Ectopic expression of activated Ras1 induces hyperplastic growth and increased cell death in Drosophila imaginal tissues

Development ◽  
1998 ◽  
Vol 125 (1) ◽  
pp. 1-9 ◽  
Author(s):  
F.D. Karim ◽  
G.M. Rubin
Keyword(s):  
Cell Proliferation ◽  
Cell Death ◽  
Cell Fate ◽  
Ectopic Expression ◽  
Tissue Growth ◽  
Mapk Cascade ◽  
Loss Of Function ◽  
Direct Role ◽  
Genes Encoding ◽  
Hyperplastic Tissue

The Drosophila Ras1 gene is required for proper cell fate specification throughout development, and the loss-of-function phenotype of Ras1 suggests an additional role in cell proliferation or survival. A direct role for RAS1 in promoting cell proliferation, however, has not been established. We show that expression of an activated form of RAS1 (RAS1V12) during Drosophila imaginal disc development is sufficient to drive ectopic cell proliferation and hyperplastic tissue growth. In addition, expression of RAS1V12 induces widespread cell death in the imaginal discs, including cells not expressing the transgene, which results in ablation of adult structures. Loss-of-function mutations in the genes encoding RAF, MEK, MAPK and KSR dominantly suppress RAS1V12-induced cell proliferation. Furthermore, two RAS effector loop mutations (E37G and Y40C) that block the RAS-RAF interaction, also suppress RAS1V12-induced proliferation, consistent with a requirement for the MAPK cascade during the RAS1 mitogenic response. These two RAS effector loop mutants, however, retain some activity and can act synergistically with a MAPK gain-of-function mutation, suggesting that RAS1 may also act through signaling pathway(s) distinct from the MAPK cascade.

The Serrate locus of Drosophila and its role in morphogenesis of the wing imaginal discs: control of cell proliferation

Development ◽  
1994 ◽  
Vol 120 (3) ◽  
pp. 535-544 ◽  
Author(s):  
S.A. Speicher ◽  
U. Thomas ◽  
U. Hinz ◽  
E. Knust
Keyword(s):  
Cell Proliferation ◽  
Transmembrane Protein ◽  
Ectopic Expression ◽  
Imaginal Discs ◽  
Specific Cell ◽  
Loss Of Function ◽  
Severe Reduction ◽  
Homozygous Mutant ◽  
Wing Imaginal Discs ◽  
Larval Lethality

The Drosophila gene Serrate encodes a transmembrane protein with 14 EGF-like repeats in its extracellular domain. Here we show that loss-of-function mutations in this gene lead to larval lethality. Homozygous mutant larvae fail to differentiate the anterior spiracles, exhibit poorly developed mouth-hooks and show a severe reduction in the size of the wing and haltere primordia, which is not due to cell death. The few homozygous mutant escapers that pupariate develop into pharate adults that almost completely lack wings and halteres. Clonal analysis in the adult epidermis demonstrates a requirement for Serrate during wing and haltere development. Targeted ectopic expression of Serrate in the imaginal discs using the yeast transcriptional activator Gal4 results in regionally restricted induction of cell proliferation, e.g. the ventral tissues in the case of the wings and halteres. The results suggest that the wild-type function of Serrate is required for the control of position-specific cell proliferation during development of meso- and metathoracic dorsal discs, which in turn exerts a direct effect on morphogenesis.

scholarly journals Loss offlflTriggers JNK-Dependent Cell Death inDrosophila

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Jiuhong Huang ◽  
Lei Xue
Keyword(s):  
Cell Death ◽  
Function Analysis ◽  
Ectopic Expression ◽  
Negative Regulator ◽  
Loss Of Function ◽  
Jnk Pathway ◽  
Dependent Cell ◽  
Jnk Activation ◽  
First Time

falafel(flfl) encodes aDrosophilahomolog of human SMEK whosein vivofunctions remain elusive. In this study, we performed gain-of-function and loss-of-function analysis inDrosophilaand identified flfl as a negative regulator of JNK pathway-mediated cell death. While ectopic expression offlflsuppresses TNF-triggered JNK-dependent cell death, loss offlflpromotes JNK activation and cell death in the developing eye and wing. These data report for the first time an essential physiological function offlflin maintaining tissue homeostasis and organ development. As the JNK signaling pathway has been evolutionary conserved from fly to human, a similar role of PP4R3 in JNK-mediated physiological process is speculated.

