Open Access. Powered by Scholars. Published by Universities.®
- Discipline
- Publication Year
- Publication
- File Type
Articles 1 - 30 of 52
Full-Text Articles in Genetics and Genomics
Rna Recognition By The Caenorhabditis Elegans Oocyte Maturation Determinant Oma-1, Ebru Kaymak, Sean Ryder
Rna Recognition By The Caenorhabditis Elegans Oocyte Maturation Determinant Oma-1, Ebru Kaymak, Sean Ryder
Sean P. Ryder
Maternally supplied mRNAs encode proteins that pattern early embryos in many species. In the nematode Caenorhabditis elegans, a suite of RNA-binding proteins regulates expression of maternal mRNAs during oogenesis, the oocyte to embryo transition, and early embryogenesis. To understand how these RNA-binding proteins contribute to development, it is necessary to determine how they select specific mRNA targets for regulation. OMA-1 and OMA-2 are redundant proteins required for oocyte maturation--an essential part of meiosis that prepares oocytes for fertilization. Both proteins have CCCH type tandem zinc finger RNA-binding domains. Here, we define the RNA binding specificity of OMA-1 and demonstrate that …
Caenorhabditis Elegans Alg-1 Antimorphic Mutations Uncover Functions For Argonaute In Microrna Guide Strand Selection And Passenger Strand Disposal, Anna Y. Zinovyeva, Isana Veksler-Lublinsky, Ajay A. Vashisht, James A. Wohlschlegel, Victor R. Ambros
Caenorhabditis Elegans Alg-1 Antimorphic Mutations Uncover Functions For Argonaute In Microrna Guide Strand Selection And Passenger Strand Disposal, Anna Y. Zinovyeva, Isana Veksler-Lublinsky, Ajay A. Vashisht, James A. Wohlschlegel, Victor R. Ambros
Victor R. Ambros
MicroRNAs are regulators of gene expression whose functions are critical for normal development and physiology. We have previously characterized mutations in a Caenorhabditis elegans microRNA-specific Argonaute ALG-1 (Argonaute-like gene) that are antimorphic [alg-1(anti)]. alg-1(anti) mutants have dramatically stronger microRNA-related phenotypes than animals with a complete loss of ALG-1. ALG-1(anti) miRISC (microRNA induced silencing complex) fails to undergo a functional transition from microRNA processing to target repression. To better understand this transition, we characterized the small RNA and protein populations associated with ALG-1(anti) complexes in vivo. We extensively characterized proteins associated with wild-type and mutant ALG-1 and found that the mutant …
Robust Distal Tip Cell Pathfinding In The Face Of Temperature Stress Is Ensured By Two Conserved Micrornas In Caenorhabditis Elegans, Samantha L. Burke, Molly Hammell, Victor R. Ambros
Robust Distal Tip Cell Pathfinding In The Face Of Temperature Stress Is Ensured By Two Conserved Micrornas In Caenorhabditis Elegans, Samantha L. Burke, Molly Hammell, Victor R. Ambros
Victor R. Ambros
Biological robustness, the ability of an organism to maintain a steady-state output as genetic or environmental inputs change, is critical for proper development. MicroRNAs have been implicated in biological robustness mechanisms through their post-transcriptional regulation of genes and gene networks. Previous research has illustrated examples of microRNAs promoting robustness as part of feedback loops and genetic switches and by buffering noisy gene expression resulting from environmental and/or internal changes. Here we show that the evolutionarily conserved microRNAs mir-34 and mir-83 (homolog of mammalian mir-29) contribute to the robust migration pattern of the distal tip cells in Caenorhabditis elegans by specifically …
Inhibiting Mirna In Caenorhabditis Elegans Using A Potent And Selective Antisense Reagent, Genhua Zheng, Victor R. Ambros, Wen-Hong Li
Inhibiting Mirna In Caenorhabditis Elegans Using A Potent And Selective Antisense Reagent, Genhua Zheng, Victor R. Ambros, Wen-Hong Li
Victor R. Ambros
BACKGROUND: Antisense reagents can serve as efficient and versatile tools for studying gene function by inhibiting nucleic acids in vivo. Antisense reagents have particular utility for the experimental manipulation of the activity of microRNAs (miRNAs), which are involved in the regulation of diverse developmental and physiological pathways in animals. Even in traditional genetic systems, such as the nematode Caenorhabditis elegans, antisense reagents can provide experimental strategies complementary to mutational approaches. Presently no antisense reagents are available for inhibiting miRNAs in the nematode C. elegans. RESULTS: We have developed a new class of fluorescently labelled antisense reagents to inhibit miRNAs in …
