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At least 703 records · Page 39Linked to original sources
PubMed1996

Differential regulation of fibroblast growth factor (FGF) receptor-1 mRNA and protein by two molecular forms of basic FGF. Modulation of FGFR-1 mRNA stability.

To evaluate possible functional differences between basic fibroblast growth factor (FGF) 2 isoforms we analyzed the effects of the 18-kDa FGF-2 which mainly localizes in the cytosol and that of the nuclear-targeted 22.5-kDa form on FGF receptors (FGFR) expression. These peptides were expressed at low amounts through a retroviral-infection system. Point mutated FGF-2 cDNAs under the control of the beta-actin promoter were used to infect a pancreatic cell line (AR4 2J) which does not produce FGF-2. Saturation and competition binding studies with 125I-FGF-2 revealed a 3-fold increase in both high and low affinity receptors in cells expressing the 22.5-kDa form and a 2-fold increase only in the high affinity receptors in cells producing the 18-kDa form. Kd values and molecular weights of the high affinity receptors were unaffected. Increasing cell densities or cell treatment with exogenous FGF-2 resulted in FGFR down-regulation as in control cells. Neutralizing anti-FGF-2 antibodies and suramin did not affect receptor density in control and in cells producing the 22.5-kDa form but further increased by 60 and 80%, respectively, the receptor level in cells synthesizing the 18-kDa form. These data suggest the involvement of the intracellular stored FGF-2 in FGFR up-regulation. Although all cells expressed FGFR-1, -2, and -3 mRNA only the FGFR-1 transcript was found increased, 6-fold in 22.5-kDa expressing cells and 3-fold in cell producing the shortest secreted isoform. The increase in FGFR-1 mRNA levels in the 22.5-kDa expressing cells was due to enhanced stability of the transcript. Confocal microscopy detected the presence of FGFR-1 at the cell surface whereas secretory isoforms of the receptor were not observed. Reverse transcriptase-polymerase chain reaction did not reveal significant differences in the expression of FGFR-1 variants. In the 22.5-kDa expressing cells exogenous FGF-2 evoked a stronger translocation of the calcium-phospholipid-dependent PKC. These results indicate that the transfected FGF-2 isoforms up-regulated FGFR-1 mRNA and protein. The 22.5-kDa form acted by increasing FGFR-1 mRNA stability enhancing cell responses to exogenous FGF-2.

Animals↗
PubMed1996

Mutants of eukaryotic initiation factor eIF-4E with altered mRNA cap binding specificity reprogram mRNA selection by ribosomes in Saccharomyces cerevisiae.

Recognition of the 5'-end of eukaryotic mRNA by the ribosomal 43 S preinitiation complex involves the eukaryotic translation initiation factor eIF-4E (eIF-4alpha). Deletion mutants of the eIF-4E gene of Saccharomyces cerevisiae (CDC33) encoded proteins with reduced affinity for the 5'-cap. One of these mutant proteins lacked any detectable binding to a cap analogue binding column, yet was still able to support cell growth. More than 17% of the total eIF-4E amino acid sequence could be removed without fully inactivating this factor. At least 30 of the N-terminal amino acids are not essential for function. The minimal functional eIF-4E protein segment therefore comprises at most 176 amino acids. The translation and growth defects of the deletion mutants could be at least partially compensated by increases in eIF-4E synthesis, possibly due to a mass-action effect on mRNA binding. Electroporation of yeast spheroplasts with in vitro synthesized mRNA allowed us to characterize the ability of eIF-4E mutant strains to distinguish between capped and uncapped mRNAs in vivo. Our data show that the cap specificity of eIF-4E determines to what extent the translational apparatus differentiates between capped and uncapped mRNAs and indicate the minimum relative mRNA (cap) binding activity of eIF-4E required for yeast cell viability.

Amino Acid Sequence↗
PubMed1998

Identification of a hormonally regulated luteinizing hormone/human chorionic gonadotropin receptor mRNA binding protein. Increased mrna binding during receptor down-regulation.

