Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Caenorhabditis elegans (29)
- MicroRNAs (19)
- Caenorhabditis elegans Proteins (9)
- Gene Expression Regulation, Developmental (8)
- RNA, Helminth (5)
-
- Mutation (4)
- RNA, Messenger (4)
- Transcription Factors (4)
- Carrier Proteins (3)
- Cell Cycle (3)
- DNA-Binding Proteins (3)
- Drosophila melanogaster (3)
- Nuclear Proteins (3)
- *Genes, Helminth (2)
- Gene Regulatory Networks (2)
- RNA-Induced Silencing Complex (2)
- Signal Transduction (2)
- *Gene Expression Regulation, Developmental (1)
- *Phenotype (1)
- Cell Differentiation (1)
- Coronary Artery Disease (1)
- Drosophila Proteins (1)
- Gene Deletion (1)
- Gene Expression (1)
- Gene Expression Profiling (1)
- Genetics (1)
- Genome-Wide Association Study (1)
- Insulin (1)
- Metamorphosis, Biological (1)
- Models, Biological (1)
Articles 1 - 30 of 40
Full-Text Articles in Entire DC Network
The Decapping Scavenger Enzyme Dcs-1 Controls Microrna Levels In Caenorhabditis Elegans, Gabriel Bosse, Stefan Ruegger, Maria Ow, Alejandro Vasquez-Rifo, Evelyne Rondeau, Victor Ambros, Helge Grosshans, Martin Simard
The Decapping Scavenger Enzyme Dcs-1 Controls Microrna Levels In Caenorhabditis Elegans, Gabriel Bosse, Stefan Ruegger, Maria Ow, Alejandro Vasquez-Rifo, Evelyne Rondeau, Victor Ambros, Helge Grosshans, Martin Simard
Victor R. Ambros
In metazoans, microRNAs play a critical role in the posttranscriptional regulation of genes required for cell proliferation and differentiation. MicroRNAs themselves are regulated by a multitude of mechanisms influencing their transcription and posttranscriptional maturation. However, there is only sparse knowledge on pathways regulating the mature, functional form of microRNA. Here, we uncover the implication of the decapping scavenger protein DCS-1 in the control of microRNA turnover. In Caenorhabditis elegans, mutations in dcs-1 increase the levels of functional microRNAs. We demonstrate that DCS-1 interacts with the exonuclease XRN-1 to promote microRNA degradation in an independent manner from its known decapping scavenger …
Developmental Decline In Neuronal Regeneration By The Progressive Change Of Two Intrinsic Timers, Yan Zou, Hui Chiu, Anna Zinovyeva, Victor Ambros, Chiou-Fen Chuang, Chieh Chang
Developmental Decline In Neuronal Regeneration By The Progressive Change Of Two Intrinsic Timers, Yan Zou, Hui Chiu, Anna Zinovyeva, Victor Ambros, Chiou-Fen Chuang, Chieh Chang
Victor R. Ambros
Like mammalian neurons, Caenorhabditis elegans neurons lose axon regeneration ability as they age, but it is not known why. Here, we report that let-7 contributes to a developmental decline in anterior ventral microtubule (AVM) axon regeneration. In older AVM axons, let-7 inhibits regeneration by down-regulating LIN-41, an important AVM axon regeneration-promoting factor. Whereas let-7 inhibits lin-41 expression in older neurons through the lin-41 3' untranslated region, lin-41 inhibits let-7 expression in younger neurons through Argonaute ALG-1. This reciprocal inhibition ensures that axon regeneration is inhibited only in older neurons. These findings show that a let-7-lin-41 regulatory circuit, which was previously …
The Developmental Timing Regulator Hbl-1 Modulates The Dauer Formation Decision In Caenorhabditis Elegans, Xantha Karp, Victor Ambros
The Developmental Timing Regulator Hbl-1 Modulates The Dauer Formation Decision In Caenorhabditis Elegans, Xantha Karp, Victor Ambros
Victor R. Ambros
Animals developing in the wild encounter a range of environmental conditions, and so developmental mechanisms have evolved that can accommodate different environmental contingencies. Harsh environmental conditions cause Caenorhabditis elegans larvae to arrest as stress-resistant "dauer" larvae after the second larval stage (L2), thereby indefinitely postponing L3 cell fates. HBL-1 is a key transcriptional regulator of L2 vs. L3 cell fate. Through the analysis of genetic interactions between mutations of hbl-1 and of genes encoding regulators of dauer larva formation, we find that hbl-1 can also modulate the dauer formation decision in a complex manner. We propose that dynamic interactions between …
