Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “microRNA expression”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources
PubMed2005

Loss of function of OsDCL1 affects microRNA accumulation and causes developmental defects in rice.

MicroRNAs (miRNAs) and small interfering RNAs (siRNAs) are two types of noncoding RNAs involved in developmental regulation, genome maintenance, and defense in eukaryotes. The activity of Dicer or Dicer-like (DCL) proteins is required for the maturation of miRNAs and siRNAs. In this study, we cloned and sequenced 66 candidate rice (Oryza sativa) miRNAs out of 1,650 small RNA sequences (19 to approximately 25 nt), and they could be further grouped into 21 families, 12 of which are newly identified and three of which, OsmiR528, OsmiR529, and OsmiR530, have been confirmed by northern blot. To study the function of rice DCL proteins (OsDCLs) in the biogenesis of miRNAs and siRNAs, we searched genome databases and identified four OsDCLs. An RNA interference approach was applied to knock down two OsDCLs, OsDCL1 and OsDCL4, respectively. Strong loss of function of OsDCL1IR transformants that expressed inverted repeats of OsDCL1 resulted in developmental arrest at the seedling stage, and weak loss of function of OsDCL1IR transformants caused pleiotropic developmental defects. Moreover, all miRNAs tested were greatly reduced in OsDCL1IR but not OsDCL4IR transformants, indicating that OsDCL1 plays a critical role in miRNA processing in rice. In contrast, the production of siRNA from transgenic inverted repeats and endogenous CentO regions were not affected in either OsDCL1IR or OsDCL4IR transformants, suggesting that the production of miRNAs and siRNAs is via distinct OsDCLs.

Arabidopsis Proteins↗
PubMed2006

MicroRNA trafficking and human cancer.

MicroRNAs (miRNAs) are short endogenous noncoding small RNA molecules with 21 to 25 nucleotides (nt) in length, which negatively regulate gene expression either by degrading specific mRNA or impeding translation at the transcriptional and post-transcriptional level. Recent advances suggest that miRNAs play prominent roles in development, genome organization, viral and transposon defense, and human disease, including neurodegenerative and metabolic diseases. Surprisingly, miRNAs are now linked with a variety of cancers, in which a reduced expression or overexpression may lead to oncogene or tumor suppressor gene-like actions. Here we will overview the miRNA pathway and its regulation with emphasis on the links with human cancer. Finally potential applications of miRNA in tumor diagnosis and therapy will be discussed.

Gene Expression Regulation, Neoplastic↗
PubMed2006

MicroRNA therapeutics: a new niche for antisense nucleic acids.

MicroRNA molecules (miRNAs) are naturally occurring triggers of the RNA-interference pathway. The first identified miRNA, lin-4, was discovered in Caenorhabditis elegans >20 years ago. What began as a curiosity in this model organism has expanded into almost every area of biology; there are now 326 confirmed miRNA genes in humans and the total is predicted to reach 1000. Each miRNA has the potential to regulate hundreds of mRNAs; therefore, there are likely to be few biological pathways not impacted by miRNA regulation. Recent evidence has suggested that miRNAs might be viable therapeutic targets for a wide range of diseases, including cancer. A recent article by Stoffel and colleagues has demonstrated remarkably effective inhibition of miRNAs in vivo, thus providing an entry point into the promising new arena of miRNA therapeutics.

Animals↗
PubMed2007

MicroRNAs and their regulatory roles in animals and plants.

microRNAs (miRNAs) are an abundant class of newly identified endogenous non-protein-coding small RNAs. They exist in animals, plants, and viruses, and play an important role in gene silencing. Translational repression, mRNA cleavage, and mRNA decay initiated by miRNA-directed deadenylation of targeted mRNAs are three mechanisms of miRNA-guided gene regulation at the post-transcriptional levels. Many miRNAs are highly conserved in animals and plants, suggesting that they play an essential function in plants and animals. Lots of investigations indicate that miRNAs are involved in multiple biological processes, including stem cell differentiation, organ development, phase change, signaling, disease, cancer, and response to biotic and abiotic environmental stresses. This review provides a general background and current advance on the discovery, history, biogenesis, genomics, mechanisms, and functions of miRNAs.

Animals↗
PubMed2006

Direct and sensitive miRNA profiling from low-input total RNA.

We have developed a sensitive, accurate, and multiplexed microRNA (miRNA) profiling assay that is based on a highly efficient labeling method and novel microarray probe design. The probes provide both sequence and size discrimination, yielding in most cases highly specific detection of closely related mature miRNAs. Using a simple, single-vial experimental protocol, 120 ng of total RNA is directly labeled using Cy3 or Cy5, without fractionation or amplification, to produce precise and accurate measurements that span a linear dynamic range from 0.2 amol to 2 fmol of input miRNA. The results can provide quantitative estimates of the miRNA content for the tissues studied. The assay is also suitable for use with formalin-fixed paraffin-embedded clinical samples. Our method allows rapid design and validation of probes for simultaneous quantitative measurements of all human miRNA sequences in the public databases and to new miRNA sequences as they are reported.

