scholarly journals Raf Kinase Inhibitory Protein Function Is Regulated via a Flexible Pocket and Novel Phosphorylation-Dependent Mechanism

2008 ◽  
Vol 29 (5) ◽  
pp. 1306-1320 ◽  
Author(s):  
Alexey E. Granovsky ◽  
Matthew C. Clark ◽  
Dan McElheny ◽  
Gary Heil ◽  
Jia Hong ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Protein Function ◽  
Binding Pocket ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Signaling Proteins ◽  
Inhibitory Protein ◽  
Raf Kinase ◽  
Raf Kinase Inhibitory Protein ◽  
Mitogen Activated Protein

ABSTRACT Raf kinase inhibitory protein (RKIP/PEBP1), a member of the phosphatidylethanolamine binding protein family that possesses a conserved ligand-binding pocket, negatively regulates the mammalian mitogen-activated protein kinase (MAPK) signaling cascade. Mutation of a conserved site (P74L) within the pocket leads to a loss or switch in the function of yeast or plant RKIP homologues. However, the mechanism by which the pocket influences RKIP function is unknown. Here we show that the pocket integrates two regulatory signals, phosphorylation and ligand binding, to control RKIP inhibition of Raf-1. RKIP association with Raf-1 is prevented by RKIP phosphorylation at S153. The P74L mutation increases kinase interaction and RKIP phosphorylation, enhancing Raf-1/MAPK signaling. Conversely, ligand binding to the RKIP pocket inhibits kinase interaction and RKIP phosphorylation by a noncompetitive mechanism. Additionally, ligand binding blocks RKIP association with Raf-1. Nuclear magnetic resonance studies reveal that the pocket is highly dynamic, rationalizing its capacity to interact with distinct partners and be involved in allosteric regulation. Our results show that RKIP uses a flexible pocket to integrate ligand binding- and phosphorylation-dependent interactions and to modulate the MAPK signaling pathway. This mechanism is an example of an emerging theme involving the regulation of signaling proteins and their interaction with effectors at the level of protein dynamics.

scholarly journals Characterization of the Raf Kinase Inhibitory Protein (RKIP) Binding Pocket: NMR-Based Screening Identifies Small-Molecule Ligands

PLoS ONE ◽  
2010 ◽  
Vol 5 (5) ◽  
pp. e10479 ◽  
Author(s):  
Anne N. Shemon ◽  
Gary L. Heil ◽  
Alexey E. Granovsky ◽  
Mathew M. Clark ◽  
Dan McElheny ◽  
...  
Keyword(s):  
Small Molecule ◽  
Binding Pocket ◽  
Inhibitory Protein ◽  
Raf Kinase ◽  
Raf Kinase Inhibitory Protein ◽  
Small Molecule Ligands

scholarly journals Crystal structure reveals the full Ras:Raf interface and advances mechanistic understanding of Raf activation

2020 ◽  
Author(s):  
Trinity Cookis ◽  
Carla Mattos
Keyword(s):  
Crystal Structure ◽  
Mapk Pathway ◽  
Molecular Model ◽  
Md Simulations ◽  
Binding Pocket ◽  
Mitogen Activated Protein Kinase ◽  
Raf Kinase ◽  
Mitogen Activated Protein ◽  
Dimerization Interface ◽  
Continuous Surface

AbstractThe interaction between Ras and Raf-kinase through the Ras-binding (RBD) and cysteine-rich domains (CRD) of Raf is essential for signaling through the mitogen-activated protein kinase (MAPK) pathway, yet the molecular mechanism leading to Raf activation has remained elusive. We present the 2.8 Å crystal structure of the HRas/CRaf-RBD_CRD complex showing the Ras/Raf interface as a continuous surface on Ras. In the Ras dimer, with helices roughly perpendicular to the membrane, the CRD is located between the two Ras protomers and far from the membrane, where its dynamic nature in the Ras binding pocket is expected to accommodate BRaf and CRaf heterodimers. Our structure and its analysis by MD simulations, combined with work in the literature, result in a molecular model in which Ras binding is involved in the release of Raf autoinhibition while the Ras/Raf complex dimerizes to promote a platform for signal amplification, with Raf-CRD poised to have direct and allosteric effects on both the Ras active site and the dimerization interface.

scholarly journals Specific Functional Features of the Cell Integrity MAP Kinase Pathway in the Dimorphic Fission Yeast Schizosaccharomyces japonicus