Circulating Micrornas In Cardiovascular Disease, David Mcmanus, Victor Ambros
Circulating Micrornas In Cardiovascular Disease, David Mcmanus, Victor Ambros
Victor R. Ambros
Comment on: Transcoronary concentration gradients of circulating microRNAs. [Circulation. 2011]
Micrornas And Developmental Timing, Victor Ambros
Micrornas And Developmental Timing, Victor Ambros
Victor R. Ambros
MicroRNAs regulate temporal transitions in gene expression associated with cell fate progression and differentiation throughout animal development. Genetic analysis of developmental timing in the nematode Caenorhabditis elegans identified two evolutionarily conserved microRNAs, lin-4/mir-125 and let-7, that regulate cell fate progression and differentiation in C. elegans cell lineages. MicroRNAs perform analogous developmental timing functions in other animals, including mammals. By regulating cell fate choices and transitions between pluripotency and differentiation, microRNAs help to orchestrate developmental events throughout the developing animal, and to play tissue homeostasis roles important for disease, including cancer.
Dauer Larva Quiescence Alters The Circuitry Of Microrna Pathways Regulating Cell Fate Progression In C. Elegans, Xantha Karp, Victor Ambros
Dauer Larva Quiescence Alters The Circuitry Of Microrna Pathways Regulating Cell Fate Progression In C. Elegans, Xantha Karp, Victor Ambros
Victor R. Ambros
In C. elegans larvae, the execution of stage-specific developmental events is controlled by heterochronic genes, which include those encoding a set of transcription factors and the microRNAs that regulate the timing of their expression. Under adverse environmental conditions, developing larvae enter a stress-resistant, quiescent stage called 'dauer'. Dauer larvae are characterized by the arrest of all progenitor cell lineages at a stage equivalent to the end of the second larval stage (L2). If dauer larvae encounter conditions favorable for resumption of reproductive growth, they recover and complete development normally, indicating that post-dauer larvae possess mechanisms to accommodate an indefinite period …
Mirwip: Microrna Target Prediction Based On Microrna-Containing Ribonucleoprotein-Enriched Transcripts, Molly Hammell, Dang Long, Liang Zhang, Andrew Lee, C. Steven Carmack, Min Han, Ye Ding, Victor Ambros
Mirwip: Microrna Target Prediction Based On Microrna-Containing Ribonucleoprotein-Enriched Transcripts, Molly Hammell, Dang Long, Liang Zhang, Andrew Lee, C. Steven Carmack, Min Han, Ye Ding, Victor Ambros
Victor R. Ambros
Target prediction for animal microRNAs (miRNAs) has been hindered by the small number of verified targets available to evaluate the accuracy of predicted miRNA-target interactions. Recently, a dataset of 3,404 miRNA-associated mRNA transcripts was identified by immunoprecipitation of the RNA-induced silencing complex components AIN-1 and AIN-2. Our analysis of this AIN-IP dataset revealed enrichment for defining characteristics of functional miRNA-target interactions, including structural accessibility of target sequences, total free energy of miRNA-target hybridization and topology of base-pairing to the 5' seed region of the miRNA. We used these enriched characteristics as the basis for a quantitative miRNA target prediction method, …
Systematic Analysis Of Dynamic Mirna-Target Interactions During C. Elegans Development, Liang Zhang, Molly Hammell, Brian Kudlow, Victor Ambros, Min Han
Systematic Analysis Of Dynamic Mirna-Target Interactions During C. Elegans Development, Liang Zhang, Molly Hammell, Brian Kudlow, Victor Ambros, Min Han
Victor R. Ambros
