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Biomedical subjects

J L Veyrune

Publications and source records attributed to J L Veyrune.

12 recordsLinked to original sources
PubMed2001

mRNA localization by a 145-nucleotide region of the c-fos 3'--untranslated region. Links to translation but not stability.

The presence of a localization signal in the 3'-untranslated region of c-fos mRNA was investigated by in situ hybridization and cell fractionation techniques. Cells were transfected with chimeric gene constructs in which the beta-globin coding region was used as a reporter and linked to either its own 3'-untranslated region, the c-fos 3'-untranslated region, or the c-fos 3'-untranslated region containing different deletions. Replacement of the endogenous beta-globin 3'-untranslated region by that from c-fos caused a redistribution of the transcripts so that they were recovered in cytoskeletal-bound polysomes and seen localized in the perinuclear cytoplasm. Deletion of the AU-rich instability region did not affect transcript localization, but removal of a distinct 145-nucleotide region of the 3'-untranslated region abolished it. The prevention of transcript translation by desferrioxamine led to a marked loss of transcript localization, independent of mRNA instability. The data show that the 3'-untranslated region of c-fos mRNA, as c-myc, contains a localization signal, which targets the mRNA to the perinuclear cytoskeleton. We propose that this is important to ensure efficient nuclear import of these key regulatory proteins. mRNA localization by the fos 3'-untranslated region is independent of mRNA instability, and the two are determined by different regulatory elements.

3' Untranslated Regions↗
PubMed2000

Prevalence of oral health problems in a group of individuals with Down syndrome in France.

This cross-sectional study describes oral health problems in a sample of children with Down syndrome (DS) compared with their siblings. Data were collected using the Oral Assessment - Down Syndrome questionnaire, a validated French language evaluation to be completed by the child's carer. Parents attending a national meeting anonymously answered a questionnaire for their child with DS and for the sibling closest in age and returned their replies by post. Data concerning 204 individuals with DS (103 males, 101 females; mean age 9.6 years) and 161 of their siblings (80 males, 81 females; mean age 11.8 years) were returned. The association between DS status, age, and oral health was analysed. There was a greater frequency of oral health problems in those with DS with regard to function, clinical signs, disability, and development. The prevalence of chewing problems did not improve with age, the prevalence of bleeding gums and mouth breathing increased with age, and that of tongue protrusion reduced with age. Most parents rated the general and oral health of their children with DS highly, although worse than for their siblings.

Adolescent↗
PubMed2000

Complete denture wearers: electromyography of mastication and texture perception whilst eating meat.

This study was undertaken to evaluate the sensitivity of denture wearers to different food textures and to follow masticatory pattern adaptation with variation in texture using electromyography (EMG) recordings. Nine patients with complete dentures and 9 dentate control patients without any oro-dental pathology were studied. Six different samples of beef were obtained from the same muscle by altering the state of the muscle fibres and by variation of the cooking temperature. The variations in texture were mechanically controlled. Electromyographic activity was recorded during chewing. The patients' subjective appreciation of texture was reported using a 10-cm non-structured analogue scale. The following parameters were analysed: muscle work, number of masticatory cycles, number of rejected samples, initial tenderness, overall tenderness, juiciness, and duration of chewing for each sample in the mouth. Muscle activity was less for the edentulous group, particularly that of the masseter muscles. The masticatory pattern of complete denture wearers was less adapted to each sample texture than was that of the control group. Both groups perceived differences in texture of the samples. It was concluded that although texture perception is little altered, muscular adaptation to the bolus is reduced in patients with complete dentures.

Adaptation, Physiological↗
PubMed1999

Localisation of a reporter transcript by the c-myc 3'-UTR is linked to translation.

