Analysis of Dominant Enhancers and Suppressors of Activated Notch in Drosophila

Genetics ◽  
1996 ◽  
Vol 144 (3) ◽  
pp. 1127-1141 ◽  
Author(s):  
Esther M Verheyen ◽  
Karen J Purcell ◽  
Mark E Fortini ◽  
Spyros Artavanis-Tsakonas
Keyword(s):  
Cell Fate ◽  
Notch Signaling Pathway ◽  
Notch Receptor ◽  
Gene Products ◽  
Mutagenesis Screen ◽  
Cell Fate Decisions ◽  
Site Mutagenesis ◽  
Notch Receptor Signaling ◽  
Cellular Transformations ◽  
New Alleles

Abstract The Notch receptor controls cell fate decisions throughout Drosophila development. Truncated, ligand-independent forms of this protein delay or block differentiation. We have previously shown that expression of the intracellular domain of the receptor under the control of the sevenless enhancer/promoter induces a rough eye phenotype in the adult fly. Analysis of the resultant cellular transformations suggested that this form of Notch acts as a constitutively activated receptor. To identify gene products that interact with Notch, a second-site mutagenesis screen was performed to isolate enhancers and suppressors of the eye phenotype caused by expression of these activated Notch molecules. We screened 137,000 mutagenized flies and recovered 290 dominant modifiers. Many new alleles of previously identified genes were isolated, as were mutations defining novel loci that may function in the Notch signaling pathway. We discuss the data with respect to known features of Notch receptor signaling and Drosophila eye development.

scholarly journals Synergy between the ESCRT-III complex and Deltex defines a ligand-independent Notch signal

2011 ◽  
Vol 195 (6) ◽  
pp. 1005-1015 ◽  
Author(s):  
Kazuya Hori ◽  
Anindya Sen ◽  
Tom Kirchhausen ◽  
Spyros Artavanis-Tsakonas
Keyword(s):  
Cell Fate ◽  
Notch Signaling Pathway ◽  
Notch Receptor ◽  
Endocytic Pathway ◽  
Lysosomal Degradation ◽  
Cell Fate Decisions ◽  
Rate Limiting Step ◽  
Notch Signal ◽  
Endocytic Machinery ◽  
A Cell

The Notch signaling pathway defines a conserved mechanism that regulates cell fate decisions in metazoans. Signaling is modulated by a broad and multifaceted genetic circuitry, including members of the endocytic machinery. Several individual steps in the endocytic pathway have been linked to the positive or negative regulation of the Notch receptor. In seeking genetic elements involved in regulating the endosomal/lysosomal degradation of Notch, mediated by the molecular synergy between the ubiquitin ligase Deltex and Kurtz, the nonvisual β-arrestin in Drosophila, we identified Shrub, a core component of the ESCRT-III complex as a key modulator of this synergy. Shrub promotes the lysosomal degradation of the receptor by mediating its delivery into multivesicular bodies (MVBs). However, the interplay between Deltex, Kurtz, and Shrub can bypass this path, leading to the activation of the receptor. Our analysis shows that Shrub plays a pivotal rate-limiting step in late endosomal ligand-independent Notch activation, depending on the Deltex-dependent ubiquitinylation state of the receptor. This activation mode of the receptor emphasizes the complexity of Notch signal modulation in a cell and has significant implications for both development and disease.

scholarly journals Drosophila Notch receptor activity suppresses Hairless function during adult external sensory organ development.