Although microRNA (miRNA)-mediated functions have been implicated in many aspects of animal development, the majority of miRNA::mRNA regulatory interactions remain to be characterized experimentally. We used an AIN/GW182 protein immunoprecipitation approach to systematically analyze miRNA::mRNA interactions during C. elegans development. We characterized the composition of miRNAs in functional miRNA-induced silencing complexes (miRISCs) at each developmental stage and identified three sets of miRNAs with distinct stage-specificity of function. We then identified thousands of miRNA targets in each developmental stage, including a significant portion that is subject to differential miRNA regulation during development. By identifying thousands of miRNA family-mRNA pairs with temporally …
Immunopurification Of Ago1 Mirnps Selects For A Distinct Class Of Microrna Targets, Xin Hong, Molly Hammell, Victor Ambros, Stephen Cohen
Immunopurification Of Ago1 Mirnps Selects For A Distinct Class Of Microrna Targets, Xin Hong, Molly Hammell, Victor Ambros, Stephen Cohen
Victor R. Ambros
microRNAs comprise a few percent of animal genes and have been recognized as important regulators of a diverse range of biological processes. Understanding the biological functions of miRNAs requires effective means to identify their targets. Combined efforts from computational prediction, miRNA over-expression or depletion, and biochemical purification have identified thousands of potential miRNA-target pairs in cells and organisms. Complementarity to the miRNA seed sequence appears to be a common principle in target recognition. Other features, including miRNA-target duplex stability, binding site accessibility, and local UTR structure might affect target recognition. Yet computational approaches using such contextual features have yielded largely …
Micrornas: Genetically Sensitized Worms Reveal New Secrets, Victor Ambros
Micrornas: Genetically Sensitized Worms Reveal New Secrets, Victor Ambros
Victor R. Ambros
Why do many microRNA gene mutants display no evident phenotype? Multiply mutant worms that are selectively impaired in genetic regulatory network activities have been used to uncover previously unknown functions for numerous Caenorhabditis elegans microRNAs.
The Regulation Of Genes And Genomes By Small Rnas., Victor Ambros, Xuemei Chen
The Regulation Of Genes And Genomes By Small Rnas., Victor Ambros, Xuemei Chen
Victor R. Ambros
A recent Keystone Symposium on 'MicroRNAs and siRNAs: Biological Functions and Mechanisms' was organized by David Bartel and Shiv Grewal (and was held in conjunction with 'RNAi for Target Validation and as a Therapeutic', organized by Stephen Friend and John Maraganore). The 'MicroRNAs and siRNAs' meeting brought together scientists working on diverse biological aspects of small regulatory RNAs, including microRNAs, small interfering RNAs (siRNAs) and Piwi-interacting RNAs (piRNAs and rasiRNAs). Among the themes discussed were the diversity of small regulatory RNAs and their developmental functions, their biogenesis, the identification of their regulatory targets, their mechanisms of action, and their roles …
Characterization Of Microrna Expression Levels And Their Biological Correlates In Human Cancer Cell Lines., Caifu Chen, Arti Gaur, David Jewell, Yu Liang, Dana Ridzon, Jason Moore, Victor Ambros, Mark Israel
Characterization Of Microrna Expression Levels And Their Biological Correlates In Human Cancer Cell Lines., Caifu Chen, Arti Gaur, David Jewell, Yu Liang, Dana Ridzon, Jason Moore, Victor Ambros, Mark Israel
Victor R. Ambros
MicroRNAs are small noncoding RNAs that function by regulating target gene expression posttranscriptionally. They play a critical role in developmental and physiologic processes and are implicated in the pathogenesis of several human diseases including cancer. We examined the expression profiles of 241 human microRNAs in normal tissues and the NCI-60 panel of human tumor-derived cell lines. To quantify microRNA expression, we employed a highly sensitive technique that uses stem-loop primers for reverse transcription followed by real-time PCR. Most microRNAs were expressed at lower levels in tumor-derived cell lines compared with the corresponding normal tissue. Agglomerative hierarchical clustering analysis of microRNA …
The 2007 George W. Beadle Medal. Robert K. Herman., Victor Ambros
The 2007 George W. Beadle Medal. Robert K. Herman., Victor Ambros
Victor R. Ambros
No abstract provided.
