specific regulation of exogenous and antiviral RNA silencing in Arabidopsis and identify TSL as an intrinsic regulator of RNA interference. PMID:24920830

  18. The herpes simplex virus 1 US3 protein kinase blocks caspase-dependent double cleavage and activation of the proapoptotic protein BAD.

    PubMed

    Benetti, Luca; Munger, Joshua; Roizman, Bernard

    2003-06-01

    An earlier report showed that the U(S)3 protein kinase blocked the apoptosis induced by the herpes simplex virus 1 (HSV-1) d120 mutant at a premitochondrial stage. Further studies revealed that the kinase also blocks programmed cell death induced by the proapoptotic protein BAD. Here we report the effects of the U(S)3 protein kinase on the function and state of a murine BAD protein. Specifically, (i) in uninfected cells, BAD was processed by at least two proteolytic cleavages that were blocked by a general caspase inhibitor. The untreated transduced cells expressed elevated caspase 3 activity. (ii) In cells cotransduced with the U(S)3 protein kinase, the BAD protein was not cleaved and the caspase 3 activity was not elevated. (iii) Inasmuch as the U(S)3 protein kinase blocked the proapoptotic activity and cleavage of a mutant (BAD3S/A) in which the codons for the regulatory serines at positions 112, 136, and 155 were each replaced with alanine codons, the U(S)3 protein kinase does not act by phosphorylation of these sites nor was the phosphorylation of these sites required for the antiapoptotic function of the U(S)3 protein kinase. (iv) The U(S)3 protein kinase did not enable the binding of the BAD3S/A mutant to the antiapoptotic proteins 14-3-3. Finally, (v) whereas cleavage of BAD at ASP56 and ASP61 has been reported and results in the generation of a more effective proapoptotic protein with an M(r) of 15,000, in this report we also show the existence of a second caspase-dependent cleavage site most likely at the ASP156 that is predicted to inactivate the proapoptotic activity of BAD. We conclude that the primary effect of U(S)3 was to block the caspases that cleave BAD at either residue 56 or 61 predicted to render the protein more proapoptotic or at residue 156, which would inactivate the protein.

  19. A novel human STE20-related protein kinase, HGK, that specifically activates the c-Jun N-terminal kinase signaling pathway.

    PubMed

    Yao, Z; Zhou, G; Wang, X S; Brown, A; Diener, K; Gan, H; Tan, T H

    1999-01-22

    The yeast serine/threonine kinase STE20 activates a signaling cascade that includes STE11 (mitogen-activated protein kinase kinase kinase), STE7 (mitogen-activated protein kinase kinase), and FUS3/KSS1 (mitogen-activated protein kinase) in response to signals from both Cdc42 and the heterotrimeric G proteins associated with transmembrane pheromone receptors. Using degenerate polymerase chain reaction, we have isolated a human cDNA encoding a protein kinase homologous to STE20. This protein kinase, designated HPK/GCK-like kinase (HGK), has nucleotide sequences that encode an open reading frame of 1165 amino acids with 11 kinase subdomains. HGK was a serine/threonine protein kinase that specifically activated the c-Jun N-terminal kinase (JNK) signaling pathway when transfected into 293T cells, but it did not stimulate either the extracellular signal-regulated kinase or p38 kinase pathway. HGK also increased AP-1-mediated transcriptional activity in vivo. HGK-induced JNK activation was inhibited by the dominant-negative MKK4 and MKK7 mutants. The dominant-negative mutant of TAK1, but not MEKK1 or MAPK upstream kinase (MUK), strongly inhibited HGK-induced JNK activation. TNF-alpha activated HGK in 293T cells, as well as the dominant-negative HGK mutants, inhibited TNF-alpha-induced JNK activation. These results indicate that HGK, a novel activator of the JNK pathway, may function through TAK1, and that the HGK --> TAK1 --> MKK4, MKK7 --> JNK kinase cascade may mediate the TNF-alpha signaling pathway. PMID:9890973

  20. Global Phosphoproteomic Analysis of Human Skeletal Muscle Reveals a Network of Exercise-Regulated Kinases and AMPK Substrates.

    PubMed

    Hoffman, Nolan J; Parker, Benjamin L; Chaudhuri, Rima; Fisher-Wellman, Kelsey H; Kleinert, Maximilian; Humphrey, Sean J; Yang, Pengyi; Holliday, Mira; Trefely, Sophie; Fazakerley, Daniel J; Stöckli, Jacqueline; Burchfield, James G; Jensen, Thomas E; Jothi, Raja; Kiens, Bente; Wojtaszewski, Jørgen F P; Richter, Erik A; James, David E

    2015-11-01

    Exercise is essential in regulating energy metabolism and whole-body insulin sensitivity. To explore the exercise signaling network, we undertook a global analysis of protein phosphorylation in human skeletal muscle biopsies from untrained healthy males before and after a single high-intensity exercise bout, revealing 1,004 unique exercise-regulated phosphosites on 562 proteins. These included substrates of known exercise-regulated kinases (AMPK, PKA, CaMK, MAPK, mTOR), yet the majority of kinases and substrate phosphosites have not previously been implicated in exercise signaling. Given the importance of AMPK in exercise-regulated metabolism, we performed a targeted in vitro AMPK screen and employed machine learning to predict exercise-regulated AMPK substrates. We validated eight predicted AMPK substrates, including AKAP1, using targeted phosphoproteomics. Functional characterization revealed an undescribed role for AMPK-dependent phosphorylation of AKAP1 in mitochondrial respiration. These data expose the unexplored complexity of acute exercise signaling and provide insights into the role of AMPK in mitochondrial biochemistry.

  1. Protein kinase C mediates cholinergically regulated protein phosphorylation in a Cl(-)-secreting epithelium.

    PubMed

    Cohn, J A

    1990-02-01

    T84 cell monolayers were used to study the cholinergic regulation of protein phosphorylation in epithelial cells. When T84 cell monolayers are labeled with 32Pi and stimulated with carbachol, six proteins exhibit altered phosphorylation. The most prominent response is a fivefold increase in labeling of p83, an acidic protein of Mr 83,000. Increasing labeling of p83 parallels stimulated secretion with respect to the onset of agonist action, agonist potency, and antagonism by atropine. However, the p83 and secretory responses differ in that the p83 response is more sustained. When T84 cell fractions are incubated with [gamma-32P]ATP, Ca2(+)-phospholipid stimulates p83 labeling. Phosphorylation of p83 also occurs when a T84 cell extract is incubated with purified protein kinase C and when intact cells are exposed to phorbol myristate acetate. p83 does not become phosphorylated in cell fractions incubated with adenosine 3',5'-cyclic monophosphate (cAMP) or in monolayers stimulated with agonists acting via cAMP. Thus carbachol stimulates the phosphorylation of an endogenous substrate for protein kinase C in T84 cells. The duration of this phosphorylation response suggests that protein kinase C may mediate a sustained response to carbachol, possibly acting to limit the duration of stimulated secretion.

  2. Exploitation of latent protein allostery enables the evolution of novel and divergent MAP kinase regulation

    PubMed Central

    Coyle, Scott M.; Flores, Jonathan; Lim, Wendell A.

    2013-01-01

    SUMMARY Allosteric interactions provide precise spatiotemporal control over signaling proteins, but how allosteric activators and their targets co-evolve is poorly understood. Here, we trace the evolution of two allosteric activator motifs within the yeast scaffold protein Ste5 that specifically target the mating MAP kinase Fus3. One activator (Ste5-VWA) provides pathway insulation and dates to the divergence of Fus3 from its paralog, Kss1; a second activator (Ste5-FBD) that tunes mating behavior is, in contrast, not conserved in most lineages. Surprisingly, both Ste5 activator motifs could regulate MAP kinases that diverged from Fus3 prior to the emergence of Ste5, suggesting that Ste5 activators arose by exploiting latent regulatory features already present in the MAPK ancestor. The magnitude of this latent allosteric potential drifts widely among pre-Ste5 MAP kinases, providing a pool of hidden phenotypic diversity that, when revealed by new activators, could lead to functional divergence and the evolution of distinct signaling behaviors. PMID:23953117

  3. Heat Shock Factor 1 Is a Substrate for p38 Mitogen-Activated Protein Kinases

    PubMed Central

    Dayalan Naidu, Sharadha; Sutherland, Calum; Zhang, Ying; Risco, Ana; de la Vega, Laureano; Caunt, Christopher J.; Hastie, C. James; Lamont, Douglas J.; Torrente, Laura; Chowdhry, Sudhir; Benjamin, Ivor J.; Keyse, Stephen M.; Cuenda, Ana

    2016-01-01

    Heat shock factor 1 (HSF1) monitors the structural integrity of the proteome. Phosphorylation at S326 is a hallmark for HSF1 activation, but the identity of the kinase(s) phosphorylating this site has remained elusive. We show here that the dietary agent phenethyl isothiocyanate (PEITC) inhibits heat shock protein 90 (Hsp90), the main negative regulator of HSF1; activates p38 mitogen-activated protein kinase (MAPK); and increases S326 phosphorylation, trimerization, and nuclear translocation of HSF1, and the transcription of a luciferase reporter, as well as the endogenous prototypic HSF1 target Hsp70. In vitro, all members of the p38 MAPK family rapidly and stoichiometrically catalyze the S326 phosphorylation. The use of stable knockdown cell lines and inhibitors indicated that among the p38 MAPKs, p38γ is the principal isoform responsible for the phosphorylation of HSF1 at S326 in cells. A protease-mass spectrometry approach confirmed S326 phosphorylation and unexpectedly revealed that p38 MAPK also catalyzes the phosphorylation of HSF1 at S303/307, previously known repressive posttranslational modifications. Thus, we have identified p38 MAPKs as highly efficient catalysts for the phosphorylation of HSF1. Furthermore, our findings suggest that the magnitude and persistence of activation of p38 MAPK are important determinants of the extent and duration of the heat shock response. PMID:27354066

