Results 1 - 10
of
460
The Drosha-DGCR8 complex in primary microRNA processing
- Genes Dev
, 2004
"... RNase III proteins play key roles in microRNA (miRNA) biogenesis. The nuclear RNase III Drosha cleaves primary miRNAs (pri-miRNAs) to release hairpin-shaped pre-miRNAs that are subsequently cut by the cytoplasmic RNase III Dicer to generate mature miRNAs. While Dicer (class III) and other simple RNa ..."
Abstract
-
Cited by 217 (4 self)
- Add to MetaCart
RNase III proteins play key roles in microRNA (miRNA) biogenesis. The nuclear RNase III Drosha cleaves primary miRNAs (pri-miRNAs) to release hairpin-shaped pre-miRNAs that are subsequently cut by the cytoplasmic RNase III Dicer to generate mature miRNAs. While Dicer (class III) and other simple RNase III proteins (class I) have been studied intensively, the class II enzyme Drosha remains to be characterized. Here we dissected the action mechanism of human Drosha by generating mutants and by characterizing its new interacting partner, DGCR8. The basic action mechanism of Drosha was found to be similar to that of human Dicer; the RNase III domains A and B form an intramolecular dimer and cleave the 3 and 5 strands of the stem, respectively. Human Drosha fractionates at ∼650 kDa, indicating that Drosha functions as a large complex. In this complex, Drosha interacts with DGCR8, which contains two double-stranded RNA (dsRNA)-binding domains. By RNAi and biochemical reconstitution, we show that DGCR8 may be an essential component of the pri-miRNA processing complex, along with Drosha. Based on these results, we propose a model for the action mechanism of class II RNase III proteins. [Keywords: microRNA; Drosha; DGCR8; processing] Supplemental material is available at
Molecular basis for the recognition of primary microRNAs by the Drosha-DGCR8 complex
- Cell
, 2006
"... The Drosha-DGCR8 complex initiates micro-RNA maturation by precise cleavage of the stem loops that are embedded in primary transcripts (pri-miRNAs). Here we propose a model for this process that is based upon evidence from both computational and biochemical analyses. A typical metazoan pri-miRNA con ..."
Abstract
-
Cited by 130 (1 self)
- Add to MetaCart
The Drosha-DGCR8 complex initiates micro-RNA maturation by precise cleavage of the stem loops that are embedded in primary transcripts (pri-miRNAs). Here we propose a model for this process that is based upon evidence from both computational and biochemical analyses. A typical metazoan pri-miRNA consists of a stem of 33 bp, with a terminal loop and flanking segments. The terminal loop is unessential, whereas the flanking ssRNA segments are critical for processing. The cleavage site is determined mainly by the distance ( 11 bp) from the stem-ssRNA junction. Purified DGCR8, but not Drosha, interacts with pri-miRNAs both directly and specifically, and the flanking ssRNA segments are vital for this binding to occur. Thus, DGCR8 may function as the molecular anchor that measures the distance from the dsRNA-ssRNA junction. Our current study thus facilitates the prediction of novel micro-RNAs and will assist in the rational design of small hairpin RNAs for RNA interference.
Non-coding RNA
- Hum. Mol. Genet., 15(Spec No
, 2006
"... The term non-coding RNA (ncRNA) is commonly employed for RNA that does not encode a protein, but this does not mean that such RNAs do not contain information nor have function. Although it has been generally assumed that most genetic information is transacted by proteins, recent evidence suggests th ..."
Abstract
-
Cited by 76 (2 self)
- Add to MetaCart
(Show Context)
The term non-coding RNA (ncRNA) is commonly employed for RNA that does not encode a protein, but this does not mean that such RNAs do not contain information nor have function. Although it has been generally assumed that most genetic information is transacted by proteins, recent evidence suggests that the majority of the genomes of mammals and other complex organisms is in fact transcribed into ncRNAs, many of which are alternatively spliced and/or processed into smaller products. These ncRNAs include microRNAs and snoRNAs (many if not most of which remain to be identified), as well as likely other classes of yet-to-be-discovered small regulatory RNAs, and tens of thousands of longer transcripts (including complex patterns of interlacing and overlapping sense and antisense transcripts), most of whose functions are unknown. These RNAs (including those derived from introns) appear to comprise a hidden layer of internal signals that control various levels of gene expression in physiology and development, including chromatin architecture/epigenetic memory, transcription, RNA splicing, editing, translation and turnover. RNA regulatory networks may determine most of our complex characteristics, play a significant role in disease and constitute an unexplored world of genetic variation both within and between species.