Developmental Biology. Encountering Micrornas In Cell Fate Signaling., Xantha Karp, Victor Ambros
Developmental Biology. Encountering Micrornas In Cell Fate Signaling., Xantha Karp, Victor Ambros
Victor R. Ambros
Comment on: LIN-12/Notch activation leads to microRNA-mediated down-regulation of Vav in C. elegans. [Science. 2005]
The Functions Of Animal Micrornas., Victor Ambros
The Functions Of Animal Micrornas., Victor Ambros
Victor R. Ambros
MicroRNAs (miRNAs) are small RNAs that regulate the expression of complementary messenger RNAs. Hundreds of miRNA genes have been found in diverse animals, and many of these are phylogenetically conserved. With miRNA roles identified in developmental timing, cell death, cell proliferation, haematopoiesis and patterning of the nervous system, evidence is mounting that animal miRNAs are more numerous, and their regulatory impact more pervasive, than was previously suspected.
A Short History Of A Short Rna, Victor Ambros, Rosalind Lee, Rhonda Feinbaum
A Short History Of A Short Rna, Victor Ambros, Rosalind Lee, Rhonda Feinbaum
Victor R. Ambros
Comment on: The C. elegans heterochronic gene lin-4 encodes small RNAs with antisense complementarity to lin-14. [Cell. 1993]
Identification Of Micrornas And Other Tiny Noncoding Rnas By Cdna Cloning, Victor Ambros, Rosalind Lee
Identification Of Micrornas And Other Tiny Noncoding Rnas By Cdna Cloning, Victor Ambros, Rosalind Lee
Victor R. Ambros
MicroRNAs (miRNAs) and other small RNAs can be identified by cloning and sequencing cDNAs prepared from the ∼22-nt fraction of total RNA. Methods are described for the construction of cDNA libraries from small noncoding RNAs through the use of T4 RNA ligase, reverse transcriptase, and polymerase chain reaction. cDNAs are cloned in λ or plasmid vectors, and the sequences are compared to annotated genomic sequence databases, and analyzed by RNA folding programs to distinguish miRNA sequences from other small RNAs of similar size. Northern blot hybridization is used to confirm the expression of small RNAs in vivo.
Role Of Micrornas In Plant And Animal Development, Victor Ambros, James Carrington
Role Of Micrornas In Plant And Animal Development, Victor Ambros, James Carrington
Victor R. Ambros
Small RNAs, including microRNAs (miRNAs) and short interfering RNAs (siRNAs), are key components of an evolutionarily conserved system of RNA-based gene regulation in eukaryotes. They are involved in many molecular interactions, including defense against viruses and regulation of gene expression during development. miRNAs interfere with expression of messenger RNAs encoding factors that control developmental timing, stem cell maintenance, and other developmental and physiological processes in plants and animals. miRNAs are negative regulators that function as specificity determinants, or guides, within complexes that inhibit protein synthesis (animals) or promote degradation (plants) of mRNA targets.
Microrna Pathways In Flies And Worms: Growth, Death, Fat, Stress, And Timing, Victor Ambros
Microrna Pathways In Flies And Worms: Growth, Death, Fat, Stress, And Timing, Victor Ambros
Victor R. Ambros
Drosophila geneticists have uncovered roles for microRNAs in the coordination of cell proliferation and cell death during development, and in stress resistance and fat metabolism. In C. elegans, a homolog of the well-known fly developmental regulator hunchback acts downstream of the microRNAs lin-4 and let-7 in a pathway controlling developmental timing.