  4. Regulation of protein phosphatase inhibitor-1 by cyclin-dependent kinase 5.

    PubMed

    Nguyen, Chan; Nishi, Akinori; Kansy, Janice W; Fernandez, Joseph; Hayashi, Kanehiro; Gillardon, Frank; Hemmings, Hugh C; Nairn, Angus C; Bibb, James A

    2007-06-01

    Inhibitor-1, the first identified endogenous inhibitor of protein phosphatase 1 (PP-1), was previously reported to be a substrate for cyclin-dependent kinase 5 (Cdk5) at Ser67. Further investigation has revealed the presence of an additional Cdk5 site identified by mass spectrometry and confirmed by site-directed mutagenesis as Ser6. Basal levels of phospho-Ser6 inhibitor-1, as detected by a phosphorylation state-specific antibody against the site, existed in specific regions of the brain and varied with age. In the striatum, basal in vivo phosphorylation and dephosphorylation of Ser6 were mediated by Cdk5, PP-2A, and PP-1, respectively. Additionally, calcineurin contributed to dephosphorylation under conditions of high Ca2+. In biochemical assays the function of Cdk5-dependent phosphorylation of inhibitor-1 at Ser6 and Ser67 was demonstrated to be an intramolecular impairment of the ability of inhibitor-1 to be dephosphorylated at Thr35; this effect was recapitulated in two systems in vivo. Dephosphorylation of inhibitor-1 at Thr35 is equivalent to inactivation of the protein, as inhibitor-1 only serves as an inhibitor of PP-1 when phosphorylated by cAMP-dependent kinase (PKA) at Thr35. Thus, inhibitor-1 serves as a critical junction between kinase- and phosphatase-signaling pathways, linking PP-1 to not only PKA and calcineurin but also Cdk5.

  5. Activation of protein kinase C in permeabilized human neuroblastoma SH-SY5Y cells.

    PubMed

    Larsson, C; Saermark, T; Mau, S; Simonsson, P

    1992-08-01

    The activation of protein kinase C was investigated in digitonin-permeabilized human neuroblastoma SH-SY5Y cells by measuring the phosphorylation of the specific protein kinase C substrate myelin basic protein4-14. The phosphorylation was inhibited by the protein kinase C inhibitory peptide PKC19-36 and was associated to a translocation of the enzyme to the membrane fractions of the SH-SY5Y cells. 1,2-Dioctanoyl-sn-glycerol had no effect on protein kinase C activity unless the calcium concentration was raised to concentrations found in stimulated cells (above 100 nM). Calcium in the absence of other activators did not stimulate protein kinase C. Phorbol 12-myristate 13-acetate was not dependent on calcium for the activation or the translocation of protein kinase C. The induced activation was sustained for 10 min, and thereafter only a small net phosphorylation of the substrate could be detected. Calcium or dioctanoylglycerol, when applied alone, only caused a minor translocation, whereas in combination a marked translocation was observed. Arachidonic acid (10 microM) enhanced protein kinase C activity in the presence of submaximal concentrations of calcium and dioctanoylglycerol. Quinacrine and p-bromophenacyl bromide did not inhibit calcium- and dioctanoylglycerol-induced protein kinase C activity at concentrations which are considered to be sufficient for phospholipase A2 inhibition.

  6. Calcium-Dependent Protein Kinases from Arabidopsis Show Substrate Specificity Differences in an Analysis of 103 Substrates

    PubMed Central

    Curran, Amy; Chang, Ing-Feng; Chang, Chia-Lun; Garg, Shilpi; Miguel, Rodriguez Milla; Barron, Yoshimi D.; Li, Ying; Romanowsky, Shawn; Cushman, John C.; Gribskov, Michael; Harmon, Alice C.; Harper, Jeffrey F.

    2011-01-01

    The identification of substrates represents a critical challenge for understanding any protein kinase-based signal transduction pathway. In Arabidopsis, there are more than 1000 different protein kinases, 34 of which belong to a family of Ca2+-dependent protein kinases (CPKs). While CPKs are implicated in regulating diverse aspects of plant biology, from ion transport to transcription, relatively little is known about isoform-specific differences in substrate specificity, or the number of phosphorylation targets. Here, in vitro kinase assays were used to compare phosphorylation targets of four CPKs from Arabidopsis (CPK1, 10, 16, and 34). Significant differences in substrate specificity for each kinase were revealed by assays using 103 different substrates. For example CPK16 phosphorylated Serine 109 in a peptide from the stress-regulated protein, Di19-2 with KM ∼70 μM, but this site was not phosphorylated significantly by CPKs 1, 10, or 34. In contrast, CPKs 1, 10, and 34 phosphorylated 93 other peptide substrates not recognized by CPK16. Examples of substrate specificity differences among all four CPKs were verified by kinetic analyses. To test the correlation between in vivo phosphorylation events and in vitro kinase activities, assays were performed with 274 synthetic peptides that contained phosphorylation sites previously mapped in proteins isolated from plants (in vivo-mapped sites). Of these, 74 (27%) were found to be phosphorylated by at least one of the four CPKs tested. This 27% success rate validates a robust strategy for linking the activities of specific kinases, such as CPKs, to the thousands of in planta phosphorylation sites that are being uncovered by emerging technologies. PMID:22645532

  7. Citron rho-interacting kinase, a novel tissue-specific ser/thr kinase encompassing the Rho-Rac-binding protein Citron.

    PubMed

    Di Cunto, F; Calautti, E; Hsiao, J; Ong, L; Topley, G; Turco, E; Dotto, G P

    1998-11-01

    We have identified a novel serine/threonine kinase belonging to the myotonic dystrophy kinase family. The kinase can be produced in at least two different isoforms: a approximately 240-kDa protein (Citron Rho-interacting kinase, CRIK), in which the kinase domain is followed by the sequence of Citron, a previously identified Rho/Rac binding protein; a approximately 54-kDa protein (CRIK-short kinase (SK)), which consists mostly of the kinase domain. CRIK and CRIK-SK proteins are capable of phosphorylating exogenous substrates as well as of autophosphorylation, when tested by in vitro kinase assays after expression into COS7 cells. CRIK kinase activity is increased severalfold by coexpression of costitutively active Rho, while active Rac has more limited effects. Kinase activity of endogenous CRIK is indicated by in vitro kinase assays after immunoprecipitation with antibodies recognizing the Citron moiety of the protein. When expressed in keratinocytes, full-length CRIK, but not CRIK-SK, localizes into corpuscular cytoplasmic structures and elicits recruitment of actin into these structures. The previously reported Rho-associated kinases ROCK I and II are ubiquitously expressed. In contrast, CRIK exhibits a restricted pattern of expression, suggesting that this kinase may fulfill a more specialized function in specific cell types.

  8. Glucose deprivation increases tau phosphorylation via P38 mitogen-activated protein kinase.

    PubMed

    Lauretti, Elisabetta; Praticò, Domenico

    2015-12-01

    Alterations of glucose metabolism have been observed in Alzheimer's disease (AD) brain. Previous studies showed that glucose deprivation increases amyloidogenesis via a BACE-1-dependent mechanism. However, no data are available on the effect that this condition may have on tau phosphorylation. In this study, we exposed neuronal cells to a glucose-free medium and investigated the effect on tau phosphorylation. Compared with controls, cells incubated in the absence of glucose had a significant increase in tau phosphorylation at epitopes Ser202/Thr205 and Ser404, which was associated with a selective activation of the P38 mitogen-activated protein kinase. Pharmacological inhibition of this kinase prevented the increase in tau phosphorylation, while fluorescence studies revealed its co-localization with phosphorylated tau. The activation of P38 was secondary to the action of the apoptosis signal-regulating kinase 1, as its down-regulation prevented it. Finally, glucose deprivation induced cell apoptosis, which was associated with a significant increase in both caspase 3 and caspase 12 active forms. Taken together, our studies reveal a new mechanism whereby glucose deprivation can modulate AD pathogenesis by influencing tau phosphorylation and suggest that this pathway may be a new therapeutic target for AD.

  9. Computational study of Gleevec and G6G reveals molecular determinants of kinase inhibitor selectivity

    SciTech Connect

    Lin, Yen -Lin; Meng, Yilin; Huang, Lei; Roux, Benoît

    2014-10-22

    Gleevec is a potent inhibitor of Abl tyrosine kinase but not of the highly homologous c-Src kinase. Because the ligand binds to an inactive form of the protein in which an Asp-Phe-Gly structural motif along the activation loop adopts a so-called DFG-out conformation, it was suggested that binding specificity was controlled by a “conformational selection” mechanism. In this context, the binding affinity displayed by the kinase inhibitor G6G poses an intriguing challenge. Although it possesses a chemical core very similar to that of Gleevec, G6G is a potent inhibitor of both Abl and c-Src kinases. Both inhibitors bind to the DFG-out conformation of the kinases, which seems to be in contradiction with the conformational selection mechanism. To address this issue and display the hidden thermodynamic contributions affecting the binding selectivity, molecular dynamics free energy simulations with explicit solvent molecules were carried out. Relative to Gleevec, G6G forms highly favorable van der Waals dispersive interactions upon binding to the kinases via its triazine functional group, which is considerably larger than the corresponding pyridine moiety in Gleevec. Upon binding of G6G to c-Src, these interactions offset the unfavorable free energy cost of the DFG-out conformation. When binding to Abl, however, G6G experiences an unfavorable free energy penalty due to steric clashes with the phosphate-binding loop, yielding an overall binding affinity that is similar to that of Gleevec. Such steric clashes are absent when G6G binds to c-Src, due to the extended conformation of the phosphate-binding loop.