Genetics ◽  
1995 ◽  
Vol 141 (4) ◽  
pp. 1491-1505
Author(s):  
D F Lyman ◽  
B Yedvobnick
Keyword(s):  
Cell Fate ◽  
Daughter Cell ◽  
Notch Receptor ◽  
Sensory Organ ◽  
Cell Fates ◽  
Gain Of Function ◽  
Over Expression ◽  
Cell Fate Decisions ◽  
Synergistic Enhancement ◽  
Conditional Expression

Abstract The neurogenic Notch locus of Drosophila encodes a receptor necessary for cell fate decisions within equivalence groups, such as proneural clusters. Specification of alternate fates within clusters results from inhibitory communication among cells having comparable neural fate potential. Genetically, Hairless (H) acts as an antagonist of most neurogenic genes and may insulate neural precursor cells from inhibition. H function is required for commitment to the bristle sensory organ precursor (SOP) cell fate and for daughter cell fates. Using Notch gain-of-function alleles and conditional expression of an activated Notch transgene, we show that enhanced signaling produces H-like loss-of-function phenotypes by suppressing bristle SOP cell specification or by causing an H-like transformation of sensillum daughter cell fates. Furthermore, adults carrying Notch gain of function and H alleles exhibit synergistic enhancement of mutant phenotypes. Over-expression of an H+ transgene product suppressed virtually all phenotypes generated by Notch gain-of-function genotypes. Phenotypes resulting from over-expression of the H+ transgene were blocked by the Notch gain-of-function products, indicating a balance between Notch and H activity. The results suggest that H insulates SOP cells from inhibition and indicate that H activity is suppressed by Notch signaling.

Role of Notch and achaete-scute complex in the expression of Enhancer of split bHLH proteins

Development ◽  
1995 ◽  
Vol 121 (11) ◽  
pp. 3745-3752 ◽  
Author(s):  
V. Jennings ◽  
J. de Celis ◽  
C. Delidakis ◽  
A. Preiss ◽  
S. Bray
Keyword(s):  
Cell Fate ◽  
Notch Pathway ◽  
Interaction Mechanism ◽  
Cell Interaction ◽  
Precursor Cell ◽  
Notch Receptor ◽  
Sensory Organ ◽  
Cell Fate Decisions ◽  
Sensory Organ Precursor ◽  
Enhancer Of Split

The proteins encoded by Notch and the Enhancer of split complex are components of a cell-cell interaction mechanism which is important in many cell fate decisions throughout development. One such decision is the formation of the sensory organ precursor cell during the development of the peripheral nervous system in Drosophila. Cells acquire the potential to be neural through the expression of the proneural genes, and the Notch pathway is required to limit neural fate to a single cell from a proneural cluster. However, despite extensive analysis, the precise pathways linking the proneural with Notch and Enhancer of split gene functions remain obscure. For example, it has been suggested that achaete-scute complex proteins directly activate Enhancer of split genes leaving the action of Notch in the pathway unclear. Using monoclonal antibodies that recognise products of the Enhancer of split complex, we show that these proteins accumulate in the cells surrounding the developing sensory organ precursor cell and that their expression is dependent on the activity of Notch and does not directly correlate with expression of Achaete. We further clarify the pathway by showing that ubiquitous expression of an activated Notch receptor leads to widespread accumulation of Enhancer of split proteins even in the absence of achaete-scute complex proteins. Thus Enhancer of split protein expression in response to Notch activity does not require achaete-scute complex proteins.

scholarly journals Cancer Stem Cells, Quo Vadis? The Notch Signaling Pathway in Tumor Initiation and Progression

Cells ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1879 ◽  
Author(s):  
Christian T. Meisel ◽  
Cristina Porcheri ◽  
Thimios A. Mitsiadis
Keyword(s):  
Stem Cells ◽  
Cancer Stem Cells ◽  
Notch Signaling ◽  
Signaling Pathway ◽  
Cell Fate ◽  
Adult Life ◽  
Notch Pathway ◽  
Notch Signaling Pathway ◽  
Fine Tuning ◽  
Cell Fate Decisions

