Role of the EGFR/Ras/Raf pathway in specification of photoreceptor cells in the Drosophila retina

Development ◽  
2001 ◽  
Vol 128 (7) ◽  
pp. 1183-1191 ◽  
Author(s):  
L. Yang ◽  
N.E. Baker
Keyword(s):  
Map Kinase ◽  
Egf Receptor ◽  
Eye Development ◽  
Photoreceptor Cells ◽  
Cell Types ◽  
Cell Specification ◽  
Kinase Activation ◽  
Cell Spacing ◽  
Egfr Activation

The Drosophila EGF receptor is required for differentiation of many cell types during eye development. We have used mosaic analysis with definitive null mutations to analyze the effects of complete absence of EGFR, Ras or Raf proteins during eye development. The Egfr, ras and raf genes are each found to be essential for recruitment of R1-R7 cells. In addition Egfr is autonomously required for MAP kinase activation. EGFR is not essential for R8 cell specification, either alone or redundantly with any other receptor that acts through Ras or Raf, or by activating MAP kinase. As with Egfr, loss of ras or raf perturbs the spacing and arrangement of R8 precursor cells. R8 cell spacing is not affected by loss of argos in posteriorly juxtaposed cells, which rules out a model in which EGFR acts through argos expression to position R8 specification in register between adjacent columns of ommatidia. The R8 spacing role of the EGFR was partially affected by simultaneous deletion of spitz and vein, two ligand genes, but the data suggest that EGFR activation independent of spitz and vein is also involved. The results prove that R8 photoreceptors are specified and positioned by distinct mechanisms from photoreceptors R1-R7.

Interaction between Drosophila EGF receptor and vnd determines three dorsoventral domains of the neuroectoderm

Development ◽  
1998 ◽  
Vol 125 (18) ◽  
pp. 3625-3633 ◽  
Author(s):  
Y. Yagi ◽  
T. Suzuki ◽  
S. Hayashi
Keyword(s):  
Map Kinase ◽  
Receptor Tyrosine Kinase ◽  
Egf Receptor ◽  
Regulatory Region ◽  
Homeobox Gene ◽  
Kinase Activation ◽  
Intermediate Column ◽  
Kinase Signaling Pathway ◽  
Map Kinase Signaling Pathway

Neurogenesis in Drosophila melanogaster starts by an ordered appearance of neuroblasts arranged in three columns (medial, intermediate and lateral) in each side of the neuroectoderm. Here we show that, in the intermediate column, the receptor tyrosine kinase DER represses expression of proneural genes, achaete and scute, and is required for the formation of neuroblasts. Most of the early function of DER is likely to be mediated by the Ras-MAP kinase signaling pathway, which is activated in the intermediate column, since a loss of a component of this pathway leads to a phenotype identical to that in DER mutants. MAP-kinase activation was also observed in the medial column where esg and proneural gene expression is unaffected by DER. We found that the homeobox gene vnd is required for the expression of esg and scute in the medial column, and show that vnd acts through the negative regulatory region of the esg enhancer that mediates the DER signal, suggesting the role of vnd is to counteract DER-dependent repression. Thus nested expression of vnd and the DER activator rhomboid is crucial to subdivide the neuroectoderm into the three dorsoventral domains.

Dissecting the roles of the Drosophila EGF receptor in eye development and MAP kinase activation

Development ◽  
1998 ◽  
Vol 125 (19) ◽  
pp. 3875-3885 ◽  
Author(s):  
J.P. Kumar ◽  
M. Tio ◽  
F. Hsiung ◽  
S. Akopyan ◽  
L. Gabay ◽  
...  
Keyword(s):  
Map Kinase ◽  
Egf Receptor ◽  
Eye Development ◽  
Neuronal Cells ◽  
Morphogenetic Furrow ◽  
Kinase Activation

A new conditional Egfr allele was used to dissect the roles of the receptor in eye development and to test two published models. EGFR function is necessary for morphogenetic furrow initiation, is not required for establishment of the founder R8 cell in each ommatidium, but is necessary to maintain its differentiated state. EGFR is required subsequently for recruitment of all other neuronal cells. The initial EGFR-dependent MAP kinase activation occurs in the furrow, but the active kinase (dp-ERK) is observed only in the cytoplasm for over 2 hours. Similarly, SEVENLESS-dependent activation results in cytoplasmic appearance of dp-ERK for 6 hours. These results suggest an additional regulated step in this pathway and we discuss models for this.

scholarly journals Integrins can collaborate with growth factors for phosphorylation of receptor tyrosine kinases and MAP kinase activation: roles of integrin aggregation and occupancy of receptors.