  10. Computational study of Gleevec and G6G reveals molecular determinants of kinase inhibitor selectivity

    DOE PAGESBeta

    Lin, Yen -Lin; Meng, Yilin; Huang, Lei; Roux, Benoît

    2014-10-22

    Gleevec is a potent inhibitor of Abl tyrosine kinase but not of the highly homologous c-Src kinase. Because the ligand binds to an inactive form of the protein in which an Asp-Phe-Gly structural motif along the activation loop adopts a so-called DFG-out conformation, it was suggested that binding specificity was controlled by a “conformational selection” mechanism. In this context, the binding affinity displayed by the kinase inhibitor G6G poses an intriguing challenge. Although it possesses a chemical core very similar to that of Gleevec, G6G is a potent inhibitor of both Abl and c-Src kinases. Both inhibitors bind to themore » DFG-out conformation of the kinases, which seems to be in contradiction with the conformational selection mechanism. To address this issue and display the hidden thermodynamic contributions affecting the binding selectivity, molecular dynamics free energy simulations with explicit solvent molecules were carried out. Relative to Gleevec, G6G forms highly favorable van der Waals dispersive interactions upon binding to the kinases via its triazine functional group, which is considerably larger than the corresponding pyridine moiety in Gleevec. Upon binding of G6G to c-Src, these interactions offset the unfavorable free energy cost of the DFG-out conformation. When binding to Abl, however, G6G experiences an unfavorable free energy penalty due to steric clashes with the phosphate-binding loop, yielding an overall binding affinity that is similar to that of Gleevec. Such steric clashes are absent when G6G binds to c-Src, due to the extended conformation of the phosphate-binding loop.« less

  11. Chromatographic resolution of altered forms of protein kinase C

    SciTech Connect

    Ashendel, C.L.; Minor, P.L.; Baudoin, P.A.; Carlos, M.

    1987-05-01

    Rapid chromatographic resolution of protein kinase C (PKC) in extracts of rat brain on DEAE-cellulose yielded two major peaks of activity. These fractions bound phorbol esters with identical affinity and specificity and had similar ratios of PKC to phorbol ester-binding activities. Chicken egg yolk antibodies raised to PKC in the first fraction reacted with 74 to 76 kilodalton peptides in the second fraction. Chromatography of each fraction on hydroxylapatite yielded similar distributions of three PKC isozymes. Rechromatography of the DEAE-cellulose fractions on DEAE-cellulose confirmed that these forms of PKC were not rapidly interconvertible. Results of experiments in which extracts or fractions were incubated with MgATP and phosphatase inhibitors were consistent with elution of dephospho-PKC in the first fraction while the second fraction contained phospho-PKC. If confirmed, this suggests that a substantial fraction of PKC in rat and mouse tissues exists in the phosphorylated form.

  12. Intramolecular conformational changes optimize protein kinase C signaling.

    PubMed

    Antal, Corina E; Violin, Jonathan D; Kunkel, Maya T; Skovsø, Søs; Newton, Alexandra C

    2014-04-24

    Optimal tuning of enzyme signaling is critical for cellular homeostasis. We use fluorescence resonance energy transfer reporters in live cells to follow conformational transitions that tune the affinity of a multidomain signal transducer, protein kinase C (PKC), for optimal response to second messengers. This enzyme comprises two diacylglycerol sensors, the C1A and C1B domains, that have a sufficiently high intrinsic affinity for ligand so that the enzyme would be in a ligand-engaged, active state if not for mechanisms that mask its domains. We show that both diacylglycerol sensors are exposed in newly synthesized PKC and that conformational transitions following priming phosphorylations mask the domains so that the lower affinity sensor, the C1B domain, is the primary diacylglycerol binder. The conformational rearrangements of PKC serve as a paradigm for how multimodule transducers optimize their dynamic range of signaling.

  13. Intramolecular conformational changes optimize protein kinase C signaling.

    PubMed

    Antal, Corina E; Violin, Jonathan D; Kunkel, Maya T; Skovsø, Søs; Newton, Alexandra C

    2014-04-24

    Optimal tuning of enzyme signaling is critical for cellular homeostasis. We use fluorescence resonance energy transfer reporters in live cells to follow conformational transitions that tune the affinity of a multidomain signal transducer, protein kinase C (PKC), for optimal response to second messengers. This enzyme comprises two diacylglycerol sensors, the C1A and C1B domains, that have a sufficiently high intrinsic affinity for ligand so that the enzyme would be in a ligand-engaged, active state if not for mechanisms that mask its domains. We show that both diacylglycerol sensors are exposed in newly synthesized PKC and that conformational transitions following priming phosphorylations mask the domains so that the lower affinity sensor, the C1B domain, is the primary diacylglycerol binder. The conformational rearrangements of PKC serve as a paradigm for how multimodule transducers optimize their dynamic range of signaling. PMID:24631122

  14. Conformation-selective inhibitors reveal differences in the activation and phosphate-binding loops of the tyrosine kinases Abl and Src.

    PubMed

    Hari, Sanjay B; Perera, B Gayani K; Ranjitkar, Pratistha; Seeliger, Markus A; Maly, Dustin J

    2013-12-20

    Over the past decade, an increasingly diverse array of potent and selective inhibitors that target the ATP-binding sites of protein kinases have been developed. Many of these inhibitors, like the clinically approved drug imatinib (Gleevec), stabilize a specific catalytically inactive ATP-binding site conformation of their kinases targets. Imatinib is notable in that it is highly selective for its kinase target, Abl, over other closely related tyrosine kinases, such as Src. In addition, imatinib is highly sensitive to the phosphorylation state of Abl's activation loop, which is believed to be a general characteristic of all inhibitors that stabilize a similar inactive ATP-binding site conformation. In this report, we perform a systematic analysis of a diverse series of ATP-competitive inhibitors that stabilize a similar inactive ATP-binding site conformation as imatinib with the tyrosine kinases Src and Abl. In contrast to imatinib, many of these inhibitors have very similar potencies against Src and Abl. Furthermore, only a subset of this class of inhibitors is sensitive to the phosphorylation state of the activation loop of these kinases. In attempting to explain this observation, we have uncovered an unexpected correlation between Abl's activation loop and another flexible active site feature, called the phosphate-binding loop (p-loop). These studies shed light on how imatinib is able to obtain its high target selectivity and reveal how the conformational preference of flexible active site regions can vary between closely related kinases.

  15. Structural Characterization of Proline-rich Tyrosine Kinase 2 (PYK2) Reveals a Unique (DFG-out) Conformation and Enables Inhibitor Design

    SciTech Connect

    Han, Seungil; Mistry, Anil; Chang, Jeanne S.; Cunningham, David; Griffor, Matt; Bonnette, Peter C.; Wang, Hong; Chrunyk, Boris A.; Aspnes, Gary E.; Walker, Daniel P.; Brosius, Arthur D.; Buckbinder, Leonard; Pfizer

    2009-05-21

    Proline-rich tyrosine kinase 2 (PYK2) is a cytoplasmic, non-receptor tyrosine kinase implicated in multiple signaling pathways. It is a negative regulator of osteogenesis and considered a viable drug target for osteoporosis treatment. The high-resolution structures of the human PYK2 kinase domain with different inhibitor complexes establish the conventional bilobal kinase architecture and show the conformational variability of the DFG loop. The basis for the lack of selectivity for the classical kinase inhibitor, PF-431396, within the FAK family is explained by our structural analyses. Importantly, the novel DFG-out conformation with two diarylurea inhibitors (BIRB796, PF-4618433) reveals a distinct subclass of non-receptor tyrosine kinases identifiable by the gatekeeper Met-502 and the unique hinge loop conformation of Leu-504. This is the first example of a leucine residue in the hinge loop that blocks the ATP binding site in the DFG-out conformation. Our structural, biophysical, and pharmacological studies suggest that the unique features of the DFG motif, including Leu-504 hinge-loop variability, can be exploited for the development of selective protein kinase inhibitors.

  16. Biochemical and biophysical characterization of four EphB kinase domains reveals contrasting thermodynamic, kinetic and inhibition profiles

    PubMed Central

    Overman, Ross C.; Debreczeni, Judit E.; Truman, Caroline M.; McAlister, Mark S.; Attwood, Teresa K.

    2013-01-01

    The Eph (erythropoietin-producing hepatocellular carcinoma) B receptors are important in a variety of cellular processes through their roles in cell-to-cell contact and signalling; their up-regulation and down-regulation has been shown to have implications in a variety of cancers. A greater understanding of the similarities and differences within this small, highly conserved family of tyrosine kinases will be essential to the identification of effective therapeutic opportunities for disease intervention. In this study, we have developed a route to production of multi-milligram quantities of highly purified, homogeneous, recombinant protein for the kinase domain of these human receptors in Escherichia coli. Analyses of these isolated catalytic fragments have revealed stark contrasts in their amenability to recombinant expression and their physical properties: e.g., a >16°C variance in thermal stability, a 3-fold difference in catalytic activity and disparities in their inhibitor binding profiles. We find EphB3 to be an outlier in terms of both its intrinsic stability, and more importantly its ligand-binding properties. Our findings have led us to speculate about both their biological significance and potential routes for generating EphB isozyme-selective small-molecule inhibitors. Our comprehensive methodologies provide a template for similar in-depth studies of other kinase superfamily members. PMID:23627399

  17. Biochemical and biophysical characterization of four EphB kinase domains reveals contrasting thermodynamic, kinetic and inhibition profiles.

