scholarly journals Phosphorylation Sites in Protein Kinases and Phosphatases Regulated by Formyl Peptide Receptor 2 Signaling

2020 ◽  
Vol 21 (11) ◽  
pp. 3818
Author(s):  
Maria Carmela Annunziata ◽  
Melania Parisi ◽  
Gabriella Esposito ◽  
Gabriella Fabbrocini ◽  
Rosario Ammendola ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinases ◽  
Protein Phosphatase ◽  
Intracellular Signaling ◽  
Molecular Mechanisms ◽  
Fine Tuning ◽  
Formyl Peptide Receptor ◽  
Signaling Cascades ◽  
Regulatory Subunit ◽  
Formyl Peptides

FPR1, FPR2, and FPR3 are members of Formyl Peptides Receptors (FPRs) family belonging to the GPCR superfamily. FPR2 is a low affinity receptor for formyl peptides and it is considered the most promiscuous member of this family. Intracellular signaling cascades triggered by FPRs include the activation of different protein kinases and phosphatase, as well as tyrosine kinase receptors transactivation. Protein kinases and phosphatases act coordinately and any impairment of their activation or regulation represents one of the most common causes of several human diseases. Several phospho-sites has been identified in protein kinases and phosphatases, whose role may be to expand the repertoire of molecular mechanisms of regulation or may be necessary for fine-tuning of switch properties. We previously performed a phospho-proteomic analysis in FPR2-stimulated cells that revealed, among other things, not yet identified phospho-sites on six protein kinases and one protein phosphatase. Herein, we discuss on the selective phosphorylation of Serine/Threonine-protein kinase N2, Serine/Threonine-protein kinase PRP4 homolog, Serine/Threonine-protein kinase MARK2, Serine/Threonine-protein kinase PAK4, Serine/Threonine-protein kinase 10, Dual specificity mitogen-activated protein kinase kinase 2, and Protein phosphatase 1 regulatory subunit 14A, triggered by FPR2 stimulation. We also describe the putative FPR2-dependent signaling cascades upstream to these specific phospho-sites.

scholarly journals Mediation of the Cardioprotective Effects of Mannitol Discovered, with Refutation of Common Protein Kinases

2021 ◽  
Vol 22 (22) ◽  
pp. 12471
Author(s):  
Carolin Torregroza ◽  
Chiara O. Glashoerster ◽  
Katharina Feige ◽  
Martin Stroethoff ◽  
Annika Raupach ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Infarct Size ◽  
Reperfusion Injury ◽  
Protein Kinases ◽  
Intracellular Signaling ◽  
Myocardial Protection ◽  
Signaling Cascades ◽  
Control Group ◽  
Receptor Subtypes ◽  
Cardioprotective Effects

The osmodiuretic agent Mannitol exerts cardioprotection against ischemia and reperfusion (I/R) injury when applied as a pre- and/or postconditioning stimulus. Previously, we demonstrated that these properties are mediated via the activation of mitochondrial ATP-sensitive potassium (mKATP) channels. However, considering Mannitol remains in the extracellular compartment, the question arises as to which receptor and intracellular signaling cascades are involved in myocardial protection by the osmodiuretic substance. Protein kinase B (Akt) and G (PKG), as part of the reperfusion injury salvage kinase (RISK) and/or endothelial nitric oxide (eNOS)/PKG pathway, are two well-investigated intracellular targets conferring myocardial protection upstream of mitochondrial potassium channels. Adenosine receptor subtypes have been shown to trigger different cardioprotective pathways, for example, the reperfusion injury. Further, Mannitol induces an increased activation of the adenosine 1 receptor (A1R) in renal cells conferring its nephroprotective properties. Therefore, we investigated whether (1) Akt and PKG are possible signaling targets involved in Mannitol-induced conditioning upstream of the mKATP channel and/or whether (2) cardioprotection by Mannitol is mediated via activation of the A1R. All experiments were performed on male Wistar rats in vitro employing the Langendorff isolated heart perfusion technique with infarct size determination as the primary endpoint. To unravel possible protein kinase activation, Mannitol was applied in combination with the Akt (MK2206) or PKG (KT5823) inhibitor. In further groups, an A1R blocker (DPCPX) was given with or without Mannitol. Preconditioning with Mannitol (Man) significantly reduced the infarct size compared to the control group. Co-administration of the A1R blocker DPXPC fully abolished myocardial protection of Mannitol. Interestingly and in contrast to the initial hypothesis, neither administration of the Akt nor the PKG blocker had any impact on the cardioprotective properties of Mannitol-induced preconditioning. These results are quite unexpected and show that the protein kinases Akt and PKG—as possible targets of known protective signaling cascades—are not involved in Mannitol-induced preconditioning. However, the cardioprotective effects of Mannitol are mediated via the A1R.

