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mRNA Localization (mrna + localization)
Selected AbstractsPostplasmic/PEM RNAs: A class of localized maternal mRNAs with multiple roles in cell polarity and development in ascidian embryosDEVELOPMENTAL DYNAMICS, Issue 7 2007François Prodon Abstract Ascidian is a good model to understand the cellular and molecular mechanisms responsible for mRNA localization with the discovery of a large family of localized maternal mRNAs, called postplasmic/PEM RNAs, which includes more than 40 members in three different ascidian species (Halocynthia roretzi, Ciona intestinalis, and C. savignyi). Among these mRNAs, two types (Type I and Type II) have been identified and show two different localization patterns from fertilization to the eight-cell stage. At the eight-cell stage, both types concentrate to a macromolecular cortical structure called CAB (for Centrosome Attracting Body) in the posterior-vegetal B4.1 blastomeres. The CAB is responsible for unequal cleavages and the partitioning of postplasmic/PEM RNAs at the posterior pole of embryos during cleavage stages. It has also been suggested that the CAB region could contain putative germ granules. In this review, we discuss recent data obtained on the distribution of Type I postplasmic/PEM RNAs from oogenesis to late development, in relation to their localization and translational control. We have first regrouped localization patterns for Type I and Type II into a comparative diagram and included all important definitions in the field. We also have made an exhaustive classification of their embryonic expression profiles (Type I or Type II), and analyzed their functions after knockdown and/or overexpression experiments and the role of the 3,-untranslated region (3,UTR) controlling both their localization and translation. Finally, we propose a speculative model integrating recent data, and we also discuss the relationship between postplasmic/PEM RNAs, posterior specification, and germ cell formation in ascidians. Developmental Dynamics 236:1698,1715, 2007. © 2007 Wiley-Liss, Inc. [source] Changes in alternative brain-derived neurotrophic factor transcript expression in the developing human prefrontal cortexEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2009Jenny Wong Abstract In this study, we determined when and through which promoter brain-derived neurotrophic factor (BDNF) transcription is regulated during the protracted period of human frontal cortex development. Using quantitative real-time polymerase chain reaction, we examined the expression of the four most abundant alternative 5, exons of the BDNF gene (exons I, II, IV, and VI) in RNA extracted from the prefrontal cortex. We found that expression of transcripts I,IX and VI,IX was highest during infancy, whereas that of transcript II,IX was lowest just after birth, slowly increasing to reach a peak in toddlers. Transcript IV,IX was significantly upregulated within the first year of life, and was maintained at this level until school age. Quantification of BDNF protein revealed that levels followed a similar developmental pattern as transcript IV,IX. In situ hybridization of mRNA in cortical sections showed the highest expression in layers V and VI for all four BDNF transcripts, whereas moderate expression was observed in layers II and III. Interestingly, although low expression of BDNF was observed in cortical layer IV, this BDNF mRNA low-zone decreased in prominence with age and showed an increase in neuronal mRNA localization. In summary, our findings show that dynamic regulation of BDNF expression occurs through differential use of alternative promoters during the development of the human prefrontal cortex, particularly in the younger age groups, when the prefrontal cortex is more plastic. [source] FMRP RNA targets: identification and validationGENES, BRAIN AND BEHAVIOR, Issue 6 2005J. C. Darnell The Fragile X Syndrome is caused by the loss of function of the FMR1 gene (Pieretti et al. 1991. Cell 66, 817,822; O'Donnell & Warren 2002. Annu Rev Neurosci 25, 315,338]. Identification of the RNA targets to which FMRP binds is a key step in understanding the function of the protein and the cellular defects caused by its absence (Darnell et al. 2004 Ment Retard Dev Disabil Res Rev 10, 49,52). Here we discuss the current understanding of FMRP as an RNA-binding protein, the different approaches that have been taken to identify FMRP RNA targets and the relevance of some of these approaches to FMRP biology. In addition, we present evidence that point mutations in the K-homology (KH)1 or KH2 domains of FMRP abrogate its polyribosome association in transfected neuroblastoma cells but that the deletion of the RGG box does not. This suggests that RNA binding by the RGG box of FMRP may mediate other aspects of cellular mRNA metabolism such as mRNA localization or that it may have a role downstream of polyribosome association. [source] The acute phase protein haptoglobin is locally expressed in arthritic and oncological tissuesINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 2 2003Mirjam B. Smeets Summary., Haptoglobin is an acute phase protein known to be highly expressed in the liver. Recently, we showed increased local arterial haptoglobin expression after flow-induced arterial remodelling and found that haptoglobin is involved in cell migration and arterial restructuring probably through accumulation of a temporary gelatin matrix. Since cell migration and matrix turnover are important features in the pathology of arthritis and cancer, we hypothesized that haptoglobin is also locally expressed in arthritic and oncological tissues. In this study, we investigated local haptoglobin expression in arthritic rats (n = 12) using semi-quantitative PCR and Western blotting, and we studied haptoglobin mRNA localization in human kidney tumours (n = 3) using in situ hybridization. The arthritic rats demonstrated an increase of haptoglobin mRNA (2.5-fold, P < 0.001) and protein (2.6-fold, P < 0.001) in the arthritic Achilles tendon. Haptoglobin protein was also increased in the arthritic ankle (2.6-fold, P < 0.001) but not in the non-arthritic knee. In human kidney tumours, tumour and stromal cells produced haptoglobin mRNA. This study shows that the liver protein haptoglobin is, in addition to the artery, also expressed in arthritic and oncological tissues that are recognized for enhanced cell migration and matrix turnover. [source] Dynamics of bidirectional transport of Arc mRNA in neuronal dendritesTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 3 2007Joseph L. Dynes Abstract The mRNA for Arc (activity-regulated cytoskeletal protein) is delivered into dendrites and localizes selectively at active synapses. Here we use a green fluorescent protein-based labeling system and confocal microscopy to define the transport kinetics of exogenously expressed mRNA from chimaeric Arc constructs (Arc/MS2 mRNA) in the dendrites of living rat neurons in culture. Arc/MS2 mRNA assembles into particles that move independently, bidirectionally, and intermittently in a fashion indicative of transport. Transport velocities range from below 6 to 65 ,m/minute, which is consistent with actin-based and microtubule-based transport, respectively. In general, orthograde translocations are longer than retrograde translocations. Rapidly translocating Arc/MS2 mRNA particles sometimes reverse direction and decrease velocity just before stopping, suggesting that local signals regulate Arc mRNA targeting movements. These observations identify several phases of Arc mRNA movement that serve as potential points for regulating Arc mRNA localization. J. Comp. Neurol. 500:433,447, 2007. © 2006 Wiley-Liss, Inc. [source] | ||||||||||