In eukaryotes, regulation of mRNA translation enables a fast, localized and finely tuned expression of gene products. Within the translation process, the first stage of translation initiation is most rigorously modulated by the actions of eukaryotic initiation factors (eIFs) and their associated proteins. These 11 eIFs catalyze the joining of the tRNA, mRNA and rRNA into a functional translation complex. Their activity is influenced by a wide variety of extra- and intracellular signals, ranging from global, such as hormone signaling and unfolded proteins, to specific, such as single amino acid imbalance and iron deficiency. Their action is correspondingly comprehensive, in increasing or decreasing recruitment and translation of most cellular mRNAs, and specialized, in targeting translation of mRNAs with regulatory features such as a 5 terminal oligopyrimidine tract (TOP), upstream open reading frames (uORFs), or an internal ribosomal entry site (IRES). In mammals, two major pathways are linked to targeted mRNA translation. The target of rapamycin (TOR) kinase induces translation of TOP and perhaps other subsets of mRNAs, whereas a family of eIF2 kinases does so with mRNAs containing uORFs or an IRES. TOR targets translation of mRNAs that code for proteins involved in translation, an action compatible with its widely accepted role in regulating cellular growth. The four members of the eIF2 kinase family increase translation of mRNAs coding for stress response proteins such as transcription factors and chaperones. Though all four kinases act on one main substrate, eIF2, published literature demonstrates both common and unique effects by each kinase in response to its specific activating stress. This suggests that the activated eIF2 kinases regulate the translation of both a global and a specific set of mRNAs. Up to now, few studies have attempted to test such a hypothesis; none has been done in mammals.
eIF2alpha kinases GCN2 and PERK modulate transcription and translation of distinct sets of mRNAs in mouse liver.
No sample metadata fields
View SamplesGene expression profiling of zebrafish early eye development on 3 to 5 days post fertilization (dpf)
Integrating multiple genome annotation databases improves the interpretation of microarray gene expression data.
Specimen part
View SamplesChanges in nuclear Ca2+ homeostasis activate specific gene expression programs and are central to the acquisition and the plastic storage of memories. DREAM /KChIP proteins form heterotetramers that bind DNA and repress transcription in a Ca2+-dependent manner. Single ablation of one member of the DREAM/KChIP family may result in a mild or the absence of phenotype due to partial gene compensation. To study the function of DREAM/KChIP proteins in the brain, we used transgenic mice expressing a Ca2+-insensitive/CREB-independent dominant active mutant DREAM (daDREAM). We show that daDREAM controls the expression of several activity-dependent transcription factors including Npas4, Nr4a1, Mef2C, JunB and c-Fos, as well as the chromatin modifying enzyme Mbd4 and proteins related to actin polymerization like Arc and gelsolin. Thus, directly or through these targets, expression of daDREAM in the forebrain resulted in a complex phenotype characterized by i) impaired learning and memory, ii) loss of recurrent inhibition and enhanced LTP in the dentate gyrus without affecting Kv4-mediated potassium currents, and iii) modified spine density in DG granule neurons. Our results propose DREAM as a master-switch transcription factor regulating several activity-dependent gene expression programs to control synaptic plasticity, learning and memory.
DREAM controls the on/off switch of specific activity-dependent transcription pathways.
Specimen part
View Samples