Invited Review: Regulation of myosin phosphorylation in smooth muscle

2001 ◽  
Vol 91 (1) ◽  
pp. 497-503 ◽  
Author(s):  
Gabriele Pfitzer
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase ◽  
Protein Kinases ◽  
Intracellular Signaling ◽  
Muscle Tone ◽  
Force Production ◽  
Regulatory Subunit ◽  
Regulatory Light Chains ◽  
Smooth Muscle Tone ◽  
Dependent Protein

Phosphorylation of the regulatory light chains of myosin II (rMLC) by the Ca2+/calmodulin-dependent myosin light-chain kinase (MLCK) and dephosphorylation by a type 1 phosphatase (MLCP), which is targeted to myosin by a regulatory subunit (MYPT1), are the predominant mechanisms of regulation of smooth muscle tone. The activities of both enzymes are modulated by several protein kinases. MLCK is inhibited by the Ca2+/calmodulin-dependent protein kinase II, whereas the activity of MLCP is increased by cGMP and perhaps also cAMP-dependent protein kinases. In either case, this results in a decrease in the Ca2+ sensitivity of rMLC phosphorylation and force production. The activity of MLCP is inhibited by Rho-associated kinase, one of the effectors of the monomeric GTPase Rho, and protein kinase C, leading to an increase in Ca2+sensitivity. Hence, smooth muscle tone appears to be regulated by a network of activating and inactivating intracellular signaling cascades.

scholarly journals Angiotensin II-Mediated Protein Kinase D Activation Stimulates Aldosterone and Cortisol Secretion in H295R Human Adrenocortical Cells

Endocrinology ◽  
2006 ◽  
Vol 147 (12) ◽  
pp. 6046-6055 ◽  
Author(s):  
Damian G. Romero ◽  
Bronwyn L. Welsh ◽  
Elise P. Gomez-Sanchez ◽  
Licy L. Yanes ◽  
Silvia Rilli ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Protein Kinase ◽  
Protein Kinases ◽  
Intracellular Signaling ◽  
Molecular Mechanisms ◽  
Protein Kinase D ◽  
Cell Physiology ◽  
Cortisol Secretion ◽  
Adrenal Cells ◽  
Constitutively Active

Protein kinases are important mediators in intracellular signaling. Angiotensin II is the most important modulator of adrenal zona glomerulosa cell physiology. Angiotensin II regulates steroidogenesis and proliferation among many other metabolic processes. H295R human adrenal cells are a widely used experimental model to study adrenal cell physiology and metabolism. We screened for protein kinase expression levels using the Kinetwork system in H295R cells after 3 h angiotensin II treatment. Protein kinase D (PKD) was the protein kinase that suffers the most dramatic changes. PKD is a member of a new class of serine/threonine protein kinases that is activated by phosphorylation. Our studies indicated that angiotensin II time- and dose-dependently increased PKD phosphorylation, which occurred within 2 min of angiotensin II treatment and at concentrations as low as 1 nm. PKD phosphorylation was also dose-dependently increased by the PKC activator phorbol 12-myristate 13-acetate. Angiotensin II-mediated PKD phosphorylation was blocked by several PKC inhibitors. Furthermore, PKCε translocation inhibitor peptide decreased angiotensin II-mediated PKD phosphorylation, and PKCε down-regulation by RNA interference also decreased PKD phosphorylation mediated by angiotensin II. Cotransfection of constitutively active PKD mutant constructs up-regulated aldosterone synthase and 11β-hydroxylase expression in reporter assays. Constitutively active PKD mutants increased aldosterone and cortisol secretion under angiotensin II stimulatory conditions. This study reveals that PKD is an intracellular signaling mediator of angiotensin II regulation of steroidogenesis in human adrenal cells. These data provide new insights into the molecular mechanisms involved in angiotensin II-induced physiological and pathophysiological events in adrenal cells.

scholarly journals Ca2+ Microdomains, Calcineurin and the Regulation of Gene Transcription

