scholarly journals A Screen for Mutations That Suppress the Phenotype of Drosophila armadillo, the β-Catenin Homolog

Genetics ◽  
2000 ◽  
Vol 155 (4) ◽  
pp. 1725-1740
Author(s):  
Rachel T Cox ◽  
Donald G McEwen ◽  
Denise L Myster ◽  
Robert J Duronio ◽  
Joseph Loureiro ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Adhesion ◽  
Programmed Cell Death ◽  
Cell Survival ◽  
Wnt Pathway ◽  
Genetic Modifier ◽  
Wnt Signaling Pathway ◽  
Adherens Junction ◽  
Cell Fates ◽  
Wnt Signal

Abstract During development signaling pathways coordinate cell fates and regulate the choice between cell survival or programmed cell death. The well-conserved Wingless/Wnt pathway is required for many developmental decisions in all animals. One transducer of the Wingless/Wnt signal is Armadillo/β-catenin. Drosophila Armadillo not only transduces Wingless signal, but also acts in cell-cell adhesion via its role in the epithelial adherens junction. While many components of both the Wingless/Wnt signaling pathway and adherens junctions are known, both processes are complex, suggesting that unknown components influence signaling and junctions. We carried out a genetic modifier screen to identify some of these components by screening for mutations that can suppress the armadillo mutant phenotype. We identified 12 regions of the genome that have this property. From these regions and from additional candidate genes tested we identified four genes that suppress arm: dTCF, puckered, head involution defective (hid), and Dpresenilin. We further investigated the interaction with hid, a known regulator of programmed cell death. Our data suggest that Wg signaling modulates Hid activity and that Hid regulates programmed cell death in a dose-sensitive fashion.

scholarly journals The actin nucleation factors JMY and WHAMM enable a rapid p53-dependent pathway of apoptosis

2020 ◽  
Author(s):  
Virginia L. King ◽  
Nathan K. Leclair ◽  
Kenneth G. Campellone
Keyword(s):  
Gene Expression ◽  
Cell Death ◽  
Programmed Cell Death ◽  
Actin Cytoskeleton ◽  
Cell Survival ◽  
G Protein ◽  
Actin Nucleation ◽  
Caspase Cleavage ◽  
Cell Death Pathways ◽  
Small G Protein

AbstractThe actin cytoskeleton is a well-known player in most vital cellular processes, but comparably little is understood about how the actin assembly machinery impacts programmed cell death pathways. In the current study, we explored roles for the human Wiskott-Aldrich Syndrome Protein (WASP) family of actin nucleation factors in DNA damage-induced apoptosis. Inactivation of each WASP-family gene revealed that two, JMY and WHAMM, are required for rapid apoptotic responses. JMY and WHAMM enable p53-dependent cell death by enhancing mitochondrial permeabilization, initiator caspase cleavage, and executioner caspase activation. The loss of JMY additionally results in significant changes in gene expression, including upregulation of the small G-protein RhoD. Depletion or deletion of RHOD increases cell death, suggesting that RhoD normally plays a key role in cell survival. These results give rise to a model in which JMY and WHAMM promote intrinsic cell death responses that can be opposed by RhoD.Author SummaryThe actin cytoskeleton is a collection of protein polymers that assemble and disassemble within cells at specific times and locations. Cytoskeletal regulators called nucleation-promoting factors ensure that actin polymerizes when and where it is needed, and many of these factors are members of the Wiskott-Aldrich Syndrome Protein (WASP) family. Humans express 8 WASP-family proteins, but whether the different factors function in programmed cell death pathways is not well understood. In this study, we explored roles for each WASP-family member in apoptosis and found that a subfamily consisting of JMY and WHAMM are critical for a rapid pathway of cell death. Furthermore, the loss of JMY results in changes in gene expression, including a dramatic upregulation of the small G-protein RhoD, which appears to be crucial for cell survival. Collectively, our results point to the importance of JMY and WHAMM in driving intrinsic cell death responses plus a distinct function for RhoD in maintaining cell viability.

Cell death in normal and rough eye mutants of Drosophila

Development ◽  
1991 ◽  
Vol 113 (3) ◽  
pp. 825-839 ◽  
Author(s):  
T. Wolff ◽  
D.F. Ready
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Compound Eye ◽  
Cell Lineage ◽  
Cell Fates ◽  
Cone Cells ◽  
A Cell ◽  
Retinal Epithelium ◽  
Fly Eye ◽  
Dying Cells

The regular, reiterated cellular pattern of the Drosophila compound eye makes it a sensitive amplifier of defects in cell death. Quantitative and histological methods reveal a phase of cell death between 35 and 50 h of development which removes between 2 and 3 surplus cells per ommatidium. The timing of this epoch is consistent with cell death as the last fate to be specified in the progressive sequence of cell fates that build the ommatidium. An ultrastructural survey of cell death suggests dying cells in the fly eye have similarities as well as differences with standard descriptions of programmed cell death. A failure of cell death to remove surplus cells disorganizes the retinal lattice. A screen of rough eye mutants identifies two genes, roughest and echinus, required for the normal elimination of cells from the retinal epithelium. The use of an enhancer trap as a cell lineage marker shows that the cone cells, like other retinal cells, are not clonally related to each other or to their neighbors.