    PubMed

    Overman, Ross C; Debreczeni, Judit E; Truman, Caroline M; McAlister, Mark S; Attwood, Teresa K

    2013-01-01

    The Eph (erythropoietin-producing hepatocellular carcinoma) B receptors are important in a variety of cellular processes through their roles in cell-to-cell contact and signalling; their up-regulation and down-regulation has been shown to have implications in a variety of cancers. A greater understanding of the similarities and differences within this small, highly conserved family of tyrosine kinases will be essential to the identification of effective therapeutic opportunities for disease intervention. In this study, we have developed a route to production of multi-milligram quantities of highly purified, homogeneous, recombinant protein for the kinase domain of these human receptors in Escherichia coli. Analyses of these isolated catalytic fragments have revealed stark contrasts in their amenability to recombinant expression and their physical properties: e.g., a >16°C variance in thermal stability, a 3-fold difference in catalytic activity and disparities in their inhibitor binding profiles. We find EphB3 to be an outlier in terms of both its intrinsic stability, and more importantly its ligand-binding properties. Our findings have led us to speculate about both their biological significance and potential routes for generating EphB isozyme-selective small-molecule inhibitors. Our comprehensive methodologies provide a template for similar in-depth studies of other kinase superfamily members. PMID:23627399

  18. HPLC-DAD protein kinase inhibitor analysis in human serum.

    PubMed

    Dziadosz, Marek; Lessig, Rüdiger; Bartels, Heidemarie

    2012-04-15

    We here describe an HPLC-DAD method to analyse different protein kinase inhibitors. Potential applications of this method are pharmacokinetic studies and therapeutic drug monitoring. Optimised chromatography conditions resulted in a very good separation of seven inhibitors (vatalanib, bosutinib, canertinib, tandutinib, pazopanib, dasatinib - internal standard and erlotinib). The good sensitivity makes this method competitive with LC/MS/MS. The separation was performed with a Lichrospher 100-5 RP8, 250 mm × 4 mm column maintained at 30 ± 1 °C, and with a mobile phase of 0.05 M H(3)PO(4)/KH(2)PO(4) (pH=2.3)-acetonitrile (7:3, v/v) at a flow rate of 0.7 mL/min. A simple and fast sample preparation sequence with liquid-liquid extraction led to good recoveries (73-90%) of all analytes. The recovery hardly reached 50% only for pazopanib. This method can also be used for targeted protein kinase inhibitor quantification. A perfect linearity in the validated range (20-10,000 ng/mL) and an LOQ of 20 ng/mL were achieved. The relative standard deviations and accuracies of all examined drug concentrations gave values much lower than 15% both for between- and within-batch calculations. All analysed PKIs were stable for 6 months in a 1mg/mL dimethyl sulfoxide stock solution. Vatalanib, bosutinib and erlotinib were also stable in human serum in the whole examined concentration range. PMID:22425385

  19. Examining Ligand-Based Stabilization of Proteins in Cells with MEK1 Kinase Inhibitors.

    PubMed

    Auld, Douglas S; Davis, Christopher A; Jimenez, Marta; Knight, Sinead; Orme, Jonathon P

    2015-06-01

    In this study, we describe the evaluation of a cell-based protein stability assay using β-galactosidase fragment complementation technology performed in two independent laboratories. The assay is based on the ability of certain ligands to bind to a protein leading to a ligand-protein complex that has a different stability than the free protein. The assay employed a prolabeled-tagged MEK1 kinase stably expressed in A549 cells and this was used to evaluate focused sets of compounds containing known MEK1inhibitors as well as a random set of compounds. An assay using a prolabeled-tagged lysine methyltransferase known as G9a expressed in A549 cells was used as a counterscreen. In one study, it was found that the majority of MEK1 inhibitors were either found as inactive (52%) or showed a selective inhibitory response (18%) in the cell-based MEK1 assay; however, eight compounds showed a specific activation response consistent with stabilization of MEK1 in cells. Examination of these stabilizing compounds showed that three of these were analogs of hypothemycin, a known covalent allosteric MEK1 inhibitor, while the remaining compounds covered one structural class. Both laboratories were able to confirm activity in the cell-based MEK1 assay for known MEK1 inhibitors and found that this activity was highly selective over the G9a counterscreen assay. Screening of a mechanism of action library containing compounds with bioactivity annotations against the cell-based MEK1 assay did not reveal any mechanisms leading to an increase in signal other than inhibitors of MEK1. This study supports that the MEK1 cellular protein stability assay is sensitive to certain MEK1 inhibitors, often noncompetitive inhibitors with respect to ATP. The cellular stability assay format could be useful to rapidly filter kinase inhibitor hit lists for allosteric kinase inhibitors and support target engagement in cells.

  20. Stress-activated mitogen-activated protein kinases c-Jun NH2-terminal kinase and p38 target Cdc25B for degradation.

    PubMed

    Uchida, Sanae; Yoshioka, Katsuji; Kizu, Ryoichi; Nakagama, Hitoshi; Matsunaga, Tsukasa; Ishizaka, Yukihito; Poon, Randy Y C; Yamashita, Katsumi

    2009-08-15

    Cdc25 dual specificity phosphatases positively regulate the cell cycle by activating cyclin-dependent kinase/cyclin complexes. Of the three mammalian Cdc25 isoforms, Cdc25A is phosphorylated by genotoxic stress-activated Chk1 or Chk2, which triggers its SCFbeta-TrCP-mediated degradation. However, the roles of Cdc25B and Cdc25C in cell stress checkpoints remain inconclusive. We herein report that c-Jun NH2-terminal kinase (JNK) induces the degradation of Cdc25B. Nongenotoxic stress induced by anisomycin caused rapid degradation of Cdc25B as well as Cdc25A. Cdc25B degradation was dependent mainly on JNK and partially on p38 mitogen-activated protein kinase (p38). Accordingly, cotransfection with JNK1, JNK2, or p38 destabilized Cdc25B. In vitro kinase assays and site-directed mutagenesis experiments revealed that the critical JNK and p38 phosphorylation site in Cdc25B was Ser101. Cdc25B with Ser101 mutated to alanine was refractory to anisomycin-induced degradation, and cells expressing such mutant Cdc25B proteins were able to override the anisomycin-induced G2 arrest. These results highlight the importance of a novel JNK/p38-Cdc25B axis for a nongenotoxic stress-induced cell cycle checkpoint.

  1. Regulation of the MAPK pathway by raf kinase inhibitory protein.

    PubMed

    Vandamme, Drieke; Herrero, Ana; Al-Mulla, Fahd; Kolch, Walter

    2014-01-01

    The Raf kinase inhibitor protein 1 (RKIP-1) was the first reported endogenous inhibitor of Raf-1-MEK-ERK/MAPK cascade, by interfering with the phosphorylation of MEK by Raf-1. However, RKIP's functions related to the MAPK signaling are far more complex. Newer data indicate that by modulating different protein-protein interactions, RKIP is involved in fine-tuning cell signaling, modulating ERK dynamics, and regulating cross talk between different pathways. Here, we describe the molecular mechanisms by which RKIP controls MAPK signaling at different levels and vice versa and its regulation via feedback phosphorylation. We also focus on several discrepancies and questions that remain, such as the RKIP binding regulation by Raf-1 N-region phosphorylation, the possible B-Raf inhibition, and the effects of RKIP-lipid binding. We also describe how RKIP's role as key signaling modulator of many cell fate decisions leads to the fact that fine control of RKIP activity and regulation is crucial to avoid pathological processes, such as metastasis, pulmonary arterial hypertension, and heart failure.

  2. Human pyruvate kinase M2: a multifunctional protein.

    PubMed

    Gupta, Vibhor; Bamezai, Rameshwar N K

    2010-11-01

    Glycolysis, a central metabolic pathway, harbors evolutionary conserved enzymes that modulate and potentially shift the cellular metabolism on requirement. Pyruvate kinase, which catalyzes the last but rate-limiting step of glycolysis, is expressed in four isozymic forms, depending on the tissue requirement. M2 isoform (PKM2) is exclusively expressed in embryonic and adult dividing/tumor cells. This tetrameric allosterically regulated isoform is intrinsically designed to downregulate its activity by subunit dissociation (into dimer), which results in partial inhibition of glycolysis at the last step. This accumulates all upstream glycolytic intermediates as an anabolic feed for synthesis of lipids and nucleic acids, whereas reassociation of PKM2 into active tetramer replenishes the normal catabolism as a feedback after cell division. In addition, involvement of this enzyme in a variety of pathways, protein-protein interactions, and nuclear transport suggests its potential to perform multiple nonglycolytic functions with diverse implications, although multidimensional role of this protein is as yet not fully explored. This review aims to provide an overview of the involvement of PKM2 in various physiological pathways with possible functional implications. PMID:20857498

  3. Hydrogen peroxide activates activator protein-1 and mitogen-activated protein kinases in pancreatic stellate cells.

    PubMed

    Kikuta, Kazuhiro; Masamune, Atsushi; Satoh, Masahiro; Suzuki, Noriaki; Satoh, Kennichi; Shimosegawa, Tooru

    2006-10-01

    Activated pancreatic stellate cells (PSCs) are implicated in the pathogenesis of pancreatic inflammation and fibrosis, where oxidative stress is thought to play a key role. Reactive oxygen species such as hydrogen peroxide (H(2)O(2)) may act as a second messenger to mediate the actions of growth factors and cytokines. But the role of reactive oxygen species in the activation and regulation of cell functions in PSCs remains largely unknown. We here examined the effects of H(2)O(2) on the activation of signal transduction pathways and cell functions in PSCs. PSCs were isolated from the pancreas of male Wistar rats, and used in their culture-activated, myofibroblast-like phenotype unless otherwise stated. Activation of transcription factors was examined by electrophoretic mobility shift assay and luciferase assay. Activation of mitogen-activated protein (MAP) kinases was assessed by Western blotting using anti-phosphospecific antibodies. The effects of H(2)O(2) on proliferation, alpha(1)(I)procollagen gene expression, and monocyte chemoattractant protein-1 production were evaluated. The effect of H(2)O(2) on the transformation of freshly isolated PSCs in culture was also assessed. H(2)O(2) at non-cytotoxic concentrations (up to 100 microM) induced oxidative stress in PSCs. H(2)O(2) activated activator protein-1, but not nuclear factor kappaB. In addition, H(2)O(2) activated three classes of MAP kinases: extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38 MAP kinase. H(2)O(2) induced alpha(1)(I)procollagen gene expression but did not induce proliferation or monocyte chemoattractant protein-1 production. H(2)O(2) did not initiate the transformation of freshly isolated PSCs to myofibroblast-like phenotype. Specific activation of these signal transduction pathways and collagen gene expression by H(2)O(2) may play a role in the pathogenesis of pancreatic fibrosis.