Micrornas And Other Tiny Endogenous Rnas In C. Elegans, Victor Ambros, Rosalind Lee, Ann Lavanway, Peter Williams, David Jewell
Micrornas And Other Tiny Endogenous Rnas In C. Elegans, Victor Ambros, Rosalind Lee, Ann Lavanway, Peter Williams, David Jewell
Victor R. Ambros
BACKGROUND: MicroRNAs (miRNAs) are small noncoding RNAs that are processed from hairpin precursor transcripts by Dicer. miRNAs probably inhibit translation of mRNAs via imprecise antisense base-pairing. Small interfering RNAs (siRNAs) are similar in size to miRNAs, but they recognize targets by precise complementarity and elicit RNA-mediated interference (RNAi). We employed cDNA sequencing and comparative genomics to identify additional C. elegans small RNAs with properties similar to miRNAs and siRNAs. RESULTS: We found three broad classes of small RNAs in C. elegans: (1) 21 new miRNA genes (we estimate that C. elegans contains approximately 100 distinct miRNA genes, about 30% of …
The Expression Of The Let-7 Small Regulatory Rna Is Controlled By Ecdysone During Metamorphosis In Drosophila Melanogaster, Lorenzo Sempere, Edward Dubrovsky, Veronica Dubrovskaya, Edward Berger, Victor Ambros
The Expression Of The Let-7 Small Regulatory Rna Is Controlled By Ecdysone During Metamorphosis In Drosophila Melanogaster, Lorenzo Sempere, Edward Dubrovsky, Veronica Dubrovskaya, Edward Berger, Victor Ambros
Victor R. Ambros
In Caenorhabditis elegans, the heterochronic pathway controls the timing of developmental events during the larval stages. A component of this pathway, the let-7 small regulatory RNA, is expressed at the late stages of development and promotes the transition from larval to adult (L/A) stages. The stage-specificity of let-7 expression, which is crucial for the proper timing of the worm L/A transition, is conserved in Drosophila melanogaster and other invertebrates. In Drosophila, pulses of the steroid hormone 20-hydroxyecdysone (ecdysone) control the timing of the transition from larval to pupal to adult stages. To test whether let-7 expression is regulated by ecdysone …
Micrornas: Tiny Regulators With Great Potential, Victor Ambros
Micrornas: Tiny Regulators With Great Potential, Victor Ambros
Victor R. Ambros
Animal genomes contain an abundance of small genes that produce regulatory RNAs of about 22 nucleotides in length. These microRNAs are diverse in sequence and expression patterns, and are evolutionarily widespread, suggesting that they may participate in a wide range of genetic regulatory pathways.
Development. Dicing Up Rnas, Victor Ambros
Development. Dicing Up Rnas, Victor Ambros
Victor R. Ambros
Comment on: A cellular function for the RNA-interference enzyme Dicer in the maturation of the let-7 small temporal RNA. [Science. 2001]
The Temporal Control Of Cell Cycle And Cell Fate In Caenorhabditis Elegans, Victor Ambros
The Temporal Control Of Cell Cycle And Cell Fate In Caenorhabditis Elegans, Victor Ambros
Victor R. Ambros
The nematode Caenorhabditis elegans develops through two major phases: the first phase, embryogenesis, consists of a rapid series of cleavage cell divisions leading to morphogenesis of a first stage larva. The second phase is postembryonic development, which consists of developmentally regulated cell cycles that occur during the four larval stages leading to the adult. Precursor cells set aside during embryogenesis divide through stereotypical cell lineage patterns during the four larval stages to generate larval and adult structures. The precise timing of the postembryonic cell divisions is under strict control, in most cases with a developmentally regulated G1. In certain postembryonic …
Control Of Developmental Timing In Caenorhabditis Elegans, Victor Ambros
Control Of Developmental Timing In Caenorhabditis Elegans, Victor Ambros
Victor R. Ambros
Studies of the nematode Caenorhabditis elegans have identified genetic and molecular mechanisms controlling temporal patterns of developmental events. Mutations in genes of the C. elegans heterochronic pathway cause altered temporal patterns of larval development, in which cells at certain larval stages execute cell division patterns or differentiation programs normally specific for other stages. The products of the heterochronic genes include transcriptional and translational regulators and two different cases of novel small translational regulatory RNAs. Other genes of the pathway encode evolutionarily conserved proteins, including a homolog of the Drosophila Period circadian timing regulator, and a member of the nuclear receptor …
