scholarly journals PDZ-RhoGEF ubiquitination by Cullin3–KLHL20 controls neurotrophin-induced neurite outgrowth

2011 ◽  
Vol 193 (6) ◽  
pp. 985-994 ◽  
Author(s):  
Mei-Yao Lin ◽  
Yu-Min Lin ◽  
Te-chan Kao ◽  
Hsiang-Hao Chuang ◽  
Ruey-Hwa Chen
Keyword(s):  
Neurite Outgrowth ◽  
Cortical Neurons ◽  
Mitogen Activated Protein Kinase ◽  
Nucleotide Exchange ◽  
Neuronal Morphogenesis ◽  
Rhoa Activity ◽  
Nucleotide Exchange Factor ◽  
Ubiquitin Ligase Complex ◽  
Neurotrophin 3 ◽  
Mitogen Activated Protein

The induction of neurite outgrowth and arborization is critical for developmental and regenerative processes. In this paper, we report that the BTB-kelch protein KLHL20 promoted neurite outgrowth and arborization in hippocampal and cortical neurons through its interaction with Cullin3 to form a ubiquitin ligase complex. This complex targeted PDZ–Rho guanine nucleotide exchange factor (RhoGEF), a protein abundantly expressed in the brain, for ubiquitin-dependent proteolysis, thereby restricting RhoA activity and facilitating growth cone spreading and neurite outgrowth. Importantly, targeting PDZ-RhoGEF to KLHL20 required PDZ-RhoGEF phosphorylation by p38 mitogen-activated protein kinase. In response to p38-activating neurotrophins, such as brain-derived neurotrophic factor and neurotrophin-3, KLHL20-mediated PDZ-RhoGEF destruction was potentiated, leading to neurotrophin-induced neurite outgrowth. Our study identified a ubiquitin-dependent pathway that targets PDZ-RhoGEF destruction to facilitate neurite outgrowth and indicates a key role of this pathway in neurotrophin-induced neuronal morphogenesis.

scholarly journals Semaphorin 4D activates the MAPK pathway downstream of plexin-B1

2006 ◽  
Vol 394 (2) ◽  
pp. 459-464 ◽  
Author(s):  
Jennifer Aurandt ◽  
Weiquan Li ◽  
Kun-Liang Guan
Keyword(s):  
Nervous System ◽  
Mapk Pathway ◽  
Large Family ◽  
Cellular Systems ◽  
Mitogen Activated Protein Kinase ◽  
Nucleotide Exchange ◽  
Semaphorin 4D ◽  
C Terminus ◽  
Nucleotide Exchange Factor ◽  
Mitogen Activated Protein

Semaphorins are a large family of transmembrane and secreted proteins that signal primarily through the receptor plexin. Semaphorins have been characterized in the nervous system as axon guidance cues; however, they have also been shown to control development of other cellular systems such as the vasculature and lungs. As the role of semaphorins outside of the nervous system has broadened, so has elucidation of the intracellular signalling pathways they initiate. Previously, we and others have shown that plexin-B1 activates RhoA through the binding and activation of RhoGEF (guanine nucleotide-exchange factor)/LARG (leukaemia-associated RhoGEF) in response to semaphorin 4D stimulation. In the present study, we show that semaphorin 4D activates the MAPK (mitogen-activated protein kinase) pathway. We have found that the mechanism of activation requires the C-terminus of plexin-B1 and the activation of RhoA.

scholarly journals Cleavage of the signaling mucin Msb2 by the aspartyl protease Yps1 is required for MAPK activation in yeast

2008 ◽  
Vol 181 (7) ◽  
pp. 1073-1081 ◽  
Author(s):  
Nadia Vadaie ◽  
Heather Dionne ◽  
Darowan S. Akajagbor ◽  
Seth R. Nickerson ◽  
Damian J. Krysan ◽  
...  
Keyword(s):  
Mapk Pathway ◽  
Active Form ◽  
Cell Polarization ◽  
Mitogen Activated Protein Kinase ◽  
Aspartyl Protease ◽  
Nucleotide Exchange ◽  
Mapk Activation ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Mitogen Activated Protein