  4. Modulation of neurosteroid potentiation by protein kinases at synaptic- and extrasynaptic-type GABAA receptors

    PubMed Central

    Adams, Joanna M.; Thomas, Philip; Smart, Trevor G.

    2015-01-01

    GABAA receptors are important for inhibition in the CNS where neurosteroids and protein kinases are potent endogenous modulators. Acting individually, these can either enhance or depress receptor function, dependent upon the type of neurosteroid or kinase and the receptor subunit combination. However, in vivo, these modulators probably act in concert to fine-tune GABAA receptor activity and thus inhibition, although how this is achieved remains unclear. Therefore, we investigated the relationship between these modulators at synaptic-type α1β3γ2L and extrasynaptic-type α4β3δ GABAA receptors using electrophysiology. For α1β3γ2L, potentiation of GABA responses by tetrahydro-deoxycorticosterone was reduced after inhibiting protein kinase C, and enhanced following its activation, suggesting this kinase regulates neurosteroid modulation. In comparison, neurosteroid potentiation was reduced at α1β3S408A,S409Aγ2L receptors, and unaltered by PKC inhibitors or activators, indicating that phosphorylation of β3 subunits is important for regulating neurosteroid activity. To determine whether extrasynaptic-type GABAA receptors were similarly modulated, α4β3δ and α4β3S408A,S409Aδ receptors were investigated. Neurosteroid potentiation was reduced at both receptors by the kinase inhibitor staurosporine. By contrast, neurosteroid-mediated potentiation at α4S443Aβ3S408A,S409Aδ receptors was unaffected by protein kinase inhibition, strongly suggesting that phosphorylation of α4 and β3 subunits is required for regulating neurosteroid activity at extrasynaptic receptors. Western blot analyses revealed that neurosteroids increased phosphorylation of β3S408,S409 implying that a reciprocal pathway exists for neurosteroids to modulate phosphorylation of GABAA receptors. Overall, these findings provide important insight into the regulation of GABAA receptors in vivo, and into the mechanisms by which GABAergic inhibitory transmission may be simultaneously tuned by

  5. Characterization of the fission yeast mcs2 cyclin and its associated protein kinase activity.

    PubMed Central

    Molz, L; Beach, D

    1993-01-01

    We have previously described the isolation of mcs2-75, a mutation obtained as an allele-specific suppressor of a dominant allele of cdc2. mcs2 was cloned and determined to be an essential gene, the product of which shares homology with the cyclin family of proteins. In contrast to the behavior of some, but not all cyclins, the mcs2 protein is constant in its abundance and localization throughout the cell cycle. A kinase activity that co-precipitates with mcs2 can be detected when myelin basic protein (MBP) is provided as an exogenous substrate. This kinase activity is constant throughout the cell cycle. mcs2 does not appear to associate with the cdc2 protein kinase or an antigenically related kinase. Finally, a protein kinase termed csk1 (cyclin suppressing kinase) was isolated as a high copy suppressor of an mcs2 mutation. csk1 is not essential, however, the level of kinase activity that co-precipitates with mcs2 is reduced approximately 3-fold in strains harboring a csk1 null allele. Therefore, csk1 may encode a protein kinase physically associated with mcs2 or alternatively may function as an upstream activator of the mcs2-associated kinase. Images PMID:8467814

  6. Disruption of the serine/threonine protein kinase H affects phthiocerol dimycocerosates synthesis in Mycobacterium tuberculosis

    PubMed Central

    Gómez-Velasco, Anaximandro; Bach, Horacio; Rana, Amrita K.; Cox, Liam R.; Bhatt, Apoorva; Besra, Gurdyal S.

    2013-01-01

    Mycobacterium tuberculosis possesses a complex cell wall that is unique and essential for interaction of the pathogen with its human host. Emerging evidence suggests that the biosynthesis of complex cell-wall lipids is mediated by serine/threonine protein kinases (STPKs). Herein, we show, using in vivo radiolabelling, MS and immunostaining analyses, that targeted deletion of one of the STPKs, pknH, attenuates the production of phthiocerol dimycocerosates (PDIMs), a major M. tuberculosis virulence lipid. Comparative protein expression analysis revealed that proteins in the PDIM biosynthetic pathway are differentially expressed in a deleted pknH strain. Furthermore, we analysed the composition of the major lipoglycans, lipoarabinomannan (LAM) and lipomannan (LM), and found a twofold higher LAM/LM ratio in the mutant strain. Thus, we provide experimental evidence that PknH contributes to the production and synthesis of M. tuberculosis cell-wall components. PMID:23412844

  7. Insect freeze tolerance: Roles of protein phosphatases and protein kinase A.

    PubMed

    Pfister, Thomas D; Storey, Kenneth B

    2006-01-01

    Freeze-tolerant larvae of the goldenrod gall fly, Eurosta solidaginis Fitch, show multiple metabolic adaptations for subzero survival including the autumn synthesis of high concentrations of polyols. The induction and regulation of cold hardiness adaptations requires the intermediary action of signal transduction enzymes. The present study evaluates changes in the activities of cAMP-dependent protein kinase (PKA), protein phosphatases 1 (PP1), 2A, 2C, and protein tyrosine phosphatases (PTPs) over the course of the winter season and also in insects exposed to -4, -20 degrees C, or anoxic conditions in the laboratory. The increased PKA and decreased PP1 over the winter season and/or at subzero temperature support a regulatory role for these enzymes in cryoprotectant polyol synthesis. PTP activities were also strongly increased under these conditions and may act to antagonize tyrosine kinase mediated cell growth and proliferation responses and, thereby, contribute to hypometabolism and diapause over the winter.

  8. Dataset of integrin-linked kinase protein: Protein interactions in cardiomyocytes identified by mass spectrometry.

    PubMed

    Traister, Alexandra; Lu, Mingliang; Coles, John G; Maynes, Jason T

    2016-06-01

    Using hearts from mice overexpressing integrin linked kinase (ILK) behind the cardiac specific promoter αMHC, we have performed immunoprecipitation and mass spectrometry to identify novel ILK protein:protein interactions that regulate cardiomyocyte activity and calcium flux. Integrin linked kinase complexes were captured from mouse heart lysates using a commercial antibody, with subsequent liquid chromatography tandem mass spectral analysis. Interacting partners were identified using the MASCOT server, and important interactions verified using reverse immunoprecipitation and mass spectrometry. All ILK interacting proteins were identified in a non-biased manner, and are stored in the ProteomeXchange Consortium via the PRIDE partner repository (reference ID PRIDE: PXD001053). The functional role of identified ILK interactions in cardiomyocyte function and arrhythmia were subsequently confirmed in human iPSC-cardiomyocytes. PMID:27408918

  9. Phosphorylation and inhibition of. gamma. -glutamyl transferase activity by cAMP-dependent protein kinase

    SciTech Connect

    Kolesnichenko, L.S.; Chernov, N.N.

    1986-10-20

    It was shown that preparations of bovine kidney ..gamma..-glutamyl transferase of differing degrees of purity are phosphorylated by cAMP-dependent protein kinase. This is accompanied by a decrease in both the transferase and hydrolase activities of the enzyme. Consequently, ..gamma..-glutamyl transferase may serve as the substrate and target of the regulation of cAMP-dependent protein kinase.

  10. Steroidogenic Acute Regulatory Protein Overexpression Correlates with Protein Kinase A Activation in Adrenocortical Adenoma

    PubMed Central

    Xie, Jing; Su, Tingwei; Jiang, Lei; Jiang, Yiran; Cao, Yanan; Liu, Jianmin; Ning, Guang; Wang, Weiqing

    2016-01-01

    The association of pathological features of cortisol-producing adrenocortical adenomas (ACAs) with somatic driver mutations and their molecular classification remain unclear. In this study, we explored the association between steroidogenic acute regulatory protein (StAR) expression and the driver mutations activating cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) signaling to identify the pathological markers of ACAs. Immunohistochemical staining for StAR and mutations in the protein kinase cAMP-activated catalytic subunit alpha (PRKACA), protein kinase cAMP-dependent type I regulatory subunit alpha (PRKAR1A) and guanine nucleotide binding protein, alpha stimulating (GNAS) genes were examined in 97 ACAs. The association of StAR expression with the clinical and mutational features of the ACAs was analyzed. ACAs with mutations in PRKACA, GNAS, and PRKAR1A showed strong immunopositive staining for StAR. The concordance between high StAR expression and mutations activating cAMP/PKA signaling in the ACAs was 99.0%. ACAs with high expression of StAR had significantly smaller tumor volume (P < 0.001) and higher urinary cortisol per tumor volume (P = 0.032) than those with low expression of StAR. Our findings suggest that immunohistochemical staining for StAR is a reliable pathological approach for the diagnosis and classification of ACAs with cAMP/PKA signaling-activating mutations. PMID:27606678

  11. Steroidogenic Acute Regulatory Protein Overexpression Correlates with Protein Kinase A Activation in Adrenocortical Adenoma.

