Ingolia, N. T. | Search bioRxiv

bioRxiv2018

Orthogonal regulation of ferritin translation by human eIF3 and the iron response proteins

A central problem in human biology remains the discovery of causal molecular links between mutations identified in genome-wide association studies (GWAS) and their corresponding disease traits. This challenge is magnified for variants residing in non-coding regions of the genome. Single-nucleotide polymorphisms (SNPs) in the 5 untranslated region (5-UTR) of the ferritin light chain (FTL) gene that cause hyperferritinemia are thought to disrupt translation repression by altering iron regulatory protein (IRP) interactions with the FTL mRNA 5-UTR. Here, we show that human eukaryotic translation initiation factor 3 (eIF3) acts as a distinct repressor of FTL mRNA translation, and eIF3-mediated FTL repression is disrupted by a subset of SNPs in FTL that cause hyperferritinemia. These results identify a direct role for eIF3-mediated translational control in a specific human disease.

molecular biology↗

bioRxiv2017

Experience-dependent translational state defined by cell type-specific ribosome profiling

Experience-dependent neuronal activity regulates the translation of mRNA, supporting memory formation. We have developed a new method termed translating ribosome affinity purification and ribosome profiling (TRiP) which allows us to determine cell type-specific ribosome occupancy of mRNA with nucleotide resolution. Using TRiP we show that a memory-inducing experience creates a distinct translational state in mouse CA1 pyramidal cells. The experience-dependent translation state is characterized by enhanced translation of protein-coding open reading frames (ORFs) including numerous components of the actin cytoskeleton and calcium/calmodulin binding proteins, and by decreased translation of a defined subset of genes containing upstream ORFs (uORFs). Using animals heterozygous for an unphosphorylatable allele of the eukaryotic translation initiation factor 2 (eIF2), we show that dephosphorylation of eIF2 contributes significantly to the experience-dependent translation state. These observations demonstrate that TRiP is a valuable methodology for studying physiologically relevant changes in translational state in genetically defined cell types.

genomics↗