The Notch signaling pathway regulates cell proliferation, cytodifferentiation and cell fate decisions in both embryonic and adult life. Several aspects of stem cell maintenance are dependent from the functionality and fine tuning of the Notch pathway. In cancer, Notch is specifically involved in preserving self-renewal and amplification of cancer stem cells, supporting the formation, spread and recurrence of the tumor. As the function of Notch signaling is context dependent, we here provide an overview of its activity in a variety of tumors, focusing mostly on its role in the maintenance of the undifferentiated subset of cancer cells. Finally, we analyze the potential of molecules of the Notch pathway as diagnostic and therapeutic tools against the various cancers.

scholarly journals Ero1L, a thiol oxidase, is required for Notch signaling through cysteine bridge formation of the Lin12-Notch repeats in Drosophila melanogaster

2008 ◽  
Vol 182 (6) ◽  
pp. 1113-1125 ◽  
Author(s):  
An-Chi Tien ◽  
Akhila Rajan ◽  
Karen L. Schulze ◽  
Hyung Don Ryoo ◽  
Melih Acar ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Notch Signaling ◽  
Cell Fate ◽  
Disulfide Bonds ◽  
Cell Communication ◽  
Notch Receptor ◽  
Cell Fate Decisions ◽  
Unfolded Protein ◽  
Thiol Oxidase ◽  
The Unfolded Protein Response

Notch-mediated cell–cell communication regulates numerous developmental processes and cell fate decisions. Through a mosaic genetic screen in Drosophila melanogaster, we identified a role in Notch signaling for a conserved thiol oxidase, endoplasmic reticulum (ER) oxidoreductin 1–like (Ero1L). Although Ero1L is reported to play a widespread role in protein folding in yeast, in flies Ero1L mutant clones show specific defects in lateral inhibition and inductive signaling, two characteristic processes regulated by Notch signaling. Ero1L mutant cells accumulate high levels of Notch protein in the ER and induce the unfolded protein response, suggesting that Notch is misfolded and fails to be exported from the ER. Biochemical assays demonstrate that Ero1L is required for formation of disulfide bonds of three Lin12-Notch repeats (LNRs) present in the extracellular domain of Notch. These LNRs are unique to the Notch family of proteins. Therefore, we have uncovered an unexpected requirement for Ero1L in the maturation of the Notch receptor.

scholarly journals Delta-1 Activation of Notch-1 Signaling Results inHES-1 Transactivation

1998 ◽  
Vol 18 (12) ◽  
pp. 7423-7431 ◽  
Author(s):  
Sophie Jarriault ◽  
Odile Le Bail ◽  
Estelle Hirsinger ◽  
Olivier Pourquié ◽  
Frédérique Logeat ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Drosophila Melanogaster ◽  
Notch Signaling ◽  
Cell Fate ◽  
Notch Signaling Pathway ◽  
Notch Receptor ◽  
Cell Fate Determination ◽  
Notch 1 ◽  
Promoter Construct ◽  
Enhancer Of Split

ABSTRACT The Notch receptor is involved in many cell fate determination events in vertebrates and invertebrates. It has been shown inDrosophila melanogaster that Delta-dependent Notch signaling activates the transcription factor Suppressor of Hairless, leading to an increased expression of the Enhancer of Splitgenes. Genetic evidence has also implicated the kuzbaniangene, which encodes a disintegrin metalloprotease, in the Notch signaling pathway. By using a two-cell coculture assay, we show here that vertebrate Dl-1 activates the Notch-1 cascade. Consistent with previous data obtained with active forms of Notch-1 aHES-1-derived promoter construct is transactivated in cells expressing Notch-1 in response to Dl-1 stimulation. Impairing the proteolytic maturation of the full-length receptor leads to a decrease in HES-1 transactivation, further supporting the hypothesis that only mature processed Notch is expressed at the cell surface and activated by its ligand. Furthermore, we observed that Dl-1-inducedHES-1 transactivation was dependent both on Kuzbanian and RBP-J activities, consistent with the involvement of these two proteins in Notch signaling in Drosophila. We also observed that exposure of Notch-1-expressing cells to Dl-1 results in an increased level of endogenous HES-1 mRNA. Finally, coculture of Dl-1-expressing cells with myogenic C2 cells suppresses differentiation of C2 cells into myotubes, as previously demonstrated for Jagged-1 and Jagged-2, and also leads to an increased level of endogenousHES-1 mRNA. Thus, Dl-1 behaves as a functional ligand for Notch-1 and has the same ability to suppress cell differentiation as the Jagged proteins do.

