Home About us Contact
|
Home About us Contact | ||
|
|
||
Translational Regulation (translational + regulation)
Selected AbstractsTranslational regulation in cell stress and apoptosis.JOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 3 2001Roles of the eIF4E binding proteins Abstract Several mechanisms have been identified by which protein synthesis may be regulated during the response of mammalian cells to physiological stresses and conditions that induce apoptotic cell death (reviewed in Clemens et al., Cell Death and Differentiation 7, 603,615, 2000). Recent developments allow us to up-date this analysis and in this article I concentrate on one particular aspect of this regulation that has not previously been reviewed in depth in relation to apoptosis, viz. the control of the initiation of protein synthesis by eukaryotic initiation factor eIF4E and the eIF4E binding proteins (4E-BPs). Changes in the state of phosphorylation of the 4E-BPs and in the extent of their association with eIF4E occur at an early stage in the response of cells to apoptotic inducers. The review discusses the mechanisms by which these events are regulated and the significance of the changes for the control of protein synthesis, cell proliferation and cell survival. [source] Translational regulation of a novel testis-specific RNF4 transcriptMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 1 2003Raffaela Pero Abstract The RING-finger protein SNURF/RNF4, a modulator of both steroid receptor dependent and basal transcription, is expressed at very high levels in testis and at much lower levels in several other tissues. In somatic tissues, the RNF4 gene is expressed as a 3-kb transcript while an additional shorter sized transcript (1.6 kb) was found in mouse testis. In murine germ cells, RNF4 protein expression is strongly modulated during progression of spermatogonia to spermatids, with a peak in spermatocytes. The expression of 3-kb transcript correlated with protein levels in the different germ cell populations. Conversely, the 1.6-kb transcript was abundantly and specifically expressed in spermatids, in which RNF4 protein was detected at very low levels. We have then examined possible mechanisms underlying this discrepancy. Primer extension and RNase protection analyses demonstrated that the 1.6- and 3.0-kb transcripts originate from the same promoter, encode for the same protein and differ in the 3, UTR. In vitro assays showed that protein degradation is not involved in the regulation of RNF4 protein level. Finally, polysome analysis revealed that only a slight fraction of the testis-specific transcript is engaged in translation, thus providing a feasible mechanism for the quantitative differences of RNF4 mRNA and protein levels. Present results demonstrate that RNF4 short transcript is poorly translated suggesting that this mechanism could be essential for normal spermatogenesis. Mol. Reprod. Dev. 66: 1,7, 2003. © 2003 Wiley-Liss, Inc. [source] Neuronal activity and neurotrophic factors regulate GAD-65/67 mRNA and protein expression in organotypic cultures of rat visual cortexEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2003Silke Patz Abstract Environmental factors are known to regulate the molecular differentiation of neocortical interneurons. Their class-defining transmitter synthetic enzymes are the glutamic acid decarboxylases (GAD); yet, fairly little is known about the developmental regulation of transcription and translation of the GAD-65/67 isoforms. We have characterized the role of neuronal activity, neurotrophins and afferent systems for GAD-65/67 expression in visual cortex in organotypic cultures (OTC) compared with in vivo in order to identify cortex-intrinsic regulatory mechanisms. Spontaneously active OTC prepared at postnatal day 0 displayed from 10 days in vitro (DIV) onwards 12,14% GAD-65/GAD-67 neurons similar to in vivo. However, GAD-65 mRNA was higher, whereas GAD-67 protein was lower, than in vivo. During the first week neurotrophins increased whereas the Trk receptor inhibitor K252a and MEK inhibitors decreased both GAD mRNAs and proteins. After 10 DIV GAD expression no longer depended on neurotrophin signalling. Activity-deprived OTC revealed only 6% GAD-67 neurons and mRNA and protein were reduced by 50%. GAD-65 mRNA was less reduced, but protein was reduced by half, suggesting translational regulation. Upon recovery of activity GAD mRNAs, cell numbers, and both proteins quickly returned to normal and these ,adult' levels were resistant to late-onset deprivation. In 20 DIV activity-deprived OTC, only neurotrophin 4 increased GAD-65/67 mRNAs, rescued the percentage of GAD-67 neurons and increased both proteins in a TrkB-dependent manner. Activity deprivation had thus shifted the period of neurotrophin sensitivity to older ages. The results suggested neuronal activity as a major regulator differentially affecting transcription and translation of the GAD isoforms. The early presence of neuronal activity promoted the GAD expression in OTC to a neurotrophin-independent state suggesting that neurotrophins play a context-dependent role. [source] Nuclease sensitive element binding protein 1 gene