1996 ◽  
Vol 135 (6) ◽  
pp. 1633-1642 ◽  
Author(s):  
S Miyamoto ◽  
H Teramoto ◽  
J S Gutkind ◽  
K M Yamada
Keyword(s):  
Signal Transduction ◽  
Growth Factors ◽  
Growth Factor ◽  
Map Kinase ◽  
Tyrosine Kinases ◽  
Map Kinases ◽  
Egf Receptor ◽  
Growth Factor Receptor ◽  
Kinase Activation ◽  
Transient Activation

Integrins mediate cell adhesion, migration, and a variety of signal transduction events. These integrin actions can overlap or even synergize with those of growth factors. We examined for mechanisms of collaboration or synergy between integrins and growth factors involving MAP kinases, which regulate many cellular functions. In cooperation with integrins, the growth factors EGF, PDGF-BB, and basic FGF each produced a marked, transient activation of the ERK (extracellular signal-regulated kinase) class of MAP kinase, but only if the integrins were both aggregated and occupied by ligand. Transmembrane accumulation of total tyrosine-phosphorylated proteins, as well as nonsynergistic MAP kinase activation, could be induced by simple integrin aggregation, whereas enhanced transient accumulation of the EGF-receptor substrate eps8 required integrin aggregation and occupancy, as well as EGF treatment. Each type of growth factor receptor was itself induced to aggregate transiently by integrin ligand-coated beads in a process requiring both aggregation and occupancy of integrin receptors, but not the presence of growth factor ligand. Synergism was also observed between integrins and growth factors for triggering tyrosine phosphorylation of EGF, PDGF, and FGF receptors. This collaborative response also required both integrin aggregation and occupancy. These studies identify mechanisms in the signal transduction response to integrins and growth factors that require various combinations of integrin aggregation and ligands for integrin or growth factor receptors, providing opportunities for collaboration between these major regulatory systems.

Role of MAP kinase activation in Nramp1 mRNA stability in RAW264.7 macrophages expressing Nramp1Gly169

2002 ◽  
Vol 215 (2) ◽  
pp. 195-206 ◽  
Author(s):  
William P Lafuse ◽  
Gail R Alvarez ◽  
Bruce S Zwilling
Keyword(s):  
Map Kinase ◽  
Mrna Stability ◽  
Kinase Activation ◽  
Raw264.7 Macrophages

Protective role of Bcl-2 on β-amyloid-induced cell death of differentiated PC12 cells: reduction of NF-κB and p38 MAP kinase activation

2004 ◽  
Vol 49 (1) ◽  
pp. 69-80 ◽  
Author(s):  
Youn Sook Song ◽  
Hye Ji Park ◽  
Soo Yeon Kim ◽  
Seung Ho Lee ◽  
Hwan Soo Yoo ◽  
...  
Keyword(s):  
Cell Death ◽  
Map Kinase ◽  
Pc12 Cells ◽  
Protective Role ◽  
P38 Map Kinase ◽  
Kinase Activation ◽  
Differentiated Pc12 Cells ◽  
Β Amyloid

scholarly journals p38α Mitogen-activated Protein Kinase Sensitizes Cells to Apoptosis Induced by Different Stimuli

2004 ◽  
Vol 15 (2) ◽  
pp. 922-933 ◽  
Author(s):  
Almudena Porras ◽  
Susana Zuluaga ◽  
Emma Black ◽  
Amparo Valladares ◽  
Alberto M. Alvarez ◽  
...  
Keyword(s):  
Map Kinase ◽  
Cell Types ◽  
Mitogen Activated Protein Kinase ◽  
Extracellular Signal Regulated Kinase ◽  
Survival Pathways ◽  
Proapoptotic Protein ◽  
Extracellular Signal ◽  
Survival Pathway ◽  
Mitogen Activated Protein