Animals↗
PubMed2005

Microarray profiling of microRNAs reveals frequent coexpression with neighboring miRNAs and host genes.

MicroRNAs (miRNAs) are short endogenous RNAs known to post-transcriptionally repress gene expression in animals and plants. A microarray profiling survey revealed the expression patterns of 175 human miRNAs across 24 different human organs. Our results show that proximal pairs of miRNAs are generally coexpressed. In addition, an abrupt transition in the correlation between pairs of expressed miRNAs occurs at a distance of 50 kb, implying that miRNAs separated by <50 kb typically derive from a common transcript. Some microRNAs are within the introns of host genes. Intronic miRNAs are usually coordinately expressed with their host gene mRNA, implying that they also generally derive from a common transcript, and that in situ analyses of host gene expression can be used to probe the spatial and temporal localization of intronic miRNAs.

Base Sequence↗
PubMed2005

Specific effects of microRNAs on the plant transcriptome.

Most plant microRNAs (miRNAs) have perfect or near-perfect complementarity with their targets. This is consistent with their primary mode of action being cleavage of target mRNAs, similar to that induced by perfectly complementary small interfering RNAs (siRNAs). However, there are natural targets with up to five mismatches. Furthermore, artificial siRNAs can have substantial effects on so-called off-targets, to which they have only limited complementarity. By analyzing the transcriptome of plants overexpressing different miRNAs, we have deduced a set of empirical parameters for target recognition. Compared to artificial siRNAs, authentic plant miRNAs appear to have much higher specificity, which may reflect their coevolution with the remainder of the transcriptome. We also demonstrate that miR172, previously thought to act primarily by translational repression, can efficiently guide mRNA cleavage, although the effects on steady-state levels of target transcripts are obscured by strong feedback regulation. This finding unifies the view of plant miRNA action.

Base Pairing↗
PubMed2006

A tiny helper lightens the maternal load.

In a recent issue of Science, the puzzle of how a large number of maternal mRNAs can be coordinately destroyed at the mid-blastula transition of early animal embryogenesis is solved. The mysterious agent is not a protein but rather a microRNA that is transcribed at this transition point.

Animals↗
PubMed2004

MicroRNA regulation of NAC-domain targets is required for proper formation and separation of adjacent embryonic, vegetative, and floral organs.

BACKGROUND: MicroRNAs (miRNAs) are approximately 21 nucleotide (nt) RNAs that regulate gene expression in plants and animals. Most known plant miRNAs target transcription factors that influence cell fate determination, and biological functions of miRNA-directed regulation have been reported for four of 15 known microRNA gene families: miR172, miR159, miR165, and miR168. Here, we identify a developmental role for miR164-directed regulation of NAC-domain genes, which encode a family of transcription factors that includes CUP-SHAPED COTYLEDON1 (CUC1) and CUC2. RESULTS: Expression of a miR164-resistant version of CUC1 mRNA from the CUC1 promoter causes alterations in Arabidopsis embryonic, vegetative, and floral development, including cotyledon orientation defects, reduction of rosette leaf petioles, dramatically misshapen rosette leaves, one to four extra petals, and one or two missing sepals. Reciprocally, constitutive overexpression of miR164 recapitulates cuc1 cuc2 double mutant phenotypes, including cotyledon and floral organ fusions. miR164 overexpression also leads to phenotypes not previously observed in cuc1 cuc2 mutants, including leaf and stem fusions. These likely reflect the misregulation of other NAC-domain mRNAs, including NAC1, At5g07680, and At5g61430, for which miR164-directed cleavage products were detected. CONCLUSIONS: These results demonstrate that miR164-directed regulation of CUC1 is necessary for normal embryonic, vegetative, and floral development. They also show that proper miR164 dosage or localization is required for separation of adjacent embryonic, vegetative, and floral organs, thus implicating miR164 as a common regulatory component of the molecular circuitry that controls the separation of different developing organs and thereby exposes a posttranscriptional layer of NAC-domain gene regulation during plant development.

Amino Acid Sequence↗
PubMed2025

Transcriptomic profile induced by calcitriol in CaSki human cervical cancer cell line.