disruption results in early embryonic lethalityJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 1 2006Lin Fan Abstract Nuclease sensitive element binding protein 1 (NSEP1) is a member of the EFIA/NSEP1/YB-1 family of DNA-binding proteins whose members share a cold shock domain; it has also been termed DNA-binding protein B and Y box binding protein-1 because of its recognition of transcriptional regulatory elements. In addition, NSEP1 functions in the translational regulation of renin, ferritin, and interleukin 2 transcripts, and our laboratory has reported that it plays a role in the biosynthesis of selenium-containing proteins. To test the functional importance of NSEP1 in murine embryonic development, we have utilized a clone of ES cells in which the NSEP1 gene had been disrupted by integration of a plasmid gene-trapping vector into the seventh exon. Injection of these cells into C57BL/6 blastocysts resulted in 11 high percentage chimeric mice; crosses to wild type C57BL/6 mice generated 82 F1 agouti mice, indicating germ line transmission of the ES cell clone, but genotyping showed no evidence of the disrupted allele in any of these agouti offspring even though spermatozoa from four of five tested mice contained the targeted allele. Embryos harvested after timed matings of chimeric male mice demonstrated only the wildtype allele in 27 embryos tested at E7.5, E12.5, and E18.5. These results suggest that gene targeting of NSEP1 induces a lethal phenotype in early embryos, due to either haploinsufficiency of NSEP1 or formation of a dominant negative form of the protein. In either case, these data indicate the functional importance of the NSEP1 gene in murine early embryonic development. J. Cell. Biochem. © 2006 Wiley-Liss, Inc. [source] Involvement of Gadd153 in the pathogenic action of presenilin-1 mutationsJOURNAL OF NEUROCHEMISTRY, Issue 3 2002Ollivier Milhavet Abstract Mutations in the presenilin-1 (PS1) gene cause early onset familial Alzheimer's disease (FAD) by a mechanism believed to involve perturbed endoplasmic reticulum (ER) function and altered proteolytic processing of the amyloid precursor protein. We investigated the molecular mechanisms underlying cell death and ER dysfunction in cultured cells and knock-in mice expressing FAD PS1 mutations. We report that PS1 mutations cause a marked increase in basal protein levels of the pro-apoptotic transcription factor Gadd153. PS1 mutations increase Gadd153 protein translation without affecting mRNA levels, while decreasing levels of the anti-apoptotic protein Bcl-2. Moreover, an exaggerated Gadd153 response to stress induced by ER stress agents was observed in PS1 mutant cells. Cell death in response to ER stress is enhanced by PS1 mutations, and this endangering effect is attenuated by anti-sense-mediated suppression of Gadd153 production. An abnormality in the translational regulation of Gadd153 may sensitize cells to the detrimental effects of ER stress and contribute to the pathogenic actions of PS1 mutations in FAD. [source] Premature translation of transition protein 2 mRNA causes sperm abnormalities and male infertilityMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 3 2007Khailun Tseden Abstract During mammalian spermiogenesis somatic histones are replaced at first by transition proteins, which are in turn replaced by the protamines, forming the sperm nucleoprotamines. It is believed that transition protein 2 (Tnp2) is necessary for maintaining the normal processing of protamines and, consequently, the completion of chromatin condensation. The transition protein mRNAs are stored in translationally inert messenger ribonucleoprotein particles for up to 7 days until translational activation in elongated spermatids. Substantial evidence suggests an involvement of 3,untranslated region (UTR) in the translational regulation of the Tnp2 mRNAs. In order to determine the role of Tnp2 3,UTR in translational regulation and to study whether the translational repression of Tnp2 mRNA is necessary for normal spermatid differentiation in mice, we generated transgenic mice that carry a Tnp2-hGH transgene. In this transgene, 3,UTR of Tnp2 gene was replaced by 3, 3,UTR of human growth hormone gene. In these transgenic animals, transcription and translation of Tnp2 occur simultaneously in round spermatids which is an evidence for involvement of Tnp2 3,UTR in its translation repression. Premature translation of Tnp2 mRNA caused abnormal head morphogenesis, reduced sperm motility and male infertility. These results show clearly that a strict temporal and stage-specific Tnp2 translation is necessary for the correct differentiation of round spermatids into mature spermatozoa and for male fertility. Mol. Reprod. Dev. © 2006 Wiley-Liss, Inc. [source] The mTOR target 4E-BP1 contributes to differential protein expression during normoxia and hypoxia through changes in mRNA translation efficiencyPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 5 2008Michaël G. Magagnin Abstract Hypoxia causes a rapid and sustained inhibition in mRNA translation that is characterized by both a transient phosphorylation of eukaryotic initiation factor 2-alpha (eIF2,) and by inhibition