To elucidate the molecular events associated with the regulation of luteinizing hormone/human chorionic gonadotropin (LH/hCG) receptor mRNA stability during hCG-induced receptor down-regulation, we have identified an LH/hCG receptor-specific mRNA binding protein. Proteins were isolated from control and down-regulated rat ovary and were incubated with in vitro transcribed RNAs corresponding to the full-length LH/hCG receptor, as well as 5'- and 3'-truncated receptor forms. Resultant ribonucleoprotein complexes were analyzed by RNA gel mobility shift. A prominent Mr 50,000 ribonucleoprotein complex was identified with the following characteristics: 1) specificity for LH/hCG receptor open reading frame sequences located between nucleotides 102 and 282; 2) lack of competition by nonspecific RNAs; 3) a 3-fold increase in RNA binding activity during hCG-induced receptor down-regulation; and 4) limited tissue expression. This report describes the first evidence of an LH/hCG receptor mRNA binding protein, which we term LRBP-1, for luteinizing hormone receptor RNA binding protein-1. This protein is a candidate for a trans-acting factor involved in the hormonal regulation of LH/hCG receptor mRNA stability in rat ovary.

Animals↗
PubMed2000

Glucocorticoid-mediated destabilization of cyclin D3 mRNA involves RNA-protein interactions in the 3'-untranslated region of the mRNA.

Glucocorticoids regulate the expression of the G(1) progression factor, cyclin D3. Cyclin D3 messenger RNA (CcnD3 mRNA) stability decreases rapidly when murine T lymphoma cells are treated with the synthetic glucocorticoid dexamethasone. Basal stability of CcnD3 mRNA is regulated by sequences within the 3'-untranslated region (3'-UTR). RNA-protein interactions occurring within the CcnD3 3'-UTR have been analyzed by RNA electrophoretic mobility shift assay. Three sites of RNA-protein interaction have been mapped using this approach. These elements include three pyrimidine-rich domains of 25, 26, and 37 nucleotides. When the cyclin D3 3'-UTR was stably overexpressed, the endogenous CcnD3 mRNA was no longer regulated by dexamethasone. Likewise, overexpression of a 215-nucleotide transgene that contains the 26- and 37-nucleotide elements blocks glucocorticoid inhibition of CcnD3 mRNA expression. These observations suggest that the 215-nucleotide 3'-UTR element may act as a molecular decoy, competing for proteins that bind to the endogenous transcript and thereby attenuating glucocorticoid responsiveness. UV-cross-linking experiments showed that two proteins of approximate molecular weight 37,000 and 52,000 bind to this 3'-UTR element.

3' Untranslated Regions↗
PubMed2006

Regulation of SOX9 mRNA in human articular chondrocytes involving p38 MAPK activation and mRNA stabilization.

Human articular chondrocytes rapidly lose their phenotype in monolayer culture. Recently we have shown that overexpression of the transcription factor SOX9 greatly enhanced re-expression of the phenotype in three-dimensional aggregate cultures. Here we show that endogenous SOX9 mRNA can be rapidly up-regulated in subcultured human articular chondrocytes if grown in alginate, in monolayer with cytochalasin D, or with specific inhibition of the RhoA effector kinases ROCK1 and -2, which all prevent actin stress fiber formation. Disruption of actin stress fibers using any of these redifferentiation stimuli also supported the superinduction of SOX9 by cycloheximide. The superinduction was blocked by inhibitors of the p38 MAPK signaling pathway and involved the stabilization of SOX9 mRNA. Furthermore stimulation of chondrocyte p38 MAPK activity with interleukin-1beta resulted in increased levels of SOX9 mRNA, and this was again dependent on the absence of actin stress fibers in the cells. In this study of chondrocyte redifferentiation we have provided further evidence of the early involvement of SOX9 and have discovered a novel post-transcriptional regulatory mechanism activated by p38 MAPK, which stabilized SOX9 mRNA.

Alginates↗
PubMed1986

Human keratinocytes contain mRNA indistinguishable from monocyte interleukin 1 alpha and beta mRNA. Keratinocyte epidermal cell-derived thymocyte-activating factor is identical to interleukin 1.