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 875
Author(s):  
Gerald Thiel ◽  
Tobias Schmidt ◽  
Oliver G. Rössler
Keyword(s):  
Transcription Factors ◽  
Protein Kinase ◽  
Protein Kinases ◽  
Gene Transcription ◽  
Intracellular Signaling ◽  
Second Messengers ◽  
Major Function ◽  
Surface Receptors ◽  
Dependent Protein

Ca2+ ions function as second messengers regulating many intracellular events, including neurotransmitter release, exocytosis, muscle contraction, metabolism and gene transcription. Cells of a multicellular organism express a variety of cell-surface receptors and channels that trigger an increase of the intracellular Ca2+ concentration upon stimulation. The elevated Ca2+ concentration is not uniformly distributed within the cytoplasm but is organized in subcellular microdomains with high and low concentrations of Ca2+ at different locations in the cell. Ca2+ ions are stored and released by intracellular organelles that change the concentration and distribution of Ca2+ ions. A major function of the rise in intracellular Ca2+ is the change of the genetic expression pattern of the cell via the activation of Ca2+-responsive transcription factors. It has been proposed that Ca2+-responsive transcription factors are differently affected by a rise in cytoplasmic versus nuclear Ca2+. Moreover, it has been suggested that the mode of entry determines whether an influx of Ca2+ leads to the stimulation of gene transcription. A rise in cytoplasmic Ca2+ induces an intracellular signaling cascade, involving the activation of the Ca2+/calmodulin-dependent protein phosphatase calcineurin and various protein kinases (protein kinase C, extracellular signal-regulated protein kinase, Ca2+/calmodulin-dependent protein kinases). In this review article, we discuss the concept of gene regulation via elevated Ca2+ concentration in the cytoplasm and the nucleus, the role of Ca2+ entry and the role of enzymes as signal transducers. We give particular emphasis to the regulation of gene transcription by calcineurin, linking protein dephosphorylation with Ca2+ signaling and gene expression.

scholarly journals The TOR Signal Transduction Cascade Controls Cellular Differentiation in Response to Nutrients

2001 ◽  
Vol 12 (12) ◽  
pp. 4103-4113 ◽  
Author(s):  
N. Shane Cutler ◽  
Xuewen Pan ◽  
Joseph Heitman ◽  
Maria E. Cardenas
Keyword(s):  
Signal Transduction ◽  
Protein Kinases ◽  
Protein Phosphatase ◽  
Nutrient Sensing ◽  
Yeast Cells ◽  
Regulatory Subunit ◽  
Growth Defect ◽  
Tor Pathway ◽  
Pseudohyphal Growth ◽  
Pseudohyphal Differentiation

Rapamycin binds and inhibits the Tor protein kinases, which function in a nutrient-sensing signal transduction pathway that has been conserved from the yeast Saccharomyces cerevisiaeto humans. In yeast cells, the Tor pathway has been implicated in regulating cellular responses to nutrients, including proliferation, translation, transcription, autophagy, and ribosome biogenesis. We report here that rapamycin inhibits pseudohyphal filamentous differentiation of S. cerevisiae in response to nitrogen limitation. Overexpression of Tap42, a protein phosphatase regulatory subunit, restored pseudohyphal growth in cells exposed to rapamycin. The tap42-11 mutation compromised pseudohyphal differentiation and rendered it resistant to rapamycin. Cells lacking the Tap42-regulated protein phosphatase Sit4 exhibited a pseudohyphal growth defect and were markedly hypersensitive to rapamycin. Mutations in other Tap42-regulated phosphatases had no effect on pseudohyphal differentiation. Our findings support a model in which pseudohyphal differentiation is controlled by a nutrient-sensing pathway involving the Tor protein kinases and the Tap42–Sit4 protein phosphatase. Activation of the MAP kinase or cAMP pathways, or mutation of the Sok2 repressor, restored filamentation in rapamycin treated cells, supporting models in which the Tor pathway acts in parallel with these known pathways. Filamentous differentiation of diverse fungi was also blocked by rapamycin, demonstrating that the Tor signaling cascade plays a conserved role in regulating filamentous differentiation in response to nutrients.

scholarly journals MEF2A Regulates the MEG3-DIO3 miRNA Mega Cluster-Targeted PP2A Signaling in Bovine Skeletal Myoblast Differentiation