Dynamics of Notch signalling in the mouse oviduct and uterus during the oestrous cycle

2016 ◽  
Vol 28 (11) ◽  
pp. 1663 ◽  
Author(s):  
D. Murta ◽  
M. Batista ◽  
A. Trindade ◽  
E. Silva ◽  
L. Mateus ◽  
...  
Keyword(s):  
Real Time ◽  
Cell Fate ◽  
Expression Patterns ◽  
Cell Signalling ◽  
Notch Signalling ◽  
Notch Receptor ◽  
Effector Proteins ◽  
Oestrous Cycle ◽  
Cell Fate Decisions ◽  
Effector Genes

The oviduct and uterus undergo extensive cellular remodelling during the oestrous cycle, requiring finely tuned intercellular communication. Notch is an evolutionarily conserved cell signalling pathway implicated in cell fate decisions in several tissues. In the present study we evaluated the quantitative real-time polymerase chain reaction (real-time qPCR) and expression (immunohistochemistry) patterns of Notch components (Notch1–4, Delta-like 1 (Dll1), Delta-like 4 (Dll4), Jagged1–2) and effector (hairy/enhancer of split (Hes) 1–2, Hes5 and Notch-Regulated Ankyrin Repeat-Containing Protein (Nrarp)) genes in the mouse oviduct and uterus throughout the oestrous cycle. Notch genes are differentially transcribed and expressed in the mouse oviduct and uterus throughout the oestrous cycle. The correlated transcription levels of Notch components and effector genes, and the nuclear detection of Notch effector proteins, indicate that Notch signalling is active. The correlation between transcription levels of Notch genes and progesterone concentrations, and the association between expression of Notch proteins and progesterone receptor (PR) activation, indicate direct progesterone regulation of Notch signalling. The expression patterns of Notch proteins are spatially and temporally specific, resulting in unique expression combinations of Notch receptor, ligand and effector genes in the oviduct luminal epithelium, uterus luminal and glandular epithelia and uterine stroma throughout the oestrous cycle. Together, the results of the present study imply a regulatory role for Notch signalling in oviduct and uterine cellular remodelling occurring throughout the oestrous cycle.

scholarly journals Vital roles of mTOR complex 2 in Notch-driven thymocyte differentiation and leukemia

2012 ◽  
Vol 209 (4) ◽  
pp. 713-728 ◽  
Author(s):  
Keunwook Lee ◽  
Ki Taek Nam ◽  
Sung Hoon Cho ◽  
Prathyusha Gudapati ◽  
Yoonha Hwang ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Notch Signaling ◽  
Cell Fate ◽  
Lymphoblastic Leukemia ◽  
Notch Receptor ◽  
Leukemic Cells ◽  
Cell Fate Decisions ◽  
Proliferation And Differentiation ◽  
Physiological Outcomes

Notch plays critical roles in both cell fate decisions and tumorigenesis. Notch receptor engagement initiates signaling cascades that include a phosphatidylinositol 3-kinase/target of rapamycin (TOR) pathway. Mammalian TOR (mTOR) participates in two distinct biochemical complexes, mTORC1 and mTORC2, and the relationship between mTORC2 and physiological outcomes dependent on Notch signaling is unknown. In this study, we report contributions of mTORC2 to thymic T-cell acute lymphoblastic leukemia (T-ALL) driven by Notch. Conditional deletion of Rictor, an essential component of mTORC2, impaired Notch-driven proliferation and differentiation of pre-T cells. Furthermore, NF-κB activity depended on the integrity of mTORC2 in thymocytes. Active Akt restored NF-κB activation, a normal rate of proliferation, and differentiation of Rictor-deficient pre-T cells. Strikingly, mTORC2 depletion lowered CCR7 expression in thymocytes and leukemic cells, accompanied by decreased tissue invasion and delayed mortality in T-ALL driven by Notch. Collectively, these findings reveal roles for mTORC2 in promoting thymic T cell development and T-ALL and indicate that mTORC2 is crucial for Notch signaling to regulate Akt and NF-κB.