Keratinocytes produce an IL-1 like factor termed epidermal cell-derived thymocyte-activating factor (ETAF). In this study, we show that ETAF and IL-1 are identical by the following criteria: Both normal and malignant human keratinocytes contain mRNAs identical to monocytic IL-1 alpha and IL-1 beta mRNA, as determined by an S1 nuclease protection assay; and IL-1 activity in medium conditioned by these cells can be neutralized by antibodies specific for human IL-1. The IL-1 alpha and IL-1 beta mRNAs can be identified in cultured human keratinocytes in the absence of identifiable stimulation; this basal level of mRNA can be further induced to accumulate with certain defined stimuli. Cultured normal human keratinocytes (HFKs) contain 2-4 times more IL-1 alpha than IL-1 beta mRNA; in contrast, human peripheral blood monocytes contain 10-20 times more IL-1 beta than IL-1 alpha mRNA. The IL-1 activity released by these HFK can be neutralized by an antibody that neutralizes both alpha and beta IL-1, but not by an antibody that neutralizes only IL-1 beta. While human monocytes produce a large excess of IL-1 beta after appropriate stimulation, these data suggest that IL-1 alpha is a major (and may be the predominant) form of IL-1 produced by human keratinocytes.

Cell Line↗
PubMed1998

Nuclear history of a pre-mRNA determines the translational activity of cytoplasmic mRNA.

The pathways of synthesis and maturation of pre-messenger RNA in the nucleus have a direct effect on the translational efficiency of mRNA in the cytoplasm. The transcription of intron-less mRNA in vivo directs this mRNA towards translational silencing. The presence of an intron at the 5' end of the transcript relieves this silencing, whereas an intron at the 3' end further represses translation. These regulatory events are strongly dependent on the transcription of pre-mRNA in the nucleus. The impact of nuclear history on regulatory events in the cytoplasm provides a novel mechanism for the control of gene expression.

Animals↗
PubMed1999

Intronless mRNA transport elements may affect multiple steps of pre-mRNA processing.

We have reported recently that a small element within the mouse histone H2a-coding region permits efficient cytoplasmic accumulation of intronless beta-globin cDNA transcripts. This sequence lowers the levels of spliced products from intron-containing constructs and can functionally replace Rev and the Rev-responsive element (RRE) in the nuclear export of unspliced HIV-1-related mRNAs. In work reported here, we further investigate the molecular mechanisms by which this element might work. We demonstrate here through both in vivo and in vitro assays that, in addition to promoting mRNA nuclear export, this element acts as a polyadenylation enhancer and as a potent inhibitor of splicing. Surprisingly, two other described intronless mRNA transport elements (from the herpes simplex virus thymidine kinase gene and hepatitis B virus) appear to function in a similar manner. These findings prompt us to suggest that a general feature of intronless mRNA transport elements might be a collection of phenotypes, including the inhibition of splicing and the enhancement of both polyadenylation and mRNA export.

Animals↗
PubMed2001

The exon-exon junction complex provides a binding platform for factors involved in mRNA export and nonsense-mediated mRNA decay.

We recently reported that spliceosomes alter messenger ribonucleoprotein particle (mRNP) composition by depositing several proteins 20-24 nucleotides upstream of mRNA exon-exon junctions. When assembled in vitro, this so-called 'exon-exon junction complex' (EJC) contains at least five proteins: SRm160, DEK, RNPS1, Y14 and REF. To better investigate its functional attributes, we now describe a method for generating spliced mRNAs both in vitro and in vivo that either do or do not carry the EJC. Analysis of these mRNAs in Xenopus laevis oocytes revealed that this complex is the species responsible for enhancing nucleocytoplasmic export of spliced mRNAs. It does so by providing a strong binding site for the mRNA export factors REF and TAP/p15. Moreover, by serving as an anchoring point for the factors Upf2 and Upf3, the EJC provides a direct link between splicing and nonsense-mediated mRNA decay. Finally, we show that the composition of the EJC is dynamic in vivo and is subject to significant evolution upon mRNA export to the cytoplasm.

Animals↗
PubMed1996

Rat plasma triglycerides and hepatic fatty acid synthetase mRNA, but not apolipoprotein B and A-IV mRNA, respond to dietary fat content.