2019 ◽  
Vol 20 (11) ◽  
pp. 2748 ◽  
Author(s):  
Yaning Wang ◽  
Chugang Mei ◽  
Xiaotong Su ◽  
Hongbao Wang ◽  
Wucai Yang ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Molecular Mechanisms ◽  
Regulatory Subunit ◽  
Myoblast Differentiation ◽  
Mirna Cluster ◽  
Skeletal Myoblast ◽  
Iodothyronine Deiodinase ◽  
Luciferase Activity Assay ◽  
Phosphatase 2A ◽  
Protein Phosphatase 2

Understanding the molecular mechanisms of skeletal myoblast differentiation is essential for studying muscle developmental biology. In our previous study, we reported that knockdown of myocyte enhancer factor 2A (MEF2A) inhibited myoblast differentiation. Here in this study, we further identified that MEF2A controlled this process through regulating the maternally expressed 3 (MEG3)—iodothyronine deiodinase 3 (DIO3) miRNA mega cluster and protein phosphatase 2A (PP2A) signaling. MEF2A was sufficient to induce MEG3 expression in bovine skeletal myoblasts. A subset of miRNAs in the MEG3-DIO3 miRNA cluster was predicted to target PP2A subunit genes. Consistent with these observations, MEF2A regulated PP2A signaling through its subunit gene protein phosphatase 2 regulatory subunit B, gamma (PPP2R2C) during bovine myoblast differentiation. MiR-758 and miR-543 in the MEG3-DIO3 miRNA cluster were down-regulated in MEF2A-depleted myocytes. Expression of miR-758 and miR-543 promoted myoblast differentiation and repressed PPP2R2C expression. Luciferase activity assay showed that PPP2R2C was post-transcriptionally targeted by miR-758 and miR-543. Taken together, these results reveal that the MEG3-DIO3 miRNAs function at downstream of MEF2A to modulate PP2A signaling in bovine myoblast differentiation.

scholarly journals The AGC Kinase SsAgc1 Regulates Sporisorium scitamineum Mating/Filamentation and Pathogenicity

mSphere ◽  
2019 ◽  
Vol 4 (3) ◽  
Author(s):  
Yixu Wang ◽  
Yi Zhen Deng ◽  
Guobing Cui ◽  
Chengwei Huang ◽  
Bin Zhang ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Signaling Pathway ◽  
Protein Kinases ◽  
Molecular Mechanisms ◽  
Economic Losses ◽  
Signal Molecules ◽  
Dependent Protein Kinase ◽  
Sporisorium Scitamineum ◽  
Fungal Mating ◽  
Dependent Protein

ABSTRACT Sporisorium scitamineum is the fungal pathogen causing severe sugarcane smut disease that leads to massive economic losses globally. S. scitamineum invades host cane by dikaryotic hyphae, formed after sexual mating of two haploid sporidia of opposite mating type. Therefore, mating/filamentation is critical for S. scitamineum pathogenicity, while its molecular mechanisms remain largely unknown. The AGC (cyclic AMP [cAMP]-dependent protein kinase 1 [protein kinase A {PKA}], cGMP-dependent protein kinase [PKG], and protein kinase C [PKC]) kinase family is a group of serine/threonine (Ser/Thr) protein kinases conserved among eukaryotic genomes, serving a variety of physiological functions, including cell growth, metabolism, differentiation, and cell death. In this study, we identified an AGC kinase, named SsAgc1 (for S. scitamineum Agc1), and characterized its function by reverse genetics. Our results showed that SsAgc1 is critical for S. scitamineum mating/filamentation and pathogenicity, and oxidative stress tolerance under some circumstances. Transcriptional profiling revealed that the SsAgc1 signaling pathway may control expression of the genes governing fungal mating/filamentation and tryptophan metabolism, especially for tryptophol production. We showed that tryptophan and tryptophol could at least partially restore ssagc1Δ mating/filamentation. Overall, our work revealed a signaling pathway mediated by AGC protein kinases to regulate fungal mating/filamentation, possibly through sensing and responding to tryptophol as signal molecules. IMPORTANCE The AGC signaling pathway represents a conserved distinct signaling pathway in regulation of fungal differentiation and virulence, while it has not been identified or characterized in the sugarcane smut fungus Sporisorium scitamineum. In this study, we identified a PAS domain-containing AGC kinase, SsAgc1, in S. scitamineum. Functional analysis revealed that SsAgc1 plays a regulatory role on the fungal dimorphic switch.

scholarly journals Role of Calcium and EPAC in Norepinephrine-Induced Ghrelin Secretion