Proteases and caspase-like activity in the yeast Saccharomyces cerevisiae

2011 ◽  
Vol 39 (5) ◽  
pp. 1502-1508 ◽  
Author(s):  
Derek Wilkinson ◽  
Mark Ramsdale
Keyword(s):  
Cell Death ◽  
Cell Fate ◽  
Caspase 3 ◽  
Antifungal Drugs ◽  
Loss Of Function ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cell Death Response ◽  
Substrate Choice ◽  
Industrial Yeasts ◽  
Stimulation Of

A variety of proteases have been implicated in yeast PCD (programmed cell death) including the metacaspase Mca1 and the separase Esp1, the HtrA-like serine protease Nma111, the cathepsin-like serine carboxypeptideases and a range of vacuolar proteases. Proteasomal activity is also shown to have an important role in determining cell fate, with both pro- and anti-apoptotic roles. Caspase 3-, 6- and 8-like activities are detected upon stimulation of yeast PCD, but not all of this activity is associated with Mca1, implicating other proteases with caspase-like activity in the yeast cell death response. Global proteolytic events that accompany PCD are discussed alongside a consideration of the conservation of the death-related degradome (both at the level of substrate choice and cleavage site). The importance of both gain-of-function changes in the degradome as well as loss-of-function changes are highlighted. Better understanding of both death-related proteases and their substrates may facilitate the design of future antifungal drugs or the manipulation of industrial yeasts for commercial exploitation.

scholarly journals Epithelial cell-turnover ensures robust coordination of tissue growth in Drosophila ribosomal protein mutants

PLoS Genetics ◽  
2021 ◽  
Vol 17 (1) ◽  
pp. e1009300
Author(s):  
Nanami Akai ◽  
Shizue Ohsawa ◽  
Yukari Sando ◽  
Tatsushi Igaki
Keyword(s):  
Cell Proliferation ◽  
Cell Death ◽  
Ribosomal Protein ◽  
Developmental Delay ◽  
Developmental Process ◽  
Ribosomal Protein Gene ◽  
Developmental Time ◽  
Tissue Growth ◽  
Cell Turnover ◽  
Essentially Normal

Highly reproducible tissue development is achieved by robust, time-dependent coordination of cell proliferation and cell death. To study the mechanisms underlying robust tissue growth, we analyzed the developmental process of wing imaginal discs in Drosophila Minute mutants, a series of heterozygous mutants for a ribosomal protein gene. Minute animals show significant developmental delay during the larval period but develop into essentially normal flies, suggesting there exists a mechanism ensuring robust tissue growth during abnormally prolonged developmental time. Surprisingly, we found that both cell death and compensatory cell proliferation were dramatically increased in developing wing pouches of Minute animals. Blocking the cell-turnover by inhibiting cell death resulted in morphological defects, indicating the essential role of cell-turnover in Minute wing morphogenesis. Our analyses showed that Minute wing discs elevate Wg expression and JNK-mediated Dilp8 expression that causes developmental delay, both of which are necessary for the induction of cell-turnover. Furthermore, forced increase in Wg expression together with developmental delay caused by ecdysone depletion induced cell-turnover in the wing pouches of non-Minute animals. Our findings suggest a novel paradigm for robust coordination of tissue growth by cell-turnover, which is induced when developmental time axis is distorted.

Patterning of dopaminergic neurotransmitter identity among Caenorhabditis elegans ray sensory neurons by a TGFbeta family signaling pathway and a Hox gene

Development ◽  
1999 ◽  
Vol 126 (24) ◽  
pp. 5819-5831 ◽  
Author(s):  
R. Lints ◽  
S.W. Emmons
Keyword(s):  
Caenorhabditis Elegans ◽  
Heat Shock ◽  
Signaling Pathway ◽  
Cell Fate ◽  
Sensory Neurons ◽  
Ectopic Expression ◽  
Temperature Shift ◽  
Temperature Sensitive ◽  
Loss Of Function ◽  
Hox Gene