The objective was to determine whether apolipoprotein B and A-IV mRNA abundance or plasma lipid concentrations would be altered by chronic or acute consumption of diets that differed in fat content. Forty Wistar male rats were fed either a low fat (5 g/ 100 g) or high fat (20 g/100 g) diet for 4 wk. Animals were killed unfed or 3 h after consumption of a test meal of the diet to which they had been adapted (n = 8). In addition, a low fat diet-adapted group was fed a high fat test meal and killed 3 h after the meal. Adaptation to the high or low fat diets did not result in differences in triglyceride or cholesterol concentrations in the plasma of unfed rats. In fed animals, plasma, VLDL, and LDL triglyceride concentrations were significantly higher in those fed the high fat test meal than in those fed the low fat test meal. Feeding did not alter plasma cholesterol concentrations; however, LDL cholesterol concentrations in the groups fed the high fat meals were significantly higher than in the group fed the low fat meal. There were no differences in plasma apolipoproteins B, A-IV, E, and A-I nor in the liver or intestinal apolipoprotein B and A-IV mRNA contents. Fatty acid synthetase (FAS) activity was significantly higher in rats adapted to the low fat diet, and no increase in activity due to feeding was observed. Hepatic FAS mRNA was higher in fed than unfed rats, and the low fat test meal resulted in a higher level than the high fat test meal. Plasma lipid concentrations were affected by the fat content of test meals rather than by the adaptation diet fat content. Apolipoprotein B and A-IV mRNA do not seem to respond to dietary fat or meal feeding.

Animals↗
PubMed1991

Rapid c-myc mRNA degradation does not require (A + U)-rich sequences or complete translation of the mRNA.

The c-myc proto-oncogene encodes a highly unstable mRNA. Stabilized, truncated myc transcripts have been found in several human and murine tumors of hematopoietic origin. Recently, two tumors expressing 3' truncated c-myc mRNAs that were five times more stable than normal myc transcripts, were described. We have tried to determine the cause of the increased stability of the 3' truncated myc transcripts by studying the half-life of mutated c-myc mRNAs. The c-myc 3' untranslated region has been shown to contain sequences that confer mRNA instability. Possible candidates for such sequences are two (A + U)-rich regions in the 3' end of the c-myc RNA that resemble RNA destabilizing elements present in the c-fos and GMCSF mRNAs. We show that deletions in the (A + U)-rich regions do not stabilize c-myc messengers, and that hybrid mRNAs containing SV40 sequences at their 3' ends and terminating at an SV40 polyadenylation signal decay as quickly as normal c-myc transcripts. Our results indicate that neither the loss of (A + U)-rich sequences nor the mere addition of non-myc sequences to the 3' end of the mRNA lead to stabilization. We also show that rapid degradation of c-myc mRNA does not require complete translation of the coding sequences.

Adenine↗
PubMed1992

How are tRNAs and mRNA arranged in the ribosome? An attempt to correlate the stereochemistry of the tRNA-mRNA interaction with constraints imposed by the ribosomal topography.

Two tRNA molecules at the ribosomal A- and P-sites, with a relatively small angle between the planes of the L-shaped molecules, can be arranged in two mutually exclusive orientations. In one (the 'R'-configuration), the T-loop of the A-site tRNA faces the D-loop of the P-site tRNA, whereas in the other (the 'S'-configuration) the D-loop of the A-site tRNA faces the T-loop of the P-site tRNA. A number of stereochemical arguments, based on the crystal structure of 'free' tRNA, favour the R-configuration. In the ribosome, the CCA-ends of the tRNA molecules are 'fixed' at the base of the central protuberance (the peptidyl transferase centre) of the 50S subunit, and the anticodon loops lie in the neck region (the decoding site) of the 30S subunit. The translocation step is essentially a rotational movement of the tRNA from the A- to the P-site, and there is convincing evidence that the A-site must be located nearest to the L7/L12 protuberance of the 50S subunit. The mRNA in the two codon-anticodon duplexes lies on the 'inside' of the 'elbows' of the tRNA molecules (in both the S-type and R-type configurations), and runs up between the two molecules from the A- to the P-site in the 3' to 5'-direction. These considerations have the consequence that in the S-configuration the mRNA in the codon-anticodon duplexes is directed towards the 50S subunit, whereas in the R-configuration it is directed towards the 30S subunit. The results of site-directed cross-linking experiments, in particular cross-links to mRNA at positions within or very close to the codons interacting with A- or P-site tRNA, favour the latter situation. This conclusion is in direct contradiction to other current models for the arrangement of mRNA and tRNA on the ribosome.

Cross-Linking Reagents↗
PubMed1995

Defining a novel cis element in the 3'-untranslated region of mammalian ribonucleotide reductase component R2 mRNA: role in transforming growth factor-beta 1 induced mRNA stabilization.