The vitamin D endocrine system, primarily mediated by its main metabolite calcitriol and the vitamin D receptor (VDR), plays a critical role in numerous human physiological processes, ranging from calcium metabolism to the prevention of various tumors, including cervical cancer. In this study, we comprehensively investigated the genomic regulatory effects of calcitriol in a cervical cancer model. We examined the transcriptional changes induced by calcitriol in CaSki cells, a cervical cell line harboring multiple copies of HPV16, the primary causal agent of cervical cancer. Our microarray findings, revealed that calcitriol regulated over 1000 protein-coding genes, exhibiting a predominantly repressive effect on the CaSki cell transcriptome by suppressing twice as many genes as it induced. Calcitriol decreased EPHA2 and RARA expression while inducing KLK6 and CYP4F3 expression in CaSki cells, as validated by qPCR and Western blot. Functional analysis demonstrated that calcitriol effectively inhibited key processes involved in cancer progression, including cell proliferation and migration. This was further supported by the significant downregulation of MMP7 and MMP13 mRNA levels. Our microarray results also showed that, in addition to its effects on protein-coding genes, calcitriol significantly regulates non-coding RNAs, altering the expression of approximately 400 non-coding RNAs, including 111 microRNA precursors and 29 mature microRNAs, of which 17 were upregulated and 12 downregulated. Notably, among these calcitriol-regulated microRNAs are some involved in cervical cancer biology, such as miR-6129, miR-382, miR-655, miR-211, miR-590, miR-130a, miR-301a, and miR-1252. Collectively, these findings suggest that calcitriol exhibits a significant antitumor effect in this advanced cervical cancer model by blocking critical processes for tumor progression, underscoring the importance of maintaining adequate vitamin D nutritional status.

Humans↗
PubMed2006

Developmental and seasonal expression of PtaHB1, a Populus gene encoding a class III HD-Zip protein, is closely associated with secondary growth and inversely correlated with the level of microRNA (miR166).

In contrast to our knowledge of the shoot apical meristem, our understanding of cambium meristem differentiation and maintenance is limited. Class III homeodomain leucine-zipper (HD-Zip) proteins have been shown to play a regulatory role in vascular differentiation. The hybrid aspen (Populus tremulaxPopulus alba) class III HD-Zip transcription factor (PtaHB1) and microRNA 166 (Pta-miR166) family were cloned from hybrid aspen using a combination of in silico and polymerase chain reaction methods. Expression analyses of PtaHB1 and Pta-miR166 were performed by Northern blot analysis. The expression of PtaHB1 was closely associated with wood formation and regulated both developmentally and seasonally, with the highest expression during the active growing season. Also, its expression was inversely correlated with the level of Pta-miR166. Pta-miR166-directed cleavage of PtaHB1 in vivo was confirmed using modified 5'-rapid amplification of cDNA ends (RACE). The expression of Pta-miR166 was much higher in the winter than in the growing seasons, suggesting seasonal and developmental regulation of microRNA in this perennial plant species.

Amino Acid Sequence↗
PubMed2006

Cloning and regulation of the vertebrate homologue of lin-41 that functions as a heterochronic gene in Caenorhabditis elegans.

The Caenorhabditis elegans gene lin-41 is the one of the heterochronic genes that regulate the timing of many developmental events. MicroRNA let-7 negatively regulates the expression of lin-41 through RNA-RNA interaction on its 3' untranslated region (UTR). Here, we report the isolation of chick and mouse homologues of lin-41 that encode the RBCC-NHL family protein and their expression patterns. C. elegans lin-41 is one of the RBCC-NHL families and the predicted amino acid sequences of isolated two genes encode the same family proteins. Chick and mouse lin-41 expression was also observed in developing limb buds, branchial arches, and tail buds. The 3'UTRs of the mouse and chick lin-41 genes contain multiple let-7 complementary sites. Using luciferase assay, we showed that lin-41 expression can be regulated through let-7 complementary sites.

3' Untranslated Regions↗
PubMed2006

A PCR-based method for detection and quantification of small RNAs.

Recent cloning efforts have identified hundreds of thousands of small RNAs including micro RNAs (miRNAs), Piwi-interacting RNAs (piRNAs), and small nucleolar RNAs (snoRNAs). These non-coding small RNAs need to be further validated and characterized by detecting and quantifying their expression in different tissues and during different developmental courses. A simple, accurate, and sensitive method for small RNA expression profiling is in high demand. Here, we report such a PCR-based method.

Animals↗
PubMed2005

Small RNA asymmetry in RNAi: function in RISC assembly and gene regulation.

RNAi is a conserved gene-specific regulatory mechanism, which silences target gene expression transcriptionally and post-transcriptionally. The RNAi machinery converts the sequence specific information of a long double stranded RNAs (dsRNAs) into small 21-22 nt long dsRNAs (siRNAs, miRNAs) which assemble into an effector complex, the RNA induced silencing complex (RISC). RISC assembly is asymmetric; one strand of an siRNA or a miRNA preferentially incorporates into the RNA-protein complex. Here, I review the rules of the asymmetric RISC formation and discuss their possible regulatory function in several steps in RNAi.

Animals↗