Local induction of patterning and programmed cell death in the developing Drosophila retina

Development ◽  
1998 ◽  
Vol 125 (12) ◽  
pp. 2327-2335 ◽  
Author(s):  
D.T. Miller ◽  
R.L. Cagan
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Egf Receptor ◽  
Pigment Cells ◽  
Cell Fates ◽  
Adult Retina ◽  
Ras Pathway ◽  
Cell Ablation ◽  
Cone Cells ◽  
Local Cell

Local cell signaling can pattern the nervous system by directing cell fates, including programmed cell death. In the developing Drosophila retina, programmed cell death is used to remove excess cells between ommatidia. Cell ablation revealed the source and position of signals required for regulating the pattern of programmed cell death among these interommatidial cells. Two types of signals regulate this patterning event. Notch-mediated signals between interommatidial precursors result in removal of unneeded cells. Cone cells and primary pigment cells oppose this signal by supplying a ‘life’-promoting activity; evidence is provided that this signal occurs through localized activation of the EGF Receptor/Ras pathway. Together, these signals refine the highly regular pattern observed in the adult retina.

scholarly journals A Novel Functional Screen in Human Cells Identifies MOCA as a Negative Regulator of Wnt Signaling

2008 ◽  
Vol 19 (11) ◽  
pp. 4660-4674 ◽  
Author(s):  
Elanite Caspi ◽  
Rina Rosin-Arbesfeld
Keyword(s):  
Cell Adhesion ◽  
Wnt Pathway ◽  
Target Genes ◽  
Negative Regulator ◽  
T Cell Factor ◽  
Functional Screen ◽  
Brain Cdna Library ◽  
Membrane Bound ◽  
Canonical Wnt ◽  
Wnt Signal

Aberrant Wnt signal transduction is involved in many human diseases such as cancer and neurodegenerative disorders. The key effector protein of the canonical Wnt pathway is β-catenin, which functions with T-cell factor/lymphoid enhancer factor (TCF/LEF) to activate gene transcription that leads to expression of Wnt target genes. In this study we provide results obtained from a novel functional screen of a human brain cDNA library used to identify 63 genes that are putative negative Wnt regulators. These genes were divided into eight functional groups that include known canonical and noncanonical Wnt pathway components and genes that had not yet been assigned to the Wnt pathway. One of the groups, the presenilin-binding proteins, contains the modifier of cell adhesion (MOCA) gene. We show that MOCA is a novel inhibitor of Wnt/β-catenin signaling. MOCA forms a complex with β-catenin and inhibits transcription of known Wnt target genes. Epistasis experiments indicate that MOCA acts to reduce the levels of nuclear β-catenin, increase the levels of membrane-bound β-catenin, and enhances cell–cell adhesion. Therefore, our data indicate that MOCA is a novel Wnt negative regulator and demonstrate that this screening approach can be a rapid means for isolation of new Wnt regulators.

Programmed cell death and the control of cell survival: lessons from the nervous system

Science ◽  
1993 ◽  
Vol 262 (5134) ◽  
pp. 695-700 ◽  
Author(s):  
M. Raff ◽  
B. Barres ◽  
J. Burne ◽  
H. Coles ◽  
Y Ishizaki ◽  
...  
Keyword(s):  
Cell Death ◽  
Nervous System ◽  
Programmed Cell Death ◽  
Cell Survival

Mast cell adhesion induces cytoskeletal modifications and programmed cell death in oligodendrocytes

2010 ◽  
Vol 218 (1-2) ◽  
pp. 57-66 ◽  
Author(s):  
Nevenka Medic ◽  
Paola Lorenzon ◽  
Francesca Vita ◽  
Elisa Trevisan ◽  
Anna Marchioli ◽  
...  
Keyword(s):  
Cell Death ◽  
Mast Cell ◽  
Cell Adhesion ◽  
Programmed Cell Death

scholarly journals A novel microRNA located in the TrkC gene regulates the Wnt signaling pathway and is differentially expressed in colorectal cancer specimens

2017 ◽  
Vol 292 (18) ◽  
pp. 7566-7577 ◽  
Author(s):  
Sadat Dokanehiifard ◽  
Atena Yasari ◽  
Hadi Najafi ◽  
Meisam Jafarzadeh ◽  
Maryam Nikkhah ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Wnt Signaling ◽  
Cell Survival ◽  
Cell Lines ◽  
Wnt Pathway ◽  
Wnt Signaling Pathway ◽  
Sw480 Cell ◽  
Tumor Tissues ◽  
Diphenyltetrazolium Bromide ◽  
Colorectal Cancer Cell Lines