Ribonucleotide reductase R2 gene expression is elevated in BALB/c 3T3 fibroblasts treated with transforming growth factor beta 1. We investigated the possibility that the 3'-UTR of ribonucleotide reductase R2 mRNA contains regulatory information for TGF-beta 1 induced message stability. Using end-labeled RNA fragments in gel shift assays and UV cross-linking analyses, we detected in the 3'-UTR a novel 9 nucleotide (nt) cis element, 5'-GAGUUUGAG-3' site, which interacted specifically with a cytosolic protease sensitive factor to form a 75 kDa complex. The cis element protein binding activity was inducible and markedly up-regulated cross-link 4 h after TGF-beta 1 treatment of mouse BALB/c 3T3 cells. Other 3'-UTRs [IRE, GM-CSF, c-myc and homopolymer (U)] were poor competitors to the cis element with regard to forming the TGF-beta 1 dependent RNA-protein complex. However, the cis element effectively competed out the formation of the R2 3'-UTR protein complex. Cytosolic extracts from a variety of mammalian cell lines (monkey Cos7, several mouse fibrosarcomas and human HeLa S3) demonstrated similar TGF-beta 1 dependent RNA-protein band shifts as cell extract from BALB/c 3T3 mouse fibroblasts. Binding was completely prevented by several different mutations within the cis element, and by substitution mutagenesis, we were able to predict the consensus sequences, 5'-GAGUUUNNN-3' and 5'-NNNUUUGAG-3' for optimal protein binding. These results support a model in which the 9 nt region functions in cis to destabilize R2 mRNA in cells; and upon activation, a TGF-beta 1 responsive protein is induced and interacts with the 9 nt cis element in a mechanism that leads to stabilization of the mRNA. This appears to be the first example of a mRNA binding site that is involved in TGF-beta 1-mediated effects.

3T3 Cells↗
PubMed1997

The N-terminal half of the influenza virus NS1 protein is sufficient for nuclear retention of mRNA and enhancement of viral mRNA translation.

A collection of C-terminal deletion mutants of the influenza A virus NS1 gene has been used to define the regions of the NS1 protein involved in its functionality. Immunofluorescence analyses showed that the NS1 protein sequences downstream from position 81 are not required for nuclear transport. The capacity of these mutants to bind RNA was studied by in vitro binding tests using a model vRNA probe. These experiments showed that the N-terminal 81 amino acids of NS1 protein are sufficient for RNA binding activity. The collection of mutants also served to map the NS1 sequences required for nuclear retention of mRNA and for stimulation of viral mRNA translation, using the NP gene as reporter. The results obtained indicated that the N-terminal 113 amino acids of NS1 protein are sufficient for nuclear retention of mRNA and stimulation of viral mRNA translation. The possibility that this region of the protein may be sufficient for virus viability is discussed in relation to the sequences of NS1 genes of field isolates and to the phenotype of known viral mutants affected in the NS1 gene.

Animals↗
PubMed1979

Sequences of large T1 ribonuclease-resistant oligoribonucleotides from protamine mRNA: the overall architecture of protamine mRNA.

Limited T1 ribonuclease digestion of the family of protamine mRNA's purified from rainbow trout testis yields several large oligoribonucleotide fragments ranging in size from 12--54 nucleotides in length. Several of these fragments purified by two dimensional gel electrophoresis contain several G residues and must represent nuclease-resistant, base-paired regions of the mRNA. Sequence analysis of these oligonucleotides by the method of Simoncsits, A., Brownlee, G.G., Brown, R.S., Rubin, J.R. and Guilley, H. (1977) Nature 269: 833-836, shows that these oligoribonucleotides arise from the 5'- and 3'-non-coding regions of the mRNA. Comparisons of the sequences of the large RNA fragment with DNA sequences obtained after cloning double-stranded protamine cDNA in the plasmids pBr322 and pmB9 show precise correspondence of a 54 nucleotide RNA fragment with positions 49--100 from the 3'-poly(A) tract and extending to within 5 nucleotides of the termination codon. Two other RNA fragments of 21 and 25 nucleotides in length arise from the 5'-non-coding region of the message and possess an AUG-sequence at their 3'-termini which is the initiation codon. The presence of distinct by homologous sequences in several sets of large RNA fragments is consistent with the presence of several closely related protamine mRNA's.

Animals↗
PubMed2005

Pre-mRNA processing enhancer (PPE) elements from intronless genes play additional roles in mRNA biogenesis than do ones from intron-containing genes.