The 3'-untranslated region of c-myc mRNA contains a perinuclear localisation signal which is sufficient to target beta-globin coding sequences. The link between perinuclear mRNA localisation and translation has been investigated using cells transfected with chimeric gene constructs in which globin reporter sequences were linked to the c-myc 3'-untranslated region and the iron-responsive element from ferritin mRNA. Iron supplementation of the medium promoted translation of the chimeric mRNA as assessed by its presence in polysomes; in situ hybridisation showed that the mRNA was localised around the nucleus. Treatment with the iron chelator desferrioxamine for 16 h prevented both translation and mRNA localisation. In controls where the expressed mRNA lacked the iron-responsive element desferrioxamine had no effect upon localisation. In contrast, arrest of on-going global translation by puromycin treatment had no effect on mRNA localisation. The data suggest that if initiation of translation of a mRNA containing the c-myc localisation signal is prevented in some way then localisation does not occur, whereas once the mRNA has been localised further translation is not required to maintain mRNA localisation.

3' Untranslated Regions↗
PubMed1999

A novel calcium signaling pathway targets the c-fos intragenic transcriptional pausing site.

In many cell types, increased intracellular calcium gives rise to a robust induction of c-fos gene expression. Here we show that in mouse Ltk(-) fibroblasts, calcium ionophore acts in synergy with either cAMP or PMA to strongly induce the endogenous c-fos gene. Run-on analysis shows that this corresponds to a substantial increase in active polymerases on downstream gene sequences, i.e. relief of an elongation block by calcium. Correspondingly a chimeric gene, in which the human metallothionein promoter is fused to the fos gene, is strongly induced by ionophore alone, unlike a c-fos promoter/beta-globin coding unit chimeric construct. Internal deletions in the hMT-fos reporter localize the intragenic calcium regulatory element to the 5' portion of intron 1, thereby confirming and extending previous in vitro mapping data. Ionophore induced cAMP response element-binding protein phosphorylation on Ser(133) without affecting the extracellular signal-regulated kinase cascade. Surprisingly, induction involved neither CaM-Ks nor calcineurin, while the calmodulin antagonist W7 activated c-fos transcription on its own. These data suggest that a novel calcium signaling pathway mediates intragenic regulation of c-fos expression via suppression of a transcriptional pause site.

1-Methyl-3-isobutylxanthine↗
PubMed1999

Development of a synthetic bolus using silicone elastomer for the study of masticatory efficiency.

STATEMENT OF PROBLEM: Masticatory efficiency has been proposed as an outcome measure for prosthetic rehabilitation. However, no standardized method is available for this type of assessment. PURPOSE: This study developed a normalized synthetic test food with reproducible physical and rheologic properties. MATERIAL AND METHODS: Two silicone putties of different hardness were studied. The texture of each putty varied by the addition of silicone oil. Rheologic characteristics of 7 samples were compared with the same properties of 5 natural food substances. RESULTS: Seven varieties of synthetic bolus were produced, each of which were of a different hardness, modulus of elasticity, and tensile strength. The natural food substances demonstrated great rheologic variability. The synthetic bolus samples exhibited a texture profile approaching that of natural foods. The principal difference between the 2 groups tested was that of the homogeneity of the silicone samples. CONCLUSION: None of the samples reproduced all the rheologic properties of the natural food substances; however, the results showed that their characteristics were sufficiently similar for the silicone samples to be suggested as a reproducible alternative for the testing of masticatory efficiency.

Bread↗
PubMed1999

[Removable prosthesis: masticatory efficiency].

The late consultation in odontology often leads to tooth extraction. This negligence, in a long term, will cause complete toothlessness. This state of invalidity will be compensated by prosthesis. The removable prosthesis is often indicated because of the cost price. It is the result of a successful therapeutics, only if it fits aesthetically and functionally, within a chewing efficiency. In a first part, we will define masticatory efficiency, as different from masticatory capacity and capability. Then, in a second part, through some experimentation, we will show how fundamental research can guide the practitioner in his prosthetics choices and assessments.

Dental Materials↗
PubMed1996

A localisation signal in the 3' untranslated region of c-myc mRNA targets c-myc mRNA and beta-globin reporter sequences to the perinuclear cytoplasm and cytoskeletal-bound polysomes.