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 …
Mutations In Conserved Residues Of The C. Elegans Microrna Argonaute Alg-1 Identify Separable Functions In Alg-1 Mirisc Loading And Target Repression, Anna Y. Zinovyeva, Samir Bouasker, Martin J. Simard, Christopher M. Hammell, Victor R. Ambros
Mutations In Conserved Residues Of The C. Elegans Microrna Argonaute Alg-1 Identify Separable Functions In Alg-1 Mirisc Loading And Target Repression, Anna Y. Zinovyeva, Samir Bouasker, Martin J. Simard, Christopher M. Hammell, Victor R. Ambros
Victor R. Ambros
microRNAs function in diverse developmental and physiological processes by regulating target gene expression at the post-transcriptional level. ALG-1 is one of two Caenorhabditis elegans Argonautes (ALG-1 and ALG-2) that together are essential for microRNA biogenesis and function. Here, we report the identification of novel antimorphic (anti) alleles of ALG-1 as suppressors of lin-28(lf) precocious developmental phenotypes. The alg-1(anti) mutations broadly impair the function of many microRNAs and cause dosage-dependent phenotypes that are more severe than the complete loss of ALG-1. ALG-1(anti) mutant proteins are competent for promoting Dicer cleavage of microRNA precursors and for associating with and stabilizing microRNAs. However, …
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 …
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, …
Caenorhabditis Elegans Micrornas Of The Let-7 Family Act In Innate Immune Response Circuits And Confer Robust Developmental Timing Against Pathogen Stress, Zhiji Ren, Victor R. Ambros
Caenorhabditis Elegans Micrornas Of The Let-7 Family Act In Innate Immune Response Circuits And Confer Robust Developmental Timing Against Pathogen Stress, Zhiji Ren, Victor R. Ambros
Victor R. Ambros
Animals maintain their developmental robustness against natural stresses through numerous regulatory mechanisms, including the posttranscriptional regulation of gene expression by microRNAs (miRNAs). Caenorhabditis elegans miRNAs of the let-7 family (let-7-Fam) function semiredundantly to confer robust stage specificity of cell fates in the hypodermal seam cell lineages. Here, we show reciprocal regulatory interactions between let-7-Fam miRNAs and the innate immune response pathway in C. elegans. Upon infection of C. elegans larvae with the opportunistic human pathogen Pseudomonas aeruginosa, the developmental timing defects of certain let-7-Fam miRNA mutants are enhanced. This enhancement is mediated by the p38 MAPK innate immune pathway acting …
Effect Of Life History On Microrna Expression During C. Elegans Development, Xantha Karp, Molly Hammell, Maria C. Ow, Victor R. Ambros
Effect Of Life History On Microrna Expression During C. Elegans Development, Xantha Karp, Molly Hammell, Maria C. Ow, Victor R. Ambros
Victor R. Ambros
Animals have evolved mechanisms to ensure the robustness of developmental outcomes to changing environments. MicroRNA expression may contribute to developmental robustness because microRNAs are key post-transcriptional regulators of developmental gene expression and can affect the expression of multiple target genes. Caenorhabditis elegans provides an excellent model to study developmental responses to environmental conditions. In favorable environments, C. elegans larvae develop rapidly and continuously through four larval stages. In contrast, in unfavorable conditions, larval development may be interrupted at either of two diapause stages: The L1 diapause occurs when embryos hatch in the absence of food, and the dauer diapause occurs …
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.
Prb/Cki Pathways At The Interface Of Cell Cycle And Development, Victor Ambros
Prb/Cki Pathways At The Interface Of Cell Cycle And Development, Victor Ambros
Victor R. Ambros
Comment on: The cyclin-dependent kinase inhibitors, cki-1 and cki-2, act in overlapping but distinct pathways to control cell-cycle quiescence during C. elegans development. Buck SH, et al. Cell Cycle 2009; 8:2613-20.