Signaling mucins are cell adhesion molecules that activate RAS/RHO guanosine triphosphatases and their effector mitogen-activated protein kinase (MAPK) pathways. We found that the Saccharomyces cerevisiae mucin Msb2p, which functions at the head of the Cdc42p-dependent MAPK pathway that controls filamentous growth, is processed into secreted and cell-associated forms. Cleavage of the extracellular inhibitory domain of Msb2p by the aspartyl protease Yps1p generated the active form of the protein by a mechanism incorporating cellular nutritional status. Activated Msb2p functioned through the tetraspan protein Sho1p to induce MAPK activation as well as cell polarization, which involved the Cdc42p guanine nucleotide exchange factor Cdc24p. We postulate that cleavage-dependent activation is a general feature of signaling mucins, which brings to light a novel regulatory aspect of this class of signaling adhesion molecule.

scholarly journals Structurally different lysophosphatidylethanolamine species stimulate neurite outgrowth in cultured cortical neurons via distinct signaling pathway

2020 ◽  
Author(s):  
Kazutoshi Hisano ◽  
Shiori Kawase ◽  
Tetsuhiko Mimura ◽  
Hiroki Yamada ◽  
Hisao Haniu ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Neurite Outgrowth ◽  
Cortical Neurons ◽  
Mitogen Activated Protein Kinase ◽  
Dependent Manner ◽  
Neuronal Viability ◽  
Form And Function ◽  
Mitogen Activated Protein ◽  
Cultured Cortical Neurons ◽  
Mapk Inhibitor

Abstract Neurite outgrowth is important in neuronal circuit formation and functions, and for regeneration of neuronal networks following trauma and disease in the brain. Thus, identification and characterization of the molecules that regulate neurite outgrowth are essential for understanding how brain circuits form and function and for the development of treatment of neurological disorders. In this study, we found that lysophosphatidylethanolamine (LPE), one of the lysophospholipids, influences neurite outgrowth in cultured cortical neurons. Extracellular application of either of the structurally different LPE spices, palmitoyl LPE (16:0 LPE) and stearoyl LPE (18:0 LPE) dramatically increased the areas of axon and dendrite without affecting the neuronal viability. Subsequent analysis revealed that both LPEs increased the length of neurite in a dose-dependent manner. Interestingly, inhibition of phospholipase C, one of the effectors for G-protein-coupled receptor-mediated signaling pathways, inhibited 18:0 LPE-stimulated neurite outgrowth but not 16:0 LPE-stimulated neurite outgrowth. The effects of protein kinase C (PKC) inhibitors on neurite outgrowth were also different. Inhibitor against PKCα, β, δ, ε, η, and θ inhibited both 16:0 LPE- and 18:0 LPE-induced neurite outgrowth. In contrast, an inhibitor against PKCα, β, γ, δ, and ζ inhibited the 18:0 LPE effect but not the 16:0 LPE effect. We also found that both 16:0 LPE and 18:0 LPE activate mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK)1/2. There was no substantial difference in the amount of phosphorylated MAPK/ERK1/2 between 16:0 LPE and 18:0 LPE-treated cultures. MAPK inhibitor completely inhibited 18:0 LPE-induced neurite outgrowth and partially inhibited 16:0 LPE-induced neurite outgrowth. Thus, the effect of the MAPK inhibitor differed between the 16:0 LPE- and 18:0 LPE-treated cultures. Collectively, the results suggest that the structurally different LPE species, 16:0 LPE and 18:0 LPE stimulate neurite outgrowth through the distinct signaling cascades in cultured cortical neurons.

scholarly journals Two Ras Pathways in Fission Yeast Are Differentially Regulated by Two Ras Guanine Nucleotide Exchange Factors