Mir-17-5p regulates breast cancer cell proliferation by inhibiting translation of AIB1 mRNA
- Mol. Cell Biol
, 2006
"... MicroRNAs are an extensive family of 22-nucleotide-long noncoding RNAs expressed in a wide range of eukaryotes, including humans, and they are important in development and disease. We found that microRNA Mir-17-5p has extensive complementarity to the mRNA of AIB1 (named for “amplified in breast canc ..."
Abstract
-
Cited by 71 (0 self)
- Add to MetaCart
(Show Context)
MicroRNAs are an extensive family of 22-nucleotide-long noncoding RNAs expressed in a wide range of eukaryotes, including humans, and they are important in development and disease. We found that microRNA Mir-17-5p has extensive complementarity to the mRNA of AIB1 (named for “amplified in breast cancer 1”). Cell culture experiments showed that AIB1 expression was downregulated by Mir-17-5p, primarily through trans-lational inhibition. Expression of Mir-17-5p was low in breast cancer cell lines. We also found that downregu-lation of AIB1 by Mir-17-5p resulted in decreased estrogen receptor-mediated, as well as estrogen receptor-independent, gene expression and decreased proliferation of breast cancer cells. Mir-17-5p also completely abrogated the insulin-like growth factor 1-mediated, anchorage-independent growth of breast cancer cells. Our results reveal that Mir-17-5p has a role as a tumor suppressor in breast cancer cells. MicroRNAs (miRNAs) are genomically encoded, 22-nu-cleotide-long noncoding RNAs found in many organisms. miRNAs are produced from primary RNA polymerase II tran-scripts by sequential processing in the nucleus and cytoplasm (26, 27). Nuclear precursor RNAs are cleaved by the endo-nuclease Drosha in a “microprocessor complex ” to release
Characterization and identification of microRNA core promoters in four model species
- PLoS Comput Biol
"... Characterization and identification of microRNA core promoters in four model species ..."
Abstract
-
Cited by 51 (2 self)
- Add to MetaCart
(Show Context)
Characterization and identification of microRNA core promoters in four model species
Processing of pre-microRNAs by the Dicer-1-Loquacious complex in Drosophila cells
- PLoS Biol
, 2005
"... Open access, freely available online ..."
(Show Context)
miRGen: a database for the study of animal microRNA genomic organization and function
- Nucleic Acids Res
, 2007
"... doi:10.1093/nar/gkl904 ..."
Human miRNA precursors with box H/ACA snoRNA features. PLoS. Comput. Biol. 2009; 5:e1000507. [PubMed: 19763159
"... MicroRNAs (miRNAs) and small nucleolar RNAs (snoRNAs) are two classes of small non-coding regulatory RNAs, which have been much investigated in recent years. While their respective functions in the cell are distinct, they share interesting genomic similarities, and recent sequencing projects have id ..."
Abstract
-
Cited by 37 (6 self)
- Add to MetaCart
(Show Context)
MicroRNAs (miRNAs) and small nucleolar RNAs (snoRNAs) are two classes of small non-coding regulatory RNAs, which have been much investigated in recent years. While their respective functions in the cell are distinct, they share interesting genomic similarities, and recent sequencing projects have identified processed forms of snoRNAs that resemble miRNAs. Here, we investigate a possible evolutionary relationship between miRNAs and box H/ACA snoRNAs. A comparison of the genomic locations of reported miRNAs and snoRNAs reveals an overlap of specific members of these classes. To test the hypothesis that somemiRNAsmight have evolved from snoRNA encoding genomic regions, reportedmiRNA-encoding regions were scanned for the presence of box H/ACA snoRNA features. Twenty miRNA precursors show significant similarity to H/ACA snoRNAs as predicted by snoGPS. These include molecules predicted to target known ribosomal RNA pseudouridylation sites in vivo for which no guide snoRNA has yet been reported. The predicted folded structures of these twenty H/ACA snoRNA-like miRNA precursors reveal molecules which resemble the structures of known box H/ACA snoRNAs. The genomic regions surrounding these predicted snoRNA-like miRNAs are often similar to regions around snoRNA retroposons, including the presence of transposable elements, target site duplications and poly (A) tails. We further show that the precursors of five H/ACA snoRNA-like miRNAs (miR-151, miR-605, mir-664, miR-215 and miR-140) bind to dyskerin, a specific protein component of functional box H/ ACA small nucleolar ribonucleoprotein complexes suggesting that these molecules have retained some H/ACA snoRNA
Aberrant Expression of Oncogenic and Tumor- Suppressive MicroRNAs in Cervical Cancer Is Required for Cancer Cell Growth
"... MicroRNAs (miRNAs) play important roles in cancer development. By cloning and sequencing of a HPV16 + CaSki cell small RNA library, we isolated 174 miRNAs (including the novel miR-193c) which could be grouped into 46 different miRNA species, with miR-21, miR-24, miR-27a, and miR-205 being most abund ..."