There is increasing evidence that in mammalian cells some mRNAs are localised to specific parts of the cytoplasm and a proportion of mRNAs and polyribosomes are associated with the cytoskeleton. It has been shown previously that c-myc mRNA is present in the perinuclear cytoplasm and associated with the cytoskeleton, and that this localisation is dependent upon the 3' untranslated region of the mRNA. The present studies show that in transfected fibroblasts the c-myc 3' untranslated region is able to localise beta-globin reporter sequences to the perinuclear cytoplasm. Studies with constructs containing deletions within the 3' untranslated region identify the region between bases 194 and 280 as critical for localisation. Transfection of cells with constructs in which this region is linked to beta-globin sequences showed that it was sufficient to localise the chimaeric transcripts to the perinuclear cytoplasm and to cytoskeletal-bound polyribosomes. Transfection with constructs containing a mutated AUUUA sequence within the 194-280 base region showed that this conserved AUUUA is required for targeting of both c-myc mRNA and a chimaeric transcript of beta-globin transcripts linked to the c-myc 3' untranslated region. The region between bases 194 and 280 did not induce instability of beta-globin transcripts and the AUUUA mutation had little effect upon mRNA stability. We propose that this 86 nt region of the 3' untranslated region contains a localisation signal to target c-myc mRNA so that it is retained on cytoskeletal-bound polysomes in the perinuclear cytoplasm; a conserved AUUUA sequence appears to be a critical part of this signal.

Animals↗
PubMed1995

c-fos mRNA instability determinants present within both the coding and the 3' non coding region link the degradation of this mRNA to its translation.

The instability of oncogenic mRNA such as c-fos mRNA is controlled in cis by sequences present in both the coding and the 3' untranslated regions (3'UTR). The latter contains AU-rich elements (ARE) which, depending on the cellular context, mediate either their rapid degradation or inhibit their translation. These observations, along with the known increase of the life spans of many unstable mRNA promoted by inhibitors of protein synthesis, raise the possibility that both processes are linked. To investigate further the putative involvement of translation in both coding region and ARE-mediated rapid decay of c-fos mRNA, we designed an expression vector based on the use of the ferritin mRNA iron regulatory element (IRE). The latter structure links translation to intracellular iron concentration when inserted at the proper location within the 5'UTR. Rapid degradation of a beta-globin/c-fos 3'UTR construct was prevented by Desferrioxamine, an iron chelator, and facilitated by ferric ammonium citrate or hemin, while stability of other mRNAs not containing the IRE or the ARE were unchanged. The same conclusion was reached when the stability of a c-fos mRNA devoid of ARE was assessed in function of iron availability.

Adenine↗
PubMed1994

Nuclear import of serum response factor (SRF) requires a short amino-terminal nuclear localization sequence and is independent of the casein kinase II phosphorylation site.

Serum stimulation of resting cells is mediated at least in part at the transcriptional level by the activation of numerous genes among which c-fos constitutes a model. Serum response factor (SRF) forms a ternary complex at the c-fos serum response element (SRE) with an accessory protein p62TCF/Elk-1. Both proteins are the targets of multiple phosphorylation events and their role is still unknown in the amino terminus of SRF. While the transcriptional activation domain has been mapped between amino acids 339 and 508, the DNA-binding and the dimerization domains have been mapped to between amino acids 133-235 and 168-235, respectively, no role has been proposed for the amino-terminal portion of the molecule. We demonstrate in the present work that amino acids 95 to 100 contain a stretch of basic amino acids that are sufficient to target a reporter protein to the nucleus. Moreover, this sequence appears to be the only nuclear localization signal operating in SRF. Finally, whereas the global structure around this putative nuclear location signal is reminiscent of what is found in the SV40 T antigen, the casein kinase II phosphorylation site does not determine the rate of cyto-nuclear protein transport of this protein.

Amino Acid Sequence↗