2021 ◽  
Vol 7 (6) ◽  
pp. 482
Author(s):  
Elisa Gómez-Gil ◽  
Alejandro Franco ◽  
Beatriz Vázquez-Marín ◽  
Francisco Prieto-Ruiz ◽  
Armando Pérez-Díaz ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Environmental Changes ◽  
Yeast Species ◽  
Mapk Signaling ◽  
Fine Tuning ◽  
Mitogen Activated Protein Kinase ◽  
Major Influence ◽  
Cell Integrity ◽  
Mitogen Activated Protein ◽  
Functional Features

Mitogen activated protein kinase (MAPK) signaling pathways execute essential functions in eukaryotic organisms by transducing extracellular stimuli into adaptive cellular responses. In the fission yeast model Schizosaccharomyces pombe the cell integrity pathway (CIP) and its core effector, MAPK Pmk1, play a key role during regulation of cell integrity, cytokinesis, and ionic homeostasis. Schizosaccharomyces japonicus, another fission yeast species, shows remarkable differences with respect to S. pombe, including a robust yeast to hyphae dimorphism in response to environmental changes. We show that the CIP MAPK module architecture and its upstream regulators, PKC orthologs Pck1 and Pck2, are conserved in both fission yeast species. However, some of S. pombe’s CIP-related functions, such as cytokinetic control and response to glucose availability, are regulated differently in S. japonicus. Moreover, Pck1 and Pck2 antagonistically regulate S. japonicus hyphal differentiation through fine-tuning of Pmk1 activity. Chimeric MAPK-swapping experiments revealed that S. japonicus Pmk1 is fully functional in S. pombe, whereas S. pombe Pmk1 shows a limited ability to execute CIP functions and promote S. japonicus mycelial development. Our findings also suggest that a modified N-lobe domain secondary structure within S. japonicus Pmk1 has a major influence on the CIP signaling features of this evolutionarily diverged fission yeast.

scholarly journals Identification of the functional components of the Ras signaling pathway regulating pituitary cell-specific gene expression.

1994 ◽  
Vol 14 (3) ◽  
pp. 1553-1565 ◽  
Author(s):  
K E Conrad ◽  
J M Oberwetter ◽  
R Vaillancourt ◽  
G L Johnson ◽  
A Gutierrez-Hartmann
Keyword(s):  
Gene Expression ◽  
Pituitary Cell ◽  
Mitogen Activated Protein Kinase ◽  
Specific Gene ◽  
Ras Signaling ◽  
Raf Kinase ◽  
Prolactin Gene ◽  
Ras Signaling Pathway ◽  
Mitogen Activated Protein ◽  
Prolactin Promoter

Ras, a small GTP-binding protein, is required for functional receptor tyrosine kinase signaling. Ultimately, Ras alters the activity of specific nuclear transcription factors and regulates novel patterns of gene expression. Using a rat prolactin promoter construct in transient transfection experiments, we show that both oncogenic Ras and activated forms of Raf-1 kinase selectively stimulated the cellular rat prolactin promoter in GH4 rat pituitary cells. We also show that the Ras signal is completely blocked by an expression vector encoding a dominant-negative Raf kinase. Additionally, using a molecular genetic approach, we determined that inhibitory forms of p42 mitogen-activated protein kinase and an Ets-2 transcription factor interfere with both the Ras and the Raf activation of the rat prolactin promoter. These findings define a functional requirement for these signaling constituents in the activation of the prolactin gene, a cell-specific gene which marks the lactotroph pituitary cell type. Further, this analysis allowed us to order the components in the Ras signaling pathway as it impinges on regulation of prolactin gene transcription as Ras-->Raf kinase-->mitogen-activated protein kinase-->Ets. In contrast, we show that intact c-Jun expression inhibited the Ras-induced activation of the prolactin promoter, defining it as a negative regulator of this pathway, whereas c-Jun was able to enhance the Ras activation of an AP-1-driven promoter in GH4 cells. These data show that c-Jun is not the nuclear mediator of the Ras signal for the highly specialized, pituitary cell-specific prolactin cellular promoter. Thus, we have defined a model system which provides an ideal paradigm for studying Ras/Raf signaling pathways and their effects on neuroendocrine cell-specific gene regulation.

scholarly journals Suramin Targets the Conserved Ligand-Binding Pocket of Human Raf1 Kinase Inhibitory Protein

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1151
Author(s):  
Chenyun Guo ◽  
Zhihua Wu ◽  
Weiliang Lin ◽  
Hao Xu ◽  
Ting Chang ◽  
...  
Keyword(s):  
Side Effects ◽  
Ligand Binding ◽  
Mapk Pathway ◽  
Regulatory Protein ◽  
Therapeutic Index ◽  
Binding Pocket ◽  
Biological Macromolecules ◽  
Inhibitory Protein ◽  
Ligand Binding Pocket ◽  
Raf1 Kinase