We have investigated the mechanism that patterns dopamine expression among Caenorhabditis elegans male ray sensory neurons. Dopamine is expressed by the A-type sensory neurons in three out of the nine pairs of rays. We used expression of a tyrosine hydroxylase reporter transgene as well as direct assays for dopamine to study the genetic requirements for adoption of the dopaminergic cell fate. In loss-of-function mutants affecting a TGFbeta family signaling pathway, the DBL-1 pathway, dopaminergic identity is adopted irregularly by a wider subset of the rays. Ectopic expression of the pathway ligand, DBL-1, from a heat-shock-driven transgene results in adoption of dopaminergic identity by rays 3–9; rays 1 and 2 are refractory. The rays are therefore prepatterned with respect to their competence to be induced by a DBL-1 pathway signal. Temperature-shift experiments with a temperature-sensitive type II receptor mutant, as well as heat-shock induction experiments, show that the DBL-1 pathway acts during an interval that extends from two to one cell generation before ray neurons are born and begin to differentiate. In a mutant of the AbdominalB class Hox gene egl-5, rays that normally express EGL-5 do not adopt dopaminergic fate and cannot be induced to express DA when DBL-1 is provided by a heat-shock-driven dbl-1 transgene. Therefore, egl-5 is required for making a subset of rays capable of adopting dopaminergic identity, while the function of the DBL-1 pathway signal is to pattern the realization of this capability.

Abstract 442: Epigenetic Regulation of Ezh2 in Direct Human Cardiac Reprogramming

2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Yang Zhou ◽  
Yawen Tang ◽  
Lianzhong Zhao ◽  
Rui Lu ◽  
Jianyi Zhang
Keyword(s):  
Cardiovascular Disease ◽  
Cell Fate ◽  
Epigenetic Regulation ◽  
Ectopic Expression ◽  
The United States ◽  
Inhibitory Effect ◽  
Loss Of Function ◽  
Lower Efficiency

Cardiovascular disease is still the leading cause of death in the United States. Due to the limited regenerative capacity of adult hearts, the damage caused by heart injury could not be reversed and often progressed into heart failure. In need of cardiovascular disease treatment, many therapies aimed at either cell transplantation or cell regeneration have been proposed. Direct reprogramming of somatic cells into induced cardiomyocytes (iCMs) is considered to be a promising strategy for regenerative medicine. The induction of cardiomyocytes from non-myocytes has been achieved efficiently via ectopic expression of reprogramming factors both in vitro and in vivo with mice models. However, as human cells are more resistant to the reprogramming process, the generation of human iCMs (hiCMs) has been restricted by the factor that using more complex cocktails generated only functionally immature cells with lower efficiency and longer conversion time. The inefficiency of hiCMs production called for the identification and elucidation of underlying species-specific regulatory mechanisms in human, and removal of the additional epigenetic barriers which might be damping the hiCMs reprogramming. Here, we identified a human-specific epigenetic barrier, Enhancer of zesta homolog 2 (EZH2), via an unbiased loss-of-function screening. With the knockdown of EZH2, the hiCM reprogramming efficiency was significantly increased, accompanied with profound repression of collagen and extracellular matrix genes, which are related to the formation of fibrosis. Consistently, Inhibition of EZH2 catalytic activity via small molecules promotes hiCM reprogramming, suggesting that EZH2’s inhibitory effect was mediated by epigenetic regulation of histone modifications. Therefore, our study revealed a previously unrecognized regulatory mechanism of human cardiac reprogramming, which allows us to overcome the fibroblast fate barriers and ease the cardiac cell fate conversion.

scholarly journals Lysophosphatidic acid receptor 6 regulated by miR-27a-3p attenuates tumor proliferation in breast cancer

2021 ◽  
Author(s):  
J. Lei ◽  
S. Guo ◽  
K. Li ◽  
J. Tian ◽  
B. Zong ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Proliferation ◽  
Lysophosphatidic Acid ◽  
Ectopic Expression ◽  
Disease Free Survival ◽  
Loss Of Function ◽  
Poor Overall Survival ◽  
Free Survival ◽  
Lpa Receptor

Abstract Purpose Lysophosphatidic acid (LPA) is a bioactive molecule which participates in many physical and pathological processes. Although LPA receptor 6 (LPAR6), the last identified LPA receptor, has been reported to have diverse effects in multiple cancers, including breast cancer, its effects and functioning mechanisms are not fully known. Methods Multiple public databases were used to investigate the mRNA expression of LPAR6, its prognostic value, and potential mechanisms in breast cancer. Western blotting was performed to validate the differential expression of LPAR6 in breast cancer tissues and their adjacent tissues. Furthermore, in vitro experiments were used to explore the effects of LPAR6 on breast cancer. Additionally, TargetScan and miRWalk were used to identify potential upstream regulating miRNAs and validated the relationship between miR-27a-3p and LPAR6 via real-time polymerase chain reaction and an in vitro rescue assay. Results LPAR6 was significantly downregulated in breast cancer at transcriptional and translational levels. Decreased LPAR6 expression in breast cancer is significantly correlated with poor overall survival, disease-free survival, and distal metastasis-free survival, particularly for hormone receptor-positive patients, regardless of lymph node metastatic status. In vitro gain and loss-of-function assays indicated that LPAR6 attenuated breast cancer cell proliferation. The analyses of TCGA and METABRIC datasets revealed that LPAR6 may regulate the cell cycle signal pathway. Furthermore, the expression of LPAR6 could be positively regulated by miR-27a-3p. The knockdown of miR-27a-3p increased cell proliferation, and ectopic expression of LPAR6 could partly rescue this phenotype. Conclusion LPAR6 acts as a tumor suppressor in breast cancer and is positively regulated by miR-27a-3p.