p38α mitogen-activated protein (MAP) kinase is a broadly expressed signaling molecule that participates in the regulation of cellular responses to stress as well as in the control of proliferation and survival of many cell types. We have used cell lines derived from p38α knockout mice to study the role of this signaling pathway in the regulation of apoptosis. Here, we show that cardiomyocytes and fibroblasts lacking p38α are more resistant to apoptosis induced by different stimuli. The reduced apoptosis of p38α-deficient cells correlates with decreased expression of the mitochondrial proapoptotic protein Bax and the apoptosis-inducing receptor Fas/CD-95. Cells lacking p38α also have increased extracellular signal-regulated kinase (ERKs) MAP kinase activity, and the up-regulation of this survival pathway seems to be at least partially responsible for the reduced levels of apoptosis in the absence of p38α. Phosphorylation of the transcription factor STAT3 on Ser-727, mediated by the extracellular signal-regulated kinase MAP kinase pathway, may contribute to the decrease in both Bax and Fas expression in p38α-/- cells. Thus, p38α seems to sensitize cells to apoptosis via both up-regulation of proapoptotic proteins and down-regulation of survival pathways.

Ionomycin causes activation of p38 and p42/44 mitogen-activated protein kinases in human neutrophils

2001 ◽  
Vol 281 (1) ◽  
pp. C350-C360 ◽  
Author(s):  
David J. Elzi ◽  
A. Jason Bjornsen ◽  
Todd MacKenzie ◽  
Travis H. Wyman ◽  
Christopher C. Silliman
Keyword(s):  
Map Kinase ◽  
Map Kinases ◽  
P38 Map Kinase ◽  
Polymorphonuclear Neutrophils ◽  
Human Neutrophils ◽  
Kinase Activation ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Activating Transcription Factor

Many receptor-linked agents that prime or activate the NADPH oxidase in polymorphonuclear neutrophils (PMNs) elicit changes in cytosolic Ca2+concentration and activate mitogen-activated protein (MAP) kinases. To investigate the role of Ca2+in the activation of p38 and p42/44 MAP kinases, we examined the effects of the Ca2+-selective ionophore ionomycin on priming and activation of the PMN oxidase. Ionomycin caused a rapid rise in cytosolic Ca2+that was due to both a release of cytosolic Ca2+stores and Ca2+influx. Ionomycin also activated (2 μM) and primed (20–200 nM) the PMN oxidase. Dual phosphorylation of p38 MAP kinase and phosphorylation of its substrate activating transcription factor-2 were detected at ionomycin concentrations that prime or activate the PMN oxidase, while dual phosphorylation of p42/44 MAP kinase and phosphorylation of its substrate Elk-1 were elicited at 0.2–2 μM. SB-203580, a p38 MAP kinase antagonist, inhibited ionomycin-induced activation of the oxidase (68 ± 8%, P < 0.05) and tyrosine phosphorylation of 105- and 72-kDa proteins; conversely, PD-98059, an inhibitor of MAP/extracellular signal-related kinase 1, had no effect. Treatment of PMNs with thapsigargin resulted in priming of the oxidase and activation of p38 MAP kinase. Chelation of cytosolic but not extracellular Ca2+completely inhibited ionomycin activation of p38 MAP kinase, whereas chelation of extracellular Ca2+abrogated activation of p42/44 MAP kinase. These results demonstrate the importance of changes in cytosolic Ca2+for MAP kinase activation in PMNs.

scholarly journals N-syndecan deficiency impairs neural migration in brain

2006 ◽  
Vol 174 (4) ◽  
pp. 569-580 ◽  
Author(s):  
Anni Hienola ◽  
Sarka Tumova ◽  
Evgeny Kulesskiy ◽  
Heikki Rauvala
Keyword(s):  
Neuronal Migration ◽  
Egf Receptor ◽  
Src Kinase ◽  
Heparin Binding ◽  
Laminar Structure ◽  
Kinase Activation ◽  
Radial Migration ◽  
Migratory Routes ◽  
Migratory Stream

N-syndecan (syndecan-3) is a transmembrane proteoglycan that is abundantly expressed in the major axonal pathways and in the migratory routes of the developing brain. When ligated by heparin-binding (HB) growth-associated molecule (GAM; pleiotrophin), N-syndecan mediates cortactin–Src kinase-dependent neurite outgrowth. However, the functional role of N-syndecan in brain development remains unexplored. In this study, we show that N-syndecan deficiency perturbs the laminar structure of the cerebral cortex as a result of impaired radial migration. In addition, neural migration in the rostral migratory stream is impaired in the N-syndecan–null mice. We suggest that the migration defect depends on impaired HB-GAM–induced Src kinase activation and haptotactic migration. Furthermore, we show that N-syndecan interacts with EGF receptor (EGFR) at the plasma membrane and is required in EGFR-induced neuronal migration.

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