Suramin was initially used to treat African sleeping sickness and has been clinically tested to treat human cancers and HIV infection in the recent years. However, the therapeutic index is low with numerous clinical side-effects, attributed to its diverse interactions with multiple biological macromolecules. Here, we report a novel binding target of suramin, human Raf1 kinase inhibitory protein (hRKIP), which is an important regulatory protein involved in the Ras/Raf1/MEK/ERK (MAPK) signal pathway. Biolayer interference technology showed that suramin had an intermediate affinity for binding hRKIP with a dissociation constant of 23.8 µM. Both nuclear magnetic resonance technology and molecular docking analysis revealed that suramin bound to the conserved ligand-binding pocket of hRKIP, and that residues K113, W173, and Y181 play crucial roles in hRKIP binding suramin. Furthermore, suramin treatment at 160 µM could profoundly increase the ERK phosphorylation level by around 3 times. Our results indicate that suramin binds to hRKIP and prevents hRKIP from binding with hRaf1, thus promoting the MAPK pathway. This work is beneficial to both mechanistically understanding the side-effects of suramin and efficiently improving the clinical applications of suramin.

scholarly journals Effect of Static Magnetic Field on Monascus ruber M7 Based on Transcriptome Analysis

2021 ◽  
Vol 7 (4) ◽  
pp. 256
Author(s):  
Shuyan Yang ◽  
Hongyi Zhou ◽  
Weihua Dai ◽  
Juan Xiong ◽  
Fusheng Chen
Keyword(s):  
Magnetic Field ◽  
Static Magnetic Field ◽  
Morphological Characteristics ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Primary Metabolism ◽  
Monascus Ruber ◽  
Growing Period ◽  
Monascus Pigments ◽  
Mitogen Activated Protein

The effects of a static magnetic field (SMF) on Monascus ruber M7 (M. ruber M7) cultured on potato dextrose agar (PDA) plates under SMF treatment at different intensities (5, 10, and 30 mT) were investigated in this paper. The results revealed that, compared with the control (CK, no SMF treatment), the SMF at all tested intensities did not significantly influence the morphological characteristics of M. ruber M7, while the intracellular and extracellular Monascus pigments (MPs) and extracellular citrinin (CIT) of M. ruber M7 were increased at 10 and 30 mT SMF but there was no impact on the MPs and CIT at 5 mT SMF. The transcriptome data of M. ruber M7 cultured at 30 mT SMF on PDA for 3 and 7 d showed that the SMF could increase the transcriptional levels of some relative genes with the primary metabolism, including the carbohydrate metabolism, amino acid metabolism, and lipid metabolism, especially in the early growing period (3 d). SMF could also affect the transcriptional levels of the related genes to the biosynthetic pathways of MPs, CIT, and ergosterol, and improve the transcription of the relative genes in the mitogen-activated protein kinase (MAPK) signaling pathway of M. ruber M7. These findings provide insights into a comprehensive understanding of the effects of SMF on filamentous fungi.

scholarly journals The Emerging Role of Macrophages in Immune System Dysfunction under Real and Simulated Microgravity Conditions

2021 ◽  
Vol 22 (5) ◽  
pp. 2333
Author(s):  
Yulong Sun ◽  
Yuanyuan Kuang ◽  
Zhuo Zuo
Keyword(s):  
Immune System ◽  
Mapk Signaling ◽  
Immune Defense ◽  
Mitogen Activated Protein Kinase ◽  
Therapeutic Drugs ◽  
Physiological Processes ◽  
Immune System Dysfunction ◽  
Cell Immunity ◽  
Mitogen Activated Protein ◽  
Microgravity Conditions

In the process of exploring space, the astronaut’s body undergoes a series of physiological changes. At the level of cellular behavior, microgravity causes significant alterations, including bone loss, muscle atrophy, and cardiovascular deconditioning. At the level of gene expression, microgravity changes the expression of cytokines in many physiological processes, such as cell immunity, proliferation, and differentiation. At the level of signaling pathways, the mitogen-activated protein kinase (MAPK) signaling pathway participates in microgravity-induced immune malfunction. However, the mechanisms of these changes have not been fully elucidated. Recent studies suggest that the malfunction of macrophages is an important breakthrough for immune disorders in microgravity. As the first line of immune defense, macrophages play an essential role in maintaining homeostasis. They activate specific immune responses and participate in large numbers of physiological activities by presenting antigen and secreting cytokines. The purpose of this review is to summarize recent advances on the dysfunction of macrophages arisen from microgravity and to discuss the mechanisms of these abnormal responses. Hopefully, our work will contribute not only to the future exploration on the immune system in space, but also to the development of preventive and therapeutic drugs against the physiological consequences of spaceflight.

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