Tropomyosin receptor kinase C (TrkC) is involved in cell survival, apoptosis, differentiation, and tumorigenesis. TrkC diverse functions might be attributed to the hypothetical non-coding RNAs embedded within the gene. Using bioinformatics approaches, a novel microRNA named TrkC-miR2 was predicted within the TrkC gene capable of regulating the Wnt pathway. For experimental verification of this microRNA, the predicted TrkC-premir2 sequence was overexpressed in SW480 cells, which led to the detection of two mature TrkC-miR2 isomiRs, and their endogenous forms were detected in human cell lines as well. Later, an independent promoter was deduced for TrkC-miR2 after the treatment of HCT116 cells with 5-azacytidine, which resulted in differential expression of TrkC-miR2 and TrkC host gene. RT-quantitative PCR and luciferase assays indicated that the APC2 gene is targeted by TrkC-miR2, and Wnt signaling is up-regulated. Also, Wnt inhibition by using small molecules along with TrkC-miR2 overexpression and TOP/FOP flash assays confirmed the positive effect of TrkC-miR2 on the Wnt pathway. Consistently, TrkC-miR2 overexpression promoted SW480 cell survival, which was detected by flow cytometry, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays, and crystal violate analysis. RT-qPCR analysis revealed that TrkC-miR2 is significantly up-regulated (∼70 times) in colorectal tumor tissues compared with their normal pairs. Moreover, the TrkC-miR2 expression level discriminated grades of tumor malignancies, which was consistent with its endogenous levels in HCT116, HT29, and SW480 colorectal cancer cell lines. Finally, an opposite expression pattern was observed for TrkC-miR2 and the APC2 gene in colorectal cancer specimens. In conclusion, here we introduce TrkC-miR2 as a novel regulator of Wnt signaling, which might be a candidate oncogenic colorectal cancer biomarker.

Wnt Signaling Is Associated with Anti-Apoptosis in the Interaction Between Acute Myeloid Leukemia Cells and Stromal Cells

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1366-1366
Author(s):  
Yosuke Minami ◽  
Yosuke Niwa ◽  
Akihiro Abe ◽  
Fumihiko Hayakawa ◽  
Tomoki Naoe
Keyword(s):  
Bone Marrow ◽  
Cell Death ◽  
Wnt Signaling ◽  
Stromal Cells ◽  
Research Funding ◽  
Wnt Pathway ◽  
Wnt Signaling Pathway ◽  
Bone Marrow Stroma Cell ◽  
Marrow Stroma ◽  
Canonical Wnt

Abstract Abstract 1366 Recent studies have revealed that strength of the Wnt signaling pathway regulates normal hematopoiesis including hematopoietic stem cells, and aberrant activation of the pathway is involved in the development of several types of leukemias. In the bone marrow microenvironment, stromal cells are rich sources of cytokines and some secreted cytokines have been observed to block induction of cell death in myeloid leukemia cells exposed to chemotherapy. Here, we examined the role of the Wnt signaling pathway on cell-adhesion, proliferation and survival of the stroma-dependent human AML cell line, TRL-01 cells, which we previously established (Ninomiya, et al. Cancer Gen Cyto, 2006). TRL-01 cells were maintained in the co-culturing with the hTERT-transduced human bone marrow stroma cell line, HTS cells, and cell death of TRL-01 cells was induced after removal of HTS cells. Treatment with the Wnt-receptor competitor, secreted Frizzled related protein (sFRP)-1, or the Rho kinase inhibitor, Y29632 (previously reported as an inhibitor of the non-canonical Wnt downstream pathway), but not with the specific inhibitor of the canonical Wnt pathway (DKK-1) induced apoptosis in dose-dependent manners in TRL-01 cells co-cultured with HTS cells. These results suggested that the non-canonical pathway of Wnt signaling might regulate survival of TRL-01 on the stromal cells. Next, we comprehensively investigated transcripts of the Wnt pathway components (10 Frizzleds, 2 LRPs, and 18 Wnts) in TRL-01 cells and HTS cells using RT-PCR. Transcripts of Wnt5A and Wnt9A were expressed in TRL-01 cells, but not in HTS cells. Moreover, the cell death of TRL-01 cells after removal of HTS cells was partially prevented by additional treatment with Wnt5A or Wnt9A not by other Wnt molecules such as Wnt5B. On the other hand, treatment with Wnt3A induced activated nuclear beta-catenin using Western-blotting, however, did not contribute to the survival of TRL-01 cells without the stromal co-culturing. Moreover, we are investigating regulation of the anti-apoptotic downstream pathway molecules in TRL-01 cells as well as effects of other inhibitors targeted for the Wnt signaling. We are also examining expressions of Wnt pathway components in primary AML bone marrow cells and other human bone marrow stroma cell lines such as HS-5 cells. These results imply association of Wnt5A and Wnt9A with anti-apoptosis in the interaction between AML cells and stromal cells, and a possible therapeutic target of AML for overcoming the resistance to chemotherapy in the bone marrow microenvironment. Disclosures: Naoe: Chugai Pharma: Research Funding; Novartis Pharma: Research Funding; Kyowa-Hakko Kirin: Research Funding.

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