scholarly journals Co-expression patterns define epigenetic regulators associated with neurological dysfunction

2018 ◽  
Author(s):  
Leandros Boukas ◽  
James M. Havrilla ◽  
Aaron R. Quinlan ◽  
Hans T. Bjornsson ◽  
Kasper D. Hansen
Keyword(s):  
Expression Patterns ◽  
Neurological Dysfunction ◽  
Dual Function ◽  
Loss Of Function ◽  
Direct Role ◽  
Human Genes ◽  
Systematic Effort ◽  
Genes Encoding ◽  
Epigenetic Regulators ◽  
Coding Variants

AbstractCoding variants in genes encoding for epigenetic regulators are an emerging cause of neurological dysfunction and cancer. However, a systematic effort to identify disease candidates within the human epigenetic machinery (EM) has not been performed, and it is unclear whether features exist that distinguish between variation-intolerant and variation-tolerant EM genes, and between EM genes associated with neurological dysfunction versus cancer. Here, we rigorously define a set of 295 human genes with a direct role in epigenetic regulation (writers, erasers, remodelers, readers). Systematic exploration of these genes reveals that while individual enzymatic functions are always mutually exclusive, readers often also exhibit enzymatic activity as well (dual function EM genes). We find that the majority of EM genes are very intolerant to loss-of-function variation, even when compared to the dosage sensitive group of transcription factors. Using this strategy, we identify 103 novel EM disease candidates. We show that the intolerance to loss-of-function variation is driven by the protein domains encoding the epigenetic function, strongly suggesting that disease is caused by a perturbed chromatin state. Unexpectedly, we also describe a large subset of EM genes that are co-expressed within multiple tissues. This subset is almost exclusively populated by extremely variation-intolerant EM genes, and shows enrichment for dual function EM genes. It is also highly enriched for genes associated with neurological dysfunction, even when accounting for dosage sensitivity, but not for cancer-associated EM genes. These findings prioritize novel disease candidate EM genes, and suggest that the co-expression itself may play a functional role in normal neurological homeostasis.

scholarly journals miR-637 prevents glioblastoma progression by interrupting ZEB2/WNT/β-catenin cascades

2021 ◽  
Author(s):  
Wei Wang ◽  
Zilong Zhou ◽  
Shuai Han ◽  
Di Wu
Keyword(s):  
Phase Transition ◽  
Central Nervous System ◽  
Cell Proliferation ◽  
Ectopic Expression ◽  
S Phase ◽  
Signaling Cascades ◽  
Loss Of Function ◽  
The Central Nervous System ◽  
Canonical Wnt ◽  
Tumor Growth Suppression

Abstract Glioblastomas (GBMs) are the most frequent primary malignancies in the central nervous system. Aberrant activation of WNT/β-catenin signaling pathways is critical for GBM malignancy. However, the regulation of WNT/β-catenin signaling cascades remains unclear. Presently, we observed the increased expression of ZEB2 and decreased expression of miR-637 in GBM. The expression of miR-637 was negatively correlated with expression of ZEB2. miR-637 overexpression overcame the ZEB2-enhanced cell proliferation and G1/S phase transition. In addition, miR-637 suppressed canonical WNT/β-catenin pathways by targeting WNT7A directly. Gain- and loss-of-function experiments in U251 mice demonstrated that miR-637 inhibited cell proliferation and arrested the G1/S phase transition, leading to tumor growth suppression. The collective findings suggest that ZEB2 and WNT/β-catenin cascades merge at miR-637 and the ectopic expression of miR-637 disturbs ZEB2/WNT/β-Catenin-mediated GBM growth. The findings should inform improved β-catenin-targeted therapy against GBM.

Sign in / Sign up

Export Citation Format

Share Document