    PubMed

    Zhou, Weiwei; Wu, Luming; Xie, Jing; Su, Tingwei; Jiang, Lei; Jiang, Yiran; Cao, Yanan; Liu, Jianmin; Ning, Guang; Wang, Weiqing

    2016-01-01

    The association of pathological features of cortisol-producing adrenocortical adenomas (ACAs) with somatic driver mutations and their molecular classification remain unclear. In this study, we explored the association between steroidogenic acute regulatory protein (StAR) expression and the driver mutations activating cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) signaling to identify the pathological markers of ACAs. Immunohistochemical staining for StAR and mutations in the protein kinase cAMP-activated catalytic subunit alpha (PRKACA), protein kinase cAMP-dependent type I regulatory subunit alpha (PRKAR1A) and guanine nucleotide binding protein, alpha stimulating (GNAS) genes were examined in 97 ACAs. The association of StAR expression with the clinical and mutational features of the ACAs was analyzed. ACAs with mutations in PRKACA, GNAS, and PRKAR1A showed strong immunopositive staining for StAR. The concordance between high StAR expression and mutations activating cAMP/PKA signaling in the ACAs was 99.0%. ACAs with high expression of StAR had significantly smaller tumor volume (P < 0.001) and higher urinary cortisol per tumor volume (P = 0.032) than those with low expression of StAR. Our findings suggest that immunohistochemical staining for StAR is a reliable pathological approach for the diagnosis and classification of ACAs with cAMP/PKA signaling-activating mutations.

  12. Steroidogenic Acute Regulatory Protein Overexpression Correlates with Protein Kinase A Activation in Adrenocortical Adenoma.

    PubMed

    Zhou, Weiwei; Wu, Luming; Xie, Jing; Su, Tingwei; Jiang, Lei; Jiang, Yiran; Cao, Yanan; Liu, Jianmin; Ning, Guang; Wang, Weiqing

    2016-01-01

    The association of pathological features of cortisol-producing adrenocortical adenomas (ACAs) with somatic driver mutations and their molecular classification remain unclear. In this study, we explored the association between steroidogenic acute regulatory protein (StAR) expression and the driver mutations activating cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) signaling to identify the pathological markers of ACAs. Immunohistochemical staining for StAR and mutations in the protein kinase cAMP-activated catalytic subunit alpha (PRKACA), protein kinase cAMP-dependent type I regulatory subunit alpha (PRKAR1A) and guanine nucleotide binding protein, alpha stimulating (GNAS) genes were examined in 97 ACAs. The association of StAR expression with the clinical and mutational features of the ACAs was analyzed. ACAs with mutations in PRKACA, GNAS, and PRKAR1A showed strong immunopositive staining for StAR. The concordance between high StAR expression and mutations activating cAMP/PKA signaling in the ACAs was 99.0%. ACAs with high expression of StAR had significantly smaller tumor volume (P < 0.001) and higher urinary cortisol per tumor volume (P = 0.032) than those with low expression of StAR. Our findings suggest that immunohistochemical staining for StAR is a reliable pathological approach for the diagnosis and classification of ACAs with cAMP/PKA signaling-activating mutations. PMID:27606678

  13. Targeting protein–protein interactions in complexes organized by A kinase anchoring proteins

    PubMed Central

    Calejo, Ana I.; Taskén, Kjetil

    2015-01-01

    Cyclic AMP is a ubiquitous intracellular second messenger involved in the regulation of a wide variety of cellular processes, a majority of which act through the cAMP – protein kinase A (PKA) signaling pathway and involve PKA phosphorylation of specific substrates. PKA phosphorylation events are typically spatially restricted and temporally well controlled. A-kinase anchoring proteins (AKAPs) directly bind PKA and recruit it to specific subcellular loci targeting the kinase activity toward particular substrates, and thereby provide discrete spatiotemporal control of downstream phosphorylation events. AKAPs also scaffold other signaling molecules into multi-protein complexes that function as crossroads between different signaling pathways. Targeting AKAP coordinated protein complexes with high-affinity peptidomimetics or small molecules to tease apart distinct protein–protein interactions (PPIs) therefore offers important means to disrupt binding of specific components of the complex to better understand the molecular mechanisms involved in the function of individual signalosomes and their pathophysiological role. Furthermore, development of novel classes of small molecules involved in displacement of AKAP-bound signal molecules is now emerging. Here, we will focus on mechanisms for targeting PPI, disruptors that modulate downstream cAMP signaling and their role, especially in the heart. PMID:26441649

  14. Molecular characterization of recombinant mouse adenosine kinase and evaluation as a target for protein phosphorylation.

    PubMed

    Sahin, Bogachan; Kansy, Janice W; Nairn, Angus C; Spychala, Jozef; Ealick, Steven E; Fienberg, Allen A; Greene, Robert W; Bibb, James A

    2004-09-01

    The regulation of adenosine kinase (AK) activity has the potential to control intracellular and interstitial adenosine (Ado) concentrations. In an effort to study the role of AK in Ado homeostasis in the central nervous system, two isoforms of the enzyme were cloned from a mouse brain cDNA library. Following overexpression in bacterial cells, the corresponding proteins were purified to homogeneity. Both isoforms were enzymatically active and found to possess K(m) and V(max) values in agreement with kinetic parameters described for other forms of AK. The distribution of AK in discrete brain regions and various peripheral tissues was defined. To investigate the possibility that AK activity is regulated by protein phosphorylation, a panel of protein kinases was screened for ability to phosphorylate recombinant mouse AK. Data from these in vitro phosphorylation studies suggest that AK is most likely not an efficient substrate for PKA, PKG, CaMKII, CK1, CK2, MAPK, Cdk1, or Cdk5. PKC was found to phosphorylate recombinant AK efficiently in vitro. Further analysis revealed, however, that this PKC-dependent phosphorylation occurred at one or more serine residues associated with the N-terminal affinity tag used for protein purification.

  15. Pharmacological modulation of protein kinases as a new approach to treat addiction to cocaine and opiates.

    PubMed

    García-Pardo, María Pilar; Roger-Sanchez, Concepción; Rodríguez-Arias, Marta; Miñarro, Jose; Aguilar, María Asunción

    2016-06-15

    Drug addiction shares brain mechanisms and molecular substrates with learning and memory processes, such as the stimulation of glutamate receptors and their downstream signalling pathways. In the present work we provide an up-to-date review of studies that have demonstrated the implication of the main memory-related calcium-dependent protein kinases in opiate and cocaine addiction. The effects of these drugs of abuse in different animal models of drug reward, dependence and addiction are altered by manipulation of the mitogen-activated protein kinase (MAPK) family, particularly extracellular signal regulated kinase (ERK), calcium/calmodulin-dependent kinase II (CaMKII), the protein kinase C (PKC) family (including PKMζ), cAMP-dependent protein kinase A (PKA), cGMP-dependent protein kinase G (PKG), the phosphatidylinositol 3-kinase (PI3K) pathway and its downstream target mammalian target of Rapamycin (mTOR), cyclin-dependent kinase 5 (Cdk5), heat-shock proteins (Hsp) and other enzymes and proteins. Research suggests that drugs of abuse induce dependence and addiction by modifying the signalling pathways that involve these memory-related protein kinases, and supports the idea that drug addiction is an excessive aberrant learning disorder in which the maladaptive memory of drug-associated cues maintains compulsive drug use and contributes to relapse. Moreover, the studies we review offer new pharmacological strategies to treat opiate and cocaine dependence based on the manipulation of these protein kinases. In particular, disruption of reconsolidation of drug-related memories may have a high therapeutic value in the treatment of drug addiction. PMID:27056740

  16. Pharmacological modulation of protein kinases as a new approach to treat addiction to cocaine and opiates.

    PubMed

    García-Pardo, María Pilar; Roger-Sanchez, Concepción; Rodríguez-Arias, Marta; Miñarro, Jose; Aguilar, María Asunción

    2016-06-15

    Drug addiction shares brain mechanisms and molecular substrates with learning and memory processes, such as the stimulation of glutamate receptors and their downstream signalling pathways. In the present work we provide an up-to-date review of studies that have demonstrated the implication of the main memory-related calcium-dependent protein kinases in opiate and cocaine addiction. The effects of these drugs of abuse in different animal models of drug reward, dependence and addiction are altered by manipulation of the mitogen-activated protein kinase (MAPK) family, particularly extracellular signal regulated kinase (ERK), calcium/calmodulin-dependent kinase II (CaMKII), the protein kinase C (PKC) family (including PKMζ), cAMP-dependent protein kinase A (PKA), cGMP-dependent protein kinase G (PKG), the phosphatidylinositol 3-kinase (PI3K) pathway and its downstream target mammalian target of Rapamycin (mTOR), cyclin-dependent kinase 5 (Cdk5), heat-shock proteins (Hsp) and other enzymes and proteins. Research suggests that drugs of abuse induce dependence and addiction by modifying the signalling pathways that involve these memory-related protein kinases, and supports the idea that drug addiction is an excessive aberrant learning disorder in which the maladaptive memory of drug-associated cues maintains compulsive drug use and contributes to relapse. Moreover, the studies we review offer new pharmacological strategies to treat opiate and cocaine dependence based on the manipulation of these protein kinases. In particular, disruption of reconsolidation of drug-related memories may have a high therapeutic value in the treatment of drug addiction.