2002 ◽  
Vol 22 (13) ◽  
pp. 4598-4606 ◽  
Author(s):  
Piyi Papadaki ◽  
Véronique Pizon ◽  
Brian Onken ◽  
Eric C. Chang
Keyword(s):  
Mitogen Activated Protein Kinase ◽  
Critical Element ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Signaling Specificity ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Mitogen Activated Protein ◽  
Kinase Cascade ◽  
Synthetically Lethal

ABSTRACT How a given Ras prreotein coordinates multiple signaling inputs and outputs is a fundamental issue of signaling specificity. Schizosaccharomyces pombe contains one Ras, Ras1, that has two distinct outputs. Ras1 activates Scd1, a presumptive guanine nucleotide exchange factor (GEF) for Cdc42, to control morphogenesis and chromosome segregation, and Byr2, a component of a mitogen-activated protein kinase cascade, to control mating. So far there is only one established Ras1 GEF, Ste6. Paradoxically, ste6 null (ste6Δ) mutants are sterile but normal in cell morphology. This suggests that Ste6 specifically activates the Ras1-Byr2 pathway and that there is another GEF capable of activating the Scd1 pathway. We thereby characterized a potential GEF, Efc25. Genetic data place Efc25 upstream of the Ras1-Scd1, but not the Ras1-Byr2, pathway. Like ras1Δ and scd1Δ, efc25Δ is synthetically lethal with a deletion in tea1, a critical element for cell polarity control. Using truncated proteins, we showed that the C-terminal GEF domain of Efc25 is essential for function and regulated by the N terminus. We conclude that Efc25 acts as a Ras1 GEF specific for the Scd1 pathway. While ste6 expression is induced during mating, efc25 expression is constitutive. Moreover, Efc25 overexpression renders cells hyperelongated and sterile; the latter can be rescued by activated Ras1. This suggests that Efc25 can recruit Ras1 to selectively activate Scd1 at the expense of Byr2. Reciprocally, Ste6 overexpression can block Scd1 activation. We propose that external signals can partly segregate two Ras1 pathways by modulating GEF expression and that GEFs can influence how Ras is coupled to specific effectors.

scholarly journals p27Kip1 Inhibition of GRB2-SOS Formation Can Regulate Ras Activation

2003 ◽  
Vol 23 (11) ◽  
pp. 3735-3752 ◽  
Author(s):  
Stephanie J. Moeller ◽  
Elizabeth D. Head ◽  
Robert J. Sheaff
Keyword(s):  
Human Cancer ◽  
Growth Factor Receptor ◽  
Mitogen Activated Protein Kinase ◽  
Control Mechanisms ◽  
Nucleotide Exchange ◽  
Restriction Point ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Ras Activation ◽  
Mitogen Activated Protein

ABSTRACT p27Kip1 (p27) is often inappropriately downregulated in aggressive human cancers. Although p27 can inhibit cyclin-dependent kinases (CDKs), low p27 does not always correlate with increased CDK activity. Furthermore, cells derived from p27−/− mice respond to antimitogens, maintain restriction point control, and do not deregulate CDKs. Thus, disruption of a p27 function other than CDK inhibition may contribute to the disease state. A yeast two-hybrid screen identified growth factor receptor-bound protein 2 (GRB2) as a p27 binding partner. We now demonstrate that p27 can inhibit GRB2 function by blocking its association with the guanine nucleotide exchange factor SOS. Endogenous p27 is rapidly exported from the nucleus to the cytoplasm in response to mitogen stimulation, where it binds GRB2 concomitant with a decrease in GRB2-associated SOS. As predicted, mitogen-stimulated p27−/− cells maintained their GRB2-SOS complexes for significantly longer. The Ras/mitogen-activated protein kinase pathway does not appear to be deregulated in cells lacking p27 despite excess GRB2-SOS, suggesting that additional control mechanisms are present. A transient-transfection approach was employed to show that p27 can inhibit Ras activation by targeting GRB2 and further revealed that the CDK and GRB2 inhibitory functions of p27 are separable and distinct. Thus, p27 downregulation may compromise control of Ras, one of the most common oncogenic events in human cancer.

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