Abstract
-
Cited by 37 (1 self)
- Add to MetaCart
(Show Context)
MicroRNAs (miRNAs) play important roles in cancer development. By cloning and sequencing of a HPV16 + CaSki cell small RNA library, we isolated 174 miRNAs (including the novel miR-193c) which could be grouped into 46 different miRNA species, with miR-21, miR-24, miR-27a, and miR-205 being most abundant. We chose for further study 10 miRNAs according to their cloning frequency and associated their levels in 10 cervical cancer- or cervical intraepithelial neoplasia-derived cell lines. No correlation was observed between their expression with the presence or absence of an integrated or episomal HPV genome. All cell lines examined contained no detectable miR-143 and miR-145. HPV-infected cell lines expressed a different set of miRNAs when grown in organotypic raft cultured as compared to monolayer cell culture, including expression of miR-143 and miR-145. This suggests a correlation between miRNA expression and tissue differentiation. Using miRNA array analyses for age-matched normal cervix and cervical cancer tissues, in combination with northern blot verification, we identified significantly deregulated miRNAs in cervical cancer tissues, with miR-126, miR-143, and miR-145 downregulation and miR-15b, miR-16, miR-146a, and miR-155 upregulation. Functional studies showed that both miR-143 and miR-145 are suppressive to cell growth. When introduced into cell lines, miR-146a was found to promote cell proliferation. Collectively, our data indicate that downregulation of miR-143 and miR-145 and upregulation of miR-146a play a role in cervical
Z (2010) The fate of miRNA* strand through evolutionary analysis: implication for degradation as merely carrier strand or potential regulatory molecule? PLoS ONE 5: e11387
"... Background: During typical microRNA (miRNA) biogenesis, one strand of a,22 nt RNA duplex is preferentially selected for entry into a silencing complex, whereas the other strand, known as the passenger strand or miRNA * strand, is degraded. Recently, some miRNA * sequences were reported as guide miRN ..."
Abstract
-
Cited by 37 (5 self)
- Add to MetaCart
(Show Context)
Background: During typical microRNA (miRNA) biogenesis, one strand of a,22 nt RNA duplex is preferentially selected for entry into a silencing complex, whereas the other strand, known as the passenger strand or miRNA * strand, is degraded. Recently, some miRNA * sequences were reported as guide miRNAs with abundant expression. Here, we intended to discover evolutionary implication of the fate of miRNA * strand by analyzing miRNA/miRNA * sequences across vertebrates. Principal Findings: Mature miRNAs based on gene families were well conserved especially for their seed sequences across vertebrates, while their passenger strands always showed various divergence patterns. The divergence mainly resulted from divergence of different animal species, homologous miRNA genes and multicopy miRNA hairpin precursors. Some miRNA* sequences were phylogenetically conserved in seed and anchor sequences similar to mature miRNAs, while others revealed high levels of nucleotide divergence despite some of their partners were highly conserved. Most of those miRNA precursors that could generate abundant miRNAs from both strands always were well conserved in sequences of miR-#-5p and miR-#-3p, especially for their seed sequences. Conclusions: The final fate of miRNA * strand, either degraded as merely carrier strand or expressed abundantly as potential functional guide miRNA, may be destined across evolution. Well-conserved miRNA * strands, particularly conservation in seed sequences, maybe afford potential opportunities for contributing to regulation network. The study will broaden our