  17. Yeast spindle pole body duplication gene MPS1 encodes an essential dual specificity protein kinase.

    PubMed Central

    Lauzé, E; Stoelcker, B; Luca, F C; Weiss, E; Schutz, A R; Winey, M

    1995-01-01

    The MPS1 gene has been previously identified by a mutant allele that shows defects in spindle pole body (SPB) duplication and cell cycle control. The SPB is the centrosome-equivalent organelle in the yeast Saccharomyces cerevisiae, and it nucleates all the microtubules in the cell. We report the isolation of the MPS1 gene, which encodes an essential protein kinase homolog. The MPS1 open reading frame has been fused to those that encode the LexA protein or the GST protein and both of these constructs function in yeast. The fusion proteins have been affinity-purified from yeast extracts and the GST chimeric protein has been found to be a phosphoprotein. Both proteins have been used to demonstrate intrinsic in vitro protein kinase activity of Mps1p against exogenous substrates and itself (autophosphorylation). A mutation predicted to abolish kinase function not only eliminates in vitro protein kinase activity, but also behaves like a null mutation in vivo, suggesting that kinase activity contributes to the essential function of the protein. Phosphoamino acid analysis of substrates phosphorylated by Mps1p indicates that this kinase can phosphorylate serine, threonine and tyrosine residues, identifying Mps1p as a dual specificity protein kinase. Images PMID:7737118

  18. Neurochondrin is an atypical RIIα-specific A-kinase anchoring protein.

    PubMed

    Hermann, Jennifer S; Skroblin, Philipp; Bertinetti, Daniela; Hanold, Laura E; von der Heide, Eva K; Wagener, Eva-Maria; Zenn, Hans-Michael; Klussmann, Enno; Kennedy, Eileen J; Herberg, Friedrich W

    2015-10-01

    Protein kinase activity is regulated not only by direct strategies affecting activity but also by spatial and temporal regulatory mechanisms. Kinase signaling pathways are coordinated by scaffolding proteins that orchestrate the assembly of multi-protein complexes. One family of such scaffolding proteins are the A-kinase anchoring proteins (AKAPs). AKAPs share the commonality of binding cAMP-dependent protein kinase (PKA). In addition, they bind further signaling proteins and kinase substrates and tether such multi-protein complexes to subcellular locations. The A-kinase binding (AKB) domain of AKAPs typically contains a conserved helical motif that interacts directly with the dimerization/docking (D/D) domain of the regulatory subunits of PKA. Based on a pull-down proteomics approach, we identified neurochondrin (neurite-outgrowth promoting protein) as a previously unidentified AKAP. Here, we show that neurochondrin interacts directly with PKA through a novel mechanism that involves two distinct binding regions. In addition, we demonstrate that neurochondrin has strong isoform selectivity towards the RIIα subunit of PKA with nanomolar affinity. This article is part of a Special Issue entitled: Inhibitors of Protein Kinases.

  19. Structure-function analysis of a bacterial deoxyadenosine kinase reveals the basis for substrate specificity.

    PubMed

    Welin, Martin; Wang, Liya; Eriksson, Staffan; Eklund, Hans

    2007-03-01

    Deoxyribonucleoside kinases (dNKs) catalyze the transfer of a phosphoryl group from ATP to a deoxyribonucleoside (dN), a key step in DNA precursor synthesis. Recently structural information concerning dNKs has been obtained, but no structure of a bacterial dCK/dGK enzyme is known. Here we report the structure of such an enzyme, represented by deoxyadenosine kinase from Mycoplasma mycoides subsp. mycoides small colony type (Mm-dAK). Superposition of Mm-dAK with its human counterpart's deoxyguanosine kinase (dGK) and deoxycytidine kinase (dCK) reveals that the overall structures are very similar with a few amino acid alterations in the proximity of the active site. To investigate the substrate specificity, Mm-dAK has been crystallized in complex with dATP and dCTP, as well as the products dCMP and dCDP. Both dATP and dCTP bind to the enzyme in a feedback-inhibitory manner with the dN part in the deoxyribonucleoside binding site and the triphosphates in the P-loop. Substrate specificity studies with clinically important nucleoside analogs as well as several phosphate donors were performed. Thus, in this study we combine structural and kinetic data to gain a better understanding of the substrate specificity of the dCK/dGK family of enzymes. The structure of Mm-dAK provides a starting point for making new anti bacterial agents against pathogenic bacteria.

  20. Rapid Identification of Protein Kinase Phosphorylation Site Motifs Using Combinatorial Peptide Libraries.

    PubMed

    Miller, Chad J; Turk, Benjamin E

    2016-01-01

    Eukaryotic protein kinases phosphorylate substrates at serine, threonine, and tyrosine residues that fall within the context of short sequence motifs. Knowing the phosphorylation site motif for a protein kinase facilitates designing substrates for kinase assays and mapping phosphorylation sites in protein substrates. Here, we describe an arrayed peptide library protocol for rapidly determining kinase phosphorylation consensus sequences. This method uses a set of peptide mixtures in which each of the 20 amino acid residues is systematically substituted at nine positions surrounding a central site of phosphorylation. Peptide mixtures are arrayed in multiwell plates and analyzed by radiolabel assay with the kinase of interest. The preferred sequence is determined from the relative rate of phosphorylation of each peptide in the array. Consensus peptides based on these sequences typically serve as efficient and specific kinase substrates for high-throughput screening or incorporation into biosensors.

  1. Breast tumor kinase (protein tyrosine kinase 6) regulates heregulin-induced activation of ERK5 and p38 MAP kinases in breast cancer cells.

    PubMed

    Ostrander, Julie Hanson; Daniel, Andrea R; Lofgren, Kristopher; Kleer, Celina G; Lange, Carol A

    2007-05-01

    Total tyrosine kinase activity is often elevated in both cytosolic and membrane fractions of malignant breast tissue and correlates with a decrease in disease-free survival. Breast tumor kinase (Brk; protein tyrosine kinase 6) is a soluble tyrosine kinase that was cloned from a metastatic breast tumor and found to be overexpressed in a majority of breast tumors. Herein, we show that Brk is overexpressed in 86% of invasive ductal breast tumors and coexpressed with ErbB family members in breast cancer cell lines. Additionally, the ErbB ligand, heregulin, activates Brk kinase activity. Knockdown of Brk by stable expression of short hairpin RNA (shRNA) in T47D breast cancer cells decreases proliferation and blocks epidermal growth factor (EGF)- and heregulin-induced activation of Rac GTPase, extracellular signal-regulated kinase (ERK) 5, and p38 mitogen-activated protein kinase (MAPK) but not Akt, ERK1/2, or c-Jun NH(2)-terminal kinase. Furthermore, EGF- and heregulin-induced cyclin D1 expression is dependent on p38 signaling and inhibited by Brk shRNA knockdown. The myocyte enhancer factor 2 transcription factor target of p38 MAPK and ERK5 signaling is also sensitive to altered Brk expression. Finally, heregulin-induced migration of T47D cells requires p38 MAPK activity and is blocked by Brk knockdown. These results place Brk in a novel signaling pathway downstream of ErbB receptors and upstream of Rac, p38 MAPK, and ERK5 and establish the ErbB-Brk-Rac-p38 MAPK pathway as a critical mediator of breast cancer cell migration.

  2. [Effects of phosphatidylinositol-3 kinase/protein kinase b/bone morphogenetic protein-15 pathway on the follicular development in the mammalian ovary].

    PubMed

    Wu, Yan-qing; Chen, Li-yun; Zhang, Zheng-hong; wang, Zheng-chao

    2013-04-01

    In mammals, ovarian follicle is made of an oocyte with its surrounding granulosa cells and theca cells. Follicular growth and development is a highly coordinated programmable process, which guarantees the normal oocyte maturation and makes it having the fertilizing capacity. The paracrine and autocrine between oocytes and granulosa cells are essential for the follicular development to provide a suitable microenvironment. Phosphatidylinositol-3 kinase /protein kinase B is one of these important regulatory signaling pathways during this developmental process, and bone morphogenetic protein-15 an oocyte-specific secreted signal molecule, which regulates the follicular development by paracrine in the mammalian ovary. The present article overviewed the role of phosphatidylinositol-3 kinase / protein kinase B signaling during the follicular development based on our previous investigation about protein kinase B /forkhead transcription factor forkhead family of transcription factors -3a, and then focused on the regulatory effects of bone morphogenetic protein-15, as a downstream signal molecule of phosphatidylinositol-3 kinase / forkhead family of transcription factors -3a pathway, on ovarian follicular development, which helped to further understand the molecular mechanism regulating the follicular development and to treat ovarian diseases like infertility.

  3. Protein kinase–inhibitor database: Structural variability of and inhibitor interactions with the protein kinase P-loop

    PubMed Central

    Patel, Ronak Y.; Doerksen, Robert J.