scholarly journals The Drosophila melanogaster Suppressor of deltex Gene, a Regulator of the Notch Receptor Signaling Pathway, Is an E3 Class Ubiquitin Ligase

Genetics ◽  
1999 ◽  
Vol 152 (2) ◽  
pp. 567-576 ◽  
Author(s):  
M Cornell ◽  
D A P Evans ◽  
R Mann ◽  
M Fostier ◽  
M Flasza ◽  
...  
Keyword(s):  
Notch Signaling ◽  
Signaling Pathway ◽  
Cell Fate ◽  
Ubiquitin Ligase ◽  
Notch Pathway ◽  
Notch Receptor ◽  
Negative Regulator ◽  
Loss Of Function ◽  
Wing Vein ◽  
Cell Fate Decisions

Abstract During development, the Notch receptor regulates many cell fate decisions by a signaling pathway that has been conserved during evolution. One positive regulator of Notch is Deltex, a cytoplasmic, zinc finger domain protein, which binds to the intracellular domain of Notch. Phenotypes resulting from mutations in deltex resemble loss-of-function Notch phenotypes and are suppressed by the mutation Suppressor of deltex [Su(dx)]. Homozygous Su(dx) mutations result in wing-vein phenotypes and interact genetically with Notch pathway genes. We have previously defined Su(dx) genetically as a negative regulator of Notch signaling. Here we present the molecular identification of the Su(dx) gene product. Su(dx) belongs to a family of E3 ubiquitin ligase proteins containing membrane-targeting C2 domains and WW domains that mediate protein-protein interactions through recognition of proline-rich peptide sequences. We have identified a seven-codon deletion in a Su(dx) mutant allele and we show that expression of Su(dx) cDNA rescues Su(dx) mutant phenotypes. Overexpression of Su(dx) also results in ectopic vein differentiation, wing margin loss, and wing growth phenotypes and enhances the phenotypes of loss-of-function mutations in Notch, evidence that supports the conclusion that Su(dx) has a role in the downregulation of Notch signaling.

scholarly journals A somatic proteoglycan controls Notch-directed germ cell fate

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sandeep Gopal ◽  
Aqilah Amran ◽  
Andre Elton ◽  
Leelee Ng ◽  
Roger Pocock
Keyword(s):  
Transcription Factor ◽  
Caenorhabditis Elegans ◽  
Germ Cell ◽  
Cell Fate ◽  
Notch Receptor ◽  
Cell Behavior ◽  
Cell Fate Decisions ◽  
Calcium Dependent ◽  
Notch Receptors ◽  
Germline Proliferation

AbstractCommunication between the soma and germline optimizes germ cell fate programs. Notch receptors are key determinants of germ cell fate but how somatic signals direct Notch-dependent germ cell behavior is undefined. Here we demonstrate that SDN-1 (syndecan-1), a somatic transmembrane proteoglycan, controls expression of the GLP-1 (germline proliferation-1) Notch receptor in the Caenorhabditis elegans germline. We find that SDN-1 control of a somatic TRP calcium channel governs calcium-dependent binding of an AP-2 transcription factor (APTF-2) to the glp-1 promoter. Hence, SDN-1 signaling promotes GLP-1 expression and mitotic germ cell fate. Together, these data reveal SDN-1 as a putative communication nexus between the germline and its somatic environment to control germ cell fate decisions.

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