A Compendium Of Caenorhabditis Elegans Rna Binding Proteins Predicts Extensive Regulation At Multiple Levels, Alex Tamburino, Sean Ryder, Albertha Walhout
A Compendium Of Caenorhabditis Elegans Rna Binding Proteins Predicts Extensive Regulation At Multiple Levels, Alex Tamburino, Sean Ryder, Albertha Walhout
Sean P. Ryder
Gene expression is regulated at multiple levels, including transcription and translation, as well as mRNA and protein stability. Although systems-level functions of transcription factors and microRNAs are rapidly being characterized, few studies have focused on the posttranscriptional gene regulation by RNA binding proteins (RBPs). RBPs are important to many aspects of gene regulation. Thus, it is essential to know which genes encode RBPs, which RBPs regulate which gene(s), and how RBP genes are themselves regulated. Here we provide a comprehensive compendium of RBPs from the nematode Caenorhabditis elegans (wRBP1.0). We predict that as many as 887 (4.4%) of C. elegans …
A Quantitative Rna Code For Mrna Target Selection By The Germline Fate Determinant Gld-1, Jane Wright, Dimos Gaidatzis, Mathias Senften, Brian Farley, Eric Westhof, Sean Ryder, Rafal Ciosk
A Quantitative Rna Code For Mrna Target Selection By The Germline Fate Determinant Gld-1, Jane Wright, Dimos Gaidatzis, Mathias Senften, Brian Farley, Eric Westhof, Sean Ryder, Rafal Ciosk
Sean P. Ryder
RNA-binding proteins (RBPs) are critical regulators of gene expression. To understand and predict the outcome of RBP-mediated regulation a comprehensive analysis of their interaction with RNA is necessary. The signal transduction and activation of RNA (STAR) family of RBPs includes developmental regulators and tumour suppressors such as Caenorhabditis elegans GLD-1, which is a key regulator of germ cell development. To obtain a comprehensive picture of GLD-1 interactions with the transcriptome, we identified GLD-1-associated mRNAs by RNA immunoprecipitation followed by microarray detection. Based on the computational analysis of these mRNAs we generated a predictive model, where GLD-1 association with mRNA is …
Fbf Represses The Cip/Kip Cell-Cycle Inhibitor Cki-2 To Promote Self-Renewal Of Germline Stem Cells In C. Elegans, Irene Kalchhauser, Brian Farley, Sandra Pauli, Sean Ryder, Rafal Ciosk
Fbf Represses The Cip/Kip Cell-Cycle Inhibitor Cki-2 To Promote Self-Renewal Of Germline Stem Cells In C. Elegans, Irene Kalchhauser, Brian Farley, Sandra Pauli, Sean Ryder, Rafal Ciosk
Sean P. Ryder
Although the decision between stem cell self-renewal and differentiation has been linked to cell-cycle modifications, our understanding of cell-cycle regulation in stem cells is very limited. Here, we report that FBF/Pumilio, a conserved RNA-binding protein, promotes self-renewal of germline stem cells by repressing CKI-2(Cip/Kip), a Cyclin E/Cdk2 inhibitor. We have previously shown that repression of CYE-1 (Cyclin E) by another RNA-binding protein, GLD-1/Quaking, promotes germ cell differentiation. Together, these findings suggest that a post-transcriptional regulatory circuit involving FBF and GLD-1 controls the self-renewal versus differentiation decision in the germline by promoting high CYE-1/CDK-2 activity in stem cells, and inhibiting CYE-1/CDK-2 …
A Feedback Circuit Involving Let-7-Family Mirnas And Daf-12 Integrates Environmental Signals And Developmental Timing In Caenorhabditis Elegans, Christopher M. Hammell, Xantha Karp, Victor R. Ambros
A Feedback Circuit Involving Let-7-Family Mirnas And Daf-12 Integrates Environmental Signals And Developmental Timing In Caenorhabditis Elegans, Christopher M. Hammell, Xantha Karp, Victor R. Ambros
Victor R. Ambros
Animal development is remarkably robust; cell fates are specified with spatial and temporal precision despite physiological and environmental contingencies. Favorable conditions cause Caenorhabditis elegans to develop rapidly through four larval stages (L1-L4) to the reproductive adult. In unfavorable conditions, L2 larvae can enter the developmentally quiescent, stress-resistant dauer larva stage, enabling them to survive for prolonged periods before completing development. A specific progression of cell division and differentiation events occurs with fidelity during the larval stages, regardless of whether an animal undergoes continuous or dauer-interrupted development. The temporal patterning of developmental events is controlled by the heterochronic genes, whose products …
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 …
Potent Effect Of Target Structure On Microrna Function, Peter Williams, Dang Long, Rosalind Lee, Chi Chan, Victor Ambros, Ye Ding
Potent Effect Of Target Structure On Microrna Function, Peter Williams, Dang Long, Rosalind Lee, Chi Chan, Victor Ambros, Ye Ding
Victor R. Ambros
MicroRNAs (miRNAs) are small noncoding RNAs that repress protein synthesis by binding to target messenger RNAs. We investigated the effect of target secondary structure on the efficacy of repression by miRNAs. Using structures predicted by the Sfold program, we model the interaction between an miRNA and a target as a two-step hybridization reaction: nucleation at an accessible target site followed by hybrid elongation to disrupt local target secondary structure and form the complete miRNA-target duplex. This model accurately accounts for the sensitivity to repression by let-7 of various mutant forms of the Caenorhabditis elegans lin-41 3' untranslated region and for …
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.