Most mRNA-encoding genes require introns for efficient expression in high eukaryotes. However, mRNAs can efficiently accumulate in the cytoplasm without intron excision if they contain cis-acting elements such as the post-transcriptional regulatory element (PRE) of hepatitis B virus (HBV), the constitutive transport element (CTE) of Mason-Pfizer monkey virus (MPMV), or the pre-mRNA processing enhancer (PPE) of herpes simplex virus' thymidine kinase (HSV-TK) gene. We compared the activities of these viral elements, the Rev-responsive element (RRE) of the human immunodeficiency virus (HIV), and the human c-Jun gene's enhancer (CJE), an element newly identified here, to enable expression of an intronless variant of the human beta-globin gene. The PRE, PPE and CJE from naturally intronless genes, but not the CTE or RRE from intron-containing genes, significantly enhanced stability, 3' end processing and cytoplasmic accumulation. When the transcripts included the beta-globin gene's first intron, the PRE, PPE and CJE still enhanced mRNA biogenesis, in some cases without intron excision. Thus, elements enabling stability, 3' end formation and nucleocytoplasmic export, not the presence of introns or their excision per se, are necessary for mRNA biogenesis. While the CTE and RRE primarily enhance nucleocytoplasmic export, PPE-like elements from naturally intronless genes facilitate polyadenylation as well.

Active Transport, Cell Nucleus↗
PubMed2006

Dynamics of nascent mRNA folding and RNA-protein interactions: an alternative TAR RNA structure is involved in the control of HIV-1 mRNA transcription.

HIV-1 Tat protein regulates transcription elongation by binding to the 59 nt TAR RNA stem-loop structure transcribed from the HIV-1 5' long terminal repeat (5'-LTR). This established Tat-TAR interaction was used to investigate mRNA folding and RNA-protein interactions during early transcription elongation from the HIV-1 5'-LTR. Employing a new site-specific photo-cross-linking strategy to isolate transcription elongation complexes at early steps of elongation, we found that Tat interacts with HIV-1 transcripts before the formation of full-length TAR (TAR59). Analysis of RNA secondary structure by free energy profiling and ribonuclease digestion indicated that nascent transcripts folded into an alternative TAR RNA structure (TAR31), which requires only 31 nt to form and includes an analogous Tat-binding bulge structure. Functionally, TAR31, similar to TAR59, acts as a transcriptional terminator in vitro, and mRNA expression from TAR31-deficient HIV-1 5'-LTR mutant promoters is significantly decreased. Our results support a role for TAR31 in the control of HIV-1 mRNA transcription and we propose that this structure is important to stabilize the short early transcripts before the transcription complex commits for processive elongation. Overall, this study demonstrates that RNA folding during HIV-1 transcription is dynamic and that as the nascent RNA chain grows during transcription, it folds into a number of conformations that function to regulate gene expression. Finally, our results provide a new experimental strategy for studying mRNA conformation changes during transcription that can be applied to investigate the folding and function of nascent RNA structures transcribed from other promoters.

Gene Products, tat↗
PubMed2005

MicroRNA Mirn122a reduces expression of the posttranscriptionally regulated germ cell transition protein 2 (Tnp2) messenger RNA (mRNA) by mRNA cleavage.

MicroRNAs play important roles in regulating development at both transcriptional and posttranscriptional levels. Here, we report 29 microRNAs from mouse testis that are differentially expressed as the prepubertal testis differentiates to the adult testis. Using computational analyses to identify potential microRNA target mRNAs, we identify several possible male germ cell target mRNAs. One highly conserved sequence in the 3'-untranslated region (UTR) of transition protein 2 (Tnp2) mRNA, a testis-specific and posttranscriptionally regulated mRNA in postmeiotic germ cells, is complementary to Mirn122a. Mirn122a is enriched in late-stage male germ cells and is predominantly on polysomes. Mirn122a, but not another noncomplementary microRNA, inhibits the activity of a luciferase reporter construct containing the 3'-UTR of Tnp2. Site-directed mutations of Mirn122a indicate that base pairing of the 5'-region of Mirn122a to its complementary site in the 3'-UTR of Tnp2 mRNA is essential for the downregulation of luciferase activity. Real-time reverse transcription-polymerase chain reaction and ribonuclease protection assays reveal that the Mirn122a-directed decrease of the Tnp2 reporter gene activity results from mRNA cleavage. We propose that specific microRNAs, such as Mirn122a, could be involved in the posttranscriptional regulation of mRNAs such as Tnp2 in the mammalian testis.

Animals↗