of the mRNA cap binding protein eIF4E via activation of two distinct inhibitory proteins, the mammalian target of rapamycin (mTOR) target 4E-BP1 and the eIF4E transporter 4E-T. Although the importance of eIF2, phosphorylation during hypoxia has been clearly demonstrated, there is little information on the potential relevance of eIF4E regulation. We generated HeLa cells stably expressing a short hairpin interfering RNA (shRNA) against 4E-BP1 and found that despite efficient knockdown, no significant changes occurred in the overall inhibition of mRNA translation during hypoxia. However, using a proteomics approach we identified seven proteins that were exclusively expressed in the 4E-BP1 knockdown cells during both normoxic and hypoxic conditions. Further investigation of the transcriptional and translational regulation of these genes by quantitative RT-PCR indicated that the loss of 4E-BP1 causes a significant increase in the rate of protein synthesis of S100 calcium-binding protein A4 (S100A4) and transgelin 2. These 4E-BP1 regulated proteins have previously been associated with tumor cell motility, invasion and metastasis and may thus contribute to an adverse tumor phenotype. [source] Quantitative analysis of 2,3,7,8-tetrachlorodibenzo- p -dioxin-induced proteome alterations in 5L rat hepatoma cells using isotope-coded protein labelsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 8 2006Hakan Sarioglu Abstract In an effort to contribute to a better understanding of the hepatic toxicity of the ubiquitous environmental pollutant and hepatocarcinogen 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD), a comprehensive quantitative proteome analysis was performed on 5L rat hepatoma cells exposed to 1,nM TCDD for 8,h. Changes in the abundances of individual protein species in TCDD-treated cells as compared to untreated cells were analysed using the nongel-based isotope-coded protein label (ICPL) method [Schmidt,,A., Kellermann,,J., Lottspeich,,F., Proteomics 2005, 5, 4,15]. 89 proteins were identified as up- or down-regulated by TCDD. For the majority of the altered proteins, an impact of TCDD on their abundance had not been known before. Due to the physicochemical properties or the translational regulation of a large number of the affected proteins, their alteration would have escaped detection by gel-based methods for proteome analysis and by standard mRNA expression profiling, respectively. The identified proteins with TCDD-altered abundance include several proteins implicated in cell cycle regulation, growth factor signalling and the control of apoptosis. The results thus provide new starting-points for the investigation of specific aspects of the toxicity and carcinogenicity of dioxin in liver. [source] A semi-dominant mutation in the ribosomal protein L10 gene suppresses the dwarf phenotype of the acl5 mutant in Arabidopsis thalianaTHE PLANT JOURNAL, Issue 6 2008Akihiro Imai Summary Disruption of the Arabidopsis thaliana ACAULIS5 (ACL5) gene, which has recently been shown to encode thermospermine synthase, results in a severe dwarf phenotype. A previous study showed that sac51-d, a dominant suppressor mutant of acl5-1, has a premature termination codon in an upstream open reading frame (ORF) of SAC51, which encodes a putative transcription factor, and suggested the involvement of upstream ORF-mediated translational control in ACL5 -dependent stem elongation. Here we report the identification of a gene responsible for sac52-d, another semi-dominant suppressor mutant of acl5-1. SAC52 encodes ribosomal protein L10 (RPL10A), which is highly conserved among eukaryotes and implicated in translational regulation. Transformation of acl5-1 mutants with a genomic fragment containing the sac52-d allele rescued the dwarf phenotype of acl5-1. GUS reporter activity under the control of a SAC51 promoter with its upstream ORF was higher in acl5-1 sac52-d than in acl5-1, suggesting that suppression of the acl5-1 phenotype by sac52-d is attributable, in part, to enhanced translation of certain transcripts including SAC51. We also found that a T-DNA insertion allele of SAC52/RPL10A causes lethality in the female gametophyte. [source] Expression, purification, crystallization and preliminary crystallographic analysis of the proliferation-associated protein Ebp1ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 9 2007Eva Kowalinski ErbB-3-binding protein 1 (Ebp1) is a member of the family of proliferation-associated 2G4 proteins (PA2G4s) and plays a role in cellular growth and differentiation. Ligand-induced activation of the transmembrane receptor ErbB3 leads to dissociation of Ebp1 from the receptor in a phosphorylation-dependent manner. The non-associated protein is involved in transcriptional and translational regulation in the cell. Here, the overexpression, purification, crystallization and preliminary crystallographic studies of Ebp1 from Homo sapiens are reported. Initially observed crystals were improved by serial seeding to single crystals suitable for data collection. The optimized crystals belong to the tetragonal space group P41212 or P43212 and diffracted to a resolution of 1.6,Å. [source] | |||||||||||||