Endocrinology ◽  
2014 ◽  
Vol 155 (1) ◽  
pp. 98-107 ◽  
Author(s):  
Bharath K. Mani ◽  
Jen-Chieh Chuang ◽  
Lilja Kjalarsdottir ◽  
Ichiro Sakata ◽  
Angela K. Walker ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Intracellular Signaling ◽  
Endocrine Cells ◽  
Molecular Mechanisms ◽  
Phosphodiesterase Inhibitor ◽  
Intracellular Signaling Pathways ◽  
Ghrelin Secretion ◽  
Kinase A

Ghrelin is an orexigenic hormone secreted principally from a distinct population of gastric endocrine cells. Molecular mechanisms regulating ghrelin secretion are mostly unknown. Recently, norepinephrine (NE) was shown to enhance ghrelin release by binding to β1-adrenergic receptors on ghrelin cells. Here, we use an immortalized stomach-derived ghrelin cell line to further characterize the intracellular signaling pathways involved in NE-induced ghrelin secretion, with a focus on the roles of Ca2+ and cAMP. Several voltage-gated Ca2+ channel (VGCC) family members were found by quantitative PCR to be expressed by ghrelin cells. Nifedipine, a selective L-type VGCC blocker, suppressed both basal and NE-stimulated ghrelin secretion. NE induced elevation of cytosolic Ca2+ levels both in the presence and absence of extracellular Ca2+. Ca2+-sensing synaptotagmins Syt7 and Syt9 were also highly expressed in ghrelin cell lines, suggesting that they too help mediate ghrelin secretion. Raising cAMP with the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine also stimulated ghrelin secretion, although such a cAMP-mediated effect likely does not involve protein kinase A, given the absence of a modulatory response to a highly selective protein kinase A inhibitor. However, pharmacological inhibition of another target of cAMP, exchange protein-activated by cAMP (EPAC), did attenuate both basal and NE-induced ghrelin secretion, whereas an EPAC agonist enhanced basal ghrelin secretion. We conclude that constitutive ghrelin secretion is primarily regulated by Ca2+ influx through L-type VGCCs and that NE stimulates ghrelin secretion predominantly through release of intracellular Ca2+. Furthermore, cAMP and its downstream activation of EPAC are required for the normal ghrelin secretory response to NE.

scholarly journals IQGAP1 binds AMPK and is required for maximum AMPK activation

2020 ◽  
pp. jbc.RA120.016193
Author(s):  
Andrew C. Hedman ◽  
Zhigang Li ◽  
Laëtitia Gorisse ◽  
Swetha Parvathaneni ◽  
Chase J. Morgan ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Intracellular Signaling ◽  
Energy Homeostasis ◽  
Molecular Mechanisms ◽  
Direct Interaction ◽  
Mitogen Activated Protein Kinase ◽  
Null Cell ◽  
Ampk Signaling ◽  
In Cells

AMP-activated protein kinase (AMPK) is a fundamental component of a protein kinase cascade that is an energy sensor. AMPK maintains energy homeostasis in the cell by promoting catabolic and inhibiting anabolic pathways. Activation of AMPK requires phosphorylation by the liver kinase B1 or by the Ca2+ /calmodulin-dependent protein kinase kinase 2 (CaMKK2). The scaffold protein IQGAP1 regulates intracellular signaling pathways, such as the mitogen-activated protein kinase and AKT signaling cascades. Recent work implicates the participation of IQGAP1 in metabolic function, but the molecular mechanisms underlying these effects are poorly understood. Here, using several approaches including binding analysis with fusion proteins, siRNA-mediated gene silencing, RT-PCR, and knockout mice, we investigated whether IQGAP1 modulates AMPK signaling. In vitro analysis reveals that IQGAP1 binds directly to the α1 subunit of AMPK. In addition, we observed a direct interaction between IQGAP1 and CaMKK2, which is mediated by the IQ domain of IQGAP1. Both CaMKK2 and AMPK associate with IQGAP1 in cells. The ability of metformin and increased intracellular free Ca2+ concentrations to activate AMPK is reduced in cells lacking IQGAP1. Importantly, Ca2+-stimulated AMPK phosphorylation was rescued by re-expression of IQGAP1 in IQGAP1-null cell lines. Comparison of the fasting response in wild-type and IQGAP1-null mice revealed that transcriptional regulation of the gluconeogenesis genes PCK1 and G6PC and the fatty acid synthesis genes FASN and ACC1 is impaired in IQGAP1-null mice. Our data disclose a previously unidentified functional interaction between IQGAP1 and AMPK and suggest that IQGAP1 modulates AMPK signaling.

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