    2011-01-01

    Structure based drug design of protein-kinase inhibitors has been facilitated by availability of an enormous number of structures in the Protein Databank (PDB), systematic analyses of which can provide insight into the factors which govern ligand–protein kinase interactions and into the conformational variability of the protein kinases. In this study, a non-redundant database containing 755 unique, curated and annotated PDB protein kinase–inhibitor complexes (each consisting of a single protein kinase chain, a ligand and water molecules around the ligand) was created. With this dataset, analyses were performed of protein conformational variability and interactions of ligands with 11 P-loop residues. Analysis of ligand–protein interactions included ligand atom preference, ligand–protein hydrogen bonds and the number and position of crystallographic water molecules around important P-loop residues. Analysis of variability in the conformation of the P-loop considered backbone and side-chain dihedral angles, and solvent accessible surface area (SASA). A distorted conformation of the P-loop was observed for some of the protein kinase structures. Lower SASA was observed for the hydrophobic residue in β1 of several members of the AGC family of protein kinases. Our systematic studies were performed amino-acid by amino-acid, which is unusual for analyses of protein kinase–inhibitor complexes. PMID:20681595

  4. Computational Modeling Reveals Optimal Strategy for Kinase Transport by Microtubules to Nerve Terminals

    PubMed Central

    Koon, Yen Ling; Koh, Cheng Gee; Chiam, Keng-Hwee

    2014-01-01

    Intracellular transport of proteins by motors along cytoskeletal filaments is crucial to the proper functioning of many eukaryotic cells. Since most proteins are synthesized at the cell body, mechanisms are required to deliver them to the growing periphery. In this article, we use computational modeling to study the strategies of protein transport in the context of JNK (c-JUN NH2-terminal kinase) transport along microtubules to the terminals of neuronal cells. One such strategy for protein transport is for the proteins of the JNK signaling cascade to bind to scaffolds, and to have the whole protein-scaffold cargo transported by kinesin motors along microtubules. We show how this strategy outperforms protein transport by diffusion alone, using metrics such as signaling rate and signal amplification. We find that there exists a range of scaffold concentrations for which JNK transport is optimal. Increase in scaffold concentration increases signaling rate and signal amplification but an excess of scaffolds results in the dilution of reactants. Similarly, there exists a range of kinesin motor speeds for which JNK transport is optimal. Signaling rate and signal amplification increases with kinesin motor speed until the speed of motor translocation becomes faster than kinase/scaffold-motor binding. Finally, we suggest experiments that can be performed to validate whether, in physiological conditions, neuronal cells do indeed adopt such an optimal strategy. Understanding cytoskeletal-assisted protein transport is crucial since axonal and cell body accumulation of organelles and proteins is a histological feature in many human neurodegenerative diseases. In this paper, we have shown that axonal transport performance changes with altered transport component concentrations and transport speeds wherein these aspects can be modulated to improve axonal efficiency and prevent or slowdown axonal deterioration. PMID:24691408

  5. Quantitative proteomics reveals dynamic interaction of c-Jun N-terminal kinase (JNK) with RNA transport granule proteins splicing factor proline- and glutamine-rich (Sfpq) and non-POU domain-containing octamer-binding protein (Nono) during neuronal differentiation.

    PubMed

    Sury, Matthias D; McShane, Erik; Hernandez-Miranda, Luis Rodrigo; Birchmeier, Carmen; Selbach, Matthias

    2015-01-01

    The c-Jun N-terminal kinase (JNK) is an important mediator of physiological and pathophysiological processes in the central nervous system. Importantly, JNK not only is involved in neuronal cell death, but also plays a significant role in neuronal differentiation and regeneration. For example, nerve growth factor induces JNK-dependent neuronal differentiation in several model systems. The mechanism by which JNK mediates neuronal differentiation is not well understood. Here, we employed a proteomic strategy to better characterize the function of JNK during neuronal differentiation. We used SILAC-based quantitative proteomics to identify proteins that interact with JNK in PC12 cells in a nerve growth factor-dependent manner. Intriguingly, we found that JNK interacted with neuronal transport granule proteins such as Sfpq and Nono upon NGF treatment. We validated the specificity of these interactions by showing that they were disrupted by a specific peptide inhibitor that blocks the interaction of JNK with its substrates. Immunoprecipitation and Western blotting experiments confirmed the interaction of JNK1 with Sfpq/Nono and demonstrated that it was RNA dependent. Confocal microscopy indicated that JNK1 associated with neuronal granule proteins in the cytosol of PC12 cells, primary cortical neurons, and P19 neuronal cells. Finally, siRNA experiments confirmed that Sfpq was necessary for neurite outgrowth in PC12 cells and that it most likely acted in the same pathway as JNK. In summary, our data indicate that the interaction of JNK1 with transport granule proteins in the cytosol of differentiating neurons plays an important role during neuronal development.

  6. Protein engineering of protein kinase A catalytic subunits results in the acquisition of novel inhibitor sensitivity.

    PubMed

    Niswender, Colleen M; Ishihara, R Wesley; Judge, Luke M; Zhang, Chao; Shokat, Kevan M; McKnight, G Stanley

    2002-08-01

    Analysis of the role of specific protein kinases in signal transduction networks has relied heavily on ATP analog inhibitors. Currently used agents, however, often do not distinguish between kinase family members. Genetic approaches can also be used to inactivate a specific kinase, but these techniques do not afford the rapid kinetics possible with pharmacological inhibitors. To circumvent this problem, modification of the structure of a particular protein kinase can be performed to engineer a drug-target interaction of choice. We have used this method to create protein kinase A (PKA) catalytic subunits with modifications that confer sensitivity to novel ATP analog inhibitors. Mutation of methionine 120 to alanine or glycine in either the Calpha or Cbeta subunits of PKA induces sensitivity to a series of C-3 derivatized pyrazolo[3,4-d]pyrimidine-based inhibitors. Modification of threonine 183 enhances this inhibitor sensitivity. The IC(50) values in cell culture of the most broadly effective agent, 1-NM, ranged from 25 to 200 nm depending upon the combination of modified amino acids and were significantly higher than the potencies observed with H-89. Despite their high sequence conservation, Cbeta enzymes with inhibitor-sensitive amino acids at position 120 showed a substantial loss of overall catalytic activity when used to induce reporter gene transcription in transfected cells. Conversion of position 46 (lysine to isoleucine) rescued the ability of position 120 mutated Cbeta enzymes to induce gene transcription. Application of this combined genetic and pharmacological approach should allow analysis of the specific roles of PKA isoforms in cell culture and in vivo. PMID:12034735

  7. Ca2+/Calmodulin-Dependent Protein Kinase Kinases (CaMKKs) Effects on AMP-Activated Protein Kinase (AMPK) Regulation of Chicken Sperm Functions

    PubMed Central

    Nguyen, Thi Mong Diep; Combarnous, Yves; Praud, Christophe; Duittoz, Anne; Blesbois, Elisabeth

    2016-01-01

    Sperm require high levels of energy to ensure motility and acrosome reaction (AR) accomplishment. The AMP-activated protein kinase (AMPK) has been demonstrated to be strongly involved in the control of these properties. We address here the question of the potential role of calcium mobilization on AMPK activation and function in chicken sperm through the Ca2+/calmodulin-dependent protein kinase kinases (CaMKKs) mediated pathway. The presence of CaMKKs and their substrates CaMKI and CaMKIV was evaluated by western-blotting and indirect immunofluorescence. Sperm were incubated in presence or absence of extracellular Ca2+, or of CaMKKs inhibitor (STO-609). Phosphorylations of AMPK, CaMKI, and CaMKIV, as well as sperm functions were evaluated. We demonstrate the presence of both CaMKKs (α and β), CaMKI and CaMKIV in chicken sperm. CaMKKα and CaMKI were localized in the acrosome, the midpiece, and at much lower fluorescence in the flagellum, whereas CaMKKβ was mostly localized in the flagellum and much less in the midpiece and the acrosome. CaMKIV was only present in the flagellum. The presence of extracellular calcium induced an increase in kinases phosphorylation and sperm activity. STO-609 reduced AMPK phosphorylation in the presence of extracellular Ca2+ but not in its absence. STO-609 did not affect CaMKIV phosphorylation but decreased CaMKI phosphorylation and this inhibition was quicker in the presence of extracellular Ca2+ than in its absence. STO-609 efficiently inhibited sperm motility and AR, both in the presence and absence of extracellular Ca2+. Our results show for the first time the presence of CaMKKs (α and β) and one of its substrate, CaMKI in different subcellular compartments in germ cells, as well as the changes in the AMPK regulation pathway, sperm motility and AR related to Ca2+ entry in sperm through the Ca2+/CaM/CaMKKs/CaMKI pathway. The Ca2+/CaMKKs/AMPK pathway is activated only under conditions of extracellular Ca2+ entry in the cells

  8. Molecular characterization and analysis of a novel calcium-dependent protein kinase from Eimeria tenella.

    PubMed

    Han, H Y; Zhu, S H; Jiang, L L; Li, Y; Dong, H; Zhao, Q P; Kong, C L; Huang, B

    2013-05-01

    The calcium-dependent protein kinases (CDPKs) are unique enzymes found only in plants, green algae, ciliates and apicomplexan parasites. In this study, a novel CDPK gene of Eimeria tenella, designed EtCDPK3, was cloned using rapid amplification of cDNA ends (RACE) based on the expressed sequence tag (EST). The entire cDNA of EtCDPK3 contained 1637 nucleotides encoding 433 amino acids and the deduced EtCDPK3 protein had canonical characteristic domains identified in other CDPKs, including a well-conserved amino-terminal kinase domain and a carboxy-terminal calmodulin-like structure with 4 EF-hand motifs for calcium binding. The expression profiles of the EtCDPK3 gene in different development stages were investigated by real-time quantitative PCR. Messenger RNA levels from the EtCDPK3 gene were higher in sporozoites than in other stages (unsporulated oocysts, sporulated oocysts a