The Lin-41 Rbcc Gene Acts In The C. Elegans Heterochronic Pathway Between The Let-7 Regulatory Rna And The Lin-29 Transcription Factor, Frank Slack, Michael Basson, Zhongchi Liu, Victor Ambros, H. Horvitz, Gary Ruvkun
The Lin-41 Rbcc Gene Acts In The C. Elegans Heterochronic Pathway Between The Let-7 Regulatory Rna And The Lin-29 Transcription Factor, Frank Slack, Michael Basson, Zhongchi Liu, Victor Ambros, H. Horvitz, Gary Ruvkun
Victor R. Ambros
Null mutations in the C. elegans heterochronic gene lin-41 cause precocious expression of adult fates at larval stages. Increased lin-41 activity causes the opposite phenotype, reiteration of larval fates. let-7 mutations cause similar reiterated heterochronic phenotypes that are suppressed by lin-41 mutations, showing that lin-41 is negatively regulated by let-7. lin-41 negatively regulates the timing of LIN-29 adult specification transcription factor expression. lin-41 encodes an RBCC protein, and two elements in the lin-413'UTR are complementary to the 21 nucleotide let-7 regulatory RNA. A lin-41::GFP fusion gene is downregulated in the tissues affected by lin-41 at the time that the let-7 …
The Lin-4 Regulatory Rna Controls Developmental Timing In Caenorhabditis Elegans By Blocking Lin-14 Protein Synthesis After The Initiation Of Translation, Philip Olsen, Victor Ambros
The Lin-4 Regulatory Rna Controls Developmental Timing In Caenorhabditis Elegans By Blocking Lin-14 Protein Synthesis After The Initiation Of Translation, Philip Olsen, Victor Ambros
Victor R. Ambros
lin-4 encodes a small RNA that is complementary to sequences in the 3' untranslated region (UTR) of lin-14 mRNA and that acts to developmentally repress the accumulation of LIN-14 protein. This repression is essential for the proper timing of numerous events of Caenorhabditis elegans larval development. We have investigated the mechanism of lin-4 RNA action by examining the fate of lin-14 mRNA in vivo during the time that lin-4 RNA is expressed. Our results indicate that the rate of synthesis of lin-14 mRNA, its state of polyadenylation, its abundance in the cytoplasmic fraction, and its polysomal sedimentation profile do not …
The Timing Oflin-4rna Accumulation Controls The Timing Of Postembryonic Developmental Events Incaenorhabditis Elegans, Rhonda Feinbaum, Victor Ambros
The Timing Oflin-4rna Accumulation Controls The Timing Of Postembryonic Developmental Events Incaenorhabditis Elegans, Rhonda Feinbaum, Victor Ambros
Victor R. Ambros
The lin-4 gene encodes a small RNA that is required to translationally repress lin-14 toward the end of the first larval stage of Caenorhabditis elegans development. To determine if the timing of LIN-14 protein down-regulation depends on the temporal profile of lin-4 RNA level, we analyzed the stage-specificity of lin-4 RNA expression during wild-type development and examined the phenotypes of transgenic worms that overexpress lin-4 RNA during the first larval stage. We found that lin-4 RNA first becomes detectable at approximately 12 h of wild-type larval development and rapidly accumulates to nearly maximum levels by 16 h. This profile of …
Cell Cycle-Dependent Sequencing Of Cell Fate Decisions In Caenorhabditis Elegans Vulva Precursor Cells, Victor Ambros
Cell Cycle-Dependent Sequencing Of Cell Fate Decisions In Caenorhabditis Elegans Vulva Precursor Cells, Victor Ambros
Victor R. Ambros
In Caenorhabditis elegans, the fates of the six multipotent vulva precursor cells (VPCs) are specified by extracellular signals. One VPC expresses the primary (1 degrees ) fate in response to a Ras-mediated inductive signal from the gonad. The two VPCs flanking the 1 degrees cell each express secondary (2 degrees ) fates in response to lin-12-mediated lateral signaling. The remaining three VPCs each adopt the non-vulval tertiary (3 degrees ) fate. Here I describe experiments examining how the selection of these vulval fates is affected by cell cycle arrest and cell cycle-restricted lin-12 activity. The results suggest that lin-12 participates …
Heterochronic Genes, Victor Ambros
Heterochronic Genes, Victor Ambros
Victor R. Ambros
This chapter focuses on our current understanding of the C. elegans heterochronic gene pathway as determined by genetic characterization of the regulatory interactions among the genes (Ambros and Horvitz 1987; Ambros 1989; Liu and Ambros 1989) and recent progress on the cloning, sequencing, and molecular analysis of genes involved in this pathway (Ruvkun et al. 1989; Arasu et al. 1991; Papp et al. 1991; Wightman et al. 1991; Lee et al. 1993; Rougvie and Ambros 1995; E. Moss et al., in prep). Primary emphasis is placed on the developmental decisions controlled by the heterochronic genes, the regulatory interactions among genes …