Interacting Endogenous And Exogenous Rnai Pathways In Caenorhabditis Elegans., Rosalind C. Lee, Christopher M. Hammell, Victor R. Ambros
Interacting Endogenous And Exogenous Rnai Pathways In Caenorhabditis Elegans., Rosalind C. Lee, Christopher M. Hammell, Victor R. Ambros
Victor R. Ambros
C. elegans contains numerous small RNAs of ~21-24 nt in length. The microRNAs (miRNAs) are small noncoding RNAs produced by DCR-1- and ALG-dependent processing of self-complementary hairpin transcripts. Endogenous small interfering RNAs (endo-siRNAs), associated with ongoing silencing of protein-coding genes in normal worms, are produced by mechanisms that involve DCR-1 but, unlike miRNAs, also involve RDE-2, RDE-3, RDE-4, RRF-1, and RRF-3. The tiny noncoding (tncRNAs) are similar to endo-siRNAs in their biogenesis except that they are derived from noncoding sequences. These endo-siRNA- and tncRNA-based endogenous RNAi pathways involve some components, including DCR-1 and RDE-4, that are shared with exogenous RNAi, …
The Caenorhabditis Elegans Heterochronic Regulator Lin-14 Is A Novel Transcription Factor That Controls The Developmental Timing Of Transcription From The Insulin/Insulin-Like Growth Factor Gene Ins-33 By Direct Dna Binding., Marta Hristova, Darcy Birse, Yang Hong, Victor R. Ambros
The Caenorhabditis Elegans Heterochronic Regulator Lin-14 Is A Novel Transcription Factor That Controls The Developmental Timing Of Transcription From The Insulin/Insulin-Like Growth Factor Gene Ins-33 By Direct Dna Binding., Marta Hristova, Darcy Birse, Yang Hong, Victor R. Ambros
Victor R. Ambros
A temporal gradient of the novel nuclear protein LIN-14 specifies the timing and sequence of stage-specific developmental events in Caenorhabditis elegans. The profound effects of lin-14 mutations on worm development suggest that LIN-14 directly or indirectly regulates stage-specific gene expression. We show that LIN-14 can associate with chromatin in vivo and has in vitro DNA binding activity. A bacterially expressed C-terminal domain of LIN-14 was used to select DNA sequences that contain a putative consensus binding site from a pool of randomized double-stranded oligonucleotides. To identify candidates for genes directly regulated by lin-14, we employed DNA microarray hybridization to compare …
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 C. Elegans Heterochronic Gene Lin-46 Affects Developmental Timing At Two Larval Stages And Encodes A Relative Of The Scaffolding Protein Gephyrin., Anita Pepper, Jill Mccane, Kevin Kemper, Denise Yeung, Rosalind Lee, Victor Ambros, Eric Moss
The C. Elegans Heterochronic Gene Lin-46 Affects Developmental Timing At Two Larval Stages And Encodes A Relative Of The Scaffolding Protein Gephyrin., Anita Pepper, Jill Mccane, Kevin Kemper, Denise Yeung, Rosalind Lee, Victor Ambros, Eric Moss
Victor R. Ambros
The succession of developmental events in the C. elegans larva is governed by the heterochronic genes. When mutated, these genes cause either precocious or retarded developmental phenotypes, in which stage-specific patterns of cell division and differentiation are either skipped or reiterated, respectively. We identified a new heterochronic gene, lin-46, from mutations that suppress the precocious phenotypes caused by mutations in the heterochronic genes lin-14 and lin-28. lin-46 mutants on their own display retarded phenotypes in which cell division patterns are reiterated and differentiation is prevented in certain cell lineages. Our analysis indicates that lin-46 acts at a step immediately downstream …
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 …
An Extensive Class Of Small Rnas In Caenorhabditis Elegans, Rosalind Lee, Victor Ambros
An Extensive Class Of Small Rnas In Caenorhabditis Elegans, Rosalind Lee, Victor Ambros
Victor R. Ambros
The lin-4 and let-7 antisense RNAs are temporal regulators that control the timing of developmental events in Caenorhabditis elegans by inhibiting translation of target mRNAs. let-7 RNA is conserved among bilaterian animals, suggesting that this class of small RNAs [microRNAs (miRNAs)] is evolutionarily ancient. Using bioinformatics and cDNA cloning, we found 15 new miRNA genes in C. elegans. Several of these genes express small transcripts that vary in abundance during C. elegans larval development, and three of them have apparent homologs in mammals and/or insects. Small noncoding RNAs of the miRNA class appear to be numerous and diverse.
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 …